Speed-Sensorless Direct Torque Control System Of Induction Motors' Design And Implementation

With the development of the power electronic and digital control technology, various types of motor control technologies are emerging. Among them, the direct torque control has received widespread attention for its novel control thoughts, simple control structure and excellent control performance. In order to meet the requirements of multi-motors coordination control, a new method based on the average stator flux-oriented control is proposed from the traditional DTC theory. By controlling the total stator current, the method has realized the purpose of the control of the average stator flux-component and average torque-component simultaneously. After the theoretical derivation, the feasibility of this method has been verified on the PSIM simulation platform.In addition, speed sensors installed in the AC drive system will make the system diseconomy, large and low-reliability. This paper focuses on the study of sensorless DTC for AC motors, first analyzes the direct speed estimation method and Model Reference Adaptive Control method. On this basis, a mutual MRAS method is proposed and applied in the single inverter drives double motors DTC system. Simulation results show that this new method has good speed identification performance in both low and high speed ranges.After the completion of the theoretical derivation and simulation, the hardware platform and the software are designed. The experimental results verify that the mutual MRAS method applied in the single inverter drives double motors DTC system has both good dynamic and steady performance.