adminINVERTERS
The inverter is an electrical device that converts direct electric current to alternating electric current. It is usually installed between the battery and the grid or an alternating current load. Its main duty is to convert direct electric current as supplied from a direct electric current generator or a direct electric current storage source like a battery to an alternating electric current supply or load.
Inverters are either full bridge inverters or half bridge inverters. Full bridge inverters consist of four switches, whereas the half bridge inverter consists of two diodes and two switches.
Inverters work by using switches to convert direct current (DC) electric power into alternating current (AC) electric power. The conversion from direct current to alternating current follows a four step process: in the first step the inverter receives the direct current power from a battery, solar panel or other direct current power source. In the second step, the inverter uses the switches to convert the direct current power into alternating current power. In the third step the inverter uses filters to remove any unwanted harmonics or noise from the alternating current output and in the final step the inverter produces alternating current power that can be used to power electrical devices.
Inverters are mainly classified in two classes. In The first class are the grid tied, off grid and hybrid inverters. Synchronous or grid tied inverters, which are used in utilities connected to photovoltaic and other direct current type generating systems. The second type or static inverters or off grid inverters are designed and used for independent utility supply or off grid tied systems. While hybrid inverter can be used for both grid tied and off grid connections.
The other classification of inverters is according to the waveform they produce. The three most common inverter waveforms are square wave, modified sine wave and the pure sine wave inverters.
Square wave inverters switch the direct current input into a step function or square form alternating current electric output. They provide little output voltage control, limited surge capability and considerable harmonic distortion and noise. Consequently square wave inverters are only suitable for small loads applications, such as required by incandescent lights and small appliances.
Modified sine wave inverters switch direct current to alternating current using complex circuits that can switch into a modified sine wave output. They can handle large surges and produce outputs with much less noise and harmonic distortion. This type of inverter is more suitable for operating over a wide range of loads such as lights, standard electronic equipment but not with equipment or devices prone to serve noise and harmonic distortion.
Pure Sine wave inverters are used to operate sensitive electronic devices that requires high quality waveforms. They produce little or no noise and harmonic distortion, enabling them to be employed to operate sensitive electronic equipment. They also have high surge capabilities and can be used to start many types of motors easily.
Inverters find widespread application in the following; solar power systems, uninterruptible power supplies, electric vehicles and remote power systems.
Inverters have several advantages, including; high efficiencies of above 90%, they are reliable, flexible and also cost effective.
However the main disadvantages of inverter are their complexity, excessive heat generation and noise generation.
The future of inverters will be driven by the following trends and developments: Smart inverters technologies incorporating real time monitoring, remote control and grid support. Hybrid inverters incorporating multiple energy sources like utility supply, solar supply, wind power and other energy systems simultaneously and off course, advanced control systems enabling them to respond promptly to grid network load demand. All this developments will no doubt result in increased efficiencies, reliability and optimization of the overall power system.
SOURCES:
- Inverter technology by B.K Bose.
- Power electronics and inverters by Ned Mohan.
- Inverters applications and design by Ulrich Nicolai.
- Grid forming power inverters: control and applications byNabil Mohamm.
- Electric vehicle power electronics and inverters by S.K Mazumder.
