WO2019095771A1 - Control method, control circuit and system for four-transistor buck-boost circuit - Google Patents

Abstract

Disclosed in embodiments of the present application are a control method, a control circuit and a system for a four-transistor BUCK-BOOST circuit, for use in switching a working mode of the four-transistor BUCK-BOOST circuit by changing a modulation manner on the premise of without adding an additional hardware circuit, thereby achieving the objective of improving the overall working efficiency of the circuit. The method in an embodiment of the present application comprises: obtain an actual output voltage value of a four-transistor BUCK-BOOST circuit; when the circuit is in a rated load state and the actual output voltage value is overshot, adjusting the circuit to a phase-shift control mode, a phase shift angle between Q4 and Q1 increases in the phase-shift control mode, so that an output current decreases; and in the phase-shift control mode, if the actual output voltage value overshoots as the output current further decreases, adjust the circuit to be a width adjustment control mode, the duty cycles of Q1 and Q3 decrease with an equal proportion in the width adjustment control mode, so that the output current decreases.

Description

Control method, control circuit and system for four-tube BUCK-BOOST circuit

This application claims priority to Chinese Patent Application No. 200911154589.0, entitled "Control Method, Control Circuit and System for Four-Button BUCK-BOOST Circuit", filed on November 20, 2017, with the application number of 201711154589.0 The entire contents are incorporated herein by reference.

Technical field

The present application relates to the field of BUCK-BOOST circuits, and in particular, to a control method, a control circuit and a system for a four-tube BUCK-BOOST circuit.

Background technique

A DC/DC converter is an electronic device that converts one DC voltage into another DC voltage. The four-tube BUCK-BOOST circuit is a DC/DC circuit topology widely used in recent years, and its circuit structure is shown in FIG. Among them, Q1 to Q4 are power metal oxide semiconductor field effect transistors (MOSFETs), Lo is a filter inductor, Cin is an input capacitor, and Co is an output filter capacitor. The control strategy of the circuit is flexible, and four MOSFET tubes can be combined with a variety of pulse width modulation (PWM) modulation strategies.

The technical solution adopted in the prior art is: a boundary conduction mode (BCM) + a discontinuous conduction mode (DCM) of the inductor current, and two modulation control modes are used simultaneously, as shown in FIG. 1 above. On the basis of the four-tube BUCK-BOOST circuit, as shown in FIG. 2A and FIG. 2B, when the output is overloaded, the circuit operates in the BCM mode and operates according to the PWM modulation mode shown in FIG. 2A: t0 to t3 are a complete During the switching cycle, the two MOS transistors of the same bridge arm are complementarily turned on. The initial moments Q1 and Q4 of the cycle are turned on, and the end times Q2 and Q3 of the cycle are turned off at the same time, and the inductor current is critically continuous, that is, the inductor current starts to open the next cycle immediately after the zero crossing at time t3. As the load decreases, the operating frequency of the circuit increases linearly. When the specified maximum frequency is reached, the operating frequency does not change any more. After that, the circuit enters the DCM mode and operates according to the PWM modulation mode shown in Figure 2B: t0~t4 For a complete switching cycle, the two MOS transistors of the same bridge arm are complementarily turned on. Compared with the BCM mode, at time t3, the inductor current crosses zero, then Q3 turns off, Q4 turns on, and Q2 and Q4 are turned on at the same time from t3 to t4, and the inductor current is clamped. The Q2 is turned off as the end of a cycle, after which Q1 is turned on, a new duty cycle is started, and the circuit repeats this work. By controlling the duty ratio of Q1 and Q4, the purpose of adjusting the converter voltage transfer ratio and controlling the output voltage is achieved.

However, in the existing technical solutions, additional detection and control circuits need to be added to realize switching between the two working modes of BCM and DCM, and the control is complicated and the circuit cost is increased.

Summary of the invention

The embodiment of the present application provides a control method, a control circuit and a system for a four-tube BUCK-BOOST circuit, which are used to switch the working mode of a four-tube BUCK-BOOST circuit by changing a modulation mode without additional hardware circuits. In order to achieve the purpose of improving the overall efficiency of the circuit.

A first aspect of the present application provides a method for controlling a four-tube BUCK-BOOST circuit, where the four-tube BUCK-BOOST circuit includes a power input terminal, a voltage output terminal, and four power MOSFETs, which are Q1 and Q2, respectively. Q3 and Q4, the Q1 and the Q2 are complementary conduction, the Q3 and the Q4 are complementary conduction, the input end of the Q1 is connected to the positive pole of the input power source, and the output end of the Q2 is The negative end of the power input end is connected, the output end of the Q4 is connected to the negative pole of the voltage output end, and the input end of the Q3 is connected to the positive pole of the voltage output end, comprising: acquiring the four-tube BUCK-BOOST circuit Actual output voltage value; when the four-tube BUCK-BOOST circuit is in a rated load state and the actual output voltage value is overshooted, the four-tube BUCK-BOOST circuit is adjusted to a phase shift control mode, wherein the rated load State indicates that the four-tube BUCK-BOOST circuit is in a full-load state, in which the phase shift angle between Q4 and Q1 is increased, so that the output current is reduced; , the phase shift between Q4 and Q1 The value of the output current is inversely related to the current value of the output current; in the phase shift control mode, if the actual output voltage value is overshooted, the four-tube BUCK-BOOST circuit is adjusted to the width control a mode in which a duty ratio of the Q1 and the Q3 is proportionally decreased such that the output current is decreased; and a duty ratio of the Q1 and the Q3 is proportionally changed The multiple is positively correlated with the current value of the output current. In the embodiment of the present application, no additional hardware circuit is added, and only by changing the modulation mode, the phase shift angle and the duty ratio are controlled, so that the four-tube BUCK-BOOST circuit can always work at light load/no load when the load is reduced. The state realizes the switching of the working mode of the four-tube BUCK-BOOST circuit, thereby achieving the purpose of improving the overall working efficiency of the circuit.

In a possible implementation, in a first implementation manner of the first aspect of the embodiments of the present application, when the four-tube BUCK-BOOST circuit is in a rated load state and the actual output voltage value is overshooted, Adjusting the four-tube BUCK-BOOST circuit to the phase shift control mode includes: determining a difference between the actual output voltage value and the rated output voltage value when the four-tube BUCK-BOOST circuit is in the rated load state Whether the value is greater than a preset value; if so, determining that the actual output voltage value is overshooted and adjusting the four-tube BUCK-BOOST circuit to the phase shift control mode. In this implementation manner, how to judge whether the actual output voltage value is overshooted is refined, and the steps of the embodiment of the present application are further improved.

In a possible design, in a second implementation manner of the first aspect of the embodiments of the present application, the adjusting the four-tube BUCK-BOOST circuit to the phase shift control mode includes: increasing at a preset first rate The phase shift angle of the Q4 and the Q1 such that a difference between the actual output voltage value and the rated output voltage value is less than the preset value. In this implementation manner, how to adjust the circuit to the phase shift control mode is refined, and the achievable manner of the embodiment of the present application is added.

In a possible implementation, in a third implementation manner of the first aspect of the embodiments of the present application, in the phase shift control mode, if the actual output voltage value is overshooted, the fourth Adjusting the BUCK-BOOST circuit to the widening control mode includes: when the phase shift angle reaches a maximum value, and the actual voltage output value is overshooted, the four-tube BUCK-BOOST circuit ends the phase shift control mode And adjusting to the widening control mode; when the output voltage of the four-tube BUCK-BOOST circuit is greater than the input voltage, the maximum value is the value of the duty cycle of the Q2; when the four-tube BUCK-BOOST When the output voltage of the circuit is less than the input voltage, the maximum value is the value of the duty cycle of the Q4. In this implementation manner, the specific value of the maximum value that the phase shift angle can reach under different buck boost conditions, and the trigger condition for switching from the phase shift control mode to the widened control mode are enhanced, and the present application is enhanced. The logic of the embodiment.

In a possible design, in a fourth implementation manner of the first aspect of the embodiments of the present application, the adjusting the four-tube BUCK-BOOST circuit to the adjustment control mode includes: presetting a second rate, etc. The ratio reduces the duty cycle of the Q1 and the duty cycle of the Q3 such that an error between the actual output voltage value and the nominal output voltage value is less than the preset value. In this implementation manner, how to adjust the circuit to the widening control mode is refined, and the achievable manner of the embodiment of the present application is added.

In a possible design, in a fifth implementation manner of the first aspect of the embodiment, the calculation formula of the voltage transmission ratio of the four-tube BUCK-BOOST circuit is:

The P is used to represent a voltage transmission ratio of the four-tube BUCK-BOOST circuit, the DQ1 is used to represent the duty ratio of the Q1, and the DQ2 is used to represent the duty ratio of the Q2, the DQ3 Used to represent the duty cycle of the Q3, the DQ4 is used to represent the duty cycle of the Q4. In this implementation manner, the specific calculation formula of the voltage transmission ratio in the circuit is refined, so that the operability of the embodiment of the present application is stronger.

