Silicon controlled rectifier control system and switching power supply

Abstract

The embodiment of the application discloses a silicon controlled rectifier control system and a switching power supply, wherein the system comprises: a power supply circuit, a zero-crossing detection circuit for detecting an AC zero-crossing point signal, a silicon controlled rectifier control circuit for controlling a load and an MCU control circuit; the power supply circuit is electrically connected with the zero-crossing detection circuit, the silicon controlled rectifier control circuit and the MCU control circuit, and is used for converting AC into 12V DC and 5V DC; the MCU control circuit is electrically connected with the zero-crossing detection circuit and the silicon controlled rectifier control circuit, and is used for controlling the on-off of the silicon controlled rectifier control circuit according to the zero-crossing point signal; a freewheeling diode corresponding to the 12V DC is arranged in the zero-crossing detection circuit, and the zero-crossing detection circuit does not arrange the freewheeling diode corresponding to the 5V DC. Thus, voltage backflow is avoided, damage to components is avoided, and the stability of the system is improved.

Description

Technical Field

[0001] This invention relates to the field of switching power supply technology, and in particular to a thyristor control system and a switching power supply. Background Technology

[0002] Current thyristor control systems use zero-crossing detection circuits to detect the zero-crossing signal of AC current. The MCU (microcontroller unit) chip controls the on / off state of the thyristor control circuit based on the zero-crossing signal. Under normal circumstances, current should flow from high level to low level. However, existing thyristor control systems have negative current during the positive half-wave, which can cause voltage reverse flow, damaging components and affecting system stability. Summary of the Invention

[0003] Based on this, it is necessary to address the problem that existing thyristor control systems have negative current during the positive half-wave, which can lead to voltage backflow, damage components, and affect system stability. Therefore, a thyristor control system and switching power supply are proposed.

[0004] This application proposes a thyristor control system, the system comprising: a power supply circuit, a zero-crossing detection circuit for detecting the zero-crossing signal of AC power, a thyristor control circuit for controlling the load, and an MCU control circuit.

[0005] The power supply circuit is electrically connected to the zero-crossing detection circuit, the thyristor control circuit, and the MCU control circuit, and is used to convert AC power into 12V DC power and 5V DC power;

[0006] The MCU control circuit is electrically connected to the zero-crossing detection circuit and the thyristor control circuit, and is used to control the on / off state of the thyristor control circuit according to the zero-crossing signal.

[0007] The zero-crossing detection circuit includes a freewheeling diode corresponding to the 12V DC power, but does not include a freewheeling diode corresponding to the 5V DC power.

[0008] Furthermore, the zero-crossing detection circuit includes: a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, the freewheeling diode, a first capacitor, and a PNP transistor;

[0009] The first end of the first resistor is electrically connected to the power supply circuit, the second end of the first resistor is electrically connected to the first end of the second resistor, the anode of the freewheeling diode is electrically connected to the second end of the second resistor, the first end of the third resistor and the base of the PNP transistor, the cathode of the freewheeling diode is electrically connected to the 12V DC output terminal of the power supply circuit, and the second end of the third resistor and the emitter of the PNP transistor are both electrically connected to the 5V DC output terminal of the power supply circuit.

[0010] The collector (C) of the PNP transistor is electrically connected to the first terminal of the fourth resistor and the first terminal of the fifth resistor. The second terminal of the fifth resistor and the first terminal of the first capacitor are both electrically connected to the MCU control circuit. The second terminal of the fourth resistor and the second terminal of the first capacitor are both grounded.

[0011] Furthermore, the power supply circuit includes: a varistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, a ninth capacitor, a tenth capacitor, a first diode, a second diode, a third diode, a fourth diode, a first inductor, a second inductor, a common-mode inductor, a first electrolytic capacitor, a second electrolytic capacitor, a third electrolytic capacitor, a fourth electrolytic capacitor, a fifth electrolytic capacitor, a ground terminal, a switching power supply chip, and a step-down chip;

[0012] The first terminal of the varistor, the first terminal of the second capacitor, the first terminal of the eighth resistor, the first terminal of the third capacitor, the first terminal of the first inductor, and the negative terminal of the first electrolytic capacitor are all electrically connected to the neutral wire of the AC power supply. The first terminal of the sixth resistor is electrically connected to the live wire of the AC power supply. The second terminal of the sixth resistor is electrically connected to the second terminal of the varistor, the second terminal of the second capacitor, the first terminal of the seventh resistor, the first terminal of the fourth capacitor, the first terminal of the first resistor, and the positive terminal of the first diode. The second terminal of the seventh resistor is electrically connected to the second terminal of the eighth resistor. The ground terminal is connected between the second terminal of the fourth capacitor and the second terminal of the third capacitor.

