7 - Power Semiconductor Devices

Abstract

This chapter provides an overview of power semiconductor devices as they are used as switches in power electronics applications. Ideal switches arbitrarily block large forward and reverse voltages, with zero current flow in the off-state, arbitrarily conduct large currents with zero voltage drop in the on-state, and have negligible switching time and power loss. Material and design limitations prevent semiconductor devices from operating as ideal switches. It is important to understand the operation of these devices to determine how much the device characteristics can be idealized. Available semiconductor devices could be either controllable or uncontrollable. In an uncontrollable device, such as the diode, on-and off-states are controlled by circuit conditions. Devices like BJTs, MOSFETs, and their combinations can be turned on and off by control signals, and hence, are controllable devices. Thyristors belong to an intermediate category defined by latch-on being determined by a control signal and turn-off governed by external circuit conditions. This chapter presents a summary of the design equations, terminal characteristics, and the circuit performance of contemporary and emerging power devices.