In a possible design, in a sixth implementation manner of the first aspect of the embodiments of the present application, when the four-tube BUCK-BOOST circuit is in the rated load state, the four-tube BUCK-BOOST circuit is adopted. Full load inductor current critical continuous BCM modulation control mode. In this implementation, the working mode adopted by the circuit when the circuit is in the rated load state is described, so that the content of the embodiment of the present application is richer and easier to implement.

A second aspect of the embodiments of the present application provides a control circuit for controlling a four-tube BUCK-BOOST circuit including a power input terminal, a voltage output terminal, and four power MOSFETs: Q1, Q2 Q3 and Q4, the Q1 and the Q2 are complementary conduction, the Q3 and the Q4 are complementary conduction, the input end of the Q1 is connected to the positive pole of the input power source, and the output end of the Q2 Connected to the negative pole of the power input end, the output end of the Q4 is connected to the negative pole of the voltage output end, the input end of the Q3 is connected to the positive pole of the voltage output end, and the control circuit comprises a voltage detecting circuit and a pulse width The PWM control circuit includes: the voltage detecting circuit, configured to acquire an actual output voltage value of the four-tube BUCK-BOOST circuit; and the PWM control circuit, configured to receive an actual output voltage detected by the voltage detecting circuit And determining, when the four-tube BUCK-BOOST circuit is in a rated load state and the actual output voltage value is overshoot, outputting a first control signal of the phase-shift modulation mode to the four-tube BUCK-BOOST circuit, Controlling the four-tube BUCK-BOOST circuit to operate in a phase shift control mode, the rated load state indicating that the four-tube BUCK-BOOST circuit is in a full-load state, in the phase shift control mode, the Q4 and the Q1 The phase shift angle between the two increases, so that the output current decreases; the value of the phase shift angle between Q4 and Q1 is inversely related to the current value of the output current; in the phase shift control mode, The PWM control circuit is further configured to receive an actual output voltage value detected by the voltage detecting circuit, and determine that if the actual output voltage value overshoots, output a second control signal of the widened control mode to the a four-tube BUCK-BOOST circuit for controlling the four-tube BUCK-BOOST circuit to operate in a widening control mode, in which the duty ratios of the Q1 and the Q3 are proportionally reduced, such that The output current is decreased; a multiple of the proportional change of the duty ratios of Q1 and Q3 is positively correlated with the current value of the output current. In the embodiment of the present application, no additional hardware circuit is added, and only by changing the modulation mode, the phase shift angle and the duty ratio are controlled, so that the four-tube BUCK-BOOST circuit can always work at light load/no load when the load is reduced. The state realizes the switching of the working mode of the four-tube BUCK-BOOST circuit, thereby achieving the purpose of improving the overall working efficiency of the circuit.

In a possible design, in a first implementation manner of the second aspect of the embodiments of the present application, the PWM control circuit includes a first comparison circuit and a first adjustment circuit, including: the first comparison circuit, when When the four-tube BUCK-BOOST circuit is in the rated load state, it is configured to receive an actual voltage output value output by the voltage detecting circuit, and determine whether a difference between the actual output voltage value and a rated output voltage value is Is greater than a preset value; if yes, outputting a first trigger signal to the first adjustment circuit; the first adjustment circuit is configured to receive the first trigger signal output by the first comparison circuit, and according to the The first trigger signal outputs the first control signal to the four-tube BUCK-BOOST circuit to control the four-tube BUCK-BOOST circuit to operate in a phase shift control mode. In this implementation manner, how to judge whether the actual output voltage value is overshooted is refined, and the steps of the embodiment of the present application are further improved.

In a possible implementation, in a second implementation manner of the second aspect of the embodiments of the present application, the first control signal is used to indicate that the four-tube BUCK-BOOST circuit increases the preset first rate. Q4 and a phase shift angle of the Q1 such that a difference between the actual output voltage value and the rated output voltage value is less than the preset value. In this implementation manner, how to adjust the circuit to the phase shift control mode is refined, and the achievable manner of the embodiment of the present application is added.

In a possible implementation, in a third implementation manner of the second aspect of the embodiments of the present application, the PWM control circuit includes a second comparison circuit and a second adjustment circuit,

The second comparison circuit is configured to receive an actual voltage output value output by the voltage detecting circuit when the four-tube BUCK-BOOST circuit operates in the phase shift control mode; if the second comparison circuit is configured according to The actual voltage output value determines that when the phase shift angle reaches a maximum value, and the actual voltage output value overshoots, the second trigger signal is output to the second adjustment circuit; and the second adjustment circuit is configured to: Receiving the second trigger signal output by the second comparison circuit, and outputting the second control signal to the four-tube BUCK-BOOST circuit according to the second trigger signal to control the four-tube BUCK- The BOOST circuit ends the phase shift control mode and adjusts to the widened control mode; when the output voltage of the four-tube BUCK-BOOST circuit is greater than the input voltage, the maximum value is the value of the duty cycle of the Q2 When the output voltage of the four-tube BUCK-BOOST circuit is less than the input voltage, the maximum value is the value of the duty ratio of the Q4. In this implementation manner, the specific value of the maximum value that the phase shift angle can reach under different buck boost conditions, and the trigger condition for switching from the phase shift control mode to the widened control mode are enhanced, and the present application is enhanced. The logic of the embodiment.

In a possible design, in a fourth implementation manner of the second aspect of the embodiments of the present application, the second control signal is used to indicate that the four-tube BUCK-BOOST circuit is proportionally reduced by a preset second rate. The duty ratio of the Q1 and the duty ratio of the Q3 are small such that an error between the actual output voltage value and the rated output voltage value is less than the preset value. In this implementation manner, how to adjust the circuit to the widening control mode is refined, and the achievable manner of the embodiment of the present application is added.

In a possible design, in a fifth implementation manner of the second aspect of the embodiment of the present application, the calculation formula of the voltage transmission ratio of the four-tube BUCK-BOOST circuit is:

The P is used to represent a voltage transmission ratio of the four-tube BUCK-BOOST circuit, the DQ1 is used to represent the duty ratio of the Q1, and the DQ2 is used to represent the duty ratio of the Q2, the DQ3 Used to represent the duty cycle of the Q3, the DQ4 is used to represent the duty cycle of the Q4. In this implementation manner, the specific calculation formula of the voltage transmission ratio in the circuit is refined, so that the operability of the embodiment of the present application is stronger.

In a possible design, in a sixth implementation manner of the second aspect of the embodiment of the present application, when the four-tube BUCK-BOOST circuit is in the rated load state, the four-tube BUCK-BOOST circuit is adopted. Full load inductor current critical continuous BCM modulation control mode. In this implementation, the working mode adopted by the circuit when the circuit is in the rated load state is described, so that the content of the embodiment of the present application is richer and easier to implement.

A third aspect of the present application provides a control system for a four-tube BUCK-BOOST circuit including a power input terminal, a voltage output terminal, and four power MOSFETs Q1, Q2, Q3, and Q4. Q1 and Q2 are complementary conduction, Q3 and Q4 are complementary conduction, an input end of the Q1 is connected to a positive pole of the input power source, an output end of the Q2 is connected to the power source The output terminal of the input terminal is connected to the negative terminal of the voltage output terminal, and the input terminal of the Q3 is connected to the positive terminal of the voltage output terminal, and includes: an acquisition module, configured to acquire the four-tube BUCK-BOOST The actual output voltage value of the circuit; the mode selection module, configured to adjust the four-tube BUCK-BOOST circuit to phase shift when the four-tube BUCK-BOOST circuit is in a rated load state and the actual output voltage value is overshooted a control mode in which a phase shift angle between the Q4 and the Q1 is increased such that an output current is decreased; a value of a phase shift angle between the Q4 and Q1, The current value of the output current is inversely related; the mode The selection module is further configured to adjust the four-tube BUCK-BOOST circuit to the widening control mode when the actual output voltage value is overshooted in the phase shift control mode, in the widening control mode The duty ratios of Q1 and Q3 are reduced in proportion such that the output current is decreased; the duty ratios of Q1 and Q3 are proportionally changed, and the current value of the output current Is a positive correlation.

In a possible design, in a first implementation manner of the third aspect of the embodiments of the present application, the mode selection module specifically includes: a determining unit, when the four-tube BUCK-BOOST circuit is in a rated load state, And a method for determining whether a difference between the actual output voltage value and the rated output voltage value is greater than a preset value; the first adjusting unit, if yes, is configured to adjust the four-tube BUCK-BOOST circuit to the phase shift control mode . In this implementation manner, how to judge whether the actual output voltage value is overshooted is refined, and the steps of the embodiment of the present application are further improved.

