Design of efficient power converters for electric vehicle charging and vehicle-to-grid applications

This research presents the design and optimization of bidirectional Dual Active Bridge (DAB) convertersfor electric vehicle battery charging applications, encompassing both heavy and light electric vehicles. The core of the studies is a 5.6 kW DAB converter that can seamlessly transition between 3.7 kW and 11.2 kW power outputs to accommodate different vehicle requirements without the need for circuit component changes. This flexibility is achieved through the novel integration of interleaved and parallel operation capabilities, allowing for efficient operation across a broad power range. Key innovations include the design of a high-frequency transformer with dual secondary outputs to facilitate power transfer at high currents up to 30 A, optimizing thermal design and minimizing the stress on the circuit board. The use of next�generation power semiconductors and low-loss magnetic circuit elements has resulted in an optimized single-stage bidirectional converter design that showcases enhanced efficiency and competitiveness in the field. Furthermore, the converters design enables easy reconfiguration to meet the desired power output, vehicle type, and application needs, making it adaptable for future applications such as Vehicle-to-Grid (V2G) systems. The combination of these features, versatility in power output, efficient high-current transfer, innovative use of power semiconductors, and adaptability for future technologies—positions this DAB converter as a significant advancement in electric vehicle charging technology, offering a scalable solution to meet the evolving demands of electric mobility and renewable energy integration

Suitability of pesticide risk indicators for less developed countries: a comparison

Pesticide risk indicators provide simple support in the assessment of environmental and health risks from pesticide use, and can therefore inform policies to foster a sustainable interaction of agriculture with the environment. For their relative simplicity, indicators may be particularly useful under conditions of limited data availability and resources, such as in Less Developed Countries (LDCs). However, indicator complexity can vary significantly, in particular between those that rely on an exposure–toxicity ratio (ETR) and those that do not. In addition, pesticide risk indicators are usually developed for Western contexts, which might cause incorrect estimation in LDCs. This study investigated the appropriateness of seven pesticide risk indicators for use in LDCs, with reference to smallholding agriculture in Colombia. Seven farm-level indicators, among which 3 relied on an ETR (POCER, EPRIP, PIRI) and 4 on a non-ETR approach (EIQ, PestScreen, OHRI, Dosemeci et al., 2002), were calculated and then compared by means of the Spearman rank correlation test. Indicators were also compared with respect to key indicator characteristics, i.e. user friendliness and ability to represent the system under study. The comparison of the indicators in terms of the total environmental risk suggests that the indicators not relying on an ETR approach cannot be used as a reliable proxy for more complex, i.e. ETR, indicators. ETR indicators, when user-friendly, show a comparative advantage over non-ETR in best combining the need for a relatively simple tool to be used in contexts of limited data availability and resources, and for a reliable estimation of environmental risk. Non-ETR indicators remain useful and accessible tools to discriminate between different pesticides prior to application. Concerning the human health risk, simple algorithms seem more appropriate for assessing human health risk in LDCs. However, further research on health risk indicators and their validation under LDC conditions is needed

Assessment of nitrogen excess in an agricultural area using a nitrogen balance approach

A pilot study has been initiated to develop an approach for quantification of nitrogen excesses from agricultural activities that involve greenhouse farming in Kumluca Plain, Turkey. Detailed calculations utilizing the nitrogen balance method (NBM) were carried out at nine different locations within the plain over a time period of one year. The major contributing factors and governing operative mechanisms taken into consideration were nitrogen application rates both as organic and chemical fertilizers, irrigation water application practices, and nitrogen uptake by plants. The adopted approach yielded valuable information such as plant nitrogen uptake efficiencies, excess nitrogen, leaching rates and leachate nitrogen concentrations. Further, a site specific multiple linear regression model has been developed to estimate the ratio (Nleachate/Ngroundwater) as a function of independent variables: farming age, excess nitrogen application and SEEPAGE Index Number. The negative sign of the model parameters implies that the ratio (Nleachate/Ngroundwater) decreases as values of the independent variables increase. The adopted approach and the obtained results can beneficially be applied to similar sites to establish basic parameters of irrigation and fertilizer application operations.</jats:p

Evaluation of performance and environmental benefits of a full-scale pump as turbine system in Antalya water distribution network

Abstract In recent years, pumps used in turbine mode (pump as turbine, PAT) have started to appear as a viable option to reduce pressure in water distribution networks in addition to energy production at micro scale. In this study, evaluation of performance of a recently installed PAT system in Antalya City, Turkey, is presented for the first operational period of approximately 5 months. This full-scale PAT system was implemented in a parallel pipeline with a pressure reducing valve. The operation of the installed PAT system was continuously monitored online for flow rate, power and pressure. The installed PAT system, being in operation since 26 January 2016, works efficiently in a wide range of inflows (130–300 m3/h) and the produced energy varies between 0.7 and 8.4 kWh for a reduction of approximately one bar pressure head with an average efficiency of 60%. Based on the initial 5 months of operational data, environmental benefits of green energy production, reduction in physical water losses and carbon dioxide emissions were evaluated. Based on the implementation cost of the PAT system and the revenues from the environmental benefits, payback period of this specific full-scale PAT application was computed as 53 days or 1.8 months.</jats:p