Josef Lutz Heinrich Schlangenotto Uwe Scheuermann - Semiconductor Power Devices

Josef Lutz 1

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Abstract

In a competitive market, technical systems rely on automation and process control to improve their productivity. Initially, these productivity gains were focused on attaining higher production volumes or less (human) labor-intensive processes to save costs. Today, attention is paid toward energy efficiency because of a global awareness of climate change and, above all, questions related to increasing energy prices, as well as security of energy and increasing urbanization. Consequently, it is expected that the trend toward more electrical systems will continue and accelerate over the next decades. As a result, the need to efficiently process electrical energy will dramatically increase.

In a competitive market, technical systems rely on automation and process control to improve their productivity. Initially, these productivity gains were focused on attaining higher production volumes or less (human) labor-intensive processes to save costs. Today, attention is paid toward energy efficiency because of a global awareness of climate change and, above all, questions related to increasing energy prices, as well as security of energy and increasing urbanization. Consequently, it is expected that the trend toward more electrical systems will continue and accelerate over the next decades. As a result, the need to efficiently process electrical energy will dramatically increase.

Devices that are capable of converting electrical energy from one form into another, i.e. transforming electrical energy, have been a major breakthrough technology since the beginning of electrical power systems and are considered key enabling technologies. For example, without transformers, large-scale power generation, transmission, and distribution of electrical power would not have been possible. Interestingly, very few people today are aware that without this invention, initially called secondary generator [], we would not have been able to create such an efficient, safe, and (locally) environmentally clean power source. Of course, as transformers, or generally speaking electromagnetic devices, can only transform voltage or control reactances, their use in automation systems remained limited. At the beginning of electrification, frequency and phase control could only be realized using electromechanical conversion devices (i.e. motors, generators). However, these machines were bulky, required maintenance, had high losses, and remained expensive. Furthermore, these electromechanical devices had rather low control bandwidth. Therefore, they operated mostly at fixed set points. Today, most automation and process control systems require more flexible energy conversion means to vary dynamically voltage or to regulate current, frequency, phase angle, etc.

At present, power electronics is the most advanced electrical energy conversion technology that attains both high flexibility and efficiency. As an engineering field, power electronics came into existence about 50 years ago, with the development and the market introduction of the so-called silicon controlled rectifier, known today as the thyristor [].

Simply stated, a power electronics system is an efficient energy conversion means using power semiconductor devices . A power electronics system can be illustrated with the block diagram shown in Fig..

A special class of power electronic system s are electrical drives. A block diagram of an electrical drive is illustrated in Fig. ]. In the near future, despite the increased use of power converters in photovoltaic systems and computer power supplies, it is expected that this dominance of drives will remain. Most experts predict that the existing industrial markets for drives will continue to grow and will be complemented by newly developed markets, such as wind turbines, more electric ships and aircrafts, and electric mobility, i.e. trains, trams, trolley busses, automobiles, scooters, and bikes.