Priority load sharing for electrical power systems having multiple power sources

1. An electrical power system comprising:

an output for supplying a DC output voltage to a load;

a first power source connected with the output for generating DC power, the first power source configured to:

regulate the DC output voltage to the load in a constant voltage regulation mode in response to a demand of the load being less than an output capacity of the first power source;

transition from the constant voltage regulation mode to an alternate mode in response to the demand of the load increasing from a value less than the output capacity of the first power source to a value greater than the output capacity of the first power source, the alternate mode comprising one of a constant current mode and a constant power mode; and

transition from the alternate mode to the constant voltage regulation mode in response to the demand of the load decreasing from a value greater than the output capacity of the first power source to a value less than the output capacity of the first power source; and

a second power source connected with the output for generating DC power and configured to:

start supplying DC power to the load in response to the demand of the load increasing from a value less than the output capacity of the first power source to a value greater than the output capacity of the first power source; and

stop supplying DC power to the load in response to the demand of the load decreasing from a value greater than the output capacity of the first power source to a value less than the output capacity of the first power source.

2. The electrical power system of claim 1 , wherein the second power source is configured to regulate the DC output voltage in a constant voltage regulation mode during operation of the first power source in the alternate mode.

3. The electrical power system of claim 2 , wherein the electrical power system is configured to:

supply DC power to the load using only the first power source during operation of the first power source in the constant voltage regulation mode; and

supply DC power to the load using both the first power source and the second power source during operation of the first power source in the alternate mode.

4. The electrical power system of claim 1 , wherein the first power source has a higher droop load line voltage setting range than a range of a droop load line voltage setting of the second power source.

5. The electrical power system of claim 1 , wherein the second power supply is configured to operate in an enabled-on state in response to the first power source operating in the constant voltage regulation mode; and

wherein the enabled-on state comprises the second power source producing DC power but not supplying the produced DC power to the load.

6. The electrical power system of claim 5 further comprising a third power source connected with the output to supply DC power to the load, wherein the electrical power system is configured to:

supply DC power to the load using only the first power source and the second power source in response to the demand of the load being greater than the output capacity of the first power source and less than a combined output capacity of the first power source and the second power source; and

supply DC power to the load using the first, second, and third power sources in response to the demand of the load being greater than the output capacity of the first and second power sources.

7. The electrical power system of claim 6 , wherein the third power source is configured to maintain the enabled on-state in response to not supplying DC power to the load.

8. The electrical power system of claim 1 , wherein:

the first power source includes multiple power supplying devices connected with a first load share bus;

the second power source includes multiple other power supplying devices connected with a second load share bus; and

an output voltage regulation setting of the first power source is greater than an output voltage regulation setting of the second power source.

9. The electrical power system of claim 8 , wherein the output voltage regulation setting of the first power source is 12.6V and the output voltage regulation setting of the second power source is 12.4V.

10. The electrical power system of claim 8 , wherein the output voltage regulation setting of the first power source is separated from the output voltage regulation setting of the second power source by at least a specified guard band value to inhibit interaction of active current sharing control of the first load share bus and active current sharing control of the second load share bus.

11. The electrical power system of claim 1 , wherein the first power source includes a switched-mode power supply and the second power source includes a backup battery unit.

12. The electrical power system of claim 1 , wherein the electrical power system is configured to switch the first power source to a secondary priority setting and switch the second power source to a primary priority setting, during operation of the power system.

13. A method for supplying a DC output voltage from an output to a load, the method comprising:

regulating, via a first power source coupled with the output, the DC output voltage to the load in a constant voltage regulation mode in response to a demand of the load being less than an output capacity of the first power source;

transitioning from the constant voltage regulation mode to one of a constant current mode and a constant power mode in response to the demand of the load increasing from a value less than the output capacity of the first power source to a value greater than the output capacity of the first power source;

transitioning from the one of the constant current mode and the constant power mode to the constant voltage regulation mode in response to the demand of the load decreasing from a value greater than the output capacity of the first power source to a value less than the output capacity of the first power source;

supplying DC power to the load via a second power source in response to the demand of the load increasing from a value less than the output capacity of the first power source to a value greater than the output capacity of the first power source; and

ceasing supply of the DC power to the load via the second power source in response to the demand of the load decreasing from a value greater than the output capacity of the first power source to a value less than the output capacity of the first power source.

14. The method of claim 13 further comprising regulating the DC output voltage in a constant voltage regulation mode via a second power source connected with the output during operation of the first power source in the alternate mode.

15. The method of claim 14 further comprising:

supplying DC power to the load using only the first power source during operation of the first power source in the constant voltage regulation mode; and

supplying DC power to the load using both the first power source and the second power source during operation of the first power source in the alternate mode.

16. The method of claim 13 further comprising operating the second power supply in an enabled-on state in response to the first power source operating in the constant voltage regulation mode; and

wherein the enabled-on state comprises the second power source producing DC power but not supplying the produced DC power to the load.

17. The method of claim 16 further comprising:

supplying DC power to the load using only the first power source and the second power source in response to the demand of the load being greater than the output capacity of the first power source and less than a combined output capacity of the first power source and the second power source; and

supplying DC power to the load using the first power source, the second power source, and a third power source in response to the demand of the load being greater than the output capacity of the first and second power sources.

18. The method of claim 17 further comprising maintaining the third power source in the enabled on-state in response to not supplying DC power to the load.

19. An electrical power system comprising:

an output for supplying a DC output voltage to a load;

a first power source connected with the output for generating DC power, the first power source configured to:

regulate the DC output voltage to the load in a constant voltage regulation mode in response to a demand of the load being less than an output capacity of the first power source;

transition from the constant voltage regulation mode to an alternate mode in response to the demand of the load increasing from a value less than the output capacity of the first power source to a value greater than the output capacity of the first power source, the alternate mode comprising one of a constant current mode and a constant power mode; and

transition from the alternate mode to the constant voltage regulation mode in response to the demand of the load decreasing from a value greater than the output capacity of the first power source to a value less than the output capacity of the first power source; and

a second power source connected with the output for generating DC power;

wherein:

the first power source includes multiple power supplying devices connected with a first load share bus;

the second power source includes multiple other power supplying devices connected with a second load share bus; and

an output voltage regulation setting of the first power source is greater than an output voltage regulation setting of the second power source.

20. An electrical power system comprising:

an output for supplying a DC output voltage to a load;

a first power source connected with the output for generating DC power, the first power source configured to:

regulate the DC output voltage to the load in a constant voltage regulation mode in response to a demand of the load being less than an output capacity of the first power source;

transition from the constant voltage regulation mode to an alternate mode in response to the demand of the load increasing from a value less than the output capacity of the first power source to a value greater than the output capacity of the first power source, the alternate mode comprising one of a constant current mode and a constant power mode; and

transition from the alternate mode to the constant voltage regulation mode in response to the demand of the load decreasing from a value greater than the output capacity of the first power source to a value less than the output capacity of the first power source; and

a second power source connected with the output for generating DC power;

wherein the electrical power system is configured to switch the first power source to a secondary priority setting and switch the second power source to a primary priority setting, during operation of the power system.