BEST HUB MOTOR 4 all Bake

Beagle123 · **May 2, 2007**

I read the links provided, and they were interesting. However, I'm more interested in data that will help me build a better bike.

Fetcher, check me if I'm wrong, but I've concluded from reading that dc motors will increase their RPMs proportionally with voltage.

Correct?

Also, an increase in current producess more torque (?)

Correct?

Thses kinds of principals are really helpful to me when I'm trying to design a bike.

Another really important point is that every motor has a range of RPMs that are very efficient. Knowing where that band is, and how to change/optimize it is very useful information.

I can't say that I understand it all yet, but when I do, I'd like to write a guide to help people choose and work with dc motors. It seems like its pretty easy to run your bike in an inefficient manner (but maybe not).

For example, suppose you have a 24v motor, and you want to run 20 amps through it at 36v. How will that change the numbers for the motor?

I wrote a topic on my current situation "here"

Beagle123 · **May 2, 2007**

O.K. Now we're getting somewhere.

Take a look at this motor:

<a href="http://www.lemcoltd.com/lem_170.htm">LEM-170</a>

At the bottom of the page are three Excell Spreadsheets that show the motor's performance at 24v, 36v and 48v.

Would you agree with tise statement?:

Eventhough this motor looks excellent, its a bad choice for a scooter becasue its too big. If you look at the graphs, at 48v the motor "barely gets off the ground" at 50 amps. This motor performs best at 150 amps, so its better suited for a motorcycle etc.

Do you agree with this?:

The biggest problem with electric motors is the "accelerating from a stop" phase. So smaller motors may be better at getting up to the speed they need to perform best.

And, motors perform best when they have a significant load. I.e. taking a 750w motor and making it put out 400w. This would favor the smaller motors as well.

It seems like choosing a motor that's too big could easily be a problem.

Agree?

Also, I think that Lemco page I found could be a good resource to write a guide for choosing how to run a motor. Or perhaps the rule of thumb should be "go with the higher voltage."

Thanks fetcher. You're really help a lot of us on this site. I hope I can contribute more in the future as I learn more.

By the way, I'm considering this motor for my next proiject:

<A href="http://tncscooters.com/product.php?sku=106170">Cheap Unite Motor</a>

If I'm correct, it should produce nicely when asked to produce 600w or so.

SolarTriker · **Feb 14, 2010**

Ooooooh I'm loving this stuff fetcher!!!!

Thanks for posting this! Really going to have to put in a few hours and get my head around it all. I'm in no real hurry with my build - just really want to think it through and design it so it works first time. This is probably going to be the slowest build in the world - will take a few months! I love the evlogix current control switch sold on that one guys! I want to model an Astro 3210 on a 24V setup limited to 250W and gear it to do ~20Mph on 27 speed 16in wheels. Don't laugh! i'm not taking a monster recumpence creation and turning it into a schoolgirl - I just like wearing a frock sometimes! You guys should try it get in touch with your feminine side! haha!

Thanks for your help and inspiration!

