| 摘要 |
PROBLEM TO BE SOLVED: To stably perform output control of a high-frequency power supply in a wide range without unnecessary power loss.SOLUTION: An RF power controller 7 controls an output voltage Vof a DC-DC conversion part 3 to change output powers Pand Pof a DC-RF conversion part 4. An RF composition part 5, when there is a phase difference &thetas; between output voltages vand vof the DC-RF conversion part 4, outputs to the load a power Pobtained by composing the output powers Pand Pat a ratio depending on the phase difference &thetas;. The RF power controller 7, in a state where an output power Pof the DC-DC conversion part 3 is a predetermined switching threshold Por more, sets the phase difference &thetas; to be zero, and changes the output voltage Vof the DC-DC conversion part 3 to control the output power Pto a target power P. When the output power Pis changed smaller than the switching threshold P, the output voltage Vof the DC-DC conversion part 3 is fixed to a value at the change of state, and the phase difference &thetas; is changed to control the output power Pto the target power P. |
