The Study, Based On Dsp Controlled Pfc Circuit

Nowadays PFC inverters which are being used in many fields play an important role in the life. It is used in many applications. Many control methods are explored, including average current control, peak current control, hysteretic control, nonlinear carrier control, etc. All of these control methods had been implemented by the analog circuits. Among these PFC control methods, average current mode control is the most popular. Several commercial ICs, such as UC3854/3855 and ML4824 are available for the PFC applications.With the development of the digital technique, more and more control algorithms can be implemented in power electronics by the digital chips: microprocessors or digital signal processors (DSP). The merits of digital control: simple hardware, no temperature drift, flexible control and easy to realize advanced arithmetic etc, make digital control technique to be used in power supply manufacture to let it more credible and easier to realize in batches with lower costs. In the current it is popular to use digital control in power design. This thesis presents the total project to design the PFC power supply based on DSP. It summarizes the control method of the PFC and the characteristic of the digital control. In order to get good dynamic as well as static performance, multiple-loop control strategy with the instantaneous outer voltage loop and inner current loop is used in PFC converter based on DSP TMS320LF2407A. How to get the control parameters is analyzed in details and the experimental results are displayed.To reduce the harmonics in the line current, the random PWM mode is adapt. Related to the typically constant PWM carrier frequency and its high harmonics, modulation of this frequency can be used to decrease EMI and cost no more gain.All of the existing control technique cannot take full advantages of the DSP and the switching frequency of the converter is limited by the speed of the DSP. So a new predictive control strategy is proposed to solve the above mentioned problems in digital controlled PFC.