Patent ID: 9209723
Filing Date: 2015-12-08
Classification: H02P

Abstract:
1. A control device of a three-phase AC motor comprising: an inverter that drives the AC motor; a current sensor that senses a current flowing through a sensor phase of the AC motor; and a controller that includes a current estimation device, wherein the current estimation device calculates a current phase based on the sensor phase, which is defined as a sensor-phase-standard current phase, according to an α axis current and a β axis current in a fixed coordinate system, wherein the fixed coordinate system is set by an α axis and a β axis, wherein the α axis is in a same direction as an axis of the sensor phase, wherein the β axis is orthogonal to the axis of the sensor phase, wherein the current estimation device calculates a current estimated value of another phase other than the sensor phase according to the sensor-phase-standard current phase and a current sensed value of the sensor phase, wherein the current sensed value of the sensor phase is sensed by the current sensor, wherein the controller switches on and off a switching element of each phase of the inverter so as to control a current flowing through the AC motor, wherein the current estimation device includes: wherein the second calculator calculates the β axis current according to the first differential value of the α axis current, wherein the second calculator calculates a second differential value of the α axis current at every intermediate timing according to a change amount of the α axis current between a present intermediate timing and a previous intermediate timing, wherein the second calculator calculates the β axis current according to the second differential value of the α axis current, and wherein the intermediate timing is set to have an unequal interval between two adjacent switch timings.