[0013] The cathode of the first diode is electrically connected to the anode of the second diode, and the cathode of the second diode is electrically connected to the anode of the first electrolytic capacitor and the first terminal of the second inductor.

[0014] The second terminal of the first inductor is electrically connected to the negative terminal of the second electrolytic capacitor, the first terminal of the common mode inductor, the positive terminal of the fourth electrolytic capacitor, the positive terminal of the third diode, the output terminal of the 12V DC power supply, the first terminal of the eleventh resistor, the first terminal of the seventh capacitor, the first terminal of the eighth capacitor, and the VIN pin of the step-down chip.

[0015] The second terminal of the second inductor is electrically connected to the positive terminal of the second electrolytic capacitor, the switching power supply chip, and the first terminal of the fifth capacitor. The first terminal of the ninth resistor is electrically connected to the second terminal of the fifth capacitor. The second terminal of the ninth resistor is electrically connected to the two GND pins of the switching power supply chip, the negative terminal of the third electrolytic capacitor, the second terminal of the common mode inductor, the first terminal of the sixth capacitor, and the negative terminal of the fourth diode. The VCC pin of the switching power supply chip is electrically connected to the positive terminal of the third electrolytic capacitor and the negative terminal of the third diode. The second terminal of the sixth capacitor is electrically connected to the first terminal of the tenth resistor.

[0016] The VOUT pin of the step-down chip is electrically connected to the first terminal of the ninth capacitor, the positive terminal of the fifth electrolytic capacitor, the first terminal of the twelfth resistor, the first terminal of the tenth capacitor, and the output terminal of the 5V DC power supply.

[0017] The second terminal of the tenth resistor, the positive terminal of the fourth diode, the negative terminal of the fourth electrolytic capacitor, the second terminal of the eleventh resistor, the second terminal of the seventh capacitor, the second terminal of the eighth capacitor, the GND pin of the step-down chip, the second terminal of the ninth capacitor, the negative terminal of the fifth electrolytic capacitor, the second terminal of the twelfth resistor, and the second terminal of the tenth capacitor are all grounded.

[0018] Furthermore, the system also includes: a central heating wire and a side heating wire, wherein the central heating wire is connected in series with the silicon controlled rectifier circuit and then connected in parallel with the side heating wire, and the side heating wire is connected between the neutral wire and the live wire;

[0019] The thyristor control circuit includes: a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eleventh capacitor, a twelfth capacitor, an optocoupler, and a thyristor;

[0020] The first end of the intermediate heating wire is electrically connected to the live wire, the second end of the intermediate heating wire is electrically connected to the first end of the eleventh capacitor, the first end of the thyristor and the fourth pin of the optocoupler, and the second end of the eleventh capacitor is electrically connected to the first end of the thirteenth resistor.

[0021] The second terminal of the thyristor is electrically connected to the first terminal of the fourteenth resistor and the first terminal of the sixteenth resistor; the second terminal of the fourteenth resistor is electrically connected to the first terminal of the twelfth capacitor and the first terminal of the fifteenth resistor; and the second terminal of the sixteenth resistor is electrically connected to the sixth pin of the optocoupler.

[0022] The second pin of the optocoupler is grounded, the first pin of the optocoupler is electrically connected to the first end of the seventeenth resistor, and the second end of the seventeenth resistor is electrically connected to the MCU control circuit.

[0023] The second terminal of the thirteenth resistor, the third terminal of the thyristor, the second terminal of the twelfth capacitor, and the second terminal of the fifteenth resistor are all electrically connected to the neutral line.

[0024] Furthermore, the thyristor control circuit also includes a connector, the first end of which is electrically connected to the first end of the eleventh capacitor, the first end of the thyristor, and the fourth pin of the optocoupler, and the second end of which is electrically connected to the second end of the intermediate heating wire, wherein the connector uses copper inserts.

[0025] Furthermore, the thyristor control circuit also includes a test terminal, which is electrically connected to the third terminal of the thyristor.

[0026] Furthermore, the system also includes a double-pole switch connected between the power supply circuit and the thyristor control circuit.

[0027] Furthermore, the system also includes a neutral wire relay, which is installed between the neutral wire output terminal of the double-pole switch and the thyristor control circuit, and is electrically connected to the output terminal of the 12V DC power supply and the MCU control circuit.

