CN117394835A - Electronic switch drive circuit, electronic switch and control method - Google Patents

Abstract

An electronic switch drive circuit, electronic switch and control method, including an electronic switch main circuit composed of a power semiconductor disposed between an input and an output terminal, a rectifier element connected in parallel on both sides of the power semiconductor, and an electronic circuit connected to the power semiconductor. Switch drive circuit; the output end of the rectifier element is connected in series with the capacitor C1 and the power semiconductor switch Q3, and the capacitor C1 is also connected in parallel with a controllable discharge circuit. The discharge circuit is composed of a resistor R3 connected in series with the power semiconductor switch Q4; the electronic switch drive circuit includes Negative feedback circuit and quick shutdown circuit; the negative feedback circuit includes operational amplifier U1, reference voltage, and corresponding peripheral circuits, and the quick shutdown circuit includes semiconductor switches. The invention is softer when the electronic switch is turned on, absorbs energy quickly during the turn-off process, has less interference and has longer component life; a single fault has a small impact range when multiple electronic switches supply power to multiple loads, and can effectively isolate faults in a timely manner. branch.

Description

Electronic switch drive circuit, electronic switch and control method

Technical field

The present invention relates to the technical field of electronic switches, and in particular to an electronic switch drive circuit, an electronic switch and a control method.

Background technique

With the advancement of power semiconductors and microprocessors, the development and popularization of electronic switches have been accelerated. Most of the electronic switches on the market currently use the solution shown in Figure 1; the solution in Figure 1 is a typical two-way control electronic switch. Its input side (IN+ and IN-, generally connected to the power supply equipment) is connected to the power supply nearby, and the sensor The resistance is very small and can be ignored; its output side (composed of OUT+ and OUT-, generally connected to electrical equipment or batteries) is connected to the load or battery. The cable is generally long and has a certain inductive reactance, and the risk of being struck by lightning because of the long cable is also Significant increase.

In Figure 1, R1 is the current sampling resistor, used for current measurement and protection; the drive signals DRV1 and DRV2 control the power MOSFETs Q1 and Q2 to achieve on-off between the input (composed of IN+ and IN-) and the output (composed of OUT+ and OUT-) Control, where Q1 and Q2 may be one MOSFET respectively or multiple MOSFETs connected in parallel; Q1 and Q2 generally have body diodes. When used, Q1 and Q2 are connected in series in the direction of the reverse series connection of the body diodes to achieve bidirectional control of the current; D1, D2 and D3 are generally TVS or varistors (maybe multiple parallel connections), or TVS and varistors are connected in parallel to achieve over-voltage control to protect Q1 and Q2 from damage; L1 is generally an air-core inductor for decoupling. When the output (composed of OUT+ and OUT-) suffers from severe conditions such as lightning strikes, the energy flowing to Q1 and Q2 is limited to protect these two power semiconductor devices.

In recent years, electronic switches have been increasingly used. Current mainstream electronic switches often have the following shortcomings:

(1) Its conduction is often a hard switch. When the load has capacitive input, it will bring a relatively large impact (surge) current, which will cause interference problems and increase the burden on the power supply equipment. Excessive current will increase the load on the equipment. risk of damage;

(2) In applications where a power supply device with limited current is used to supply power to multiple loads through multiple electronic switches, when a short circuit occurs in a branch of the electrical device, the electronic switch does not have constant current control and is short-circuited with the power supply device. Protection mismatch often leads to interruption of the output of power supply equipment, resulting in short-term or long-term power supply interruption to all loads;

(3) The overvoltage of electronic switches comes from two aspects. One is due to the inductive reactance of the customer load or power cable (under the same circumstances, the longer the cable, the greater the inductive reactance). When the current is disconnected, there will be a voltage spike. (overvoltage) occurs; the other is that lightning strikes or other overvoltages in the use environment will cause abnormal increases in line voltage and current; the traditional solution is to connect TVS or varistor in parallel on the power semiconductor switching device of the electronic switch or on the loop. When an energy-absorbing device passively absorbs energy, its theoretical clamping voltage is generally ±20%, and -20% must be higher than the maximum working voltage. The withstand voltage of the power semiconductor switching device of the electronic switch must be greater than +20%. This will This brings up two questions:

1) Each time it is absorbed, the device will bear an impact. The interference is relatively large and the life of the energy-absorbing device is worrying.

2) The power semiconductor switching devices selected for electronic switches require higher withstand voltage.

Contents of the invention

In view of the above technical problems, this technical solution provides an electronic switch drive circuit, electronic switch and control method, which uses constant current control and active energy absorption control for the power semiconductor switching device of the electronic switch; ensuring that the conduction process of the electronic switch is more stable. Softer, the energy absorption during the turn-off process is also softer, with less interference and longer component life; when multiple electronic switches supply power to multiple loads, the impact range of a single fault is small, and the fault shunt is isolated in time; it can effectively solve the above problems .

