AC power supply misconnection prevention circuit and control method and air conditioner

Abstract

The invention discloses an AC power supply misconnection prevention circuit and a control method and an air conditioner, wherein the AC power supply misconnection prevention circuit comprises a rectifier module connected in series between the AC power supply and a switch power supply, the input end of the rectifier module is connected to a phase sequence detection module, the output end of the rectifier module is connected to a switch power supply input port and is connected to an electrical equipment port through a switch module, and an MCU module controls the on and off of the switch module according to a feedback signal of the phase sequence detection module; the invention solves the problem of damage to a mainboard and a motor due to wrong connection of three-phase electricity during installation, and has the advantages of simple circuit and low cost.

Description

Technical Field

[0001] The invention relates to a power supply circuit, and in particular to an AC power supply misconnection prevention circuit and control method and an air conditioner. Background Art

[0002] In the air conditioning system, whether it is a single-phase system or a three-phase system, the main control board uses a single-phase 220VAC power supply, and the motor needs to be powered by a 310V DC voltage after 220VAC rectification (see Figure 1 ). In the three-phase power system required for the unit, the three-phase L1, L2, L3, and N power supply of the unit needs to be connected during the installation process. However, during the wiring process, it is easy to connect the phase sequence incorrectly. For example, the power supply of the main control board is connected from the phase voltage to the line voltage 380VAC (peak value of about 537V), which will cause the busbar electrolytic capacitor 680UF / 450V and the fan to be over-voltage and damaged. Some engineers use four electrolytic capacitors in series and parallel to meet the requirements of withstand voltage and capacitance, but this solution is more expensive, the PCB board occupies a large area, and only protects the main board, and cannot protect the motor from damage.

[0003] Therefore, how to design an AC power supply misconnection prevention circuit and control method and an air conditioner is a technical problem that needs to be solved urgently in the industry. Summary of the invention

[0004] In order to solve the defect in the prior art that the power phase line is easily connected incorrectly, the present invention provides an AC power misconnection prevention circuit and control method and an air conditioner.

[0005] The technical solution adopted by the present invention is an AC power supply anti-wrong connection circuit, including a rectifier module connected in series between the AC power supply and the switching power supply, the input end of the rectifier module is connected to the phase sequence detection module, the output end of the rectifier module is connected to the switching power supply input port and connected to the power-consuming equipment port through the switch module, and the MCU module controls the on and off of the switch module according to the feedback signal of the phase sequence detection module.

[0006] The switch module includes a seventh relay K7 and an eighth relay K8 connected in series in sequence, the seventh relay K7 and the eighth relay K8 are connected in series in the positive bus or the negative bus at the output end of the rectifier module, the normally open contact of the seventh relay K7 is connected in parallel with a current limiting resistor R4, and a bus capacitor C134 is connected between the positive and negative ports of the electrical equipment port; after power-on, the MCU module controls the eighth relay K8 to close after the AC power connection feedback from the phase sequence detection module is normal, and controls the seventh relay K7 to close after a delay of M seconds.

[0007] Two ends of the coil of the seventh relay K7 are connected in parallel with a seventh freewheeling diode D7 and a third capacitor C3 , and two ends of the coil of the eighth relay K8 are connected in parallel with an eighth freewheeling diode D8 and an eighth capacitor C8 .

[0008] A withstand voltage capacitor group is connected between the positive busbar and the negative busbar at the output end of the rectifier module, and the withstand voltage capacitor group is composed of a plurality of withstand voltage capacitors connected in series.

[0009] A negative temperature coefficient resistor R6 is connected in series between the input end of the rectifier module and the AC power supply.

[0010] A filter module is connected in series between the negative temperature coefficient resistor R6 and the AC power supply.

[0011] A varistor RV1 is connected between the two power lines of the AC power source.

[0012] The present invention discloses a control method for an AC power supply misconnection prevention circuit. The circuit adopts the above-mentioned AC power supply misconnection prevention circuit. The control method comprises the following steps: the circuit is electrically connected to the AC power supply, and electric energy is transmitted to the switching power supply through a rectifier module; after detecting that the AC power supply wiring is abnormal, the eighth relay K8 and the seventh relay K7 are prohibited from closing, and an alarm signal is issued; after detecting that the AC power supply wiring is normal, the eighth relay K8 is controlled to close, the rectifier module charges the bus capacitor C134 through the current limiting resistor R4, and the seventh relay K7 is controlled to close after a delay of M seconds.

[0013] The present invention also provides an air conditioner, which adopts the AC power supply misconnection prevention circuit.

[0014] The present invention also provides an air conditioner, which adopts the above-mentioned AC power supply misconnection prevention circuit control method.