In a possible implementation, in a second implementation manner of the third aspect of the embodiments, the first adjusting unit is specifically configured to:

The phase shift angle of the Q4 and the Q1 is increased at a preset first rate such that a difference between the actual output voltage value and the rated output voltage value is less than the preset value. In this implementation manner, how to adjust the circuit to the phase shift control mode is refined, and the achievable manner of the embodiment of the present application is added.

In a possible design, in a third implementation manner of the third aspect of the embodiment, the mode selection module specifically includes:

a second adjusting unit, when the phase shift angle reaches a maximum value, and the actual voltage output value is overshooted, used to end the phase shift control mode and adjust the phase shift control mode to the four-tube BUCK-BOOST circuit Wide control mode

When the output voltage of the four-tube BUCK-BOOST circuit is greater than the input voltage, the maximum value is a value of the duty ratio of the Q2;

When the output voltage of the four-tube BUCK-BOOST circuit is less than the input voltage, the maximum value is the value of the duty cycle of the Q4. In this implementation manner, the specific value of the maximum value that the phase shift angle can reach under different buck boost conditions, and the trigger condition for switching from the phase shift control mode to the widened control mode are enhanced, and the present application is enhanced. The logic of the embodiment.

In a possible design, in a fourth implementation manner of the third aspect of the embodiment, the second adjusting unit is specifically configured to:

Decreasing the duty ratio of the Q1 and the duty ratio of the Q3 at a preset second rate such that an error between the actual output voltage value and the rated output voltage value is less than the preset value. In this implementation manner, how to adjust the circuit to the widening control mode is refined, and the achievable manner of the embodiment of the present application is added.

In a possible design, in a fifth implementation manner of the third aspect of the embodiment of the present application, the calculation formula of the voltage transmission ratio of the four-tube BUCK-BOOST circuit is:

The P is used to represent a voltage transmission ratio of the four-tube BUCK-BOOST circuit, the DQ1 is used to represent the duty ratio of the Q1, and the DQ2 is used to represent the duty ratio of the Q2, the DQ3 Used to represent the duty cycle of the Q3, the DQ4 is used to represent the duty cycle of the Q4. In this implementation manner, the specific calculation formula of the voltage transmission ratio in the circuit is refined, so that the operability of the embodiment of the present application is stronger.

In a possible design, in a sixth implementation manner of the third aspect of the embodiments of the present application, when the four-tube BUCK-BOOST circuit is in the rated load state, the four-tube BUCK-BOOST circuit is adopted. Full load inductor current critical continuous BCM modulation control mode. In this implementation, the working mode adopted by the circuit when the circuit is in the rated load state is described, so that the content of the embodiment of the present application is richer and easier to implement.

A fourth aspect of the present application provides a chip device including a processor and a memory, the memory including instructions operable to execute a memory stored instruction to cause the chip device to perform the method of the first aspect described above .

A fifth aspect of the present application provides a computer readable storage medium having stored therein instructions that, when executed on a computer, cause the computer to perform the methods described in the above aspects.

A sixth aspect of the present application provides a computer program product comprising instructions which, when run on a computer, cause the computer to perform the methods described in the various aspects above.

As can be seen from the above technical solutions, the embodiment of the present application has the following advantages: detecting an actual output voltage value of the four-tube BUCK-BOOST circuit; when the four-tube BUCK-BOOST circuit is in a rated load state, and the actual output When the voltage value is overshoot, the four-tube BUCK-BOOST circuit is adjusted to a phase shift control mode, in which the phase shift angle between the Q4 and the Q1 is increased; In the phase control mode, if the actual output voltage value is overshooted, the four-tube BUCK-BOOST circuit is adjusted to a widening control mode, in which the Q1 and the Q3 account for The ratio is reduced in proportion. In the embodiment of the present application, no additional hardware circuit is added, and only by changing the modulation mode, the phase shift angle and the duty ratio are controlled, so that the four-tube BUCK-BOOST circuit can always work at light load/no load when the load is reduced. The state realizes the switching of the working mode of the four-tube BUCK-BOOST circuit, thereby achieving the purpose of improving the overall working efficiency of the circuit.

DRAWINGS

1 is a structural diagram of a conventional BUCK-BOOST circuit;

2A is a schematic diagram of a conventional BCM modulation control mode;

2B is a schematic diagram of a conventional DCM modulation control mode;

3 is a schematic flowchart of a possible control method of a four-tube BUCK-BOOST circuit according to an embodiment of the present application;

4 is a schematic diagram of a possible boost state BCM modulation control mode according to an embodiment of the present disclosure;

FIG. 5 is a schematic diagram of a possible boost state phase shift control mode according to an embodiment of the present application; FIG.

FIG. 6 is a schematic diagram of a possible boost state widening control mode according to an embodiment of the present application; FIG.

FIG. 7 is a schematic diagram of a possible buck modulation control mode according to an embodiment of the present application; FIG.

FIG. 8 is a schematic diagram of a possible buck phase shift control mode according to an embodiment of the present application; FIG.

FIG. 9 is a schematic diagram of a possible buck state widening control mode according to an embodiment of the present application; FIG.

FIG. 10 is a schematic structural diagram of a possible control circuit according to an embodiment of the present disclosure;

FIG. 11 is a schematic structural diagram of a control system of a possible four-tube BUCK-BOOST circuit according to an embodiment of the present application.

Detailed ways

The embodiment of the present application provides a control method, a control circuit and a system for a four-tube BUCK-BOOST circuit, which are used to switch the working mode of a four-tube BUCK-BOOST circuit by changing a modulation mode without additional hardware circuits. In order to achieve the purpose of improving the overall efficiency of the circuit.

The technical solutions in the embodiments of the present application are clearly and completely described in the following with reference to the drawings in the embodiments of the present application. It is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments obtained by a person skilled in the art based on the embodiments of the present application without creative efforts are within the scope of the present application.

The traditional four-tube BUCK-BOOST circuit control scheme can be divided into three working modes: BUCK, BUCK-BOOST, and BOOST. Among them, as shown in Figure 1, BUCK mode: Q3 remains on, Q4 remains off, Q1 and Q2 alternately conducts; BUCK-BOOST mode: Q1 and Q2 alternately turn on, Q3 and Q4 alternately turn on; BOOST mode: Q1 remains on, Q2 remains off, and Q3 and Q4 alternately conduct. Each cycle, the circuit only works in one operating mode. When the input voltage is greater than the desired output voltage, the circuit operates in BUCK mode; when the input voltage is close to the desired output voltage, the circuit operates in BUCK-BOOST mode; when the input voltage is less than the desired output At voltage, the circuit operates in BOOST mode.

In addition, the four-tube BUCK-BOOST circuit has the characteristics of flexible control strategy. The four MOS tubes Q1, Q2, Q3 and Q4 can combine a variety of Pulse Width Modulation (PWM) strategies. In the prior art, the following PWM strategies can be used:

1 continuous conduction mode (CCM): In one switching cycle, the inductor current never goes to 0. It can also be understood that the inductor never “resets”, that is, the inductor flux never returns during the switching cycle. 0, when the MOS tube is closed, there is current flowing through the coil. However, when the circuit operates in CCM mode, the zero voltage switch (ZVS) of the MOS transistor cannot be turned on, and the circuit efficiency is difficult to optimize.

2BCM mode + forced continuous conduction mode (FCCM): In the BCM mode, the controller monitors the inductor current. Once the current is detected to be equal to 0, the power switch is immediately closed. The controller always waits for the inductor current to "reset" to activate the switch. If the inductor current is high and the ramp is fairly flat, the switching period is extended. In the FCCM mode, since the low-level MOS transistor is bi-directional, when the current on the inductor is 0, the current of the inductor is reversed, and the synchronous current of the MOS transistor does not turn off, which is also a continuous conduction mode, so it is the FCCM mode. When the four-tube BUCK-BOOST circuit adopts BCM mode+FCCM mode, if the output is overloaded, the circuit works in BCM modulation control mode, and the inductor current is critically continuous, that is, the inductor current starts to open the next cycle immediately after zero crossing. As the output load decreases, the operating frequency of the circuit increases linearly. When the maximum frequency is reached, the operating frequency does not change. After that, the circuit enters the FCCM mode. At this time, the negative current of the inductor begins to increase. When the output is unloaded, The average value of the forward current is the same as the average value of the negative current. It can be seen that the circuit has a circulating current, which is not conducive to the optimization of light load efficiency.

