Power supply and method of supplying power to load

A plasma generating system comprising:

• a load including an ICP (Inductively Coupled Plasma) device configured to induce a plasma when a power is applied;
• an inverter configured to convert DC (direct current) voltage into AC (alternating current) voltage having a driving frequency and provide the AC voltage to a load, the inverter including at least a first switch and a second switch wherein a first output node between the first switch and the second switch is electrically connected to one end of the load;
• and
• a controller configured to control the driving frequency of the AC power by providing switching signals to the inverter, the switching signals including at least a first switch signal corresponding to the first switch and a second switch signal corresponding to a second switch included in the inverter;
• wherein the controller is further configured to determine the driving frequency according to a control routine such that the driving frequency follows a resonant frequency of the load which is varying as the plasma is induced,
• wherein the control routine comprises:
• acquiring current phase information by detecting a current which is caused by the AC voltage and flows through the load and the inverter,
• acquiring voltage phase information estimated from at least one of the first switch signal or the second switch signal causing the AC voltage,
• calculating a delay time by using the current phase information and the voltage phase information,
• acquiring N delay times by iterating the acquisition of current phase information, the acquisition of voltage phase information, and the calculation N times,
• calculating a representative value for the N delay times, and
• when the representative value is in a predetermined range, maintaining the driving frequency, and
• when the representative value is out of the predetermined range, changing the driving frequency.