A single-phase dual frequency inverter based on multi-frequency selective harmonic elimination

Simultaneous generation of two AC outputs at different frequencies from a single-phase inverter offers practical benefits and control flexibility for many industrial applications. In this paper, a dual-frequency selective harmonic elimination (DFSHE) modulation method is proposed to generate and control two individual frequencies in an H-bridge, while diminishing undesired harmonics. Two AC elements are synthesized independently in the modulation scheme, and thus flexible individual power regulation is achieved via the proposed method. In addition, both unipolar and bipolar DFSHE cases are investigated. Characteristics of the two methods are compared and alternatives are provided for different applications. The generation algorithms of the DFSHE are also studied in this paper, and can be applied to a variety of DC/AC topologies without adding extra switching devices. Finally, the experimental results from a 100W dual-load single-phase inverter verify the effectiveness of proposed method, where 50 kHz and 450 kHz AC outputs are generated and individually regulated.