MODIFIED DISCONTINUOUS PWM STRATEGY FOR THREE-PHASE GRID CONNECTED
Abstract
The main objective of this project is to propose a MD PWM strategy for three-phase grid connected PV inverters. Compared with DPWM the MD PWM technique reduces the current leakage in PV inverters by reducing the magnitude of low-frequency harmonics present in the common mode voltage. Common-mode and differential-mode dynamics are damped by a new hybrid active-passive damping scheme. High efficiency, low cost and reduced size, the transformerless grid-connected PV inverters are widely used. Due to electromagnetic disturbances and device safety, PV systems are grounded for which there is a path of leakage current. This issue can be resolved With the help of modified DPWM so that the leakage current would be maintained below the standard limit and there would be a gradual improvement in efficiency.
Code Description & Execution For PWM strategy for three-phase grid connected
Algorithm Description
Block diagram of MD PWM strategy for three-phase grid connected PV inverters
PWM techniques are distinguished by pulses of constant amplitude and varying duty cycles for each period. To control the inverter output voltage and lessen its harmonic content, these pulses’ widths are modulated.
- first the DC power supply is given to the 3-level inverter
- the 3-level inverter is fed by MD PWM
- 3-level inverter generates the AC power output
- the generated AC power output is supplied to the grid
Model Description
There is only one file to execute :MDPWM_LOAD.slx
The above simulation is the circuit diagram of three phase grid connected system
SUBSYSTEM:
The above simulation is the circuit diagram of modified discontinues PWM
Note: Matlab file or codes are saved in .mdl and .slx format.
Steps to Execute the Code
- Download the zip file and unzip it
- Open matlab and click on simulink icon on home tab
3. Click on open when the following window pops up
4. A window pops up from which select the required file and click on open
5. The required file will be opened. Click on ‘run’ option and once the simulation is ready double click on scope to view the results.
Result for PWM strategy for three-phase grid connected
Issues Faced
- To run this simulation basic addons are required (in most cases addons will be already installed).
- There might be an error because of the version difference(this project is done on matlab version R2022a).