Power-Linked Predictive Control Strategy for Power Electronic Traction Transformer

Abstract

Power electronic traction transformer (PETT) is a module-cascaded converter with high-frequency-link technology to realize high-power conversion. A typical structure of PETT contains a single-phase cascaded H-bridge rectifier in the first stage and several dual active full-bridge (DAB) dc-dc converters in the second stage. For PETT adopting such a complex topological structure, the control strategy also becomes complicated and should be carefully designed. In this article, a power-linked predictive control (PLPC) strategy for PETT is proposed based on the predictive controls of the H-bridge rectifier and DAB dc-dc converter. A power link is brought into the control strategy to connect the H-bridge rectifier with a dc-dc converter, through which the input power of PETT can match the output power. Moreover, the voltage balance control and power balance control are also combined with predictive control by the PLPC strategy. Using such a strategy, the fluctuation of the H-bridge rectifier dc voltage is suppressed, the circumfluence among modules is reduced, and the dynamic and steady-state performances are both improved compared with traditional strategy. Simulation and experimentation platforms with both resistance load and motor load are built to show the effectiveness and correctness of the PLPC strategy.