The field of power electronics is mainly concerned with the conversion of power from one form to another and the conversion from one voltage level to another using various power electronic converters. A number of control strategies are used in converters to assist in this conversion. Another important aspect of using power converters is conditioning.
Signal conditioning helps us ensure clean and pure, i.e. free of harmonics, input and output signals. It is not possible to obtain a perfectly clean signal, but there are ways and means of reducing the harmonic content, the simplest of which is the use of a simple low-pass LC filter.
Power electronics converters mainly consist of solid state switches, such as Power MOSFET, Power BJT, IGBT, Thyristors, etc., and lossless components, namely inductors and capacitors. Inductors and capacitors are ideally suited for use in power converters because there is zero power loss in these components compared to resistance.
Resistance leads to power loss, and thus efficiency loss, and power converters must be highly efficient because power loss during conversion reduces the efficiency of the entire system. If you want to study some technical questions on Power Electronics, check out our Basic Electronics Questions.
In power electronics, solid state devices are used as switches. They can be either on or off. They are never used for amplification. The frequency with which solid-state devices are switched on and off is called the switching frequency. The inductors and capacitors used can lead to increased weight and increased volume of the power converters leading to a decrease in the power density of the converters. This can be remedied by a higher switching frequency which reduces the size of the components used in the converter. But higher switching frequency leads to higher switching losses.
However, switching losses are small compared to transmission losses. High switching losses will lead to high temperatures at the junctions, and a temperature difference of more than 100oC between body and junction can damage the solid-state device. We can take care of this with an appropriately sized heatsink.
The main types of conversion are DC to DC, AC to DC, DC to AC and AC to AC. Using DC to DC converters to step up or step down DC voltage is a great advantage because AC voltage can be easily stepped up using a transformer but using a transformer with DC leads to core saturation. causes Eventually the transformer was damaged. The conversion of AC to DC is known as rectification which is used to supply DC loads, such as DC motors, using an AC power supply.
DC to AC conversion is called inversion and it is a very useful and important part of our daily life nowadays where we are trying to end our dependence on fossil fuels. Inverters can take power from DC sources, such as batteries, and convert them to AC power for use in AC motors as seen in Totos et al. AC to AC conversion is done by either Cycloconverters or Matrix Cycloconverters. These converters are very powerful in that they can be used for a wide range of industrial applications, such as cement and ball mill drives, rolling mill drives, etc. Cycloconverters can also convert a single-phase AC supply into a three-phase supply. and so on.
Control of converters deals with implemented logic, either with analog electronics or digital-based microcontrollers, DSP processors or FPGAs, to turn solid state devices on and off. The simplest is the Pulse Width Modulation (PWM) scheme. Control of converters becomes complicated when converters use feedback loops.