Research on space vector pulse-width modulation strategy for three-phase four-leg medium frequency inverter using natural coordinate

Abstract

In order to study the capacity under unbalanced load of the inverter, the space vector pulse-width modulation(SVPWM) in natural coordinate is analyzed, which reduces the complexity of coordinate transformation, vector selection and duty cycle calculation in αβγ coordinate, as well as facilitates the realization of digital control. By analyzing the average current model of the three-phase four-leg topology, the load current is sampled in real time and the reference voltage is calculated so that the inverter can adapt to various unbalanced loads, the PI controller is used to stabilize the output voltage. Simulation and experiments verify that the inverter can bear non-linear and unbalanced load , total harmonic distortion of the output voltage waveform is small.

Keywords

• three-phase four-leg inverter
• SVPWM
• natural coordinate
• unbalanced load