Space Vector Modulation And Application Study On A Matrix Converter

Matrix converter is considered as an "all silicon" power converter with an advanced circuit topology. It permits frequency conversion in a single-stage processing without large reactive energy storage components. It draws sinusoidal input currents and allows the input fundamental displacement factor to be set at unity or freely varied regardless of the load power factor. Besides these, it is capable of performing frequency conversion with sinusoidal output voltages and currents at the desired output frequency and allows bi-directional power flow.Combined with computer simulation and prototype experiment, the space vector modulation method of the equivalent AC-DC-AC structure for the matrix converter and its application in drive systems and AC-excited generation systems, were deeply investigated in this dissertation.According to the space vector modulation method of the equivalent structure of the AC-DC-AC conversion, the AC-AC transformation control and the double-space-vector PWM scheme of the matrix converter were deduced. On the basis of the scheme and through the comparisons of several different modulation methods, a optimized switching scheme was presented to gain optimal input and output performance, as well as reduced switching loss. An efficient general digital method was presented to realize the modulation. And then the main circuit and its control system were built, in which the combinations of IGBTs controlled by four-step current commutation algorithm were adopted due to the lack of the true bi-directional switches at present. The effect of current commutation was analyzed, and therefore a compensation method was present to overcome it. The design principle of input filter and its affection to input and output performance were discussed, and a modulation method with input power factor correction was presented. Following an improved V/f control strategy applied in conventional motor drive system was developed to overcome the limitation of voltage transform ratio in matrix converter. Combined with the advantages of matrix converter and AC-excited generation technique, a Variable-Speed Constant-Frequency (VSCF) AC-excited generator fed by a matrix converter was developed, and the simulation and experiment results demonstrate thatmatrix converter is ideal AC-excitation source. Finally, the operation principle and the control of the reactive power and bi-directional energy flow were discussed in detail, which show that reactive power is energy exchange rather than consumption, so it need not be supplied by external source but can be produced by high frequent switching process in three phase circuit; and the bi-directional energy flow is the nature of the bi-directional switch which supplies loop for power flow.This dissertation mainly discussed principal issues of the matrix converter such as realization and application. By the theoretical analysis, computer simulation and experimental investigation, some valuable experiences and significant conclusions were given, which found the technological basis for the matrix converter's further practical studies.