CN202872701U - Control device for three-phase alternating-current motors - Google Patents

Abstract

The utility model discloses a control device for three-phase alternating-current motors. The control device comprises a current detection module, a reactor L, a first switch module, a second switch module and a control module, wherein three input ends of the first switch module are respectively connected with A phase, B phase and C phase of a three-phase alternating-current power supply, three output ends of the first switch module are respectively connected with three input ends of the reactor L through the current detection module, three output ends of the reactor L are respectively connected with three winding terminals of a three-phase alternating-current motor, three input ends of the second switch module are respectively connected with the three input ends of the reactor L, three output ends of the second switch module are respectively connected with the three output ends of the reactor L, and the current detection module, the first switch module and the second switch module are respectively connected with the control module. With the control device for three-phase alternating-current motors, the starting current of a three-phase alternating-current motor with heavy load can be reduced, and the normal startup of the three-phase alternating-current motor with heavy load can be ensured.

Description

A three-phase AC motor control device

technical field

The utility model relates to the field of electric control, in particular to a three-phase AC motor control device.

Background technique

The existing three-phase AC motor control device controls the starting current of the three-phase AC motor with a large load (such as large centrifugal water pumps, centrifugal fans, presses, conveying and driving motors, etc.) The voltage drop of the transmission line is too large, which makes it difficult to start the three-phase AC motor.

China Patent Publication No. 200994115, published on December 19, 2007, the name of the utility model is a motor energy-saving control device. The application discloses a motor energy-saving control device, which includes a central processing unit, switching elements and a three-phase AC main circuit, the three-phase AC main circuit is connected to the motor through a switching element, the central processing unit is connected to the switching element, a sensor is arranged on the wire connecting the three-phase AC main circuit to the motor, and the sensor is connected to the central processing unit connect. Its disadvantage is that when the device controls the starting of a three-phase AC motor with a large load, the starting current of the three-phase AC motor is too large, which causes the voltage drop of the transmission line to be too large, resulting in difficulty in starting the three-phase AC motor.

Utility model content

The purpose of the utility model is to overcome the technical problem that the current of the three-phase AC motor with a large load is too large when it starts, which causes the voltage drop of the transmission line to be too large, resulting in the difficulty of starting the three-phase AC motor, and provides a three-phase AC motor. The device can reduce the starting current of a three-phase AC motor with a large load and ensure the normal start of the three-phase AC motor with a large load.

In order to solve the above problems, the utility model adopts the following technical solutions to achieve:

A three-phase AC motor control device of the present utility model includes a current detection module, a reactor L, a first switch module, a second switch module and a control module, and the three input terminals of the first switch module are respectively connected to the three-phase Phase A, Phase B and Phase C of the AC power supply are connected, and the three output terminals of the first switch module are respectively connected with the three input terminals of the reactor L through the current detection module, and the three output terminals of the reactor L are respectively connected with the three-phase The three winding terminals of the AC motor are connected, the three input terminals of the second switch module are respectively connected with the three input terminals of the reactor L, and the three output terminals of the second switch module are respectively connected with the three output terminals of the reactor L The signal output terminal of the current detection module, the control terminal of the first switch module and the control terminal of the second switch module are respectively connected with the control module.

In this technical solution, the control module controls the first switch module to be powered on, and the three-phase AC motor is powered on to start. During the starting process, the speed of the three-phase AC motor accelerates, and the current in the circuit is relatively large. The current detection module detects the large current and sends a trigger signal to the control module. The control module controls the second switch module to be disconnected, and no current flows through the second module. At this time, the reactor L acts as an impedance to reduce the starting current of the three-phase AC motor, prevent the voltage drop of the transmission line from being too large, and ensure the three-phase The AC motor starts normally. When the speed of the three-phase AC motor enters a constant speed state, the current decreases to a stable state, the current detection module sends a trigger signal to the control module, the control module controls the second switch module to be turned on, and the second switch module has current passing through, and the three-phase AC power supply The output current flows to the three-phase AC motor through the second switch module, the reactor L stops working, and the three-phase AC motor works normally.

Preferably, the current detection module includes a current transformer TA1, a current transformer TA2 and a current relay KL, and the A-phase output current and the C-phase output current of the three-phase AC power supply respectively pass through the iron core of the current transformer TA1 and the current mutual inductance One end of the coil of the current transformer TA1 is grounded, and the other end is connected to one end of the first coil of the current relay KL, and the other end of the first coil of the current relay KL is respectively connected to one end of the second coil of the current relay KL and its first coil. One end of the three coils is connected, the other end of the second coil of the current relay KL is connected to one end of the current transformer TA2, the other end of the third coil of the current relay KL and the other end of the current transformer TA2 are both grounded, and the normally closed contact of the current relay KL is connected to the current transformer TA2. connected to the control module.

When the operating current of the three-phase AC motor is too large, the current through the coil of the current relay KL exceeds the set value, the normally closed contact of the current relay KL is disconnected, and a trigger pulse signal is sent to the control module. The control module receives the trigger pulse signal and controls the second switch module to turn off.

Preferably, the control module includes a start button ST, a stop button STP, an AC contactor KM and an AC contactor KMY, and the first switch module is composed of the first normally open contact and the second normally open contact of the AC contactor KM. point and the third normally open contact, the second switch module is composed of the first normally open contact, the second normally open contact and the third normally open contact of the AC contactor KMY, the first normally open contact of the AC contactor KMY The series circuit composed of four normally open contacts and the coil of the AC contactor KM is connected in parallel with the series circuit composed of the normally closed contact of the current relay KL, the fifth normally open contact of the AC contactor KM and the coil of the AC contactor KMY. A parallel circuit, the parallel circuit is connected in series with the stop button STP and the single-phase AC power supply to form a start control loop, the start button ST is connected in parallel with the fourth normally open contact of the AC contactor KM.

Press the start button ST, the coil of the AC contactor KM is energized, the first normally open contact, the second normally open contact, the third normally open contact, the fourth normally open contact and the fifth normally open contact of the AC contactor KM The open contact is closed, and the three-phase AC motor is energized and starts to work. The AC contactor KMY is energized, and the first normally open contact, the second normally open contact and the third normally open contact of the AC contactor KMY are closed. Due to the excessive current when starting, the normally closed contact of the current relay KL is disconnected, the coil of the AC contactor KMY is de-energized, the first normally open contact, the second normally open contact and the third normally open contact of the AC contactor KMY The contacts are open. Press the stop button STP, the first normally open contact, the second normally open contact and the third normally open contact of the AC contactor KM are disconnected, and the three-phase AC motor stops working.

Preferably, the three-phase AC motor control device further includes an overload detection module, the overload detection module includes a current transformer TA3, a current transformer TA4 and a current relay KGL, and the control module also includes a time relay KT, a three-phase AC The A-phase output current and C-phase output current of the power supply pass through the iron core of the current transformer TA3 and the iron core of the current transformer TA4 respectively, and one end of the current transformer TA3 is grounded, and the other end is connected to the coil end of the current relay KGL and the current mutual One end of the transformer TA4 is connected, the other end of the coil of the current relay KGL and the other end of the current transformer TA4 are grounded, the normally open contact of the current relay KGL, the coil of the time relay KT and the single-phase AC power supply are connected in series to form a loop, and the normal of the time relay KT The closing contact is connected in series in the starting control loop.

When the three-phase AC motor is overloaded, the working current of the three-phase AC motor is too large, the current through the coil of the current relay KGL exceeds the set value, the normally open contact of the current relay KGL is closed, and the coil of the time relay KT is energized. The normally closed contact of the time relay KT is disconnected after the set time, the AC contactor KM is powered off, and the first normally open contact, the second normally open contact and the third normally open contact of the AC contactor KM are disconnected , The three-phase AC motor stops working to prevent the three-phase AC motor from being damaged.

