In the induction cooker, the IGBT is a component with a large share of damage. If the cause of the failure is not identified, the test machine will cause the IGBT to be damaged again.
1. Capacitor failure
When the 0.3UF capacitor fails, or leaks, and the 400V capacitor capacity becomes smaller, the frequency of the induction cooker and LC oscillation circuit will be high, which will cause IGBT damage. When other components are checked and there is no problem, replace the 0.3UF and 400V capacitors.
2. IGBT tube control circuit
The excitation circuit is abnormal, and the pulse signal output by the oscillation circuit cannot directly control the saturation, turn-on and cut-off of the IGBT, and must be done by amplifying the excitation pulse signal. If there is a problem with the excitation signal, the high voltage will be added back to the G level of the IGBT tube, causing the IGBT to break down instantly and be damaged.
3. Synchronous circuit
The synchronization circuit is abnormal. The main function of the synchronization circuit in the induction cooker is to ensure that the switching pulse added to the G level of the IGBT tube is synchronized with the delay of the VCE pulse on the IGBT tube. When the synchronization circuit works abnormally, the IGBT tube breaks down instantaneously.
4. 18V working circuit
The 18V voltage is abnormal. When the 18V voltage appears in the induction cooker, it will cause the IGBT tube excitation circuit, the fan cooling system and the LM339 to work abnormally, causing the IGBT to be damaged instantly when it is powered on.
5. Cooling system
The cooling system is abnormal. The induction cooker works in a high current state, and its calorific value is also large. If the cooling system is abnormal, it will cause the IGBT to be overheated and damaged.
6. Integrated chip
If the MCU is abnormal, the IGBT will be burnt inside the MCU due to the abnormal working frequency.
7. VCE detection circuit
The VCE detection circuit is abnormal. The VCE detection induction cooker passes the pulse voltage on the IGBT official collector, divides the resistance by the resistance, and obtains the sampled voltage = sampling voltage. The information change of this voltage is transmitted to the CPU, and the CPU monitors the voltage change and makes various responses. The command, when the VCE detection circuit fails, the VEC pulse amplitude. Exceed the limit value of IGBT tube, resulting in IGBT damage. The user's pot is deformed, or the pot is raised and uneven, and the eddy current generated in the pot cannot uniformly heat the deformed pot, so that the temperature sensor of the pot is abnormal, and the CPU cannot detect the abnormal temperature signal. And continue to heat, resulting in IGBT damage.
8. User cookware problems
The user's cookware is deformed, or the bottom of the cooker is raised and uneven, and the eddy current generated at the bottom of the cooker cannot uniformly heat the deformed cookware, so that the temperature sensor of the cookware is abnormal, and the CPU cannot detect the abnormal temperature signal. Continue to heat, resulting in IGBT damage.
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