A Space Vector Pwm Algorithm For Three-Level Inverter Operation In Entire Modulation Range And Its Implementation

Since the advantages of the three-level inverter, such as large output power, high voltage utilization and less harmonic, it has been widely used in modern industry. The Space Vector Pulse Width Modulation(SVPWM) algorithm because of its wide modulation range, well waveform of output voltage and easy digital realizaiton, etc, gradually become a great focus of scientific research and industry fields. To meet the requirements for the motor output torque and inverter low voltage suitability, how to expand the modulation range and obtain the higher voltage utilizaiton become a important problem, which extremely need to be solved. In order to realize the Neutral Point Clamped (NPC) three-level inverter, the comprehensive algorithm’s points of SVPWM were studied in detail and mainly focus on the two kinds of overmodulation algorithm, which can support a feasible solution for the three-level inverter in entire modulaiton range.First of all, the topology structure and mechanism of the three level inverter were described in this paper. The basic principles in SVPWM algorithm were theoretical derived, Based on MATLAB/Simulink to build three level inverter SVPWM algorithm in the simulation model for its linear modulation.Secondly, the three-level inverter algorithm in overmodulation range was derived detailed. Draw lessons from the classical theory of two mode overmodulation algorithm for its partition method,two overmodualtion algorithms:one based on piecewise fitting and the other based on the superposition principle, were not only gived its analysis,but also the simulation model, and evaluated them according to its output performance and realizability.Then, analyzed the reason of neutral voltage fluctuations from the three-level inverter’s topology structure and introduced several kinds of commonly neutral voltage balance control strategy. Support a method based on conservation theorem, which can be used in wide modulation range,and build its simulation model in differernt dc side capacitor parameters.Finally, rapid control prototying experiment platform with dSPACE controller, three-level inverter and squirrel-cage three-phase asynchronous motor physical object was set up. The main circuit model of the SVPWM algorithm in entire modulation was built and completed on this platform. The validity and effectiveness of the modulate and control algorithm were proved by the experimental result.