Electromagnetic heating(electromagnetic heater) is an energy conversion process that uses the principle of electromagnetic induction to convert electric energy into heat energy. The rectifier circuit converts the 50 / 60Hz AC voltage into DC voltage, and then converts the DC voltage into a high-frequency voltage with a frequency of 20 ~ 40KHz through the power control circuit. When the high-speed changing AC current passes through the coil, the coil will produce a high-speed changing magnetic field, When the alternating magnetic force line in the magnetic field passes through the metal pipeline (magnetic and conductive materials), countless small vortices are generated in the pipe wall, which makes the pipe wall of the oil pipeline heat itself and exchange heat with the crude oil, so as to achieve the purpose of heating the crude oil.
Frequency converter(electromagnetic heater) is the core component of high-frequency electromagnetic heater. It is an electric energy control device that uses the on-off function of power semiconductor devices to convert power frequency power supply to another frequency. At present, the frequency converter mainly adopts AC DC AC mode. First, the power frequency AC power supply is converted into DC power supply through rectifier, and then the DC power supply is converted into AC power supply with controllable frequency and voltage to supply the motor. The circuit of frequency converter is generally composed of rectifier, intermediate DC link, inverter and control. The rectifier part is a three-phase bridge uncontrollable rectifier, the inverter part is an IGBT three-phase bridge inverter and the output is PWM waveform, and the middle DC link is filtering, DC energy storage and buffered reactive power
