EP2640973B1 - Method and control device for the rotational-speed-variable control of an expeller pump unit and expeller pump arrangement - Google Patents

Description

The invention relates to a method for variable-speed control of a positive displacement pump unit for conveying a fluid consisting of a positive displacement pump and a drive, wherein the drive consists of a provided with stator and rotor electric drive motor and a frequency converter, by means of a control device, wherein a controlled variable of the positive displacement pump the control device is controlled to a desired value, wherein by the control device at least one state provided by the drive state value of the drive is detected and from the control device, the controlled variable of the positive displacement pump is determined to control the positive displacement pump unit without the use of sensors to the desired value, and a suitable control device for carrying out the method and a corresponding displacement pump arrangement.

Displacement pumps are often used to convey fluids, ie liquids or gases, at medium to high pressures and small flow rates. The drive is usually an electric asynchronous motor with upstream frequency converter used in combination with a designed as a process controller control device for variable-speed operation of the induction motor. Due to the variable-speed operation can be achieved with a measurement of the final pressure as a controlled variable of the positive displacement pump, a regulation of the pressure with changing flow rate. The control device is usually in addition to the actual regulation in addition intended for control, monitoring and / or diagnostic tasks. Frequency converter and control device are usually designed separately. To avoid overpressures and for rapid pressure reduction separate pressure relief valves are used in a conventional positive displacement pump assembly pressure side. A start of the drive against a closed slide is not possible without control intervention of the pressure relief valve drive. Providing a required pressure at a flow rate equal to zero, the so-called zero flow rate is not possible in a conventional arrangement. This increases the time required to adjust the pressure when the slider is opened.

Furthermore, a method for sensorless control of rotor angle position or rotor position, hereinafter referred to simply as position, and speed of a synchronous reluctance known. The state values are speed and position of the synchronous reluctance motor and, via the torque-forming current component, its torque.

The DE 20 2005 001 746 U1 discloses an apparatus for controlling a fluid flow machine having a processor device with a memory module in which a mathematical model is stored.

The EP 0 156 399 A2 discloses a control system for a multiple displacement pump assembly.

The WO 03/031918 A1 discloses an apparatus and method for monitoring flow rates.

The EP 2 196 678 A1 discloses a method and apparatus for cavitation detection of a pump driven by a frequency converter.

The GB 2 352 533 A discloses a method for controlling the delivery size of a pump by measuring the input power of the motor as actual value for the delivery quantity.

The US 2003/0127289 A1 discloses a method for sensorless drive control of an electric vehicle.

The object of the invention is to provide a method for variable-speed control of a positive displacement pump unit, which increases the dynamics of the control and requires fewer individual components of the arrangement, and to provide a suitable control device for carrying out the method and a corresponding positive displacement pump arrangement.

This object is achieved according to the invention with a method in which torque and position of the drive motor are detected as state values of the drive. As controlled variables of the positive displacement pump, in particular the final pressure and the delivered fluid volume are provided. According to the invention, torque and position of the drive motor are detected as state values of the drive. By means of the method according to the invention, a regulation to a nominal value is created which entirely manages without sensory detection of the controlled variable and is based purely on the state values supplied by the drive.

The control device is also provided for control, monitoring and / or diagnostic tasks. In this application, without limitation of the overall functionality of the device simplifying the term control device is used. Frequency converter and control device according to the invention can also be designed integrated.

An embodiment of the method provides that the final pressure is determined by the control device as a controlled variable of the positive displacement pump in order to regulate the positive displacement pump unit without the use of sensors to the final pressure setpoint. As a result, a control to a final pressure setpoint is created, which manages without a sensory detection of the final pressure.

