| 摘要 |
<P>PROBLEM TO BE SOLVED: To carry out appropriate sine wave driving according to a rotor position. <P>SOLUTION: A back electromotive force detection circuit 20 compares a phase voltage Vu of a coil Lu with a neutral point voltage Vcom to detect a zero-cross point, and outputs a back electromotive force detection signal BEMF_EDGE. A pulse signal generation circuit 42 generates a pulse signal PULSE whose frequency is n (n is an integer not smaller than 2) times that of the back electromotive force detection signal in synchronization with the back electromotive force detection signal BEMF_EDGE. A sinusoidal signal generation circuit 70 outputs a sinusoidal control signal CNT according to the pulse signal PULSE. A PWM signal generation circuit 80 synthesizes the control signal CNT with a torque signal Strq to generate a pulse width-modulated signal Spwm. A switching control circuit 30 controls the sequence of a switching circuit 10 based on the back electromotive force detection signal BEMF_EDGE, and further controls the switching of a switch included in the switching circuit 10 based on the PWM signal Spwm. <P>COPYRIGHT: (C)2008,JPO&INPIT |
