APPARATUS AND METHOD FOR COMPENSATING REFERENCE VOLTAGE IN BLDC MOTOR CONTROL SYSTEM

摘要

The present invention relates to an apparatus and a method for correcting a reference voltage used for determining a zero-crossing point of counter-electromotive force in a BLDC motor control system using a sensor-less control technique. According to the present invention, the apparatus for correcting a reference voltage includes an A/D converter and a control part. The A/D converter measures a DC voltage applied to an inverter part, and also measures a counter-electromotive force signal induced to the stator of a BLDC motor. The control part performs the following procedures: defining a half of the measured DC voltage as a reference voltage used for determining a zero-crossing point of counter-electromotive force (hereinafter referred to as reference voltage); calculating duty ratios of two sections covering zero-crossing points of each phase during a single cycle based on the reference voltage; and correcting the reference voltage by successively increasing or decreasing the reference voltage so as to make the duty ratios of the two sections become identical, if the duty ratios of the two sections are not identical. Accordingly, the present invention can locate the position of a rotor more accurately by correcting the error of a sensed reference voltage, thereby increasing the accuracy of motor control and therefore preventing the malfunction and performance degradation of the motor and avoiding system instability.