DE102022203051B3 - Method for operating a variable speed pump - Google Patents

Abstract

The invention relates to a method for operating a variable-speed variable pump (120), in which a conveyor mechanism (122) which can be adjusted in a displacement volume per working cycle is driven by means of a variable-speed drive (121), comprising determining a load torque on the variable-speed variable pump (120), Depending on an operating state, specifying a target value (VPu, target) for a parameter determining the displacement volume per working cycle so that a drive torque of the variable-speed drive (121) is at most a peak drive torque (Man,max) of the drive (121) or corresponds to a continuous drive torque (Man,0) of the drive (121).

Description

The present invention relates to a method for operating a variable-speed variable pump, in which a conveyor mechanism that can be adjusted in a displacement volume per working cycle is driven by means of a variable-speed drive, and to an electro-hydraulic system.

Pumps on which the invention is based have a conveyor mechanism with a variable displacement volume per working cycle (so-called hydraulic displacement machine, e.g. axial piston machine), which is driven by a variable speed drive. When operating such pumps, the volume flow and/or the delivery pressure (i.e. pressure difference between inlet and outlet) are usually regulated by appropriately adjusting the displacement volume of the conveyor and the speed, i.e. such pumps have two degrees of freedom in the control.

From the EP 2 192 309 B1 For example, a method is known in which such a pump is operated by regulating a pressure or a quantity of pressure medium by controlling the volume setting of the pump. A speed deviation of the drive is taken into account.

The DE 10 2019 220 322 A1 relates to a method for operating a variable-speed variable pump, in which a conveyor mechanism that can be adjusted in a displacement volume per working cycle is driven by means of a variable-speed drive, with at least one variable being specified as part of a control system by specifying a speed setpoint for a speed of the drive and a setpoint for a displacer volume The parameter that determines the displacement per work cycle can be regulated to a setpoint, the speed setpoint being adjusted when the setpoint changes for the parameter that determines the displacement volume per work cycle by means of a precontrol.

The DE 10 2013 006 137 A1 relates to a method for regulating a pressure medium supply for at least one hydraulic actuator, which is supplied with a quantity of pressure medium by a variable-speed variable pump, in which a conveyor mechanism that can be adjusted in a displacement volume per working cycle is driven by a variable-speed drive, which is determined by a predetermined pressure and/or or volume flow profile is determined, wherein a speed setpoint and a setpoint for the parameter determining the displacement volume per work cycle are specified for a process sequence by solving a model-based optimization problem, which is specified by a target function for the process sequence.

The DE 10 2012 016 780 B4 relates to a method for operating a fluid pump, in which a conveyor mechanism that conveys a delivery volume per revolution is driven by an electric drive rotating at a speed, the conveyor mechanism being adjustable and the drive being designed to be variable in speed, an actual volume flow being set to a target volume flow and /or an actual delivery pressure is regulated to a target delivery pressure by specifying the speed of the drive as a manipulated variable with a fixed delivery volume, with a first, larger delivery volume being specified in full-load operation of the drive and a second, smaller one in partial-load operation of the drive Funding volume is specified.

The DE 10 2007 007 005 B4 relates to an electro-hydraulic control arrangement for controlling a hydraulic consumer, comprising a fluid pump whose displacement volume can be adjusted, a variable-speed electric drive coupled to the fluid pump for driving the fluid pump, and a pressure detection device for detecting a fluid pressure, a main control circuit being provided, the actuator of which is a speed actuator of the electric drive is and through which the fluid pressure and/or a downstream manipulated variable can be detected and regulated, and by means of a secondary control chain, a displacement volume actuator of the fluid pump can be controlled as a function of the detected fluid pressure, the secondary control chain acting on the displacement volume control element in accordance with a pressure setpoint supplied to it in the sense of a pressure control acts, the main control loop and the secondary control chain interacting in the sense of a replacing pressure/speed control of the consumer, and wherein in a pressure limiting operation the speed actuator is subjected to a predetermined reduced speed value and in a speed limiting operation the displacement volume actuator is set to its maximum value.

Based on this prior art, the invention is intended to decouple the drive torque of the drive from the load pressure of the driven conveyor by adjusting the displacement volume with the aim of optimal engine utilization.

