Electric driveline system and electric driveline system operating method
Methods and systems for an electric driveline are provided. In one example, the electric driveline system includes a transmission with a planetary gearset, with a first gearset component rotationally coupled to a first electric machine and a second electric machine, and a first output interface and a second output interface rotationally coupled to a first axle and a second axle, respectively, and a second gearset component in the planetary gearset. The driveline system further includes a first friction clutch configured to selectively brake a third gearset component and a second friction clutch configured to selectively couple the first gearset component to an output shaft.
1. An electric driveline system, comprising:
a transmission including:
a planetary gearset with a first gearset component that is rotationally coupled to a first electric machine and a second electric machine;
a first output interface and a second output interface rotationally coupled to a first axle and a second axle, respectively, and a second gearset component in the planetary gearset;
a first friction clutch coupled to a third gearset component in the planetary gearset and configured to selectively brake the third gearset component;
a second friction clutch configured to selectively couple the first gearset component to an output shaft; and
a first disconnect clutch and a second disconnect clutch coupled to the first and second output interfaces, respectively.
2. The electric driveline system of claim 1 , further comprising a control unit including instructions that when executed cause the control unit to
operate the first friction clutch and the second friction clutch to synchronously shift between a first gear configuration and a second gear configuration.
3. The electric driveline system of claim 1 , wherein the first gearset component is a sun gear, the second gearset component is a carrier, and the third gearset component is a ring gear.
4. The electric driveline system of claim 1 , further comprising:
a third electric machine mechanically driving a lubricant pump; and
a control unit including instructions that when executed cause the control unit to:
adjust a speed of the lubricant pump based on a lubricant demand of the transmission;
wherein:
the third electric machine receives electric power from a lower voltage inverter and the first and second electric machines receive electric power from higher voltage inverters; or
the first electric machine, the second electric machine, and the third electric machine receive electric power from inverters that operate with a similar voltage.
5. The electric driveline system of claim 1 , further comprising a coolant circuit with coolant conduits routed through the first and second electric machines and a heat exchanger coupled to the transmission.
6. The electric driveline system of claim 1 , wherein the first and second electric machines are arranged parallel to one another.
7. The electric driveline system of claim 1 , further comprising a mechanical power take-off (PTO) and a PTO clutch coupled to the output shaft of the first electric machine or the second electric machine.
8. The electric driveline system of claim 7 , further comprising a control unit including instructions that when executed cause the control unit to:
allocate mechanical power distribution to the mechanical PTO and the output shaft based on a prioritization of a PTO power demand and a traction power demand.
9. The electric driveline system of claim 1 , further comprising:
a first inverter electrically coupled to the first electric machine and a traction battery;
a second inverter electrically coupled to the second electric machine and the traction battery; and
a control unit including instructions that when executed cause the control unit to:
coordinate electric power flow to the first and second inverters from the traction battery.
10. The electric driveline system of claim 1 , further comprising a heat exchanger coupled to a transmission housing or a vehicle frame and configured to transfer heat from a lubricant in the transmission to a coolant that is circulated through the heat exchanger.
11. A method for operation of an electric driveline system, comprising:
transferring rotational energy to a sun gear of a planetary gearset from a first electric machine and a second electric machine; and
shifting between a first gear configuration and a second gear configuration via:
engagement of a first friction clutch coupled to a ring gear of the planetary gearset and a synchronizer coupled to the first friction clutch; and
disengagement of a second friction clutch coupled to the sun gear of the planetary gearset; and
transferring rotational energy to one or more of a first axle and a second axle from a carrier in the planetary gearset.
12. The method of claim 11 , further comprising transferring rotational energy from the first electric machine to a power take-off (PTO).
13. The method of claim 12 , further comprising disconnecting the first axle from the electric driveline system via operation of a first disconnect clutch.
14. The method of claim 13 , further comprising disconnecting the second axle from the electric driveline system via operation of a second disconnect clutch.
15. The method of claim 11 , wherein the step of shifting between the first gear configuration and the second gear configuration is implemented by a driveline control unit (DCU) in electronic communication with a vehicle control unit (VCU).
16. An electric driveline system, comprising:
a powershift transmission including:
a planetary gearset with sun gear rotationally coupled to a first electric machine and a second electric machine;
a first output interface and a second output interface coupled to a carrier in the planetary gearset and to a first axle and a second axle, respectively;
a first friction clutch and a synchronizer coupled to a ring gear in the planetary gearset, wherein the first friction clutch is configured to brake the ring gear to shift the planetary gearset between a first gear configuration and a second gear configuration; and
a second friction clutch coupled to the sun gear and configured to selectively couple the sun gear to an output shaft.
17. The electric driveline system of claim 16 , further comprising:
a mechanical power take-off (PTO) and a PTO clutch coupled to the output shaft of the first electric machine or the second electric machine; and
a control unit including instructions that when executed cause the control unit to:
allocate mechanical power distribution to the mechanical PTO and the planetary gearset based on a prioritization of a PTO power demand and a traction power demand.
18. The electric driveline system of claim 16 , further comprising:
a third electric machine mechanically driving a lubricant pump; and
a control unit including instructions that when executed cause the control unit to:
operate the lubricant pump and a valve coupled to the powershift transmission to adjust a flowrate of lubricant to the planetary gearset based on lubrication demands of the powershift transmission.
19. The electric driveline system of claim 18 , wherein:
the third electric machine receives electric power from a lower voltage inverter and the first and second electric machines receive electric power from higher voltage inverters; or
the first electric machine, the second electric machine, and the third electric machine receive electric power from inverters that have a similar operating voltage.