The Research On Cascaded High Voltage Converter And Its Vector Control

The technology to adjust speed with variable frequency and high voltage is acommanding heights technology in the field of power electronic,which involves speedregulation and energy-saving for high power ac motor with all kinds of load.Highvoltage inverter has not a mature and consistent topological structure as low voltageinverter.H bridge cascaded multilevel inverter(HBCMI) is becoming the maintopological structure of high-voltage inverter because of the features of the modulardesign,the use of low voltage components to realize high voltage output,thefacilitating of fault redundancy design for inverter,etc.The modulation method is thehot issue and difficulty in study for HBCMI due to the need of real-time control tomany power switch devices. This paper researchs and puts forward differentmodulation method suitable for HBCMI, and looks for the relationship and disciplinebetween them.It makes the theory analysis, simulation and experimental validation fordifferent modulation method,and provides some effective methods to improve thecontrol performance for HBCMI in the field of high voltage variable frequency.In this paper, based on the phase shift SPWM of HBCMI,"phase shift SVPWM"is launched by the changing of implementing pulse to SVPWM.SVPWM is widelyapplied in high performance vector control for two level inverter.SVPWM actually isevolved by SPWM.SVPWM is only applied to two level inverter with eight switchstates and can not be directly applied to HBCMI with a large switch states.The outputvoltage of HBCMI is the difference value between two level inverter group outputvoltage formed by left bridge arms of all H bridges and two level inverter groupoutput voltage formed by right bridge arms of all H bridges from the topology ofHBCMI.So a suitable modulation of "phase shift SVPWM" is introduced for HBCMIby the use of phase shift principle and SVPWM.This paper also makes research on“rotor field-oriented vector control"to motor by the implementing of HBCMI’s phaseshift SVPWM.The paper not only makes theoretical analysis to the above proposed all sorts ofmodulation methods,but also gives a large number of simulation waveform to provethe modulation methods correct and effective at the same time.This paper finally makes engineering design for the application of HBCMI in thefield of high voltage variable frequency,and gives out the main circuit’s hardware and software design to HBCMI.