A motor's top speed RPM is determined by several things but one that is useful to be able to discover is the number of poles. Sometimes however it's useful to know. More generally though, it allows us to calculate whether an ESC will be able to switch the voltage between the windings fast enough to reach the speed of rotation we need.
The more poles the faster the ESC switching must be per revolution and ESCs have limits but most of the time it's not this but the supply power against the load that limits the speed. The poles we are interested in as far as ESCs are concerned are simply the number of magnets in the motor so if you can see the magnets you can find the number of poles easily. If you can't then it gets more complicated often involving an oscilloscope and driving the motor while monitoring the frequency of the output between two of the three windings.
Pendantic side note: OK so actually each magnet has two magnetic poles North and South but since only one of those is facing the windings we can safely ignore the other one as it doesn't interact with the motor and so the number of poles in a motor becomes the number of magnets.
A two pole motor below. It happens to be a stator from a brushed motor but that's not important here, poles are poles whether it's brushed or brushless:. See below a 12 pole rotor from a broken brushless outrunner. A couple of the magnets have lost their shiny metal coating due to contact with the stator hence being broken and can't be seen very well but the arrows show where they are. As a side note, some ESCs will allow you to choose the "timing" often low, med, high.
This is very like the timing of the ignition in a car and sets the number of degrees of "advance". The stator windings need to reach peak magnetic field strength at the correct time relative to the position of the rotor. This correct position varies with many things but the size of the motor tends to be the one we can most easily see.
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In electric motors the required timing relates to the rate at which the windings magnetise and de-magnetise when power is applied which is in turn related to the size of the winding. Put another way round, because it takes a bigger winding longer to reach peak magnetic field strength when voltage is applied the brushless ESC must begin applying that voltage earlier to get the winding to a condition where it can most effectively pull the rotor around.
Brushless motor "poles" and how to count them. What is Heli-Hack? Fixed Wing Aircraft sprooce. Blade mCP X sprooce. Brushless motor "poles" and how to count them sprooce. ESC Timing - what it is and how to choose it sprooce. HBFP Brushless main motor sprooce. Revo Mixing sprooce.Simply defined, a pole is a north or south magnetic field of force that is generated by a permanent magnet or current passing through a coil of wire.
For stepper motors, however, this definition does not necessarily translate to a simple definition of pole count. Different manufacturers use different names to refer to their poles and various stepper-motor types have varying kinds and numbers of poles.
Permanent-magnet stepper motors are the simplest. Manufacturers define their pole count by the number of pole pairs or stator windings.
Increasing the number of pole pairs on the rotor itself or adding more stator phases increases resolution. Variable-reluctance and hybrid stepper motors have teeth on their rotors, and stators define pole count. These types of stepper motors move 1. Rotation step angle is half that of a permanent-magnet stepper motor with the same number of stator windings.
The two cups have teeth that are offset by one tooth in relation to the other. Here too, the greater number of teeth, the greater number of poles, the higher the resolution and the smaller the steps. This can influence design decisions in a few ways. Basically, the more poles, the more precisely a drive can control stepper motor output.
Beyond this simple fact, manufacturers offer varying arrangements and numbers of stator poles and teeth.
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Because pole count affects torque as well, it can lead to design decisions related to inertia matching as well For more on inertia matching, see FAQ: How do stepper motors handle inertia mismatch?
One last note: because the angle of step affects motor vibration and noise, designers should keep that motor feature in mind when making decisions about pole count. You must be logged in to post a comment. You may also like: 7 questions to ask before picking an ac motor drive… FAQ: What is stepper drive idle-current reduction and why does… Minimizing stepper motor vibration with affordable technology Open-loop stepper motor versus closed-loop stepper motor systems Updated: Trends in electric motors Part I — Miniaturization, connectivity,….
