Hillhater said:
TTc’r...respect your personal experience, but how are you actually measuring your “peak torque” ?
There is extensive data posted from NASA tests on the Prestolite MTC4001, and whilst they do not run it down to a full stall (?), the data clearly show the controller input current increasing with torque loading as the rpm reduces (from 4000 down to 250 rpm) . Maximum torque is at the lowest rpm , as is the maximum current draw and power input.
https://www.semanticscholar.org/paper/Straight-and-chopped-dc-performance-data-for-a-and-Edie/e723c61bf0d4925e9e53525d2dceff67ce3a82b5/figure/4
That chart you list pairs the motor with an outdated and highly inefficient controller from the 1970s that does not pulse width modulate the signal as well as today's tech. The combination's extremely low efficiency at lower rpms is very telling, granted, this is not a highly efficient motor to start with. If I had the money, I'd upgrade to a synchronous reluctance motor/controller setup.
My controller sets my motor voltage limit to 165V, twice as much as what is shown in the chart you list. I have not dynoed the car, so I don't have a real world measurement of peak torque, but with a series DC machine, torque varies as a square of the armature current, and the maximum torque possible is inversely proportional to rpm(the higher the voltage applied, the higher of an rpm that the motor can make a given amount of torque), and my controller is set up to allow peak motor current all the way until the max power output settings on the controller are reached(based upon max battery current, but the motor curve itself is also influenced by max motor current and max motor voltage via controller. Once motor voltage rises to the limit is when motor current and thus torque has to drop off). I only have my gauges set up to measure speed(mph), motor rpm, battery current draw, battery voltage, and motor temperature, so I have no way to compare motor current(and thus torque) and battery current together. I have the max current output from the controller to the motor set at 700A, and it is reached as soon as the ramp function(set at 1000A/s) allows once the accelerator is floored, but I can definitely feel the acceleration drop off a bit after about 4,000 rpm or so. When I get all the bugs for this car worked out and actually finish it, I plan to increase max current draw from my batteries to 600A to get a bit more peak power and extend the max rpm for the peak torque part of my motor's performance curve
I did make a spreadsheet to simulate my setup. My real world experience appears to match it, even if I may not yet have had a chance to apply the scientific method to get some hard numbers. I don't know when that will be though, as I've repeatedly spent my savings keeping my mom from losing her house, and she's disabled and unable to walk or work. Although I have close to 10 years of experience as an electrical engineer, I'm currently stuck washing dishes at a restaurant for minimum wage at the moment, so getting this car ready could easily take years... Finishing my electric velomobile will cost a lot less time and money and I currently use it on a daily basis, so that has been my focus as of late.