Mohammad Rezwan Khan

Fault Detection and Localization Method for Modular Multilevel Converters

The modular multilevel converter (MMC) is attractive for medium- or high-power applications because of the advantages of its high modularity, availability, and high power quality. However, reliability is one of the most important issues for MMCs which are made of large number of power electronic submodules (SMs). This paper proposed an effective fault detection and localization method for MMCs. An MMC fault can be detected by comparing the measured state variables and the estimated state variables with a Kalman filter. The fault localization is based on the failure characteristics of the SM in the MMC. The proposed method can be implemented with less computational intensity and complexity, even in case that multiple SM faults occur in a short time interval. The proposed method is not only implemented in simulations with professional tool PSCAD/EMTDC, but also verified with a down-scale MMC prototype controlled by a real-time digital signal controller in the laboratory. The results confirm the effectiveness of the proposed method.

Feasibility Study and Techno-economic Optimization Model for Battery Thermal Management System

The paper investigates the feasibility of employing a battery thermal management system (BTMS) in different applications based on a techno economic analysis considering the battery lifetime and application profile, i.e. current requirement. The preliminary objective is to set the decision criteria of employing a BTMS and if the outcome of the decision is positive, to determine the type of the employed BTMS. However, employing a BTMS needs to meet a number of application requirements and different BTMS associates a different amount of capital cost to ensure the battery performance over its lifetime. Hence, the objective of this paper is to develop and detail the method of the feasibility for commissioning BTMS called “The decision tool framework” (DTF) and to investigate its sensitivity to major factors (e.g. lifetime and application requirement) which are well-known to influence the battery pack thermal performance, battery pack performance and ultimately the performance as well as utility of the desired application. This DTF is designed to provide a common framework of a BTMS manufacturer and designer to evaluate the options of different BTMS applicable for different applications and operating conditions. The results provide insight into the feasibility and the required specification and configuration of a BTMS.

Multiphysics based thermal modeling of a pouch lithium-ion battery cell for the development of pack level thermal management system

The research is focused on the development of a three-dimensional cell level multiphysics battery thermal model. The primary aim is to represent the cooling mechanism inside the unit cell battery pack. It is accomplished through the coupling of heat transfer and computational fluid dynamics (CFD) physics. A lumped value of heat generation (HG) inside the battery cell is used. It stems from isothermal calorimeter experiment. HG depends on current rate and the corresponding operating temperature. It is demonstrated that the developed model provides a deeper understanding of the thermal spatio-temporal behavior of Li-ion battery in different operating conditions.

Determination of the behavior and performance of commercial Li-Ion pouch cells by means of isothermal calorimeter

In this experiment-based research, there is an attempt to determine the evolution of surface temperature distribution, thermal behaviour and performance of a battery cell at the same time. The pouch type commercial test cell has a 13Ah capacity and Lithium Titanate Oxide (LTO) based anode. Temperatures on the surface of the cell are measured using contact thermocouples. Additionally, the heat flux is simultaneously measured with the isothermal calorimeter. This heat flux measurement is used for determining the heat generation inside the cell. Consequently, the important performance constituent of the battery cell efficiency is calculated. Those are accomplished at different temperature levels (0°C and 25°C) of continuous constant current 1C charge and discharge. Also, the maximal increase in the battery temperature over the cell surface is found on the battery cell surface. The heat flow calibration and experimentation for calorimetric measurement are deliberated. The experimental procedure is a very precise determination of the heat generation and the efficiency of the battery cell.

Three Dimensional Thermal Modeling of Li-Ion Battery Pack Based on Multiphysics and Calorimetric Measurement

A three-dimensional multiphysics-based thermal model of a battery pack is presented. The model is intended to demonstrate the cooling mechanism inside the battery pack. Heat transfer (HT) and computational fluid dynamics (CFD) physics are coupled for both time-dependent and steady-state simulation. Inside the battery cells in the pack a lumped value of heat generation (HG), that works as a volumetric heat source, is used. The measured HG stems from the cell level isothermal calorimeter experiment. The batteries inside the pack stay in the same initial thermal state in the simulation case. The pack is simulated to find the temperature gradient over the pack surfaces. Moreover, the temperature evolution results are simulated. It is demonstrated that the developed pack model can provide the thermal spatio-temporal behaviour with great detail. The result helps to understand the thermal behavior of the cells inside a battery pack.

Investigation of Battery Heat Generation and Key Performance Indicator Efficiency Using Isothermal Calorimeter

In this experiment-based research, the performance and behaviour of a pouch type Li-ion battery cell are reported. The commercial test cell has a Lithium Titanate Oxide (LTO) based anode with 13Ah capacity. It is accomplished by measuring the evolution of surface temperature distribution, and the heat flux of the battery cell at the same time. Temperatures on the surface of the cell are measured using contact thermocouples, whereas, the heat flux is measured simultaneously by the isothermal calorimeter. This heat flux measurement is used for determining the heat generation inside the cell. Consequently, using the heat generation result the important performance constituent of the battery cell efficiency is calculated. Those are accomplished at different temperature levels (-5°C, 10°C, 25°C and 40°C) of continuous charge and discharge constant current rate (1C,2C,4C,8C,10C (maximum)). There is a significant change in heat generation in both charge and discharge events on different temperature and C-rate. The heat flux change level is nonlinear. This nonlinear heat flux is responsible for the nonlinear change of efficiency in different C-rate in a particular temperature. The presented experimental technique is a very precise determination to profile the battery cell. The result of the research can be incorporated in constructing a precise datasheet for a battery cell which can assist the researchers, engineers, and different stakeholders to enhance different aspects of battery research.

Modelling Thermal Effects of Battery Cells inside Electric Vehicle Battery Packs

Introduction: The poster presents a methodology to account for thermal effects on battery cells to improve the typical thermal performances in a pack through heating calculations generally performed under the operating condition assumption. The aim is to analyse the issues based on battery thermophysical characteristics and their impact on the electrical state of battery cells(Khan, Mulder et al. 2013, Khan, Andreasen et al. 2014, Khan et al. 2014, Khan, Mulder et al. 2014, Khan, Nielsen et al. 2014). Based on this analysis, we derive strategies in achieving the goal, and then propose a battery thermal management system with cell-level thermal controls. . Computational Methods: To achieve this, a 3D FEM model of a simplified battery pack is solved in COMSOL Multiphysics with the time varying heat source with different flow rates and in two different cell orientations. The Heat equation is used to model the pack and the classical cooling media e.g. Air and Liquid for the battery pack is implemented. Results: At the end of the discharge, Figure indicates lower temperatures (around 25°C) at the front and higher temperatures (around 30°C) at the rear of the module. Therefore, Figure emphasises the need for a sufficient inlet air velocity for a proper thermal management of the cells located in the rear of the module.