Three-phase motor Y-connected low-speed reverse operation and braking circuit

The circuit shown in the figure uses high-power semiconductor diodes to reduce the voltage and realize low-speed operation of the motor. When STF is pressed, the AC contactor KMF is powered and closed, and the motor M runs forward. When STP is pressed, motor M is powered off. If STR is pressed at this time, the diodes VD1~VD3 are connected by the reversing contactor KMR, the power supply is rectified, and the DC current is input to the three-phase stator winding. If M is not rotating, STP is pressed, and M is braked. If you want the motor to reverse at low speed, just press STR once and the motor M will run at low speed.