EP4508331A1

EP4508331A1 - Method for controlling a circulation pump

Info

Publication number: EP4508331A1
Application number: EP24720117.1A
Authority: EP
Inventors: Erik Baasch Sørensen; Christian BLAD
Original assignee: Grundfos Holdings AS
Current assignee: Grundfos Holdings AS
Priority date: 2023-06-30
Filing date: 2024-04-16
Publication date: 2025-02-19
Also published as: WO2025002619A1; CN119546855A

Abstract

The present disclosure is directed to a method for controlling a circulation pump (7) being installed in a system (1 ) for heating or cooling, wherein the system (1 ) is equipped with one or more temperature controlled valves (9), wherein the method comprises: operating the pump at an operating point, wherein the current operating point is defined as the intersection point of an adaptable pump characteristic curve and a variable system characteristic curve (33a-c), wherein the system characteristic curve (33a-c) varies with a common degree of openness (OD) of the one or more temperature-controlled 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 an adjustable control curve; and automatically adjusting the control curve when the system characteristic curve (33a-c) changes in order to keep the common degree of openness (OD) of the one or more temperature-controlled valves (9) in a desired range between a minimum common degree of openness (ODmin) and a maximum common degree of openness (ODmax), characterised in that automatically adjusting the control curve comprises determining a system variable (/cv) being susceptible to system characteristic curve changes, and using the system variable (/cv) as an input to provide a feed forward signal (27) to automatically adjust the control curve in a feed forward control (29).

