| 摘要 |
PURPOSE:To always maintain a load power constant by performing the processes of analog-to-digital converting a load voltage, calculating the effective value, and leading a firing angle in the half wave of an AC waveform, thereby rapidly correcting the control amount of the load. CONSTITUTION:When detecting a voltage applied to a load 3, analog-to-digital converting it, calculating the effective value form the value, then comparing it with a set value of a target value setter 9 and deciding the firing angle of a semiconductor element 7, the processes of detecting the applied voltage to deciding the firing angle are finished within the half wave of an AC waveform. To this end, an A/D conversion is started from the firing point of the load 8, and the square integration value of the data is obtained at every interruption of the A/D conversion. This is continued up to a zero-crossing point, and when a zero-cross interrupt is generated, a mean route is calculated to obtain the effective value,and the firing angle is obtained by proportionally calculating from the effectively value. |
