CN119546855A

CN119546855A - Method for controlling a circulation pump

Info

Publication number: CN119546855A
Application number: CN202480002630.4A
Authority: CN
Inventors: 艾瑞克·B·索伦森; C·布拉德
Original assignee: Grundfos Holdings
Current assignee: Grundfos Holdings
Priority date: 2023-06-30
Filing date: 2024-04-16
Publication date: 2025-02-28
Also published as: WO2025002619A1; EP4508331A1

Abstract

The present disclosure relates to a method for controlling a circulation pump (7) installed in a system (1) for heating or cooling, wherein the system (1) is provided with one or more thermo valves (9), wherein the method comprises-operating the pump at an operating point, wherein the current operating point is defined as the intersection of an adaptable pump characteristic and a variable system characteristic (33 a-c), wherein the system characteristic (33 a-c) varies with a common Opening (OD) of the one or more thermo valves (9), wherein the pump characteristic is adapted by setting the speed of the pump (7), wherein the speed of the pump (7) is controlled in such a way that the operating point follows an adjustable control curve, and-automatically adjusting the control curve when the system characteristic (33 a-c) varies, to keep the common Opening (OD) of the one or more thermo valves (9) within a desired range between the minimum common opening (OD _min) and the maximum common opening (O _Dmax), characterized in that the automatic adjustment comprises automatically adjusting the system characteristic (kv) to be influenced by the system characteristic (kv) and providing a feed-forward variable (29) in response to the system variable.

Description

Method for controlling a circulation pump

Technical Field

The present disclosure relates to a method for controlling a circulation pump installed in a system for heating or cooling, wherein the system is equipped with one or more thermo-valves. For example, the system may be a conventional home heating system having a radiator equipped with a thermo valve (e.g., a Thermostatic Radiator Valve (TRV)). Alternatively or additionally, the thermostatted valve of the system may be a "smart valve" that is remotely temperature controlled by a smart valve application.

Background

The circulation pump is typically mounted at the piping system as a stand-alone circulation pump assembly comprising a pump, an electric motor for driving the pump and an electronics housing with electronics for controlling the speed of the motor. The circulation pump may be operated in different selectable control modes (e.g., a constant pressure control mode or a proportional pressure control mode). Each control mode may include a number of selectable pump control curves. If the pump is operated following a particular pump control curve, the operating point of the pump will be as consistent as possible with the pump control curve.

When the pipe system comprises a temperature controlled valve, the valve is gradually closed when the demand for thermal energy is reduced, and the valve is gradually opened when the demand for thermal energy is increased, so as to achieve the target temperature. In general, the circulation pump as a separate pump assembly does not obtain any direct information about the degree of valve opening or closing. If the pump follows its set pump control curve, it may run at an unnecessarily high speed when the valve is closed, or at an excessively low speed when the valve is open. Excessive pump speeds waste energy savings potential and result in undesirable flow noise. Too low a speed of the pump has a negative effect on the user comfort, since the cooling or heating system does not reach its target temperature, at least not within a desired time.

It is known in the art to adapt the pump control curve automatically in closed-loop control based on the pipe resistance value as feedback value. For example, EP0726396B1 or EP1323986B1 describes such an automatic adaptation of the pump control curve in closed-loop control.

Known methods of automatic adaptation of pump control curves have been shown to successfully reduce energy consumption and flow noise when the valve is closed. However, known methods of automatic adaptation of the pump control curve also appear to be too slow when the valve is open during periods of high thermal energy demand. The user thus experiences a lack of comfort because the cooling or heating system does not reach its target temperature, at least not within a desired time.

It is therefore an object of the present disclosure to provide a method for controlling a circulation pump which, on the one hand, adapts the pump control curves sufficiently fast both when the proportional control valves in the system are closed and when they are open. On the other hand, when the proportional control valve is closed, the energy consumption and flow noise are still reduced as much as possible.

Disclosure of Invention

According to a first aspect of the present disclosure, a method for controlling a circulation pump installed in a system for heating or cooling is provided, wherein the system is equipped with one or more thermo-valves. The method comprises the following steps:

Operating the pump at an operating point, wherein the current operating point is defined as the intersection of an adaptable pump characteristic curve and a variable system characteristic curve, wherein the system characteristic curve varies as a function of the common opening of the one or more temperature-controlled valves, wherein the pump characteristic curve is adapted by setting the pump speed, wherein the pump speed is controlled in such a way that the operating point follows an adjustable pump control curve, and

Automatically adjusting the pump control curve when the system characteristic curve changes to maintain the common opening of the one or more thermo valves within a desired range between a minimum common opening and a maximum common opening,

It is characterized in that the method comprises the steps of,

Automatically adjusting the pump control curve includes determining a system variable susceptible to a change in the system characteristic curve and using the system variable as an input to provide a feed forward signal to automatically adjust the pump control curve in a feed forward control.

