Motor forward and reverse circuit diagram analysis

Single chip microcomputer STM32L151CCU6

1206 red anti-stick

The forward and reverse control of the motor uses the production machinery to require moving parts to move in both positive and negative directions, such as the forward and reverse control of the machine table motor; the positive and negative control of the universal milling machine spindle; the rise and fall of the elevator and crane Control and other places. So how can we achieve positive and negative control?

To realize the forward and reverse control of the motor, it is necessary to adjust any two of the phase sequence of the power supply (we call it commutation), usually the V phase is unchanged, and the U phase and W are relative to the regulator, in order to ensure two contacts. When the device is in motion, the phase sequence of the motor can be reliably replaced. When wiring, the upper port of the contactor should be kept consistent, and the lower port of the contactor should be phase-adjusted. Since the phase sequence of the two phases is reversed, it is necessary to ensure that the two KM coils cannot be energized at the same time, otherwise serious phase-to-phase short-circuit faults will occur, so interlocking must be taken. For safety reasons, the double interlocking positive and negative control lines of the button interlock (mechanical) and the contactor interlock (electrical) are often used (as shown in the figure below); the button interlock is used even if the forward and reverse buttons are pressed at the same time. It is also impossible for the two contactors for phase modulation to be energized at the same time, and the phase-to-phase short circuit is avoided mechanically. In addition, since the contactor of the application is interlocked, as long as one of the contactors is energized, the long-closed contacts will not be closed, so that in the application of mechanical and electrical double interlocking, the power supply system of the motor cannot be short-circuited. The motor is effectively protected, and accidents caused by phase-to-phase short circuit during phase modulation are avoided, and the contactor is burned out.

In the figure, the main circuit uses two contactors, a forward contactor KM1 and a reverse contactor KM2. When the three pairs of main contacts of the contactor KM1 are turned on, the phase sequence of the three-phase power source is connected to the motor by U-V-W. When the three pairs of main contacts of the contactor KM1 are disconnected and the three pairs of main contacts of the contactor KM2 are turned on, the phase sequence of the three-phase power source is connected to the motor by W-V-U, and the motor rotates in the opposite direction. The circuit requires that the contactor KM1 and the contactor KM2 cannot be powered on at the same time, otherwise their main contacts will be closed at the same time, causing the U and W two-phase power supply to be short-circuited. To this end, in the respective branches of the KM1 and KM2 coils, a pair of auxiliary normally closed contacts of the other pair are connected in series to ensure that the contactors KM1 and KM2 are not simultaneously powered, and the two pairs of auxiliary normally closed contacts of KM1 and KM2 are The function played in the line is called interlocking or interlocking. The two pairs of auxiliary normally closed contacts are called interlocking or interlocking contacts.
Forward start process: press the start button SB2, the contactor KM1 coil is energized, and the auxiliary normally open contact of KM1 in parallel with SB2 is closed to ensure that the KMl coil is continuously energized, and the main contact of the KM1 connected in series in the motor circuit is continuously closed. The motor runs continuously in the forward direction.
Stop process: press the stop button SB1, the contactor KMl coil is de-energized, and the auxiliary contact of KM1 connected in parallel with SB2 is disconnected to ensure that the KMl coil is continuously de-energized, and the main contact of KMl connected in series in the motor circuit is continuously disconnected. , cut off the motor stator power supply, the motor stops.
Reverse start process: press the start button SB3, the contactor KM2 coil is energized, and the auxiliary normally open contact of KM2 in parallel with SB3 is closed to ensure that the KM2 coil is continuously energized, and the main contact of the KM2 connected in series in the motor circuit is continuously closed. The motor runs continuously in reverse.
For this kind of control circuit, when changing the steering of the motor, it is necessary to press the stop button SB1 and then the reverse button SB3 to reverse the motor. If you do not press SB1 first, but press SB3 directly, the motor will not reverse.