Method of determining output torque limits of a hybrid transmission operating in a fixed gear operating range state

• US 8,249,766 B2
• Filed: 10/22/2008
• Issued: 08/21/2012
• Est. Priority Date: 11/05/2007
• Status: Active Grant

• Current Assignee: Bayerische Motoren Werke AG, Daimler AG (Mercedes-Benz Group AG), Chrysler Group LLC (Stellantis NV)
• Original Assignee: Bayerische Motoren Werke AG, GM Global Technology Operations LLC (General Motors Company), Daimler AG (Mercedes-Benz Group AG), Chrysler Group LLC (Stellantis NV)
• Inventors: Heap, Anthony H., Hsieh, Tung-Ming
• Primary Examiner(s): Fleming, Faye M.
• Application Number:
  US12/255,781
• Publication Number:
  US 20090115353A1
• Time in Patent Office: 1,399 Days
• Field of Search: 701/22, 701/51, 701/54, 318/8, 318/9, 318/139, 318/434, 477/3
• US Class Current: 701/22
• CPC Class Codes: B60K 1/02 comprising more than one electric motor
• CPC Class Codes: B60K 6/365 with the gears having orbital motion
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60K 6/547 the transmission being a stepped gearing
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/443 Torque
• CPC Class Codes: B60L 2240/486 Operating parameters
• CPC Class Codes: B60W 10/02 including control of driveline 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 10/115 with planetary gears
• CPC Class Codes: B60W 20/11 using model predictive control [MPC] strategies, i.e. control methods based on models predicting performance utilising navigation and traffic information in the control strategy B60W20/12
• CPC Class Codes: B60W 2050/0006 Digital architecture hierarchy
• CPC Class Codes: B60W 2050/0031 Mathematical model of the vehicle
• CPC Class Codes: B60W 2510/0657 Engine torque
• CPC Class Codes: B60W 2510/1005 Transmission ratio engaged
• CPC Class Codes: B60W 2510/1025 Input torque
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2540/12 Brake pedal position
• CPC Class Codes: B60W 2710/0666 : Engine torque
• CPC Class Codes: B60W 2710/083 : Torque
• CPC Class Codes: B60W 2710/1022 : Input torque
• CPC Class Codes: B60W 2710/105 : Output torque
• CPC Class Codes: F16H 2037/0866 : Power split variators with distributing differentials, with the output of the CVT connected or connectable to the output shaft
• CPC Class Codes: F16H 2037/102 : the input or output shaft of the transmission is connected or connectable to two or more differentials
• CPC Class Codes: F16H 2037/104 : Power split variators with one end of the CVT connected or connectable to two or more differentials
• CPC Class Codes: F16H 2037/106 : with switching means to provide two variator modes or ranges
• CPC Class Codes: F16H 2200/201 : with three sets of orbital gears
• CPC Class Codes: F16H 2200/2041 : with four engaging means
• CPC Class Codes: F16H 3/728 : with means to change ratio in the mechanical gearing
• CPC Class Codes: Y02T 10/40 : Engine management systems
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility

Abstract

A hybrid transmission is operative to transfer power between an input member and first and second torque machines and an output member in a fixed gear operating range state. The first and second torque machines are connected to an energy storage device. A method for controlling the hybrid transmission includes determining an output torque command at the output member, determining motor torque constraints for the first and second torque machines and determining power constraints for the energy storage device, iteratively selecting candidate input torques transferable to the input member and associated output torques, determining a second torque constraint associated with the candidate input torque, determining a third torque constraint associated with the candidate input torque, and determining a preferred input torque comprising the candidate input torque that achieves the commanded output torque at the output member and satisfies the motor torque constraints for the first and second torque machines, satisfies the power constraints for the energy storage device, and satisfies the second and third torque constraints associated with the candidate input torque when operating in the fixed gear operating range state.

