Nanosatellite solar cell regulator

• US 7,786,716 B2
• Filed: 08/29/2005
• Issued: 08/31/2010
• Est. Priority Date: 08/29/2005
• Status: Active Grant

• Current Assignee: Aerospace Corporation
• Original Assignee: Aerospace Corporation
• Inventors: Simburger, Edward J., Rumsey, Daniel L., Carian, Peter J.
• Primary Examiner(s): Patel; Rajnikant B
• Application Number:
  US11/214,377
• Publication Number:
  US 20070044837A1
• Time in Patent Office: 1,828 Days
• Field of Search: 323282-290, 323/222, 323/225, 323/275, 323/906, 323/907, 136/244, 136/246, 136/252, 136/259, 136/293, 136/291, 136/292, 320/101, 320/104, 320/107, 320/117, 320/125
• US Class Current: 323/290
• CPC Class Codes: B64G 1/428 Power distribution and management
• CPC Class Codes: B64G 1/443 Photovoltaic cell arrays
• CPC Class Codes: H02J 4/00 Circuit arrangements for mains or distribution networks not specified as ac or dc
• CPC Class Codes: H02J 7/35 with light sensitive cells
• CPC Class Codes: Y10S 323/906 Solar cell systems

Abstract

A solar cell regulator in a nanosatellite includes a pulse width modulated DC-DC boost converter and a peak power tracking controller for converting solar cell power to bus power for charging of system batteries and powering loads while the controller controls the pulse width modulation operation of the converter for sensing solar cell currents and voltages along a power characteristic curve of the solar cell for peak power tracking, for determining any power data point, including a peak power point, an open circuit voltage point, and a short circuit current point along the power characteristic curve of the solar cell, and for communicating the power data to a satellite processor for monitoring the performance of the solar cell during operational use of the satellite.

Claims

1. A nanosatellite solar cell regulator comprising,

a nanosatellite,

a regulator for peak power tracking of a solar cell, the regulator disposed between the solar cell and a nanosatellite ring power bus,

the regulator comprising,

an input current sensor for measuring an input current Iin from the solar cell,

a boost converter for receiving an input voltage Vin at the input current Iin from the solar cell providing input power (Vin)(Iin), the regulator providing an output current Iout, the regulator converting the input power to output power (VBus)(Iout) where VBus>

Vin, the output power is communicated onto the ring power bus via an isolation diode between the boost converter and a VBus measuring device, the ring power bus having an output bus voltage VBus, the solar cell having a peak power point, and

a controller for monitoring the input power and for controlling the boost converter for providing the peak power output of the solar cells.

2. The device of claim 1 wherein,

the solar cell is a string of series connected solar cells.

3. The device of claim 1 wherein,

the solar cell is an array of solar cells.

13. The device of claim 1 wherein,

the nanosatellite comprises a battery,

the ring power bus is coupled to the battery, and

the solar cells charges the battery through the regulator and ring power bus.

14. The device of claim 1 wherein,

the data bus is a ring data bus, and

the power data is communicated onto the ring data bus of the nanosatellite, the ring data bus being connected to the nanosatellite processor.

17. The device of claim 1 wherein,

the nanosatellite processor communicates a request for power data to the controller.

18. The device of claim 1 wherein,

the nanosatellite processor communicates a request for power data to the controller, and

the controller communicates power data to the processor.

19. The device of claim 1 wherein,

the nanosatellite processor communicates a request for power data to the controller, and

the controller communicates power data to the processor, the power data comprising power points along the power characteristic curve.