The term "common opening" of one or more thermo valves, i.e. in the form of proportional control valves, is to be understood as an absolute or relative measure of the degree of opening or closing of all these thermo valves, e.g. ranging from 0% to 100%, through which the circulation pump pumps the heating or cooling liquid. If only one valve is present in the system, the "common opening" may simply be the opening of the valve. If there are two or more valves in the system, a weighted or unweighted average of the opening of the valves may be considered a "common opening". The individual pump assembly has no information about the common opening, but it "senses" the line resistance in proportion to the common opening of the valve. When all valves of the system are opened to the maximum, the pump experiences the lowest line resistance. When all but one valve is closed and this valve that is open is almost closed, the pump experiences the highest line resistance. It can be assumed that the pipe resistance is constant as long as the common opening of the valves does not change.

The system characteristic curve varies with the line resistance, i.e. it varies with the common opening of the valves. If the system characteristic changes, the pump characteristic is adapted by changing the pump speed to maintain the operating point on the pump control curve. If the pump control curve (e.g., a proportional pressure control curve in the form of a linear line in a head-flow-diagram) is fixed, then the undesirable situation occurs that the pump is not running at full speed when the valve is fully open due to high thermal energy demand and that the pump is running too fast when the valve is nearly closed or fully closed due to low or no thermal energy demand. In other words, it is most desirable to have the common opening degree of the valves within a desired range between the minimum common opening degree and the maximum common opening degree. Within this desired range, the thermo valve is able to react to the rise and fall of the thermal energy demand. Thus, the pump control curve is not fixed, but is adjustable to keep the common opening of the valves as much as possible within a desired range.

The inventive concept now consists in accelerating the adjustment of the pump control curve by determining a system variable susceptible to a change in the system characteristic curve and using the system variable as an input to provide a feed-forward signal to automatically adjust the pump control curve in feed-forward control.

For example, the system variable may be a flow factor, also denoted as kv value. The kv value is defined, for example, in "Fluidic characteristic quantities of control VALVES AND THEIR determination (fluid characteristic amount of control valve and determination thereof)", and is searched for in 2020, month 4 and 17, VDI, VDE, month 9 and 2173. The kv value represents the water flow through the system in m ³/h at a given common opening, with a pressure drop across the valve of 1 bar. It should be noted that the complete definition indicates that the flowing medium must have a specific gravity of 1000kg/m ³ and a kinematic viscosity of 10 ^-6m²/s, for example water. The kv value is generally defined asWhere q is the flow in m ³/h, dp is the pressure drop across the valve in bar, and SG is the specific gravity of the flowing medium (for water sg=1).

The pump can determine or estimate system variables based on its current operating point and performance indicators, such as the head and/or flow it provides, its current pump speed, power consumption, and/or current drawn by the pump drive motor. The determined or estimated system variable is then used as an input to provide a feed forward signal to automatically adjust the pump control curve in the feed forward control.

Optionally, the method may further comprise continuously or periodically monitoring a head value h indicative of the head currently provided by the circulation pump and a flow value q indicative of the flow currently provided by the circulation pump, wherein the head value h and the flow value q are used to determine a system variable, such as a kv value. To avoid the need for pressure sensors and/or flow sensors, it is beneficial to derive the lift and flow values from the electrical performance indicators of the pump motor (e.g., motor speed and power consumption).

Optionally, the step of automatically adjusting the pump control curve may further comprise:

recording the maximum and minimum values of the system variables that have been determined in the past period of time, and

-Determining a common opening value indicative of the common opening of the one or more thermo valves based on the distance of the system variable from the recorded maximum value and/or the recorded minimum value.

The maximum kv value and the minimum kv value may be used to estimate kv values for the highest common opening of the valve and the lowest common opening of the valve, respectively, over time.

Optionally, automatically adjusting the pump control curve may further comprise using a stored adaptable mapping between the system variable and a feedforward signal to be applied to the feedforward control. This is beneficial in consideration of the deviation from the target opening degree indicated by the PI controller. The map for feed forward may be adapted to keep the deviation from the target opening at a minimum.

Alternatively, a deviation of the determined common opening value from a predetermined reference common opening value may be used as another input to provide a feed forward signal in addition to the system variable, and wherein the deviation is used to update the stored adaptable mapping. It should be noted that under normal operation, this other input is much smaller than the contribution of the system variable to the feed forward control. The contribution of the deviation of the opening degree from the target opening degree is a relatively small correction to the feed-forward control, e.g. within +/-5%.

Alternatively, the stored adaptable map may include a list of relative values defining which control curve to apply at predetermined system variable points within the total range of applicable control curves, wherein the relative values are interpolated between the predetermined system variable points. For example, a suitable pump control curve may be in the range between the lowest proportional pressure curve PP1 and the highest proportional pressure curve PP 3. The stored adaptive map may include a list of relative values expressed in terms of percentages ranging from 0% for the lowest proportional pressure curve PP1 to 100% for the highest proportional pressure curve PP 3.

