Effect of Supply Voltage
a.As the applied as voltage is increased hysteresis loss increases.
b.Eddy current losses are given by
W e α f2 t2 B2 m
Where Bm = maximum flux density in wb /m2
If supply voltage is increased flux due to eddy current will increase hence the power loss will increase. It means the production of the surface heat will be more if the applied voltage is increased.
Induction heating is much superior to electric resistance heating. In electric resistance heating the next of heat transfer is very less ( l approx 100 w/sq cm or so). However in induction heating the rate of heat transfer can be as high as 10000w/sq cm. Because of high rate of heating the rate of production of goods can be very high moreover the life of the living of a high frequency furnace is more than double that of power frequency furnace. Shows a block diagram of induction heating . this complete system consist of AC- DC converter filter and inverter. AC - DC converter is used to convert 50Hz AC to DC filter is used to improve the wave shape and inverter is used to give high frequency AC.
Induction cooking is one of the important application induction heating. An electric or gas cooking has very poor efficiency because appreciable amount of heat is lost to the surroundings induction cooking avoids this wastage of heat. Figure shown a block diagram of inaction cooking rectifiers and filters are used to converts 50 Hz AC to smoothened DC an inverter converts this DC into very high frequency AC which is then fed to the induction coil. The eddy currents in the metal pan heat the pan and do the cooking.