A simulation method for analyzing saliencies with respect to enhanced INFORM-capability for sensorless control of PM motors in the low speed range including standstill

In many drive applications, the so called "sensorless" control of permanent magnet synchronous machines (PMSM) has got increasing importance with respect to reduced costs and increased reliability. The position estimation based on back-EMF in the high speed range is already state of the art. In the low speed range there are different approaches for measuring and evaluating inherent saliencies, caused by saturation due to permanent magnets, stator current and rotor geometry. A type test of the PMSM is necessary for specifying the capability of sensorless angular position detection and control at low speed and standstill. However, a prediction based on simulation would support the construction process of the PMSM considerably. Hence, in this paper, a simulation method that yields information about the "INFORM-capability" of the PMSM is introduced. The correspondence between the simulation strategy and the sensorless measurement sequence is explained in detail. The result is a simulation method, that yields an a priori information about the ability for sensorless control in the low speed range and thus is a useful tool for PMSMs that are still under construction and shall be used in sensorless applications. The method is verified on an external rotor PMSM with surface-mounted magnets