Anti-series bidirectional constant current source clamping circuit, AC SSPC and control method

Abstract

The invention discloses an anti-series bidirectional constant current source clamping circuit, an alternating current SSPC and a control method.The clamping circuit is of a symmetrical structure and comprises an upper power tube, a lower power tube, a first negative feedback resistor and a second negative feedback resistor, the drain electrode of the upper power tube is connected with the power output end of an alternating current solid state power controller, and the drain electrode of the lower power tube is connected with the power output end of the alternating current solid state power controller; the source electrode of the upper power tube is connected with one end of the first negative feedback resistor, the drain electrode of the lower power tube is connected with the power ground of the AC solid state power controller, and the source electrode of the lower power tube is connected with one end of the second negative feedback resistor. The other end of the first negative feedback resistor is connected with the other end of the second negative feedback resistor and then connected with the same analog ground, and the grid electrodes of the upper power tube and the lower power tube are connected and then connected with the same control instruction. The clamping circuit provided by the invention not only provides a path for leakage current, but also greatly reduces the equivalent resistance of the load side, and realizes constant-current discharge of the capacitive load while reducing the voltage of the load side.

Description

Technical Field

[0001] The present invention relates to an anti-series bidirectional constant current source clamping circuit, an AC SSPC and a control method, and belongs to the fields of power electronics technology and electrical engineering technology. Background Art

[0002] Solid-State Power Controllers (SSPCs) use power semiconductor devices as switches, integrating the switching control functions of relays and the protection functions of circuit breakers. They have the advantages of fast response, no arcing, no mechanical contacts, low on-state power consumption, strong load adaptability, and high reliability. They are the key core of advanced solid-state power distribution systems.

[0003] In aviation solid-state power distribution systems, when an AC SSPC is unloaded, the equivalent resistance on the load side is much greater than when the AC SSPC is off. This leakage current can cause a "pseudo-voltage" phenomenon on the load side, close to the supply voltage. Furthermore, when a capacitive load is connected to the AC SSPC, leakage current continuously charges the load side in the off state, causing a continuous voltage buildup on the load side. This problem is exacerbated as system voltage levels increase, posing a serious threat to system operation and personnel safety. Therefore, in-depth research on the clamping circuit of an AC SSPC has important theoretical and engineering value.

[0004] The conventional solution is to connect a bleeder resistor in parallel with the load. When the AC SSPC is turned off, the bleeder resistor is connected to the load side and dissipates the energy of the load capacitor in the bleeder resistor. In terms of discharge safety and stability, this solution has a current spike during the initial discharge, followed by an exponential decay of the discharge current, resulting in low safety and stability during the discharge process. In terms of clamping voltage, the parallel bleeder resistor solution ultimately clamps the load-side voltage to below 3V, resulting in a high clamping voltage. In terms of discharge time, the parallel bleeder resistor discharge time is always longer than 100ms. In terms of volume and weight, since all energy is dissipated in the bleeder resistor, the resistor is relatively large, resulting in a large total volume and weight for the power device.

[0005] In order to further reduce the clamping voltage and discharge time and improve the safety of the discharge process, it is necessary to further optimize the clamping circuit of the AC SSPC. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to address the defects and shortcomings in the aforementioned background and provide an anti-series bidirectional constant current source clamping circuit, AC SSPC and control method. These circuits can not only clamp the load voltage to below 1V, but also provide an energy release channel for the load capacitor, and achieve controllable energy release time, with the discharge time being controllable within 10ms.

[0007] In order to solve the above technical problems, an embodiment of the present application first provides an anti-series bidirectional constant current source clamping circuit, which is applied to an AC solid-state power controller, and is characterized in that the clamping circuit is connected in parallel between the power output end and the power ground of the AC solid-state power controller. The clamping circuit adopts a symmetrical structure, including an upper power tube, a lower power tube, a first negative feedback resistor, and a second negative feedback resistor. The drain of the upper power tube is connected to the power output end of the AC solid-state power controller, the source of the upper power tube is connected to one end of the first negative feedback resistor, the drain of the lower power tube is connected to the power ground of the AC solid-state power controller, the source of the lower power tube is connected to one end of the second negative feedback resistor, the other end of the first negative feedback resistor is connected to the other end of the second negative feedback resistor and then connected to the same analog ground, and the gates of the upper power tube and the lower power tube are connected and then connected to the same control instruction.