The present invention is realized through the following technical solutions:

An electronic switch drive circuit. The electronic switch drive circuit includes: a negative feedback constant current control circuit composed of an operational amplifier as the core, and a fast protection shutdown circuit; the negative feedback constant current control circuit includes an operational amplifier, reference voltage, and corresponding peripheral circuits. The fast protection shutdown circuit includes a semiconductor switch.

A control method for an electronic switch drive circuit, which performs constant current control on the above-mentioned electronic switch drive circuit. In the negative feedback constant current control circuit, when the amplified current signal continues to be less than the reference voltage, the output signal of the operational amplifier will be positively saturated, and will eventually output a high level close to the power supply of the op amp, controlling Q1 to turn on in saturation; conversely, assuming that the output signal was in positive saturation before, when the amplified current signal is greater than the reference voltage, the output signal of the op amp It will continue to decrease from positive saturation until the current flowing through Q1 is equal to the set value. At this time, the output signal will stabilize at a certain voltage value due to the effect of negative feedback, and Q1 will be controlled to work in the amplified state; if the amplified current signal is always is greater than the reference voltage, the output signal of the op amp will eventually stabilize at a low level.

An electronic switch, including a main circuit composed of a current sampling resistor R1, a power semiconductor, an inductor L1, and a lightning protection varistor RV1 arranged between the input and output terminals; both sides of the power semiconductor are connected in parallel with rectifier elements , and an electronic switch drive circuit connected to the power semiconductor, the electronic switch drive circuit adopts the above-mentioned electronic switch drive circuit, and uses the above-mentioned electronic switch drive circuit control method to perform constant current control on the electronic switch drive circuit; the rectification The output end of the component is connected in series with the capacitor C1 and the semiconductor switch Q3. The capacitor C1 is also connected in parallel with a controllable discharge circuit. The discharge circuit is composed of a resistor R3 connected in series with the power semiconductor switch Q4.

Further, the electronic switch is used to control a DC shunt or an AC shunt; the DC shunt can be a two-way switch control or a one-way switch control.

Further, when the electronic switch is used for bidirectional switching, the power semiconductor includes power semiconductor Q1 and power semiconductor Q2. Q1 controls the forward current and Q2 controls the reverse current; the input terminals of the rectifier bridge are connected on both sides of the bidirectional switch. , the rectifier bridge output is connected in series with the capacitor and power semiconductor switch.

Further, when the electronic switch is used for a one-way switch, the power semiconductor includes a power semiconductor Q1, and a rectifier diode D2, a capacitor C1 and a semiconductor switch Q3 are connected in parallel at both ends of the one-way switch to achieve energy clamping; the rectifier diode D2, capacitor C1 and semiconductor switch Q3 are connected as follows: the anode of rectifier diode D2 is connected to the cathode of the body diode of one-way switch Q1, the cathode of rectifier diode D2 is connected to capacitor C1 and semiconductor switch Q3 in turn, and the body of semiconductor switch Q3 The anode of the diode is connected to the anode of the body diode of the one-way switch Q1.

Further, the capacitor C1 is an electrolytic capacitor.

Further, the capacitor C1 is also connected in parallel with a slow discharge resistor R2. The slow discharge resistor R2 is a resistor with a large resistance. It is used to ensure that the voltage of the capacitor C1 is basically when the power semiconductor Q3 in the discharge circuit does not conduct for a long time. Zero; when the discharge circuit is discharging normally, this resistance can be ignored.

Furthermore, between the input and output terminals, when the input may suffer lightning strikes, a decoupling inductor L2 is added to the input side, and the decoupling inductor L2 is an air-core inductor.

Further, the power semiconductors Q1 and Q2, semiconductor switch Q3, and power semiconductor switch Q4 can be MOSFET tubes, IGBT tubes, or thyristors, or any combination thereof.

A control method for an electronic switch, which controls the above-mentioned electronic switch; provides different control methods when the electronic switch appears in different working states. The specific control method is:

Working condition 1: The electronic switch is turned off when it is normally turned on. After the electronic switch Q1 or/and Q2 is turned off, the power semiconductor switch Q4 is turned off at the same time, and the semiconductor switch Q3 is turned on until the current IL1 flows through the loop. After reaching zero, after the semiconductor switch Q3 is turned off, the power semiconductor switch Q4 resumes conduction and discharges the capacitor C1; during this process, the current IL1 flowing through the loop decreases from the operating current to zero, and the electronic switch Q1 or/and The parallel voltage VD1 of Q2 increases from zero to the supply voltage; at this time, the energy of C1 clamp is: the energy stored in the working current IL1 in the inductance L1 and the inductive reactance of the output side cable;

