Power supply control circuit

Abstract

The present invention relates to the field of low-voltage electrical appliances, and in particular to a power supply control circuit, which comprises a rectifying and anti-surge interference circuit, a switch control circuit, an AC-DC conversion circuit, a load-end voltage detection circuit and an MCU which are connected in sequence, and the MCU is also connected to the switch control circuit; the switch control circuit also comprises a switch circuit and a control circuit, the rectifying and anti-surge interference circuit, the switch circuit and the AC-DC conversion circuit are connected in sequence, and the MCU, the control circuit and the switch circuit are connected in sequence; the MCU drives the switch circuit to be turned on or off through a control circuit according to the load-end voltage detected by the load-end voltage detection circuit; the power supply control circuit of the present invention, wherein the switch control circuit controls the turning on and off of the AC-DC conversion circuit, so that the power supply control circuit can be applied to a three-phase three-wire system or a three-phase power supply system.

Description

Technical Field

[0001] The invention relates to the field of low-voltage electrical appliances, and in particular to a power supply control circuit. Background Art

[0002] With the advancement of smart grid construction, the electricity meter fee control system has received extensive attention as a foundation. Among them, the external circuit breaker of the electricity meter is a key component for realizing the intelligent fee control function with the smart electricity meter. When the user is in arrears, the smart electricity meter sends a signal to open the circuit through the fee control line, and the external circuit breaker of the electricity meter opens and disconnects the user's power supply; when the user renews the fee, the smart electricity meter sends a signal to close the circuit through the fee control line, and the external circuit breaker of the electricity meter automatically closes and connects the user's power supply.

[0003] Since the external circuit breaker is connected to the back end of the smart energy meter, the circuit breaker itself will become part of the load, and its power consumption will be included in the energy meter measurement; if the power consumption of the external circuit breaker itself is too large, the energy meter will incur charges even if there is no user load, affecting the correct measurement of electricity.

[0004] The existing external circuit breaker of the energy meter uses a dedicated AC-DC power chip to achieve ultra-low power consumption. The chip integrates a high-voltage power MOSFET and can provide a zero standby mode. When the MCU sends a low level to the ZC pin of the power chip, the power chip is in normal working state; when the MCU sends a high level, the power chip is in zero standby mode, and the average phase line current is less than 0.2mA. However, since the power chip has a built-in 600-720V power MOSFET, in a three-phase three-wire system or a system with only three-phase power supply, the voltage after rectification of the three-phase power supply can reach 800V, which the MOSFET in the existing power chip cannot withstand. Therefore, in a three-phase three-wire system or a system with only three-phase power supply, the existing power chip cannot be used, which limits the scope of application of the existing external circuit breaker of the energy meter. Summary of the invention

[0005] The object of the present invention is to overcome the defects of the prior art and provide a power supply control circuit, wherein the switch control circuit controls the opening and closing of the AC-DC conversion circuit, so that the power supply control circuit can be applicable to a three-phase three-wire system or a three-phase power supply system.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A power supply control circuit comprises a rectifying and anti-surge interference circuit 1, a switch control circuit 2, an AC-DC conversion circuit 3, a load terminal voltage detection circuit 4 and an MCU which are connected in sequence, and the MCU is also connected to the switch control circuit 2;

[0008] The switch control circuit 2 further includes a switch circuit 20 and a control circuit 21, the rectification and surge interference prevention circuit 1, the switch circuit 20 and the AC-DC conversion circuit 3 are connected in sequence, and the MCU, the control circuit 21 and the switch circuit 20 are connected in sequence;

[0009] The MCU drives the switch circuit 20 to be turned on or off through the control circuit 21 according to the load terminal voltage detected by the load terminal voltage detection circuit 4 .

[0010] Preferably, when the load terminal voltage is equal to or lower than the turn-on voltage threshold, the MCU drives the switch circuit 20 of the switch control circuit 2 to turn on through the control circuit 21 of the switch control circuit 2; when the load terminal voltage is equal to or higher than the turn-off voltage threshold, the MCU drives the switch circuit 20 to turn off through the control circuit 21; the turn-on voltage threshold is less than the turn-off voltage threshold.

[0011] Preferably, the AC-DC conversion circuit 3 includes a high-frequency transformer T1 and a rectifier filter circuit 30, the rectifier filter circuit 30 includes an energy storage capacitor C7, the energy storage capacitor C7 is a polar capacitor, the two ends of the secondary coil L1 of the high-frequency transformer T1 are connected to the two ends of the energy storage capacitor C7, and the MCU obtains the voltage U at both ends of the energy storage capacitor C7 through the load end voltage detection circuit 4. C7 , is the load terminal voltage;

[0012] When the switch circuit 20 is in the on state, the energy storage capacitor C7 is charged to U C7 ≥ the shutdown voltage threshold, the MCU drives the switch circuit 20 to shut down through the control circuit 21; when the switch circuit 20 is in the off state, the energy storage capacitor C7 discharges to U C7 When the voltage is less than or equal to the turn-on voltage threshold, the MCU drives the switch circuit 20 to turn on through the control circuit 21.