According to one embodiment of the invention, it is provided that the final pressure of the positive displacement pump is regulated by means of a stored in the control device engine torque-end pressure dependence of the positive displacement pump unit. The control device and / or the integrated with the control device running drive is parameterized or adapted by such a pressure model to the respective positive displacement pump. By controlling the motor torque, the final pressure of the pump is controlled. The engine torque-final pressure dependency stored in the control device is provided in the form of a characteristic curve, a value table, or the like. A formulaic relationship is also provided and can be stored in a storage device provided in the control device. As appropriate and sufficient in a first approximation, a simple linear relationship between engine torque and discharge pressure the actual value of the engine torque manure and the constant k ₁ has been found that _is with the actual value of the final pressure p, is given by the following equation: $${\mathrm{p}}_{\mathrm{is}}={\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">k</figure-callout>}}_1\cdot {\mathrm{M}}_{\mathrm{is}}$$

For a precise determination of the final pressure, it has been proven that the speed of the motor can additionally be detected by the control device. By such a dynamic model, the printing pressure determination can for the starting ω _is taking into account the dynamic torque component formed from the product of the engine inertia constant Θ and the derivative of the speed, according to the following equation carried out: $${\mathrm{p}}_{\mathrm{is}}={\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">k</figure-callout>}}_1\cdot \left({\mathrm{M}}_{\mathrm{is}}-\mathrm{\Theta }\cdot {\mathrm{\omega }}_{\mathrm{is}}\text{'}\right)$$

It has also proven to be expedient to detect state values, in particular position, rotational speed and torque, of a sensorless synchronous reluctance motor with a flow barrier cut by means of the regulating device. A rotor of a synchronous reluctance motor, provided with flow barriers or flow barriers in the rotor lamination section, can be controlled sensor-less with regard to its rotor angle position, also referred to as the position below, and its speed. In addition to the state values Speed and position of the synchronous reluctance motor is still available with the torque-generating current component, the torque of the motor. The nominal torque of the sensorless synchronous reluctance motor is already available when the engine is stopped, so that even with a flow rate of zero, the pressure can be maintained at the required level. The method according to the invention, in conjunction with the sensorless synchronous reluctance motor, enables a positive-displacement pump to start against a closed slide. The desired final pressure is available immediately.

It is particularly advantageous that such a synchronous reluctance motor is controlled without speed and without position sensors. Thus, with the method according to the invention, there is a control to a final pressure setpoint, which does not require a sensory detection of the final pressure and without position and speed sensors.

Additional advantages are provided by an embodiment of the method according to which the position of the drive motor, ie the angular position of the drive rotor to the drive stator, is detected by the control device, and the delivered volume of fluid is determined with the value of the closed displacement pump volume, the displacement volume. This results in the pumped fluid volume from the distance traveled distance of the drive rotor and the displacement of the positive displacement pump. Thus, defined by the method fluid volume can be promoted. End pressure and delivered fluid volume of the positive displacement pump unit can thus be determined simultaneously.

Furthermore, not complete filling of the positive displacement pump with the fluid to be delivered can be detected by the combination of final pressure control and determination of the delivered fluid volume. By recognizing an incomplete filling, which may be present, a correct calculation of the quantity delivered can take place.

It is provided that a predetermined volume of fluid is conveyed by the determined actual fluid volume with the predetermined fluid volume by the control device is compared and upon reaching the predetermined fluid volume, a conveying operation of the positive displacement pump unit is stopped. For this purpose, for example, starting with a start time, the delivery volume per piston stroke of the positive displacement pump is added up. Upon reaching the predetermined fluid volume of the delivery operation of the positive displacement pump unit is stopped. For this purpose, a pressure side arranged valve can be controlled by the control device and this closed.

In a control device according to the invention for carrying out the method according to the invention, wherein a controlled variable of a positive displacement pump is regulated by the control device to a desired value, it is provided that the control device comprises means for detecting at least one state value provided by the drive and a memory device that the control device Controlled variable determined from the state value, in order to regulate the positive displacement pump unit without the use of sensors and on the basis of the state values supplied by the drive to the predetermined setpoint. For this purpose, torque and position of the drive motor are detected according to the invention as state values of the drive. In particular, it is provided that the final pressure of the positive displacement pump is used as a controlled variable. This allows the regulation of the final pressure to the final pressure setpoint without pressure sensors. From the position information of the drive motor can be controlled to the control variable funded fluid volume.

