[Objective] Aiming at the issue of power device junction temperature fluctuations and lifetime degradation caused by half-cycle modulation in high-power doubly-fed wind power converters with three-level topologies under low-frequency operating conditions

this paper proposes an operational state-aware and performance-optimized switching control method between three-level active neutral-point-clamped (ANPC) and neutral-point-clamped (NPC) modes. [Methods] A frequency-adaptive dynamic topology switching technique was employed

where the ANPC topology was activated in the high-frequency range to reduce switching losses

while a switch to the NPC topology was implemented in the low-frequency range to suppress diode conduction losses. This approach was validated through high-fidelity simulation and a physical prototype platform. [Results] Experimental results demonstrated that the proposed control method exhibited significant advantages during the operation of the doubly-fed three-level converter

with particularly outstanding effectiveness in suppressing diode junction temperature fluctuations. By dynamically matching the optimal topology to the rotor frequency

the loss distribution of the converter’s power devices was rendered more rational

and the fluctuation amplitude of the diode junction temperature was effectively reduced over a wide frequency range. [Conclusion] The proposed method effectively balances system control performance and device reliability

thus providing a viable and novel approach for the design of low-frequency control strategies in doubly-fed three-level converters.