Monday, February 06, 2017

Induction Heating - Cooker Project

Single plate induction cooker demonstration board  Uses ST7LITE09 and STGW40NC60WD (40 A, W series).

The design is entirely controlled by a simple ST7FLITE09Y0 8-bit microcontroller, which  provides the PWM driving signals, communicates information to the user interface, and  drives the fan and relay control to the plate feedback.

With Single Voltage Flash Memory, Data Eeprom, Adc, Timers, Spi Active - ST7LITE09Y0 8-Bit Mcu

Induction Heating - Cooker Project

A single plate induction cooker with the ST7FLITE09Y0  PDF - Excerpt From Application Note above AN2383 Application note -

Put simply, an induction cooking element (what on a gas stove would be called a "burner") is a special kind of transformer. When a good-sized piece of magnetically conducting material such as, for example, a cast-iron frying pan, is placed in the magnetic field created by the cooking element, the field transfers ("induces") energy into the metal. That transferred energy causes the metal - the cooking vessel - to become hot.

By controlling the intensity of the magnetic field, we can control the amount of heat being generated in the cooking vessel and we can change that amount instantaneously.

Induction cooking functions based on the principle of the series L-C resonant circuit, where the inductance L is the cooking element itself. By changing the switching frequency of the high voltage half-bridge driver, the alternating current flowing through the cooking element changes its value. The intensity of the magnetic field and therefore the heating energy can be controlled this way.

Induction Cooker - STMicro AN2383

The +325 V DC link voltage is applied through a filter to the upper-side IGBT only when the safety relay is closed and the system is on. Components inside the dotted rectangle are the core part of the power stage: the L-C resonant tank is obtained by the plate (represented in the schematic by a spiral) and the capacitors on the left side. The resonant capacitor has been divided in two identical capacitors, so that the amount of current flowing through each capacitor is reduced by half, while the voltage to the capacitors remains the same.

Induction heating is a non-contact heating process - Richie's Tesla Coil Web Page