ron van sommeren · **Jun 9, 2011**

See

http://www.consult-g2.com/course.html

CHAPTER 1: MAGNETIC PRINCIPLES
1.1 Introduction
1.2 Magnetic circuits and the design equations
1.3 Sample calculation of magnetic flux design in a gap
1.4 The B-H curves of PM materials
1.5 Excursions of the operating points
1.6 Energy product and maximum energy product
1.7 Intrinsic and normal B-H curves
1.8 Magnetic forces on permeable materials
CHAPTER 2: MAGNETIC MATERIALS
2.1 Magnetically hard (PM) materials
2.2 Magnetically soft materials
CHAPTER 3: FLUX, RELUCTANCE AND PERMEANCE
3.1 Intuitive concept of flux
3.2 Reluctance and permeance
3.3 General formulation of reluctance
3.4 Roter's method
3.5 Numerical calculations of magnetic fields
3.5.1 Finite difference method
3.5.2 Finite element method
CHAPTER 4: ELECTROMAGNETICS
4.1 Force and emf generation
4.2 Transformer operation
4.3 Instruments of magnetics
CHAPTER 5: MAGNETIZING OF PERMANENT MAGNETS
5.1 Magnetizing requirements
5.2 Current vs. time in an ideal magnetizer
5.3 Real magnetizers
5.4 Optimization
5.5 Other considerations
5.6 Forces on conductors and coils
5.7 Winding patterns
CHAPTER 6: MOTOR DYNAMICS
6.1 Force production
6.1.1 Forces between a conductor and steel
6.2 Energy considerations
6.2.1 The force equation
6.3 Torque balance equation
6.3.1 Dynamic determination of torque
6.3.2 Torque development by 2 fields
CHAPTER 7: MOTOR DESIGN
7.1 Introduction
7.2 Overall dimensions
7.3 The magnetic circuit
7.4 Magnet performance
7.5 Design features
7.6 Motor winding
7.7 Winding connections
7.8 Motor characteristics
7.9 Loss calculation
7.10 Armature reaction and demagnetization
7.11 Acceleration
7.12 Designing with computers
CHAPTER 8: MANUFACTURING CONSIDERATIONS
8.1 Introduction
8.2 Laminations
8.2.1 Die punching
8.2.2 Chemical etching
8.2.3 Laser cutting
8.3 Stator stack
8.4 Winding
8.5 Magnet magnetization
8.6 Bearing assembly
CHAPTER 9: ELECTRONIC CONTROLLERS
9.1 Types of drives
9.2 Speed control
9.3 Sensorless control
CHAPTER 10: STEPPER MOTORS
10.2 Torque characteristics
10.3 Electromagnetic principles
10.4 Stepper design tips
CHAPTER ll: ACTUATORS
11.1.2 Basic principles
11.1.3 Shorted turn
11.1.4 Equivalent circuit
11.1.5 Static magnetic circuit
11.1.6 Coil construction
11.1.7 Improving linearity
11.1.8 Actuator dynamics
11.2 Solenoids
11.2.1 Introduction
11.2.2 First order force calculation
11.2.3 Idealized model
11.2.4 Bobbin and winding
11.2.5 Packing factor
11.2.6 Gap location
11.2.7 Plunger face shape
11.2.8 Remanence and sticking
11.2.9 The plunger-wall flux crossing region
11.2.10 Solenoid drive circuit consideration
11.2.11 Solenoids operating against springs
11.2.12 Constant force variable position solenoid
11.2.13 Solenoid actuation speed
11.2.14 Some other solenoid types
11.2.14.1 AC solenoids
11.2.14.2 Rotary solenoids
11.2.15 Testing of solenoids
11.3 Linear multiphase motors
11.4 Other actuators

jonescg · **Aug 7, 2009**

I noticed a post about "slow winds" and "fast winds" and I got to thinking, I should really make a post so the average punter can make sense of the slang. Shoot me down if this has already been done, but there is a lot of misleading crap out there about how electric motors work...

Lets say we have 5 kg of copper, and you can beat it into any sized wire you like. Use this wire to wind up say a 12 pole motor.

Using thinner wire, your 5 kg of copper can be wrapped around the armature 10 times per pole. Lets call this a ten turn motor.

Using thicker wire, your 5 kg of copper can only be wrapped around the armature 5 times per pole. This is a 5 turn motor.

The torque characteristics of these motors are going to be very different. The 10 turn motor is going to have a higher torque constant than the 5 turn motor - that is, more torque will be produced per amp of current. Torque constants are expressed in Nm per amp.

We also know that volts and amps are related, and torque and motor speed are related. So torque characteristics may also be expressed as voltage constants. In our case above, the 10 turn motor will have a lower voltage constant than the 5 turn motor. Voltage constants are usually expressed as rpm per volt. That is, the 10 turn motor will spin slower than the 5 turn motor per volt applied.

So when someone says "I prefer a slow wind" they are referring to a motor which has more turns of wire per kilogram of copper, and thus spin slower at a given voltage. At that same voltage, a "faster wind" will spin faster.

Miles · **Mar 16, 2007**

Good idea. There's a huge amount of rubbish about "high torque winds" etc..

jonescg said:
So torque characteristics may also be expressed as voltage constants. In our case above, the 10 turn motor will have a lower voltage constant than the 5 turn motor.

