Methods and systems for vehicle drive

A method of operating a first electric machine and a second electric machine in a vehicle drive, the first electric machine electrically coupled to the second electric machine by a bus and the vehicle drive configured to propel a vehicle, the method comprising:

• operating the vehicle drive in a first operating mode by:
• operating the first electric machine in a voltage mode, wherein the first electric machine at least one of produces and consumes electrical power at the bus to maintain a first voltage on the bus when operated in the voltage mode;
• and
• operating the second electric machine in a torque mode, wherein the second electric machine at least one of produces and consumes electrical power at the bus to maintain a first torque at an output of the second electric machine when operated in the torque mode;
• wherein a sum of the electrical power at least one of produced and consumed by the first electric machine, the electrical power losses, and the electrical power at least one of produced and consumed by the second electric machine is zero in the first operating mode;
• and
• operating the vehicle drive in a second operating mode by:
• operating the first electric machine in the torque mode, wherein the first electric machine at least one of produces and consumes electrical power at the bus to maintain a second torque at an output of the first electric machine when operated in the torque mode;
• and
• operating the second electric machine in the voltage mode, wherein the second electric machine at least one of produces and consumes electrical power at the bus to maintain a second voltage on the bus when operated in the voltage mode;
• wherein a sum of the electrical power at least one of produced and consumed by the first electric machine, the electrical power losses, and the electrical power at least one of produced and consumed by the second electric machine is zero in the second operating mode.

A system for operating a first electric machine and a second electric machine in a vehicle drive, the first electric machine electrically coupled to the second electric machine by a bus and the vehicle drive configured to propel a vehicle, the system comprising a processing circuit configured to:

• operate the vehicle drive in a first operating mode by:
• operating the first electric machine to regulate electrical power at the bus to maintain a first voltage on the bus;
• and
• operating the second electric machine to consume electrical power from the bus;
• wherein a sum of the electrical power regulated by the first electric machine, the electrical power losses, and the electrical power consumed by the second electric machine is zero in the first operating mode;
• and
• operate the vehicle drive in a second operating mode by:
• operating the first electric machine to consume electrical power from the bus;
• and
• operating the second electric machine to regulate electrical power at the bus to maintain a second voltage on the bus;
• wherein a sum of the electrical power consumed by the first electric machine, the electrical power losses, and the electrical power regulated by the second electric machine is zero in the second operating mode.