Trigger control circuit of soft starter and soft starter

Abstract

The utility model discloses a trigger control circuit of a soft starter and the soft starter, and the trigger control circuit effectively isolates the direct electrical connection between a microprocessor and a silicon controlled rectifier trigger circuit through introducing a first-stage isolation circuit and a second-stage isolation circuit. The influence of electromagnetic interference generated by a high-voltage line, a large-scale motor and the like on a trigger signal is reduced, so that the risk of distortion, false triggering or triggering failure of the trigger signal is reduced, and stable operation of the soft starter is ensured; the push-pull circuit can output a strong driving signal to ensure that a trigger signal can be accurately transmitted in the silicon controlled rectifier trigger circuit, so that the connection and disconnection of the anti-parallel thyristors are controlled, the soft start and soft stop of a motor are realized, and the response speed and the stability of the transmission of the trigger signal of the thyristors are improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to soft starter technical field, concretely relates to a trigger control circuit and soft starter of soft starter. BACKGROUND

[0002] Soft starter is a kind of advanced motor control device that is integrated with motor soft start, soft parking, light load energy saving and multiple protection functions, mainly by three-phase anti-parallel thyristor, microprocessor control unit, trigger circuit, current detection device and bypass contactor etc., wherein three-phase anti-parallel thyristor as voltage regulator, is connected in series between power supply and motor stator, for adjusting output voltage.

[0003] After receiving starting instruction, soft starter, control unit starts calculating and outputs the signal of triggering thyristor, and trigger circuit generates trigger pulse according to the signal of control unit, makes thyristor gradually conduct, and the output voltage of thyristor gradually increases, and the rotating speed and torque of motor also gradually increase, until reaching rated rotating speed and torque, and bypass contactor is attracted directly through internal signal trigger, simultaneously cutting off thyristor, to complete the soft start of motor. The soft parking of soft starter also calculates and outputs the signal of triggering thyristor, and trigger circuit generates trigger pulse according to the signal of control unit, makes thyristor gradually close, and the output voltage of thyristor gradually reduces, and the rotating speed and torque of motor also gradually reduce, until motor stops.

[0004] Therefore, the trigger circuit of soft starter is the core circuit of controlling thyristor conduction, and after receiving the control signal of control unit, trigger circuit outputs trigger signal to thyristor to realize the soft start and soft parking of motor. However, in actual working scene, due to the existence of high-voltage line, large motor etc., the trigger circuit of soft starter is interfered by electromagnetic interference generated thereby, leading to trigger signal distortion, false triggering or trigger failure, which affects the normal operation of soft starter.

[0005] Therefore, it is urgent to propose a trigger control circuit of soft starter to overcome the problem that soft starter cannot work normally due to electromagnetic interference. SUMMARY

[0006] To solve the above problem, the utility model provides a trigger control circuit and soft starter of soft starter.

[0007] The utility model discloses a first aspect provides a kind of trigger control circuit of soft starter, including microprocessor, switching power supply circuit, current detection circuit, zero-crossing detection circuit, silicon-controlled trigger circuit and be connected in the anti-parallel thyristor of soft starter main circuit, the output of the current detection circuit and the output of the zero-crossing detection circuit are respectively connected the input of the microprocessor, the switching power supply circuit is respectively the microprocessor and the silicon-controlled trigger circuit provides operating voltage, the silicon-controlled trigger circuit includes primary isolation circuit, push-pull circuit, secondary isolation circuit, first output circuit and second output circuit, the input of the primary isolation circuit is connected the output of the microprocessor, the output of the primary isolation circuit is connected the input of the push-pull circuit, the output of the push-pull circuit is connected the input of the secondary isolation circuit, the output of the secondary isolation circuit is respectively connected the input of the first output circuit and the input of the second output circuit, the output of the first output circuit and the output of the second output circuit are respectively connected the anti-parallel thyristor.

[0008] Based on the first aspect, in a possible implementation manner, the primary isolation circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a first triode and an optocoupler; a first end of the first resistor is connected to the output of the microprocessor, a second end of the first resistor is respectively connected to a first end of the second resistor and a base of the first triode, a second end of the second resistor and an emitter of the first triode are connected in common, a collector of the first triode is connected to a cathode of the optocoupler, a first end of the third resistor is connected to a first high level, a second end of the third resistor is connected to an anode of the optocoupt, a collector of the optocoupler is connected to a second high level, a transmitter of the optocoupler is connected to a first end of the fourth resistor, and a second end of the fourth resistor is connected to the input of the push-pull circuit.

