Control system for DC bus regulation

Patent metadata

Field	Value
Publication number	US-11038442-B2
Application number	US-201916675721-A
Country	US
Kind code	B2
Filing date	Nov 6, 2019
Priority date	Nov 6, 2019
Publication date	Jun 15, 2021
Grant date	Jun 15, 2021

Abstract

A device that includes a memory and a processor is disclosed. The processor may be configured to receive a control signal for operating a plurality of traction motors of a work machine. The control signal may include information relating to an actual speed of the work machine, a target speed of the work machine, and a generator speed of a generator operatively coupled to the traction motors. The processor may be configured to determine respective torque commands associated with the traction motors based on the actual speed and the target speed, and determine a generator power limit based on the generator speed. The processor may be configured to determine a threshold based on the respective torque commands and the generator power limit, adjust the respective torque commands based on the threshold, and cause the traction motors to be operated based on the adjusted respective torque commands.

First claim

What is claimed is:

1. A method, comprising:
receiving a control signal for operating a plurality of traction motors of a work machine,
the plurality of traction motors being in electrical communication with a generator of the work machine, and
the control signal including information relating to an actual speed of the work machine, a target speed of the work machine, and a generator speed of the generator;

determining respective torque commands associated with the plurality of traction motors based on the actual speed and the target speed;
determining a total power demand associated with the plurality of traction motors based on the respective torque commands and respective traction motor speeds;
determining a generator power limit based on the generator speed;
determining a limit ratio based on the total power demand and the generator power limit;
adjusting the respective torque commands of the plurality of traction motors based on the limit ratio; and
causing an action to be performed based on the adjusted respective torque commands.

2. The method of claim 1 , wherein determining the respective torque commands comprises:
determining a steering command based on the control signal;
determining respective speed commands associated with the plurality of traction motors based on one or more of the actual speed, the target speed, or the steering command,
the respective speed commands being proportioned between the plurality of traction motors to cause steering of the work machine according to the steering command; and

determining the respective torque commands based on the respective speed commands.

3. The method of claim 1 , wherein determining the total power demand comprises:
determining respective power demands of the plurality of traction motors based on the respective torque commands; and
determining the total power demand based on the respective power demands.

4. The method of claim 1 , wherein determining the generator power limit comprises:
determining the generator power limit based on the generator speed and a generator torque limit.

5. The method of claim 1 , wherein the limit ratio is configured to saturate to a value of 1.

6. The method of claim 1 , wherein adjusting the respective torque commands comprises:
derating the respective torque commands by the limit ratio such that the total power demand approximates the generator power limit.

7. The method of claim 1 , wherein causing the action to be performed comprises:
enabling the plurality of traction motors to be controlled according to the adjusted respective torque commands.

8. A device, comprising:
one or more memories; and
one or more processors, communicatively coupled to the one or more memories, configured to:
receive a control signal for operating a plurality of traction motors of a work machine,
the control signal including information relating to an actual speed of the work machine, a target speed of the work machine, and a generator speed of a generator operatively coupled to the plurality of traction motors;

determine respective torque commands associated with the plurality of traction motors based on the actual speed and the target speed;
determine a generator power limit based on the generator speed;
determine a threshold based on the respective torque commands and the generator power limit;
adjust the respective torque commands based on the threshold; and
cause the plurality of traction motors to be operated based on the adjusted respective torque commands.

9. The device of claim 8 , wherein the one or more processors, when determining the respective torque commands, are configured to:
determine a steering command based on the control signal;
determine respective speed commands associated with the plurality of traction motors based on one or more of the actual speed, the target speed, or the steering command,
the respective speed commands being proportioned between the plurality of traction motors to cause steering of the work machine according to the steering command; and

determine the respective torque commands based on the respective speed commands.

10. The device of claim 8 , wherein the one or more processors, when determining the generator power limit, are configured to:
determine the generator power limit based on the generator speed and a generator torque limit.

11. The device of claim 8 , wherein the one or more processors, when determining the threshold, are configured to:
determine respective power demands of the plurality of traction motors based on the respective torque commands and respective speeds of the plurality of traction motors;
determine a total power demand based on an aggregation of the respective power demands; and
determine the threshold as a limit ratio,
the limit ratio being determined based on a ratio between the generator power limit and the total power demand.

12. The device of claim 8 , wherein the one or more processors, when adjusting the respective torque commands, are configured to:
derate the respective torque commands by a limit ratio,
the limit ratio being determined based on a ratio between the generator power limit and a total power demand of the plurality of traction motors.

13. The device of claim 8 , wherein the one or more processors are further configured to:
determine respective power demands of the plurality of traction motors based on the respective torque commands and respective speeds of the plurality of traction motors;
determine a total power demand based on an aggregation of the respective power demands;
compare the total power demand with the generator power limit; and
derate the respective torque commands by a limit ratio based on determining that the total power demand exceeds the generator power limit,
the limit ratio being determined based on a ratio between the generator power limit and the total power demand.

14. A work machine, comprising:
a first traction motor;
a second traction motor;
a generator operatively coupled to the first traction motor and the second traction motor; and
a controller configured to:
receive information relating to an actual speed of the work machine, a target speed of the work machine, and a generator speed of the generator,
determine, based on the actual speed and the target speed, a first torque command associated with the first traction motor and a second torque command associated with the second traction motor,
determine a total power demand based on the first torque command and the second torque command,
determine a generator power limit based on the generator speed,
determine a threshold based on the total power demand and the generator power limit,
adjust the first torque command and the second torque command based on the threshold to obtain an adjusted first torque command and an adjusted second torque command, and
cause an action to be performed based on the adjusted first torque command and the adjusted second torque command.

15. The work machine of claim 14 , wherein the controller, when receiving the information, is configured to:
receive the target speed from a user interface of the work machine, and
receive one or more of the actual speed or the generator speed from a set of sensors associated with the work machine.

16. The work machine of claim 14 , wherein the controller, when determining the first torque command and the second torque command, is configured to:
receive a steering command from a user interface of the work machine,
determine, based on one or more of the actual speed, the target speed, or the steerin

Assignees

• Caterpillar Inc

Inventors

• Kuras Brian
• Sharma Ankit
• Cowper Lance

Classifications

• B60W2300/44

  Tracked vehicles · CPC title

• B60W2300/17

  Construction vehicles, e.g. graders, excavators · CPC title

• B60W20/50

  Control strategies for responding to system failures, e.g. for fault diagnosis, failsafe operation or limp mode · CPC title

• B60K6/46

  Series type · CPC title

• H02P5/50 Primary

  by comparing electrical values representing the speeds · CPC title