Determining electrical efficiency of permanent magnet synchronous machines with different control methods

An algorithm to calculate the electrical efficiency of permanent magnet synchronous machines with four different control methods is presented. The direct- and quadrature-axis stator current components are optimized to find the control method producing the maximum electrical efficiency. The developed computation algorithm was tested with three different permanent magnet synchronous machine applications, i.e., a low-speed high-torque direct-driven wind power generator with rotor surface magnets, a hybrid drive for an energy recovery system and a geared wind power generator with rotor buried magnets. The performance of the developed computation algorithm was verified by comparing the calculated electrical efficiencies with the measurements in the case of the hybrid drive machine.