Hybrid mode‐hopping modulation for LLC resonant converter achieving high efficiency and linear behaviour

Abstract

Frequency modulation (FM) has been widely used in the inductor-inductor-capacitor (LLC) resonant converter due to excellent soft switching features. However, low power efficiency in light load conditions and complex control due to the nonlinear converter behaviour are common concerns for the FM method. In this study, a hybrid mode-hopping modulation method is proposed for the LLC resonant converter to address these challenges. The LLC resonant converter operates at any two of three power-efficient operating modes for a different amount of time within a single modulation period. By determining the mode hopping time and combining different mode-hopping modulations, the LLC resonant converter can achieve a wide range of output power and maintain high efficiency at the same time. Besides, since the switching frequencies are fixed, the relationships between the duty cycle and the output power are linear, which can significantly simplify the control design. Compared with the existing modulation methods, the proposed hybrid mode-hopping modulation makes the LLC resonant converter behaves linear, simplifies the control design, achieves wide operation range and ensures high efficiency even in light load condition.

Inserted-Shunt Integrated Planar Transformer With Low Secondary Leakage Inductance for LLC Resonant Converters

“…This work was supported by the Engineering and Physical Sciences Research Council (EPSRC) under grant EP/S031421/1. inductances of the LLC tank [8][9][10]. Integrating magnetic components of an LLC converter into a single magnetic device enhances the power density and efficiency.…”

Fully-Integrated Transformer With Asymmetric Primary and Secondary Leakage Inductances for a Bidirectional Resonant Converter

“…Resonant converters can provide high efficiency and power density at a low cost since they benefit from soft-switching capability and magnetic integration. Therefore, resonant converters are becoming desirable for dc-dc applications like ESSs [8][9][10].…”

Super Twisting Sliding Mode Control Strategy for Input Series Output Parallel Converters

“…Similar to these topologies, an isolated topology based on the current source converter is presented in [8]. Compared to LLC and DAB, the key advantage of this topology is the small-size capacitor requirement [8]- [10].…”