DC-AC/DC Power Inverter - Electrical Engineering …

1 DC-AC/DC Power InverterTeam Not PlatypusMatthew BrownHenry GodmanJohn MartinezDylan PaitonMatthew PaizMay 12, 2010 AbstractAn intelligent DC-DC/AC converter system was designed and implemented in the Spring of 2010for New Mexico Tech s Junior Design Class. The intelligent converter draws Power from twoenergy harvesters; a 400W-12V Sunforce Wind Generator and a 60W-12V Sunforce Solar PV Power is stored in an Optima 12V sealed lead acid battery. The Inverter is comprised of fivemajor subsystems: smart battery charger, Inverter , measurement system, data logger and internetinterface. Components were selected through decision matrices and purchased online or procuredthrough the Electrical Engineering department at NMT.

2 Circuits were designed in Protel 99SE andcreated from etching and milling processes. Data was sent via HTTP to the EE server on the NMTcampus and displayed real-time information on a web page. Operation of each subsystem wasdemonstrated independently and in would like to take a moment to thank the following people for all of their help on this Erives gave us constant guidance, constructive critique and useful advice throughout thesemester. Dr. Jorgenson was kind enough to let us figure out how to use his milling machine withno prior experience. Dr. Wedeward and Dr. Rison both helped us with their expertise when weran into walls.

3 Norton was a great resource this semester. He let us use materials from his shopand found exactly what we needed more than a few times. David Park helped with the initialsetup of the milling machine. Andy Tubesing and Chris Pauli were always available to help us getall the miscellaneous parts that made our project a success. Dr. Erives Dr. Jorgensen Dr. Wedeward Dr. Rison Norton Euart David Park Andy Tubesing Chris Pauli2 Contents1 Introduction82 Background93 Design and Design .. Components and Field Testing .. Generator .. Generator Regulation Data .. Array .. Panel Regulation Data .. to DC/AC Power Inverter .

4 Battery Charger .. Logger Subsystem .. Subsystem .. Interface .. Description .. Work .. 34 Bibliography354A Code For Data Logger38B Code For Internet Interface485 List of Power Functions .. Matrix for Data Logger .. Matrix for Internet Interface .. 326 List of One Schematic of Intelligent converter .. of Various Waveforms .. Diagram of The SG3524 IC .. Schematic for Inverter Circuit .. Stage .. Stage .. Stage Output .. Inverter Circuit .. Stage Charge .. Battery Trickle Charger Results .. Protel PCB Schematic.

5 Real Time Voltage .. Client Mode Operation .. Example of Various Waveforms .. Protel Schematic .. Measurement Circuit Prototype .. Progress Comparison For Each Subsystem .. 347 Chapter 1 IntroductionToday we are seeing a fast growing availability of renewable energy harvesters. While the energyconversion process of these devices produces little to no pollution, the Power that is generated isoften intermittent and unreliable. This is best exemplified by the wind generator and photovoltaic(PV) solar cells; both work well while the wind is blowing and the sun is shining, but fail to pro-duce when they are not.

6 The purpose of this project is to try to take those two sources and make apower system that can provide, at least somewhat, a more stable source of energy. To accomplishthis, our team has designed a system where the energy produced from both of these sources isstored into a sealed lead acid battery. An Inverter is connected in series with this battery, produc-ing 120 VAC at 60Hz to emulate wall Power . Power and signal characteristics will be measured,logged, and displayed in real time on the Electrical Engineering server at New Mexico Tech. Theproject design was implemented according the specifications for the spring 2010 EE382 guidelines[1].

7 The following paper outlines the system we developed. First we describe the background ofintelligent chargers, and then we discuss each individual subsystem in detail. For symmetry,we included individual conclusions for each subsystem, stating its current progress. There is anoverall conclusion at the end of the paper as well, which gives a broader overview of the status ofthe project. The scope of this project was to develop a working prototype for the Inverter was suggested about three fourths of the way into the project that we develop an enclosure forthe system as well, but a working prototype with proper output was the primary 2 BackgroundIntelligent Inverters are currently available on the market.

8 Microchip Technologies provides adetailed list for the functions of an intelligent Inverter (below).Digital On/Off control for low standby powerPower supply sequencing and hot-swap controlProgrammable soft-start profilePower supply history logging and fault managementOutput voltage marginingCurrent fold back controlLoad sharing and balancingRegulation reference adjustmentCompensation network control and adjustmentFull digital control of Power control loopCommunications for status monitoring and controlAC RMS voltage measurementPower factor correctionTable : Intelligent Power FunctionsThey are designed for both grid-tie and off the grid applications.

9 They operate much like uninter-ruptable Power supplies (UPS). The main goal is be able to supply Power to a load directly froma main Power source, be it a generator or a wall outlet while available and continue to provideconstant Power when that main source of Power goes range of technologies is implemented to meet the functions listed above. Computers, microcon-trollers and FPGAs are all currently used to manage these sorts of systems. Square wave, modifiedsine wave and pure sine wave inverters are all implemented as well, depending on the load re-9quirements. Analog circuitry exploiting timers and op-amps are used to measure voltages andcurrents on these systems.

10 ICs are also becoming more and more popular as devices are moreavailable for high Power applications. The same is true for battery charging circuitry. While thetechnology exists to easily display data about the system online, it is not employed all of the functions above is beyond the scope of this project. For this design, our teamwill provide a proof of concept for an intelligent Inverter system that can log data online in realtime. The budget for the project was $400. Because of this limited budget, cost was a major factorwhen selecting 3 Design and Overall DesignOur intelligent converter will contain five major subsystems.