Electrical

Dan’s Race Report

Posted on November 2, 2011 by Daniel Chambers

This is not so much a race report as a summary of the entire year’s efforts, challenges, disappointments and successes. The culmination of all this activity was Australia’s WSC 2011, so in non-chronological fashion I’ll start there.

The most frustrating thing for a group of enthusiastic engineers is to have their efforts and aspirations thwarted by bureaucracy. But that’s exactly what happened when our shipping company refused to give us our container or even accept any form of payment. We spent an unproductive and relaxing two weeks in Darwin without a car to work on. However, what we achieved in the following fortnight after we finally got our hands on the car cannot be overstated. The car arrived in a “working” condition (we’d done some driving back in the UK at Bourn Airfield) but getting the vehicle race-ready took a huge amount of proverbial elbow grease and midnight oil.

We successfully fitted new lights and LED drivers, tested new driver controls and telemetry, performed solar battery charging tests and re-wired a few things that we’d never got around to in the UK, including the rear-view camera. The mechanical guys chipped in with a new set of wheels, worked out…
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Posted in 2011 Car, Electrical, Energy, WSC | Comments Off

The Electrical Team Lights The Way

Posted on July 20, 2011 by Lucy Fielding

The electrical rebuild has accelerated from “rapid” to “frantic” in recent weeks. Numerous tasks compete for the attention of the electrical team, from battery management systems and cell balancing, to lights and driver controls. It’s all got to be done, and recent work has focussed on getting the car ready for testing this weekend.

The battery management system (BMS) is something we’re particularly proud of. Not only does it intercept, interpret and act upon CAN messages from the Lifebatt cell management modules (CMMs), but it also monitors the current into and out of the battery via our Isabellenhütte shunt resistors and shuts off the battery from the rest of the vehicle in the event of a fault.

Posted in 2011 Car, Electrical | 2 Comments

Battery Taxonomy

Posted on June 17, 2011 by Lucy Fielding

Those ardent followers of not only our blog but also our twitter feed (@cuer2011) will have started to hear many names float about in reference to the battery. In deference to their loyalty, and also because it makes a reasonably interesting blog post about batteries, here is a breakdown of the components of CUER’s battery.

We begin with the smallest unit in a battery – the cell. This is a single lithium-iron-phosphate (LiFePO4) cell. A cell is essentially a block of chemistry – in its simplest form, it contains two metal electrodes and an electrolyte (here, LiFePO4). What we often refer to as a battery (e.g. Duracell, Energizer) is actually just a single cell. They work by undergoing oxidation and reduction reactions at the two electrodes; these reactions are complementary and require a flow of electrons. It is this flow of electrons that provides the ‘electricity’ from the cell.

Here is one of our cells:

Posted in 2011 Car, Anatomy of a Solar Car, Electrical | Leave a comment

Progress on the Battery

Posted on June 14, 2011 by Lucy Fielding

Just a quick post about working on the battery pack (“the Kraken”). We have mostly finished the plywood prototype battery enclosure, but still need to finish up a few things:

- Drill a few holes in the side walls for the top cell supports

- Drill holes to mount the contactor(s), DC-DC converter and CAN node.

- Make up as many 10 cell “sticks” of cells as we can and get these mounted. Putting them in the largest bracket set (“the 40-cell Beast”) would be best so that that part is complete.

- Produce interconnects between the blocks of cells (crimp connectors on thick wire with single Anderson connectors).

This stuff should only take about 3 hours (maybe that’s optimistic…).
When we’ve got this sorted we can try and get some BMS software tested on our prototype CAN nodes with the PicKit. We have also produced a rough outline of what we need to run past the guys at LiFeBATT so we can make sure our BMS catches all error states.

Posted in 2011 Car, Electrical | Leave a comment

MPPTs – what’s in a name?

Posted on January 14, 2011 by Lucy Fielding

Following on from the article on solar cells, we continue to disperse the dense fog surrounding electrical engineering to reveal the technology behind CUER’s most-loved acronym* – the MPPT.

