Energy storage systems and methods
First Claim
1. A method for use with an energy storage system connected with a variable load, the load at some times drawing power from the energy storage system and at other times regenerating power to be stored within the energy storage system, the power draw being greater at some times and lesser at other times, the regenerated power to be stored being greater at some times and lesser at other times, the energy storage system comprising a storage battery and an ultracapacitor, the method comprising the steps of:
- monitoring the state-of-charge (SOC) of the ultracapacitor;
dynamically establishing a set point toward which the SOC is configured to be driven; and
adjusting the dynamic set point as a function of sensed load currents, wherein the sensed load currents are sensed between the storage system and the load, andwherein the dynamic establishment of the set point is a function of an average of the lowest three frequencies obtained by a fast Fourier transform of the sensed load currents.
5 Assignments
0 Petitions
Accused Products
Abstract
In an energy storage system that includes a battery and an ultracapacitor, the state of charge (SOC) of the capacitor is the subject of a dynamic set-point. This dynamic set-point control is a function of the load regime to which the storage system is exposed, for example a hybrid automobile or electric automobile. The control may be based in part upon real-time fast Fourier transform analysis of load current, permitting real-time adjustment of control coefficients. In this way, it is possible to minimize the occurrence of the capacitor being fully charged at a time when it would be desired to be able to absorb high current, for example from regenerative braking. Likewise it is possible to minimize the occurrence of the capacitor being nearly discharged at a time when it would be desirable to have boost power available. A result is that even a relatively small ultracapacitor (having perhaps one two-hundredth the energy storage capacity of the battery) can permit greatly reducing waste heat dissipated in the battery, and can reduce otherwise unnecessary cycling of current into and out of the battery. This can extend battery life and battery performance.
23 Citations
18 Claims
-
1. A method for use with an energy storage system connected with a variable load, the load at some times drawing power from the energy storage system and at other times regenerating power to be stored within the energy storage system, the power draw being greater at some times and lesser at other times, the regenerated power to be stored being greater at some times and lesser at other times, the energy storage system comprising a storage battery and an ultracapacitor, the method comprising the steps of:
-
monitoring the state-of-charge (SOC) of the ultracapacitor; dynamically establishing a set point toward which the SOC is configured to be driven; and adjusting the dynamic set point as a function of sensed load currents, wherein the sensed load currents are sensed between the storage system and the load, and wherein the dynamic establishment of the set point is a function of an average of the lowest three frequencies obtained by a fast Fourier transform of the sensed load currents. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. An energy storage system for connection with a variable load, the load at some times drawing power from the energy storage system and at other times regenerating power to be stored within the energy storage system, the power draw being greater at some times and lesser at other times, the regenerated power to be stored being greater at some times and lesser at other times, the energy storage system comprising:
-
a storage battery; an ultracapacitor having a state of charge (SOC); a power converter in series with the ultracapacitor; the ultracapacitor and power converter together in parallel with the battery and in turn disposed for connection with the variable load; a load current sensor configured to sense a load current between the storage system and the load; and a controller connected with the load sensor and one or more SOC sensors configured to determine the SOC of the ultracapacitor; wherein the controller is configured to be responsive to one or more of the sensed load currents for dynamically establishing a set point toward which the SOC is configured to be driven, and adjusting the dynamic set point as a function of the sensed load current, and wherein the controller is configured to dynamically establish the set point as a function of an average of the lowest three frequencies obtained by a fast Fourier transform of a plurality of the sensed load currents. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
-
Specification