This project is based on a cascaded H bridge inverter and various topologies. Inverters are mainly used for commercial and industrial purposes. The unique structure of the multilevel inverter is low harmonics in output voltage. There are different types of multilevel inverters. Among these Cascaded multilevel inverters have drawn tremendous interest in the power industry because it requires fewer components. As the number of levels increases the harmonic content of the output voltage waveform decreases. This Cascaded H-Bridge fifteen-level inverter with a minimum number of switches. As the level increases the synthesized output waveform has more steps that produce a staircase wave that approaches desired waveform. The problem of switching losses and power losses can be eliminated with a minimum number of switches.
The multilevel inverter provides a suitable solution for medium and high power systems to synthesize an output voltage which allows a reduction of harmonic content in voltage and current waveforms. The solar photovoltaic (PV) modules directly convert the light energy into electrical energy, but energy obtained from the PV module acts as a low voltage DC source and has relatively low conversion efficiency. In order to improve the efficiency and convert low voltage DC source into usable AC source, the power electronics converters are used to transform DC into AC.
In normal fifteen level cascaded inverter is required for 28 switches to produce the fifteen-level output. And also required for 7 sources. If 28 switch means the PWM pulses are generated complicated. So this 15 level inverter is used to less number power switches.
This project proposed a Cascaded Multilevel Inverter with a reduced number of switches and the switching losses are also get reduced with reduced total harmonics distortion (THD). And also easy to control the voltage of the multilevel inverter. ( cascaded h bridge multilevel inverter )
Block Diagram Explanation
- Pulse generator: – Here we have used a PIC microcontroller (PIC 16F877A) to make a switching signal.
- Driver circuit: -It can be used to amplify the pulses and provide isolations by using an optocoupler. It has two functions,
- Bridge Rectifier: It converts AC to DC Supply.
- Inverter: It converts DC to AC Supply.
Pic Controller Board
The pic controller is used to generate the PWM pulses for the converter and inverter circuits. The pic controller pulses are given to the driver circuit as input. Driver board is mainly used to isolate and amplify the input signals from the controller. The amplified driver output will be connected to the main power circuit devices. And the devices are turned on by using the PWM pulses. The power transformer is directly connected to the bridge rectifier. The bridge rectifier converts the ac voltage into a dc voltage. Dc voltage is converted into ac voltage by using a multilevel inverter circuit. The Cascaded Multilevel Inverter output waveform is shown below. – cascaded h bridge multilevel inverter
Circuit Diagram For Dc To Ac Fifteen Level
- Reduce the switching loss.
- High efficiency.
- Reduced THD.
- Reduced number of switches.
- Industrial machines
- Automobiles medical equipment
- Household appliances
- High Power Applications
In this project Cascaded Multilevel Inverter, it reduces the uneven degradation of power switches, switching losses when compared to the conventional PWM technique, and harmonics are reduced and the output waveform level is increased. And also increase the efficiency.
Multilevel Inverter Output