3BCM mode + DCM mode: In DCM mode, the inductor current will always be 0 during one switching cycle, which means that the inductor is properly "reset", that is, when the MOS transistor is closed, the inductor current is zero. When the four-tube BUCK-BOOST circuit adopts BCM mode+FCCM mode, if the output is overloaded, the circuit works in BCM modulation control mode. As the output load decreases, the circuit operating frequency increases linearly. When the maximum frequency is reached, The operating frequency no longer changes, after which the circuit enters DCM mode and operates in accordance with the PWM modulation scheme shown in Figure 2B. However, in the process of switching between BCM and DCM, it is necessary to add additional detection and control circuits, and the control is complicated.

In view of this, the present application provides a control method for a four-tube BUCK-BOOST circuit for realizing the efficiency of the BUCK-BOOST circuit in a full load range without additional hardware circuitry.

Please refer to FIG. 3 , which is a flowchart of a method for controlling a four-tube BUCK-BOOST circuit provided by the present application, and the method includes:

301. Obtain an actual output voltage value of the four-tube BUCK-BOOST circuit;

Based on the circuit structure diagram of the four-tube BUCK-BOOST circuit shown in FIG. 1, the four-tube BUCK-BOOST circuit receives the input voltage Vin, and outputs a stable output voltage signal Vout after power conversion. The four-tube BUCK-BOOST circuit includes: The filter inductor Lo is coupled to the first MOS transistor Q1 between the first end of the input voltage Vin and the inductor Lo, and the second MOS transistor Q2 coupled between the first end of the inductor Lo and the ground, coupled to the inductor Lo. The third terminal is connected to the third MOS transistor Q3 between the stable output voltage Vout, and the fourth MOS transistor Q4 is coupled between the second end of the inductor Lo and the ground. Among them, Cin is the input filter capacitor, and Co is the output filter capacitor.

During the operation of the circuit, the actual output voltage value of the four-tube BUCK-BOOST circuit is obtained, that is, the value of the actual output voltage signal Vout outputted after the power conversion, and then the actual output voltage value is compared with the rated output voltage value. The difference.

302, when the four-tube BUCK-BOOST circuit is in a rated load state, determine whether the difference between the actual output voltage value and the rated output voltage value is greater than a preset value; if yes, proceed to step 303; if not, proceed to step 304;

It should be noted that the circuit load capacity can be as follows: no load, light load, heavy load and full load. The light load means that the load rate is below the first threshold in the load range of the circuit relative to the full load. In practical applications, the first threshold may be 30% or 50%, and the load of the circuit during heavy load. The rate can be an interval, such as 75% to 95%. When the four-tube BUCK-BOOST circuit is in the rated load state, the circuit works in BCM mode, realizes ZVS turn-on of all MOS tubes, and has high heavy load efficiency, and is suitable for high-power output occasions. In the present application, the rated load state can be expressed. Full load and / or heavy load state, it can be understood that in the load of the constant voltage source, when the resistance is large, the load is light, and as the resistance gradually increases, the total current is gradually reduced as the voltage is stabilized. The voltage of the resistor gradually becomes larger. For example, in a circuit, V=(R1+R2)*I. If V is constant and R2 becomes larger, I becomes smaller, so R1*I becomes smaller, and R2*I=V- R1*I becomes larger. Therefore, as the output current gradually decreases, there is a case where the actual output voltage value overshoots, that is, exceeds the rated output voltage value, so it is determined whether the difference between the actual output voltage value and the rated output voltage value is greater than a preset value. If yes, the actual output voltage value is considered to be overshoot, and step 303 is performed; if not, the actual output voltage value is considered to satisfy the condition of the rated output voltage value to be output, and step 304 is performed. It should be noted that, in practical applications, there are various ways to determine the actual output voltage value overshoot of the four-tube BUCK-BOOST circuit, except to determine whether the difference between the actual output voltage value and the rated output voltage value is greater than a preset value. In addition, the difference between the actual output voltage value and the rated output voltage value may be determined. If the difference is greater than the first preset value, the actual output voltage value is considered to be overshooted, and step 303 is performed; if the difference is less than the first A preset value is considered to be a condition that the actual output voltage value satisfies the rated output voltage value to be output, and step 304 is performed. Therefore, the specific method for determining whether the actual output voltage value is overshooted is not limited in this application.

303, adjusting the four-tube BUCK-BOOST circuit to the phase shift control mode;

When the four-tube BUCK-BOOST circuit is in the rated load state and the actual output voltage value is overshooted, the four-tube BUCK-BOOST circuit is adjusted to the phase shift control mode. In the phase shift control mode, Q4 shown in FIG. The phase shift angle between Q1 increases, and the value of the phase shift angle between Q4 and Q1 is inversely related to the current value of the output current, that is, the value of the phase shift angle between Q4 and Q1 causes the output current to decrease. In turn, the actual output voltage value is kept constant, that is, the actual output voltage value is overshooted. Wherein, adjusting the circuit to the phase shift control mode may increase the phase shift angle of Q4 and Q1 at a preset first rate, or otherwise increase the phase shift angle between Q4 and Q1 stepwise to maintain the actual output voltage value. It is stable, so this application is not limited.

304. Maintain the four-tube BUCK-BOOST circuit in BCM mode;

When the four-tube BUCK-BOOST circuit is in the rated load state and the actual output voltage value is not overshooted, the operating mode of the four-tube BUCK-BOOST circuit is unchanged, that is, maintained in the BCM mode.

305, in the phase shift control mode, determine whether the difference between the actual output voltage value and the rated output voltage value is greater than the agreed value; if yes, proceed to step 306; if not, proceed to step 307;

It can be understood that in the phase shift control mode, the phase shift angle between Q4 and Q1 is continuously increased, and the output current can be gradually reduced to maintain the constant value of the actual output voltage. However, when the phase shift between Q4 and Q1 is made, When the angle reaches the maximum value, if the output current is further reduced, and the phase shift angle between Q4 and Q1 can no longer increase, there may still be an overshoot of the actual voltage output value, so the actual output voltage value and the rated output are judged. Whether the difference between the voltage values is greater than the agreed value, if yes, the actual output voltage value is overshooted, and step 306 is performed; if not, the actual output voltage value is considered to satisfy the condition of the rated output voltage value to be output, and the steps are performed. 307. Similar to step 302, there are various ways to determine the actual output voltage value overshoot of the four-tube BUCK-BOOST circuit in practical applications, and details are not described herein.

It should be noted that the preset value in step 302 and the agreed value in step 305 may be the same value or different values, which is not limited herein.

In addition, the four-tube BUCK-BOOST circuit is a buck-boost hybrid circuit. When the four-tube BUCK-BOOST circuit is in the boost state, that is, the output voltage of the four-tube BUCK-BOOST circuit is greater than the input voltage, between Q4 and Q1. The maximum value of the phase shift angle is the value of the duty cycle of Q2; when the four-tube BUCK-BOOST circuit is in the buck state, that is, the output voltage of the four-tube BUCK-BOOST circuit is less than the input voltage, between Q4 and Q1 The maximum value of the phase shift angle is the value of the duty cycle of Q4.

306. End the phase shift control mode of the four-tube BUCK-BOOST circuit and adjust to the widening control mode;

When the phase shift angle between Q4 and Q1 reaches the maximum value and the actual voltage output value overshoots, the four-tube BUCK-BOOST circuit ends the phase shift control mode and adjusts to the widening control mode. In the widened control mode, The duty ratios of Q1 and Q3 are proportionally reduced, and the multiples of the duty ratios of Q1 and Q3 are positively correlated with the current value of the output current, so the duty ratios of Q1 and Q3 are proportionally reduced. The output current is reduced, thereby maintaining the actual output voltage value constant, that is, eliminating the overshoot condition. Wherein, adjusting the circuit to the phase shift control mode may reduce the duty ratios of Q1 and Q3 by a preset second rate, or otherwise reduce the duty ratios of Q1 and Q3 to maintain the actual output voltage. The value is stable, so the specific application is not limited.

307. Maintain the four-tube BUCK-BOOST circuit in the phase shift control mode.

When the four-tube BUCK-BOOST circuit is in the phase shift control mode and the actual output voltage value is not overshooted, the operating mode of the four-tube BUCK-BOOST circuit is unchanged, that is, maintained in the phase shift control mode.

For ease of understanding, the embodiments of the present application will be described below with reference to specific examples, including A: four tubes BUCK-BOOST in a boost state and B: four tubes BUCK-BOOST in a buck state, as follows:

A: Four tubes BUCK-BOOST are in a boost state

Take a boosted Buck-Boost converter with an input voltage of 30V, an output voltage of 60V, and a rated output current of 15A as an example.