Alternatively, if the updated map has a non-negative gradient throughout, the stored adaptive map may be updated only for one or two relative values at those predetermined system variable points closest to the currently determined system variable, and wherein if the updated map does not have a non-negative gradient throughout, then

-Updating the stored adaptive map for one or both of the relative values at those predetermined system variable points closest to the currently determined system variable, in addition to updating the stored adaptive map for all higher predetermined system variable points by shifting these relative values up by an amount required to avoid the updated map having a negative gradient, and/or

-Updating the stored adaptive map for one or both of the relative values at those predetermined system variable points closest to the currently determined system variable, and further updating the stored adaptive map for all the relative values at lower predetermined system variable points by shifting these relative values downwards by an amount required to avoid that the updated map has a negative gradient.

The mapping between the system variable and the feedforward signal to be applied for feedforward control must not have a negative gradient, because the pump must not decrease the pump control curve when the valve is open, i.e. when the kv value rises. Similarly, the pump control curve must not increase when the valve is closed.

Alternatively, the adjustable pump control curve may be a proportional pressure curve. This is particularly advantageous if the valve is mounted at a heating radiator.

Alternatively, the system may comprise one or more thermal energy consumers and the one or more thermostatically-actuated valves may be automatically-actuated valves and/or thermostatically-actuated valves mounted at the thermal energy consumers. Preferably, the thermal energy consumer is a radiator of the heating system.

Alternatively, if the determined system variable is less than the previously determined system variable, the feedforward signal may be low-pass filtered by a predetermined time constant before the feedforward signal is used to automatically adjust the pump control curve in the feedforward control. This is particularly advantageous for avoiding undesired rapid oscillations between the control curves. Such oscillations have been shown to occur in households with low kv value variations, where small variations in valve opening may result in large variations in pump head that the valve is attempting to compensate for. Preferably, to avoid such oscillations, a first order filter, for example with a time constant of 1200 seconds, may be applied if the kv value decreases. However, the rising kv value may be used as an input to the feed-forward control without filtering.

Alternatively, the pump control curve can be steplessly adjusted within the total range of applicable pump characteristics.

Optionally, the method may further comprise operating the pump in a first lifting (boost) mode and/or a second lifting mode, wherein,

As long as the determined common opening value, which indicates the common opening of the one or more thermo valves, is within a predetermined low lift region adjacent to the minimum common opening or within a predetermined high lift region adjacent to the maximum common opening, a gain factor is applied in the first lift mode to more strongly adjust the pump control curve, and wherein,

The pump is operated at maximum speed in the second lifting mode if the following conditions are met:

The system variable is within a predetermined velocity lift region adjacent to the maximum value of the record of the system variable,

-The maximum pump control curve is currently applied and the predetermined period of maximum lift time has not elapsed.

The first boost mode may be referred to as PI controller boost. When the kv value and/or the opening degree is close to the maximum value or the minimum value, i.e. in the lifting region, the first lifting mode is preferably applied as a first level of lifting. If the first lift mode fails to successfully disengage the system from the high lift region within a given period of time, the second lift mode is activated to operate the pump at maximum speed for a particular maximum lift time.

According to another aspect of the present disclosure, there is provided a computer program having instructions which, when executed by a computer, cause the computer to perform the method previously described.

According to another aspect of the present disclosure, there is provided a circulation pump for installation in a system for heating or cooling, wherein the circulation pump comprises control electronics configured to perform the method described previously or to perform the above-described procedure.

Alternatively, the circulation pump may be automatically programmed at the manufacturing site of the circulation pump to perform the previously described method or to perform the previously described procedure. Thus, the fully assembled circulation pump may be left at the manufacturing site in a fully programmed state for shipment to the customer, such that the customer does not need to program the circulation pump.

The methods disclosed herein may be implemented in the form of compiled or uncompiled software code stored on a computer readable medium having instructions for performing the methods. Preferably, the software is installed on the control electronics within the circulation pump according to the invention. Alternatively or additionally, the method may be performed by software in a cloud-based system and/or a Building Management System (BMS).

Drawings

Embodiments of the present disclosure will now be described, by way of example, with reference to the following drawings, in which:

FIG. 1 schematically illustrates an example of a system for heating or cooling described herein;

FIG. 2 illustrates an example of a circulation pump described herein;

FIG. 3 schematically illustrates an example of how a pump control curve may be automatically adjusted according to the present disclosure;

fig. 4 schematically illustrates an example of how a common opening is determined according to the present disclosure;

Fig. 5 shows a determined kv value for a time of recording a maximum kv value and a minimum kv value according to the present disclosure;

FIG. 6 schematically illustrates an example of how valve position is controlled according to the present disclosure;

Fig. 7 shows a head-flow diagram of a lift region with an indication for valve position control according to the present disclosure;

FIG. 8a shows an example of an initial mapping between kv values and feedforward signals according to the present disclosure;

fig. 8b shows an example of the control curve in the head-flow diagram after the control curve has been adapted to the heating system;

FIG. 9 schematically shows an example of how the mapping between the kv value and the feedforward signal is updated according to the present disclosure, and

Fig. 10 shows an example of a map before an update, after an update, and with a limit to avoid negative gradients.

