Silicon controlled rectifier driving circuit and driving method thereof

Abstract

The present invention discloses a thyristor drive circuit and a driving method thereof. The thyristor drive circuit includes an MCU chip U1, a zero-crossing signal circuit, and a thyristor trigger circuit, and the thyristor drive circuit is used to drive a heating element Heater. A charge retention circuit is connected between a low-voltage isolation optocoupler B1 and the L line of the mains. The thyristor drive circuit and the driving method disclosed in the present invention realize automatic protection of thyristor drive under multiple types of fault conditions by cleverly setting a charge retention circuit, thereby avoiding safety hazards such as high-temperature burning; the thyristor trigger time reference is outputted by delaying the internal timer of the MCU chip to correct the zero-crossing signal delay; the reliability of the circuit triggering is ensured by decomposing the trigger time of the thyristor into multiple short-time trigger segments, while reducing electromagnetic radiation.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor power driving, and in particular relates to a thyristor driving circuit and a thyristor driving circuit driving method. Background Art

[0002] See attached figure Figure 1 , Figure 1 The traditional classic thyristor drive control scheme is shown. Specifically, when the zero-crossing signal ZeroCross_in arrives in advance, the MCU immediately sends a low-level trigger signal SCR2 after receiving the signal, driving the zero-crossing optocoupler MOC3041 to turn on and connect the peripheral power circuit.

[0003] However, the above traditional driving scheme has defects, which are briefly described as follows. Due to driving signal failures such as the control chip sending out an erroneous trigger signal, the chip program running is suspended / damaged, etc., when the trigger signal SCR2 maintains a low level for a long time, the thyristor will always be in the on state, causing the peripheral power circuit to lose control, and even causing accidents such as motor runaway and heater burning and fire.

[0004] Therefore, it is necessary to develop a safety trigger circuit that can automatically shut down the thyristor in the event of system debugging, chip failure, program failure, etc. Summary of the invention

[0005] The present invention aims at the prior art, overcomes the above-mentioned defects, and provides a thyristor drive circuit and a thyristor drive circuit driving method.

[0006] The present invention adopts the following technical solution, the thyristor drive circuit includes an MCU chip U1, a zero-crossing signal circuit, and a thyristor trigger circuit, and the thyristor drive circuit is used to drive a heating element Heater, wherein:

[0007] The circuit structure of the strong power side of the zero-crossing signal circuit includes a resistor R45, a resistor R46, a rectifier diode D1, and a low-voltage isolation optocoupler B1, one end of the resistor R46 is connected to one end of the resistor R45 through the rectifier diode D1, the other end of the resistor R45 is connected to the N line of the mains, the other end of the resistor R46 is connected to the input end of the low-voltage isolation optocoupler B1, and a charge retention circuit is connected between the low-voltage isolation optocoupler B1 and the L line of the mains;

[0008] The thyristor trigger circuit includes a thyristor TRI1, a resistor R14, a current limiting resistor R4, a low-voltage isolation optocoupler B2 and a resistor R48. The T2 end of the thyristor TRI1 is connected to the heating element Heater, the T1 end of the thyristor TRI1 is connected to the charge holding circuit, the T1 end of the thyristor TRI1 is simultaneously connected to the G end of the thyristor TRI1 through the resistor R14, the G end of the thyristor TRI1 is connected to the first end of the low-voltage isolation optocoupler B2 through the current limiting resistor R4, and the third end of the low-voltage isolation optocoupler B2 is connected to the control port of the MCU chip U1 through the resistor R48.

[0009] According to the above technical solution, the charge holding circuit is composed of a voltage stabilizing diode D6 and a capacitor C2 connected in parallel. The charge holding circuit is used to provide the thyristor trigger circuit with a charge for driving the thyristor TRI1 within a limited time. The charge provided by the charge holding circuit to the thyristor trigger circuit is limited to triggering the thyristor TRI1 within 1 to 10 AC cycles.

[0010] The rectifier diode D1 and the low-voltage isolation optocoupler B1 constitute not only the charging circuit of the charge retention circuit, but also the high-voltage current zero-crossing signal generating circuit, so that the charging current is only generated in the positive half cycle of the AC voltage, and the zero-crossing signal is also only generated in the positive half cycle of the AC voltage, and the negative half cycle circuit is cut off.

