Induction Cooker Switching Power Supply Operating Principle and Power Supply Troubleshooting
Switching power supply part of the induction cooker, generally produces two voltages, 18V and 5V, of which 5V is to the main control chip and key display driver chip power supply, 18V voltage to the fan as well as the IGBT drive circuit power supply. As the power consumption of the induction cooker control circuit is relatively small, the switching power supply will generally use on-chip integrated switching tube driver chip, in order to save costs, many power supplies will also use non-isolated drive, commonly used driver chip models such as VIPer12A.
Induction switching power supply working principle
The use of different chips and programmes of the switching power supply peripheral components used in the parameters will be slightly different, but the basic principle of operation are the same, to VIPer12A for example, this is a very commonly used models in the induction cooker. VIPer12A is the STMicroelectronics power supply driver chip, the chip is integrated into the internal high-voltage power tubes, and in the chip switch tube drain integrated voltage source, so the power supply does not need a start-up resistor to work. The power supply does not need a start-up resistor to work. The chip is also integrated inside the over-temperature, over-current, over-voltage and other protection circuits, depending on the package, its maximum output power can be up to 13W.
In addition to the internal voltage generation circuitry, the VIPer12A also has a special power tube structure. The internal switching tube has two sources, and there is a difference in the area of these two principles, and a current sampling resistor is connected between the source with a smaller area and ground. Because the sampling resistor is connected to the smaller source, the current flowing through this resistor is not the total current flowing through the switching tube, but a part of it, and the total current can be derived through proportional calculation. This design not only reduces the loss on the sampling resistor, to play a certain role in energy saving, but also in the chip outside the current sampling resistor is not needed, simplifying the circuit structure, cost savings, which is also a relatively unique aspect of the design of this chip.