Working condition 2: When there is a surge in the off state, when a surge voltage at the output port is detected in the off state/is greater than the protection value, the semiconductor switch Q3 needs to be turned on immediately to clamp the energy to protect the electronics. Switch Q1 or/and Q2, when the operating current IL1 increases from small to large and then decreases to zero, the semiconductor switch Q3 is turned off, and then the power semiconductor switch Q4 is turned on to discharge the capacitor C1; at this time, the energy clamped by C1 is: output The surge energy or lightning strike energy attenuated by the inductor L1 at the port;

Working condition 3: It is turned on during normal shutdown. After the electronic switch Q1 or/and Q2 changes from the off state to the on state, the operating current IL1 quickly reaches the load current and VD1 quickly drops to zero; at this time, the C1 clamp is not energy;

Working condition 4: There is a surge in the conduction state. Due to lightning strikes or surges, when the operating current IL1 is greater than the protection value, the electronic switch Q1 or/and Q2 is immediately turned off, and the semiconductor switch Q3 is always turned on, turning on the power semiconductor. Switch Q4 becomes closed; the energy clamped by C1 at this time is the energy stored in L1 and the output cable due to surges or lightning strikes.

beneficial effects

The invention proposes an electronic switch drive circuit, electronic switch and control method. Compared with the existing technology, it has the following beneficial effects:

The present invention connects the power semiconductor switching device of the electronic switch to the driving circuit and uses constant current control on the driving circuit to make the conduction process of the electronic switch softer; and actively controls the energy absorption through the energy absorption loop to make the conduction process of the electronic switch smoother. It is soft, has fast energy absorption during the turn-off process, has little interference and has a longer component life; when multiple electronic switches supply power to multiple loads, a single fault has a small impact range and can effectively isolate faulty branches in a timely manner.

The present invention uses a constant current control method to control DRV1 and DRV2. When the electrical equipment is capacitive, the electrical equipment can also be charged with a set constant current until the voltage of the electrical equipment and the power supply equipment are equal; and by During the power supply process of the electronic switch of the present invention, even if the electrical equipment is abnormal (such as short circuit), its dynamic current can be well controlled, which improves the reliability and stability of the power supply equipment, electronic switch, and electrical equipment.

The electronic switch with the constant current control function of the present invention can achieve that even if a certain electrical equipment fails (such as a short circuit), its transient and long-term impact range can be controlled within the fault branch itself and will not affect other branches. and normal use of power supply equipment.

Description of the drawings

Figure 1 is a schematic diagram of the topology scheme of electronic switches currently on the market.

Figure 2 is a schematic diagram of the electronic switch driving circuit of Embodiment 1 of the present invention.

Figure 3 is a schematic diagram of topological circuit connections in Embodiment 3 of the present invention.

Figure 4 is a schematic diagram of topological circuit connections in Embodiment 4 of the present invention.

Figure 5 is a schematic diagram of topological circuit connections in Embodiment 5 of the present invention.

Figure 6 is a schematic diagram of topological circuit connections in Embodiment 6 of the present invention.

Figure 7 is a schematic diagram of topological circuit connections in Embodiment 7 of the present invention.

Figure 8 is a schematic diagram of topological circuit connections in Embodiment 8 of the present invention.

Fig. 9 is a control method diagram of Embodiment 9 of the present invention.

Figure 10 is a table mentioned in Embodiment 9 of the present invention.

Implementation

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. The described embodiments are only some of the embodiments of the present invention, but not all of the embodiments. Without departing from the design concept of the present invention, various modifications and improvements made by ordinary people in the art to the technical solution of the present invention shall fall within the protection scope of the present invention.

Example

As shown in Figure 2, an electronic switch drive circuit is provided. The electronic switch drive circuit includes: a negative feedback constant current control circuit composed of an operational amplifier as the core, and a fast protection shutdown circuit. Among them, the power semiconductor switch Q1 controls the forward current (IR1 is positive), and the power semiconductor switch Q2 controls the reverse current (IR1 is negative).

The negative feedback constant current control circuit includes an operational amplifier, a reference voltage, and corresponding peripheral circuits. Taking the drive DRV1 of the power semiconductor switch Q1 as an example, the negative feedback constant current control circuit consists of an operational amplifier U1, a reference voltage Ref1, and peripheral circuits. The circuit consists of resistors R4 and R5, capacitors C3 and C5, and driving resistor R8. The fast protection shutdown circuit is composed of semiconductor switch Q5; when a dangerous overvoltage, overcurrent or overtemperature accident occurs, Protect1 outputs a high level, and Q5 quickly pulls the drive DRV1 of the power semiconductor switch Q1. Low.

