Method and apparatus for power flow management in electro-mechanical transmissions

• US 7,070,530 B2
• Filed: 08/26/2003
• Issued: 07/04/2006
• Est. Priority Date: 08/26/2003
• Status: Active Grant

• Current Assignee: The Timken Company
• Original Assignee: The Timken Company
• Inventors: Ai, Xiaolan, Anderson, Scott
• Primary Examiner(s): LEWIS, TISHA D
• Application Number:
  US10/648,079
• Publication Number:
  US 20050049100A1
• Time in Patent Office: 1,043 Days
• Field of Search: 475 3- 5, 475/257, 475/270, 475/317, 477 3- 9, 477/15, 477/17, 701/22, 701/51, 701/53, 290/1.C, 290/4.C
• US Class Current: 475/5
• 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 6/543 the transmission being a continuously variable transmission
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/10 including control of change-speed gearings
• 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 20/10 Controlling the power contribution of each of the prime movers to meet required power demand
• 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 2200/2007 with two sets of orbital gears
• CPC Class Codes: F16H 3/727 with at least two dynamo electric machines for creating an electric power path inside the gearing, e.g. using generator and motor for a variable power torque path special adapted for a hybrid electric vehicle B60K6/20
• CPC Class Codes: F16H 3/728 with means to change ratio in the mechanical gearing
• CPC Class Codes: Y02T 10/62 Hybrid vehicles

Abstract

A method for power management in an electro-mechanical power-split infinitely variable transmission (eVT) designed to be operated within a designated speed ratio range for vehicular applications. The eVT is comprised of an input shaft coupled to the output shaft of a drive engine to receive power, a drive shaft, two electric machines, and a pair of planetary trains each having a sun member, a ring member, a set of planetary members, and a planet carrier. The eVT further contains one or more torque transfer devices to connect or disconnect members of the planetary trains for transferring torque. The drive shaft is coupled with a final drive of a vehicle for delivering or recapturing power to or from the vehicle drive wheels. The two electric machines are interconnected electronically via a power control unit and are coupled respectively with members of the planetary train. The method of power management in the eVT is selected based on the current speed and torque of the input and drive shafts, and upon the desired operating parameters.

Claims

1. A power transmission system for regulating the delivery of power to a drive shaft, said power transmission system comprising:

an engine having an output shaft;

a pair of planetary trains operatively coupled between said output shaft and said drive shaft for transmitting power output from said engine to said drive shaft, each of said planetary trains including a sun member, a ring member, a set of planet members, and a planet carrier;

a first electric machine linked with at least said one member of a first planetary train in said pair of planetary trains for receiving and transmitting power to and from said drive shaft;

a second electric machine linked with said one member of a second planetary train in said pair of planetary trains for receiving and transmitting power to and from said drive shaft;

a set of torque transfer components operatively coupled to said pair of planetary trains, said set of torque transfer components including a clutch for selectively coupling a member of said first planetary train to a member of said second planetary train, and a brake for selectively coupling a member of said second planetary train to a fixed member of the power transmission system;

an engine control unit configured to provide an engine torque responsive to a target torque level established based on a performance objective;

a power control unit operatively coupled to said first and second electric machines, said power control unit configured to control a flow of electric power to and from each of said electric machines to regulate a magnitude of delivered power to the drive shaft, and said power control unit further configured to control said at least one set of torque transfer components; and

wherein said first and second electric machines each have a power rating P_v of;

$P_v\ge <br><br>\frac{{\left(\sqrt{\frac{{\mathrm{SR}}_2}{{\mathrm{SR}}_1}<br><br>\left(1+\mathrm{\psi <br><br>}\right)}-1\right)}^2}{\frac{{\mathrm{SR}}_2}{{\mathrm{SR}}_1}-1}<br><br>P_{i<br><br>\text{\hspace{1em}<br><br>}<br><br>n}$

where P_in is power delivered to the input of said power transmission system;

where SR₁ is the output-to-input speed ratio at which said first electric machine has a zero rotational speed;

where SR₂ is the output-to-input speed ratio at which said second electric machine has a zero rotational speed; and

where ψ

is a ratio of electric input power to said first and second electric machines to mechanical input power at said engine output shaft.

