IGBT or MOSFET

IGBT or MOSFET




In the solar energy conversion process, there are various kinds of advanced power devices can be used, such as MOSFET, bipolar junction transistors (BJT) and the IGBT. To achieve the best conversion efficiency and performance, choose the right inverter for solar power transistors challenging and very time-consuming.

Over the years studies have shown that, IGBT power devices can provide more than any other advantages, including a more current handling capability, with the voltage (rather than current) to facilitate realization of gate control, as well as an integrated package ultra-fast recovery diode achieve faster turn-off time. IGBT is a minority carrier device, its off-time depends on the minority carrier re-combination of speed, therefore, with the recent process technology and device structures to improve its switching characteristics have been significantly enhanced.



IGBT is basically have the structure of metal gate-oxide gate bipolar transistor (BJT). This design allows the gate IGBT can be the same as the MOSFET in order to replace the current to voltage control switch. As a BJT, IGBT's current handling capability higher than the MOSFET. At the same time, IGBT same applies BJT as a minority carrier device. This means that the speed of IGBT off by a handful of carriers to determine the composite rate of speed. In addition, IGBT's closing time and its collector - emitter saturation voltage (Vce (on)) is inversely proportional to.



If the IGBT has the same size and technology, a speed IGBT than the speed of a standard IGBT has a higher Vce (on). However, speeding the closure of IGBT Standard IGBT is much faster than the speed. Figure 2 shows this relationship by controlling the IGBT is a minority carrier recombination rate of the use of cycles in order to influence the closing time to achieve.



Generally speaking, due to a larger current IGBT (which is more than twice the MOSFET), so the cost of the program using IGBT than using low cost MOSFET. In addition to cost considerations, the device performance by the degree of power loss table, while the power loss can be divided into: conduction and switching categories. As a minority-carrier-based devices, under the high current, IGBT has a lower turn-on voltage, which means lower conduction losses. But the MOSFET switching speed faster than in IGBT switching losses so low. So for calling for lower switching frequencies and higher current applications, choose the IGBT is more suitable and has a more low-cost advantage. On the other hand, MOSFET have the ability to meet the high-frequency, low current applications, especially those of more than 100kHz switching frequency power inverter power module needs. Although the device cost point of view, MOSFET than in IGBT expensive, but its ability to deal with a higher switching frequency will simplify the magnetic design of the output filter will significantly reduce the size of the output inductor.



For these reasons, more manufacturers prefer therefore to a high level of energy in the power inverter used in IGBT. According to Microsemi company, the company's production of MOS8 IGBT in static and dynamic testing (to minimize the overall power loss) in the optimization of performance can be well suited to these applications. On the other hand, even if the cost of MOSFET is a major consideration, but for the introduction of a better program, it should re-examine the potential use of MOSFET, such as Microsemi's MOS7/MOS8 MOSFET with the leading features of the very suitable for the design of solar energy inverter.



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