Integrated Drive System with Modularised Energy Storage for Automotive Applications

Vehicle electrification is a major shift in industry bringing a wealth of opportunities. Standard topology EV Powertrains are based on a two level inverter fed by a large single battery pack. Separate onboard charger, DC-DC converter and battery management systems are needed to complete the Power Electronics package. While integration of power electronics with the motor is under active research, it can also be integrated away from the motor in a potentially less harsh environment within the battery pack. Modular Multilevel Converters have the potential not only to allow for modular battery pack and power electronics design but also integration of the Inverter and Onboard Charger within the battery pack itself. As cost and efficiency continue to be the biggest challenges facing vehicle manufacturers today and for the foreseeable future, this research has the potential to offer a different set of design constraints which may benefit certain applications.
The aims and objectives are
Literature review:
1) Understand, document and quantify the requirements and constraints placed upon systems like this in an automotive powertrain application
2) Understand and quantify the benefits and drawbacks brought to powertrain costs and efficiency by the particular topology
Observe Behaviour:
1) Simulate behaviour (Electrical and Thermal) of TLI and MMC topologies (Various submodule designs and number of levels) to replicate observations in Literature review
2) Develop auxiliary models to assist in simulating behaviour of topologies over a number of industry standard drive cycles
3) Determine optimum topologies for various use-cases and ascertain how these relate to each other
Create theory to match states and predict system behaviour in other state:
1) Pick a promising candidate topology from the above and use simulation to predict operation under new use case
2) Compare this against a predicted bad performer (Avoid false positives)
3) Compare this against a predicted unsuited use case (Avoid false negatives)
Test system in other state and validate predictions:
1) Prototype the two candidate topologies and verify they meet the requirements set (Priority on first candidate)
2) Validate the simulation results on HiL rig using prototype drives and loads
The aim is to research the use of low cost low voltage GaN based devices in modular multilevel converter topologies to ascertain their viability in automotive powertrain applications. The main focus would be on high voltage high power heavy duty powertrains. Already used in HVDC power transmission lines, and with some automotive suppliers offering basic 3 level converters already, the design seeks to use low voltage switches in series, to gain High Voltage operating capability. Research has shown more complex versions of these topologies able to simultaneously take on duties of Inverter and on board charger while being an integral part of the battery pack.
The research carried out is at TRL3 where analytical and experimental critical function and/or characteristic proof-of concept work is undertaken. This is at the upper end of the EPSRC's defined funding TRL remit. The theme of the research is vehicle electrification in line with the AAPS CDT remit and the concept potentially allows for lowering vehicle component costs, better managing the battery state of charge and thermal envelope, as well as benefiting design by further integrating electronics and battery into modular systems

Impact Summary

This proposal has been developed from the ground up to guarantee the highest level of impact. The two principal routes towards impact are via the graduates that we train and by the embedding of the research that is undertaken into commercial activity. The impact will have a significant commercial value through addressing skills requirements and providing technical solutions for the automotive industry - a key sector for the UK economy.

The graduates that emerge from our CDT (at least 84 people) will be transformative in two distinct ways. The first is a technical route and the second is cultural.

In a technical role, their deep subject matter expertise across all of the key topics needed as the industry transitions to a more sustainable future. This expertise is made much more accessible and applicable by their broad understanding of the engineering and commercial context in which they work. They will have all of the right competencies to ensure that they can achieve a very significant contribution to technologies and processes within the sector from the start of their careers, an impact that will grow over time. Importantly, this CDT is producing graduates in a highly skilled sector of the economy, leading to jobs that are £50,000 more productive per employee than average (i.e. more GVA). These graduates are in demand, as there are a lack of highly skilled engineers to undertake specialist automotive propulsion research and fill the estimated 5,000 job vacancies in the UK due to these skills shortages. Ultimately, the CDT will create a highly specialised and productive talent pipeline for the UK economy.

The route to impact through cultural change is perhaps of even more significance in the long term. Our cohort will be highly diverse, an outcome driven by our wide catchment in terms of academic background, giving them a 'diversity edge'. The cultural change that is enabled by this powerful cohort will have a profound impact, facilitating a move away from 'business as usual'.

The research outputs of the CDT will have impact in two important fields - the products produced and processes used within the indsutry. The academic team leading and operating this CDT have a long track record of generating impact through the application of their research outputs to industrially relevant problems. This understanding is embodied in the design of our CDT and has already begun in the definition of the training programmes and research themes that will meet the future needs of our industry and international partners. Exchange of people is the surest way to achieve lasting and deep exchange of expertise and ideas. The students will undertake placements at the collaborating companies and will lead to employment of the graduates in partner companies.

The CDT is an integral part of the IAAPS initiative. The IAAPS Business Case highlights the need to develop and train suitably skilled and qualified engineers in order to achieve, over the first five years of IAAPS' operations, an additional £70 million research and innovation expenditure, creating an additional turnover of £800 million for the automotive sector, £221 million in GVA and 1,900 new highly productive jobs.

The CDT is designed to deliver transformational impact for our industrial partners and the automotive sector in general. The impact is wider than this, since the products and services that our partners produce have a fundamental part to play in the way we organise our lives in a modern society. The impact on the developing world is even more profound. The rush to mobility across the developing world, the increasing spending power of a growing global middle class, the move to more urban living and the increasingly urgent threat of climate change combine to make the impact of the work we do directly relevant to more people than ever before. This CDT can help change the world by effecting the change that needs to happen in our industry.