This paper presents a single-phase bidirectional isolated AC-DC converter with Power Factor Correction (PFC) consisting of a half-bridge on the AC side and a full-bridge on the DC side to accomplish single-stage power conversion. The converter applies a new control scheme combining phase-shift and frequency modulation to achieve Zero-Voltage-Switching (ZVS) over the full range of the AC line voltage. Compared to the conventional boost PFC approach, the proposed converter eliminates high frequency harmonic distortions on the mains due to the inherently integrated LC input filter stage. The operating principle in AC-to-DC and DC-to-AC under ZVS conditions by means of analytical considerations are provided. Simulation results and a detailed loss model of a 3.3 kW electric vehicle battery charger to connect to the 230 Vrms / 50 Hz mains considering a battery voltage range of 280 V to 430 V validate the theoretical analysis. The converter can also be used as a submodule in a Cascaded H-Bridge Converter (CHB) for medium or high voltage applications.

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The paper presents a novel modeling approach of the power flow in a bidirectional dual active bridge DC-DC converter. By using basic superposition principles, the mathematical distinction of cases is avoided in the modeling process of highfrequency transformer currents for different types of modulation. The generalized model is used in an optimization of converter losses of a 3.3 kW electric vehicle battery charger with an input voltage of 400 V and a battery voltage range of 280 V to 420 V. Besides the commonly used control variables such as phase-shift and clamping intervals, also the variation of switching frequency is considered in the optimization process. The optimal modulation including frequency variation leads to an increase of converter efficiency up to 8.6 % using IGBTs and 17.8 % using MOSFETs in the most critical point compared to phase-shift modulation at fixed switching frequency.

The paper presents a novel modeling approach of the power flow in a bidirectional dual active bridge DC-DC converter. By using basic superposition principles, the mathematical distinction of cases is avoided in the modeling process of the high-frequency transformer currents for different types of modulation. The generalized model is used in the optimization of the converter losses of a 3.3 kW electric vehicle battery charger with an input voltage of 400 V and a battery voltage range from 280 V to 420 V. Besides the commonly used control variables such as the phase-shift and the clamping intervals, the variation in the switching frequency is also considered in the optimization process. The optimal modulation including the frequency variation leads to an increase in the converter efficiency up to 8.6% using IGBTs and 17.8% using MOSFETs at the most critical point compared to phase-shift modulation at a fixed switching frequency.

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