When the circuit is fully loaded, it works according to the BCM modulation control mode. As shown in Figure 4, it is the boost state full load BCM modulation control mode waveform diagram, where t0~t3 is a complete duty cycle. At time t0, Q1 and Q4 are simultaneously When conducting, the inductor current IL increases linearly; at time t1, Q4 turns off, and the inductor current IL reaches the peak current I1; then, during the period from t1 to t2, Q1 and Q3 are simultaneously turned on, and the inductor current decreases linearly at time t2. When Q1 is turned off, the inductor current IL is reduced to I2; then, during the period from t2 to t3, Q3 and Q2 are simultaneously turned on, and the inductor current IL decreases linearly. At time t3, the inductor current IL crosses zero, and at this time, Q3 is turned off at the same time. , Q2, end a work cycle. The input voltage of the circuit is Vin=30V, the output voltage is 60V, and the required voltage transmission ratio is 2. The calculation formula of the voltage transmission ratio of the four-tube BUCK-BOOST circuit is:

The P is used to represent a voltage transmission ratio of the four-tube BUCK-BOOST circuit, the DQ1 is used to represent the duty ratio of the Q1, and the DQ2 is used to represent the duty ratio of the Q2, the DQ3 Used to represent the duty cycle of the Q3, the DQ4 is used to represent the duty cycle of the Q4. The duty ratio DQ1 of Q1 can be 0.8, and the duty ratio DQ4 of Q4 is 0.6. At this time, the voltage transmission ratio P of the circuit is DQ1/(1-DQ4)=2, because the duty ratios of Q2 and Q3 are respectively Q1. The duty cycle of Q4 is complementary, so the duty cycle DQ2 of Q2 is 0.2, and the duty cycle DQ3 of Q3 is 0.6 (the influence of dead zone is ignored in this application). Let the inductance be: L=1.12uH, the switching frequency is: fs=250kHz, calculate the peak current I1=(Vin×DQ4)/(L×fs)=64.3A, I2=I1+((Vin-Vo)× (DQ1-DQ4)) / (L × fs) = 42.9A, output current Io = 0.5 × (I1 + I2) × (DQ1 - DQ4) + 0.5 × I2 × DQ2, bringing the duty ratio and I1, I2 into The calculated output current Io=15A is calculated to match the set output current value.

When the output current decreases, the circuit starts phase shift control, maintaining the duty cycle of each MOS tube unchanged, and adjusting the output current by adjusting the phase of the Q1 and Q4 duty cycle start timing, when Q1 and Q3 are simultaneously turned off. The maximum phase shift angle is reached at all times. Figure 5 shows the waveform when the phase shift angle Da reaches the maximum value, that is, the duty value of Q2 is 0.2. t0~t3 is a complete duty cycle. At time t0, Q1 and Q4 are simultaneously turned on, and the inductor current increases linearly; At the moment Q4 is turned off, the inductor current reaches the peak current I1; then, in the period from t1 to t2, Q1 and Q3 are simultaneously turned on, the inductor current linearly decreases, and the inductor current crosses zero at time t2, at which time Q1 and Q3 are simultaneously turned off. In the subsequent period from t2 to t3, Q2 and Q4 are turned on at the same time, the inductor clamp is short-circuited, the inductor current is kept at 0A, and then the next new switching cycle is started as Q1 is turned on. Since the duty ratio of each MOS transistor remains unchanged, the voltage transfer ratio remains unchanged and the output voltage remains unchanged at 60V. Compared with the inductor current in Figure 4, the current waveform changes, maintaining the inductance L = 1.12uH, the switching frequency fs is unchanged at 250kHz, and I1 = (Vin × (DQ4-Da)) / (L × fs) = 42.9A, where Da is the maximum phase shift angle. When the output voltage of the four-tube BUCK-BOOST circuit is greater than the input voltage, the value of Da is the value of the duty cycle DQ2 of Q2, and the output current Io = 0.5 × I1 × DQ3 = 8.58A. It can be seen that as the load decreases, the phase shift angle between Q4 and Q1 increases, and the output current can be reduced, while maintaining the voltage transmission ratio unchanged, and ensuring that the output voltage is constant.

As the output current is further reduced, it is no longer possible to reduce the load current by increasing the phase shift angle. At this time, the control mode is entered, and the duty ratios of Q1 and Q3 are reduced proportionally, and the load current is reduced. The voltage transmission ratio is maintained on a constant basis. Taking the waveform shown in Figure 6 as an example, the duty cycle DQ1 of Q1 is reduced from 0.6 to 0.6. In order to maintain the voltage transmission ratio unchanged, the duty cycle DQ3 of Q3 is adjusted to 0.3, and Q2 and Q4 are still respectively. The complementary conduction with Q1 and Q3 is maintained, so the duty ratios DQ2 and DQ4 of Q2 and Q4 are respectively increased to 0.4 and 0.7, respectively. T0~t3 is a complete working cycle. At time t0, Q1 and Q4 are turned on at the same time, and the inductor current increases linearly. At time t1, Q4 turns off, the inductor current reaches the peak current I1; then in the period from t1 to t2, Q1 and Q3 At the same time, the inductor current decreases linearly. At the time t2, the inductor current crosses zero. At this time, Q1 and Q3 are turned off at the same time. In the subsequent period from t2 to t3, Q2 and Q4 are simultaneously turned on, and the inductor clamp is short-circuited. The inductor current remains at 0A without change, and then with Q1 turned on, the next new switching cycle begins. The inductance is maintained at 1.12uH and the switching frequency is unchanged at 250kHz. The peak current I1=(Vin×(DQ1-DQ3))/(L×fs)=32.1A is obtained by calculation, and the output current Io=0.5×I1×DQ3= 4.82A. It can be seen that as the load is further reduced, switching from the phase shift control to the widening control can further reduce the output current while maintaining the voltage transmission ratio unchanged, and ensuring that the output voltage is constant.

B: Four tubes BUCK-BOOST are in a buck state

Take a buck Buck-Boost converter with an input voltage Vin of 60V, an output voltage Vo of 30V, and a rated output current of 15A.

When the circuit is fully loaded, it works according to the BCM modulation control mode. As shown in Figure 7, it is the BCM modulation control mode waveform diagram of the buck state. t0~t3 is a complete duty cycle, and Q1 and Q4 are simultaneously turned on at t0. The inductor current increases linearly; at time t1, Q4 turns off and the inductor current reaches I2. Then, in the period from t1 to t2, Q1 and Q3 are turned on at the same time, the inductor current increases linearly, and Q1 turns off at time t2, and the inductor current reaches the peak current. I1; Then, in the period from t2 to t3, Q3 and Q2 are simultaneously turned on, the inductor current decreases linearly, and the inductor current crosses zero at time t3. At this time, Q3 and Q2 are turned off at the same time, and one duty cycle is ended. The input voltage of the circuit is 60V, the output voltage is 30V, and the required voltage transmission ratio is 0.5. The duty ratio DQ1 of Q1 can be 0.4, and the duty ratio DQ4 of Q4 is 0.2. At this time, the voltage transmission ratio of the circuit is DQ1/(1). -DQ4)=0.5, since the duty ratios of Q2 and Q3 are complementary to the duty ratios of Q1 and Q4, respectively, so the duty cycle DQ2 of Q2 is 0.6, and the duty ratio DQ3 of Q3 is 0.8 (the dead zone is ignored in this application). Impact). Let the inductance be L=1.12uH and the switching frequency be: fs=500kHz. By calculation, I2=(Vin×DQ4)/(L×fs)=21.4A, I1=I2+((Vin-Vo)×(DQ1) -DQ4)) / (L × fs) = 32.1A, output current = 0.5 × (I1 + I2) × (DQ1 - DQ4) + 0.5 × I1 × DQ2, DQ1, DQ4 and I1, I2 are brought into the calculation to obtain the output Current = 15A, which corresponds to the set output current value.

When the output current decreases, the circuit starts phase shift control, maintaining the duty cycle of each MOS tube unchanged, and adjusting the output current by adjusting the phase of the Q1 and Q4 duty-start time, when Q1 and Q3 are simultaneously turned on. The maximum phase shift angle is reached. Figure 8 shows the waveform when the phase shift angle Da reaches the maximum value, that is, the duty value of Q4 is 0.2. t0~t3 is a complete duty cycle. At time t0, Q1 and Q3 are simultaneously turned on, and the inductor current increases linearly; at t1 At the moment Q1 is turned off, the inductor current reaches the peak current I1; then, in the period from t1 to t2, Q2 and Q3 are simultaneously turned on, the inductor current decreases linearly, and the inductor current crosses zero at time t2, at which time Q3 is turned off, after which During the period from t2 to t3, Q2 and Q4 are simultaneously turned on, the inductor clamp is short-circuited, the inductor current is kept at 0A, and then the next new switching cycle is started as Q1 and Q3 are simultaneously turned on. Since the duty ratio of each MOS transistor remains unchanged, the voltage transfer ratio remains unchanged, and the output voltage remains unchanged at 30V. Compared with the inductor current in Figure 7, the current waveform changes, the inductance is maintained as: L=1.12uH, the switching frequency is: fs=500kHz, and I1=((Vin-Vo)× is calculated by calculation. (DQ1-DQ4+Da)) / (L × fs) = 21.4A, output current Io = 0.5 × I1 × DQ3 = 8.56A. It can be seen that as the load decreases, the phase shift angle between Q4 and Q1 increases, and the output current can be reduced, while maintaining the voltage transmission ratio unchanged, and ensuring that the output voltage is constant.

