Working principle of switching power supply and troubleshooting of power supply without voltage output
The switching power supply part of an induction cooker generally generates two voltages, 18V and 5V. 5V supplies power to the main control chip and button display driver chip, while 18V supplies power to the fan and IGBT driver circuit. Due to the relatively low power consumption of the electromagnetic furnace control circuit, switching power supplies generally use driver chips with integrated switch transistors on the chip. In order to save costs, many power supplies also use non isolated drivers, commonly used driver chip models such as VIPer12A.
Working principle of electromagnetic furnace switch power supply
The component parameters used on the periphery of switching power supplies using different chips and schemes may vary slightly, but their basic working principle is the same. Taking VIPer12A as an example, this is a very commonly used model in induction cookers. VIPer12A is a power driver chip launched by Italian semiconductor. The chip integrates a high-voltage power transistor and a voltage source at the drain of the chip switch transistor, so the power supply can work without starting a resistor. The chip also integrates protection circuits such as over temperature, over current, and over voltage, and its maximum output power can reach 13W depending on the packaging.
In addition to having an internal voltage generating circuit, VIPer12A also has a unique power transistor structure. The internal switch tube has two source electrodes, and there is a difference in the area between these two principles. A current sampling resistor is connected between the smaller source electrode and the ground. Due to the sampling resistor being connected to a smaller source electrode, the current flowing through this resistor is not the total current flowing through the switch tube, but a portion of it. The total current can be obtained through proportional calculation. This design not only reduces the loss on the sampling resistor and has a certain energy-saving effect, but also eliminates the need for current sampling resistors outside the chip, simplifying the circuit structure and saving costs. This is also a unique aspect of this chip design.