[0009] In a possible implementation manner of the first aspect, the push-pull circuit comprises an operational amplifier, a same-phase input resistor, a feedback resistor, a fifth resistor, a sixth resistor, a first diode, a second diode, a second transistor and a third transistor; a non-inverting input end of the operational amplifier is connected to a second end of the fourth resistor, a first end of the same-phase input resistor is connected to an inverting input end of the operational amplifier, a second end of the same-phase input resistor is connected to a reference voltage, a first end of the feedback resistor is connected to the inverting input end of the operational amplifier, a second end of the feedback resistor is connected to an output end of the operational amplifier, the fifth resistor, the first diode, the second diode and the sixth resistor are connected in series, the output end of the operational amplifier is connected to a negative electrode of the first diode, a first end of the fifth resistor is connected to a second high level, a first end of the sixth resistor is grounded, a second end of the fifth resistor is connected to a base of the second transistor, a second end of the sixth resistor is connected to a base of the third transistor, a collector of the second transistor is connected to the second high level, an emitter of the second transistor is connected to an emitter of the third transistor, a collector of the third transistor is grounded, and the emitter of the second transistor and the collector of the third transistor are connected to an input end of the two-stage isolation circuit respectively.

[0010] In a possible implementation manner of the first aspect, the push-pull circuit further comprises a first capacitor and a second capacitor; a first end of the first capacitor is connected to the collector of the second transistor, a second end of the first capacitor is connected to the base of the second transistor, a first end of the second capacitor is connected to the collector of the third transistor, and a second end of the second capacitor is connected to the base of the third transistor.

[0011] In a possible implementation manner of the first aspect, the second transistor is an NPN type transistor, and the third transistor is a PNP type transistor.

[0012] In a possible implementation manner of the first aspect, the two-stage isolation circuit comprises a pulse transformer, a voltage stabilizing diode, a third capacitor and a seventh resistor; a negative electrode of the voltage stabilizing diode is connected to the emitter of the second transistor and a first end of the third capacitor respectively, a positive electrode of the voltage stabilizing diode is connected to the collector of the third transistor and a first end of the seventh resistor respectively, and two ends of a primary winding of the pulse transformer are connected to a second end of the third capacitor and a second end of the seventh resistor respectively.

[0013] In a possible implementation manner of the first aspect, the anti-parallel thyristor comprises a first thyristor and a second thyristor connected in anti-parallel; an output end of the first output circuit is connected to a gate electrode of the first thyristor and a cathode of the first thyristor, and an output end of the second output circuit is connected to a gate electrode of the second thyristor and a cathode of the second thyristor.

[0014] In a possible implementation manner of the first aspect, the first output circuit comprises a third diode, a fourth diode and an eighth resistor; two ends of a first winding of a secondary side of the pulse transformer are respectively connected to a positive electrode of the third diode and a positive electrode of the fourth diode, a negative electrode of the third diode is connected to a negative electrode of the fourth diode, and the eighth resistor is connected in parallel to the fourth diode, a first end of the eighth resistor is connected to the gate electrode of the first thyristor, and a second end of the eighth resistor is connected to the cathode of the first thyristor; the second output circuit comprises a fifth diode, a sixth diode and a ninth resistor; two ends of a second winding of the secondary side of the pulse transformer are respectively connected to a positive electrode of the fifth diode and a positive electrode of the sixth diode, a negative electrode of the fifth diode is connected to a negative electrode of the sixth diode, and the ninth resistor is connected in parallel to the sixth diode, a first end of the ninth resistor is connected to the gate electrode of the second thyristor, and a second end of the ninth resistor is connected to the cathode of the second thyristor.

[0015] In a possible implementation manner of the first aspect, the soft starter further comprises a surge protection circuit, the surge protection circuit comprising a varistor, a tenth resistor and a fourth capacitor; the varistor is connected in parallel to two ends of the anti-parallel thyristor, the tenth resistor and the fourth capacitor are connected in series, and first ends of the tenth resistor and the fourth capacitor are respectively connected to two ends of the varistor.

