Magnetic pole position estimating method and control apparatus for synchronous motor

摘要

The invention has an object to provide a magnetic pole position estimating method and a control apparatus for a synchronous motor which reliably detect the position of a magnetic pole of the synchronous motor to carry out stable control also when a high load is applied or a load is suddenly changed. A coordinate transformer (8) transforms a detected current value is into an impedance observation axis positioned in a place shifted from an estimated magnetic pole position theta by 45 degrees. A high-frequency impedance estimator (10) estimates high-frequency impedances Zdm and Zqm on two points which are advanced and delayed by an electrical angle of 45 degrees from a gamma-axis. A first magnetic pole position estimator (13) estimates a first magnetic pole position estimated value theta to eliminate a deviation between the high-frequency impedances Zdm and Zqm. A second magnetic pole position estimator (14) inputs a current command value idelta* to estimate an internal phase angle compensating angle thetar and subtracts the internal phase angle compensating angle thetar from the first magnetic pole position estimated value theta, and outputs a second magnetic pole position thetac.