According to an advantageous embodiment, it is provided that in the storage device of the control device, an engine torque-end pressure dependency of the positive displacement pump unit is stored and the control device controls the final pressure of the positive displacement pump by means of the engine torque-end pressure dependency of the positive displacement pump unit. The storage device serves to store the characteristic parameters or parameters characteristic of the respective positive-displacement pump. This takes place in the form of a characteristic curve, a value table, a formulaic relationship or the like. Conveniently, a linear relationship between engine torque and final pressure according to the above equation 1 is stored in the storage device.

Furthermore, the control device according to the invention is able to determine from the position information of the drive motor, more precisely the angular position of the drive rotor, and the value of the closed displacement pump volume, the displacement, the volume of fluid delivered and / or to regulate a predetermined fluid delivery rate.

A positive displacement pump assembly according to the invention with a positive displacement pump unit for conveying a fluid, wherein the positive displacement pump unit consists of a positive displacement pump and a variable speed drive, wherein the drive consists of an electric drive motor and a frequency converter, wherein a controlled variable, in particular end pressure and / or delivered fluid volume, the positive displacement regulated is, and optionally with a pressure side arranged valve, in particular shut-off valve is characterized by a control device according to the invention. Optionally, the valve, in particular the shut-off valve, is controlled and / or regulated by the regulating device.

Advantageously, the drive motor of the positive displacement pump unit is a sensorless synchronous reluctance motor with flow barriers. A flux-locked synchronous reluctance motor can be controlled sensorless with respect to its rotor angle position, and its speed. As state values of the control device speed, position and torque of the synchronous reluctance motor are available. The nominal torque of the sensorless synchronous reluctance motor is already available when the engine is stopped, so that even with a flow rate of zero, the pressure can be maintained at the required level. With the sensorless synchronous reluctance motor, it is also possible to start the positive-displacement pump unit against a closed slide. The desired final pressure is available immediately.

It has proven to be expedient that the drive has means for sensorless determination of the position and the rotational speed of the drive motor. The drive has for this purpose means for measuring electrical voltages and / or electric currents of the drive motor.

Fig. 1

eine Verdrängerpumpenanordnung gemäß dem Stand der Technik, die

Fig. 2

eine erfindungsgemäße Verdrängerpumpenanordnung, die

Fig. 3

eine regelungstechnische Darstellung einer erfindungsgemäßen Druckregelung, die

Fig. 4a

eine regelungstechnische Darstellung eines erfindungsgemäßen Verfahrensablaufs hinsichtlich Initialisierung Fluidvolumenbestimmung und Ventilöffnung, und die

Fig. 4b

eine regelungstechnische Darstellung eines erfindungsgemäßen Verfahrensablaufs hinsichtlich Fluidvolumenbestimmung und Ventilschließung.

Embodiments of the invention are illustrated in the drawings and will be described in more detail below. It show the

Fig. 1

a Verdrängerpumpenanordnung according to the prior art, the

Fig. 2

a Verdrängerpumpenanordnung invention, the

Fig. 3

a control engineering view of a pressure control according to the invention, the

Fig. 4a

a control engineering view of a process sequence according to the invention with regard to initialization fluid volume determination and valve opening, and the

Fig. 4b

a control technical representation of a process sequence according to the invention in terms of fluid volume determination and valve closure.

The FIG. 1 shows a Verdrängerpumpenanordnung 1 'according to the prior art in a schematic representation. A positive displacement pump 2 is connected on its pressure side 3 and on its suction side 4 to a piping system of a system not shown and by means of a shaft 5 by an existing rotor and stator electric motor 6 ', here a conventional induction motor, driven. The electric motor 6 'is variable speed operated and is supplied via a frequency converter 7' multi-phase, here three-phase, with a multi-phase, here three-phase, AC electrical network 9. _To f by means of a predetermined frequency reference value, the frequency converter operates 7 'the electric motor 6' at a certain but variable speed. Electric motor 6 'and frequency converter 7' thereby form the drive for the positive displacement pump 2. On the pressure side 3 of the positive displacement pump 2 is detected by a pressure sensor 10, a signal according to the final pressure pist of the assembly 1 'and forwarded to a control device 11'. The control device 11 'is used to control the final pressure pist the displacement pump 2 to a predetermined Enddrucksollwert p _to f _set by means of a frequency reference. To avoid

Overpressures and for rapid pressure reduction are in such a positive displacement pump assembly 1 'the pressure side separate, not shown here, pressure relief valves necessary. Providing a required pressure at a flow rate equal to zero, the so-called zero flow rate, is not possible with this arrangement. The time to adjust the pressure when opening a pressure side arranged, not shown here, slider is increased.