Leave a Reply Cancel reply You must be logged in to post a comment.Frequency Converters. Variable Frequency Drives. Power Inverters. Voltage Converters. Soft Starters. There are many much more interesting questions related to the pole number of induction motors, e. Does the induction motor supplied by the main grid say, 50 Hz increases its torque capability in "p" times with growing pole number "p" since its speed decreases in "p" time like in a gearbox?
Are performances of these two motors different or the same? Please note excluding frequency and inter-coil connections all remained the same. It depends on the required speed.
The 60 is there to convert from revolutions per second to revolutions per minute as the frequency is in cycles per second. The induction motor will run at a slight less speed due to "slip" which is what gives the motor its torque. For example 5. When selecting a three phase motor, the number of poles is chosen to achieve the speed of rotation that you require.
The actual running speed is the synchronous speed minus the slip speed. For a 50 Hz three phase supply:. To determine the number of poles, you can read the data plate directly or calculate it from the RPM stated on the data plate or you can count the coils and divide by 3 poles per phase or by 6 pairs of poles per phase. Where the power of the induction motor is constant, the torque increases at the rate that the speed decreases. I often see name plates with things like VAC, When these "specials" are made I usually see 6 pole machines - but that may be just a manufacturer's preference.
You have no items in your shopping cart. Blog Tags. Home Blog How to determine the pole number of an induction motor? How to determine the pole number of an induction motor? Saturday, November 15, Tags: Induction Motor. Leave your comment. Is no. So the name of the article is "how to determine the number of poles of an induction motor" i read the whole article still don't know how to determine the number of poles on an induction motor.March 30, When one refers to How many poles an electric motor has, they are commonly referring to how many magnetic poles there are.
Many often wonder the differences between motors having more or less poles. Here, we will focus on a brief discussion concerning Brushless motor magnetic poles. Main focus will be placed on In Runner Motors, where the rotor spins inside of the stator. Common in runner motors have 2 or 4 magnetic poles. There are some motors containing 6 poles as well.
Outrunner motors may have in excess of 6 magnetic poles. You may want to read more on outrunners vs inrunners and what the differences are. The largest characteristic that a motor with more poles displays when all else is equal is a drop in the KV value. When all else is equal between 2 brushless motorsthe one containing a higher pole count will have a lower KV value.
This is the number one important characteristic of differences in a motors pole count. All else that we will talk about is based off of this. It may not be what you thought it was. Pole counts do influence cogging torque on slotted motors. Generally on inrunner motorscogging torque increases as you increase in magnetic pole count. The torque is gained as a result of lower KV. Depending on the exact application this may be an advantage or disadvantage.
There is one route a Motor Manufacture may take in order to bring the KV back up to a usable amount. The best option is to decrease the amount of winds in the motor. A 2 Pole motor for example will typically have many more winds than a 4 Pole motor. When a 4 Pole motor has the amount of windings reduced, KV will increase back to the amount needed. When a winding from the motor is removed, the physical size of the motor remains the same resulting in a void.
The best solution to this created void is to add more copper. More Copper is added to the winding. This is done in such a way similar to moving down in the Gauge type. In other words the wire used as a wind is now increased in diamater.
As we know from electrical theory, when the cross section of a wire is increased the resistance decreases. This decreased resistance would allow a greater current load to pass through the motor. When comparing a 4 Pole motor that has the same physical size as a 2 Pole motor and the same KV as a 2 Pole motor, the 4 Pole motor in theory would be able to handle greater current loads.
The greater current loads will result in greater power. This is similar to saying a 4 pole motor has better overall efficiency when compared to a 2 pole motor.Maximum reliability Maximum dynamic response Extremely compact High overload capacity Maintenance-free operation Can be installed in any position Degree of protection IP The DT high torque motor series provides an innovative concept for highly dynamic applications.