[0016] In the second aspect of the utility model, a soft starter is provided, which comprises the trigger control circuit described above.

[0017] Compared with the prior art, the technical scheme has the following beneficial effects:

[0018] The trigger control circuit of the soft starter effectively isolates the direct electrical connection between the microprocessor and the silicon-controlled trigger circuit by introducing the first isolation circuit and the second isolation circuit, reduces the influence of electromagnetic interference generated by high-voltage lines, large motors and the like on the trigger signal, thereby reducing the risk of distortion, false triggering or triggering failure of the trigger signal, and ensuring stable operation of the soft starter; the push-pull circuit can output a strong driving signal, ensuring that the trigger signal can be accurately and correctly transmitted in the silicon-controlled trigger circuit, thereby controlling the conduction and turn-off of the anti-parallel thyristor, realizing soft starting and soft parking of the motor, and improving the response speed and stability of the thyristor trigger signal transmission. Attached Figure Description

[0019] Figure 1 This is a block diagram of the trigger control circuit of the soft starter in an embodiment of the present invention.

[0020] Figure 2 This is a block diagram of the thyristor trigger circuit according to an embodiment of the present invention.

[0021] Figure 3 This is a schematic diagram of the thyristor trigger circuit according to an embodiment of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0023] Example 1

[0024] Combined with appendix Figure 1 To be continued Figure 3 This utility model provides a trigger control circuit for a soft starter, comprising a microprocessor 1, a switching power supply circuit 2, a current detection circuit 3, a zero-crossing detection circuit 4, a thyristor trigger circuit 5, and an anti-parallel thyristor 6 connected to the main circuit of the soft starter. The output terminals of the current detection circuit 3 and the zero-crossing detection circuit 4 are respectively connected to the input terminals of the microprocessor 1. The switching power supply circuit 2 provides operating voltages for the microprocessor 1 and the thyristor trigger circuit 5. The thyristor trigger circuit 5 includes a primary isolation circuit 51, a push-pull circuit 52, and a secondary isolation circuit 53. The circuit includes a first output circuit 53, a second output circuit 54, and a third output circuit 55. The input terminal of the first-stage isolation circuit 51 is connected to the output terminal of the microprocessor 1. The output terminal of the first-stage isolation circuit 51 is connected to the input terminal of the push-pull circuit 52. The output terminal of the push-pull circuit 52 is connected to the input terminal of the second-stage isolation circuit 53. The output terminal of the second-stage isolation circuit 53 is connected to the input terminals of the first output circuit 54 and the second output circuit 55, respectively. The output terminals of the first output circuit 54 and the second output circuit 55 are respectively connected to the anti-parallel thyristor 6.

[0025] In the embodiment, the anti-parallel thyristor 6 is connected between an external power supply and a motor to be driven, and one or three sets of the anti-parallel thyristor 6 can be provided according to the application scene (single phase or three phase) of the soft starter, so that the silicon controlled trigger circuit 5 is set according to the number of the anti-parallel thyristor 6. Figure 3 The silicon controlled trigger circuit 5 is used for triggering and driving a set of anti-parallel thyristors 6.

[0026] In the embodiment, the zero-crossing detection circuit 4 is used for detecting the zero-crossing point of an alternating current signal, that is, the instant when the signal changes from a positive maximum value to a negative maximum value or from a negative maximum value to a positive maximum value. By detecting the zero-crossing point, the soft starter can accurately control the switching-on time of the power supply, thereby avoiding a large impact current during starting and protecting the power supply and the load device. The current detection circuit 3 is used for collecting the output current of the motor, participating in the realization of current closed-loop regulation, and providing the protection module to complete overcurrent protection, phase loss protection, overload protection, locked-rotor protection and the like.

[0027] In the embodiment, the trigger control circuit of the soft starter introduces a first isolation circuit 51 and a second isolation circuit 53, effectively isolating the direct electrical connection between the microprocessor 1 and the silicon controlled trigger circuit 5, reducing the influence of electromagnetic interference generated by high-voltage lines, large motors and the like on the trigger signal, thereby reducing the distortion, false triggering or triggering failure risk of the trigger signal and ensuring the stable operation of the soft starter. The push-pull circuit 52 can output a strong driving signal to ensure that the trigger signal can be accurately and correctly transmitted in the silicon controlled trigger circuit 5, thereby controlling the conduction and closing of the anti-parallel thyristor 6 and realizing the soft starting and soft stopping of the motor, improving the response speed and stability of the thyristor trigger signal transmission.

