Driving switches of a plasma load power supply
Operation of a plasma supply device having at least one switching bridge with at least two switching elements, and configured to deliver a high frequency output signal having a power of >500 W and a substantially constant fundamental frequency >3 MHz to a plasma load is accomplished by determining at least one operating parameter, at least one environmental parameter of at least one switching element and/or a switching bridge parameter, determining individual drive signals for the switching elements taking into account the at least one operating parameter, the at least one environmental parameter and/or the switching bridge parameter, and individually driving the switching elements with a respective drive signal.
1. A method of operating a power supply delivering a high frequency output signal having a power of more than 500 W and a substantially constant fundamental frequency greater than 3 MHz to a plasma load, the method comprising:
determining an operating parameter, an environmental parameter of a switching element or a switching bridge parameter;
generating individual drive signals for at least two switching elements of a switching bridge of the power supply as a function of the determined operating parameter, environmental parameter, or switching bridge parameter; and
individually driving the switching elements of the power supply with respective ones of the generated drive signals in normal operation of the power supply;
wherein individually driving the switching elements includes driving the switching elements in a non-complimentary manner.
2. The method of claim 1 , wherein determining the operating parameter, environmental parameter or switching bridge parameter comprises determining an electrical parameter.
3. The method of claim 2 , wherein determining the electrical parameter comprises determining an amount of electrical current flowing through one of the switching elements, a voltage at one of the switching elements, a current path, or a voltage profile.
4. The method of claim 1 , wherein determining the operating parameter, environmental parameter or switching bridge parameter comprises determining a temperature of one of the switching elements, as the environmental parameter.
5. The method of claim 1 , wherein determining the operating parameter, environmental parameter or switching bridge parameter comprises determining a parameter indicative of a load impedance seen by the switching bridge, as the switching bridge parameter.
6. The method of claim 1 , wherein individually driving the switching elements comprises variably driving the switching elements and analyzing a resulting change in the operating parameter, environmental parameter, or switching bridge parameter.
7. The method of claim 1 , wherein individually driving the switching elements comprises briefly switching at least one of the switching elements on during a portion of the switching cycle when the switching element is normally open.
8. The method of claim 1 , wherein one or more of the switching elements are maintained in a nonconductive state for one or more periods of the fundamental frequency.
9. A power supply configured to generate an output power greater than 500 W at a substantially constant fundamental frequency greater than 3 MHz, and to deliver a high-frequency output signal to a plasma load, by which, at least upon mismatching, reflected power is returned to the power supply, the power supply comprising:
a drive signal generator, which drives at least two drivers;
a switching bridge having at least two switching elements, each of the drivers associated with only a respective one of the switching elements; and
at least one sensor connected to the drive signal generator and responsive to an operating parameter, a switching element environmental parameter, a switching bridge parameter, or a combination thereof;
wherein the power supply is configured such that, when the power supply is operated in normal operation while at least indirectly connected to a plasma load, the drive signal generator generates individual drive signals for the switching elements as a function of input from the sensor, and such that non-complimentary operation of the switching elements is enabled.
10. The power supply of claim 9 , wherein one of the drivers and the associated switching element are arranged in a common housing.
11. The power supply of claim 9 , wherein the switching elements and associated drivers are arranged in the form of a half bridge within a common housing.
12. The power supply of claim 9 , wherein the switching elements and associated drivers are arranged in the form of a full bridge within a common housing.
13. The power supply of claim 9 , wherein the drive signal generator drives drivers for all of the switching elements.
14. The power supply of claim 9 , wherein the drive signal generator is in the form of a digital module.
15. The power supply of claim 14 , wherein the digital module is a DSP.
16. The power supply of claim 9 , further comprising an A/D converter connected downstream of the sensor.
17. The power supply of claim 9 , wherein the switching bridge is a first switching bridge, the power supply further comprising a second switching bridge, and wherein outputs of the first and second switching bridges are coupled by way of a coupler.