Cascade Adaptive Control Research Articles

Sampled‐data adaptive nonlinear control of shunt power filters

AbstractThis study is on the control of shunt power filters associated with nonlinear loads. Specifically, The focus is made on single‐phase half‐bridge filters and the aim is to design a controller meeting two requirements: (1) the effect of current harmonics and reactive power is compensated for so that a power factor close to unity is achieved at the point of common coupling (PCC); (2) the inverter DC bus voltage is satisfactorily regulated. To meet these requirements, we propose a (two‐loop) cascade adaptive controller that is designed on the basis of the system nonlinear model, using Lyapunov stability tools. Compared to existing controllers, the present controller has three major features. It is adaptive compensating for parameter uncertainty. It is output feedback in the sense that it involves an observer estimating online the inaccessible signals. It is sampled‐data and so is immediately implementable using digital means. In addition to theoretical analysis, the performances of the proposed controller are evaluated by simulation using MATLAB/Simulink.

Speed cascade adaptive control for hybrid electric vehicle using electronic throttle control during car-following process

Achieving robust longitudinal speed control for hybrid electric vehicles (HEVs) through precise position tracking of electric throttle control system (ETCS) can improve engine fuel economy and vehicle longitudinal speed performance. Whereas, nonlinearities resulting from friction, gearbox, and return springs of ETCS, uncertain system parameters related to production deviations and device aging, disturbance from the air flow fluctuation on the throttle plate, and unknown road grade and uncertain preceding vehicle acceleration make control design challenging. Aiming at this issue, a speed cascade control scheme considering car-following scenario is investigated for a parallel ETCS controlled HEV in this paper, of which contains a primary speed adaptive controller and a secondary electronic throttle adaptive nonlinear active disturbance rejection controller with the adaptive gains extended state observer. The distinction from the existing relevant literatures is that the inherent characteristics of nonlinearity and uncertainty in the ETCS and longitudinal velocity kinematics, and the car following scenarios are explicitly taken into account in the design of the cascade control for ETCS controlled HEVs. Both simulation and rapid-control-prototype (RCP) experimental results demonstrate the effectiveness and practicality of the proposed scheme and the advantages over other existing research strategies.

English

English

Design and implementation of an advanced controller in plant distributed control system for improving control of non-linear belt weigh feeder

A Belt Weigh Feeder (BWF) is a flat belt conveyor designed for feeding bulk material into a chemical process in a controlled fashion for better process control. The dynamic weight of bulk material is measured with a belt weigh bridge and the belt speed is controlled to compensate for any variation in the weight so that the mass feed rate is maintained as per the set feed rate. The problem of belt speed control is challenging as the dynamic response of system is non-linear and there are frequent changes in belt load due to variation in bulk material characteristics. The control accuracy of belt weigh feeder is fully dependent on the controller’s performance in providing precise control of speed of motor/belt. Any delay in achieving the set feed rate or frequent deviation between set and actual feed rate affects the quality and efficiency of downstream process. Conventional PI controller is unable to provide optimum control due to system non-linearity. To overcome this problem, in this paper first the operating data of the BWF system is analysed and the nature and cause for the nonlinearity is investigated. The system is then modelled using the design parameters of plant belt weigh feeder, which is then simulated to have a better insight into its non-linear response. Subsequently, based on simulation results, a PI Fuzzy Logic (PI-FL) controller is designed to improve the control accuracy of the system. Further, to ensure the stability of the system, an adaptive controller is introduced in cascade to fine tune the gains of PI-FL controller as per the operating speed of the BWF. Finally, an advanced PI-FL with cascade adaptive controller is implemented in the plant DCS (microprocessor based process control system). The actual test results indicate reduction in the Integral of Absolute Error (IAE) of the system by about 34% using this controller.

Controlling Chaos in Permanent Magnet Synchronous Motors by Cascade Adaptive Approach

Chaotic phenomena in permanent magnet synchronous motors (PMSM) can be observed when parameters in PMSM are in a certain range. In general, chaos will degrade the performance of PMSM or even collapse the system. In order to suppress the chaos in PMSM, cascade adaptive control is utilized in this paper. Faithful model of PMSM is not necessarily required by using adaptive control based on dynamic compensation mechanism. By choosing appropriate controller parameters, chaos will be eliminated and the response speed can be tunable. Numerical simulation results for nominal case and parameter perturbation case are given out to confirm the cascade adaptive control is valid in chaos control of PMSM.

Cascade adaptive control of uncertain unified chaotic systems

The chaos control of uncertain unified chaotic systems is considered. Cascade adaptive control approach with only one control input is presented to stabilize states of the uncertain unified chaotic system at the zero equilibrium point. Since an adaptive controller based on dynamic compensation mechanism is employed, the exact model of the unified chaotic system is not necessarily required. By choosing appropriate controller parameters, chaotic phenomenon can be suppressed and the response speed is tunable. Sufficient condition for the asymptotic stability of the approach is derived. Numerical simulation results confirm that the cascade adaptive control approach with only one control signal is valid in chaos control of uncertain unified chaotic systems.