This letter studies and implements a high-efficiency LiFePO 4 battery charger. The modular design can satisfy the requirements of series/parallel charging for electric vehicle applications. A CC-CC-CV charging scheme is also realized to meet the characteristics of LiFePO 4 battery stacks. A 2 kW laboratory prototype is built and tested. The experimental results are shown to verify the feasibility of the proposed scheme.

In this study, a buck power factor corrector (PFC) with gallium nitride field effect transistor (GaN FET) and integrated inductor is studied. An interleaved constant-frequency clamped-current control method is adopted to achieve high power factor, low input and output current ripples as well as high efficiency. Two inductors in the studied interleaved buck PFC are integrated to reduce the core loss. A 300 W/80 V laboratory prototype with 300 kHz switching frequency was built and tested under universal input voltage conditions. Experimental results are shown to verify the performance of the studied converter. According to the experimental verifications, the efficiency can reach higher than 95% from 10 to 100% load variations at 115 V input. The measured input current harmonic can meet with the IEC 61000-3-2 Class D standard.

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This paper provides a new signal compensation method for digital inverters, which is aimed at improving the voltage source inverter. Because of the non‐ideal characteristics of components of the inverter (e.g., metal oxide semiconductor field‐effect transistor module), the output voltage is unequal at positive and negative half cycles. This will result in inductive load saturation, and the switches will be damaged. The method proposed in this paper utilizes a combination of pulse signal and reference signal for adjusting the height and the width of pulse signal, with small direct current offset compensated by the average voltage of the signal. This method can also be adopted in a built‐in, low‐resolution pulse width modulation digital controller, which has advantages such as automatic compensation of output voltage and low cost. Copyright © 2012 John Wiley & Sons, Ltd.

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