Electrical devices that are designed to reproduce and to further enhance the quality of electricity coming from the main power lines are classified as a Sinewave Inverter. Technically, inverters transform direct current (DC) from batteries to alternating current (AC) to power conventional electrical devices.
The resulting AC can be made available depending on the required frequency and voltage using suitable transformers, control and switching circuits. Inverters are actually high-power electronic oscillator. It performs the reverse function of converters or rectifiers. Three kinds of waveforms are produced by inverters; the square wave being the simplest and are now obsolete; the other two being the modified sine wave and true sine wave. Sine wave is of better choice as compared to the square wave although it is not that easy to generate. The sine wave has an advantage of having soft temporal rise in amplitude or voltage and the absence or minimal presence of harmonic oscillations. These harmonic oscillations, if present, can cause undesirable forces that can add noise or interference to the equipment.
Considering the modified or quasi-sine inverters, it is known as the second generation of power inverter. Modified sine wave inverters are a compromise between the low harmonics of the waveform quality and the high cost of the true sine wave inverter. Modified sine wave inverters can run stereos, TV's, induction motors, computers, microwaves, etc. It has harmonics that is low enough not to cause problems with the common household appliances. Though useful, it has its disadvantage; its peak voltage varies in relation to the battery voltage. In effect, appliances or equipments with compromised or no power supply regulation may erratically behave when the supply or battery voltage fluctuates. It is much cheaper as compared to the other type.
Pertaining to the true or pure sine wave inverters, it is the modern form of inverter. It is called pure because it enables cleaner running system. The design and construction of this inverter totally eliminated the harmonics and almost all appliances operate correctly with this type of inverter. Moreover, utilizing this kind of device reduces noise in the TV sets, audio amplifiers etc.
Comparing the waveform it produces to the waveform that the power lines deliver, it delivers the same, if not better than the latter. Because of the duty and quality of waveform it produces, it is comparatively more expensive than its modified counter part. Pure sine wave inverter is the choice for utilization of most sensitive electronic devices.
In terms of the type of equipment available on the market, the potential purchaser is faced with the paradox of choice - the more devices and brands there are, the more difficult it is to make an informed decision based on the required criteria.
