Download Technical Approach

Objectives
The ISU Senior Design Laboratories have power
supplies which the students can use to test their
designs. However, these supplies are limited in number
and capability. Therefore, the group will design and
implement new power supplies for the Senior Design
Laboratories.
•Convert AC wall power to a constant DC voltage
Functional Requirements
•3 sets of voltage outputs
•Voltage outputs of +1.5, +3.0, +4.5, +5.0, +6.0, +9.0, +12.0, +15.0, +18.0, and +24.0V
Design Constraints
General Background
•Needs to be from $25 to $50 per supply
•Inexpensive, reliable power supplies that can provide a wide range of voltages are
needed to replace the present power supplies
•Must provide voltage to within 1.2% of target voltage
•Voltages should correspond to common battery voltages to provide accurate
simulation
•Must conform to UL or equivalent safety specifications
Technical Problem
Measurable Milestones
•Must be able to provide three separate voltages simultaneously
•Transformer construction
•Power supplies must conform to safety specifications
•Provide 1 voltage within ½% from 0 to full load
•Voltages must remain with ½% of target voltage
•Provide cell voltages within ½% from 0 to full load
Operating Environment
•Limit current to 1 Amp or less
•Should be easy and convenient to use
•Make voltages selectable
•Power supplies will be used in indoor labs
•Must be able to withstand small to medium amounts of mechanical stress and
prevent catastrophic failure if a student connects the terminals backwards or shorts
the supply out
•Put all parts in robust case
End Product Description
Intended Uses and Users
•Fairly lightweight and compact
•It will be used in Senior Design Laboratories for testing products
•Provide selectable voltages needed in any combination to within ½%
•To be used by students/faculty with at least a basic understanding of electrical theory
Assumptions
•The supply will be used indoors at room temperature
Limitations
•The supply cannot provide more than 1 Amp per terminal
•Want to keep production cost between $25 and $50
Technical Approach
•Use transformer to get desired voltage
•Put multiple taps on transformer to get other voltages
•Regulate main voltage, others should follow
•Limit current by controlling duty cycle
23%
Item
Estimated Cost
Poster
$50
Parts
$50
Total
$100
•Rectify: Convert AC signal to DC
Peter 73 hours
26%
Erik 77 hours
Joel 63 hours
23%
28%
Philip 65 hours
Clients:
Group May03-22 Team Members:
•Dr. John W. Lamont
•Peter Holm, CprE
•Ralph E. Patterson III
•Erik Johnson, EE
Advisor:
•Dr. Allan Potter
•Joel Jorgensen, EE
•Philip Schulz, EE
•Test each combination of voltages over a wide range of loads, monitor actual voltage
and current
•Make sure selectors work properly