| 摘要 |
Provided is a high-frequency power supply device that makes the effective power of a load constant. A SWEEP-mode in which frequency is roughly changed is started from a time point (t1) at which high-frequency power is started to be output, and a voltage standing wave ratio (VSWR value) that is the ratio between a FWD value and a REF value is obtained. When the VSWR value becomes a predetermined VSWR threshold value or less (reflective wave reduces to a predetermined level), an ADJUST-mode in which frequency is finely changed according to the VSWR value is started (at t2). For a REF value proportion calculated from the REF value and the FWD value, a REF value proportion difference that is the difference between previous and current REF value proportions is also obtained. If a state in which the REF value proportion difference is less than or equal to a predetermined REF value proportion difference threshold value continues for a predetermined time (from t3 to t4), it is determined that matching by the frequency control is saturated and then power corresponding to reflective wave power (W) is added to forward wave power (W), thereby performing an effective power constant control for matching an effective power to a target output.
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