Output Power Feedback Control Based on Triangular Inductor Current for DC-DC Converter Utilizing Singular Auxiliary Chopper Circuit

Abstract

This paper proposes an output power control circuit for a non-isolated DC-DC converter utilizing a single auxiliary chopper circuit intended for railway applications. Conventional auxiliary converters typically consist of a large number of power devices and require large inductors to suppress current ripple, which results in increased mass and volume. To address this problem, the proposed circuit uses a single auxiliary chopper circuit and transfers power using a triangular ac inductor current at high switching frequency, which reduces the size of the inductor. This paper focuses on the operating principles of the proposed circuit, and introduces an output power control circuit based on feedback control. The control circuit regulates the output power using the characteristics of the triangular ac inductor current to estimate the average output current, which enables output power regulation without a current sensor on the output voltage side, reducing costs. A simplified theoretical expression for the output power is derived with a direct relationship between the output power and triangular ac inductor current generation. The proposed control circuit is verified through experimental, simulated, and theoretical results, where output power is properly regulated under different operating conditions.