Power semiconductor devices: diodes and thyristors, their types and applications

Power semiconductor devices - elements that are used in electric energy converters and in power plant circuits, are an integral component of both direct and alternating current circuits. They play the role of rectifiers or blockers that prevent switching overvoltages. Most often, these details are found in the designs of powerful turbine generators, galvanic plants, low-voltage welding devices, synchronous compensators, electric generators of cars and tractors.

Varieties of popular power diodes

Power diodes are classified into low-frequency and frequency. The first can have a pin, tablet and avalanche versions. Silicon is used to produce such elements. Modifications are used in circuits with a frequency of up to 500 Hz. They can withstand vibration and repeated shock for a short time.

Power diodes are used at frequencies from 2000 Hz and more. They are intended for installation schemes requiring fast reverse recovery and low charges. Their feature is the ability to withstand high loads. Their execution can be pin and tablet.

Where are power diodes used?

Various industrial installations can not do without the use of both versions of power diodes. Their applications depend on the purpose and features of the technology. Elements are embedded in schemes:

• unmanaged and semi-automatic rectification bridges;

• welding machines and inverters, characterized by high and low power;

• powerful electric drives of industrial equipment and vehicles;

• rectifiers of electrolysis and galvanic devices;

• equipment used in metallurgy;

• uninterruptible power supplies.

Power diodes are unmanaged electronic keys. They are distinguished by one-sided conductivity. The conductive state of the elements acquire when exposed to direct voltage. Semiconductors are designed for currents above 10 amperes. When choosing them, it is necessary to take into account the type of execution and technical specifications.

The correct solution will help prevent overvoltage during the switching process, increasing currents that cause external or internal short circuits, overheating of devices, and the negative impact of interference.

Thyristors: operation and varieties

These are semiconductor devices designed to equip rectifiers, inverter devices, switching regulators, generator excitation lines. Based on the type of thyristors, they are used in pulse-width start-up circuits or in contactless devices. They effectively cope with the tasks of controlling the speed of electric rolling stocks, and the protection of welding equipment.

Low-frequency devices can withstand the influence of sinusoidal vibrations in the range up to 100 Hz. They are not afraid of multiple loads lasting 2-15 ms. Increased load resistance have high-speed thyristors.

They are indispensable in installations requiring short-term on and off. Such elements are distinguished by their ability to withstand critical rates of voltage increase when closed and current pulses when open.

Common thyristor models are used:

• in the formation of direct or alternating current circuits in a variety of electrical installations and electronic devices;

• equipping high-power compensators, regulators and converting mechanisms of traction substations, synchronous electric motors, electric arc furnaces;

• complete sets of electric welding and melting equipment, electric vehicles, UPS, power plants;

• designing other converters.

When choosing semiconductor devices created on the basis of a single crystal having three pn junctions, it is necessary to pay attention to the number of conclusions. By this value, they are classified into diode, triode and tetrode.

The second important point is the principle of operation of power devices. It can be symmetric (current flows in both directions) and asymmetric (pulses travel in one direction).

Devices of the first type are able to function with positive and negative indicators. The individual selection parameters are the maximum permissible forward and reverse currents, the level of voltage drop, the degree of the control signal, the dissipated power, which determines the strength of the connected loads.