System and method for compensation of turbo lag in hybrid vehicles

Patent metadata

Field	Value
Publication number	US-9714021-B2
Application number	US-201514838403-A
Country	US
Kind code	B2
Filing date	Aug 28, 2015
Priority date	Mar 14, 2013
Publication date	Jul 25, 2017
Grant date	Jul 25, 2017

Abstract

A system and method for compensation of turbo lag in hybrid vehicles is disclosed. The system identifies a zero boost power limit of the engine and a torque curve power limit. A turbocharger dynamic model is then developed based on measurements of the input engine power and the output max available engine power. The model is used to determine an overall propulsion power limit based on the combination of the engine and motor in operation. A power request by the driver may then be limited to the overall propulsion power limit to compensate for the effect of the turbocharger when propelling the vehicle using both the engine and motor and better simulate the engine-only response.

First claim

The invention claimed is:

1. A method of operating a hybrid vehicle using a hybrid controller, comprising:
determining a zero boost power limit of an engine of the hybrid vehicle, said engine including a turbocharger;
determining a torque curve power limit of the engine, said torque curve power limit based upon the maximum available power when the turbocharger is operating;
monitoring a current power of the engine and a current maximum available power of the engine when the current maximum available power is between the zero boost power limit and the torque curve power limit; and
determining a dynamic response model of the engine based on said monitoring, said model providing an estimation of the engine output power over time as the turbocharger substantially contributes to the output power of the engine.

2. The method of claim 1 , further comprising:
receiving a driver output torque request; and
operating the hybrid vehicle such that the collective output power of the engine and an eMachine of the hybrid vehicle is automatically limited to a turbo-equivalent power limit based on said model, said turbo-equivalent power limit representing the power limit of the engine acting alone.

3. The method of claim 2 , further comprising:
determining an actual engine torque of the engine;
multiplying said actual engine torque by a current engine speed of the engine to determine a current engine power;
determining an eMachine torque of the eMachine;
multiplying said eMachine torque by a current eMachine speed of the eMachine to determine a current eMachine output power;
adding said current engine power and said eMachine power to determine a total propulsion power;
using the dynamic model to determine the turbo-equivalent power limit; and
controlling the engine and eMachine power outputs so that the total propulsion power matches the turbo-equivalent power limit.

4. The method of claim 2 , further comprising:
setting the turbo-equivalent power limit to the zero boost power limit if the zero boost power limit is greater than said turbo-equivalent power limit.

5. The method of of claim 2 , further comprising:
setting the turbo-equivalent power limit to the torque curve power limit if the torque curve power limit is less than the turbo-equivalent power limit.

6. The method of of claim 1 , wherein said dynamic response model is determined by the controller using infinite impulse response filtering.

7. The method of claim 1 , wherein said dynamic response model is represented discreetly by the equation:
y ([ n +1 ]T s )=α y ( nT s )+ k (1−α) u ( nT s )

where T is a constant, k is a constant,

α
=

e

-

T
S

T

,

 T s is a discrete sample time, y([n +1]T s ) is the turbo-equivalent output power of the n +1 iteration, y(nT s ) is the turbo-equivalent output power value of the n interation, and u(nT s ) is the current engine power of the n iteration.

8. The method of claim 7 , wherein T and k are adaptively determined by infinite impulse response filtering.

9. The method claim 1 , wherein said zero boost power limit is determined by monitoring the maximum available torque of the engine while the engine is idling.

10. The method of claim 9 , wherein said zero boost power limit is determined by multiplying a current engine speed by the average of the maximum available torque of the engine when idling.

11. A hybrid system, comprising:
an engine having a turbocharger;
an engine controller operatively coupled to the engine;
an eMachine;
a hybrid controller operatively coupled to the eMachine and in communication with the engine controller;
wherein the hybrid controller is configured to:
determine a zero boost power limit of the engine;
receive torque curve information from the engine controller;
determine a torque curve power limit of the engine from said torque curve information;
monitor a current power of the engine and a current maximum available power of the engine when the current maximum available power is between the zero boost power limit and the torque curve power limit; and
determine a dynamic response model of the engine based on said monitoring, said model providing an estimation of the engine output power over time as the turbocharger substantially contributes to the output power of the engine.

12. The method of claim 11 , wherein the hybrid controller is further configured to:
receive a driver output torque request from said engine controller; and
operate the hybrid vehicle such that the collective output power of the engine and an eMachine of the hybrid vehicle is automatically limited to a turbo-equivalent power limit based on said model, said turbo-equivalent power limit representing the power limit of the engine acting alone.

13. The system of claim 12 , wherein the hybrid controller is further configured to:
receive an actual engine torque and a current engine speed from the engine controller;
multiply said actual engine torque by said current engine speed to determine a current engine power;
determine an eMachine torque of the eMachine;
multiply said eMachine torque by a current eMachine speed of the eMachine to determine a current eMachine output power; and
add said current engine power and said eMachine power to determine a total propulsion power;
using the dynamic model to determine the turbo-equivalent power limit; and
controlling the engine and eMachine power outputs so that the total propulsion power matches the turbo-equivalent power limit.

14. The system of claim 12 , wherein the hybrid controller is further configured to set the turbo-equivalent power limit to the zero boost power limit if the zero boost power limit is greater than said turbo-equivalent power limit.

15. The system of claim 12 , wherein the hybrid controller is further configured to set the turbo-equivalent power limit to the torque curve power limit if the torque curve power limit is less than the turbo-equivalent power limit.

16. The system of claim 12 , wherein said dynamic response model is determined by the hybrid controller using infinite impulse response filtering.

17. The system of claim 11 , wherein said dynamic response model is
represented discreetly by the equation:
y ([ n +1 ]T s )=α y ( nT s )+ k (1−α) u ( nT s )

where T is a constant, k is a constant,

α
=

e

-

T
S

T

,

 T s is a discrete sample time, y([n +1]T s ) is the turbo-equivalent output power of the n +1 iternation, y(nT s ) is the turbo-equivalent output power value of the n iteration, and u(nT s ) is the current engine power of the n iteration.

18. The system of claim 17 , wherein T and k are adaptively determined by th

Assignees

• Allison Transm Inc

Inventors

• West Stephen T

Classifications

• B60W2050/0039

  of the propulsion unit · CPC title

• Y10S903/93

  Conjoint control of different elements · CPC title

• B60W20/11

  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 title

• B60K6/24

  characterised by the combustion engines · CPC title

• F02D2200/1004

  Estimation of the output torque · CPC title