Motor Control
Need to do a good writeup so I am not a pathetic engineer who only does software.
Resources
- Fundamentals of motor control by STMElectronics
There’s like your brushed motors, which you simply control by sending voltage through it.
- The motor’s rotation speed is proportional to the voltage
- The load determines how much current you are drawing from
For a BLDC Motor, there are two things sent to it:
- Current → controls how much torque, intensity of the field
- Frequency (through pwm signal) → controls how fast you are alternating between the poles
Those things are mediated by an ESC.
lots of edge cases
like the ROBOTIS motors (XL-330s and XL-430s) did not use an ESC, so idk how they were controlled.
What about voltage?
I mean you can’t just arbitrary send extra voltage to a motor, can you?
- Yes, that’s the holding torque. But how does that work? Like usually, the current going through a system is determined by how much resistance there is. So is the motor controller the thing that is varying the current, or the resistance of the motor? Like how does that work?
- I think it’s the other way around, you can’t arbitrary say you want to send 2A and it sends 2A
- If your input source is 12V, you can “kind of” send 6V by doing PWM (12V with 50% duty cycle)