Detailed Description

Fig. 1 shows a system 1 for heating or cooling, typically installed in a home. For simplicity, system 1 is hereinafter referred to as a heating system, but it may equally be a cooling system without departing from the spirit of the present disclosure. The system 1 comprises a source of thermal energy 3, such as a gas boiler, a heat exchanger, a heating coil (coil) or a heat reservoir. The thermal energy source 3 is connected to a pipe system 4 filled with a fluid, such as water, which pipe system 4 is used for transferring thermal energy to one or more thermal energy consumers 5, such as a radiator, floor heating or heat exchanger. At least one circulation pump 7 is installed in the system 1 to circulate the fluid to transfer thermal energy from the thermal energy source 3 to the one or more thermal consumers 5.

The system 1 is also equipped with one or more thermo valves 9, such as a Thermo Radiator Valve (TRV), a smart valve or other kind of thermo valve. Each thermostatted valve 9 may be mounted in the vicinity of one of the thermal consumers 5 to control the fluid flow through that respective thermal consumer 5. The thermal energy consumers 5 are mounted in parallel in the system 1 such that each of the thermal energy consumers 5 has a fluid inlet connected to the feed line of the system 1 and a fluid outlet connected to the return line of the system 1. Preferably, the associated thermo valve 9 is mounted at the fluid inlet of the thermal energy consumer 5.

Typically, there is no direct control connection between the circulation pump 7 and the thermo valve 9. The thermo-valve 9 is controlled by closed loop control using a thermostat, wherein a temperature sensor is used to determine the current temperature and a target temperature can be set for the thermostat. For example, in the case of a heating system, when the measured temperature is lower than the target temperature, the valve 9 is opened in order to increase the flow rate of the heating fluid through the respective thermal energy consumers 5. Similarly, when the measured temperature is higher than the target temperature, the valve 9 is closed so as to reduce the flow of heating fluid through the thermal energy consumer 5.

It is known in principle that it is useful to adjust the speed of the circulation pump 7 in dependence on the common opening of the thermo valve 9. Since the circulation pump 7 is an independent device and the opening degree of the thermo valve 9 is not directly known, in principle, the circulation pump 7 is operated too fast when the common opening degree of the valves 9 is low, or the circulation pump 7 is operated too slow when the common opening degree of the valves 9 is high. This would lead to the undesirable situation that the circulation pump 7 consumes unnecessary power and produces unnecessary flow noise when the valve 9 is close to closing. Furthermore, the circulation pump 7 may not provide sufficient flow when the valve 9 is opened to the maximum during times of high thermal energy demand. Thus, comfort may be lacking during times of high thermal energy demand because it takes too long to reach the target temperature. It has been shown that known "auto-adapt" algorithms do not react fast enough to provide the required thermal energy flow in case of high thermal energy demand.

Fig. 2 shows a circulation pump 7 installed in the heating or cooling system 1 shown in fig. 1. The hardware of the circulation pump 7 as shown in fig. 2 may be identical to that of the circulation pump known in the prior art. However, the difference is the manner in which it is programmed and thus controlled to operate. The circulation pump 7 comprises a pump housing 11 having a suction inlet 13 and a pressure outlet 14. The suction inlet 13 and the pressure outlet 14 comprise coaxially aligned flanges pointing in opposite directions for installation in the pipe system 4 of the cooling or heating system 1 as shown in fig. 1. The pump housing 11 houses an impeller (not visible) that is rotatable about a rotor axis R to drive a fluid flow (e.g., a water flow) from a suction inlet 13 to a pressure outlet 14. The circulation pump 7 is a wet-running circulation pump with an integrated Permanent Magnet Synchronous Motor (PMSM) within a motor housing 15.

Furthermore, the circulation pump 7 comprises control electronics (not visible) within the motor housing 15 in order to control the speed of the circulation pump 7. The cover 17 of the motor housing 15 includes a front face 19 having a human-machine interface element such as a display, LED indicator, one or more buttons or switches. The user may manually set the circulation pump 7to follow a fixed control curve or operate in an "auto-adapt" control mode to automatically adapt the applied control curve. For example, in case the heating system 1 has a radiator as the thermal energy consumer 5, the circulation pump 7 may be set to one of three fixed ratio pressure curves PP1, PP2 and PP 3. For example, fig. 8b shows an example of three fixed control curves as linear lines in the head (h) -flow (q) diagram.

The circulation pump 7 may also include a wireless interface or connector through which the control electronics within the circulation pump 7 may be programmed, reprogrammed, or updated. Thus, the circulation pump 7 may be programmed at the time of manufacture and assembly and/or when it has been installed in the cooling or heating system 1.