[0013] Preferably, the load-end voltage detection circuit 4 includes a resistor R2 and a resistor R12, one end of the resistor 12 is connected to the positive electrode of the energy storage capacitor C7, and the other end is connected in series with one end of the resistor R12, the other end of the resistor R12 is connected to the negative electrode of the energy storage capacitor C7, and the node between the resistor R2 and the resistor R12 is connected to the MCU.

[0014] Preferably, the switch circuit 20 includes a MOS tube Q1, a resistor R4, a resistor R7, a diode D7 and a voltage regulator tube Z2; the control circuit 21 includes an optical coupler U5, a resistor R9, a resistor R11, a capacitor C3 and a MOS tube Q4; the first pin of the optical coupler U5 is connected to the MCU, the second pin is connected to the ground GND through the resistor R9, the third pin is connected to the G pole of the MOS tube Q4 and is connected to the S pole of the MOS tube Q4 through the parallel resistor R11 and the capacitor C3, and the fourth pin is connected to the ground GND through the resistor R9. The pin is connected to the D pole of the MOS tube Q4 and then connected to the cathode of the diode D7 and the cathode of the voltage regulator tube Z2 respectively; the D pole of the MOS tube Q1 is connected to the output end of the rectification and surge protection interference circuit 1 and is connected to the G pole of the MOS tube Q1 through the resistors R4 and R7 connected in series in sequence, the G pole of the MOS tube Q1 is connected to the anode of the diode D7, and the S pole of the MOS tube Q1 is connected to the anode of the voltage regulator tube Z2, the input end of the AC-DC conversion circuit 3, and the S pole of the MOS tube Q4 respectively.

[0015] Preferably, the rectifier and filter circuit 30 also includes a diode D2, a diode D5, a capacitor C24, a resistor R1 and a capacitor C1; one end of the secondary coil L1 is connected to the anode of the diode D2, the cathode of the diode D2 is connected to the anode of the diode D5, the cathode of the diode D5 is connected to the positive electrode of the energy storage capacitor C7, the other end of the secondary coil L1 and the cathode of the energy storage capacitor C7 are both connected to the ground GND, the resistor R1 and the capacitor C1 are connected in series between the anode and cathode of the diode D2, and the capacitor C24 is connected in parallel with the energy storage capacitor C7.

[0016] Preferably, the AC-DC conversion circuit 3 further includes a power chip U1 , the switch circuit 20 is connected to one end of the primary coil L0 of the high-frequency transformer T1 , and the other end of the primary coil L0 is connected to the power chip U1 .

[0017] Preferably, the AC-DC conversion circuit 3 further includes an input capacitor circuit 33 and an RCD absorption circuit 32, the switch circuit 20 is connected to one end of the primary coil L0 through the input capacitor circuit 33, and the end of the primary coil L0 is connected to the other end of the primary coil L0 through the RCD absorption circuit 32;

[0018] The input capacitor circuit 33 includes a diode D1, a capacitor EC1, a capacitor EC2, a resistor R3, a resistor R8, a resistor R10 and a resistor R13, the switch circuit 20 is connected to the anode of the diode D1, the cathode of the diode D1 is respectively connected to one end of the primary coil L0 and the positive electrode of the capacitor EC1, the negative electrode of the capacitor EC1 is connected to the positive electrode of the capacitor EC2, the negative electrode of the capacitor EC2 is connected to the ground GND, the resistor R3 and the resistor R8 are connected in series and then connected in parallel with the capacitor EC1, the resistor R10 and the resistor R13 are connected in series and then connected in parallel with the capacitor EC2;

[0019] The RCD absorption circuit 32 includes a capacitor C2, a resistor R5 and a diode D6. The resistor R5 and the diode D6 are connected in series between the first terminal and the second terminal of the primary coil L0. The cathode of the diode D6 is connected to the resistor R5. The capacitor C2 is connected to the resistor R5 in parallel. The second terminal of the primary coil L0 of the high-frequency transformer T1 is respectively connected to the cathode of the diode D6 and the 8th pin of the power chip U1.

[0020] Preferably, the AC-DC conversion circuit 3 further includes a feedback loop 31 connected to the power chip U1; the feedback loop 31 includes a capacitor C13, a MOS tube Q2, a resistor R29, a capacitor C5, a resistor R25, a resistor R30, a voltage regulator tube Z3 and a capacitor C9;

[0021] The D pole of the MOS tube Q2 is respectively connected to the 4th pin of the power chip U1, one end of the capacitor C13, and one end of the capacitor C5, the other end of the capacitor C13 is connected to the ground GND, the S pole of the MOS tube Q2 is connected to the ground GND through the resistor R29, the G pole of the MOS tube Q2 is connected to the ground GND through the resistors R25 and R30 connected in series in sequence, the voltage regulator tube Z3 and the capacitor C9 are connected in series and then connected in parallel with the resistor R30, the anode of the voltage regulator tube Z3 is respectively connected to the other end of the capacitor C5 and the node between the resistor R25 and the resistor R30, and the cathode of the voltage regulator tube Z3 is connected to the ground GND through the capacitor C9.

