| CPC H02M 7/537 (2013.01) [H02M 1/38 (2013.01); H02M 7/5387 (2013.01); H03H 7/38 (2013.01); H05H 1/4652 (2021.05)] | 11 Claims |
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1. 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.
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