CONTROL UNIT FOR BRUSHLESS DC MOTOR AND VENTILATION BLOWER

PROBLEM TO BE SOLVED: To provide a control unit which controls rotational speed by rotating a brushless DC motor used for a heat exchange type cooling unit used for cooling an apparatus by means of sensorless driving, capable of preventing variation in cycle and increase in motor current by keeping constant motor voltage output from an inverter circuit even when power source voltage rapidly changes, disabling overcurrent protection, restraining degradation in pole position detection accuracy of the brushless DC motor without causing motor stop due to out-of-step, and increasing the reliability of brushless DC motor driving. SOLUTION: This device has a voltage detecting means 15 for detecting power voltage value of a DC power supply 5. A PWM output means 12 ensures a constant motor voltage output from the inverter circuit 1 based on the power voltage value and the motor voltage value regardless of variations of the power voltage of the DC power supply 5. COPYRIGHT: (C)2008,JPO&INPIT