[0022] Preferably, the 3rd and 5th pins of the power chip U1 are connected to the ground GND, the 2nd pin is connected to the ground GND through a resistor R19 and a capacitor C8 in parallel, the 6th pin is connected to the ground GND through a resistor R20, the 1st pin is connected to the ground GND through capacitors EC3 and C4 in parallel, the positive pole of capacitor EC3 is connected to the 1st pin, and the negative pole is connected to the ground GND, the 1st pin is also connected to a 15V / 500mA power supply through a diode D15, the cathode of the diode D15 is connected to the 1st pin, and the anode is connected to the 15V / 500mA power supply.

[0023] Preferably, the rectification and surge interference protection circuit 1 includes an A-phase input terminal, a B-phase input terminal, a C-phase input terminal, a varistor VR1, a varistor VR2, a varistor VR3, a diode D3, a diode D4 and a winding resistor FR1; the two ends of the varistor VR1 are respectively connected to the C-phase input terminal and the B-phase input terminal, the two ends of the varistor VR2 are respectively connected to the A-phase input terminal and the B-phase input terminal, the A-phase input terminal is connected to the anode of the diode D3, the C-phase input terminal is connected to the anode of the diode D4, the cathode of the diode D3 is connected to the cathode of the diode D4 and then connected to one end of the winding resistor FR1, the other end of the winding resistor FR1 is respectively connected to the switch circuit 20 of the switch control circuit 2 and one end of the varistor VR3, the other end of the varistor VR3 is connected to the B-phase input terminal and then connected to the ground GND.

[0024] Preferably, an LDO chip U3 is also included, wherein the first pin of the LDO chip U3 is connected to the positive electrode of the energy storage capacitor C7, the second pin is connected to the ground GND, the third pin is connected to the VCC power supply, and is connected to the ground GND through the parallel capacitors C12 and C22.

[0025] The power control circuit of the present invention controls the on or off of the switch control circuit 2 through the cooperation of the switch control circuit 2, the load-end voltage detection circuit 4 and the MCU, thereby realizing the switching of the working mode and the standby mode of the AC-DC conversion circuit 3, so that the high-voltage power MOSFET built into the AC-DC power chip does not need to bear excessive voltage, and the built-in high-voltage power MOSFET of the AC-DC power chip can even be eliminated, so that the power control circuit of the present invention can be applicable to a three-phase three-wire system or a three-phase power supply system.

[0026] In addition, the power control circuit of the present invention, through the charging / discharging process of the energy storage capacitor C7, puts the entire power control circuit in an intermittent power supply state, reduces the average power consumption of the entire power system, and meets the low power consumption requirements in a three-phase power system or a system with an input of 380V. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the module structure of the power supply control circuit of the present invention;

[0028] Figure 2 It is the circuit intention of the power supply control circuit of the present invention;

[0029] Figure 3 It is a circuit diagram of the rectification and surge interference prevention circuit of the present invention;

[0030] Figure 4 is a circuit diagram of a switch control circuit of the present invention;

[0031] Figure 5is a circuit diagram of an AC-DC conversion circuit of the present invention;

[0032] Figure 6 The present invention Figure 2 Magnified view of part A. DETAILED DESCRIPTION

[0033] The following is combined with Figure 1-6 The following embodiments are provided to further illustrate the specific implementation of the power supply control circuit of the present invention. The power supply control circuit of the present invention is not limited to the description of the following embodiments.

[0034] The power supply control circuit of the present invention comprises a rectification and surge protection circuit 1, a switch control circuit 2, an AC-DC conversion circuit 3, a load-end voltage detection circuit 4 and an MCU which are connected in sequence. The MCU is also connected to the switch control circuit 2. The MCU drives the switch control circuit 2 to turn on or off according to the load-end voltage detected by the load-end voltage detection circuit 4.

[0035] The switch control circuit 2 also includes a switch circuit 20 and a control circuit 21. The rectification and surge interference protection circuit 1, the switch circuit 20 and the AC-DC conversion circuit 3 are connected in sequence. The MCU, the control circuit 21 and the switch circuit 20 are connected in sequence. The MCU drives the switch circuit 20 to be turned on or off through the control circuit 21 according to the load end voltage detected by the load end voltage detection circuit 4.

[0036] The existing external circuit breaker of the electric energy meter adopts a dedicated AC-DC power supply chip to achieve ultra-low power consumption. The chip integrates a high-voltage power MOSFET and can provide a zero standby mode, which is controlled by the ZC pin. When the MCU outputs a low level to the ZC pin, the AC-DC power supply chip is in normal working state; when the MCU outputs a high level to the ZC pin, the AC-DC power supply chip is in zero standby mode. However, since the AC-DC power supply chip has a built-in 600-720V power MOSFET, the external circuit breaker of the electric energy meter containing the AC-DC power supply chip cannot be used in a three-phase three-wire system or a three-phase power supply system.

[0037] The power control circuit of the present invention controls the on or off of the switch control circuit 2 through the cooperation of the switch control circuit 2, the load-end voltage detection circuit 4 and the MCU, thereby realizing the switching of the working mode and the standby mode of the AC-DC conversion circuit 3, so that the high-voltage power MOSFET built into the AC-DC power chip does not need to bear excessive voltage, and the high-voltage power MOSFET built into the AC-DC power chip can even be eliminated, so that the power control circuit of the present invention can be applicable to a three-phase three-wire system or a three-phase power supply system.

[0038] Preferably, Figure 2 and 4As shown, when the load terminal voltage is equal to or lower than the turn-on voltage threshold, the MCU drives the switch circuit 2 of the switch control circuit 2 to turn on through the control circuit 21 of the switch control circuit 2; when the load terminal voltage is equal to or higher than the turn-off voltage threshold, the MCU drives the switch circuit 20 to turn off through the control circuit 21; the turn-on voltage threshold is less than the turn-off voltage threshold.

[0039] Preferably, Figure 2 and 5 As shown, the AC-DC conversion circuit 3 includes a high-frequency transformer T1 and a rectifier filter circuit 30. The rectifier filter circuit 30 includes a capacitor C7. The energy storage capacitor C7 is a polar capacitor. The two ends of the secondary coil of the high-frequency transformer T1 are connected to the two ends of the energy storage capacitor C7. The MCU obtains the voltage U at both ends of the energy storage capacitor C7 through the load end voltage detection circuit 4. C7 , is the load terminal voltage; when the switch circuit 20 is in the on state, the energy storage capacitor C7 is charged to U C7 ≥ the shutdown voltage threshold, the MCU drives the switch circuit 20 to shut down through the control circuit 21; when the switch circuit 20 is in the off state, the energy storage capacitor C7 discharges to U C7 When the voltage is less than or equal to the turn-on voltage threshold, the MCU drives the switch circuit 20 to turn on through the control circuit 21.

[0040] like Figure 1 and 2 FIG. 1 is an implementation of the power supply control circuit of the present invention.

[0041] The power supply control circuit of the present invention comprises a rectification and surge protection circuit 1, a switch control circuit 2, an AC-DC conversion circuit 3, a load-end voltage detection circuit 4 and an MCU which are connected in sequence, and the MCU is also connected to the control circuit 2; the MCU drives the switch control circuit 2 to turn on or off according to the load-end voltage detected by the load-end voltage detection circuit 4, thereby realizing the opening or disconnection of the AC-DC conversion circuit 3.

[0042] Preferably, Figure 2 and 4 As shown, the switch control circuit 2 includes a switch circuit 20 and a control circuit 21, the rectification and surge interference prevention circuit 1, the switch circuit 20 and the AC-DC conversion circuit 3 are connected in sequence, and the MCU, the control circuit 21 and the switch circuit 20 are connected in sequence; the MCU drives the switch circuit 20 to turn on or off through the control circuit 21 according to the load terminal voltage detected by the load terminal voltage detection circuit 4. Further, when the load terminal voltage is equal to or lower than the turn-on voltage threshold, the MCU drives the switch circuit 20 to turn on through the control circuit 21; when the load terminal voltage is equal to or higher than the turn-off voltage threshold, the MCU drives the switch circuit 20 to turn off through the control circuit 21; the turn-on voltage threshold is less than the turn-off voltage threshold.

[0043] Preferably, Figure 2 and 5 As shown, the AC-DC conversion circuit 3 includes a high-frequency transformer T1 and a rectifier filter circuit 30. The rectifier filter circuit 30 includes an energy storage capacitor C7. The energy storage capacitor C7 is a polar capacitor. The two ends of the secondary coil of the high-frequency transformer T1 are respectively connected to the two ends of the energy storage capacitor C7. The MCU obtains the voltage U at both ends of the energy storage capacitor C7 through the load end voltage detection circuit 4. C7 , is the load terminal voltage; when the switch circuit 20 is in the on state, the energy storage capacitor C7 is charged to U C7 ≥ the shutdown voltage threshold, the MCU drives the switch circuit 20 to shut down through the control circuit 21; when the switch circuit 20 is in the off state, the energy storage capacitor C7 discharges to U C7 When the voltage is less than or equal to the turn-on voltage threshold, the MCU drives the switch circuit 20 to turn on through the control circuit 21.

[0044] like Figure 4 As shown, an embodiment of the switch control circuit 2 is shown.

[0045] The switch control circuit 2 includes a switch circuit 20 and a control circuit 21. The switch circuit 20 includes a MOS tube Q1, a resistor R4, a resistor R7, a diode D7 and a voltage regulator tube Z2. The control circuit includes an optical coupler U5, a resistor R9, a resistor R11, a capacitor C3 and a MOS tube Q4. The first pin of the optical coupler U5 is connected to the MCU, the second pin is connected to the ground GND through the resistor R9, the third pin is connected to the G pole of the MOS tube Q4 and connected to the G pole of the MOS tube Q4 through the parallel resistor R11 and the capacitor C3. The 4th pin is connected to the S pole, and the 4th pin is connected to the D pole of the MOS tube Q4, and then connected to the cathode of the diode D7 and the cathode of the voltage regulator tube Z2 respectively; the D pole of the MOS tube Q1 is connected to the output end of the rectification and surge interference prevention circuit 1 and is connected to the G pole of the MOS tube Q1 through the resistors R4 and R7 connected in series in sequence, the G pole of the MOS tube Q1 is connected to the anode of the diode D7, and the S pole of the MOS tube Q1 is connected to the anode of the voltage regulator tube Z2, the input end of the AC-DC conversion circuit 3, and the S pole of the MOS tube Q4 respectively. Further, as Figure 4 As shown, the first pin of the optical coupler U5 is connected to the anode of the light emitting diode of the optical coupler U5, and the second pin is connected to the cathode of the light emitting diode.

