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DE-102024210749-A1 - Method for controlling an electric drive of a hydraulic pump in a hydraulic system

DE102024210749A1DE 102024210749 A1DE102024210749 A1DE 102024210749A1DE-102024210749-A1

Abstract

The invention relates to a method for controlling an electric drive (4, 6) of a hydraulic pump (2) in a hydraulic system comprising at least one hydraulic consumer (10), wherein the electric drive is controlled by a manipulated variable and wherein the at least one hydraulic consumer (10) is supplied with hydraulic fluid by the pump (2) based on consumer requirements, comprising: determining (110) a first value (42) for the manipulated variable by means of a pressure regulator (40) that regulates a pump pressure (38) of the pump to a target pump pressure (36) determined by the consumer requirements; determining (120) a second value (52) for the manipulated variable by means of a speed controller (50) that regulates a speed (46) of the pump to a target pump speed (44) determined by the consumer requirements; determining (130) a third value (56) for the manipulated variable from the first and the second value; a determination (140) of one or more limit values (82, 102) for the manipulated variable by means of respective controllers (96, 98) by which one or more limit values (80, 90) of the hydraulic system are controlled to one or more limit setpoint values (78, 88); a determination (150) of a control value (60) for the manipulated variable from the third value and the one or more limit values; and a control (160) of the electric drive with the control value (60).

Inventors

  • Steffen Rose
  • Fabian Wiedmer
  • Daniel Neyer
  • Dominik Thomas Hoffmann

Assignees

  • Robert Bosch Gesellschaft mit beschränkter Haftung

Dates

Publication Date
20260513
Application Date
20241108

Claims (14)

  1. Method for controlling an electric drive (4, 6) of a hydraulic pump (2) in a hydraulic system having at least one hydraulic consumer (10), wherein the electric drive is controlled by a manipulated variable and wherein the at least one hydraulic consumer (10) is supplied with hydraulic fluid by the pump (2) based on consumer demands, comprising: - Determining (110) a first value (42) for the manipulated variable by means of a pressure regulator (40) which reduces a pump pressure (38) of the pump to a setpoint pump pressure (36) determined by the consumers requirements are determined; - Determining (120) a second value (52) for the manipulated variable by means of a speed controller (50)), which regulates a speed (46) of the pump to a target pump speed (44) which is determined by the consumer requirements; - Determining (130) a third value (56) for the manipulated variable from the first and the second value; - Determining (140) one or more limit values (82, 102) for the manipulated variable by means of respective controllers (96, 98), by which one or more limit values (80, 90) of the hydraulic system are regulated to one or more limit setpoints (78, 88); - Determining (150) a control value (60) for the manipulated variable from the third value and the one or more limit values; and - Controlling (160) the electric drive with the control value (60).
  2. Procedure according to Claim 1 , wherein when determining the third value (56): - the third value (56) is determined as the minimum of the first value (42) and the second value (52), or - the third value (56) is determined by means of a function which, in particular, after a period of time following a change in the minimum of the first value (42) and the second value (52), selects the minimum of the first and the second value as the third value, or - the third value (56) is determined as an average of the first and the second value (52).
  3. A method according to one of the preceding claims, wherein when determining the setpoint (60), the setpoint (60) is determined as greater than or equal to the at least one first limit value of one or more limit values (82, 102) and/or as less than or equal to the at least one second limit value of one or more limit values (82, 102) for at least one second limit value; wherein, in particular, the setpoint (60) is determined as the maximum of the third value (56) and the at least one first limit value and/or as the minimum of the third value (56) and the at least one second limit value.
  4. Method according to one of the preceding claims, wherein when determining the setpoint (60) the setpoint (60) is determined as the maximum of the third value (56) and the one or more restriction values (82, 102).
  5. A method according to any of the preceding claims, wherein the one or more limiting parameters include the pump pressure, wherein the corresponding limiting setpoint is a minimum pump pressure; and/or wherein the one or more limiting parameters include the speed of the pump, wherein the corresponding limiting setpoint is a minimum speed.
  6. Method according to one of the preceding claims, wherein the manipulated variable is a torque or a speed of the electric drive (4, 6).
  7. A method according to any one of the preceding claims, whereby the pressure regulator (40) has an integral component, wherein a difference (68) between the first value (42) and the third value (56) is determined and the difference is used in an anti-windup function of the integral component of the pressure regulator (40); and/or whereby the speed controller (50) has an integral component, wherein a difference (72) between the second value (52) and the third value (56) is determined and the difference is used in an anti-windup function of the integral component of the speed controller (50).
  8. A method according to any of the preceding claims, whereby the pressure regulator (40) has an integral component, wherein a difference (64) between the third value (56) and the control value (60) is determined and the difference is used in an anti-windup function of the integral component of the pressure regulator; and/or whereby the speed controller (50) has an integral component, wherein a difference (100) between the third value (56) and the control value (60) is determined and the difference is used in an anti-windup function of the integral component of the speed controller.
  9. Procedure according to one of the Claims 1 until 6 , wherein the pressure regulator (40) has an integral component, wherein a first difference (68) between the first value (42) and the third value (56) is determined, a second difference (64) between the third value (56) and the control value (60) is determined, and the minimum of the first and second differences is used in an anti-windup function of the integral component of the pressure regulator (40); and/or wherein the speed controller (50) has an integral component, wherein a third difference (72) between the second value (52) and the third value (56) is determined, a fourth difference (100) between the third value (56) and the control value (60) is determined, and the minimum of the third and fourth differences is used in an anti-windup function the integral part of the speed controller (50) is used.
  10. Method according to one of the preceding claims, wherein for each of the one or more restriction values (82, 102) the respective controller (96, 98) has an integral component, wherein a difference (86, 94) between the respective restriction value (82, 102) and the actuated value (60) is determined and the difference is used in an anti-windup function of the integral component of the respective controller.
  11. Computing unit comprising a processor configured to perform the method according to any of the preceding claims.
  12. Hydraulic system comprising a hydraulic pump (2) with an electric drive (4, 6) and a hydraulic consumer (10), wherein the electric drive is controlled by a manipulated variable and wherein the at least one hydraulic consumer (10) is supplied with hydraulic fluid by the pump (2) based on consumer requirements, and a computing unit according to Claim 11 .
  13. A computer program comprising commands that are executed by the computing unit of the hydraulic system during the execution of the program. Claim 12 this causes the procedure to be continued according to Claim 1 until 10 to execute.
  14. Computer-readable data carrier on which the computer program is located Claim 13 is stored.

