remove voltage-sense network from PCB

[codebot]

Greetings,

I propose that we remove the voltage-sense networks from the output of each of the BLDC output nodes (A/B/C). Reasoning:

• BLDC phase voltage-sense data is only useful when a motor is being driven in "block-commutation" mode, where 2 of the 3 BLDC phase lines are being driven (high/low) at any given instant, and the 3rd phase line is "floating", and that floating line has an analog voltage which is useful for estimating the commutation point. In field-oriented ("vector") control mode, which is used in robots because it's the only way to have nice current/torque control around the zero-velocity point, all 3 phase lines are being driven high/low all the time, so the voltage-sense lines don't have any meaningful data on them; they are always either hammered high (48v) or hammered low (0v).
• the BLDC output nodes are the highest-EMI component of the system since they switch far (0 to 48v) at super fast edge rates. Anything we can do to simplify those nodes (for example, by removing the voltage-sense divider) and shorten their PCB traces will help reduce noise in the system.
• removing components always reduces cost, albeit in this case it's only 6 resistors, but still, the placements do cost money.

OK to proceed with the removal?

[dgealy]

Happy to remove the voltage sense lines!

[gbalke]

Agreed. We don't use these at all!

[codebot]

awesome. Done!