Shaft Position sensor

Technical discussion on converting internal combustion to electric
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Bukes
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Shaft Position sensor

Post by Bukes »

Hi all, I was looking for a resolver or encoder to provide shaft position / angle data to the inverter for the AC induction motor I’m using.

I’ve really struggled to find something reasonably priced. Even an option on alibaba that was supposedly US$55 / unit has come back complaining about only shipping 1 unit and quoted US$115 a unit. I may lodge a complaint… but only after I’ve found an alternative :p
9C91747E-B250-444A-9D84-9DD4A3710A52.jpeg
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Wondering if instead anyone has tried using a crankshaft sensor used for fuel injection? They’re well established reliable auto tech, and I can get a setup for US$70 (plus shipping). Here’s an example of diy fitting one to an old combustion engine:

https://www.diyautotune.com/news/crank-and-cam-sensors/

In this case the inverter driver is being built (otherwise I assume the manufacturer would provide or specify a resolver or encoder to use).

I couldn’t find any rotary encoders that would fit the shaft in the motor (42mm front output / 40mm back fan), so whatever I do I will need to make a mount for both the trigger and the sensor.

What have other people used to solve this piece of the EV architecture?
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coulomb
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Re: Shaft Position sensor

Post by coulomb »

Bukes wrote: Sat, 08 Jan 2022, 10:56 What have other people used to solve this piece of the EV architecture?
This is what Weber and I (mostly Weber in this case) used for an encoder:

viewtopic.php?p=34430#p34430

We don't seem to have a section on encoder selection, so perhaps it was a no-brainer. You should be able to read the brand at least from the photo. It seems such a tiny thing.

Edit: so you don't have to stand on your head 🙃 I don't seem to have the high resolution original of this photo.

Encoder closeup.jpg
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MG ZS EV 2021 April 2021.
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weber
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Re: Shaft Position sensor

Post by weber »

This is the one pictured above. Not particularly low-cost these days.
https://au.rs-online.com/web/p/motion-c ... %3Atrue%7D

RS have some at lower prices now:
https://au.rs-online.com/web/c/automati ... 4294639672
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Bukes
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Re: Shaft Position sensor

Post by Bukes »

Awesome thanks guys, how did you mount these to the motor shaft?
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coulomb
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Re: Shaft Position sensor

Post by coulomb »

See our published work :)

It's all in the post I linked to earlier. Here is the link again: Weber and Coulomb's MX-5 .
MG ZS EV 2021 April 2021.
Nissan Leaf 2012 with new battery May 2019.
5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.
1.4 kW solar with 1.2 kW Latronics inverter and FIT.
Patching PIP-4048/5048 inverter-chargers.
a4x4kiwi
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Re: Shaft Position sensor

Post by a4x4kiwi »

You may also look at bearings with in built encoders. This is the first one I found after googling.
https://www.skf.com/au/products/rolling ... oder-units
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jonescg
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Re: Shaft Position sensor

Post by jonescg »

Malcolm! Great to see you on here 😀
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Bukes
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Re: Shaft Position sensor

Post by Bukes »

weber wrote: Thu, 29 Sep 2011, 19:55 The following photo shows how we have turned a low cost encoder, intended to be mounted by its case and to have a flexible coupling to the motor shaft, into a shaft-mounted encoder.

Image

We have Araldited a radial stainless rod to the case and we will place its outer end between two stainless pins mounted to the motor body, parallel to the shaft. That way we lock up only the single degree of freedom required to prevent the encoder body rotating, hence it is called an anti-rotation arm.

This allows the encoder shaft to be solidly mounted to the motor shaft, in this case by being a friction fit in a hole drilled in the end of the motor shaft. If the other 5 degrees of freedom were not still available the slightest misalignment would cause a massive load on the encoder's bearing and it would soon fail.

It would generally be better to attach the anti-rotation arm to the other end of the case, nearer the shaft, but in this case the encoder is inside a pulley which drives the pulley of the original air-conditioning compressor (via a belt with an idler for adjusting tension). So the arm has to get past the pulley. The cable has to get past the pulley too, so it will be tied to the arm.

[Edit: Added last paragraph]
Thanks! This makes the job seem straight forward :) I was wondering how to avoid snapping the small shaft
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