CN219372267U - Driving circuit for semiconductor switch, hybrid relay and motor starter - Google Patents

Abstract

The present disclosure relates to a drive circuit for a semiconductor switch, a hybrid relay, and a motor starter. The driving circuit includes: first and second switching units, a switching control unit, first and second clamping units, an input terminal and an output terminal. The input terminal is adapted to be coupled to a power source and the output terminal is configured to output a control signal to a control electrode of the semiconductor switch to control the semiconductor switch to be closed or opened. The first and second switch units are connected in series between the input terminal and the output terminal. The switch control unit is configured to control the first switch unit to be turned on or off and to control the second switch unit to be turned on or off. The first clamping unit is connected with the first switching unit in parallel, the second clamping unit is connected with the second switching unit in parallel, the clamping voltage of the first clamping unit is smaller than the withstand voltage value of the first switching unit, and the clamping voltage of the second clamping unit is smaller than the withstand voltage value of the second switching unit. In this way, the withstand voltage value of the driving circuit can be doubled.

Description

Driving circuit for semiconductor switch, hybrid relay and motor starter

Technical Field

Embodiments of the present utility model relate generally to the field of electrical switches, and more particularly, to a drive circuit, a hybrid relay, and a motor starter for a semiconductor switch.

Background

The motor starter is a device for assisting the starting of a motor. The motor starter can enable the motor to start stably, has small impact on a power grid, and can also realize control of soft stopping, braking, overload, phase-failure protection and the like of the motor. The motor starter is mainly used in large-scale motors and asynchronous motors. In large motor applications, surges may occur, for example, which cause the input voltage of the motor starter to suddenly rise. Typically, the surge voltage is clamped to a certain voltage value to protect the switching devices in the starter from breakdown by the surge voltage. However, in some high voltage scenarios, the available semiconductor price in the drive circuit for the switching device cannot safely operate at a viable clamp voltage. Therefore, how to design a driving circuit capable of withstanding surge voltage is a challenge facing a designer.

Disclosure of Invention

Embodiments of the present disclosure provide a driving circuit with a surge protection function, thereby at least partially solving the above and other potential problems existing in the prior art.

A first aspect of the present disclosure relates to a driving circuit for a semiconductor switch. The semiconductor switch includes a first pole adapted to be coupled to a power source, a second pole adapted to be coupled to a load, and a control pole. The driving circuit includes: the switching control unit comprises a first switching unit, a second switching unit, a switching control unit, a first clamping unit, a second clamping unit, an input end and an output end; the input terminal is suitable for being coupled to a power supply, and the output terminal is configured to output a control signal to a control electrode of the semiconductor switch to control the semiconductor switch to be closed or opened; the first switch unit and the second switch unit are connected in series between the input end and the output end, the switch control unit is coupled to the first switch unit and the second switch unit and is configured to control the first switch unit to be closed or opened and the second switch unit to be closed or opened, the first clamping unit is connected with the first switch unit in parallel, the second clamping unit is connected with the second switch unit in parallel, the clamping voltage of the first clamping unit is smaller than the withstand voltage value of the first switch unit, and the clamping voltage of the second clamping unit is smaller than the withstand voltage value of the second switch unit.

According to the embodiment of the disclosure, by connecting two switch units in series in the driving circuit, the two switch units can be divided, thereby improving the withstand voltage value of the whole driving circuit. In order to avoid excessive voltage at a single switching unit caused by uneven voltage division among the switching units, a clamping unit is connected in parallel for each switching unit for protection. Furthermore, two switching units connected in series may not be closed synchronously, for example due to an unsynchronized control signal or the like, when a voltage is applied to a single switching unit, which may cause the switching unit to break down if the voltage is too high. The provision of the clamp unit can also avoid such a situation. Thus, by providing a clamp unit for each switch unit, inclusion of the switch unit can be achieved, thereby improving the safety of the circuit.

