Research On Matrix Convert Based On Over-modulation Strategy Applying To The Power System Of Variable Speed Constant Frequency

Variable Speed Constant Frequency (VSCF) due to its peculiar advantages is widely used not only in aircraft electrical generating system but also in Wind Electric Power System. At present, the power converters of Variable Speed Constant Frequency have some disadvantages such as large capacitor storage link, serious harmonic pollution and so on. Matrix Converter as a new power converter is concerned by many experts because it has an adjustable power factor, allows bi-directional energy transfer and has no large capacitor storage link. Under the liner model, the voltage transfer ratio of Matrix Converter is 0.866. The paper applies the over-module strategy of Matrix Converter to variable speed constant frequency power generating system.Firstly, this paper introduces the over-modulation strategy of Matrix Converter in detail. The different module strategies have been applied to the virtual rectifier area and the virtual inverter area. The paper obtains the relation between voltage modulation ratio of the first model and voltage modulation ratio of the second model region by deducing the formula. And the relation between the voltage transfer ratio and voltage modulation ratio of Matrix Converter in any modulation ratio is obtained.In the simulation software, the simulation model of Matrix convert Based on over-modulation strategy applying to the power system of Variable Speed Constant Frequency is established. Not only the over-modulation strategy but also the power system of Variable Speed Constant Frequency which is based on Matrix Convert using over-modulation strategy is simulated and analyzed.The system design is introduced in detail, which includes the hardware design and the software programming design. There is the main power circuit, the controlled circuit, the circuit of the identifying wave, the IGBT-driving circuit, the delay circuit, the over-current protection circuit and so on. The software programming design is completed by DSP and CPLD. The calculation of over-modulation duties ratio is finished by DSP and the nine driving signals are obtained by CPLD.Finally, the experimental platform has been designed. The experiments of the over-modulation strategy and the power system of Variable Speed Constant Frequency which is based on Matrix Convert using over-modulation strategy have been made. The results show that the amplitude of the output voltage is rising greatly.