Description

Applicant: GRUNDFOS HOLDING A/S Title: Method for controlling a circulation pump Our Ref.: GP 3722 WO Description TECHNICAL FIELD [01] The present disclosure is directed to a method for controlling a circulation pump being installed in a system for heating or cooling, 5 wherein the system is equipped with one or more temperature- controlled valves. For example, the system may be an ordinary house- hold heating system with radiators that are equipped with temperature- controlled valves, e.g. thermostatic radiator valves (TRVs). Alternatively, or in addition, the temperature-controlled valves of the system may be 10 “smart valves” being remotely temperature-controlled by a smart valve application. BACKGROUND 15 [02] A circulation pump is typically installed at a 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. constant pressure 20 control mode or proportional pressure control mode. Each control mode may include a certain number of selectable pump control curves. If the pump is operated to follow a certain pump control curve, the operating point of the pump sticks to the pump control curve if pos- sible. 25 Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 [03] When the piping system comprises temperature-controlled valves, the valves gradually close when the demand for thermal energy decreases and they gradually open when the demand for thermal en- ergy increases in order to achieve a target temperature. Typically, the 5 circulation pump as a stand-alone pump assembly does not get any direct information about how much the valves are opened or closed. If the pump sticks to its set pump control curve, it may run with an unnec- essary high speed when the valves close or with a too low speed when the valves open. A too high speed of the pump waists energy saving 10 potential and leads to undesired flow noise. A too low speed of the pump has a negative impact on the user comfort, because the cooling or heating system does not achieve its target temperatures, at least not within a desired time frame. 15 [04] It is known in the prior art to automatically adapt the pump con- trol curve in a closed-loop control based on a pipe resistance value as a feedback value. For example, EP 0726396 B1 or EP 1323986 B1 de- scribe such an automatic adaptation of the pump control curve in a closed-loop control. 20 [05] It has shown that the known methods of automatic adaptation of the pump control curve successfully reduce the energy consumption and flow noise when the valves close. However, the known methods of automatic adaptation of the pump control curve have also shown to25 be too slow when the valves open during high thermal energy de- mand. The user thus experiences a lack of comfort, because the cool- ing or heating system does not achieve its target temperatures, at least not within a desired time frame. 30 [06] It is therefore an object of the present disclosure to provide a method for controlling a circulation pump that on the one hand adapts the pump control curve quickly enough both when the proportional control valves in the system are closing and when they are opening. On Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 the other hand, the energy consumption and the flow noise is still to be reduced as much as possible when the proportional control valves are closing. 5 SUMMARY [07] According to a first aspect of the present disclosure, a method is provided for controlling a circulation pump being installed in a system 10 for heating or cooling, wherein the system is equipped with one or more temperature-controlled valves. The method comprises: - operating the pump at an operating point, wherein the current operating point is defined as the intersection point of an adapta- ble pump characteristic curve and a variable system characteris- 15 tic curve, wherein the system characteristic curve varies with a common degree of openness of the one or more temperature- controlled valves, wherein the pump characteristic curve is adapted by setting the speed of the pump, wherein the speed of the pump is controlled in such a way that the operating point fol-20 lows an adjustable pump control curve; and - automatically adjusting the pump control curve when the system characteristic curve changes in order to keep the common de- gree of openness of the one or more temperature-controlled valves in a desired range between a minimum common degree25 of openness and a maximum common degree of openness, characterised in that, automatically adjusting the pump control curve comprises determining a system variable being susceptible to system characteristic curve changes, and using the system variable as an input to provide a feed 30 forward signal to automatically adjust the pump control curve in a feed forward control. Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 [08] The term “common degree of openness” of the one or more temperature-controlled valves, i.e. in form of proportional control valves, is to be understood as an absolute or relative measure of how much open or closed all those temperature-controlled valves are 5 through which the circulation pump pumps heating or cooling liquid, e.g. ranging from 0% to 100%. If only one valve exists in the system, the “common degree of openness” may simply be the opening degree of said valve. If there are two or more valves in the system, a weighted or unweighted average of the opening degrees of the valves may be 10 considered as the “common degree of openness”. A stand-alone pump assembly has no information about the common degree of openness, but it “feels” a pipe resistance that scales with the common degree of openness of the valves. When all valves of the system are open to a maximum degree, the pump experiences the lowest pipe 15 resistance. When all of the valves but one are closed, and the one open valve is nearly closed, the pump experiences the highest pipe resistance. It can be assumed that the pipe resistance is constant as long as the common degree of openness of the valves does not change. 