In some embodiments, the semiconductor switch is, for example, a triac for use in an ac circuit. A triac is typically used as a switch in an ac circuit. The triac is made of NPNPN five-layer semiconductor material and includes three electrodes. Two of the three electrodes connected in the main circuit are called electrodes and electrodes, and the other electrode connected in the control circuit is called a control electrode G, or a gate, a gate. The triac can be controlled to close or open by adjusting the voltage at the G-pole.

In some embodiments, the first switching unit comprises a first optocoupler triac and the second switching unit comprises a second optocoupler triac. The first optocoupler bidirectional thyristor comprises a first output end and a second output end, the second optocoupler bidirectional thyristor comprises a first output end and a second output end, and the first output end, the second output end and the first output end and the second output end of the second optocoupler bidirectional thyristor are connected in series between the input end and the output end of the driving circuit. In such an embodiment, the output terminals of the two optocoupler triacs are connected in series in the drive circuit, so that the triacs of the optocoupler triacs are connected in series for voltage division. The optocoupler bidirectional thyristor is also called as a photoelectric bidirectional thyristor or a photoelectric triac, and has the main advantages of completely isolating any noise or voltage spike appearing on an alternating current power line, and carrying out zero-crossing detection on a sine waveform, thereby reducing switching and surge currents and realizing protection of any semiconductor device used.

In some embodiments, the first optocoupler triac includes a first input and a second input, the second optocoupler triac includes a first input and a second input, and the first input, the second input of the first optocoupler triac and the first input, the second input of the second optocoupler triac are coupled to the switch control unit. In such an embodiment, by coupling the input terminals of the first optocoupler triac and the second optocoupler triac to a common switch control unit, the two optocoupler triacs can be controlled simultaneously with the switch control unit, thereby achieving synchronous switching of the two optocoupler triacs.

In some embodiments, the switch control unit includes: the voltage source is coupled to the first input end of the first optocoupler bidirectional thyristor; the first end of the control switch is coupled to the second input end of the second optocoupler triac, the second end of the control switch is grounded, the second input end of the first optocoupler triac is coupled with the first input end of the second optocoupler triac, and the control switch is configured to control the first optocoupler triac and the second optocoupler triac to be turned on or off. In such an embodiment, the input ends of the two optocoupler bi-directional thyristors are connected in series in the voltage supply circuit, that is, the light emitting diodes of the optocoupler bi-directional thyristors are connected in series between the voltage source and the control switch, and when the control switch is turned on, the circuit where the light emitting diodes of the two optocoupler bi-directional thyristors are located is turned on, and at this time, the light emitting diodes emit light, so that the optocoupler bi-directional thyristors are turned on, and the driving circuit is turned on.

In some alternative embodiments, the switch control unit includes: a voltage source coupled to the first input of the first optocoupler triac and the first input of the second optocoupler triac; and a control switch, wherein a first end of the control switch is coupled to the second input end of the first optocoupler triac and the second input end of the second optocoupler triac, and a second end of the control switch is grounded, and the control switch is configured to control the first optocoupler triac and the second optocoupler triac to be turned on or off. In such an embodiment, the input ends of the two optocoupler bi-directional thyristors are connected in parallel in the voltage supply circuit, that is, the light emitting diodes of the optocoupler bi-directional thyristors are connected in parallel between the voltage source and the control switch, and when the control switch is turned on, the circuit where the light emitting diodes of the two optocoupler bi-directional thyristors are located is turned on, and at this time, the light emitting diodes emit light, so that the optocoupler bi-directional thyristors are turned on, and the driving circuit is turned on.

In some embodiments, the control switch further comprises a control terminal. The control terminal of the control switch is configured to receive the control signal and to turn on the control switch in response to the control signal being high. In such an embodiment, the control switch may be, for example, a MOSFET, the control terminal of which is capable of receiving a control signal from the micro-control unit and causing the control switch to be closed when a control signal of a high level is received.

