A Systematic Study on the Harmonic Overlap Effects for DC/AC Converters under Low Switching Frequency Modulation

In most high power industrial applications, the low switching frequency modulations (LSFM) are usually implemented to reduce loss and heat dissipation pressure. However, there some unexpected influences caused by order harmonic sinusoidal pulse width modulation (SPWM), such as imbalanced submodule in cascaded half-bridge inverter (CHB) limited output capability H-bridge neutral-point-clamped (HNPC) converter. This paper starts generalizing basic characteristic of two-level SPWM, then deeply investigates low-frequency on operation circuits. They classified into three mechanisms generally named overlap effect (HOE). The corresponding solutions copy with proposed verified topologies through high-power simulations simulations. addition, a comprehensive summary these effects typical converters is drawn. design rules schemes for multilevel voltage source (VSCs) at also proposed.