The future is never certain. That’s for sure. (irony intended)
The future of electric motor technology is going to come from the electronics industry. That has been my position for some time. And I think its still true to a large extent. The improvements in control technology made possible through powerful processors like DSP’s and MCU’s have increased performance of a lot of major technologies. Old-school closed loop servo controls that used to keep track of things down to the millisecond, are now able to regulate in the microseconds. Control systems are now capable of coordinated motion that updates in the microsecond range.
Recent reductions in the cost of power electronics, FETs and IGBTs, the building blocks of AC inverters, brushless dc amplifiers, stepping motor controls, have all benefitted. This has lowered the payback threshold for AC inverters to 3 horsepower applications. Microstepping drives have benefitted from size and cost enhancement to the point where several manufacturers have successfully integrated the controls directly with the motor, a great way to improve total cost.
Falling prices and increasing performance of these technologies make controlling an electric motor a great application for a processor of your choice and embedded software. One interesting side effect is that the motor becomes software upgradeable as performance and efficiency gains become the domain of software algorithm programming.
Where this leads to is anybody’s guess. And if any readers have an opinion on the subject I would be glad to hear it. It seems a fascinating area to speculate on.
But the huge shift in materials cost over the last few years has changed the motor marketplace for the forseeable future. Rising steel and copper prices and falling magnet prices are all changes that were quite the opposite of what was expected. I think we all lived in the history of steel and copper being cheap and pricing being constant for quite some time.
Neodymium magnets have always been expensive, which I always thought was odd since neodymium is quite available. But falling prices have made Neodymium Iron Boron magnets a bargain, to the point where ac appliance motors smaller and more powerful by embedding the magnets in the rotor and eliminating some of the size and mass of the steel laminations and copper to achieve a certain power point.
This leads to a new branch of motor technology. We keep inventing new motor species every time we find a new solution to an old problem. Sometimes its just a lower cost solution. But the new Permanent Magnet AC motor, what we used to call the buried magnet motor, has finally made its place in the world. Sometimes called the Permanent Magnet Synchronous Motor, a term that is somewhat of a misnomer, the new motor adds magnets to the rotor of a standard ac motor allowing it to be started without the use of a unique starting algorithm. This differentiates the new motor from the brushless dc motor.
So is it all about the electronics? Yes, but not exclusively. When we do the cost equation for solving a motor and drive application, the cost landscape has changed. The answer we get today isn’t the same as the answer we got a couple of years ago.