I think it's better to use the term velocity constant rather than voltage constant. Firstly, it's consistent with the expression of terms in the torque constant. Secondly, it doesn't equate to the true voltage constant (Ke in V/1000rpm) because of the voltage drop from the parasitic torque. Thirdly the abbreviation for volts is upper case V, which also adds to the confusion...

I also think Km should only be used for Nm/✓W and not as an alternative to Kt.

Anyone disagree?

You could argue that angular velocity should only be expressed in radians/sec.........

Drum · **Oct 9, 2014**

Hi All,

Here's a link to a Webinar about using Rare Earth magnets efficiently. It is available online until January 2015.

I do not know enough to judge how useful this will be to other members, but hopefully some may benefit from it. It is presented through "Globalspec" by Electron Energy Corporation.

Here's the link: http://click.email.globalspec.com/?qs=d3e9f51e6309a68626d10ce47902f8e0d44a2907667d1a69dbff22acfe24780f

and here's a copy / paste of the e-mail from Globalspec:

NOW ON-DEMAND

Available On-Demand Until

January 7, 2015

WEBINAR PRESENTER:

Dr. Jinfang Liu,

Chief Operating Officer

Lori Haley,

Manufacturing Engineer

Karla Takasumi,

Senior Applications Engineer

KEY TAKE-AWAYS:
• Understand the magnetic properties of rare earth magnets and learn how they impact magnetic circuit design and analysis
• Learn how to design using FEA to improve performance of magnet systems
• Case Study using FEA analysis of Halbach designs to increase magnetic flux density 40% without changing overall dimensions

________________________________________

Important!

System Requirements & Compatibility Check
• System Requirements — to ensure successful access on the day
of the webinar, test your system to see if it meets the system
requirements.

• Trouble Accessing the Webinar — please copy and paste the URL

below into your browser.

http://event.on24.com/r.htm?e=822688&s=1&k=45EC7C094AB108B5DE482A46AFE86BD7

• Sound/Volume — turn your speakers up to hear the audio.

You will not need to dial in.

________________________________________
ABOUT ELECTRON ENERGY CORPORATION:
EEC Magnets and Assemblies ITAR/DFARS Compliant

Superior magnetic properties, ultra-high temperature tolerance and excellent reliability make Electron Energy Corporation magnets ideal for motors, actuators and generators.

Founded in 1970, EEC is dedicated to improving rare earth magnet performance to meet the most technically demanding applications in aerospace, military, medical, electronics, and motion control markets. As world-renowned experts in material sciences, testing and 2-D/3-D Finite Element Analysis, our vertically integrated operation provides you with the full range of services to meet your magnetic needs.

________________________________________

Regards,

Dave

spinningmagnets · **Oct 9, 2014**

You could argue that angular velocity should only be expressed in radians/sec...

I am searching for the correct engineering term that would describe the speed of the magnets in a PMDC motor. It relates to the amps that the motor demands when bogged down, and three comparative examples to hopefully highlight what I am looking for are:

1) Small diameter direct drive hub in a 26-inch wheel (408?)...

2) Large diameter hub (Magic Pie?) in a smaller wheel (20-inch?)...

3) Hub-motor used as a non-hub with a high reduction to a small rear wheel.

I have come across the term "tangential magnet speed", but I regretfully didn't save the link. I am hoping to form a user-friendly term along the lines of the motors' "magnet speed per meter of wheel travel"

jpgey · **Jan 12, 2012**

Very usefull link, with interaction and phase schema, delta, star, sinus and sensorless, Stepper and BLDC Motors Animation

http://en.nanotec.com/support/tutorials/stepper-motor-and-bldc-motors-animation/

Kerrshay · **Oct 3, 2018**

These are well researched resources on how Motors work! Thanks for sharing.

HarryC · **Nov 25, 2019**

Hello,

Please can someone tell me the difference between a unipolar stepper motor and a bipolar stepper motor. I understand that Bipolar motors have a higher torque but can they be used in the same applications?

fechter · **Dec 31, 2006**

HarryC said:
Hello,
Please can someone tell me the difference between a unipolar stepper motor and a bipolar stepper motor. I understand that Bipolar motors have a higher torque but can they be used in the same applications?