Example

A control method for an electronic switch drive circuit, which performs constant current control on the electronic switch drive circuit described in Embodiment 1.

In the negative feedback constant current control circuit, when the amplified current signal continues to be less than the reference voltage, the output signal of the op amp will be positively saturated, and will eventually output a high level close to the op amp power supply, controlling Q1 to be saturated and conductive; conversely, Assume that the previous state of the output signal was positive saturation. When the amplified current signal is greater than the reference voltage, the output signal of the op amp will continue to decrease from positive saturation until the current flowing through Q1 is equal to the set value. At this time, the output signal will Since the effect of negative feedback is stable at a certain voltage value, Q1 is controlled to work in an amplified state; if the amplified current signal is always greater than the reference voltage, the output signal of the op amp will eventually stabilize at a low level.

Taking the constant current control of DRV1 as an example, the working principle of the constant current control circuit described in Embodiment 1 is: a negative feedback constant current control circuit composed of an op amp as the core (op amp U1, reference Ref1, resistors R4 and R5, capacitor C3 and C5, drive resistor R8), when the amplified current signal K1*IR1 continues to be less than the reference voltage Ref1 (the current flowing through the loop is less than the set value), the output DRV1 of the op amp will be positively saturated (eventually the output will be close to The high level of the op amp power supply) controls the saturated conduction of Q1. On the contrary, assuming that the previous state of DRV1 was positive saturation, when the amplified current signal K1*IR1 is greater than the reference voltage Ref1 (the current flowing through the loop is greater than the set value), the output DRV1 of the op amp will continue to decrease from positive saturation. Until the current flowing through Q1 is equal to the set value, DRV1 will stabilize at a certain voltage value due to the effect of negative feedback, controlling Q1 to work in the amplified state; if the amplified current signal K1*IR1 is always greater than Ref1, the operation The output DRV1 of the amplifier will eventually stabilize at a low level (close to the low level of the op amp power supply).

The difference between this circuit and the traditional circuit is that when the traditional circuit is turned on, it directly outputs a high level to the driver DRV1 (controlling Q1) or DRV2 (controlling Q2). Then Q1 or Q2 will immediately turn on with low impedance. At this time, if the load is capacitive property, a large impact (surge) current will be generated, which will cause great interference and easily damage the electronic switch, power supply equipment and electrical equipment; and using the method of this embodiment to control DRV1 and DRV2 can When the electrical equipment is capacitive, the electrical equipment can also be charged with a set constant current until the voltages of the electrical equipment and the power supply equipment are equal, and during the process of supplying power through the electronic switch of the present invention, the electrical equipment Abnormalities (such as short circuits), the dynamic current can also be well controlled, which is crucial to improving the reliability of power supply equipment, electronic switches, and electrical equipment.

Moreover, when the power supply capacity of the power supply equipment is limited or the OCP is sensitive, if there is no constant current control, a short circuit of a single electrical equipment will cause the output voltage of the power supply equipment to be pulled down, which will cause long or short-term interruption of adjacent electrical equipment. electricity; and an electronic switch with a constant current control function can achieve that even if a certain electrical equipment fails (such as a short circuit), its transient and long-term impact range can be controlled within the fault branch itself, affecting other branches and power supply. Equipment has no impact.

Example

As shown in Figure 3, an electronic switch with surge protection and constant current control includes a main circuit arranged between the input and output terminals, an energy absorption circuit in parallel with the main circuit, and power semiconductors in the main circuit respectively. It consists of an electronic switch drive circuit with Q1 and Q2 connected in series. The electronic switch drive circuit adopts an electronic switch drive circuit described in Embodiment 1, and uses the electronic switch drive circuit control method described in Embodiment 2 to perform constant current control on the electronic switch drive circuit.

The electronic switch is used to control the DC shunt or the AC shunt; the DC shunt can be controlled by a two-way switch or a one-way switch. When used in DC situations, INA and OUTA can be positive, or INB and OUTB is positive. This embodiment is aimed at electronic switches used for bidirectional switching. The power semiconductor includes power semiconductor switch Q1 and power semiconductor switch Q2. Q1 controls the forward current and Q2 controls the reverse current. The power semiconductor switch Q1 and the power semiconductor switch Q2 may also work. In constant current state, but the constant current time is not long, generally no more than 1 minute.

In this embodiment, the specific main circuit is composed of power semiconductor Q2, current sampling resistor R1, power semiconductor Q1, inductor L1, and lightning protection varistor RV1. The energy absorption loop is composed of rectifier bridge DB1, electrolytic capacitor C1, slow discharge resistor R2, fast discharge loop R3 and Q4, and control switch Q3.

