CN114415580B - A control method for arcless breaking of AC circuit - Google Patents

Abstract

The invention discloses a control method for breaking an AC circuit without arc, belonging to the technical field of electric power control. Voltage detection step: detect the input voltage value in the power supply step, and compare the input control voltage value with the set value; closing step: the control circuit delays outputting the positive pulse to the coil, and the electromagnetic actuator is turned on at the next zero-crossing point The main circuit; in the disconnection step, the electromagnetic actuator disconnects the main circuit at the next zero-crossing point; the present invention solves the problem of arc generated in the switching process of the AC load on and off, and is highly efficient and energy-saving, and the electromagnetic actuator is controlled by software delay to close And the time to disconnect the circuit, the time-delayed on/off control of the contacts is performed to find the real current zero-crossing point, which effectively solves the electrical corrosion problem of the contacts when the load is switched.

Description

A control method for arcless breaking of AC circuit

technical field

The invention belongs to the technical field of electric power control, and in particular relates to a control method for breaking an AC circuit without arc.

Background technique

AC contactors are generally used in industrial control scenarios of power frequency AC single-phase AC220V or three-phase AC380V. Due to the working characteristics of power frequency AC, the current and voltage change interactively at a relatively fixed frequency, and the voltage is relatively high. In the electromagnetic coil control main circuit At the moment of switching on and off, arcing will occur in the contacts. The arcing will not only cause a serious decrease in the working life of the contacts, but also cause electromagnetic radiation interference during the arcing process, which will affect the normal operation of surrounding electronic circuits and wireless communications. In the application of inductive load control, due to the influence of arcing, the electrical life is generally only 10% or even less than 1% of the designed mechanical life, resulting in frequent maintenance of equipment lines and frequent production shutdown accidents. After years of development, engineers have limited the development of basic new materials for contacts and the arc-extinguishing structure design of products for AC current switching and arc-breaking suppression technology. So far, the solution to the problem has remained in exploration and research. At this stage, especially for the AC contactor arc suppression technology, the entire industry is helpless.

AC contactors are currently mainly used in the field of power control. There are currently three common methods for power control. The first traditional method uses electromagnetic holding contactors, which are widely used at present, easy to use, and simple control circuits. The disadvantage is that the electrical life is short. The power consumption of the coil is large, and the heating temperature rises. At present, the development direction of the industry has an urgent need to be eliminated. The second is to use a thyristor as the AC on-off control. This method has no arc during operation and has a long life, which can be basically ignored. It does not count, but there is a certain voltage drop when the thyristor is turned on. When the current flowing is large, the power consumption is large, and the heat generation is serious. The thyristor is prone to breakdown due to the low withstand voltage value, and the logic control circuit is complicated and the reliability is poor; The third is to use a magnetic latching contactor. This method only has the advantage of controlling the power consumption of the coil. The disadvantage is that the electrical life is short and the logic control circuit is complex. Therefore, a new control method needs to be developed to solve the existing problems.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a control method for breaking the AC circuit without arc, so as to solve the problem of serious arc in the switching process of AC inductive load on and off.

In order to achieve the above purpose, the present invention provides the following technical solutions: a control method for arc-free AC circuit breaking, comprising the following steps:

Power supply steps:

Convert the input control voltage into the coil working voltage of the electromagnetic actuator, and supply power to the energy storage circuit at the same time;

Input voltage detection steps:

Detecting the input voltage value in the power supply step, and comparing the input voltage value with the set value;

Closing steps:

When the control power supply is turned on or it is detected that the input voltage is higher than the closing set value of the coil voltage of the electromagnetic actuator, and the zero-crossing signal of the main circuit is detected, the control circuit delays and outputs the positive pulse to the coil, and the electromagnetic actuator will output the positive pulse to the coil after the next pass. Turn on the main circuit at zero point;

Disconnect steps:

When the control power supply is disconnected or it is detected that the input voltage is lower than the closing set value of the coil voltage of the electromagnetic actuator, and the zero-crossing signal of the main circuit is detected, the control circuit delays the output of the reverse pulse to the coil, and the electromagnetic actuator is in the next pass. Disconnect the main circuit at zero point.

