System for multiple energy storage and management and method of making same
View Patent ↗A propulsion system includes an electric drive, a first energy storage system electrically coupled to the electric drive through a DC link, and a second energy storage system electrically coupled to the first energy storage system in a series connection. The first energy storage system comprises a high specific-energy storage device and the second energy storage system comprises a low specific-power storage device. The propulsion system also includes a third energy storage system comprising a high specific-energy storage device electrically coupled to the second energy storage system. A bi-directional boost converter is electrically coupled to the second and third energy storage systems such that a terminal of the third energy storage system is electrically coupled to a low voltage side of the bi-directional boost converter and a terminal of the second energy storage system is coupled to a high voltage side of the bi-directional boost converter.
1. A propulsion system comprising:
an electric drive;
a first energy storage system electrically coupled to the electric drive through a direct current (DC) link, the first energy storage system comprising a high specific-energy storage device;
a second energy storage system electrically coupled to the first energy storage system in a series connection, the second energy storage system comprising a high specific-power storage device;
a third energy storage system electrically coupled to the second energy storage system, the third energy storage system comprising a high specific-energy storage device; and
a first bi-directional boost converter electrically coupled to the second and third energy storage systems such that a terminal of the third energy storage system is electrically coupled to a low voltage side of the first bi-directional boost converter and a terminal of the second energy storage system is coupled to a high voltage side of the first bi-directional boost converter.
2. The propulsion system of claim 1 wherein the first energy storage system comprises a low specific power battery.
3. The propulsion system of claim 2 wherein the first energy storage system comprises at least one of a lithium ion battery, a sodium metal halide battery, and a lead-acid battery.
4. The propulsion system of claim 1 wherein the third energy storage system comprises a low specific power battery; and
wherein the third energy storage system has a different chemical composition than the first energy storage system.
5. The propulsion system of claim 1 wherein the second energy storage system comprises one of a power battery and an ultracapacitor.
6. The propulsion system of claim 1 wherein the first bi-directional boost converter is configured to control an amount of energy transferred from the third energy storage system to the second energy storage system through the first bi-directional boost converter to maintain a state-of-charge (SOC) of the second energy storage system between an upper threshold and a lower threshold.
7. The propulsion system of claim 1 further comprising a second bi-directional boost converter, wherein a low voltage side of the second bi-directional boost converter is electrically coupled to a terminal of the first energy storage system; and
wherein a high voltage side of the second bi-directional boost converter is electrically coupled to a positive terminal of the DC link.
8. The propulsion system of claim 1 wherein a voltage of the third energy storage system is lower than a voltage of the second energy storage system; and
wherein a voltage of the first energy storage system is lower than the voltage of the third energy storage system.
9. A method of assembling a control system for an electric drive comprising:
providing a first bi-directional boost converter;
coupling a terminal of a first high specific-energy storage device to a low-voltage side of the first bi-directional boost converter;
coupling a terminal of a high specific-power storage device to a high-voltage side of the bi-directional boost converter;
coupling a first terminal of a second high specific-energy storage device to the terminal of the high specific-power storage device to form a series connection between the high specific-power storage device and the second high specific-energy storage device.
10. The method of claim 9 further comprising:
providing a second bi-directional boost converter having a power rating that is higher than a power rating of the first bi-directional boost converter; and
coupling a second terminal of the second high specific-energy storage device to a low voltage side of the second bi-directional boost converter.
11. The method of claim 9 wherein the step of coupling the first high specific-energy storage device to the first bi-directional boost converter and the step of coupling the high specific-power storage device to the first bi-directional boost converter form a parallel connection between the first high specific-energy storage device and the high specific-power storage device.
12. An energy storage arrangement for an electrically powered system, the arrangement comprising:
a first bi-directional boost converter;
a high specific-power storage device having a positive terminal electrically coupled to a high-voltage side of the first bi-directional boost converter; and
a first high specific-energy storage device having a negative terminal electrically coupled to the high-voltage side of the first bi-directional boost converter and to the positive terminal of the high specific-power storage device;
a second high specific-energy storage device having a positive terminal electrically coupled to a low-voltage side of the first bi-directional boost converter; and
wherein a series connection is formed between the high specific-power storage device and the first high specific-energy storage device.
13. The energy storage arrangement of claim 12 wherein the first high specific-energy storage device comprises a low specific power battery.
14. The energy storage arrangement of claim 13 wherein the first high specific-energy storage device comprises a lithium ion battery.
15. The energy storage arrangement of claim 12 wherein the second high specific-energy storage device comprises a low specific power battery.
16. The energy storage arrangement of claim 15 wherein the second high specific-energy storage device comprises a sodium metal halide battery.
17. The energy storage arrangement of claim 12 wherein the high specific-power storage device comprises one of a power battery and an ultracapacitor.
18. The energy storage arrangement of claim 12 wherein the first bi-directional boost converter comprises an energy management system programmed to selectively transmit a charging voltage from the second high specific-energy storage device to the high specific-power storage device.
19. The energy storage arrangement of claim 18 wherein the energy management system is programmed to maintain a state-of-charge (SOC) of the high specific-power storage device between a predetermined lower threshold and a predetermined upper threshold.
20. The energy storage arrangement of claim 12 wherein a voltage of the second high specific-energy storage device is lower than a voltage of the high specific-power storage device; and
wherein a voltage of the first high specific-energy storage device is lower than the voltage of the second high specific-energy storage device.
21. The energy storage arrangement of claim 12 further comprising a second bi-directional boost converter having a low voltage side electrically coupled to a positive terminal of the first high specific-energy storage device.