[0028] Furthermore, the system also includes: a live wire relay, the first end of which is electrically connected to the live wire output terminal of the double-pole switch, and the second end of which is electrically connected to the intermediate heating wire and the side heating wire.

[0029] This application also proposes a switching power supply, the switching power supply comprising: a thyristor control system as described in any of the preceding claims.

[0030] The thyristor control system of this application converts AC power into 12V DC power and 5V DC power through a power supply circuit. The zero-crossing detection circuit is equipped with a freewheeling diode corresponding to the 12V DC power, while the zero-crossing detection circuit is not equipped with the freewheeling diode corresponding to the 5V DC power, thereby avoiding voltage backflow, preventing damage to components, and improving the stability of the system. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] in:

[0033] Figure 1 This is a block diagram of a thyristor control system in one embodiment;

[0034] Figure 2 This is a schematic diagram of the MCU control circuit in one embodiment;

[0035] Figure 3 This is a schematic diagram of the power supply circuit and zero-crossing detection circuit in one embodiment;

[0036] Figure 4 This is a schematic diagram of a thyristor control circuit, a neutral wire relay, and a live wire relay in one embodiment;

[0037] Figure 5 A schematic diagram showing the direction of current in the presence of voltage reverse flow;

[0038] Figure 6 This is a schematic diagram of the current direction of the positive half-wave of the alternating current in this application. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] like Figure 1 As shown, this application proposes a thyristor Q11 control system, the system comprising: a power supply circuit 100, a zero-crossing detection circuit 200 for detecting the zero-crossing signal of AC power, a thyristor Q11 control circuit 400 for controlling the load, and an MCU control circuit.

[0041] The power supply circuit 100 is electrically connected to the zero-crossing detection circuit 200, the thyristor Q11 control circuit 400, and the MCU control circuit, and is used to convert AC power into 12V DC power and 5V DC power.

[0042] The MCU control circuit is electrically connected to the zero-crossing detection circuit 200 and the thyristor Q11 control circuit 400, and is used to control the on / off state of the thyristor Q11 control circuit 400 according to the zero-crossing signal.

[0043] The zero-crossing detection circuit 200 includes a freewheeling diode corresponding to the 12V DC power, but does not include a freewheeling diode corresponding to the 5V DC power.

[0044] In this embodiment, the system converts AC power to 12V DC power and 5V DC power through the power supply circuit 100. The zero-crossing detection circuit 200 is equipped with a freewheeling diode corresponding to the 12V DC power, but the zero-crossing detection circuit 200 is not equipped with the freewheeling diode corresponding to the 5V DC power, thereby avoiding voltage backflow, preventing damage to components, and improving the stability of the system.

[0045] The load includes, but is not limited to, incandescent lamps.

[0046] The power supply circuit 100 receives AC power from an AC power source via an AC interface, and then converts the AC power into 12V DC and 5V DC. The 12V DC is 12V direct current. The 5V DC is 5V direct current.

[0047] like Figure 2 As shown, the MCU control circuit includes an MCU chip U3 and supporting circuitry. The MCU chip controls the switching on and off of the optocoupler U4 in the SCR Q11 control circuit 400 by outputting high and low levels. The switching on and off of the optocoupler U4 controls the SCR Q11 in the SCR Q11 control circuit 400. The MCU control circuit is electrically connected to the 5V DC output terminal of the power supply circuit 100.

[0048] The freewheeling diode is a diode.

[0049] like Figure 3 As shown, in one embodiment, the zero-crossing detection circuit 200 includes: a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R75, a fifth resistor R79, the freewheeling diode, a first capacitor C1, and a PNP transistor Q1.

[0050] The first end of the first resistor R1 is electrically connected to the power supply circuit 100, the second end of the first resistor R1 is electrically connected to the first end of the second resistor R2, the anode of the freewheeling diode is electrically connected to the second end of the second resistor R2, the first end of the third resistor R3 and the base of the PNP transistor Q1, the cathode of the freewheeling diode is electrically connected to the 12V DC output terminal of the power supply circuit 100, and the second end of the third resistor R3 and the emitter of the PNP transistor Q1 are both electrically connected to the 5V DC output terminal of the power supply circuit 100.

[0051] The collector (C) of the PNP transistor Q1 is electrically connected to the first terminal of the fourth resistor R75 and the first terminal of the fifth resistor R79. The second terminal of the fifth resistor R79 and the first terminal of the first capacitor C1 are both electrically connected to the MCU control circuit. The second terminals of the fourth resistor R75 and the first capacitor C1 are both grounded. By setting a freewheeling diode corresponding to the 12V DC power supply, and by not setting a freewheeling diode corresponding to the 5V DC power supply in the zero-crossing detection circuit 200, voltage reverse flow is avoided, preventing damage to components and improving system stability.

