JPS56101397A - Motor control circuit - Google Patents

Abstract

PURPOSE:To reduce the switching loss of the motor control circuit with a simple configuration by conducting an AC switching element between a full-wave rectifying circuit and a smoothing circuit via an AC switch firing circuit with a double voltage command signal of a rectangular wave signal generator, thereby obtaining the double voltage direct current. CONSTITUTION:An AC/DC converter 1' consists of a full-wave rectifying circuit using diodes 11'-14', a smoothing circuit having a resistor 15' and smoothing capacitors 16', 17' a triac 18 connected to the intermediate point between the one end of the AC input of the full-wave rectifying circuit and the capacitors 16', 17', and an AC switch firing circuit 19 for controlling the triac. When the rectangular wave generator 40 generates a timing signal having higher than a predetermined frequency to transistors 21-26 for driving an inverter motor 30, the transistor 19a of the firing circuit 19 is conducted by the double voltage command signal generated simultaneously, and thereby the triac 18 is conducted so as to obtain the double voltage direct current. Thus, the switching loss and noise can be reduced with a simple configuration.