20 [09] The system characteristic curve varies with the pipe resistance, i.e. it varies with the common degree of openness of the valves. If the system characteristic curve changes, the pump characteristic curve is adapted by changing the pump speed to keep the operating point on 25 the pump control curve. If the pump control curve, e.g. a proportional pressure control curve in form of a linear line in a head-flow-diagram, is fixed, undesirable situations occur in which the pump does not run at full speed when the valves are fully open for high thermal energy de- mand and in which the pump runs too quickly when the valves are 30 nearly or fully closed for low or no thermal energy demand. In other words, it is most desirable to have the common degree of openness of the valves in a desired range between a minimum common degree of Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 openness and a maximum common degree of openness. In that de- sired range, the temperature-controlled valves can react to a rise and fall of the thermal energy demand. Thus, the pump control curve is not fixed, but adjustable to keep the common degree of openness of the 5 valves within the desired range as much as possible. [10] The inventive idea is now to speed up the adjustment of the pump control curve by determining a system variable that is suscepti- ble to system characteristic curve changes and by using the system 10 variable as an input to provide a feed forward signal to automatically adjust the pump control curve in a feed forward control. [11] For example, the system variable may be the flow factor, also denoted as kv-value. The kv-value is, for example, defined in “Fluidic 15 characteristic quantities of control valves and their determination”, VDI, VDE, September 2007, 2173, retrieved 17 April 2020. The kv-value ex- presses the amount of water flow in units of m³/h through the system at a given common degree of openness with a pressure drop of 1 bar across the valves. It should be noted that the complete definition says 20 that the flow medium must have a specific gravity of 1000 kg/m³ and a kinematic viscosity of 10⁻⁶ m²/s, e.g. water. The kv-value is generally de- fined as ^_^ = ^_^^^ wherein q is the flow in units of m³/h, ^p is the pres- sure drop across the valves in units of bar, and SG is the specific gravity of the flow medium (SG = 1 for water). 25 [12] The pump is able to determine or estimate the system variable based on its current operating point and performance indicators, such as its provided head and/or flow, its current pump speed, power con- sumption and/or the electric current currently drawn by the pump drive 30 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 a feed forward control. Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 [13] Optionally, the method may further comprise continuously or regularly monitoring a head value h indicative of the head currently provided by the circulation pump and a flow value q indicative of the 5 flow currently provided by the circulation pump, wherein the head val- ue h and the flow value q are used to determine the system variable, e.g. the kv-value. In order to avoid the need for a pressure sensor and/or a flow sensor, it is beneficial to derive the head value and the flow value from electric performance indicators of the pump moto, e.g. 10 motor speed and power consumption. [14] Optionally, the step of automatically adjusting the pump control curve may further comprise: - logging a maximum and a minimum of the system variable that15 has been determined over a past period of time; and - determining a common degree of openness value indicative of the common degree of openness of the one or more tempera- ture-controlled valves in dependence of the distance of the sys- tem variable from the logged maximum and/or logged minimum. 20 The maximum and minimum kv-values may be used to estimate over time the kv-values for the highest common degree of opening of the valves and the lowest common degree of opening of the valves, re- spectively. 25 [15] Optionally, automatically adjusting the pump control curve may further comprise using a stored adaptable mapping between the sys- tem variable and the feed forward signal to be applied for the feed forward control. This is beneficial to account for deviations from the tar- get opening degree as indicated by a PI controller. The mapping used 30 for the feed forward may be adapted to keep the deviation from the target opening degree at a minimum. Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 [16] Optionally, a deviation of the determined common degree of openness value from a pre-determined reference common degree of openness may be used as a further input in addition to the system vari- able to provide the feed forward signal, and wherein said deviation is 5 used to update the stored adaptable mapping. It should be noted that this further input is, under normal operation, much smaller than the con- tribution of the system variable to the feed forward control. The contri- bution of the deviation of the opening degree from the target opening degree is rather a minor correction, e.g. in the range of +/- 5%, to the10 feed forward control. [17] Optionally, the stored adaptable mapping may comprise a list of relative values defining which pump control curve is applied within a total range of applicable pump control curves at pre-determined sys-15 tem variable points, wherein the relative values are interpolated be- tween the pre-determined system variable points. For example, the applicable pump control curves may range between a lowest propor- tional pressure curve PP1 and a highest proportional pressure curve PP3. The stored adaptable mapping may comprise a list of relative values in20 terms of percentage ranging from 0% for the lowest proportional pres- sure curve PP1 and 100% for the highest proportional pressure curve PP3. [18] Optionally, the stored adaptable mapping may be updated 25 only for the one or two relative value(s) at those pre-determined system variable point(s) that are closest to the currently determined system variable if the updated mapping has a throughout non-negative gra- dient, and wherein otherwise the stored adaptable mapping is updat- ed in addition 30 - for the relative values at all higher pre-determined system variable points by shifting those relative values upward by an amount that Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 is needed to avoid the updated mapping from having a negative gradient, and/or - for the relative values at all lower pre-determined system variable points by shifting those relative values downward by an amount 5 that is needed to avoid the updated mapping from having a negative gradient. The mapping between the system variable and the feed forward signal to be applied for the feed forward control must not have a negative gradient, because the pump must not reduce the pump control curve 10 when the valves open, i.e. the kv-value rises. Similarly, the pump control curve must not increased when the valves close. [19] Optionally, the adjustable pump control curve may be a propor- tional pressure curve. This is particularly beneficial if the valves are in- 15 stalled at heating radiators. [20] Optionally, the system may comprise one or more thermal ener- gy consumers and the one or more temperature-controlled valves may be automatically