[0052] The first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R75, and the fifth resistor R79 are all resistors.

[0053] The first capacitor, C1, is a capacitor.

[0054] like Figure 3 As shown, in one embodiment, the power supply circuit 100 includes: a varistor MOV1, a sixth resistor R10, a seventh resistor R8, an eighth resistor R5, a ninth resistor R9, a tenth resistor R11, an eleventh resistor R6, a twelfth resistor R7, a second capacitor CX1, a third capacitor CY1, a fourth capacitor CY2, a fifth capacitor C6, a sixth capacitor C7, a seventh capacitor C5, an eighth capacitor C3, a ninth capacitor C2, a tenth capacitor C4, a first diode D3, a second diode D4, a third diode D1, a fourth diode D5, a first inductor L1, a second inductor L3, a common-mode inductor L2, a first electrolytic capacitor EC1, a second electrolytic capacitor EC4, a third electrolytic capacitor EC5, a fourth electrolytic capacitor EC2, a fifth electrolytic capacitor EC3, a ground terminal, a switching power supply chip U2, and a buck chip U1.

[0055] The first terminal of the varistor MOV1, the first terminal of the second capacitor CX1, the first terminal of the eighth resistor R5, the first terminal of the third capacitor CY1, the first terminal of the first inductor L1, and the negative terminal of the first electrolytic capacitor EC1 are all electrically connected to the neutral wire of the AC power supply. The first terminal of the sixth resistor R10 is electrically connected to the live wire of the AC power supply. The second terminal of the sixth resistor R10 is electrically connected to the second terminal of the varistor MOV1, the second terminal of the second capacitor CX1, the first terminal of the seventh resistor R8, the first terminal of the fourth capacitor CY2, the first terminal of the first resistor R1, and the positive terminal of the first diode D3. The second terminal of the seventh resistor R8 is electrically connected to the second terminal of the eighth resistor R5. The ground terminal is connected between the second terminal of the fourth capacitor CY2 and the second terminal of the third capacitor CY1.

[0056] The cathode of the first diode D3 is electrically connected to the anode of the second diode D4, and the cathode of the second diode D4 is electrically connected to the anode of the first electrolytic capacitor EC1 and the first terminal of the second inductor L3.

[0057] The second terminal of the first inductor L1 is electrically connected to the negative terminal of the second electrolytic capacitor EC4, the first terminal of the common mode inductor L2, the positive terminal of the fourth electrolytic capacitor EC2, the positive terminal of the third diode D1, the output terminal of the 12V DC power supply, the first terminal of the eleventh resistor R6, the first terminal of the seventh capacitor C5, the first terminal of the eighth capacitor C3, and the VIN pin of the step-down chip U1.

[0058] The second terminal of the second inductor L3 is electrically connected to the positive terminal of the second electrolytic capacitor EC4, the switching power supply chip U2, and the first terminal of the fifth capacitor C6. The first terminal of the ninth resistor R9 is electrically connected to the second terminal of the fifth capacitor C6. The second terminal of the ninth resistor R9 is electrically connected to the two GND pins of the switching power supply chip U2, the negative terminal of the third electrolytic capacitor EC5, the second terminal of the common mode inductor L2, the first terminal of the sixth capacitor C7, and the negative terminal of the fourth diode D5. The VCC pin of the switching power supply chip U2 is electrically connected to the positive terminal of the third electrolytic capacitor EC5 and the negative terminal of the third diode D1. The second terminal of the sixth capacitor C7 is electrically connected to the first terminal of the tenth resistor R11.

[0059] The VOUT pin of the step-down chip U1 is electrically connected to the first terminal of the ninth capacitor C2, the positive terminal of the fifth electrolytic capacitor EC3, the first terminal of the twelfth resistor R7, the first terminal of the tenth capacitor C4, and the output terminal of the 5V DC power supply.

[0060] The second terminal of the tenth resistor R11, the positive terminal of the fourth diode D5, the negative terminal of the fourth electrolytic capacitor EC2, the second terminal of the eleventh resistor R6, the second terminal of the seventh capacitor C5, the second terminal of the eighth capacitor C3, the GND pin of the step-down chip U1, the second terminal of the ninth capacitor C2, the negative terminal of the fifth electrolytic capacitor EC3, the second terminal of the twelfth resistor R7, and the second terminal of the tenth capacitor C4 are all grounded.