[0015] The beneficial effects of the technical solution provided by the present invention are:

[0016] The invention solves the problem of damage to the mainboard and the motor caused by wrong connection of three-phase electricity during installation, and has the advantages of simple circuit and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention is described in detail below with reference to the embodiments and accompanying drawings, wherein:

[0018] Figure 1 is a circuit diagram of an existing control circuit;

[0019] Figure 2 It is a circuit diagram of a preferred embodiment of the present invention;

[0020] Figure 3 It is a circuit principle block diagram of the present invention. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0022] The present invention can solve the circuit scheme of single-phase mainboard and motor damage caused by wrong phase sequence of three-phase wires. Figure 1 For the existing circuit, if the phase voltage of 220VAC is mistakenly connected to the line voltage of 380VAC (peak value is about 537V), the bus capacitor's withstand voltage is 450V, and the capacitor is damaged due to overvoltage; the motor power supply voltage is about 310V, and the motor will also be damaged due to overvoltage.

[0023] The present invention discloses an AC power supply misconnection prevention circuit. Figure 3 As shown in the circuit principle block diagram, the AC power supply anti-misconnection circuit includes a rectifier module connected in series between the AC power supply and the switching power supply, the input end of the rectifier module is connected to the phase sequence detection module, the output end of the rectifier module is connected to the switching power supply input port and connected to the electrical equipment port through the switch module, and the MCU module controls the on and off of the switch module according to the feedback signal of the phase sequence detection module.

[0024] After power-on, the AC power supply is rectified into DC by the rectifier module, and the switching power supply is used to supply power to the main board of the device through the switching power supply input port. The MCU module obtains continuous power for detection. If the phase sequence is detected to be wrong, the switch module remains disconnected, and the motor connected to the port of the power-consuming device is not powered, thereby achieving the purpose of protecting the motor.

[0025] See also Figure 2 In the preferred embodiment shown, the switch module includes a seventh relay K7 and an eighth relay K8 connected in series in sequence, the seventh relay K7 and the eighth relay K8 are connected in series in the positive bus or the negative bus of the output end of the rectifier module, the normally open contact of the seventh relay K7 is connected in parallel with the current limiting resistor R4, and the bus capacitor C134 is connected between the positive and negative ports of the power-consuming device port; after power-on, the MCU module controls the eighth relay K8 to close after the AC power connection feedback from the phase sequence detection module is normal, and controls the seventh relay K7 to close after a delay of M seconds, and the current limiting resistor R4 exits operation. The seventh relay K7 has a seventh freewheeling diode D7 and a third capacitor C3 connected in parallel at both ends of the coil, and the eighth freewheeling diode D8 and the eighth capacitor C8 connected in parallel at both ends of the coil of the eighth relay K8.

[0026] In a preferred embodiment, a withstand voltage capacitor group is connected between the positive bus and the negative bus at the output end of the rectifier module, and the withstand voltage capacitor group is composed of withstand voltage capacitors C135 and C136 connected in series. The two withstand voltage capacitors C135 and C136 with withstand voltage values ​​of 47UF / 450V are connected in series, and the withstand voltage value of the bus voltage is 900V;

[0027] In a preferred embodiment, a negative temperature coefficient resistor R6 is connected in series between the input end of the rectifier module and the AC power supply. At the moment of power-on, since the busbar capacitor has only two capacitors C135 and C136 connected in series, the capacitance is 23.5UF, and the negative temperature coefficient resistor R6 (cement resistor is used in the preferred embodiment) in series in the line can meet the power-on requirements.

[0028] A filter module is connected in series between the negative temperature coefficient resistor R6 and the AC power supply. A varistor RV1 is connected between the two power lines of the AC power supply. Figure 2 In the preferred embodiment shown, C1, T2 and C2 form a π-shaped filter. FUSE1 is a fuse.

[0029] In a preferred embodiment of the present invention, two capacitors with smaller capacitance (C135 and C136) are first connected in series. After the series connection, the withstand voltage can reach 900V, which meets the requirement of not burning the capacitors when the lines are connected incorrectly. The bus capacitor (C134) with larger capacitance controls the access of the large capacitor through the MCU controller relay. Since one of the lines of the motor is powered at the rear end of the normally open contact of the eighth relay K8, the purpose of protecting the motor can be achieved at the moment of power-on.

[0030] When the power supply voltage is connected to the normal phase voltage 220VAC, the bus voltage supplies power to the switching power supply and the MCU works normally; when the MCU detects that the phase sequence is normal through the phase sequence detection circuit, the eighth relay K8 is energized and the bus capacitor C134 with a larger capacitance is connected to the loop. After a period of time M, the seventh relay K7 is energized, the current limiting resistor R4 stops running, and the MCU and the motor can work normally.

