Driving circuit for controlling on and off of relay at zero point

Abstract

The utility model discloses a driving circuit for starting and closing a zero-point control relay. The driving circuit comprises an electric appliance working circuit with at least one group of electric appliances, the relay comprises a coil of a switch K0, when the coil is powered on, the switch K0 is switched on to enable the circuit to be switched on, and when the coil is powered off, the switch K0 is bounced off to enable the circuit to be switched off; the first optocoupler detection element is used for detecting the voltage of the working circuit of the electric appliance; and the control element sends a power-on high-level signal and controls the coil to be powered on when receiving the first high-level signal and a power-on instruction input by the outside, and sends a power-off low-level signal and controls the coil to be powered off when receiving the first high-level signal and a power-off instruction input by the outside. According to the circuit, the control element, the first optocoupler detection element and the second optocoupler detection element are utilized, the relay is controlled to be turned on and turned off at zero voltage, and the structure of the second optocoupler detection element has the function of assisting in judging the fault reason of the relay.

Description

Technical Field

[0001] The utility model relates to the technical field of circuits for controlling the opening and closing of a relay, and more specifically, to a driving circuit for controlling the opening and closing of a relay at a zero point. Background Art

[0002] A relay is an automatic switching element with isolation function. It mainly plays the roles of automatic adjustment, safety protection, and circuit conversion in the circuit. It is widely used in major downstream fields such as home appliances, automobiles, medical care, consumer electronics, photovoltaics, and industrial control.

[0003] In the existing working circuit of an electrical appliance with a control element and a relay, when a user needs the electrical appliance to work normally, the user inputs a power-on command to the control element, and then the control element controls the coil in the relay to be energized. After the coil is energized, a magnetic force is generated, and the switch is attracted under the action of the magnetic force, so that the switch is closed, thereby making the working circuit of the electrical appliance conductive and the electrical appliance can work normally; when the user needs the electrical appliance to stop working, the user inputs a power-off command to the control element, and then the control element controls the coil in the relay to be de-energized. After the coil is de-energized, the magnetic force is lost, and the switch rebounds and resets under the action of the reset spring of the relay, and the switch is re-opened, thereby disconnecting the working circuit of the electrical appliance and stopping the electrical appliance.

[0004] However, the working circuit of an electrical appliance generally transmits alternating current to the electrical appliance, and alternating current has a current and voltage periodicity. If the voltage at the moment the switch closes or the voltage when the switch opens is too high when the user inputs a power-on command or a power-off command, the electrical appliance may be easily damaged. Summary of the invention

[0005] In response to the existing technical problems, the purpose of the utility model is to provide a circuit for opening and closing a zero-point control relay, so that the switch K0 of the relay is opened or closed at zero-point voltage, thereby reducing the possibility of damage to electrical appliances and improving their service life. At the same time, it can also assist in determining the cause of relay failure.

[0006] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0007] A driving circuit for opening and closing a zero-point control relay, comprising:

[0008] An electrical appliance working circuit having at least one set of electrical appliances;

[0009] A relay, the relay is connected to the working circuit of the electrical appliance, the relay comprises a switch K0 and a coil, when the coil is energized, the switch K0 is closed, so that the working circuit of the electrical appliance is turned on, and the electrical appliance operates; when the coil is de-energized, the switch K0 is opened, so that the working circuit of the electrical appliance is disconnected, and the electrical appliance stops operating;

[0010] A control element, used for receiving power-on and power-off instructions input from the outside, and controlling the power-on and power-off of the coil;

[0011] It is characterized in that it also includes: a first optical coupler detection element, which is used to detect the voltage of the working circuit of the electrical appliance, and outputs a first high-level signal when a zero-point voltage is detected, and outputs a first low-level signal when a non-zero-point voltage is detected; the control element, when receiving the first high-level signal and an external power-on instruction, sends a high-level power-on signal and controls the coil to be powered on, and when receiving the first high-level signal and an external power-off instruction, sends a low-level power-off signal and controls the coil to be powered off.

