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I hope this is not too far off topic. I'm trying to establish some VFD requirements
The truck is a 91 Chevy S-10. It seems to me that the truck will take about 30 HP at 2700 rpm to keep me at 65 mph. See reference one below for where I got that number
I have tested (sort of) my 30 HP 575VAC three phase 1750 rpm motor (all 300 pounds of it) with a smaller 208V surplus industrial VFD. The motor is rated just under 30 amps and I fed is all 17 amps that the little VFD could produce. The off-the-line torque measures about 60 foot-lb. That's at about 30 VAC and 0.5 Hz, the starting frequency of the VFD. The motor is rated for about 90 foot-lb at 1750 rpm. See reference 2 for where that number came from.
The total drag from the first site includes a 30 mph head wind and a 2% grade on dry pavement. The 1994 S-10 on the site has an automatic, so there is a bit of loss from the auto transmission. I live in the prairies, so 2% is the highest grade this little truck will see.
A bit about motors. An industrial medium efficiency motor is designed to start 'across-the-line'. Full power is applied using a starter and the motor gets very high inrush current (6 to 8 times rated current) until it gets up to running speed. The big iron in these motors is there to absorb this large heat load on start. I'm hoping that I can get 60 HP out of this motor for about 30 sec to get up to highway speed. I plan to mount the motor beneath the bed and couple to the drive shaft. At that point, there is only the 3.43 rear end between the motor and the 205/75 r14 tires that meet the road. If it were a high efficiency motor, it would absorbe 10 times starting current, and the synchronous speed would be closer to 1800 rpm, like maybe 1790.
The numbers I get for over-driving the 30 HP up to 2X current are 180 foot-lb of torque * 3.43 gear box * 12 inches/foot /radius of tire which is 13.5 inches
So around 550 lb of force pushing the truck forward from a stand-still. With an estimated 4500 lb of truck and batteries, this gets me to 65 mph in about 30 or 35 seconds.
If I put a 75 HP VFD at 575 VAC on this motor, it would only be putting out 75 amps rms with a 950 VDC bus.
You guys are talking about hundreds of amps here, right?
Link 1 - evconvert. I used the 1994 S10, a Warp 9 motor, Optima 31T batteries, and a Zila 2K controller. I know it's all DC, but I'm looking for approximates here. 1 string of batteries at 144V, 80% DOD and a 2% incline with a 30 mph head wind. That gets me a 10 mile range. The weight and misc is where the weight comes from. The drag calculations is where the acceleration comes from. The tire sizes don't quite match and I think I have a different differential on my 91, so I need 2700 rpm at 65 mph not 2100 as the site shows. I'm using most of the rest of the information as is for a starting point. Prepend 3w's
evconvert.com/tools/evcalc/.
Link 2 - rotating horsepower. I entered 90 foot-lb at 1750 rpm and got 30 HP or close enough. Prepend 3w's, add htm
calculatoredge.com/new/horsepower
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