Electrothermics

I.3. Power supply

The power supply technology depends strongly on the heating frequency. The main power supply technologies are the following:

– Direct link to the network. In this case, the inductor is directly linked to the network transformer that regulates current and power.

– Thyristor converters with frequencies between 100 Hz and 10 kHz.

– Transistor converters with frequencies of up to 2 MHz.

– Triode converters with frequencies of up to 5 MHz.

In an application of induction heating, the impedance of charge is often strongly inductive. We then use an impedance matching unit to improve the power factor and to obtain a nearly resistive charge with respect to the generator.

The efficiency of transistor generators is of the order of 90%. However, triode generators have an efficiency of less than 70% due to the losses in the triode’s anode.