A Simulation And Realization On Cascaded Multi-level High Voltage Converter Carrier Phase Shift Technology

Converter has ideal speed performance and significant energy-saving effect, in which cascaded multi-level high voltage converter with advanced technology and excellent reliability, has been widely used and developed towards high-capacity, high performance, redundant design and excellent reliability rapidly.This paper described a variety of high-voltage inverter topologies and methods of induction motor speed control, focusing on analysis of cascaded multi-level high voltage converter circuit topology, power unit topology and the work principle. A variety of high-voltage inverter control strategies were introduced and a comparative analysis of multi-level inverter carrier-based modulation and phase shift amplitude modulation was made.Moreover, basic principles of the carrier phase shift pulse width modulation (SPWM) technology was researched and a simulation model in MATLAB of cascaded multi-level high voltage converter was created with a six power units cascaded for example, and simulation for carrier phase shift SPWM technology as the control method was analyzed as well. Simulation results show that cascaded multi-level high voltage converter output voltage ladder number are far more than traditional two-level and three-level inverter. The phase voltage reaches to 13 voltage levels and line voltage arrives at 25 voltage levels, which is consistent with the theoretical analysis and has very perfect output voltage and current waveforms and low harmonic content and total harmonic distortion.When six power units cascade, the high voltage converter has 18 power units requiring for 36 roads of pulses. According to that the digital signal processor (DSP) used in current motors can only provide up to 16 pulses, a carrier phase shift SPWM technology realized by the connection of DSP and logic programmable gate array (FPGA) is proposed. In this way, DSP is used to calculate in formula sample methods for SPWM pulses, and FPGA is taken to create 36-way pulse control signals for SPWM when six power units cascade.A development item based on 6kV-900kW type cascaded multi-level high voltage converter has been experimented. Experimental results show the feasibility of the method, and the input harmonic is little, power factor is high, output voltage waveform is close to sinusoidal wave, changes is in low level and numbers of electrical levels are according with M=2N+1. Meanwhile, the system has high anti-jamming capability and reliability, and can run sustainable drop volume while fault occurs to reduce downtime loss. As a result, relevant basis for further study of the content is settled.