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“Tolerances are insane, especially if you’re 3D printing” is what someone told me when I said I was working on a cycloidal gearbox. I couldn’t agree more. This was the first project where I was punished every time I didn’t get my tolerances precise enough. Fusing 3D-printed pieces with metal was incredibly frustrating, and on a project where there were so many complex pieces, each mistake compounds. I chose the cycloidal drive as my first gearbox because I was very interested in the motion. I still remember I came across a YouTube video that was alluding to getting higher torque gears without teeth. Needless to say, it was an unskippable title, and after watching it, I was determined to get my hands dirty with a 3D-printed design. ...

Field oriented control is one of the predominant ways to maximize torque out of your BLDC motor. Here’s what I learned: Inputs to the control loop are obtained from each inverter stage. The inverters set a voltage that the motor coils respond to, and the response is sensed by shunts placed below each inverter stage’s lower leg. This results in 3 currents (Ia, Ib, Ic). The voltage across the shunts is measured and sent to the MCU to be discretized, transformed, and controlled. ...

Today, I’ll be showing all the sources of heat within a BLDC motor. We’ll be using the ODrive D5065 motor as our model. To start, there are 3 types of heat present in a motor at any time: core losses, copper losses, and mechanical losses. Starting with copper losses, you can have heat loss due to the motor demanding current from the electronic speed controller (ESC), which would represent DC current loss as described by $P = I^2 R$. Additionally, as a result of the motor requiring 3-phase power to work, we also have skin effect and proximity effect, the effects of which increase greatly at higher frequencies. ...