[0012] By adopting the above technical solution, the first optical coupler detection element is used to detect the zero voltage of the working circuit of the electrical appliance, and when the voltage is zero, the first high level signal is output, and when the voltage is non-zero, the first low level signal is output. When the control element receives the first high level signal, the control element will determine that the working circuit of the electrical appliance is in a zero voltage state at this time. The user gives the control element a power-on instruction, and the control element actually receives the two judgments of "in a zero voltage state" and "need to be powered on". Only when the control element receives these two judgments will the control element generate a high level power-on signal, and then control the coil to be powered on, thereby causing the switch K0 to be closed, that is, when the switch K0 is closed, the working circuit of the electrical appliance is at a zero voltage. When the control element receives the first high-level signal, the control element will determine that the working circuit of the electrical appliance is in a zero-voltage state at this time. The user gives the control element a power-off command. What the control element actually receives at this time are the two judgments of "in a zero-voltage state" and "need to be powered off". Only when the control element receives these two judgments will the control element generate a high-level power-off signal, thereby controlling the coil to be powered off, thereby causing the switch K0 to pop open. In other words, the switch K0 pops open when the working circuit of the electrical appliance is in a zero-voltage state. When the control element receives other signals, such as the first low-level signal, no matter whether the user gives the control element a power-on command or a power-off command, no signal will be sent to control the power-on and power-off of the coil. In this way, whether the switch K0 is closed or popped open, it can only be when the working circuit of the electrical appliance is in a zero-voltage state, thereby reducing the possibility of damage to the electrical appliance and increasing its service life.

[0013] Furthermore, the working circuit of the electrical appliance includes a live wire, a neutral wire and the electrical appliance. The live wire is connected in series with the switch K0 and then connected to the electrical appliance. The current output end of the electrical appliance is connected to the neutral wire.

[0014] By adopting the above technical solution, the components of the working circuit of the electrical appliance and their connection relationship are described.

[0015] Furthermore, it also includes a time measuring unit for measuring the closing time and the opening time of the switch K0.

[0016] Alternating current has a periodicity of current and voltage, and a zero voltage will appear at regular intervals, which will last for a fixed period of time. The closing and opening of switch K0 requires a certain amount of time, and the existence of the closing and opening time of switch K0 easily causes the working circuit of the electrical appliance to miss the time period of the zero voltage when switch K0 is closed or opened. By adopting the above technical solution, the closing time of switch K0 and the opening time of switch K0 can be detected by the time measurement unit, so that the user can pre-adjust the zero voltage duration of the alternating current input to the working circuit of the electrical appliance according to the measured closing time and opening time, so that the closing and opening moments of switch K0 fall within the time period when the zero voltage appears and lasts.

[0017] Further, the time measurement unit includes a second optical coupler detection element and the first optical coupler detection element, the first optical coupler detection element is connected to the working circuit of the electrical appliance and is far away from the electrical appliance, the second optical coupler detection element is connected to the working circuit of the electrical appliance and is close to the electrical appliance, and the switch K0 is located between the first optical coupler detection element and the second optical coupler detection element;

[0018] When the first optical coupler detection element detects the zero voltage, it sends out a first high-level signal. If the control element also receives a power-on command from the outside at this time, it sends out a power-on high-level signal and controls the switch K0 to close. The time when the control element sends out the power-on high-level signal is recorded as T1. After the control switch K0 is closed, the second optical coupler detection element detects the zero voltage and sends out a second high-level signal. The time when the control element receives the second high-level signal is recorded as T2. T2-T1 is the closing time of the switch K0.

[0019] When the first optocoupler detection element detects the zero-point voltage, it sends out a first high-level signal. If the control element also receives a power-off command from the outside at this time, it sends out a high-level power-off signal and controls the switch K0 to pop open. The time when the control element sends out the high-level power-off signal is recorded as T3. After the switch K0 pops open, the second optocoupler detection element stops sending out the second high-level signal. The disappearance time of the second high-level signal is recorded as T4. T4-T3 is the pop-up time of the switch K0.

[0020] By adopting the above technical solution, the specific structure of the time measurement unit and how to realize the time measurement are described in detail. In addition, the structure of the second optical coupler detection element shown in the above technical solution also has the function of assisting in determining the cause of the relay failure. According to the measured time, the zero voltage duration is adjusted in advance. Under normal circumstances, the user should be able to use it normally, but if the user inputs a power-on command to the control element, the control element receives the first high-level signal, sends a power-on high-level signal to energize the coil of the relay, but there is no current passing through the working circuit of the electrical appliance. If the control element does not receive the second high-level signal from the second optical coupler detection element at this time, it is very likely that the switch K0 contact of the relay is burned out. However, if the user inputs a power-off command to the control element, the control element receives the first high-level signal, sends a power-off high-level signal to de-energize the relay coil, but there is still current passing through the working circuit of the electrical appliance. If the control element receives the second high-level signal from the second optical coupler detection element at this time, it is very likely that the switch K0 of the relay is sticky.

