JPS5722392A - Slow-damping device for pole change motor - Google Patents

Abstract

PURPOSE:To reduce a regenerative braking torque as well as to smoothly perform a switching from the high-speed side to the low-speed side of a pole change motor by a method wherein an optional switching is performed from a single-phase operation to a three-phase operation by applying the detection signal of a groove harmonic number which is expected to be induced at the high-speed side winding. CONSTITUTION:When the pole change motor I.M. is in three-phase side operation by the closed circuit of a mangetic switch MC1, the MC1 is open-circuited by the detection sensor such as a limit switch and the like, an MC3 is closed, a single-phase is obtained by having the MC1 open- circuited, using the detection sensor such as a limit switch and te like and having the MC3 in closed state, and a regenerative braking operation is performed. At this time, normally opened contact M3 is closed by the closed circuit of te MC3, the positive voltage period only among the groove harmonic number voltage, to be induced on the high-speed side winding, is imputted to a photocoupler PC through a diode D1, the above output is applied by a transistor Tr1 and is inputted to a ring counter R.C. Then, the ring counter RC sends out an output at the point of time when the detected pulse number is coincided with the set pulse number, a transistor Tr2 is turned to ON state, an auxiliary relay Ry is operated, the MC3 is open-circuited, the MC2 is close- circuited and the motor is switched from a single-phase to a three-phase operation.