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Old 07-18-2014, 12:23 AM   #6701 (permalink)
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Originally Posted by MPaulHolmes View Post
We can also try a higher frequency (say, 15KHz) if the hissing gets annoying, but there will be more heat loss. Instead of spread-spectrum, I wonder if we could do the Jetson's car sound? I bet we could. It might take quite a bit of memory, but we have the space.
The hiss is not bad, much better than the whine. I will be interested in what other people think.

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Old 07-18-2014, 12:46 AM   #6702 (permalink)
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Quote:
Originally Posted by MPaulHolmes View Post
We can also try a higher frequency (say, 15KHz) if the hissing gets annoying, but there will be more heat loss. Instead of spread-spectrum, I wonder if we could do the Jetson's car sound? I bet we could. It might take quite a bit of memory, but we have the space.
Here's a short article about manufacturers trying to find a sound for electric cars.
Adding Sounds to the Silence of Electric Cars | Public Radio International

They should hire Paul as a consultant, he has it solved already. The Jetsons sound would be fun but i think the spread spectrum sound is a winner. Audible, not annoying, generated buy the motor itself so no extra equipment required. Also i imagine a highway full of hissing electric cars would be less offensive than a highway full of roaring ICE vehicles.
The sound probably wouldn't travel very far compared to the lower frequency exhaust sound of an ICE vehicle.
The sounds they proposed in the article would be awful when a large number of vehicles were involved and they were travelling both towards and away from you creating freaky doppler variations and combinations. I am imagining the sound you get when you step into a very large, very busy and very loud video game arcade.
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Old 07-18-2014, 12:06 PM   #6703 (permalink)
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Rest assured, say the sound experts, that one way or the other, the cost of adding noises to electric vehicles will end up in the sticker price.
haha. In a way, they are right. In order for spread spectrum to work, it has to run at a lower frequency, which makes for less heat generation, which reduces the amount of cooling necessary, which lowers the overall price.

Since it seems that the driver section is working, I feel safe now to finish the AC board, and send it in. Spread spectrum switching can be used in the AC case too.
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Old 07-18-2014, 12:37 PM   #6704 (permalink)
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The Jetson's sound would be a great start.

Would the pitch changes when the speed changes?

There is a new electric Harley that is being shown - it sounds, to me, more like a lower pitched turbocharger whine. You can hear it during a couple of the videos here Harley Davidson Livewire electric motorcycle taken out for first spin in NYC | Mail Online

Best to avoid that sound ... Harley aggressively guards it's signature sounds ...
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Old 07-18-2014, 04:28 PM   #6705 (permalink)
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Personally I like the "Flubber" sound ! Mine has a "Hemi" sound so I can get pulled over for not having a muffler ......
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Old 07-20-2014, 03:43 AM   #6706 (permalink)
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Paul,

I stumbled upon this; http://www.evbmw.com/igbt.pdf.. very interesting..

and wondered.. don't we need those snubber capacitors also?
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Old 07-20-2014, 05:20 AM   #6707 (permalink)
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The sbe cap is like one big snubber. It's one of the selling points. They actually advertise that it eliminates the need for a snubber cap. The stray inductance of that capacitor, assuming a laminated bus, is less than 15nH. (Also, Fran told me about using a film cap for the bus capacitor. He added a snubber cap, and it caused problems.)

Notice that they appeared to be using electrolytics in the pdf. So their ESR may have been 1000 times greater than the 150microOhms of the SBE ring cap. And their stray inductance would be much bigger too.
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Old 07-20-2014, 05:29 AM   #6708 (permalink)
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I actually use snubbers with SBE cap and didn't see any strange things in scope patterns; looks like they don't hurt anything but also don't give to much benefit in this application (laminated bus + low inductance film cap).
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Old 07-20-2014, 07:25 AM   #6709 (permalink)
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Paul,

I don't know if it is on purpose, but:
the serial command lists params with an underscore, and you need to set them with a dash (in stead of underscore)
Took me a while to find out.. but once you know it doesn't matter.
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Old 07-20-2014, 09:59 AM   #6710 (permalink)
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That is really good to know, z-power! Flores, do you have a practical way to scope from collector to emitter (B+ to M+)? It was not very practical for me. Given a 12v golf cart.

Fran had done that (dashes and underscore) in the original code, so I had been trying to keep it as consistent as possible.

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