SU1665476A1 - Dc/dc voltage converter - Google Patents

Abstract

This invention relates to electrical engineering and can be used in secondary power supply sources. The goal is to increase efficiency. The device contains a transformer 1, the secondary winding of which through a rectifier 2 and filter 3 is connected to the output pins, a semiconductor switch 4, for example, a field-effect transistor with static induction, the control input of which through two additional switches 5, 6 is connected to the output of the control unit 7. When the first 5 and second 6 additional keys are unlocked and locked in, the unlocking and blocking current pulses will pass through the control input of the semiconductor key 4, and due to the capacitor 14, the current pulses will The phenomena force unlocking and locking of the semiconductor key 4. 4 Il.

Description

The invention relates to electrical engineering and can be used in the sources of secondary power supply systems of radio engineering, automation and computer technology.

The aim of the invention is to increase efficiency.

Figure 1 shows the electrical circuit of the converter; Figure 2 shows the diagrams of currents and voltages on the converter elements; Figs 3 and 4 show the electrical circuit and voltage diagrams on the elements of the control unit.

The DC converter contains a transformer 1. The secondary winding of which is connected via rectifier 2 and filter 3 with output terminals, and the primary winding is connected

To the first power output of the semiconductor key 4, for example, a field-effect transistor with a control pn junction, the control input of the semiconductor key 4 is connected to the first output pins of two additional keys, for example, to the emitters of the complementary pair of transistors 5,6 7, and the collector of the first transistor 5 is connected to the first output of the unipolar voltage source 8. The second transistor 6 of the complementary pair, shunted by the third resistor 9, is connected to the first condenser a satator 10 and a diode 11 connected to the connection point of the first 12 and second 13 resistors and the second 14 capacitor, third key 15. Block up

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5 contains an overload sensor 16, a pulse-width modulator 17, a trigger 18, an element AND 19, an element OR 20, a power amplifier 21, a matching transformer 22, a diode optocoupler 23, the first 24 and second 25 logical inverters, the third capacitor 26 and the eighth starting circuit resistor 27, switch 28, key 29, as well as fourth 30, fifth 31, sixth 32 and seventh 33 resistors.

In order to ensure reliable operation of the converter, the voltage of the unipolar voltage source and the supply voltage of the control unit 7 should appear before the input voltage of the converter and disappear after the last voltage is removed.

The input voltage is usually supplied to the converter from the mains rectifier through starting circuits.

The unipolar voltage source 8 and the power source of the control unit 7 can be implemented on the basis of an autonomous low-power voltage converter supplied from a network rectifier. In a number of cases, the source can be simultaneously used to power the control unit 7.

Consider the operation of the device in steady state. Let the first transistor (Fig. 2, a) 5 be turned on and the transistor b be turned off at some time moment c. In the interval ti -12 (Fig. 2, c), a forced unlocking of the key 4 takes place via the forcing capacitor 14 and the charge of the capacitor 10 along the circuit: the positive pole of the unipolar voltage source, the transistor 5, the gate-source of the key 4, the locking capacitor 10, resistor 12, negative pole of unipolar voltage source 8. At the end of the control pulse at the time of the TZ, the first transistor 5 is locked (Fig. 2, a) and transistor 6 is opened (Fig. 2.6). There is a quick recharge of the gate-source capacitance of the key 4 with the subsequent maintenance of the latter in the locked state due to the voltage on the capacitor 10 charged in the previous half-period (Fig. 2, d). At the same time, at the stage of the locked state of the key 4 (interval ta-14), the discharge to the zero of the capacitor 14 occurs through the resistor 13.

When the pulses of the control unit 7 (for example, the operation of protection or malfunctions of the control system 15 itself) disappear, and also when the converter is turned on, it is necessary to ensure the supply of a blocking voltage between

the control and one of the power terminals (source) of the semiconductor switch 4.

At the moment of switching on the converter of direct voltage, the control

the signal from the output of the control unit 7 enters the base of the key 15 and opens it. There is a fast charge of the capacitor 10 on the circuit: the positive pole of the unipolar voltage source 8. key 15, capacitor 10, diode 11, resistor 12, negative pole of the unipolar voltage source 8. The voltage on the capacitor 10 is applied through resistor 9 between the manager and one of the power (sources)

The 5 pins of the semiconductor key 4 and the latter turn out to be locked. Upon completion of the transient processes in the control unit 7, a signal is generated that locks the key 15. Subsequently, the converter operates as shown earlier. When the control pulses hit, the transistors 5.6 are turned off, the control unit 7 generates a signal that enables the switch 15, and a block voltage is maintained at the control input of the semi-conductor key 4. This ensures reliable locking of the semiconductor key 4, both in steady state and in emergency conditions. Block

0 control 7 is designed to generate control pulses, providing alternately turning on transistors 5 and 6 and locking key 15 in a steady state, as well as locking transistors 5

5 and 6 and the inclusion of key 15 during the initial switching on of the converter and in emergency conditions. As a rule, the control unit has a transformer output, which provides galvanic isolation of the input

0 and the output circuit of the converter, and also contains a pulse-width modulator 17, which provides stabilization of the output voltage of the converter.

