Download Power Melder Midterm Presentation

Power Melder
Midterm Presentation
December 2nd, 2008
About Us
Christopher
Harper
EE
Tina
McGlaston
CPE
Power
conversion
electronics
Humaninterfacing
Daniel Wilson
CPE
Tyler Pettit
EE
Control Loops
Power-factor
correction
Humaninterfacing
Overview
 Current Problem
 Solution
 Constraints
 Practical Constraints
 Technical Constraints
 Progress
 Test Plan
 Questions
Current Problem
 Small generators cannot power large loads.
Solution
 Parallel power generation
System Overview
DC-DC Converter Subsystem
Master/Slave bus
ADC
Bridge
From
generator rectifier
μC
Power
factor
correction
DC-DC
converter
Shunt
resistor
Output
bus
Practical Constraint: Economic
 The Power Melder must cost less than a typical
consumer generator with similar capacity.
[1]
Practical Constraint: Safety
 Input Isolation
 Fuses
 Conductor Separation
Voltage Between Conductors
( AC Peaks or DC Volts )
Minimum Bare Board Spacing
B1
B2
B3
B4
…
…
…
…
…
301-500
0.25mm (.01 in.)
2.5mm (.1 in.)
12.5mm (.492 in.)
0.8mm (.0315 in.)
…
…
…
…
…
B1 - Internal Conductors
B2 - 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
[2]
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
Human Interfacing
• User Interface
• 4 line x 20 character LCD
• 12-key keypad for input
• User interface will allow the user input various
information about the generators in use.
Human Interfacing
 6 Menus/Screens
 Home
 Generator
 Mode
 Sharing
 Power
 Done
 # always takes user to Home menu
 * serves as ENTER button
Human Interfacing
 Home Menu
 Displays operating mode of each generator
 Displays output power of each generator
 Displays total power of system
Human Interfacing
 Generator Menu
 Allows user to select which generator to configure
 User can always hit # to cancel and go back to Home Menu
Human Interfacing
 Mode Menu
 Allows user to select whether the generator selected will
operate in Sharing, Primary, or Backup mode
 User can always hit # to cancel and go back to Home menu
Human Interfacing
 Sharing Menu
 Allows user to set sharing percentage of selected generator
 User can always hit # to cancel and go back to Home menu
 User must hit * after finished
Human Interfacing
 Power Menu
 Allows user to set maximum power to draw from selected
generator
 User can always hit # to cancel and go back to Home menu
 User must hit * after finished
Human Interfacing
 Done Menu
 Updates generator information and redirects user to Home
menu
Human Interfacing
 User Interface Demo
Power Factor Correction
First Hardware Prototype
Completed Circuit
After Failure
Power Factor Correction
 Re-constructed circuit
 Several failures
 Attempted to order new
PFC chip (ML4821)
 Removed PFC from
design
 Lost Input Voltage
Range Technical
Constraint
PCBs
Rectifier +
Rectifier -
Layout for DC-DC Converter PCB
PCBs
 Layout for Master
Controller PCB
PCBs
 Power Melder PCBs
Converter PCB
Master Controller PCB
Populated Master
Controller PCB
Enclosure
Parts for Power Melder Enclosure
Test Plan - Subsystem
 Subsystem testing
 Converter
different input voltages
 too little power
 different and varying loads


Master controller
keypad
 LCD
 different menu selections

Test Plan - System
 Test with…
 one source (each converter)
 failing source (not enough power capability)
 different operation modes
Primary/backup
 Percent sharing



varying loads
varying input voltages
 Questions?