Application of Power Electronics in Hybrid Fuel Cell Powertrains

Growing environmental concerns have led to a huge interest in renewable energy sources. Fuel cells have the potential to be one of these sources. They are very well suited for automotive and working machine applications, where they can replace internal combustion engines. Unfortunately, the load profiles in such applications contain a large number of high transients including regenerative braking peaks. In order to maximize the fuel cell lifetime and to enable the ability to recover braking energy, the fuel cell has to be paralleled with energy storage systems like batteries and supercapacitors or both. The resulting system is called a hybrid fuel cell powertrain. A hybrid fuel cell powertrain can be constructed without power electronics but only in special applications. Practical hybrid powertrains require the use of power electronic converters from which DC/DC conversion is perhaps the most important. The dynamic behaviour of every energy source associated with the powertrain has to be understood in order to design proper DC/DC converters. Especially fuel cells are low-voltage high-current devices requiring the use of high-power DC/DC converters with low input-current ripples. Various topologies have been proposed to fulfil this requirement and the requirements of energy storage systems as well. In addition to the topological issues, the control design of the converters is equally important for assuring stable powertrain operation and sufficient transient dynamics. The results obtained from the simulations imply that a well-behaving powertrain can be realized, provided that the control loops are designed properly. The results emphasize the need for proper sizing of the powertrain components and the need for choosing correct powertrain configuration with appropriate voltage levels. It can be determined from the results, that even though a powertrain equipped with power electronic converters is more complex than a powertrain without such devices, it has very clear and strong advantages. /Kir1

Application of Power Electronics in Hybrid Fuel Cell Powertrains

Growing environmental concerns have led to a huge interest in renewable energy sources. Fuel cells have the potential to be one of these sources. They are very well suited for automotive and working machine applications, where they can replace internal combustion engines. Unfortunately, the load profiles in such applications contain a large number of high transients including regenerative braking peaks. In order to maximize the fuel cell lifetime and to enable the ability to recover braking energy, the fuel cell has to be paralleled with energy storage systems like batteries and supercapacitors or both. The resulting system is called a hybrid fuel cell powertrain. A hybrid fuel cell powertrain can be constructed without power electronics but only in special applications. Practical hybrid powertrains require the use of power electronic converters from which DC/DC conversion is perhaps the most important. The dynamic behaviour of every energy source associated with the powertrain has to be understood in order to design proper DC/DC converters. Especially fuel cells are low-voltage high-current devices requiring the use of high-power DC/DC converters with low input-current ripples. Various topologies have been proposed to fulfil this requirement and the requirements of energy storage systems as well. In addition to the topological issues, the control design of the converters is equally important for assuring stable powertrain operation and sufficient transient dynamics. The results obtained from the simulations imply that a well-behaving powertrain can be realized, provided that the control loops are designed properly. The results emphasize the need for proper sizing of the powertrain components and the need for choosing correct powertrain configuration with appropriate voltage levels. It can be determined from the results, that even though a powertrain equipped with power electronic converters is more complex than a powertrain without such devices, it has very clear and strong advantages. /Kir1

Method for dimensioning battery and thermal management systems for heavy-duty vehicle applications using aged battery experimental data and advanced modelling techniques

During the life of a Li-Ion battery, capacity and power capability fade. Despite this degradation, an electric vehicle battery needs to deliver designed power performance until battery end-of-life. Comprehension of battery performance degradation is required to design sufficient margin for power capability and thermal management. This paper proposes battery laboratory testing combined with advanced modelling techniques to obtain design parameters based on aged batteries. Laboratory cell aging and characterization tests are performed to parametrise models, which are used to verify electric city bus battery performance at various lifetime levels. The modelling gives an indication on the level of margin that needs to be designed for power capability and thermal management. The results obtained indicate that from performance point of view, the battery that was studied can be utilized well beyond 80% capacity point while still retaining power capability and low cell level power losses.</jats:p

Improving the Cybersecurity Awareness of Finnish Podiatry SMEs

In the health and welfare sector, many entrepreneurs and employees are not skilled in information and cybersecurity, even when they are constantly dealing with sensitive data. This case study research examines a team of private Finnish podiatrists and their cybersecurity capabilities. The goal of the study is to gather the most important information and cybersecurity topics and create an easy to-read guide that helps businesses find the framework for their information and cybersecurity and address it in more detail. The results of the case study show that the target organization's most important information and cybersecurity areas are phishing, secure environment, secure communication, passwords, software updates, backups, and physical security. Understanding these topics and following the planned guidelines will strengthen the security posture of all small and medium-sized enterprises (SMEs) in the health and welfare sector