2 hall sensor and 3 phase BLDC motor
2 hall sensor and 3 phase BLDC motor
(OP)
Hi all,I get a brushless permanent magnet motor used on autobike, with 2 hall sensor, but 3 phase of delta connection.
its back EMF is sinusoidal well. And I know most of BLDC motor use 3 hall sensors to detect the rotor position and sent the signal into controller. also its back EMF is trapezoidal. But this motor is much different, could anyone give a answer about it?
Thanks
its back EMF is sinusoidal well. And I know most of BLDC motor use 3 hall sensors to detect the rotor position and sent the signal into controller. also its back EMF is trapezoidal. But this motor is much different, could anyone give a answer about it?
Thanks





RE: 2 hall sensor and 3 phase BLDC motor
What is so different about the motor that has you concerned? Also, if not already in place, when using longer battery leads , it is a good idea to place some extra capacitors at the input terminals of the controller. Varying speeds with a trapeziodal controller tends to be hard on the controller perhaps due to the inductive effect of the longer wires.
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If it is broken, fix it. If it isn't broken, I'll soon fix that.
RE: 2 hall sensor and 3 phase BLDC motor
RE: 2 hall sensor and 3 phase BLDC motor
Yes, you can get away with using only two sensors, however starting the motor is a problem, as you don't know exactly where the rotor is.
I would expect the controller for this motor to apply a rotating three-phase field to get the rotor turning, and as soon as this is established then use the signals from the two sensors to synthesise the third phase.
If this is some kind of constant-speed application it would be OK.
Benta.
RE: 2 hall sensor and 3 phase BLDC motor
this isn't cost-optimized design - I hope this is 2 sine analog Halls instead 3 digital Halls! Some sine servo amp may use them for sinusoidal commutation of PMBL motors.