ASYNCHRONOUS MOTOR SOFT START-UP DEVICE Russian patent published in 2014 - IPC H02P1/26 H02P1/28 

FIELD: electricity.

SUBSTANCE: the device comprises an incoming switch (1), voltage and current sensors (4, 5), an asynchronous motor (3) which stator winding ends are connected to clamps of the three-phase alternating current diode bridge (9), between direct-current clamps of the latter in conducting direction of a semiconductor switch (10) with snubber circuit (11) a high-frequency pulse-modulated signal from the output of control signal (12) is supplied to its control input. Starts of the stator windings are connected to the output of LC-filters (2) in each motor phase and their inputs are connected to the incoming switch (1). In parallel to each stator winding there are powered alternating current switches (6, 7, 8) which control inputs are coupled to the respective outputs of the control system.

EFFECT: reducing voltage level at the key in the direct-current circuit of the three-phase diode bridge, weight and dimensions due to power loss reduction in the snubber circuit, providing low harmonic factor in the network current.

5 dwg