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Power Subsystem Build & Test

Table of Contents

Power Subsystem Level Build & Test Phase

During this phase, the Power Management Boards were assembled, and testing has begun. The MPPT and the batteries were ordered, the solar panel was tested, and software had been started for the Power Management Board.

Power Management Board

The Power Management Board was assembled and testing has begun. The assembled PCB is shown below.
PMB PCB Front

PMB PCB Front

PMB PCB Back

PMB PCB Back

MPPT

The GV-5 Lithium Ion 12.5V MPPT solar charge controller was purchased from batteryspace.com.

MPPT

MPPT

Battery

18 of the Samsung 35E 18650 3500mAh batteries were purchase from IRM. They will be assembled in either a 3S5P or 3S6P configuration.

Battery

Battery

Test Results Summary

Solar Panel

The solar panel was tested briefly to ensure it was working by putting a lamp directly over it and measuring the open circuit voltage. The voltage was measured to be 17.03V. This value makes sense because the max open circuit voltage is 24V so when the solar panel is under more light we would expect to see this. The test setup is shown below.
Solar Panel Test

Solar Panel Test

More testing will be done with the solar panel once the MPPT arrives.

Power Management Board Hardware

Initial testing of the Power Management Board is done and some more detailed tests are remaining. A picture taken of both the 12V output and the 24V output is shown below.
PMB Output Voltages

PMB Output Voltages

The test plans are shown below. Some are completed, partially completed, and some have not been started. These tests will all be finished within the next phase.

Impedance Check

Impedance Check

Impedance Check

12V Turn On and Turn Off Voltage

12V Turn On/Turn Off

12V Turn On/Turn Off

12V Regulation and Efficiency

12V Regulation and Efficiency

12V Regulation and Efficiency

At 3.4A load on the 12V output a thermal image of the board was taken. The 12V Buck Boost Converter was measured to be around 65 degC. This is warm but is not too much of a concern because the part has internal switches so it makes sense that it is getting hot.

12V Converter Thermal Image

12V Converter Thermal Image

12V Load Step Response

12V Load Step Response

12V Load Step Response

12V Ripple Voltage

12V Ripple Voltage

12V Ripple Voltage

12V Ripple Voltage

12V Ripple Voltage

24V Turn On and Turn Off Voltage

24V Turn On/Turn Off

24V Turn On/Turn Off

24V Regulation and Efficiency

24V Regulation and Efficiency

24V Regulation and Efficiency

24V Load Step Response

24V Load Step Response

24V Load Step Response

24V Ripple Voltage

24V Ripple Voltage

24V Ripple Voltage

3.3V Regulation

3.3V Regulation

3.3V Regulation

Subsystem Build & Test Documents/Power/Power Test Plans.xlsx

Power Management Board Software

I2C software has been written to communicate with the MAX34409, 4 channel current sensor and the INA226, power monitor. Data is received by the MSP432 from these sensors and is printed out over UART, shown below. The values of the results have not been checked for accuracy yet. The next step will be to load specific output and verify the current drawn matches our measurement/calculation.

Calling MAX34409

COMMS_SHNT measurement: ff

COMMS_SNS measurement: a5a5a5a5

DACQ_SHNT measurement: 24

DACQ_SNS measurement: a5a5a5a5

EXTRA_SHNT measurement: 0

EXTRA_SNS measurement: a5a5a5a5

CBOB0_SHNT measurement: 0

CBOB0_SNS measurement: a5a5a5a5

Calling INA226

SOLAR_SHNT measurement: 2

SOLAR BUS VOLTAGE measurement: 0

SOLAR CURRENT measurement: 2

SOLAR POWER measurement: 0

SOLAR overflow in calculation if bit 2 high: 0

BATETRY SHNT measurement: 1

BATTERY BUS VOLTAGE measurement: ab

BATTERY CURRENT measurement: ff

BATTERY POWER measurement: 1

BATTERY overflow in calculation if bit 2 high: 0

Risk and Problem Tracking

As issues are found with Power Management Board, they are recorded in the document shown below. Some of this issues have been resolved and some still need to be investigated further. Also, some things were documented that were not necessarily a problem but resulted in a board modification so they were documented here.
PMB Problem Tracking

PMB Problem Tracking

Subsystem Build & Test Documents/Power/Power_Problem_Tracking.xlsx

Functional Demo Materials

Plans for next phase


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