Research on Full Digital Control High-voltage Direct Current LLC Power Supply for Rail Transit Based on Domestic Embedded Chips

Abstract

Objective High-efficiency LLC (logic link control of) topology high-voltage direct current power supplies are widely used in the field of rail transit. However, due to the variable frequency control characteristics of LLC circuits, achieving full digitalization is challenging, and research on domestication lags behind. Thus it is necessary to carry out relevant research. Method Based on the HPM6300 series of full digital control LLC high-voltage power supply circuits from Shanghai Xianji Semiconductor Technology Co., Ltd. (hereinafter referred to as 'Xianji'), an analysis is conducted using the primary harmonic approximation method to establish a circuit model. The control flow of the circuit system program is analyzed. Experimental verification is performed by constructing a prototype with a power of 1.5 kW. Result & Conclusion The experimental results confirm that using the domestic Xianji embedded control chip HPM6300 MCU to build an LLC test prototype, and through PFM+PWM hybrid control, wide-range input can be achieved, and voltage output can be quickly stabilized. Different control methods can be adopted in the future, to achieve wide-range input with structural changes.

Keywords

• rail transit
• high-voltage dc power supply
• llc resonant converter
• primary harmonic approximation method