First off, let’s get the formalities out of the way. ‘MPPT’ stands for ‘Maximum Power Point Tracker’. This may have been mentioned in previous blog posts, possibly in an attempt to clear away the aforementioned fog. It’s not entirely certain why they thought it would help. It’s unlikely that the response to this revelation was “oh, Maximum Power Point Trackers – they track the maximum power point! Of course! It’s all so clear!” No, this is a PR challenge even Ronseal would struggle with.

However, unlike the average Ronseal customer (or perhaps not?) we are in a position to understand the relationship between the photons reaching a solar cell, and the amount of useful energy we can get out of it. However energy on its own is not a useful measure. A solar array could provide 1kJ of energy – in fact, they all will, if you wait long enough – but an array that produces 1kJ in 0.5s is better than one that produces it in 20s.

Power, then, is…
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Posted in Anatomy of a Solar Car, Auto Technology, Electrical, Renewable technology | Leave a comment

Shining a Light on Photovoltaic Technology

Posted on November 1, 2010 by Lucy Fielding

A solar cell is fascinating, in that it is one of only a few machines that operate with no moving parts. This gives it a potential edge over other energy-generating technologies, which have to contend with energy losses and maintenance costs due to constant motion (e.g. turbines) and heat transfer (e.g. biofuels, nuclear).

The basic premise behind a solar cell is identical to that behind any type of chemical cell or battery – the separation of regions of different electrical potential. An electric current flows when these regions are connected to each other by an electrical circuit, allowing the negatively-charged electrons to flow towards the positive terminal. In a solar cell, this is achieved by the use of semiconductor materials – a certain class of non-metals that, under certain conditions, can conduct electricity.

Posted in Anatomy of a Solar Car, Electrical, Renewable technology | Leave a comment

Inside Nature’s Geeks: the Electrical Engineer

Posted on August 11, 2009 by Dan Wilkins

Time to Zero Hour: 2 weeks

Panic Level: 100-125 bpm

This week, CUER SunSpot takes you on a rather dull extremely fascinating journey inside the world of electrical and information engineering - a world where phases, magnetic fields, currents, voltages and, ultimately, sharp corners* cause a multitude of things to go nastily wrong. Or, alternatively, wonderfully right. But, this being problem-solving week, the probability that there is going to be a blog post about everything working absolutely fine is somewhere down there with you getting to see that live Michael Jackson concert next month…

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Battery Box Completion and Testing

Posted on May 30, 2009 by Dan Wilkins

As the title suggests, the battery box (and all the electronics within it) has been assembled and is currently being tested up at CAPE. We have also shock tested the overall battery, which involved frantically running up and down King’s Parade on the cobbles to see if anything broke (at present, nothing has!). This of course produced a lot of interest, and we had a talk with a group of curious french schoolchildren about CUER, the battery pack, and Global Green Challenge. You never know, we may yet have some more international Friends of CUER!

Many thanks to everyone that helped out, especially James and Andrew for doing the actual trolley-ing! You didn’t look like muppets at all…

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Battery Pack Manufacture Progress

Posted on March 10, 2009 by Dan Wilkins

As technical sub-teams shift focus from design to manufacture, so too has the battery pack project, and the pace of manufacture has stepped up in the last few weeks. As of writing, the three battery modules have been fitted with cells, and initial checks have been done by Chao Yu, the lead designer and manufacturer of the battery pack.

So far the project has progressed smoothly with few delays, thanks in no small part to the contributions by REAPsystems Ltd and Farnell UK Ltd. REAPsystems are supporting the project by donating their battery management systems (BMS), which will be used to monitor and control the operation of the Lithium-polymer based pack for optimal performance and reliability, as well as supplying the team with additional components and design expertise. Farnell UK have kindly donated electronic components and tools to CUER, which has been beneficial not only for the battery pack, but also for the rest of the electrical team’s projects.

- Anthony

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