Inverter Panel is an electronic device or circuitry that changes direct current (DC) to alternating current
The input voltage, output voltage and frequency, and overall power handling depend on the design of the specific device or circuitry. The inverter does not produce any power; the power is provided by the DC source.
A power inverter can be entirely electronic or may be a combination of mechanical effects (such as a rotary apparatus) and electronic circuitry. Static inverters do not use moving parts in the conversion process.
Circuitry that performs the opposite function, converting AC to DC, is called a rectifier. An inverter can produce a square wave, modified sine wave, pulsed sine wave, pulse width modulated wave (PWM) or sine wave depending on circuit design. The two dominant commercialized waveform types of inverters as a modified sine wave and square wave.
There are two basic designs for producing a household plug-in voltage from a lower-voltage DC source, the first of which uses a switching boost converter to produce a higher-voltage DC and then converts to AC. The second method converts DC to AC at battery level and uses a line-frequency transformer to create the output voltage. This is one of the simplest waveforms an inverter design can produce and is best suited to low-sensitivity applications such as lighting and heating. Square wave output can produce “humming” when connected to audio equipment and is generally unsuitable for sensitive electronics. A power inverter device which produces a multiple step sinusoidal AC waveform is referred to as a sine wave inverter. To more clearly distinguish the inverters with outputs of much less distortion than the modified sine wave (three steps) inverter designs, the manufacturers often use the phrase pure sine wave inverter. Almost all consumer grade inverters that are sold as a “pure sine wave inverter” do not produce a smooth sine wave output at all, just a less choppy output than the square wave (two-step) and modified sine wave (three steps) inverters. However, this is not critical for most electronics as they deal with the output quite well. The inverter may be built as standalone equipment for applications such as solar power, or to work a power supply from batteries which are charged separately.
The other configuration is when it is a part of a bigger circuit such as a power supply unit, or a UPS. In this case, the inverter input DC is from the rectified mains AC in the PSU, while from either the rectified AC in the in the UPS when there is power, and from the batteries whenever there is a power failure. There are different types of inverters based on the shape of the switching waveform. These have varying circuit configurations, efficiencies, advantages and disadvantages
An inverter provides an ac voltage from dc power sources and is useful in power electronics and electrical equipment rated at the ac mains voltage. In addition, they are widely used in the switched mode power supplies inverting stages. The circuits are classified according to the switching technology and switch type, the waveform, the frequency and output waveform. The basic circuits include an oscillator, control circuit, drive circuit for the power devices, switching devices, and a transformer.
The conversion of dc to alternating voltage is achieved by converting energy stored in the dc source such as the battery, or from a rectifier output, into an alternating voltage. This is done using switching devices which are continuously turned on and off, and then stepping up using the transformer. Although there are some configurations which do not use a transformer, these are not widely used.
The DC input voltage is switched on and off by the power devices such as MOSFETs or power transistors and the pulses fed to the primary side of the transformer. The varying voltage in the primary induces an alternating voltage at secondary winding. The transformer also works as an amplifier where it increases the output voltage at a ratio determined by the turn’s ratio. In most cases, the output voltage is raised from the standard 12 volts supplied by the batteries to either 120 Volts or 240 volts AC. The three commonly used Inverter output stages are, a push-pull with centre tap transformer, push-pull half-bridge, or push-pull full bridge. The push-pull with centre tap is most popular due to its simplicity and, guaranteed results; however, it uses a heavier transformer and has a lower efficiency.
A simple push-pull DC to AC inverter with centre tap transformer circuit is a shown in the figure below. The inverters are classified according to their output waveforms with the three common types being the square wave, the pure sine wave and the modified sine wave.
The square wave is simple and cheaper, however, it has a low power quality compared to the other two. The modified square wave provides a better power quality (THD~ 45%) and is suitable for most electronic equipment. These have rectangular pulses that have dead spots between the positive half cycle and the negative half cycle