02-25-2019, 06:33 AM
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#3391 (permalink)
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EcoModding Lurker
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Industrial 3 Phase motor
Hi Guy's
Is a surplus industrial 3 phase motor suitable for an EV, if so what sort of rating would be considered suitable for an average size compact car, not a dragster just a potterer?
I have seen plenty advertised on ebay with ratings 3hp, 5hp and 10hp and does the number of poles feature in the equation?
regards John
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02-25-2019, 11:59 AM
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#3392 (permalink)
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Master EcoModder
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Quote:
Originally Posted by hehehole
Extended Back EMF model for permanent magnet synchronous machine with different inductances in d- and q-axis:
publik.tuwien.ac.at/files/PubDat_176266.pdf (couldn't post a link as I'm new, you can also look for the title in google)
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The link
https://publik.tuwien.ac.at/files/PubDat_176266.pdf
Interesting description. It would be *GREAT* to get Field Oriented control without an encoder.
Several industrial vendors do their own version of this. I don't know of anyone that has open-sourced it so far.
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02-25-2019, 12:18 PM
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#3393 (permalink)
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Quote:
Originally Posted by johnsiddle
Hi Guy's
Is a surplus industrial 3 phase motor suitable for an EV, if so what sort of rating would be considered suitable for an average size compact car, not a dragster just a potterer?
I have seen plenty advertised on ebay with ratings 3hp, 5hp and 10hp and does the number of poles feature in the equation?
regards John
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The simple answer is No. The 3 phase motors from golf carts and fork trucks are better, since they are already set up for lower voltage. But they are not often bigger than 3 HP.
A surplus motor is good for a utility vehicle. But it is likely too heavy and produces too little torque for a free-way capable car.
The industrial electric motors are designed to run 24 hours per day, for years. So they have more copper, more steel, etc in them to absorb the heat and radiate it to the local area. And most of them are air-cooled. The motors designed for use in cars are all moving to liquid cooling.
Electric vehicles are normally used for an hour or 2 before they are parked for a few hours. So you can push into the design factors .. and maybe run a 5 HP motor at 10 HP or 12 HP for that hour or 2. And push harder, to maybe 20 HP for acceleration.
One of the issues with the industrial motors is the voltage. To drive them you need quite a high voltage pack. 220V AC needs about 350V for the pack. That's OK if you are recycling a leaf pack or a bolt pack. Not so great if you have larger cells, like LiFePO4 prismatic cells.
To drive a 220V motor at 4 times the amps that it is rated for, you need more voltage. About 4 times the voltage at rated speed. Lots of these motors are 1800 rpm. That's a bit low to put into a transmission and have 60 mph out the other side. So you may also need to drive the motor at more than 60 Hz. The impedance of the motor, the inductance part, is related to frequency. So the higher the speed you want to go, the higher the voltage you need.
Alternately, you can change the wiring of the coils in the motor to drop the required voltage, but that requires a bit of luck with how the motor is wound, and some effort in tearing the motor apart, searching for and finding the coil connections, cutting the coil connections apart, soldering the coils together a different way, and putting it all back together again so that it works. There have been people that got it done, but I have not read of many.
I have access to surplus motors from work. I looked at a few larger motors as the electricians pulled them apart to replace bearings, or whatever else they were doing. The connections between coils on modern motors are not obvious to the untrained (mine) eye.
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Last edited by thingstodo; 02-27-2019 at 02:35 PM..
Reason: fix typos
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02-26-2019, 05:54 PM
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#3394 (permalink)
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Controller Command help.
Hi,
I'm new to the forum, and have been reading through the messages looking for help with the AC controller commands. Awhile back MPaulHomes mentioned adding "Help" to the command structure. IE: "help motor-type" to get additional information. I tried this on my newly purchased controller only to get an "Invalid Command".
Where can I find a list of the commands with basic descriptions of what each means? For instance what is Motor-Type 1 vs 2, 3 and 4?
My hope here is to build a controller to replace the Curtis 1239 144V in my EV conversion. The goal is to get more power out of the HPEVS AC51 motor and maybe, must maybe.... be able to switch over to the Netgain Hyper9.
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02-26-2019, 06:16 PM
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#3395 (permalink)
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PaulH
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02-26-2019, 06:20 PM
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#3396 (permalink)
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Current sensor question
MPaulHomes, The controller config states the range for "current-sensor-amps-per-volt" to be 0-480. I purchased the 600A current sensors (bigger is better?) so can I use 960 for this value? The config accepts the setting, but I want to be sure the imbedded software will also be happy with it.
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03-04-2019, 01:39 AM
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#3397 (permalink)
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Anyone have a recommendation of which encoder would be good to use for the board to add on if I dont already have one? Thanks
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03-04-2019, 05:42 PM
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#3398 (permalink)
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Master EcoModder
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Quote:
Originally Posted by esali1987
Anyone have a recommendation of which encoder would be good to use for the board to add on if I dont already have one? Thanks
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I don't have a recommendation for you. It can get pricey. A through-shaft encoder with 150 PPR or more will start at $500 new.
60 pulses per revolution is enough for good control. It boils down to where you have enough space to put it, what product you can find that will fit, and how you can mount the unit in that space.
There are through-shaft encoders, where the motor shaft sticks through the encoder disc and the rest of the encoder is sort of supported by that shaft.
There are magnets that you can super-glue to the end of an exposed shaft and a small PC board with a chip mounted on it does the magnet sensing and gives you pulses.
And there are ... many ways .. of putting a toothed gear of some sort onto the motor shaft, or monitoring a driven shaft inside the gearbox, or even driving a pulley or gear specifically for the encoder .... all of them give you pulses that work OK for control but don't show you which direction the motor is going. 12-24V DC Inductive switches are used in this last case. Depending on your RPM and how many pulses per revolution you want, they can start at $50 ... if you can fit them where they need to go.
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03-05-2019, 07:05 AM
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#3399 (permalink)
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EcoModding Lurker
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Encoder
I also have a Siemens 1FV motor with this encoder attached with T, S, R, (+), and (-). This seems like outputs would be sinusoidal for the three phases. This probably would not work right?
Thanks
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03-05-2019, 12:36 PM
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#3400 (permalink)
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Master EcoModder
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Quote:
Originally Posted by esali1987
I also have a Siemens 1FV motor with this encoder attached with T, S, R, (+), and (-). This seems like outputs would be sinusoidal for the three phases. This probably would not work right?
Thanks
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I think sinusoidal is for a resolver, not an encoder. And I think you get sine, cos as signals, not one per phase? Not sure. Sorry. This looks fairly close to your diagram but not exact.
https://www.google.com/search?q=siem...a3QwdgM:&vet=1
What other feedback systems are out there?
My encoder on my siemens has A, Abar, B, Bbar, Z, Zbar, + and -. It's a 7 or 8 pin round connector that is hard to source. It sort of looks like the microphone connectors from the 60's and 70's. The encoder runs on 24VDC so I put the output signals through a voltage divider resistor network, and took the 5V-ish signals to Paul's control board. It worked well, even with unsheolded cat5 cable, run across the power cables, and jury-rigged to control board.
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