INDUSTRIAL ELECTRONICS
PRINCIPLE OF
INDUCTION HEATING
WHAT IS INDUCTION HEATING ?
• In induction heating systems, an alternating current (AC) is passed
through a coil, generating a rapidly changing magnetic field. When a
metal object is placed within this field, eddy currents are induced in
the object.
• These currents flow against the resistivity of the material, producing
localized heat without direct contact.
• This efficient and precise heating technique is widely used in
applications such as metal hardening, brazing, soldering, and melting,
offering advantages like fast heating rates, energy efficiency, and clean
operation.
BLOCK DIAGRAM
PRINCIPLE OF INDUCTION
HEATING
The principle of induction heating can be explained with the help of :
• A Hypothetical Single-Phase Circuit
• Parallel RLC Circuit
A Hypothetical Single-Phase
Circuit
The principle of induction heating can be
explained with the help of a hypothetical
single-phase circuit, where the load
consists of a thick metal rod, which is
actually like a short circuit for the
secondary winding. As a result, heavy
current flows through the rod, which gets
heated up. With such a dead short circuit,
however, the secondary winding of the
transformer may get unduly heated and
thus damaged .
Parallel RLC Circuit
A parallel RLC circuit supplied by a
high-frequency, single- phase ac
voltage source inverter. The
inductance coil wound round the metal
rod acts like the primary of a
transformer with the metal rod
(workpiece) acting as the secondary;
consequently, circulating currents flow
through the metal rod, thereby heating
it. The performance of this circuit vis-
à-vis a circuit supplied by a current
source inverter is now examined in
detail
ADVANTAGES OF INDUCTION
HEATING
➢Fast and Efficient Heating: Heat is generated directly in the material, reducing
heat losses.
➢Precise and Controlled Heating: Temperature, heating rate, and heating zones
can be finely controlled.
➢Non-Contact Process: No physical contact between the coil and the
workpiece.
➢Clean and Safe: No open flame or combustion.
➢Repeatable and Automated: Easily integrated into automated systems.
➢Improved Product Quality: Minimizes oxidation and material distortion.
➢Energy Saving: Heat is localized to the target area, minimizing wasted energy.
APPLICATIONS OF INDUCTION
HEATING
✓ Metal Hardening
✓ Metal Melting and Forging
✓ Brazing and Soldering
✓ Heat Treating
✓ Shrink Fitting
✓ Welding
✓ Induction Cooking
✓ Semiconductor Industry
SUMMARY
Induction heating is a non-contact method of heating electrically
conductive materials using electromagnetic induction. When an
alternating current (AC) passes through a coil, it generates a changing
magnetic field. This field induces eddy currents in the nearby
conductive material. The resistance of the material to these currents
causes Joule heating, raising its temperature. In magnetic materials,
hysteresis losses also contribute to heating.
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