The motor controller is mainly realized by operating the motor driver through computer programming. The motor controller has the characteristics of maintenance free, fast response speed, stable control of the motor and so on.
1、 Contactor control motor forward and reverse circuit
The contactor controls the inching of the motor. This circuit has only one steering. How to change the steering of the motor, only the phase sequence of two items needs to be changed. Therefore, this circuit has only one contactor and can only control the operation of one motor in one direction.
L1 — L2 — L3 three-phase power supply enters the Fu fuse, the fuse comes out into the main contact of KM1 contactor, comes out into the thermal relay and goes to the motor. We assume that the forward rotation, then the reverse rotation is connected in this way. We connect the three-phase power from the fuse in parallel, and the three-phase power enters the km2 main contact. For the outgoing line, pay attention to changing the phase sequence of the two phases, any two phases can be. It can be connected in parallel to the outgoing line of KM1 contactor.
2、 Double interlocking reversible control circuit
Working principle of double interlocking reversible control circuit: press the start button SB2, KM1 suction and self-protection, and the motor rotates forward. KM1 contact in parallel with the normally open point of button SB2 is a self-protection contact. Press the start button Sb3, KM1 is powered off and released, km2 is sucked and self-protection, and the motor is reversed. SB1 is the stop button. The circuit realizes mechanical interlocking by the dynamic breaking contacts of buttons SB2 and Sb3, and the auxiliary dynamic breaking contacts of km2 and KM1 connected in series in AC contactor coils KM1 and km2 realize electrical interlocking. The fr dynamic breaking contact in series in the control circuit is that the thermal relay automatically disconnects the control circuit when the motor is overloaded or out of phase and overheated, so as to protect the motor.
3、 Electromagnetic holding brake control circuit
After the power switch QS is turned on, press the start button SB2, and the contactor km coil is energized and self-locking. The Yb coil of the electromagnetic holding brake is energized to attract the armature (moving iron core) to make the moving and static iron core close. The moving iron core overcomes the spring tension and forces the brake lever to move upward, so as to separate the brake shoe of the brake from the brake wheel and cancel the braking of the motor; At the same time, the motor is powered on and started to normal operation. When it is necessary to stop, press the stop button SB1, the contactor km will be powered off and released, and the power supply of the motor will be cut off. At the same time, the coil of the electromagnetic holding brake will also be powered off, and the armature will be released. Under the action of spring tension, the brake shoe will hold the brake wheel tightly, and the motor will be braked and stop rotating quickly.
Electromagnetic holding brake is widely used in hoisting machinery. When the heavy object is lifted to a certain height, if the line suddenly breaks down or power is cut off, the motor will be cut off, and the electromagnetic holding brake coil will also be cut off. The brake shoe will immediately hold the brake wheel to make the motor brake and stop, so as to prevent accidents caused by the sudden fall of heavy objects.
Editor in charge: PJ