What are Power Semiconductor Devices

Power semiconductor devices are electronic components that directly enable electrical energy conversion or circuit control in main circuits. They are primarily used for power conversion, including rectification, inversion, DC chopping, as well as AC power control, frequency conversion, or phase shifting. Unlike other types of semiconductors, power semiconductors can withstand high voltages and large currents, typically operating in switching states. They serve as the core of electrical energy conversion and circuit control, playing a crucial role in the efficient generation, transmission, conversion, storage, and control of electrical energy.

Power semiconductor devices can be classified based on carrier types into bipolar power semiconductors and unipolar power semiconductors. Bipolar power semiconductor devices include power diodes, bipolar junction transistors (BJT), power transistors (GTR), thyristors, and insulated-gate bipolar transistors (IGBT). Unipolar power semiconductor devices include power MOSFETs and Schottky diodes, among others. Their operating voltages and frequencies also differ.

Insulated-Gate Bipolar Transistor (IGBT) is a composite, fully controlled voltage-driven power semiconductor device consisting of a BJT (Bipolar Junction Transistor) and a MOS (Metal-Oxide-Semiconductor) structure. IGBTs can convert between DC and AC power or change the frequency of current, serving functions such as inversion and frequency conversion.

In terms of control types, power semiconductor devices have evolved from uncontrollable devices to semi-controllable devices, and then to fully controllable devices. Initially, silicon diodes were used in the power field, including ordinary diodes and Schottky diodes, all of which are uncontrollable devices. This was followed by thyristors, which can withstand high reverse breakdown voltages and large currents but have the disadvantage of passive turn-off, relying on external conditions, making them semi-controllable devices. In the 1960s, the turn-off capability of thyristors was achieved, leading to the development of Gate Turn-Off Thyristors (GTO). With the advancement of MOSFET technology, Power MOSFETs emerged in the late 1970s. Since then, fully controllable devices have developed rapidly, with switching speeds and frequencies generally higher than those of thyristors.

The main characteristics of power semiconductor devices include: ① Their primary function is to achieve the conversion and control of high-power electrical energy. ② The most important parameter is the power they can handle, or the voltage and current ranges they can withstand, which are typically far greater than those of general electronic devices. ③ To minimize power loss, they operate almost exclusively in switching states, controlled by dedicated drive circuits to turn on or off. ④ They generate significant heat dissipation and often require heatsinks to enhance the cooling capacity of the device or system.