2. The power transmission system of claim 1 wherein said power control unit is configured to select a control structure for said first and second electric machines responsive to a speed ratio between said drive shaft and said engine output shaft.

3. The power transmission system of claim 2 wherein said power control unit is configured to control one of said first and second electric machines to provide torque to regulate said speed ratio.

4. The power transmission system of claim 2 wherein said power control unit is configured to control one of said first and second electric machines to provide torque to balance power in said pair of planetary trains.

5. The power transmission system of claim 1 wherein said power control unit is configured to selectively control said at least one set of torque transfer components responsive to a speed ratio between said drive shaft and said engine output shaft.

6. The power transmission system of claim 5 wherein said power control unit is configured to control said at least one set of torque transfer components to selectively couple two or more components of said pair of planetary trains in an output power-split configuration.

7. The power transmission system of claim 5 wherein said power control unit is configured to control said at least one set of torque transfer components to selectively couple two or more components of said pair of planetary trains in an compound power-split configuration.

8. The power transmission system of claim 5 wherein said power control unit is configured to control said at least one set of torque transfer components to alter one or more couplings between said pair of planetary trains between an output power-split configuration and a compound power-split configuration at a node point where a rotational speed of at least one of said first and second electric machines is substantially zero.

9. The power transmission system of claim 1 further including an energy storage device operatively coupled to said first and second electric machines;

and

wherein said power control unit is operatively coupled to said energy storage device to regulate a flow of electric energy between said energy storage device, said first electric machine, and said second electric machine.

10. The power transmission system of claim 9 wherein said engine control unit is configured to shut off said engine responsive to a predetermined set of operating conditions;

and

wherein said power control unit is further configured to

control said torque transfer components to decouple said first and second planetary trains responsive to said predetermined set of operating conditions; and

to regulate a flow of electric power from said energy storage device to at least one of said first and second electric machines, wherein said electric machine provides power to said drive shaft through said second planetary train.

11. The power transmission system of claim 2 wherein said power control unit is configured responsive to said speed ratio:

(a) at or below a first node point to regulate torque from said first electric machine and said second electric machine utilizing a first control regime; and

(b) greater than said first node point to regulate torque from said first electric machine and said second electric machine utilizing a second control regime.

12. The power transmission system of claim 11 wherein said power control unit is further configured responsive to said speed ratio greater than a switch point to regulate torque from said second electric machine and said first electric machine utilizing a third control regime.

13. The power transmission system of claim 12 wherein said power control unit is further configured to optionally utilize said third control regime in place of said second control regime when said speed ratio is greater than said first node point to regulate torque from said first electric machine and said second electric machine.

14. The power transmission system of claim 11 wherein said power control unit is configured responsive to said speed ratio at or below said first node point to regulate torque from said first electric machine to:

$T_{\mathrm{E1}}=\frac{T_{\mathrm{R1}}}{K_1}+{\mathrm{\phi <br><br>}}_{\mathrm{SGI}}<br><br>\left({\mathrm{\omega <br><br>}}_e^{*}-{\mathrm{\omega <br><br>}}_e\right)$

and the power from said second electric machine to;

P_E2=−

P_E1+P<sub>pto—

e</sub>

where

T_R1 is the input torque to the ring member of the first planetary train;

K₁ is the planetary ratio of the first planetary train;

φ

SGI(ω

_e*−

ω

_e) is a feedback function of engine speed error;

P_E1 is the electrical power from the first electric machine; and

P<sub>pto—

e</sub> is the electrical power taken off from said engine and said pair of planetary trains.

15. The power transmission system of claim 11, wherein said power control unit is configured responsive to said speed ratio greater than said first node point to regulate torque from said first electric machine to:

$T_{\mathrm{E1}}=\left(\frac{K_1<br><br>K_2}{K_2+1}·<br><br>\frac{1}{{\mathrm{SR}}_{o-i}}+\frac{1-K_1<br><br>K_2}{K_2+1}\right)<br><br>\frac{T_{\mathrm{R1}}}{K_1}-\frac{K_2}{K_2+1}·<br><br>\frac{P_{\mathrm{pto\_e}}}{{\mathrm{\omega <br><br>}}_d}+{\mathrm{\phi <br><br>}}_{\mathrm{SGII}}<br><br>\left({\mathrm{\omega <br><br>}}_e^{*}-{\mathrm{\omega <br><br>}}_e\right)$

and the power from said second electric machine to;

P_E2=−

P_E1+P<sub>pto—

e</sub>

where

T_R1 is the input torque to the ring member of the first planetary train;

K₁ is the planetary ratio of the first planetary train;

K₂ is the planetary ratio of the second planetary train;

SR_o-l is the speed ratio;

φ

_SGII (ω

_e*−

ω

_e) is a feedback function of engine speed error;

P_E1 is the electrical power from the first electric machine; and

P<sub>pto—

e</sub> is the electrical power taken off from said engine and said pair of planetary trains.

