Principle of electromagnetic heater:

An electromagnetic heater is a device that converts electrical energy into heat using the principle of electromagnetic induction. The electromagnetic controller converts 220V/380V, 50/60Hz AC power into DC through a rectifying circuit, then transforms the DC into a high-frequency current of 10-40kHz via the control circuit. As the current flows through the coil, it generates a varying alternating magnetic field. When the alternating magnetic flux lines within the field pass through ferromagnetic materials (such as iron, cobalt, and nickel), numerous small eddy currents are induced within the metal, causing the material to heat up rapidly, thereby achieving the purpose of heating the metal.

Inverters are the core components of high-frequency electromagnetic heaters, utilizing the on-off action of power semiconductor devices to convert AC power sources to another frequency of electrical energy control devices. The inverters currently in use mainly employ AC-DC-AC conversion, first converting the AC power source to DC power through a rectifier, and then converting the DC power into an AC power source that can control both frequency and voltage to supply the motor. The circuit of the inverter generally consists of four parts: rectification, intermediate DC section, inversion, and control. The rectification section is a three-phase bridge-type uncontrolled rectifier, the inversion section is a three-phase bridge-type IGBT inverter with PWM waveform output, and the intermediate DC section includes filtering, DC energy storage, and reactive power buffering.