IGBT in Washing Machine Agitator
Electric automatic washing machines are now common in homes for the cleaning of daily household laundry. Washing machines were developed to eliminate the drudgery of scrubbing and rubbing to remove dirt from clothes. Electric washing machines were advertised and discussed in newspapers as early as 1904. The first automatic washing machine was introduced by Bendix in 1937. Sixty percent of the 25 Million wired homes in the United States had an electric washing machine by 1940. The annual sales for washing machines have grown to more than 58 million units worldwide by 2003. Many of these units are front loaders. Early automatic washing machines utilized mechanical means for making any changes in impeller/drum speed. Since the 1970s, electronic control of motor speed has become a common feature of most washing machines. Modern automatic washing machines provide many sophisticated features to handle the safe cleaning of a wide range of fabrics with a variety of soil removal requirements. The soil removal in an automatic electric washing machine is performed by a process of agitation of the clothes. The agitator is controlled using IGBT-based motor control modules. The direction of rotation of the motor and its speed can be regulated by using the power delivered via the IGBTs. Inverter control with IGBTs reduces wash/spin noise and vibration, and enables adjustment of the amount of water and motor torque to suit the washing load.