PSU 08/09 Page

Current Status


The power supply unit (PSU) for PLUME has been purchased. It is the 1U CubeSat electrical power supply by Clyde Space. The main features of the PSU are:

  • It can interface up to 6 solar arrays
  • It has three battery charge regulators (BCRs). Each BCR acts as a MPPT setting the solar array's voltage to the optimal value for maximum efficiency. In addition, BCRs provide a constant current and voltage which is required for charging the battery.
  • There are three power buses, a 5V regulated that can deliver up to 1.2A, a 3.3V regulated that can deliver up to 1A and an unregulated power bus.
  • Each bus has over-current protection. In case of a short circuit of any subsystem, the over-current protection prevents damage of the PSU by switching the power bus off for a few milliseconds.
  • The battery has under-voltage protection. In order to prevent deep discharge of the battery, if the battery voltage drops below 6.5V, the output buses are disabled until the battery voltage reaches 7.5V.
  • There is telemetry and telecommand available via an I2C bus. There is a telecommand that resets all three buses and there are telemetries that give the battery's current, voltage, temperature and current direction, the solar arrays' voltages, currents and temperatures and the buses' currents.
  • The power consumption of the PSU is <0.1W, its mass is 152.96g (including the mass of the battery) and its dimensions are 95mm (l) x 90mm (w) x 15mm (d). These data are also contained in table 1.
  • An estimation of the average power delivered by the PSU over one orbit: 2.40W.

Photo of our PSU taken at the SRC during the testing procedure

Table 1. PSU Mechanical Details

Dimensions Mass Power Consumption
95mm(l) x 90mm(w) x 15mm(d) 152.96 g <0.1W

We are currently in the process of testing the PSU. Listed below are all the testings required.

Table 2. Current Status of the PSU

Component Description Status
I2C Bus Test the telemetry and telecommand available via I2C bus currently testing
BCR Test whether the BCRs are functioning properly currently testing
Battery Board Go through charge - discharge cycles of the battery board using different power inputs testing procedure developed and approved. Actual testing not started

Attached to this page you can find the test plan for the PSU with additional information on the functionality of the PSU.

Solar Panels

The Technology of Solar Cells

The team has considered three companies that supply solar cells for CubeSat projects. These are Clyde Space, EMCORE and Spectrolab. Information on the solar cells available from each company can be found here The Technology of Solar Cells.

Unless otherwise stated, the content of this page is licensed under Creative Commons Attribution-Share Alike 2.5 License.