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This paper presents a 100kW one-cell switched-tank converter (STC) for electric vehicle (EV) application. A new evaluation method that evaluates different converter topologies has been proposed in this paper to show the advantages of the STC over the boost converter and 3-level flying capacitor multilevel (FCML) converter. Both non-interleaved (1-phase) and interleaved (2-phase and 3-phase) operation of the STC have been analyzed. The analytical study shows that it is difficult to achieve the optimum design of the passive components such as input and output capacitors in 1-phase converter because of the high RMS current flowing through them. This means the passive components need to be over-designed in order to meet the current stress requirement. For instance, the designed capacitance of input capacitor is several times of the required value, which leads to bulky capacitor size. Therefore, this paper evaluates the potentials of using 2-phase and 3-phase interleaved operation to address this issue. Two operation modes, zero-voltage switching (ZVS) mode and zero-current switching (ZCS) mode, are evaluated to show the ZCS operation mode is more suitable for the presented converter with interleaved operation. By using the interleaving concept, the predicted 100kW 3-phase interleaved converter can achieve 60% size reduction based on the 1-phase converter design. And the predicted power density of the 3-phase interleaved STC can achieve 115kW/L power density. Simulation results are provided to validate the theoretical analysis. Both 1-phase and 3-phase 100kW prototypes under developing are shown in this paper.

A new Switched Tank Converter (STC) with Partial Power Voltage Regulation (PPVR) is introduced for electric vehicle applications. It offers a flexibly adjustable conversion ratio for a wide-range battery voltage. The unregulated stage is modularized with resonant switched capacitor converters. All device voltage stresses are equal to the input voltage. The efficient unregulated stage processes the bulk of system power and the less efficient regulated stage processes a small amount of power. Thus, high overall efficiency can be achieved. A new index called Semiconductor Loss Index (SLI) is defined as a function of semiconductor die area to evaluate different power topologies. It is helpful to analyze the impact of each switch die area, different operated output power, switching frequency, and conversion ratio on the total device power loss. With the same total semiconductor die area, the proposed converter can achieve less than 1/3 device total power loss compared with boost converter. A 4-kW 1200V output converter prototype with 200V~400V input voltage range is developed, which combines a 6 times conversion ratio STC with a PPVR buck converter. The overall full-load efficiency of designed 4-kW converter can reach to 97.71%. Simulation, prototype and experiment results are presented to verify the validity of the proposed converter.