Here is a pretty good explanation:

https://techexplorations.com/blog/a...e-between-unipolar-and-bipolar-stepper-motors

I don't see why either couldn't be used for a particular application but the drive circuit will be different.

HarryC · **Feb 4, 2020**

Unipolar Motors do not require the use of H-bridges, making it simpler to install and operate. According to this website: https://www.accu.co.uk/en/p/95-unipolar-stepper-motors-vs-bipolar-stepper-motors

However, Bipolar motors are generally have more torque and are more efficient than unipolar motors

This is another educational link: http://www.tigoe.com/pcomp/code/circuits/motors/stepper-motors/ this website says you can identify whether its a unipolar or bipolar motor by measuring the coil distance.

Green · **May 26, 2023**

fechter said:
Here's a very detailed and well illustrated tutorial on the basics of AC induction motors and brushed DC motors. You can learn a lot from this.
If you're not the techie type, ignore the mathematical formulas and just look at the pictures.
http://www.reliance.com/mtr/mtrthrmn.htm

Here's a resource for brushless motor theory for engineers:
时时彩软件2023-时时彩软件2023官方版下载.0-幸运彩app最新版本下载-幸运彩app下载软件安装-幸运彩app安卓版下载安装
　　所以说，发现《王者荣耀》的缺点容易，但是站在他们的角度分析思考问题并且给出行之有效的建议，却非常困难，如果一定要提出一个建议的话，那就是他们在社交化的道路当中，对于大数据能发挥的作用和数据挖掘的优势理解的还不够的深入，因为社交是分为熟人社交和陌生人社交的，熟人社交领域，微信、QQ做的已经够好了，他们的方式也确实是有效的，然而在陌生人社交领域，腾讯却还并没有一个非常成功的模式，我曾经写过一篇《今日头条产品分析报告》，在那篇报告里面，我看到的不仅仅是数据挖掘在新闻领域的成功运用，我还看到了在陌生人社交的领域，大数据同样有非常大的作用，而游戏，不正是陌生人社交的一个最好的地方之一吗。
www.drivetechinc.com
another nice one here:
http://ww1.microchip.com/downloads/en/AppNotes/00885a.pdf

A more basic explaination is here:
Brushless DC electric motor - Wikipedia
en.wikipedia.org

A nice animation of a brushless motor:
http://www.electricwheelscompany.co.uk/brushless_motor.html

To calculate speed, acceleration, current, and voltage, the famous 4QD calculator:
Motor Current Calculator - 4QD - Electric Motor Control
A JavaScript calculator that helps you estimate the likely motor current from first physical principles.
www.4qd.co.uk

another excellent simiulator to help evaluate how different motor, battery, and controller combinations will perform on an electric bike:
http://www.ebikes.ca/simulator/

A tutorial on motor calculations: http://tinyurl.com/323cjr

Hi Fetcher,

Seems like these are some good content to understand about motors as per the comments. Unfortunately, some of links are not working and not available. Could you please some other alternate links or videos which gives information as the above links. I will be really grateful.

evskunk · **Jun 17, 2023**

I have been reading APL's and HH's threads and strongly motivated to build an Axial motor. I have a basic question which seems to be almost assumed in the threads. How do we determine the number of turns required and AWG that need to be used? What is the math behind this?

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Friday, February 21, 2025

Mid-Drive or Hub Motor – Which Should I Choose?

Additional Resources

THE TYPES OF ELECTRIC MOTORS IN EBIKES

HUB MOTOR DESIGN

PERFORMANCE ATTRIBUTES OF HUB MOTORS

HUB MOTOR DESIGN TRADEOFFS

AGENCY CERTIFICATIONS

CONCLUSION

Friday, February 14, 2025

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Thursday, February 6, 2025

Powerful Bafang Rear Hub Motor – Safecastle

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Breeze Elite Bafang Rear Hub Motor Kit

How Motors Work - some educational links

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