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<p>Is there any reason you don't purchase an in-stock BLDC motor
driver such as:</p>
<p><br>
</p>
<p><a class="moz-txt-link-freetext" href="https://www.mouser.com/ProductDetail/Texas-Instruments/DRV10983SQPWPRQ1?qs=%2Fha2pyFadujPwfH%2FXzivpU8AHrIO6U7ALudxKfjNJze3U2dD%2F68jly3tmYweXSYm">https://www.mouser.com/ProductDetail/Texas-Instruments/DRV10983SQPWPRQ1?qs=%2Fha2pyFadujPwfH%2FXzivpU8AHrIO6U7ALudxKfjNJze3U2dD%2F68jly3tmYweXSYm</a></p>
<p><br>
</p>
<p>Mouser shows 66 in stock, and at $4.61 each.</p>
<p><br>
</p>
<p>I'm only showing the one device rated to 2 amps that I filtered
from all the parts currently available and am not endorsing.<br>
</p>
<p><br>
</p>
<p>Hope this helps.</p>
<p><br>
</p>
<p>Rick<br>
</p>
<div class="moz-cite-prefix">On 10/7/2021 2:32 AM, Mike Lisanke via
TriEmbed wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CALt_PJSp2CZ98wf+DK=F7o_8eo0=sOdqyZxNdRzzWvA7EZE2Nw@mail.gmail.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div dir="ltr">Charlie,
<div><br>
</div>
<div>You can commutate the motor phase from a rotary encoder. No
need for Hall effect sensors. Just phase lock to a zero point
and know (measure) the 120 degree phase angles. </div>
<div>I did much open loop motor control at IBM. It wasn't
difficult and we did it with very simple controllers. It does
pay to have a watchdog timer power-off all op amps in-case
your SW debug locks up or runs away. I had our HW tech
eventually create a socketed linear amp. Our HW engineer was
an audiophile and said my SW brought tears to his eyes (not in
a good way). </div>
<div><br>
</div>
<div>BTW, linear motes and steppers with microstepping can all
be encoder-commutated and driven off 1 sinusoid table at 3
offsets. </div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Wed, Oct 6, 2021 at 9:44 PM
Charles West via TriEmbed <<a
href="mailto:triembed@triembed.org" moz-do-not-send="true">triembed@triembed.org</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div dir="ltr">
<div>@Pete:</div>
<div>When you were working on it, did the motor you were
using have hall effect sensors in it? That's about all
that makes me willing to try this. In the worse case, I
should be able to fall back to trapezoidal control based
off of the hall effect sensors without any sort of fancy
estimation. I hope I can do better than that though.</div>
<div><br>
</div>
<div>@Carl&Rodney:</div>
<div>I've been actively looking through motor control gate
drivers trying to find something that is simple enough I
can work with it, available and capable enough. So far,
the best I've found is the STDRIVE101 (<a
href="https://www.mouser.com/ProductDetail/STMicroelectronics/STDRIVE101?qs=xZ%2FP%252Ba9zWqYdY88AYx%252Blxg%3D%3D"
target="_blank" moz-do-not-send="true">https://www.mouser.com/ProductDetail/STMicroelectronics/STDRIVE101?qs=xZ%2FP%252Ba9zWqYdY88AYx%252Blxg%3D%3D</a>).
I'm bumbling my way through designing a test circuit for
it now, but I would be the first to admit that I am rather
terrible at analog electronics.</div>
<div><br>
</div>
<div>Thanks,</div>
<div>Charlie<br>
</div>
<br>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Tue, Oct 5, 2021 at
3:35 PM Carl Nobile via TriEmbed <<a
href="mailto:triembed@triembed.org" target="_blank"
moz-do-not-send="true">triembed@triembed.org</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div dir="ltr">So my bad, I read Charlie's email and
missed the brushless part. I must have brushes in my
mind.
