Efficient Bidirectional DC-DC Converter using Digital Adaptive Frequency Modulation

A digital adaptive frequency modulated bidirectional dc-dc converter is introduced for an efficient and reliable energy management system. The proposed system achieves zero voltage switching (ZVS) without an additional zero-crossing detector (ZCD) circuit. To achieve the ZVS condition, frequency is calculated adaptively in every cycle. As this method does not involve a ZCD circuit, it can be easily retrofitted to any circuit configuration. The proposed system satisfies the ZVS condition for a wide range of voltage (Battery voltage 12V-24V & Bus voltage 28V-36V) and load variations. The proposed digital adaptive frequency control is validated in an interleaved bidirectional dc-dc converter topology. The interleaving technique reduces the effective conduction loss and current ripple, thus increasing the converter performance and overall efficiency. A 200W interleaved bidirectional dc-dc converter for battery charging/discharging is designed and digital adaptive frequency control is validated in a MATLAB/Simulink platform. The results are encouraging.