Permanent Magnet Generators: Price vs. RPM
Permanent magnet alternators can be operated at different speeds. Thus there are alternators working at low rpm and others at high rpm. This feature is suitable when these alternators have applications in various fields like wind turbines, hydro-kinetic energy and other renewable energy devices. For example, vertical axis permanent magnet wind generators require very low rpm for direct drive applications. But there is a compensating factor when reducing the speed, which is price.
The price of an alternator is inversely proportional to the rpm of the permanent magnet alternator. As we go on reducing the rpm of the alternator keeping the power output fixed, the price increases. As the speed decreases, the alternator becomes physically larger in size. This is because reducing the speed increases the material consumption of the device. The device becomes bigger because of overall volume increase. The diameter or the length has to be increased since total flux needs to be increased at lower rpm to match the conductors. More copper and magnets are required. The type of permanent magnet used is NdFeB which is driving cost factor in permanent magnet alternators.
PMGL’s expertise is to match the customer’s alternator speed and power requirements at the best efficiency.