<div><br>
</div>
<div>So brushless DC motors are actually 3 phase
synchronous AC motors, So three different PWM
modulators are needed for each motor. Each PWM is 120
degrees out of sync with the others. and there can be
absolutely no overlay on the others. There are special
MCUs that are made for these motors. See the link
below, it's for an older 8 bit MCU, but will give you
an idea as to what needs to be done.</div>
<div><a
href="http://ww1.microchip.com/downloads/en/devicedoc/atmel-7710-8-bit-microcontroller-at90pwm216-316_datasheet-summary.pdf"
target="_blank" moz-do-not-send="true">http://ww1.microchip.com/downloads/en/devicedoc/atmel-7710-8-bit-microcontroller-at90pwm216-316_datasheet-summary.pdf</a><br>
</div>
<div><br>
</div>
<div>~Carl</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Tue, Oct 5, 2021 at
12:55 PM Pete Soper via TriEmbed <<a
href="mailto:triembed@triembed.org" target="_blank"
moz-do-not-send="true">triembed@triembed.org</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px
0px 0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div>
<p>I once got the idea I could control a brushless
motor by being "clever" controlling set of
drivers. I was mistaken. Without some means of
sensing the behavior of the motor, whether it be
back EMF or some other feedback it's about 99% of
hopeless. Which is to say I was too stubborn to
give up and managed to see the motor (from a
server disk drive) spin, but if I squinted at it
there was misbehavior. A truly silly waste of
time.</p>
<p>-Pete<br>
</p>
<div>On 10/5/21 12:45, R Radford via TriEmbed wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div dir="ltr">Carl, Charles is looking for a
brushless controller, not just a DC motor
driver. Brushless motors are closer to a
stepper motor than a regular DC motor, but the
'steps' are controlled by sensing hall effect
sensors to know when to step to keep the motor
running smoothly.
<div><br>
</div>
<div>They are great as they have less
mechanical issues over time (no brushes to
replace) and also produce less electrical
noise. </div>
<div><br>
</div>
<div>The circuit you show is a nice DC to PWM
circuit that is similar to one I did many
years ago, but now most (all?)
microprocessors have built in hardware
assist PWM so that part is already handled.
The first time I used a similar circuit was
controlling a robot from a 286 PC based
robot where I used the parallel port to
drive an R2R D/A circuit comparing against a
triangle wave similar to your circuit. It
worked great at the time, but now would not
be needed. I still have that old hardware
somewhere - perhaps I should pull it out and
upgrade it.</div>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Tue, Oct 5,
2021 at 12:02 PM Carl Nobile via TriEmbed <<a
href="mailto:triembed@triembed.org"
target="_blank" moz-do-not-send="true">triembed@triembed.org</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div dir="ltr">Charly,
<div><br>
</div>
<div>There are a few solutions to the
controller problem. I designed an analog
PWM circuit using op-amps and
comparators that works great. You would
also need an H-Bridge you would then need
just one MCU board to control the PWM
circuits then then control the H-Bridge
circuits.</div>
<div>My design is at: <a
href="https://github.com/cnobile2012/VoltageControlledPWM"
target="_blank" moz-do-not-send="true">https://github.com/cnobile2012/VoltageControlledPWM</a></div>
<div>My motors are fairly low current and
voltage so the H-Bridges I'm using won't
work for you, however MPJA.com has one in
the link below, that will handle higher
currents.</div>
<div><a
href="https://www.mpja.com/Dual-H-Bridge-DC-Motor-Driver/productinfo/35567+MP/"
target="_blank" moz-do-not-send="true">https://www.mpja.com/Dual-H-Bridge-DC-Motor-Driver/productinfo/35567+MP/</a><br>
</div>
<div>It will handle two motors and is only
$22.95 ea. They give full docs on their
site.</div>
<div>My PWM board shou interface with it
fine.</div>
<div><br>
</div>
<div>~Carl</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Sun,
Oct 3, 2021 at 11:16 PM Charles West via
TriEmbed <<a
href="mailto:triembed@triembed.org"