The connection method of the energy absorption loop is: the input terminal of the rectifier bridge DB1 is connected in parallel on both sides of the power semiconductor switches Q1 and Q2. The output terminal of the rectifier bridge DB1 is connected in series with the capacitor C1 and the semiconductor switch Q3. The capacitor C1 is also connected in parallel with a rectifier bridge DB1. Controlled discharge loop, the discharge loop is composed of resistor R3 connected in series with power semiconductor switch Q4.

Capacitor C1 is also connected in parallel with a slow discharge resistor R2. The slow discharge resistor R2 is a resistor with a large resistance. It is used to ensure that the voltage of capacitor C1 is basically zero when the power semiconductor Q3 in the discharge circuit does not conduct for a long time; when the discharge circuit is normal When discharging, this resistance can be ignored.

Power semiconductor switches Q1 and Q2 can each be a semiconductor switching device, but in order to reduce losses or facilitate heat dissipation, multiple semiconductor switching devices are generally connected in parallel. Q3 and Q4 are generally single semiconductor switching devices. Power semiconductors Q1 and Q2, semiconductor switch Q3, and power semiconductor switch Q4 can be MOSFET tubes, IGBT tubes, thyristors, or any combination thereof. Capacitor C1 is an electrolytic capacitor, and the main circuit is similar to the traditional solution; the innovation of this embodiment is mainly in the driving circuit and energy absorption circuit of Q1 and Q2.

In actual use, the circuit of this embodiment can complete communication through MCU (single-chip microcomputer or processor such as ARM) and other related circuits for remote control or other control; and the power semiconductors Q1 and Q2 may also add heat sinks. The two parts described here are completed using conventional prior art. This embodiment does not make any improvements to it, and will not be elaborated here.

In this embodiment, the conditions of the surge protection circuit (energy absorption circuit) are: Q1, Q2 and Q4 are all disconnected, Q3 is closed; the energy absorption path is: output terminal OUTA → cable (with inductive reactance) → load (user Connected between OUTA and OUTB) → cable (with inductive reactance) → output terminal OUTB → inductor L1 → rectifier bridge DB1 → capacitor C1 → power semiconductor Q3 → rectifier bridge DB1 → input terminal INB → power supply → input terminal INA → output terminal OUTA, during this process the voltage of C1 will increase due to charging.

The discharge conditions of capacitor C1 are: Q3 is open or VD1 is zero and Q4 is closed; when Q4 is on, the discharge path of capacitor C1 is: capacitor C1 → resistor R3 → power semiconductor switch Q4 → capacitor C1. The reason why capacitor C1 discharges and needs to be discharged quickly is to ensure that the surge energy absorption circuit can absorb the next possible energy faster.

Example

On the basis of Embodiment 3, the positions of the circuit composed of Q3, R2, C1, R3, and Q4 are reversed; a circuit as shown in Figure 4 is obtained. The body diodes of Q3 and Q4 are oriented in the same direction as the diodes of the rectifier bridge.

In this embodiment, the conditions of the surge protection circuit (energy absorption circuit) are: Q1, Q2 and Q4 are all disconnected, Q3 is closed; the energy absorption path is: output terminal OUTA → cable (with inductive reactance) → load (user Connected between OUTA and OUTB) → cable (with inductive reactance) → output terminal OUTB → inductor L1 → rectifier bridge DB1 → power semiconductor Q3 → capacitor C1 → rectifier bridge DB1 → input terminal INB → power supply → input terminal INA → output terminal OUTA, during this process the voltage of C1 will increase due to charging.

The discharge conditions and discharge path of the capacitor C1 are the same as those in Embodiment 3.

Other structures and principles of this embodiment are the same as those of Embodiment 3, and will not be repeated here.

Example

On the basis of Embodiment 3, the positions of R3 and Q4 are reversed; a circuit as shown in Figure 5 is obtained. The body diodes of Q3 and Q4 are oriented in the same direction as the diodes of the rectifier bridge.

In this embodiment, the conditions of the surge protection circuit (energy absorption loop) and the energy absorption path are the same as in Embodiment 3.

The discharge conditions of capacitor C1 are: Q3 is open or VD1 is zero and Q4 is closed; when Q4 is on, the discharge path of capacitor C1 is: capacitor C1 → power semiconductor switch Q4 → resistor R3 → capacitor C1. The reason why capacitor C1 discharges and needs to be discharged quickly is to ensure that the surge energy absorption circuit can absorb the next possible energy faster.

Other structures and principles of this embodiment are the same as those of Embodiment 3, and will not be repeated here.

Example

On the basis of Embodiment 3, the positions of R3 and Q4 are reversed, and at the same time, the positions of the circuit composed of Q3, R2, C1, R3, and Q4 are reversed; a circuit as shown in Figure 6 is obtained. The body diodes of Q3 and Q4 are oriented in the same direction as the diodes of the rectifier bridge.

