Research On Fault Tolerant Control And Speed Regulation Of Synchronous Motor Based On Hybrid Flux Model

With the advantages of adjustable excitation current and power factor,the electric excitation synchronous motor is more suitable for speed regulation in high-power applications.But the synchronous motor has the characteristics of high-order coupling and difficult to control.This paper studies the T-type three-level topology modulation and new fault-tolerant control strategy,and adopts a double closed-loop vector control based on the hybrid flux model of filter and compensation scheme to control the speed of synchronous motor.Using T-type three-level topology,the three-level modulation method is analyzed.For the open-circuit failure of the bridge arm switch tube,analyze the current flow direction,and study the modulation method of vector rearrangement according to the two types of open circuit faults of the upper and lower half of the bridge arm and the open circuit of the neutral point bridge arm.The arm’s fault-tolerant control circuit analyzes the working principles of the two types of fault-tolerant circuits.The simulation verifies the correctness of the proposed circuit scheme and solves the problem of fault-tolerant control of the T-type three-level switch in different fault situations.According to the mathematical models of synchronous motors in three common coordinate systems,the parameters of the current inner loop,speed outer loop double closed-loop controller and the excitation circuit controller are designed and set.The design of the magnetic flux observation algorithm is an important part of vector control.Aiming at the problems that the current model is sensitive to motor parameters and the voltage model has an integral initial value deviation,an observation method of a hybrid air-gap flux linkage model based on filters and compensation schemes is proposed..This method not only enables the system to use the open-loop current model in the low-speed section,but also uses the adaptive voltage model in the high-speed section,while also achieving a smooth transition between the two models.This makes the method suitable for accurately observing the magnetic flux in the entire speed range and solving the problem of integral deviation.Four-stage speed curve makes the entire stroke of the synchronous motor more stable.The proposed control strategy was simulated and systematically experimentally studied using MATLAB and three-level frequency conversion control experimental schemes.The results verified the effectiveness of the adopted strategy.