A Variable Frequency Phase-Shift Modulation Constant Power Control Strategy for LCC Resonant Capacitor Charging Power Supply

Abstract

This article develops the constant power control technology of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> resonant capacitor charging power supply (CCPS) to accelerate the charging speed and use the full capacity of the device at the same time. For the constant power control of the CCPS, variable frequency modulation works in a wide frequency range with large reactive power, and phase-shift modulation (PSM) cannot work with a wide gain range. Therefore, a variable frequency (VF)-PSM constant power control strategy is proposed in this article, which achieves high utilization of transformer and high efficiency of power supply system. Based on state plane analysis, the analytical expressions in different operating modes are derived for the ZVS boundary and the multidimensional relationship between power, output voltage, frequency, and phase-shift angle. Accordingly, a control trajectory of the phase-shift angle and frequency in gain-power plane is calculated. Thus, the problems caused by using the current with large harmonic components to calculate the output power in real time are avoided and the control is simple and accurate. Finally, a 500 W, 1 kV charging experiment was conducted to verify the effectiveness of the VF-PSM constant power control strategy and the feasibility of phase-shift angle and frequency trajectory control in gain-power plane.