Inductance measurement method for permanent magnet synchronous motors using AC with DC bias

We have developed a method that uses AC with a DC bias to measure the inductances (L_d, L_q) of permanent magnet synchronous motors (PMSMs). Such motors are widely used in electrical equipment because they are highly efficient. Our method can be used to measure nonlinear characteristics of a PMSM, such as magnetic flux and inductance with cross-magnetization. We have compared our method with a conventional method and the results of a finite-element method analysis. The comparisons with the finite-element method analysis revealed that our method can be used to accurately determine the inductances of PMSMs, which is necessary in some vector control strategies.