[0021] Furthermore, the first optocoupler detection element includes a first phototransistor and a first bidirectional diode capable of emitting light, one port of the first bidirectional diode is connected to the live wire through a wire, the other port of the first bidirectional diode is connected to the neutral wire through a wire, the emitter of the first phototransistor is connected to GND, the collector of the first phototransistor is connected to the first high-level signal receiving end of the control element through a wire, and the wire portion between the collector of the first phototransistor and the first high-level signal receiving end of the control element is connected to a first pull-up resistor R6.

[0022] By adopting the above technical scheme, the specific structure of the first optocoupler detection element is specifically described. When a non-zero voltage appears between the live wire and the neutral wire of the working circuit of the electrical appliance, the first bidirectional diode will emit light, the emitter of the first phototransistor will be turned on, and the emitter of the first phototransistor will be connected to GND, then the control element receives the first low-level signal; when a zero voltage appears between the live wire and the neutral wire of the working circuit of the electrical appliance, the first bidirectional diode will not emit light, the emitter of the first phototransistor will not be turned on, the emitter of the first phototransistor will not be connected to GND, and the electrical signal will be emitted through the collector of the first phototransistor. After being processed by the first pull-up resistor R6, the electrical signal will be clamped at a high level, thereby forming a first high-level signal.

[0023] Furthermore, the second optocoupler detection element includes a second phototransistor and a second bidirectional diode capable of emitting light, one port of the second bidirectional diode is connected to the wire portion between the switch K0 and the electrical appliance through a wire, the other port of the second bidirectional diode is connected to the neutral line through a wire, the emitter of the second phototransistor is connected to GND, the collector of the second phototransistor is connected to the second high-level signal receiving end of the control element through a wire, and the wire portion between the collector of the second phototransistor and the second high-level receiving end of the control element is connected to a second pull-up resistor R7.

[0024] By adopting the above technical solution, the specific structure of the second optocoupler detection element is specifically described. Through the description, it is found that the structure of the second optocoupler detection element is the same as that of the first optocoupler detection element, and the first optocoupler detection element and the second optocoupler detection element are in a parallel state. Therefore, when the switch K0 is in a closed state, the second optocoupler detection element will emit a second high-level signal, and the principle of generating the second high-level signal is the same as the principle of the first optocoupler detection element generating the first high-level electrical signal.

[0025] Furthermore, the port of the control element that sends out the high-level signal for power on and the low-level signal for power off is connected to a common transistor through a wire, the base of the common transistor is connected to the port of the control element that generates the high-level signal for power on and the low-level signal for power off, the emitter of the common transistor is connected to GND, and the collector of the common transistor is connected to the relay through a wire;

[0026] When the control element generates a high-level power-on signal, the common triode is turned on, current flows into the relay, and the coil is energized;

[0027] When the control element generates a power-off high-level signal, the ordinary triode is blocked, no current flows through the relay, and the coil is powered off.

[0028] By adopting the above technical solution, it is specifically described how the control element controls the coil of the relay to be energized.

[0029] Furthermore, the control element is an MCU.

[0030] By adopting the above technical solution, the control element is further limited to MCU, which has the advantages of intelligence, high performance, energy saving, etc.

[0031] Compared with the prior art, the beneficial effects of the utility model are: 1. By utilizing the first optocoupler detection element and the control element, the closing of the switch K0 to energize the working circuit of the appliance, and the opening of the switch KO to de-energize the working circuit of the appliance, can only be performed when the working circuit of the appliance is at zero voltage, thereby reducing the possibility of damage to the appliance and improving its service life; 2. By utilizing the time measurement unit composed of the first optocoupler detection element and the second optocoupler detection element, the user can pre-adjust the zero voltage duration of the alternating current input to the working circuit of the appliance according to the measured time, so that the closing moment and the opening moment of the switch K0 of the relay both fall within the time period when the zero voltage appears and lasts; 3. The structure of the second optocoupler detection element also has the function of assisting in determining the cause of relay failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is the overall circuit diagram of the utility model;

[0033] Figure 2 A partial schematic diagram to highlight the first optical coupler detection element;

[0034] Figure 3 A partial schematic diagram to highlight the second optical coupler detection element;

[0035] Figure 4 A partial schematic diagram to highlight the control components.

[0036] Figure numerals: 1. relay; 11. coil; 2. electrical appliance; 3. MCU; 4. first bidirectional diode; 5. first phototransistor; 6. live wire; 7. neutral wire; 8. second bidirectional diode; 9. second phototransistor; 10. ordinary transistor. DETAILED DESCRIPTION

[0037] The utility model is described in detail below in conjunction with the accompanying drawings and embodiments.