Preferably, the control circuit includes a series step-down circuit for reducing the input voltage of the power supply to a set voltage, a MCU power supply circuit connected with the series step-down circuit, and a rectifier connected with the power source for converting the input alternating current into direct current A filter circuit, an energy storage circuit connected to the MCU power supply circuit for supplying electrical energy, a power supply signal conversion circuit used to detect the input control voltage, a coil drive circuit connected to the MCU power supply circuit for driving the coil on and off, and used for receiving The power supply signal conversion circuit voltage detection signal and sends the zero-crossing pulse signal to the micro-control chip U2 of the zero-crossing detection conversion circuit, and the zero-crossing detection conversion circuit that receives the zero-crossing pulse signal of the micro-control chip U2 and switches the coil input electrode.

Preferably, the energy storage circuit includes a diode D5 whose one end is connected to the coil driving circuit, an energy storage capacitor C2 connected to the other end of the diode D5, and a resistor R2 connected in parallel with the diode D5;

The rectifying and filtering circuit includes a diode D1 connected to the positive electrode of the power supply, and a capacitor C3 connected to the diode D1;

The series step-down circuit includes a diode D2, a diode D3, and a diode D4 connected in series in sequence, and the diode D2 is connected to the rectifying filter circuit;

The MCU power supply circuit includes a resistor R1 connected to the series voltage reducing circuit, a Zener diode DW1 connected to one end of the resistor R1, and a capacitor C1 connected in parallel with the Zener diode DW1;

Wherein, one end of the capacitor C1 and the Zener diode DW1 is connected with the VREF pin of the driving chip U1 in the coil driving circuit; the other end of the resistor R1 is connected with the VBB pin of the driving chip U1 in the coil driving circuit;

The resistor R7 is connected to the LSS pin of the driving chip U1, and the OUT1 pin and the OUT2 pin of the driving chip U1 are connected to the coil.

Preferably, in the power supply step: the power supply is powered on, the positive electrode is rectified and filtered by the diode D1, the capacitor C3 is rectified and filtered, and the diode D2, the diode D3, and the diode D4 are connected in series to reduce the voltage, and the number of diodes connected in series according to the level of the input voltage is used for driving The VBB pin of the chip U1 provides the power supply voltage, charges the capacitor C2 energy storage capacitor through the resistor R2, and is connected to the analog voltage input Vref pin of the driver chip U1 through the resistor R1 and the Zener diode DW1 in series with a voltage with a voltage regulation value of 5V; The positive pole of the power supply is divided by the resistor R4, the resistor R3 and the resistor R10 and then connected to the AD signal input terminal of the AN10 pin of the microcontroller chip U2; the output I/O ports P3.4 and P3.5 of the microcontroller chip U2 are respectively connected to the driver IN1 pin and IN2 pin of chip U1.

Preferably, the coil drive circuit includes a drive chip U1, a resistor R7 connected to the LSS pin of the drive chip U1 at one end, a diode D7 and a diode D11 connected to the other end of the resistor R7, and a diode D6 connected to the diode D7 , Diode D8 connected to diode D11.

Preferably, the power supply signal conversion circuit includes a resistor R4 connected to the series step-down circuit at one end, a resistor R3 connected to the other end of the resistor R4, a resistor R10 connected to the resistor R3, and a capacitor C4 connected in parallel to both ends of the resistor R10 and Zener diode DW2;

The nodes of the resistor R10, the capacitor C4 and the Zener diode DW2 are connected to the negative electrode of the power supply, and the Zener diode DW2 is also connected to the AN10 pin of the micro-control chip U2.

Preferably, the zero-crossing detection conversion circuit includes a photocoupler U3 connected to the micro-control chip U2, a transistor V1 and a capacitor C5 connected to U3, a resistor R11 connected to the transistor V1, and one end connected to the resistor R11 It is connected to D14 on the node of capacitor C5, the Zener diode DW3 connected to the other end of D14, the resistor R5 connected in parallel with the Zener diode DW3, the diode D9 connected to the resistor R5, and the diode D13 connected in parallel with the diode D9. Resistor R8 on diode D9, resistor R9 with one end connected to diode D13, diode D10 connected to the node of diode D9 and resistor R8 at one end, diode D12 connected in series with diode D10 and connected to the node of diode D13 and resistor R9.

