Characterization and Comparison of High Blocking Voltage IGBTs and IEGTs Under Hard- and Soft-Switching Conditions

The market of converters connected to transmission lines continues to require insulated gate bipolar transistors (IGBTs) with higher blocking voltages to reduce the number of IGBTs connected in series in high-voltage converters. To cope with these demands, semiconductor manufactures have developed several technologies. Nowadays, IGBTs up to 6.5-kV blocking voltage and IEGTs up to 4.5-kV blocking voltage are on the market. However, these IGBTs and injection-enhanced gate transistors (IEGTs) still have very high switching losses compared to low-voltage devices, leading to a realistic switching frequency of up to 1 kHz. To reduce switching losses in high-power applications, the auxiliary resonant commutated pole inverter (ARCPI) is a possible alternative. In this paper, switching losses and on-state voltages of NPT-IGBT (3.3 kV-1200 A), FS-IGBT (6.5 kV-600 A), SPT-IGBT (2.5 kV-1200 A, 3.3 kV-1200 A and 6.5 kV-600 A) and IEGT (3.3 kV-1200 A) are measured under hard-switching and zero-voltage switching (ZVS) conditions. The aim of this selection is to evaluate the impact of ZVS on various devices of the same voltage ranges. In addition, the difference in ZVS effects among the devices with various blocking voltage levels is evaluated.

I. Introduction

Converters connected to transmission lines (e.g., FACTS devices) require insulated gate bipolar transistors (IGBTs) with high blocking voltages and low switching losses to reduce number of devices connected in series and capacity of ac filters. However, these performances have a tradeoff relationship. To improve this tradeoff, semiconductor companies have developed several technologies. They are field stop (FS), soft punch through (SPT) technology, and injection-enhanced gate transistor (IEGT) technology. Such technologies make it possible to operate near the silicon semiconductor limit. Nowadays, the FS technology is applied to 6.5-kV IGBTs [1]–[3], as well as the SPT technology [4], [5]. In addition, IEGTs with blocking voltages up to 4.5 kV are available [6]–[8]. However, all these IGBTs and IEGTs still have very high switching losses; thus, in practice, the switching frequency is limited to about 1 kHz. If such devices are used in inverters connected to transmission lines (e.g., STATCOMs), high switching frequencies are necessary to achieve low harmonic distortion of the current without large filters.