According to the invention, a method and an electro-hydraulic system with the features of the independent patent claims are proposed. Advantageous refinements are the subject of the subclaims and the following description.

The invention is concerned with the operation of a variable-speed variable pump, such as in particular an axial piston pump with, for example, proportional adjustment, in which a conveyor mechanism that can be adjusted in a displacement volume per working cycle is driven by means of a variable-speed drive, such as an electric motor. To adjust the conveyor system, a so-called swivel plate can be provided in such a variable pump. Based on the load torque (in particular load pressure or differential pressure) on the pump as well as load characteristics of the drive motor (e.g. peak and continuous drive torque, max. overload time (=duration of the max. torque)), an appropriate setpoint for the displacement volume is generated to limit the drive torque. The invention thus creates a decoupling of the drive torque of the drive from the load pressure of the driven conveyor by adjusting the displacement volume with the aim of optimal engine utilization.

The current or drive torque of electric drives is usually thermally limited and depends on the duration of the load. However, hydrostatic motor-pump units often have to provide high load pressures over a relatively long period of time. A suitable adjustment of the displacement volume decouples pressure and drive torque. The invention prevents the drive from being overloaded. Within the scope of the invention, the displacement volume is specified so that it can always be applied by the electric drive. The invention is particularly applicable to pumps that are equipped with an adjusting device for specifically influencing their displacement volume based on control specifications. In particular, two operating states, static and dynamic, with different displacement volume specifications can be distinguished

According to the invention, the dependence on the operating state is taken into account by a dependence on a temporal change in the load torque on the variable-speed variable pump. This is an easy-to-implement option for characterizing the operating state.

According to the invention, the load torque and the peak drive torque of the drive are converted into a first manipulated variable in accordance with a first filter function with a time delay, in particular a PDT1 function, and the load torque and the continuous drive torque of the drive are converted into a first manipulated variable in accordance with a second filter function with a time delay , in particular a PDT1 function, a second manipulated variable is determined, the setpoint for the parameter determining the displacement volume per work cycle being specified based on the smaller of the first and second manipulated variables. This makes it possible to implement an operating state or load gradient dependency with a predeterminable time course, in particular in such a way that a timely change from the peak drive torque to the continuous drive torque takes place almost automatically before the motor is damaged. For this purpose, the first filter function preferably has a smaller time delay than the second filter function, preferably zero.

Preferably, in a dynamic operating state, the setpoint for the parameter determining the displacement volume per working cycle is specified such that the drive torque of the variable-speed drive is greater than the continuous drive torque and corresponds at most to the peak drive torque of the drive. In this way, the displacement volume is controlled or regulated in such a way that dynamic operating states are realized using the corner power or peak power of the electric drive.

In particular, in the dynamic operating state, the setpoint for the parameter determining the displacement volume per working cycle is specified such that the drive torque of the variable-speed drive corresponds at most to the peak drive torque of the drive for a permissible overload time. This means that peak performance can be maintained for as long as possible. It can additionally be provided to adapt the overload time using a determined (in particular measured (e.g. using a temperature sensor) or estimated) thermal drive utilization. This means that thermal damage to the drive can be avoided.

According to a further advantageous embodiment, in a static operating state, the setpoint for the parameter determining the displacement volume per working cycle is specified so that the drive torque of the variable-speed drive corresponds at most to the continuous drive torque of the drive. This ensures long-term or continuous operation; Stationary operating states are achieved using the nominal power of the electric drive.

A computing unit according to the invention, for example a control and/or regulating unit for a variable-speed variable pump with a variable-speed drive, is set up, in particular in terms of programming, to carry out a method according to the invention.

The invention furthermore relates to an electro-hydraulic drive system such as an electro-hydraulic axle comprising a variable-speed variable pump with a variable-speed drive and a computing unit according to the invention.

The implementation of a method according to the invention in the form of a computer program or computer program product with program code for carrying out all method steps is also advantageous because this causes particularly low costs, especially if an executing control device is used for additional tasks and is therefore present anyway. Suitable data carriers for providing the computer program are, in particular, magnetic, optical and electrical memories, such as hard drives, flash memories, EEPROMs, DVDs, etc. It is also possible to download a program via computer networks (Internet, intranet, etc.).

