Doubled-Frequency Triangular Current Mode Modulation With Sinusoidal Frequency Profile for a Three-Level ANPC Converter

Triangular current mode (TCM) modulation is a well-researched technique for optimizing the trade-off between converter power or gravimetric density and power efficiency. However, its application in multilevel AC-DC converters has been limited. This paper extends the TCM concept to a three-level active-neutral-point-clamped (3L-ANPC) converter and addresses key implementation challenges. First, two fundamental TCM commutation sequences are introduced. Building on these, a doubled-frequency TCM (DF-TCM) modulation method is proposed to offer additional benefits. A major drawback of conventional TCM is its complex switching frequency profile, which imposes significant computational burdens and can easily excite circuit resonance. To address this, this paper proposes replacing it with sinusoidal frequency profiles (SFP). Additionally, considerations for parameter design are discussed, and a model for semiconductor conduction losses is developed. Finally, a hardware prototype is constructed to validate the feasibility of the proposed DF-TCM strategy.