16. The power transmission system of claim 11 wherein said power control unit is configured responsive to said speed ratio greater than said first node point to regulate torque from said second electric machine to:

$T_{\mathrm{E2}}=\left(\frac{K_1}{K_2+1}·<br><br>\frac{1}{{\mathrm{SR}}_{o-i}}+\frac{K_1+1}{K_2+1}\right)<br><br>\frac{T_{\mathrm{R1}}}{K_1}-\frac{1}{K_2+1}·<br><br>\frac{P_{\mathrm{pto\_e}}}{{\mathrm{\omega <br><br>}}_d}+{\mathrm{\phi <br><br>}}_{\mathrm{SGIII}}<br><br>\left({\mathrm{\omega <br><br>}}_e^{*}-{\mathrm{\omega <br><br>}}_e\right)$

and the power from said first electric machine to;

P_E1=−

P_E2+P<sub>pto—

e</sub>

where

T_R1 is the input torque to the ring member of the first planetary train;

K₁ is the planetary ratio of the first planetary train;

K₂ is the planetary ratio of the second planetary train;

SR_o-l is the speed ratio;

ω

_d is the drive shaft speed;

φ

_SGIII (ω

_e*−

ω

_e) is a feedback function of engine speed error;

P_E2 is the electrical power from the second electric machine; and

P<sub>pto—

e</sub> is the electrical power taken off from said engine and said pair of planetary trains.

17. The power transmission system of claim 11 wherein said power control unit is configured responsive to said speed ratio:

(a) greater than said first node point and below a switch point less than a second said node point to regulate torque from said first electric machine to $T_{\mathrm{E1}}=<br><br>\left(\frac{K_1<br><br>K_2}{K_2+1}·<br><br>\frac{1}{{\mathrm{SR}}_{o-i}}+\frac{1-K_1<br><br>K_2}{K_2+1}\right)<br><br>\frac{T_{\mathrm{R1}}}{K_1}-\frac{K_2}{K_2+1}·<br><br>\frac{P_{\mathrm{pto\_e}}}{{\mathrm{\omega <br><br>}}_d}+{\mathrm{\phi <br><br>}}_{\mathrm{SGii}}<br><br>\left({\mathrm{\omega <br><br>}}_e^{*}-{\mathrm{\omega <br><br>}}_e\right)$

and to regulate power from said second electric machine to;

P_E2=−

P_E1+P<sub>pto—

e</sub>

where

T_R1 is the input torque to the ring member of the first planetary train;

K₁ is the planetary ratio of the first planetary train;

K₂ is the planetary ratio of the second planetary train;

SR_o-l is the speed ratio;

φ

_SGII (ω

_e*−

ω

_e) is a feedback function of engine speed error;

P_E1 is the electrical power from said first electric machine; and

P<sub>pto—

e</sub> is the electrical power taken off from said engine and said pair of planetary trains;

(b) at or greater than said switch point to regulate torque from said second electric machine to $T_{\mathrm{E2}}=<br><br>\left(\frac{K_1}{K_2+1}·<br><br>\frac{1}{{\mathrm{SR}}_{o-i}}-\frac{K_1+1}{K_2+1}\right)<br><br>\frac{T_{\mathrm{R1}}}{K_1}-\frac{1}{K_2+1}·<br><br>\frac{P_{\mathrm{pto\_e}}}{{\mathrm{\omega <br><br>}}_d}+{\mathrm{\phi <br><br>}}_{\mathrm{SGiIi}}<br><br>\left({\mathrm{\omega <br><br>}}_e^{*}-{\mathrm{\omega <br><br>}}_e\right)$

the power from said first electric machine to;

P_E1=−

P_E2+P<sub>pto—

e</sub>

where

T_R1 is the input torque to the ring member of the first planetary train;

K₁ is the planetary ratio of the first planetary train;

K₂ is the planetary ratio of the second planetary train;

SR_o-l is the speed ratio;

ω

_d is the drive shaft speed;

φ

_SGIII (ω

_e*−

ω

_e) is a feedback function of engine speed error;

P_E2 is the electrical power from said second electric machine; and

P<sub>pto—

e</sub> is the electrical power taken off from said engine and said pair of planetary trains.

