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High Power Charger For Electric Vehicles

Periodic Reporting for period 2 - HPCForEVs (High Power Charger For Electric Vehicles)

Reporting period: 2018-08-01 to 2019-07-31

While reserves of fossil fuels are depleting, raising serious environmental concerns, major European and Asian countries (CN, IN, UK, FR, NO, NL, DE) have announced plans to phase out petrol and diesel cars and completely transition to the EV market as early as in 2030. Despite the fact whether there is a complete phase out of petrol and diesel cars or not, the trend is clear. The Electric vehicle, EV, market is significantly increasing, and the infrastructure needs to be prepared to accommodate such a revolution.
Meanwhile, a global transition towards renewable energy sources is followed by increased fluctuations of electricity production. Fluctuations in demand generated by increasing number of EV’s combined with fluctuations in supply generated by renewable energy sources are the key challenges to stability and quality of electrical power grids. Another major challenge for electrification of the transport sector is the availability of EV chargers and the hours needed to fully charge an electric vehicle compared to the minutes needed to fill the tank on a combustion-engine vehicle.
To overcome these challenges, the technical development as well as social acceptance of both EV charging stations and in-grid installations that can deal with 2-way fluctuations, must be carried out in parallel complementing and supporting each other. Ideally, a BEESS, battery electrical energy storage solution, operated by the Nerve Switch® technology stack, provides the solution as well as improves overall system efficiency and reduces the costs.

Aiming to utilize the idea behind the Nerve Switch®, the HPCforEVs project focused on:
1. Exploration of a novel BMS, Battery Management System, the Nerve Switch®, that allows for optimal single cell control and supervision, higher energy efficiency, increased system reliability and optimization of system’s lifetime.
2. Development of a modular and scalable battery system incorporating and exploiting the Nerve Switch® technology for battery cell topology variation during operation, thereby replacing most DC power electronic components.
3. Design of an HPC, High Power Charger, in full compliance with the CCS communication standard able to connect directly to a Nerve Switch®-equipped battery system.
4. Market maturity of a Nerve Switch®-equipped battery-buffered HPC for EVs, characterised by lower initial acquisition costs, improved profitability and reduced environmental impact.
5. Evaluation of the potential for the Nerve Switch® technology stack to be used in control systems for a variety of the energy conversion, storage and transmission systems with variable topologies.
The achievement of all objectives relied on the core Nerve Switch® technology which was successfully realised.
The Nerve Switch® is based on the idea of being able to control each individual cell in the system and thereby manage the power output directly at cell level. This is achieved by removing central power electronic subsystems in a battery system and integrate parts of the active electronics components (i.e. the power transistors) directly at the individual battery cells.
The Nerve Switch® replaces the conventional BMS and extends the monitoring with individual battery cell control. In extend, nominal voltage and current of the battery system can be regulated directly by controlling the number of individual battery cells that are engaged or bypassed.
In contrast to conventional BMS, the Nerve Switch® is capable of actively balancing the battery cells state of health. Since differences in state of health of the individual battery cells is usually the cause for imbalances in their state of charge, Nerve Switch® enabled battery systems will have a considerably longer lifetime.
The Nerve Switch® concept was demonstrated, is now fully functional and can be scaled from laboratory to technology demonstrators. A detailed analysis of possible designs for the Nerve Switch® circuit was made. The current fifth design revision is now being certified according to international standards.
Based on the Nerve Switch® technology, a modular and scalable stationary battery system for 19” rack systems were designed and developed. A unique HW and SW based thermal management system for the battery cells and the Nerve Switch® was developed. Highly competitive Energy and Power density of 8kWhel and 12kWel, in 6u rack heights was achieved. Grid connection can be done with most AC/DC-inverters and operated at all time close to their maximum efficiency
A completely new design for an HPC station was designed. The charger can be directly coupled to a Nerve Switch® operated battery system without dedicated DC-DC power electronics. This facilitates a simpler and less expensive system integration with higher overall efficiency and flexibility.
Several prototypes and technology demonstrators of Nerve Switch®-equipped battery electric energy storage systems were installed during the project and others are scheduled to serve as proof of concept of the Nerve Switch® technology stack.
Dissemination focused primarily on exhibiting, speaking at conferences and having 1:1 meetings with potential stakeholders. General communication such as press releases and LinkedIn posts have been well received and reposted by various medias, which has generated a lot of interest. In extend several patent applications and invention disclosure reports are generated to extend the Nerve Switch® technology stack to a variety of other applications.
The design of the electronic circuitry of the Nerve Switch®, was improved to handle higher currents and voltages. Furthermore, it’s capability for faster and smoother engaging and bypassing battery cells to facilitate topology variation in the battery system was integrated. In addition, it was successfully demonstrated that in-line linear current regulation is possible in a Nerve Switch®-equipped battery system.
A prototype of an integrated silicon-carbide-based transistor in form of a direct copper-busbar integration was successfully developed and tested, enabling higher switching frequencies combined with lower internal impedance by using state of the art SiC-based transistors as power switches.
The Nerve Switch® technology enables an efficient and reliable battery system at lower costs. Conventional battery management systems, and their limitations, are being entirely replaced whereas power electronics subsystems are made redundant to a great extent.
The modularity and scalability of the Nerve Switch® technology motivates early investments in battery systems. The ease of use and the low/none operating maintenance will be decisive for smaller integrations of Nerve Switch®-equipped battery systems; the same battery modules with the Nerve Switch® technology can be used for storing electric energy from a solar panel in residential houses as well as for discharging electric energy for coping with grid fluctuations or to charge an electric vehicle.
It is indisputable that battery systems have a socio-economic importance within a sustainable energy transition and to reduce CO2 emissions. Fluctuations in demand and supply of electric energy caused by inconsistencies in supply of renewables and demand by electric vehicles can be met with battery electric energy storage solutions. The primary perquisite for this is cost and efficiency of reliable battery systems – which the Nerve Switch® will be a key driver for.
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