Let's consider an example of block implementation

5 of control 15. It consists of an overload sensor 16, designed to protect the power transistor against overloads, a pulse width modulator (PWM) 17 that produces control pulses,

0 modulated in duration, power amplifier 21, providing amplification of control pulses to the required level, matching voltage transformer 22, providing galvanic isolation of control unit 7 and semiconductor switch 4. When turning on the DC voltage converter, switch 9 also closes the input voltage applied to start-up circuit 28 and provides charge to its capacitor

26. In the interval ti - t2 (Fig. 4, a), as long as the voltage across the resistor 27 exceeds the threshold voltage of the first logic inverter 24, the voltage at its output is zero, which sets the trigger 18 to one. This zero sets the second inverter 25 to the unit state (FIG. 4, d), which provides a high level signal at the output of the logic element OR 20 This leads to a significant increase in the emitter magnitude of the optocoupler 23. The receiving element of the optocoupler 23 through the limiting resistor 32 is connected to the first and second output pins of the key 15 (figure 1). Therefore, in the interval ti - t2 (Fig. 4, a), the key 15 is unlocked and the capacitor 10 is charged.

It should be noted that from the moment ti (Fig. 4, a) PWM 17 starts working, but control pulses at the input of power amplifier 21 are absent as long as there is a zero level at one of the inputs of the circuit And 19, and at the output winding of the matching voltage transformer 22 , one extreme output of which is connected to the emitters of transistors 5, 6 of the converter, and the other through the base resistors 30, 31 is connected to the bases of transistors 5,6.

Thus, in the interval ti - t2 (Fig. 4, a), the transistors 5,6 will turn out to be locked with zero voltage from the output winding of the matching transformer 22, and the key 4 - with the voltage of the locking capacitor 10.

Thus, the possibility of the occurrence of unacceptably large currents through key 4 and when turning on

After the end of the transient processes, the unit is set at the output of the logic inverter 24 (FIG. 4,6), the output of the logic inverter 25 (FIG. 4, d) is zero. This leads to the establishment of a low voltage level at the output of the logic element OR 20, the cessation of the current of the receiving element of the optocoupler 23 and the locking of the key 15. At the same time, at time t2 (FIG. 4, a), an enable signal is output from the output of the logic inverter 24 (FIG. 4,6) to the input element AND 19. The signal of the pulse-width modulator 17 passes through the element AND 19, is amplified to the required level by the power amplifier 21 and through the transformer 22 controls the operation of the transistors 5,6 of the converter.

It should be noted that in the absence of emergency modes, a logical unit is present at the output of the overload sensor 16. In emergency conditions (time 1h), the output of the overload sensor 16 is set to a logical zero (FIG. 4, e), which sets the trigger 18 to one state on the inverse output (FIG. 4, d), to the output of the OR 20 logic element - 5 high level signal, which, opaquely, optocoupler 23 opens the key 15 of the converter and, as mentioned above, provides the charge of the capacitor 10 and the ignition of the key 4. Simultaneously with this

0 (Fig. 2.e) the zero signal from the non-inverting output of the trigger 18 is fed to one of the inputs of the element And 19, prohibits the passage of signals of pulse-width

5 of the modulator 17 to the input of the power amplifier 31. At the output of the transformer 22, the voltage is zero and the transistors 5 and 6 of the converter turn out to be locked

The DC / DC converter allows you to dramatically increase the operating frequency of the converter to hundreds of kilohertz and higher due to the provision of the necessary steep front and increase its efficiency.

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Claims (1)

Claim 1. Inverter of constant voltage to constant, containing a transformer, the secondary winding of which 0 is connected via a rectifier and a filter with output terminals, and the primary winding is connected between the first input terminal and the first power output of the semiconductor switch, the second power output of which 5 is connected to the second input terminal, and the control input is connected to the connection point of the first output pins of two additional keys, the control inputs of which are connected from the output of the control unit, the inputs of which are connected to the output pins and the overload sensor, respectively, the second output terminal of the first additional key connected to the first output of a unipolar voltage source, and the second output output of the SECOND additional switch is connected to the first output of the first capacitor, the third switch, the first the second and second resistors, the second capacitor and the diode, and so that in order to increase efficiency, the second output of the first capacitor is connected to the second power output of the semiconductor key and to the first output terminal of the third key, The secondary input of which is connected to the input of the control unit, the second output terminal of the third key to the first output of the unipolar voltage source, the second output of which is connected through the first resistor and the second capacitor, shunted by the second resistor, to the second power supply water of the semiconductor resistor and the second capacitor, while the key, while the second output terminal of the control unit is made providing a second additional key, which shunt the formation of the unlocking third bath by the third resistor, connects the key to the input signal when the first and second emergency modes. p 377 a g s -If W about - Fig.} FIG. 2 Kjs 29 28 27 one r-i B8 3 | Ј QwQ 5/5  Fig.Z