Switching Megawatts with Power Transistors

K. Shenai
2013 The Electrochemical Society Interface  
S emiconductor silicon revolutionized the computing and communication industries in the last century. With the invention of the semiconductor transistor, miniaturization of electronic systems took place at an unprecedented rate. Today, everyone has access at their fingertips to computing and communication devices capable of delivering multi-megabits of data within seconds, once simply unthinkable. The advent of silicon integrated circuit (IC) technology enabled the information revolution, and
more » ... formation technology (IT) was a prime driver of the 20 th century global economic boom. With the advent of information technology, energy technology has become more critical than ever before. 1 Batterypowered, wireless handheld computing and communication devices are finding applications in every walk of life from the boardroom to the emergency room. However, further miniaturization and performance enhancement of these devices are hindered by battery size and limited storage capacity. At the same time, batterychargers are inefficient and waste nearly 25% of the electricity used. 2 Hybrid electric vehicles (HEVs) are becoming cost-effective and popular; and there is growing interest in developing all-electric transportation, especially from the perspective of environmental concerns. 3 The electricity transmission and distribution infrastructure is more than 100 years old and is in the midst of the greatest change in its history. 4 A flexible and robust smart electricity grid is needed that is capable of efficiently integrating distributed renewable energy resources, including solar and wind generators. 5 At the same time, alternative and more efficient methods of electricity delivery such as direct DC are under development and have the potential for rapid penetration of renewable energy for local utilization. 6 Fundamentals of Solid-State Energy Conversion Today, more than 80% of electrons that power electric utility infrastructure and transportation flow through a semiconductor switch that is used to convert one form of electricity into another form. This solidstate energy conversion is widely referred to as "power electronics." Power electronics constitutes the backbone of electricity transmission, distribution, and processing much like signal electronics is used for Fig. 1. A simple power electronics switching circuit showing load, switch, control, and voltage and current stresses on the switch. constructing the information highway. 7,8 Figure 1 illustrates how the load is energized from the power source using a controllable 3-terminal power switch. A voltage source, v SUP , supplies current to the load when the switch is closed by applying a control signal to the switch terminal "C." Assuming that no stray inductances and capacitances exist in the circuit, all reactive elements present in this circuit arise from the load and the switch. In most power electronic applications, the load is inductive; consequently, both the magnitude (i L (t)) and rate of change of current di L (t) dt in the load are important. For example, for motor control applications,
doi:10.1149/2.f05131if fatcat:y7xc6iku2vdflnsei4iretiwsy