The FIG. 2 shows a schematic representation of a Verdrängerpumpenanordnung invention 1 with a positive displacement pump unit for conveying a fluid, which consists of a positive displacement pump 2 and a variable speed drive. The drive is formed by a provided with a stator and rotor electric drive motor 6 and a frequency converter 7. The electric motor 6 is polyphase via the frequency converter 7, here three-phase, connected to a mehrphasigien, here three-phase, AC electrical network 9. A control device 11 controls the positive displacement pump 2 to a predetermined final pressure setpoint. On the pressure side 3 of the positive displacement pump 2 designed as a shut-off valve 13 is arranged for closing the pressure-side pipe. The control device 11 has means for detecting the motor state values angular position φ _is , rotational speed ω _is and torque Mist of the drive motor 6 on. The control device 11 has a memory device for storing parameters, dependencies and / or characteristics. The control device 11 determines the final pressure pact from the torque Mist in order to regulate the displacement pump unit without the use of sensors to the predetermined final pressure p _soll . The control device 11 has the in the FIG. 3 shown and explained in more detail pressure regulator 15 which generates a required frequency setpoint f _soll . In contrast to the prior art, according to the invention neither a sensor signal of a pressure of the positive displacement pump nor of another sensor is required. According to the invention, the control device rather uses a stored in the storage device of the control device 11 engine torque-end pressure dependency of the positive displacement pump unit to control the final pressure of the positive displacement pump by means of the motor torque-end pressure dependence of the positive displacement pump unit. In addition, the control device 11 is capable of the position information φ _{is of} the drive motor 6 and a value of the completed displacement pump volume, the displacement volume, to determine the delivered fluid volume and / or to regulate a predetermined fluid delivery rate. About the control signal r, the control device 11, the shut-off valve 13 and control this open or close. In addition, with the aid of the speed information ω _, the accuracy of the pressure determination can be improved by taking into account the dynamic torque component in the starting state.

The FIG. 3 shows in a control engineering view of the operation of the pressure regulator 15 according to the invention. The actual value of the Verdrängerpumpenenddruckes pist results according to a stored in the memory device of the control device 11 engine torque-end pressure dependency 17 of manure. In this embodiment, this dependence is approximated by a linear model and given the constant k ₁ by the following formula: $${\mathrm{p}}_{\mathrm{is}}={\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">k</figure-callout>}}_1\cdot {\mathrm{M}}_{\mathrm{is}}$$

According to the invention, further models 17 are provided, for example a pressure model which maps the dynamic starting behavior according to equation 2 above. A control difference e between setpoint p _soll and calculated controlled variable pist is fed to a controller 16, in this case a proportional-integral controller (PI controller), which calculates therefrom the required frequency setpoint f _soll .

The FIG. 4a shows in a control engineering representation of a method sequence according to the invention for determining a funded fluid volume with respect to initialization and valve opening. The FIG. 4b shows accordingly the procedure in relation to the actual volume determination and a final valve closure. Given a start condition ("start = 1") and in the case of a control difference e below a threshold s, a valve 13 arranged on the pressure side 3 of the positive displacement pump 2 _is opened and opened for the start of a delivery with a defined fluid delivery volume V _soll held. The condition according to which the control difference e should be below a certain threshold ensures that a desired pressure level is built up before the delivery. In addition, done by the consideration of this start condition the determination of the volume determination on the condition that the positive displacement pump is completely filled. For the purpose of initializing the quantity determination, the initial angular position φ _{is set} to the actual value of the motor angular position (pist) The conveyed volume V _is given by k ₂ as a factor according to FIG Fig. 4b according to the closed delivery volume of the positive displacement pump (stroke volume) to: $${\mathrm{V}}_{\mathrm{is}.\mathrm{k}}={\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">k</figure-callout>}}_2\cdot {\mathrm{\theta }}_{\mathrm{k}}$$

The determination of volume takes place cyclically in successive, iterative steps marked with index k, where θ _{k represents} the value for the entire swept angular distance of the rotor. In the case of an achieved predetermined fluid flow rate V ( _{"V, k>} V _{shall") to} the conveying operation is stopped ( "start: = 0") and the check valve 13 is closed ( "r: = 0"). By such a method, the control device of the invention from the position information determined φ _is the drive motor and the value of the closed Verdrängerpumpenvolumens the pumped fluid volume and can to a predetermined fluid flow rate V _should regulate at a given pressure.

