An offline optimization method for efficiency optimized operation of interior permanent magnet synchronous machines

Interior permanent magnet machines have several advantages compared to permanent magnet synchronous machines having the magnets on the rotor surface. The drawback is the quite more complex control structure for energy efficient and stable operation of this machines. In a prior work, some current control structures have been discussed assuming the energy optimized current setpoints to be given. In this work, the calculation of the setpoints is explained to achieve energy optimized operation of the IPMSM. The proposed method for calculating the setpoints uses an offline optimization method to derive matrices which easily could be implemented in a microcontroller as look-up tables. Comparing the proposed optimized current control to a non optimized current control for salient pole machines on a test bench, yields an energy efficiency improvement of up to 23% in the lower field weakening area.