Patent ID: 7310247

Claim:
A method for controlling transformer excitation cycles, comprising: a means of setting a duty cycle of a transformer: defining the front semiperiod of each duty cycle to be an excitation cycle and the rear semiperiod of each duty cycle to be a demagnetization cycle; making all said duty cycles have an identical duty width; making all said excitation cycles have an identical change of excitation current; and making all said demagnetization cycles have an identical change of excitation current; a means of detecting a modified excitation cycle of said transformer: obtaining said modified excitation cycle and the maximum current of said modified excitation cycle according to the variation of the power driving the load behind said transformer; and a means of modifying said demagnetization cycle of said transformer: setting a saturated excitation value and a demagnetization reference value of said transformer with said demagnetization reference value used to enforce that said transformer cannot start said excitation cycle of the next duty cycle unless the minimum current of said demagnetization cycle is equal to or less than said demagnetization reference value; and using the maximum current of said modified excitation cycle obtained in the preceding step and said demagnetization reference value to generate a modified demagnetization cycle under the identical change of said excitation current of a normal demagnetization cycle, wherein the maximum current of any one said modified excitation cycle will not exceed said saturated excitation value, and said transformer can always operate normally.