Hybrid powertrain and method for controlling the same

Patent metadata

Field	Value
Publication number	US-2016009268-A1
Application number	US-201414329002-A
Country	US
Kind code	A1
Filing date	Jul 11, 2014
Priority date	Jul 11, 2014
Publication date	Jan 14, 2016
Grant date	—

Abstract

A method for controlling a hybrid powertrain includes the following steps: receiving a torque request; determining a plurality of possible motor torques for the first and second electric machines capable of achieving the torque requested; determining system power losses of the powertrain for all the possible motor torques for the first and second electric machines capable of achieving the torque requested; determining a lowest power loss of the system power losses determined for the plurality of possible motor torques for the first and second electric machines; determining a first operating torque for the first electric machine and a second operating torque for the second electric machine that correspond with the lowest power loss; and commanding the first electric machine to generate the first operating torque and the second electric machine to generate the second operating torque in order to achieve the torque requested while minimizing the system power losses.

First claim

1 . A method for controlling a hybrid powertrain, the powertrain including a drive axle, an engine operatively coupled to the drive axle, a first electric machine operatively coupled to the drive axle, a second electric machine operatively coupled to the drive axle, and a controller in communication with the engine, the first electric machine, and the second electric machine, the method comprising:
receiving, via the controller, a torque request; determining, via the controller, whether the hybrid powertrain is operating in the electric-only operating mode, wherein the engine is off when the hybrid powertrain is operating in the electric-only mode; determining, via the controller, a plurality of possible motor torques of the first and second electric machines capable of achieving the torque requested only if the hybrid powertrain is operating in the electric-only mode; determining system power losses of the powertrain for all the possible motor torques of the first and second electric machines capable of achieving the torque requested while the hybrid powertrain is operating in the electric-only mode; determining a lowest power loss of the system power losses determined for the plurality of possible motor torques of the first and second electric machines while the hybrid powertrain is operating in the electric-only mode; determining a first operating torque for the first electric machine and a second operating torque for the second electric machine that correspond to the lowest power loss while the hybrid powertrain is operating in the electric-only mode; and commanding, via the controller, the first electric machine to generate the first operating torque and the second electric machine to generate the second operating torque in order to achieve the torque requested while minimizing the system power losses while the hybrid powertrain is operating in the electric-only mode.

2 . The method of claim 1 , further comprising determining a maximum output torque and a minimum output torque capable of being jointly generated by the first and second electric machines.

3 . The method of claim 2 , wherein the maximum output torque and the minimum output torque are based, at least in part, on a maximum battery power and a minimum battery power.

4 . The method of claim 3 , wherein the maximum output torque and the minimum output torque are based, at least in part, on a maximum motor torque of the first electric machine, a maximum motor torque of the second electric machine, and a minimum motor torque of the first electric machine, and a minimum motor torque of the second electric machine.

5 . The method of claim 4 , wherein the maximum output torque and the minimum output torque are based, at least in part, on an input brake torque capacity, wherein the input brake capacity is a capacity of an input brake connected to an engine crankshaft of the engine, the input brake is movable relative to a stationary member of the hybrid powertrain between an engaged position and a disengaged position, the input brake interconnects the engine crankshaft to the stationary member in the engaged position so as to prevent rotation of the engine crankshaft, and the input brake is decoupled from the stationary member in the disengaged position so as to allow the engine crankshaft to rotate.

6 . The method of claim 7 , further comprising determining whether the torque requested is less than or equal to the maximum output torque and greater than or equal to the minimum output torque, wherein the first operating torque for the first electric machine and the second operating torque for the second electric machine are based, at least in part, on the maximum output torque and the minimum output torque if the torque requested is greater than or equal to the maximum output torque and the input brake is in the engaged position.

7 . The method of claim 5 , further comprising determining, via the controller, whether the input brake is in the engaged position, wherein the maximum output torque and the minimum output torque are determined only if the input brake is in the engaged position.

8 . The method of claim 6 , wherein the first operating torque for the first electric machine and the second operating torque for the second electric machine are based, at least in part, on the maximum output torque and the minimum output torque if the torque requested is less than or equal to the minimum output torque and the input brake is in the engaged position.

9 . The method of claim 6 , wherein determining, via the controller, the plurality of possible motor torques for the first and second electric machines capable of achieving the torque requested is performed if the torque requested is less than or equal to the maximum output torque and greater than or equal to the minimum output torque and the input brake is in the engaged position.

10 . The method of claim 9 , wherein determining the system power losses includes determining motor losses, inverter losses, load dependent mechanical losses, and battery losses for all the possible motor torques for the first and second electric machines capable of achieving the torque requested, and the system power losses are not based on unloaded mechanical losses.

11 . A hybrid powertrain, comprising:
a drive axle; an engine operatively coupled to the drive axle; a first electric machine operatively coupled to the drive axle; a second electric machine operatively coupled to the drive axle; and a controller in communication with the engine, the first electric machine, and the second electric machine, wherein the controller is programmed to:
receive a torque request;
determine a plurality of possible motor torques for the first and second electric machines capable of achieving the torque requested;
determine system power losses of the powertrain for all the possible motor torques of the first and second electric machines capable of achieving the torque requested while the engine is off;
determine a lowest power loss of the system power losses determined for the plurality of possible motor torques of the first and second electric machines while the engine is off;
determine a first operating torque for the first electric machine and a second operating torque for the second electric machine that correspond with the lowest power loss while the engine is off; and
command the first electric machine to generate the first operating torque and the second electric machine to generate the second operating torque in order to achieve the torque requested while minimizing the system power losses while the engine is off.

12 . The hybrid powertrain of claim 11 , wherein the controller is programmed to determine a maximum output torque and a minimum output torque capable of being jointly generated by the first and second electric machines only if the hybrid powertrain is operating in a mode selected from a group consisting of an electric-only operating mode and an engine-off, regenerative mode.

13 . The hybrid powertrain of claim 12 , further comprising an input brake connected to an engine crankshaft of the engine, wherein the input brake is movable relative to a stationary member of the hybrid powertrain between an engaged position and a disengaged position, the input brake interconnects the engine crankshaft to the stationary member in the engaged position so as to prevent rotation of the engine crankshaft, and the input brake is decoupled from the stationary member in the disengaged position so as to allow the engine crankshaft to rotate, the engine is off and the input brake is in the engaged position when the hybrid powertrain is operating in the electric-only operatin

Assignees

• Gm Global Tech Operations Inc

Inventors

• Tamai Goro
• Wang Lan
• Bucknor Norman K

Classifications

• Y02T10/62

  Hybrid vehicles · CPC title

• B60W20/10 Primary

  Controlling the power contribution of each of the prime movers to meet required power demand · CPC title

• B60W2710/083

  Torque · CPC title

• B60W10/08 Primary

  including control of electric propulsion units, e.g. motors or generators · CPC title

• B60W2510/083

  Torque · CPC title