![]() ![]() ![]() This basic functionality of an IPM is illustrated in Figure 3.įigure 3. This feedback mechanism leads to an “intelligent” power switch that can protect itself from failure conditions. It monitors the device's current density to shut the device down when an overcurrent/short-circuit condition occurs. This control circuitry, which is integrated with the IGBT, is a feedback loop with current sensing capability. Instead of optimizing the device performance, some manufacturers decided to add some control circuitry to the available IGBTs to prevent it from latch-up. Over the years, the IGBT manufacturers have improved the device physics to achieve better power switches that are capable of withstanding relatively larger current densities without experiencing a latch-up failure. ![]() The Basic Concept of an Intelligent Power Module (IPM) Note that the body region resistance and the gain of BJTs are functions of ambient temperature and the device becomes more susceptible to latch-up at elevated temperatures. The latch-up current is shown in Figure 2.įigure 2. Latch-up current. In this case, the IGBT current is no longer controlled by the gate voltage. Image courtesy of STMicroelectronics.ĭepending on the current density and the rate of change of voltage (dvdt) at the device turn-off, the parasitic thyristor can turn on and cause device failure (latch-up). Vertical cross-section and an equivalent circuit model of a punch-through (PT) IGBT. Figure 1 illustrates the creation of this parasitic thyristor.įigure 1. The main problem with an IGBT is a parasitic PNPN (thyristor) structure that can lead to device failure. At voltage ratings above 200 V, MOSFETs exhibit inferior conduction performance as compared to a BJT.Īn IGBT combines the best of these two worlds to realize a high-performance power switch: it offers the ease of drive of a MOSFET with on-state characteristics of a BJT. However, the major challenge with power MOSFETs is that their on-state resistance increases with device breakdown voltage. With power MOSFETs being voltage-controlled devices, we need simpler drive circuitry. Power BJTs have desirable on-state conduction performance however, they are current-controlled devices and need complex base drive circuitry. In this article, we’ll look at some of the basic concepts of this technology and see how an IPM can extract the best performance possible from an available IGBT device. Overcurrent, overheating, and under-voltage detection are three of the self-protection functions commonly found in an IPM. In this way, the best possible performance can be achieved from an available IGBT technology. ![]() It includes the required drive circuitry and the protection functions, as well as the IGBTs. An intelligent power module (IPM) is a power semiconductor module that integrates into a single package all the circuitry required to operate an IGBT. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |