A Modular Three-Phase Buck-Boost Motor Drive Topology

The voltage-source inverter (VSI) is a fundamental power electronic device to drive three-phase electrical machines with high performance. In this paper, a modular three-phase DC/Rectified AC/AC (DC/RAC/AC) inverter supplying a permanent-magnet synchronous machine (PMSM) is proposed. In this topology, the three-phase VSI is composed of three single-phase modules connected in parallel. Each single-phase inverter module consists of a non-inverting bidirectional buck-boost DC/DC converter and a cascaded H-bridge inverter. Here, the DC/DC converter generates rectified AC waveforms and the H-bridge inverter alternates these signals to create the intended AC voltage waveform. Therefore, the bulk DC Bus capacitor and boost converter inductor, which exist in a typical battery-powered voltage boosting topology can be eliminated which results in a smaller size and reduced cost. In addition, the switching losses only occur in the DC/DC converter unit and the H-bridge inverter switching losses are negligible due to the zero-voltage switching while in a conventional structure, high-frequency switching occurs both in the DC/DC converter and the six-switch inverter causing reduced overall system efficiency. The proposed inverter is controlled with a well-known field-oriented control (FOC). This paper presents the operating principle, design, and control structure of the proposed three-phase inverter. The functionality of the three-phase inverter is verified through PowerSim simulations. The proposed motor drive system is compared to the conventional one while driving a 4 kW PMSM with FOC and the whole system efficiency difference map is generated. The biggest difference is recorded as 3.8 points favoring the proposed system.