Patent ID: 6396225
Filing Date: 2002-05-28
Classification: H02P

Abstract:
A DC brushless motor driving apparatus, comprising: a driver portion for generating inverter driving signals; an inverter being connected with six semiconductor switching elements in a three phase bridge, and for producing motor driving signals to be supplied to the stator windings of the DC brushless motor by driving said semiconductor switching elements with said inverter driving signals; and a plurality of comparators, each for comparing a motor terminal voltage across each phase of the stator windings of said DC brushless motor to a reference voltage of a DC power source voltage of said inverter, wherein said inverter driving signals include a PWM signal which is used to control any one of said semiconductor switching elements of said inverter to chop the motor driving signals in each turn-on interval of said DC brushless motor, and said driver portion detects levels of position detecting signals which are outputted from said comparators upon basis of timings of said inverter driving signals, thereby setting commutation timings for exchanging the turn-on intervals of said DC brushless motor depending upon the detection result thereof, wherein, there is further provided means for making a frequency of said PWM signals variable.