[0046] like Figure 5 FIG. 1 is an embodiment of the rectifier and filter circuit 30 .

[0047] The rectifier and filter circuit 30 includes a diode D2, a diode D5, a capacitor C24, a resistor R1 and a capacitor C1; one end of the secondary coil L1 is connected to the anode of the diode D2, the cathode of the diode is connected to the anode of the diode D5, the cathode of the diode D5 is connected to the positive electrode of the energy storage capacitor C7, the negative electrode of the energy storage capacitor C7 and the other end of the secondary coil L1 are both connected to the ground GND, the resistor R1 and the capacitor C1 are connected in series between the anode and cathode of the diode D2, and the capacitor C24 is connected in parallel with the energy storage capacitor C7.

[0048] like Figure 5 FIG. 4 is an embodiment of the load terminal voltage detection circuit 4 .

[0049] The load-end voltage detection circuit 4 includes a resistor R2 and a resistor R12, one end of the resistor R12 is connected to the positive electrode of the energy storage capacitor C7, and the other end is connected in series with one end of the resistor R12, the other end of the resistor R12 is connected to the negative electrode of the energy storage capacitor C7, and the node between the resistor R2 and the resistor R12 is connected to the MCU.

[0050] Specifically, when the energy storage capacitor C7 is discharged, the voltage across R12 decreases linearly. When the MCU detects that the voltage across the resistor R12 is ≤ the turn-on voltage threshold, the MCU turns on the MOS tube Q1 through the optocoupler U5, so that the AC-DC conversion circuit 3 works normally, and the energy storage capacitor C7 starts to charge; when the MCU detects that the voltage across the resistor R12 is ≥ the turn-off voltage threshold, the MCU disconnects the MOS tube Q1 through the optocoupler U5, and the AC-DC conversion circuit 3 is disconnected, and the energy storage capacitor C7 starts to discharge.

[0051] The following will be combined Figure 4 and 5 , the principle and process of the MCU driving the switch circuit 20 to be turned on / off through the control circuit 21 according to the load terminal voltage are explained.

[0052] like Figure 4 and 5As shown, the node between the resistor R2 and the resistor R12 of the load-end voltage detection circuit 4 outputs a signal V_CHK (i.e., the load-end voltage) to the MCU, and the MCU compares the signal V_CHK with the turn-on voltage threshold and the turn-off voltage threshold. Then, the MCU outputs a signal CTK to the first pin of the optocoupler U5 according to the comparison result; when the signal V_CHK≤the turn-on voltage threshold, the signal CTK output by the MCU to the first pin of the optocoupler U5 is at a low level, and the output electrode of the optocoupler U5 is cut off, causing the MOS tube Q4 to be cut off. Due to the cut-off state of the MOS tube Q4 In the on-state, there is a voltage difference between the G pole and the S pole of the MOS tube Q1, and the MOS tube Q1 is an N-channel MOS tube, so the MOS tube Q1 is turned on, so that the AC-DC conversion circuit 3 is turned on, and the energy storage capacitor C7 of the AC-DC conversion circuit 3 starts to charge; when the signal V_CHK≥the turn-off voltage threshold, the signal CTK output by the MCU to the first pin of the optocoupler U5 is high, the output pole of the optocoupler U5 is turned on, and the voltage of the resistor R11 increases, causing the MOS tube Q4 to work in the saturation region and be in a fully on state. Due to the turn-on voltage V th Greater than the junction voltage V of MOS tube Q1 DS The sum of the node voltages of the diode D7 and the MOS tube Q1 is in the cut-off state. Since the MOS tube Q1 is in the cut-off state, the AC-DC conversion circuit 3 has no power input, the power chip is in a stopped working state, and the AC-DC conversion circuit 3 has no voltage output. At this time, the energy storage capacitor C7 starts to discharge.

[0053] The power control circuit of the present invention, through the charging / discharging process of the energy storage capacitor C7, puts the entire power control circuit in an intermittent power supply state, reduces the average power consumption of the entire power system, and meets the low power consumption requirements in a three-phase power system or a system with an input of 380V.

[0054] like Figure 5 FIG. 1 is an embodiment of the AC-DC conversion circuit 3 .

[0055] The AC-DC conversion circuit 3 includes a power chip U1, a high-frequency transformer T1 and a rectifier filter circuit 30, the switch circuit 20 is connected to one end of the primary coil L0 of the high-frequency transformer T1, the other end of the primary coil L0 is connected to the power chip U1, and the secondary coil L1 of the high-frequency transformer T1 is connected to the rectifier filter circuit 30. Further, as Figure 5 As shown, the AC-DC conversion circuit 3 also includes an input capacitor circuit 33, an RCD absorption circuit 32 and a feedback circuit 31. The switch circuit 20 is connected to one end of the primary coil L0 through the input capacitor circuit, and the end of the primary coil L0 is connected to the other end of the primary coil L0 through the RCD absorption circuit 32. The feedback circuit 31 is connected to the power chip U1.