18. The power transmission system of claim 1 wherein said power control unit is further configured to control said at least one set of torque transfer components to decouple said first and second planetary trains, to drive said first electric machine from said engine through said first planetary train to generate electric power, and to drive said drive shaft in reverse operation from said second electric machine through said second planetary train;

and

wherein said power control unit is further configured to regulate a flow of electric power from said first electric machine to said second electric machine.

19. The power transmission system of claim 18, wherein said first planetary train is configured to amplify a rotational speed between said output shaft of said engine and said first electric machine;

and

wherein said second planetary train is configured to reduce a rotational speed between said second electric machine and said drive shaft.

20. The power transmission system of claim 1 wherein said engine control unit and power control unit are configured for hybrid mode operation.

21. The power transmission system of claim 1 wherein said engine control unit and power control unit are configured for non-hybrid mode operation.

22. The power transmission system of claim 1 wherein said engine control unit and power control unit are configured for electric-only operation.

23. The power transmission system of claim 1 wherein said engine control unit and power control unit are configured for series hybrid mode operation.

24. A method for series hybrid operation in a power transmission system including an engine having an output shaft, a pair of planetary units between the engine output shaft and an output drive shaft, each planetary unit having a ring member located around a sun member, planet members located between the sun and ring members, and a carrier member coupled with the planets and providing axes about which the planet members rotate, one of the members of the first planetary unit engageable with one of the members of the second planetary unit to form a first compound member branch, another of the members of the first unit engageable with another of the members of the second planetary unit to form a second compound branch, a first electric machine coupled to the sun member of the first planetary unit, and a second electric machine coupled to the sun member of the second planetary unit, a power control unit coupled to the first and second electric machines, the method comprising:

decoupling said first and second planetary trains from each other;

configuring said first planetary train as a speed increaser;

driving said first electric machine from said engine output shaft through said first planetary train to generate electrical power;

configuring said second planetary train as a speed reducer;

delivering said electrical power from said first electric machine to said second electric machine;

driving said output drive shaft from said second electric machine through said secondary planetary train; and

regulating said generation and delivery of electrical power from said first electric machine to said second electric machine to control said output drive shaft rotational speed.

25. A method for power regulation in a power transmission system including an engine having an output shaft, a pair of planetary units between the engine output shaft and an output drive shaft, each planetary unit having ring member located around a sun member, planet members located between the sun and ring members, and a carrier member coupled with the planets and providing axes about which the planet members rotate, at least one of the members of the first planetary unit engagable with one of the members of the second planetary unit to form a compound member branch, a first electric machine coupled to one member of the first planetary unit, and a second electric machine coupled to one member of the second planetary unit, a power control unit coupled to the first and second electric machines, the method comprising:

identifying the output drive shaft rotational speed and driver inputs;

calculating engine output utilizing said output drive shaft rotational speed and at least one driver input;

determining a engine operating point based on a selected performance objective;

calculating a speed ratio between said output drive shaft and said engine output shaft;

selecting an operating regime for said power transmission system based upon said calculated speed ratio;

selecting a control routine for each of said first and second electric machines based upon said calculated speed ratio;

controlling one of said electric machines to provide torque to regulate said engine rotational speed based upon said operating regime and control routines;

controlling a second of said electric machines to provide torque to balance power in said first and second planetary units based upon said operating regime and control routines; and

regulating the engine to achieve a desired engine output torque based on a selected performance objective.

26. The method for power regulation of claim 25 wherein the step of selecting a control routine for each of said electric machines is responsive to said speed ratio being:

(a) at or below a first node point, to select a first set of control routines;

(b) greater than said first node to select a second set of control routines; and

(c) greater than a switch point to select a third set of control routines.

