A Single-Stage Buck/Boost Three-Phase DC-AC Power Converter with Sine-PWM Method and Non-Pulsating AC Waveforms

Three-phase DC/AC power converters enable several applications including photovoltaic systems, electric traction inverters, uninterruptible power supplies, and utility systems. The classical three-phase voltage source inverter (VSI) topology featuring a single-pole double throw switch per-phase, which forms the workhorse of these applications, can operate in only buck mode of operation. Increasing number of applications including transformer-less photovoltaic systems, battery cells, fuel cells, and traction motors require a wide range of input and output voltage range. Hence, a DC/AC power converter topology capable of voltage buck and boost operation will enable wider operating range resulting in efficient and higher performance system designs. The paper presents a single-stage bidirectional DC/AC inverter topology capable of buck and boost mode of operation. In comparison to the state-of-the-art approaches, the topology features minimum switch count (two semiconductor switches per-phase) and simple converter operation with sinusoidal pulse-width modulation. Further, due to the presence of inherent filtering elements, the output voltages and currents are non-switched non-pulsating waveforms resulting in minimized output harmonic and EMI filtering requirements and, lower over-voltages due to long cables. The paper presents the analytical results including component sizing and loss calculation equations of the proposed approach in a step-by-step manner. Detailed simulation and experimental results verify the analytical results.