A Three-Level DTC System Based on Virtual Space Vector Modulation for Bearingless Permanent Magnet Synchronous Motor

2014 ◽  
Vol 703 ◽  
pp. 356-359 ◽  
Author(s):  
Yu Xin Sun ◽  
Chang Sheng Xu ◽  
Huang Qiu Zhu

In This paper, a direct torque control (DTC) method for bearingless permanent magnet synchronous motor (BPMSM) based on three-level neutral-point clamped (NPC) inverter is described. Through the analysis of virtual space vector modulation, an independent control strategy is adopted into the suspension winding control and a flux linkage error vector SVM-DTC method supplied by three-level NPC inverter is introduced into the torque windings control. By using the proposed control strategy, the neutral-point voltage variation can be greatly limited and the voltage shifting can be eliminated. The results of simulation verify the feasibility of the control algorithm, the dv/dt of output voltage and the torque ripple are restrained effectively, satisfactory robustness and the good performance of the radial levitation can be achieved in a wide speed range by using the proposed method.

Author(s):  
Bowen Ning ◽  
Shanmei Cheng ◽  
Baokang Yan ◽  
Fengxing Zhou

This study investigates the direct torque control strategy of permanent magnet synchronous motor with the space vector modulation, on account of large torque fluctuation and varied switching frequency of classic direct torque control strategy. The relationship among the terminal control voltages and the torque and stator flux of the permanent magnet synchronous motor is derived through the dynamic model of motor. Accordingly, the torque and the flux closed-loop feedback control structure are established, where the error signals are regulated by the proportional and integral controllers to generate output voltages. Furthermore, the parameters of the controllers are designed through explicitly analyzing the frequency domain models of the torque control loop and the flux control loop. The accurate calculation formula of control parameters, which has both explicit setting target and definite physical meaning, is obtained. Therefore, the design of torque and flux controller parameters becomes easy in the direct torque control with space vector modulation technology, and satisfactory flux and torque control can be acquired. Finally, simulation and experimental tests are demonstrated in support of the validity of the investigated scheme and the feasibility of the proposed controller parameter design.


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