An ac relay hysteresis control circuit suitable for use in power products

Abstract

The present application relates to the technical field of AC relay, and discloses an AC relay hysteresis control circuit suitable for power products, which comprises a bridge full-wave rectifier circuit, a high-voltage detection circuit, a high-voltage linear voltage stabilizing circuit, a thyristor control circuit and an AC relay, is used for detecting commercial power and driving the AC relay to output power supply to a load; the L and N terminals are connected with the input of the bridge full-wave rectifier circuit, the output of the rectifier circuit is connected with the input of the high-voltage detection circuit and the high-voltage linear voltage stabilizing circuit, the output of the detection circuit and the output of the voltage stabilizing circuit are connected with the input of the thyristor control circuit, the output of the control circuit is respectively connected with the N terminal and the input of the AC relay, the other end of the relay input is connected with the L terminal, the common terminal of the relay output is connected with the L and N terminals, the normally closed contact is connected with the empty pin, and the normally open contact is connected with the load. The present application improves the problem that the traditional AC relay is prone to failure and the circuit is broken due to frequent attraction and release, realizes the accurate hysteresis on-off control of commercial power detection and the relay, and improves the operation reliability of power equipment.

Description

Technical Field

[0001] This invention relates to the field of AC relay technology, and more particularly to an AC relay hysteresis control circuit suitable for power products. Background Technology

[0002] Nowadays, AC relays are widely used in low-voltage power distribution. They are electronic control devices. When a certain voltage is applied across the coil, a certain current flows through the coil, thereby generating an electromagnetic effect. The armature is attracted by the electromagnetic force and moves towards the moving contact (normally open contact) against the spring tension, breaking away from the stationary contact (normally closed contact) and connecting with the moving contact.

[0003] The minimum operating voltage of an AC relay is generally no more than 70% of its rated voltage. However, in low-voltage power distribution systems, due to the complexity of power user loads and the harshness of the power supply line environment, the mains voltage may still be low. When the mains voltage drops to the operating threshold voltage of the AC relay, the relay will frequently engage and disengage, causing the contacts to switch on and off at high frequency. This is extremely prone to arcing and sparking. This irreversible damage will increase contact impedance, increase losses, reduce service life, and easily cause relay failure and open circuits. It may even cause the relay contacts to fail to disconnect, leading to serious safety accidents. Summary of the Invention

[0004] This invention addresses the shortcomings and defects of existing technologies by providing an AC relay hysteresis control circuit suitable for power products. It improves upon the problems of reduced lifespan and easy failure of traditional AC relays due to frequent engagement and disengagement, and enables precise hysteresis on / off control of AC relays for mains power detection.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] An AC relay hysteresis control circuit suitable for power products includes a bridge full-wave rectifier circuit, a high-voltage detection circuit, a high-voltage linear regulator circuit, a thyristor control circuit, and an AC relay, used to detect the mains voltage and drive the AC relay to output Vout to supply power to the load circuit.

[0007] The L and N terminals of the mains input are connected to the input terminals of the bridge full-wave rectifier circuit, respectively. The positive and negative output terminals of the bridge full-wave rectifier circuit are connected to the input terminals of the high-voltage detection circuit and the high-voltage linear regulator circuit, respectively. The output V1 of the high-voltage detection circuit and the output Vcc of the high-voltage linear regulator circuit are connected to the input terminals of the thyristor control circuit, respectively. One end of the output of the thyristor control circuit is connected to the N terminal, and the other end is connected to the input of the AC relay coil. The other end of the AC relay coil input is connected to the L terminal. The common terminal of the AC relay output is connected to the L and N terminals. The normally closed contact is connected to the empty pin, and the normally open contact is connected to the output Vout. Vout is connected to both ends of the load.

[0008] Preferably, the high-voltage linear regulator circuit includes a Zener diode VD6, an N-channel MOSFET VT1, a current-limiting resistor R3, a current-limiting resistor R4, and a current-limiting resistor R5.

[0009] The output VDAC of the bridge full-wave rectifier circuit is connected to one end of the current-limiting resistor R3. The other end of R3 is connected to the cathode of the Zener diode VD6 and the gate of the MOSFET VT1. The anode of the Zener diode VD6 is connected to PGND. VDAC is connected to one end of the current-limiting resistor R4. The other end of R4 is connected to the drain of VT1. The source of VT1 is connected to one end of the current-limiting resistor R5. The other end of R5 outputs Vcc.

