Patent ID: 7852035
Filing Date: 2010-12-14
Classification: H02P

Abstract:
1. A motor drive circuit for current-driving a motor by PWM pulse generated by reading waveform data composed of a plurality of data and approximated to a sine wave for a predetermined period stored in a memory, comprising: an address counter; a polarity inverted data generator circuit for generating data having polarity inverted from positive to negative or from negative to positive; and a PWM pulse generator circuit for generating the PWM pulse, wherein the predetermined period is a half period, said address counter has digits the number of which is larger than the number of bits of an access address storing the waveform data of said memory by one bit or more, a certain bit of the one bit or more in the bit positions of said address counter is used as a flag bit or flag bits for inverting a polarity of the waveform data from positive to negative or from negative to positive, and the polarity inverted data generator circuit responds to the data read out from the memory and the flag bit or bits and generates the data having polarity inverted from positive to negative or negative to positive according to a value or values of the flag bit or flag bits, whereby a waveform data corresponding to one period of the sine wave is obtained by producing the waveform data for a half period read out from said memory.