Research On Controlling Strategy Of High Performance Matrix Converter Fed Induction Motor Adjustable Speed System

Matrix converter is a kind of direct AC-AC power electronic converter. Its advantages over the traditional pulse width modulation converters lie in the capability of bi-directional power flow, nearly sinusoidal input/output waveforms and a controllable input power factor. Using matrix converter in adjustable speed drives (ASDs) could achieve high performance as well as to meet the electromagnetic interference requirement. Therefore, matrix converter fed induction motor drive systems has high potency in the next generation of ASDs.A modulation algorithm to compensate the unbalance of input voltage is presented based on the analysis on topology, operational mechanism and the direct space vector modulation strategy of matrix converter. Then, a non-linear analytical model of matrix converter, which is the general form of all modulation strategies known, is deduced by introducing the concept of the duty cycle space vecter.Input filters are usually adopted in matrix converter systems to meet the requirement of electromagnetic compatibility (EMC). On the other hand, input filter is potential to deteriorate the dynamic performance, even determine instability. The reasons for deteriorated dynamic performance and potential instability are analyzed, and the mechanism that input filter influences stability are determined. An alternative filter topology is proposed to improve the input current quality from the point of reducing output impedance of input filter. Furthermore, a control method to improve both dynamic performance and stability, virtual resistant algorithm, is presented, which only requires the addition of a low-pass digital filter in the existing modulation strategy. This algorithm is easily implemented, avoiding the power consumed by actual resistance.Based on the generalization and improvement of the input filter design for matrix converter, a multi-object optimization designing algorithm is presented. The constraints are assurance of stability, minimization of total harmonic distortion, avoidance of resonance caused by harmonic current at the switching frequency, while the object is the weighted sum of construction cost, base frequency voltage drop, base frequency voltage phase shift, stability margin of power and the power consumed by filter resistance. The analytical description of all objects and constraints is achieved from mathematical consideration. Then, a Non-dominated Sorting Genetic Algorithm (NSGA-II) is proposed and the approach of constraints resolution is improved.The design of PI controller-based matrix converter fed induction motor vector control system is verified, leading to the large signal non-linear equations of the system. The stability and dynamic performance are analyzed. An active disturbance rejection controller (ADRC)-based matrix converter fed induction motor vector control system is proposed and realized. It is illustrated that ADRC has some advantages over PI controller with the comparison of the proposed system with that of PI controllers. The modeling, analyzing and designing of matrix converter are integrated into a theoretical framework.On the basis of theoretical research, a prototype of matrix converter fed induction motor system is proposed, including hardware and software design. The hardware design includes the schemes of switching matrix, input filter and the control board. The DSP and CPLD based control algorithm is implemented in the software design.Finally, this paper makes some conclusions, and presents some issues for future research.