[0010] Preferably, the high-voltage detection circuit includes a rectifier filter safety capacitor C1, a capacitor C2, a Zener diode VD5, a voltage detection chip N1, a current-limiting resistor R1, and a resistor R2;

[0011] The outputs VDAC and PGND of the bridge full-wave rectifier circuit are connected to both ends of C1 respectively. VDAC is connected to one end of the current-limiting resistor R1. The other end of R1 is connected to the cathode of VD5 and one end of R2. The anode of VD5 and the other end of R2 are connected to PGND. The cathode of VD5 is connected to one end of capacitor C2 and input pin 1 of voltage detection chip N1. The other end of capacitor C2 is connected to PGND. Pin 2 of N1 is connected to PGND. Output pin 3 of N1 is connected to V1.

[0012] Preferably, the thyristor control circuit includes an N-channel MOSFET VT3, a P-channel MOSFET VT2, an optically controlled thyristor coupler O1, a bidirectional thyristor VT4, a capacitor C3, and resistors R6 to R13.

[0013] The Vcc output of the high-voltage linear regulator circuit is connected to one end of resistor R6 and the source of MOSFET VT2. The gate of VT2 is connected to the other end of R6 and one end of voltage divider resistor R9. The other end of R9 is connected to the drain of MOSFET VT3, forming the on / off control circuit of Vcc power supply coupler O1. The V1 output of the high-voltage detection circuit is connected to one end of drive resistor R7. The other end of R7 is connected to the gate of VT3 and one end of bleeder resistor R8. The other end of R8 and the source of VT3 are connected to PGND, forming the on / off control circuit of MOSFET VT2. The drain of MOSFET VT2 is connected to one end of current-limiting resistor R10. The other end of R10 is connected to the light control. Pin 1 of thyristor coupler O1, pins 1 and 2 of O1 are the anode and cathode of its internal LED, respectively. Pin 2 of O1 is connected to PGND. Output pins 4 and 6 of O1 are the anodes A1 and A2 of its internal bidirectional thyristor, respectively. Pin 4 of O1 is connected to one end of resistor R12 and the control electrode G of bidirectional thyristor VT4. The other end of R12 is connected to the N terminal. Pin 6 of O1 is connected to one end of current-limiting resistor R11. The other end of R11 is connected to one end of capacitor C3 and one end of R13. The other end of C3 is connected to the N terminal. The other end of R13 is connected to the A2 anode output V2 of VT4. The A1 anode of VT4 is connected to the N terminal, forming the on / off control circuit of thyristor VT4.

[0014] Preferably, the AC relay is a double-pole double-throw AC relay K1;

[0015] K1 contains switch one and switch two;

[0016] Knife switch one includes pins 2, 3, and 4;

[0017] Knife switch two includes pins 6, 7, and 8;

[0018] The common terminal pin 3 is connected to the normally closed contact pin 2, the common terminal pin 6 is connected to the normally closed contact pin 7, the output V2 of the thyristor control circuit is connected to pin 1 of the output terminal of the AC relay K1 coil, pin 8 of K1 is connected to the mains L terminal, pin 3 is connected to the N terminal, pin 6 is connected to the L terminal, pins 4 and 5 of K1 are connected to the output Vout respectively, and Vout is connected to the two ends of the load to supply power to the load;

[0019] The AC relay K1 can be replaced with a single-pole single-throw AC relay, that is, only the part of the above-mentioned knife switch two is retained;

[0020] Based on a single AC relay, multiple AC relays can be connected in parallel according to different output loads.

[0021] Preferably, the bridge full-wave rectifier circuit includes diodes VD1 to VD4;

[0022] The L terminal of the AC power input is connected to the anode of VD1 and the cathode of VD3, the N terminal of the AC power input is connected to the anode of VD2 and the cathode of VD4, the cathodes of VD1 and VD2 are connected to VDAC, and the anodes of VD3 and VD4 are connected to PGND.

[0023] The beneficial technical effects of this invention are: it improves the problem of reduced lifespan and easy failure of traditional AC relays due to frequent engagement and disengagement, and can realize precise hysteresis on / off control of AC relays for mains power detection, thereby improving the operational reliability of power equipment. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the AC relay hysteresis control circuit described in this invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and do not limit the scope of the invention.

[0026] Example.

