A novel hybrid seven-level converter for permanent magnet synchronous motor driving system based on model predictive control

A novel hybrid three-phase seven-level converter is proposed in the paper. Each phase consists of a four-level bridge and a two-level H bridge, which contains ten switching devices and a floating capacitor. The circuit structure is introduced and working principle of the converter containing 14 commutation paths is analyzed, which is easy to control the floating capacitor voltage. In order to drive permanent magnet synchronous motor (PMSM) with the proposed converter, model predictive control (MPC) strategy is adopted. The control objectives such as controlling the currents of PMSM and capacitor voltages balancing are included in a cost function with two weight factors, which can control the currents of PMSM and balance the capacitor voltages simultaneously. To validate the proposed control scheme, simulations in two cases are carried out by using Matlab/Simulink software. Finally, the feasibility and efficiency in two cases are verified with the experimental test bench based on RT_LAB.