Port-controlled Hamiltonian Model Research Articles

Path-Tracking Cascade Control of Hydraulic-Tracked Vehicles Based on Port-Controlled Hamiltonian Model

Path-Tracking Cascade Control of Hydraulic-Tracked Vehicles Based on Port-Controlled Hamiltonian Model

Passivity-Based Control of Single-Phase Cascaded H-Bridge Grid-Connected Photovoltaic Inverter

This article presents a nonlinear passivity-based control for a grid-connected cascaded H-bridge (CHB) photovoltaic (PV) system. The proposed control system is based on a port-controlled Hamiltonian model extracted from the synchronous reference frame system. Grid current dynamics is included in this model. Compared to existing solutions, the proposed control method has a robust performance and enhances the stability of the CHB-based PV system in the case of disturbances such as unequal irradiance over distinct PV arrays or a sudden sag or swell in the grid voltage. This controller also provides the independent control of each dc-link voltage. Therefore, the individual maximum power point tracking algorithms can be realized in each PV array, and the harvested energy can be maximized. Finally, simulation results and experimental investigations are conducted to verify the effectiveness of the proposed strategy.

Robust Stable Limit Cycle Generation in Multi-Input Mechanical Systems

SUMMARYThis paper proposes a robust controller for the generation of stable limit cycles in multi-input mechanical systems subjected to model uncertainties. The proposed idea is based on Port-Controlled Hamiltonian (PCH) model and energy-based control by considering the Hamiltonian function as the Lyapunov function. For this purpose, first, a nominal controller is designed by shaping the energy function of the system according to the structure of the desired limit cycle. Then, an additional robustifying control term is designed based on the integral sliding mode method with the selection of an appropriate sliding surface. Finally, computer simulations for two practical case studies are provided to confirm the effectiveness of the proposed controller in the generation of stable limit cycles in the presence of uncertainties.

Optimal Task-Invariant Energetic Control for a Knee-Ankle Exoskeleton

Task-invariant control methods for powered exoskeletons provide flexibility in assisting humans across multiple activities and environments. Energy shaping control serves this purpose by altering the human body's dynamic characteristics in closed loop. Our previous work on potential energy shaping alters the gravitational vector to reduce the user's perceived gravity, but this method cannot provide velocity-dependent assistance. The interconnection and damping assignment passivity-based control (IDA-PBC) method provides more freedom to shape a dynamical system's energy through the interconnection structure of a port-controlled Hamiltonian system model. This letter derives a novel energetic control strategy based on IDA-PBC for a backdrivable knee-ankle exoskeleton. The control law provides torques that depend on various basis functions related to gravitational and gyroscopic terms. We optimize a set of constant weighting parameters for these basis functions to obtain a control law that produces able-bodied joint torques during walking on multiple ground slopes. We perform experiments with an able-bodied human subject wearing a knee-ankle exoskeleton to demonstrate reduced activation in certain lower-limb muscles.

L2-Gain Adaptive Robust Control for Hybrid Energy Storage System in Electric Vehicles

The underlying voltage/current tracking control is a key issue for a hybrid energy storage system (HESS) in electric vehicles. This article presents an innovative passivity-based L2-gain adaptive robust control (L2-ARC) method for a fully active battery/super-capacitor HESS. First, by exploiting and analyzing the internal structural properties, the port-controlled Hamiltonian model with dissipation for HESS is derived and then, the interconnection and damping assignment-passive based controller (IDA-PBC) is designed to realize the underlying control, where the rule-based energy management strategy is adopted to generate the current references. To overcome the adverse influence of external disturbances and parameter perturbations under complex driving conditions, by combining the L2 gain disturbance attenuation technique with the IDA-PBC method, the L2-ARC method is developed to guarantee fast response, high performance, and robust stability. Moreover, an adaptive mechanism is adopted to estimate the electrical parameters. The performance of L2-ARC is thoroughly investigated and compared through comprehensive case studies with traditional PID, IDA-PBC, and sliding mode controllers. Finally, a control prototype is implemented to validate L2-ARC.

Finite-Time Control for a Coupled Four-Tank Liquid Level System Based on the Port-Controlled Hamiltonian Method

This work investigates the finite-time control problem for a nonlinear four-tank cross-coupled liquid level system by the port-controlled Hamiltonian (PCH) model. A fixed-free methodology is exhibited which can be used to simplify the controller design procedure. To get an adjustable convergent gain of the finite-time control, a feasible technique named damping normalization is proposed. A novel parameter autotuning algorithm is given to clarify the principle of choosing parameters of the PCH method. Furthermore, a finite-time controller is designed by a state-error desired Hamiltonian function, and the relationship between the settling time and a parameter is given, which can be applied in practical engineering easily to adjust the settling time according to the industrial need. Finally, simulation and experimental results verify the effectiveness of the proposed algorithm.

Energy shaping controller design of three‐phase quasi‐Z‐source inverter for grid‐tie

Although the control strategy regarding quasi-Z-source inverter (qZSI) has been widely studied, the dynamic response and steady-state accuracy of the system with a non-linear section should be further improved. Based on this, this study proposes an energy shaping control (ESC) method based on the port-controlled Hamiltonian (PCH) model for qZSIs. Firstly, based on the average state-space model, the PCH model of the qZSI system is first built, which is an indispensable preprocessing for the following controller design. Based on the proposed model, the ESC method combining the interconnect matrix with damping configuration is proposed to improve the dynamic response and steady-state accuracy, which is verified through comparing with several existing linear and non-linear control strategies in detail. Finally, simulation and experimental results verify the effectiveness of the proposed method.

Adaptive Disturbance Attenuation Control of Two Tank Liquid Level System With Uncertain Parameters Based on Port-Controlled Hamiltonian

This paper investigates the problem of the level control for two tank liquid level system(TTLLS) with parametric uncertainties and lumped disturbances. It is achieved by a novel adaptive disturbance attenuation control method based on the Port-Controlled Hamiltonian (PCH) model. Firstly, the model of TTLLS is established according to the mass balance principle and the PCH model is achieved. Based on the PCH model, the PCH controller of TTLLS is designed and the stability of the closed-loop system is ensured. To reduce the impact of disturbances and unmeasurable parameters, adaptive L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> disturbance attenuation technology is integrated. To achieve the robustness and simplify the calculation, the parameter estimation vector is designed by splitting complex mathematical expressions. Utilizing the properties of the PCH method and merits of the adaptive disturbance attenuation technology, the integrated controller achieves good performance. Moreover, simulation and experimental results are given to show the effectiveness and strong robustness of the proposed control algorithm.

Toward Stabilization of Constant Power Loads Using IDA-PBC for Cascaded LC Filter DC/DC Converters

This article proposes a modified interconnection and damping assignment passivity-based control (IDA-PBC) for dc/dc converter cascaded with an LC filter. The plant is modeled using the port-controlled Hamiltonian (PCH) form. The main objective is to stabilize the cascaded system in case the system supplies constant power load (CPL). To solve the instability issues caused by tightly controlled cascaded systems, the IDA-PBC based on an overall PCH model, including LC input filter and dc/dc converter, is established. Moreover, to ensure that the proposed IDA-PBC admits one unique solution, an adaptive interconnection matrix is designed to build the internal links in the PCH model. Furthermore, in order to improve the implementation on an onboard dc microgrid application with time-varying CPLs, a modified IDA-PBC algorithm is proposed based on the error between the state vector and the desired operating point, which might be variable. The closed-loop Hamiltonian function is chosen as the Lyapunov candidate function to guarantee that the system operates in a stable manner. The virtual damping assignment technique is addressed to tune the dynamic characteristic of the closed-loop system. Simulation and experimental results are carried out to illustrate the proposed method's effectiveness.

Port Controlled Hamiltonian Modeling and IDA-PBC Control of Dual Active Bridge Converters for DC Microgrids

Power electronics-based medium-voltage direct current (MVdc) microgrids consist of several interconnected feedback-controlled switching converters. Such systems experience bus voltage stability challenges owing to the negative incremental resistance of constant power loads and converter control loop interactions. To tackle the stability challenges, this paper presents the application of the interconnection and damping assignment passivity-based control (IDA-PBC) approach to the port-controlled Hamiltonian model of dual active bridge (DAB) source-side converters in an MVdc microgrid. For the DABs, a fundamental average model approach considering phase shift modulation is provided and used for deriving the corresponding IDA-PBC control law. We analyze the effectiveness of the controller on large signal scenarios considering disturbances such as load step up, and DAB disconnection. Hardware-in-the-Loop experiments using Opal-RT and Labview field programmable gate arrays (FPGAs), as well as, low power prototype tests are carried out to demonstrate the validity and feasibility of the proposed approach.

