Closed-Loop Control Of AC-AC Matrix Converter Based On DSP

Matrix converter (MC) is a power converter based on AC-AC direct conversion. More and more attention is paid to MC depending on its adventages, such as omitting the DC part, obtaining unit power factor, getting sinusoidal input currents and output voltages and easy to realize bidirectional flow of energy.This dissertation firstly introduces the fundamental elements and modulation methods of three-phase AC-AC MC. Then mainly analyzes modulation process of MC with dual space vector modulation (DSVM) and gains the mathematic relations between inputs and outputs. The duty expressions of MC have been derived by the method of separate modulation and then combination of input current vector and output voltage vector.MC closed-loop control method based on DSVM is presented, in which the RMS value of output line voltage is taken as feedback and PI regulator is adopted. Meanwhile, Matlab simulation model of the system has been established, and the input and output characteristic and the effectivity of closed-loop control of MC have been analyzed.The software and hardware designs of MC closed-loop control system are introduced in detail. The functions of system controller are mainly finished by DSP and CPLD. The functions, such as the realization of closed-loop and calculation of the modulation duties online, are finished in DSP. The responsibility of CPLD mainly is switch control signals transition.Finally, the prototype of closed-loop control system of MC has been designed. A seris of experiments have been made, and the results show that the closed-loop control of MC presented here is correct. Also, the MC closed-loop systems based on the method can be applied to the variable frequency power supplies.