Electric motors are still one of the most difficult technologies to apply correctly. The problem is that electric motors are literally “the workhorse of industry”, and they are used in a wide range of applications. Each application, each statement of work that is being designed presents unique requirements.
The problem is bounded by the mechanical work to be done. This sets the minimum performance required for the product or mechanism to be successful. Primarily the qualification of a motor for a specific task is based on its speed and torque. There is a laundry list of other attributes that come after that must all be considered to get the best overall match.
Sometimes the quality of the product can be enhanced by the electric motor technology. Air handling systems can be highly differentiated by how quiet they are, regardless if its a ceiling fan, blower or convection oven fan. The latest generation of vacuums from Dyson share a custom high RPM brushless motor to give the product light weight, high vacuum and high electrical efficiency. All important attributes that are directly derived from the motor technology.
Commercially, it is only cost effective to custom design an electric motor and drive electronics if there are large numbers involved. Depending on the price point of the application this can be anywhere in the 2,000 to 10,000 units per year range. The cost of embedded motor control technology and power electronics have all dropped dramatically making this aspect more attractive, but there is usually a certain amount of firmware development required, and the cost can be unpredictable.
In addition, the tooling to create a new electric motor can be expensive since laminations will have to be laser cut or stamped, stacked and the wire of the stator wound in the stator slots. Permanent magnets can be expensive, but fortunately there are resources in the US with extensive experience to help develop new motor designs.
In the world of industrial machinery there are very few situations where the unit volumes are high enough to merit custom design. So the machinery builder is left with a very difficult task, survey all the existing off-the-shelf motor vendors and try and get a good match between what the application requires and what is cost effective from existing suppliers. This leads to the whole value chain of modified motors which tend to be very expensive.
More next week.