New-Tech Europe | November 2016 | Digital edition

efficiency. In applications where more dynamic control is needed, the use of PMSM makes more sense. Then in some applications, where the cost is critical and factors such as weight-to-torque ratio and robustness are needed, the use of SRMs has been seen. Another classic industrial ACIM application is large HP (>15 HP) compressors. Here SyncRM motors have started to appear, as they have a very similar structure to ACIMs, including the same stator design with a different rotor. However, for the same frame size, you can increase the torque and efficiency, or reduce the frame size. Then there are the applications where there haven’t been any motors, such as under the hood of a car. Here, the electrical motor is being used to replace the mechanical serpentine belt, increasing efficiency, as the load can come and go with motors, while with the belt it is always there even though it isn’t needed. These days, everything counts when it comes to efficiency and fuel economy. Here the trend has been to move from belt to BLDC motor to PMSM. Another application in cars that is utilizing electric motors is drive by wire. Here, for example, SRMs are being used to drive the hydraulic pumps in the brakes. The high-speed capability of the SRM can build up pressure quickly, to allow for fast break response. Another very different application space where the use of electrically commutated motors has had a big impact is battery-operated tools and appliances. With the improvements in battery technologies, such as lithium-ion, we can now have vacuum cleaners and power tools utilizing the efficiency of BLDC motors. Initially, these applications primarily used

Figure 1: Electric Motors for Improved Fuel Efficiency

Figure 2a: Synchronous motor drive circuit

Figure 2b: SRM Drive Circuit

brushed DC motors, but there was a limitation on speed and torque. The higher power/torque density of BLDC motors allows for reasonable weight, longevity and performance that is close to matching the wired

version. In home appliances, such as washing machines, refrigerators, dishwashers, air conditioners, etc., the primary workhorse, just as in the industrial space, has been the

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