Electric & Hybrid Vehicle Technology - July 2021
Pride of Britain
James Billington 2021-07-20 04:09:31
The Fab
A dream team made of British electric propulsion companies, academics and engineers are working collaboratively on the Triumph-TE 1 electric motorcycle project. We speak to all the partners involved in the unique arrangement to understand each part of the groundbreaking bike’s anatomy
Two-wheeled vehicles represent a significant segment in the shift to zero-emission mobility. As such, the global electric motorcycle market is expected to reach US$41bn by 2028, growing at a CAGR of 3.09% from 2021. Buoyed by a growing number of manufacturers tilting towards non-IC powertrains, the movement is currently highlighted by iconic motorcycle maker Harley-Davidson, who was surprisingly one of the first to rollout its fully battery-powered LiveWire bike.
Now we can add another iconic two-wheel brand to this list, Triumph, which is currently entering the testing stages of its TE-1 project – a collaborative effort funded by government initiative Innovate UK to improve electrification technology for motorcycles. It involves Williams Advanced Engineering, Integral Powertrain, WMG at the University of Warwick, and Triumph.
First announced in 2019, the project is now into its second phase with the battery and powertrain prototype revealed. So far, teams have been working on all the specification settings, benchmarking, the battery system, control unit for the battery and bike itself.
For the engineers working on the motorcycle, it presents a different set of challenges compared to electric passenger car development. Triumph has led the requirements from a bike perspective, but collaboratively the partners have tried to push the boundaries for electric propulsion – whether it’s the battery, motor or inverter.
DYRR ARDASH
senior commercial manager, Williams Advanced Engineering
How different is it working on a two-wheeled vehicle compared to typical passenger cars?
This is one of those really interesting opportunities. Here, the levels of system integration that we’ve had to apply requires a different approach. Considering the packaging space, we have to ensure we have the energy to meet the range while reducing the mass of the propulsion system as much as possible and still delivering performance. One of the key things of this is that the battery is a structural member of the bike and additionally we’ve tried very hard to keep the center of gravity as consistent as possible, similar to a regular IC bike. The sensitivity of just millimeters will affect how the bike will feel so we’ve done quite a lot of work on that.
Talk us through the battery and also how you’ve mitigated the issue of impact protection?
The layout of the battery is unique to the TE-1 program as it utilizes our next generation of module that we have designed and developed for future vehicles. It draws upon all our experience and knowledge of WAE’s decade of developing electric powertrains.
The overall efficiency is 150Wh/k, which might not sound like an amazing figure but when you consider the size of the pack and include all the charge ports, charge control hardware, the battery management system, the DC/DC, motorbike control ECU, that’s quite impressive. We’ve done significant work on CAE to look at potential impact and crashes. We then integrated the battery within the bike frame to ensure it is as robust as possible. There are specifics of the structural elements that we’ve included to overcome challenges of impact.
How is the battery cooled and what thermal management technology has been integrated?
It is a liquid-cooled battery and is run off completely different circuits to the motor to optimize performance. We spent a lot of time doing CAE work to develop the thermal cooling around the pack to make sure the battery cell technology is keeping at its most optimum temperature. We also selected cell technology that will allow significant performance for longer. It was class-leading in benchmarks against other products we have tried and tested. Another important aspect is being able to take a faster charge than other existing bike technology – we can charge the pack in under 20 minutes from 0-80% SOC. It uses a 350V battery architecture with a CHAdeMO DC charge port.
Did you introduce any new construction techniques or materials for the battery?
We are using a combination of existing technology and there are some new techniques we have introduced for the first time to put the battery pack together. As for materials, there are some interesting elements used but at this stage we cannot reveal what they are. What I can say is, though, it is significantly moving the game forward for mass efficiency for a battery pack.
What did you learn from other electric motorcycles already on the market?
We’ve looked at the majority of EV motorcycle products out there from a benchmarking perspective – we liked some things and didn’t like others. There are some specific attributes that we want to be class-leading – in terms of performance for longer, range, charging, and mass distribution. We will be able to achieve 120 miles on the WLTC cycle.
ANDREW CROSS
chief technical officer, Integral Powertrain (e-drive)
How have things developed for TE-1 over the course of phase 1?
It was very much a blank sheet at the start of the project in terms of what sort of motor and inverter we could make. Across the partners, we’ve produced a specification that was outlined within the first three months of the project.
For the design, we have produced a very compact motor based on our electric machine core technology, but its new feature is a scalable integrated inverter within the architecture. As we increase the diameter of the machine for larger package size and larger torque requirement we can grow that scalable power.
What’s it like designing an electric motor for a two-wheeler as opposed to a passenger car?
In most electric vehicle applications space and weight is an absolute premium and within a motorcycle, this is even more so. The challenge is getting the motor and inverter as light as possible and to make space for a battery that offers good range and efficiency. The more efficient a powertrain is, the less battery is needed for the same range. Very low loss powertrain technology with a silicon carbide power stage in the inverter means we can keep those losses to a minimum and either maximize range or minimize energy store mass.
The motor is literally pint-sized. How much of a challenge was it to be able to produce power from such a small package?
