Patent ID: 7102327
Filing Date: 2006-09-05
Classification: G01R,H02M,H02P

Abstract:
1. A method for reconstructing motor phase current from a DC bus current on a DC bus in a PWM inverter motor drive system and for controlling the motor, comprising: forming a command voltage vector according to a space vector modulation arrangement for controlling the motor; measuring the DC bus current on the DC bus supplying power to the inverter to obtain an indication of motor current; determining when the command voltage vector results in an inverter switching state that prevents the measuring of the DC bus current from accurately indicating motor phase current; switching the PWM inverter motor drive system from three phase modulation to two phase modulation to reduce the minimum pulse clamping produced by the PWM inverter motor drive system thereby allowing dc bus current measurement with reduced acoustic noise and torque ripples; forming a voltage vector sum from two additive vectors, the vector sum being substantially the same as the command voltage vector, wherein at least one of the additive vectors represents a switching state permitting the measuring of the DC bus current to indicate motor phase current; applying at least one of the additive vectors to the space vector modulation in a first switching cycle of the PWM inverter drive system wherein a switchin cycle is defined by the PWM period of the PWM inverter motor drive system; and applying the other additive vector to the space vector modulation in a second switching cycle of the PWM inverter drive system, such that the time average of the additive vectors is equivalent to the command voltage vector thereby to compensate for a voltage error introduced by the at least one vector that permits the measuring of the DC bus current to indicate motor phase current.