The study of the properties of semiconductors has allowed the creation of new elements that have become actively used in various electronic circuits. Gradually, more powerful devices appeared that allowed switching high-power electric circuits.
A good example of this is a thyristor converter. Since its inception, he began to enjoy well-deserved popularity among designers. This device is actively used in various electrical circuits: starting and charging devices, welding machines, heaters, inverters,
controlled rectifiers etc. This is not a complete list of devices that use a thyristor converter.
Over time, powerful devices appeared, with the help of which it became possible to control the speed of electric motors or thermal installations. They began to be actively used in production, and in some cases even replaced the then-traditional generator-engine (GD) system.
Improving control schemes has significantly increased the reliability of these
devices. A powerful thyristor converter is able to control the excitation current or to be connected directly to
the motor
armature circuit . However, the first pulse-phase control systems (SIFU) often worked with errors. This could lead, for example, to the βoverturningβ of the inverter and the failure of the power elements. The structural base also left much to be desired. Over time, these problems are a thing of the past. Reliable electronic devices have appeared that reliably control and, if necessary, protect the thyristor converter sensitive to overloads. It should also be noted high efficiency, good maintainability and small dimensions of this device in relation to alternative systems.
But, in addition to good operational characteristics, such devices have some disadvantages with respect to the power circuit:
The ratio of reactive and active power when using them does not change for the better for the general supply network. To maintain cos Ο, one has to use reactive power compensators based on capacitors.
During their operation, thyristor converters strongly pollute the power network with high-frequency noise. To combat this drawback, special RC circuits are used.
Using specially designed devices, you can change such a parameter as the frequency of the mains. It is used in the operation of
induction furnaces, in the molding of metals or in other electrical installations. This function is carried out by a thyristor
frequency converter specially developed for these purposes
. Its creation made it possible to significantly improve the existing technologies for metal processing at the time.
Over time, alternative devices appeared that work according to completely different principles. Schemes based on powerful IGBT transistors are being developed, which are more used to control low and medium power motors. They are gradually replacing obsolete systems.