Remote plasma source (RPS) power coupling circuit and control system

A remote plasma source (RPS) power coupling circuit, comprising:

• a direct-current (DC) voltage source, two current sharing circuits connected in parallel, a three-winding transformer, and a chamber load, wherein each of the two current sharing circuits comprises:
• a full-bridge inverter circuit, wherein the DC voltage source is input to the full-bridge inverter circuit;
• a resonant converter connected to the full-bridge inverter circuit, wherein the resonant converter comprises an inductor Lr, a capacitor Cr, and an inductor Lk;
• the inductor Lr is connected to the full-bridge inverter circuit;
• and the inductor Lk is connected to the three-winding transformer;
• and
• a current sharing resistor Ro connected to the inductor Lk;
• wherein the three-winding transformer comprises primary winding coils respectively connected to the two current sharing circuits, and a secondary winding coil connected to the chamber load;
• the RPS power coupling circuit is controlled by a control system;
• the control system comprises a power loop, a current loop, and a current sharing loop;
• the power loop serves as an outer loop of the control system;
• the current sharing loop and the power loop act concurrently;
• and the current loop serves as an inner loop of the control system;
• the current loop is configured to:
• acquire output current reference values io1, io2 upon power loop proportional-integral (PI) adjustment, and determine an average filtered value īo according to the output current reference values io1, io2;
• acquire current errors es, es′ according to the average filtered value īo, output currents io, io′, and voltage errors er, er′;
• acquire current loop errors eo1, eo2 according to the output current reference values io1, io2, the voltage errors er, er′, and the average filtered value īo;
• and
• perform current loop PI adjustment according to the current loop errors eo1, eo2;
• and
• the control system further comprises a controller and a pulse-width modulation (PWM) modulator;
• the controller is configured to acquire a switching frequency and a duty cycle upon the current loop PI adjustment, and configured to perform the current loop PI adjustment on the current loop error eo1 to obtain an output signal vfs, and perform amplification and amplitude limiting on the output signal vfs to obtain a frequency signal fs of the PWM modulator;
• and perform the current loop PI adjustment on the current loop error eo1 and take a reciprocal to obtain an output signal vd, and perform amplification and amplitude limiting on the output signal vd to obtain the duty cycle d of the PWM modulator;
• and
• the PWM modulator is configured to control and output a pulse signal according to the switching frequency and the duty cycle, thereby controlling on-off of switching transistors S1-S4.