Woonki Na

Multi-phase sliding mode control power converter for electrical vehicle applications

In this paper, a multi-phase sliding mode controller is presented for an electric vehicle system having a fuel cell power source and energy storage systems such as battery and ultracapacitor. Details of the multi-dimensional sliding mode control for this multi-input power converter are designed with a dynamic Proton Exchange Membrane Fuel Cell(PEMFC), Li-Ion battery and Ultracapacitor models. The proposed controller is verified and validated throughout the simulation and the small scaled DSP test-bed in terms of the ripple reduction of the current on the DC link under various conditions.

Modeling and control of solar/fuel cell powered hybrid power systems

In this paper, a modeling and supervisory control strategy for a solar/fuel cell powered hybrid power system are developed for stand-alone residential applications. Using Ultra-Capacitors(UC) and PhotoVoltaic (PV) panel together with a Fuel Cell(FC) system is a possible solution to provide sufficient power supplies for residential areas. Each model for the FC, PV and UC are developed, and four modes of operations of the proposed hybrid power system are defined for the proposed supervisory control. The proposed hybrid power system is simulated and analyzed based upon the modeling and the supervisory control algorithm in Matlab/Simulink environment.

Design and control of an interleaved bi-directional power converter for railway applications

This paper is with regard to a topology of an interleaved bidirectional buck-boost power converter for railway applications. The objectives of this proposed power converter topology are to suppress the harmonics at the both sides of the input terminal and output terminal using this topology. Since the both sides of voltages have wide operating ranges such as the battery voltage ranging 500V∼700V, and the DC link voltage ranging 500V∼1000V, the control algorithm for this power converter is investigated especially at the aspect of smoothing transients caused by the changes of current direction and the modes of operation(buck or boost modes). Control design, and simulation and experiment results are presented to validate the proposed system.

Improved maximum power point tracking algorithm using a Fuzzy Logic Controller for a Photovoltaic System

In this paper, an improved the maximum power point tracking (MPPT) in a Photovoltaic (PV) System is designed by using a Fuzzy Logic Controller (FLC). The objectives of designing the FLC for MPPT in the PV systems are to accelerate the MPPT rate, and to set a smaller oscillating zone around the maximum power point (MPP). The proposed FLC based MPPT adopts a set of variable step sizes with regard to flexible criteria. Also, for the proposed MPPT implementation, a simple Discontinuous Conduction Mode (DCM) algorithm is considered. Experimental results of the proposed FLC based MPPT show that an improvement is observed in terms of tracking of the MPPT, and maximizing of the output power of the PV modules compared to the conventional Perturb and Observe (P&O) algorithm.

Difference in EDCTV between MLD- and SCSLD-based noise elimination of the series/parallel-cell configured battery pack

The state-of-charge (SOC) estimation and state-of-health (SOH) prediction of the series/parallel-cell configured battery pack are determined by measuring an elaborate experimental discharging/charging terminal voltage (EDCTV) signal. Unfortunately, an unavoidable sensing of noisy in the EDCTV signal clearly results in non-correct SOC/SOH performances. Therefore, it is surely required to investigate an innovative approach that can sufficiently eliminate the noise in original EDCTV signal. From this perspective, this approach finally adapted the discrete wavelet transform (DWT)-based noise elimination, namely denoising technique. Specifically, in terms of the decomposition and reconstruction levels in the multi-resolution analysis (MRA), this approach analyzed the difference in de-noised EDCTV signals between multi-level DWT(MLD)- and series connected single-level DWT (SCSLD)-based noise elimination by two thresholding rules (hard- and soft-thresholding). For clear evaluation of comparative analyses, the signal-to-noise ratio (SNR) values were calculated. Consequently, this approach entirely gives an additional and unique solution of the noise elimination for efficient operation of the series/parallel-cell configured battery pack.

Optimized implementation of a DC-DC power converter modeling and control strategy for efficient operation of a photovoltaic application

This paper describes a small signal model, voltage controller design and its implementation for a DC/DC converter in a PV(Photovoltaic) system. The detailed small signal model is proposed to design a voltage controller for the system. Based on the proposed small signal model, a voltage controller for the PV system is designed and tested with different internal resistances of the PV system. The designed voltage controller is validated through a DSP(Digital Signal Processor) based prototype PV system.

