Method of determining output torque limits of a hybrid transmission operating in a fixed gear operating range state
View Patent ↗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.
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 A — MIN ≦T A ≦T A — MAX and
T B — MIN ≦T B ≦T B — MAX , and
representing the maximum and minimum battery power constraints comprising
P BAT =P A,ELEC +P B,ELEC +P DC — LOAD ;
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 X 2 +T Y 2 );
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
[
T
X
T
Y
]
=
[
A
1
0
0
B
1
]
*
[
T
A
T
B
]
+
[
A
2
B
2
]
;
transforming the mathematical equations representing the second and third torque constraints to equations consisting of lines respectively comprising
T M2 =T A to T M2 *( T X −A 2 )/ A 1 +T B to T M2 *( T T −B 2 )/ B 1 +Misc — T M2 and
T M3 =T A to T M3 *( T X −A 2 )/ A 1 +T B to T M3 *( T Y −B 2 )/ B 1 +Misc — T M3 ; and
transforming the mathematical equations representing the output torque to an equation consisting of a line comprising
T M1 =T A to T M1 *( T X −A 2 )/ A 1 +T B to T M1 *( T Y −B 2 )/ B 1 +Misc — T M1 .
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 A — MIN ≦T A ≦T A — MAX and
T B — MIN ≦T B ≦T B — MAX , and
representing the maximum and minimum battery power constraints comprising
P BAT =P A,ELEC +P B,ELEC +P DC — LOAD ;
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 X 2 +T Y 2 )+ 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
[
T
X
T
Y
]
=
[
A
1
0
0
B
1
]
*
[
T
A
T
B
]
+
[
A
2
B
2
]
;
transforming the mathematical equations representing the torque constraints of the first and second applied torque transfer clutches to equations consisting of lines respectively comprising
T M2 =T A T M2 *( T X −A 2 )/ A 1 +T B to T M2 *( T Y −B 2 )/ B 1 +Misc — T M2 and
T M3 =T A to T M3 *( T X −A 2 )/ A 1 +T B to T M3 *( T Y −B 2 )/ B 1 +Misc — T M3 ; and
transforming the mathematical equations representing the output torque to an equation consisting of a line comprising:
T M1 =T A to T M1 *( T X −A 2 )/ A 1 +T B to T M1 *( T Y −B 2 )/ B 1 +Misc — T M1 .
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.