How to Set the Number of Motor Poles (and Find Pole Pairs) on SOLO

Number Of Poles for a Brushless or a Permanent Magnet Synchronous Motor

Introduction

One wrong number can make your motor report the wrong speed and commutate badly. The number of motor poles is that number. Set it too low or too high, and SOLO drives the motor as if it spins faster or slower than it really does, so the speed reading drifts and the motor can stutter or refuse to run.

The fix is short. Find your pole count from the datasheet, the nameplate, or by counting magnets, then enter it in Motion Terminal. This guide shows both steps, in order.

Poles vs Pole Pairs: Quick Definition

A motor pole is a single magnetic pole on the rotor, north or south. Poles always come in north-south sets, so the total pole count is always even. A pole pair is one north pole plus one south pole, which is why pole pairs are simply the pole count divided by two.

A motor with 14 magnets on the rotor has 14 poles and 7 pole pairs. The two numbers describe the same motor. The difference matters only because some fields ask for poles and some ask for pole pairs, so you need to know which one you are entering.

Takeaway: poles are the magnetic poles on the rotor, pole pairs are half that count.

How to Find the Number of Poles on Your Motor

Most motors tell you the pole count somewhere. Start with the easy sources, then fall back to counting or a quick test if the data is missing.

From the Datasheet or Nameplate

The fastest source is the datasheet or the nameplate on the motor body. Look for “poles”, “number of poles”, “pole pairs”, or “P”. A line like “8 poles” or “4 pole pairs” answers the question directly.

Watch the wording. If the sheet says 4 pole pairs, the pole count is 8. If it says 8 poles, the pole pairs are 4. Some BLDC datasheets also list the magnet count, which equals the pole count for a standard surface-magnet rotor. When two values seem to disagree, trust the one labeled in plain words over a guess.

Counting Magnets or Slots

No datasheet? You can count. On many BLDC and PMSM motors you can open the housing and count the permanent magnets on the rotor. The magnet count is the pole count. Count carefully, because the magnets sit close together and are easy to miscount by one.

Do not confuse poles with stator slots. The slots are the teeth that hold the windings, and their number is usually different from the pole count. For example, a common hobby motor is 12 slots and 14 poles. Count the rotor magnets for poles, not the stator teeth.

Deriving It from Electrical vs Mechanical Revolutions

If you cannot open the motor and have no datasheet, you can still find the pole pairs with a test. The rule is simple. The motor goes through one electrical cycle per pole pair for every mechanical turn. So a 7 pole pair motor completes 7 electrical revolutions for each full turn of the shaft.

Turn the shaft slowly by hand for exactly one mechanical revolution and count the electrical cycles SOLO reports. That count is your pole pair number. Multiply by two to get poles. This method is rough by hand, but it gets you a starting value when nothing else is available.

Takeaway: datasheet first, count magnets second, derive from electrical cycles as a last resort.

Setting the Poles Parameter in Motion Terminal

Once you have the number, entering it takes a few seconds. Open Motion Terminal, connect to your SOLO unit, and go to the motor configuration panel. Find the field for the pole count in the motor parameters group, next to the other motor basics like motor type and rated current.

Read the field label before you type. Some firmware fields ask for the number of poles and some ask for pole pairs. Enter the value that matches the label. If the field is labeled poles and your motor is 7 pole pairs, type 14. If the field is labeled pole pairs, type 7. Then save the parameter to the controller so the value persists after a power cycle.

Verifying with a Slow Spin

Always confirm the value before you trust it. Command a slow, low-speed spin in open loop, or turn the shaft by hand, and watch the electrical angle or electrical revolution count in the monitor. For one full mechanical turn you should see the angle wrap exactly as many times as your pole pair number.

If you set 7 pole pairs and the angle wraps 7 times per mechanical turn, the value is right. If it wraps a different number of times, your pole count is wrong, so go back and re-check the spec. This slow-spin check catches most pole-count mistakes in under a minute.

Takeaway: enter the value that matches the field label, then verify with one slow mechanical turn.

Why the Poles Value Affects Commutation and Speed

The pole count is not a cosmetic setting. SOLO uses it to convert between electrical and mechanical motion. Commutation, hall decoding, and encoder math all depend on it.

For speed, the controller divides the electrical frequency by the pole pairs to get mechanical RPM. A wrong pole count scales the speed reading by the same wrong factor. Enter half the real pole count and the reported RPM is double the real value.

For commutation, hall sensors and encoders both report position in electrical terms that SOLO maps back to the rotor using the pole count. With the wrong number the commutation timing is off, so the motor can cog, draw extra current, run hot, or fail to start. With hall sensors, this maps the six hall states to the right electrical sector. With an encoder, it sets how many counts make one electrical cycle. SOLO reads rotor position through motor encoders and other feedback devices, and the pole count ties those readings to real shaft motion.

Takeaway: poles link electrical and mechanical motion, so a wrong value breaks both speed and commutation.

How SOLO Helps You Set Motor Poles

SOLO controllers keep the pole count as a clear, single parameter in Motion Terminal, so you set it once and the firmware uses it across speed, commutation, and feedback. The terminal lets you run a low-speed spin and watch the electrical angle, which makes the slow-spin check easy to do right after you enter the value. SOLO supports hall sensors, incremental and absolute encoders, and sensorless modes, and the same pole count feeds all of them. You can configure it on any of our motor controllers through the free Motion Terminal.

Conclusion

Setting the number of motor poles comes down to two steps. First find the value from the datasheet, the nameplate, or by counting the rotor magnets, and remember that pole pairs are half the pole count. Then enter it in Motion Terminal, matching the field label for poles or pole pairs, and verify it with one slow mechanical turn while you watch the electrical angle wrap. Get this number right and your speed reading and commutation line up with the real motor. A good next step is to open Motion Terminal on your SOLO unit and set the pole count now, then run the slow-spin check to confirm it.

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