Preferably, the three-phase AC motor control device further includes a voltage detection module, the voltage detection module includes a voltage transformer TV, a voltage relay KY1, a voltage relay KY2 and a voltage relay KY3, and the control module further includes a signal relay KX1 and Indicator light H1, the three input terminals of the primary coil of the voltage transformer TV are respectively connected with phase A, phase B and phase C of the three-phase AC power supply, and the two ends of the coil of the voltage relay KY1 are respectively connected with the A phase of the secondary coil of the voltage transformer TV. The phase output terminal is connected to the B-phase output terminal, the two ends of the coil of the voltage relay KY2 are respectively connected to the B-phase output terminal and the C-phase output terminal of the voltage transformer TV secondary coil, and the two ends of the coil of the voltage relay KY3 are respectively connected to the voltage transformer TV The A-phase output terminal of the TV secondary coil is connected to the C-phase output terminal, the single-phase AC power supply, the coil of the signal relay KX1, the normally open contact of the voltage relay KY1 and its normally closed contact are connected in series to form a loop, and the voltage relay KY2 The normally open contacts and the normally open contacts of the voltage relay KY3 are respectively connected in parallel with the normally open contacts of the voltage relay KY1, the normally closed contacts of the voltage relay KY2 and the normally closed contacts of the voltage relay KY3 are respectively connected with the normally closed contacts of the voltage relay KY1 The contacts are connected in parallel, and the normally open contact of the signal relay KX1, the indicator light H1 and the single-phase AC power supply are connected in series to form a circuit.

During the operation of the three-phase AC motor, when any one of phase A, phase B and phase C of the three-phase AC power supply loses or loses phase, the voltage on the voltage relay KY1, voltage relay KY2 or voltage relay KY3 exceeds the set value. Fixed value action, the signal relay KX1 coil is energized, and the normally open contact of the signal relay KX1 is closed. The indicator light H1 lights up when it is energized, reminding the staff that the three-phase AC motor is in a state of phase loss or lack of phase operation, and emergency treatment is required.

Preferably, the voltage detection module also includes a voltage relay KY4, the control module also includes a signal relay KX2 and an indicator light H2, and the two ends of the coil of the voltage relay KY4 are respectively connected to the A-phase output terminal and the secondary coil of the voltage transformer TV. The C-phase output terminal is connected, the normally open contact of the voltage relay KY4, the coil of the signal relay KX2 and the single-phase AC power supply are connected in series to form a circuit, and the normally open contact of the signal relay KX2, the indicator light H2 and the single-phase AC power supply are connected in series to form a circuit circuit.

During the operation of the three-phase AC motor, when a low voltage occurs in any of the phases A, B and C of the three-phase AC power supply, the voltage on the coil of the voltage relay KY4 is lower than the set value, and the voltage of the voltage relay KY4 The normally open contact is closed and the normally open contact of the signal relay KX2 is closed. The indicator light H2 lights up when it is powered on, reminding the staff that the three-phase AC motor is in a low-voltage operating state and needs emergency treatment.

Preferably, the three-phase AC motor control device further includes a leakage detection module, the leakage detection module includes a current transformer TA5 and a zero-sequence current relay KN, the control module includes a signal relay KX3 and an indicator light H3, and the three-phase AC The A-phase output current, B-phase output current and C-phase output current of the power supply pass through the iron core of the current transformer TA5, and the coil of the current transformer TA5 is connected in series with the coil of the zero-sequence current relay KN to form a loop, and the zero-sequence current relay The normally open contact of KN, the coil of the signal relay KX3 and the single-phase AC power supply are connected in series to form a loop, and the normally open contacts of the signal relay KX3, the indicator light H3 and the single-phase AC power supply are connected in series to form a loop.

