IGBT reliability analysis Relationship between output voltage edge rate and switching rate

Nowadays, with the rapid development of science and technology, traditional power conversion has been unable to meet the needs of power equipment. With the rise of new frequency conversion equipment, the application of high-power IGBT is gradually increasing. The reliability of IGBT is directly related to the efficiency of frequency conversion and the safety of power equipment. Therefore, the reliability of IGBT is becoming the focus of attention. This article comes from the experience of experts, and discusses the problem of the mismatch between the output voltage and the switching rate of the drive circuit in the reliability of IGBT. Interested friends come and take a look.

In IGBTs, the following problems are sometimes encountered. The rising and falling edge rates of the output voltage of the drive circuit do not match the switching rate of the IGBT, or the peak power of the auxiliary power supply is insufficient, resulting in the drive circuit not being able to drive at full amplitude. The consequence of this problem is that the product batch consistency is reduced and the worst-case probability of the system is increased.

In fact, the most direct parameter to measure the performance of an IGBT driver is the output capability. That is, the output peak current and the rising and falling edge rates. The reason for this is because the switching process of the IGBT corresponds to the changing waveform of the gate voltage. It is precisely the above two indicators that determine the quality of the waveform. Because the power level of the IGBT and the requirements of the application are very different. Therefore, the output capacity requirements of the corresponding drivers are also very different. And if you choose a driver with insufficient output capacity in order to save costs, it will definitely not be worth the loss. Especially in occasions where high reliability is required. So how to measure whether the output capacity of the driver is sufficient?

First, in terms of rising and falling rates. When the collector current corresponding to the IGBT gate voltage reaches the current actual collector current value, that is, when the IGBT operates at the boundary point between the linear amplification range and the saturation range. The driver output should be able to ensure that the maximum (minimum) output voltage has been reached.