Further advantages and refinements of the invention result from the description and the accompanying drawing.

It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or alone, without departing from the scope of the present invention.

• 1 zeigt einen Schaltplan eines hydraulischen Systems, einen Antriebsmotor und eine Steuerung mit einer Einrichtung zur Einstellung der Drehzahl und ein Förderwerk mit einer Einrichtung zur Einstellung des Fördervolumens umfasst.
• 2 zeigt einen Signalflussplan eines Steuerschemas gemäß einer bevorzugten Ausführungsform der Erfindung.
• 3 zeigt beispielhafte Verläufe von Betriebsgrößen Druck, Antriebsmoment und Fördervolumen bei Anwendung eines Steuerschemas gemäß einer bevorzugten Ausführungsform der Erfindung.

The invention is shown schematically in the drawing using exemplary embodiments and is described in detail below with reference to the drawing.

• 1 shows a circuit diagram of a hydraulic system, a drive motor and a controller with a device for adjusting the speed and a conveyor with a device for adjusting the delivery volume.
• 2 shows a signal flow diagram of a control scheme according to a preferred embodiment of the invention.
• 3 shows exemplary curves of operating variables pressure, drive torque and delivery volume when using a control scheme according to a preferred embodiment of the invention.

In 1 an electro-hydraulic system 100, as may be the basis for the invention, is shown schematically. The electrohydraulic system 100 has an actuator designed as a hydraulic cylinder 110 with a piston 111 movable along an x-axis, which is actuated by a variable-speed variable pump 120. A hydraulic circuit 130 with, for example, oil as a medium or operating medium is arranged between the variable-speed variable pump 120 and the hydraulic cylinder 110.

The variable-speed variable pump 120 has a variable-speed drive designed as an electric motor 121 and a conveyor mechanism 122 and is designed, for example, as an axial piston pump in a swash plate design. By adjusting the angle of the swivel plate, i.e. the so-called swivel angle, the displacement volume of the conveyor can be changed per work cycle.

A control and/or regulating unit 140 is set up in terms of programming to carry out a preferred embodiment of a method according to the invention. In the example shown, it has several modules 141, 142, 143, here a control module 141, a speed control module 142 and a displacement volume control module 143. However, it should be made clear that the individual modules do not have to be installed in a unit and do not have to be implemented in a programmatic manner. In particular, a displacement volume control module 143 is often designed, for example, as an analog swivel angle controller.

A speed setpoint n _target and an actual speed value n _{ist are} supplied to the speed control module 142, from which a setpoint M _An for a drive torque is determined according to conventional regulation or control methods, for example using P and/or I and/or D transfer functions. The speed setpoint can come, for example, as a controlled specification from a user or as a control value from a higher-level pressure/force/position/speed controller for the hydraulic circuit or the output machine (e.g. cylinder or hydraulic motor).

The displacement volume control module 143 is supplied with a displacement volume setpoint V _PU,soll and an actual displacement volume value V _PU,ist , from which a manipulated variable for the conveyor system is determined using conventional methods.

In order to detect the pressure p ₁ , p ₂ in front of and behind the conveyor, two pressure sensors are provided in the present case.

The control module 141 receives the pressure values p ₁ , p ₂ and the (setpoint or actual) value M _An (in electrical machines, the time constant is significantly shorter compared to hydraulics, so that the setpoint and actual value are always viewed as the same when viewed in this way can be supplied for the drive torque, from which the setpoint for the displacement volume is determined. The drive torque can preferably be used here in order to take into account a portion of the friction in the total torque (which is present in addition to the external load, which is not negligible). As shown below, it is particularly taken into account in the form of additional load pressure.

Hydrostatic pumps provide a volume flow that is essentially proportional to the product of the speed and the pump size characterized by the displacement volume. The flow occurs from one work connection to the other depending on the direction of rotation. If different pressures p ₁ , p ₂ prevail at the working connections, a drive machine must provide a corresponding torque. The required torque is proportional to the product of the pressure difference and the pump size characterized by the displacement volume.

