The Smart Current Limiter is a switching DC to DC converter that provides a digitally pre-set input current control for inrush limiting and power management. Being able to digitally adjust the current level in combination with external feedback can be used for control systems like temperature control in high power DC appliances. Traditionally inrush current limiting is done using a passive resistance whose resistance changes depending on the current level. Bypassing this inrush limiting resister with a Mosfet improves efficiency and controllability, but footprint and losses remain large. A switched current mode controlled inrush limiter can limit inrush currents and even control the amount of current passing to the application. This enables power management and inrush current limitation in a single device. To reduce footprint and costs a balance between losses and cost-price on one side and electromagnetic interference on the other side is sought and an optimum switching frequency is chosen. To reduce cost and copper usage, switching happens on a high frequency of 300kHz. This increases the switching losses but greatly reduces the inductor size and cost compared to switching supplies running on lower frequencies. Additional filter circuits like snubbers are necessary to keep the control signals and therefore the output current stable.
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Municipalities often collaborate with other stakeholders in smart city projects to develop and implement technological innovations to address complex urban issues. We propose the shared portfolio approach as an alternative way of collaborating, because we have identified possible limitations when the commonly used single-project approach is adopted in complex contexts, such as the smart city context. The portfolio approach enhances flexibility, an embedded focus and cross-project learning, because partners work on multiple projects – either in parallel or in succession – to develop multiple solutions to a specific problem. An in-depth case study is used to illustrate how the shared portfolio approach works. In practice, these insights can be used by public bodies who aim to collaborate in smart city development or by partners who work on smart city projects and wish to continue their collaboration in a portfolio setting. Conceptually, our paper develops a connection between cross-sector partnership literature and smart city literature by revealing how the shared portfolio approach could be an effective way to deal with the complexities of innovation in the smart city context.
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As the Dutch electric vehicle (EV) fleet continues to expand, so will the amount of charging sessions increase. This expanding demand for energy will add on to the already existing strain on the grid, primarily during peak hours on workdays in the early morning and evening. This growing energy demand requires new methods to handle the charging of EVs, to distribute the available energy in the most effective way. Therefore, a large number of ‘smart charging’ initiatives have recently been developed, whereby the charging session of the EV is based on the conditions of the energy grid. However, the term smart charging is used for a variety of smart charging initiatives, often involving different optimization strategies and charging processes. For most practitioners, as well as academics, it is hard to distinguish the large range of smart charging initiatives initiated in recent years, how they differentiate from each other and how they contribute to a smarter charging infrastructure. This paper has the objective to provide an overview of smart charging initiatives in the Netherlands and develop a categorization of smart charging initiatives regarding objectives, proposed measures and intended contributions. We will do so by looking at initiatives that focus on smart charging at a household level, investigating the smart charging possibilities for EV owners who either make use of a private or (semi-)public charging point. The different smart charging initiatives will be analyzed and explicated in combination with a literature study, focusing on the different optimization strategies and requirements to smart charge an electric vehicle.
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