[0011] According to the above technical solution, the weak-current side circuit structure of the zero-crossing signal circuit includes a resistor R3, a resistor R5 and a transistor Q3, one end of the resistor R3 is connected to the second end of the low-voltage isolation optocoupler B1, the other end of the resistor R3 is connected to the base of the transistor Q3, the collector of the transistor Q3 is simultaneously connected to the signal input end of the MCU chip U1 and one end of the resistor R5, and the other end of the resistor R5 is grounded.

[0012] The present invention patent application also discloses a thyristor drive circuit driving method, comprising the following steps:

[0013] Step S1: applying an AC voltage to both ends of the mains L line and the N line simultaneously to form a zero-crossing signal having a lag time Δt after the zero-crossing point on the weak current side of the zero-crossing signal circuit;

[0014] Step S2: the MCU chip obtains the zero-crossing signal and starts an internal timer according to the zero-crossing signal, wherein the internal timer is used to set the thyristor triggering time reference t1 and the thyristor triggering time reference t2;

[0015] Step S3: the MCU chip outputs a control signal according to the above-mentioned thyristor triggering time reference t1 and thyristor triggering time reference t2;

[0016] Step S4: The thyristor TRI1 is driven by the charge provided by the charge holding circuit, and the thyristor TRI1 drives the heating element Heater according to the above control signal.

[0017] According to the above technical solution, step S1 is specifically implemented as follows:

[0018] An AC voltage is applied to both ends of the AC power L line and the N line at the same time. In the positive half cycle of the AC voltage, when the AC voltage exceeds the sum of the voltage Uc2 across the capacitor C2 and the forward trigger voltage Vf of the low-voltage isolation optocoupler B1, a zero-crossing signal with a delay time Δt that lags behind the zero-crossing point is formed on the weak current side of the zero-crossing signal circuit.

[0019] According to the above technical solution, the above lag time Δt is:

[0020]

[0021] According to the above technical solution, step S2 specifically includes the following steps:

[0022] Step S2.1: The MCU chip obtains the zero-crossing signal and starts an internal timer according to the zero-crossing signal;

[0023] Step S2.2: Delay (T / 2-Δt) time to generate the thyristor triggering time reference t1 of the AC voltage;

[0024] Step S2.3: Continue to delay for T / 2 time and generate the thyristor triggering time base t2 of the AC voltage.

[0025] According to the above technical solution, the control signal in step S3 is composed of at least two short-time trigger segments.

[0026] According to the above technical solution, the interval between adjacent short-time trigger segments is 30 to 200 us, and the duration of each short-time trigger segment is 10 to 100 us.

[0027] According to the above technical solution, the maximum charge amount Q provided by the charge retention circuit is:

[0028]

[0029] Wherein, U is the effective value of the voltage of the AC power supply.

[0030] The thyristor drive circuit and the driving method disclosed in the present invention have the beneficial effects of realizing automatic protection of thyristor drive under various types of fault conditions by cleverly setting a charge retention circuit, thereby avoiding safety hazards such as high-temperature burning; outputting a thyristor trigger time reference by delaying the internal timer of an MCU chip to correct the zero-crossing signal delay; and ensuring the reliability of circuit triggering by decomposing the thyristor trigger time into multiple short-time trigger segments, while reducing electromagnetic radiation. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the circuit schematic of the traditional thyristor drive solution.

[0032] Figure 2 It is a circuit schematic diagram of a part of the circuit of the preferred embodiment of the present invention.

[0033] Figure 3 It is a circuit schematic diagram of a part of the circuit of the preferred embodiment of the present invention.

[0034] Figure 4 4 is a waveform diagram of a zero-crossing signal (ZeroCrocs In) according to a preferred embodiment of the present invention.

[0035] Figure 5 It is a schematic diagram of multiple short-time trigger segments according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0036] The present invention discloses a thyristor drive circuit and a thyristor drive circuit driving method. The specific implementation of the present invention is further described below in conjunction with preferred embodiments.

[0037] See attached figure Figures 2 to 5 , Figure 2 and Figure 3 The circuit structures of the thyristor drive circuit are shown respectively, Figure 4 shows the waveform of the zero-crossing signal, Figure 5 An optimized triggering mode (multi-segment triggering segment) is shown.