target="_blank" moz-do-not-send="true">triembed@triembed.org</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div dir="ltr">
<div>Hello all!</div>
<div><br>
</div>
<div>For the past 5 years or so, I've
been working on a open source low cost
sidewalk delivery robot. The current
draft (prototype picture: <a
href="http://goodbot.ai/lib/exe/fetch.php?media=mk3draft1.jpg"
target="_blank"
moz-do-not-send="true">http://goodbot.ai/lib/exe/fetch.php?media=mk3draft1.jpg</a>)
has 4 hoverboard style motors in a
skid steer arrangement. Each robot
will need 4 motor controllers, which
is one the big cost drivers right now
(even prior to the covid shortage, the
controller cost more than the motors).<br>
</div>
<div><br>
</div>
<div>My last stab at designing a
brushless motor controller failed
spectacularly and the covid parts
shortage has also made the central
parts of that design completely
unavailable. In addition, the bulk
price for the motor controllers I've
been using jumped from $56 per to
~$100 per.</div>
<div><br>
</div>
<div>Given that, I thought it might be
time to get back to the drawing
board. However, I am not an expert at
this sort of thing, so I thought it
might be good to post what I am
thinking and see if I am completely
off the reservation.</div>
<div><br>
</div>
<div>I'm currently using off-brand VESC
motor controllers (schematic for
normal ones here: <a
href="https://vesc-project.com/sites/default/files/Benjamin%20Posts/VESC_6.pdf"
target="_blank"
moz-do-not-send="true">https://vesc-project.com/sites/default/files/Benjamin%20Posts/VESC_6.pdf</a>).
They are great but do way more than I
need. They can handle sensored and
sensorless motors and be reconfigured
with MANY different options using a
desktop application. I don't need to
make something that is easy to make
work for lots of different motors and
I don't need to support sensorless
operation. I just need to make
something that works for my motors.</div>
<div><br>
</div>
<div>The approach that the VESC takes is
a central microcontroller which talks
with a (not currently available)
DRV8301 chip. This chip in turn
senses voltage/current across each
motor coil and drives 6 N-channel
mosfets to control the motor (3 high
side, 3 low side). It does FOC
control, which I believe is state of
the art in terms of smooth motor
control. It also integrates the 3
halls sensors that sensored motors
have if they are available.</div>
<div><br>
</div>
<div>I'm having trouble finding any of
these 6 mosfet motor controller
optimized gate drivers, so I am
thinking that I will just get some
high side/low side mosfet drivers
(like maybe these: <a
href="https://www.mouser.com/ProductDetail/STMicroelectronics/SRK2000A?qs=WHlX%252B%252B9%2FRwCG%2FkukabfLqA%3D%3D"
target="_blank"
moz-do-not-send="true">https://www.mouser.com/ProductDetail/STMicroelectronics/SRK2000A?qs=WHlX%252B%252B9%2FRwCG%2FkukabfLqA%3D%3D</a>)
and some nice mosfets. Particularly
without dedicated chips being
available, I'm not going to try to do
current or voltage sensing. I am
thinking that I would just PWM the 3
half bridges and try to do sinusoidal
motor control using a STM32
microcontroller to drive it and the
hall sensors in the motors to estimate
position relative to the coils.</div>
<div><br>
</div>
<div>If I may ask, does this sound
reasonable or am I totally off base?</div>
<div><br>
</div>
<div>Thanks,</div>
<div>Charlie<br>
</div>
</div>
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-- <br>
<div dir="ltr">
<div dir="ltr">--------------------------------------------------------------<br>
Carl J. Nobile (Software Engineer/API
Design)<br>
<a href="mailto:carl.nobile@gmail.com"
target="_blank" moz-do-not-send="true">carl.nobile@gmail.com</a><br>
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-- <br>
<div dir="ltr">
<div dir="ltr">--------------------------------------------------------------<br>
Carl J. Nobile (Software Engineer/API Design)<br>
<a href="mailto:carl.nobile@gmail.com" target="_blank"
moz-do-not-send="true">carl.nobile@gmail.com</a><br>
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<div dir="ltr" class="gmail_signature">Best regards, Mike</div>
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