Multi-phase sliding mode control for chattering suppression in a DC-DC converter

This paper presents a Multi-Phase Sliding Mode(MPSM) Control Strategy for solving chattering issues inherently existing in DC-DC converters. The main idea of the proposed methodology is to implement a MPSM Control for geometrically nullifying the amplitude of ripple currents yielded by the switching patterns. The benefits of the proposed Multi-Phase Sliding Mode Control strategy involve low-switching frequency contributing to reduce switching power loss and leading to simplification of circuit topology. Throughout the experimental implementation, the concepts of control strategies were validated and the advantages of the proposed strategy were confirmed such as low-switching power loss, and simple circuit structure compared to traditional multi-phase SMC implementations.

Efficient FCTV provision considering DWT and DWPT-based noise suppression for overcoming the noise-induced voltage loss in PEM fuel cell

This approach gives insight to the design and implementation of the noise suppression based on the wavelet transform (WT) for efficient FCTV signal provision. The most important thing in this approach is to show the comparative analyses on noise suppression between two transforms, such as the discrete wavelet transform (DWT) and discrete wavelet packet transform (DWPT). With an identical mother wavelet of Daubechies db3, the multi-resolution analysis (MRA)-based decomposition and reconstruction processes for reducing the noise-induced voltage loss are basically done in the DWT and DWPT. The marked difference between two transforms is the MRA-based decomposition/reconstruction ability of high frequency component related to the sensing of noisy. For reference, this approach considered two noise suppression techniques such as hard- and soft-thresholdings and checked signal-to-noise ratio (SNR) values for clear evaluation of all comparative analyses. From these results, it is capable of suggesting three conclusions. First, the performance on noise suppression of the DWPT is superior to that of the DWT. Second, the noise-induced voltage loss is more suppressed at soft-thresholding technique when compared to hard-thresholding technique irrespective of the DWT and DWPT. Last, the optimal decomposition/reconstruction levels that have the maximum SNR values are respectively determined in hard- and soft-thresholding techniques. Our definite suggestions sufficiently enable us to achieve an optimal solution for efficient FCTV provision. This approach has been extensively verified by experimental results of the FCTV using a single cell.

Noise suppression of the DWT-based MRA on mother wavelet and decomposition level optimization for a robust adaptive SOC estimator in multi-cell battery string

This approach newly presents an innovative method that implements the noise suppression considering the discrete wavelet transform (DWT)-based multi-resolution analysis (MRA). Specifically, this approach elaborately carries out two comparative analyses of the noise suppression depending on information on mother wavelet and decomposition level in the MRA. The first is to select the decomposition level having a high performance of the noise suppression under the same condition of mother wavelet. On the contrary, with an identical condition of the decomposition level, the second is to compare the noise suppression of different mother wavelets under the same condition of the decomposition level. All comparative analyses are evaluated in terms of signal-to-noise ratio (SNR). This approach entirely makes a comparison between two noise suppression techniques considering hard- and soft-thresholding. From these results, our analytic results suggest the clear comparison by showing the SNR difference with various mother wavelets and decomposition levels. Consequently, it can be surely expected to optimize the mother wavelet and the decomposition level for noise suppression of the noise-riding EDCV signal in multi-cell battery string. Our experimental multi-cell battery string in series/parallel (2S3P) using 2.2Ah unit cells previously discriminated was used.

Control design of DSP based a bi-directional converter for electric vehicles applications

In this paper, a control design of Digital Signal Processor based a power factor corrected(PFC) converter and a bidirectional converter for Plug-In Hybrid Electric Vehicles (PHEVs) is discussed. In order to design current and voltage controllers of the PFC converter and the bi-directional converter for PHEVs, small signal models are used. Design procedures of current controllers for the PFC controller and the bi-directional converter are explained and analyzed by using small signal models and bode plots. The suggesting design procedures of controllers for the PFC converter and the bi-directional converter are verified, and validated throughout simulations and a DSP based prototype.