NTC thermistor chip, whose resistance varies with temperature, is widely used in all kinds of occasions such as temperature monitoring, temperature control, temperature compensation, etc., and plays a pivotal role in the IGBT(party Gate polarizing Transistor). IGBT has become one of the fast-growing power electronics due to its high-input impedance and low-conductive voltage drop, which has gradually replaced the thyristor and gate-turn-off thyristor. IGBT is easy to drive, high peak current capacity, self-closing, high switching frequency (10-40 kHz) and is widely used in small, high-efficiency variable frequency power supplies, motor speed control, UPS and inverted welding machines.
IGBT is controlled by grid (G), emitter (E), and collector (C). Its working principle is to provide the base current to the PNP (Plug-and-play) transistor by adding forward gate voltage to form a channel, so as to make IGBT conductive; Conversely, the reverse gate voltage is added to eliminate the channel, cutting off the base current, and turning the IGBT off. If a driving positive voltage is added between the grid and the emitter of IGBT, the metal oxide semiconductor field effect transistor(MOSFET) will be on, and the collector and base of PNP transistor will become a low resistance state, making the transistor on. If the voltage between the grate and the emitter of the IGBT is 0V, the metal oxide semiconductor field effect transistor will be intercepted, cutting off the supply of the base current of PNP transistor, causing the transistor off.
If the drive voltage between the gate and the emitter of IGBT is too low, it will cause the IGBT to operate unstable; And if the drive voltage is too high, even beyond the withstand voltage between the grid-emitter, there is a chance that the IGBT will be permanently damaged. Similarly, if the voltage between the collector and the emitter of IGBT exceeds the permissible value, the current flowing through the IGBT will exceed the limit, causing the IGBT to exceed the allowed temperature, and there is a chance that the IGBT will be permanently damaged. At this point, we need to use the pointer-type multimeter to determine whether the IGBT is damaged. The specific operation is as follows:
First of all, the pointer-type multimeter is dialed to R×10KΩ (if the gear is R×1KΩ, the internal voltage is too low to make IGBT on), with a black probe connected the collector(C) of IGBT, the red probe connected to the emitter (E) of the IGBT, the pointer of multimeter is in zero;
Then, touch the grid (G) and the collector (C) with fingers at the same time, at which point the IGBT is triggered on, and the pointer of the multimeter swings significantly and points in a direction with a small resistance value and can be maintained in a certain position;
Then, touch the grid (G) and emitter (E) with fingers at the same time, at which point the IGBT is blocked and the pointer of the multimeter returns to zero.
In the detection, if the above phenomenon occurs, it means that the IGBT is not damaged, otherwise there is a problem with the IGBT.
High-reliable NTC thermistor chip for IGBT produced by EXSENSE Electronics Technology Co., Ltd., because of its high temperature, high accuracy (can up to ±0.5%, ±1%, ±2%, ±3%), rapid response and so on, which plays an indispensable role in IGBT module.