DC to AC Inverter

The main function of an inverter is to convert current voltage e.g. DC to AC or direct current voltage to alternating current voltage. In most instances DC voltage becomes high voltage. In this converter, the voltage of the DC converts in alternating suitable voltage. The wave changes from square to sinusoidal shape. DC-AC inverters are electronic devices used to produce ‘mains voltage’ AC power from low voltage DC energy (from a battery or solar panel). This makes them very suitable for when one needs to use AC power tools or appliances with regulating voltage, e.g. caravans, mobile homes, running audio, video and computing equipment in remote areas.

There are two main steps:

1. It converts the incoming DC into AC
2. It sets up the resulting AC to mains voltage level using a transformer.

Usually there are two metal oxide semiconductor field effect transistors (MOSFET) used as well-organized switches. The DC voltage provided from the battery source can be renovated into AC voltage quite easily as the whole circuit is controlled by fuses. Whenever the fuse is be on then activity begins. Connecting the source battery with the primary transformer, the connections of both MOSFETs need to join with the primary transformer and the ground level. Whenever the first MOSFET (Q1) will is switched on, DC current will be followed through the primary transformer, and if over current is appeared anytime that will be sent to the ground through ground. Similarly, whenever MOSFET (Q2) is switched on from the bottom, the second half circuit will be complete. MOSFET is used in this way as the electronic switch to convert the DC into AC. As the MOSFETs are being simply turned on and off, the pure sine wave cannot be made a regular pulse. The resulting waveform then is usually called a “modified sine wave” and as the RMS voltage is close to 230 V most AC tools and appliances are able to operate from such a waveform without problems.

The use of the Inverter

The use of the inverter when connected to a 12V outlet in your car, truck, boat, RV or directly from a dedicated 12V battery, is to efficiently and reliably power a wide variety of household AC products namely portable stereos, laptop computer, TVs, VCR, and other similar products. The inverter has used reliable solid-state power electronics for years ensuring a trouble-free operation and includes the following automatic features to ensure safety is always achieved, which are listed below:

• Low battery alarm
• Low voltage shutdown
• High voltage shutdown
• Overload shutdown
• Overheating shutdown
• Short circuit protection
• Maximum safety

Sine Wave Inverters

As mentioned earlier, most DC-AC inverters deliver a modified sine-wave output voltage, because they convert the incoming DC into AC by using MOSFET transistors as electronic switches. This gives very high conversion efficiency, but the alternating pulses. Output waveform is also relatively rich in harmonics. Some appliances are less than happy with such a supply waveform; however examples include light dimmers, variable speed drills, sewing machine speed controls and some laser printers.

Because of this, inverter manufacturers do make a small number of models, which are designed to deliver a pure sine wave output.

Generally speaking these inverters use rather more complex circuitry than the modified sine-wave type, because it is hard to produce a pure sine wave output while still converting the energy into AC efficiently. As a result pure sine-wave inverters tend to be significantly more expensive, for the same output power rating.

The most common type of pure sine-wave inverter operates by first converting the low voltage DC into high voltage DC, using a high frequency DC-DC converter. It then uses a high frequency PWM system to convert the high voltage DC into chopped AC, which is passed through an L-C low-pass filter to produce the final 50 Hz sine-wave output. This is like a high-voltage version of the single-bit digital to analog conversion process used in many CD players.