Implementation of a digital controller using DSP TMS320F28335 for frequency and power tracking of load resonant inverters

As the need for more complex control and friendly user interface is increasing, digital control implementation is crucial in modern energy conversion systems and power electronic converters. The Load resonant inverter (LRI) can be controlled to generate a quasi square wave of variable pulse width generated by digital signal processor (DSP). It is used to store the required commands for generating the necessary waveforms to control the frequency of the inverter through proper design of switching pulses. In this paper, a digital controller has been implemented which possess advantages of phase shift control while providing rapid frequency tracking for load resonant applications. The digital control algorithm has been optimized in Embedded C Language and implemented on a floating point Digital Signal Processor TMS320F28335. The DSP alogorithm is experimentally evaluated on load resonant inverter used for an induction heating system prorotype.