The Research On A Novel Control For Cells Cascaded High-Voltage Inverter

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.The most commonly used modulation method-" phase shift SPWM " for HBCMIis taken as the foundation of this paper.The " new carrier reverse phase shift SPWM"and" new carrier same phase shift SPWM " are taken out by changing the doublepolarity carrier of phase shift SPWM to " reverse single polarity carrier "and" samephase polarity carrier " respectively.The modulation mode can effectively reduceswitch loss because the power switching device remains on or off state for half a cyclein each cycle of modulation wave.With the launch of the new carrier phase shiftSPWM,"variable ring width constant frequency current hysteresis control method" istaken out by changing its pulses producing way by the comparing of triangle carrierand sine wave to current hysteresis control which can realize the fast track of inverteractual output current to given current.This paper finally makes engineering design for the application of HBCMI in thefield of high voltage variable frequency.The paper gives out the main circuit’shardware and software design to HBCMI,which includes multi-channel pulse triggerdesign based on FPGA, the main control circuit’s hardware design and part softwaredesign based on DSP, etc.The proposed all kinds of modulation method for HBCMIare validated in the engineering device of high voltage inverter and it gives out allthe waveforms which verifys the correctness of the proposed modulation methods.