Method and device for controlling a torque of an electric motor of an electro-hydraulic system

Patent metadata

Field	Value
Publication number	US-9976549-B2
Application number	US-201214126526-A
Country	US
Kind code	B2
Filing date	May 11, 2012
Priority date	Jun 16, 2011
Publication date	May 22, 2018
Grant date	May 22, 2018

Abstract

A method is used to control a torque of an electric motor of an electro-hydraulic system. The method includes selecting a value of a set point torque depending on a current pressure in a hydraulic circuit of the electro-hydraulic system. The method also includes determining a control signal for controlling the torque of the electric motor using a target torque and the set point torque.

First claim

The invention claimed is:

1. A method for controlling a torque of an electric motor of an electro-hydraulic system, the method comprising:
selecting, using a processor, a value of a target torque as a function of a current pressure and a predefined maximum pressure in a hydraulic circuit of the electro-hydraulic system, wherein a first value of the target torque is selected if the current pressure is lower than the predefined maximum pressure and a second value of the target torque is selected if the current pressure is higher than the predefined maximum pressure;
calculating the setpoint torque based on the current pressure in the hydraulic circuit of the electro-hydraulic system, and
determining, using the processor, an actuation signal to control the torque of the electric motor based on a setpoint torque and the target torque,
wherein the actuation signal is determined by a closed-loop controller, in which a closed-loop control curve is limited to the selected value of the target torque as a maximum value.

2. The method as claimed in claim 1 , wherein:
the value of the target torque is selected as a function of a predefined maximum pressure in the hydraulic circuit of the electro-hydraulic system and the current pressure in the hydraulic circuit of the electro-hydraulic system.

3. The method as claimed in claim 2 , wherein the second value of the target torque is determined from the predefined maximum pressure in the hydraulic circuit of the electro-hydraulic system and from a pump stroke of a pump driven by the electric motor of the electro-hydraulic system.

4. The method as claimed in claim 2 , further comprising:
comparing the predefined maximum pressure in the hydraulic circuit of the electro-hydraulic system and the current pressure in the hydraulic circuit of the electro-hydraulic system to generate a comparison value.

5. The method as claimed in claim 4 , further comprising:
making a threshold value decision based on the comparison value to generate a selection value for use in selecting the value of the target torque.

6. The method as claimed in claim 1 , wherein the value of the target torque is selected by a switch configured to be switched between two switched positions.

7. The method as claimed in claim 1 , further comprising:
performing at least one of the following:
(i) further calculating the setpoint torque based on at least one of: a setpoint rotational speed and a current rotational speed of the electric motor; and
(ii) converting the actuation signal into a motor current to drive the electric motor.

8. A device for controlling a torque of an electric motor of an electro-hydraulic system, the device comprising:
a first apparatus configured to select, using a processor, a value of a target torque as a function of a current pressure and a predefined maximum pressure in a hydraulic circuit of the electro-hydraulic system, wherein a first value of the target torque is selected if the current pressure is lower than the predefined maximum pressure and a second value of the target torque is selected if the current pressure is higher than the predefined maximum pressure; and
a second apparatus configured to determine an actuation signal, using the processor, to control the torque of the electric motor based on a setpoint torque and the target torque,
wherein the setpoint torque is calculated based on the current pressure, and
wherein the actuation signal is determined by a closed-loop controller, in which a closed-loop control curve is limited to the selected value of the target torque as a maximum value.

9. A method for controlling a torque of an electric motor of an electro-hydraulic system, the method comprising:
selecting, using a processor, a value of a target torque as a function of a current pressure and a predefined maximum pressure in a hydraulic circuit of the electro-hydraulic system, wherein a first value of the target torque is selected if the current pressure is lower than the predefined maximum pressure and a second value of the target torque is selected if the current pressure is higher than the predefined maximum pressure; and
determining, using the processor, an actuation signal to control the torque of the electric motor based on a setpoint torque and the target torque,
wherein the actuation signal is determined by a closed-loop controller, in which a closed-loop control curve is limited to the selected value of the target torque as a maximum value, and
wherein the closed-loop controller receives the setpoint torque and the selected value of the target torque as inputs.

10. The method as claimed in claim 9 , wherein:
the value of the target torque is selected as a function of a predefined maximum pressure in the hydraulic circuit of the electro-hydraulic system and the current pressure in the hydraulic circuit of the electro-hydraulic system.

11. The method as claimed in claim 10 , wherein the second value of the target torque is determined from the predefined maximum pressure in the hydraulic circuit of the electro-hydraulic system and from a pump stroke of a pump driven by the electric motor of the electro-hydraulic system.

12. The method as claimed in claim 10 , further comprising:
comparing the predefined maximum pressure in the hydraulic circuit of the electro-hydraulic system and the current pressure in the hydraulic circuit of the electro-hydraulic system to generate a comparison value.

13. The method as claimed in claim 12 , further comprising:
making a threshold value decision based on the comparison value to generate a selection value for use in selecting the value of the target torque.

14. The method as claimed in claim 9 , wherein the setpoint torque is calculated based on the current pressure in the hydraulic circuit of the electro-hydraulic system.

Assignees

• Mueller Karsten
• Schueren Volker
• Holl Dieter
• Spatz Bernd
• Herold Dirk Walter
• Haug Wolfgang
• Schemm Eberhard
• Bosch Gmbh Robert

Inventors

• Mueller Karsten
• Schueren Volker
• Holl Dieter
• Spatz Bernd
• Herold Dirk-Walter
• Haug Wolfgang
• Schemm Eberhard

Classifications

• H02P23/20

  Controlling the acceleration or deceleration · CPC title

• F15B2211/20515

  Electric motor · CPC title

• H02P6/08

  Arrangements for controlling the speed or torque of a single motor (H02P6/10, H02P6/28 take precedence) · CPC title

• F15B11/00 Primary

  Servomotor systems without provision for follow-up action; {Circuits therefor}(F15B3/00 takes precedence) · CPC title

• H02P25/024

  controlled by supply frequency · CPC title