4. A nanosatellite solar cell regulator comprising,

a nanosatellite,

a regulator for peak power tracking of a solar cell, the regulator disposed between the solar cell and a nanosatellite ring power bus, the regulator for providing power data of the solar cell to a nanosatellite processor through a ring data bus, the regulator comprising,

an input current sensor for measuring an input current Iin from the solar cell providing an input voltage Vin,

an output current sensor for measuring an output current Iout of the power bus having a bus voltage VBus,

a boost converter for receiving an input voltage Vin and input current Iin from the solar cell providing input power (Vin)(Iin), the regulator providing an output current Iout, the regulator converting the input power to output power (VBus)(Iout) where VBus>

Vin, the output power conducted to the ring power bus, the output power is communicated onto the ring power bus via an isolation diode between the boost converter and a VBus measuring device, the ring power bus having an output bus voltage VBus, the solar cell having a peak power point, the solar cell having an open circuit voltage, the solar cell having a short circuit current, the solar cell having a power characteristic curve comprising the peak power point and the short circuit current and the open circuit voltage, and

a controller for monitoring the input power and for controlling the boost converter for providing peak power output of the solar cell, the controller reducing the output power when the peak power point is exceeded, the controller monitoring the input power for determining power data comprising the peak power point, the controller for communicating the power data to the nanosatellite processor, the power data comprising a data point on the power characteristic curve.

5. The device of claim 4 wherein,

the power data comprises the peak power point and the open circuit voltage and the short circuit current.

6. The device of claim 4 wherein,

the solar cell is a string of series connected solar cells.

7. The device of claim 4 wherein,

the solar cell is an array of solar cells.

8. The device of claim 4 wherein,

the boost converter compares a reference voltage to VBus for determining an error signal, and

the boost converter modulating a pulse width modulation signal by the error signal for converting input power into output power at the peak power point.

9. The device of claim 4 wherein,

controller controls the boost converter to reduce the input current Iin to zero for determining the open circuit voltage, and

the power data comprises the open circuit voltage.

10. The device of claim 4 wherein,

the controller controls the boost converter to short circuit the input voltage Vin for determining the short circuit current, and

the power data comprises the short circuit current.

11. The device of claim 4 wherein,

the boost converter compares a reference voltage to the bus voltage VBus for determining an error signal,

the boost converter modulating a pulse width modulation signal by the error signal for converting the input power into the output power, and

the controller controlling the pulse width modulation to a plurality of power points of the input power between an open circuit and a short circuit of the power characteristic curve.

12. The device of claim 4 wherein,

the boost converter compares a reference voltage to the bus voltage VBus for determining an error signal,

the boost converter modulating a pulse width modulation signal by the error signal for converting input power into output power,

the controller controlling the pulse width modulation to a plurality of power points of the input power between an open circuit and a short circuit of the power characteristic curve, and

the power data comprises a plurality of data points on the power characteristic curve.

15. The device of claim 4 wherein,

the nanosatellite processor commands the controller to open circuit the solar cell for determining an open circuit voltage point along the power characteristic curve.

16. The device of claim 4 wherein,

the nanosatellite processor commands the controller to short circuit the solar cell for determining a short circuit current point along the power characteristic curve.

20. A method of operating an electric power system for a nanosatellite comprising the steps of,

providing a nanosatellite and a nanosatellite ring power bus electric power distribution system,

determining a reference voltage corresponding to a maximum power point from a solar cell power source including one or more solar cells,

supplying power from the solar cell power source to a boost converter,

boosting the voltage of the supplied power in the boost converter,

supplying power from a boosted voltage power output of the boost converter to the nanosatellite ring power bus, and

controlling the boost converter to reduce the power supplied by the solar cell power source when the corresponding solar cell power source voltage falls below the reference voltage.

21. The method of claim 20 further including the steps of,

short circuiting the solar cell power source by operation of the boost converter in a short circuit mode, and

preventing overloading the ring power bus by providing an isolation diode between the boost converter and the ring power bus.

22. A method of operating an electric power system for a nanosatellite comprising the steps of,

providing a nanosatellite and a nanosatellite ring power bus electric power distribution system,

supplying power from the solar cell power source to a boost converter,

boosting the voltage of the supplied power in the boost converter,

supplying power from a boosted voltage power output of the boost converter to the nanosatellite ring power bus, and

controlling the boost converter to reduce the power supplied by the solar cell power source when a commanded power increase results in a lower power output.

23. The method of claim 22 further including the steps of,

short circuiting the solar cell power source by operation of the boost converter in a short circuit mode, and

preventing overloading the ring power bus by providing an isolation diode between the boost converter and the ring power bus.