In this embodiment, the conditions of the surge protection circuit (energy absorption circuit) are: Q1, Q2 and Q4 are all disconnected, Q3 is closed; the energy absorption path is: output terminal OUTA → cable (with inductive reactance) → load (user Connected between OUTA and OUTB) → cable (with inductive reactance) → output terminal OUTB → inductor L1 → rectifier bridge DB1 → power semiconductor Q3 → capacitor C1 → rectifier bridge DB1 → input terminal INB → power supply → input terminal INA → output terminal OUTA, during this process the voltage of C1 will increase due to charging.

The discharge conditions of capacitor C1 are: Q3 is open or VD1 is zero and Q4 is closed; when Q4 is on, the discharge path of capacitor C1 is: capacitor C1 → power semiconductor switch Q4 → resistor R3 → capacitor C1. The reason why capacitor C1 discharges and needs to be discharged quickly is to ensure that the surge energy absorption circuit can absorb the next possible energy faster.

Other structures and principles of this embodiment are the same as those of Embodiment 3, and will not be repeated here.

Example

In some situations, both the input and output sides may be subject to lightning strikes and surges. In this case, based on Embodiment 3, a decoupling inductor L2 can be added between the input and output ends on the input side, as shown in the figure 7 circuit.

In this embodiment, the conditions of the surge protection circuit (energy absorption circuit) are: Q1, Q2 and Q4 are all disconnected, Q3 is closed; the energy absorption path is: output terminal OUTA → cable (with inductive reactance) → load (user Connected between OUTA and OUTB) → cable (with inductive reactance) → output terminal OUTB → inductor L1 → rectifier bridge DB1 → capacitor C1 → power semiconductor Q3 → rectifier bridge DB1 → decoupling inductor L2 → input terminal INB → power supply → Input terminal INA → output terminal OUTA, during this process the voltage of C1 will increase due to charging.

The discharge conditions and discharge path of the capacitor C1 are the same as those in Embodiment 3.

Other structures and principles of this embodiment are the same as those of Embodiment 3, and will not be repeated here.

Example

Electronic switches can be used to control DC shunts or AC shunts; the DC shunts can be controlled by two-way switches or one-way switches. When used in DC situations, INA and OUTA can be positive, or INB and OUTB is positive. In this embodiment, when the electronic switch is used as a one-way switch, the power semiconductor includes the power semiconductor Q1. In DC applications and only need to control the direction of unidirectional current, a simpler circuit as shown in Figure 8 can be used.

In this embodiment, the specific main loop is composed of a current sampling resistor R1, a power semiconductor Q1, an inductor L1, and a lightning protection varistor RV1. The energy absorption circuit is composed of rectifier diode D2, electrolytic capacitor C1, slow discharge resistor R2, fast discharge circuit R3 and Q4, and control switch Q3. The two ends of the one-way switch Q1 are connected in parallel with the rectifier diode D2, the capacitor C1 and the semiconductor switch Q3 to achieve energy clamping.

The connection method of the energy absorption loop is: the anode of the rectifier diode D2 is connected to the cathode of the body diode of the one-way switch Q1, the cathode of the rectifier diode D2 is connected to the capacitor C1 and the semiconductor switch Q3 in turn, and the anode of the body diode of the semiconductor switch Q3 is connected to the single The capacitor C1 connected to the anode of the body diode of the switch Q1 is also connected in parallel with a controllable discharge circuit. The discharge circuit is composed of a resistor R3 connected in series with the power semiconductor switch Q4.

Capacitor C1 is also connected in parallel with a slow discharge resistor R2. The slow discharge resistor R2 is a resistor with a large resistance. It is used to ensure that the voltage of capacitor C1 is basically zero when the power semiconductor Q3 in the discharge circuit does not conduct for a long time; when the discharge circuit is normal When discharging, this resistance can be ignored.

In this embodiment, the conditions of the surge protection circuit (energy absorption loop) are: Q1 and Q4 are all disconnected, Q3 is closed; the energy absorption path is: output terminal OUTA → cable (with inductive reactance) → load (user connected at Between OUTA and OUTB) → cable (with inductive reactance) → output terminal OUTB → inductor L1 → rectifier diode D2 → capacitor C1 → power semiconductor Q3 → resistor R1 → input terminal INB → power supply → input terminal INA → output terminal OUTA, During this process, the voltage of C1 will increase due to charging.

The discharge conditions of capacitor C1 are: Q3 is open or VD1 is zero and Q4 is closed; when Q4 is on, the discharge path of capacitor C1 is: capacitor C1 → resistor R3 → power semiconductor switch Q4 → capacitor C1. The reason why capacitor C1 discharges and needs to be discharged quickly is to ensure that the surge energy absorption circuit can absorb the next possible energy faster.

Other structures and principles of this embodiment are the same as those of Embodiment 3, and will not be repeated here.

