An Optimized Loss‐Balancing Modulation Strategy for ANPC‐3L Inverter

ABSTRACT In existing modulation strategies for active neutral‐point‐clamped three‐level (ANPC‐3L) inverters, high‐frequency and low‐frequency switches are separated, with loss mainly concentrated in some fixed high‐frequency operating switches, resulting in uneven loss distribution across switches among bridge arms. To address these issues, a loss‐balance optimization modulation strategy is proposed. In this paper, the loss distribution of power switches under different commutation paths is analysed, and a loss‐estimation model for switches is established based on the characteristics of power switches to quantify the total losses. Aimed at loss balancing for all power switches, the switching modes (commutation paths) in the modulation process are automatically selected by the proposed strategy, achieving relatively balanced losses among all switches. Experiments are carried out with an 18 kW three‐phase ANPC‐3L inverter. Compared with existing loss‐balance strategies, the proposed strategy shows better loss (temperature) balance performance and almost equal efficiency.