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?