[0056] Preferably, the model of the power chip U1 is HF920GSE.

[0057] Preferably, Figure 5 As shown, the input capacitor circuit 33 includes a diode D1, a capacitor EC1, a capacitor EC2, a resistor R3, a resistor R8, a resistor R10 and a resistor R13, the switch circuit 21 is connected to the anode of the diode D1, the cathode of the diode D1 is respectively connected to the first terminal of the primary coil L0 and the positive electrode of the capacitor EC1, the negative electrode of the capacitor EC1 is connected to the positive electrode of the capacitor EC2, the negative electrode of the capacitor EC2 is connected to the ground GND, the resistor R3 and the resistor R8 are connected in series and then connected in parallel with the capacitor EC1, and the resistor R10 and the resistor R13 are connected in series and then connected in parallel with the capacitor EC2. The resistor R3, the resistor R8, the resistor R10 and the resistor 13 are equal resistance resistors, which is conducive to ensuring the consistency of the voltage across the capacitor EC1 and the capacitor EC2.

[0058] Preferably, Figure 5 As shown, the RCD absorption circuit 32 is used to absorb the leakage inductance of the primary coil L0, including a capacitor C2, a resistor R5 and a diode D6, the resistor R5 and the diode D6 are connected in series between the first terminal and the second terminal of the primary coil L0, the capacitor C2 is connected in parallel with the resistor R5, the cathode of the diode D6 is connected to the resistor R5, and the second terminal of the primary coil L0 is respectively connected to the anode of the diode D6 and the 8th pin of the power chip U1. Further, the first terminal and the second terminal of the primary coil L0 are the input end and the output end of the primary coil L0, respectively.

[0059] Preferably, Figure 5 As shown, the feedback loop 31 includes capacitor C13, MOS tube Q2, resistor R29, capacitor C5, resistor R25, resistor R30, voltage regulator tube Z3 and capacitor C9; the D pole of the MOS tube Q2 is respectively connected to the 4th pin of the power chip U1, one end of the capacitor C13, and one end of the capacitor C5, the other end of the capacitor C13 is connected to the ground GND, the S pole of the MOS tube Q2 is connected to the ground GND through the resistor R29, the G pole of the MOS tube Q2 is connected to the ground GND through the resistor R25 and the resistor R30 connected in series, the voltage regulator tube Z3 and the capacitor C9 are connected in series and then connected in parallel with the resistor R30, the anode of the voltage regulator tube Z3 is respectively connected to the other end of the capacitor C5 and the node between the resistor R25 and the resistor R30, and the cathode of the voltage regulator tube Z3 is connected to the ground GND through the capacitor C9. Further, as Figure 5 As shown, the node between the voltage regulator Z3 and the capacitor C9 is connected to a 15V power supply. The power control circuit of the present invention has a feedback loop 31 that can adjust the PWM inside the power chip U1 according to the output voltage value, so that the output voltage is stable.

[0060] Preferably, Figure 5As shown, the 3rd and 5th pins of the power chip U1 are connected to the ground GND, the 2nd pin is connected to the ground GND through a resistor R19 and a capacitor C8 in parallel, the 6th pin is connected to the ground GND through a resistor R20, the 1st pin is connected to the ground GND through a capacitor EC3 and a capacitor C4 in parallel, the positive electrode of the capacitor EC3 is connected to the 1st pin, and the negative electrode is connected to the ground GND, the 1st pin is connected to a 15V / 500mA power supply through a diode D15, the cathode of the diode D15 is connected to the 1st pin, and the anode is connected to the 15V / 500mA power supply.

[0061] Preferably, Figure 5 As shown, the first pin of the power chip U1 is the VCC pin, the second pin is the FSET pin, the third pin is the PRO pin, the fourth pin is the FB pin, the fifth pin is the GND pin, the sixth pin is the S pin, and the eighth pin is the D pin.

[0062] It should be pointed out that the 15 / 500mA power supply and the 15V power supply are both output power supplies of the AC-DC conversion circuit.

[0063] like Figure 2 and 3 As shown, it is an embodiment of the rectification and surge protection circuit.

[0064] The rectification and surge interference prevention circuit 1 includes an A-phase input terminal, a B-phase input terminal, a C-phase input terminal, a varistor VR1, a varistor VR2, a varistor VR3, a diode D3, a diode D4 and a winding resistor FR1; the two ends of the varistor VR1 are respectively connected to the C-phase input terminal and the B-phase input terminal, the two ends of the varistor VR2 are respectively connected to the A-phase input terminal and the B-phase input terminal, the A-phase input terminal is connected to the anode of the diode D3, the C-phase input terminal is connected to the anode of the diode D4, the cathode of the diode D3 is connected to the cathode of the diode D4 and then connected to one end of the winding resistor FR1, the other end of the winding resistor FR1 is respectively connected to the switch circuit 20 of the switch control circuit 2 and one end of the varistor VR3, the other end of the varistor VR3 is connected to the B-phase input terminal and then connected to the ground GND. The varistor VR1 and the varistor VR2 can absorb the instantaneous surge voltage or current generated at the power supply end to avoid damage to the back-end devices. The varistor VR3 is connected to the back end of the winding resistor FR1 and can absorb the residual pressure generated at both ends of the varistor VR1 and the varistor VR2. Figure 3 As shown, the models of the varistors VR1 / VR2 / VR3 are all 821KD10, the models of the diodes D3 / D4 are all BF2K, and the model of the winding resistor FR1 is 100R.

