Comparison of Midpoint Voltage Control of T-Type Three-Level Inverter with SVPWM and DPWMA Modulation Methods

This paper addresses the problem of midpoint potential fluctuation in a T-type three-level inverter under a discontinuous pulse width modulation strategy A (DPWMA), and by analyzing the main causes of midpoint potential imbalance under this method, a midpoint potential balance control method based on the virtual component compensation is proposed to improve the undesirable effects of the midpoint potential offset under the DPWMA modulation method. The performances of the two modulation methods in terms of steady state performance, dynamic response, power loss and efficiency are analyzed by comparing with the conventional space vector pulse width modulation (SVPWM). The simulation results show that DPWMA modulation has lower power loss and the proposed virtual compensation-based midpoint potential balancing control method has better balancing capability. The study in this paper provides a useful reference for the modulation selection and midpoint potential balance control of T-type three-level topology circuits.