[0028] In the embodiment, as shown in the accompanying Figure 3 The first end of the first resistor R1 is connected to the output end of the microprocessor, the second end of the first resistor R1 is respectively connected to the first end of the second resistor R2 and the base of the first triode Q1, the second end of the second resistor R2 and the emitter of the first triode Q1 are commonly connected, the collector of the first triode Q1 is connected to the cathode of the optocoupler U1, the first end of the third resistor R3 is connected to the first high level VCC1, the second end of the third resistor R3 is connected to the anode of the optocoupler U1, the collector of the optocoupler U1 is connected to the second high level VCC2, the transmitter of the optocoupler U1 is connected to the first end of the fourth resistor R4, and the second end of the fourth resistor R4 is connected to the input end of the push-pull circuit.

[0029] In the embodiment, the output of the microprocessor 1 is connected to the first resistor R1 to input a trigger signal trigger to the first isolation circuit 51, to control the first triode Q1 to be on or off, so that the optocoupler U1 outputs an isolated signal.

[0030] In the embodiment, as shown in the attached Figure 3 The push-pull circuit 52 includes an operational amplifier U2, a same-phase input resistor Rin, a feedback resistor Rf, a fifth resistor R5, a sixth resistor R6, a first diode D1, a second diode D2, a second triode Q2 and a third triode Q3; the inverting input of the operational amplifier U2 is connected to the second end of the fourth resistor R4, the first end of the same-phase input resistor Rin is connected to the non-inverting input of the operational amplifier U2, the second end of the same-phase input resistor Rin is connected to a reference voltage Vref, the first end of the feedback resistor Rf is connected to the non-inverting input of the operational amplifier U2, the second end of the feedback resistor Rf is connected to the output of the operational amplifier U2, the fifth resistor R5, the first diode D1, the second diode D2 and the sixth resistor R6 are connected in series, the output of the operational amplifier U2 is connected to the negative electrode of the first diode D1, the first end of the fifth resistor R5 is connected to a second high voltage VCC2, the first end of the sixth resistor R6 is grounded, the second end of the fifth resistor R5 is connected to the base of the second triode Q2, the second end of the sixth resistor R6 is connected to the base of the third triode Q3, the collector of the second triode Q2 is connected to the second high voltage VCC2, the emitter of the second triode Q2 is connected to the emitter of the third triode Q3, the collector of the third triode Q3 is grounded, and the emitter of the second triode Q2 and the collector of the third triode Q3 are respectively connected to the input of the second isolation circuit.

[0031] In the embodiment, the output voltage of the operational amplifier U2 is Vout, , where R4 is the resistance of the fourth resistor R4, Rf is the resistance of the feedback resistor Rf, Vin is the voltage input signal of the inverting input of the operational amplifier U2, and Vref is the voltage input signal of the non-inverting input of the operational amplifier U2; by adjusting the resistance of the fourth resistor R4 and the feedback resistor Rf and the reference voltage Vref, the operational amplifier U2 outputs an output signal with positive and negative alternation; and by push-pull amplification of the output signal by the second diode D2 and the third triode Q3, it is ensured that the trigger signal can be accurately transmitted in the silicon-controlled trigger circuit.

[0032] In the embodiment, the first high voltage VCC1, the second high voltage VCC2 and the reference voltage Vref are all output by the switching power supply circuit 2.

[0033] In the embodiment, the push-pull circuit 52 further comprises a first capacitor C1 and a second capacitor C2; a first end of the first capacitor C1 is connected to the collector of the second transistor Q2, a second end of the first capacitor C1 is connected to the base of the second transistor Q2, a first end of the second capacitor C2 is connected to the collector of the third transistor Q3, and a second end of the second capacitor C1 is connected to the base of the third transistor Q3; the first capacitor C1 and the second capacitor C2 can stabilize the working point of the amplification circuit, reduce self-oscillation of the circuit, and thus improve the stability of the circuit.

[0034] In the embodiment, the second transistor Q2 is an NPN type transistor, and the third transistor Q3 is a PNP type transistor.

[0035] In the embodiment, the second transistor Q2 is an NPN type transistor, and the third transistor Q3 is a PNP type transistor.

