An induction heating power supply is a device that generates a high-frequency electromagnetic field and transmits it to a heater to produce current, thereby heating the heating medium.
Induction heating power supplies are widely used in hot working and heat treatment industries such as metal smelting, welding, pipe bending, and surface hardening. Different workpieces and processes require different power supply operating frequencies and output power.
The rectifier uses an uncontrolled three-phase full-bridge rectifier circuit. The filter uses two electrolytic capacitors C1 and C2 connected in series to reduce the voltage across a single capacitor. R2 and R3 serve as voltage equalization resistors. R1 is a current-limiting resistor. When the system is powered on, since the voltage across the capacitor is zero, the current will be very large when the capacitor is initially charged. Adding the current-limiting resistor R1 reduces the current from being too large. When the voltage across the capacitor reaches a certain value, the AC contactor K1 closes, short-circuiting the current-limiting resistor. The system can then operate normally. The inverter uses a single-phase inverter bridge connected to a series resonant circuit via a transformer. Two sets of IGBTs with alternating single-phase angles are used to convert a constant DC voltage into a 10Hz-10kHz square wave voltage output to the load. The operating waveform is shown in Figure 2. C3 and C4 are non-inductive absorption capacitors used to suppress surge voltage across the IGBTs.