Power supply and method of supplying power to load

1. A power supply comprising:

an inverter configured to convert direct current (DC) power into alternating current (AC) power,

wherein the inverter comprises two output nodes such that the AC power is supplied to a load via the two output nodes, and

wherein the inverter further comprises an inductor which is electrically connected between the two output nodes; and

a controller configured to:

 periodically determine a next cell to be a powering cell or a freewheeling cell,

 adjust a total length of a freewheeling period in the freewheeling cell for controlling the power supplied to the load, and

 control the inverter according to the determined cell configuration,

wherein the powering cell consists of only powering period,

wherein the freewheeling cell comprises a powering period and a freewheeling period, at least one of a positive voltage and a negative voltage being output during the powering period and both of a positive voltage and a negative voltage being not output during the freewheeling period, and

wherein the freewheeling cell is configured that i) absolute value of a positive peak of a current of the inductor is to be matched to an absolute value of a negative peak of the current of the inductor, and ii) a total length for the positive voltage in the freewheeling cell is to be identical to a total length for the negative voltage in the freewheeling cell such that a damage to the at least one first switch and the at least one second switch can be minimized while adjusting the power supplied to the load using the freewheeling cell.

2. The power supply as set forth in claim 1 ,

wherein the controller is further configured to:

obtain a current power amount supplied to the load, and

increase the freewheeling period when the obtained power amount is greater than a target power amount.

3. The power supply as set forth in claim 1 ,

wherein the controller is further configured to:

obtain a current power amount supplied to the load, and

decrease the freewheeling period when the obtained power amount is smaller than a target power amount.

4. The power supply as set forth in claim 1 ,

wherein the controller is further configured to:

obtain a current power amount supplied to the load, and

increases or decreases the freewheeling period periodically until the obtained power amount becomes equal to a target power amount.

5. The power supply as set forth in claim 1 ,

wherein the controller is further configured to:

obtain a current power amount supplied to the load,

detect a difference between the obtained power amount and a target power amount, and

adjust the freewheeling period according to the detected difference such that the obtained power amount becomes equal to the target power amount.

6. The power supply as set forth in claim 1 ,

wherein the controller is further configured to limit a length of each of freewheeling periods in the freewheeling cell to a threshold value or less, and

wherein the controller is further configured to calculate the threshold value depending on a quality factor of the load and a period of the AC power.

7. The power supply as set forth in claim 1 ,

wherein the load is an inductively coupled plasma (ICP).

8. The power supply as set forth in claim 1 ,

wherein one of the two output nodes is a first output node and the other of the two output nodes is a second output node,

wherein the inverter comprises:

a first transistor and a first diode coupled in parallel between a power supply node and the first output node;

a second transistor and a second diode coupled in parallel between the first output node and a ground node;

a third transistor and a third diode coupled in parallel between the ground node and the second output node; and

a fourth transistor and a fourth diode coupled in parallel between the power supply node and the second output node, and

wherein the controller is configured to control respective voltages of gates of the first to fourth transistors.