As the output current is further reduced, it is no longer possible to reduce the load current by increasing the phase shift angle. At this time, the control mode is entered, and the duty ratios of Q1 and Q3 are reduced proportionally, and the load current is reduced. The voltage transmission ratio is maintained on a constant basis. Taking the waveform shown in Figure 9 as an example, the duty cycle DQ1 of Q1 is reduced from 0.4 to 0.2. In order to maintain the voltage transmission ratio of 0.5, the duty cycle DQ3 of Q3 is adjusted to 0.4, and Q2 and Q4 are still respectively. The complementary conduction with Q1 and Q3 is maintained, so the duty ratios DQ2 and DQ4 of Q2 and Q4 are respectively increased to 0.8 and 0.6. T0~t3 is a complete working period. At time t0, Q1 and Q3 are turned on at the same time, and the inductor current increases linearly. At time t1, Q1 turns off, the inductor current reaches the peak current I1; then in the period from t1 to t2, Q2 and Q3 At the same time, the inductor current decreases linearly. At the time t2, the inductor current crosses zero. At this time, Q3 is turned off. In the subsequent period from t2 to t3, Q2 and Q4 are turned on at the same time, the inductor clamp is short-circuited, and the inductor current is kept. No change occurs for 0A, and then with the opening of Q1 and Q3, the next new switching cycle begins. Maintain the inductance is 1.12uH, the switching frequency is 500kHz, and I1=((Vin-Vo)×DQ1)/(L×fs)=10.7A is obtained by calculation. The output current Io=0.5×I1×DQ3=2.14A . It can be seen that as the load is further reduced, switching from the phase shift control to the widening control can further reduce the output current while maintaining the voltage transmission ratio unchanged, and ensuring that the output voltage is constant.

It can be seen from the above that in the embodiment of the present application, the BCM modulation control mode is adopted during full load or heavy load, and the switching timing of the MOS transistor in one cycle is accordingly: Q1, Q4 conduction → Q1, Q3 conduction → Q2, Q3 conduction Thus, the ZVS of all MOS tubes is realized, and the heavy load is ensured to be efficient; as the load is reduced, the phase shift control mode is first entered (the phase shift of the Q4 and Q1 turn-on timings is adjusted), so that the circuit enters the DCM state until Q1 and Q3. At the same time, turn off (boost mode) / turn on (buck mode), reach the maximum phase shift angle, and end the phase shift control; as the load further decreases, the phase shift control mode ends, enters the widened control mode, etc. The ratio reduces the duty ratio of Q1 and Q3, maintains the converter voltage transmission ratio constant, and increases the duty ratio of Q2 and Q4 to maintain the switching frequency. Therefore, the phase shift control and the widening control are combined in this application. The BUCK-BOOST circuit is fully loaded in the BCM state. When the load is reduced, it can always work in the DCM state to ensure the full load range is efficient. At the same time, the ZVS characteristics of the circuit are not affected, and the heavy load efficiency can be guaranteed; Working in DCM mode, not In the negative circulation, the efficiency is optimized, and the full load range is high. 3. No additional hardware circuit is added, and the phase shift angle and duty ratio are controlled. The control strategy is simple and efficient. 4. The switching frequency is constant and does not change with the load. The change, simplifying the EMI filter design.

The control method of the four-tube BUCK-BOOST circuit in the embodiment of the present application is described above. The following describes the control circuit provided by the embodiment of the present application, where the control circuit is used to control a four-tube BUCK-BOOST circuit, and the four tubes The BUCK-BOOST circuit includes a power input terminal, a voltage output terminal and four power MOSFETs Q1 Q Q4, the Q1 and the Q2 are complementary conduction, the Q3 and the Q4 are complementary conduction, and the input of the Q1 The end is connected to the positive pole of the input power source, the output end of the Q2 is connected to the negative pole of the power input end, the output end of the Q4 is connected to the negative pole of the voltage output end, and the input end of the Q3 is connected to the voltage The positive terminal of the output terminal is connected. Please refer to FIG. 10, which is a schematic structural diagram of a possible control circuit according to an embodiment of the present application. The control circuit includes a voltage detecting circuit 1001 and a PWM control circuit 1002.

The voltage detecting circuit 1001 is configured to obtain an actual output voltage value of the four-tube BUCK-BOOST circuit;

The PWM control circuit 1002 is configured to receive an actual output voltage value detected by the voltage detecting circuit, and determine that when the four-tube BUCK-BOOST circuit is in a rated load state, and the actual output voltage value is overshooted, And outputting a first control signal of the phase shift modulation mode to the four-tube BUCK-BOOST circuit to control the four-tube BUCK-BOOST circuit to operate in a phase shift control mode, in the phase shift control mode, The phase shift angle between Q4 and Q1 is increased, so that the output current is decreased; the value of the phase shift angle between Q4 and Q1 is inversely related to the current value of the output current;

In the phase shift control mode, the PWM control circuit 1002 is further configured to receive the actual output voltage value obtained by the voltage detecting circuit 1001, and determine that the actual output voltage value overshoots, then the bandwidth control is performed. a second control signal of the mode is output to the four-tube BUCK-BOOST circuit to control the four-tube BUCK-BOOST circuit to operate in a widening control mode, in the widening control mode, the Q1 and the Q3 The duty cycle is proportionally reduced such that the output current is decreased; a multiple of the proportional variation of the duty ratios of Q1 and Q3 is positively correlated with the current value of the output current.

Optionally, the PWM control circuit 1002 may specifically include a first comparison circuit 10021 and a first adjustment circuit 10022, including:

The first comparison circuit 10021 is configured to receive an actual voltage output value output by the voltage detecting circuit 1001 when the four-tube BUCK-BOOST circuit is in a rated load state, and determine the actual output voltage value and the rated output. Whether the difference between the voltage values is greater than a preset value; if so, the first trigger signal is output to the first adjustment circuit 10022;

The first adjustment circuit 10022 is configured to receive the first trigger signal output by the first comparison circuit 10021, and output the first control signal to the four-tube BUCK- according to the first trigger signal. The BOOST circuit controls the four-tube BUCK-BOOST circuit to operate in the phase shift control mode.

Optionally, the PWM control circuit 1002 may specifically include a second comparison circuit 10023 and a second adjustment circuit 10024.

The second comparison circuit 10023 is configured to receive an actual voltage output value output by the voltage detecting circuit 1001 when the four-tube BUCK-BOOST circuit operates in the phase shift control mode; if the second comparison The circuit 10023 determines, according to the actual voltage output value, when the phase shift angle reaches a maximum value, and the actual voltage output value overshoots, outputting a second trigger signal to the second adjustment circuit 10024;

The second adjustment circuit 10024 is configured to receive the second trigger signal output by the second comparison circuit 10023, and output the second control signal to the four-tube BUCK- according to the second trigger signal. a BOOST circuit to control the four-tube BUCK-BOOST circuit to end the phase shift control mode and adjust to the widened control mode;

When the output voltage of the four-tube BUCK-BOOST circuit is greater than the input voltage, the maximum value is a value of the duty ratio of the Q2;

When the output voltage of the four-tube BUCK-BOOST circuit is less than the input voltage, the maximum value is the value of the duty cycle of the Q4.

The embodiment of the present application further provides a control system of a four-tube BUCK-BOOST circuit, the four-tube BUCK-BOOST circuit includes a power input terminal, a voltage output terminal, and four power MOSFETs Q1 Q Q4, and the Q1 and the Q2 is complementary conduction, Q3 and Q4 are complementary conduction, an input end of the Q1 is connected to a positive pole of the input power source, and an output end of the Q2 is connected to a negative pole of the power input end, The output end of the Q4 is connected to the negative pole of the voltage output end, and the input end of the Q3 is connected to the positive pole of the voltage output end. Referring to FIG. 11, a schematic structural diagram of a possible control system provided by the embodiment of the present application includes :

The obtaining module 1101 is configured to obtain an actual output voltage value of the four-tube BUCK-BOOST circuit;

The mode selection module 1102 is configured to adjust the four-tube BUCK-BOOST circuit to the phase shift control mode when the four-tube BUCK-BOOST circuit is in a rated load state and the actual output voltage value is overshooted. In the phase shift control mode, the phase shift angle between the Q4 and the Q1 is increased, so that the output current is decreased; the value of the phase shift angle between the Q4 and Q1, and the current value of the output current For anti-correlation;

The mode selection module 1102 is further configured to: when the actual output voltage value is overshooted, adjust the four-tube BUCK-BOOST circuit to a widening control mode in the phase shift control mode, where the widening In the control mode, the duty ratios of Q1 and Q3 are reduced in proportion such that the output current is decreased; the duty ratios of Q1 and Q3 are proportionally changed, and the output current is The current value is positively correlated.