During the operation of the three-phase AC motor, when any phase of A, B, and C phases of the three-phase AC power supply leaks and generates zero-sequence current, the induced current generated by the current transformer TA5 is not zero, and the zero-sequence The coil of the current relay KN is energized, the normally open contact of the zero sequence current relay KN is closed, and the normally open contact of the signal relay KX3 is closed. The indicator light H3 lights up when it is energized, reminding the staff that the three-phase AC motor is in a state of leakage and requires emergency treatment.

The beneficial effects of the utility model are: (1) The starting current of the three-phase AC motor with a large load can be reduced, and the normal start of the three-phase AC motor with a large load can be ensured. (2) When the three-phase AC motor is overloaded, the control module controls the three-phase AC motor to stop working to prevent the three-phase AC motor from being damaged. (3) During the operation of the three-phase AC motor, when any one of the phases A, B and C of the three-phase AC power supply loses or loses phase, the indicator H1 is powered on and lights up to remind the staff of the three-phase AC The motor is in a phase loss or phase loss operation state. (4) During the operation of the three-phase AC motor, when any of the phases A, B and C of the three-phase AC power supply has a low voltage, the indicator light H2 is powered on and lights up to remind the staff that the three-phase AC motor is in Low voltage operation state. (5) During the operation of the three-phase AC motor, when any one of the phases A, B and C of the three-phase AC power supply leaks electricity, the indicator light H3 lights up when it is powered on, reminding the staff that the three-phase AC motor is in leakage operation state.

Description of drawings

Fig. 1 is a kind of circuit principle connection block diagram of the present utility model;

Fig. 2 is the circuit schematic diagram of the three-phase AC motor working circuit of the present utility model;

Fig. 3 is the circuit schematic diagram of the current detection module of the present utility model;

Fig. 4 is the circuit schematic diagram of the overload detection module of the present utility model;

Fig. 5 is the schematic circuit diagram of the leakage detection module of the present invention;

Fig. 6 is a schematic circuit diagram of the control module of the present invention.

In the figure: 1. Current detection module, 2. First switch module, 3. Second switch module, 4. Control module, 5. Three-phase AC power supply, 6. Single-phase AC power supply, 7. Overload detection module, 8. Voltage detection module, 9, leakage detection module, 10, three-phase AC motor.

Detailed ways

The technical solutions of the present utility model will be further specifically described below through the embodiments and in conjunction with the accompanying drawings.

Embodiment: A three-phase AC motor control device in this embodiment, as shown in FIG. 1 , includes a current detection module 1, a reactor L, a first switch module 2, a second switch module 3, a control module 4, and an overload detection module Module 7, voltage detection module 8 and leakage detection module 9, the three input terminals of the first switch module 2 are respectively connected to the A phase, B phase and C phase of the three-phase AC power supply 5 through the voltage detection module 8, the first switch module The three output ends of 2 are respectively connected to the three input ends of the reactor L through the current detection module 1 and the overload detection module 7, and the three output ends of the reactor L are respectively connected to the three-phase AC motor 10 through the leakage detection module 9 The winding terminals are connected, the three input terminals of the second switch module 3 are respectively connected with the three input terminals of the reactor L, the three output terminals of the second switch module 3 are respectively connected with the three output terminals of the reactor L, and the control Module 4 is connected to current detection module 1 , first switch module 2 , second switch module 3 , single-phase AC power supply 6 , overload detection module 7 , voltage detection module 8 and leakage detection module 9 .

