DYNAMIC BRAKING DEVICE FOR THREE-PHASE INDUCTION MOTOR Russian patent published in 2004 - IPC

FIELD: electrical engineering and automation; dynamic braking of three-phase induction motors. SUBSTANCE: proposed device designed for stepless braking of three-phase induction motor up to full stop of its rotor in response to signal varying according to proportional-integral law for shaping turn-on angle of controllable-rectifier thyristors is provided with newly introduced frequency comparison unit, matching unit, wound braking relay with one break and two make contacts, relay coil being connected to limiting amplifier output. Second lead of STOP button is connected through braking-relay break contact to first phase lead of power supply. First and second input leads of emf sensor are connected through first and second break contacts of contactor to neutral and third-phase leads of motor stator winding, respectively, and output is connected to limiting amplifier output. First and second input leads of matching device are connected through first and second make contacts of braking relay to neutral and third-phase leads of power supply, respectively, and output is connected to first input of comparison unit whose second input is connected to limiting amplifier output. Output of frequency comparison unit is connected both to integration unit input and to first input of adding unit whose second input is connected to integration unit output. Adding unit output is connected to input of pulse-phase control unit. EFFECT: enhanced reliability of stepless motor braking. 1 cl, 1 dwg