Comments on Back-EMF in bipolar stepper motor seems inconsistent with torque graph
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Back-EMF in bipolar stepper motor seems inconsistent with torque graph
In the AM2224-1000 datasheet for the '1000' model the following parameters are given:
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Nominal voltage per phase: 1.4V
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Back-EMF amplitude: 3.8V/k step/s
There is also torque/speed graph present for different voltages:
However, it seems that the graph does not correspond to the data from the table. If I want to use the stepper at 4000 steps/s, the back-EMF generated would presumably be:
$V_{\text{back-EMF}} = 3.8 \times 4 = 15.2V$
Whereas
$V_{\text{8x-nominal}} = 1.4 \times 8 = 11.2V$
The graph shows at this point that motor is still generating torque. If the back-EMF really is this high, would it not be the case that the motor never reaches 4k steps/s, because as the back-EMF reached supply voltage, no more current can be pushed into the windings and it would reach max speed and 0 torque condition?
The 4x and 1x nominal graphs also seem to exceed what is possible, which leads me to believe I have misinterpreted the datasheet or that I am missing something fundamental.
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