Improved Model Predictive Control for Multimotor System Using Reduced-Switch-Count VSI With Current Minimization

A multimotor system supplied from the reduced-switch-count voltage source inverter (VSI) is considered in this article. First, an improved multiple vectors model predictive control (MV-MPC) scheme is proposed for driving n three-phase permanent magnet synchronous motors (PMSMs) by (2n + 1)-leg VSI. To realize independent control of multimotor, a control period is partitioned into multi-interval, one per motor. In the proposed MV-MPC scheme, the quasi-optimal voltage vectors (VVs) are selected to replace zero VVs under the restriction of identical common leg switching states. Thus, a whole control period can be fully utilized to generate multiple active VVs for a motor. Moreover, the overcurrent in the common leg is discussed and addressed. Take the five-leg VSI as an example, the expression of overcurrent in the common leg is first derived. Next, a general overcurrent elimination method based on current phase regulation is designed for the multimotor system operating at an identical speed. Finally, the proposed MV-MPC scheme combined with the overcurrent elimination strategy is experimentally carried out. The test results indicate that the MV-MPC method can effectively reduce current ripple and achieve a faster dynamic response. The overcurrent eliminationmethod can minimize the overcurrent regardless of the load conditions of the motors.

Automated summary

This article considers a multimotor system supplied by the reduced-switch-count voltage source inverter (VSI). An improved multiple vectors model predictive control (MV-MPC) scheme is proposed for driving n three-phase permanent magnet synchronous motors (PMSMs) using (2n + 1)-leg VSI. The proposed scheme allows independent control of each motor by partitioning the control period into multi-intervals. The experiment results demonstrate the effectiveness of the MV-MPC method in reducing current ripple and achieving a faster dynamic response, as well as the overcurrent elimination method in minimizing overcurrent regardless of motor load conditions.