| 摘要 |
PURPOSE:To perform constant-power control on a load with a simple constitution, by applying a negative feedback control method, in which an integrated output is sampled when the integrated output just shows its effective value after the AC voltage impressed across the load is rectified and integrated, and compared with a reference value. CONSTITUTION:The trigger point (phase angle) of a switching element D1 is controlled by a phase control signal from a phase control circuit 37 and a voltage, whose effective value is adjusted against an input AC 100V, is impressed across a load 32. The AC voltage impressed across the load 32 is transmitted to the secondary side by a transformer T. The AC voltage induced on the secondary side of the transformer T is inputted to an integration circuit 34 where the AC voltage is integrated after rectification at a rectifier circuit 33. The transformer T, rectifier circuit 33, and integration circuit 34 constitute an effective value detecting circuit. The resistance values of resistances R2 and R3 and capacity value of a capacitor C2 are previously fixed in such a way that the output of the integration circuit 34 at the time of sampling for voltage measurement can just show an effective value. |
