A parabolic voltage control strategy for burst mode converters with constant burst frequency and eliminated audible noise

Burst mode control is widely employed by power converters to improve the light load efficiency. One drawback of burst mode control is that the burst frequency changes with different load, which would introduce audible noise to the system. In order to solve the frequency variation problem of burst mode controlled converters, a parabolic voltage control method is proposed in this paper. By the use of a pair of parabolic carriers as the control bands, the burst frequency is controlled to be constant and audible noise can be eliminated. The derivation of the proposed parabolic voltage control is conducted and operating principles are discussed. The performance of the proposed control method is experimentally verified by the use of a burst mode boost converter.