Sensored vs sensorless. Essentially, it boils down to how the ESC can interpret where the rotor is in relation to the stator coils in the motor. Brushless motors have 3 field coils and the ESC switches 2 of them on at a time. The rotor is magnetic and is induced to move because of the electric current being applied in the coils. By switching the coils on and off really fast, the rotor turns and bingo we get and output that we can hook into the transmission.
A sensored motor has hall-effect (I think) positional sensors inside it which 'tell' the ESC exactly where the rotor is in relation to the sensors so it knows which coils to turn on and by how much. The upshot is that you get a better throttle response in theory which is helpful in our type of application where we are varying the throttle so much.
The downside is that you have an additional wire to package between the ESC and the motor and sensored motors don't like getting wet.
Sensorless motors relie on the ESC software to detect where the rotor is as opposed to the sensors - so depending on the ESC software, you can get some that are virtually as good as sensored in throttle feel or some where the motor will hesitate as you apply the throttle because the ESC doesn't quite know what current to pass to which coils. Modern sensorless ESCs are pretty good and they have the added bonus that the motors are more robust against moisture ingress (no sensors to go wrong). That said, most competition homologated motors are sensored but depending on the ESC, some sensored ESCs will allow you to run a sensorless motor as well.
I've run a Dynamite Sensored Fuze ESC with both a 3800Kv sensorless motor and a 7.5T sensored motor and I was pretty pleased and amazed at the throttle feel from the sensorless mode.
The other added benefit with sensorless is that the motors generally run slightly more efficient than sensored ones.
That's my humble understanding anyway - there are some very clever guys on here (much cleverer than me) and I'm sure they'll be able to chip in and fill in the gaps where I'm wrong.
|