Akshya Swain

An Optimal PID Controller for a Bidirectional Inductive Power Transfer System Using Multiobjective Genetic Algorithm

Bidirectional inductive power transfer (IPT) systems are suitable for applications that require wireless and two-way power transfer. However, these systems are high-order resonant networks in nature and, hence, design and implementation of an optimum proportional-integral-derivative (PID) controller using various conventional methods is an onerous exercise. Further, the design of a PID controller, meeting various and demanding specifications, is a multiobjective problem and direct optimization of the PID gains often lead to a nonconvex problem. To overcome the difficulties associated with the traditional PID tuning methods, this paper, therefore, proposes a derivative-free optimization technique, based on genetic algorithm (GA), to determine the optimal parameters of PID controllers used in bidirectional IPT systems. The GA determines the optimal gains at a reasonable computational cost and often does not get trapped in a local optimum. The performance of the GA-tuned controller is investigated using several objective functions and under various operating conditions in comparison to other traditional tuning methods. It was observed that the performance of the GA-based PID controller is dependent on the nature of the objective function and therefore an objective function, which is a weighted combination of rise time, settling time, and peak overshoot, is used in determining the parameters of the PID controller using multiobjective GA. Simulated and experimental results of a 1-kW prototype bidirectional IPT system are presented to demonstrate the effectiveness of the GA-tuned controller as well as to show that gain selection through multiobjective GA using the weighted objective function yields the best performance of the PID controller.

A Wireless Power Pickup Based on Directional Tuning Control of Magnetic Amplifier

This paper proposes a novel inductor-capacitor-inductor wireless power pickup with directional tuning control (DTC) for a magnetic amplifier. The proposed technique allows the power pickup to achieve full-range tuning/detuning operation to regulate power flow and maintain the output voltage to be constant. The method eliminates the tedious fine-tuning process associated with traditional fixed power pickup tuning methods and eases the component selection. Moreover, it can overcome the online circuit parameter variations and automatically achieve the maximum power transfer capacity when required. In order to meet dynamic load demands, a magnetic amplifier is used as a variable inductor and is controlled by a novel DTC algorithm to change the tuning condition of the power pickup. The effectiveness of the proposed power pickup and its applicability to general wireless power transfer applications have been demonstrated by both simulation and experimental results.

A Dynamic Multivariable State-Space Model for Bidirectional Inductive Power Transfer Systems

Bidirectional inductive power transfer (IPT) systems facilitate contactless power transfer between two sides, which are separated by an air gap, through weak magnetic coupling. Typical bidirectional IPT systems are essentially high-order resonant circuits and, therefore, difficult to both design and control without an accurate mathematical model, which is yet to be reported. This paper presents a dynamic model, which provides an accurate insight into the behavior of bidirectional IPT systems. The proposed state-space-based model is developed in a multivariable framework and mapped into frequency domain to compute the transfer function matrix of eight-order bidirectional IPT systems. The interaction between various control variables and degree of controllability of the system are analyzed from the relative gain array and singular values of the system. The validity of the proposed dynamic model is demonstrated by comparing the predicted behavior with that measured from a 1 kW prototype bidirectional IPT system under various operating conditions. Experimental results convincingly indicate that the proposed model accurately predicts the dynamical behavior of bidirectional IPT systems and can, therefore, be used as a valuable tool for transient analysis and optimum controller design.

Robust sensor fault estimation scheme for satellite attitude control systems

Abstract The present paper proposes two new schemes of sensor fault estimation for a class of nonlinear systems and investigates their performances by applying these to satellite control systems. Both of the schemes essentially transform the original system into two subsystems (subsystems 1 and 2), where subsystem-1 includes the effects of system uncertainties, but is free from sensor faults and subsystem-2 has sensor faults but without any uncertainties. Sensor faults in subsystem-2 are treated as actuator faults by using integral observer based approach. The effects of system uncertainties in subsystem-1 can be completely eliminated by a sliding mode observer (SMO). In the first scheme, the sensor faults present in subsystem-2 are estimated with arbitrary accuracy using a SMO. In the second scheme, the sensor faults are estimated by designing an adaptive observer (AO). The sufficient condition of stability of the proposed schemes has been derived and expressed as a linear matrix inequality (LMI) optimization problem and the design parameters of the observers are determined by using LMI techniques. The effectiveness of the schemes in estimating sensor faults is illustrated by considering an example of a satellite control system. The results of the simulation demonstrate that the proposed schemes can successfully estimate sensor faults even in the presence of system uncertainties.

