PWM INVERTER DRIVE PERMANENT MAGNET TYPE SYNCHRONOUS MOTOR AND METHOD FOR CONTROLLING VENTILATION BLOWER

摘要

PROBLEM TO BE SOLVED: To obtain a small and inexpensive PWM inverter drive permanent magnet type synchronous motor that can accurately control motor generating torque and to obtain a method for controlling a ventilation blower.SOLUTION: At 12 and 14, motor current is made proportional to generated torque by making a phase difference between the phase of phase induction voltage indicated by a position sensor signal and the phase of motor current flowing through the motor coils closer to a target phase difference and nearly constant. At 11 and 9, DC bus current is detected at a shunt resistor inserted into the DC bus of a PWM inverter main circuit, and a motor current feedback value Imf is calculated in such a way that the average current of the DC bus obtained by averaging is divided by a modulation rate of 3 and a value corresponding to power factor of a synchronous motor and its result is multiplied by a coefficient. At 8, based on comparison of a motor current command value Im* and the motor current feedback value, adjusting output of a first voltage adjustment component (q-axis current command) makes the motor current close to the target value.