Hydraulic load management for electric motor driven systems

Patent metadata

Field	Value
Publication number	US-12537472-B2
Application number	US-202418739054-A
Country	US
Kind code	B2
Filing date	Jun 10, 2024
Priority date	Jun 10, 2024
Publication date	Jan 27, 2026
Grant date	Jan 27, 2026

Abstract

Hydraulic load management for electric motor driven systems, such as hydraulic systems in a work machine, is disclosed. The hydraulic system may include an electric motor coupled to a hydraulic pump to provide hydraulic fluid to a hydraulic actuator, and a power bus may connect an electric power source to the electric motor. Hydraulic load management may include determining an actual electric power available at the electric power source, comparing the actual electric power to a threshold electric power for operating the electric motor at a full capacity, and setting a value for an available electric power and a current power curve for the electric motor corresponding to the available electric power. When hydraulic system input is detected, electric power is provided via the power bus, and the electric motor is operated at a motor speed based on the current power curve and a commanded speed from the hydraulic system input.

First claim

What is claimed is:

1 . A work machine comprising:
a hydraulic pump; an electric motor operatively coupled to the hydraulic pump; an electric power source; a power bus connecting the electric power source to the electric motor to transmit electric power from the electric power source to the electric motor; and a controller operatively connected to the electric motor and the electric power source, the controller configured to:
determine an actual electric power stored at the electric power source,
compare the actual electric power to a threshold electric power, and
set a value for an available electric power for the electric power source based on the comparison of the actual electric power to the threshold electric power,
set the value for the available electric power equal to a maximum electric power in response to determining that the actual electric power is not less than the threshold electric power, and
set a current power curve equal to a full power curve in response to determining that the available electric power is equal to the maximum electric power.

2 . The work machine of claim 1 , wherein the controller is configured to set a current power curve equal to an adjusted power curve in response to determining that the available electric power is less than a maximum electric power.

3 . The work machine of claim 1 , wherein the controller is configured to set the value for the available electric power equal to the actual electric power in response to determining that the actual electric power is less than the threshold electric power.

4 . The work machine of claim 3 , wherein the controller is configured to set a current power curve equal to an adjusted power curve in response to determining that the available electric power is equal to the actual electric power.

5 . The work machine of claim 1 , wherein the controller is configured to set a current power curve based on the value of the available electric power.

6 . The work machine of claim 5 , comprising a hydraulic actuator in fluid communication with the hydraulic pump, where the electric motor, the hydraulic pump and the hydraulic actuator are components of a hydraulic system of the work machine, and wherein the controller is configured to:
detect a hydraulic system input to actuate the hydraulic actuator, wherein the hydraulic system input comprises a commanded speed; cause the electric power source to transmit electric power to the electric motor via the power bus; determine a motor speed for the electric motor based on the current power curve and the commanded speed; and cause the electric motor to operate at the determined motor speed.

7 . The work machine of claim 6 , wherein the hydraulic system comprises a flow control valve fluidly connected between the hydraulic pump and the hydraulic actuator and operatively connected to the controller, wherein the hydraulic system input comprises a commanded direction, and wherein the controller is configured to cause the flow control valve to move to a position to cause hydraulic fluid from the hydraulic pump to move the hydraulic actuator in the commanded direction.

8 . A method for hydraulic load management of an electric motor driven hydraulic system of a work machine, wherein the hydraulic system includes both a hydraulic pump operatively coupled to the electric motor and a hydraulic actuator in fluid communication with the hydraulic pump, and wherein a power bus connects an electric power source of the work machine to the electric motor to transmit electric power from the electric power source to the electric motor, the method comprising:
determining an actual electric power stored at the electric power source; comparing the actual electric power to a threshold electric power for operating the electric motor at a full capacity; setting a value for an available electric power for the electric power source based on the comparison of the actual electric power to the threshold electric power; setting a current power curve based on the value of the available electric power; detecting a hydraulic system input to actuate the hydraulic actuator, wherein the hydraulic system input comprises a commanded speed; causing the electric power source to transmit electric power to the electric motor via the power bus; determining a motor speed for the electric motor based on the current power curve and the commanded speed; and causing the electric motor to operate at the determined motor speed.

9 . The method of claim 8 , comprising setting the value for the available electric power equal to a maximum electric power in response to determining that the actual electric power is not less than the threshold electric power.

10 . The method of claim 9 , comprising setting a current power curve equal to a full power curve in response to determining that the available electric power is equal to the maximum electric power.

11 . The method of claim 9 , comprising setting a current power curve equal to an adjusted power curve in response to determining that the available electric power is less than a maximum electric power.

12 . The method of claim 8 , comprising setting the value for the available electric power equal to the actual electric power in response to determining that the actual electric power is less than the threshold electric power.

13 . The method of claim 12 , comprising setting a current power curve equal to an adjusted power curve in response to determining that the available electric power is equal to the actual electric power.

14 . The method of claim 8 , wherein the hydraulic system includes a flow control valve fluidly connected between the hydraulic pump and the hydraulic actuator and operatively connected to the controller, and wherein the hydraulic system input comprises a commanded direction, the method comprising causing the flow control valve to move to a position to cause hydraulic fluid from the hydraulic pump to move the hydraulic actuator in the commanded direction.

15 . A controller for a work machine having a hydraulic system including a hydraulic pump, an electric motor operatively coupled to the hydraulic pump, and a hydraulic actuator fluidly connected to the hydraulic pump, the work machine further including an electric power source and a power bus connecting the electric power source to the electric motor to transmit electric power from the electric power source to the electric motor, where the controller is configured to:
determine an actual electric power stored at the electric power source; compare the actual electric power to a threshold electric power; set a value for an available electric power for the electric power source based on the comparison of the actual electric power to the threshold electric power; set a current power curve based on the value of the available electric power; detect a hydraulic system input to actuate the hydraulic actuator, wherein the hydraulic system input comprises a commanded speed; cause the electric power source to transmit electric power to the electric motor via the power bus; determine a motor speed for the electric motor based on the current power curve and the commanded speed; and cause the electric motor to operate at the determined motor speed.

16 . The controller of claim 15 , wherein the controller is configured to:
set the value for the available electric power equal to the actual electric power in response to determining that the actual electric power is less than the threshold electric power; and set the current power curve equal to an adjusted power curve in

Assignees

• Caterpillar Inc

Inventors

• Menold Rodney L
• Lane Cameron T
• Olson Andrew
• Schneider Karl P

Classifications

• F15B2211/76

  Control of force or torque of the output member · CPC title

• F15B2211/755

  Control of acceleration or deceleration of the output member · CPC title

• F15B2211/75

  Control of speed of the output member · CPC title

• H02P29/40

  Regulating or controlling the amount of current drawn or delivered by the motor for controlling the mechanical load · CPC title

• G01R31/382

  Arrangements for monitoring battery or accumulator variables, e.g. SoC · CPC title