[0061] The sixth resistor R10, the seventh resistor R8, the eighth resistor R5, the ninth resistor R9, the tenth resistor R11, the eleventh resistor R6, and the twelfth resistor R7 are all resistors.

[0062] The second capacitor CX1, the third capacitor CY1, the fourth capacitor CY2, the fifth capacitor C6, the sixth capacitor C7, the seventh capacitor C5, the eighth capacitor C3, the ninth capacitor C2, and the tenth capacitor C4 are all capacitors.

[0063] The first diode D3, the second diode D4, the third diode D1, and the fourth diode D5 are all diodes.

[0064] Both the first inductor L1 and the second inductor L3 are inductors.

[0065] The common-mode inductor L2 is an inductor with a magnetic core or an iron core.

[0066] The first electrolytic capacitor EC1, the second electrolytic capacitor EC4, the third electrolytic capacitor EC5, the fourth electrolytic capacitor EC2, and the fifth electrolytic capacitor EC3 are all electrolytic capacitors.

[0067] A copper connector is used as the grounding terminal interface.

[0068] The switching power supply chip U2, also known as a switching power supply management chip, is used to convert AC power to DC power.

[0069] The step-down chip U1 uses a chip that can reduce voltage.

[0070] The second terminal of the second inductor L3 is electrically connected to pins 5, 6, 7, and 8 of the switching power supply chip U2. Pins 5 and 6 of the switching power supply chip U2 are both NC, and pins 7 and 8 of the switching power supply chip U2 are both SW.

[0071] like Figure 4 As shown, in one embodiment, the above system further includes: a middle heating wire HOT2 and a side heating wire HOT1, wherein the middle heating wire HOT2 is connected in series with the silicon controlled rectifier Q11 control circuit 400 and then connected in parallel with the side heating wire HOT1, and the side heating wire HOT1 is connected between the neutral wire and the live wire.

[0072] The thyristor Q11 control circuit 400 includes: a thirteenth resistor R4, a fourteenth resistor R76, a fifteenth resistor R84, a sixteenth resistor R13, a seventeenth resistor R77, an eleventh capacitor C16, a twelfth capacitor C17, an optocoupler U4, and a thyristor Q11.

[0073] The first end of the intermediate heating wire HOT2 is electrically connected to the live wire, the second end of the intermediate heating wire HOT2 is electrically connected to the first end of the eleventh capacitor C16, the first end of the silicon controlled rectifier Q11 and the fourth pin of the optocoupler U4, and the second end of the eleventh capacitor C16 is electrically connected to the first end of the thirteenth resistor R4.

[0074] The second terminal of the thyristor Q11 is electrically connected to the first terminal of the fourteenth resistor R76 and the first terminal of the sixteenth resistor R13. The second terminal of the fourteenth resistor R76 is electrically connected to the first terminal of the twelfth capacitor C17 and the first terminal of the fifteenth resistor R84. The second terminal of the sixteenth resistor R13 is electrically connected to the sixth pin of the optocoupler U4.

[0075] The second pin of the optocoupler U4 is grounded, the first pin of the optocoupler U4 is electrically connected to the first end of the seventeenth resistor R77, and the second end of the seventeenth resistor R77 is electrically connected to the MCU control circuit.

[0076] The second terminal of the thirteenth resistor R4, the third terminal of the thyristor Q11, the second terminal of the twelfth capacitor C17, and the second terminal of the fifteenth resistor R84 are all electrically connected to the neutral line.

[0077] Both the central heating wire HOT2 and the side heating wire HOT1 use heating wires.

[0078] The thirteenth resistor R4, the fourteenth resistor R76, the fifteenth resistor R84, the sixteenth resistor R13, and the seventeenth resistor R77 are all resistors.

[0079] Both the eleventh capacitor C16 and the twelfth capacitor C17 are capacitors.

[0080] The second end of the seventeenth resistor R77 is connected to pin 19 of the MCU chip U3 in the MCU control circuit.

[0081] In one embodiment, the aforementioned thyristor Q11 control circuit 400 further includes a connector. The first end of the connector is electrically connected to the first end of the eleventh capacitor C16, the first end of the thyristor Q11, and the fourth pin of the optocoupler U4. The second end of the connector is electrically connected to the second end of the intermediate heating wire HOT2. The connector uses copper contacts. Copper contacts facilitate quick and accurate connection of the intermediate heating wire HOT2.

[0082] In one embodiment, the aforementioned thyristor Q11 control circuit 400 further includes a test terminal, which is electrically connected to the third terminal of the thyristor Q11. The test terminal is used to test the thyristor Q11 control system.