With a high pole count and optimized lamination geometry, these motors achieve an excellent power density and a system-efficient torque.Full Pitch and Short Pitch Winding (Worked Example)
With this motor series you receive a compact drive that is particularly well-suited for applications with a high cycle frequency. The motors are available in convection-cooled and liquid-cooled versions. Developed with high reliability, high dynamic response, compact dimensions, and largely maintenance-free operation in mind, this series with its high overload capacity is ideal for peak loads.
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How to determine the pole number of an induction motor?
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Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It only takes a minute to sign up. I am having trouble finding diagrams to show induction motors with poles not equal to 3x.
Everything I find is 2 poles per phase. Can anyone explain and help me visualize, for example, a 4 pole 3 phase induction motor? Images from Basil Networks permanent magnet brushless motors page. This is worth a read as it shows the series motor connections.
Figure 4. Source Wikipedia: induction motor. Because a magnet field has two poles N and S, or one pole pair. And it is not poles per phase, but rather poles or pole pairs. For example you have a two pole motor, or a motor with one pole pair, which is the same. The picture below is a representation of magnetic flux of 2 pole vs. Edit: You should search for rotating magnetic field. The current in three phase winding generates magnetic field of constant magnitude that rotates if the currents are AC.
The same could be done with two phase windings with 90 degrees appart, but we would need 4 wires, meanwhile the three phase system uses only 3 wires. Therefore the number of phases isn't related to the number of pole pairs. Edit2: Special for user JonRB that has no idea of induction motors, see there are 2,4,6, Sign up to join this community.
The best answers are voted up and rise to the top.Choosing the best quadcopter motors is critical if you are serious about performance. Without the right motors, nothing else will matter much.
Your drone will simply not perform as it should. You might try rewiring, using a different set of blades, replacing the controller board or maybe even tinker with the frame. If your motor selection for your quadcopter is not right, your multicopter will not perform well. Motors have a huge impact on how the craft performs — perhaps a lot more than any other part or accessory.
Another reason why you will want to be careful in selecting the right motors for your quad is the cost. Motors can be pretty expensive — especially the brushless ones.
This page will explain all of the complex sounding stuff and make the task of choosing the right motors easy and fun! It is best to choose motors that can rotate both clockwise and counter clockwise. Quadcopters have 4 motors — and for the highest stability, two of these rotate clockwise while the other two rotate counter clockwise. You can buy motors that are either clockwise or anti clockwise only, but that would make the craft a lot harder to fly.
Sure, there are algorithms that can take care of the resulting instability for you, but these would be really hard to keep in the air if you are relatively inexperienced and choose to fly in the manual mode.
You would need to have some understanding of what pole count of a motor is, but you would not want to fuss about this. A motor with a higher pole count requires more voltage and produces more torque — or lift. But it also will have a lower rpm or revolutions per minute.
You will want to use larger blades with these motors. A motor with a lower pole count has more rpm and requires less voltagebut the corresponding output torque — or lifting power — is also lower. The propeller blades also have to be correspondingly smaller as well. These motors will not be able to handle larger propellers.
Quadcopters generally use higher pole count motors — outrunners — so that they can avoid using a gearbox. High pole count motors output a high torque — and this means a gearbox will not be necessary to increase the torque. This is a critical number you would need to pay attention to. The Kv value is critical when you want to calculate the load a motor will be able to carry. Note : The notation is Kv and not kV. A motor with a Kv rating rotates at a speed of rpm when 1 volt is applied at no load.
If it happens to be a 12V motor, then it will rotate at a speed of 12, rpm at 12 V under zero load. Another Kv motor has a maximum rpm of 40, and is rated at watt. With a drop in Kv value, the torque produced by the motor increases. More torque means more acceleration, and more lifting power. Conversely, motors with higher Kv value produce less torque.
For motors with higher Kv value, you will have to choose smaller propellers. With smaller propellers, you can achieve higher speeds, but efficiency will be lower. On the other hand, motors with lower Kv value can handle larger propellers that can lift more weight, use less electrical current, are more stable — but have lower speeds. A higher pole count motor will have lower Kv value, can output more power and has less rpm.