[0038] Preferably, the thyristor drive circuit includes an MCU chip U1, a zero-crossing signal circuit, and a thyristor trigger circuit, and the thyristor drive circuit is used to drive a heating element Heater, wherein:

[0039] The circuit structure of the strong power side of the zero-crossing signal circuit includes a resistor R45, a resistor R46, a rectifier diode D1, and a low-voltage isolation optocoupler B1, one end of the resistor R46 is connected to one end of the resistor R45 through the rectifier diode D1, the other end of the resistor R45 is connected to the N line of the mains (AC power supply), the other end of the resistor R46 is connected to the first end of the low-voltage isolation optocoupler B1, and a charge retention circuit is connected between the low-voltage isolation optocoupler B1 and the L line of the mains (AC power supply);

[0040] The thyristor trigger circuit includes thyristor TRI1 (bidirectional thyristor), resistor R14, current limiting resistor R4 (driving current limiting resistor), low-voltage isolation optocoupler B2 and resistor R48. The T2 end of the thyristor TRI1 is connected to the heating element Heater, the T1 end of the thyristor TRI1 is connected to the charge holding circuit, the T1 end of the thyristor TRI1 is simultaneously connected to the G end of the thyristor TRI1 through the resistor R14, the G end of the thyristor TRI1 is connected to the first end of the low-voltage isolation optocoupler B2 through the current limiting resistor R4, and the third end of the low-voltage isolation optocoupler B2 is connected to the control port (SCR1, control signal) of the MCU chip U1 through the resistor R48.

[0041] It is worth mentioning that the charge retention circuit is composed of a voltage stabilizing diode D6 and a capacitor C2 in parallel, and the charge retention circuit is used to provide the thyristor trigger circuit with a charge to drive the thyristor TRI1 within a limited time, so that the thyristor TRI1 cannot be effectively turned on when the next AC half cycle arrives. This protects the heating circuit in a fault state and automatically eliminates safety hazards such as high temperature burning and fire.

[0042] In other words, the charge provided by the charge holding circuit to the thyristor trigger circuit is limited.

[0043] Furthermore, the charge provided by the charge holding circuit to the thyristor trigger circuit is limited to triggering the thyristor TRI1 within 1 to 10 AC cycles.

[0044] Preferably, the voltage stabilization threshold across the voltage stabilizing diode D6 is 12V.

[0045] It is worth mentioning that the rectifier diode D1 and the low-voltage isolation optocoupler B1 constitute not only the charging circuit of the charge retention circuit, but also the high-voltage current zero-crossing signal generating circuit. The high-voltage current sampling circuit reduces the static power consumption of the zero-crossing signal circuit by half.

[0046] In other words, the above-mentioned high-voltage current zero-crossing signal generating circuit enables the charging current to be generated only in the positive half cycle of the AC power supply, and the zero-crossing signal is also generated only in the positive half cycle of the AC voltage, and the negative half cycle circuit is cut off, which meets the green and environmental protection energy-saving requirements.

[0047] It is worth mentioning that the patent application of the present invention also discloses a thyristor drive circuit driving method based on the above thyristor drive circuit, comprising the following steps:

[0048] Step S1: applying an AC voltage to both ends of the mains L line and the N line simultaneously to form a zero-crossing signal (ZeroCross in) having a lag time Δt after the zero-crossing point on the weak current side of the zero-crossing signal circuit;

[0049] Step S2: the MCU chip obtains the zero-crossing signal and starts an internal timer according to the zero-crossing signal, wherein the internal timer is used to set the thyristor triggering time reference t1 and the thyristor triggering time reference t2;

[0050] Step S3: the MCU chip outputs a control signal (SCR1) according to the above-mentioned thyristor triggering time reference t1 and thyristor triggering time reference t2;

[0051] Step S4: The thyristor TRI1 is driven by the charge provided by the charge holding circuit, and the thyristor TRI1 drives the heating element Heater according to the above control signal.

[0052] Preferably, step S1 is specifically implemented as follows:

[0053] An AC voltage is applied to both ends of the AC power L line and the N line at the same time. In the positive half cycle of the AC voltage, when the AC voltage exceeds the sum of the voltage Uc2 across the capacitor C2 and the forward trigger voltage Vf of the low-voltage isolation optocoupler B1, a zero-crossing signal with a delay time Δt that lags behind the zero-crossing point is formed on the weak current side of the zero-crossing signal circuit.