[0008] An embodiment of the present application also provides an AC solid-state power controller, including a main power circuit, a clamping circuit and a clamping circuit control logic circuit, characterized in that the clamping circuit is connected in parallel between the power output end and the power ground of the AC solid-state power controller, and the clamping circuit adopts a symmetrical structure, including an upper power tube, a lower power tube, a first negative feedback resistor, and a second negative feedback resistor. The source of the upper power tube is connected to one end of the first negative feedback resistor, the source of the lower power tube is connected to one end of the second negative feedback resistor, the other end of the first negative feedback resistor is connected to the other end of the second negative feedback resistor and then connected to the same analog ground, and the gates of the upper power tube and the lower power tube are connected and then connected to the same control instruction output by the clamping circuit control logic circuit.

[0009] Preferably, the main power circuit includes a first power tube and a second power tube connected in anti-series, the drain of the first power tube serves as the power input end of the AC solid-state power controller and is connected to the AC power supply, the drain of the second power tube serves as the power output end of the AC solid-state power controller and is connected to the clamping circuit and the load, the gate of the first power tube and the source of the second power tube are connected to the same analog ground, and the gate of the first power tube and the gate of the second power tube are connected to different switching instructions.

[0010] Preferably, the clamp circuit control logic circuit includes a NOR gate, an OR gate and an RS trigger, the two input ends of the NOR gate are respectively connected to the switch instructions of the first power tube and the second power tube, the four input ends of the OR gate are respectively connected to the switch instructions of the first power tube and the second power tube, and the positive and negative logic signals of the load current direction; the output end of the NOR gate is connected to the RS trigger The output of the OR gate is connected to the RS flip-flop end, the RS flip-flop The terminal outputs the control instruction.

[0011] The present application also provides a control method for the AC solid-state power controller, which includes: When the AC solid-state power controller is turned on: in the positive half cycle of the AC power supply voltage, the second power tube is turned on first, and after the voltage crosses zero, the first power tube is turned on, and the upper power tube and the lower power tube are turned off; in the negative half cycle of the AC power supply voltage, the first power tube is turned on first, and after the voltage crosses zero, the second power tube is turned on, and the upper power tube and the lower power tube are turned off; When the AC solid-state power controller is turned off: in the positive half cycle of the load current, the second power tube is turned off first, and the first power tube is turned off after the current passes through zero, and the upper power tube and the lower power tube are turned on; in the negative half cycle of the load current, the first power tube is turned off first, and the second power tube is turned off after the current passes through zero, and the upper power tube and the lower power tube are turned on.

[0012] The present invention has the following beneficial effects: 1. The clamping circuit of the present invention can clamp the load terminal voltage of the AC solid-state power controller to within 1V when it is unloaded; 2. The clamping circuit of the present invention provides an energy release path for the capacitive load, preventing the existence of leakage current from causing continuous accumulation of voltage on the load side. The capacitive load energy discharge current is stable without current spikes, and the discharge current and discharge time are controllable. The discharge time is reduced to less than 10ms, effectively improving the safety of the AC solid-state power controller. 3. The two MOSFETs in the clamping circuit of the present invention share the same turn-on signal, which simplifies control; 4. The clamping circuit of the present invention only requires two enhancement-mode MOSFETs, and the total volume of the power device is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is an AC SSPC circuit diagram based on an anti-series bidirectional constant current source clamp circuit; Figure 2 It is the working mode diagram of the anti-series bidirectional constant current source clamp circuit; Figure 3 This is the overall control timing diagram of the AC SSPC based on the anti-series bidirectional constant current source clamp circuit; Figure 4 This is the working timing diagram of the anti-series bidirectional constant current source clamp circuit; Figure 5 This is the operating circuit diagram when the load is unloaded and the SSPC is in steady-state off condition; Figure 6 This is the operating circuit diagram of the capacitive load and the SSPC in the steady-state off condition; Figure 7 This is the clamp circuit control logic circuit diagram. DETAILED DESCRIPTION

