Tobias Wikstrom

Experimental study on plasma engineering in 6500 V IGBTs

This paper discusses the design of high-voltage Insulated Gate Bipolar Transistors (IGBTs), especially the effects on the on-state excess carrier distribution and its consequences for the IGBTs on-state, turn-off and Safe Operating Area (SOA) properties. It is concluded that by careful design, considerable robustness is achievable together with total losses that are comparable to a state-of-the-art GCT Thyristor of similar voltage class.

IGCTs: High-Power Technology for power electronics applications

This paper focuses on the most recent technical developments in Integrated Gate Commutated Thyristors. Improved Safe Operating Area (SOA) of a new IGCT chip set based on ABBs High Power Technology (HPT) platform with a rated voltage of 10kV is presented. A matching 10kV freewheeling diode is also reported. Combined, these developments open the door to new applications of silicon IGCTs reaching voltage levels of 7.2kV RMS or more.

The Corrugated P-Base IGCT - a New Benchmark for Large Area SQA Scaling

A 91 mm diameter IGCT with extraordinary safe operating area (SOA) is presented in this paper. The power density at turn-off reached values as high as 700 W/cm2, which is twice the previously reported SOA limit for devices with a comparable diameter. The improvement was achieved by masking one of the p-base diffusions, giving the p-base a corrugated appearance as well as improving the gate circuit.

The Destruction Mechanism in GCTs

This paper focuses on the causes that lead to the final destruction in standard gate-commutated thyristor (GCT) devices. A new 3-D model approach has been used for simulating the GCT which provides a deep insight into the operation of the GCT in extreme conditions. This allows drawing some conclusions on the complex mechanisms that drive these devices to destruction, previously impossible to explain using 2-D models.

An IGCT chip set for 7.2 kV (RMS) VSI application

In this paper we present a novel Integrated Gate- Commutated Thyristor (IGCT) for application in medium voltage drives at voltage levels of 7.2kV RMS or more. Measurements of over 11kV blocking-, on-state- and expanded SOA switching behavior are the basis for a detailed description of the performance. The new design features a planar junction termination, in combination with a corrugated p-base. These design concepts provide acceptable turn-on properties and improve turn-off Safe Operating Area (SOA) simultaneously. Improved diode soft reverse recovery at low currents is demonstrated using a combination of deep buffers and the Field Charge Extraction (FCE) concept.

Why is fast recovery diode plasma-engineering with ion-irradiation superior to that with emitter efficiency reduction?

This paper presents the comparison of two 4.5 kV diodes with expanded safe operating area (SOA) in terms of an expansion to higher line voltages. In order to improve the reverse recovery characteristic the excess carrier concentration close to the anode during the on-state has to be reduced. To control the injection efficiency of the anode two state of the art technologies, the reduction of the emitter doping and the ion irradiation in the p-doping region, are compared in this paper. The local lifetime control technique is shown to have major advantages compared to the emitter doping reduction technique in terms of up to 50% lower switching losses at recovering from low forward current densities (e.g., 2 A/cm/sup 2/). This improvement was obtained on devices with identical on-state characteristic. Additionally, a softer switching behavior is observed for the ion-irradiated diodes. An explanation for this experimentally found behavior is provided by calibrated computer simulations.

Recent advancements in IGCT technologies for high power electronics applications

In this paper, we review the progress made recently for further developing the Integrated Gate Commutated Thyristor (IGCT) device concept for high power electronics applications. A wide range of newly introduced IGCT technologies are discussed and recent prototype experimental results as well as novel structures and future trends of the IGCT technology are presented. This will provide system designers with a comprehensive overview of the potentials possible with this device concept.

The 150 mm RC-IGCT: A device for the highest power requirements

A 4500V RC-IGCT switching more than 10 kA in both switch and diode mode was developed for application in cascaded multilevel topologies. The performance was facilitated by using most of a 150 mm silicon wafer for a single device. Furthermore, the stray inductance of the gate bushing inductance was lowered an order of magnitude, and the use of an outer ring gate contributed significantly to lower impedance on the device itself. Adjustment of the di/dt choke led to significant reduction of total losses. FCE as a means of loss optimization was investigated.

Parameters influencing the maximum controllable current in gate commutated thyristors

The model of interconnected numerical device segments can give a prediction on the dynamic performance of large area full wafer devices such as the GCTs and can be used as an optimization tool for designing GCTs. In this paper we evaluate the relative importance of the shallow p-base thickness, its peak concentration, the depth of the p-base and the buffer peak concentration.

Turn-off failure mechanism in large area IGCTs

The destruction mechanism in large area IGCTs (Integrated Gate Commutated Thyristors) under inductive switching conditions is analyzed in detail. The three-dimensional nature of the turn-off process in a 91mm diameter wafer is simulated with a two-dimensional representation. Simulation results show that the final destruction is caused by the uneven dynamic avalanche current distribution across the wafer.