State-space Averaging Research Articles

Multiscale Change Point Detection for Univariate Time Series Data with Missing Value

This paper studies the autoregressive integrated moving average (ARIMA) state space model combined with Kalman smoothing to impute missing values in a univariate time series before detecting change points. We estimate a scale-dependent time-average variance constant that depends on the length of the data section and is robust to mean shifts under serial dependence. The consistency of the proposed estimator is shown under the assumption allowing heavy tailedness. Integrating the proposed estimator with the moving sum and wild binary segmentation procedures to determine the number and locations of change points is discussed. Furthermore, the performance of the proposed methods is evaluated through extensive simulation studies and applied to the Beijing multi-site air quality dataset to impute missing values and detect mean changes in the data.

Design and implementation of Golden Eagle optimized cascaded PI and LQR controller for PFC SEPIC converter in EV charging

This research article focuses on designing and implementing a single ended primary inductor converter (SEPIC) for an AC-DC converter, followed by an electric vehicle (EV) charger. It improves the high-power factor at the AC supply with minimum harmonic distortion. The Golden Eagle optimization techniques are adapted to optimize the tuning of Proportional-Integral (PI) and Linear Quadratic Regulator (LQR) controller parameters for better converter performance. The optimization is designed based on the eagle knowledge of hunting methods at various angles of spiral trajectories in capturing the animal. The SEPIC converter is designed and derived from the state space model by state space averaging, and the reduced model is obtained through the moment matching method to reduce computational complexity. The Golden Eagle Optimize the parameters of KP and KI of the PI controller and weighing matrix Q of the linear quadratic controller. The fitness function of the proposed optimization is the sum of the Integral Absolute error (IAE) and Integral Square error (ISE). The proposed optimization is implemented using MATLAB/SIMULINK software, and the simulation outcomes demonstrate an improved settling time, fast recovery against input and output variations, Total Harmonic Distortion (THD) of 1.75 %, and enhanced stability.

DC Regulation and Loop Gain Analysis of a DC-DC Switch Mode Power Supply: A Case Study on a Synchronous PWM Controlled Buck Converter

This study investigates the DC regulation of a DC-DC buck converter operating with pulse width modulation (PWM), taking into account the internal resistance of the coil and the on-resistance of the switching device. The effect of these parameters on the input/output disturbances is analyzed in continuous-conduction mode under constant frequency voltage mode control. The study also explores the effect on loop gain using the IRU3037 8-pin IC synchronous PWM controlled buck converter. The transfer function of the IRU3037 IC is derived from datasheet values using state-space averaging and AC small signal methods. A Type II compensator is then designed based on the derived transfer function. In addition, the step response characteristics of the open-loop and closed-loop circuits are investigated by time domain analysis.

Golden eagle optimized fractional-order PI controller design for a PFC SEPIC converter in EV charging

The power factor correction converter is the function of the front-end converter, followed by the DC–DC converter of the electric vehicle charger. It improves the power factor and regulates the output voltage and current. This research article proposes the Golden Eagle optimization for fractional order PI (FOPI) controller for Single Ended Primary Inductor Converter (SEPIC) power factor correction. The Golden eagle optimization is based on its knowledge of hunting tactics at various degrees of spiral trajectories to catch the prey. The FOPI controller has a broad range of controller parameters that provide better control and performance of the converter. The tuning of the parameters of the FOPI controller is optimized in Golden Eagle Optimization, and the Integral Absolute error with Integral Square error is used for the objective function. The optimized parameters of FOPI compare with the conventional PI controller performance. The SEPIC converter is designed and derived from the state space model by state space averaging, and the reduced model is obtained through the moment matching method. This system is tested under MATLAB/SIMULINK, and simulation results show improved settling time, fast dynamic response, reduction of inrush current, less harmonic distortion, and stability.