[0014] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0015] Example 1 This embodiment provides an anti-series bidirectional constant current source clamping circuit, and provides an AC solid-state power controller based on the anti-series bidirectional constant current source clamping circuit.

[0016] like Figure 1 As shown, the anti-series bidirectional constant current source clamp circuit of this embodiment is connected in parallel to the power output end of the AC solid-state power controller. Powerout and power ground PGND The clamp circuit adopts a symmetrical structure, including the upper power tube S aux1 , lower power tube S aux2 , the first negative feedback resistor R 1. Second negative feedback resistor R 2. Upper power tube S aux1 The drain is connected to the power output terminal of the AC solid-state power controller Powerout, Upper power tube S aux1 The source and the first negative feedback resistor R 1 is connected to the lower power tube S aux2 The drain is connected to the power ground of the AC solid-state power controller PGND, Lower power tube S aux2 The source and the second negative feedback resistor R 2 is connected to the first negative feedback resistor R The other end of 1 is connected to the second negative feedback resistor R 2 and then connect the other end to the same analog ground AGND 2. Upper power tube S aux1 , lower power tube S aux2 After the gates are connected, connect the same control instruction CMD aux Among them, the upper power tube S aux1 , lower power tube S aux2 Both are enhancement mode MOSFETs.

[0017] like Figure 1 As shown, the AC SSPC based on the anti-series bidirectional constant current source clamp circuit of this embodiment is composed of an AC power supply V SThe AC SSPC power circuit consists of three parts: the main power circuit, the anti-series bidirectional constant current source clamping circuit and the load. Figure 7 The clamp circuit shown controls the logic circuit.

[0018] The main power circuit of AC SSPC consists of the first power tube S upp , the second power tube S low It is composed of two identical N-channel enhancement-type Si MOSFETs connected in anti-series. upp The drain of the AC solid-state power controller is connected to the AC power supply as the power input terminal, and the second power tube S low The drain of the AC solid-state power controller is connected to the clamping circuit and the load as the power output terminal. upp The gate of the second power tube S low The source of the first power tube S is connected to the same analog ground AGND1. upp The gate of the first switching command CMD is connected upp , the second power tube S low The gate of the second switch command CMD is connected low .

[0019] like Figure 7 The clamp circuit control logic circuit of this embodiment includes an RS trigger composed of a NOR gate OR1, an OR gate OR2 and two NAND gates. The two input terminals of the NOR gate OR1 are respectively connected to the first switch instruction CMD. upp , the second switch command CMD low The four input terminals of the OR gate OR2 are connected to the first switch command CMD upp , the second switch command CMD low , and load current direction positive and negative logic signals I + and I -. I +、 I - are logic signals indicating the direction of load current, high level indicates valid, I + indicates the direction of current is from the power input terminal of AC SSPC Powerin Flow to the power output end Powerout , I - indicates the opposite direction of current. The output of the NOR gate OR1 is connected to the RS trigger The output of the OR gate OR2 is connected to the RS trigger The RS flip-flop Output clamp circuit control instruction CMD aux .

[0020] Table 1 Clamp circuit control logic circuit function table

[0021] Figure 2 This is the working mode diagram of the anti-series bidirectional constant current source clamp circuit. In the capacitive load energy release stage, according to the direction of the load discharge current, its working mode is divided into two categories: forward constant current discharge and reverse constant current discharge.

