Research On Three-level Inverter Direct Torque Control

Direct torque control(DTC) is a new type frequency control technology and has many issues that need our study. This paper focuses on the two level inverter direct torque control and three-level inverter direct torque control, which has received good purposes. The paper has effective function in multilevel inverter direct torque control (DTC) system.Firstly, the paper analyses the principle and configuration of DTC, then it builds mathematics models of motor based on stator stationary coordinates and establishes three observation models of flux linkage. On the foundation of vector, the paper analyses the spatial region judgement,flux linkage,orque and current's coordination control. Finally, the paper puts forward to a logic gate controlled strategy of current and simulates the two level inverter direct torque control. The results show that this method can achieve better function on restraining overcurrent .Under the basis of these investigation, it analyses the principle and configuration of DTC about the three-level inverter DTC. The work principle,work process and switch model of diode-clamped three-level inverter are discussed. Its mathematics models are built between three-level inverter and motor. In the paper, the reasons of neutral-point potential fluctuation are discussed. It gives a three-level inverter direct torque control way based on fixation complex vector. Finally, the simulations show good effects in balancing neutral-point potential fluctuation and reducing voltage swing.