Adaptive sliding mode control for a class of MIMO nonlinear systems with uncertainties

Abstract This paper proposes an adaptive scheme of designing sliding mode control (SMC) for affine class of multi-input multi-output (MIMO) nonlinear systems with uncertainty in the systems dynamics and control distribution gain. The proposed adaptive SMC does not require any a priori knowledge of the uncertainty bounds and therefore offers significant advantages over the non-adaptive schemes of SMC design. The closed loop stability conditions are derived based on Lyapunov theory. The effectiveness of the proposed approach is demonstrated via simulations considering an example of a two-link robot manipulator and has been found to be satisfactory.

Modeling, Sensitivity Analysis, and Controller Synthesis of Multipickup Bidirectional Inductive Power Transfer Systems

Inductive power transfer (IPT) systems are increasingly being used in numerous industrial applications, which essentially require power without any physical contacts. In contrast to unidirectional IPT systems, bidirectional IPT systems are inherently higher-order resonant networks and relatively complex in modeling, design, and control. The complexity further exacerbates with the increase in number of pickups or loads, making design and implementation of such systems a real challenge. This paper, therefore, develops a multivariable dynamic model for a multipickup bidirectional IPT system, which can provide an accurate insight into the behavior of this system and can be used for controller synthesis under variations of component values. The output sensitivity to various parameters and the interaction among various control variables and degree of controllability of the system are investigated using frequency domain analysis. The validity of the model is verified under various operating conditions by comparing the predicted behavior with a 1-kW prototype of a bidirectional IPT system with two pickups. Measured results convincingly demonstrate that the proposed model accurately predicts the dynamic behavior of bidirectional IPT systems with multiple pickups and can, therefore, be used as a valuable tool for both dynamic analysis and controller design.

A new contactiess power pick-up with continuous variable inductor control using magnetic amplifier

This paper proposes a new contactless power pickup with a LCL tuning circuit which utilizes the magnetic amplifier as a variable inductor. The tuning circuit of the power pick-up is based on the LCL configuration and provides a simple relationship between the open circuit voltage of the pick-up coil and the output voltage regardless of the load variation. The use of magnetic amplifier as a variable inductor offers significant advantages where the inductance is dynamically varied using a controller and BJT to deliver power under a variety of load conditions. The proposed method can significantly improve the overall performance of the ICPT (inductively coupled power transfer) system by producing continuous waveforms within the system at all times. Simulations based on PLECS (a Simulink toolbox) demonstrate that the new method can successfully control the output voltage resulting in satisfactory steady state performance.

Robust H∞ adaptive descriptor observer design for fault estimation of uncertain nonlinear systems

Abstract This paper proposes a novel fault estimation observer for both nonlinear descriptor and normal systems, which are subjected simultaneously to actuator faults, sensor faults and unstructured non-parametric uncertainties. The considered faults can be unbounded and can have many forms, such as abrupt faults, constant faults and high-frequency faults. Sufficient conditions for the existence of the proposed observer with an H ∞ performance have been derived based on Lyapunov stability theory, and expressed in terms of Bilinear Matrix Inequalities (BMIs) which are then converted into quasi-convex Linear Matrix Inequalities (LMIs) by using the cone complementarity linearization (CCL) algorithm. Simulated examples are presented to illustrate the effectiveness of the proposed observer for both descriptor systems and normal systems and have been shown to perform better than some of the existing methods of fault estimation.

Reducing Low-Cost INS Error Accumulation in Distance Estimation Using Self-Resetting

Error accumulation is one of the critical factors that limit the effective use of low-cost inertial navigation systems (INS) in tracking applications, especially during prolonged time intervals. This paper proposes an improved method to reduce the error accumulation by automatically resetting it in the INS-based systems. This method does not require any additional external sensors and reference systems and therefore offers various ad-vantages. Necessary calibration has been done to accurately evaluate the parameters used within the method. The perform-ance of this proposed resetting method has been experimentally evaluated by tracking the moving vehicles both in indoor and outdoor environments. Results of the experiments demonstrate that the proposed method can significantly reduce the INS errors and successfully recover the trajectories of the moving vehicles with an adequate accuracy.

An Overhead Free Clustering Algorithm for Wireless Sensor Networks

An overhead-free, fully distributed clustering algorithm is proposed to decompose wireless sensor networks, where nodes are initialized with either equivalent or different energy capacities, into a two-tier clustered hierarchical structure. Energy-rich nodes are assured to act as cluster heads (CH), and CHs are dispersed evenly over the network. In the new algorithm, a converting function, a multiplicatively increasing CH selection probability, and two backoff strategies are interwoven over three phases during the CH selection and placement. Via simulations, the performance of the proposed algorithm has been demonstrated considering representative network scenarios. The results show that our algorithm outperforms some existing clustering methods in extending the system lifetime and enlarging the network data capacity.