GaN-Based Megahertz Single-Phase Inverter With a Hybrid TCM Control Method for High Efficiency and High-Power Density
Teng Liu, Cai Chen, Ke Xu, Yi Zhang, Yong Kang
Abstract
Compared with traditional frequency limitation method DCM and QCFTCM for TCM-based inverter, this article proposes a hybrid TCM method, which can achieve both full range ZVS and frequency variation limitation. An accurate resonant transition model is established and the switching frequency variation range can be obtained for TCM. The hybrid control can be implemented according to the variation ratio γ. In order to determine the optimal γ, an offline optimization algorithm based on loss estimation is proposed. Therefore, an accurate analytical loss model for GaN HEMTs considering the nonlinear junction capacitance is given for TCM and hybrid TCM. The loss model shows that the total losses of hybrid TCM inverter are reduced compared with TCM. Moreover, an interleaved GaN-based megahertz single-phase inverter with digital control is demonstrated with 120 W/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> power density. The aforementioned benefits are experimentally verified in the optimal hybrid TCM. With this hybrid control, the measured peak efficiency is 98%. Compared with pure TCM mode, there is a 70% reduction in the switching frequency and the related efficiency is 0.8% higher at light loads. Higher power density (135 W/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ) can be achieved in hybrid TCM through further increasing the switching frequency compared with pure TCM.