It’s spinning at around 20,000rpm, so in the first instance, it’s challenging to minimize AC losses and high frequency loss. Then, of course, it’s managing the heat, so having very good thermal performance in a way that’s robust and safe is hard but important. The motor uses our advanced cooling technology and some patented features to make the high power density.
What cooling technology is used?
On one level have a very conventional ethylene-glycol-water mix as the carrier of heat. That’s technology inherited from conventional IC engine cooling. It’s a very low-risk, proven approach and water is practically the best cooling medium. As we go into the motor and inverter, the cooling between the two is shared so it reduces the number of housing parts, pipework and connections required. There is a detail in getting the heat through from the copper and iron in the machine and also created in the SiC semiconductors out to coolant. That’s part of the nearing task.
How have you been testing the motor and what sort of benchtesting results have you seen thus far?
The new motor will be the same for the final demonstrator as the mule bike. We built and tested this using all the dyno work with full power and torque and mapping of the motor and delivered that to Triumph where it is now being built into the bike. It is precisely in line with our simulator expectations. On the inverter, it’s a new power stage and it’s exceeding our expectations from the simulation so we can deliver a more continuous current than we needed.
PHIL WHIFFIN
head of advanced propulsion systems, WMG
How did WMG get involved in the project?
We’re a department made up of half academics and half industry, so we get involved in collaborative projects. We’ve collaborated with over 1,000 companies since we started and we’ve been involved with passenger car electrification and major OEMs for a long time. We helped bring together the consortium for this.
What simulation technology was used for the TE-1?
Our main role in the project is the model simulation, which helps with the analysis and identifying if the targets being set are feasible. Initially, we were able to model the motorcycle over certain drive cycles, looking at the behavior of the bike and the rider. It enables us to look at whether if we were to increase the mass of the bike by X, what it does to the range, etc. There are all sorts of different motorcycle drive cycles used to work out range, but then there are some special cycles from the partners which we replicated in the simulation.
We also work on the stability model which looks at slip, lean angles, and traction control modeling. As the model has become more detailed from simulation it has enabled us to try out some advanced control techniques.
With the mule bike now being built, we will be in a situation where we know the control and safety systems work, we know where the efficiencies gains and losses are, which means we’re not going to find issues out later on. It’s also a lot easier to make changes try things out we just wouldn’t do when if we built multiple physical bikes.
Have there been any challenges in the project?
There’s a lot of integration and innovation from all the partners so trying to manage all that and bring it all together is a challenge. But that’s why we do all the simulation and HIL rigs so you can minimize the risk of some of that innovation and try it out in a safe and repeatable environment without damaging the motor or battery.
What has funding meant for this project?
The UK government is focused on electrification, which is a good thing so there are a lot of opportunities. It’s not just about the money side of things. One of the benefits of a project like this is that the risk is shared. In a collaborative project the partners are a lot more innovative and you can move things forward more. It’s also a lot more open than you would find in a standard commercial relationship.
STEVE SARGENT
chief product officer, Triumph Motorcycles
When did the idea for Triumph to go electric happen?
It was never this Big Bang moment. We keep an eye on trends in the market – not just the motorcycle market, but in the automotive world, legislation, and political sentiment. At board meetings there has been regular discussion around the progress of electrification and how fast it might come into our particular segment of the market. It’s about finding the right time and the right opportunity to make a move.
How did Triumph respond to Harley-Davidson’s LiveWire?
As soon as Harley started showing off its prototype we were all over it, trying to understand what they had done and what they were trying to achieve with it. They took that bike around getting customer feedback and perhaps unbeknownst to them there were a number of Triumph people actually registered and managed to get on the test rides of the bike.
As soon as we possibly could we were trying to understand what the capability of it was. But that was never really the starting point of our objective, what we really wanted to do was understand from a customer perspective what kind of motorcycle would persuade a rider off an IC engine bike onto an electric one.
How have you designed the TE-1 to integrate the battery and powertrain?
We started with an understanding of the kind of wheelbase that we needed and the steering geometry but most important was the weight distribution. To get a motorcycle to handle properly you have to get the right distribution from front to rear but also the perfect center of gravity. There has been a lot of discussion within this project with the partners who have focused on that weight distribution aspect.
For WAE, for example, when they’re developing a battery for a four-wheeled vehicle they’ve got a very large floorplan to play with, but for us, they had to consider the overall size of the battery but also the internal construction where the weight was going to sit so it fitted with the weight distribution we needed.
We’ve focused very much on the center gravity on the bike and the weight distribution within the battery to result in a weight that is very similar to a conventional motorcycle powertrain.
What are you learning from this project?
Electric vehicles are completely new to us. We’re discovering what is possible. Resetting our understanding our expectations of what we can get out of the motorcycle, has been a big learning curve. We have years of experience developing throttle maps, traction control maps, ABS setting, etc for a conventional motorcycle. How we go about developing that for an electric cycle is a new process for us, as well as additional considerations such as regenerative braking and what it does to the chassis dynamics.
How do you think the TE-1 will transform the landscape for electric motorcycles?
It will hopefully excite people about what a Triumph electric motorcycle could be. That change in opinion is a very important part of the future of electric vehicles. Of course, being an Innovate UK project, one of the key objectives is that partners involved in the project develop IP that they can sell onto other companies who can use it on their vehicles
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