Research Of Performance Assessment Method For Three-phase To Three-phase Matrix Converters' Modulate Strategy

Along with the wide application of renewable energy, the requirements of electrical energy conversion are harder. Matrix converter is considered as a general switch type electric energy converter, with advantages of unlimited output frequency, no intermediate storage element, within energy can be two-way flowing, be the converter of any two kinds of power energy. The performance of matrix converter is related with not only its hardware topology structure, but also the use of the modulation algorithm. There is not an effective method in the comparison of control effect with different modulation algorithms. The algorithm for the converter is evaluated based on the minimum variance performance index and improved by using the predictive control. The main achievements of this paper are:(1)Comparative analyzing of modulation strategies for current three-phase to three-phase matrix converter, such as direct transfer function method and the double space vector. And they are realized the simulation by using SIMULINK simulation platform in MATLAB. The numerical results show that the converter based on direct transfer function method has output waveform that is close to sinusoidal wave. It has large calculations and its control effect is not satisfied in the actual controller under the condition of limited calculation. The calculations of double space vector are small but its output waveform has some distortion.(2)A new method is presented by using the minimum variance criterion to evaluate the performance of the modulation strategy of matrix converter. How different key factors affecting the reliability of performance evaluation results are discussed, and a strategy of choosing correct parameters is given. The numerical results show that the proposed method can preferable reflect the real situation of power quality, and has certain prediction ability of matrix converter output. Its effect is much better than general performance assessment method based on the total harmonic distortion rate.(3)For the three-phase to three-phase matrix converter nonlinear model, an improved modulation strategy is proposed by combining the predictive control theory and nonlinear data fusion prediction technology. The specific steps of the algorithm are given. The simulations results show that the proposed method overcomes the defects of the two classical kinds of matrix converter modulation strategies. Its minimum variance performance index is close to one, the tracking accuracy of output is high and the feasibility is good.