[0038] The terms "first", "second" or "third" etc. used in the present invention are to distinguish different objects rather than to describe a specific order.

[0039] The directional terms used in the present invention, such as "upper", "lower", "left", "right", etc., are based on the directions and positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the specific protection scope of the present invention.

[0040] See also Figure 1 , Figure 2 As shown, a driving circuit for opening and closing a zero-point control relay includes an electrical appliance working circuit with at least one group of electrical appliances 2. The electrical appliance working circuit specifically includes a live wire 6, a neutral wire 7 and an electrical appliance 2. The live wire 6 is connected in series with a switch K0 and then connected to the electrical appliance 2. The current output end of the electrical appliance 2 is connected to the neutral wire 7. The driving circuit also includes a relay 1, a control element and a first optical coupling detection element. The relay 1 is connected to the electrical appliance working circuit. The relay 1 includes a switch K0 and a coil 11. When the coil 11 is energized, the switch K0 is closed, so that the electrical appliance working circuit is turned on and the electrical appliance 2 operates. When the coil 11 is de-energized, the switch K0 pops open, so that the electrical appliance working circuit is disconnected and the electrical appliance 2 stops operating. The control element is used to receive power-on and power-off instructions input from the outside, and control the power-on and power-off of the coil 11. The first optical coupling detection element is used to detect the voltage of the electrical appliance working circuit. When the zero-point voltage is detected, a first high-level signal is output, and when a non-zero-point voltage is detected, a first low-level signal is output.

[0041] Specifically, the first optocoupler detection element includes a first phototransistor 5 and a first bidirectional diode 4 capable of emitting light, one port of the first bidirectional diode 4 is connected to a live wire 6 through a wire, the other port of the first bidirectional diode 4 is connected to a neutral wire 7 through a wire, the emitter of the first phototransistor 5 is connected to GND, the collector of the first phototransistor 5 is connected to a first high-level signal receiving end of the control element through a wire, and the wire portion between the collector of the first phototransistor 5 and the first high-level signal receiving end of the control element is connected to a first pull-up resistor R6.

[0042] When a non-zero voltage appears between the live wire 6 and the neutral wire 7 of the working circuit of the electrical appliance, the first bidirectional diode 4 will emit light, the emitter of the first phototransistor 5 will be turned on, and the emitter of the first phototransistor 5 will be connected to GND, then the control element receives the first low-level signal; when a zero-point voltage appears between the live wire 6 and the neutral wire 7 of the working circuit of the electrical appliance, the first bidirectional diode 4 will not emit light, the emitter of the first phototransistor 5 will not be turned on, the emitter of the first phototransistor 5 will not be connected to GND, and the electrical signal will be emitted through the collector of the first phototransistor 5, and after being processed by the first pull-up resistor R6, the electrical signal will be clamped at a high level, thereby forming a first high-level signal.

[0043] When the control element receives the first high-level signal emitted by the first optocoupler detection element and the power-on command input from the outside, it sends a high-level power-on signal, the ordinary transistor 10 is turned on, the current enters the relay 1, and the coil 11 is energized; when the control element receives the first high-level signal emitted by the first optocoupler detection element and the power-off command input from the outside, it sends a low-level power-off signal, the ordinary transistor 10 is blocked, no current flows through the relay 1, and the coil 11 is powered off.

[0044] See also Figures 1 to 3 As shown, alternating current has a periodicity of current and voltage, and a zero-point voltage will appear at intervals, which will last for a fixed period of time. The closing and opening of switch K0 requires a certain amount of time. The existence of the closing time and the opening time of switch K0 easily causes the switch K0 to miss the existence time period of the zero-point voltage at the moment of closing or opening. In order to measure the closing and opening time of switch K0, it is convenient to adjust the zero-point voltage duration of the alternating current input to the working circuit of the electrical appliance in advance. A time measuring unit for measuring the closing time and the opening time of switch K0 is also provided. The time measuring unit includes a second optical coupler detection element and a first optical coupler detection element, the second optical coupler detection element is connected in parallel with the first optical coupler detection element, the first optical coupler detection element is connected to the working circuit of the electrical appliance and is far away from the electrical appliance 2, the second optical coupler detection element is connected to the working circuit of the electrical appliance and is close to the electrical appliance 2, and the switch K0 is located between the first optical coupler detection element and the second optical coupler detection element.

