Switching Power SupplyAbstractDesign ConstraintsAdvantagesDesign Flow ChartInput Rectification CircuitSwitchingOptions for Ringing EliminationOptions for Ringing Elimination (cont’d)Snubber Circuit DesignPCB LayoutPrinted Circuit BoardSo Far:Special ThanksReferencesSwitching Power SupplySwitching Power SupplyAdvisor: Dr. Noel SchulzJeremy Stevens (EE) Frankie Runnels (EE)Dereck Lenoir (EE) Carl Jeffery Jones (EE)Sponsor: Mississippi Power CompanyAbstractAbstractThe utility companies have three different voltages ranging from 90-310 VAC that they use for their remote communications Available power supplies only offer an input voltage range of 90-265 VAC The utility companies have to either have three separate power supplies or use power tapped power suppliesMississippi Power wants universal power supply that will accept any of the voltagesMississippi Power designed a power supply to fit their needs; however, it is too noisyThe power supply has EMI problems as well as several transients on the output signalDesign ConstraintsDesign ConstraintsInput voltage ranges from 90 to 310 VACOutput voltage is a constant 13.5 VDCOutput power ranges from 0 to 40 watts The output noise level will be less than 200 mV pk-pkTotal cost should be less than $100AdvantagesAdvantages•Utility companies can use one power supply instead of three•Less training will be required since the power supply will be universal•Power supply more cost efficient than traditional power suppliesSwitchingSwitchingControllerControllerInput Input RectificationRectificationOutputOutputRectificationRectificationFeedbackFeedbackDesign Flow ChartDesign Flow ChartSurgeSurgeProtectionProtectionFlyback Flyback TransformerTransformerVACVACVDC VDCInput Rectification CircuitInput Rectification Circuit•Common Mode Inductor •Full Bridge Rectifier•RC Time ConstantSwitchingSwitchingOptions for Ringing EliminationOptions for Ringing Elimination•Soft Switching: Increases voltage on the switch gradually thus causing less stress on filter components•Snubber Circuits: Redirects the signal caused by leakage inductance on the transformer into an RCD Tank circuit for dissipationOptions for Ringing Options for Ringing Elimination (cont’d)Elimination (cont’d)•Band Pass Filter: Filters out all frequencies except the switching frequency thus eliminating unwanted harmonics•PCB Layout: Short, fat traces have lower inductances and radiate less energy at higher frequencies (Senior Design II)Snubber Circuit DesignSnubber Circuit DesignP e r i o d1 1T RC=Pick a Value of R and Calculate CConside rations:1 – Power consumption by the Resistor2 – Effects of Snubber on over all circuit EfficiencyPCB LayoutPCB LayoutPSpice SchematicImport into CapturePrint to a Layout FileAlter Traces to meet SpecificationsImport into ISOPro, Isolate, and etch circuit boardPrinted Circuit BoardPrinted Circuit BoardSo Far:So Far:Reduction in energy forced back into the MOSFETReduction in noise on the outputMaintained Acceptable EfficiencyBegan a new PCB LayoutSpecial ThanksSpecial ThanksDr. MazzolaMr. Jim GaffordMr. Even BurnettMr. Bill BuchananCingular WirelessReferencesReferencesM. Brown, Power Supply Cookbook, Butterworth-Heinemann, Woburn, MA, USA, 2001B. Seal, Senior Electrical Engineer, personal communication, August 2002R.W. Goody, Orcad pSPICE for Windows, Prentiss Hall, USA, 1997M. Herniter, Schematic Capture with Cadence Pspicce, Prentiss Hall, December 2000Dr. S. Grzybowski, Mississippi State University High Voltage Laboratory, http://www.ece.msstate.edu/hvl/geninfo.html , Dept of Electrical and Computer Engineering, Mississippi State University, MS, USA,
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