Claims (15)

1. Method for the variable rotational speed control of a displacement pump unit for delivering a fluid, by means of a control device, the displacement pump unit comprising a displacement pump and a drive, the drive comprising an electric drive motor provided with stator and rotor and a frequency converter, a controlled variable of the displacement pump being controlled to a set point by the control device, wherein,
   by means of the control device (11), at least one drive-provided state value of the drive is registered and, from this, the controlled variable of the displacement pump (2) is determined by the control device (11), in order to control the displacement pump unit to the set point without the use of sensors,
   characterized in that
   torque and position of the drive motor (6) are registered as state values of the drive.
2. Method according to Claim 1, characterized in that the final pressure is determined by the control device (11) as controlled variable of the displacement pump (2), in order to control the displacement pump unit to the final pressure set point without using sensors.
3. Method according to Claim 1 or 2, characterized in that the final pressure of the displacement pump (2) is controlled by means of a motor torque-final pressure dependency of the displacement pump unit that is stored in the control device (11).
4. Method according to Claim 3, characterized in that the final pressure is determined by taking a dynamic torque component into account.
5. Method according to one of Claims 1 to 4, characterized in that state values, in particular position, rotational speed and torque, of a sensorless synchronous reluctance motor having flux barriers are registered by the control device (11).
6. Method according to Claim 5, characterized in that the synchronous reluctance motor is controlled without rotational speed sensors and without position sensors.
7. Method according to one of Claims 1 to 6, characterized in that the position of the drive motor (6) is registered by the control device (11), and the delivered fluid volume is determined with the value of the sealed displacement pump volume.
8. Method according to Claim 7, characterized in that a predefined fluid volume is delivered by the fluid volume determined being compared by the control device (11) with the predefined fluid volume and, when the predefined fluid volume is reached, delivery operation of the displacement pump unit being stopped.
9. Control device for implementing the method according to one of Claims 1 to 8, a controlled variable of a displacement pump being controlled to a set point by the control device, wherein the control device (11) has means for registering at least one drive-provided state value of the drive and a memory device, in that the control device (11) determines the controlled variable from the state value, in order to control the displacement pump unit to the predefined set point without using sensors, characterized in that the control device (11) has means for registering the drive-provided state values torque and position of the drive motor (6).
10. Control device according to Claim 9, characterized in that the final pressure of the displacement pump (2) is used as controlled variable.
11. Control device according to Claim 10, characterized in that a motor torque-final pressure dependency of the displacement pump unit is stored in the memory device of the control device (11), and the control device (11) controls the final pressure of the displacement pump (2) by means of the motor torque-final pressure dependency of the displacement pump unit.
12. Control device according to Claim 9, 10, or 11, characterized in that the control device (11) determines the fluid volume delivered from the position information of the drive motor (6) and the value of the sealed displacement pump volume and/or controls a predefined fluid delivery rate.
13. Displacement pump arrangement having a displacement pump unit for delivering a fluid, the displacement pump unit comprising a displacement pump and a variable rotational speed drive, the drive comprising an electric drive motor provided with stator and rotor and a frequency converter, a controlled variable of the displacement pump being controlled, and possibly having a valve arranged on the pressure side, characterized by a control device (11) according to one of Claims 9 to 12.
14. Displacement pump arrangement according to Claim 13, characterized in that the drive motor (6) of the displacement pump unit is a synchronous reluctance motor having flux barriers and operated without sensors.
15. Displacement pump arrangement according to Claim 14, characterized in that the drive has means for determining the position and the rotational speed of the drive motor (6) without sensors.

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