[0045] The second optocoupler detection element includes a second phototransistor 9 and a second bidirectional diode 8 that can emit light. One port of the second bidirectional diode 8 is connected to the wire portion between the switch K0 and the electrical appliance 2 through a wire, and the other port of the second bidirectional diode 8 is connected to the neutral line 6 through a wire. The emitter of the second phototransistor 9 is connected to GND, and the collector of the second phototransistor 9 is connected to the second high-level signal receiving end of the control element through a wire. The wire portion between the collector of the second phototransistor 9 and the second high-level receiving end of the control element is connected to a second pull-up resistor R7.

[0046] From the description of the second optocoupler detection element, it can be seen that the structure of the second optocoupler detection element is the same as that of the first optocoupler detection element, and the first optocoupler detection element and the second optocoupler detection element are in a parallel state. Therefore, when the switch K0 is in a closed state, the second optocoupler detection element will emit a second high level signal, and the principle of generating the second high level signal is the same as the principle of the first optocoupler detection element generating the first high level electrical signal.

[0047] The first optocoupler detection element is connected to the working circuit of the electrical appliance and is far away from the electrical appliance 2, the second optocoupler detection element is connected to the working circuit of the electrical appliance and is close to the electrical appliance 2, and the switch K0 is located between the first optocoupler detection element and the second optocoupler detection element; when the first optocoupler detection element detects the zero-point voltage, it sends out a first high-level signal, and if the control element also receives a power-on command input from the outside at this time, it sends out a power-on high-level signal and controls the switch K0 to close, and the time when the control element sends out the power-on high-level signal is recorded as T1; after the control switch K0 is closed, the second optocoupler detection element detects the zero-point voltage and sends out a first high-level signal. The first optocoupler detection element detects the zero voltage and sends out a first high-level signal. If the control element also receives a power-off command from the outside at this time, it sends out a high-level power-off signal and controls the switch K0 to pop open. The time when the control element sends out the high-level power-off signal is recorded as T3. After the switch K0 pops open, the second optocoupler detection element stops sending out the second high-level signal. The disappearance time of the second high-level signal is recorded as T4. T4-T3 is the pop-up time of the switch K0.

[0048] In addition, a first filter capacitor C1 can be set at the wire portion between the collector of the first phototransistor 4 and the first high-level receiving end of the control element to process the electrical signal from the first optocoupler detection element and eliminate noise; a second filter capacitor C2 can be set at the wire portion between the collector of the second phototransistor 9 and the second high-level receiving end of the control element to process the electrical signal from the second optocoupler detection element and eliminate noise.

[0049] See also Figure 1 , Figure 4 As shown, it is specifically described how the control element controls the power on and off of the coil through a high-level power-on signal and a low-level power-off signal.

[0050] The control element is specifically MCU 3, and the port of the control element that sends out the high-level signal for power-on and the low-level signal for power-off is connected to the ordinary transistor 10 through a wire. The base of the ordinary transistor 10 is connected to the port of the control element that generates the high-level signal for power-on and the low-level signal for power-off, the emitter of the ordinary transistor 10 is connected to GND, and the collector of the ordinary transistor 10 is connected to the relay 1 through a wire.

[0051] When the control element generates a high-level signal for power on, the ordinary transistor 10 is turned on, current enters the relay 1, and the coil 11 is energized; when the control element generates a low-level signal for power off, the ordinary transistor 10 is blocked, no current flows through the relay 1, and the coil 11 is de-energized.

[0052] The above are only preferred implementations of the utility model. The protection scope of the utility model is not limited to the above embodiments. All technical solutions under the idea of ​​the utility model belong to the protection scope of the utility model. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the utility model should also be regarded as the protection scope of the utility model.

Claims

1. A driving circuit for opening and closing a zero-point control relay, comprising: An electrical appliance working circuit having at least one set of electrical appliances (2); A relay (1), the relay (1) being connected to the working circuit of the electrical appliance, the relay (1) comprising a switch K0 and a coil (11), when the coil (11) is energized, the switch K0 is closed, so that the working circuit of the electrical appliance is turned on, and the electrical appliance (2) operates; when the coil (11) is de-energized, the switch K0 is opened, so that the working circuit of the electrical appliance is turned off, and the electrical appliance (2) stops operating; A control element, used for receiving power-on and power-off instructions input from the outside, and controlling the power-on and power-off of the coil (11); It is characterized by further comprising: The first optical coupling detection element is used to detect the voltage of the working circuit of the electrical appliance, and outputs a first high-level signal when a zero-point voltage is detected, and outputs a first low-level signal when a non-zero-point voltage is detected; the control element, when receiving the first high-level signal and a power-on instruction input from the outside, sends a high-level power-on signal and controls the coil (11) to be powered on, and when receiving the first high-level signal and a power-off instruction input from the outside, sends a low-level power-off signal and controls the coil (11) to be powered off.

