True FOC: definition and examples

Electric Motors and Controllers
bww129   100 mW

100 mW
Posts: 35
Joined: Apr 14 2020 7:44am
Location: Lancaster PA, USA

Re: True FOC: definition and examples

Post by bww129 » Apr 29 2020 9:39am

Just to throw another definition out there, on page 38 of this ST presentation it states:
"The objective of the [FOC] algorithm is to control the vector components of the stator magnetic field (i.e. the phase currents) in order to obtain the target intensity and phase relation with the rotor magnetic field."

https://www.st.com/content/ccc/resource ... s_pres.pdf

There is also plenty of other good information/diagrams in the presentation.
Last edited by bww129 on Jun 04 2020 1:51pm, edited 1 time in total.

john61ct   100 GW

100 GW
Posts: 6292
Joined: Dec 18 2018 2:06pm

Re: True FOC: definition and examples

Post by john61ct » May 08 2020 2:25pm

Reference from @Bullfrog, not sure if a dupe

https://pdfs.semanticscholar.org/40ac/0 ... 1c74f6.pdf

john61ct   100 GW

100 GW
Posts: 6292
Joined: Dec 18 2018 2:06pm

Re: True FOC: definition and examples

Post by john61ct » May 12 2020 9:32am

Factoid from another relevant thread on IPM specifically, using Lebowsky as an example.
viewtopic.php?f=30&t=105572&start=25#p1554542
amberwolf wrote:Phase current sensors have nothing to do with motor position sensors.
Aren't the latter what is referred to as "encoders"? Are either also referred to as "resolvers"?

I inferred from the above that FOC calculations could be (usually are at least in the ebike world?) based on instantaneous tracking of the individual phase current levels.

Also, any clarification as to how "true FOC" can work in a sensorless setup would be greatly appreciated.

User avatar
Lebowski   1 GW

1 GW
Posts: 3389
Joined: Jun 28 2011 1:38am
Location: beautiful Zurich, Switzerland

Re: True FOC: definition and examples

Post by Lebowski » May 12 2020 10:00am

john61ct wrote:
May 12 2020 9:32am
Also, any clarification as to how "true FOC" can work in a sensorless setup would be greatly appreciated.
You can read the explanation of my stuff here :
viewtopic.php?f=30&t=104895#p1533225

john61ct   100 GW

100 GW
Posts: 6292
Joined: Dec 18 2018 2:06pm

Re: True FOC: definition and examples

Post by john61ct » Jun 03 2020 5:29pm


bww129   100 mW

100 mW
Posts: 35
Joined: Apr 14 2020 7:44am
Location: Lancaster PA, USA

Re: True FOC: definition and examples

Post by bww129 » Jun 06 2020 1:36pm

Vector control for dummies is a very good read with some excellent animations: https://www.switchcraft.org/learning/20 ... or-dummies

john61ct   100 GW

100 GW
Posts: 6292
Joined: Dec 18 2018 2:06pm

Re: True FOC: definition and examples

Post by john61ct » Jun 06 2020 1:43pm

bww129 wrote:Vector control for dummies is a very good read with some excellent animations: https://www.switchcraft.org/learning/20 ... or-dummies
Wow, thanks!

ProgramThyself   10 mW

10 mW
Posts: 28
Joined: May 20 2019 12:13pm
Location: Cambridge, MA
Contact:

Re: True FOC: definition and examples

Post by ProgramThyself » Jun 07 2020 9:13pm

Prof. Kirtley gives a definition in his MIT course notes (Chapter 7, Section 3.3)
https://ocw.mit.edu/courses/electrical- ... rse-notes/
For high performance drives, we will generally assume that the power supply, generally an inverter, can supply currents in the correct spatial relationship to the rotor to produce torque in some reasonably effective fashion. We will show in this section how to determine, given a required torque (or if the torque is limited by either voltage or current which we will discuss anon), what the values of Id and Iq must be. Then the power supply, given some means of determining where the rotor is (the instantaneous value of θ), will use the inverse Park’s transformation to determine the instantaneous valued required for phase currents. This is the essence of what is known as “field oriented control”, or putting stator currents in the correct location in space to produce the required torque.

Post Reply