Preferably, in the closing step, when the control power is turned on or the AD input terminal AN10 of the micro-control chip U2 detects that the input control voltage is greater than the set value of the coil voltage of the electromagnetic actuator, and P1.7 of the micro-control chip U2 detects the AC voltage At the falling edge of the zero-crossing point of the signal, after the program control delay of the micro-control chip U2, IN2 is set to high level, and IN1 is low level; When the power is turned on, the state of the magnetic force of the electromagnet is reversed, and the electromagnetic actuator is kept closed under the action of the permanent magnet, and then the IN2 low level is controlled by the program of the micro-control chip U2, and the IN2 pin level of the driver chip U1 is pulled low. , According to the truth table of the driver chip U1, the OUT1 pin and OUT2 pin of the driver chip U1 output high resistance, the electromagnetic actuator coil loses power, and the coil current is zero.

Preferably, in the disconnection step: when the control power supply is powered off, or the AD AN10 of the micro-control chip U2 detects that the input control voltage is lower than the set value of the coil voltage of the electromagnetic actuator, the energy storage capacitor C2 discharges through the diode D5 and continues to be the chip Supply power, diode D4 is turned off in the reverse direction and prohibits supplying power to the power signal conversion circuit, the P1.7 pin of the microcontroller chip U2 detects the falling edge of the zero-crossing point of the AC signal, controls IN1 to set a high level, and drives the OUT1 pin of the chip U1 , The output of OUT2 pin flips instantly, the OUT2 pin outputs the negative pole, the OUT1 pin outputs the positive pole, the coil of the electromagnetic actuator is energized under the action of the energy storage capacitor C2, the state of the magnetic force of the electromagnet is reversed, and the electromagnetic actuator is in the permanent state. Under the action of the magnet, it remains disconnected, and then the program of the micro-control chip U2 controls the IN1 low level, the IN1 pin level of the driver chip U1 is pulled down, the OUT1 and OUT2 pins of the driver chip U1 output high resistance, and the electromagnetic The actuator coil is de-energized, and the coil current is zero.

Preferably, the IN1 and IN2 pins of the driver chip U1 are respectively connected with the P3.4 pins and the P3.5 pins of the micro-control chip U2; the micro-control chip U2 also includes an RXD pin for communication , TXD pin, INT1 pin for programming interface, INT1 pin, TDI pin, TCK pin.

The technical effects and advantages of the present invention are as follows: the control method for breaking an AC circuit without arc is convenient to use, solves the problem of arcing in the switching process of the AC load on and off, and is highly efficient and energy-saving, and delays the closing and opening of the electromagnetic actuator. The time of the circuit is controlled by time-delayed on and off of the contacts to find the real current zero-crossing point, which effectively solves the problem of electrical corrosion of the contacts when the load is switched.

Description of drawings

Fig. 1 is the schematic flow chart of the present invention

Fig. 2 is the working principle diagram of the electromagnetic actuator of the present invention;

FIG. 3 is a control circuit diagram of the present invention.

In the figure: 1. Series step-down circuit; 2. MCU power supply circuit; 3. Energy storage circuit; 4. Power signal conversion circuit; 5. Coil drive circuit; 6. Zero-crossing detection and conversion circuit; , the first permanent magnet; 9, the second permanent magnet; 10, the moving iron core; 11, the coil; 12, the magnetic conductor; 13, the control circuit board; 14, the control power supply; 15, the main circuit static contact; Loop moving contact; 17. Linkage components.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The present invention provides a control method for breaking an AC circuit without an arc as shown in FIG. 1 , comprising the following steps:

Power supply steps:

Convert the input control voltage into the coil working voltage of the electromagnetic actuator, and supply power to the energy storage circuit 3 at the same time;

Input voltage detection steps:

Detecting the input voltage value in the power supply step, and comparing the input voltage value with the set value;

