What is an inverter, and how does it work?

Inverter is the device, scheme, or system that creates alternating current by connecting the DC source. There is another way to define: an inversion – the inverse function of rectification. Rectifiers convert alternating current into a constant, and the inverters on the contrary, make the DC voltage to AC.

Inverters are not rare device. Under other names, they appear in numerous applications. Inverters, of course, you can call and vibration transducers and generators of feedback, and relaxation oscillators. Do they make the DC voltage to AC? In fact, using the names “inverter” and “generator” is somewhat arbitrary. The inverter can be the generator and the generator can be used as an inverter. Usually preferred to use the term “inverter”, when the operating frequency was less than 100 kHz, and the operation performed by them ensures variable voltage circuit or some other equipment. Modern inverters have no restrictions on the frequency.

Because there is no clearly defined border between the inverters and generators, we can say that many inverters are the generators of a special type. Other inverters can essentially be controlled by switches or amplifiers. The choice of the term actually depends on how apart the accents. The scheme creates a radio-frequency oscillations with relatively high frequency stability have traditionally identified themselves as a generator. Scheme generator, which focuses on parameters such as efficiency, the ability to control and overload capability, and which has a range of sonic or infrasonic frequencies, can be called an inverter.

In practice, when we look at the final destination of the scheme, differences between the inverters and generators are fairly obvious. Appointment of the scheme immediately tell us how to more accurately call it: a generator or inverter. Typically, an inverter is used as a power source.

The inverter feeds the energy from DC source and produces an alternating voltage and a rectifier connected to an AC voltage and a constant voltage at the output. There is a third option – the scheme or system draws power from the DC source and provides also a constant voltage to the load. A device that this operation is called a transducer. But not any scheme that has a constant input voltage and constant output voltage, the converter can be considered. For example, potentiometers, voltage dividers, attenuators and actually “convert” a constant voltage level to another. But they generally can not be called transducers. Here, in the process of the conversion is not an element of the inverter, vibrator, or a generator. In other words, the process of this converter is as follows: DC voltage – AC – DC voltage. Convenient is the following definition of the converter: a scheme or system that consumes and delivers power to a DC voltage, which is an intermediate process in the transfer of energy is used to generate an alternating voltage (sometimes used the expression dc-to-dc converter.)

Practical value of determination of the converter is that the converter operates essentially as a constant voltage transformer. This feature allows you to manipulate the levels of DC voltage and current as well as it is done using transformers in systems with alternating voltage. In addition, such a converter transformer provides isolation between input and output circuits. This contributes to electrical safety and simplifies a number of problems when designing systems. Consider a transmitter with an additional operation. Assume that the complete sequence of operations is as follows: AC voltage, DC voltage, AC voltage, DC voltage. This means that the device gets its power from an AC voltage, rectifies this voltage, inverts it to AC voltage, rectifies and again. This is the basic principle of the many sources of supply. Is this not unreasonably excessive? No, so far as the inversion of the alternating voltage generated has a much higher frequency than the frequency of the network, eliminating the bulky and expensive transformer, designed for the frequency of the network. Transformer inverter (operating at frequencies from 20 kHz to several MHz) is very small and provides complete isolation.