Patent ID: 9450528
Filing Date: 2016-09-20
CPC Classification: H02P

Claim Text:
1. A sensorless control apparatus for a synchronous motor, comprising: a current controller which is input with current commands and current responses, and which outputs voltage commands; a voltage-command coordinate converter which performs coordinate conversion on the voltage commands based on an estimated phase angle to obtain three-phase voltage commands; a PWM processing unit which pulse-width-modulates each three-phase voltage command, based on comparison between the three-phase voltage command and a PWM carrier, and thereby generates a gate command for an inverter; a high-frequency voltage calculator which obtains a plurality of high-frequency voltage components by calculating an applying voltage value applied to the synchronous motor from the inverter using an output signal of the PWM processing unit, and calculating sine components and cosine components of a plurality of frequencies not lower than a carrier frequency of the PWM carrier included in the applying voltage value; a high-frequency current calculator which obtains a plurality of high-frequency current components by calculating said sine components and cosine components of the plurality of frequencies not lower than the carrier frequency, wherein said plurality of high-frequency voltage components are included in a current response value from the synchronous motor driven by the inverter; and an estimated angle calculator which calculates the estimated phase angle indicative of an estimated value of an angle of rotation of the synchronous motor, based on two pairs selected from a plurality of pairs each including the high-frequency voltage component and the high-frequency current component each of which includes a cosine component and a sine component at an equal frequency, wherein one of the selected high-frequency voltage components has a greatest absolute value and another one of the selected high-frequency voltage components has greatest components in a direction perpendicular to the one of the selected high-frequency voltage components.