[0065] Preferably, Figure 2 and 6As shown, the power control circuit of the present invention also includes an LDO chip U3, the first pin of the LDO chip U3 is connected to the positive electrode of the energy storage capacitor C7, the second pin is connected to the ground GND, the third pin is connected to the VCC power supply, and the third pin is connected to the system ground SGND (system ground SGND and ground GND are of equal potential) through the capacitor C12 and capacitor C22 connected in parallel. Further, the LDO chip U3 is a low voltage difference linear voltage regulator chip, the first pin is the VIN pin, the second pin is the GND pin, the third pin is the VOUT pin, the capacitor C12 and the capacitor C22 are the output terminal capacitors of the LDO chip U3, and the energy storage capacitor C7 and the capacitor C24 of the AC-DC conversion circuit 3 are connected in parallel as the input capacitors of the LDO chip U3.

[0066] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A power control circuit, characterized in that: It comprises a rectifying and anti-surge interference circuit (1), a switch control circuit (2), an AC-DC conversion circuit (3), a load end voltage detection circuit (4) and an MCU which are connected in sequence, and the MCU is also connected to the switch control circuit (2); The switch control circuit (2) further comprises a switch circuit (20) and a control circuit (21); the rectification and surge interference prevention circuit (1), the switch circuit (20) and the AC-DC conversion circuit (3) are connected in sequence; and the MCU, the control circuit (21) and the switch circuit (20) are connected in sequence; The MCU drives the switch circuit (20) to be turned on or off through the control circuit (21) according to the load terminal voltage detected by the load terminal voltage detection circuit (4); The AC-DC conversion circuit (3) comprises a high-frequency transformer T1 and a rectifier filter circuit (30), the rectifier filter circuit (30) comprises an energy storage capacitor C7, the energy storage capacitor C7 is a polar capacitor, the two ends of the secondary coil L1 of the high-frequency transformer T1 are connected to the two ends of the energy storage capacitor C7, and the MCU obtains the voltage U at the two ends of the energy storage capacitor C7 through the load end voltage detection circuit (4). C7 , is the load terminal voltage; When the switch circuit (20) is in the on state, the energy storage capacitor C7 is charged to U C7 When the voltage is greater than or equal to the turn-off voltage threshold, the MCU drives the switch circuit (20) to turn off through the control circuit (21); when the switch circuit (20) is in the off state, the energy storage capacitor C7 discharges to U C7 When the voltage is less than or equal to the start-up voltage threshold, the MCU drives the switch circuit (20) to be turned on through the control circuit (21); The turn-on voltage threshold is less than the turn-off voltage threshold.

2. The power control circuit according to claim 1, characterized in that: The load-end voltage detection circuit (4) comprises a resistor R2 and a resistor R12, one end of the resistor 12 is connected to the positive electrode of the energy storage capacitor C7, and the other end is connected in series with one end of the resistor R12, the other end of the resistor R12 is connected to the negative electrode of the energy storage capacitor C7, and the node between the resistor R2 and the resistor R12 is connected to the MCU.

3. The power control circuit according to claim 1, characterized in that: The switch circuit (20) comprises a MOS tube Q1, a resistor R4, a resistor R7, a diode D7 and a voltage regulator tube Z2; the control circuit (21) comprises an optical coupler U5, a resistor R9, a resistor R11, a capacitor C3 and a MOS tube Q4; the first pin of the optical coupler U5 is connected to the MCU, the second pin is connected to the ground GND through the resistor R9, the third pin is connected to the G pole of the MOS tube Q4 and is connected to the S pole of the MOS tube Q4 through the parallel resistor R11 and the capacitor C3, and the fourth pin is connected to the ground GND through the resistor R9. The D pole of the MOS tube Q1 is connected to the D pole of the MOS tube Q4 and then respectively connected to the cathode of the diode D7 and the cathode of the voltage regulator tube Z2; the D pole of the MOS tube Q1 is connected to the output end of the rectification and surge interference prevention circuit (1) and is connected to the G pole of the MOS tube Q1 through the resistor R4 and the resistor R7 connected in series in sequence; the G pole of the MOS tube Q1 is connected to the anode of the diode D7; the S pole of the MOS tube Q1 is respectively connected to the anode of the voltage regulator tube Z2, the input end of the AC-DC conversion circuit (3), and the S pole of the MOS tube Q4.

4. The power control circuit according to claim 1, characterized in that: The rectifier filter circuit (30) further comprises a diode D2, a diode D5, a capacitor C24, a resistor R1 and a capacitor C1; one end of the secondary coil L1 is connected to the anode of the diode D2, the cathode of the diode D2 is connected to the anode of the diode D5, the cathode of the diode D5 is connected to the positive electrode of the energy storage capacitor C7, the other end of the secondary coil L1 and the cathode of the energy storage capacitor C7 are both connected to the ground GND, the resistor R1 and the capacitor C1 are connected in series between the anode and cathode of the diode D2, and the capacitor C24 is connected in parallel with the energy storage capacitor C7.

