Enhanced Analytical Models Based on Switching Angles to Evaluate the Effects of Optimized Pulse Patterns on the Overall Electric Drive Train

Optimized pulse patterns (OPPs) can be used to improve overall drive train performance. Recently, they have been applied to minimize the current harmonics of salient permanent magnetic synchronous motors. Applying OPPs to the electrical drive train, may improve the efficiency, but may have a negative effect on the DC link capacitor or air gap torque ripple. In electric vehicle applications it is crucial to consider their effect on various parameters. Certain limits may be exceeded which restrict the use of OPPs at these operating points. Therefore, this article presents analytical models derived from switching angles in the context of synchronous modulation to directly evaluate the beneficial or detrimental effects associated with OPPs on the overall electric drive system. Since the model equations are based on switching angles, they are particularly suitable for pulse pattern optimization. Switching angles can be identified that minimize either current harmonics, switching losses, DC-ink voltage ripple, DC-link current stress, or the air-gap torque of the machine with respect to low frequency modulation. Measurements on a machine test bench are performed to validate the correctness of the presented models.