Improved symmetrical pulse-density-modulation induction heating power based on FPGA

This paper proposes an improved symmetrical PDM (pulse-density-modulated) method, which distributes the pulses in a work cycle more symmetrically comparing with the previous PDM approaches, to avoid the output current unstable and discontinuous in light load status. A state machine method is implemented to generate the symmetrical pulses based on FPGA. The details of improved symmetrical PDM principle, generation circuits and control circuit design are given. Some experimental results are shown to verify the validity of the method.