Yongdong Li
Tsinghua University
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Publication
Featured researches published by Yongdong Li.
power electronics specialists conference | 2001
Zhuohui Tan; Yongdong Li; Min Li
The multilevel inverter has attracted great interest in the high-voltage high-power field because of its less distorted output. In this paper, a direct torque control (DTC) technique based on a three-level neutral-point-clamped (NPC) inverter is presented. In order to solve the intrinsic neutral-point voltage-balancing problem and to obtain a high performance DTC, a special vector selection method is introduced and the concept of virtual vector is developed. By using the proposed control strategy, a quick and robust response AC drive can be achieved without sensing the neutral-point voltage. The strategy can be verified by simulation and experimental results.
power electronics specialists conference | 1994
Jun Hu; Dongqi Zhu; Yongdong Li; Jingde Gao
This paper proposes a new control method for shaft sensorless permanent magnet synchronous motor drive systems. The rotor position and speed are estimated by using a sliding observer with only stator voltage and current measurements. The observer structure and its design method are discussed. The simulation results of the overall system are presented to demonstrate the effectiveness of the approach.<<ETX>>
conference of the industrial electronics society | 2003
Hu Hu; Yongdong Li
In this paper, the torque ripples in low speed range of conventional direct torque control are discussed in detail, and a new vector selection table based on area voltage is proposed to control the torque and flux. In this case, two predictive control schemes of torque and flux are presented to reduce torque ripples and improve the steady and dynamic performance. Finally, simulations and experiment results are given to show the validity and the advantages of the proposed predictive schemes based on area voltage vector table.
international power electronics and motion control conference | 2000
Jixiong Wu; Yongdong Li; Jie Chen; Hu Hu
This paper presents a practical improvement to the conventional stator flux estimator for digital direct torque control of an induction motor, in which the predictive torque control is adapted to decrease the torque ripple. In addition, the slip frequency estimation method of speed is proposed to get a fast and rather precise speed control, leading to a high performance direct torque control of an induction motor in low speed region. Finally the experimental results show the validity of the proposed method.
ieee international conference on power system technology | 2002
Hu Hu; Yongdong Li
In this paper, schemes of direct torque control (DTC) for railway traction over the whole speed range are proposed. In order to observe the phase angle and amplitude of stator flux accurately, a flux observer based on a U-N model is presented. In the low-speed range, the locus of stator flux is controlled to be a circle to reduce torque ripples, and the schemes of start-up and the selection method of voltage vectors are proposed in this paper. In medium-speed and high-speed range, the locus of stator flux is controlled to be hexagonal to reduce switching frequency. In order to obtain good steady state and dynamic performance, a DTC scheme under square wave conditions in the high-speed range is proposed. All of the methods and schemes are implemented on a 500 kW converter and a 190 kW induction motor, and are proved to be effective by experiment results.
international power electronics and motion control conference | 2004
Guofeng Yuan; Jianyun Chai; Yongdong Li
Microporous and Mesoporous Materials | 2001
Yongdong Li; Hu Hu; Jie Chen; Jixiong Wu
Procedia - Social and Behavioral Sciences | 2004
Geng Wang; Yongdong Li; Xiaojie You
international conference on performance engineering | 2001
Zhuohui Tan; Yongdong Li; Hu Hu; Min Li; Jie Chen