Fig. 3 shows how the circulation pump 7 of fig. 2 is programmed for control. As already mentioned above, it is known in the prior art (for example from EP0726396B1 or EP1323986B 1) to adapt the pump control curve automatically in closed-loop control on the basis of the line resistance value as feedback value. Thus, the circulation pump 7 is known to react to changes in the opening of the valve 9 and set the pump control curve accordingly. Since this has been shown to be too slow to provide adequate comfort in the case of high thermal energy demands, the idea of the present invention is to use a system variable (e.g. pipe resistance or kv value) as input to provide a feed-forward signal to automatically adjust the control curve in feed-forward control. In other words, the circulation pump 7 is more actively used for indirectly controlling the valve position. It should be noted that there is no direct control communication between the circulation pump 7 and the valve 9. However, the circulation pump 7 knows that the valve 9 is open when the valve 9 does not obtain sufficient heat energy flow, and that the valve 9 is closed when the valve 9 obtains too much heat energy flow.

Thus, the control diagram shown in fig. 3 includes valve position control 21 and opening degree estimation 23. The goal of the valve position control 21 is to automatically adjust the control curve as the line resistance changes in order to maintain the common opening OD of the valve 9 within a desired range between the minimum common opening OD _min and the maximum common opening OD _max. Here, the common opening OD is kept as close as possible to a predetermined fixed reference or target opening OD _ref, for example OD _ref =0.55, where OD _min =0, and OD _max =1. The central range of the common opening is desirable because it leaves up and down control spaces to adjust the valve position to the current thermal energy demand.

The valve position control 21 takes the form of two variables (i.e., the current system variable in the form of a kv value and an estimated value of the current common opening OD) As input. The opening degree estimation 23 provides a kv value and an estimated common opening degree valueBoth as outputs to provide these values as inputs into the valve position control 21. The opening degree estimation 23 estimates the lift valueAnd flow valueAs input. The circulation pump 7 continuously or periodically monitors a lift value indicative of the lift h currently provided by the circulation pump 7In the same way, the circulation pump 7 continuously or periodically monitors a flow value indicative of the flow q currently provided by the circulation pump 7It should be noted, however, that neither the head h nor the flow q is necessarily measured by a pressure sensor and/or a flow sensor. Instead, the electronics performance variables of the circulation pump 7 (e.g., the present motor speed, the present consumed electric power, or the drawn electric motor current) may be used to estimate the present lift valueAnd the current flow valueThe opening degree estimation 23 is explained in more detail with reference to fig. 4 and 5. The details of the valve position control 21 are explained in more detail with reference to fig. 6. The output of the valve position 21 is a reference value h _ref indicating which proportional pressure curve the circulation pump 7 is to apply. The reference value h _ref is the sum of the output from the PI controller 25 and the adaptive feed forward signal 27.

Fig. 4 shows the opening degree estimation 23 in more detail. The opening estimate 23 starts with a lift value based on monitoringAnd a monitored flow valueThe kv value is calculated. The kv value (also denoted as flow factor) is used as a system variable to represent the flow of water through the system 1 in cubic meters per hour at a given common opening OD of the valve 9, with a pressure drop across the valve 9 of 1 bar. Thus, the kv value is calculated asThe kv value is also limited to be above a predetermined minimum value, such as 3.5m ³/h. If the lift valueBelow a lower limit, e.g., 0.5mH ₂ O, the kv value may be set to kv=od _ref(kv_high-kv_low)+kv_low. Fig. 5 depicts how a filter is applied to the calculated kv values in order to determine the current maximum kv value kv _high and the current minimum kv value kv _low. A timer is implemented to ensure that the system 1 stabilizes since the control algorithm was started. Estimated opening valueOnly if a predetermined minimum duration (e.g., 10 minutes) has elapsed since the control algorithm was started.

If the start-up delay has elapsed, it is checked whether the kv value shows a spike, for example after a start-up after a night set callback. The opening estimate 23 is suppressed as long as the kv value shows a high gradient indicating a kv spike. If there is no kv spike, the calculated kv values are filtered to determine minimum kv values kv _low and maximum kv values kv _high, which represent the minimum kv values and the maximum kv values over a particular time. The minimum kv value kv _low and the maximum kv value kv _high are calculated using peak detection filters with forgetting factors. This is achieved by low-pass filtering the kv value, wherein the time constant for the filtering is changed based on the relation between kv (kv _low and kv _high). For kv _high, the varying time constant gives a signal that changes rapidly towards higher values and slowly towards lower values. For kv _low, the varying time constant gives a signal that varies rapidly towards lower values and slowly towards higher values. The filtering is shown in fig. 5. Estimating the opening degree according to the following formula

k_υ,Δ＝max(k_υhigh-k_υlow,k_υBandMin)

It should be noted that k _vBandMin is used to protect the algorithm from division by zero and may be set to, for example, 0.03. When the kv value changes too little, k _{v,dynband,min} may be used to stop the re-estimation, i.e. k _{v,dynband,min} may be set to 0.05. In the case where the variation in kv value is very small, the estimated opening valueIs set to the reference value OD _ref. This is done to ensure that the values kv _low and kv _high have been initialized and that there is sufficient signal-to-noise ratio in the kv signal to perform meaningful control.

