Three-level High Power Variable Frequency Speed Sensorless Vector Control System

The multilevel technology is an important topological form suitable for high voltage and high-power electric energy transform. The basic theory of three level inverter is studied in this paper and the inverter control of space vector pulse width modulation (SVPWM) is also researched. Then the mathematic model of induction system with three-level inverter drive is proposed. The causes of neutral point voltage bias are analyzed. In order to improve some common used control methods of neutral point voltage, a strategy of parameter self-commission fuzzy control is proposed. This algorithm has better adaptability and robustness for neutral point of three-level, a nonlinear time varying object. Besides, the static and dynamic error could be controlled in a low extent. With this algorithm, the balance of neutral point could be achieved.Speed sensorless vector control of induction motor could achieve high performance by coordinate transformation. This control method omits the speed sensor, reduces the cost and improves the reliability of system, making it possible for more severe environment. Speed sensorless vector control has become a hot research point of modern motor drive field. In this paper, researches are focused on speed sensorless vector control system based on full-order state obsever.In this dissertation, the mathematic model of induction motor is constructed based on coordinate transformation. Then the principle of vector control is analyzed. A voltage decoupling control mode of voltage source three level inverter drives is also offered. According to model reference adaptive theory, two model reference adaptive methods are introduced. One is based on rotor flux and the other is based on full-order state observer. An improved voltage reference model is analyzed, the simulation and experimental results are also given. The speed sensorless vector control system based on full-order state observer is mainly focused in the dissertation. The state estimation error under different discrete mode of full-order state observer and the reconstruction of observer input voltage are researched. The pole distribution principle of full-order state observer in full speed range is given to guide the design of feedback matrix.In order to improve the control in low speed range, the dead time compensation of SVPWM and inverter tube pressure drop compensation technology are reaseached.At last, the theories above are proved by systematic experiments through the platform of speed sensorless vector control system based on full-order flux observer.