State Space Average Modeling, Small Signal Analysis, and Control Implementation of an Efficient Single-Switch High-Gain Multicell Boost DC-DC Converter with Low Voltage Stress

This paper presents the closed-loop control of a single-switch high-gain multicell boost DC-DC converter working in a continuous conduction mode (CCM). This converter is particularly designed for applications in photovoltaic systems. One of the main advantages of the proposed converter is that it only employs one active semiconductor switch, which decreases the converter losses and cost, increases the efficiency, and simplifies the control circuit. Moreover, the multicell nature of the proposed converter offers the possibility of obtaining the required voltage gain by selecting the number of cells. State space average (SSA) modeling and small-signal analysis are used to model the switching converter power stages of the proposed converter. The parasitic series resistances of the passive elements of the converter circuit are considered to improve the accuracy of the modeling. Small-signal analysis is used to derive the open-loop transfer functions, input-to-output and control-to-output transfer functions of the proposed converter to examine its dynamic performance. The stability of the converter is analyzed to design the parameters of the voltage controller using the proposed modeling method. The experimental prototype of the proposed single-switch two-cell boost DC-DC converter was implemented. The simulation and experimental results proved the effectiveness of the proposed boost DC-DC converter under different working conditions. It has a fast dynamic response without overshoots. A comprehensive comparison between the proposed converter and previous boost converters is provided. It guarantees a required variable and constant high voltage gain with a wider duty ratio range. It compromises between the required performance, the low number of components, low voltage stress on the components, and cost-effectiveness. The experimental efficiency of the proposed converter is about 96% at a 100 W load.

A comprehensive analysis and closed-loop control of a non-isolated boost three-port converter for stand-alone PV system

This study critically investigates analysis and control of non-isolated boost three-port DC to DC converter (TPC) forstandalone PV system. The converter is controlled such that regulates flow of power from PV array to load and batteries as storage devices.According to PV power, there are four operating modes of operation of converter. Simple reduced-order dynamic models of the converter in various modes of operation are obtained using state-space averaging and small-signal techniques. In this work, the controllers of the closed-loop scheme are designed and only two controllers are used to achieve output voltage regulation, and to extract maximum power from PV array under different operating conditions. Closed-loop system simulation is studied to verify the operation of converter with the designed controllers in different modes. Transition between modes is presented with solar radiation variation and change of connected loads. Experimental verification of control systems at different modes of operation is investigated. The experimental results show that the controllers can regulate the power flow between TPC three ports and regulate output voltage under PV irradiance variation and load changing. The controller shows good performance measures such as maximum settling time of 0.06 s, maximum steady-state ripples of ±0.8 %, and 99.3 % power efficiency.

An approximate dynamic model of double-sided LCC resonant converter in wireless power transmission based on average current model

Wireless Power Transmission (WPT) system could realize a non-contact power transmission through the air gap weak magnetic coupling. This paper aims at analyzing a dynamic model of the WPT system based on a double-side LCC. Firstly, in the multivariable framework, the dynamic characteristics of double-side LCC resonant compensation topology are analyzed by the mutual inductance model. The approximate small-signal model of double-side LCC resonant converter is derived by generalized state-space averaging (GSSA). Additionally, a double-side LCC compensation topology based on double closed-loop average current mode control approach is proposed. By contrasting the behavior of the WPT system under various operating conditions, the efficacy of the suggested dynamic model is illustrated. Finally, a wireless power transmission system experiment platform with a resonant frequency of 85 kHz and an output power of 3 kW was built. Through the experiments, it is determined that the model has a certain ability to predict the dynamic behavior of the wireless charging system. So, it can be utilized as a useful instrument for the transient's analysis and the controller development optimization.© 2017 Elsevier Inc. All rights reserved.

A novel modulation for four‐switch Buck‐boost converter to eliminate the right half plane zero point

AbstractThe four‐switch Buck‐Boost (FSBB) converter are widely used in combination with other isolated converter to extend the voltage range capability of the overall structure. When the converter operates in buck‐boost mode and boost mode, it exhibits a right half plane zero (RHPZ) in the control to output transfer function. This characteristic would cause negative impact to stability of the converter. In order to eliminate the RHPZ, a novel modulation method is proposed in this paper. The buck mode is introduced to the modulation to adjust the voltage gain, and the corresponding average state space modeling for the FSBB with the proposed modulation is established. The simulation of the converter with the proposed modulation method and traditional modulation are presented. Finally, experiment results by hardware in the loop (HIL) platform is employed to verity the correctness of theoretical analysis results.