Optionally, the mode selection module 1102 specifically includes a determining unit 11021 and a first adjusting unit 11022:

The determining unit 11021 is configured to determine whether a difference between the actual output voltage value and the rated output voltage value is greater than a preset value when the four-tube BUCK-BOOST circuit is in a rated load state;

The first adjusting unit 11022, if yes, is configured to adjust the four-tube BUCK-BOOST circuit to the phase shift control mode.

Optionally, the first adjusting unit 11022 is specifically configured to:

The phase shift angle of the Q4 and the Q1 is increased at a preset first rate such that a difference between the actual output voltage value and the rated output voltage value is less than the preset value.

Optionally, the mode selection module 1102 may specifically include: a second adjustment unit 11023,

a second adjusting unit 11023, configured to: when the phase shift angle reaches a maximum value, and the actual voltage output value is overshoot, is used to end the phase shift control mode of the four-tube BUCK-BOOST circuit and adjust to The widening control mode;

When the output voltage of the four-tube BUCK-BOOST circuit is greater than the input voltage, the maximum value is a value of the duty ratio of the Q2;

When the output voltage of the four-tube BUCK-BOOST circuit is less than the input voltage, the maximum value is the value of the duty cycle of the Q4.

Optionally, the second adjusting unit 11023 is specifically configured to:

Decreasing the duty ratio of the Q1 and the duty ratio of the Q3 at a preset second rate such that an error between the actual output voltage value and the rated output voltage value is less than the preset value.

The embodiment of the present application further provides a chip device, where the chip device includes: a processor, a communication unit, and a memory. The memory includes instructions that are executed by the processor to cause the chip device to perform the steps performed by the control circuit in the embodiment illustrated in FIG. 3 above. The processor can be various types of processors. The communication unit may be, for example, an input/output interface, a pin or a circuit, etc., and the communication unit includes a system bus. Optionally, the chip further includes a memory, where the memory may be a memory inside the chip device, such as a register, a cache, a random access memory (RAM), an EEPROM or a FLASH, etc.; It may be a memory located outside the chip device, which may be various types of memory. The processor is coupled to a memory that can execute instructions stored in the memory to cause the chip device to perform the steps performed by the control circuit of the embodiment illustrated in Figure 3 above.

The processor according to various embodiments of the present application may be a central processing unit (CPU), a general-purpose processor, a digital signal processor (DSP), or an application specific integrated circuit (ASIC). Field Programmable Gate Array (FPGA) or other programmable logic device, transistor logic device, hardware component or any combination thereof. The processor 780 can implement or perform various exemplary logical blocks, modules and circuits described in connection with the present disclosure. The processor can also be a combination of computing functions, for example, including one or more microprocessor combinations, a combination of a DSP and a microprocessor, and the like. Alternatively, the processor may include one or more processing units.

The memory involved in various embodiments of the present application may include a volatile memory, such as a random access memory (RAM), a nonvolatile volatile random access memory (NVRAM), and a phase change random memory. Memory change RAM (PRAM), magnetoresistive random access memory (MRAM), etc., may also include non-volatile memory, such as at least one disk storage device, read-only memory (read-only memory, ROM), Electrically Erasable Programmable Read-Only Memory (EEPROM), flash memory device, such as NOR flash memory or NAND flash memory, semiconductor device, For example, Solid State Disk (SSD).

The terms "first" and "second" in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or order. It is to be understood that the data so used may be interchanged where appropriate so that the embodiments described herein can be implemented in a sequence other than what is illustrated or described herein. In addition, the terms "comprises" and "comprises" and "the" and "the" are intended to cover a non-exclusive inclusion, for example, a process, method, system, product, or device that comprises a series of steps or units is not necessarily limited to Those steps or units may include other steps or units not explicitly listed or inherent to such processes, methods, products or devices.

In each of the above embodiments of the present application, it may be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented in software, it may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions described in accordance with embodiments of the present application are generated in whole or in part. The computer can be a general purpose computer, a special purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer readable storage medium or transferred from one computer readable medium to another computer readable medium, for example, the computer instructions can be wired from a website site, computer, server or data center (for example, coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (eg infrared, wireless, microwave, etc.) to another website site, computer, server or data center. The computer readable storage medium can be any available media that can be accessed by a computer or a data storage device such as a server, data center, or the like that includes one or more available media. The usable medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a DVD), or a semiconductor medium (eg, a solid state hard disk) or the like. The above description is only a preferred embodiment of the present application, but the scope of protection of the present application is not limited thereto, and any person skilled in the art can easily think of changes or within the technical scope disclosed in the present application. Replacement should be covered by the scope of this application. Therefore, the scope of protection of the present application should be determined by the scope of protection of the claims.

Claims (24)

A method for controlling a four-tube BUCK-BOOST circuit includes a power input terminal, a voltage output terminal, and four power MOSFETs: Q1, Q2, Q3, and Q4, wherein the Q1 and the Q2 are Complementary conduction, the Q3 and the Q4 are complementary conduction, the input end of the Q1 is connected to the positive pole of the input power source, and the output end of the Q2 is connected to the negative pole of the power input end, the Q4 The output end is connected to the negative pole of the voltage output end, and the input end of the Q3 is connected to the positive pole of the voltage output end, and is characterized in that: Obtaining an actual output voltage value of the four-tube BUCK-BOOST circuit; When the four-tube BUCK-BOOST circuit is in a rated load state and the actual output voltage value is overshooted, the four-tube BUCK-BOOST circuit is adjusted to a phase shift control mode, and the rated load state represents the four tubes The BUCK-BOOST circuit is in a fully loaded state, in which the phase shift angle between Q4 and Q1 is increased, such that the output current is reduced; between Q4 and Q1 The value of the phase shift angle is inversely related to the current value of the output current; In the phase shift control mode, if the actual output voltage value is overshooted, the four-tube BUCK-BOOST circuit is adjusted to a widened control mode, and in the widened control mode, the Q1 and the The ratio of the duty ratio of Q3 is reduced such that the output current is decreased; the multiple of the ratio of the duty ratios of Q1 and Q3 is proportional to the current value of the output current. The control method according to claim 1, wherein said four-tube BUCK-BOOST circuit is adjusted when said four-tube BUCK-BOOST circuit is in a rated load state and said actual output voltage value is overshooted. The mode to phase shift control includes: When the four-tube BUCK-BOOST circuit is in the rated load state, determining whether a difference between the actual output voltage value and the rated output voltage value is greater than a preset value; If so, it is determined that the actual output voltage value is overshooted, and the four-tube BUCK-BOOST circuit is adjusted to the phase shift control mode. The control method according to claim 2, wherein the adjusting the four-tube BUCK-BOOST circuit to the phase shift control mode comprises: The phase shift angle of the Q4 and the Q1 is increased at a preset first rate such that a difference between the actual output voltage value and the rated output voltage value is less than the preset value. The control method according to claim 1, wherein in the phase shift control mode, if the actual output voltage value is overshooted, the four-tube BUCK-BOOST circuit is adjusted to a widening control. The modes include: When the phase shift angle reaches a maximum value and the actual voltage output value overshoots, the four-tube BUCK-BOOST circuit ends the phase shift control mode and adjusts to the width adjustment control mode; When the output voltage of the four-tube BUCK-BOOST circuit is greater than the input voltage, the maximum value is a value of the duty ratio of the Q2; When the output voltage of the four-tube BUCK-BOOST circuit is less than the input voltage, the maximum value is the value of the duty cycle of the Q4. The control method according to claim 4, wherein the adjusting the four-tube BUCK-BOOST circuit to the widening control mode comprises: Decreasing the duty ratio of the Q1 and the duty ratio of the Q3 at a preset second rate such that an error between the actual output voltage value and the rated output voltage value is less than the preset value. The control method according to any one of claims 1 to 5, characterized in that the calculation formula of the voltage transmission ratio of the four-tube BUCK-BOOST circuit is:

