Introduction

Author(s):  
Sadegh Vaez-Zadeh

An overview of permanent magnet synchronous (PMS) motors and the related control system are presented in this chapter as introductory materials for the rest of the book. The interconnections of the control system to the power electronic inverter and the motor are emphasized. In addition, the major parts of the system are overviewed. Pulse width-modulated voltage source inverter, as the most commonly used power converter in PMS motor drives, is briefly discussed. PMS motors configurations and operating principles are also presented after considering characteristics of permanent magnet materials. Major PMS motor control methods including vector control, direct torque control, predictive control, deadbeat control, and combined vector and direct torque control are briefly reviewed. Finally, several rotor position and speed estimation schemes, and offline and online parameter estimation methods are overviewed.

Author(s):  
Xiaoxin Hou ◽  
Mingqian Wang ◽  
Guodong You ◽  
Jinming Pan ◽  
Xiating Xu ◽  
...  

The traditional direct torque control system of permanent magnet synchronous motor has many problems, such as large torque ripple and variable switching frequency. In order to improve the dynamic and static performance of the control system, a new torque control idea and speed sensorless control scheme are proposed in this paper. First, by deriving the equation of torque change rate, an improved torque controller is designed to replace the torque hysteresis controller of the traditional direct torque control. The improved direct torque control strategy can significantly reduce the torque ripple and keep the switching frequency constant. Then, based on the improved direct torque control and considering the sensitivity of the stator resistance to temperature change, a speed estimator based on the model reference adaptive method is designed. This method realizes the stator resistance on-line identification and further improves the control precision of the system. The performance of the traditional direct torque control and the improved direct torque control are compared by simulation and experiment under different operating conditions. The simulation and experimental results are presented to support the validity and effectiveness of the proposed method.


Author(s):  
Tibor Vajsz ◽  
László Számel ◽  
György Rácz

Direct torque control with space vector modulation (DTC-SVM) is one of the most promising alternatives of field-oriented control in the case of permanent magnet synchronous motor drives. This method controls the electromagnetic torque of the motor with excellent dynamics which makes it an attractive choice in the case of servo drives. In this article DTC-SVM is investigated with Matlab-Simulink simulation and it is proven that DTC-SVM has severe instability-issues during overloading and its overload-capabilities are heavily dependent on the speed. Therefore, a novel modified DTC-SVM method is proposed which is stable during overloading and its overload-capabilities are practically independent of the speed. Also, the overload-capability of the new method is superior to that of classical DTC-SVM, while the two methods are practically identical from the point of view of the torque-control dynamics and the torque-ripple generated.


2013 ◽  
Vol 341-342 ◽  
pp. 1013-1017
Author(s):  
Yi Ming Li ◽  
Wei Huang ◽  
Peng Jin ◽  
Jun Rong

According to the analysis of mathematical model for permanent magnet synchronous motor (PMSM), direct torque control(DTC) technology is introduced to the control system of PMSM. The paper builds dual-closed loop control system of PMSM, and the outer loop is speed loop, the inner loop is flux and torque loop, at the same time, the paper makes simulation in Matlab/Simulink. The simulation results show that the DTC technology significantly improves the dynamic performances of PMSM, and the control system is no overshoot, and has small flux response comparing with the conventional control methods of PMSM. So the application of DTC technology in PMSM provides a new thoughtful way for PMSM control system designing and debugging in actual application.


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