Transistor Temperature Balancing Method for Three-level Inverters Based on FCS-MPC

The there-level Neutral Point Clamped(3L-NPC) inverter is widely used in various applications. One of shortcoming in there-level NPC is the uneven temperature distribution caused by uneven power loss distribution. For this reason, this paper proposes a temperature balance control (TBC) method based on finite control set model predictive control (FCS-MPC) to improve the temperature distribution of inverters. Firstly, the evaluation function of the FCS-MPC is established, which includes current tracking, power tracking and current, power limiting. Based on the discrete model, a predicted value of the three-phase current and transistor power loss corresponding to all active switch states in the next sampling period is then calculated. Finally, in all the effective switch states, a switch state is selected, which corresponds to the smallest evaluation function value. The switch state will be used as the control signal for the next sampling period. The simulation results show that the proposed TBC method can not only balance the temperature distribution, but also has little effect on the system control performance.