Why does the induction cooker heat up for a while and then stop the induction cooker heating principle and maintenance skills?

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After using the induction cooker for a long time, it is inevitable that there will be such problems. For example, if the external power supply is connected, the machine cannot be turned on, the induction cooker will automatically stop working after heating for a period of time, and the furnace will intermittently heat for a while to stop. In detail, the induction cooker is heated for a while and then stopped to encounter such use. How should we solve it?

Induction Cooker is one of the commonly used home appliance utensils that are closely related to our lives. Every day, we use cooking, cooking and cooking to make all kinds of delicious food. However, if the induction cooker is used improperly, or if it is used for a long time, it will inevitably lead to problems that are so difficult to solve. Xiaobian some days ago, the beauty of the home induction cooker is broken, get the maintenance department to dismantle the detection problem, my stove is because the cooking smoke is too much, do not pay attention to the kitchen air circulation, over time, the internal circuit board erosion of the induction cooker Excessive soot stains, causing the display panel to not work can not be turned on. Later, the maintenance master replaced the main circuit board to resume normal work. It was also a chestnut that cost a lot of money to buy life experience, indicating that the daily maintenance work of the induction cooker is also an important part.

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Analysis of the principle of induction cooker heating:

The induction cooker is heated by an electromagnetic field. When the power frequency transformer in the household appliance is working, the iron core will generate heat. The iron core is neither connected to the primary winding nor connected to the secondary winding. How does it heat up? Let us take a look at the following picture:

A schematic diagram of the common power transformer structure is shown above. When the coil is connected to alternating current, an alternating magnetic field is generated in the coil. Each piece of silicon steel in the transformer has magnetic flux lines passing through it. Due to the change of the magnetic field strength, the number of magnetic lines (magnetic flux) passing through each silicon steel sheet changes. According to Lenz's law, it is generated inside each silicon steel sheet. Close the vortex-like induced current (the direction of the current is the current direction at a certain moment) to prevent the change of the magnetic flux. This induced current is called eddy current, which is called eddy current. The eddy current flows in each of the silicon steel sheets, and since the electric current has a thermal effect, the silicon steel sheet generates heat and the temperature rises. The phenomenon that eddy currents convert electrical energy into heat through metal is called the thermal effect of eddy currents.

Although the thermal effect of eddy currents can adversely affect electrical equipment, it can be applied to heating technology, which is called electromagnetic heating technology.

The induction cooker heats up for a while and stops. What is the cause?

There are several possibilities for this phenomenon:

1, the thermistor has problems, replacement;

2, the circuit heat dissipation performance is not good, so that the thermal protection is frequently turned on, you can change the cooking in the ventilation;

3. There is a problem with the oscillating capacitor in the PWM generating wave circuit, and it is replaced;

4, the power plug is a bit loose, it may also cause this phenomenon;

5, turn on the heating mode, select the maximum file to start the test, there may be problems with the mode;

6, cpu is faulty, this is equivalent to only change the motherboard.

For the case where the induction heating is not heated for a certain period of time, the main reason may be the overcurrent of the main circuit or the overvoltage protection of the power tube c. (It can detect the power in the main circuit, whether the whole bridge has leakage or not; whether the potentiometer VR1 current has a problem, whether the power supply voltage is 5V, 18V, 300V in the standby state is normal)

Firstly, it can be checked that the induction cooker is heated for a period of time without heating. This situation is intelligent (computer control mode) or manual; if it is intelligent control, it means that the selected induction cooker mode is incorrect, and another cooking mode can be replaced. If it is manual, there may be less thermal grease on the temperature sensor on the coil plate. Adding thermal grease will be good. If you add thermal grease, it is a problem in the main class.

This problem can also occur when the high voltage capacitors and high voltage resistors on the motherboard are broken. If there is no problem on the motherboard, then there may be a display panel, but the display panel is generally bad.

Again, pay attention to whether the heat sink works normally when the power is turned on, and whether the operation is smooth or not.

In addition, check the two thermistors on the lower coil, one on the IGBT tube and the other on the middle of the coil disc (the resistor on the disc, coated with white thermal grease). When checking the resistance operation, whether the synchronous large resistance value changes or not, and whether the working voltage of the two resistors is normal. Sometimes, unstable voltages can also cause the induction cooker to not heat up.

Observe the looseness of the plug inside the induction cooker. Unplug the two plugs of the magnetron. Check whether the voltage on the primary coil of the transformer is 220 volts. If it is unstable, it can be powered off. Pull out the plugs with pliers. Check for looseness, and the micro switch can also be used to measure it.

During the test, specific problems can be found through the induction cooker current detection method. The actual operation is as follows:

The intermittent heating fault of the induction cooker is involved in many fault points, and it is troublesome to repair. According to experience, it is easy to judge the fault range by carefully observing the change of current magnitude:

1. When the current jumps in the range of 0---7A. It should be checked whether the large resistance value of the synchronous circuit is variable or not, and whether the voltage of the two sampling terminals of the synchronous circuit is normal.

2. When the current jumps in the range of 0---4A. Should focus on the various components of the current detection circuit, such as current transformers (constant copper wire and double op amp circuit), adjustable resistors, diodes, RC components and single-chip circuits.

3. If the current jump is not regular, it is important to check whether the components of the surge protection circuit are good.

4. The small heating is normal. When the large heating is intermittent, you can check the 300V and the filter capacitor first. Check whether the 2μF anti-interference capacitor capacity is reduced. You can use the 3.3μF capacitor to test it. However, due to the thinness of the power supply lead wire or the poor contact of the socket, the failure caused by the use of the pot not meeting the requirements cannot be ignored.

When we use the induction cooker, what precautions, daily maintenance and airframe maintenance work should we pay attention to?

In order to use the induction cooker for a long time, there are the following points to note:

1. The induction cooker has a certain low-frequency electromagnetic radiation. Do not use magnetic cards (such as bank cards) to prevent the magnets from being magnetized, demagnetized or damaged.

2. Although it is not proven that a small amount of low-frequency radiation is harmful or harmless to the human body, pregnant women and children should not use the induction cooker, just in case.

3. The distance between the operator and the induction cooker should not be less than 0.5 m, and do not stand by the induction cooker for a long time to reduce the electromagnetic radiation and ensure safety.

4. The induction cooker uses the magnetic field to induce eddy current heating, that is, the current is generated by the current through the coil. When the magnetic field lines pass through the bottom of the iron pot, the magnetic lines are cut, thereby generating numerous small eddy currents, so that the iron pot itself has iron atoms. Rotating at high speed and producing food that collides with heat and directly heats the pot. In other words, it is the ferromagnetic effect of the ferromagnetic body in the alternating magnetic field to heat up, so the pot should use a wok, not a ceramic pot. If you use aluminum pans, copper pots and other metal pots, the heat efficiency is also very low, basically can not be used.

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