[0022] Mode I: Forward constant current discharge Assume that the load voltage is V load Positive, that is, the power output end of the AC solid-state power controller Powerout Potential higher than power ground PGND , the control instruction CMD of the clamp circuit aux Jumping from low level to high level, the same driving voltage V drv (constant 14V) applied to the gate of the upper / lower power tube and the analog ground AGND 2, the actual power tube gate-source voltage V GS Greater than the threshold voltage V TH After that, the discharge current in the circuit gradually increases from zero. R 1, as the discharge current increases, the voltage divider on the resistor V R1 Also increases linearly, the upper power tube S aux1 Gate-source voltage V GS1 Reduce, thereby controlling the drain-source current of the power tube I D1 Decreases, and after a certain period of time the circuit current reaches a constant value I CCS+ At this time, the upper power tube S aux1 Working in the saturation region, with the first negative feedback resistor R 1 forms a forward constant current source; at the same time, due to the second negative feedback resistor R 2, the lower power tube S aux2 Gate-source voltage V GS2 Increase, at this time the lower power tube S aux2 It is in a fully conductive state and works in the variable resistance area.

[0023] By the upper power tube S aux1 and the first negative feedback resistor R 1 Constant current source I CCS+ , which can be expressed as:

[0024] in, μ 0 is the electron mobility, C ox is the gate oxide capacitance per unit area, W is the channel width, L is the effective channel length. When the enhancement mode MOSFET device is determined, the forward constant current I CCS+ The first negative feedback resistor R 1 only confirmed.

[0025] Mode II: Reverse constant current discharge Assume that the load voltage is V load Negative, that is, the power output end of the AC solid-state power controller Powerout Potential lower than power ground PGND , the control instruction CMD of the clamp circuit aux Jumping from low level to high level, the same driving voltage V drv (constant 14V) applied to the gate of the upper / lower power tube and the analog ground AGND 2, the power tube gate-source voltage V GS Raised to the threshold voltage V TH When the discharge current in the circuit starts from zero and gradually increases. R 2, the voltage across the resistor V R2 As the discharge current increases, it increases linearly, resulting in the lower power tube S aux2 Gate-source voltage V GS2 Reduce, and thus control the drain-source current of the power tube I D2 Decreases, and after a certain period of time the circuit current reaches a constant value I CCS- At this time, the lower power tube S aux2 Working in saturation region, with the second negative feedback resistor R 2 forms a reverse constant current source; at the same time, the first negative feedback resistor R 1 makes the upper power tube S aux1 Gate-source voltage V GS1 Increase, at this time the upper power tube S aux1 It is in a fully conductive state and works in the variable resistance area.

[0026] The lower power tube and the second negative feedback resistorR 2 Constant current source composed of I CCS- , which can be expressed as:

[0027] Similarly, when the enhancement mode MOSFET device is determined, the reverse constant current I CCS- The second negative feedback resistor R 2 is the only certainty. Under the premise that the upper and lower power tube characteristics of the clamp circuit are consistent, in order to ensure that the forward and reverse discharge currents are basically the same, the resistance values ​​of the first and second negative feedback resistors in series should be equal when selecting. That is: R 1 =R 2 =R (3) I CCS+ =I CCS- =I CCS (4) Then we have:

[0028] Defining the gate transconductance of a MOSFET g m for:

[0029] in, μ 0 is the electron mobility, C ox is the gate oxide capacitance per unit area, W is the channel width, L is the effective channel length, V GS is the gate-source voltage of the power tube, V TH is the threshold voltage of the power tube.

[0030] Substituting formula (6) into formula (5) yields:

[0031] After confirming that the upper and lower power tubes use the same enhancement-mode MOSFET, g m 、 V drv 、 V TH The value is fixed, according to formula (7) the discharge current of this branch I CCS Can be made of resistor RThe only certainty.

