Patent ID: 9634556
Date: 2017-04-25
CPC Classifications: H02M,Y02B

Claim:
1. A control method for controlling a power converter, the power converter at least comprising a switch and an inductor, the switch being electrically coupled to the inductor, and being selectively turned on or off according to a control signal to make the inductor store or release an energy, wherein when the energy of the inductor is completely released, resonance occurs between the inductor and a parasitic capacitance of the switch, the control method comprising: determining an on-time and a falling time according to at least one of voltage information and current information of the power converter; determining a switching period of the control signal according to the on-time, the falling time and a resonant period corresponding to the inductor and the parasitic capacitance; adjusting the switching period by comparing the switching period with a first threshold period and a second threshold period, wherein the second threshold period is greater than the first threshold period; and outputting the control signal having the switching period when the switching period is greater than the first threshold period and less than the second threshold period, or when the switching period is greater than the second threshold period and the power converter operates at over 50% of a rated power, wherein the first threshold period and the second threshold period have the following specific relations therebetween: where TMIN is the first threshold period, TMAX is the second threshold period, TR is the resonant period, K1 and K2 are nonnegative integers, and FSET is a minimum switching frequency of the switch when the power converter operates in a boundary conduction mode and at 50% of the rated power.