EEEN40700 MEngSc Electrical Project
Design a new Transformerless Common-Ground PV Inverter
Project Description:
Transformerless photovoltaic (PV) inverters, particularly those with common-ground configurations, are increasingly preferred due to several advantages they offer. These include reduced electromagnetic interference (EMI) noise, elimination of leakage current, and higher efficiency compared to traditional inverters with transformers. In addition to these benefits, grid-connected PV inverters must meet specific requirements outlined by standards such as IEEE 1547-2018.
These requirements include:
a) Ability to provide reactive power to the AC grid as per IEEE 1547-2018.
b) Low active component count, which simplifies design and reduces costs.
c) High quality of converter current, meeting the standards set by IEEE 1547 and IEEE 519.
Different types of common ground inverters have been developed, categorized based on their configuration:
• Single-stage inverters: These include dc-dc converters with positive and negative voltage outputs, and variations such as flying capacitor (FC) or flying inductor (FI) inverters.
• Multi-stage inverters: These consist of a dual-output dc-dc converter combined with a half bridge (HB) inverter, and more complex designs like flying capacitor multilevel inverters.
The project aims to propose a novel structure for a PV inverter system. The proposed transformerless PV inverter is designed to eliminate leakage current, making it suitable for both on-grid and off-grid applications. Additionally, the converter ensures acceptable quality of the grid-side current and high efficiency. It incorporates a modern controller in its control loop, enabling smooth, accurate, and rapid responses.
The project involves setting up simulation model for a 500W PV inverter capable of converting 180Vdc to 110Vrms in a closed-loop system. The results obtained from this simulation will be crucial in evaluating its performance, including efficiency under varying load conditions, Total Harmonic Distortion (THD), and waveforms during steady-state and transient operations.
The tasks outlined for the project include:
1. Conducting a literature review of existing PV inverters.
2. Identifying and selecting a new PV inverter topology.
3. Analysing the operational principles of the proposed topology.
4. Performing design calculations for active and passive components.
5. Designing the control system for optimal performance.
Software Needed:
MATLAB or PLECS