[0032] Assume that the absolute value of the initial load voltage is V 0, the discharge current in the auxiliary branch is constant I CCS , ignoring the parasitic resistance of the load side line, the load discharge time T discharge It can be expressed as:

[0033] From formula (8), we can see that the discharge current I CCS The larger the discharge time T discharge Therefore, the bleeder resistor R Under certain conditions, the discharge current I CCS and discharge time T discharge There is a definite corresponding relationship, which makes the energy discharge process of the capacitive load completely controllable, including the discharge current and discharge time can be precisely adjusted.

[0034] Figure 3 This is the overall control timing diagram of the AC SSPC based on the anti-series bidirectional constant current source clamp circuit. The control timing diagram corresponds to the power supply voltage V S In the negative half cycle, the AC SSPC is turned on and the load current I load In the positive half cycle, the AC SSPC is turned off, t 0~ t 2 corresponds to the opening process of AC SSPC, t 3~ t 5 corresponds to the shutdown process of AC SSPC, t 5 After that, the clamping circuit works.

[0035] t 0: The main switch command CMD of AC SSPC becomes high, AC SSPC is turned on, due to the power supply voltage V S In the negative half cycle, the first power tube S of the main power circuit is turned on first. upp However, due to the second power tube S of the main power circuit low It has not been opened yet, and the main power circuit is still in the reverse cut-off state; t 1: Power supply voltage V S When entering the positive half cycle, the second power tube S of the main power circuit low The body diode and the first power tube S of the main power circuit that has been turned on uppThe channel forms a forward path to enable the load current to change from zero; t 2: Turn on the second power tube S of the main power circuit low , the AC SSPC enters the steady-state conduction state; t 3: The main switch command CMD of AC SSPC becomes low, AC SSPC is turned off, and the load current I load In the positive half cycle, first turn off the second power tube S of the main power circuit low , the second power tube S of the main power circuit low Current switches from the MOSFET channel to the body diode, and the load current continues; t 4: Load current I load When entering the negative half cycle, the AC SSPC is in the negative cut-off state, and the current naturally crosses zero and is turned off; t 5: Turn off the first power tube S of the main power circuit upp , the AC SSPC enters a stable off-state with bidirectional cutoff, and the control instruction CMD of the clamping circuit aux Go high, the power tube S aux1 , lower power tube S aux2 When the switch is turned on, the loop current flows through the clamp circuit, and the load voltage gradually decreases.

[0036] Table 2 AC SSPC zero-crossing switch control logic

[0037] Figure 4 This is the working timing diagram of the anti-series bidirectional constant current source clamp circuit. When the power tube S aux1 , lower power tube S aux2 When conducting, if the power output terminal of the AC solid-state power controller Powerout The voltage is higher than the power ground of the AC solid-state power controller PGND The voltage of the clamp circuit is as follows (a); on the contrary, if the upper power tube S aux1 , lower power tube S aux2 When turned on, the power output terminal of the AC solid-state power controller Powerout The voltage is lower than the power ground of the AC solid-state power controller PGND The working sequence of the clamping circuit is as follows (b).

[0038] t 0: The main switch command CMD of AC SSPC is set to low, and AC SSPC is turned off.

[0039] t1: Control instruction CMD of clamping circuit aux Set high level, the power tube S aux1 , lower power tube S aux2 If the power output terminal of the AC solid-state power controller is turned on, Powerout The voltage is higher than the power ground of the AC solid-state power controller PGND Voltage, current I CSS + Power tube S aux1 , the first negative feedback resistor R 1. Lower power tube S aux2 , the second negative feedback resistor R 2 Clamp the load side voltage to V C ; If the power output terminal of the AC solid-state power controller Powerout The voltage is lower than the power ground of the AC solid-state power controller PGND Voltage, current I CSS -Through the lower power tube S aux2 , the second negative feedback resistor R 2. Upper power tube S aux1 , the first negative feedback circuit R 1Clamp the load side voltage to V C .