Generalized state‐space averaging modeling to fourth‐order power converters operating in DCM

AbstractThis paper presents a novel methodology for correcting the state‐space averaging (SSA) modeling for DC‐DC power converters represented for fourth‐order systems operating in discontinuous conduction mode (DCM). SSA modeling has been widely employed for converters operating in continuous conduction mode (CCM), obtaining a good similarity between the switched converter and the mathematical model. In contrast, when the converters work in DCM, significant deviations between the average and RMS values imply errors in the SSA model. Hence, the proposed generalized SSA modeling methodology provides an accurate model to aid the controllers and system design. Consequently, the proposed technique can be applied to distinct fourth‐order power converters such as Zeta, Ćuk, and SEPIC in several applications. Additionally, SSA corrections can be associated with different techniques for obtaining the small‐signals representation. Simulation and experimental results and mathematical analyses that prove the feasibility and functionality of the proposal are addressed.

Generalized Pulse Width Modulation Switch Model for Converters Based on the Multistate Switching Cell in Discontinuous Conduction Mode.

This work introduces a generalized version of the pulse width modulation (PWM) switch model applied in the small-signal modeling of converters based on the multistate switching cell (MSSC) operating in discontinuous conduction mode (DCM). It consists of extending the concept formerly introduced by Vorperian for the representation of multiphase converters in DCM, yielding a circuit-based approach that does not rely on matrix manipulations unlike state-space averaging (SSA). The derived dc and ac models are valid for any number of switching states and any operating region defined in terms of the duty cycle, thus allowing for determining the voltage gain and distinct transfer functions. A thorough discussion of results is presented to demonstrate the applicability of the derived models to represent distinct configurations of the MSSC.

Applying k‐nearest neighbors to time series forecasting: Two new approaches

AbstractThe k‐nearest neighbors algorithm is one of the prominent techniques used in classification and regression. Despite its simplicity, the k‐nearest neighbors has been successfully applied in time series forecasting. However, the selection of the number of neighbors and feature selection is a daunting task. In this paper, we introduce two methodologies for forecasting time series that we refer to as Classical Parameters Tuning in Weighted Nearest Neighbors and Fast Parameters Tuning in Weighted Nearest Neighbors. The first approach uses classical parameters tuning that compares the most recent subsequence with every possible subsequence from the past of the same length. The second approach reduces the neighbors' search set, which leads to significantly reduced grid size and hence a lower computational time. To tune the models' parameters, both methods implement an approach inspired by cross‐validation for weighted nearest neighbors. We evaluate the forecasting performance and accuracy of our models. Then, we compare them to other approaches, especially, Seasonal Autoregressive Integrated Moving Average, Holt Winters, and Exponential Smoothing State Space Model. Real data examples on retail and food services sales in the United States and milk production in the United Kingdom are analyzed to demonstrate the application and efficiency of the proposed approaches.

Applying Particle Swarm Optimization for Investigating the Stability of DC-DC Buck-Boost Converter: A Software Based Approach

ABSTRACT Stability of power converters has always been a major concern when dealing with nonlinear behavior of the system and swarm-based optimization techniques are proven to be handy as they are widely employed. Hence, this study presents an investigative approach to explore the compatibility of applying different variants of Particle Swarm Optimization (PSO) to design an optimized PID controller for DC-DC Buck-Boost converter. This work assesses converter stability through optimization of the PID controller using classical PSO (cPSO), Time-Varying Inertia Weight PSO (TVIW-PSO), Chaotic Descending Inertia Weight PSO (CDIW-PSO), Self-organizing Hierarchical PSO (HPSO) and Random inertia weight PSO (RIW-PSO). The State Space Average (SSA) method is utilized to model and attain the transfer function; eigenvalue analysis and time domain simulation analysis are considered to investigate the stability. Moreover, four objective functions and various performance parameters such as percentage of overshoot, rise time, settling time, and peak amplitude are tabulated to assess the system’s efficiency and the outcomes of different approaches are compared extensively. Amongst all, CDIW-PSO showcased better performances e.g. overshoot of 1.08%, settling time 0.000228s and rise time 0.000143s. The findings illustrate algorithm’s capacity to reduce transient and steady-state faults and makes it compatible with more nonlinear applications.