Fig. 6 shows the valve position control 21 in more detail. When the valve position control 21 is activated, it receives the calculated kv value and the estimated opening valueAs input variables. The kv value is used to calculate the output Out _ff of the adaptive feedforward control 29 as the feedforward signal 27. The adaptive feedforward control 29 includes an adaptive mapping using a store between kv values and the feedforward signal 27Out _ff. Fig. 8a shows an example of such an adaptable map, which is initially stored in the control electronics of the circulation pump 7. The feed forward signal 27Out _ff can be calculated as a linear interpolation between stored mapped points, such as

Where ff _kv,0 is the point just below the current kv value and ff _href,0 is the corresponding relative proportional pressure curve. ff _kv,1 is the point just above the current kv value and ff _href,1 is the corresponding relative proportional pressure curve. If the kv value is outside the range of the map, the relative proportional pressure curve value of the first and last points in the map is used.

The PI controller 25 will refer to the common opening OD _ref and the estimated common openingThe difference between them is taken as the input error to be minimized. The PI controller 25 may include controller parameters such as gain, time constant, and controller limit parameters that may be predetermined for normal operation. However, when the system 1 is in a lifting area as shown in fig. 7, the controller parameter may be set to a specific value. In particular, in case the system 1 is in a boost region, the controller gain and the controller limiting parameter may be multiplied by a certain factor when the boost control is activated in the PI controller 25. Boosting the PI controller 25 by applying a gain factor is a first boosting mode according to an embodiment of the present disclosure. In case the thermal energy demand is particularly high, the circulation pump may be operated in a second lifting mode, wherein the circulation pump 7 is set to maximum speed if the kv value is within a lifting region adjacent to the kv _max value and the maximum pump control curve is applied and the predetermined period of maximum lifting time has not elapsed.

The output 28Out _PI of the PI controller 25 (i.e., estimated common opening degreeDeviation from a predetermined reference common opening OD _ref) is used to update the stored adaptive map of the feed-forward control 29. Further, the output h _ref of the valve position control 21 is the sum of the feedforward signal 27Out _ff and the output 28Out _PI of the PI controller 25. It should be noted, however, that the output 28Out _PI of the PI controller 25 provides a much smaller contribution than the feedforward signal 27Out _ff, e.g., +/-5%, to the output h _ref of the valve position control 21 under normal operation (i.e., outside of any boost mode), with the feedforward signal 27Out _ff ranging from 0% to 100% and based on the kv value used as input to the feedforward control 29.

Fig. 7 shows a diagram of head (h) versus flow (q) with a pump characteristic 31 for maximum pump speed and three system characteristics 33a-c shown. The system characteristic 33a represents the case when the valve 9 has a minimum opening (od=0) and the kv value is at its minimum kv _min. The system characteristic 33b represents the case where the common opening OD of the valve 9 is at the reference value OD _ref (for example, OD _ref =0.55). The objective of the valve position control 21 is to operate the circulation pump 7 in such a manner that the common opening of the valves 9 is at or near the reference value OD _ref. The system characteristic curve 33c represents the case where the common opening OD is at a maximum value (od=1) and the kv value is at its maximum value kv _max. The lift region of the first lift mode to which the PI controller 25 is applied is a region (band) close to the limit system characteristic curves 33a and 33 c.

Fig. 8a shows an initial mapping 26 of kv values between zero and 2.5m ³/h with the pressure curve to be applied expressed as a percentage, which is a relative proportion. The relative proportional pressure curve value of 100% may represent the highest proportional pressure curve PP3. A relative proportional pressure curve value of 0% may represent the lowest proportional pressure curve PP1. The feedforward signal Out _ff, which is the output 27 of the feedforward control 29, is an interpolation between the mapped points in fig. 8a. The map of fig. 8a is then stored in the control electronics of the circulation pump 7.

Fig. 8b shows an example of the control curve in the lift (h) -flow (q) diagram after it has been adapted to the heating system 1. The lowest proportional pressure curve PP1 is only followed for flow rates below 0.1m ³/h or 0.1m ³/h. For flow rates between 0.1m ³/h and 0.2m ³/h, the proportional pressure curve gradually increases to apply the proportional pressure curve PP3 for flow rate values between 0.2m ³/h and 0.9m ³/h. Above 0.9m ³/h, the circulation pump 7 reaches its maximum in the example shown and follows its maximum pump characteristic curve 31 for flow values above 0.9m ³/h. When the pump reaches its maximum speed limit, the head decreases as the flow increases above 0.9m ³/h.

