Induction heating is based on two basic physical phenomena: Faraday electromagnetic induction and the Joule effect.
When alternating current I1 passes through the coil, an alternating magnetic field is established in the space around the coil. Induction electromotive force E is generated in the metal billet in the alternating magnetic field. Faraday’s law of electromagnetic induction determines:
e(t) = -n(dΦ)/(dt)
The negative sign in formula (1) indicates that the direction of the induced ELECTROmotive force is opposite to the direction of the rate of change of magnetic flux.
φ=φmsinωt， The angular frequencyω=2πf， Then the effective value of the induced electromotive force is:
Treat the billet as a closed loop with only one turn. When the induced electromotive force is generated, the loop produces an alternating loop of its own circulation, eddy current I2. Induction heating is the use of the heat generated by eddy currents to heat metal billets.