[0054] Preferably, the above lag time Δt is:

[0055]

[0056] Preferably, in step S1, due to the high voltage current sampling circuit, a zero-crossing signal (ZeroCross in) is generated in the positive half cycle of the current and voltage and is cut off in the negative half cycle of the current and voltage, so as to reduce static power consumption.

[0057] Preferably, step S2 specifically includes the following steps:

[0058] Step S2.1: The MCU chip obtains the zero-crossing signal and starts an internal timer according to the zero-crossing signal;

[0059] Step S2.2: Delay (T / 2-Δt) time to generate the thyristor triggering time reference t1 of the AC voltage;

[0060] Step S2.3: Continue to delay for T / 2 time and generate the thyristor triggering time base t2 of the AC voltage.

[0061] The thyristor triggering time reference t1 in step S2.2 is located in the negative half cycle of the AC voltage.

[0062] The thyristor triggering time reference t2 in step S2.3 is located in the positive half cycle of the AC voltage.

[0063] The period T of the AC voltage is the average value of multiple zero-crossing signal intervals. For example, if 5 zero-crossing signals are sampled within the last 80 milliseconds, the period T = 80ms / (5-1) = 20ms.

[0064] Preferably, the control signal (SCR1) in step S3 is composed of at least two short-time trigger segments.

[0065] In other words, due to the signal error of the actual zero-crossing circuit, AC voltage fluctuation, grid interference, and the accuracy of the internal timer, the trigger time base of the thyristor may be inaccurate, leading or lagging behind the actual zero-crossing signal by dozens of microseconds. When it is ahead, it will cause the thyristor to trigger missed, or too much trigger delay will cause a large disturbance power conduction component. This multi-segment triggering method ensures reliable circuit triggering and minimizes electromagnetic radiation.

[0066] The interval between adjacent short-time trigger segments is tens of microseconds, preferably 30 to 200 us.

[0067] The duration of each short-time trigger segment is preferably 10 to 100 us.

[0068] Preferably, the charge provided by the charge holding circuit in step S4 is only used to trigger the thyristor TRI1 within one half cycle of the AC voltage.

[0069] The maximum charge Q provided by the charge retention circuit is:

[0070]

[0071] Where U is the effective value of the voltage of the AC power supply. When the power supply is 220 volts, the frequency is 50 Hz.

[0072] When resistance R45=R46=51K, the maximum charge Q on capacitor C2 is ≌19.4uQ.

[0073] When the voltage threshold across the voltage stabilizing diode D6 is 12V, the capacitance value of C2 is C=Q / 12=1.6uF. Considering the deviation of the actual capacitance and the requirement for the stability of the driving voltage, C2>=4.7uF is selected.

[0074] According to the above preferred embodiment, the working principle of the thyristor driving circuit disclosed in the patent application of the present invention is as follows.

[0075] See attached figure Figure 2 The thyristor driving circuit includes an MCU chip U1, a zero-crossing signal circuit, and a thyristor triggering circuit. The thyristor driving circuit is used to drive the thyristor TRI1 (ie, the heating element).

[0076] See attached figure Figure 3 The circuit structure of the strong current side of the zero-crossing signal circuit includes a resistor R45, a resistor R46, a rectifier diode D1, a low-voltage isolation optocoupler B1, a voltage regulator tube D6, and a capacitor C2;

[0077] The weak current side circuit structure of the zero-crossing signal circuit includes a resistor R3, a resistor R5 and a transistor Q3;

[0078] The thyristor trigger circuit includes a thyristor TRI1, a resistor R14, a current limiting resistor R4, a low voltage isolation optocoupler B2 and a resistor R48.

[0079] See attached figure Figure 4 When an AC voltage is applied to L and N, in the positive half cycle of the AC voltage, when the AC voltage exceeds the sum of the voltage Uc2 across the capacitor C2 and the forward trigger voltage Vf of the low-voltage isolation optocoupler B1, a zero-crossing signal with a delayed zero-crossing point appears on the weak current side, and the lag time Δt is:

[0080]

[0081] When the control chip MCU receives the zero-crossing signal after a delay of Δt, an internal timer is immediately started, and the delay (T / 2-Δt) sends out the negative half-cycle thyristor trigger time reference t1; then it continues to delay T / 2 and sends out the positive half-cycle thyristor trigger time reference t2, so as to correct the delay of the zero-crossing signal, reduce the starting current in the circuit, and reduce conducted interference and electromagnetic radiation.

