Research On VIENNA Rectifier Based On Fractional Order PID Controller

The widely use of power electronic equipment makes people’s life and industrial manufacture more and more convenient; However we have to acknowledge that the power grid is polluted seriously by these equipment. The standard of power using is improving, and APFC technology is becoming more and more important. Generally, three-phase PWM rectifier is used in high-voltage and high-power situation, however the traditional topology is complex and it’s difficult to control. VIENNA rectifier is a new three-phase, three-level topology, it’s easy to improve the switch frequency and power density, and now many researchers are studying on it.There are many shortcomings in dual-loop structure used traditional PID controller, some new control strategies performance good but it takes lots of time to calculate. Fractional-order PID performance well while using a bit more calculation. This paper takes fractional-order PID controller into VIENNA rectifier, providing a new control method for PWM rectifier.Analyze the working principle of VIENNA rectifier, get the different working models and establish the mathematical model. To make the analysis simple, decouple the VIENNA rectifier under average model, obtain the transfer functions between the duty cycle, inductive current and output voltage.Import the mathematical definition of fractional-order calculus, and establish the structure of fractional-order PID. Because it is difficult to design the parameters, this paper gives out a new method: bring in intelligent optimization algorithms. To implement fractional-order PID controller by DSP, Oustaloup approximate and bilinear transform are used. Based on VIENNA rectifier, design the fractional-order PID controller parameters using MGASA algorithm. The result of Simulink model indicates that the dynamic response such as overshoot and adjustment time of fractional-order PID controller is much better than integer-order PID controller.Experimental platform can output DC700 V, 2kW is established. The experimental result verifies that the VIENNA rectifier is able to work in a higher switching frequency and can get a higher power density. The results also verifies that it is feasible to control VIENNA rectifier by fractional-order PID controller.