Description

The present invention relates to a method for controlling an electric drive of a hydraulic pump in a hydraulic system, as well as a computing unit and a computer program for its implementation and a hydraulic system. Background of the invention Machines, especially mobile construction equipment (e.g., excavators), can have a working hydraulic system to move components (e.g., boom sections) using hydraulic actuators (e.g., hydraulic cylinders and/or hydraulic motors). One way to make the use of the working hydraulic system more efficient is to provide a demand-based flow rate, for example, by using a variable displacement pump, which is typically relatively expensive compared to fixed displacement pumps. In hydraulic systems with a fixed displacement pump driven by an electric motor, the speed of the pump or the motor can be varied to adjust the flow rate. Various control concepts are possible to supply hydraulic systems used in mobile applications to control working equipment with the desired flow rate. For example, flow-matching systems like EFM (Electro-hydraulic Flow Matching) use flow rate or speed control. In systems whose control is based on a pressure or pressure difference, such as LS and LUDV systems (LS: Load-Sensing, LUDV: Load-pressure-independent flow distribution), pressure control is used. Disclosure of the invention According to the invention, a method for controlling an electric drive of a hydraulic pump in a hydraulic system, as well as a computing unit and a computer program for its execution, and a hydraulic system with the features of the independent claims are proposed. Advantageous embodiments are the subject of the dependent claims and the following description. Within the scope of the invention, in a hydraulic system with a pump driven by an electric actuator controlled by a manipulated variable, a first value and a second value for the manipulated variable are determined by a pressure regulator and a speed controller. Furthermore, a third value is determined from the first and second values. Several limit values for the manipulated variable are determined by means of respective controllers, wherein the controllers regulate one or more limit values of the hydraulic system to one or more limit setpoints. A control value for the manipulated variable is determined from the third value and the one or more limit values. This enables a sequential control system between the pressure and speed controllers, which additionally takes into account limits imposed by individual components, dependent on the operating state or mode, or resulting from the system design. By taking into account the limitations through respective controllers, which are different from the speed controller and pressure controller, instead of taking them into account directly in the speed controller or the pressure controller, it can be prevented that a limitation is not taken into account when the other of the two controllers (speed controller, pressure controller), in which the limitation is not taken into account, is active. The control variable is, in particular, a torque or a speed of the electric drive. In one embodiment, the third value is determined as the minimum of the first and second values, or the third value is determined by a function that, in particular, selects the minimum of the first and second values as the third value after a time interval has elapsed since a change in the minimum of the first and second values has occurred, or the third value is determined as the average of the first and second values. Selecting the minimum ensures energy-efficient operation. When using the function, the time interval can, for example, be fixed or determined by limiting the magnitude of the rate of change of the third value. This, as well as averaging, ensures smooth transitions. On average, the first and second values can be weighted differently and variably. For example, a time-dependent weighting can be applied, whereby, for instance, from a point in time when the first or second value falls below the other, the smaller of the two values is weighted more heavily over time, specifically until its weight is 1 and the weight of the other is 0, or until a change in circumstances occurs that determines which value is smaller. A weighting that depends on the difference between the larger of the two values (i.e., the first and second value) is also possible; for example, the smaller of the two Values are weighted more heavily the further apart they are. According to one embodiment, the manipulated value is determined as greater than or equal to at least one first constraint value of the one or more constraint values, and/or as less than or equal to at least one second constraint value of the one or more constraint values. In particular, the manipulated value is determined as the maximum of the third value and the at least one first constraint value, and/or as the minimum of the third value and the at least one second con