The Research On High Voltage Variable Frequency Variable Speed System Based On Five-level Neutral-point-clamped(NPC) H-bridge Inverter

High voltage variable frequency variable speed device has a broad marketprospect, research on the high voltage variable frequency variable speed technology isof great significance for energy saving, environmental protection and promote thedevelopment and application of high voltage variable frequency variable speedtechnology. High voltage variable frequency variable speed technology related toelectricity, electronics, electrical, information and control fields. The focus researchof this paper is the power converter and its pulse width modulation technique of thehigh voltage variable frequency variable speed system and the motor vector controltechnology.This paper describes the background and significance for the research of highvoltage variable frequency variable speed system, analyzes the application of highvoltage frequency converter and the research status and development trend of highvoltage variable frequency speed control technology at home and abroad. Introducesthe basic structure and several common topology of main circuit and theircharacteristics for high voltage frequency converter, and used the neutral-pointclamped H bridge five level inverter as the main circuit of the high voltage invertertopology.The topology structure of the main circuit for high voltage frequencyconverter based on the neutral point clamped H-bridge five level inverter arepresented in this paper.This paper on the basis of the topology of five-level neutral point clamped (NPC)H-Bridge inverter and its operating principle, proposes a novel algorithm of spacevector pulse width modulation (SVPWM), which can be applied to the five-levelinverter. In this algorithm, reference voltage position is located by twelve judgingrules, and in order to avoid the abrupt change of output voltage vectors during theprocess of desired vector changing from one section to another, used the method thatmade the output vector changes of the two adjacent triangle in the opposite direction.In this paper, the implementation approachs and concrete steps for the algorithm usedto control five-level inverter are studied with simulation. The simulation results showthat the proposed algorithm is correct and effective, the harmonics of inverter outputvoltage are significantly reduced and the amplitude of fundamental voltage alsoincreased significantly compared with the traditional SPWM method. A control circuitbased on DSP and FPGA has been designed, and the FPGA are used to implement the SVPWM algorithm. In this paper, the implementation approachs and concrete stepsfor the algorithm by used of FPGA are gived, and using the Quartus II software tosimulated and experimental for the algorithm.The simulation and experimentalresults are consistent with the theoretical calculation, it showed that the design iscorrect and effective.This paper on the basis of the mathematical model of the AC induction motor andthe basic principles of rotor field oriented vector control, in the Matlab/Simulinkenvironment built the simulation models that based on space voltage vector pulsewidth modulation (SVPWM) and five-level inverter control system. Finally, made thesimulation study of the entire control system, the simulation results show that thevector variable frequency control system has good static and dynamic performance,the response speed of speed and torque is fast, have a small torque ripple, and thedisturbance rejection ability is good, validate the control algorithm. the simulationalgorithm for further study of frequency control system of the digital realization of acertain value.