Controlling/regulating current in DC machine for fan involves varying PWM generator control signal depending on comparison result so current in machine is regulated to demand value

摘要

The method involves controlling a PWM generator's (182) duty cycle with a control signal, controlling the current in the DC machine with the PWM generator output (PWM2) to produce a pulsed DC current (i2;i2'), deriving a pulsed current-dependent signal from the pulsed DC current, comparing it with a demand signal and varying the PWM generator control signal accordingly so the current in the machine is regulated to the demand value. Independent claims are also included for a DC machine for implementing the method, an arrangement for controlling or regulating the revolution rate of a DC machine and the use of a DC motor for driving a fan.