Model predictive control of a hybrid stacked multicell converter with voltage balancing and fault tolerance capability

Abstract

Due to the merits of low conduction losses and superior output power quality, a hybrid stacked multicell converter (HSMC) was put forward as a competitive alternative in the medium/low-voltage high-efficiency applications. A nine-level HSMC (9L-HSMC) can be seen as a combination of a five-level SMC (5L-SMC) and two-level half-bridge, and proper modulation and control strategy are essential for the HSMC to obtain the optimal output performance. This work develops a finite control-set model predictive control (MPC) strategy for 9L-HSMC to balance the capacitor voltages and maintain the desired outputs, rendering the absence of the linear regulator and pulse width modulation (PWM) modulator possible. The fault-tolerant operation can also be achieved flexibly when open-circuit faults occur at active bidirectional switches in the 5L-SMC bridge, and the performance is verified by simulations. Finally, experiments under several typical operating conditions are implemented to verify the effectiveness of 9L-HSMC with the developed MPC strategy.