DC bus for photovoltaic power supplying computing loads

Vincent Flaherty

4th year Electronic Engineering

Project Aims

• The aim of this project is to investigate if the efficiency of power delivered from a domestic PV installation can be improved by supplying such DC loads through a DC bus instead of through an AC grid connection.

Progress to Date

• Research of PV systems.

• Review of power consumption of different loads.

• Review of PV inverters.

Progress to Date

• Investigation and PSPICE simulation of AC/DC converter.

• Full Wave Rectifier

• Flyback Converter

PV systems• PV modules convert sunlight to electricity.

• Made from semiconductor materials.

• General efficiency (6 – 20%)

• An ideal solar cell can be modelled using a current source in parallel with a diode

Power Consumption• The average power consumption for a range of electrical

devices which drive DC loads.

[Figure taken from cnet.com]

Appliance Consumption

LCD Television 213 Watts

Plasma Television 339 Watts

Playstation 3 197 Watts

Xbox 360 187 Watts

Average PC 78 Watts

Nintendo Wii 19 Watts

Wireless Router 7 Watts

PV Inverters• Used to change DC electricity to AC electricity.

• 2 main types used with PV systems.• Grid-tie inverters.• Battery backup inverters

• Solar inverters use procedures such as MPPT to deal with the PV array.

MPPT

• DC/DC converter functions as optimal load for a PV cell.

• MPPT is used by solar inverters to get the most power possible from a PV array.

• Can be used with or without batteries.

• The benefits of MPPT regulators are greatest during cold, hazy or cloudy weather.

Fullwave Rectifier

• Used to convert AC to DC.

• Most simple method of conversion.

• Quite easily simulated using PSPICE.

Fullwave Rectifier

Flyback Converter• DC/DC converter with isolation between input and

output.

• Very similar to Buck-Boost converter.

• Voltage ratios can be multiplied due to turns in transformer.

• Can operate over a wide range of inputs.

Flyback Converter

Major Challenges

• Finding circuit schematic for AC/DC adapter.

• Effective simulation of Flyback converter.

Next Steps• Finalisation of Flyback converter

simulation.

• Investigation and simulation of other DC/DC converters. (Buck, Boost etc.)

Questions?