| 摘要 |
PROBLEM TO BE SOLVED: To generate a sine-wave for optimum compensation for power factor even during variation of frequency and load by sensing a load of an inverter circuit and then re-set the amplitude of sine-wave table and sine-wave value. SOLUTION: First, a zero voltage point of AC voltage is supplied to an interrupt terminal (S10), an interval of the zero voltage point detecting signal is detected and the frequency of AC voltage is decided to be 50 Hz or 60 Hz (S12). Amplitude of the sine-wave table and sine-wave are set to the determined frequency (S14). Thereafter, the sine-wave table is stored in an auxiliary memory (S16). While a power factor compensation is conducted, change of load is sensed (S20) but if there is no change of load, the pre-stored sine-wave is supplied in direct to a power factor compensation control unit. However, if a load is changed, after the amplitude of sine-wave table and sine-wave value are set again, such sine-wave table is stored in the auxiliary memory. |