[0031] When the power supply voltage is mistakenly connected to the three-phase line voltage of 380VAC, the withstand voltage of the two capacitors (C135, C136) is 900V, which meets the requirements. The switching power supply chip and MCU work normally. After the MCU works, the phase sequence detection circuit detects the phase sequence error. Relays K7 and K8 remain inactive. The power supply voltage of the motor is disconnected due to the disconnection of the eighth relay K8, achieving the purpose of protecting the motor and the mainboard. The circuit described in this scheme has low cost, small PCB area, and can also achieve the function of protecting the motor.

[0032] The present invention discloses a control method for an AC power supply misconnection prevention circuit. The circuit adopts the above-mentioned AC power supply misconnection prevention circuit. The control method comprises the following steps: the circuit is electrically connected to the AC power supply, and electric energy is transmitted to the switching power supply through a rectifier module; after detecting that the AC power supply wiring is abnormal, the eighth relay K8 and the seventh relay K7 are prohibited from closing, and an alarm signal is issued; after detecting that the AC power supply wiring is normal, the eighth relay K8 is controlled to close, the rectifier module charges the bus capacitor C134 through the current limiting resistor R4, and after a delay of M seconds, the seventh relay K7 is controlled to close, the current limiting resistor R4 is stopped from running, and the electrical equipment is powered on and can work normally.

[0033] It should be noted that the value of M seconds varies depending on the device.

[0034] The invention also discloses an air conditioner, which adopts the AC power supply misconnection prevention circuit.

[0035] The invention also discloses an air conditioner, which adopts the AC power supply misconnection prevention circuit control method.

[0036] The above embodiments are for illustration only and are not intended to be limiting. Any equivalent modifications or changes made thereto without departing from the spirit and scope of the present application shall be included in the scope of the claims of the present application.

Claims

1. An AC power supply misconnection prevention circuit, comprising a rectifier module connected in series between an AC power supply and a switching power supply, characterized in that: The input end of the rectifier module is connected to the phase sequence detection module, the output end of the rectifier module is connected to the switch power input port, and is connected to the power device port through the switch module, and the MCU module controls the on and off of the switch module according to the feedback signal of the phase sequence detection module; The switch module includes a seventh relay K7 and an eighth relay K8 connected in series in sequence, the seventh relay K7 and the eighth relay K8 are connected in series in the positive bus or the negative bus of the output end of the rectifier module, the normally open contact of the seventh relay K7 is connected in parallel with the current limiting resistor R4, and the bus capacitor C134 is connected between the positive and negative ports of the electrical equipment port; after power-on, the MCU module controls the eighth relay K8 to close after the AC power supply wiring feedback from the phase sequence detection module is normal, and controls the seventh relay K7 to close after a delay of M seconds; Two ends of the coil of the seventh relay K7 are connected in parallel with a seventh freewheeling diode D7 and a third capacitor C3 , and two ends of the coil of the eighth relay K8 are connected in parallel with an eighth freewheeling diode D8 and an eighth capacitor C8 .

2. The AC power supply misconnection prevention circuit according to claim 1, characterized in that: A withstand voltage capacitor group is connected between the positive busbar and the negative busbar at the output end of the rectifier module, and the withstand voltage capacitor group is composed of a plurality of withstand voltage capacitors connected in series.

3. The AC power supply misconnection prevention circuit according to claim 1, characterized in that: A negative temperature coefficient resistor R6 is connected in series between the input end of the rectifier module and the AC power supply.

4. The AC power supply misconnection prevention circuit according to claim 3, characterized in that: A filter module is connected in series between the negative temperature coefficient resistor R6 and the AC power supply.

5. The AC power supply misconnection prevention circuit according to claim 1, characterized in that: A varistor RV1 is connected between the two power lines of the AC power source.

6. A method for controlling an AC power supply circuit to prevent wrong connection, characterized in that: The circuit adopts the AC power supply misconnection prevention circuit according to any one of claims 1 to 5, and the control method comprises the following steps: The circuit is electrically connected to an AC power source and transmits electrical energy to the switching power supply through a rectifier module; After detecting that the AC power supply wiring is abnormal, the eighth relay K8 and the seventh relay K7 are prohibited from closing, and an alarm signal is issued; After detecting that the AC power connection is normal, the eighth relay K8 is controlled to close, and the rectifier module charges the bus capacitor C134 through the current limiting resistor R4. After a delay of M seconds, the seventh relay K7 is controlled to close.

7. An air conditioner, characterized in that: The air conditioner adopts the AC power supply misconnection prevention circuit according to any one of claims 1 to 5.

8. An air conditioner, characterized in that: The air conditioner adopts the AC power supply misconnection prevention circuit control method described in claim 6.

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