| 摘要 |
PROBLEM TO BE SOLVED: To easily calculate a loss power protecting level without performing experiment, inhibit a progressive-wave power in a sufficiently required range and protect a switching element against heat generation. SOLUTION: This high frequency power supply includes an excessive loss power protecting circuit 614 for computing a power amplifier loss power PL from a DC voltage detection signal Vi, a DC current detection signal Ii, a progressive-wave power detection signal Pf and a reflected-wave power detection signal Pr and computing a loss power subtraction signal ΔPL (<0) when the power amplifier loss power PL exceeds a power amplifier loss power protecting level PLp, and a progressive-wave power set value/detection value comparing circuit 69 for adding the loss power subtraction signal ΔPL (<0) to a signal Ps-Pf obtained by subtracting the progressive-wave power detection signal Pf from the progressive-wave power set signal Ps to inhibit a progressive-wave power error signal ΔPs to be Pf-Ps+ΔPL and inhibit progressive-wave power, whereby a heating value for a power amplifier 6 is inhibited. |