By means of an adjustment device for the displacement volume of the pump and a suitable operating strategy, the area of application of the motor-pump unit can be significantly expanded compared to a system with a constant pump, in that a high volume flow can be provided at low load pressures, while the drive motor cannot be used at high load pressures is overloaded. The present invention takes into account both the limitation of the continuous torque M ₀ and the peak torque M _max and thereby allows the maximum power of the drive motor/converter to be used for a limited time.

A pressure difference on the pump drive requires/generates a proportional torque M _L,P on the pump shaft according to: $$M_{L,p}=\frac{v_{Pu,Is\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="DE102022203051B3\_0014.png"\; state="\{\{state\}\}">t</figure-callout>}}}{2\cdot \pi }\cdot \left(p_1-p_2\right)$$

A speed approximately generates (minus leakage volume flows) a volume flow according to: $$Q_{Pu}=v_{Pu,Ist}\cdot n$$

wobei J_MoPu das Trägheitsmoment der Einheit ist, φ̈ die Drehwinkelbeschleunigung und M_R,ges das Gesamt-Reibmoment am Triebwerk.Overall, the torque balance on the engine of the motor-pump unit is: $${\text{J}}_{\text{MoPu}}\cdot \ddot{\phi }=M_{an}-M_{L,p}-M_{R,Ges}$$

where J _MoPu is the moment of inertia of the unit, φ̈ is the rotational angular acceleration and M _R,ges is the total frictional moment on the engine.

um die Kontrolle über die Antriebsdrehzahl zu behalten und ein ungewolltes Absinken derselben zu verhindern.When limiting the engine torque M _an to a limit value M _an,max, the following must therefore apply as a minimum requirement: $$M_{L,P}\le M_{an,max}$$

to maintain control over the drive speed and prevent it from dropping unintentionally.

This condition can be met by appropriately adjusting the displacement volume as follows: $$\frac{v_{Pu,SOll,Spit\mathrm{e.g}e}}{v_{Pu,max}}\le \frac{2\cdot \pi }{v_{Pu,max}}\cdot \frac{M_{an,max}}{\left|p_1-{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="DE102022203051B3\_0014.png"\; state="\{\{state\}\}">p</figure-callout>}}_2\right|+\left|{\widehat{p}}_{R,Ges,scH\ddot{a}t\mathrm{e.g}}\right|}$$

This already takes into account that devices for adjusting the displacement volume of a pump (such as a swivel angle adjustment) often expect a target signal that is related to the maximum displacement volume V _PU,max , and the actual displacement volume is also specified as a relational quantity. The real (total) friction on the engine can be taken into account as an estimated additional pressure difference P̂ _R,tot , which is derived from the drive torque and the delivery volume.

welche in Abhängigkeit vom jeweils anstehenden Lastdruck die Pumpenverstellung so ausführt, dass das Spitzenmoment des Motors nicht durch das Abtriebsmoment überschritten wird.An alternative form can be given for Equation 5a if the relative quantity α is introduced for the relative displacement volume. This results in the requirement: $${\alpha }_{SOll,Spit\mathrm{e.g}e}\le \frac{2\cdot \pi }{v_{Pu,max}}\cdot \frac{M_{an,max}}{\left|p_1-{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="DE102022203051B3\_0014.png"\; state="\{\{state\}\}">p</figure-callout>}}_2\right|+\left|{\widehat{p}}_{R,Ges,scH\ddot{a}t\mathrm{e.g}}\right|}$$

which, depending on the load pressure, adjusts the pump so that the peak torque of the motor is not exceeded by the output torque.

In an analogous manner, a setpoint for the (relative) displacement volume can be derived, which ensures compliance with the (lower) continuous torque M _an,0 of the drive motor: $${\alpha }_{SOll,Dauer}\le \frac{2\cdot \pi }{v_{Pu,max}}\cdot \frac{M_{an\mathrm{,0}}}{\left|p_1-{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="DE102022203051B3\_0014.png"\; state="\{\{state\}\}">p</figure-callout>}}_2\right|+\left|{\widehat{p}}_{R,Ges,scH\ddot{a}t\mathrm{e.g}}\right|}$$

Since M _an,0 ≤ M _an,max , a direct application of the rules for torque limitation as in Eq. 5b and 6 formulate the displacement volume must always be reduced to such an extent that the continuous torque is not exceeded. This would prevent the basic power of the drive motor from being used.