Closing steps:

When the control power is turned on or it is detected that the input control voltage is higher than the closing set value of the coil voltage of the electromagnetic actuator, and the zero-crossing signal of the main circuit is detected, the control circuit delays the output of the positive pulse to the coil, and the electromagnetic actuator is in the next When the zero-crossing point, the main circuit is turned on. If the detected input control voltage is higher than the set value, the micro-control chip U2 detects the falling edge, the coil of the electromagnetic actuator is energized, and the electromagnetic actuator remains closed under the action of the permanent magnet; this implementation In the example, when the micro-processing chip U2 detects the zero-crossing point on the AC signal side, the delay program of the micro-processing chip U2 outputs a closing signal to the full-bridge control chip U1, and the electromagnetic actuator accurately turns on the main circuit at the next zero-crossing point. The main circuit is closed without arcing; the coil of the electromagnetic actuator is energized, and the electromagnetic actuator remains closed under the action of the permanent magnet;

Disconnect steps:

When the control power supply is disconnected or it is detected that the input control voltage is lower than the closing set value of the coil voltage of the electromagnetic actuator, and the zero-crossing signal of the main circuit is detected, the control circuit delays the output of the reverse pulse to the coil, and the electromagnetic actuator is in the next The main circuit is disconnected when the zero-crossing point is reached. If the detected input control voltage is lower than the set value, the micro-control chip U2 detects the falling edge, and the energy storage circuit 3 supplies power to the electromagnetic actuator coil, and converts the positive value of the electromagnetic actuator coil during the closing step. Negative polarity, the state of the magnetic force of the electromagnet is reversed, the electromagnetic actuator remains disconnected under the action of the permanent magnet, the coil of the electromagnetic actuator is de-energized, and the coil current is zero; in this embodiment, when the microprocessor chip U2 detects When the zero-crossing point of the AC main circuit is reached, the delay program of the microprocessor chip U2 outputs a shutdown signal to the full-bridge control chip U1, and the electromagnetic actuator accurately breaks the main circuit at the next zero-crossing point. At this time, the energy storage capacitor continues to supply power. The electric control circuit is powered, the full-bridge control chip U1 outputs the reverse voltage, and the magnetic direction of the coil electromagnetic is reversed, so that the main circuit has no arc breaking in the state of zero-crossing, and the program controls the full-bridge control chip U1 The output voltage is zero, and the electromagnetic The coil of the actuator is de-energized, and the electromagnetic actuator remains disconnected under the action of the permanent magnet;

As shown in FIG. 3 , the control circuit includes: a series step-down circuit 1 for reducing the input control voltage of the power supply to a set voltage;

The series step-down circuit 1 includes a diode D2, a diode D3, and a diode D4 connected in series in sequence, and the diode D2 is connected to the rectifying filter circuit 7.

The MCU power supply circuit 2 connected to the series step-down circuit 1, the MCU power supply circuit 2 includes a resistor R1 connected to the series step-down circuit 1, a Zener diode DW1 connected to one end of the resistor R1, and the voltage stabilizer. The capacitor C1 connected in parallel with the voltage diode DW1;

One end of the capacitor C1 and the Zener diode DW1 is connected to the VREF pin of the drive chip U1 in the coil drive circuit 5; the other end of the resistor R1 is connected to the VBB pin of the drive chip U1 in the coil drive circuit 5. connect.

A coil drive circuit 5 connected to the MCU power supply circuit 2 for driving the coil on and off. The coil drive circuit 5 includes a drive chip U1, a resistor R7 whose one end is connected to the LSS pin of the drive chip U1, and a resistor R7 connected to the resistor R7. The diode D7 and the diode D11 at the other end, the diode D6 connected to the diode D7, and the diode D8 connected to the diode D11; the resistor R7 is connected to the LSS pin of the driver chip U1, and the OUT1 lead of the driver chip U1 pin and OUT2 pin and coil are connected.

