Heatsink‐less MMC Active Power Filter Using Low‐Voltage Si‐MOSFETs for Air Conditioner Applications

ABSTRACT This article presents a design methodology for low‐voltage converters and an associated cooling structure necessary for applying a modular multilevel converter (MMC)‐based active power filter (APF) using low‐voltage Si‐MOSFETs, specifically for inverter‐driven air conditioners. The voltage detection circuit is simplified by referencing the MMC neutral point, eliminating voltage concentration on specific cells during APF shutdown. The proposed MMC‐APF comprises 36 low‐voltage Si‐MOSFETs, each with an on‐resistance of several mΩ, effectively distributing heat generation and limiting power loss to less than 1W per device. By utilizing airflow from the air conditioner's outdoor unit fan, the system operates without additional heatsinks or cooling fans. Experimental results confirm that the proposed MMC‐APF achieves purely sinusoidal source currents with a unity power factor, while reducing total loss by 38.6% compared to a conventional two‐level IGBT‐based APF.