Charly, 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. My design is at: https://github.com/cnobile2012/VoltageControlledPWM 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. https://www.mpja.com/Dual-H-Bridge-DC-Motor-Driver/productinfo/35567+MP/ It will handle two motors and is only $22.95 ea. They give full docs on their site. My PWM board shou interface with it fine.
~Carl On Sun, Oct 3, 2021 at 11:16 PM Charles West via TriEmbed < [email protected]> wrote: > Hello all! > > 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: > http://goodbot.ai/lib/exe/fetch.php?media=mk3draft1.jpg) 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). > > 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. > > 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. > > I'm currently using off-brand VESC motor controllers (schematic for normal > ones here: > https://vesc-project.com/sites/default/files/Benjamin%20Posts/VESC_6.pdf). > 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. > > 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. > > 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: > https://www.mouser.com/ProductDetail/STMicroelectronics/SRK2000A?qs=WHlX%252B%252B9%2FRwCG%2FkukabfLqA%3D%3D) > 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. > > If I may ask, does this sound reasonable or am I totally off base? > > Thanks, > Charlie > _______________________________________________ > Triangle, NC Embedded Computing mailing list > > To post message: [email protected] > List info: http://mail.triembed.org/mailman/listinfo/triembed_triembed.org > TriEmbed web site: http://TriEmbed.org > To unsubscribe, click link and send a blank message: mailto: > [email protected]?subject=unsubscribe > > -- -------------------------------------------------------------- Carl J. Nobile (Software Engineer/API Design) [email protected] --------------------------------------------------------------
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