In this case, a rectifier is often included to convert the AC power in the mains power system into the DC power. In contrast, AC drives mostly use an inverter to adjust the voltage and frequency in the AC power, which will be also described in more detail in Chapter 7. The power electronic converter may be determined according to the given power source and the driving motor.įor DC drives, power electronic converters such as a controlled rectifier or a chopper can be used to adjust the DC power, which will be described in more detail in Chapter 2. Power electronic converters play the role of taking electrical energy from the power system and turning it into a suitable form needed by a motor. Sang-Hoon Kim, in Electric Motor Control, 2017 1.4.3 Power Electronic Converters This approach is valid for the two main topologies found on the grid: Two-level voltage source converter (VSC) and modular multilevel converters (MMC). Some general ideas are first recalled for the grid-following converter, but more focus is made on the grid-forming control. The general idea of this chapter is to start from the fundamental concepts of active power management in the grid with a voltage source to propose a classification of different types of controls for power electronic converters based on fundamental thinking. This is the concept of grid-forming control. It is likely that some converters will need to switch from current source mode to a voltage source mode. However, with the increase of these power electronic converters, this becomes less true. It assumes that the grid is strong enough to behave as a voltage source at the point of common coupling of the converter. Indeed, the power electronic converters are connected to the grid as current injectors (i.e., they are controlled based on the grid-following concept). Moreover, it is likely that the type of connection currently used will not be sufficient in the future. The influence of power electronic converters in the grid cannot be neglected anymore also many studies confirm the good behavior of the new grids comprising a high rate of these new devices. Beside renewables, the development of many projects of high-voltage direct current (HVDC) links also increases the impact of power converters on the grid. At the same time, photovoltaic energy started also to grow with an obvious mandatory direct current ( DC)/alternating current (AC) conversion, which requires a power electronic interfacing. The connection of wind turbines with power electronic converters became compulsory also to optimize the aerodynamic power conversion.
Very quickly, the power of the wind turbine increased and more rules were imposed, for example, voltage ride-through capability, injection of reactive power. Indeed, in the old small wind turbines, the mechanical power was converted to electrical power thanks to induction machines directly connected to the grid. The beginning of the renewable energy story had a moderate influence on the power electronic converters market. One of the major applications is the drive of electrical machines mainly used in the beginning for industrial applications, and now propagated in many household appliances. Power electronic converters have been developed for several tenths of years with many types of applications. Taoufik Qoria, Xavier Guillaud, in Converter-Based Dynamics and Control of Modern Power Systems, 2021 8.1 Introduction It is also worth noting that the progress in speed and efficacy of information and power processing in modern PWM converters makes them nearly ideal power amplifiers. Switching functions, which stress the discrete character of power electronic converters, and space vectors of voltage and current, are convenient tools for analysis and control of these converters.
The same observation applies to hard-switching converters, although the soft-switching ones will certainly increase their market share. It seems that phase-controlled rectifiers and ac voltage controllers will maintain their presence in power electronics for years to come.
Pulse width modulated converters offer better operating characteristics than the phase-controlled ones, but the very process of high-frequency switching creates undesirable side effects of its own. The described variety of power electronic converters allows efficient conversion and control of electrical power. TRZYNADLOWSKI, in Control in Power Electronics, 2002 1.6 CONCLUSION
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