A phase-shift dual-frequency selective harmonic elimination for multiple AC loads in a full bridge inverter configuration

Concurrent dual-frequency ac outputs from a single-inverter configuration potentially benefit many industrial applications, such as induction heating and wireless power transfer. In this paper, a phase-shift dual-frequency selective harmonic elimination (DFSHE) method is proposed to simultaneously generate and regulate two ac outputs at different frequencies from a single full-bridge inverter, which expands the family of DFSHEs. With the phase shift operation, all triplen harmonics of the fundamental are inherently suppressed in the inverter output spectrum, which improves the output THD, and may ease filter design. In addition, an evaluation of the unipolar, bipolar and phase-shift DFSHE techniques is presented, which analyzes design tradeoffs for multi-frequency applications. Finally, experimental results from a 50 W dual-output inverter validate the effectiveness of the proposed method, which agree with theoretical predictions and simulation results.