27. The method for power regulation of claim 26 wherein said first set of control routines regulates torque from said first electric machine to:

$T_{\mathrm{E1}}=\frac{T_{\mathrm{R1}}}{K_1}+{\mathrm{\phi <br><br>}}_{\mathrm{SGI}}<br><br>\left({\mathrm{\omega <br><br>}}_e^{*}-{\mathrm{\omega <br><br>}}_e\right)$

and power from said second electric machine to;

P_E2=−

P_E1+P<sub>pto—

e</sub>

where

T_R1 is the input torque to the ring member of the first planetary train;

K₁ is the planetary ratio of the first planetary train;

φ

_SGI ( 

_e*−

ω

_e) is a feedback function of engine speed error;

P_E1 is the electrical power from the first electric machine; and

P<sub>pto—

e</sub> is the electrical power taken off from said engine and said pair of planetary trains.

28. The method for power regulation of claim 26 wherein said second set of control routines regulates torque from said first electric machine to:

$T_{\mathrm{E1}}=\left(\frac{K_1<br><br>K_2}{K_2+1}·<br><br>\frac{1}{{\mathrm{SR}}_{o-i}}+\frac{1-K_1<br><br>K_2}{K_2+1}\right)<br><br>\frac{T_{\mathrm{R1}}}{K_1}-\frac{K_2}{K_2+1}·<br><br>\frac{P_{\mathrm{pto\_e}}}{{\mathrm{\omega <br><br>}}_d}+{\mathrm{\phi <br><br>}}_{\mathrm{SGii}}<br><br>\left({\mathrm{\omega <br><br>}}_e^{*}-{\mathrm{\omega <br><br>}}_e\right)$

and power from said second electric machine to;

P_E2=−

P_E1+P<sub>pto—

e</sub>

where

T_R1 is the input torque to the ring member of the first planetary train;

K₁ is the planetary ratio of the first planetary train;

K₂ is the planetary ratio of the second planetary train;

SR_o-l is the speed ratio;

φ

_SGII (ω

_e*−

ω

_e) is a feedback function of engine speed error;

P_E1 is the electrical power from the first electric machine; and

P<sub>pto—

e</sub> is the electrical power taken off from said engine and said pair of planetary trains.

29. The method for power regulation of claim 26 wherein said third set of control routines regulates torque from said first electric machine to:

$T_{\mathrm{E2}}=<br><br>\left(\frac{K_1}{K_2+1}·<br><br>\frac{1}{{\mathrm{SR}}_{o-i}}-\frac{K_1+1}{K_2+1}\right)<br><br>\frac{T_{\mathrm{R1}}}{K_1}-\frac{1}{K_2+1}·<br><br>\frac{P_{\mathrm{pto\_e}}}{{\mathrm{\omega <br><br>}}_d}+{\mathrm{\phi <br><br>}}_{\mathrm{SGiIi}}<br><br>\left({\mathrm{\omega <br><br>}}_e^{*}-{\mathrm{\omega <br><br>}}_e\right)$

and power from said first electric machine to;

P_E1=−

P_E2+P<sub>pto—

e</sub>

where

T_R1 is the input torque to the ring member of the first planetary train;

K₁ is the planetary ratio of the first planetary train;

K₂ is the planetary ratio of the second planetary train;

SR_o-l is the speed ratio;

ω

_d is the drive shaft speed;

φ

_SGIII (ω

_e*−

ω

_e) is a feedback function of engine speed error;

P_E2 is the electrical power from the second electric machine; and

P<sub>pto—

e</sub> is the electrical power taken off from said engine and said pair of planetary trains.

30. The method for power regulation of claim 25 wherein the step of selecting an operating regime for said power transmission system is responsive to said calculated speed ratio being:

(a) at or below a first node point, to select an output-power split operating regime and to disengage the second compound branch members; and

(b) greater than said first node point to select a compound power-split operating regime and to engage the second compound branch members.

31. The method of claim 25 for power regulation in a power transmission system wherein a low-speed hybrid operating regime is selected further including the steps of:

decoupling said first and second planetary units;

regulating said engine output torque to zero;

delivering electrical power to said second electric machine from an energy storage device; and

controlling said second electric machine to provide torque to said output drive shaft through said second planetary unit.