Adaptive Robust Simultaneous Stabilization of Two Dynamic Positioning Vessels Based on a Port-Controlled Hamiltonian (PCH) Model

In this paper, the adaptive robust simultaneous stabilization problem of two ships is studied. Firstly, the water surface three-degree-of-freedom ship models are transformed into port-controlled Hamiltonian (PCH) models. Using a single output feedback controller, the two PCH systems are combined to generate an enhanced PCH system based on Hamiltonian structural attributes. Then, considering the situation with both external interference and structural parameter perturbation in the systems, an adaptive robust output feedback controller is designed to stabilize the two systems simultaneously. Finally, the effectiveness of the controller proposed in this paper is illustrated by a simulation example.

A global asymptotical stable control scheme for a Hexverter in fractional frequency transmission systems

A fractional frequency transmission system (FFTS) is the most competitive choice for long distance transmission of offshore wind power, while the Hexverter, as a newly proposed direct AC/AC converter, is an attractive choice for its power conversion. This paper proposes a novel control scheme characterizing the global stability and strong robustness of the Hexverter in FFTS applications, which are based on the interconnection and damping assignment passivity-based control (IDA-PBC) methodology. Firstly, the frequency decoupled model of the Hexverter is studied and then a port-controlled Hamiltonian (PCH) model is built. On this basis, the IDA-PB control scheme of the Hexverter is designed. Considering the interference of system parameters and unmodeled dynamics, integrators are added to the IDA-PB controller to eliminate the steady-state error. In addition, the voltage-balancing control is applied in order to balance the capacitor DC voltages to obtain a better performance. Finally, the simulation results and experimental results are presented to verify the effectiveness and superiority of the IDA-PB controller.

A Nonlinear Supplementary Controller for Transient Response Improvement of Distributed Generations in Micro-Grids

This paper proposes a nonlinear supplementary controller for enhancing the transient response of distributed generations (DGs) in micro-grids. The proposed supplementary control system is based on an interconnection and damping assignment passivity-based controller and is designed according to the port-controlled Hamiltonian model of DGs. The controller is applied to the decentralized unified control scheme of DGs that enables seamless transitions between islanded and grid-connected modes. The proposed controller is generic and can be applied to DGs with different types of primary sources. The stability of the proposed supplementary controller is verified analytically, and the performance of the proposed controller is verified in a multi-resource micro-grid via time-domain simulations.

Energy-based Hamiltonian approach in H∞ controller design for n-degree of freedom mechanical systems

This paper studies the energy-based approach for controller design of -degree of freedom mechanical systems. In this approach, the Hamiltonian function, which is the sum of kinetic and potential energies of the system, is considered as the Lyapunov function for stability analysis. The stability analysis is done based on the port-controlled Hamiltonian (PCH) model. In this regard, two theorems are given and proved that the proposed controllers lead to disturbance attenuation for both absolutely known system model and unknown ones with parametric uncertainties. In the case of parametric uncertainties, the energy-based controller has an adaptive approach. Performance of proposed controllers is illustrated through simulations taken on a 2-link robot manipulator system, which validate the theoretical achievements of this paper.

A Novel Speed Control Method Based on Port-Controlled Hamiltonian and Disturbance Observer for PMSM Drives

This paper is mainly focusing on the problem of speed tracking control for permanent magnet synchronous motor (PMSM) drive system subject to matched and mismatched disturbance. This is achieved by a novel Port-Controlled Hamiltonian control method with nonlinear disturbance observer. Different from the traditional speed-current cascade control for PMSM, the speed-current single loop controller is designed. Firstly, the Port-Controlled Hamiltonian model of PMSM is established, then the Hamiltonian speed controller is designed by using interconnection assignment and damping assignment method. However, the standard Hamiltonian controller cannot achieve the satisfying behavior in the presence of the parameter variations and external disturbance, thus a nonlinear disturbance observer is designed to estimate the lump disturbance of the system, which is used to the feed-forward compensation control. Finally, simulation and experiment on the speed control system of PMSM are implemented. The results show that the proposed method has fast speed control performance and strong robustness for the different disturbance.

