December 2nd, 2008

Power MelderMidterm Presentation

About Us

ChristopherHarperEE

Power conversion electronics

Tina McGlastonCPE

Human-interfacing

Daniel WilsonCPE

Control Loops

Human-interfacing

Tyler PettitEE

Power-factor correction

Overview

Current ProblemSolutionConstraints

Practical Constraints Technical Constraints

Approach and Trade-off Analysis Power-Factor Correction DC-DC Converter External ADC Opto-coupler Microprocessor

ProgressTimelineQuestions

Current Problem

Small generators cannot power large loads.

Solution

Parallel power generation

System Overview

Bridge rectifi

er

Power factor

correction

μC

Shunt resisto

r

Fromgenerator

Outputbus

ADC

DC-DC convert

er

Master/Slave bus

DC-DC Converter Subsystem

Practical Constraint: Economic

[1]

The Power Melder must cost less than a typical consumer generator with similar capacity.

Practical Constraint: Safety

Input IsolationFusesConductor Separation

[2]

Voltage Between Conductors ( AC Peaks or DC Volts ) Minimum Bare Board Spacing

  B1 B2 B3 B4

… … … … …

301-5000.25mm (.01

in.)2.5mm (.1 in.) 12.5mm (.492 in.) 0.8mm (.0315 in.)

… … … … …

B1 - Internal ConductorsB2 - External Conductors, uncoated, Sea level to 3050m ( 10K ft.)B3 - External Conductors, uncoated, over 3050m ( 10K Ft.)B4 - External Conductors, coated with permanent polymer coating

Technical Constraints

Name Description

Input Power Must accept 90-300V DC or AC 50-200Hz

Output Power Must provide a single output DC bus between 12V and 14.5V for use with an AC inverter

Output Stability Must be stable to within 10% of nominal value with a maximum of 10% ripple

Accuracy Measured power draw and power limiting must be accurate to within 10W

Power Capability Must be capable of drawing 150W from any acceptable power source

Power Factor Correction

Boosts Input Voltage creating continuous current draw Input Power Constraint met – wide input range Power Capability Constraint met – able to draw 150W

from any acceptable power source

Power Factor Correction

Input Power Tests

Power Factor Correction

Hardware Prototype

Completed Circuit After Failure

DC-DC Converter

DC-DC Converter Simulation

DC-DC Converter Evaluation

Slave Controller

Is directly connected to DC-DC converter hardware

Responsible for maintaining voltage output of individual converter

Uses take-back-half algorithm for speedIs responsible for reporting DC-DC converter

conditions to master controller

Master Controller: Control Loop

Makes sure that the main output power bus voltage is regulated. Does this by sending increment and decrement voltage commands to individual controllers

Manages power distribution from sources. Uses settings set by user to adjust converters so that appropriate power percentage is pulled from each source

Master Controller: Rainy-day case

Master Controller: Sunny-day case

Master Controller: Human Interfacing

KEYPAD

•12 button•Programmed using the standard matrix grid (4 rows x 3 columns)

• USES: to input the desired current or voltage

Master Controller: Human Interfacing (cont.)

KEYPAD TEST

Master Controller: Human Interfacing (cont.)

LCD

• Newhaven Display (NHD-0420Z-RN-GBW) • 4 lines, 20 characters per line

USES: to display the current user input and system status

Master Controller: Human Interfacing (cont.)

LCD TEST

Master Controller: Human Interfacing (cont.)

LCD TEST

Master Controller: Human Interfacing (cont.)

LCD TEST

Design II GOALS

•Add second converter•Finish master control loop•Continue Design of User Interface

Questions?