Electromagnetic induction cookers are used to heat food. The surface of the induction cooker is a heat-resistant ceramic plate. Alternating current generates a magnetic field through an electromagnetic coil under a ceramic plate. When the magnetic lines of force in the magnetic field pass through the bottom of an iron pan, a stainless steel pot and the like. , produce vortex, so that the bottom of the pot quickly heats up, thus achieving the purpose of heating food. (as shown in the figure below)
Its working process is as follows: AC voltage is converted into DC by rectifier, and then DC is converted into high-frequency AC which exceeds audio frequency by high-frequency power conversion device, and the high-frequency AC is added to flat hollow spiral induction heating coil, thus generating high-frequency alternating magnetic field. Its magnetic field lines penetrate the ceramic platen of the furnace and act on the metal pot. Due to electromagnetic induction, there is a strong eddy current in the pot. When the vortex flows against the internal resistance of the pot, the conversion from electric energy to heat energy is completed, and the generated Joule heat is the heat source of cooking.
Common faults and maintenance of induction cooker;
There are three common faults of induction cooker:
1? Burner-fuse and IGBT.
The specific performance is that there is no response when the power is turned on and the whole machine does not work. When we take apart the machine, we will find that the insurance has exploded, and it exploded so badly that the glass walls of the insurance were blackened. Further inspection, we will find that the IGBT under the large radiator is also broken, and sometimes the rectifier bridge is burnt out, but the rectifier bridge is much stronger than IGBT. Under normal circumstances, only IGBT is burned.
In this case, we should not rush to replace parts and try the machine. Also check for other broken parts. In this case, I will measure all the large resistors in the circuit and the two transistors (8050, 8550) driving IGBT, and then see if the 300V filter capacitor and the 0.33uF resonance capacitor are bulging. If all these are normal, replace all the bad parts except IGBT with new parts. At this time, start to test whether +5V,+15V or+18V and the B-pole 0V of IGBT are normal. Only when these voltages are normal can IGBT be installed. This can eliminate most of the machine explosion failures.
2? The whole machine did not respond, but it did not explode.
Trial operation, the whole machine does not work, open the induction cooker and find the fuse intact.
In this case, the power conversion chip of the induction cooker is burnt out, which generally produces a voltage of 18V, and then converts it into a voltage of +5V through 7805 for the CPU to work. Without +5V, the CPU can't work, and of course the whole machine can't. Generally, such chips in induction cookers are viper 12a, viper22a, thx203h, etc. Measure the periphery of the power conversion chip to see if there are any small devices with damaged connectors. If yes, replace them.
3? It can be opened, but the fault code is displayed.
This kind of fault must first understand the meaning of the code, and then repair it purposefully. There are many fault codes of induction cookers on the Internet, so we can make full use of them. This kind of fault is generally large in resistance and volume, so it can be measured one by one and replaced if there is any change. At the same time, check the transformer, 300v/5uF capacitor, thermistor and the only potentiometer in the induction cooker. As long as these places are found, such faults can generally be eliminated. A few may also be caused by damage to LM339, which can be verified by substitution.
4? Function disorder, some press the power button without response.
This kind of fault is best repaired. Generally, the key is broken, or the keyboard is dirty and leaking. Changing the key or cleaning the keyboard can solve this kind of problem.
5? Bad CPU
This kind of fault can't be repaired generally, so it's better not to waste time, because this kind of CPU is hard to find.
6? No heating or intermittent heating.
This kind of fault is not easy to repair, such as temperature detection resistor, synchronous oscillation circuit, IGBT drive, IGBT? C-pole high voltage protection circuit, current detection circuit, PWM modulation circuit and CPU circuit may all be related to this kind of fault. Fixing this fault is to test our patience.
The induction cooker is one of the daily necessities in the kitchen. No matter how you use it, you will encounter some minor problems. After understanding the internal heating principle of induction cooker, when there are small problems in induction cooker, you will understand where some problems are.
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