In some embodiments, the first clamping unit comprises at least one first transient voltage suppression diode and the second clamping unit comprises at least one second transient voltage suppression diode. A transient voltage suppression diode (TVS) is a high performance voltage limiting protection device. When the TVS is subjected to instantaneous high energy impact, the resistance of the TVS is suddenly reduced at a very high speed, and a large current is absorbed, so that the voltage between the two ends of the TVS is clamped to a preset value, and the circuit element connected in parallel with the TVS is prevented from being damaged by the instantaneous high energy impact. In such an embodiment, the clamping function can be achieved by providing a bi-directional TVS. When a plurality of transient voltage suppressing diodes are provided in series, flexibility in selection of the type can be improved, and parasitic capacitance can also be reduced to reduce interference.

In some embodiments, the first clamping unit comprises at least one first varistor and the second clamping unit comprises at least one second varistor. Similarly, piezoresistors can also be used as clamping units. The piezoresistor is a voltage limiting type protection device. By utilizing the nonlinear characteristic of the piezoresistor, when the overvoltage occurs between two poles of the piezoresistor, the piezoresistor can clamp the voltage to a relatively fixed voltage value, so that the protection of a subsequent circuit is realized.

A second aspect of the present disclosure relates to a hybrid relay. The hybrid relay includes: a first terminal and a second terminal; a mechanical switch; a semiconductor switch comprising a first pole, a second pole, and a control pole, wherein the mechanical switch is connected in parallel with the semiconductor switch between a first terminal and a second terminal; and a drive circuit for a semiconductor switch according to the first aspect of the present disclosure. An input of the drive circuit is connected to the first terminal and an output of the drive circuit is connected to a control electrode of the semiconductor switch.

According to an embodiment of the second aspect of the present disclosure, the semiconductor switch constitutes a solid state relay portion of the hybrid relay, and the mechanical switch constitutes a mechanical relay portion. Thus, the hybrid relay combines the advantages of both solid state and mechanical relays.

A third aspect of the present disclosure relates to a motor starter configured to control starting or stopping of a three-phase motor. The motor starter comprises two hybrid relays according to the first aspect of the present disclosure and one mechanical relay. A hybrid relay is adapted to be coupled to a first phase input of the three-phase motor; the other hybrid relay is adapted to be coupled to a second phase input of the three-phase motor; the mechanical relay (12) is adapted to be coupled to a third phase input of the three-phase motor.

It will be appreciated that the description and advantages for use in accordance with the first aspect of the present disclosure apply equally to the hybrid relay of the second aspect of the present disclosure and to the motor starter of the third aspect of the present disclosure.

Drawings

The above and other objects, features and advantages of embodiments of the present disclosure will become more readily apparent from the following detailed description with reference to the accompanying drawings. Embodiments of the present disclosure will now be described, by way of example and not limitation, in the figures of the accompanying drawings, in which:

FIG. 1 illustrates a schematic diagram of a motor starting system according to an exemplary embodiment of the present disclosure;

fig. 2 shows a schematic diagram of a driving circuit for a semiconductor switch according to an exemplary embodiment of the present disclosure; and

fig. 3 illustrates a schematic diagram of a specific structure of a driving circuit for a semiconductor switch according to an exemplary embodiment of the present disclosure.

Detailed Description

The principles of the present disclosure will now be described with reference to various exemplary embodiments shown in the drawings. It should be understood that these embodiments are merely provided to enable those skilled in the art to better understand and further practice the present disclosure and are not intended to limit the scope of the present disclosure in any way. It should be noted that similar or identical reference numerals may be used, where possible, in the figures and similar or identical reference numerals may designate similar or identical functions. Those skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the utility model described herein.

As used herein, the term "comprising" and variants thereof are to be construed as meaning open-ended terms including, but not limited to. The term "based on" will be read as "based at least in part on". The terms "one embodiment" and "an embodiment" should be understood as "at least one embodiment". The term "another embodiment" should be understood as "at least one other embodiment". The terms "first," "second," and the like, may refer to different or the same object. Other explicit and implicit definitions may be included below. Unless the context clearly indicates otherwise, the definition of terms is consistent throughout the specification.