5. The power control circuit according to claim 1 or 4, characterized in that: The AC-DC conversion circuit (3) further comprises a power chip U1, the switch circuit (20) is connected to one end of the primary coil L0 of the high-frequency transformer T1, and the other end of the primary coil L0 is connected to the power chip U1.

6. The power control circuit according to claim 5, characterized in that: The AC-DC conversion circuit (3) further comprises an input capacitor circuit (33) and an RCD absorption circuit (32); the switch circuit (20) is connected to one end of the primary coil L0 via the input capacitor circuit (33), and the end of the primary coil L0 is connected to the other end of the primary coil L0 via the RCD absorption circuit (32); The input capacitor circuit (33) comprises a diode D1, a capacitor EC1, a capacitor EC2, a resistor R3, a resistor R8, a resistor R10 and a resistor R13, the switch circuit (20) is connected to the anode of the diode D1, the cathode of the diode D1 is respectively connected to one end of the primary coil L0 and the positive electrode of the capacitor EC1, the negative electrode of the capacitor EC1 is connected to the positive electrode of the capacitor EC2, the negative electrode of the capacitor EC2 is connected to the ground GND, the resistor R3 and the resistor R8 are connected in series and then connected in parallel with the capacitor EC1, and the resistor R10 and the resistor R13 are connected in series and then connected in parallel with the capacitor EC2; The RCD absorption circuit (32) comprises a capacitor C2, a resistor R5 and a diode D6, wherein the resistor R5 and the diode D6 are connected in series between the first terminal and the second terminal of the primary coil L0, the cathode of the diode D6 is connected to the resistor R5, the capacitor C2 is connected in parallel to the resistor R5, and the second terminal of the primary coil L0 of the high-frequency transformer T1 is respectively connected to the cathode of the diode D6 and the eighth pin of the power chip U1.

7. The power control circuit according to claim 5, characterized in that: The AC-DC conversion circuit (3) further comprises a feedback loop (31) connected to the power chip U1; the feedback loop (31) comprises a capacitor C13, a MOS tube Q2, a resistor R29, a capacitor C5, a resistor R25, a resistor R30, a voltage regulator tube Z3 and a capacitor C9; The D pole of the MOS tube Q2 is respectively connected to the 4th pin of the power chip U1, one end of the capacitor C13, and one end of the capacitor C5, the other end of the capacitor C13 is connected to the ground GND, the S pole of the MOS tube Q2 is connected to the ground GND through the resistor R29, the G pole of the MOS tube Q2 is connected to the ground GND through the resistors R25 and R30 connected in series in sequence, the voltage regulator tube Z3 and the capacitor C9 are connected in series and then connected in parallel with the resistor R30, the anode of the voltage regulator tube Z3 is respectively connected to the other end of the capacitor C5 and the node between the resistor R25 and the resistor R30, and the cathode of the voltage regulator tube Z3 is connected to the ground GND through the capacitor C9.

8. The power control circuit according to claim 5, characterized in that: The 3rd and 5th pins of the power chip U1 are connected to the ground GND, the 2nd pin is connected to the ground GND through a resistor R19 and a capacitor C8 in parallel, the 6th pin is connected to the ground GND through a resistor R20, the 1st pin is connected to the ground GND through capacitors EC3 and C4 in parallel, the positive pole of capacitor EC3 is connected to the 1st pin, and the negative pole is connected to the ground GND, the 1st pin is also connected to a 15V / 500mA power supply through a diode D15, the cathode of the diode D15 is connected to the 1st pin, and the anode is connected to the 15V / 500mA power supply.

9. The power control circuit according to claim 1, characterized in that: The rectification and surge interference prevention circuit (1) comprises an A-phase input terminal, a B-phase input terminal, a C-phase input terminal, a varistor VR1, a varistor VR2, a varistor VR3, a diode D3, a diode D4 and a winding resistor FR1; two ends of the varistor VR1 are respectively connected to the C-phase input terminal and the B-phase input terminal, two ends of the varistor VR2 are respectively connected to the A-phase input terminal and the B-phase input terminal, the A-phase input terminal is connected to the anode of the diode D3, the C-phase input terminal is connected to the anode of the diode D4, the cathode of the diode D3 is connected to the cathode of the diode D4 and then connected to one end of the winding resistor FR1, the other end of the winding resistor FR1 is respectively connected to the switch circuit (20) of the switch control circuit (2) and one end of the varistor VR3, the other end of the varistor VR3 is connected to the B-phase input terminal and then connected to the ground GND.

10. The power control circuit according to claim 1 or 4, characterized in that: It also includes an LDO chip U3, the first pin of the LDO chip U3 is connected to the positive electrode of the energy storage capacitor C7, the second pin is connected to the ground GND, the third pin is connected to the VCC power supply, and is connected to the ground GND through parallel capacitors C12 and C22.

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