[0027] An AC relay hysteresis control circuit suitable for power products includes a bridge full-wave rectifier circuit (1), a high-voltage detection circuit (3), a high-voltage linear regulator circuit (2), a thyristor control circuit (4), and an AC relay (5), used to detect the mains voltage and drive the AC relay to output Vout to supply power to the load circuit.

[0028] The bridge full-wave rectifier circuit (1) includes diodes VD1 to VD4.

[0029] The high-voltage linear regulator circuit (2) includes a Zener diode VD6, an N-channel MOSFET VT1, a current-limiting resistor R3, a current-limiting resistor R4, and a current-limiting resistor R5.

[0030] The high-voltage detection circuit (3) includes a rectifier filter safety capacitor C1, a capacitor C2, a Zener diode VD5, a voltage detection chip N1, a current-limiting resistor R1, and a resistor R2.

[0031] The thyristor control circuit (4) includes an N-channel MOSFET VT3, a P-channel MOSFET VT2, an optically controlled thyristor coupler O1, a bidirectional thyristor VT4, a capacitor C3, and resistors R6 to R13.

[0032] The AC relay (5) is a double-pole double-throw AC relay K1; K1 contains a first knife switch and a second knife switch; the first knife switch includes pins 2, 3, and 4; the second knife switch includes pins 6, 7, and 8.

[0033] The L and N terminals of the mains power input are connected to the input terminals of the bridge full-wave rectifier circuit (1), respectively. The positive and negative output terminals of the bridge full-wave rectifier circuit (1) are connected to the input terminals of the high voltage detection circuit (3) and the high voltage linear regulator circuit (2), respectively. The output V1 of the high voltage detection circuit (3) and the output Vcc of the high voltage linear regulator circuit (2) are connected to the input terminals of the thyristor control circuit (4), respectively. One end of the output of the thyristor control circuit (4) is connected to the N terminal and the other end is connected to the input of the coil of the AC relay (5). The other end of the input of the coil of the AC relay (5) is connected to the L terminal. The common terminal of the output of the AC relay (5) is connected to the L terminal and the N terminal. The normally closed contact is connected to the empty pin and the normally open contact is connected to the output Vout. Vout is connected to both ends of the load.

[0034] The L terminal of the AC power input is connected to the anode of VD1 and the cathode of VD3, the N terminal of the AC power input is connected to the anode of VD2 and the cathode of VD4, the cathodes of VD1 and VD2 are connected to VDAC, and the anodes of VD3 and VD4 are connected to PGND.

[0035] The output VDAC of the bridge full-wave rectifier circuit (1) is connected to one end of the current limiting resistor R3. The other end of R3 is connected to the cathode of the Zener diode VD6 and the gate of the MOSFET VT1, respectively. The anode of the Zener diode VD6 is connected to PGND. VDAC is connected to one end of the current limiting resistor R4. The other end of R4 is connected to the drain of VT1. The source of VT1 is connected to one end of the current limiting resistor R5. The other end of R5 outputs Vcc.

[0036] The outputs VDAC and PGND of the bridge full-wave rectifier circuit (1) are connected to both ends of C1 respectively. VDAC is connected to one end of the current limiting resistor R1. The other end of R1 is connected to the cathode of VD5 and one end of R2. The anode of VD5 and the other end of R2 are connected to PGND. The cathode of VD5 is connected to one end of capacitor C2 and the input pin 1 of voltage detection chip N1. The other end of capacitor C2 is connected to PGND. Pin 2 of N1 is connected to PGND. The output pin 3 of N1 is connected to V1.

[0037] The Vcc output of the high-voltage linear regulator circuit (2) is connected to one end of resistor R6 and the source of MOSFET VT2. The gate of VT2 is connected to the other end of R6 and one end of voltage divider resistor R9. The other end of R9 is connected to the drain of MOSFET VT3, forming the on / off control circuit of Vcc power supply coupler O1. The V1 output of the high-voltage detection circuit is connected to one end of drive resistor R7. The other end of R7 is connected to the gate of VT3 and one end of bleeder resistor R8. The other end of R8 and the source of VT3 are connected to PGND, forming the on / off control circuit of MOSFET VT2. The drain of MOSFET VT2 is connected to one end of current limiting resistor R10. The other end of R10 is connected to the light source. Pin 1 of the thyristor coupler O1 is connected to the anode and cathode of its internal LED, respectively. Pin 2 of O1 is connected to PGND. Pins 4 and 6 of O1 are the anodes A1 and A2 of its internal bidirectional thyristor, respectively. Pin 4 of O1 is connected to one end of resistor R12 and the control electrode G of bidirectional thyristor VT4. The other end of R12 is connected to the N terminal. Pin 6 of O1 is connected to one end of current-limiting resistor R11. The other end of R11 is connected to one end of capacitor C3 and one end of R13. The other end of C3 is connected to the N terminal. The other end of R13 is connected to the A2 anode output V2 of VT4. The A1 anode of VT4 is connected to the N terminal, which constitutes the on / off control circuit of thyristor VT4.

