Doru A. Nicola

The Exergetic and Environmental Impact Assessment of Underground Electric Train Braking

Within the present industrial society, some of the greatest challenges of humanity are related to achieving a sustainable industrial metabolism, which integrates technical activity and ecological systems. Electric traction drive systems using induction motors fed by variable voltage variable frequency (VVVF) inverters have provided high performance for urban electric trains. Moreover, power converter technology based on advanced techniques in control electronics and efficient anti-slip systems allows optimum traction characteristics and minimum energy consumption. For underground electric trains, however, it is also important to assess the environmental impact of braking. From the viewpoint of exergy and environment, the braking regime, particularly electric braking, is a special aspect of non-autonomous vehicles using electric traction. As electric drive systems are used with VVVF inverters and traction induction motors, these machines with appropriate controls can realize both traction and electric braking regimes for electric traction vehicles. Concerns regarding mechanical braking are associated with unrecovered energy and material utilization. Also, for underground electric trains during mechanical braking, the abnormal but frequent situation involving the unequal charge of the traction induction motors is a concern. These aspects of underground electric trains are analysed in this article so as to assist in improving performance.

SIMULINK model for study of energy efficient train control

This paper presents the mathematical model of the useful movement of the electric vehicles. On the mathematical model basis it is built the structural diagram and the SIMULINK model associated of the useful movement. The SIMULINK model is used to calculate the energy consumption for different running regimes and different route configurations and to identify energy efficient train control methods.

Utilizing the Exergy Concept to Address Environmental Challenges of Electric Systems

Theoretically, the concepts of energy, entropy, exergy and embodied energy are founded in the fields of thermodynamics and physics. Yet, over decades these concepts have been applied in numerous fields of science and engineering, playing a key role in the analysis of processes, systems and devices in which energy transfers and energy transformations occur. The research reported here aims to demonstrate, in terms of sustainability, the usefulness of the embodied energy and exergy concepts for analyzing electric devices which convert energy, particularly the electromagnet. This study relies on a dualist view, incorporating technical and environmental dimensions. The information provided by energy assessments is shown to be less useful than that provided by exergy and prone to be misleading. The electromagnet force and torque (representing the driving force of output exergy), accepted as both environmental and technical quantities, are expressed as a function of the electric current and the magnetic field, supporting the view of the necessity of discerning interrelations between science and the environment. This research suggests that a useful step in assessing the viability of electric devices in concert with ecological systems might be to view the magnetic flux density B and the electric current intensity I as environmental parameters. In line with this idea the study encompasses an overview of potential human health risks and effects of extremely low frequency electromagnetic fields (ELF EMFs) caused by the operation of electric systems. It is concluded that exergy has a significant role to play in evaluating and increasing the efficiencies of electrical technologies and systems. This article also aims to demonstrate the need for joint efforts by researchers in electric and environmental engineering, and in medicine and health fields, for enhancing knowledge of the impacts of environmental ELF EMFs on humans and other life forms.