Patent ID: 8610385
Filing Date: 2013-12-17
Classification: H02P

Abstract:
1. A motor driving circuit comprising: an inverter circuit which supplies a driving current to a coil of a single phase brushless DC motor; a position detection sensor which detects a magnetic pole position of a magnet rotor of the single phase brushless DC motor and outputs a position detection signal; and a controller which controls the inverter circuit based on the position detection signal and a speed instruction signal which is supplied from an external source for instructing a rotating speed of the single phase brushless DC motor, wherein at a time of startup of the single phase brushless DC motor, the controller makes a pulse width of a PWM signal for controlling the inverter circuit constant in a first time period which starts after the position detection signal zero-crosses and lasts until the position detection signal zero-crosses next time, and narrows the pulse width of the PWM signal as time elapses in a second time period immediately after the first time period, and wherein the controller comprises: