Studying the properties of semiconductors made it possible to create new elements that were actively used in various electronic circuits. More powerful devices gradually appeared, which made it possible to switch electrical circuits of high power.
A good example of this is the thyristor converter. From the moment of its appearance, it began to enjoy well-deserved popularity among designers. This device is actively used in various electrical circuits: starters and chargers, 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 "generator-engine" system that was traditional at that time.(Y-D).
Improvement of control schemes has greatly increased the reliability of these
devices. A powerful thyristor converter is capable of controlling the excitation current or being connected directly to the motor armature circuit. However, the first pulse-phase control systems (PIPS) often worked with errors. This could lead, for example, to the “tipping” of the inverter and the failure of the power elements. The constructive base also left much to be desired. Over time, these problems are gone. Reliable electronic devices have appeared that reliably control and, if necessary, protect the overload-sensitive thyristor converter. It is also necessary to note the high efficiency, good maintainability and small size of this device in relation to alternative systems.
But, in addition to good performance, such devices also have some disadvantages in relation to the power circuit:
- The ratio of reactive and active power when they are used changes not for the better for the common supply network. To save cos φ, you have to use reactive power compensators based on capacitors.
- During their operation, thyristor converters quite strongly pollute the power network with high-frequency interference. To combat this shortcoming, special R-C circuits are used.
With the help of specially designed devices, you can change thisparameter, such as the mains frequency. It is used in the operation of induction furnaces, in metal forming or in other electrical installations. This function is performed by a thyristor frequency converter specially designed for this purpose. Its creation made it possible to significantly improve the technologies of metal processing in production that existed at that time.
Over time, alternative devices have appeared that work on completely different principles. Circuits based on powerful IGBT transistors are being developed, which are more used to control small and medium power motors. They are gradually replacing obsolete systems.