[0083] In one embodiment, the system further includes a double-pole switch connected between the power supply circuit 100 and the thyristor Q11 control circuit 400. It is understood that in this embodiment, the first terminal of the varistor MOV1, the first terminal of the second capacitor CX1, the first terminal of the eighth resistor R5, the first terminal of the third capacitor CY1, the first terminal of the first inductor L1, and the negative terminal of the first electrolytic capacitor EC1 are all electrically connected to the neutral wire of the AC power supply, and the first terminal of the sixth resistor R10 is electrically connected to the live wire of the AC power supply.

[0084] The double-pole switch includes a first switch and a second switch. The first terminal of the first switch is electrically connected to the neutral wire of the AC power supply, and the second terminal of the first switch is electrically connected to the control circuit 400 of the silicon controlled rectifier (SCR) Q11. The first terminal of the second switch is electrically connected to the live wire of the AC power supply, and the second terminal of the first switch is electrically connected to the control circuit 400 of the SCR Q11.

[0085] like Figure 4 As shown, in one embodiment, the system further includes a neutral wire relay, which is installed between the neutral wire output terminal of the double-pole switch and the thyristor Q11 control circuit 400, and is electrically connected to the output terminal of the 12V DC power supply and the MCU control circuit.

[0086] like Figure 4 As shown, in one embodiment, the system further includes a live wire relay, the first end of which is electrically connected to the live wire output terminal of the double-pole switch, and the second end of which is electrically connected to the intermediate heating wire HOT2 and the side heating wire HOT1.

[0087] Figure 4The diagram illustrates the neutral wire relay and the live wire relay. In the live wire relay, R17, R19, and RJ25 are resistors, Q4 is an NPN transistor, GND is the ground terminal, VDD_12V is connected to the output terminal of the 12V DC power supply, the end of R17 furthest from Q4 is connected to pin 23 of the MCU chip U3 in the MCU control circuit, D7 is a diode, and RY1 is a three-phase switch. In the neutral wire relay, R18, R20, and RJ1 are resistors, Q5 is an NPN transistor, GND is the ground terminal, VDD_12V is connected to the output terminal of the 12V DC power supply, the end of R18 furthest from Q5 is connected to pin 24 of the MCU chip U3 in the MCU control circuit, D6 is a diode, and RY2 is a three-phase switch.

[0088] Figure 5 The diagram illustrates the current direction when a freewheeling diode corresponding to the 5V DC power supply is provided in the zero-crossing detection circuit 200, and when no freewheeling diode corresponding to the 12V DC power supply is provided in the zero-crossing detection circuit 200. (a) shows the current direction during the negative half-wave of the AC power supply; (b) shows the current direction during the positive half-wave of the AC power supply. In this case, the current flows from the live wire through the current-limiting resistors R1 and R2, then through the diode D2 back to the output terminal of the 5V DC power supply, and then through U1 back to the neutral wire, forming a complete loop. Under normal circumstances, the current should flow from the high level 12V to the low level 5V. However, in (b), although the circuit can form a loop, there is a negative current, which will cause voltage backflow. Furthermore, the negative current will also pass through U1, thereby damaging U1 and affecting the stability of the entire circuit. In (b), the distortion of the zero-crossing detection circuit 200 is severe. When paired with the thyristor Q11 control circuit 400, the distortion of the zero-crossing signal will cause a large error between the actual switching time of the thyristor Q11 and the AC power supply.

[0089] When controlling the load through the thyristor Q11, theoretically, the closer the opening and closing time of the thyristor Q11 is to the zero point of the AC power supply, the smaller the impact on EMI (that is, the circuit formed by the live wire, the intermediate heating wire HOT2, pin 2 of Q11, pin 1 of Q11, and the neutral wire).

[0090] Figure 6The diagram illustrates the current direction in which a freewheeling diode corresponding to the 12V DC power supply is provided in the zero-crossing detection circuit 200, and the freewheeling diode corresponding to the 5V DC power supply is not provided in the zero-crossing detection circuit 200. In this current direction, during the positive half-wave of the AC power supply, the current will directly return from the output terminal of the 12V DC power supply to the zero line without passing through the voltage drop of U1. This avoids voltage backflow, retains all components with a common 5V, and also improves the accuracy of the zero-crossing signal, making the zero-crossing signal basically coincide with the zero point of the AC power supply. This makes the switching time of the thyristor Q11 infinitely close to the zero point of the AC power supply, reducing the electromagnetic interference of the entire circuit.

