Power train for deep space solar electric propulsion
A spacecraft includes a power train that includes a solar array, an electric propulsion subsystem, and a power conversion module. The power conversion module receives power from the solar array at a voltage, V i ; and delivers power to the electric propulsion subsystem at a voltage, V o . The spacecraft is configured to operate at a varying distance, D, from the sun within the range of D min to D max , D max being at least 1.3×D min . The solar array is configured to deliver power to the power conversion module at a voltage approximately equal to V o when the spacecraft is proximate to D max .
1. A spacecraft power train comprising:
a solar array;
an electric propulsion subsystem; and
a power conversion module that receives power from the solar array at an operating voltage, V i ; that varies with solar array temperature, and delivers power to the electric propulsion subsystem at a second voltage, V o , wherein:
the spacecraft power train is configured to operate at a varying distance, D, from the sun within the range of D min to D max , D max being at least 1.3×D min ; and
the solar array is configured to deliver power to the power conversion module such that the value of V i is approximately equal to V o , when the spacecraft is proximate to D max .
2. The spacecraft power train of claim 1 , wherein:
the electric propulsion subsystem is configured to operate with power regulated to V nom +/−approximately 10%;
the solar array is configured to deliver power to the power conversion module such that V i varies, as a function of D, between a maximum of V o and a minimum less than V o /2; and
the power conversion module is configured to deliver power to the electric propulsion subsystem at the voltage V o , such that V o is not less than V nom /1.1 and not greater than 1.1*V nom .
3. The spacecraft power train of claim 2 , wherein the solar array is configured to deliver power to the power conversion module at a voltage substantially less than V nom when the spacecraft is proximate to D min .
4. The spacecraft power train of claim 1 , wherein the power conversion module includes a boost converter with switching circuitry and an output diode.
5. The spacecraft power train of claim 4 , wherein the switching circuitry of the boost converter becomes inactive and exhibits negligible power loss when V i ≥V nom .
6. The spacecraft power train of claim 1 , wherein the power conversion module efficiency is about 99% when the solar array delivers power to the power conversion module at a voltage approximately equal to V o .
7. The spacecraft power train of claim 1 , wherein the power conversion module efficiency is about 99% when the spacecraft is at a distance from the sun of 0.9 D max or greater.
8. The spacecraft power train of claim 1 , wherein the electric propulsion subsystem includes an electric thruster configured to operate at a power ranging between a minimum power P min and a maximum power P max , P max being at least 5×P min .
9. A spacecraft comprising:
a power train that includes a solar array, an electric propulsion subsystem, and a power conversion module, wherein:
the power conversion module receives power from the solar array at an operating voltage, V i ; that varies with solar array temperature, and delivers power to the electric propulsion subsystem at a voltage, V o ;
the spacecraft is configured to operate at a varying distance, D, from the sun within the range of D min to D max , D max being at least 1.3×D min ; and
the solar array is configured to deliver power to the power conversion module such that the value of V i is approximately equal to V o when the spacecraft is proximate to D max .
10. The spacecraft of claim 9 , wherein:
the electric propulsion subsystem is configured to operate with power regulated to V nom +/−approximately 10%;
the solar array is configured to deliver power to the power conversion module such that V i varies, as a function of D, between a maximum of V o and a minimum less than V o /2; and
the power conversion module is configured to deliver power to the electric propulsion subsystem at the voltage V o , such that V o is not less than V nom /1.1 and not greater than 1.1*V nom .
11. The spacecraft of claim 10 , wherein the solar array is configured to deliver power to the power conversion module at a voltage substantially less than V nom when the spacecraft is proximate to D min .
12. The spacecraft of claim 9 , wherein the power conversion module includes a boost converter and an output diode.
13. The spacecraft power train of claim 9 , wherein the electric propulsion subsystem includes an electric thruster configured to operate at a power ranging between a minimum power P min and a maximum power P max , P max being at least 5×P min .
14. A method comprising:
disposing a spacecraft in a first orbit, the spacecraft while in the first orbit being at an approximate distance, D 1 , from the sun;
transferring the spacecraft to a second orbit, the spacecraft while in the second orbit being at an approximate distance, D 2 , from the sun, D 2 differing from D 1 by a least a factor of two; wherein,
the spacecraft includes a power train that includes a solar array, an electric propulsion subsystem, and a power conversion module;
the power conversion module receives power from the solar array at an operating voltage, V i ; that varies with solar array temperature, and delivers power to the electric propulsion subsystem at a voltage, V o ;
the spacecraft is configured to operate at a varying distance, D, from the sun within the range of D min to D max , D max being at least 1.3×D min ; and
the solar array is configured to deliver power to the power conversion module such that the value of V i is approximately equal to V o when the spacecraft is proximate to D max .
15. The method of claim 14 , wherein:
the electric propulsion subsystem is configured to operate with power regulated to V nom +/−approximately 10%;
the solar array is configured to deliver power to the power conversion module such that V i varies, as a function of D, between a maximum of V o and a minimum less than V o /2; and
the power conversion module is configured to deliver power to the electric propulsion subsystem at the voltage V o , such that V o is not less than V nom /1.1 and not greater than 1.1*V nom .
16. The method of claim 15 , wherein the solar array is configured to deliver power to the power conversion module at a voltage substantially less than V nom when the spacecraft is proximate to D min .
17. The method of claim 14 , wherein the power conversion module includes a boost converter and an output diode.
18. The method of claim 14 , wherein the electric propulsion subsystem includes an electric thruster configured to operate at a power ranging between a minimum power P min and a maximum power P max , P max being at least 5×P min .
19. The method of claim 14 , wherein D 1 is approximately equal to D min and D 2 is approximately equal to D max .
20. The method of claim 14 , wherein D 1 is approximately equal to D max and D 2 is approximately equal to D min .