31-03-2012, 12:53 PM
DC/AC Pure Sine Wave Inverter
inverters.pdf (Size: 5.32 MB / Downloads: 132)
Introduction
This report focuses on DC to AC power inverters, which aim to efficiently transform a DC power
source to a high voltage AC source, similar to power that would be available at an electrical wall outlet.
Inverters are used for many applications, as in situations where low voltage DC sources such as batteries,
solar panels or fuel cells must be converted so that devices can run off of AC power. One example of
such a situation would be converting electrical power from a car battery to run a laptop, TV or cell
phone.
Problem Statement
In the market of power inverters, there are many choices. They range from the very expensive to
the very inexpensive, with varying degrees of quality, efficiency, and power output capability along the
way. High quality combined with high efficiency exists, though it is often at a high monetary cost. For
example, Samlex America manufactures a 600 W, pure sine wave inverter; the cost is $2892. Meanwhile
GoPower manufactures a 600 W inverter with a modified sine wave output (closer to a square wave); this
model only fetches $693.
DC and AC Current
In the world today there are currently two forms of electrical transmission, Direct Current (DC) and
Alternating Current (AC), each with its own advantages and disadvantages. DC power is simply the
application of a steady constant voltage across a circuit resulting in a constant current. A battery is the
most common source of DC transmission as current flows from one end of a circuit to the other. Most
digital circuitry today is run off of DC power as it carries the ability to provide either a constant high or
constant low voltage, enabling digital logic to process code executions.
Inverters and Applications
Power inverters are devices which can convert electrical energy of DC form into that of AC. They
come in all shapes and sizes, from low power functions such as powering a car radio to that of backing
up a building in case of power outage. Inverters can come in many different varieties, differing in price,
power, efficiency and purpose.
Filter Design
The other major obstacle in the implementation of this project was the design of the filter, the original
design was a simple one pole inductorcapacitor
low pass filter designed for passing all signals under
50kHz. When first breadboarding the circuit the team used low voltage, low power capacitors and
inductors that were available in the WPI ECE shop.
Putting the Design to Work
After the successful debugging of the breadboarded circuitry it was time to transfer this work to a
PCB board. Using the full schematic in Appendix B and Eagle PCB program the team was able to
construct the circuitry for a PCB board and have it made so that the team could piece together the entire
circuit on a neat board. The full plans for the PCB board are located in Appendix D.