Huimin Ouyang

Load vibration reduction in rotary cranes using robust two-degree-of-freedom control approach

In the control of the rotary crane, it is important to consider the trade-off between the boom positioning characteristics and the sway of the load. However, it seems difficult to obtain good control performance in both of them using 1-degree-of-freedom control approach. Therefore, a robust 2-degree-of-freedom control approach is proposed in this article. First, a linear dynamic model of a rotary crane is derived using a disturbance observer. Next, a state feedback controller with integrator is designed based on the model, and controller gains are determined by using linear matrix inequality optimization for achieving robustness with respect to rope length variance. Then, a feedforward controller is designed by solving an optimal regulator problem based on the model of closed-loop system for improving the boom positioning characteristics of the crane. Finally, the experimental results confirm the effectiveness of the proposed method. Hence, the crane can be easily operated without sensor systems for measuring rope length, and consequently, the structure of the crane can be simplified and implementation cost can be reduced.

Vibration suppression in rotor system of magnetic suspended wind turbines using double stage cross feedback control

Because the gyroscopic coupling effect and the imbalance force typically generate undesirable vibrations in the rotor system of magnetic suspended wind turbines when they rotate under high speed situation, a novel cross feedback based control method is proposed. Firstly, the dynamic model of a radial four-degree-of-freedom active magnetic bearing rotor system is derived. Next, a double stage cross feedback controller is designed for suppressing the vibration caused by the gyroscopic coupling effect. Moreover, an integrator and a second order low pass filter are used to improve rotor positioning performance with disturbance. Finally, better steady accuracy and disturbance rejection performance are obtained by the proposed method through comparing with a LQR controller and a traditional cross feedback controller numerically.

Vibration suppression for rotor system of magnetic suspended wind turbines using cross-feedback-based sliding mode control

This paper proposed a novel method which is the combination of traditional cross feedback control and sliding mode control for the problem of gyroscopic coupling and imbalance disturbance in the rotor system of magnetic suspended wind turbines when they rotate under high speed situation. Firstly, the mathematical model of a radial four-degree-of-freedom active magnetic bearing rotor system is derived. Then, a sliding mode controller is designed after decoupling the model by using cross feedback control method. The stability of the whole system is guaranteed by the Lyapunov stability theory. Better robustness and regulation performance is obtained through comparing with a traditional decentralized PID-based cross feedback controller numerically.

Vibration suppression for flywheel energy storage system using modal decoupling control

Magnetic bearings have been used in flywheel energy storage systems to improve their performance because these kinds of bearings can provide non-contact supporting so that the friction between the rotor and the bearings is reduced significantly. However, the gyroscopic coupling, parameter coupling, and imbalance force affect the operating performance and stability of a magnetic suspended flywheel energy storage system with asymmetric rotor; therefore, the main purpose of this study is to propose a control method for achieving decoupling and stable operation of the aforementioned system. To this end, after deriving the mathematical model of a radial 4-degree-of-freedom rotor–bearing system, a novel cross-feedback-based modal decoupling controller is designed for vibration suppression caused by gyroscopic coupling, parameter coupling, and imbalance force. Better performance is obtained through comparing the decoupling performance, control performance, and disturbance rejection performance with a traditional decentralized proportional–integral–derivative controller and a cross-feedback controller via ADAMS–MATLAB co-simulation technology and experimental results.

Filter design at the output of the inverter in PMSM drives

This paper aims to describe a simple low-pass filter to suppress torque pulsation and current harmonics in permanent magnet synchronous motor (PMSM) drives.,For the control of the PMSM, a field-oriented control algorithm is always used. The proposed filter is actually a resistance, inductance, capacitance (RLC) filter. At the output of the inverter and the input of PMSM, an RLC filter is connected. This filter suppresses current harmonics through filtering phase voltage harmonics. Analysis of the filter is achieved through frequency characteristics analysis.,This filter can effectively filter out the harmonic of phase voltage. Both the simulation and experiment results show that the proposed filter can effectively suppress torque pulsation and current harmonics in PMSM drives. Also, the method of selecting filter parameters and the whole control system are very simple.,The filter increases the design cost of the system.,The harmonics and torque ripple of phase current are greatly suppressed. Also, the loss of the PMSM reduced.,The method of selecting filter parameters and the analysis of the proposed filter are proposed for the first time.

Modal Decoupling Control for Magnetic Suspended Flywheel Rotor

Magnetic bearings have been used in flywheel energy storage systems for improving their performance due to the main advantage of contact-free operation. However, the gyroscopic coupling, parameter coupling and imbalance force affect the operating performance and stability of an magnetic suspended flywheel energy storage system with asymmetric rotor, therefore, a cross feedback based control method is proposed. Firstly, the dynamic model of a radial four-degree-of-freedom active magnetic bearing rotor system is derived. Next, a novel cross-feedback-based modal decoupling controller is designed for vibration suppression caused by gyroscopic coupling, parameter coupling and imbalance force. Better performance is obtained through comparing the decoupling performance, control performance and disturbance rejection performance with a traditional decentralized PID and a cross feedback controller.

Stability analysis of full order observer based speed sensorless induction motor drive

Stability of full order flux observer based speed sensorless control system is studied in the paper. By small signal analysis method, the whole control system is linearized and transfer function from speed reference to practical speed is obtained. Examining pole distribution of transfer function, stability analysis is carried out. The impact of motor parameter error on speed identification system is considered. Besides, research is made on the relation between lowering bandwidth of speed identification loop and control loop and improving speed sensorless control system stability. Simulation and experiment results validate the analysis in the paper.