Originally Posted by
ariwere
DC powered battery (supply) goes through the esc comes out as 3 waves phase shifted 120 degrees (ac?) Clipped as a trapezoid wave with no negative alternation?
If the battery ESR and MOSFET on-resistance are sufficently low, then the voltage output from each ESC terminal will be at either zero or the full battery voltage while the MOSFETs are on. They essentially act only as switches. At full throttle, they are on for the entire length of each commutation phase (no PWM).
Originally Posted by
ariwere
If that statement is true then the ripple current seen is usually from ac to DC conversion in power supply circuits. Therefore where are we seeing ripple current from? A back feed from the motor?
The motor back-EMF is sinusoidal for each phase. Commutation makes this appear to the battery as a rectified 3-phase signal (DC with the tops of each sinusoid superimposed). The current has a similar appearance, but with maximums where the back-EMF is minimum (disregarding other effects from inductance, etc.) Again, this is for full throttle (no PWM).
Originally Posted by
ariwere
And to muddy the water more resistors in parallel divides resistance. So putting caps in parallel makes the ESR divide as well??? Lowering ESR will give a small bump in current adding to the "punch"? Based on lower resistance increases current??
Putting caps in parallel does divide the ESR for the combination. But this usually won't result in any perceptible increase in "punch" (power), as the commutation frequency is too low for the caps to supply current for a significant length of time.