The P is used to represent a voltage transmission ratio of the four-tube BUCK-BOOST circuit, the DQ1 is used to represent the duty ratio of the Q1, and the DQ2 is used to represent the duty ratio of the Q2, the DQ3 Used to represent the duty cycle of the Q3, the DQ4 is used to represent the duty cycle of the Q4. The control method according to claim 1, wherein when the four-tube BUCK-BOOST circuit is in the rated load state, the four-tube BUCK-BOOST circuit adopts a full load inductor current critical continuous BCM modulation control mode. A control circuit for controlling a four-tube BUCK-BOOST circuit, the four-tube BUCK-BOOST circuit including a power input terminal, a voltage output terminal, and four power MOSFETs: Q1, Q2, Q3, and Q4, the Q1 and the Q2 is a complementary conduction, the Q3 and the Q4 are complementary conduction, the input end of the Q1 is connected to the positive pole of the input power source, and the output end of the Q2 is connected to the negative pole of the power input end. An output end of the Q4 is connected to a negative terminal of the voltage output end, and an input end of the Q3 is connected to a positive terminal of the voltage output end, wherein the control circuit comprises a voltage detecting circuit and a pulse width modulation PWM control circuit, including : The voltage detecting circuit is configured to obtain an actual output voltage value of the four-tube BUCK-BOOST circuit; The PWM control circuit is configured to receive an actual output voltage value detected by the voltage detecting circuit, and determine that when the four-tube BUCK-BOOST circuit is in a rated load state and the actual output voltage value is overshooted, a first control signal of the phase shift modulation mode is output to the four-tube BUCK-BOOST circuit to control the four-tube BUCK-BOOST circuit to operate in a phase shift control mode, the rated load state indicating the four-tube BUCK-BOOST The circuit is in a full load state, in which the phase shift angle between Q4 and Q1 is increased, such that the output current is decreased; the value of the phase shift angle between Q4 and Q1 And an inverse correlation relationship with the current value of the output current; In the phase shift control mode, the PWM control circuit is further configured to receive an actual output voltage value detected by the voltage detecting circuit, and determine that if the actual output voltage value overshoots, the control mode is to be widened. And outputting a second control signal to the four-tube BUCK-BOOST circuit to control the four-tube BUCK-BOOST circuit to operate in a widening control mode, in the widening control mode, the Q1 and the Q3 The duty ratio is proportionally decreased such that the output current is decreased; a multiple of the proportional variation of the duty ratios of Q1 and Q3 is positively correlated with the current value of the output current. The control circuit according to claim 8, wherein the PWM control circuit comprises a first comparison circuit and a first adjustment circuit, comprising: The first comparison circuit is configured to receive an actual voltage output value output by the voltage detecting circuit when the four-tube BUCK-BOOST circuit is in the rated load state, and determine the actual output voltage value and the rated output. Whether the difference between the voltage values is greater than a preset value; if yes, outputting the first trigger signal to the first adjustment circuit; The first adjustment circuit is configured to receive the first trigger signal output by the first comparison circuit, and output the first control signal to the four-tube BUCK-BOOST circuit according to the first trigger signal To control the four-tube BUCK-BOOST circuit to operate in the phase shift control mode. The control circuit according to claim 9, wherein the first control signal is used to instruct the four-tube BUCK-BOOST circuit to increase a phase shift angle of the Q4 and the Q1 at a preset first rate, So that the difference between the actual output voltage value and the rated output voltage value is less than the preset value. The control circuit according to claim 8, wherein said PWM control circuit comprises a second comparison circuit and a second adjustment circuit, The second comparison circuit is configured to receive an actual voltage output value output by the voltage detecting circuit when the four-tube BUCK-BOOST circuit operates in the phase shift control mode; if the second comparison circuit is configured according to The actual voltage output value determines that when the phase shift angle reaches a maximum value and the actual voltage output value overshoots, the second trigger signal is output to the second adjustment circuit; The second adjustment circuit is configured to receive the second trigger signal output by the second comparison circuit, and output the second control signal to the four-tube BUCK-BOOST circuit according to the second trigger signal Ending the phase shift control mode and adjusting to the widening control mode by controlling the four-tube BUCK-BOOST circuit; When the output voltage of the four-tube BUCK-BOOST circuit is greater than the input voltage, the maximum value is a value of the duty ratio of the Q2; When the output voltage of the four-tube BUCK-BOOST circuit is less than the input voltage, the maximum value is the value of the duty cycle of the Q4. The control circuit according to claim 11, wherein the second control signal is used to instruct the four-tube BUCK-BOOST circuit to proportionally reduce the duty ratio and the Q1 of the Q1 at a preset second rate. The duty cycle of Q3 is such that an error between the actual output voltage value and the nominal output voltage value is less than the preset value. The control circuit according to any one of claims 8 to 12, characterized in that the calculation formula of the voltage transmission ratio of the four-tube BUCK-BOOST circuit is:

The P is used to represent a voltage transmission ratio of the four-tube BUCK-BOOST circuit, the DQ1 is used to represent the duty ratio of the Q1, and the DQ2 is used to represent the duty ratio of the Q2, the DQ3 Used to represent the duty cycle of the Q3, the DQ4 is used to represent the duty cycle of the Q4. The control circuit according to claim 8, wherein when the four-tube BUCK-BOOST circuit is in the rated load state, the four-tube BUCK-BOOST circuit adopts a full load inductor current critical continuous BCM modulation control mode. A control system for a four-tube BUCK-BOOST circuit, the four-tube BUCK-BOOST circuit includes a power input terminal, a voltage output terminal, and four power MOSFETs Q1, Q2, Q3, and Q4, wherein the Q1 and the Q2 are complementary Turning on, the Q3 and the Q4 are complementary conduction, the input end of the Q1 is connected to the positive pole of the input power source, the output end of the Q2 is connected to the negative pole of the power input end, and the output of the Q4 is The end is connected to the negative pole of the voltage output end, and the input end of the Q3 is connected to the anode of the voltage output end, and is characterized in that: An obtaining module, configured to obtain an actual output voltage value of the four-tube BUCK-BOOST circuit; a mode selection module, configured to adjust the four-tube BUCK-BOOST circuit to a phase shift control mode when the four-tube BUCK-BOOST circuit is in a rated load state and the actual output voltage value is overshooted, in the shifting In the phase control mode, the phase shift angle between the Q4 and the Q1 is increased, so that the output current is decreased; the value of the phase shift angle between the Q4 and the Q1, and the current value of the output current For anti-correlation; The mode selection module is further configured to adjust the four-tube BUCK-BOOST circuit to the widening control mode when the actual output voltage value is overshooted in the phase shift control mode, in the widening control In mode, the duty ratios of Q1 and Q3 are reduced in proportion such that the output current is decreased; the duty ratios of Q1 and Q3 are proportionally changed, and the output current is The current value is positively correlated. The control system according to claim 15, wherein the mode selection module comprises: a determining unit, configured to determine whether a difference between the actual output voltage value and the rated output voltage value is greater than a preset value when the four-tube BUCK-BOOST circuit is in a rated load state; The first adjustment unit, if yes, is configured to adjust the four-tube BUCK-BOOST circuit to the phase shift control mode. The control system according to claim 16, wherein the first adjusting unit is specifically configured to: The phase shift angle of the Q4 and the Q1 is increased at a preset first rate such that a difference between the actual output voltage value and the rated output voltage value is less than the preset value. The control system according to claim 15, wherein the mode selection module comprises: a second adjusting unit, when the phase shift angle reaches a maximum value, and the actual voltage output value is overshooted, used to end the phase shift control mode and adjust the phase shift control mode to the four-tube BUCK-BOOST circuit Wide control mode When the output voltage of the four-tube BUCK-BOOST circuit is greater than the input voltage, the maximum value is a value of the duty ratio of the Q2; When the output voltage of the four-tube BUCK-BOOST circuit is less than the input voltage, the maximum value is the value of the duty cycle of the Q4. The control system according to claim 18, wherein the second adjusting unit is specifically configured to: Decreasing the duty ratio of the Q1 and the duty ratio of the Q3 at a preset second rate such that an error between the actual output voltage value and the rated output voltage value is less than the preset value. The control system according to any one of claims 15 to 19, wherein the calculation formula of the voltage transmission ratio of the four-tube BUCK-BOOST circuit is:

The P is used to represent a voltage transmission ratio of the four-tube BUCK-BOOST circuit, the DQ1 is used to represent the duty ratio of the Q1, and the DQ2 is used to represent the duty ratio of the Q2, the DQ3 Used to represent the duty cycle of the Q3, the DQ4 is used to represent the duty cycle of the Q4. The control system according to claim 15, wherein when the four-tube BUCK-BOOST circuit is in the rated load state, the four-tube BUCK-BOOST circuit adopts a full load inductor current critical continuous BCM modulation control mode. A chip device, comprising: Processor and memory; The memory includes instructions that are executed by the processor to cause the chip device to implement the method of any one of claims 1 to 7. A computer readable storage medium comprising instructions which, when run on a computer, cause the computer to perform the method of any one of claims 1 to 7. A computer program product comprising instructions which, when run on a computer, cause the computer to perform the method of any one of claims 1 to 7.

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