Recent content by mechamania

Hi jim, The compensation with the ω.Ld.Id, ω.Lq.Iq and ω.λm terms we talked about have nothing to do with the basics of FOC. They are improvements. Miles: please correct me if I'm wrong. This compensation may be confusing when studying FOC.

Thanks for all the time spend in this thread. I learned a lot and will learn more reading it over a few times more. Thanks all.

Ok Thanks I see now you explain it in the last sentence. Sorry I overlooked it. Is it correct that these third terms are usually much smaller then the back-emk (fourth term of Vq) term? And did I understand correctly that these third terms are still important because they change faster...

Thank you very much for trying! It I learn a lot from these kind of explanations. So all three components (ω.Ld.Id, ω.Lq.Iq and ω.λm) are neede for a correct back-emk compensation. I was thinking the ω.λm was the only one needed for back-emk compensation and the other two are for another...

Wow! I wish I could 'think out loud' this way. I'm not really a math person. Although I understand some. I have to study your 'thinking' more closely. I always want to understand what I'm doing in a practical way. When I tweak parameters or change algorithms I want to be able to predict the...

So what would the result of this compensation be? Or better, what is the problem when I do not have this compensation?

So do I understand correctly that the two terms ωLdId and ωLqIq together result in a angle adjustment/change?

Thank you both very much for explaining all this stuff. I think I start to understand now why you can control the current by applying a voltage calculated by the PID that has current values as input. I found an example where a measured speed is used to compensating for the back-emf by...

@jim Thanks for you answer. I'm afraid the PID want work stable enough when cascading two integrators. So what you are saying is that you can control the motor current by controller the voltage in a more or less proportional way. And the integrattion will not disturb the PID controller?

I found a better (much simpler) controller diagram to explain my question. See attachment again. Here the torque (is current) is controlled by a PI controller. The output is a voltage. The PMW makes sure this voltage is applied to the motor. But the motor current is feedback to the PI...

I found a better picture of a FOC controller. Here you see the inner PID loops, controlling current. And the outer PID loop controlling speed. The rotor position is needed for the transformations. The output of the inner PIDs control the PMW, thus controls the voltage on the motor...

@DragonPetter: Thanks for your answer. I agree for a pure resistor the voltage control is equal to current control. But we have a lot of inductance here. I also agree that I could calculate the needed voltage given the motor speed and motor parameters (like back emf and inductance). But...

@DragonPeter I have no models yet. I just want to understand how it works first. @jim hardy Thanks. Found it. Looks very interesting. Will take some time to study it ;-)

I agree that the speed can be controlled by the frequency of the sinusoidal waveforms. But in that implementation the motor position was used to generate the correct sinusoidal phases. And the PID output controlled the amplitude of the sinusoidal waveforms. So the speed is indeed controlled by...

I understand that I can not control both torque and speed at the same time. The point is that I do not understand how the torque regulation is done using the described PID controller with PMW. The PID has current value inputs but controls the voltage of the motor. And the voltage of the...