As discussed above, at the moment when the motor starter is turned on and off, there may be an unsynchronized condition of its relay, at which time the line voltage will be loaded across the non-conducting triac, as well as across the circuit elements in the drive circuit for the triac. When a surge occurs in the circuit, it is likely to cause damage to circuit elements in the drive circuit.

Conventionally, for protection against surge voltages, a pulse transformer having a corresponding withstand voltage value may be used to control the triac. However, pulse transformers take up a large space and are less cost effective.

Various embodiments according to the present disclosure provide a driving circuit for a semiconductor switch having an improved withstand voltage value. The voltage-withstanding value of the driving circuit can be doubled by arranging two voltage-dividing modules which are formed by the switch unit and the clamping unit in series in a circuit for driving and controlling the semiconductor switch, so that surge voltage appearing in the circuit can be fully dealt with, and the service life of devices in the driving circuit can be prolonged. Meanwhile, the clamping unit can also protect the voltage of the single switching element when the switching units do not work synchronously. Thereby, on the other hand, the stability of the circuit is improved.

Fig. 1 shows a schematic diagram of a motor starting system according to an exemplary embodiment of the present disclosure. As shown in fig. 1, the three-phase motor 2 comprises a first phase input, a second phase input and a third phase input, the three inputs being connected to the power supply 3, for example via a switching device, to obtain power from the power supply 3. The power supply 3 is for example a busbar in the power grid. A motor starter 1 is connected between a power supply 3 and a three-phase motor 2 as a load. The motor starter 1 is capable of controlling the starting and closing of the three-phase motor 2. In the embodiment shown in the figures, the motor starter 1 comprises a hybrid relay 11-1 coupled to a first phase input of the three-phase motor 2, a hybrid relay 11-2 coupled to a second phase input (hybrid relays 11-1 and 11-2 are collectively referred to as hybrid relay 11), and a mechanical relay 12 coupled to a third phase input. The hybrid relay 11-1 includes a solid-state switching semiconductor switch 200-1, a drive circuit 100-1 for the semiconductor switch 200-1, a mechanical switch K1, and a first terminal 300-1 and a second terminal 400-1. In the hybrid relay 11-1, the semiconductor switch 200-1 is connected in parallel with the mechanical switch K1 between the first terminal 300-1 and the second terminal 400-1, and the input terminal 101-1 of the driving circuit 100-1 is coupled to the power source 3, and the output terminal 102-1 is coupled to the control electrode of the semiconductor switch 200-1 to control the semiconductor switch 200-1 to be turned on or off. Similarly, the hybrid relay 11-2 includes a solid-state switching semiconductor switch 200-2 (semiconductor switches 200-1 and 200-2 are collectively referred to as semiconductor switch 200), a driving circuit 100-2 for the semiconductor switch 200-2 (driving circuits 100-1 and 100-2 are collectively referred to as driving circuit 100), a mechanical switch K2, and a first terminal 300-2 and a second terminal 400-2. In the hybrid relay 11-2, the semiconductor switch 200-2 is connected in parallel with the mechanical switch K2 between the first terminal 300-2 and the second terminal 400-2, and the input terminal 101-2 of the driving circuit 100-2 is coupled to the power source 3, and the output terminal 102-2 is coupled to the control electrode of the semiconductor switch 200-2 to control the semiconductor switch 200-1 to be turned on or off. The mechanical relay 12 includes a first terminal 121 and a second terminal 122 and a mechanical switch K3. The mechanical switch K3 is connected between the first operator 121 and the second terminal 122. The mechanical switches K1, K2 and K3 may be, for example, electromagnetic contact switches.

