An Innovative Synchronous Rectification Method for 11 kW CLLC Converteronverters

Abstract:
Nowadays, CLLC topology was used widely in the bidirectional power electronic systems such as EV chargers, energy storages, on board chargers (OBC), and vehicle-to-grid (V2G) charger stations, due to a high efficiency, low electromagnetic interference (EMI), bi-directional capability, and a high-power density. However, a synchronous rectification control is not used widely because it can complicate a control system. As a result, the system performance is lower when it comes to efficiency and thermal behavior, especially when silicon carbide (SiC) MOSFETs are used in a converter. An innovative synchronous rectification method is introduced in this paper. In this method, the secondary-side synchronous rectification PWM signal is generated by the CLLC oscillation cavity current, the primary-side PWM signal and the system power. Results of a test on a 11 kW CLLC DC-DC converter show that this synchronous rectification method can increase the entire system efficiency from 97.1% to 98.1%. This rise can benefit the whole system and have a positive impact on the applications.