Example

A method for controlling an electronic switch controls the above-mentioned electronic switch. As shown in Figure 9, (taking INA as the positive power supply, INB as the negative power supply, OUTA as the load positive, and OUTB as the load negative as an example). IL1 is the current flowing through the loop, VD1 is the voltage on TVS D1 connected in parallel with switches Q1 and Q2, and DRV1-DRV4 are the drives of each switch shown in Figure 3. Based on Figure 9, the working principles of DRV3 and DRV4 under several working conditions are detailed in the table shown in Figure 10; (DRV1-DRV4 correspond to the drive of Q1-Q4 respectively, high level indicates complete conduction, and low level indicates complete shutdown) .

Different control methods are given when the electronic switch appears in different working states. The specific control methods are:

Working condition 1: The electronic switch is turned off when it is normally turned on. After the electronic switch Q1 or/and Q2 is turned off, the power semiconductor switch Q4 is turned off at the same time, and the semiconductor switch Q3 is turned on until the current IL1 flows through the loop. After reaching zero, after the semiconductor switch Q3 is turned off, the power semiconductor switch Q4 resumes conduction and discharges the capacitor C1; during this process, the current IL1 flowing through the loop decreases from the operating current to zero, and the electronic switch Q1 or/and The parallel voltage VD1 of Q2 increases from zero to the supply voltage; at this time, the energy of C1 clamp is: the energy stored in the working current IL1 in the inductance L1 and the inductive reactance of the output side cable;

Working condition 2: When there is a surge in the off state, when a surge voltage at the output port is detected in the off state/is greater than the protection value, the semiconductor switch Q3 needs to be turned on immediately to clamp the energy to protect the electronics. Switch Q1 or/and Q2, when the operating current IL1 increases from small to large and then decreases to zero, the semiconductor switch Q3 is turned off, and then the power semiconductor switch Q4 is turned on to discharge the capacitor C1; at this time, the energy clamped by C1 is: output The surge energy or lightning strike energy attenuated by the inductor L1 at the port;

Working condition 3: It is turned on during normal shutdown. After the electronic switch Q1 or/and Q2 changes from the off state to the on state, the operating current IL1 quickly reaches the load current and VD1 quickly drops to zero; at this time, the C1 clamp is not energy;

Working condition 4: There is a surge in the conduction state. Due to lightning strikes or surges, when the operating current IL1 is greater than the protection value, the electronic switch Q1 or/and Q2 is immediately turned off, and the semiconductor switch Q3 is always turned on, turning on the power semiconductor. Switch Q4 becomes closed; the energy clamped by C1 at this time is the energy stored in L1 and the output cable due to surges or lightning strikes.

The control logic of Q3 is: Q3 is turned on (DRV3 is high level) when Q1 and Q2 are turned on or IL1 is greater than or equal to zero or VD1 is greater than the supply voltage, otherwise Q3 is turned off (DRV3 is low level).

The control logic of Q4 is: Q4 is turned on (DRV4 is high level) when Q3 is turned off or VD1 is zero, otherwise Q4 is turned off (DRV4 is low level).

Among the above working conditions, working conditions 1, 2 and 4 all require energy absorption; among these three working conditions, Q1 and Q2 are all closed.

Claims (10)

1. An electronic switch driving circuit, characterized in that: the electronic switch driving circuit includes: the negative feedback constant current control circuit is composed of an operational amplifier as a core, and a rapid protection turn-off circuit; the negative feedback constant current control circuit comprises an operational amplifier, a reference voltage and a corresponding peripheral circuit, and the rapid protection turn-off circuit comprises a semiconductor switch.

2. A control method of an electronic switch driving circuit, which performs constant current control of the electronic switch driving circuit according to claim 1, characterized in that: in the negative feedback constant current control circuit, when the amplified current signal is continuously smaller than the reference voltage, the output signal of the operational amplifier is positively saturated, and finally, a high level close to the operational amplifier for supplying power is output, and the saturated conduction of Q1 is controlled; on the contrary, assuming that the previous state of the output signal is saturated in the forward direction, when the amplified current signal is greater than the reference voltage, the output signal of the operational amplifier is continuously reduced from the saturated state until the current flowing through the Q1 is equal to the set value, and at the moment, the output signal is stabilized at a certain voltage value due to the negative feedback effect, and the Q1 is controlled to work in the amplified state; if the amplified current signal is always greater than the reference voltage, the output signal of the op-amp will eventually settle at a low level.

