Power Management System Hardware Milestone: 0 Software Milestone: 0 Requirements: Interface with the existing bicycle battery voltage (35-40V typical) Provide stable, well-regulated power to each EBM subsystem Automatic shutdown at low voltage level (35V) Additional Aspirations: Avoid wasting battery power with high efficiency design Minimize complexity Objectives: 1.Identify all voltage/current needs from subsystems 2.Identify subsystem I/O software requirements 3.Develop “Power Budget” and battery charge life 4.Research specific solutions and identify component candidates 5.Design and model hardware schematic 6.Alpha test under laboratory conditions 7.Integrate into EBM subsystems and measure performance

Power Management System Hardware Milestone: 0 Solution Method Decision Matrix Voltage DividerLinear RegulatorDC-DC Buck Converter EfficiencyHorrible (scales)Poor (~60-70%)Excellent (~90%) RegulationHorribleExcellentGood Part CountExcellent Horrible Design ComplexityEasy Difficult Biggest DrawbackNo regulationInefficiencySwitching Noise Software Milestone: 0 Specific power supply parts have not yet been selected pending other subsystem part selection

Power Management System Hardware Milestone: 0 Software Milestone: 0 Requirements from top level: Step down 35-40V main battery voltage to first subsystem voltage level Needs from other subsystems: MCU Low voltage shutdown command Solution being implemented: A mix of DC-DC Buck Converter and LDO Linear Regulators Requirements from other subsystems, “Power Budget”: V_nomI_minI_nomI_maxP_minP_nomP_max VmA mW MCU (PIC) Screen Screen Backlight GPS module Voltage Sensor Current Sensor Wheel Speed Sensor Internal Memory External Memory Module