Alta electric dirtbike OEM project

Tell us about the project you do with the open inverter
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mjc506
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Re: Alta electric dirtbike OEM project

Post by mjc506 »

Hopefully 'parcel day' won't be too long :)

I don't know a huge amount about resolvers I'm afraid - I'm using a Melexis MLX91204 sin/cos encoder chip on mine, which works well but needed some fiddling (requires 5V power supply, so needed a couple potential dividers to get the output down to 3.3V levels). I have seen reports of RLS resolvers working well and Johu also recommended a different (3.3V) Melexis chip - have a read of this thread (towards the end, there's a lot of problems earlier on) viewtopic.php?f=14&t=1225&hilit=sin+cos&start=50
marengo
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Re: Alta electric dirtbike OEM project

Post by marengo »

Yes so the issue is that the openinverter board supplies 5V for all generic rotor sensors. It wants sine waves in return centered around 1.65V. The problem is that the specific sensor you and I have chosen centers around 2.5V, so that has to be "conditioned" downward to feed johubrain its' preferred diet:)
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Re: Alta electric dirtbike OEM project

Post by mjc506 »

Nothing stopping you pulling 3.3v from elsewhere on the board. And it's also designed to generate the excitation signal for a resolver. Either way, a potential divider will do the job, just try to get the centre as close as possible to 1.65v (there will be a setting in the next firmware release to account for 'off center' signals from a sincos chip, and it already measures the centre for a resolver)
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Re: Alta electric dirtbike OEM project

Post by marengo »

20210415_164442.jpg
The sine cosine sensor got here in 4 days via DHL. For some reason, DHL is sitting on the open inverter since April 1.

Next step is to get it installed into the alta housing. I ordered some trigger magnets that go on the end of the motor shaft. They look the same but one is a higher grade for applications needing more than 10 bit resolution. What resolution do I need, more or less than 10 bit?
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Re: Alta electric dirtbike OEM project

Post by mjc506 »

That looks nice, does it fit the existing mounting points?

The stock sensor already used a shaft mounted magnet, so that should work nicely with the new sensor (and no need to have to work out fixing the magnet, already been done for you) :)

Got a scope? (Or a fast multimeter and a steady hand?) Wire it up and mount it, and watch the outputs for two sine waves as you rotate the shaft.
robinhood
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Re: Alta electric dirtbike OEM project

Post by robinhood »

im so glad to have stumbled upon this, I bought an Alta bulk head from ebay and I got the Alta inverter from EVwest he invited me back if and when i get this running. your thread is vary informational and saves me a lot of guess work since I dont have a functional Alta to compare with. I have reworked smaller drone esc components in my past and some cell phone water damage repair but nothing on the 300v scale. Im sure the challenges Im faced with are not far from drones in respect to micro soldering. If I may follow your build which MCU board would you recommend for open inverter zombiefying my alta inverter. thanks again for you work. cheers from US
A disciple to Necessity the mother builder.
marengo
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Re: Alta electric dirtbike OEM project

Post by marengo »

Hi do you know what inverter you actually have? They evolved along the way and are slightly different. MX inverters wouldnt interchange with MXR inverters, for example...
robinhood
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Re: Alta electric dirtbike OEM project

Post by robinhood »

Damn I have not a clue which Inverter model I got how can I tell it has the throttle digitizer on a separate board
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marengo
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Re: Alta electric dirtbike OEM project

Post by marengo »

I bet the seller would know what bike it is for.

But you brought up a good point. The throttle data is on its own CAN with the inverter. I'm not sure if it is CAN1 or CAN2 yet. Somehow the throttle position is "digitized" for the benefit of the OEM inverter. My throttle is a regular Domino (potentiometer) throttle with an inline circuitboard molded into the harness. On yours, this circuit board lives inside the inverter case and was an upgrade apparently.
robinhood
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Re: Alta electric dirtbike OEM project

Post by robinhood »

i have a domino throttle actuator other then the hall effect there is no circuit board molded to the wires however it is from a zero sevcon build and not the alta motors stock.
Also i think this inverter came off the assemble line probably waiting to go on the latest production bike at the time of the Alta demise. at least i hope not from a defect box in the refurbish department. it doesnt smell of plasma nor do i see any sign of scorching.
so i ordered an open inverter mini logic board and i have to say impressive work hats off to the DEVs. im sure the wire mapping i have in stored for me is going to be a painful one time experience. at least for alta inverters. perhaps a nissan leaf in a future build. since my neighbor whom is suffering dementia his family gave me his weathered vw sand dune buggy... plan to give it a ''new leaf"orlife ... lol
back to where to start with my alta motor/inverter and open inverter mini...
wiki the mini logic schematic?
alta schematic unattainable probably due to polaris buy out.
i have an amscope stereo microscope and a bit of time.
A disciple to Necessity the mother builder.
robinhood
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Re: Alta electric dirtbike OEM project

Post by robinhood »

Im curious to know if you have figured out how to run open inverter with oem alta board.
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