System and method for control of high efficiency generator source impedance
Systems and methods for adjusting the source impedance of a generator are disclosed. An exemplary method includes generating a first signal and applying the first signal to a first input of a combiner, generating a second signal and applying the second signal to a second input of said combiner, and combining the first and second signals with the combiner at an output of the combiner to produce power that is delivered to the plasma load. A controllable variable impedance is provided to an isolation port of the combiner, and the controllable variable impedance is adjusted to vary the source impedance of the generator.
1. A method for adjusting the source impedance of a generator delivering power to a plasma load, either directly or through an impedance matching network, the method comprising:
generating a first signal and applying the first signal to a first input of a combiner;
generating a second signal and applying the second signal to a second input of the combiner;
combining the first and second signals with the combiner at an output of the combiner to produce power that is delivered to the plasma load;
providing a controllable variable impedance to an isolation port of the combiner; and
adjusting the controllable variable impedance to adjust the source impedance of the generator.
2. The method of claim 1 , wherein when the plasma load is matched to a designed load impedance of the combiner and the impedance in which the isolation port is terminated is equal to a designed termination impedance and the first and second signals have a designed amplitude and phase relationship, more than 80% of the total power supplied to the combiner by the first and second signals is delivered to a matched load connected to the output of the combiner and less than 20% of the total power supplied by the first and second signals is delivered to the isolation port termination; and when a phase of one of the input signals is shifted by 180 degrees, more than 80% of the total power supplied to the combiner by the first and second signals is delivered to the isolation port termination and less than 20% of the total power supplied to the combiner by the first and second signals is delivered to the matched load connected to the output.
3. The method of claim 1 , wherein the second signal is phase shifted between 60 and 120 degrees with respect to the first signal.
4. The method of claim 1 , wherein at least one of the following is monitored:
a parameter indicative of an interaction between the power supply and the plasma load, a parameter indicative of plasma ignition, and a parameter indicative of pulse shape in a pulsed power application;
wherein adjusting the source impedance includes adjusting the source impedance of the generator to promote at least one of: a reduction in an instability of the plasma load, ignition of the plasma load, and an improved pulse shape of pulsed power delivered to the plasma load.
5. The method of claim 4 , wherein adjusting includes:
mismatching the source impedance of the generator from an impedance of the plasma load; and
aligning an impedance trajectory of the plasma load with contours of an open loop power profile of the power supply.
6. The method of claim 4 , wherein monitoring includes monitoring at least one of voltage, current, forward power, reflected power and plasma load impedance.
7. The method of claim 4 , wherein adjusting includes:
adjusting the source impedance using at least one of gradient and gradientless optimization methodologies to at least one of: reduce instabilities, improve plasma ignition, and adjust a pulse shape.
8. A power supply system for providing power to a plasma load, the power supply system comprising:
a first power amplifier including an input and a first-amplifier-output;
a second power amplifier including an input and a second-amplifier-output;
a four-port combiner including a first input port disposed to receive a first signal from the first-amplifier-output, a second input port disposed to receive a second signal from the second-amplifier-output, an output port to provide output power, and an isolation port disposed to couple to a terminating impedance, wherein the combiner is configured to combine the first signal and the second signal to apply a power signal to the output port;
a controllable variable impedance component coupled to the isolation port as the terminating impedance; and
a controller configured to adjust the controllable-variable impedance component in order to modify the source impedance of the power supply system.
9. The power supply of claim 8 , comprising:
a signal generator configured to generate an input signal;
a quadrature splitter to provide, responsive to the input signal, a signal to the first power amplifier and a signal to the second amplifier that is phase shifted between 60 and 120 degrees relative to the signal provided to the first power amplifier.
10. The power supply of claim 8 , wherein the controllable variable impedance component includes at least of one of a collection of discreetly switched capacitors and a continuously variable capacitor.
11. The power supply of claim 8 , wherein the controller includes:
a processor;
a non-transitory memory including non-transitory instructions that are executable by the processor to adjust the controllable variable impedance, the instructions including instructions to:
adjust the source impedance of the power supply.
12. The power supply of claim 8 , wherein the controller includes:
a field programmable gate array;
a non-transitory memory including non-transitory instructions that are accessed by the field programmable gate array to configure the field programmable gate array to:
adjust the source impedance of the generator.