Patent ID: 6642690
Filing Date: 2003-11-04
Classification: H02M,H02P

Abstract:
A method for measuring current of each phase for an inverter control apparatus comprising a converter for converting alternating current from a three-phase alternating current power source into direct current, an inverter provided with a pair of switching devices in each phase, the inverter for converting direct current from the converter into alternating current and providing the alternating current to a three-phase induction motor, single current sensor for measuring current of a phase, which flows through the motor, an analog-to digital (A/D) converter for converting an analog measured value of current, which is measured by the current sensor, into a digital measured value, and an inverter controller for generating a reference voltage of each phase and a pulse width modulation (PWM) signal using a triangle wave on the basis of the digital measured value from the analog digital converter, to thus control switching of the switching device of each phase, the method comprising the steps of:(a) changing the reference voltages of arbitrary two phases in one cycle of the triangle wave; (b) measuring current of each phase for the one cycle of the triangle wave using the current sensor; and (c) compensating for the amount of change in the reference voltages of the two phases in the one cycle of the triangle wave.