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CN-122000843-A - Multistage energy transfer's anti strong surge protection circuit

CN122000843ACN 122000843 ACN122000843 ACN 122000843ACN-122000843-A

Abstract

The invention discloses a multistage energy transfer strong surge protection circuit which comprises a TVS tube network, a first-stage thyristor network and a second-stage thyristor network which are sequentially arranged, wherein the first-stage thyristor network is used for discharging surges exceeding first-stage peak voltage and current, the second-stage thyristor network is used for discharging surges exceeding second-stage peak voltage and current, the second-stage peak voltage and current are larger than the first-stage peak voltage and current, and the TVS tube network is used for discharging residual surge peak energy. The anti-strong surge protection circuit with the multistage energy transfer function is used for preventing surge impact from a power grid, a two-stage thyristor network is used for realizing clamp protection when voltage and current peak values are generated, and an auxiliary diode is additionally arranged in a feedback protection loop to realize overvoltage protection caused by surge impact. The protection circuit solves the problem that the inductive load equipment suffers from power grid surge impact when being started and stopped, and has the advantages of simple circuit structure, low cost and strong universality.

Inventors

  • YAN XUHUA
  • WANG XIAONAN
  • SU WEI
  • LEI JIANMING

Assignees

  • 苏州明源创半导体有限公司

Dates

Publication Date
20260508
Application Date
20260316

Claims (8)

  1. 1. The multistage energy transfer anti-strong surge protection circuit is characterized by comprising a TVS (transient voltage suppression) network, a first-stage thyristor network and a second-stage thyristor network which are sequentially arranged, wherein: The first-stage thyristor network is used for discharging surges exceeding peak voltages and peak currents corresponding to the first-stage protection, the second-stage thyristor network is used for discharging surges exceeding peak voltages and peak currents corresponding to the second-stage protection, the peak voltages and peak currents of the second-stage protection are both larger than those of the first-stage protection, and the TVS network is used for discharging residual surge peak energy.
  2. 2. The anti-strong surge protection circuit according to claim 1, wherein the first stage thyristor network comprises voltage dividing resistors R11 and R12, dead load R13, thyristor DIAC1, bidirectional thyristor VT1, and a high frequency filter capacitor, R11 and R12 are connected in series between L and N lines, the filter capacitor is connected in parallel across R12, R13 and bidirectional thyristor VT1 are connected in series between L and N lines, a control terminal of bidirectional thyristor VT1 is connected to an anode of thyristor DIAC1, and a cathode of thyristor DIAC1 is connected between resistors R11 and R12.
  3. 3. The anti-strong surge protection circuit of claim 2, wherein the first stage thyristor network is configured to break down DIAC1, turning on VT1 at 280Vac and peak current 100A.
  4. 4. The anti-strong surge protection circuit according to claim 2, wherein the second stage thyristor network comprises voltage dividing resistors R21 and R22, dead load R23, thyristor DIAC2, bidirectional thyristor VT2, and a high frequency filter capacitor, R21 and R22 are connected in series between L and N lines, the filter capacitor is connected in parallel across R22, R23 and bidirectional thyristor VT2 are connected in series between L and N lines, the control terminal of bidirectional thyristor VT2 is connected to the anode of thyristor DIAC2, and the cathode of thyristor DIAC2 is connected between resistors R21 and R22.
  5. 5. The anti-strong surge protection circuit of claim 4, wherein the second stage thyristor network is configured to break down DIAC2, turning on VT2 at 300Vac and peak current 1 kA.
  6. 6. The anti-strong surge protection circuit according to claim 4, wherein the TVS network comprises a varistor MOV1 and a TVS tube 1 which are connected in series and are arranged between an L line and an N line, a varistor MOV2 and a TVS tube 2 which are connected in series and are arranged between the L line and a ground line, a varistor MOV3 and a TVS tube 3 which are connected in series and are arranged between the N line and the ground line, and rated current capacity and maximum continuous working voltage of the varistor MOV1, the varistor MOV2 and the varistor MOV3 are larger than peak voltage and peak current corresponding to the second-stage protection.
  7. 7. The anti-strong surge protection circuit of any of claims 1-6, further comprising an auxiliary diode network in a feedback protection loop comprising a bootstrap diode D1, an auxiliary clamp diode D2, detection branch resistances R1, R2, R3, and a filter capacitance; The device comprises a control chip, a filter capacitor, a voltage sampling circuit, a voltage detection circuit, a voltage sampling circuit, a voltage detection circuit and a voltage detection circuit, wherein D1 is used for providing bootstrap power supply for the control chip, D2 is used for clamping Vaux terminal voltage of the control chip and preventing overvoltage breakdown of the control chip caused by surge impact, R1/R2/R3 is used for voltage sampling and surge state detection, and the filter capacitor is used for providing stable direct current power supply.
  8. 8. The anti-strong surge protection circuit according to claim 7, wherein in the auxiliary diode network, the cathode of the diode D1 is connected to the VCC interface of the control chip, the anode of the diode D1 is connected to the anode of the diode D2, the cathode of the diode D1 is sequentially connected in series with the resistors R2 and R3 and then connected to the GND interface of the control chip, the VS interface of the control chip is connected between R2 and R3, the resistor R1 is connected in parallel with the diode D2, and the two filter capacitors are connected in parallel between the VCC interface and the GND interface of the control chip.

