Here’s the latest video. It’s got stuff about water boilers, IGBTs (which I talk about further in this post), a brakes test and revs testing. I’m guessing there’s probably only a couple more videos to go as finish time approaches. Most of the scenes in all the videos have been shot on a Nokia N93 which has been very handy.
Will we get more EVs in 09?
I get that question a lot, along with the usual ‘fuel prices are cheap so why bother’ comments. I am not concerned; there are many other benefits to not having to use gas. An ideal world should have 80% of cars as EVs – oil is used in so many other things we take for granted. Anyway, I will not ramble, it’s new year and all that!
Other Stuff such as BMS Conformal Coating…
The BMS conformal coat has been interesting…
When compared to an unpainted module, one can see the film coat which has a tinge of blue – actually when a blacklight is shone on the BMS, it glows all spooky-like -it’d be neat to have a UV light under the hood to show a glowing engine bay for an exhibition. Hmm…. Anyway, I’ll show this in the next video.
BMS curing in military-grade conformal coating.
Electric ‘Turbo’? Oh Yeah!
An IGBT was used in the tacho send test in the video. These are chunky Insulated Gate Bipolar switching devices able to handle massive currents and could be used more commonly in future motor controllers; a few in parallel can replace a dozen or so MOSFETS. After some experimentation, large IGBTs capable of handling over 2000A could be configured to allow for a kind of ‘electric turbo’.
We could set these up to switch in when reaching a certain speed or manually cut in when required. The idea is to bypass ancillary and other voltage dependent devices for a short moment, effectively giving us a ‘boost’ direct from the battery pack when needed. This is tricky and there is a big risk of failure. What’s more, destroying an IGBT can be a costly exercise.
Have a look at the types we’re talking about…
http://www.pwrx.com/TechnicalDocument.aspx?id=750
These things have freewheeling diodes, and from my limited understanding that means they’re there to stop reverse current voltage spikes across the inductive load. When the current flow to an inductor is suddenly interrupted, the inductor attempts to maintain the current by reversing polarity and ramping up the voltage to maintain the flyback. Without the diode the voltage can go high enough to damage the IGBT. The diode allows the reverse current to flow through it and dissipate. It is important to confirm the maximum voltage that can fly back safely. Over-driving an IGBT is costly.
A Good Adaptor Plate Machining Video
And speaking of motor revs, more specifically, the adaptor plate that houses the hub, have a look at http://www.youtube.com/watch?v=L1A6ulxTEMQ&sdig=1 which shows an adaptor plate actually being machined up – excellent!
