How To Make Induction Cooker

The induction cooking design consists of a small number of simple blocks.
The isolated power supply is obtained directly from the mains, 220 V AC 50 Hz. 15 volts are
used to supply the IGBT driver, fan, relay and feedback circuitry, while 5 volts are needed to
supply the rest of the ICs, including the MCU.
The ST7FLITE09Y0 microcontroller controls the whole process and communicates with the
user interface (buttons and display), drives the fan and the relay, receives feedback from the
cooking element (referred to in this document as “plate” for simplicity) and generates the
PWM signal to drive the IGBTs.

Schematic
Although the schematic is not very complex, this section presents the different parts as
separate topics:

    Mains, DC link and zero voltage switching
    Isolated power supply
    Power stage
    Feedbacks
    MCU pin configuration

Isolated power supply
An isolated power supply is connected immediately after the mains filtering, without passing
through the safety relay. A VIPer22A and a simple voltage regulator provide 15 and 5 volts
respectively. The power supply ground is isolated from the system ground.

Microcontroller interface using RS485 & RS422

After a period of research, I found out that RS485 and RS422 is in fact the same.

RS422 is a duplex configuration. RS422 using 4 wire to communicate in both direction. One pair of wire to do transmit and the other pair to receive. Both sides is able to transmit and receive at the same time.

RS485 is a half duplex configuration. RS485 using only 2 wire to communicate in both direction. With only two wire, it means that when one side is transmitting, the other side of the communication line will be receiving. Both side cannot be transmitting at the same time. For RS485 transceiver, use MAX485 or MAX3485. They have the same pin out except that MAX485 uses 5V supply, MAX3485 uses 3.3V supply.

RS422 can be connected to work with RS485 to either receive or transmit date, but not both. RS422 can be wired directly using a pair of wire, +ve to +ve, -ve to -ve terminal. For RS422 transceiver, use MAX488 or MAX3488. They have the same pin out except that MAX488 uses 5V supply, MAX3488 uses 3.3V supply.

Circuit diagram ATMEGA64 8-bit Microcontroller with 64K Bytes In-System Programmable Flash

The ATmega64 is a low-power CMOS 8-bit microcontroller based on the AVR enhanced RISC architecture. By executing powerful instructions in a single clock cycle, the ATmega64 achieves throughputs approaching 1 MIPS per MHz, allowing the system designer to optimize power consumption versus processing speed.

The AVR core combines a rich instruction set with 32 general purpose working registers. All the 32 registers are directly connected to the Arithmetic Logic Unit (ALU), allowing two independent registers to be accessed in one single instruction executed in one clock cycle. The resulting architecture is more code efficient while achieving throughputs up to ten times faster than conventional CISC microcontrollers.