| 摘要 |
<p>A conduction signal generation circuit (10) compares a counter electromotive voltage (Vu to Vw) generated in coils (50a to 50c) of each phase of a motor (50) to a middle point voltage (Vn) of each phase so as to generate conduction signals (Mu to Mw). A pulse signal generation circuit (20) generates a pulse signal (Vpulse) whose duty ratio is controlled according to the torque. An tilt signal generation circuit (30) divides cycle (Tp) of a frequency generation signal (SigFG) obtained by synthesizing conduction signals (Mu to Mw) into a plurality of parts and generates a tilt signal (Sslp) having a pulse width gradually changed and having a frequency identical to the pulse signal (Vpulse). An output circuit (14) supplies drive current to coils (50a to 50c) of each phase according to the conduction signals (Mu to Mw), the pulse signal (Vpulse), and the tilt signal (Sslp).</p> |
