The Research On Control Strategy Of Carrier Phase Shifted Algorithm For Cells Cascaded High-Voltage Inverter

Energy crises and environmental problems have caused worldwide concerns to. the power-saving technology,which have led to both economic waste and social problems because of serious environmental pollution.The development of high power AC motor variable speed energy conservation device has meanings to reduce energy consumption of the industry. Cascaded multilevel inverter is widely used in the field of high-voltage frequency conversion and speed control because of its advantages of low switching frequency of IGBT,reduced harmonic content of the output voltage waveform and high input power factor.The paper first introduced the history and trend of high-level inverters,from AC-AC to AC-DC-AC inverters,analyzed the development direction.Then introdeced several common multilevel inverter topologies and their merits and drawbacks,including diode clamped topology,capacitor clamped topology,general clamped topology,etc.Cascaded multilevel inverter is presented seperately.Control algorithms applied to cascaded multilevel inverter are analyzed in detail in the paper,including optimized PWM algorithm,multicarrier control algorithm.On purpose of optimizing the PWM control algorithm,a novel multicarrier control algorithm is proposed based on control degrees of freedom,MATLAB simulation model is built,simulation results show that the control algorithm proposed has good advantages of output voltage harmonic and voltage utility ratio aspects.Based on the theoretical analysis, a PWM pulse-generating circuit using the method of structing memory in FPGA and combines the DSP to implement multi-PWM with carrier phase shifted in real-time is designed,experimental results show that the improved multicarrier conrol algorithm performs better.The MCU is TMS320LF2812 microprocessor,combined with practice,the control panel and power cell driven circuits are designed,moreover the paper has analyzed and compared the inverter voltage and current outputs using different modulation algrithms..According to the starting of the motor with load and no load,the reliability and stability of the inverter characteristic is proved.