Looks like I was mistaken about one thing recently, and its probably not the only thing. The new clothes washer we got to replace our failing machine does not use a switched reluctance drive. Its an intelligent inverter drive with a standard AC motor.
As somewhat of a technology freak, this comes as quite a surprise. I had been involved in a lot of advanced motor R&D during the late 1990’s. Switched reluctance was touted as the next big thing in motor technology. In truth, its a permanent magnet machine that uses high energy magnets (neodymium iron boron), which are expensive. So in the effort to advance technology, we never escape the cost impact.
Where cost is not constrained, anything is possible. Men on the moon, robots on Mars, telescopes in space that see the edge of the universe. Superconducting electromagnets that contain the power the of sun, particle accelerators that approach the speed of light. Almost anything you can think of.
But in normal everyday events, everything is cost constrained. So when customers and engineers ask if something is possible, there is always the follow on question, “How much is it going to cost?” We need to remember to answer that question explicitly, even if its not asked.
As it turns out in the washing machine, it is a lot cheaper to change the mechanical transmission into a simple belt and pulley system. By using a large reduction ratio to give the small ac motor the needed mechanical advantage and adding an intelligent inverter to the standard ac motor the new drive train is transmissionless and lower cost. This new system even includes extra sensors to detect proper motion from the tub (I think its an inductive proximity device tied to a counter on the controller that tells how fast the tub is moving). This machine cost a lot less than its predecessor, runs a lot quieter, and uses less energy over a year’s time.
Yes, the cost of the final solution is lower, and the overall machine performance is better. But the lesson that is most significant from this example is; the biggest improvements in energy reduction are not the result of trying to squeeze the last percentage point of efficiency from the motor. The biggest reduction in energy cost comes from a better mechatronic solution, leveraging the mechanical, electrical and control system together and getting the best overall result.
Coincidentally, this is also the best return on investment for the manufacturer and strengthens GE’s position as an appliance maker and employer. But the same benefits are available to everyone in manufacturing.
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