When the three-phase motor 2 is started, the mechanical switch K3 of the mechanical relay 12 is first closed so that no current is generated at the moment when the mechanical switch is closed. Since only the mechanical switch K3 is closed, no path is formed at this time, so that no current flows through the mechanical relay 12. After that, the semiconductor switch 200-1 and the semiconductor switch 200-2 will be simultaneously closed to start the three-phase motor 2. Since the semiconductor switch 200-1 and the semiconductor switch 200-2 are solid switches, an arc is not generated when closed. Then, after the semiconductor switches 200-1 and 200-2 are closed, the mechanical switches K1 and K2 are closed again. Finally, the semiconductor switch 200-1 and the semiconductor switch 200-2 are turned off. It can be seen that no current flows at the moment the mechanical switch is closed during the whole starting process, so that no arc is generated, and the service life of the mechanical switch is prolonged. During the process of turning off the motor, the switching sequence of the individual switches is reversed from the completion of the starting process.

Further, at the time of starting the three-phase motor 2, there may be a case where the semiconductor switch 200-1 and the semiconductor switch 200-2 are not simultaneously closed due to delay of a control signal or the like. In this case, the supply power will be loaded on a single semiconductor switch 11. At this time, the devices in the driving circuit 200 of the semiconductor switch 11 are loaded with a very high voltage. The drive circuit 200 is designed to be resistant to high voltages that may occur in the power supply circuit. The structure and principle of the driving circuit 200 will be described in detail with reference to fig. 2.

Fig. 2 shows a schematic diagram of a driving circuit 100 for a semiconductor switch 200 according to an exemplary embodiment of the present disclosure. As shown in fig. 2, the semiconductor switch 200 includes a first pole T1, a second pole T2, and a control pole G. The first pole T1 is coupled to a power source 3, the second pole is coupled to a load, such as the three-phase motor 2 in fig. 1, and the control pole G is coupled to the driving circuit 100, and the semiconductor switch 200 is turned on or off in response to receiving a control signal from the driving circuit 100 via the control pole G. The driving circuit 100 comprises an input 101 and an output 102. The input terminal 101 is coupled to a connection circuit of the power supply 3 and the first pole T1. The output terminal T2 is coupled to the control electrode G.

In order to be able to increase the withstand voltage value, a first switching unit 110 and a second switching unit 120 connected in series are provided between the input terminal 101 and the output terminal 102 of the driving circuit 100 to perform voltage division. A switch control unit 130 is also provided in the driving circuit 100 for controlling the first and second switching units 110 and 120 to be turned on or off, respectively. For example, the switching control unit 130 may transmit a switching control signal to the first and second switching units 110 and 120.

Since there may be a partial pressure non-uniformity between the first and second switching units 110 and 120, one of the two switching units may receive a large part of the voltage. However, when the voltage is too large, the voltage across the switching cell, which is subjected to most of the voltage, may exceed its withstand voltage value. In this regard, the first and second clamping units 140 and 150 are connected in parallel to the first and second switching units 110 and 120, respectively, and the clamping voltage of the first clamping unit 140 is smaller than the withstand voltage value of the first switching unit 110, and the clamping voltage of the second clamping unit 150 is smaller than the withstand voltage value of the second switching unit 120.

Fig. 3 illustrates a schematic diagram of a specific structure of the driving circuit 100 for the semiconductor switch 200 according to an exemplary embodiment of the present disclosure. In this embodiment, the semiconductor switch 200 is a triac suitable for use in an ac circuit. As shown in fig. 3, the semiconductor switch 200 includes a first pole T1, a second pole T2, and a control pole G. The first pole T1 is coupled to the power source 3 and the input 101 of the driving circuit 100, the second pole T2 is coupled to the load 2, and the control pole G is coupled to the output 102 of the driving circuit 100.

The first switching unit 110, the second switching unit 120, the switch control unit 130, the first clamping unit 140, and the second clamping unit 150 of the driving circuit 100. The first switching unit 110 includes a first optocoupler triac PT1, and the second switching unit 120 includes a second optocoupler triac PT2. The first optocoupler triac PT1 includes a first output terminal and a second output terminal, and the second optocoupler triac PT2 includes a first output terminal and a second output terminal. The first output terminal and the second output terminal of the first optocoupler triac PT1 and the first output terminal and the second output terminal of the second optocoupler triac PT2 are connected in series between the input terminal 101 and the output terminal 102.

