A Novel Flexible Power Control for Three-Phase Buck Rectifier Under Unbalanced Grid Voltages and Wide Grid Frequency

For the three-phase pulsewidth modulation rectifiers under unbalanced grid voltages, flexible power control is often utilized to realize multiple control objectives, e.g., constant active power control, constant reactive power control, or balanced input currents control. However, in more electric aircraft application, it is difficult to apply flexible power control because of its wide variation of grid frequency from 360 Hz to 800 Hz. In this article, a novel flexible power control is proposed for the three-phase buck rectifier under unbalanced grid voltages and wide grid frequency. The input current references are constructed by detecting the amplitudes of the grid voltages in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">αβ</i> frame. In addition, a parameter is adjusted to regulate the oscillating power between active power and reactive power to achieve flexible power control. The proposed control strategy can be implemented without phase-lock loop. It is thus suitable for the application under wide variation of grid frequency. Simulation and experimental results are provided to verify the effectiveness of the proposed control strategy.