Excitation controller for small synchronous motor - uses CMOS output amplifier to switch field current

摘要

A single CMOS amplifier (6) is emplyed which receives an input (Q) from an oscillator setting the motor speed. The field winding (11) is connected between the amplifier output and one pole of the d.c. power supply (9) with a series capacitor (12) included. For zero signal input to the amplifier the current flow (25) charges the capacitor from the supply thereby producing a current pulse in the field winding. With an amplifier input the supply is blocked and the capacitor discharges (26) giving a reverse pulse through the windings. Thus an alternating flux is set up.