Mechanical Engineer Wants to Learn About Electronics

Hello renasis, you may subscribe to the free Gear Solutions Magazine. It is available both in print and digital copy. I have a friend (an Electrical Engineer) that is a subscriber to this magazine and he found it very informative and valuable from time to time. It might help you. Here is the link to where you can subscribe it: http://mathalino.tradepub.com/free/gstp/

RTFVerterra,

Thanks for the info. I will check it out.

-renasis

Check out http://www.allaboutcircuits.com. They have an excellent on-line book (downloadable) covering the basics of electronics.

Renasis,

Before you go off and pay tuition at DeVry or elsewhere -since you already have a degree in M.E. , you ought to check out the Openware Courses that you can obtain from M.I.T. and other Major Universities for free on the web.

For example, MIT offers free Openware audio/video courses entitled:

6.002 - Circuits and Electronics (Spring 2006)

6.101- Introductory Analog Electronics Lab (Spring 2007)

6.111- Introductory Digital System Lab ( Spring 2006)

and the latter two courses will give you some hands-on application knowledge.

All the Best,

Jim (Ph.D. in E.E.)

I attended a free seminar from ST Electronics and found it very informative. They make a bunch of advanced controller chips for motor control. The seminar had a lot of theory in a short time. If you can catch one of these I know you'll be glad You did. They have great app notes too.

http://www.st.com/motor control also http://www.st.com.stm32 They sell evaluation boards also.

I am an electronic engineer and have been working with the designs of VFD (Variable Frequency Drives) for Brushless DC motors, Steppers and Switched Reluctance types. I find the most interesting is the SR Motors. They are crude, simple and cheap to build , but difficult to drive, because of the construction and technology of the pole faces. They have some very undesirable attributes that would be challenging for a person in your field. There has been a lot of papers written on the subject but I find little done.

There was one experience where I was looking for a quick path to market for a 2.5 to 4 Hp Switched Reluctance motor drive. This motor was to replace the 2.5 Hp gas motor in a trike type "around town" vehicle. I thought I could go and buy a VFD Variable Freq. Drive)for a 3 phase SR motor. Boy was I wrong. I had crowds of people coming out of the woodwork wanting tens of thousands to $160,000 dollars for the development of a drive system, but no one had a system that I could buy and wire up and run! --Except for one company that wanted over $3500.00 for the motor drive. Thats more money than the sales price of the vehicle.

Anyway -- Back to the subject of you interest in the motor drive electronics. I have a lot of information and sources of some good Motor drive electronics. The electronics is not all that complicated, and I think you will find it a fun and challenging experience. I have some crazy ideas that you may find interesting. I'm not so sure this forum would be the right place to get into all the details, but if you're interest is high, I would be more than willing to spend the time to dump a lot of technical stuff on you. There is a lot of very good info on how these systems work.

My impression, is that there is a huge market for an inexpensive SR motor drive system that would include the Motor and compatible drive for that particular motor. In my research I can explain the whys later. The SR motor's is very dependant on the mechanical design for maximum performance and minimizing the undesirable features of this type of motor.

I guess me first question is --What kind of motor electronics sparks your interest. --or-- What type of motors do you, or are you designing. Like fractional horse power or the big stuff?

Whatever you do, make sure you actually build some circuits on some form of prototyping board. There's nothing quite so educational as placing a diode backwards, or misreading the color code on a resistor, then tracing to find out why there was smoke when you connected it...

I found it quite interesting to build driver circuits for small stepper motors, like those removed from dead printers or floppy drives.

I concur. You will learn more with a good reference paper and 10 hours on the bench than a semester in school.

Wow, thanks for all the replies, very informative.

Mooseman to answer your question, I am interested in and work with fractional horsepower brushless DC motors. Given a motor application I would like to be know what electronic equipment is needed and how to setup it up.

Thanks,

-renasis

I have not worked with small motors, but I assume that it is similar to larger motors. Are you concerned with a test set-up to test the performance of your designs? If so, the classic test set-up is a test bed that would consist if a test bed plate. Depending on your budget, it can be a Optical test plate (from Edmond Scientific) type of place. the one I used for a client was about $400.00 or, an aluminum (or steel) plate 1/4"Thk. with 1/4" holes ,drilled and tapped every inch. Your plate perhaps 24"x18" big enough to mount motor, generator and torque transducer. You will also need a set of various shims for aligning shafts. (from McMaster Carr or machine supply warehouse) a set of power resistors to load a motor generator with various power settings. I built a PWM dynamic load so I wouldn't have to be changing resistors. The idea is to run your motor, driving another BLCD (most efficient you can find)as a generator. load this generator with a resistor and you get the V x A = Power. It helps to also have a dynamic torque transducer between the two. That is the basic set-up. Whether you get the accuracies you need in another question. The system will give you a relative idea of your performance compared to your competition or what is on the market for similar motors. I'm not so sure if this is the way you would test fractional horsepower devices. again -no experience with small motors.

There are other ways to test motors with hydro pumps or dynos. Messy, they may suit your needs better. I found this to be a fairly expensive method but, if you have the bucks, it may be the way to go.

The disadvantage of the motor generator system is the very low speed torque measurements. There is a way to generate EDDY Effect load that will do the job. If you get into this we can talk about the method. --simple rotating magnets.

If you are still interested in my experience with this , I will can send you some old sketches I have made of the test set-up.

I am still concerned about this approach for fractional HP motors. you are working with very small numbers. To me, that would indicate difficult measurements.

I'm not sure how to send this data and drawings to you without a E-Mail adderess.

Go to a public college and get an AA degree not to expensive and you can go for your BSEE if you like it.