In order to (short-term) utilize the maximum power of the drive, the values from Eq. 5b and 6 resulting setpoint values for the swivel angle are advantageously filtered in order to influence them over time in such a way that the engine utilization is suitably optimized.

This advantageously results in the regulation for specifying a pump displacement volume for torque limitation in general form: $${\alpha }_{SOll,Dauer}\le \frac{2\cdot \pi }{{\text{v}}_{\text{Pu}\text{,Max}}}\cdot \text{MIN}\left[\begin{array}{c}ƒ\left(\frac{K_{r\mathrm{<figure-callout\; id="0"\; label="e\; d\; M"\; filenames="DE102022203051B3\_0013.png,DE102022203051B3\_0014.png"\; state="\{\{state\}\}">e</figure-callout>}dM0}\cdot M_{an\mathrm{,0}}}{\left|p_1-{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="DE102022203051B3\_0014.png"\; state="\{\{state\}\}">p</figure-callout>}}_2\right|+\left|p_{R,Ges,scH\ddot{a}t\mathrm{e.g}}\right|},\omega \right)\\ G\left(\frac{K_{redMmax}\cdot M_{an,max}}{\left|p_1-{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="DE102022203051B3\_0014.png"\; state="\{\{state\}\}">p</figure-callout>}}_2\right|+\left|{\widehat{p}}_{R,Ges,scH\ddot{a}t\mathrm{e.g}}\right|},\omega \right)\end{array}\right]$$

The correction values designated K _redM* take into account the fact that the torque limit values in a real drive system can deviate from the nominal values.

Technically advantageously, a filter or a filter function g(M _am,max , Δp, ω) can be designed in such a way that a dynamic delay of the adjustment device is compensated for in order to implement the limitation to the maximum torque without delay and thus to ensure functionality even in the event of dynamic load changes to guarantee. A PDT1 transfer function can advantageously be used as a filter function.

Furthermore, a filter or a filter function f(M _an,0, Δρ, ω) can be technically advantageously designed in such a way that as the load increases, the reduction in the displacement volume is delayed in a defined time in order to be able to optimally use the peak power of the drive. However, when the load drops, the displacement volume is adjusted back with as little delay as possible in order to be able to achieve a high volume flow for load reduction. A PDT1 transfer function can advantageously be used as a filter function.

In order to maintain an application-related volume flow in particular, a change in the displacement volume _is expediently taken into account in the speed specification n target. The product of speed and displacement is proportional to the requested or necessary volume flow.

The signal flow plan of a preferred implementation of such a filter concept is in 2 shown and labeled 200 in total.

On the input side (left), the difference between the pressure values p ₁ and p ₂ is first formed and fed to an amount formation 201. Likewise, the amount 202 of the estimated additional pressure difference P = P̂ _{R,tot,estimated} is added to form the total relevant differential pressure Δp. This is offset in a division element 203 or 204 with the maximum drive torque M _an,max or the continuous drive torque M _an,0 and then offset in a link 205, 206 with the correction values mentioned and the maximum volume in order to obtain the relational volume control values.

$$ƒ:G\left(s\right)=\frac{T_{N,Dauer}\cdot s+1}{T_{P,Dauer}\cdot s+1}$$

These are fed to a filter function 207, 208, which represents a PDT ₁ transmission behavior in particular according to the following equation. The corresponding transfer functions are: $$G:G\left(s\right)=\frac{T_{N,Spit\mathrm{e.g}e}\cdot s+1}{T_{P,Spit\mathrm{e.g}e}\cdot s+1}$$

$$ƒ:G\left(s\right)=\frac{T_{N,Dauer}\cdot s+1}{T_{P,Dauer}\cdot s+1}$$

The resulting output values or manipulated variables α _{S, peak} and α _{S, duration} are fed to a minimum value element 209, which selects the respective smaller displacement volume as the actual manipulated variable α _target .