A power signal conversion circuit 4 connected to the coil drive circuit 5 for detecting the input control voltage, the power signal conversion circuit 4 includes a resistor R4 connected to the series step-down circuit 1 at one end, and a resistor R3 connected to the other end of the resistor R4 , Resistor R10 connected with resistor R3, capacitor C4 and Zener diode DW2 connected in parallel at both ends of resistor R10;

The nodes of the resistor R10, the capacitor C4 and the Zener diode DW2 are connected to the negative electrode of the power supply, and the Zener diode DW2 is also connected to the AN10 pin of the micro-control chip U2.

The energy storage circuit 3 that receives the voltage detection signal of the power signal conversion circuit 4 and provides electrical energy to the coil driving circuit 5. The energy storage circuit 3 includes a diode D5 whose one end is connected with the coil driving circuit 5, and a diode D5 connected to the other end of the diode D5. One end of the energy storage capacitor C2, the resistor R2 in parallel with the diode D5;

The rectifying and filtering circuit 7 includes a diode D1 connected to the positive pole of the power supply, and a capacitor C3 connected to the diode D1.

The micro-control chip U2, which is used to receive the voltage detection signal of the power signal conversion circuit 4 and send the zero-crossing pulse signal to the zero-crossing detection conversion circuit 6,

A zero-crossing detection conversion circuit 6 that receives the zero-crossing pulse signal of the micro-control chip U2 and switches the electrodes of the coil input terminals. The zero-crossing detection conversion circuit 6 includes a photocoupler U3 connected to the micro-control chip U2, and a photocoupler U3 connected to the micro-control chip U2. The connected transistor V1 and capacitor C5, the resistor R11 connected to the transistor V1, the D14 connected to the node of the resistor R11 and the capacitor C5 at one end, the Zener diode DW3 connected to the other end of D14, and the Zener diode DW3 connected in parallel The resistor R5, the diode D9 connected to the resistor R5, the diode D13 connected in parallel with the diode D9, the resistor R8 connected to the diode D9 at one end, the resistor R9 connected to the diode D13 at one end, and the node connected to the diode D9 and the resistor R8 at the other end. Diode D10, diode D12 connected in series with diode D10 and connected to diode D13 and resistor R9 node.

A rectifier and filter circuit 7 connected to the power supply for converting the input alternating current into direct current;

The IN1 and IN2 pins of the driver chip U1 are respectively connected with the P3.4 pins and the P3.5 pins of the micro-control chip U2; the micro-control chip U2 also includes an RXD pin and a TXD pin for communication. pin, INT1 pin, INT1 pin, TDI pin, TCK pin for programming interface;

The control method of the non-arc breaking AC circuit, the power supply is powered on, the positive electrode is rectified and filtered by diode D1, capacitor C3, and then the diode D2, diode D3, diode D4 multi-diode array is connected in series to reduce the voltage, and the diodes configured according to the input voltage are connected in series. Quantity, to provide the power supply voltage for the VBB pin of the driver chip U1. In this embodiment, the electromagnetic actuator adopts an AC contactor or a circuit breaker; in this embodiment, the electromagnetic actuator adopts an electromagnetic actuator as an example,

The operation of the electromagnetic actuator is shown in Figure 2; the first permanent magnet 8 is disconnected, and the second permanent magnet 9 is closed;

When the control power supply 14 is turned on, the control circuit board 13 outputs a forward voltage pulse to the coil 11 , the main circuit moving contact 16 moves downward with the linkage assembly 17 and the moving iron core 10 , and the main circuit is static under the action of the closed permanent magnet 9 . The contact 15 and the main circuit moving contact 16 are kept closed; when the control power supply 14 is disconnected, the control circuit board 13 outputs a reverse pulse voltage to the coil 11, and the main circuit moving contact 16, along with the linkage assembly 17 and the moving iron core 10 Upward movement, under the action of disconnecting the permanent magnet 8, the main circuit static contact 15 and the main circuit moving contact 16 remain disconnected;

