VARIABLE FREQUENCY AND CURRENT ELECTRIC DRIVE AND METHOD OF SWITCHING OF GATES IN ITS CIRCUIT Russian patent published in 2015 - IPC H02M5/453 

FIELD: electricity.

SUBSTANCE: circuit is implemented using power transistor switches with unilateral conductivity with the damping device connected in parallel to stator windings of the motor. The device is based on the polar capacitor participating by means of two switching transistors in two-stage switching of phase currents. The method of switching of gates is performed in two stages among which the first one is started with connection using the switching transistors of the damping capacitor in a parallel to the circuit with the power transistor of the asynchronous motor phase winding being disabled. The second stage is continued from the moment of switching off of switching transistors and the named power transistor.

EFFECT: smooth change the stator currents at the limited level of switching overvoltage without the need for dissipation of excess energy of switching in the discharge resistor.

2 cl, 3 dwg