Submitted by: DAVID SMITH

Refrigerators have become essential appliances in society for the preservation of food and beverages. The quality of life for people has been greatly enhanced with the availability of affordable refrigerators for homes. Most household refrigerators utilize the vapor compression cycle with a circulating refrigerant used to cool the refrigerator compartment. Household refrigerators originally used an on/off controlled, constant-speed, single-phase induction motor to drive the compressor. The poor efficiency of this approach made the refrigerator one of the highest power consumption appliances in the home. In order to improve the efficiency, modern refrigerators with the Energy star rating utilize variable-speed, three-phase induction motor drives. Current models that are Energy Star qualified use 50 percent less energy than the average models made in 1974.

The variable speed drive to the induction motor is provided using the six IGBTs in the inverter stage. The authors state: The total energy savings was about 40%. The system is very quiet and maintains a constant temperature within 0.1 degree Celsius which improves the quality and shelf life of food stored in the refrigerator. Many companies have optimized IGBTs for use in refrigerator compressor drives due to the large market opportunity. Some companies have developed intelligent power modules, which combine the IGBTs, fly-back rectifiers, and the drive circuits into a single module. This provides a very compact and low cost motor drive option that can be easily adopted for the manufacturing of refrigerators.

The method of inflaming an electrically conductive object (normally a metal) using an electromagnetic induction is called Induction Heating (IH). The object is heated by eddy current or Foucault currents. Induction heating (IH) is a familiar technology and very often used for cooking appliances.

A notable volume of power is dissipated by the IGBTs used in induction heating cooking applications when the application is operated at high power levels. For this reason, big heat sinks are employed generally in order to confine the junction temperature of the IGBTs from increasing more than its recommended specification value.

An induction coil in the cook-top inflames iron bottom of cookware in induction cooking using rotational magnetic induction. Only ferrous pans can be used perfectly in induction cooking, others such as: aluminum pans, copper-bottomed pans etc are not compatible usually. The heat inclined to the bottom is transferred to the food via (metal surface) conduction. Each and every IH cooking appliance functions using the electromagnetic induction phenomenon: an AC current flowing through a circuit (ex: the heating coil) yields an inconsistent magnetic flux, thus causing eddy currents to occur in a secondary circuit (i.e. the load to be heated).

Advantages of induction cookers comprise potency, protection (the induction cook-top is not het itself) and fastness. Both permanently installed and portable induction cookers are available in the market. You have the option to choose between fixed and portable induction cookers according to your need.

Because of using large heat sinks to meet the maximum junction temperature requirement, the aggregate cost of the IH cookers raises. Despite their higher initiatory cost compared to gas or electric cooking appliances and the need for special pans made of ferromagnetic materials, IH cooking appliances present benefits such as high energy efficiency, fast and safe cooking, and easy to clean cooktops that have made them popular around the world. The market for induction heating applications will grow tremendously, if production costs can be reduced, and more efficient induction heating cookers can be developed.

About the Author: David Smith, Senior Vice President of

USComponent.com

, an IGBT power transistor module distributor since 2001.

Source:

isnare.com

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