The working voltage of the coil of the electromagnetic actuator in this embodiment charges the capacitor C2 energy storage capacitor through the resistor R2 at the same time, and is connected to the analog voltage input Vref of the driving chip U1 via the resistor R1 and the voltage stabilizing diode DW1 in series with a voltage of 5V. Pin; the positive pole of the power supply is connected to the AD signal input terminal of the AN10 pin of the microcontroller chip U2 after being divided by the resistor R4, the resistor R3 and the resistor R10; the output I/O ports P3.4 and P3.5 of the microcontroller chip U2 Connect to the IN1 pin and IN2 pin of the driver chip U1 respectively; when the AD input terminal AN10 of the microcontroller chip U2 detects that the control power supply voltage is higher than the set value of the coil voltage of the electromagnetic actuator, and the P1.7 of the microcontroller chip U2 When the falling edge of the zero-crossing point of the AC signal is detected, after the delay is controlled by the program of the micro-control chip U2, IN2 is set to a high level, and IN1 is a low level; according to the truth table of U1, see Table 1,

Table 1 Truth table

The OUT2 pin of the driver chip U1 outputs the positive pole, the OUT1 pin outputs the negative supply voltage, the coil of the electromagnetic actuator is energized, the state of the magnetic force of the electromagnet is reversed, and the electromagnetic actuator remains closed under the action of the permanent magnet, and then the micro The program of the control chip U2 controls the low level of IN2, and the level of the IN2 pin of the driver chip U1 is pulled low. According to the truth table of the driver chip U1, the OUT1 pin and OUT2 pin of the driver chip U1 output high resistance, and the electromagnetic execution The mechanism coil is de-energized, and the coil current is zero; when the power supply is de-energized, or the AD of the microcontroller chip U2 detects that the input voltage is lower than the set value of the coil voltage disconnection of the electromagnetic actuator coil, the energy storage capacitor C2 discharges through the diode D5 Continue to supply power to the chip, the diode D4 is turned off in the reverse direction, and it is forbidden to supply power to the power signal conversion circuit 4. The P1.7 pin of the micro-control chip U2 detects the falling edge of the zero-crossing point of the AC signal, which is the AC synchronous zero-crossing signal. Program control IN1 is set to high level, according to the truth table again, the output of the OUT1 pin and OUT2 pin of the driver chip U1 flips instantly, the OUT2 pin outputs the negative pole, the OUT1 pin outputs the positive pole, and the electromagnetic actuator coil is connected to the energy storage capacitor C2. Under the action of the power, the direction of the magnetic force of the electromagnet is reversed, the electromagnetic actuator remains disconnected under the action of the permanent magnet, and then the program of the micro-control chip U2 controls the low level of IN1 to drive the IN1 pin of the chip U1. The level is pulled low, according to the truth table of the driver chip U1, the OUT1 and OUT2 pins of the driver chip U1 output high resistance, the electromagnetic actuator coil is de-energized, and the coil current is zero, preventing the coil from being energized under low voltage; micro control The AN0-AN5 of the chip U2 are AD input channels, which are used to expand other detection and protection functions. The RXD and TXD of the micro-control chip U2 are asynchronous communication interfaces, which can expand the communication function with the upper computer and the communication with the human-machine interface debugging software, and parameter configuration. check;

The control method for breaking the AC circuit without arc is easy to use, solves the problem of arc generated in the switching process of AC inductive load on and off, and has high efficiency and energy saving. Time-delayed on and off control to find the real current zero-crossing point, effectively solving the problem of electrical corrosion of contacts during load switching.

Finally, it should be noted that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, the The technical solutions recorded in the foregoing embodiments can be modified, or some technical features thereof can be equivalently replaced, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included. within the protection scope of the present invention.

