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Posted to commits@nuttx.apache.org by GitBox <gi...@apache.org> on 2023/01/12 19:53:37 UTC
[GitHub] [nuttx] shizacat opened a new issue, #8098: FOC get Back EMF
shizacat opened a new issue, #8098:
URL: https://github.com/apache/nuttx/issues/8098
Hi!
More the questionstion than the issue
I want to make motor control though FOC with get angle sensorless from BEMF.
For base I took example from 'example/foc'.
How I understood, right approach - get data about BEMF from injected ADC channels?
And now problems:
- The driver FOC havn't have this ability? For this needs to be done to add variable as for 'current' (foc_state_s, stm32_foc_data_s) and methods. That is, you need to update exactly NuttX?
- Set up a board to work in dual mode ADC, to get 4+4 injectd channels
Am I thinking in the right direction?
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[GitHub] [nuttx] zouboan commented on issue #8098: FOC get Back EMF
Posted by GitBox <gi...@apache.org>.
zouboan commented on issue #8098:
URL: https://github.com/apache/nuttx/issues/8098#issuecomment-1381975671
@raiden00pl maybe he want to sense BEMF when three-phase bridge was shut off, then we can sense BEMF and observer angle by fluxlinkage observer in case of motor power off.
This method is generally used in case when the motor was driven by external torque when motor power off, if we can tracking electric angle under this working condition, it will be easier to do a sensorless startup at the next time.
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[GitHub] [nuttx] raiden00pl commented on issue #8098: FOC get Back EMF
Posted by GitBox <gi...@apache.org>.
raiden00pl commented on issue #8098:
URL: https://github.com/apache/nuttx/issues/8098#issuecomment-1381925784
I don't think you can directly sense BEMF in FOC.
BEMF sensing requires only two phases of the tree phases motor conducting at any point of time,
but in FOC you have three phases conducting.
Detecting BEMF is possible only for six-step commutation (also known as trapezoidal commutation) which is not currently supported with NuttX.
BEMF angle estimation methods for FOC use BEMF estimation techniques, where you can use phases
currents and motor model to estimate BEMF and further phase angle.
One of this method is implemented here (SMO observer):
https://github.com/apache/nuttx-apps/blob/master/industry/foc/float/foc_ang_osmo.c
https://github.com/apache/nuttx/blob/1f95cfdde8338f99116f64d59db43ca146d791ae/libs/libdsp/lib_observer.c
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[GitHub] [nuttx] raiden00pl commented on issue #8098: FOC get Back EMF
Posted by GitBox <gi...@apache.org>.
raiden00pl commented on issue #8098:
URL: https://github.com/apache/nuttx/issues/8098#issuecomment-1383151205
> raiden00pl ... FOC driver pick up physical state of motor as current or else, and BEMF not very strong different the current. I think, it right place to take the current and BEMF in one place.
That's not entirely true. In fact, the FOC driver knows nothing about the powered motor. What the driver know is the state of 3-phase bridge that powers the motor (which is PWM duty and current on shunts).
That's why the driver is completely separated from parameters like the motor phase angle, motor temperature or VBUS.
This separation is very important for modular architecture, that is why I was slightly skeptical about measuring BEMF in the FOC driver. But after some thinking, I'm OK with this as long as everything will be hidden behind the Kconfig option.
I'll look at this topic more in the week, especially how to implement BEMF sensing for STM32.
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[GitHub] [nuttx] raiden00pl commented on issue #8098: FOC get Back EMF
Posted by GitBox <gi...@apache.org>.
raiden00pl commented on issue #8098:
URL: https://github.com/apache/nuttx/issues/8098#issuecomment-1382056379
@zouboan if that is the case, then I don't think the FOC driver is the right place to put the BEMF sense logic. This is more related to angle sensors than the FOC driver (in NuttX FOC architecture terms).
I'm strongly against mixing the FOC driver functionality (which is simply generate PWM and sample currents) with an app specific logic (here - angle detection).
Why not create separate driver for BEMF sensing with its own ADC and triggering ? Is there any coupling between the FOC driver and BEMF sensing that can cause problems here?
Such a driver may in the future be the base for implementing six-step controller.