The first optocoupler triac PT1 includes a first input terminal and a second input terminal, and the second optocoupler triac PT2 includes a first input terminal and a second input terminal, and is coupled to the switch control unit 130 via the input terminals to receive the switch control signal from the switch control unit 130. The switch control unit 130 includes a voltage source 131 and a control switch 132.

In the embodiment shown in the figures, the input of the first optocoupler triac PT1 and the input of the second optocoupler triac PT2 are connected in series between the voltage source 131 and the control switch 132. The voltage source 131 is, for example, 12v, and is coupled to the first input terminal of the first optocoupler triac PT1 via a resistor R3. The second input terminal of the first optocoupler triac PT1 is coupled to the first input terminal of the second optocoupler triac PT2. A second input of the second optocoupler triac PT2 is coupled to a drain of a metal-oxide semiconductor field effect transistor (MOSFET) M1 of the control switch 132. The source of MOSFET M1 is grounded. The gate of MOSFET M1 is coupled to the first terminal of capacitor C1, the first terminal of capacitor R5, and the first terminal of capacitor R4. The second terminal of the capacitor C1 is coupled to the second terminal of the capacitor R5 and is grounded. A second terminal of the capacitor R4 is coupled to the control signal input terminal and configured to receive a control signal, for example, from a Micro Control Unit (MCU).

In an alternative embodiment, the input of the first optocoupler triac PT1 and the input of the second optocoupler triac PT2 are connected in parallel between the voltage source 131 and the control switch 132. That is, the voltage source 131 is coupled to the first input terminal of the first optocoupler triac PT1 and the first input terminal of the second optocoupler triac PT2, and the control switch 132 has a first terminal coupled to the second input terminal of the first optocoupler triac PT1 and the second input terminal of the second optocoupler triac PT2. The second terminal of the control switch 132 is grounded.

When the gate of the MOSFET M1 receives a high-level control signal, the MOSFET M1 is turned on, so that the circuit where the input terminal of the first optocoupler triac PT1 and the input terminal of the second optocoupler triac PT2 are located is turned on. At this time, the light emitting diode in the first optocoupler triac PT1 and the light emitting diode of the second optocoupler triac PT2 emit light synchronously, so that the output terminal in the first optocoupler triac PT1 and the output terminal of the second optocoupler triac PT2 are turned on. At this time, the circuit between the power supply 3 and the gate G of the semiconductor switch 200 is turned on, and the gate G receives the control signal to turn on the semiconductor switch 200.

As discussed in fig. 1, at the time of starting the three-phase motor 2, if the power bus voltage is 500v, the peak voltage in the circuit may be about 1000v, and if a surge is generated, the surge voltage is about 1200v. In the event of a surge, the two terminals of the non-conductive semiconductor switch may be loaded with a high voltage of 1200v, and this voltage is simultaneously loaded to the two terminals of the driving circuit 100. However, conventionally available optocoupler thyristors have a withstand voltage of about 800v and may break down. In contrast, if a clamping device is arranged in the circuit, the voltage can only be clamped at 1000v, and the working requirement of the optocoupler bidirectional thyristor can not be met. Accordingly, the driving circuit 100 is provided with the first optocoupler triac PT1 and the second optocoupler triac PT2 connected in series to divide the voltage.

Due to the characteristics of the bidirectional thyristors in the optocoupler bidirectional thyristors for voltage division, the voltage division cannot be guaranteed to be uniform, and therefore, most of voltages exceeding the withstand voltage value can be born by one optocoupler bidirectional thyristor. Therefore, the clamping unit 140 composed of two TVS EC1 and EC2 is connected in parallel to the first optocoupler triac PT1, and the clamping unit 150 composed of two TVS EC3 and EC4 is connected in parallel to the second optocoupler triac PT2, so as to prevent the voltage applied across the optocoupler triac from exceeding the withstand voltage value, thereby realizing forced voltage division. Thus, breakdown due to surge voltage can be prevented.