Verzögerungszeit: $T_{P,Dauer}=T_{Maxmoment}\cdot \left(1-\frac{1}{e}\right)$

An advantageous parameterization of the filter parameters is as follows: Lead time: T _N,peak = T _digit Delay Time: T _P,peak = 0 Lead time: $T_{N,Dauer}=T_{MaxmOment}\cdot \left(1-\frac{1}{e}\right)\cdot SGN\left({\dot{\propto }}_{S,Dauer,stat}\right)$

Delay Time: $T_{P,Dauer}=T_{MaxmOment}\cdot \left(1-\frac{1}{e}\right)$

Therein T _Stell corresponds to the parameter of a simplified model of the dynamics of the pump adjustment. T _{maximum torque} is the time for which the drive should be able to generate its peak torque. This is to be seen as an essential operating parameter of the adjustment strategy presented and must be smaller than the actual time after which the drive reaches its thermal overload. Furthermore, e is Euler's number.

To further improve the method, the estimate of the frictional torque can be adapted to the current operating conditions using a suitable estimator. A possible device would be an integral controller for the static engine torque or other estimating devices that are common in control technology, such as observers.

To further improve the method, the effective limit value for the continuous torque can be adapted to the existing operating conditions using the measured or estimated thermal drive utilization by adapting the correction factor K _redM0 . In a similar way, the permitted overload time T _Maxmoment , which is used in the signal filter, can be adapted to the existing operating conditions.

An exemplary course of operating variables when using a preferred embodiment of the invention is shown in 3 shown.

There, in the upper diagram, the pressure difference 301 on the conveyor and a drive torque 302 on the electric drive are plotted in exemplary units against the time t, also in exemplary units. In particular, starting from a time of 0 to a time of approximately 0.85, the pressure difference and thus the load is increased from 0 to approximately 100%.

In the diagram below, the displacement volume in percent is plotted against time t for different control variables. These include α _{should, duration, stat} 303, α _{should, peak, dyn} 304, α _{should, duration, dyn} 305, α _{should, peak, stat} 306. Furthermore, the actual swivel angle α Act 307 resulting from an exemplary actuating dynamic _is plotted .

The two conditions for the limitation to the maximum torque or the continuous torque result in the two static swivel angle setpoints α _{target, duration, stat} 303 and α _{target, peak, stat} 306 with the increasing pressure difference shown. After filtering through the corresponding signal filters 207 and 208, they are The setpoint values α _{target, duration, dyn} 305 and α _{target, peak, dyn} 304 are valid for the swivel angle control. The minimum value element 209 supplies the control device 143 for the swivel angle with the smaller value of α _{target, duration, dyn} 305 and α _{target, peak, dyn} 304 at the respective time as the valid target value. With a usual configuration of the control device 143 for the swivel angle as a proportional controller, there is a time delay of the actual swivel angle value compared to the setpoint, which is shown, for example, by the actual value curve α _Act 307.

With an advantageous parameterization of the filter times, the filter 207 for the peak torque limitation compensates the actuating dynamics of the control device 143 so that the actual value _αAct 307 exactly follows the static setpoint α _{target, peak, stat} 306, so that the peak torque is not exceeded despite the limited actuating dynamics of the swivel angle controller becomes.

Furthermore, the filter 208 for the permanent torque limitation is designed with a direction-dependent signal component, so that when the load torque increases, the effective setpoint α _{target, duration, dyn} 305 lags behind the filter input α target _{, duration, stat} 303 by the desired time-limited maximum load of the electric drive machine to be able to use it, while when the load torque is reduced, the effective setpoint α _{target, duration, dyn} 305 leads the filter input α _{target, duration, stat} 303. With an advantageous parameterization of the filter times, as shown above, the filter 208 for the continuous torque limitation compensates for the control dynamics of the control device 143 so that the actual value α _Act 307 exactly follows the static setpoint α _{target, duration, stat} 303, so that when the load decreases The full performance of the motor-pump unit is available without delay and in compliance with the torque limitation despite the limited control dynamics of the swivel angle controller.

