Air blower equipped with brushless dc motor

Abstract

Air blower equipped with a brushless DC motor includes an inverter circuit, a drive logic controller, a duty indicator, a motor voltage detector, a motor current detector, and a correlation detector. A duty indicating value of the duty indicator is determined according to a value of the correlation detector.

1 . An air blower equipped with a brushless DC motor comprising:
 an inverter circuit including a plurality of upper stage side switching elements and a plurality of lower stage side switching elements connected to form a bridge;   a drive logic controller configured to perform PWM control of the upper stage side switching elements or the lower stage side switching elements, and control a DC voltage applied to the inverter circuit by energizing driving coils of the brushless DC motor sequentially in a specified direction and order;   a duty indicator configured to indicate ON/OFF duty of the PWM control;   a motor voltage detector configured to detect a voltage applied to the driving coils;   a motor current detector configured to detect a current flowing through the driving coils; and   a correlation detector configured to compare an output value of the motor voltage detector with an output value of the motor current detector,   wherein a duty indicating value of the duty indicator is determined according to a value of the correlation detector.   
     
     
         2 . The air blower equipped with a brushless DC motor according to  claim 1 ,
 wherein the motor current detector is replaced by a circuit current detector configured to detect a current of the inverter circuit.