Hans-Günter Eckel

A new family of modular IGBT converters for traction applications

Electrical locomotives and trains are nowadays driven by asynchronous motors, which are fed by voltage source inverters. The IGBT two level inverter allows a standardization of the topology and the control strategy over the whole power and voltage range. However, different application conditions (cooling, dc-link voltage, power range) lead to different converters. To allow a flexible converter design with proven components, a family of power electronic building blocks was developed, which uses 3.3 kV and 6.5 kV IGBT and achieves an output power of up to 3 MW

Experimental investigation on the behaviour of IGBT at short-circuit during the on-state

Short-circuit withstand capability is an important feature of IGBTs for voltage-source inverter applications. Many manufacturers offer IGBTs with a guaranteed short-circuit withstand time. But in most cases, the short-circuit withstand capability is defined for the short-circuit type I. In this case, the load is already short-circuited when the IGBT is turned on. If the load is short-circuited when the IGBT carries current (short-circuit type II), the stress for the IGBT can be much higher. In this paper, the short-circuit type II behaviour of different IGBTs is investigated and a concept for a gate-drive circuit for improved short-circuit type II behaviour is introduced.<<ETX>>

Comparison of multisystem traction converters for high-power locomotives

The European railways are characterized by a wide range of supply voltage systems. To allow flexible operation of electrical locomotives and short stops at system borders, multisystem locomotives are necessary. The paper gives a comparison of different solutions for multisystem converters and introduces the most promising concept based on the latest high-power IGBT technology.

Challenges in using the latest generation of IGBTs in traction converters

Summary The voltage class 6.5kV was the last step to now cover completely the whole range of voltages for traction starting with 1.7kV and 3.3kV. This lead to the general introduction of the IGBT across the whole power range of traction. In first IGBT generations the Non Punch Through design dominated here. The latest generation of IGBTs feature characteristics like field-stop design or trench design. Thus high cosmic ray withstand capability can be combined with low VCesat. For the high-power high-voltage application as used in traction, the introduction of the field stop leads to a significant change in the switching behavior compared to the conventional NPT-design. It will be shown how the IGBT and diode turn-off characteristics change and how sensitive it is to parasitic circuit characteristics. Especially in high-power circuits with relatively large stray inductances, this is a device and application challenge. Further more it will be shown that the IGBT overvoltage during turn-off transients can be controlled only by using a highly dynamic gate driver. Since no active control ofthe diode turn-offis possible, the peak-voltage must be limited by appropriate circuit and device design. For new generations of IGBT and diode, this behavior should be considered carefully by the semiconductor development.

Fundamental frequency and mission profile wearout of IGBT in DFIG converters for windpower

In this paper the influence of fundamental frequency and mission profile power cycles on estimated lifetime of the power semiconductors in the rotor side converter of a DFIG will be investigated. The aim of this paper is to get a feeling which impact the large cycles due to the variation of wind speed (mission profile cycles) and the short cycles caused by the output frequency of the converter (fundamental frequency cycles) have on the estimated life time of the power semiconductors. The total number of cycles, including mission profile and fundamental frequency cycles, were counted using the Rainflow algorithm. To count the fundamental frequency only the maximum and minimum temperature within one period of the fundamental frequency were extracted. The investigation was done for a real wind speed over time profile over 6 months.

Fixed-reference-frame-control: A novel robust control concept for grid side inverters in HVDC connected weak offshore grids

Offshore wind energy plants built at a long distance from public ac-grid are connected by HVDC-transmission. Hence an offshore ac-island-grid results, in which the HVDC station generates the grid while the inverters of the wind power plants synchronize themselves on that gird. As the power of the HVDC-station is not significant higher than that of the sum of all wind power plants, the grid is relative weak. This could lead to stability problems of wind power plants grid side converters.

Optimization of the Short-Circuit Behaviour of NPT-IGBT by the Gate Drive

SummaryShort-circuit withstand capability is an important feature for IGBT in inverter applications. With NPT-IGBT, the stress for the device is especially high if the short-circuit occurs while the device is carrying current (short-circuit type II). In this case, a high current peak and a large ovenvoltage can occur. In this paper, a model for the dependence of the current and voltage stress of a NPT-IGBT is given. It shows that the voltage stress is especially high for IGBT with a high rated current. A new Rate drive concept, the di/dt controlled gate clamping, that reduces the current and the overvoltage is investigated on. This gate drive concept is combined with a concept for turn-off of the steady-state short-circuit. Experimental results show that safe operation in every short-circuit situation is possible.

Next generation of IGBT-modules applied to high power traction

Modern high power traction converters are equipped with IGBT-modules. For a reliable operation the modules have to fulfil the following requirements: High junction temperature limit, large safe operating area, high surge current capability and sufficient thermal cycling capability. In this paper current and next generation of IGBT modules will be characterised regarding the first three aspects.

Evolution of IGBT converters for mass transit applications

Since its invention in the early 1980s the IGBT has become the dominant power semiconductor in converters for mass transit applications. The paper describes the evolution of converter technology from special circuit configurations up to todays standard. The special requirements on high power IGBTs for traction are given with respect to electrical characteristics and above all load cycle capability. Various cooling systems, natural cooling, forced air cooling and water cooling compete and differ in converter output power but also in exploiting the thermal load cycle due to differing thermal capacitance. Here they are compared with respect to their performance in mass transit applications. In the end a comparison on basic system aspects involving converter control is given.

Multicommutation of IGBTs in large inverters

Large inverter-systems are characterized by a significant number of parallel IGBTs operating on the same dc-link. The IGBT-phases are cross coupled by their mutual stray inductance. This paper investigates the special effects occurring due to nearly simultaneous switching of multiple IGBTs. This operation can cause a significant increase in stress on the IGBT and on the free wheel diode. Countermeasures to cope with these problems are discussed