Modular stacked DC architecture traction system and method of making same
View Patent ↗A modular stacked DC architecture for traction system includes a propulsion system includes an electric drive, a direct current (DC) link electrically coupled to the electric drive, and a first DC-DC converter coupled to the DC link. A first energy storage device (ESD) is electrically coupled to the first DC-DC converter, and a second DC-DC converter is coupled to the DC link and to the first DC-DC converter. The system also includes a second energy storage device electrically coupled to the second DC-DC converter and a controller coupled to the first and second DC-DC converters and configured to control a transfer of energy between the first ESD and the DC link via the first and second DC-DC converters.
1. A propulsion system comprising:
an electric drive;
a direct current (DC) link comprising a first bus and a second bus coupled to the electric drive;
a first DC-DC converter coupled to the first bus of the DC link, the first DC-DC converter comprising a plurality of switch legs, the switch legs comprising at least two switches;
a second DC-DC converter coupled to the second bus of the DC link and the first DC-DC converter, the second DC-DC converter comprising a plurality of switch legs, the switch legs comprising at least two switches;
a first energy storage device (ESD) coupled to the first DC-DC converter;
a second ESD coupled to the second DC-DC converter; and
a controller configured to:
selectively transfer energy from at least one of the first ESD and the second ESD to the electric drive by controlling a first plurality of switches in the first DC-DC converter and a second plurality of switches in the second DC-DC converter; and
selectively transfer energy from the electric drive to charge at least one of the first ESD and the second ESD by controlling a third plurality of switches in the first DC-DC converter and a fourth plurality of switches in the second DC-DC converter.
2. The propulsion system of claim 1 wherein the first plurality of switches in the first DC-DC converter comprises a first switch from a first leg of the first DC-DC converter and a second switch from a second leg of the first DC-DC converter.
3. The propulsion system of claim 1 wherein the third plurality of switches in the second DC-DC converter comprises a first switch from a first leg of the second DC-DC converter and a second switch from a second leg of the second DC-DC converter.
4. The propulsion system of claim 1 wherein the second plurality of switches in the first DC-DC converter comprises a first switch from a first leg of the first DC-DC converter and a second switch from a second leg of the first DC-DC converter.
5. The propulsion system of claim 1 wherein the fourth plurality of switches in the second DC-DC converter comprises a first switch from a first leg of the second DC-DC converter and a second switch from a second leg of the second DC-DC converter.
6. The propulsion system of claim 1 wherein the controller is further configured to control a duty cycle of the first, second, third, and fourth plurality of switches.
7. The propulsion system of claim 1 wherein the first DC-DC converter and the second DC-DC converter are bi-directional.
8. The propulsion system of claim 1 wherein a first leg of the first DC-DC converter, a first leg of the second DC-DC converter, and the electric drive form an H-bridge.
9. The propulsion system of claim 1 further comprising a third DC-DC converter coupled between the electric drive and the first and second DC-DC converters.
10. A vehicle comprising:
an electric drive comprising an inverter coupled to a traction motor;
a direct current (DC) link comprising a first bus and a second bus coupled to the electric drive;
a first DC-DC converter coupled to the first bus of the DC link, the first DC-DC converter comprising a plurality of switch legs, the switch legs comprising at least two switches;
a second DC-DC converter coupled to the second bus of the DC link and the first DC-DC converter, the second DC-DC converter comprising a plurality of switch legs, the switch legs comprising at least two switches;
a first energy storage device (ESD) coupled to the first DC-DC converter;
a second ESD coupled to the second DC-DC converter; and
a controller configured to:
selectively transfer energy from at least one of the first ESD and the second ESD to the electric drive by controlling a first plurality of switches in the first DC-DC converter and a second plurality of switches in the second DC-DC converter; and
selectively transfer energy from the electric drive to charge at least one of the first ESD and the second ESD by controlling a third plurality of switches in the first DC-DC converter and a fourth plurality of switches in the second DC-DC converter.
11. The vehicle of claim 10 wherein the first plurality of switches in the first DC-DC converter comprises a first switch from a first leg of the first DC-DC converter and a second switch from a second leg of the first DC-DC converter.
12. The vehicle of claim 10 wherein the third plurality of switches in the second DC-DC converter comprises a first switch from a first leg of the second DC-DC converter and a second switch from a second leg of the second DC-DC converter.
13. The vehicle of claim 10 wherein the second plurality of switches in the first DC-DC converter comprises a first switch from a first leg of the first DC-DC converter and a second switch from a second leg of the first DC-DC converter.
14. The vehicle of claim 10 wherein the fourth plurality of switches in the second DC-DC converter comprises a first switch from a first leg of the second DC-DC converter and a second switch from a second leg of the second DC-DC converter.
15. The vehicle of claim 10 further comprising a third DC-DC converter coupled between the electric drive and the first and second DC-DC converters.
16. A method of operating a propulsion system comprising:
coupling an electric drive to a direct current (DC) link, the DC link comprising a first bus and a second bus;
coupling a first DC-DC converter to the first bus, the first DC-DC converter comprising a plurality of switch legs, the switch legs comprising at least two switches;
coupling a second DC-DC converter to the second bus and the first DC-DC converter, the second DC-DC converter comprising a plurality of switch legs, the switch legs comprising at least two switches;
coupling a first energy storage device (ESD) to the first DC-DC converter;
coupling a second ESD to the second DC-DC converter; and
configuring a controller to:
selectively transfer energy from at least one of the first ESD and the second ESD to the electric drive by controlling a first plurality of switches in the first DC-DC converter and a second plurality of switches in the second DC-DC converter; and
selectively transfer energy from the electric drive to charge at least one of the first ESD and the second ESD by controlling a third plurality of switches in the first DC-DC converter and a fourth plurality of switches in the second DC-DC converter.
17. The method of claim 16 wherein the first plurality of switches in the first DC-DC converter comprises a first switch from a first leg of the first DC-DC converter and a second switch from a second leg of the first DC-DC converter.
18. The method of claim 16 wherein the third plurality of switches in the second DC-DC converter comprises a first switch from a first leg of the second DC-DC converter and a second switch from a second leg of the second DC-DC converter.
19. The method of claim 16 wherein the second plurality of switches in the first DC-DC converter comprises a first switch from a first leg of the first DC-DC converter and a second switch from a second leg of the first DC-DC converter.
20. The method of claim 16 wherein the fourth plurality of switches in the second DC-DC converter comprises a first switch from a first leg of the second DC-DC converter and a second switch from a second leg of the second DC-DC converter.