Energy Saving in Evaporative Coolers using Permanent Magnet Brushless Motors

Due to low cost, evaporative coolers are used in most of the central regions and in the warm and dry climate of Iran and are considered as one of the major consumers of electrical power. Most evaporative coolers use single-phase induction motors by connecting directly to the power grid. But their eefficiency is very low, and their replacement with high efficiency electric motors is considered by government bodies. Today, the use of permanent magnet brushless motors has been considered in many industrial and home applications. In this paper, the details of using the brushless motors in the application of the evaporative cooler are presented and the requirements and standards for designing and manufacturing the brushless motor and its drive are stated. A 0.5 hp brushless motor and its drive are designed and built. This motor is tested by a dynamometer and standard testing equipment. Also, the 5000 m3/h evaporative cooler equipped with this brushless motor is tested in the reference laboratory. The results obtained in both tests are compared with single-phase induction motor test results. The results demonstrate an increase of at least 60% energy consumption compared to evaporative coolers equipped to single-phase induction motors. Also, the economic considerations and extra cost of brushless motors and other technical considerations are discussed in this article. The results indicate that the use of brushless motors in this application can be a huge step in saving energy, protecting the environment and reducing the problems caused by electricity consumption in the country.