The EPS (Electrical Power Subsystem) of the standard platform is required to provide sufficient power for the satellite's payload and platform during the satellite mission, ensuring the smooth execution of the mission.
The EPS consists of solar panels, batteries, and other core components: solar panels and batteries can be replaced according to mission requirements, and batteries can also be adjusted based on DOD (Depth of Discharge) requirements; the EPS needs to implement Maximum Power Point Tracking (MPPT) through an MCU (Microcontroller Unit), regulate the BCR (Battery Charge Regulator), and support the deployment of various solar panels according to actual conditions and settings. Traditional CubeSats typically adopt a regulated voltage of 12V, with batteries designed in a 4S (series) configuration to provide a power supply above 12V, and the BCR supports 4P (parallel) charging.
Figure 1 Power generation capacity of 3U CubeSats.
Based on data from the 3U CubeSat database, Figure 1 shows the distribution of power generation capacity of 3U CubeSats, with 90% of 3U CubeSats having a power generation capacity below 30W. Therefore, the standard platform in this research assumes a maximum accommodated power of 30W. The MPPT (Maximum Power Point Tracking) is equipped with P&O (Perturb and Observe) and fuzzy logic-based control algorithms, and users can modify the MPPT algorithms.
Figure 2 EPS functional diagram.
The functional diagram of the EPS is shown in Figure 2: the electrical energy generated by the solar panels is regulated and input to the EPSU (Electrical Power Storage Unit) at maximum power to charge the batteries; the charged batteries output voltages of 3.3V, 5V, and 12V through the EPCU (Electrical Power Control Unit) and EPDU (Electrical Power Distribution Unit) for use by the standard platform. In addition, the EPS includes latching current limiting switches, which can realize on/off control of power distribution for each subsystem component, and has protection functions such as overcurrent shutdown.
