Just to clear a couple of things up...

Both brushed and brushless ESCs use the same principles for throttle control. Voltage isn't varied; power is turned on and off many thousands of times per second to simulate partial throttle. The main difference is that for full throttle, a brushed motor is ON all the time. A brushles motor continues to pulse the power, just at a faster rate.

The three wires on a brushless ESC don't actually have specific names, like positive, negative, ground. Power is cycled through any two of the three wires in a sequence to make the motor go around. It'll be something like 1 to 2, 2 to 3, 3 to 1, and so on.