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[GitHub] [nuttx] shizacat commented on issue #8098: FOC get Back EMF
Posted by GitBox <gi...@apache.org>.
shizacat commented on issue #8098:
URL: https://github.com/apache/nuttx/issues/8098#issuecomment-1382677571
Ohh, how many ))
Thank you, for your time!
@acassis, Yes/no. I rewrite this example for me. I found it complicated and not very clear. But all the changes only control (FMS), main idea of the code unchanged.
@zouboan Yep, I want change it ... try.
@zouboan Thank you for tips.
@raiden00pl Why not, Back EMF it simply voltage on ADC, which the FOC driver picks up by analogy with the current. Thank you for tips.
@raiden00pl Yes, It will be great. This is what I want.
raiden00pl ... FOC driver pick up physical state of motor as current or else, and BEMF not very strong different the current. I think, it right place to take the current and BEMF in one place.
But the calculation of the phase angle itself is already located somewhere from the outside...
Why not create separate driver for BEMF sensing with its own ADC and triggering ? - Timing, Current and voltage (BEMF) must be taken at the same time - this is the state of the motor.
Is there any coupling between the FOC driver and BEMF sensing that can cause problems here? - Yep, timing.
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[GitHub] [nuttx] acassis commented on issue #8098: FOC get Back EMF
Posted by GitBox <gi...@apache.org>.
acassis commented on issue #8098:
URL: https://github.com/apache/nuttx/issues/8098#issuecomment-1380980281
@raiden00pl could you please help here?
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[GitHub] [nuttx] acassis commented on issue #8098: FOC get Back EMF
Posted by GitBox <gi...@apache.org>.
acassis commented on issue #8098:
URL: https://github.com/apache/nuttx/issues/8098#issuecomment-1381766493
@shizacat did you test using the example available on NuttX:
$ make distclean
$ ./tools/configure.sh b-g431b-esc1:foc_b16
$ make
Flash the board
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[GitHub] [nuttx] zouboan commented on issue #8098: FOC get Back EMF
Posted by GitBox <gi...@apache.org>.
zouboan commented on issue #8098:
URL: https://github.com/apache/nuttx/issues/8098#issuecomment-1381920699
@shizacat Yes, you should add voltage define in `struct stm32_foc_data_s` of arch/arm/stm32/stm32_foc.c
and you should implement `stm32_foc_volt_get` follows the design of `stm32_foc_curr_get`
and you should implement `board_foc_voltage_get` In b-g431b-esc1 follows the design of `board_foc_current_get`
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[GitHub] [nuttx] zouboan commented on issue #8098: FOC get Back EMF
Posted by GitBox <gi...@apache.org>.
zouboan commented on issue #8098:
URL: https://github.com/apache/nuttx/issues/8098#issuecomment-1381895151
@shizacat Neither sensored nor sensorless mode of NuttX FOC driver uses BEMF, so the FOC driver does not support the acquisition of motor phase voltage at present
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[GitHub] [nuttx] pkarashchenko closed issue #8098: FOC get Back EMF
Posted by "pkarashchenko (via GitHub)" <gi...@apache.org>.
pkarashchenko closed issue #8098: FOC get Back EMF
URL: https://github.com/apache/nuttx/issues/8098
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[GitHub] [nuttx] shizacat commented on issue #8098: FOC get Back EMF
Posted by "shizacat (via GitHub)" <gi...@apache.org>.
shizacat commented on issue #8098:
URL: https://github.com/apache/nuttx/issues/8098#issuecomment-1399589405
@raiden00pl NIce work!
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[GitHub] [nuttx] raiden00pl commented on issue #8098: FOC get Back EMF
Posted by "raiden00pl (via GitHub)" <gi...@apache.org>.
raiden00pl commented on issue #8098:
URL: https://github.com/apache/nuttx/issues/8098#issuecomment-1398847092
All uper-half logic is in place now but lower-level logic for stm32 is not yet upstream. I have some initial code but not tested on HW yet.
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[GitHub] [nuttx] acassis commented on issue #8098: FOC get Back EMF
Posted by "acassis (via GitHub)" <gi...@apache.org>.
acassis commented on issue #8098:
URL: https://github.com/apache/nuttx/issues/8098#issuecomment-1399529082
Nice work @raiden00pl !!! Kudos!!!
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