Claims

1. Method for controlling a hybrid transmission operative to transfer power between an input member and first and second torque machines and an output member in a fixed gear operating range state, the first and second torque machines connected to an energy storage device, the method comprising:

determining an output torque command at the output member;

determining motor torque constraints for the first and second torque machines and determining power constraints for the energy storage device;

iteratively selecting candidate input torques transferable to the input member and associated output torques;

determining a second torque constraint associated with the candidate input torque;

determining a third torque constraint associated with the candidate input torque; and

determining a preferred input torque comprising the candidate input torque that achieves the commanded output torque at the output member and satisfies the motor torque constraints for the first and second torque machines, satisfies the power constraints for the energy storage device, and satisfies the second and third torque constraints associated with the candidate input torque when operating in the fixed gear operating range state.

2. The method of claim 1, further comprising controlling an engine operatively connected to the input member to generate the preferred input torque.

3. The method of claim 1, wherein selecting candidate input torques transferable to the input member comprises:

determining a maximum input torque and a minimum input torque;

determining torque constraints of the second and third torque constraints at the maximum input torque and at the minimum input torque; and

selecting one of the maximum input torque and the minimum input torque as an initial candidate input torque.

4. The method of claim 3, comprising iteratively generating candidate input torques by incrementally adjusting the initial candidate input torque from the selected one of the maximum and minimum input torques, and determining a corresponding output torque based upon the second and third torque constraints and the motor torque constraints and the power constraints for the energy storage device.

5. The method of claim 4, comprising:

determining torque constraints of the second and third torque constraints associated with the candidate input torque; and

determining a maximum output torque based upon the candidate input torque, the second and third torque constraints associated with the candidate input torque, the motor torque constraints and the power constraints for the energy storage device.

6. The method of claim 1, wherein selecting candidate input torques transferable to the input member comprises:

selecting a candidate input torque;

determining second and third torque constraints associated with the candidate input torque; and

determining a maximum output torque based upon the candidate input torque, the second and third torque constraints, the motor torque constraints and the power constraints for the energy storage device.

7. The method of claim 1, further comprising:

formulating mathematical equations representing the maximum and minimum motor torque constraints for the first and second torque machines respectively comprising

T<sub>A—

MIN</sub>≦

T_A≦

T<sub>A—

MAX</sub> and

T<sub>B—

MIN</sub>≦

T_B≦

T<sub>B—

MAX</sub>, and

representing the maximum and minimum battery power constraints comprising

P_BAT=P_A,ELEC+P_B,ELEC+P<sub>DC—

LOAD</sub>;

formulating a mathematical equation representing the output torque comprising

T_M1=T_A to T_M1*T_A+T_B to T_M1*T_B+Misc_—

T_M1;

formulating mathematical equations representing the second and third torque constraints respectively comprising

T_M2=T_A to T_M2*T_A+T_B to T_M2*T_B+Misc_—

T_M2 and

T_M3=T_A to T_M3*T_A+T_B to T_M3*T_B+Misc_—

T_M3;

transforming the mathematical equations representing the maximum and minimum power constraints for the energy storage device to equations of concentric circles having corresponding radii having a center locus point corresponding to a maximum charging power condition for hybrid transmission comprising

P_BAT=(T_X²+T_Y²);

transforming the mathematical equations representing the maximum and minimum motor torque constraints for the first and second torque machines to equations consisting of lines comprising

8. The method of claim 7, further comprising:

simultaneously solving the transformed mathematical equations representing the maximum and minimum motor torque constraints for the first and second torque machines, the maximum and minimum power constraints for the energy storage device and the second and third torque constraints;

determining at least one transformed achievable output torque and corresponding transformed input torque that satisfies the simultaneously solved transformed mathematical equations; and

retransforming the transformed achievable output torque to determine preferred motor torques for the first and second torque machines.

