Non-linear droop control
Aspects of non-linear droop control are described herein. In one embodiment, a system includes a first power converter or source configured to provide power to a bus, a second power converter or source configured to provide power to the bus, and a load electrically coupled to the bus. The system also includes a controller configured to adjust a droop resistance associated with the first power source according to a continuous non-linear function based on an amount of current supplied to the load by the first power source. The system can also include a second controller configured to adjust a droop resistance associated with the second power source according to the continuous non-linear function (or another continuous non-linear function). The use of the continuous non-linear functions achieves tighter voltage regulation particularly at lower loads and better load sharing at higher loads.
1. A power converter system, comprising:
at least two power converters configured to provide power to a direct current (DC) bus over a predetermined voltage range;
a load electrically coupled to the DC bus; and
a controller configured to sense an amount of current supplied over the DC bus to the load by one of the at least two power converters and to adjust a droop resistance associated with the one of the at least two power converters according to a continuous non-linear function based on the amount of current supplied to the load.
2. The power converter system of claim 1 , wherein the controller is configured to decrease a voltage reference associated with the one of the at least two power converters according to the continuous non-linear function to increase the droop resistance for the one of the at least two power converters in response to an increase in the amount of current supplied to the load by the one of the at least two power converters.
3. The power converter system of claim 1 , wherein the controller is configured to decrease a voltage reference associated with the one of the at least two power converters according to the continuous non-linear function to increase the droop resistance for the one of the at least two power converters to approach an infinite droop resistance as the amount of current supplied to the load by the one of the at least two power converters approaches a predetermined maximum output power for the one of the at least two power converters.
4. The power converter system of claim 1 , wherein the controller is configured to:
decrease a voltage reference associated with the one of the at least two power converters according to the continuous non-linear function to approach an infinite droop resistance for the one of the at least two power converters; and
transition the one of the at least two power converters into a current limiting mode as the amount of current supplied to the load by the one of the at least two power converters approaches a predetermined maximum output power for the one of the at least two power converters.
5. The power converter system of claim 1 , wherein the controller is configured to increase a voltage reference associated with the one of the at least two power converters according to the continuous non-linear function to decrease the droop resistance for the one of the at least two power converters in response to a decrease in the amount of current supplied to the load by the one of the at least two power converters.
6. The power converter system of claim 1 , wherein the controller is configured to increase a voltage reference associated with the one of the at least two power converters according to the continuous non-linear function to decrease the droop resistance for the one of the at least two power converters to approach a zero droop resistance as the amount of current supplied to the load by the one of the at least two power converters approaches zero.
7. The power converter system of claim 1 , wherein an adjustment to the droop resistance results in an increase or a decrease in the droop resistance for the one of the at least two power converters.
8. The power converter system of claim 1 , wherein the continuous non-linear function comprises an inverse parabolic function.
9. The power converter system of claim 1 , wherein the continuous non-linear function comprises an ellipse function.
10. A system, comprising:
at least two power sources configured to provide power to a bus;
a load electrically coupled to the bus; and
a controller configured to adjust a droop resistance associated with one of the at least two power sources according to a continuous non-linear function based on an amount of power supplied to the load by the one of the at least two power sources.
11. The system of claim 10 , wherein the controller is configured to increase the droop resistance for the one of the at least two power sources in response to an increase in the amount of power supplied to the load by the one of the at least two power sources.
12. The system of claim 10 , wherein the controller is configured to increase the droop resistance for the one of the at least two power sources to approach an infinite droop resistance as the amount of power supplied to the load by the one of the at least two power sources approaches a predetermined maximum output power for the one of the at least two power sources.
13. The system of claim 10 , wherein the controller is configured to:
decrease a voltage reference associated with the one of the at least two power sources according to the continuous non-linear function to approach an infinite droop resistance for the one of the at least two power sources; and
transition the one of the at least two power sources into a current limiting mode as the amount of power supplied to the load by the one of the at least two power sources approaches a predetermined maximum output power for the one of the at least two power sources.
14. The system of claim 10 , wherein the controller is configured to decrease the droop resistance for the one of the at least two power sources in response to a decrease in the amount of power supplied to the load by the one of the at least two power sources.
15. The system of claim 10 , wherein the controller is configured to decrease the droop resistance for the one of the at least two power sources to approach a zero droop resistance as the amount of power supplied to the load by the one of the at least two power sources approaches zero.
16. The system of claim 10 , wherein an adjustment to the droop resistance results in an increase or a decrease in the droop resistance for the one of the at least two power sources.
17. The system of claim 10 , wherein the continuous non-linear function comprises at least one of an inverse parabolic function or an ellipse function.