Electric drive system and energy management method
An electric drive system includes an energy storage system (ESS), a power conversion system, and an alternating current (AC) traction system. The ESS provides or receives electric power. The ESS includes a first energy storage unit and a second energy storage unit. The power conversion system is electrically coupled to the ESS for converting an input power to an output power. The AC traction system is electrically coupled to the power conversion system for converting the output power of the power conversion system to mechanical torques. The AC traction system includes a first AC drive device and a second AC drive device. An energy management system (EMS) is in electrical communication with the ESS, the AC traction system, and the power conversion system for providing control signals.
1. An electric drive system for a vehicle, comprising:
an energy storage system (ESS);
a power conversion system coupled to the ESS;
a first AC motor coupled to the power conversion system;
a second AC motor coupled to the power conversion system;
a power split device coupled between the first and second AC motors and a load of the vehicle, the power split device comprising an arrangement of gears for processing mechanical torque provided by the AC motors or load; and
an energy management system (EMS) configured to selectively:
enable both the first and second AC motors to provide a first mechanical torque to the load through the power split device to drive the vehicle; and
enable the first AC motor to provide a second mechanical torque to the load through the power split device to drive the vehicle, and enable the second AC motor to operate as a generator to receive a third mechanical torque from the power split device to generate electrical power.
2. The electric drive system of claim 1 , further comprising a transmission device coupled between the first AC motor and the power split device.
3. The electric drive system of claim 1 , wherein the ESS comprises an energy storage unit.
4. The electric drive system of claim 1 , wherein the ESS comprises a first energy storage unit and a second energy storage unit.
5. The electric drive system of claim 4 , wherein the first energy storage unit comprises a battery and the second energy storage unit comprises an ultracapacitor.
6. The electric drive system of claim 4 , wherein the power conversion system comprises a first power conversion device coupled to the first energy storage unit and a second power conversion device coupled to the second energy storage unit.
7. The electric drive system of claim 1 , further comprising a first inverter coupled between the power conversion system and first AC motor, and a second inverter coupled between the power conversions system and second AC motor.
8. The electric drive system of claim 1 , wherein the first AC motor comprises a permanent magnet motor.
9. The electric drive system of claim 1 , wherein the second AC motor comprises an induction motor.
10. The electric drive system of claim 1 , wherein the electrical power generated by the second AC motor is provided to the ESS.
11. The electric drive system of claim 1 , wherein the electrical power generated by the second AC motor is provided to the first AC motor.
12. The electric drive system of claim 1 , wherein the EMS is further configured to enable the first AC motor to operate as a generator to generate electrical power.
13. The electric drive system of claim 12 , wherein the electrical power generated by the first AC motor is provided to the ESS.
14. The electric drive system of claim 1 , wherein the ESS comprises an energy storage unit.
15. An electric drive system for a vehicle, comprising:
an energy storage unit;
a power conversion device coupled to the energy storage unit;
a traction system coupled to the power conversion device, the traction system comprising:
a first motor/generator coupled to the power conversion device; and
a second motor/generator coupled to the power conversion device;
a power split device coupled between the first motor/generator, the second motor/generator, and a load of the vehicle, the power split device comprising an arrangement of gears for processing mechanical torque provided by the motor/generators or load; and
an energy management system (EMS) configured to selectively:
enable both the first motor/generator and second motor/generator to operate as motors to provide a first mechanical torque to the load through the power split device to drive the vehicle during a first mode of operation; and
enable the first motor/generator to operate as a motor to provide a second mechanical torque to the load through the power split device to drive the vehicle, and enable the second motor/generator to operate as a generator to receive a third mechanical torque from the power split device to generate electrical power, during a second mode of operation.
16. The electric drive system of claim 15 , further comprising a transmission device coupled between the first motor/generator and the power split device.
17. The electric drive system of claim 15 , wherein the first motor/generator comprises a permanent magnet motor.
18. The electric drive system of claim 15 , wherein the second motor/generator comprises an induction motor.
19. The electric drive system of claim 15 , wherein the electrical power generated by the second motor/generator is provided to the ESS during the second mode of operation.
20. The electric drive system of claim 15 , wherein the electrical power generated by the second motor/generator is provided to the first motor/generator during the second mode of operation.
21. The electric drive system of claim 15 , wherein the EMS is further configured to enable the first motor/generator to operate as a generator to generate electrical power.
22. An electric drive system for a vehicle, comprising:
an energy storage system (ESS);
a power conversion system coupled to the ESS;
a first AC motor coupled to the power conversion system;
a second AC motor coupled to the power conversion system;
a transmission device coupled to the first AC motor for processing mechanical torque;
a power split device coupled between the transmission device and second AC motor, the power split device comprising an arrangement of gears for processing mechanical torque; and
an energy management system (EMS) configured to selectively:
enable both the first and second AC motors to provide a first mechanical torque to a load through the transmission device and power split device to drive the vehicle during a first mode of operation; and
enable the first AC motor to provide a second mechanical torque to the load through the transmission device to drive the vehicle and enable the second AC motor to operate as a generator to receive a third mechanical torque from the power split device to generate electrical power during a second mode of operation.
23. The electric drive system of claim 14 , wherein the power conversion system comprises a power conversion device coupled to the energy storage unit.
24. The electric drive system of claim 22 , further comprising a first inverter coupled between the power conversion system and first AC motor, and a second inverter coupled between the power conversions system and second AC motor.
25. The electric drive system of claim 22 , wherein the electrical power generated by the second AC motor is provided to the ESS.
26. The electric drive system of claim 22 , wherein the electrical power generated by the second AC motor is provided to the first AC motor.
27. The electric drive system of claim 22 , wherein the EMS is further configured to enable the first AC motor to operate as a generator to generate electrical power.
28. The electric drive system of claim 27 , wherein the electrical power generated by the first AC motor is provided to the ESS.