The basic idea is to provide a constant current source for the motor coils when you want the motor to turn on. Your motor current rating per phase should not be exceeded.
Your controller is just a switch which places the power supply voltage across the motor coils. Hence, you have no control of the coil current. To control the coil current you either fix the power supply voltage until the desired current rating is reached, or you use a fixed resistor to limit the current until the designed phase current is reached.
But if different motors have different current ratings you would then need different power supply voltage settings to keep the coil current controlled, or different resistors for a given power supply voltage. Your calculations should work to get the right resistance. You could also use an ammeter and an adjustable power resistor until you reach the desired current.
The next issue you will find is that as the RPM goes up the fast switching of the coils causes too little time for the current to reach the full value and your torque decreases and possibly stall your motor. Raising the power supply voltage will help higher RPM but also causes too much current at lower RPM. That is why I don't recommend your controllers. You should get a controller that can, say use 36VDC, and still keep the coil current constant for all RPM (until 36VDC becomes too low for the much higher RPM).