Two-stage power supply based on double resonant tank LLC-DCX for magnetic levitation control system applications

330V high-voltage direct current (HVDC) power system is a preferred option of the magnetic train power supply system. The power supply for magnetic levitation control system is used to provide stable operation voltage to the suspension control circuits, which is the key part of magnetic train. The suspension control power supply is typically the converter with high input voltage and low multiple output voltages. The traditional solutions have these problems, such as uncontrolled duty ratio, poor cross-regulation rate, and low reliability. In order to solve these limits, a novel two-stage solution employing the double resonant tank LLC-DCX is proposed and developed in this paper, which can overcome the problems in traditional design. The proposed solution not only can increase the overall conversion efficiency significantly because of the achieving soft-switching over the entire operation range, but also can achieve the low input current ripple and high reliability owing to the uniform thermal distribution. A 210-W, 220-380V input prototype with four outputs, is fabricated and tested in the lab, and the results are presented in this paper. The declared features are demonstrated well by the experimental results.