[0038] The common terminal pin 3 of K1 is connected to the normally closed contact pin 2, and the common terminal pin 6 is connected to the normally closed contact pin 7. The output V2 of the thyristor control circuit is connected to pin 1 of the output terminal of the AC relay K1 coil. Pin 8 of K1 is connected to the mains L terminal, pin 3 is connected to the N terminal, and pin 6 is connected to the L terminal. Pins 4 and 5 of K1 are connected to the output Vout respectively. Vout is connected to both ends of the load to supply power to the load.

[0039] In this embodiment, the operating voltage threshold of the AC relay is 154Vac, and the normal minimum operating input voltage of the product is 176Vac.

[0040] The mains input voltage is below 176Vac. After passing through the bridge full-wave rectifier circuit (1), the output VDAC is less than 249V. After detection by the high voltage detection circuit (3), it is found that it is below the action threshold voltage. The voltage detection chip N1 outputs a low level, which controls the N-channel MOSFET VT3 to disconnect. Then the P-channel MOSFET VT2 disconnects, and the Vcc output by the high voltage linear regulator circuit (2) cannot supply power to the optocoupler O1. The bidirectional thyristor VT4 of the thyristor control circuit (4) disconnects, and the AC relay (5) K1 disconnects and does not work.

[0041] The mains input voltage is greater than 176Vac. After passing through the bridge full-wave rectifier circuit (1), the output VDAC is greater than 249V. After being detected by the high voltage detection circuit (3), it is found to be higher than the action threshold voltage. The voltage detection chip N1 outputs a high level, controls the N-channel MOSFET VT3 to conduct, and then the P-channel MOSFET VT2 conducts. The Vcc output of the high voltage linear regulator circuit (2) supplies power to the optocoupler O1. The bidirectional thyristor VT4 of the thyristor control circuit (4) conducts, and the coil of the AC relay (5) K1 is powered and operates. Its output Vout supplies power to the load.

[0042] The above embodiments are descriptions of specific implementations of the present invention, and not limitations thereof. Those skilled in the art can make various modifications and changes without departing from the spirit and scope of the present invention to obtain corresponding equivalent technical solutions. Therefore, all equivalent technical solutions should be included in the patent protection scope of the present invention.

Claims

1. An AC relay hysteresis control circuit suitable for power products, characterized in that, It includes a bridge full-wave rectifier circuit, a high-voltage detection circuit, a high-voltage linear regulator circuit, a thyristor control circuit, and an AC relay, which are used to detect the mains voltage and drive the AC relay to output Vout to supply power to the load circuit. The L and N terminals of the mains input are connected to the input terminals of the bridge full-wave rectifier circuit, respectively. The positive and negative output terminals of the bridge full-wave rectifier circuit are connected to the input terminals of the high-voltage detection circuit and the high-voltage linear regulator circuit, respectively. The output V1 of the high-voltage detection circuit and the output Vcc of the high-voltage linear regulator circuit are connected to the input terminals of the thyristor control circuit, respectively. One end of the output of the thyristor control circuit is connected to the N terminal, and the other end is connected to the input of the AC relay coil. The other end of the AC relay coil input is connected to the L terminal. The common output terminal of the AC relay is connected to the L terminal and the N terminal. The normally closed contact is connected to the empty pin, and the normally open contact is connected to the output Vout. Vout is connected to both ends of the load. The thyristor control circuit is characterized by comprising an N-channel MOSFET VT3, a P-channel MOSFET VT2, an optically controlled thyristor coupler O1, a bidirectional thyristor VT4, a capacitor C3, and resistors R6 to R13. The Vcc output of the high-voltage linear regulator circuit is connected to one end of resistor R6 and the source of MOSFET VT2. The gate of VT2 is connected to the other end of R6 and one end of voltage divider resistor R9. The other end of R9 is connected to the drain of MOSFET VT3, forming the on / off control circuit of Vcc-powered optically controlled thyristor coupler O1. The V1 output of the high-voltage detection circuit is connected to one end of drive resistor R7. The other end of R7 is connected to the gate of VT3 and one end of bleed resistor R8. The other end of R8 and the source of VT3 are connected to PGND, forming the on / off control circuit of MOSFET VT2. The drain of MOSFET VT2 is connected to one end of current-limiting resistor R10, and the other end of R10... Connect pin 1 of the optically controlled thyristor coupler O1. Pins 1 and 2 of O1 are the anode and cathode of its internal LED, respectively. Pin 2 of O1 is connected to PGND. Output pins 4 and 6 of O1 are the anodes of its internal bidirectional thyristor, respectively. Pin 4 of O1 is connected to one end of resistor R12 and the control electrode G of bidirectional thyristor VT4. The other end of R12 is connected to the N terminal. Pin 6 of O1 is connected to one end of current-limiting resistor R11. The other end of R11 is connected to one end of capacitor C3 and one end of R13. The other end of C3 is connected to the N terminal. The other end of R13 is connected to the A2 anode output V2 of VT4. The A1 anode of VT4 is connected to the N terminal, forming the on / off control circuit of bidirectional thyristor VT4.

