Introduction to the internal structure and working principle of high frequency induction heating machine

The internal structure of high frequency induction heating machine:

At present, the main structures of high-frequency heating power sources on the market are rectifier circuits, filter circuits and inverter circuits. The load of high-frequency heating is the induction coil and the heated workpiece, which can be equivalent to an inductor and a resistor in series, and the load is inductive.

In actual use, in order to improve the power factor and the output power of the inverter, the method of adding a compensation capacitor is generally used to make the compensated load resonate at the operating frequency of the power supply.

The working principle of high frequency induction heating machine:

The thermal sensing conductors of high-frequency induction heaters change their resistivity and permeability when they are heated, especially around the Curie point. The frequency of the power supply varies with the load, so induction heating power supplies.

In the further subdivision process, we can divide the high-frequency heating power supply currently on the market into two types according to the compensation form of the body, namely parallel resonance type and series resonance type. The inverter used in the working process of the parallel resonant heating power supply is a parallel resonant inverter, and its load is a parallel resonant load.

Usually a current source is required for power supply. In high frequency heating, the current source is usually composed of a rectifier plus a large inductor. Due to the large inductance value, it can be approximated that the current at the input terminal of the inverter is fixed.

The alternating square wave current can be obtained at the output of the inverter by turning on and off the switching devices on the inverter alternately. The current amplitude depends on the current value at the input of the inverter, and the frequency depends on the switching device. operating frequency.

In induction heating, the voltage source usually consists of a rectifier plus a large capacitor. Due to the large capacitance value, it can be approximated that the voltage at the input terminal of the inverter is fixed. By alternately turning on and off the switching devices on the inverter, an alternating square wave voltage can be obtained at the output of the inverter. The voltage amplitude depends on the voltage at the input of the inverter, and the frequency depends on the switching of the device. frequency.