Patent ID: 6188187
Filing Date: 2001-02-13
Classification: H02P,Y10S

Abstract:
A voltage-feedback control circuit for regulating the rotational speed of a DC brushless motor having at least one input terminal, and a motor winding electrically coupled to the at least one input terminal, the voltage-feedback control circuit comprising:an electrical conduction switch having an input, an output and a control terminal for passing a motor supply signal to the DC brushless motor from a voltage across first and second terminals of a DC voltage source, the input terminal of the switch being coupled to the first terminal of the DC voltage source, and the output terminal of the switch being coupled to the at least one input terminal of the motor and defining a substantially inductorless connection therebetween to thereby allow the motor windings to serve as an inductive filter to smooth changes in the motor current;a differential (error) amplifier having first and second input terminals and an output terminal for generating a differential signal having a voltage level indicative of the difference between a voltage level corresponding to the motor supply signal and a reference voltage, the first input terminal of the differential amplifier being coupled to a voltage reference, and the second input terminal of the differential amplifier being coupled to the output terminal of the switch; anda pulse-width modulator (pwm) having an input terminal and an output terminal, the input terminal of the pwm being coupled to the output terminal of the differential amplifier and the output terminal of the pwm being coupled to the control terminal of the switch, such that the pwm generates a modulator signal having a pulse width indicative of the voltage level of the differential signal to turn the switch on and off to modulate the motor supply signal and generate a substantially constant selected voltage level to the motor supply signal.