December 2nd, 2008 Power Melder Midterm Presentation

About Us Christopher Harper EE Power conversion electronics Tina McGlaston CPE Human- interfacing Daniel Wilson CPE Control Loops Human- interfacing Tyler Pettit EE Power-factor correction

Overview Current Problem Solution Constraints  Practical Constraints  Technical Constraints Approach and Trade-off Analysis  Power-Factor Correction  DC-DC Converter  External ADC  Opto-coupler  Microprocessor Progress Timeline Questions

Current Problem Small generators cannot power large loads.

Solution Parallel power generation

System Overview Bridge rectifier Power factor correction μC Shunt resistor From generator Output bus ADC DC-DC converter 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 Isolation Fuses Conductor Separation [2] Voltage Between Conductors ( AC Peaks or DC Volts ) Minimum Bare Board Spacing B1B2B3B4 …………… mm (.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

Technical Constraints NameDescription Input PowerMust accept V DC or AC Hz Output PowerMust provide a single output DC bus between 12V and 14.5V for use with an AC inverter Output StabilityMust be stable to within 10% of nominal value with a maximum of 10% ripple AccuracyMeasured power draw and power limiting must be accurate to within 10W Power CapabilityMust 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 CircuitAfter 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 speed Is 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?