Description

Multistage energy transfer's anti strong surge protection circuit Technical Field The invention relates to a multistage energy transfer strong surge protection circuit, and belongs to the technical field of switching power supplies. Background During steady state operation of electrical equipment having a large number of inductive coils inside of electric welder, motor and compressor (air conditioner, refrigerator) etc. current flows through the coils creating a magnetic field. However, when it is switched to a start-stop transient, the abrupt switching on or off of the circuit causes a sharp change in the magnetic field according to lenz's law in order to maintain the original current, and thus causes an extremely high back electromotive force to be generated in the inductor coil in an extremely short time (typically in the order of microseconds to milliseconds). In theory, the peak voltage of the back electromotive force may reach 3kV or more, that is, surge voltage. Assuming a clamping voltage of 1kV, a peak current of 5kA, and a duration of 50 μs, the energy e≡1kV 5 kA-6s=250j. In practice, the energy is affected by the overall loop impedance, and even higher surge voltages may be generated due to factors such as line distribution parameters, switching speed, and arc re-ignition. For a single high power welder, the surge energy generated by one switching action is typically between tens to hundreds of joules. If multiple welding machines are operated simultaneously or frequently at the same node of the grid, the accumulated energy may be very large. In addition, a large surge current is generated with a high surge voltage. In the main circuit of the device or in the associated auxiliary circuit, the breakdown or energy release process caused by the off overvoltage may be accompanied by an in-rush current having a peak value between 3kA and 10 kA. Such current pulses have extremely strong instantaneous power with very short rise times, typically within 0.1 to 10 mus, and the duration of the entire pulse (often measured as half-width time) is in the range of 20 to 200 mus. This means that the system needs to withstand a high voltage, high current combined impact in the us to hundred us time scale, with extremely high power densities, which are typical of high frequency, high energy short pulse events. The rapid inflow of the instantaneous surge energy can lead to the bulge and tube explosion of an electrolytic capacitor or a common mode inductor in the equipment, as shown in fig. 1, so that frequent machine explosion is directly caused, and on the other hand, the instantaneous surge energy can be reversely injected into a power grid to affect other equipment on the same line, and finally, the efficiency and the safety in working are seriously reduced. Therefore, in the design practice of protection circuits, engineers often need to consider higher safety margins, design the capability to withstand transient voltages to levels of 6kV or even higher, to ensure that the system remains highly reliable under extreme or unpredictable conditions. The surge protection circuit shown in fig. 2 is connected in parallel with two ends of an input line of the device by using piezoresistors, and presents large impedance when the line voltage is in a normal range, when the surge voltage enters the device, the line voltage exceeds a tolerance, the impedance of the piezoresistors is rapidly reduced, and the surge current is absorbed, so that the line voltage is prevented from being too high. However, the varistor has a slow response speed and cannot suppress the voltage quickly. As shown in fig. 3, the surge protection circuit scheme commonly adopted in the industry is a varistor+tvs (transient voltage suppression diode), and has the advantages of extremely high response speed (generally ns-level), precise clamping, no aging problem, but limited protection effect and relatively high cost. In addition, in the fields of ammeter metering and the like, the electric equipment has the function of double output of alternating current and direct current on the premise of inputting alternating current commercial power. In the application of direct current output, surge energy can also generate pulse and peak oscillation on output voltage, and the reliable operation of the subsequent stage load equipment is endangered, so that the feedback protection in consideration of the surge energy is of great significance. In surge testing, such transient pulses are often simulated using 8/20 μs current waves and 1.2/50 μs voltage waves. Specifically, "8/20 μs" describes the waveform characteristics of a current pulse, i.e., the time required for the current value to rise from 10% peak to 90% peak, or approximately 80% peak, to be 8 μs, and the half-peak width (i.e., the pulse duration, meaning the time that the peak falls to 50% peak) to be 20 μs. The waveform can better simulate surge current impact caused by indirect lightning strike or hig