Speed controlling an electric machine of a hybrid electric vehicle

• US 10,640,106 B2
• Filed: 08/19/2016
• Issued: 05/05/2020
• Est. Priority Date: 08/19/2016
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Meyer, Jason, Johri, Rajit, Doering, Jeffrey Allen, Thompson, Scott James
• Primary Examiner(s): Bishop, Erin D
• Application Number:
  US15/241,995
• Publication Number:
  US 20180050687A1
• Time in Patent Office: 1,355 Days
• CPC Class Codes: B60K 2006/268 Electric drive motor starts the engine, i.e. used as starter motor
• CPC Class Codes: B60L 15/2054 by controlling transmissions or clutches
• CPC Class Codes: B60W 10/02 including control of driveline clutches
• CPC Class Codes: B60W 10/026 of lock-up clutches
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/40 Controlling the engagement or disengagement of prime movers, e.g. for transition between prime movers power-up or power-down of the driveline B60W30/192
• CPC Class Codes: B60W 2050/0008 Feedback, closed loop systems or details of feedback error signal
• CPC Class Codes: B60W 2050/0012 Feedforward or open loop systems
• CPC Class Codes: B60W 2510/0233 of torque converter lock-up clutch
• CPC Class Codes: B60W 2510/0241 Clutch slip, i.e. difference between input and output speeds
• CPC Class Codes: B60W 2510/081 Speed
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2710/021 Clutch engagement state
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

A hybrid powertrain includes an engine having a crankshaft, and an electric motor having a rotor selectively coupled to the crankshaft via a disconnect clutch. The powertrain further includes a transmission having a torque converter that has an impeller fixed to the rotor. A controller is configured to, in response to the engine starting, generate a torque command for the motor that defines a magnitude that is based on a difference between a target impeller speed and a measured impeller speed.

Claims

1. A hybrid powertrain comprising:

an engine having a crankshaft;

an electric motor including a rotor selectively coupled to the crankshaft via a disconnect clutch;

a transmission including a torque converter having an impeller fixed to the rotor and a turbine; and

a controller configured to, in response to the engine starting, generate a torque command for the motor that defines a magnitude that is based on a difference between a target impeller speed, that is based on a measured speed of the turbine, and a measured impeller speed.

2. The hybrid powertrain of claim 1, wherein the torque converter further includes a bypass clutch configured to selectively lock the impeller and the turbine relative to each other.

3. The hybrid powertrain of claim 2, wherein the controller is further configured to generate the torque command in response to the bypass clutch being open or slipping.

4. The hybrid powertrain of claim 1, wherein the torque command further includes a feedforward component, and a feedback component that is based on the difference between the target impeller speed and the measured impeller speed.

5. The hybrid powertrain of claim 1, wherein the magnitude increases in response to the difference between the target impeller speed and the measured impeller speed increasing.

6. The hybrid powertrain of claim 5, wherein the magnitude decreases in response to the difference between the commanded impeller speed and the measured impeller speed decreasing.

7. The hybrid powertrain of claim 1, wherein the controller is further configured to command the starting of the engine.

8. The hybrid powertrain of claim 1 further comprising a speed sensor disposed within the electric machine and configured to output a speed signal indicating the measured impeller speed.

9. A vehicle comprising:

an engine including a crankshaft;

a transmission including a torque converter having an impeller, and a turbine fixed to a turbine shaft that is driveably connected to driven wheels of the vehicle, wherein the torque converter further includes a bypass clutch configured to selectively lock the impeller and turbine relative to each other;

an electric machine including a rotor selectively coupled to the crankshaft via a disconnect clutch and fixed to the impeller;

a speed sensor disposed within the transmission and configured to output a speed signal indicating a measured impeller speed; and

at least one controller configured to, in response to a change in torque split between the engine and the electric machine, and the bypass clutch being open or slipping, generate a torque command for the electric machine that includes a feedforward component, and a feedback component that is based on an error between a target impeller speed and the measured impeller speed, wherein the target impeller speed is based on a measured speed of the turbine.

10. The vehicle of claim 9, wherein the change in torque split includes starting of the engine.

11. The vehicle of claim 10, wherein the controller is further programmed to command closing of the disconnect clutch in response to a request to start the engine.

12. The vehicle of claim 9, wherein the feedforward component is based on a capacity of the disconnect clutch.

13. The vehicle of claim 9, wherein the feedforward component is further based on a pedal position of an accelerator pedal of the vehicle.

14. The vehicle of claim 9, wherein a magnitude of the feedback component increases in response to the error increasing.

15. A method of controlling an electric machine of a hybrid powertrain that includes an engine, a transmission, and a torque converter having a turbine, an impeller fixed to the electric machine, and a bypass clutch, the method comprising:

generating a command to start the engine; and

in response to the command to start the engine and the bypass clutch being open or slipping, generating a speed-control torque command for the electric machine that defines a magnitude that is based on a difference between a target impeller speed, that is based on a measured speed of the turbine, and a measured impeller speed.

16. The method of claim 15 further comprising, in response to completion of the engine starting, generating a torque-control torque command for the electric machine that defines a magnitude that is based on driver-demanded torque.

17. The method of claim 15 further comprising, in response to the bypass clutch being closed, generating a torque-control torque command for the electric machine that defines a magnitude that is based on driver-demanded torque.