A Novel Nonisolated Four-Port Converter for Flexible DC Microgrid Operation

In this paper, a new non-isolated four-port DC-DC converter is proposed for DC Microgrid applications. The proposed converter offers a main feature of controlling the DC link voltage regardless of resources availability. By using four IGBT switches and only one diode, three different sources can be interfaced to a boosted DC link load. Different operation modes of the proposed architecture are discussed, testified and validated experimentally. The buck-boost capability of the proposed topology allows an enhanced flexibility to integrate various sources with distinct voltage-current (V-I) characteristics while sharing load power among all ports. In this context, steady state analysis is performed to determine the voltage gains between all ports. The control strategy is developed for the proposed topology to manage power flow between sources and load achieving basic operations for renewable resources such MPPT for PV. A theoretical based study is performed on the proposed converter including steady-state analysis, state-space averaging followed by small signal modeling and frequency response-based controller design. The converter different operating conditions are validated experimentally.

Modeling and Controller Design of Non Ideal Z-Source Converter

This paper deals with the study of the non-ideal Z-Source inverter where the inductors and capacitors resistance are taken into account, while the main aim of the Z-source inverter for performing voltage buck and boost capabilities using a unique impedance network between the power source and converter circuit is guarded. In this paper an average model for the Z-Source inverter using state space averaging is proposed. Then, the behaviors of the studied system is analyzed based on the stability of the presented model, this analyze leads to the design of the suitable controller to be used to ensure the stability of the presented model. Finally the average model analyze is verified by simulation results.

State-Space Modeling, Design, and Analysis of the DC-DC Converters for PV Application: A Review

Small-signal models of dc-dc converters are often designed using a state-space averaging approach. This design can help discuss and derive the control-oriented and other frequency-domain attributes, such as input or output impedance parameters. This paper aims to model the dc-dc converters for PV application by employing a capacitor on the input side. The modeling, design, and analysis of the dc-dc converters regarding the input capacitor is limited in the literature. Five dc-dc converters, including buck, boost, buck-boost, ĆUK, and SEPIC converters, are designed and implemented using the state-space average modeling approach in MATLAB/Simulink. The circuit topology of each converter and the state-space matrices are derived considering every constraint. A rigorous and compelling analysis of the dc-dc converters is carried out to compare system stability and, ultimately, the dynamic performance. The output of the resulting small-signal models has been demonstrated in the time-domain against topology simulations. All the converters are exposed to unpredictable weather conditions and the simulations are carried out in the PSIM software. The perturb and observe (P&O) maximum power point tracking (MPPT) algorithm is applied in all the converters to ensure maximum power point (MPP) achievement. The results showcase that the boost converter outperforms all other converters in terms of stability, settling time, and overshoot.

Implementation of Bio-inspired Algorithms in Designing Optimized PID controller for Cuk Converter for Enhanced Performance: A Software based Approach

This paper represents the idea of implementing bio-inspired algorithms in designing an optimized PID controller to investigate the stability and improve the performance of the closed-loop CUK converter. Bio-inspired algorithms (BIA) such as Firefly Algorithm (FA), Particle Swarm Optimization (PSO) and, Artificial Bee Colony (ABC) are stochastic optimization techniques and have been increasingly applied to attain optimal solution for designing and optimizing power converters in current times. The closed-loop transfer function of the CUK converter has been developed by the State Space Average (SSA) technique. This paper assesses both the cases of converter stability when it is integrated with the conventional PID controller and the BIA-PID controllers (FA-PID, PSO-PID, ABC-PID) and eventually compares the outcomes from all the controllers. For examining the stability of the system, three objective functions (IAE, ITAE, and ISE) and various performance specifications such as percentage of overshoot, rise time, settling time, and peak amplitude are tabulated. MATLAB and Simulink are used to carry out the simulations meticulously. Hence, a comparative analysis is illustrated in this paper to state a clear-sighted evaluation of the performances.

