Experimental Validation of a Novel Method for Harmonic Mitigation for a Three-Phase Five-Level Cascaded H-Bridges Inverter

In modern high-power electrical drives, the efficiency of the system is a crucial constraint. Moreover, the efficiency of power converters plays a fundamental role in modern applications requiring also a limited weight, such as the electric vehicles and novel more electric aircraft. The reduction of losses pushes for systems with a dc bus and a high number of dc/ac converters, widespread in the vehicle, not burdened by a too expensive data processing system. The purpose of this article is to concur to reduce losses by proposing an innovative selective harmonic mitigation method based on the identification of the working areas where the reference harmonics present lower amplitudes. In particular, the main objective is to find a new way to calculate the control angles in real-time operation without solving nonlinear equations, whose resolution would require expensive controllers. Through a very simple approach, the polynomial equations, which drive the control angles, were detected for a three-phase five-level cascaded H-bridge inverter and implemented in a digital system to real-time operation with a low computational cost. As a result, a comparison between the simulation and experimental behavior is presented. In the last part of this article, a real electric machine is driven by considering the appropriate working areas and current harmonics are also evaluated.