9. Method for controlling a hybrid transmission, the hybrid transmission operative in one of a plurality of fixed gear operating range states by selectively applying torque transfer clutches to transfer power between an input member and first and second torque machines and an output member, the first and second torque machines connected to an energy storage device, the method comprising:

determining an output torque command at the output member;

determining motor torque constraints for the first and second torque machines and determining battery power constraints for the energy storage device;

iteratively selecting candidate input torques transferable to the input member and associated output torques;

determining a second torque constraint based upon reactive clutch torque of a first selectively applied torque transfer clutch;

determining a third torque constraint based upon reactive clutch torque of a second selectively applied torque transfer clutch; and

determining a preferred input torque comprising the candidate input torque that achieves the commanded output torque at the output member and satisfies the motor torque constraints for the first and second torque machines, satisfies the battery power constraints, and satisfies the second and third torque constraints when operating in the fixed gear operating range state.

10. The method of claim 9, further comprising controlling an engine operatively connected to the input member to generate the preferred input torque.

11. The method of claim 9, wherein selecting candidate input torques transferable to the input member comprises:

determining a maximum input torque and a minimum input torque;

determining torque constraints of the second and third torque constraints at the maximum input torque and the minimum input torque; and

selecting one of the maximum input torque and the minimum input torque as an initial candidate input torque.

12. The method of claim 11, comprising iteratively generating candidate input torques by incrementally adjusting the initial candidate input torque from the selected one of the maximum and minimum input torques, and determining a corresponding output torque based upon the second and third torque constraints and the motor torque constraints and the battery power constraints.

13. The method of claim 12, comprising:

determining torque constraints of the first and second applied torque transfer clutches associated with the candidate input torque; and

determining a maximum output torque based upon the input torque, torque constraints of the first and second applied torque transfer clutches associated with the candidate input torque, the motor torque constraints and the battery power constraints.

14. The method of claim 9, wherein selecting candidate input torques transferable to the input member comprises:

selecting a candidate input torque;

determining torque constraints of the first and second applied torque transfer clutches associated with the candidate input torque; and

determining a maximum output torque based upon the candidate input torque, the torque constraints of the first and second applied torque transfer clutches associated with the candidate input torque, the motor torque constraints and the battery power constraints.

15. The method of claim 9, further comprising:

formulating mathematical equations representing the maximum and minimum motor torque constraints for the first and second torque machines respectively comprising

T<sub>A—

MIN</sub>≦

T_A≦

T<sub>A—

MAX</sub> and

T<sub>B—

MIN</sub>≦

T_B≦

T<sub>B—

MAX</sub>, and

representing the maximum and minimum battery power constraints comprising

P_BAT=P_A,ELEC+P_B,ELEC+P<sub>DC—

LOAD</sub>;

formulating a mathematical equation representing the output torque comprising

T_M1=T_A to T_M1*T_A+T_B to T_M1*T_B+Misc_—

T_M1;

formulating mathematical equations representing the torque constraints of the first and second applied torque transfer clutches respectively comprising

T_M2=T_A to T_M2*T_A+T_B to T_M2*T_B+Misc_—

T_M2 and

T_M3=T_A to T_M3*T_A+T_B to T_M3*T_B+Misc_—

T_M3;

transforming the mathematical equations representing the maximum and minimum battery power constraints to equations of concentric circles having corresponding radii having a center locus point corresponding to a maximum charging power condition for the hybrid transmission comprising

P_BAT=(T_X²+T_Y²)+C;

transforming the mathematical equations representing the maximum and minimum motor torque constraints for the first and second torque machines to equations consisting of lines comprising

16. The method of claim 15, further comprising:

simultaneously solving the transformed mathematical equations representing the maximum and minimum motor torque constraints for the first and second torque machines and the maximum and minimum battery power constraints, and the torque constraints of the first and second applied torque transfer clutches;

determining at least one transformed achievable output torque and corresponding transformed input torque that satisfies the simultaneously solved transformed mathematical equations; and

retransforming the transformed achievable output torque to determine preferred motor torques for the first and second torque machines.