Three-Phase Active Split-Source Inverter with step-up/step-down DC bus voltage capabilities for traction application

Abstract

This paper proposes a new single-stage DC-AC inverter with both step-up and step-down DC bus voltage capability. In a two-level inverter, low-speed operating points result in low modulation index values and poor efficiency. The proposed topology introduces a step-down mode, allowing the motor to be driven with a DC bus voltage lower than the source in low-speed regions, while maintaining the unaltered step-up capability of the DC bus. This means that the addition of the step-down function does not induce extra losses during step-up operation. The converter is validated through both simulation and experiments. In step-down mode, reduced phase current ripple and lower DC-link capacitor temperature are achieved.