| 摘要 |
PROBLEM TO BE SOLVED: To improve calculation accuracy of a current estimation value obtained by a system that uses a detected value of a current sensor detecting current flowing in one phase among all phases of an AC motor and calculates the current estimation value of other phases on the basis of the detected value.SOLUTION: A sensor-phase referenced current phase detection unit 18 calculates α-axis current iα and &bgr;-axis current i&bgr; in a fixed coordinate system (α-&bgr; coordinate system) referencing a sensor phase (W phase). In the process, the α-axis current iα is calculated on the basis of a current detection value iw.sns of the sensor phase, while the &bgr;-axis current i&bgr; is calculated on the basis of a current command value iv* of the other phase (V phase) obtained by d-axis and q-axis current command values id* and iq* and the current detection value iw.sns of the sensor phase. Then, a sensor-phase referenced current phase x&thetas;=tan(i&bgr;/iα) is calculated on the basis of the α-axis current iα and the &bgr;-axis current i&bgr;. After this, at a fundamental wave estimation unit 19, an estimation coefficient corresponding to the sensor-phase referenced current phase x&thetas; is calculated, and a current estimation value iu.est of the other phase (U phase) is obtained by multiplying the estimation coefficient by the current detection value iw.sns of the sensor phase. |
