Basics of Induction Heating
October 09, 2022
How Induction Heating Works
The induction generator generates alternating current, the alternating current generates alternating magnetic field, the conductor in the alternating magnetic field induces eddy current, and the eddy current flows on the surface of the conductor to generate heat energy to achieve the purpose of heating.
Characteristics of Induced Current
Skin effect: When an alternating current passes through a conductor, the current distribution along the conductor cross-section is uneven, and the maximum current density appears on the surface layer of the conductor. This phenomenon of current accumulation is called the skin effect.
Proximity Effect: When two conductors carrying alternating current are very close, the currents in the two conductors are redistributed under mutual influence. When the currents flowing in the two conductors are in opposite directions, the maximum current density appears on the inside of the conductor; when the currents flowing in the two conductors are in the same direction, the maximum current density appears on the outside of the conductor, which is called the proximity effect.
Ring effect: When alternating current is passed through a toroidal coil, the maximum current density appears on the inner side of the coil conductor. This phenomenon is called the ring effect.
Induction Generator/Power Supply is a device that comprehensively utilizes these three effects. A metal workpiece is placed in the induction coil, and an alternating voltage is applied to both ends of the induction coil to generate an alternating current, and an induced current is generated in the workpiece. The two currents are in opposite directions, and the situation is similar to that of two parallel busbars flowing in opposite directions. When the current and the induced current are close to each other, the coil and the workpiece exhibit a proximity effect, the current is concentrated on the inner surface of the coil and the current is concentrated on the outer surface of the workpiece. At this time, the coil itself shows a ring effect, and the workpiece itself shows a skin effect.
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