Resonant Voltage Divider With Bidirectional Operation and Startup Considered

In this paper, a resonant voltage divider (RVD) is presented with the fixed switching frequency and used as a bus converter. The proposed RVD without any control loop embedded can reach very high efficiency from the light load to the rated load, especially for the light load. In addition, the bidirectional operation of the RVD is taken into consideration, so the RVD not only can transfer energy to the voltage-regulated module (VRM) but also can reversely transfer the energy to the dc bus during the download transient period of the VRM. However, the RVD has a serious drawback that a large surge current at startup causes components to be saturated or destroyed. Consequently, how to reduce such a current based on the proposed variable switching frequency at startup is also taken into account. In this paper, the bidirectional operation of the RVD and how to suppress the startup surge current are illustrated in detail, along with some simulated and experimental results to demonstrate its effectiveness.