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# I Want to Learn How to Design an Induction Motor

## I Want to Learn How to Design an Induction Motor

(OP)
Hello,

Basically I went to school for engineering. I am well versed in basic physics, have some experience with circuit design, understand the concepts of brushless motor design and control with three phase bridges. Now I want to learn how to design induction motors and controllers of various sizes and power levels. Where can I learn the basics, the required constraints to design such motors and methods of simulation? Are there any good books? Resources? What would you recommend a beginner who wanted to learn how to design induction motors and controllers to do? Thanks for the help in advance!

Regards,
Bkhan

### RE: I Want to Learn How to Design an Induction Motor

Get a motor and tear it down -slowly- noting and remembering every detail.

Read up, on the web, about how the type motor you just tore apart actually works.

Find your local motor shop and explain that you want to learn how motors are made and volunteer to help them rewind some motors.

You'll be way ahead of the curve by the time you've helped rewind a few motors.

Keith Cress
kcress - http://www.flaminsystems.com

### RE: I Want to Learn How to Design an Induction Motor

Rotors are interesting. The motor characteristics are influenced by both the resistance of the squirrel cage winding embedded in the rotor and the depth that the winding is from the surface of the rotor.
Here's an excerpt from the Cowern Papers:
DESIGN
The design letter is an indication of the shape of the torque speed curve. Figure 1
shows the typical shape of the most commonly used design letters. They are A, B, C,
and D. Design B is the standard industrial duty motor which has reasonable starting
torque with moderate starting current and good
overall performance for most industrial
applications. Design C is used for hard to start
loads and is specifically designed to have high
starting torque. Design D is the so-called high slip
motor which tends to have very high starting
torque but has high slip RPM at full load torque. In
some respects, this motor can be said to have a
“spongy” characteristic when loads are changing.
Design D motors are particularly suited for low
speed, punch press applications and hoist and
elevator applications. Generally, the efficiency of
Design D motors at full load is rather poor and
thus they are normally used on those applications
where the torque characteristics are of primary
importance. Design A motors are not commonly
specified but specialized motors used on injection
molding applications have characteristics similar to
Design A. The most important characteristic of
Design A is the high pullout torque.

Take a look at the Cowern Papers. You will find the torque curves to accompany the description of the different designs.
COWERN PAPERS
The squirrel cage winding is often cast aluminum in smaller motors and cannot be inspected without destroying the rotor.
Study the effect of varying resistance in the rotor circuit of a wound rotor motor to get some idea of the importance of the selection of the proper rotor resistance.
There is one design called a double squirrel cage. The squirrel cage winding has figure 8 shape. At lower speeds (high slip and high rotor frequency) most of the torque is generated by the portion of the winding closest to the surface.
At normal running speed (low slip and low rotor frequency) the deeper part of the winding contributes more of the torque.
Designing from scratch? The best information is probably proprietary. Go to work for one of the manufacturers and spend 10 or 15 years working your way up to the design department.

Bill
--------------------
"Why not the best?"
Jimmy Carter

### RE: I Want to Learn How to Design an Induction Motor

The text "Design of Rotating Electrical Machines", by Jokinen, et. al., will quite literally give you all the information you will ever require in the design of an induction motor.

### RE: I Want to Learn How to Design an Induction Motor

1. You can go ahead and finalise the deign requirements.
2. Decide the motor specification based on design requirement. Like torque speed curve, power requirement etc.
3. try to perform some fundamental calculation on what will be the excitations required and frequency.
4. calculate the motor dimensions like Air-gap, Stator OD and Stator ID etc
5. calculate the conductor area based on current density etc
6. Try to calculate the overhang and winding resistance.
7. Model the motor and run a Electromagnetic FEA with it and Iterate after post processing.

There are multiple sub steps to all above and different strategy is followed by different people. Its very interesting and artistic science. Above mentioned steps are for Electromagnetic FEA and there are tons of multiphysics like thermal, acoustic, Mechanical pending if you are considering a full motor design.

Regards,

### RE: I Want to Learn How to Design an Induction Motor

I have recommended this book before, and it may be suitable to your needs: Electric Motors and Drives, by Austin Hughes.
Excellent introduction and plenty of details, with enough math to leave an engineer with avenues to follow for future learning, but not too academic.

STF

### RE: I Want to Learn How to Design an Induction Motor

I think the basic knowledge is important. Firstly, find information online and learn it well. After knowing information, then you can start praticing by dealing with real motor like disassembling it carefully. Through tearing it, you will use the knowledge of your basic information. Or, you can just directly find a teacher who can teach you because i think learning by yourself it boring and difficult.

### RE: I Want to Learn How to Design an Induction Motor

Good advice by all. I'll add a vote for the particulular textbook mentioned by ZeroSeq.

Unfortunately the request is ridiculously broad and vague. Title "design induction motors", then "motors and controllers". And op hasn't been back since September.

=====================================
(2B)+(2B)' ?

### RE: I Want to Learn How to Design an Induction Motor

We get similar demands on a daily basis.
Usually, they are looking for a "magic" formula for motor design.
But, actually, asking such a questions helps us to evaluate the degree of their knowledge.
Recently, one of them found a brilliant way to replace the wire of 1 mm diameter with two wires of 0,5 mm. He said, will be easier to do.

Tech Support in Motor Repair and Winding Design

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