3. An electronic switch comprises a main loop composed of a current sampling resistor R1, a power semiconductor, an inductor L1 and a lightning protection piezoresistor RV1, wherein the current sampling resistor R1 is arranged between an input end and an output end; the method is characterized in that: the two sides of the power semiconductor are connected with rectifying elements in parallel, and an electronic switch driving circuit connected with the power semiconductor in series is adopted to perform constant current control on the electronic switch driving circuit by adopting the electronic switch driving circuit according to claim 1 and adopting the control method of the electronic switch driving circuit according to claim 2; the output end of the rectifying element is connected with a capacitor C1 and a semiconductor switch Q3 in series, the capacitor C1 is also connected with a controllable discharging loop in parallel, and the discharging loop is formed by connecting a resistor R3 with a power semiconductor switch Q4 in series.

4. An electronic switch according to claim 3, wherein: the electronic switch is used for controlling the direct current shunt or controlling the alternating current shunt; the direct current shunt can be controlled by a bidirectional switch or a unidirectional switch.

5. An electronic switch according to claim 3, wherein: when the electronic switch is used for bidirectional switching, the power semiconductor comprises a power semiconductor Q1 and a power semiconductor Q2, wherein the power semiconductor Q1 controls forward current, and the power semiconductor Q2 controls reverse current; and the two sides of the bidirectional switch are connected with the input end of the rectifier bridge, and the output of the rectifier bridge is connected with the capacitor and the power semiconductor switch in series and then is connected with the capacitor and the power semiconductor switch.

6. An electronic switch as claimed in claim 5, wherein: when the electronic switch is used for a unidirectional switch, the power semiconductor comprises a power semiconductor Q1, and two ends of the unidirectional switch are connected with a rectifier diode, a capacitor and a semiconductor switch in parallel to realize energy clamping; the connection mode of the rectifier diode, the capacitor and the semiconductor switch is as follows: the anode of the rectifying diode is connected with the cathode of the body diode of the unidirectional switch, the cathode of the rectifying diode is sequentially connected with the capacitor and the semiconductor switch, and the anode of the body diode of the semiconductor switch is connected with the anode of the body diode of the unidirectional switch.

7. An electronic switch according to claim 3, wherein: the capacitor C1 is an electrolytic capacitor; the capacitor C1 is also connected in parallel with a slow discharging resistor R2, and the slow discharging resistor R2 is a resistor with a very large resistance value and is used for ensuring that the voltage of the capacitor C1 is basically zero when the power semiconductor Q3 in a discharging loop is not conducted for a long time; when the discharge loop is discharging normally, the resistance can be ignored.

8. An electronic switch according to claim 3, wherein: between the input and output ends, a decoupling inductance L2 is added on the input side in the case that the input is also possibly struck by lightning.

9. An electronic switch according to any one of claims 3-8, characterized in that: the power semiconductors Q1 and Q2, the semiconductor switch Q3 and the power semiconductor switch Q4 can be MOSFET tubes or IGBT tubes or thyristors or any combination thereof.

10. A control method of an electronic switch, controlling an electronic switch according to claims 3-9; the method is characterized in that: different control methods are provided aiming at different working states of the electronic switch, and the specific control methods are as follows:

working condition 1: the electronic switch is turned off during normal conduction, after the electronic switch Q1 or/and Q2 is turned off, the power semiconductor switch Q4 is turned off at the same time, the semiconductor switch Q3 is turned on until the current IL1 flowing through the loop is zero, after the semiconductor switch Q3 is turned off, the power semiconductor switch Q4 is turned on again, and the capacitor C1 is discharged; in the process, the current IL1 flowing through the loop decreases from the operating current to zero, and the voltage VD1 in parallel with the electronic switch Q1 or/and Q2 increases from zero to the supply voltage; the energy of the C1 clamp at this time is: the operating current IL1 stores energy in the inductance L1 and the inductance of the output-side cable;

working condition 2: when surge exists in the off state, when surge voltage/greater than a protection value exists at an output end port is detected in the off state, the semiconductor switch Q3 is required to be immediately conducted to clamp energy, so that the electronic switch Q1 or/and the electronic switch Q2 are protected, when the working current IL1 is reduced to zero from small to large, the semiconductor switch Q3 is turned off, and then the power semiconductor switch Q4 is conducted to discharge the capacitor C1; the energy of the C1 clamp at this time is: surge energy or lightning stroke energy of the output port attenuated by the inductor L1;

working condition 3: when the electronic switch is normally turned off, the electronic switch Q1 or/and Q2 is turned on from the off state, the working current IL1 quickly reaches the load current, and VD1 quickly drops to zero; at this point C1 clamps no energy;

working condition 4: when the working current IL1 is larger than the protection value, the electronic switch Q1 or/and the electronic switch Q2 are immediately closed, the semiconductor switch Q3 is always on, and the on-power semiconductor switch Q4 is turned into an off state due to lightning stroke or surge; the energy of the C1 clamp at this time is: energy stored in the L1 and output cables due to a surge or lightning strike.