This paper proposes a method for neutral-point voltage balancing
control for a three-level inverter that uses discontinuous pulse width
modulation (DPWM). The reliability of a three-level inverter system is
influenced by the neutral-point voltage balance. Generally, the offset
voltage is added to reference voltages in the conventional voltage balancing
control method. However, when using DPWM, only limited balance of the
neutral-point voltage is possible because turn-on and turn-off switching
occur at regular intervals. The proposed method is implemented by
adjusting the discontinuous pulse width of positive and negative cycle. The
method maintains low switching loss and effective voltage balance, without
the need for complex calculations. Simulation and experimental results
confirm the feasibility and effectiveness of the proposed method.