Claims (16)

Method for operating a variable-speed variable pump (120), in which a conveyor mechanism (122) which can be adjusted in a displacement volume per working cycle by means of a variable-speed drive (121) which has a peak drive torque (M _An,max ) and a continuous drive torque (M _{An ,0} ), is driven, comprising: determining a load torque (Δp) on the variable-speed variable pump (120), depending on an operating state, specifying a setpoint (V _Pu,Soll ) for a parameter determining the displacement volume per working cycle to an adjusting device (143) of the conveyor so that a drive torque of the variable-speed drive (121) is either more than the continuous drive torque (M _an,0 ) and at most the peak drive torque (M _an,max ) of the drive (121), or at most the Continuous drive torque (M _an,0 ) of the drive (121), the dependence on the operating state being taken into account by a dependence on a temporal change in the load torque (Δp) on the variable-speed variable pump (120), whereby from the load torque (Δp ) and the peak drive torque (M _An,max ) of the drive (121) in accordance with a first filter function (207) with a time delay (TP _,peak ) a first manipulated variable (α _S,peak ) and from the load torque (Δp) and the continuous drive torque (M _An,0 ) of the drive (121) in accordance with a second filter function (208) with a time delay ( _TP,Duration ) a second manipulated variable (α _S,Duration ) is determined, the setpoint (V _{Pu, target} ) for the parameter determining the displacement volume per working cycle is specified based on the smaller of the first and second manipulated variables. Procedure according to Claim 1 , wherein the first filter function (207) has a smaller time delay ( _{TP, peak} ) than the second filter function (208), preferably zero. Procedure according to Claim 1 or 2 , wherein the first filter function (207) and/or the second filter function (208) is a PDT1 transfer function with a lead time (T _{N, peak} , T _{N, duration} ) and a delay time ( _{TP, peak} , T _{P, duration} ) are, whereby the lead time (T _{N, peak} , T _{N, duration} ) is specified in particular as a function of an actuating dynamic of the adjusting device (143) of the conveyor system. Method according to one of the preceding claims, wherein in a dynamic operating state the setpoint (V _Pu,Soll ) for the parameter determining the displacement volume per working cycle is specified such that the drive torque of the variable-speed drive (121) is more than the continuous drive torque (M _{An .0} ) of the drive (121) and at most corresponds to the peak drive torque of the drive (121). Procedure according to Claim 4 , whereby in the dynamic operating state the setpoint (V _Pu,Soll ) for the parameter determining the displacement volume per working cycle is specified in such a way that the drive torque of the variable-speed drive (121) is more than the continuous drive torque (M _{An, 0} ) of the drive (121) and at most corresponds to the peak drive torque of the drive (121). Procedure according to Claim 5 , wherein the overload time is adjusted using a determined thermal drive utilization, and preferably with reference back to Claim 3 , whereby the time delay ( _{TP, duration} ) of the second filter function (208) is specified depending on the overload time. Method according to one of the preceding claims, wherein in a static operating state the setpoint (V _Pu,Soll ) for the parameter determining the displacement volume per working cycle is specified such that the drive torque of the variable-speed drive (121) is at most the continuous drive torque of the drive (121 ) corresponds. Method according to one of the preceding claims, wherein determining the load torque on the variable-speed variable pump (120) comprises determining a pressure difference (Δp) between an inlet and an outlet of the conveyor (122). Method according to one of the preceding claims, wherein determining the load torque on the variable-speed variable pump (120) comprises determining a friction as an additional pressure difference (p). Method according to one of the preceding claims, wherein the peak drive torque (M _an,max ) of the drive (121) and / or the continuous drive torque (M _an,0 ) of the drive (121) as a product with a correction factor (K _redMmax , K _redM0 ) are taken into account. Procedure according to Claim 10 , whereby the correction factor (K _redMmax , K _redM0 ) is adjusted using a determined thermal drive utilization. Method according to one of the preceding claims, additionally comprising: specifying a target value (n _Soll ) for the speed of the variable-speed drive (121) depending on the target value (V _Pu,Soll ) or an actual value (V _Pu,Sst ) for the displacement volume determining parameter for each work cycle. Computing unit (140), which is set up to carry out a method according to one of the preceding claims. Electro-hydraulic system (100) comprising a variable-speed variable pump (120) with a variable-speed drive (121) and a computing unit (140). Claim 13 . Computer program that the computing unit (140) of the electro-hydraulic system (100) follows Claim 14 initiated a procedure according to one of the Claims 1 until 13 to be carried out when it is executed on the computing unit (140). Machine-readable storage medium with a computer program stored on it Claim 15 .

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