[0040] The AC solid-state power controller based on the anti-series bidirectional constant current source clamping circuit of the present invention, when the AC solid-state power controller is turned on, the upper and lower power tubes S of the clamping circuit aux1 、S aux2 When the AC solid-state power controller is turned off, the upper and lower power tubes S of the clamp circuit do not work. aux1 、S aux2 Open, the clamp circuit is connected in series with the load, and the load capacitance ( C load ) The energy stored in the load resistor is dissipated ( R load And because the equivalent resistance of the clamping circuit is much smaller than the equivalent resistance of the AC solid-state power controller when it is turned off, the voltage divider value on the load side caused by the leakage current after the AC solid-state power controller is turned off can be controlled within 1V.

[0041] Figure 5 The working circuit diagram is shown in Figure 1. The load is unloaded and the SSPC is in a steady-state off state. Since the main power topology of the single-phase AC SSPC adopts two identical N-channel enhancement-type MOSFETs connected in anti-series, according to the circuit equivalent principle, the resistance can be established. R SSPC With capacitor CSSPC The equivalent two-terminal network model of the parallel SSPC, where the equivalent resistance of the SSPC in the steady-state conduction state is R SSPC It is in the milliohm level and in the megohm level in the steady-state off state.

[0042] If the clamp circuit is not added, in the SSPC control circuit, due to the presence of the load voltage sampling and conditioning circuit, that is, the differential amplifier circuit composed of the load and the operational amplifier is connected in parallel, and the differential mode input impedance of the operational amplifier is Z diff It is generally 100MΩ, so the no-load condition is approximately equivalent to a 100MΩ resistive load. Assuming that the equivalent resistance is 10MΩ when the SSPC main power circuit is off, when the load is no-load and the SSPC is in a steady-state off condition, the voltage on the load side is:

[0043] After adding the clamp circuit, the equivalent resistance of the clamp circuit is much smaller than the equivalent resistance of the SSPC shutdown. R SSPC Therefore, the partial voltage generated by the leakage current on the load side is much lower than the power supply voltage. The specific no-load clamping voltage is V C As follows: V C = 2( V DS +R aux i leak ) (10) In the above formula V DS is the drain-source conduction voltage drop of the enhancement-mode MOSFET, R aux are the resistance values ​​of the two resistors connected in series in the clamping circuit, i leak Under the same conditions, the load-side voltage after adding the clamp circuit is much lower than the load-side voltage without the clamp circuit, which greatly improves the safety of the system.

[0044] Figure 6 Figure 2 shows the operating circuit diagram for a capacitive load and the SSPC in steady-state off-state conditions. (a) shows the circuit without a clamp circuit. Solid-state switches such as MOSFETs and IGBTs still have a very small leakage current (in the order of μA) even in the off state. When the SSPC is off, this leakage current slowly charges the capacitive load.

[0045] Although the off-leakage current of the SSPC is small, the continuous charging of the capacitive load causes the voltage to rise linearly over time. This voltage may pose a hazard to personnel or equipment and needs to be suppressed through circuit design or protective measures.

[0046] Figure 6 (b) shows the circuit after adding the clamp circuit. Ignoring the current of the capacitive load, almost all the leakage current flows through the clamp circuit. At this time, the voltage on the load side is: V load = 2( V DS +R aux i leak ) (12) When a power MOSFET is on, its drain-source voltage typically remains in the millivolt range; in the off state, leakage current is only in the microampere range. By introducing a clamping circuit and setting a negative feedback resistor of tens of ohms, the load-side voltage can be effectively limited to a few volts. Compared to the case without the clamping circuit, the load-side voltage can be kept relatively stable with the clamping circuit, preventing the continuous accumulation of "virtual voltage" caused by leakage current. This design not only ensures system reliability but also eliminates potential safety hazards, effectively protecting personnel and equipment.

