Gerald Deboy

Matched pair of CoolMOST/sup TM/ transistor with SiC-Schottky diode-advantages in application

The new CoolMOS/sup TM/ C3 generation combines extremely high on-state conductivity with ultra fast switching speed at full pulse current capability. In the first generation of CoolMOS/sup TM/, due to the small chip size, one had a reduction of the saturation current at the cell level. This technique results in a reduced current capability of the device at low gate voltages. In many applications, the outstanding switching performance of the cannot be utilized due to the dynamic behaviour of CoolMOS/sup TM/ the diode. For this reason ,a whole family of SiC-diodes has been developed to get the ideal matched pair of switch and ultra fast diodes. The goal of ultra low loss applications in SMPS, power factor correction circuits and motor control units will be achieved completely.

Optimal design of a compact 99.3% efficient single-phase PFC rectifier

Due to rising energy costs the efficiency of power electronics converter systems is of higher and higher importance, especially for applications with continuous operation as e.g. server power supplies. For designing such supplies numerous parameters like the switching frequency and the characteristic values and the geometry of magnetic components must be determined. In this paper, an optimisation procedure, which automatically determines the parameter values of a single-phase bridgeless PFC rectifier for maximum efficiency is presented. There, continuous and discontinuous operation mode, as well as a concept for magnetic integration of the CM and DM filter inductors is included. For verifying the considerations, a prototype with 99.3% efficiency and a power density of 1.35kW/dm3 is presented.

A comparison of electron, proton and helium ion irradiation for the optimization of the CoolMOS/spl trade/ body diode

With a view to improving the switching speed of the internal diode, we exposed CoolMOS/spl trade/ power MOSFETs as prominent representatives of the new class of charge compensation devices to irradiation by electrons, protons or helium ions for lifetime control and studied the influence of irradiation and annealing parameters on the electrical device characteristics. Our investigations show that electron irradiation provides the best overall result. The reverse recovery charge Q/sub rr/ can be reduced by a factor of 10 compared to reference devices without any significant change of the remaining electrical data of the device.

ZVS of Power MOSFETs Revisited

Aiming for converters with high efficiency and high power density demands converter topologies with zero-voltage switching (ZVS) capabilities. This letter shows that in order to determine whether ZVS is provided at a given operating point, the stored charge within the mosfets has to be considered and the condition LI2≥2Qoss has to be fulfilled. In the case of incomplete soft switching, nonzero losses occur which are analytically derived and experimentally verified in this letter. Furthermore, the issue of nonideal soft-switching behavior of Si superjunction mosfets is addressed.

A novel trench concept for the fabrication of compensation devices

In this paper we propose a novel trench based concept for compensation devices. Our approach includes the conformal deposition of two epitaxial layers in the trench. We present simulation results indicating an improvement in Rdson*A by more than 50 % versus 600V CoolMOS as todays benchmark in compensation devices. Furthermore we demonstrate the successful implementation of the necessary single processes such as deep trench etch (aspect ratio 12:1) and conformal defect free epitaxy.

Hardware verification of a hyper-efficient (98%) and super-compact (2.2kW/dm 3 ) isolated AC/DC telecom power supply module based on multi-cell converter approach

Due to the increasing electricity demand of data centers driven by the emergence of cloud computing and big data, the focus on the development of telecom and data center power supplies is shifted towards high efficiencies. In this paper, a multi-cell converter approach for a telecom rectifier module breaking through the efficiency and power density barriers of traditional single-cell converter systems is shown. The comprehensive optimization of the entire system with respect to efficiency and volume is described and the applied component loss models are explained. Furthermore, the design of a hardware demonstrator based on the optimization results is presented and several important design aspects are explained in detail.

Compensation devices versus power MOS and high speed IGBT - a device physics based guideline for the application

This article focuses on the advantages and technological challenges of state-ofthe-art power devices for fast switching applications. It covers the power MOSFET, the high speed IGBT and the recently introduced compensation devices with 600 V blocking capability. Special emphasis is laid on the charge compensation

Hyper-efficient (98%) and super-compact (3.3kW/dm 3 ) isolated AC/DC telecom power supply module based on multi-cell converter approach

In this paper, a multi-cell converter approach for a telecom rectifier module breaking through the efficiency and power density barriers of traditional single-cell converter systems is shown. The potential of the multi-cell approach for high efficiency is derived from fundamental scaling laws of the system performances, such as the losses generated by the semiconductors and the harmonic spectrum, in dependence of the number of converter cells. Furthermore, a comprehensive optimization of the entire system with respect to efficiency and volume has been performed and the applied component loss models are described in detail. The achievable performance of the system is compared to a leading edge state-of-the-art single-cell converter system which currently sets the benchmark in terms of efficiency and power-density. In addition, the degrees of freedom of multi-cell converter systems in terms of converter operation are outlined and optimum control schemes are derived.

Determination of transient transistor capacitances of high voltage MOSFETs from dynamic measurements

This paper describes for the first time the determination of transient transistor capacitances of a high voltage transistor in a commutation circuit with application relevant conditions. Therefore, the gained characteristics reflect the transistor capacitances during switching. The dependency on operating conditions can be analyzed. New information on the drain current distribution between channel current and output capacitance current is gained from dynamic measurements. As a result, a recommendation is made for more accurate calculation of switching losses.

Superjunction Power Devices, History, Development, and Future Prospects

Superjunction has arguably been the most creative and important concept in the power device field since the introduction of the insulated gate bipolar transistor (IGBT) in the 1980s. It is the only concept known today that has challenged and ultimately proved wrong the well-known theoretical study on the limit of silicon in high-voltage devices. This paper deals with the history, device and process development, and the future prospects of Superjunction technologies. It covers fundamental physics, technological challenges as well as aspects of design and modeling of unipolar devices, such as CoolMOS. The superjunction concept is compared to other methods of enhancing the conductivity of power devices (from bipolar to employment of wide-bandgap materials) to derive its set of benefits and limitations. This paper closes with the application of the superjunction concept to other structures or materials, such as terminations, superjunction IGBTs, or silicon carbide Field Effect Transistors (FETs).