Specifically, the first clamping unit 140 includes two transient suppression diodes (TVS) EC1 and EC2 connected in series, and is connected in parallel with the output terminal of the first optocoupler triac PT 1. The second clamping unit 150 includes two TVS EC3 and EC4 connected in series and is connected in parallel with the output terminal of the second optocoupler triac PT2. That is, the first terminal of the TVS EC1 is coupled to the first output terminal of the first optocoupler triac PT 1. The second terminal of TVS EC1 is coupled to the first terminal of TVS EC 2. The second terminal of TVS EC2 is coupled to the second output terminal of the first optocoupler triac PT1 and the first terminal of TVS EC 3. Similarly, a first terminal of TVS EC3 is coupled to a first output terminal of the second optocoupler triac PT2 and a second terminal of TVS EC 2. The second end of TVS EC3 is coupled to the first end of TVS EC 4. A second terminal of the TVS EC4 is coupled to a second output terminal of the second optocoupler triac PT2. The clamping voltages of the TVS EC1 and the TVS EC2 are smaller than the withstand voltage value of the first optocoupler triac PT 1. The clamping voltages of the TVS EC3 and the TVS EC4 are smaller than the withstand voltage value of the second optocoupler triac PT2.

When the gate of the MOSFET M1 of the control switch 132 receives the high-level control signal to be turned on, the circuits where the input ends of the first optocoupler triac PT1 and the second optocoupler triac PT2 are located are turned on. However, for some reasons, the first optocoupler triac PT1 and the second optocoupler triac PT2 cannot be turned on synchronously, and at this time, the voltage in the circuit is fully loaded across the non-turned-on optocoupler triac, and when a voltage peak occurs in the circuit, the voltage across the non-turned-on optocoupler triac may exceed the withstand voltage value. By the clamping unit, the voltage across the non-conductive optocoupler bidirectional thyristor can be clamped to be smaller than the withstand voltage value. And in a short time, the non-conductive optocoupler bidirectional thyristors are also conductive, and the two optocoupler bidirectional thyristors work normally through voltage division.

It should be understood that the triac in the embodiment shown in fig. 3 is only one example of a semiconductor switch, and that the semiconductor switch described in this disclosure may be any other conventional suitable semiconductor switch. Here, the elements in the driving circuit 100 may be determined according to the type of the semiconductor switch, and the present disclosure is not intended to be limited thereto.

Thus, according to the embodiment of the present disclosure, voltage division is performed by providing the switching units connected in series and the clamping units respectively provided for the switching units, so that the overall withstand voltage value of the driving circuit is improved, surge voltage impact is prevented, and the reliability of the driving circuit is improved.

Although claims have been formulated in this application to particular combinations of features, it should be understood that the scope of the disclosure also includes any novel feature or any novel combination of features disclosed herein either explicitly or implicitly or any generalisation thereof, whether or not it relates to the same in any claim as presently claimed. The applicants hereby give notice that new claims may be formulated to such features and/or combinations of such features during the prosecution of the present application or of any further application derived therefrom.

Claims (10)

1. A drive circuit (100) for a semiconductor switch (200), the semiconductor switch (200) comprising a first pole (T1) adapted to be coupled to a power supply (3), a second pole (T2) adapted to be coupled to a load (2), and a control pole (G),

characterized in that the driving circuit (100) comprises: a first switching unit (110), a second switching unit (120), a switching control unit (130), a first clamping unit (140), a second clamping unit (150), and an input (101) and an output (102); the input terminal (101) is adapted to be coupled to the power supply (3) and the output terminal (102) is configured to output a control signal to a control electrode of the semiconductor switch (200) to control the semiconductor switch (200) to be closed or opened;

wherein the first switching unit (110) and the second switching unit (120) are connected in series between the input terminal (101) and the output terminal (102),

the switch control unit (130) is coupled to the first switch unit (110) and the second switch unit (120) and is configured to control the first switch unit (110) to be closed or opened and the second switch unit (120) to be closed or opened,

the first clamping unit (140) is connected in parallel with the first switching unit (110), the second clamping unit (150) is connected in parallel with the second switching unit (120), the clamping voltage of the first clamping unit (140) is smaller than the withstand voltage value of the first switching unit (110), and the clamping voltage of the second clamping unit (150) is smaller than the withstand voltage value of the second switching unit (120).

