Discontinuous modulated model predictive control for low inductance high-speed electric drive applications

Abstract

The performance improvement of high-power density electric machines with low inductance values for high-speed applications is still under investigation. The low inductance characteristics present higher harmonics and poor dynamic performance while applying the conventional control methods in the current loop. Modulated model predictive control (M2PC) with higher dynamics performance is a promising solution, which has been successfully applied to different applications including electric drive applications. However, the M2PC control of a machine with low inductance has not been fully investigated. Besides, the power converter operation can be improved through the implementation of certain switching patterns including discontinuous pulsewidth modulation (DPWM). So, a new strategy is proposed through the implementation of the M2PC controller based on the DPWM for low inductance electric machines. The presence of the modulator reduces the harmonic content while still maintaining the fast dynamic response of the M2PC. Also, the DPWM will provide higher voltage utilization, lower switching losses, and more potential to increase the switching frequency for a wide range of operating conditions. The proposed strategy has been applied successfully to a low inductance drive system as a case study with direct and quadrature axis inductances of 74 μH. The system has been tested and results have been demonstrated.