Hello mjsas

Thanks for your answer. I know that the problem is not easy to be solved, maybe that’s the reason it pushes me to work on it…

The KV problem is already solved. The figures, graphics and tables are the calculation for one example motor.

The first figure is an animated gif with the test motor.

The motor definition is:

• 5 turns of one wire. Wire radius 0.75mm.

• Housing: Al6061

• Material for the stator: 1020 steel. Depth: 19.7mm. laminated thickness: 0.35mm

• Magnet: NdFeB 52 MGOe

• Shaft: Std steel

The stator shape is optimized to avoid material saturation.

The graphics below are the flux linkage per phase, Back-EMF, voltage per radian and cogging torque

For this particular design the KV value I got is 4958,28 rpm/V

Coming back to the problem I am trying to solve. My next step is suppose a speed control in the easiest way, something like what is shown in the scheme below:

Let’s suppose that we have electronics capable to switch the gates S1 to S6, every 60 motor electrical degrees in the right order. For the time being, also as initial simplification, we don’t consider the power control, ie, no PWM. Electrical scheme like:

We can also consider that the timing is 0. With these assumptions, how can I solve the problem equations?

The final goal solving this problem is to have the capability to predict motor torque function of timing. As you know the torque curve of a motor is something like the one shown in the graphic below.

If we are capable to develop this model we will be able to predict torque capability vs timing, and it will be something like the following graphic

With the knowledge of the effects of timing we will know the current required, then motor temperature, battery autonomy, etc. Finally we can also increase the efficiency of the motor by setting the adequate timing curve function of rpms in the ESC.

Xavier