As shown in Figure 2, the voltage detection module 8 includes a voltage transformer TV, a voltage relay KY1, a voltage relay KY2, a voltage relay KY3 and a voltage relay KY4, and the first switch module 2 is composed of the first normally open contact of the AC contactor KM, Composed of the second normally open contact and the third normally open contact, the second switch module 3 is composed of the first normally open contact, the second normally open contact and the third normally open contact of the AC contactor KMY, three-phase The AC motor control device also includes an isolating switch QS. The three static contacts of the isolating switch QS are respectively connected to the A phase, B phase and C phase of the three-phase AC power supply 5, and the three moving contacts of the isolating switch QS are respectively connected to one end of the first normally open contact of the AC contactor KM , One end of the second normally open contact is connected to one end of the third normally open contact, the other end of the first normally open contact, the other end of the second normally open contact and the other end of the third normally open contact of the AC contactor KM are respectively It is connected with the three input terminals of the reactor L, and the three output terminals of the reactor L are respectively connected with the three winding terminals of the three-phase AC motor 10 . One end of the first normally open contact, one end of the second normally open contact and one end of the third normally open contact of the AC contactor KMY are respectively connected to the three input terminals of the reactor L, and the first normally open contact of the AC contactor KMY The other end of the point, the other end of the second normally open contact and the other end of the third normally open contact are respectively connected to the three output ends of the reactor L.

The three input terminals of the primary coil of the voltage transformer TV are respectively connected with the three moving contacts of the isolating switch QS. The two ends of the coil of the voltage relay KY1 are respectively connected to the A-phase output terminal and the B-phase output terminal of the voltage transformer TV secondary coil, and the two ends of the coil of the voltage relay KY2 are respectively connected to the B-phase output terminal and the B-phase output terminal of the voltage transformer TV secondary coil. The C-phase output terminal is connected, the two ends of the coil of the voltage relay KY3 are respectively connected with the A-phase output terminal and the C-phase output terminal of the voltage transformer TV secondary coil, and the coil of the voltage relay KY4 is connected in parallel with the coil of the voltage relay KY3.

As shown in Figure 3, the current detection module 1 includes a current transformer TA1, a current transformer TA2 and a current relay KL, and the A-phase output current and the C-phase output current of the three-phase AC power supply 5 respectively pass through the iron core of the current transformer TA1 One end of the coil of the current transformer TA1 is grounded, the other end is connected to one end of the first coil of the current relay KL, and the other end of the first coil of the current relay KL is respectively connected to one end of the second coil of the current relay KL One end of the third coil of the current relay KL is connected to one end of the second coil of the current relay KL and one end of the current transformer TA2 is connected, and the other end of the third coil of the current relay KL and the other end of the current transformer TA2 are both grounded.

As shown in Figure 4, the overload detection module 7 includes a current transformer TA3, a current transformer TA4 and a current relay KGL, and the A-phase output current and the C-phase output current of the three-phase AC power supply 5 respectively pass through the iron core of the current transformer TA3 And the iron core of the current transformer TA4, one end of the current transformer TA3 is grounded, and the other end is connected with the coil end of the current relay KGL and the end of the current transformer TA4 respectively, and the other end of the coil of the current relay KGL is grounded with the other end of the current transformer TA4.

As shown in Figure 5, the electric leakage detection module 9 includes a current transformer TA5 and a zero-sequence current relay KN, and the A-phase output current, B-phase output current and C-phase output current of the three-phase AC power supply 5 all pass through the current transformer TA5 The iron core, the coil of the current transformer TA5 and the coil of the zero-sequence current relay KN are connected in series to form a loop.

As shown in Figure 6, the control module 4 includes a power switch SA, a start button ST, a stop button STP, an AC contactor KM, an AC contactor KMY, a time relay KT, a signal relay KX1, a signal relay KX2, a signal relay KX3, and an indicator light RD, indicator light HLRD, indicator light HLGN, indicator light H1, indicator light H2, indicator light H3 and electric bell HA.

The series circuit composed of the fourth normally open contact of the AC contactor KM and the coil of the AC contactor KM and the normally closed contact of the current relay KL, the fifth normally open contact of the AC contactor KM and the coil of the AC contactor KMY The composed series circuit is connected in parallel to form a parallel circuit, which forms a circuit in series with the stop button STP, the normally closed contact of the time relay KT, the power switch SA and the single-phase AC power supply 6, and the sixth normally open contactor of the AC contactor KM The series circuit composed of contacts and indicator light RD is connected in parallel with the parallel circuit, the series circuit composed of the fourth normally open contact of AC contactor KMY and indicator light HLRD is connected in parallel with the parallel circuit, the start button ST is connected with the AC contactor KM The fourth normally open contact is connected in parallel. The normally closed contact of the AC contactor KM, the indicator light HLGN, the power switch SA and the single-phase AC power supply 6 are connected in series to form a loop.

