MOTOR SPEED CONTROLLER

PURPOSE:To prevent malfunctioning owing to noise and a high temperature minimizing electronic circuit elements by forming speed controller employing a pulse duty controlling element in which a coil is wound on an amorphous soft magnetic core. CONSTITUTION:A pulse duty controller PDC is composed of control elements 1 and 2 in which coils 1b and 1c are wound on a ring core 1a made of an amorphous soft magnetic body, diodes 4-8 and a transistor 6. A pulse generator PEC is connected to an input end of the controller while a field winding of a motor 1 to the output end thereof. The base of the transistor 6 is controlled with a speed setting circuit 20 containing a thermistor 22. Therefore, the conduction level of the transistor 6 varies according to variations in the temperature to change the pulse duty ratio of the control elements 1 and 2 thereby controlling the revolution of the motor 10. This provides a controller with a vibration resistance ideal for vehicles.