Fig. 9 shows how the mapping of fig. 8a used by the feedforward control 29 is adapted based on the output 28Out _PI of the PI controller 25. The output 28Out _PI of the PI controller 25 is used as an indicator to determine whether the feed forward signal 27Out _ff is too high or too low. If the current feed forward signal 27Out _ff is perfect for the current thermal energy demand, the output 28Out _PI of the PI controller 25 is zero. If the output of the PI controller 25 is positive, the feedforward signal 27Out _ff needs to be added. Likewise, the negative output 28Out _PI of the PI controller 25 indicates a decrease in the feedforward signal 27Out _ff. The stored map is adapted by changing the map point closest to the current kv value. Over time, the map adapts to the appropriate relative proportional pressure curve value h _ref needed to give a particular kv value.

Adaptation of the feed forward control 29 is only performed if the variation of the kv value is above the noise level (i.e. k _v,Δ≥k_{v,dynband,min}) and no kv spike is currently detected. Limiting the output 28Out _PI of the PI controller 25 based on PI controller limiting parameters prevents too aggressive adaptation when the PI controller 25 is operating in the first boost mode. The non-zero output 28Out _PI of the PI controller 25 indicates the deviation of the current kv value from the interpolation map and triggers the correction of the closest two map points proportional to the output 28Out _PI of the PI controller 25 so that the interpolation between these two corrected map points is based on the current kv value. If the current kv value is outside the mapping range of kv values, only the lowest or highest mapping points are adapted accordingly. The adapted mapping points are limited to relative proportional pressure curve values between 0% and 100%.

To avoid negative gradients in the map, the mapping points at all kv values above the adapted higher closest mapping point are shifted upwards to avoid that the updated map has the minimum amount needed for negative gradients. Similarly, where the lower closest mapping point is adapted downwards, all mapping points having kv values lower than the closest lower mapping point of the down-adaptation are shifted downwards by the amount required to avoid that the updated mapping has a negative gradient. Finally, the updated map is stored for subsequent iterations of the feedforward control 29.

Fig. 10 shows examples of how the map might look before the update (on the left), after the update (in the middle) and after adapting the map to avoid negative gradients (on the right). Fig. 10 shows on the left side the map stored before the update. However, the positive output 28Out _P of the PI controller indicates that the mapping around the current kv value should be increased. Thus, adjacent mapping points are shifted upward accordingly. The shift is weighted according to the distance of the current kv value to the mapping point. In the case shown, the nearest higher adjacent mapping point is shifted upwards more than the nearest lower adjacent mapping point. Since this will result in a negative gradient of the mapping between the nearest higher neighboring mapping point and the next nearest higher mapping point, all mapping points having kv values higher than the nearest higher neighboring mapping point are shifted upwards by the minimum amount a needed to avoid the negative gradient.

In the foregoing description, where reference is made to integers or elements having known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present disclosure, which should be construed to cover any such equivalents. The reader will also appreciate that integers or features of the disclosure that are described as optional, preferred, advantageous, convenient, etc. are optional and do not limit the scope of the independent claims.

The above embodiments are to be understood as illustrative examples of the present disclosure. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. While at least one exemplary embodiment has been shown and described, it should be understood that other modifications, substitutions, and alternatives are apparent to one of ordinary skill in the art and can be made without departing from the scope of the subject matter described herein, and the application is intended to cover any adaptations or variations of the specific embodiments discussed herein.

Furthermore, "comprising" does not exclude other elements or steps, and "a" or "an" does not exclude a plurality. Furthermore, the features or steps that have been described with reference to one of the above-described exemplary embodiments may also be used in combination with other features or steps of other exemplary embodiments described above. The method steps may be applied in any order or in parallel, or may form part of another method step or a more detailed version. It should be understood that all such modifications are intended to be within the scope of the patent granted herein as such modifications reasonably and properly fall within the scope of the contribution to the art. Such modifications, substitutions and alternatives can be made without departing from the spirit and scope of the disclosure, which should be determined from the appended claims and their legal equivalents.

List of reference numerals:

1. cooling or heating systems

3. Heat energy source

4. Pipeline system

5. Heat energy consumption device

7. Circulation pump

9. Temperature control valve

11. Pump housing

13. Suction inlet

14. Pressure outlet

15. Motor shell

17. Motor shell cover

19. Front face of motor housing cover

R rotor axis

21. Valve position control

23. Opening degree estimation

25 PI controller

27. Output Out of feedforward control _ff

28 Output Out of PI controller _PI

29. Adaptive feed forward control

31. Maximum speed pump characteristic curve

33A-c System characteristic curves

PP1 proportional pressure curve

PP2 proportional pressure curve

PP3 proportional pressure curve

A shift amount required to avoid negative gradients

Claims

1. A method for controlling a circulation pump (7) installed in a system (1) for heating or cooling, wherein the system (1) is equipped with one or more temperature control valves (9), wherein the method comprises:

