Arduino control TIP121 transistor to driving motor.

ian field

Joined Oct 27, 2012
6,536
PicMicro recommend a starting point of around 4Khz to avoid motor noise, buzz.
Max.
Most likely I'd put up with a bit of vibration in preference to an annoying whine.

Its not just the winding inductance becoming significant and limiting torque, increasing the frequency also increases losses in the armature laminations.
 

MaxHeadRoom

Joined Jul 18, 2013
28,618
I still am curious how a BLDC motor is going to be controlled by two power leads?
The last PWM controller I put together ran around 4.5Khz for a 2Hp Treadmill motor.
Many commercial drive operate around 20Khz switching freq., induction motor VFD's for e.g.
Max.
 

ian field

Joined Oct 27, 2012
6,536
I still am curious how a BLDC motor is going to be controlled by two power leads?
The last PWM controller I put together ran around 4.5Khz for a 2Hp Treadmill motor.
Many commercial drive operate around 20Khz switching freq., induction motor VFD's for e.g.
Max.
The picture posted by the TS looks pretty much like a brushes motor that you might find in any number of toys - come to think of it, same kind of motor died in the last shaver I had pack up.

If the TS is using a BLDC, its a VFD that's required to vary the speed - not PWM.
 

MaxHeadRoom

Joined Jul 18, 2013
28,618
Except the small BLDC motors you buy off ebay that has two leads has an internal commutation circuit/system and 3 stator winding, as is customary for BLDC.
Similar to PC DC fans now.
Max.
 

MaxHeadRoom

Joined Jul 18, 2013
28,618
IWHT: the control range would be pretty limited.
Not sure by pretty limited, these are the commercial BLDC drive I use and they use a switching frequency of around 20khz, IRC. (They can also be configured for DC brushed).
There has to be some way of getting phase shift when using two motor conductors to a PM rotor motor.
Max.
 

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