[0091] like Figure 4 As shown, in one embodiment, the thyristor Q11 control system further includes: resistor R82, resistor R85, and capacitor CX2.

[0092] This application also proposes a switching power supply, the switching power supply comprising: a thyristor Q11 control system as described in any of the preceding claims;

[0093] The system includes: a power supply circuit 100, a zero-crossing detection circuit 200 for detecting the zero-crossing signal of AC power, a thyristor Q11 control circuit 400 for controlling the load, and an MCU control circuit.

[0094] The power supply circuit 100 is electrically connected to the zero-crossing detection circuit 200, the thyristor Q11 control circuit 400, and the MCU control circuit, and is used to convert AC power into 12V DC power and 5V DC power.

[0095] The MCU control circuit is electrically connected to the zero-crossing detection circuit 200 and the thyristor Q11 control circuit 400, and is used to control the on / off state of the thyristor Q11 control circuit 400 according to the zero-crossing signal.

[0096] The zero-crossing detection circuit 200 includes a freewheeling diode corresponding to the 12V DC power, but does not include a freewheeling diode corresponding to the 5V DC power.

[0097] In this embodiment, the system converts AC power to 12V DC power and 5V DC power through the power supply circuit 100. The zero-crossing detection circuit 200 is equipped with a freewheeling diode corresponding to the 12V DC power, but the zero-crossing detection circuit 200 is not equipped with the freewheeling diode corresponding to the 5V DC power, thereby avoiding voltage backflow, preventing damage to components, and improving the stability of the system.

[0098] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0099] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A thyristor control system, characterized in that, The system includes: a power supply circuit, a zero-crossing detection circuit for detecting the zero-crossing signal of AC power, a thyristor control circuit for controlling the load, and an MCU control circuit. The power supply circuit is electrically connected to the zero-crossing detection circuit, the thyristor control circuit, and the MCU control circuit, and is used to convert AC power into 12V DC power and 5V DC power; The MCU control circuit is electrically connected to the zero-crossing detection circuit and the thyristor control circuit, and is used to control the on / off state of the thyristor control circuit according to the zero-crossing signal. The zero-crossing detection circuit includes a freewheeling diode corresponding to the 12V DC power, but does not include a freewheeling diode corresponding to the 5V DC power. The zero-crossing detection circuit includes: a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a freewheeling diode, a first capacitor, and a PNP transistor; The first end of the first resistor is electrically connected to the live wire of the power supply circuit, the second end of the first resistor is electrically connected to the first end of the second resistor, the anode of the freewheeling diode is electrically connected to the second end of the second resistor, the first end of the third resistor and the base of the PNP transistor, the cathode of the freewheeling diode is electrically connected to the 12V DC output terminal of the power supply circuit, and the second end of the third resistor and the emitter of the PNP transistor are both electrically connected to the 5V DC output terminal of the power supply circuit. The collector (C) of the PNP transistor is electrically connected to the first terminal of the fourth resistor and the first terminal of the fifth resistor. The second terminal of the fifth resistor and the first terminal of the first capacitor are both electrically connected to the MCU control circuit. The second terminal of the fourth resistor and the second terminal of the first capacitor are both grounded.

