Power supply and method of supplying power to load
A power supply includes an inverter configured to convert direct current (DC) power into alternating current (AC) power, an impedance matching circuit configured to supply the AC power to a load, and a controller configured to detect a delay time of an output voltage and an output current output to the impedance matching circuit and the load and to adjust a frequency of the output voltage according to the detected delay time.
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.
2. The plasma generating system of claim 1 ,
wherein during the control routine, the inverter is controlled to perform a powering operation which is applying a power to the load and a freewheeling operation which is not applying a power to the load, and
wherein a length of a first time period corresponding to the powering operation and a length of a second time period corresponding to the freewheeling operation are determined based on a predetermined target power amount.
3. The plasma generating system of claim 2 ,
wherein, in the powering operation, an output voltage of the inverter, which is applied to the load, has high level when the first switch is on and the second switch is off or low level when the first switch is off and the second switch is on, and
wherein in the freewheeling operation, the output voltage has neither high level nor low level.
4. The plasma generating system of claim 2 ,
wherein, in the powering operation, an output voltage of the inverter, which is applied to the load, has high level when the first switch is on and the second switch is off or low level when the first switch is off and the second switch is on, and
wherein in the freewheeling operation, the output voltage has zero level such that voltage across the load is 0.
5. The plasma generating system of claim 2 ,
wherein the controller is further configured to:
calculate a supplied power which is supplied to the load, and
compare the predetermined target power amount and the supplied power to determine the length of the first time period and the length of the second time period.
6. The plasma generating system of claim 1 ,
wherein the inverter further includes a third switch and a fourth switch, and
wherein a second output node between the third switch and the fourth switch is electrically connected to other end of the load.
7. The plasma generating system of claim 6 ,
wherein the inverter further comprises a first diode to a fourth diode, and
wherein each of the first diode to the fourth diode is parallelly connected to each of the first switch to the fourth switch.
8. The plasma generating system of claim 6 ,
wherein the inverter further includes an inductor serially connected between the first output node and the second output node.
9. The plasma generating system of claim 1 ,
wherein the driving frequency is slightly higher than the resonant frequency of the load.
10. The plasma generating system of claim 9 ,
wherein the driving frequency is 0.1 to 10 percent higher than the resonant frequency of the load.
11. The plasma generating system of claim 1 , further comprising a transformer,
wherein the transformer is inductively coupled to a wiring between the inverter and the load and is configured to output a signal corresponding to the phase information.