[0036] In the embodiment, the second transistor Q2 is an NPN type transistor, and the third transistor Q3 is a PNP type transistor.

[0037] In the embodiment, the first output circuit 54 comprises a third diode D3, a fourth diode D4 and an eighth resistor R8; the positive pole of the third diode D3 and the positive pole of the fourth diode D4 are respectively connected to the two ends of the first winding of the secondary side of the pulse transformer T1, the negative pole of the third diode D3 is connected to the negative pole of the fourth diode D4, the eighth resistor R8 is connected in parallel to the two ends of the fourth diode D4, the first end of the eighth resistor R8 is connected to the gate of the first thyristor SCR1, and the second end of the eighth resistor R8 is connected to the cathode of the first thyristor SCR1; the second output circuit 55 comprises a fifth diode D5, a sixth diode D6 and a ninth resistor R9; the positive pole of the fifth diode D5 and the positive pole of the sixth diode D6 are respectively connected to the two ends of the second winding of the secondary side of the pulse transformer T1, the negative pole of the fifth diode D5 is connected to the negative pole of the sixth diode D6, the ninth resistor R9 is connected in parallel to the two ends of the sixth diode D6, the first end of the ninth resistor R9 is connected to the gate of the second thyristor SCR2, and the second end of the ninth resistor R9 is connected to the cathode of the second thyristor SCR2.

[0038] In the embodiment, the signal amplified by the push-pull amplifier is isolated twice by the pulse transformer T1 to output the isolated control signal to the first output circuit 54 and the second output circuit 55.

[0039] In the embodiment, a surge protection circuit 56 is further included, the surge protection circuit 56 comprises a pressure-sensitive resistor RV1, a tenth resistor R10 and a fourth capacitor C4; the pressure-sensitive resistor RV1 is connected in parallel to the two ends of the anti-parallel thyristor, the tenth resistor R10 is connected in series with the fourth capacitor C4, and the first end of the tenth resistor R10 and the first end of the fourth capacitor C4 are respectively connected to the two ends of the pressure-sensitive resistor RV1; when there is a surge voltage input on the line, the loop in which the pressure-sensitive resistor RV1 is located is turned on to protect the anti-parallel thyristor 6 from being damaged.

[0040] Embodiment 2

[0041] The technical scheme of the utility model discloses a soft starter, comprising the trigger control circuit of embodiment 1.

[0042] The embodiments in the specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other.

[0043] It is also important to note that the use of relational terms such as first and second, and the like, are used solely to distinguish one from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0044] The above description of disclosed embodiments provides enabling concepts for practicing or using the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A trigger control circuit of a soft starter, comprising a microprocessor, a switching power supply circuit, a current detection circuit, a zero-crossing detection circuit, a silicon controlled trigger circuit and anti-parallel thyristors connected to a main circuit of the soft starter, wherein the output of the current detection circuit and the output of the zero-crossing detection circuit are connected to the input of the microprocessor respectively, and the switching power supply circuit provides working voltage for the microprocessor and the silicon controlled trigger circuit respectively, characterized in that, The thyristor trigger circuit comprises a first isolation circuit, a push-pull circuit, a second isolation circuit, a first output circuit and a second output circuit, an input end of the first isolation circuit is connected with an output end of the microprocessor, an output end of the first isolation circuit is connected with an input end of the push-pull circuit, an output end of the push-pull circuit is connected with an input end of the second isolation circuit, output ends of the second isolation circuit are connected with an input end of the first output circuit and an input end of the second output circuit respectively, and output ends of the first output circuit and the second output circuit are connected with the anti-parallel thyristor respectively.

2. The trigger control circuit of a soft starter according to claim 1, characterized in that, The first isolation circuit comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a first triode and an optical coupler, a first end of the first resistor is connected with the output end of the microprocessor, a second end of the first resistor is connected with a first end of the second resistor and a base of the first triode respectively, a second end of the second resistor and an emitter of the first triode are connected in common, a collector of the first triode is connected with a cathode of the optical coupler, a first end of the third resistor is connected with a first high level, a second end of the third resistor is connected with an anode of the optical coupler, a collector of the optical coupler is connected with a second high level, a transmitter of the optical coupler is connected with a first end of the fourth resistor, and a second end of the fourth resistor is connected with the input end of the push-pull circuit.