[0047] The above embodiments are only for illustrating the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. An anti-series bidirectional constant current source clamping circuit, applied to an AC solid-state power controller, characterized in that: The clamping circuit is connected in parallel between the power output end and the power ground of the AC solid-state power controller. The clamping circuit adopts a symmetrical structure, including an upper power tube, a lower power tube, a first negative feedback resistor, and a second negative feedback resistor. The drain of the upper power tube is connected to the power output end of the AC solid-state power controller, the source of the upper power tube is connected to one end of the first negative feedback resistor, the drain of the lower power tube is connected to the power ground of the AC solid-state power controller, the source of the lower power tube is connected to one end of the second negative feedback resistor, the other end of the first negative feedback resistor is connected to the other end of the second negative feedback resistor and then connected to the same analog ground, and the gates of the upper power tube and the lower power tube are connected and then connected to the same control instruction.

2. The anti-series bidirectional constant current source clamping circuit as claimed in claim 1, characterized in that: The upper power tube and the lower power tube are both enhancement type MOSFETs.

3. The anti-series bidirectional constant current source clamping circuit as claimed in claim 1, characterized in that: The upper power tube and the lower power tube have the same characteristics, and the first negative feedback resistor and the second negative feedback resistor have the same resistance values.

4. An AC solid-state power controller, comprising a main power circuit, a clamping circuit and a clamping circuit control logic circuit, characterized in that: The clamping circuit is connected in parallel between the power output end and the power ground of the AC solid-state power controller. The clamping circuit adopts a symmetrical structure, including an upper power tube, a lower power tube, a first negative feedback resistor, and a second negative feedback resistor. The source of the upper power tube is connected to one end of the first negative feedback resistor, the source of the lower power tube is connected to one end of the second negative feedback resistor, the other end of the first negative feedback resistor is connected to the other end of the second negative feedback resistor and then connected to the same analog ground, and the gates of the upper power tube and the lower power tube are connected and then connected to the same control instruction output by the clamping circuit control logic circuit.

5. The AC solid-state power controller according to claim 4, characterized in that: The upper power tube and the lower power tube are both enhancement type MOSFETs.

6. The AC solid-state power controller according to claim 4, characterized in that: The upper power tube and the lower power tube have the same characteristics, and the first negative feedback resistor and the second negative feedback resistor have the same resistance values.

7. The AC solid-state power controller according to any one of claims 4 to 6, characterized in that: The main power circuit includes a first power tube and a second power tube connected in anti-series, the drain of the first power tube being connected to an AC power supply as a power input end of an AC solid-state power controller, the drain of the second power tube being connected to a clamping circuit and a load as a power output end of the AC solid-state power controller, the gate of the first power tube and the source of the second power tube being connected to the same analog ground, and the gate of the first power tube and the gate of the second power tube being connected to different switching instructions.

8. The AC solid-state power controller according to claim 7, characterized in that: The clamp circuit control logic circuit includes an NOR gate, an OR gate and an RS trigger. The two input ends of the NOR gate are respectively connected to the switch instructions of the first power tube and the second power tube. The four input ends of the OR gate are respectively connected to the switch instructions of the first power tube and the second power tube, as well as the positive and negative logic signals of the load current direction. The output end of the NOR gate is connected to the RS trigger. The output of the OR gate is connected to the RS flip-flop end, the RS flip-flop The terminal outputs the control instruction.

9. The control method of the AC solid-state power controller according to claim 7, characterized in that: include: When the AC solid-state power controller is turned on: in the positive half cycle of the AC power supply voltage, the second power tube is turned on first, and the first power tube is turned on after the voltage passes through zero, and the upper power tube and the lower power tube are turned off; In the negative half cycle of the AC power supply voltage, the first power tube is turned on first, and the second power tube is turned on after the voltage passes through zero, and the upper power tube and the lower power tube are turned off; When the AC solid-state power controller is turned off: in the positive half cycle of the load current, the second power tube is turned off first, and the first power tube is turned off after the current passes through zero, and the upper power tube and the lower power tube are turned on; in the negative half cycle of the load current, the first power tube is turned off first, and the second power tube is turned off after the current passes through zero, and the upper power tube and the lower power tube are turned on.

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