Hello everyone.

Forgive my shortcomings in the field of electric motors.
I have disassembled a small portable fan and would like to ask you what kind of electric motor is mounted on it:




- In the stator I see concentrated windings which, if I am not mistaken, form 4 poles (2 north and 2 south).
- The rotor (ferromagnetic because if I put a magnet in it it is attracted) must be magnets .. so I think it is Brushless DC motor.

But if so, being DC powered with 5V .. would there be a small inverter mounted on the orange pcb visible in the photo?

 

All you need is a hall sensor coil driver to detect the magnet poles switching as it spins to drive a simple 2 phase motor by a simple coil current switch.
https://www.melexis.com/en/product/us91a/two-coil-fan-driver-high-voltage-alarm-output

 

It appears to be as the much larger washing machine variety. An out-runner motor, the rotor is the outer part and the stator is where the rotor normally is.
3ph ECM
https://www.fisherpaykeltechnologies.com/technology/direct-drive-motors

 

All you need is a hall sensor coil driver to detect the magnet poles switching as it spins to drive a simple 2 phase motor by a simple coil current switch.
https://www.melexis.com/en/product/us91a/two-coil-fan-driver-high-voltage-alarm-output

View attachment 327972

is already mounted on the pcb, can I use/connect to that with an oscilloscope? ..although I still don't know what I should measure, I'll look online at the datasheet

 

It appears to be as the much larger washing machine variety. An out-runner motor, the rotor is the outer part and the stator is where the rotor normally is.
3ph ECM
https://www.fisherpaykeltechnologies.com/technology/direct-drive-motors

So you are saying that the permanent magnets are in the red piece in the photo and not the blue one?

 

All you need is a hall sensor coil driver to detect the magnet poles switching as it spins to drive a simple 2 phase motor by a simple coil current switch.
https://www.melexis.com/en/product/us91a/two-coil-fan-driver-high-voltage-alarm-output

View attachment 327972

The number of poles, however, can be seen visually from the windings without the need for a sensor, right?

 

The number of poles, however, can be seen visually from the windings without the need for a sensor, right?

No , normally the number of poles are decided by the number of magnets on the rotor.
Also the customary way to determine the number of poles is to short the winding connections and spin the motor one rotation and measure the number of 'bumps' detected.
In post 5, that would be the magnetic poles and they rotate the rotor on a outrunner motor.

 

It might also be a synchronous motor, depending on how old it is. My impression is that BLDC motors always have multiples of three poles. active. External rotor motors have been around for a whole lot of tears. I had a LearJet 8-track player with an external rotor motor.

 

It might also be a synchronous motor, depending on how old it is. My impression is that BLDC motors always have multiples of three poles. active. External rotor motors have been around for a whole lot of tears. I had a LearJet 8-track player with an external rotor motor.

It IS synchronous, Also there are two ways to commutate, either 3ph sinewave, or BLDC, where only two windings are energized at any one time, generally the motor construction is identical, just the commutation is is different.
Motors of this type have now come into their own, mainly due to the use of rare earth magnets, the motors seen in all kinds of applications never usually seen before.

 

It IS synchronous, Also there are two ways to commutate, either 3ph sinewave, or BLDC, where only two windings are energized at any one time, generally the motor construction is identical, just the commutation is is different.
Motors of this type have now come into their own, mainly due to the use of rare earth magnets, the motors seen in all kinds of applications never usually seen before.

There are many types of electric motor and I don't want to confuse ..in this case:

- the rotor is outside the stator.
- in the stator there are windings powered by a controller that converts the DC input to AC (is it a half bridge chopper)? ..so a rotating magnetic field is generated
- at the rotor there are permanent magnets .. post #5 ?

 

As I said, the picture indicates an out-runner style BLDC etc, The rotor usually possesses the PM magnets, whether out-runner or conventional style with an internal rotor.