Torque security of MPC-based powertrain control

Patent metadata

Field	Value
Publication number	US-10125712-B2
Application number	US-201715436235-A
Country	US
Kind code	B2
Filing date	Feb 17, 2017
Priority date	Feb 17, 2017
Publication date	Nov 13, 2018
Grant date	Nov 13, 2018

Abstract

A propulsion system, control system, and method are provided that use model predictive control to generate an initial selected engine output torque value. A minimum torque limit is determined by selecting a minimum acceptable engine output torque. A maximum torque limit is determined by selecting a maximum acceptable engine output torque. A desired engine output torque value is set as: a) the minimum torque limit, if the initial selected engine output torque value is less than the minimum torque limit; b) the maximum torque limit, if the initial selected engine output torque value is greater than the maximum torque limit; or c) the initial selected engine output torque value, if the initial selected engine output torque value is neither greater than the maximum torque limit nor less than the minimum torque limit.

First claim

What is claimed is:

1. A method for controlling a propulsion system of a motor vehicle, the method comprising:
determining an initial selected engine output torque value using a model predictive control system;
determining at least one of a first minimum acceptable engine output torque and a second minimum acceptable engine output torque, the first minimum acceptable engine output torque being based on an engine output torque requested and a predetermined engine output torque minimum constant, and the second minimum acceptable engine output torque being based on an axle torque requested and a predetermined axle torque minimum constant;
determining a minimum torque limit by selecting one of the first and second minimum acceptable engine output torques;
determining whether the initial selected engine output torque value is less than the minimum torque limit;
if the initial selected engine output torque value is less than the minimum torque limit, setting a desired engine output torque value as the minimum torque limit;
determining at least one of a first maximum acceptable engine output torque and a second maximum acceptable engine output torque, the first maximum acceptable engine output torque being based on the engine output torque requested and a predetermined engine output torque maximum constant, and the second maximum acceptable engine output torque being based on the axle torque requested and a predetermined axle torque maximum constant;
determining a maximum torque limit by selecting one of the first and second maximum acceptable engine output torques;
determining whether the initial selected engine output torque value is greater than the maximum torque limit;
if the initial selected engine output torque value is greater than the maximum torque limit, setting the desired engine output torque value as the maximum torque limit; and
if the initial selected engine output torque value is neither greater than the maximum torque limit nor less than the minimum torque limit, setting the desired engine output torque value as the initial selected engine output torque value.

2. The method of claim 1 , wherein:
the step of determining at least one of a first minimum acceptable engine output torque and a second minimum acceptable engine output torque includes determining both of the first and second minimum acceptable engine output torques;
the step of determining the minimum torque limit includes selecting the lower of the first and second minimum acceptable engine output torques;
the step of determining at least one of a first maximum acceptable engine output torque and a first maximum acceptable engine output torque includes determining both of the first and second maximum acceptable engine output torques; and
the step of determining the maximum torque limit includes selecting the greater of the first and second maximum acceptable engine output torques.

3. The method of claim 2 , further comprising:
determining the first minimum acceptable engine output torque (Te_1_acc min ) by subtracting the predetermined engine output torque minimum constant from the engine output torque requested;
determining the first maximum acceptable engine output torque (Te_1_acc max ) by adding the predetermined engine output torque maximum constant to the engine output torque requested;
determining the second minimum acceptable engine output torque (Te_2_acc min ) with the following equation:

Te_
⁢
2
⁢

_acc
min

=

Ta_r
-

P
2

⁢

D
3

⁢
A

rat_a
⁢
_m
*
FD

where Ta_r is the axle torque requested, P 2 D 3 A is the predetermined axle torque minimum constant, rat_a_m is a measured actual transmission ratio, and FD is a final drive ratio; and
determining the second maximum acceptable engine output torque (Te_2_acc max ) with the following equation:

Te_
⁢
2
⁢

_acc
max

=

Ta_r
+

P
2

⁢

D
2

⁢
A

rat_a
⁢
_m
*
FD

where P 2 D 2 A is the predetermined axle torque maximum constant.

4. The method of claim 3 , further comprising:
determining whether the desired engine output torque value is set as one of the minimum torque limit and the maximum torque limit for a predetermined failure time period; and
if the desired engine output torque value is set as one of the minimum torque limit and the maximum torque limit for the predetermined failure time period, setting a failure mode output as true.

5. The method of claim 4 , further comprising setting the desired engine output torque value as the engine output torque requested if the failure mode output is true.

6. The method of claim 5 , further comprising:
determining an accelerator pedal position (PP);
determining a vehicle speed (V);
determining the axle torque requested (Ta_r) based on the accelerator pedal position (PP) and the vehicle speed (V);
determining a transmission ratio requested (Rat_r) based on the axle torque requested (Ta_r) and the vehicle speed (V); and
determining the engine output torque requested (Te_r) based on the axle torque requested (Ta_r), the transmission ratio requested (Rat_r), and the final drive ratio (FD).

7. The method of claim 6 , wherein the step of determining the initial selected engine output torque value using the model predictive control system comprises:
generating a plurality of sets of possible command values, the plurality of sets of possible command values including a plurality of commanded engine output torque values and a plurality of commanded transmission ratio values;
determining a cost for each set of possible command values of the plurality of sets of possible command values based on a first predetermined weighting value, a second predetermined weighting value, a predicted actual axle torque value of a plurality of predicted actual axle torque values, a predicted actual fuel consumption rate value of a plurality of predicted actual fuel consumption rate values, the axle torque requested, the engine output torque requested, the transmission ratio requested, and a fuel consumption rate requested;
determining which set of possible command values of the plurality of sets of possible command values has a lowest cost; and
selecting the set of possible command values that has the lowes

Assignees

• Gm Global Tech Operations Llc

Inventors

• Livshiz Michael
• Pattipati Bharath
• Worthing James L
• Whitney Christopher E

Classifications

• F02D41/20

  Output circuits, e.g. for controlling currents in command coils · CPC title

• B60W2540/10

  Accelerator pedal position · CPC title

• F02D2200/602

  Pedal position · CPC title

• F02D41/22 Primary

  Safety or indicating devices for abnormal conditions {(in air/fuel ratio feedback systems F02D41/1495, in electric control linkage F02D11/107, in purge control systems F02M25/0809)} · CPC title

• B60W2710/0666

  Engine torque · CPC title