Motors and Electronics

I have been involved in the motors and controls industry for quite some time.  Most recently, I worked for a company exploring the possibilities that new generations of RISC based microcontrollers offer for lower cost and improved performance motor applications. This effort has caused me to review all the major motor segments, DC, AC, Brushless and stepping motor, to re-examine my assumptions about what goes on and what brings us to where we are today.

Microcontrollers

Each motor family has it’s own properties due to the basic physics of the motor’s design.  DC motors which were first proposed by Faraday, actually evolved into workable machines, but electric power was not commonly available.  DC motors are intrinsically variable speed, all you have to do is vary the voltage.

AC motors which came later, proved to be more versatile when AC power distribution became widespread.  AC motors are constant speed and require no control, just a switch to turn them on and off.  As a result of the simplicity of the motor’s construction and implementation, the are very popular and found in lots of applications.

But for every application of a standard motor, there are dozens of applications where there is a need for something a little different.  And oddly, the more rules that we try to apply to how things work in the motor industry, the more exceptions there are to deal with.  The Small Motor Manufacturers Association has a motor family tree with 60+ categories.  And we keep coming up with new ones.

But the really strange thing that keeps coming up is the fact that motor manufacturers are really mechanically oriented.  Motors are machines that convert electricity to mechanical power.  So it makes sense to be focused on how much starting torque there is, what happens the load is stalled and things of that nature.

Ironically, the mechanical focus on motors is often to the exclusion of the control electronics.  Nowadays, all variable speed motors require some type of electronic control, from the variable frequency AC drive to the advanced brushless DC drive.   So for the most part, you buy a motor from one company and controls from another company.  Of course, in the modern marketing era, a lot of companies source the product they are missing and private label it.  But the real expertise may be somewhat harder to get at.

And there’s nothing wrong with this situation.  I just think it’s odd.  Clearly it’s difficult to master two different fields of engineering.  And from the standpoint of the technical competency itself, there would seem to be little in common between power electronics and the electromechanical issues of motor manufacturing.  But there is something of an imperative in the case of electrically controlled motors.  The problem being that the performance of the motor is closely linked to the electronics.

Variable frequency drive suppliers are more apt to be in the motor business, as Reliance, Baldor and some others are.  But in general, motor suppliers and drive electronics suppliers are two completely different activities.  As I have reviewed many of the large market applications, I believe there are opportunities for collaboration that will offer significant improvements in sizem weight, performance and economic opportunities for for cost reduction that would provide adequate incentive for those willing to work toward common goals.