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I would like to be able to control various kinds of sensorless brushless DC motors for robotics. Hobby ESCs are everywhere but I'd like to drive motors with a simple PWM output from a central controller without having to create a servo-like control pulse. First because it's marginally easier to do in software. Second because it would then be possible to replace existing brushed DC motors in existing equipment without modification.

I have found the MTD6501G which looks just fine and I see many people successfully driving dismantled hard drives and fan motors with it. However it can supply only 0.8A.

Another is DRV8301 - more complicated, more expensive, more external components required.

Would it be possible to use the MTD6501G with motors requiring more current by using cheap external drivers like MJE2955 on each of the phase outputs?

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    \$\begingroup\$ Not a straight answer to your question but you might want to look at Vedder ESC at vedder.se/2015/01/vesc-open-source-esc it's a very capable open source ESC which can be controlled with multiple different busses including SPI and CAN. See if it suits your needs. \$\endgroup\$ – olltsu Sep 20 '16 at 5:27
  • \$\begingroup\$ That's certainly a capable ESC - might be overkill but if this way isn't possible I'll look into building some. Thank you. \$\endgroup\$ – Adam Eberbach Sep 20 '16 at 5:46
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    \$\begingroup\$ Using external transistors is likely to defeat the internal control algorithm that makes the chip work without a motor position sensor. \$\endgroup\$ – W5VO Sep 20 '16 at 11:21
  • \$\begingroup\$ The open source replacement firmware for hobby ESCs typically supports, or can be modified to support, other command inputs. \$\endgroup\$ – Chris Stratton Sep 21 '16 at 4:53
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Thanks to those who reviewed and commented. Looks like MTD6501G is not going to work because using it to drive external silicon to increase power handling would remove the feedback from the windings that the device requires.

DRV8301 or similar does seem to be the only option if you must build your own speed controller.

The Vedder ESC is what I will probably buy for some immediate uses, and think further about experimenting with DRV8301 or similar devices - but it is going to need a reflow oven to mount so that is another challenge to overcome.

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Please try L298 as output stage to increase Current Capability. https://www.sparkfun.com/datasheets/Robotics/L298_H_Bridge.pdf enter image description here

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  • \$\begingroup\$ Can you further explain the applicability of an H-bridge to the problem controlling a three-phase brushless DC motor please? \$\endgroup\$ – Adam Eberbach Sep 20 '16 at 5:33
  • \$\begingroup\$ It cannot control the dc brushless motor. The MTD6501G remains as controller. L298 purpose is to increase the current capability (up to 4A). Use this IC is easier than add 3 sets (6 pcs) of transistor. \$\endgroup\$ – Tristanto Sep 20 '16 at 6:56
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    \$\begingroup\$ No, this is a terrible choice, even apart from needing one and a half of them \$\endgroup\$ – Chris Stratton Sep 21 '16 at 4:55

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