Detailed analysis and modeling of improved cascade buck converter

ABSTRACT – This paper presents ready-to-use nonlinear and linear averaged models of an improved cascade buck converter (ICBC) for the first time. A detailed steady-state analysis is also given, providing its operating modes, equilibrium values, and design guidelines. The modelling process consists of two stages. First, the nonlinear model is obtained using the state-space averaging technique. Subsequently, the averaged model is linearised by applying the small-ripple approximation and the small-signal model is achieved. Furthermore, the developed small-signal model is employed to derive three significant transfer functions of the converter. The proposed converter model is valid for the continuous conduction mode (CCM) when the duty cycle is lower than . To be used in validation studies, an exemplary converter with rated power that steps down input voltage to is designed. The accuracy of theoretical analyses is confirmed by the simulation results of the designed converter. Similarly, all proposed models are validated with the simulations done in both frequency-domain and time-domain. The results show that the proposed parametric model response closely matches that of the switching (non-parametric) model and hence it can be safely used for controller design in feedback systems.

H‐infinity loop shaping control of wireless power transfer system based on generalized state space averaging model

SummaryThe transmission distance and the output load of wireless power transfer (WPT) system are particularly prone to change, which results in higher requirements for the robustness and dynamic performance of the control. In order to reduce the influence of these characteristics, an H∞ loop shaping controller based on generalized state space averaging (GSSA) method is proposed in this paper. Based on the GSSA model, an appropriate compensation function is constructed for the WPT system to the target loop transfer function. The nominal coprime factorization of WPT system is carried out, and on this basis, H∞ controller is achieved by Riccati equation to minimize the infinite norm from disturbance to error output. The designed controller meets the requirements of robust. Furthermore, the obtained high‐order controller is discretized by a reasonable discretization method, and the details and limitations of its practical application are discussed based on the hardware computational capacity. The experimental results show that the proposed controller has better robustness and dynamic performance and flexibility than the mixed sensitivity H∞ controller and the Z‐N PI controller.

Modeling and Nonlinear Dynamic Analysis of Cascaded DC–DC Converter Systems Based on Simplified Discrete Mapping

As a basic structure of the distributed power systems, cascaded DC-DC converter systems have attracted a lot of attention. However, due to the interaction between the sub-converters, classic methods for modeling cascaded systems are either not accurate enough, such as state-space averaging model, or not simple enough, such as discrete-time mapping model, especially the systems with different switching frequencies. To overcome this drawback, a simplified discrete-time mapping modeling method for cascaded DC-DC converter systems is proposed in this paper. Based on the idea of state-space average, the original problem is simplified to modeling cascaded DC-DC converter systems with same switching frequencies. The proposed method is able to predict the dynamic properties of the system at all stages, such as slow-scale and fast-scale instabilities. Then, two-stage cascaded boost converter with different switching frequencies under peak current double loop control is taken as an example to present the simplified discrete-time mapping model. Finally, the effectiveness of the proposed method is verified by simulations and experiments.

A New Fast Control Strategy of Terminal Sliding Mode with Nonlinear Extended State Observer for Voltage Source Inverter.

To overcome the sensitivity of voltage source inverters (VSIs) to parameter perturbations and their susceptibility to load variations, a fast terminal sliding mode control (FTSMC) method is proposed as the core and combined with an improved nonlinear extended state observer (NLESO) to resist aggregate system perturbations. Firstly, a mathematical model of the dynamics of a single-phase voltage type inverter is constructed using a state-space averaging approach. Secondly, an NLESO is designed to estimate the lumped uncertainty using the saturation properties of hyperbolic tangent functions. Finally, a sliding mode control method with a fast terminal attractor is proposed to improve the dynamic tracking of the system. It is shown that the NLESO guarantees convergence of the estimation error and effectively preserves the initial derivative peak. The FTSMC enables the output voltage with high tracking accuracy and low total harmonic distortion and enhances the anti-disturbance ability.