Multi-Axis "Modular" BLDC Driver

An attempt to create a motor driver-board for general use.

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This project started from wanting to make a low(er) cost multi-axis motion simulator. It's a bit of a story, but ultimately I ended up trying to develop a multi-axis BLDC driver.

So, for this project I'm attempting to build an ATMega based ESC driver-board that drives multiple BLDC. The ESCs will be controlled by a "master" ATMega hub by I2C, the i2C line will also include a header to enable connecting (future planned) "support boards"

The ESCs will include the following features:
- current sensing
- field oriented control
- (attempted for low KV BLDC) step-counting using the motor's included sensors.

The features of overall board:
- USB / SD card functionality
- Load motor pre-sets to ESC from SD card (through I2C)
- Power/Current limiting per ESC (through I2C)
- Multiple operating modes (simple speed control or steps + speed control) (through I2C)

This board is meant to drive several (the goal is to make the board extendable from 1 to 6+ ESCs) BLDC motors for general use (originally a multi-axis motion simulator).  

Currently, the board is being designed with the following motors in mind:

   -  N5065 Sensored BLDC

   -  10S

   -  270 KV

   -  1820W, 50A max

So, from those requirements I've selected the following components as a basis for my ESC:

   -  SIR186LDP-T1-RE3 (Mosfets; 6 per ESC)

   -  LF2388BTR (Gate Driver; 1 per ESC)

   -  ATMEGA168PA-AU (controller; 1 per ESC)

   -  CRK0612-FZ-R001E (shunt resistor; 3 per ESC)

   -  OPA991IDCKR (op-amp, 1 per ESC)

   -  Various passive components (BoM to come later)

A quick summary of the ESC components:

The mosfets are probably oversized at 80A continuous drain (they should have ~50% duty cycle), but I've haven't decided on how I'd like to cool these yet.  So, in the future they can probably be downsized but for $1.05 each I'm not too worried (yet).

And because I'll be driving so many mosfets (especially on a large board) I opted to include a gate driver for each ESC, this too might not be necessary but for mosfets this large I'd rather drive them with a specialized chip as opposed to trying to push the ATMega.

The shunt resistor(s) are for current sensing, with all three in parallel they'll be passing .67 Watts (rated at 1 Watt).

The op-amp boosts the voltage output from the shunt resistor for current sensing (currently hits 5V at 77A with surrounding components).

  • Update and Current Condition

    Ketchup-Packet04/16/2022 at 04:32 0 comments

    2022.04.16 Update:

    Apologies for the long delay in terms of updates.

    I picked up some other projects after I had some issues regarding ordering the PCBs and supply shortage (ATMega), and moves away from this for several months.  However, this project has been in the back of my mind since, and I've grown frustrated of waiting.

    So, I am pleased to say that the PCBS have now been ordered (with the respective stencils) and should be arriving in the coming weeks.  From now, I will be focusing on acquiring the board components, and getting the needed hardware for programming the ATmega chips.

    However, regarding the ATmegas specifically, I'll have to search alternate sources for these chips, at least enough to build some prototypes.  Originally, I've been looking to purchase all of my components from Mouser, however they estimate to have these chips back in stock in February of 2023.

    Which, taking into account the seemingly continuous meltdown of our global infrastructure; is understandable yet quite frustrating.

    So, if I can source these chips, expect more updates soon, I expect to begin building the boards as soon as the supplies are in, and begin creating the firmware for the board.

    If not. . .  I'll have to pivot to the software side of things until the physical components can be located.

    (Worst case, maybe eBay will come in clutch).

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