Claims (7)

1. A control method of an arc-free disjunction alternating current circuit is characterized in that: the method comprises the following steps:

a power supply step:

converting the input control voltage into a coil working voltage of an electromagnetic actuating mechanism, and supplying power to an energy storage circuit (3);

An input voltage detection step:

detecting an input voltage value in the power supply step, and comparing the input control voltage value with a set value;

a closing step:

when the control power supply is switched on or the input control voltage is detected to be higher than a coil voltage closing set value of the electromagnetic actuating mechanism and a main loop zero-crossing signal is detected, the control circuit delays to output a forward pulse to the coil, and the electromagnetic actuating mechanism is switched on the main loop at the next zero-crossing point;

a disconnection step:

when the control power supply is disconnected or the input control voltage is detected to be lower than the coil voltage closing set value of the electromagnetic actuating mechanism and the zero-crossing signal of the main loop is detected, the control circuit delays to output a reverse pulse to the coil, and the electromagnetic actuating mechanism disconnects the main loop at the next zero-crossing point; the control circuit comprises a series voltage reduction circuit (1) for reducing the input voltage of the power supply to a set voltage, an MCU power supply circuit (2) connected with the series voltage reduction circuit (1), a rectifying and filtering circuit (7) connected with the power supply and used for converting the input alternating current into direct current, an energy storage circuit (3) connected with the MCU power supply circuit (2) and used for providing power energy, and a power supply signal conversion circuit (4) used for detecting the input control voltage, the coil driving circuit (5) is connected with the MCU power supply circuit (2) and used for driving the coil to be switched on and off, the micro-control chip U2 is used for receiving a voltage detection signal of the power signal conversion circuit (4) and sending a zero-crossing pulse signal to the zero-crossing detection conversion circuit (6), and the zero-crossing detection conversion circuit (6) is used for receiving the zero-crossing pulse signal of the micro-control chip U2 and switching the electrode of the input end of the coil; the power supply signal conversion circuit (4) comprises a resistor R4, a resistor R3, a resistor R10, a capacitor C4 and a voltage stabilizing diode DW2, wherein one end of the resistor R4 is connected with the series voltage reduction circuit (1), the resistor R3 is connected to the other end of the resistor R4, the resistor R10 is connected with the resistor R3, and the capacitor C4 and the voltage stabilizing diode DW2 are connected to two ends of the resistor R10 in parallel; the node of the resistor R10, the node of the capacitor C4 and the node of the voltage stabilizing diode DW2 are connected with the cathode of a power supply, and the voltage stabilizing diode DW2 is also connected with AN AN10 pin of the micro-control chip U2; the zero-crossing detection conversion circuit (6) comprises a photoelectric coupler U3 connected with a micro-control chip U2, a triode V1 and a capacitor C5 connected with U3, a resistor R11 connected with a triode V1, a D14 with one end connected with a node of the resistor R11 and the capacitor C5, a zener diode DW3 connected with the other end of the D14, a resistor R5 connected with the zener diode DW3 in parallel, a diode D9 connected with the resistor R5, a diode D13 connected with the diode D9 in parallel, a resistor R8 with one end connected with the diode D9, a resistor R9 with one end connected with the diode D13, a diode D10 with one end connected with a node of the diode D9 and the resistor R8, and a diode D12 connected with the diode D10 in series and connected with a node of the diode D13 and the resistor R9.

2. A method of controlling an arc-free ac circuit for breaking, according to claim 1, wherein: the energy storage circuit (3) comprises a diode D5 with one end connected with the coil driving circuit (5), an energy storage capacitor C2 connected with the other end of the diode D5, and a resistor R2 connected with the diode D5 in parallel;

the rectifying and filtering circuit (7) comprises a diode D1 connected with the positive pole of a power supply and a capacitor C3 connected with a diode D1;

the series voltage reduction circuit (1) comprises a diode D2, a diode D3 and a diode D4 which are sequentially connected in series, and the diode D2 is connected with the rectifying and filtering circuit (7);

the MCU power supply circuit (2) comprises a resistor R1 connected with the series voltage reduction circuit (1), a voltage stabilizing diode DW1 connected to one end of the resistor R1, and a capacitor C1 connected in parallel with the voltage stabilizing diode DW 1;

one end of the capacitor C1 and one end of the voltage stabilizing diode DW1 are connected with a VREF pin of a driving chip U1 in the coil driving circuit (5); the other end of the resistor R1 is connected with a VBB pin of a driving chip U1 in the coil driving circuit (5);

the resistor R7 is connected with the LSS pin of the driving chip U1, and the OUT1 pin and the OUT2 pin of the driving chip U1 are connected with the coil.

