Patent ID: 8593094

Claim:
A power conversion apparatus of an electric vehicle, comprising: a power converter for driving an alternating-current rotating machine; and a control unit for controlling the power converter based on an operation command, the control unit including a coordinate conversion unit for converting current information detected from the alternating-current rotating machine into orthogonal axis currents on orthogonal rotating coordinates, a speed determination unit for computing a voltage command for the power converter and determining speed of the alternating-current rotating machine based on the operation command and the orthogonal axis currents, and a resistance computing unit for computing a sum of a primary resistance and a secondary resistance of the alternating-current rotating machine based on the orthogonal axis currents and the voltage command after the speed determination unit determines that the speed of the alternating-current rotating machine is zero and within a predetermined time after a point in time when the operation command is changed from a brake command to a power running command, and computing the primary resistance of the alternating-current rotating machine based on the orthogonal axis currents and the voltage command after a lapse of the predetermined time, the predetermined time being set to be shorter than a secondary time constant of the alternating-current rotating machine.