- operating the pump at an operating point, wherein the current operating point is defined as the intersection of an adaptable pump characteristic curve and a variable system characteristic curve (33a-c), wherein the system characteristic curve (33a-c) varies as a function of the common opening degree (OD) of the one or more thermostatic valves (9), wherein the pump characteristic curve is adapted by setting the speed of the pump (7), wherein the speed of the pump (7) is controlled in such a way that the operating point follows the adjustable control curve; and

- automatically adjusting the control curve when the system characteristic curve (33a-c) changes so as to keep the common opening (OD) of the one or more thermostatic valves (9) within a desired range between a minimum common opening ( _ODmin ) and a maximum common opening ( _ODmax ),

Features

Automatically adjusting the control curve includes determining a system variable (kv) susceptible to changes in the system characteristic curve, and using the system variable (kv) as an input to provide a feedforward signal (27) to automatically adjust the control curve in a feedforward control (29).

2. The method according to claim 1 further comprises: continuously or periodically monitoring a head value indicating the head (h) currently provided by the circulation pump (7) and a flow value indicating the flow rate (q) currently provided by the circulation pump (7) Among them, the lift value and the flow value Used to determine the system variable (kv).

3. The method according to claim 1 or 2, wherein automatically adjusting the control curve further comprises:

- recording the maximum (kv _high ) and minimum (kv _low ) values of said system variable (kv) which have been determined over a past period of time; and

- determining a common opening value indicating a common opening (OD) of the one or more thermostatic valves (9) based on the distance of the system variable ( _kv ) from a recorded maximum value (kv _high ) and/or a recorded minimum value (kv low )

4. The method according to any of the preceding claims, wherein automatically adjusting the control curve further comprises using a stored adaptable mapping between the system variable (kv) and the feedforward signal (27) to be applied to the feedforward control (29).

5. The method according to claim 4, wherein the determined common opening value A deviation from a predetermined reference common opening ( _ODref ) is used as a further input to provide the feedforward signal (27), and wherein the deviation is used to update the stored adaptable map.

6. A method according to claim 4 or 5, wherein the stored adaptable mapping includes a list of relative values defining which control curve to apply at predetermined system variable points within a total range of applicable control curves, wherein the relative values are interpolated between the predetermined system variable points.

7. A method according to claim 6, wherein if the updated mapping has a non-negative gradient throughout, the stored adaptable mapping is updated only for one or two relative values at a predetermined system variable point closest to the currently determined system (1) variable (kv), and wherein if the updated mapping does not have a non-negative gradient throughout,

- in addition to updating the stored adaptable map for one or two relative values at predetermined system variable points closest to the currently determined system (1) variable (kv), updating the stored adaptable map for relative values at all higher predetermined system variable points by shifting the relative values upward by an amount required to avoid that the updated map has a negative gradient, and/or

- In addition to updating the stored adaptable map for one or two relative values at predetermined system variable points closest to the currently determined system (1) variable (kv), the stored adaptable map is also updated for relative values at all lower predetermined system variable points by shifting the relative values downward by an amount required to avoid that the updated map has a negative gradient.

8. The method according to any of the preceding claims, wherein the adjustable control curve is a proportional pressure curve (PP1, PP2, PP3).

9. The method according to any of the preceding claims, wherein the system (1) comprises one or more thermal energy consumers (5), and the one or more temperature-controlled valves (9) are automatically actuated valves and/or thermostatically actuated valves installed at the thermal energy consumers (5).

10. A method according to any one of the preceding claims, wherein the feedforward signal (27) is low-pass filtered with a predetermined time constant before being used for automatically adjusting the control curve in the feedforward control (29) if the determined system variable (kv) is less than a previously determined system variable (kv).

11 . The method according to claim 1 , wherein the control curve is infinitely adjustable over the entire range of an applicable pump characteristic curve.

12. The method according to any one of the preceding claims, further comprising: operating the pump in a first lift mode and/or a second lift mode, wherein:

As long as the common opening value (OD) of the one or more temperature control valves (9) is determined, applying a gain factor in the first boost mode to more strongly adjust the control curve in a predetermined low boost region adjacent to a minimum common opening ( _ODmin ) or in a predetermined high boost region adjacent to a maximum common opening ( _ODmax ), and

Wherein, the pump operates at maximum speed in the second lifting mode if the following conditions are met:

- the system variable (kv) is within a predetermined speed-up region adjacent to a recorded maximum value (kv _high ) of the system variable (kv), and

- the maximum control curve currently applied, and

-The scheduled period of maximum boost time has not yet passed.

13. A computer program comprising instructions which, when executed by a computer, cause the computer to perform a method according to any one of the preceding claims.

14. A circulation pump (7) for installation in a system (1) for heating or cooling, wherein the circulation pump (7) comprises control electronics configured to carry out a method according to any one of claims 1 to 12 or to carry out a program according to claim 13.

15. The circulation pump (7) according to claim 14, wherein the circulation pump (7) is automatically programmed at the manufacturing site of the circulation pump (7) to perform the method according to any one of claims 1 to 12 or to perform the program according to claim 13.