Dual Edge Phase Detector and Tuning Method That Uses Same

An induction heating system, comprising:

• a tank circuit;
• a drive circuit coupled to the tank circuit for driving the tank circuit, the drive circuit outputting a voltage and a current;
• a tuner comprising an energy storage device (ESD), an analog to digital (A/D) converter for producing a digital value corresponding to a voltage of the ESD, a processor and a data storage unit storing a threshold value;
• a voltage controlled oscillator (VCO) for providing to the drive circuit a signal having a frequency, the frequency of the signal being dependent on a control signal output by the processor;
• wherein
• the induction heating system is configured to produce i) a first pulse signal based on a voltage applied to the tank circuit, wherein the first pulse signal comprise a plurality of “voltage” pulses, and ii) a second pulse signal comprising a plurality of “current” pulses and each of said plurality of current pulses being associated with one of the plurality of voltage pulses,
• the tuner is configured such that, for each of said plurality of voltage pulses, i) a current flows to the ESD for a first period of time proportional to X and ii) a current flows out of the ESD for a second period of time proportional to Y,
• X is the amount of time between a rising edge of the voltage pulse and a rising edge of the current pulse associated with the voltage pulse,
• Y is the amount of time between a falling edge of the current pulse associated with the voltage pulse and a falling edge of the voltage pulse, and
• the control signal output by the processor is dependent upon the digital value produced by the A/D converter and the threshold value.