Brushless motor main lead interupt

Got a crazy idea the other day, but I need to shut off a brushless motor to do it, does anyone know if it would be safe to shut off a brushless motor by disconnecting only ONE of the three motor leads? Meaning that if a motor was running at 3/4 throttle, prop spinning, and there was a toggle switch installed in-line on ONE of the motor leads and I switched it off will the motor stop? And will the ESC/Motor be OK and not burn up? If not one, then how about switching off two or all three motor leads? And of course, I will need to switch it back on again.

Thanks

Short answer is NO it wouldn't Shut-off, would only spin slower ... From a start position and depending on the Armature's position the Motor may not start or have difficulty starting. But of course swapping any two leads will change the Motor's direction of spin

From OUR friends over at Helifreak, for the How & Whys the following LINK will or should give ya just that --->

          Capi's Brushless Motor and ESC 101

Bit of a side note and name dropping Capi is a neighbor living just a few blocks away.
Anywayz he is one of the more knowledgeable pilots around the Freak, especially when talking "electronics" 
... And although this is Off-Topic he also does a 101 Tutorial for the GYRO: Capi's Gyro 101. Both good reading ...

That's incorrect there Wood, In standard brushless motors there are three leads, two leads are current inputs and one is a neutral or sometimes referred to as a sense wire.  If you were to cut either of the two outside leads the engine will stop producing power but will freewheel.  If you have a brushless rig of any sort disconnect one of the outside leads either red or black and try it yourself, the engine will not move.  So the short answer is yes it will cut the motor if you have a disco of some kind, no it will not hurt anything and though it may not produce any power the engine will not come to a stop immediately since there is no current to stop the engine from turning.  Now dual pole brushless motors are different and I will not even try to explain there theories as it would make my head hurt.

Yup that is incorrect ... Lesson learned always check your source which in this case was me  :-[

But when I just tried what you say, If ANY one of the leads is cut the motor will (eventually) come to stop. I tried all three and the result was the same. As ALL three wire supply voltage albeit it in the form of PWM which I have verified with my oscilloscope. As it my understanding that ALL three leads are equally the same I don't get or understand your definition of what the colours mean or what each wire does. The ESC I tried uses Blue, White and Red and reversing any two of the leads WILL reverse the motor direction of spin and cutting ANY lead regardless of it's colour the motor will STOP. So I'm not sure where the misunderstanding is, unless it's the difference between a sensored and sensorless motor ?? And there "there is two ways to determine the position of the rotor, the first is with a Hall Sensor. The 2nd method is the so called "Sensorless Brushless Motor" which uses the back EMF voltage to determine the position of the rotor"


QUOTE: A brushless motor works on the same principle as the brushed motor but instead of using a mechanical commutator to redirect the current to the coils in order we use an electronic commutator. By applying a voltage or current to the winding at the proper timing we can replicate the commutator and turn the rotor . The motor and esc have three wires connected to each other forming what is known as a 3-phase motor. Each phase will be connected to a pair of windings. Lets assume phase-A will connect to the 1,4 coils , phase-B will connect to the 2,5 coils and phase-C will connect to 3,6 coils. The coils will be wires into a "Y" connect as shown below ... CONT /quote

But regardless you are correct when I removed ANY ONE lead the motor did stop w/ no apparent harm to the motor or ESC

Thanks guys, Wood, I will read through the link you posted, but I already have learned a lot just from what you guys posted here. I think I figured out how to avoid needing to do what I had thought yesterday, but maybe not. Either way it looks like the idea would work. Lets just say at this point, it involves my future tricopter build.

LOL, when one says "Let's just say" ya gotta know it's only gonna pique my curiosity So what's the idea

Ha Ha, well first I got to finish the big heli, which had a lot get done this weekend, a video will be up within a few days, then I gotta just build a basic tricopter and get it to work, but then I was thinking about a way to use the tricopter as a tilt rotor airplane/tricopter device. i don't see any reason why it won't work in my mind, but you never know with these things.