Research Of Virtual Uncontrolled Rectifier Matrix Converter

Matrix converter (MC) is a new type of AC-AC power converter with multiple advantages, such as, sinusoidal input and output currents, generation of load voltage with varying amplitude and frequency, regeneration capability, operation with unity power factor for any load, and without energy storage components in dc-link. Thus, MC compensates for the lack of conventional electric power transducer, and attracts many researchers" interests to investigate on power conversion in recent years. Voltage transfer ratio of Indirect SVPWM(Space Vector Pulse Width Modulation) Matrix Converter is no more than 0.866 in linear modulation range. Overmodulation can raise voltage transfer ratio, but it can result in distortion of output wave.To solve this problem, this paper used the strategy of " virtual dc-link " to equal MC as the processes of "virtual rectifier" and "virtual inverter". Therefore, the concept of "Virtual Uncontrolled Rectifier Matrix Converter" was put forward in this paper. The "uncontrollable rectification" was adopted in virtual rectifier, and the voltage space vector modulation was adopted in virtual inverter. The voltage transfer was raised up to 0.955 in the linear range. The voltage transfer ratio with overmodulation being adopted can be achieved, meantime output wave distortion and nonlinear can be avoided.Four-step commutation and two-step commutation were researched. The four-step commutation technology based on the measurement of load current direction and the four-step commutation technology based on the measurement of input voltage were simulated using MODELSIM. And four-step commutation technology base on load current direction detection were realized in FPGA.The Virtual Uncontrolled Rectifier Matrix Converter experiment was built. Main circuit, drive circuit, sample and condition circuit and commutation controller was designed. Bi-switch of main circuit is constituted through antiparallel IGBT. Drive circuit was composed of EXB841. EP1 C3T144C8 FPGA is adopted as commutation controller. This design meets the design requirements, it proved that the design can complete the experiments of MC, and show the availability and feasibility of this modulation strategy.