Speed and Heading Control of an Unmanned Surface Vehicle Based on State Error PCH Principle

This paper proposes a novel nonlinear control scheme based on energy-shaping (ES) principle and state error port-controlled Hamiltonian (PCH) systems for unmanned surface vehicles (USV) system. The PCH model of three degrees of freedom for USV kinetics system is established. By the ES principle, interconnection assignment and damping injection method is applied to the speed and heading control of the closed-loop USV system to realize an overall stability of control mechanism. Simulation results show that the validity and stability of control algorithm can be satisfied with the performance in speed and heading tracking of which the high simplification and portability make it applicable to the various region.

IDA‐PB control with integral action of Y‐connected modular multilevel converter for fractional frequency transmission application

Y-connected modular multilevel converter (Y-MMC) is a new topology of direct AC/AC power conversion, with broad application prospects in fractional-frequency transmission system. This study studies the mathematical model of Y-MMC and builds the port-controlled Hamiltonian model. Since vector control scheme can hardly ensure global stability, the interconnection and damping assignment passivity-based control (IDA-PBC) method is applied for controller design of Y-MMC. Three typical IDA-PBC strategies are then proposed, featuring the asymptotical stability of the desired equilibrium. To eliminate steady-state error, integrators are further added to the IDA-PB controller. Different from the previous research, the proposed method enables the decoupling of different-frequency components and the suppression of frequency leakage. Besides, the reactive power distribution coefficients are introduced to characterise the optimisation allocation of reactive power between arms. Finally, the effectiveness and superiority of the proposed control strategy are verified by both the simulation and experiment results.

An Energy-Based Control Strategy for Battery Energy Storage Systems: A Case Study on Microgrid Applications

Battery energy storage systems (BESSs) with proportional-integral (PI) control methods have been widely studied in microgrids (MGs). However, the performance of PI control methods might be unsatisfactory for BESSs due to the nonlinear characteristics of the system. To overcome this problem, an energy-based (EB) control method is applied to control the converter of a BESS in this study. The EB method is a robust nonlinear control method based on passivity theory with good performance in both transient and steady states. The detailed design process of the EB method in the BESS by adopting an interconnection and damping assignment (IDA) strategy is described. The design process comprises three steps: the construction of the port-controlled Hamiltonian model, the determination of the equilibrium point and the solution of the undetermined matrix. In addition, integral action is combined to eliminate the steady state error generated by the model mismatch. To establish the correctness and validity of the proposed method, we implement several case simulation studies based on a test MG system and compare the control performance of the EB and PI methods carefully. The case simulation results demonstrate that the EB method has better tracking and anti-disturbance performance compared with the classic PI method. Moreover, the proposed EB method shows stronger robustness to the uncertainty of system parameters.

Energy-Based Controller Design of Stochastic Magnetic Levitation System

This paper investigates the control problem of magnetic levitation system, in which velocity feedback signal is influenced by stochastic disturbance. Firstly, single-degree-freedom magnetic levitation is regarded as an energy-transform action device. From the view of energy-balance relation, the magnetic levitation system is transformed into port-controlled Hamiltonian system model. Next, based on the Hamiltonian structure, the control law of magnetic levitation system is designed by applying Lyapunov theory. Finally, the simulation verifies the correctness of the proposed results.

Control Strategy of the DC Drive Systems Based on the State Error Port-Hamiltonian Theory

A novel state error port-controlled Hamiltonian (PCH) system method is presented for speed control the direct current (DC) separately excited motor. The unity power factor regulation of three phase pulse width modulated (PWM) rectifier is also implemented. Then, the state error PCH system control theory, the PCH model of the PWM rectifier and DC motor are proposed. Moreover, the control algorithm of the duty ratio switch function is presented for the PWM rectifier. Theoretical analysis and simulation results show that the controller has good speed tracking and unity power factor control performances.