I am trying to figure out how to determine the correct winding pattern for a 3-phase BLDC motor, given that there are 10 poles and 18 slots. I have seen the very interesting post here., but as the 10-pole 18-slot pattern has not been confirmed, I am wondering how these patterns were devised in the first place.
Electrical – How to determine brushless DC (BLDC) winding pattern, based on poles and slots
brushless-dc-motor
Related Solutions
You are most likely not driving the high-side MOSFET with enough voltage to turn it on. You need to have VCC+1V or more at the gate to turn those on fully. Typically you would use a gate-driver IC to do this, which has a built-in boost circuit (bootstrap circuit).
The position depends on the design of the motor, but the position of the sensor is not magic.
The following image shows the most simple BLDC motor with just one pair of coils and a rotor with two poles, at the moment when polarity is changed:
From left to right:
- The e-magnets still attract the the poles the permament magnet of the rotor and create torque
- The polarity of the e-magnets changes
- The e-magnets repel the poles of the stator facing them and attract the poles on the opposite side, creating torque
The hall sensors of these BLDC motors often already contain a comparator giving a high or low level, indicating if they see a N or S pole.
In the example above, such a sensor would be placed where the blue triangle is. The electronics behind would make it so that the polarity of the e-magnet on the right is always the same as what the sensor sees.
You'll find this principle in that fans used in computers, though there are two pairs of coils and the rotor has four poles:
(Source)
Note that the sensor is placed so that it sees the transition when the poles of the rotor are exactly aligned with the coils!
Another type of motor uses a rotor with two poles and three pairs of coils:
(Source)
In the most basic mode of operation, each pair of coils changes its polarity when the rotor poles are aligned to it, i.e. pair A1/A2 is just about to change in the picture. (In reality, it's more complex, see the source). So you could use three hall sensors in there, each responsible for one pair of coils.
So, now it depends on the design of the motor - how many coil pairs are used, and how many poled does the rotor have. With some logic or some intelligence of the controller, it is also possible to spare some sensors.
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Best Answer
An updated version of that chart can be found at www.bavaria-direct.co.za. Here it is:-
Based on the legend
Colors (by Relph Okon)I am guessing they have been confirmed. It was probably compiled from the results of experimental winds done by several people.However many combinations can be calculated by multiplying the patterns of those with fewer poles (eg. 4 poles and 6 teeth has the same pattern as 2 poles and 3 teeth), or applying some basic rules.
The essential rules are that the number of poles must be even and the number of teeth must be divisible by 3. Secondary rule is they must not be equal (eg. 6P-6T) or an exact multiple of same (6P-12T). Best combinations seem to be where they are as close to the same as possible within those rules (eg. 2P-3T, 10P-12T, 14P-15T).