The normally open contact of the current relay KGL, the coil of the time relay KT, the power switch SA and the single-phase AC power supply 6 are connected in series to form a loop.

Single-phase AC power supply 6, power switch SA, coil of signal relay KX1, normally open contact of voltage relay KY1 and its normally closed contact are connected in series to form a circuit, the normally open contact of voltage relay KY2 and the normally open contact of voltage relay KY3 The contacts are respectively connected in parallel with the normally open contacts of the voltage relay KY1, and the normally closed contacts of the voltage relay KY2 and the normally closed contacts of the voltage relay KY3 are respectively connected in parallel with the normally closed contacts of the voltage relay KY1. The first normally open contact of the signal relay KX1, the indicator light H1, the power switch SA and the single-phase AC power supply 6 are connected in series to form a circuit, the second normally open contact of the signal relay KX1, the electric bell HA, the power switch SA and the single-phase AC The power supply 6 is connected in series to form a loop.

The normally open contact of the voltage relay KY4, the coil of the signal relay KX2, the power switch SA and the single-phase AC power supply 6 are connected in series to form a loop. The first normally open contact of the signal relay KX2, the indicator light H2, the power switch SA and the single-phase AC power supply 6 are connected in series to form a loop. The second normally open contact of the signal relay KX2 is connected in parallel with the second normally open contact of the signal relay KX1.

The normally open contact of the zero-sequence current relay KN, the coil of the signal relay KX3, the power switch SA and the single-phase AC power supply 6 are connected in series to form a loop. The first normally open contact of the signal relay KX3, the indicator light H3, the power switch SA and the single-phase AC power supply 6 are connected in series to form a loop. The second normally open contact of the signal relay KX3 is connected in parallel with the second normally open contact of the signal relay KX1.

Close the isolation switch QS and the power switch SA. Press the start button ST, the coil of the AC contactor KM is energized, the first normally open contact, the second normally open contact, the third normally open contact, the fourth normally open contact, the fifth normally open contact of the AC contactor KM The open contact and the sixth normally open contact are closed, the three-phase AC motor 10 is energized and started, and the indicator light RD is turned on.

During the starting process, the rotation speed of the three-phase AC motor 10 accelerates, and the current in the circuit is relatively large. Due to the excessive current when starting, the normally closed contact of the current relay KL is disconnected, the coil of the AC contactor KMY is de-energized, the first normally open contact, the second normally open contact and the third normally open contact of the AC contactor KMY The contacts are open. At this time, the reactor L acts as an impedance to reduce the starting current of the three-phase AC motor 10 , prevent the excessive voltage drop of the transmission line, and ensure the normal start of the three-phase AC motor 10 . When the rotation speed of the three-phase AC motor 10 enters a constant speed state, the current decreases to a stable state, the normally closed contact of the current relay KL is closed, the coil of the AC contactor KMY is energized, the first normally open contact of the AC contactor KMY, the second The normally open contact, the third normally open contact and the fourth normally open contact are closed, the reactor L stops working, and the indicator light HLRD is on.

When the three-phase AC motor 10 is overloaded, the operating current of the three-phase AC motor 10 is too large, the current passing through the coil of the current relay KGL exceeds the set value, the normally open contact of the current relay KGL is closed, and the coil of the time relay KT is energized. The normally closed contact of the time relay KT is disconnected after the set time, the AC contactor KM is powered off, and the first normally open contact, the second normally open contact and the third normally open contact of the AC contactor KM are disconnected , the three-phase AC motor 10 stops working to prevent the three-phase AC motor 10 from being damaged, the normally closed contact of the AC contactor KM is closed, and the indicator light HLGN lights up.