2. A driving circuit for opening and closing a zero-point control relay according to claim 1, characterized in that: The electrical appliance working circuit comprises a live wire (6), a neutral wire (7) and the electrical appliance (2); the live wire (6) is connected in series with the switch K0 and then connected to the electrical appliance (2); and the current output end of the electrical appliance (2) is connected to the neutral wire (7).

3. A driving circuit for opening and closing a zero-point control relay according to claim 2, characterized in that: It also includes a time measuring unit for measuring the closing time and the opening time of the switch K0.

4. A driving circuit for opening and closing a zero-point control relay according to claim 3, characterized in that: The time measurement unit comprises a second optical coupler detection element and the first optical coupler detection element, the second optical coupler detection element is connected in parallel with the first optical coupler detection element, the first optical coupler detection element is connected to the working circuit of the electrical appliance and is far away from the electrical appliance (2), the second optical coupler detection element is connected to the working circuit of the electrical appliance and is close to the electrical appliance (2), and the switch K0 is located between the first optical coupler detection element and the second optical coupler detection element; When the first optical coupler detection element detects the zero voltage, it sends out a first high-level signal. If the control element receives the power-on instruction input from the outside and the first high-level signal, it sends out a power-on high-level signal and controls the switch K0 to close. The time when the control element sends out the power-on high-level signal is recorded as T1. After the switch K0 is closed, the second optical coupler detection element detects the zero voltage and sends out a second high-level signal. The time when the control element receives the second high-level signal is recorded as T2. T2-T1 is the closing time of the switch K0. When the first optocoupler detection element detects the zero-point voltage, it sends out a first high-level signal. If the control element receives a power-off command and the first high-level signal input from the outside, it sends out a high-level power-off signal and controls the switch K0 to pop open. The time when the control element sends out the high-level power-off signal is recorded as T3. After the switch K0 pops open, the second optocoupler detection element stops sending out the second high-level signal. The disappearance time of the second high-level signal is recorded as T4. T4-T3 is the pop-up time of the switch K0.

5. A driving circuit for opening and closing a zero-point control relay according to claim 2, characterized in that: The first photocoupler detection element comprises a first photosensitive transistor (5) and a first bidirectional diode (4) capable of emitting light, one port of the first bidirectional diode (4) being connected to the live wire (6) via a wire, the other port of the first bidirectional diode (4) being connected to the neutral wire (7) via a wire, the emitter of the first photosensitive transistor (5) being connected to GND, the collector of the first photosensitive transistor (5) being connected to a first high-level signal receiving end of the control element via a wire, and the wire portion between the collector of the first photosensitive transistor (5) and the first high-level signal receiving end of the control element being connected to a first pull-up resistor R6.

6. A driving circuit for opening and closing a zero-point control relay according to claim 4, characterized in that: The second photocoupler detection element comprises a second photosensitive transistor (9) and a second bidirectional diode (8) capable of emitting light, one port of the second bidirectional diode (8) being connected to a wire portion between the switch K0 and the electrical appliance through a wire, the other port of the second bidirectional diode (8) being connected to the neutral line (7) through a wire, the emitter of the second photosensitive transistor (9) being connected to GND, the collector of the second photosensitive transistor (9) being connected to a second high-level signal receiving end of the control element through a wire, and the wire portion between the collector of the second photosensitive transistor (9) and the second high-level receiving end of the control element being connected to a second pull-up resistor R7.

7. A driving circuit for opening and closing a zero-point control relay according to claim 1, characterized in that: The port of the control element that sends out a high-level power-on signal and a low-level power-off signal is connected to a common transistor (10) via a wire, the base of the common transistor (10) is connected to the port of the control element, the emitter of the common transistor (10) is connected to GND, and the collector of the common transistor (10) is connected to the relay (1) via a wire; When the control element generates a high-level power-on signal, the common triode (10) is turned on, current flows into the relay (1), and the coil (11) is energized; When the control element generates a power-off low-level signal, the common triode (10) is blocked, no current flows through the relay (1), and the coil (11) is powered off.

8. A driving circuit for opening and closing a zero-point control relay according to claim 1, characterized in that: The control element is an MCU (3).

Images