Patent ID: 7245095
Filing Date: 2007-07-17
Classification: H02M,H02P

Abstract:
1. A control circuit of rotational speed of a fan, wherein a switching is performed by a multistage switch in a switch unit, which will in turn change a period of sampling pulse output by a PWM (Pulse Wide Modulation) unit; its characteristics being that by the sampling pulse provided from the PWM unit which is serially connected, a control unit will in turn perform a sampling action to an AC voltage, and then serve the voltage after sampling as a working voltage of a load unit; the working voltage being changed following a change in period of the sampling pulse, thereby enabling the load unit to efficiently achieve an effect of adjustment, wherein the switch unit is constituted by a multistage switch connected with a plurality of capacitors and inductors; various configuration of capacitors and inductors being selected by a switching of the multistage switch, so as to change the period of sampling pulse output by the PWM unit.