[0082] The cycle T of the AC power supply is the average value of multiple zero-crossing signal intervals. For example, if 5 zero-crossing signals are sampled within the last 80 milliseconds, the cycle T = 80ms / (5-1) = 20ms.

[0083] The driving charge of the thyristor comes from the zero-crossing signal circuit, and the charge generated by it can only be used to drive the thyristor for a limited time; when the control signal SCR1 fails, showing that it maintains a high level, or maintains a low level, or is continuously pulsed, the charge stored on C2 is quickly exhausted and the thyristor cannot be triggered within the next half cycle of the AC voltage, playing an automatic protection role under a single software or hardware drive failure. In one cycle, the maximum charge Q stored in the zero-crossing signal circuit (charge retention circuit) is:

[0084]

[0085] Where U is the effective value of the voltage of the AC power supply. When the power supply is 220 volts, the frequency is 50 Hz.

[0086] When resistance R45=R46=51K, the maximum charge Q on capacitor C2 is ≌19.4uQ.

[0087] When the voltage threshold across the voltage stabilizing diode D6 is 12V, the capacitance value of C2 is C=Q / 12=1.6uF. Considering the deviation of the actual capacitance and the requirement for the stability of the driving voltage, C2>=4.7uF is selected.

[0088] It is worth mentioning that selecting an appropriate thyristor model and drive current limiting resistor R4 can effectively realize automatic shutdown of thyristor output when the drive signal fails.

[0089] For example, if R4=330Ω is selected, the thyristor trigger current is approximately equal to 12V / 510Ω=36mA, and a thyristor with a trigger current of 30mA is selected. The maximum time that the charge on capacitor C2 can maintain the trigger current is 19.4uQ / 30mA=630us. When the low level maintenance time of the trigger signal SCR in a cycle T exceeds 630us, the charge at both ends of capacitor C2 is exhausted, and the thyristor will not be effectively opened when the next AC half-wave arrives. It protects the heating circuit in a fault state and automatically eliminates safety hazards such as high temperature burning and fire.

[0090] See attached figure Figure 5 , divide the trigger time of thyristor TRI1 into more than one short-time trigger segments, and send out a thyristor drive trigger signal every few tens of microseconds. Generally, the time of each trigger segment is about 10 to 100us, and the interval between each trigger segment is 30 to 200us.

[0091] Due to factors such as signal errors in the actual zero-crossing circuit, AC voltage fluctuations, grid interference, and the accuracy of the internal timer, the triggering time reference of the thyristor may be inaccurate, leading or lagging behind the actual zero-crossing signal by dozens of microseconds. When ahead, it will cause the thyristor to trigger missed, or too much trigger delay will cause a large disturbance power conduction component. The above multi-segment triggering method ensures reliable circuit triggering and minimizes electromagnetic radiation.

[0092] Furthermore, the zero-crossing signal circuit rectifier diode D1 and the low-voltage isolation optocoupler B1 constitute not only the charging circuit of the charge retention circuit, but also the high-voltage current zero-crossing signal generating circuit, so that the charging current is only generated in the positive half cycle of the AC voltage, and the zero-crossing signal is also only generated in the positive half cycle of the AC voltage, and the negative half cycle circuit is cut off, so that the static power consumption of the zero-crossing circuit is reduced by half, which meets the energy-saving requirements of green environmental protection.

