The Simulation Research On Sensorless Vector Control System Of The Modular Multi-level High-voltage Inverter

In China, the operating efficiency of the motor system is actually extremely low. Especially in the domain of high-voltage electrical motor, the electric efficiency is lower than world average level by30%. Therefore, it is of crucial importance for China’s energy conservation to improve the high-voltage frequency control technology. The modular multi-level high-voltage inverter owns low harmonic pollution, good output waveform, high reliability and it does not require input filter and power compensation devices, which results that it is widely applied in the high-voltage frequency conversion domain.In this paper, topologic structure, the operating principle the modulation algorithm and the control method of the modular multi-level high-voltage inverter are discussed in details, and speed sensorless vector control technology is adopted for the modular multi-level high-voltage inverter.Firstly, this paper describes the research status and development trends of modular multi-level high-voltage inverters and introduces the topologic structure of main circuit as well as the operating principle. On this basis, the multi-carrier PWM modulation algorithm is chosen as the main research object. And the carrier lamination together with the carrier phase-shifted sinusoidal pulse width modulation (SPWM) control principles is analyzed in detail by building the simulation model. Simulation results show that the carrier phase-shift SPWM algorithm can improve the equivalent switching frequency and reduce the output voltage harmonics, besides, it generates three-phase good sinusoidal currents.Secondly, the paper focus an in-depth research on the theories of three kinds of flux observations consisting of the voltage-current model, the current-speed model and the improved voltage-current model. Besides, the advantages and disadvantages of the voltage-current model and the current-speed model were analyzed, and the functions in eliminating the integral initial value error and depressing the input dc effect of the three improved voltage models were analyzed and compared in this paper. Also, the simulation models were built and the results show that the limited compensation improved voltage model owns a good performance on eliminating the waveform distortion and reducing the dc component. In terms of the speed identification, this paper analyzes the model reference adaptive speed identification theory. Based on the theory, the simulation models are built and the results show that the method has good performance.Finally, the paper analyzes the design principles of speed sensorless vector control system for the multi-level high-voltage inverter in detail. And, simulation in Matlab/Simulink was performed, which have verified the correctness and effectiveness of the theoretical analysis.