Patent ID: 8018184
Filing Date: 2011-09-13
Classification: H02P

Abstract:
1. A PWM control circuit that generates PWM signals based on an analog sensor output from a sensor provided in a device to be controlled, comprising: a polarity determination unit that judges positive polarity sections and negative polarity sections of the analog sensor output to generate a polarity signal; a full wave rectification unit that generates a full wave rectification signal by doing full rectification of the analog sensor output; an adjustment unit that generates an adjusted waveform signal by adjusting waveform of the full wave rectification signal; a carrier signal generating unit that generates a fixed frequency carrier signal; a comparator that generates an original PWM signal by comparing the adjusted waveform signal and the carrier signal; and a PWM waveform shaping unit that generates a first PWM signal for the positive polarity section and a second PWM signal for the negative polarity section, by shaping the original PWM signal according to the polarity signal.