3. A method of controlling an arc-less switched ac circuit according to claim 2, characterized in that: in the power supply step: the power supply is powered on, the anode of the power supply is rectified and filtered through a diode D1 and a capacitor C3, the power supply is serially connected with a multi-diode array of a diode D2, a diode D3 and a diode D4 for voltage reduction, the capacitor C2 energy storage capacitor is charged through a resistor R2, and the voltage with the voltage-stabilizing value of 5V, which is serially connected with a voltage-stabilizing diode DW1 through a resistor R1, is connected to an analog voltage input Vref pin of a driving chip U1; the anode of the power supply is connected to the AD signal input end of AN AN10 pin of the micro-control chip U2 after voltage division through a resistor R4, a resistor R3 and a resistor R10; output I/O ports P3.4 and P3.5 of the micro-control chip U2 are connected to pins IN1 and IN2 of the driver chip U1, respectively.

4. A method of controlling an arc-free ac circuit according to claim 1, characterized in that: the coil driving circuit (5) comprises a driving chip U1, a resistor R7 with one end connected to the LSS pin of the driving chip U1, a diode D7 and a diode D11 which are connected to the other end of the resistor R7, a diode D6 connected with the diode D7, and a diode D8 connected with the diode D11.

5. A method of controlling an arc-free ac circuit according to claim 1, characterized in that: IN the closing step, when the AD input end AN10 of the micro-control chip U2 detects that the control power supply voltage is larger than the coil voltage set value of the electromagnetic actuating mechanism and the P1.7 of the micro-control chip U2 detects a falling edge, the IN2 is set to be at a high level and the IN1 is set to be at a low level after the program control of the micro-control chip U2 is delayed; the OUT2 pin of the drive chip U1 outputs a positive pole, the OUT1 pin outputs a negative power supply voltage, the coil of the electromagnetic actuating mechanism is electrified, the magnetic direction state of the electromagnet is overturned, the electromagnetic actuating mechanism is kept closed under the action of the permanent magnet, the IN2 pin of the micro control chip U2 is controlled to be at a low level by a program, the IN2 pin of the drive chip U1 is pulled to be at a low level, the OUT1 pin and the OUT2 pin of the drive chip U1 output high resistance according to a truth table of the drive chip U1, the coil of the electromagnetic actuating mechanism is de-electrified, and the coil current is zero.

6. A method of controlling an arc-free ac circuit according to claim 1, characterized in that: in the disconnection step: when the control power supply is disconnected or the AD of the micro-control chip U2 detects that the input control voltage is lower than the voltage set value of the coil of the electromagnetic actuator, the energy storage capacitor C2 discharges and continues to provide power for the chip through the diode D5, the diode D4 is cut off in the reverse direction, and power supply to the power supply signal conversion circuit (4) is forbidden;

the pin P1.7 of the micro-control chip U2 detects a falling edge, the pin IN1 is controlled to be set at a high level, the output of the pin OUT1 and the pin OUT2 of the driving chip U1 are instantly turned over, the pin OUT2 outputs a negative pole, the pin OUT1 outputs a positive pole, the coil of the electromagnetic execution mechanism is electrified under the action of the energy storage capacitor C2, the state of the magnetic force direction of the electromagnet is turned over, the electromagnetic execution mechanism keeps a disconnected state under the action of a permanent magnet, the micro-control chip U2 controls the low level of the pin IN1, the pin IN1 of the driving chip U1 is pulled down, the pins OUT1 and the pin OUT2 of the driving chip U1 output a high resistance, the coil of the electromagnetic execution mechanism is powered off, and the coil current is zero.

7. A method of controlling an arc-free ac circuit for breaking, according to claim 2, wherein: pins IN1 and IN2 of the driving chip U1 are respectively connected with pins P3.4 and pins P3.5 of the micro control chip U2; the micro-control chip U2 further comprises an RXD pin, a TXD pin, an INT1 pin, an INT1 pin, a TDI pin and a TCK pin, wherein the RXD pin and the TXD pin are used for communication, and the INT1 pin, the INT1 pin, the TDI pin and the TCK pin are used for a programming interface.

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