2. The drive circuit according to claim 1, wherein the first switching unit (110) comprises a first optocoupler triac (PT 1) and the second switching unit (120) comprises a second optocoupler triac (PT 2),

the first optocoupler triac (PT 1) comprises a first output end and a second output end, the second optocoupler triac (PT 2) comprises a first output end and a second output end, and the first output end, the second output end and the first output end and the second output end of the second optocoupler triac (PT 2) are connected in series between the input end (101) and the output end (102) of the driving circuit (100).

3. The drive circuit according to claim 2, wherein the first optocoupler triac (PT 1) comprises a first input and a second input; the second optocoupler triac (PT 2) includes a first input and a second input; the first input terminal and the second input terminal of the first optocoupler triac (PT 1) and the first input terminal and the second input terminal of the second optocoupler triac (PT 2) are coupled to the switch control unit (130).

4. The drive circuit according to claim 2, wherein the switch control unit (130) includes:

-a voltage source (131) coupled to a first input of the first optocoupler triac (PT 1);

a control switch (132), a first end of the control switch (132) being coupled to a second input of the second optocoupler triac (PT 2), a second end of the control switch (132) being grounded,

wherein a second input of the first optocoupler triac (PT 1) is coupled to a first input of the second optocoupler triac (PT 2), and

the control switch (132) is configured to control the first optocoupler triac (PT 1) and the second optocoupler triac (PT 2) to be turned on or off.

5. The drive circuit according to claim 2, wherein the switch control unit (130) includes:

-a voltage source (131) coupled to a first input of the first optocoupler triac (PT 1) and a first input of the second optocoupler triac (PT 2);

a control switch (132), a first end of the control switch (132) being coupled to a second input of the first optocoupler triac (PT 1) and a second input of the second optocoupler triac (PT 2), a second end of the control switch (132) being grounded, and

the control switch (132) is configured to control the first optocoupler triac (PT 1) and the second optocoupler triac (PT 2) to be turned on or off.

6. The drive circuit of claim 4 or 5, wherein the control switch (132) further comprises a control terminal, the control terminal of the control switch (132) being configured to receive a control signal and to turn on the control switch (132) in response to the control signal being high.

7. The driving circuit according to claim 1, wherein,

the first clamping unit (140) comprises at least one first transient voltage suppression diode (EC 1, EC 2), and

the second clamping unit (150) comprises at least one second transient voltage suppression diode (EC 3, EC 4).

8. The driving circuit according to claim 1, wherein,

the first clamping unit (140) comprises at least one first varistor, and

the second clamping unit (150) comprises at least one second varistor.

9. A hybrid relay (11), characterized by comprising:

a first terminal (300) and a second terminal (400);

mechanical switches (K1, K2);

a semiconductor switch (200) comprising a first pole (T1), a second pole (T2) and a control pole (G),

wherein the mechanical switch (K1, K2) is connected in parallel with the semiconductor switch (200) between the first terminal (300) and the second terminal (400); and

the drive circuit (100) for a semiconductor switch according to any one of claims 1 to 8, an input (101) of the drive circuit (100) being connected to the first terminal (300) and an output (102) of the drive circuit (100) being connected to a control pole of the semiconductor switch (200).

10. Motor starter (1) configured to control the starting or stopping of a three-phase motor, characterized in that the motor starter (1) comprises two hybrid relays (11) according to claim 9 and one mechanical relay (12);

wherein one of said hybrid relays (11) is adapted to be coupled to a first phase input of said three-phase motor; -a further said hybrid relay (11) is adapted to be coupled to a second phase input of said three-phase motor; the mechanical relay (12) is adapted to be coupled to a third phase input of the three-phase motor.