2. The AC relay hysteresis control circuit for power products according to claim 1, characterized in that, The high-voltage linear regulator circuit includes a Zener diode VD6, an N-channel MOSFET VT1, a current-limiting resistor R3, a current-limiting resistor R4, and a current-limiting resistor R5. The output VDAC of the bridge full-wave rectifier circuit is connected to one end of the current-limiting resistor R3. The other end of R3 is connected to the cathode of the Zener diode VD6 and the gate of the MOSFET VT1. The anode of the Zener diode VD6 is connected to PGND. VDAC is connected to one end of the current-limiting resistor R4. The other end of R4 is connected to the drain of VT1. The source of VT1 is connected to one end of the current-limiting resistor R5. The other end of R5 outputs Vcc.

3. The AC relay hysteresis control circuit for power products according to claim 1, characterized in that, The high-voltage detection circuit includes a rectifier filter safety capacitor C1, a capacitor C2, a Zener diode VD5, a voltage detection chip N1, a current-limiting resistor R1, and a resistor R2. The outputs VDAC and PGND of the bridge full-wave rectifier circuit are connected to both ends of C1 respectively. VDAC is connected to one end of the current-limiting resistor R1. The other end of R1 is connected to the cathode of VD5 and one end of R2. The anode of VD5 and the other end of R2 are connected to PGND. The cathode of VD5 is connected to one end of capacitor C2 and input pin 1 of voltage detection chip N1. The other end of capacitor C2 is connected to PGND. Pin 2 of N1 is connected to PGND. Output pin 3 of N1 is connected to V1.

4. The AC relay hysteresis control circuit for power products according to claim 1, characterized in that, The AC relay is a double-pole double-throw AC relay K1; K1 contains switch one and switch two; Knife switch one includes pins 2, 3, and 4; Knife switch two includes pins 5, 6, and 7; The common terminal pin 3 is connected to the normally closed contact pin 2, the common terminal pin 6 is connected to the normally closed contact pin 7, the output V2 of the thyristor control circuit is connected to pin 1 of the AC relay K1 coil, pin 8 of the K1 coil is connected to the mains L terminal, pin 3 is connected to the N terminal, pin 6 is connected to the L terminal, pins 4 and 5 of K1 are connected to the output Vout respectively, and Vout is connected to the two ends of the load to supply power to the load; The AC relay K1 can be replaced with a single-pole single-throw AC relay, that is, only the part of the above-mentioned knife switch two is retained; Based on a single AC relay, multiple AC relays can be connected in parallel according to different output loads.

5. The AC relay hysteresis control circuit for power products according to claim 1, characterized in that, The bridge full-wave rectifier circuit includes diodes VD1 to VD4; The L terminal of the AC power input is connected to the anode of VD1 and the cathode of VD3, the N terminal of the AC power input is connected to the anode of VD2 and the cathode of VD4, the cathodes of VD1 and VD2 are connected to VDAC, and the anodes of VD3 and VD4 are connected to PGND.

Images