This is entirely due to the geometry of the motor. A high quality of service represents a competitive advantage for civil engineers that can gain client fidelity and more, but this is becoming harder to accomplish with modern design expectations. So I have made a math model of the motor that computes torque, it works very well but I just can’t explain why R is not constant! The main difference is that different PMSM’s can be designed with different rotor-stator flux linkages to meet different design goals. Duane Hanselman Dr Hanselman is an internationaly acknowledge expert in motor design. I’m not even a fan of “trapezoidally wound” and “sinusoidally wound” because it’s more of a continuum than separate buckets that they are placed in.
Shane, Thank you for sharing the information. There is clearly an advantage to having constant torque in things like large machines, electric vehicles, etc. It explains it better than I can in words. Posted by Shane Colton at 2: The coils serve merely to generate the flux while the iron conducts and shapes it. It’s a good question and fundamental to understanding torque generation in this type of motor! The simple DC motor model.
Shane Colton October 18, at 7: Could the use of the “high timing” mode lead to something somewhat similar with RC motors?
Thanks for the answer! I’m back 4 years later with another question! Shane Colton December 6, at 6: Guillaume December 7, at 5: You two guys have cleared a lot of things for me yet, I still want to read James’s report Thanks as well for the link to James Mevey’s thesis.
That is more “lossy” than commutation through the FET itself because of the diode drop, so maybe when that is averaged it it looks like a resistance that increases with speed.
Shane Colton: Everything You Ever Wanted to Know About Brushless Motors
The term “DC brushless motor” is a marketing term. Thanks for your patience. Guillaume December 8, at 4: But it simply does not work!
As for whether the motor tries to maintain its back EMF: I’ve been doing a lot of reading lately about brushless motors and their control. This is also always thseis. Shane Colton August 7, at Resources Today, the market is saturated with groundbreaking design projects and competition from around the world. Sorry, I hope you don’t mind spending a little of your time answering my question, this is very confusing for me.
You said you are measuring input voltage and current – does that mean input to the motor output from the ESC or input to the ESC output from the battery or power supply? In a brushed motor, the back EMF constant relating voltage produced at the open motor terminals to the speed of the motor and the torque constant relating torque produced to the current passing through the motor are the same number.
No motion is required for torque generation. The explanations are clear, but not simplified.
FOC operates in the rotor frame of reference, so it requires a method for estimating the rotor position. In my mind, your understanding is correct – the “trapezoidal” vs. Or, if you’re at full-throttle on the ESC it wouldn’t matter since they’d be the same.
Now here are two cases where the relative phase of voltage can be controlled advanced. Did I just create a new word?
Motion generates back EMF. The intent was to sell these motors as replacements for DC brush motors in servo applications One way to answer would be to say that the torque is only proportional fhesis current if the phase of the current is fixed with respect to the phase of the rotor flux i.
So the switching isn’t periodic A DC brushless motor is an AC motor. Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
Fixed voltage, advance the timing, the motor gets faster. Anyway, I’m not telling you to read the whole thing yes I am but I did.