3. A trigger control circuit of a soft starter according to claim 2, characterized in that, The push-pull circuit comprises an operational amplifier, a same-phase input resistor, a feedback resistor, a fifth resistor, a sixth resistor, a first diode, a second diode, a second triode and a third triode, an inverting input end of the operational amplifier is connected with the second end of the fourth resistor, a first end of the same-phase input resistor is connected with a same-phase input end of the operational amplifier, a second end of the same-phase input resistor is connected with a reference voltage, a first end of the feedback resistor is connected with the same-phase input end of the operational amplifier, a second end of the feedback resistor is connected with an output end of the operational amplifier, the fifth resistor, the first diode, the second diode and the sixth resistor are connected in series, the output end of the operational amplifier is connected with a negative pole of the first diode, a first end of the fifth resistor is connected with the second high level, a first end of the sixth resistor is connected with the ground, a second end of the fifth resistor is connected with a base of the second triode, a second end of the sixth resistor is connected with a base of the third triode, a collector of the second triode is connected with the second high level, an emitter of the second triode is connected with an emitter of the third triode, a collector of the third triode is connected with the ground, and the emitter of the second triode and the collector of the third triode are connected with the input end of the second isolation circuit respectively.

4. The trigger control circuit of a soft starter according to claim 3, characterized in that, The push-pull circuit further comprises a first capacitor and a second capacitor, a first end of the first capacitor is connected with the collector of the second triode, a second end of the first capacitor is connected with the base of the second triode, a first end of the second capacitor is connected with the collector of the third triode, and a second end of the second capacitor is connected with the base of the third triode.

5. The trigger control circuit of a soft starter according to claim 3, wherein, The second triode is an NPN type triode, and the third triode is a PNP type triode.

6. The trigger control circuit of a soft starter according to claim 3, wherein, The secondary isolation circuit comprises a pulse transformer, a voltage stabilizing diode, a third capacitor and a seventh resistor; the negative electrode of the voltage stabilizing diode is connected to the emitter of the second triode and the first end of the third capacitor respectively, the positive electrode of the voltage stabilizing diode is connected to the collector of the third triode and the first end of the seventh resistor respectively, and the two ends of the primary winding of the pulse transformer are connected to the second end of the third capacitor and the second end of the seventh resistor respectively.

7. A trigger control circuit for a soft starter according to claim 6, characterized in that The anti-parallel thyristor comprises a first thyristor and a second thyristor connected in anti-parallel; the output end of the first output circuit is connected to the gate of the first thyristor and the cathode of the first thyristor, and the output end of the second output circuit is connected to the gate of the second thyristor and the cathode of the second thyristor.

8. A trigger control circuit for a soft starter according to claim 7, characterized in that, The first output circuit comprises a third diode, a fourth diode and an eighth resistor; the two ends of the first secondary winding of the pulse transformer are connected to the positive electrode of the third diode and the positive electrode of the fourth diode respectively, the negative electrode of the third diode is connected to the negative electrode of the fourth diode, the eighth resistor is connected in parallel to the two ends of the fourth diode, the first end of the eighth resistor is connected to the gate of the first thyristor, and the second end of the eighth resistor is connected to the cathode of the first thyristor; the second output circuit comprises a fifth diode, a sixth diode and a ninth resistor; the two ends of the second secondary winding of the pulse transformer are connected to the positive electrode of the fifth diode and the positive electrode of the sixth diode respectively, the negative electrode of the fifth diode is connected to the negative electrode of the sixth diode, and the ninth resistor is connected in parallel to the two ends of the sixth diode, the first end of the ninth resistor is connected to the gate of the second thyristor, and the second end of the ninth resistor is connected to the cathode of the second thyristor.

9. The trigger control circuit of a soft starter according to any one of claims 1 to 8, characterized in that, The surge protection circuit comprises a voltage-dependent resistor, a tenth resistor and a fourth capacitor; the voltage-dependent resistor is connected in parallel to the two ends of the anti-parallel thyristor, the tenth resistor and the fourth capacitor are connected in series, and the first end of the tenth resistor and the first end of the fourth capacitor are connected to the two ends of the voltage-dependent resistor respectively.

10. A soft starter characterized by The trigger control circuit comprises any one of claims 1 to 9. The trigger control circuit comprises any one of claims 1 to 9.

Images