Bi-frequency Modulation Technique Of Boost Converters

In order to get fast transient response, the frequency of switching converters becomes higher and higher. For the high speed switching, much electromagnetic interference (EMI) impacting the normal work of the conveters and the electronic equipments around, is produced. The bi-frequency modulation technique has superiority on transient response and EMI character, therefore the bi-frequency modulation technique is analyzed in detail in this thesis.A bi-frequency modulated boost converter working in discontinuous conduction mode (DCM) is studied in this thesis. The operation principle and characteristics of voltage mode and current mode bi-frequency modulation are researched. The output voltage ripple and control pulse combination of voltage mode bi-frequency modulated DCM boost converter are also analyzed in detail. The starting characteristic and steady-state characteristic of voltage mode and current mode Bi-Frequency modulation are comparative analysis.According to energy conservation principle, the energy iterative model of the bi-frequency modulated DCM boost converter is built, and its energy transfer process is analyzed in detail.With the simulation software PSIM, the simulation experiment mode of bi-frequency modulated DCM boost converter is built and an experimental prototype is built at the last. With the result of simulation and experiment, the starting characteristic and steady-state characteristic of voltage mode and current mode Bi-Frequency modulation are comparative analysis and the experimental results of bi-frequency modulation and pulse-width modulation (PWM) are compared, and it is verified that the bi-frequency modulation has better transient response and EMI character.