2. The thyristor control system according to claim 1, characterized in that, The power supply circuit includes: a varistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, a ninth capacitor, a tenth capacitor, a first diode, a second diode, a third diode, a fourth diode, a first inductor, a second inductor, a common-mode inductor, a first electrolytic capacitor, a second electrolytic capacitor, a third electrolytic capacitor, a fourth electrolytic capacitor, a fifth electrolytic capacitor, a ground terminal, a switching power supply chip, and a step-down chip; The first terminal of the varistor, the first terminal of the second capacitor, the first terminal of the eighth resistor, the first terminal of the third capacitor, the first terminal of the first inductor, and the negative terminal of the first electrolytic capacitor are all electrically connected to the neutral wire of the AC power supply. The first terminal of the sixth resistor is electrically connected to the live wire of the AC power supply. The second terminal of the sixth resistor is electrically connected to the second terminal of the varistor, the second terminal of the second capacitor, the first terminal of the seventh resistor, the first terminal of the fourth capacitor, the first terminal of the first resistor, and the positive terminal of the first diode. The second terminal of the seventh resistor is electrically connected to the second terminal of the eighth resistor. The ground terminal is connected between the second terminal of the fourth capacitor and the second terminal of the third capacitor. The cathode of the first diode is electrically connected to the anode of the second diode, and the cathode of the second diode is electrically connected to the anode of the first electrolytic capacitor and the first terminal of the second inductor. The second terminal of the first inductor is electrically connected to the negative terminal of the second electrolytic capacitor, the first terminal of the common mode inductor, the positive terminal of the fourth electrolytic capacitor, the positive terminal of the third diode, the output terminal of the 12V DC power supply, the first terminal of the eleventh resistor, the first terminal of the seventh capacitor, the first terminal of the eighth capacitor, and the VIN pin of the step-down chip. The second terminal of the second inductor is electrically connected to the positive terminal of the second electrolytic capacitor, the switching power supply chip, and the first terminal of the fifth capacitor. The first terminal of the ninth resistor is electrically connected to the second terminal of the fifth capacitor. The second terminal of the ninth resistor is electrically connected to the two GND pins of the switching power supply chip, the negative terminal of the third electrolytic capacitor, the second terminal of the common mode inductor, the first terminal of the sixth capacitor, and the negative terminal of the fourth diode. The VCC pin of the switching power supply chip is electrically connected to the positive terminal of the third electrolytic capacitor and the negative terminal of the third diode. The second terminal of the sixth capacitor is electrically connected to the first terminal of the tenth resistor. The VOUT pin of the step-down chip is electrically connected to the first terminal of the ninth capacitor, the positive terminal of the fifth electrolytic capacitor, the first terminal of the twelfth resistor, the first terminal of the tenth capacitor, and the output terminal of the 5V DC power supply. The second terminal of the tenth resistor, the positive terminal of the fourth diode, the negative terminal of the fourth electrolytic capacitor, the second terminal of the eleventh resistor, the second terminal of the seventh capacitor, the second terminal of the eighth capacitor, the GND pin of the step-down chip, the second terminal of the ninth capacitor, the negative terminal of the fifth electrolytic capacitor, the second terminal of the twelfth resistor, and the second terminal of the tenth capacitor are all grounded.

3. The thyristor control system according to claim 2, characterized in that, The system further includes: a middle heating wire and a side heating wire, wherein the middle heating wire is connected in series with the silicon controlled rectifier circuit and then connected in parallel with the side heating wire, and the side heating wire is connected between the neutral wire and the live wire; The thyristor control circuit includes: a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eleventh capacitor, a twelfth capacitor, an optocoupler, and a thyristor; The first end of the intermediate heating wire is electrically connected to the live wire, the second end of the intermediate heating wire is electrically connected to the first end of the eleventh capacitor, the first end of the thyristor and the fourth pin of the optocoupler, and the second end of the eleventh capacitor is electrically connected to the first end of the thirteenth resistor. The second terminal of the thyristor is electrically connected to the first terminal of the fourteenth resistor and the first terminal of the sixteenth resistor; the second terminal of the fourteenth resistor is electrically connected to the first terminal of the twelfth capacitor and the first terminal of the fifteenth resistor; and the second terminal of the sixteenth resistor is electrically connected to the sixth pin of the optocoupler. The second pin of the optocoupler is grounded, the first pin of the optocoupler is electrically connected to the first end of the seventeenth resistor, and the second end of the seventeenth resistor is electrically connected to the MCU control circuit. The second terminal of the thirteenth resistor, the third terminal of the thyristor, the second terminal of the twelfth capacitor, and the second terminal of the fifteenth resistor are all electrically connected to the neutral line.

4. The thyristor control system according to claim 3, characterized in that, The thyristor control circuit also includes a connector, the first end of which is electrically connected to the first end of the eleventh capacitor, the first end of the thyristor, and the fourth pin of the optocoupler, and the second end of which is electrically connected to the second end of the intermediate heating wire, wherein the connector uses copper inserts.

5. The thyristor control system according to claim 3, characterized in that, The thyristor control circuit also includes: The test terminal is electrically connected to the third terminal of the thyristor.

6. The thyristor control system according to claim 3, characterized in that, The system also includes a double-pole switch, which is connected between the power supply circuit and the thyristor control circuit.

7. The thyristor control system according to claim 6, characterized in that, The system also includes a neutral wire relay, which is installed between the neutral wire output terminal of the double-pole switch and the thyristor control circuit. The neutral wire relay is electrically connected to the output terminal of the 12V DC power supply and the MCU control circuit.

8. The thyristor control system according to claim 6, characterized in that, The system also includes a live wire relay, the first end of which is electrically connected to the live wire output terminal of the double-pole switch, and the second end of which is electrically connected to the intermediate heating wire and the side heating wire.

9. A switching power supply, characterized in that, The switching power supply includes: a thyristor control system as described in any one of claims 1 to 8.

Images