Bidirectional DC-DC Converter with Dynamic Transformer Turn Ratio

The patent applies dynamics by making the transformer turn ratio adjustable based on the direction of power supply. The transformer includes a primary winding and secondary winding whose effective connection is dynamically changed through switching elements (transistors) controlled by a control circuit. When charging, the transformer operates with a first turn ratio; when discharging, it operates with a second turn ratio. This dynamic adjustment allows the transformer to maintain optimal voltage transformation ratios for different operating conditions without requiring multiple fixed transformers, thereby reducing overall size and cost while maintaining reliability.

The patent uses a single transformer with dynamically adjustable turn ratio instead of multiple transformers with fixed ratios. The switching elements and control circuit enable the same physical transformer to operate at different effective turn ratios depending on whether the battery is charging or discharging. This approach reduces manufacturing cost by eliminating the need for multiple transformers while maintaining the power conversion capability required for reliable operation in both directions.

The patent dynamically adjusts the transformer turn ratio to match the operating conditions. During charging, when the battery voltage is lower, the transformer operates with a higher turn ratio to step down the voltage appropriately. During discharging, when the battery voltage is higher, the transformer operates with a lower turn ratio. This dynamic adjustment ensures the transformer operates at or near its maximum efficiency point in both directions, minimizing power losses. The switching elements and control circuit enable this adaptation without requiring a complex variable structure, as the same physical transformer is simply operated at different effective ratios.

The patent combines a physically fixed transformer structure with dynamically controllable switching elements. The transformer itself maintains a fixed physical configuration, but the effective turn ratio is dynamically adjusted by controlling which windings are connected to the circuit through switching elements. This approach achieves voltage range adaptability for both charging and discharging operations while keeping the physical transformer size compact and cost-effective. The control circuit monitors the operating mode and adjusts the switching element states to provide the appropriate effective turn ratio.