Designing CubeSat power supply - the system

Okay.. So our CubeSat power supply subsystem should have batteries. There will probably be some solar cells to. Something else too?

The system level design is done after ESTCube-1 power system. Public information about it is available in the article.

Batteries:

  • Two lithium ion cells in parallel
  • Both are two way current limited
    • Current limits have auto retry
    • Enable signals are connected to controller
  • Temperature monitoring
  • Optional: Some kind of heater (pcb track)

In case of one battery failure the satellite can still operate. Batteries are connected through protection to a net named Main Power Bus (MPB).

Charging:

  • SPV1040 maximum power point tracking boost converter
  • 6 or 12 channels
    • Each solar cell is in parallel with others. You can smash 11 of the 12 cells and still have a working satellite.
  • If it makes channels smaller - I will use ideal diode controllers before MPPT to reduce number of MPPTs needed.
  • If it is needed - ideal diodes between SPV1040 output and Main Power Bus

Distributing:

  • Parallel regulators on 3.3 V, 5 V and 12 V rails
  • Output current limits/ideal diodes
  • If needed - input current limits
  • If regulators are wimpy and there is room - more than 1 power rail to all voltages.

Monitoring:

  • We will have a microcontroller monitoring everithing (MSP430FR or maybe Arduino)
  • All FAULT signals are connected to MCU
  • Reasonable amount of enable-disable lines
  • Digital communication with other subsystems (SPI, UART or I2C)
  • Possibility for zombie check signals from other subsystems (to function as a watchdog)
  • Battery voltage measurement
  • As much other voltage measurements as possible
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Posted on 2013-01-31, 08:16 By
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