[0093] For those skilled in the art, it is still possible to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A thyristor drive circuit, characterized in that: It includes an MCU chip U1, a zero-crossing signal circuit, and a thyristor trigger circuit. The thyristor drive circuit is used to drive a heating element Heater, wherein: The circuit structure of the strong power side of the zero-crossing signal circuit includes a resistor R45, a resistor R46, a rectifier diode D1, and a low-voltage isolation optocoupler B1, one end of the resistor R46 is connected to the positive electrode of the rectifier diode D1, the negative electrode of the rectifier diode D1 is connected to one end of the resistor R45, the other end of the resistor R45 is connected to the N line of the mains, the other end of the resistor R46 is connected to the 4th end of the low-voltage isolation optocoupler B1, and a charge holding circuit is connected between the 3rd end of the low-voltage isolation optocoupler B1 and the L line of the mains; The thyristor trigger circuit includes a thyristor TRI1, a resistor R14, a current limiting resistor R4, a low-voltage isolation optocoupler B2 and a resistor R48, one end of the heating element Heater is connected to the N line of the mains, the other end of the heating element Heater is connected to the T2 end of the thyristor TRI1, the T1 end of the thyristor TRI1 is connected to the charge holding circuit, the T1 end of the thyristor TRI1 is simultaneously connected to one end of the resistor R14, the other end of the resistor R14 is connected to the G end of the thyristor TRI1, the G end of the thyristor TRI1 is connected to one end of the current limiting resistor R4, the other end of the current limiting resistor R4 is connected to the first end of the low-voltage isolation optocoupler B2, the third end of the low-voltage isolation optocoupler B2 is connected to one end of the resistor R48, and the other end of the resistor R48 is connected to the control port of the MCU chip U1; The charge holding circuit is composed of a voltage stabilizing diode D6 and a capacitor C2 connected in parallel. The charge holding circuit is used to provide the thyristor trigger circuit with a charge for driving the thyristor TRI1 within a limited time. The charge provided by the charge holding circuit to the thyristor trigger circuit is limited to triggering the thyristor TRI1 within 1 to 10 AC cycles. The rectifier diode D1 and the low-voltage isolation optocoupler B1 constitute not only the charging circuit of the charge retention circuit, but also the high-voltage current zero-crossing signal generating circuit, so that the charging current is only generated in the positive half cycle of the AC voltage, and the zero-crossing signal is also only generated in the positive half cycle of the AC voltage, and the negative half cycle circuit is cut off.

2. The thyristor drive circuit according to claim 1, characterized in that: The weak-current side circuit structure of the zero-crossing signal circuit includes a resistor R3, a resistor R5 and a transistor Q3, one end of the resistor R3 is connected to the second end of the low-voltage isolation optocoupler B1, the other end of the resistor R3 is connected to the base of the transistor Q3, the collector of the transistor Q3 is simultaneously connected to the signal input end of the MCU chip U1 and one end of the resistor R5, and the other end of the resistor R5 is grounded.

3. The thyristor driving circuit driving method of the thyristor driving circuit according to any one of claims 1 to 2, characterized in that: The following steps are involved: Step S1: applying an AC voltage to both ends of the mains L line and the N line simultaneously to form a zero-crossing signal having a lag time Δt after the zero-crossing point on the weak current side of the zero-crossing signal circuit; Step S2: the MCU chip obtains the zero-crossing signal and starts an internal timer according to the zero-crossing signal, wherein the internal timer is used to set the thyristor triggering time reference t1 and the thyristor triggering time reference t2; Step S3: the MCU chip outputs a control signal according to the above-mentioned thyristor triggering time reference t1 and thyristor triggering time reference t2; Step S4: the thyristor TRI1 is driven by the charge provided by the charge holding circuit, and the thyristor TRI1 drives the heating element Heater according to the above control signal.

4. The thyristor driving circuit driving method according to claim 3, characterized in that: Step S1 is specifically implemented as follows: an AC voltage is simultaneously applied to both ends of the AC power L line and the N line. In the positive half cycle of the AC voltage, when the AC voltage exceeds the sum of the voltage Uc2 across the capacitor C2 and the forward trigger voltage Vf of the low-voltage isolation optocoupler B1, a zero-crossing signal with a lag time Δt that lags behind the zero-crossing point is formed on the weak current side of the zero-crossing signal circuit.

5. The thyristor driving circuit driving method according to claim 3, characterized in that: Step S2 specifically includes the following steps: Step S2.1: The MCU chip obtains the zero-crossing signal and starts an internal timer according to the zero-crossing signal; Step S2.2: Delay (T / 2-Δt) time to generate the thyristor triggering time reference t1 of the AC voltage; Step S2.3: Continue to delay for T / 2 time, and send out the thyristor triggering time reference t2 of the AC voltage; Wherein, T is the period of the AC voltage, and T is the average value of multiple zero-crossing signal intervals.

6. The thyristor driving circuit driving method according to claim 3, characterized in that: The control signal in step S3 is composed of at least two short-time trigger segments.

7. The thyristor driving circuit driving method according to claim 6, characterized in that: The interval between adjacent short-time trigger segments is 30 to 200 us, and the duration of each short-time trigger segment is 10 to 100 us.

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