Group 12 – H.E.A.D Gear Maximum Power Point Tracker Reliability and Safety Analysis Harsha Eric Atandra Daniel Vengapaty Aasen Burman Da Silva

Schematic: Main Blocks

A: PIC18F2680 C: MAX1684 B: MAX6241

FMECA Table Failure No. Failure ModePossible CausesFailure EffectsMethod of Detection Criticality A1PWM = 0% continuously Latch up, software Stop charging the batteryObservationLow A2PWM = 100% continuously Latch up, software Stop charging the batteryObservationLow A3Input from Oscillator ≠ 10MHz Failure in External Oscillator Effect baud rate, communication over CAN ObservationLow A4Relay Control = 1Latch up, software Array always disconnectedObservationLow A6Outputs give unpredictable values continuously Latch up, software Possible damage to various subsystems of the MPPT unit ObservationHigh

FMECA Table Failure No. Failure ModePossible CausesFailure EffectsMethod of Detection Criticality B1Output Voltage = 0V Failure in MAX6241 Overvoltage Protection Unit Failure, Trackers are cut off, analog outputs to µC ObservationLow B2Output Voltage out of tolerance Failure in MAX6241 Analog circuit gets effected, unpredictable behavior in µC, Possible overheating of chips and fire ObservationHigh B3Output Voltage > 4.096V Failure in MAX6241 Possible damage to Overvoltage Protection Unit and µC ObservationHigh C1Output Voltage = 0V Failure in MAX1684 SPI Shift Register, µC, Overvoltage Protection Unit, CAN transceiver, connectors disabled ObservationLow C2Output Voltage out of tolerance Failure in MAX1684 Unpredictable behavior in µC ObservationHigh C3Output Voltage > 5.0V Failure in MAX1684 Possible damage to µC, SPI shift register ObservationHigh

D: MCP23S08E: MCP2551 F: MCP6543

G: Analog Circuit

FMECA Table Failure No. Failure ModePossible CausesFailure EffectsMethod of Detection Criticality D1SO latched at same value continuously Latch up, Failure in MCP23S08 Data would not get shifted properly, effect diagnostic leds, CAN address and cable detects ObservationLow E1CAN_H ≠ CAN_L continuously Failure in MCP2551 Corruption of Data on CAN bus ObservationLow F1Output = 0 continuously Failure in MCP6543 Array always disconnectedObservationLow F2Output = 1 continuously Failure in MCP6543 Overvoltage not detected, damage to motor controller if OUTPUT_V_SENSE > 70V ObservationHigh G1Input and Output currents and voltages are 0 continuously Op amp failureCant find MPPObservationLow