Jung-Pil Park

Discrimination and screening method for a Li-Ion cell based on discrete wavelet transform (DWT)

Differences in electrochemical characteristics among Li-Ion cells inevitably result in voltage/state-of-charge (SOC) imbalances in the Li-Ion battery pack. Therefore, this paper investigates a new approach based on the discrete wavelet transform (DWT) that suitable for analyzing and evaluating discharging/charging voltage signal (DCVS) for discrimination and screening method of a Li-Ion cell. The Daubechies wavelet (dB) is used as mother wavelet for the analysis of the DCVS with a non-stationary and transients. By using the wavelet de-composition including the multi-resolution analysis (MRA), the information on the electrochemical characteristic of a cell can be extracted from a signal over a wide frequency range. By the proposed approach, the cells that have similar electrochemical characteristics are finally selected and used for stable configuration of a Li-Ion battery pack. Experimental results validated the effectiveness DWT-based proposed approach.

Current sourced power efficient sustainer circuit for AC plasma display drive

A new sustain circuit for an AC plasma display drive is proposed. The proposed circuit uses the instantaneous peak current flowing through the inductor during charging and discharging a plasma display panel (PDP), to mainly recover the energy lost by the capacitive displacement current. This circuit can be realized with a small number of part counts, and gives the zero voltage switching characteristics to all the switches even in the presence of a parasitic resistance, essential for the design of a sustain circuit for the AC plasma display. The capacitive displacement current and the required reactive power are greatly reduced in the proposed circuit. A comparative analysis and experimental results are presented to show the validity of the proposed energy recovery circuit.

Discrete wavelet transform-based characteristic analysis and SOH diagnosis for a Li-Ion cell

This paper introduces the characteristic analysis and state-of-health (SOH) diagnosis for a Li-Ion cell based on discrete wavelet transform (DWT). The DWT is a powerful tool in the analysis of the discharging/charging voltage signal (DCVS) of a Li-Ion cell with non-stationary and transient phenomena. DWT-based multi-resolution analysis (MRA) is applied for extracting the information on the electrochemical characteristic in both time and frequency domain simultaneously. Wavelet decomposition based on the selection of the order 3 Daubechies wavelet (dB3) and scale 5 as the best wavelet function and the optimal decomposition scale are implemented. In particular, this present study develops these investigations one step further by showing high/low frequency components extracted from variable Li-Ion cells with different electrochemical characteristics caused by aging effect. The experimental results show the clearness of the DWT-based approach for the reliable diagnosis of the SOH.

Automatic tuning of the switching frequency for efficiency maximization in an ESS-PV hybrid PCS

An automatic switching frequency tuning algorithm (ASTA) for a real-time condition is proposed. The primary aim is to maximize the power efficiency of a power electronic system. The power loss of a hard-switched power converter is determined by the power loss in power semiconductor devices, magnetic devices, capacitors, etc. Switching frequency of a power converter is one of the parameters which influence the power loss. The parameters which determine the maximum-efficiency point can vary with the ageing of devices and the change in environmental conditions. In this paper, a PWM-carrier frequency is utilized for efficiency maximization of a power conversion system. By varying the PWM-carrier frequency from the minimum to maximum value to search for the switching frequency associated with the point of maximum efficiency, this algorithm is designed for a hybrid-energy power conversion system which consists of DC/DC converters and a DC/AC inverter. For the realization of this algorithm, real-time power meter...

The novel MEPT algorithm development in the battery parallel system

In this paper, we propose the novel MEPT control algorithm in battery parallel system of the PCS. The proposed control algorithm is to be able to deliver the power of DC-link energy of PCS at maximum efficiency point. The benefit is available that more efficient operation and management of energy is applied at a large power system. To verify the validity of the proposed MEPT control algorithm, we carry out a computer-aided simulation and experiment.

Duty ratio compensator techniques for bidirectional charger

In this paper, we implement a non-time-varying duty ratio transfer function for Improvement of control characteristics in the system that input voltage and output voltage variable as bi-directional charger DC/DC converter. Using designed by the existing controller design gain are variable control characteristics in accordance with the input voltage fluctuation. Each benefit of the voltage controller multiplied by the reciprocal the of the duty ratio change. It is a way that duty ratio can be removed equivalently. non-time-varying duty ratio transfer function for bi-directional charger DC/DC converter is applied to simulation and experimental results using PSIM validity and superiority is verified.