Power System Architecture for Qatar University Cubesat Abdulaziz AlKuwari, Hassan Miqdad and Ahmed Diab Supervisors : Dr. Ahmed Massoud & Dr.Tamer Khattab Qatar University Department of Electrical Engineering, College of Engineering Spring 2014. Abstract.
Power System Architecture for Qatar University Cubesat Abdulaziz AlKuwari, Hassan Miqdad and Ahmed Diab
Supervisors: Dr. Ahmed Massoud & Dr.Tamer Khattab
Qatar UniversityDepartment of Electrical Engineering, College of Engineering
The role of the power supply architecture of Qatar University Cubesat is supplying all the satellite subsystems by their power requirements. The architecture composes from different stages including power generation, storage and finally distribution. The rated power of the presented system is increased by a factor of 10 compared to the actual satellite power system. The power generation is achieved by using 120W PV module. Later, the power is stored in a rechargeable battery. Three different converters are used to regulate the output voltages to match the loads requirements. To assure having a regulated voltage levels, a feedback control mechanism is also provided. In order, to control the conditioning converters a full detailed model was derived using state space technique. The model is used later, to design the controller. An adaptive maximum power point tracking algorithm is introduced and implemented practically. Finally the efficiency of the Cubesat is calculated at three different cases that represent the real situations that the satellite will operate at.
Figure 6. The overall system implementation result
Figure 3. Oscilloscope result of the MPPT with adaptive perturb (transient)
The power supply architecture of the Cubesat was designed. The power is captured by solar panels and conditioned through power converters. The converters regulate the voltage based on the satellite subsystems requirements. To extract the maximum power from the panels, a maximum power point tracking controller based on the Perturb and Observe algorithm was simulated and implemented practically. An enhancement to the algorithm was introduced by including an adaptive term to the algorithm. The power converters were modeled using the state space representation, and then a control strategy based on the state feedback control technique was proposed. Finally, the efficiency of the system was evaluated.
The overall Cubesat power system is simulated using MATLAB/Simulink. The model is shown in figure 2.
Figure 4. open loop steady-state output voltage of the buck converter number (2)
As a future work the same system has to be implemented based on the real standard size of the Cubesat power supply at which the engineering satellite phase shall be terminated. In the satellite, some loads do not require to be supplied permanently. Those loads can be disconnected during that time. A triple junction model of a PV panel shall be derived to test the behavior of the purchased PV module and its performance with the proposed MPPT algorithm. An over-current protection strategy has to be added to the system in addition to battery over -charge protection strategy.
Figure 5. closed loop transient output voltage of the buck converter number (2)
The system configuration for the On-Board Electric Power Supply System (OBEPSS) can be well visualized as illustrated in figure 1
Figure 2. Simulink model of the power supply
DSP Programming code
Power Conditioning Converters
Current, Voltage sensors and the DSP
The authors would like to thank their supervisors Dr. Ahmed Massoud and Dr. Tamer Khattab and the Department of Electrical Engineering in Qatar University. In addition, the authors would like to express their gratitude toward both Eng. Mohammed Ayad and Eng. Ayman Ammar for their extensive support .
Figure 1: The Hardware Overview Configuration of the power supply of the Cubesat