During the operation of the three-phase AC motor 10, when any one of phase A, phase B and phase C of the three-phase AC power supply 5 loses or loses phase, the voltage on the voltage relay KY1, voltage relay KY2 or voltage relay KY3 When the set value is exceeded, the signal relay KX1 coil is energized, the first normally open contact and the second normally open contact of the signal relay KX1 are closed, the indicator light H1 is lit, and the electric bell HA alarms to remind the staff that the three-phase AC motor 10 is in In case of phase failure or phase failure, emergency treatment is required.

During the operation of the three-phase AC motor 10, when a low voltage occurs in any of the phases A, B and C of the three-phase AC power supply 5, the voltage on the coil of the voltage relay KY4 is lower than the set value, and the voltage relay The normally open contact of KY4 is closed, the first normally open contact and the second normally open contact of the signal relay KX2 are closed, the indicator light H2 is lit, and the electric bell HA alarms to remind the staff that the three-phase AC motor 10 is in a low-voltage operating state , need urgent treatment.

During the operation of the three-phase AC motor 10, when a leakage occurs in any of the phases A, B and C of the three-phase AC power supply 5 and a zero-sequence current is generated, the induced current generated by the current transformer TA5 is not zero, The coil of the zero-sequence current relay KN is energized, the normally open contact of the zero-sequence current relay KN is closed, the first normally open contact and the second normally open contact of the signal relay KX3 are closed, the indicator light H3 lights up, and the electric bell HA alarms. Remind the staff that the three-phase AC motor 10 is in a state of leakage and needs emergency treatment

Claims (7)

1. A three-phase AC motor control device, characterized in that it includes a current detection module (1), a reactor L, a first switch module (2), a second switch module (3) and a control module (4), the The three input terminals of the first switch module (2) are respectively connected to the phase A, phase B and phase C of the three-phase AC power supply (5), and the three output terminals of the first switch module (2) pass through the current detection module (1) Connected to the three input terminals of the reactor L, the three output terminals of the reactor L are respectively connected to the three winding terminals of the three-phase AC motor (10), and the three terminals of the second switch module (3) The input terminals are respectively connected to the three input terminals of the reactor L, the three output terminals of the second switch module (3) are respectively connected to the three output terminals of the reactor L, the signal output terminals of the current detection module (1), the first The control terminal of the first switch module (2) and the control terminal of the second switch module (3) are respectively connected with the control module (4). 2. A three-phase AC motor control device according to claim 1, characterized in that: the current detection module (1) includes a current transformer TA1, a current transformer TA2 and a current relay KL, a three-phase AC power supply ( 5) The A-phase output current and C-phase output current pass through the iron core of the current transformer TA1 and the iron core of the current transformer TA2 respectively, one end of the coil of the current transformer TA1 is grounded, and the other end is connected to the first coil of the current relay KL One end is connected, the other end of the first coil of the current relay KL is respectively connected with one end of the second coil of the current relay KL and one end of the third coil, the other end of the second coil of the current relay KL is connected with the end of the current transformer TA2, and the current relay KL Both the other end of the third coil and the other end of the current transformer TA2 are grounded, and the normally closed contact of the current relay KL is connected to the control module (4). 3. A three-phase AC motor control device according to claim 2, characterized in that: the control module (4) includes a start button ST, a stop button STP, an AC contactor KM and an AC contactor KMY, the The first switch module (2) is composed of the first normally open contact, the second normally open contact and the third normally open contact of the AC contactor KM, and the second switch module (3) is composed of the AC contactor KMY Composed of the first normally open contact, the second normally open contact and the third normally open contact, the series circuit composed of the fourth normally open contact of the AC contactor KM and the coil of the AC contactor KM and the normal of the current relay KL The series circuit composed of the closed contact, the fifth normally open contact of the AC contactor KM and the coil of the AC contactor KMY is connected in parallel to form a parallel circuit, and the parallel circuit is connected in series with the stop button STP and the single-phase AC power supply (6) to form a To start the control loop, the start button ST is connected in parallel with the fourth normally open contact of the AC contactor KM. 4. A three-phase AC motor control device according to claim 3, characterized in that it also includes an overload detection module (7), and the overload detection module (7) includes a current transformer TA3, a current transformer TA4 and a current transformer Relay KGL, the control module (4) also includes a time relay KT, the A-phase output current and C-phase output current of the three-phase AC power supply (5) respectively pass through the iron core of the current transformer TA3 and the iron core of the current transformer TA4 One end of the current transformer TA3 is grounded, and the other end is respectively connected to one end of the coil of the current relay KGL and one end of the current transformer TA4, the other end of the coil of the current relay KGL and the other end of the current transformer TA4 are grounded, and the normally open contact of the current relay KGL The point, the coil of the time relay KT and the single-phase AC power supply (6) are connected in series to form a loop, and the normally closed contacts of the time relay KT are connected in series in the start control loop. 5. A three-phase AC motor control device according to claim 3 or 4, characterized in that it also includes a voltage detection module (8), and the voltage detection module (8) includes a voltage transformer TV, a voltage relay KY1, a voltage Relay KY2 and voltage relay KY3, the control module (4) also includes a signal relay KX1 and an indicator light H1, and the three input terminals of the primary coil of the voltage transformer TV are respectively connected to phase A and phase B of the three-phase AC power supply (5) It is connected with phase C, the two ends of the coil of the voltage relay KY1 are respectively connected with the A-phase output terminal and the B-phase output terminal of the voltage transformer TV secondary coil, and the two ends of the coil of the voltage relay KY2 are respectively connected with the secondary coil of the voltage transformer TV The B-phase output terminal is connected to the C-phase output terminal, the two ends of the coil of the voltage relay KY3 are respectively connected to the A-phase output terminal and the C-phase output terminal of the voltage transformer TV secondary coil, the single-phase AC power supply (6), and the signal relay KX1 The coil, the normally open contact of the voltage relay KY1 and its normally closed contact are connected in series to form a loop, the normally open contacts of the voltage relay KY2 and the normally open contacts of the voltage relay KY3 are respectively connected in parallel with the normally open contacts of the voltage relay KY1 , the normally closed contacts of the voltage relay KY2 and the normally closed contacts of the voltage relay KY3 are respectively connected in parallel with the normally closed contacts of the voltage relay KY1, the normally open contacts of the signal relay KX1, the indicator light H1 and the single-phase AC power supply (6) connected in series into a loop. 6. A three-phase AC motor control device according to claim 5, characterized in that: the voltage detection module (8) also includes a voltage relay KY4, and the control module (4) also includes a signal relay KX2 and an indicating Lamp H2, the two ends of the coil of the voltage relay KY4 are respectively connected with the A-phase output terminal and the C-phase output terminal of the secondary coil of the voltage transformer TV, the normally open contact of the voltage relay KY4, the coil of the signal relay KX2 and the single-phase AC power supply (6) Connected in series to form a circuit, the normally open contact of the signal relay KX2, the indicator light H2 and the single-phase AC power supply (6) connected in series to form a circuit. 7. A three-phase AC motor control device according to claim 3 or 4, characterized in that it also includes a leakage detection module (9), and the leakage detection module (9) includes a current transformer TA5 and a zero-sequence current relay KN , the control module (4) includes a signal relay KX3 and an indicator light H3, the A-phase output current, B-phase output current and C-phase output current of the three-phase AC power supply (5) all pass through the iron core of the current transformer TA5, The coil of the current transformer TA5 and the coil of the zero-sequence current relay KN are connected in series to form a loop, the normally open contact of the zero-sequence current relay KN, the coil of the signal relay KX3 and the single-phase AC power supply (6) are connected in series to form a loop, the signal relay The normally open contact of KX3, indicator light H3 and single-phase AC power supply (6) are connected in series to form a loop.

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