and/or thermostatically actuated valves installed at20 said thermal energy consumers. Preferably, the thermal energy con- sumers are radiators of a heating system. [21] Optionally, the feed forward signal may be low-pass filtered with a predetermined time constant before it is used to automatically adjust 25 the pump control curve in the feed forward control if the determined system variable is smaller than the previously determined system varia- ble. This is particularly beneficial to avoid undesired rapid oscillations between the control curves. Such oscillations have shown to occur at households with low variations of the kv-value, where small changes of 30 the opening degree of the valves may lead to larger changes of the pump head which the valves try to compensate. Preferably, in order to avoid such oscillations, a first order filter, for instance with a time con- Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 stant of 1200 seconds, may be applied if the kv-value is dropping. A rising kv-value, however, may be used unfiltered as input into the feed forward control. 5 [22] Optionally, the pump control curve may be adjustable without steps within a total range of applicable pump characteristic curves. [23] Optionally, the method may further comprise operating the pump in a first boost mode and/or in a second boost mode, wherein10 a gain factor is applied in the first boost mode for stronger adjust- ing the pump control curve as long as a determined common degree of openness value indicative of the common degree of openness of the one or more temperature-controlled valves is within a pre- determined low boost area adjacent to a minimum common degree 15 of openness or within a pre-determined high boost area adjacent to a maximum common degree of openness, and wherein the pump is operated at maximum speed in the second boost mode if - the system variable is within a pre-determined speed boost area20 adjacent to a logged maximum of the system variable, and - a maximum pump control curve is currently applied, and a pre- determined period of maximum boosting time has not lapsed. The first boost mode may be referred to as a PI controller boost. It is preferably applied as a first stage boosting when the kv-value and/or 25 the opening degree is close to a maximum or minimum value, i.e. in a boost area. If the first boost mode is not successful to get the system out of the high boost area within a given time period, the second boost mode is activated to run the pump at maximum speed for a certain maximum boosting time. 30 [24] According to another aspect of the present disclosure, a com- puter program is provided with instructions which, when the program is Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 executed by a computer, cause the computer to carry out the previ- ously described method. [25] According to another aspect of the present disclosure, a circula- 5 tion pump is provided for being installed in a system for heating or cool- ing, wherein the circulation pump comprises control electronics being configured to carry out the previously described method or to execute the above-mentioned program. 10 [26] Optionally, the circulation pump may be automatically pro- grammed at a manufacturing site of the circulation pump to carry out the previously described method or to execute the previously de- scribed program. Thereby, the fully assembled circulation pump may leave the manufacturing site fully programmed for shipping to custom- 15 ers, such that there is no need for customers to program the circulation pump. [27] The method disclosed herein may be implemented in form of compiled or uncompiled software code that is stored on a computer 20 readable medium with instructions for executing the method. Preferably, the software is installed on control electronics within the circulation pump according to the present invention. Alternatively, or in addition, the method may be executed by software in a cloud-based system and/or a building management system (BMS). 25 SUMMARY OF THE DRAWINGS [28] Embodiments of the present disclosure will now be described by way of example with reference to the following figures of which: 30 Fig.1 shows schematically an example of a system for heating or cooling described herein; Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 Fig.2 shows an example of a circulation pump described here- in; Fig.3 shows schematically an example how the pump control 5 curve is automatically adjusted according to the present disclosure; Fig.4 shows schematically an example how the common de- gree of openness is determined according to the present10 disclosure; Fig.5 shows a determined kv-value of a time for logging maxi- mum and minimum kv-values according to the present disclosure; 15 Fig.6 shows schematically an example how the valve position is controlled according to the present disclosure; Fig.7 shows a head-flow-diagram with indicated boost areas for20 the valve position control according to the present disclo- sure; Fig. 8a shows an example of an initial mapping between the kv- value and the feed forward signal according to the pre-25 sent disclosure; Fig. 8b shows an example of a control curve in a head-flow- diagram after it has been adapted to a heating system; 30 Fig.9 shows schematically an example how the mapping be- tween the kv-value and the feed forward signal is updat- ed according to the present disclosure; and Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 Fig. 10 shows an example of the mapping before an update, af- ter an update, and with the restriction to avoid a negative gradient. 5 DETAILED DESCRIPTION [29] Fig. 1 shows a system 1 for heating or cooling as it is typically in- stalled in a household. For the sake of simplicity, the system 1 is referred10 to in the following as a heating system, but it could equally be a cool- ing system without departing from the spirit of the present disclosure. The system 1 comprises a thermal energy source 3, e.g. a gas boiler, a heat exchanger, a heating coil or a heat reservoir. The thermal energy source 3 is connected to a piping system 4 filled with a fluid, e.g. water,15 for transferring thermal energy to one or more thermal energy consum- ers 5, e.g. radiators, underfloor heating, or heat exchangers. At least one circulation pump 7 is installed in the system 1 to circulate the fluid for thermal energy transfer from the thermal energy source 3 to the one or more thermal consumers 5. 20 [30] The system 1 is further equipped with one more temperature- controlled valves 9, e.g. thermostatic radiator valves (TRVs), smart valves or other kinds of temperature-controlled valves. Each of the temperature-controlled valves 9 may be installed in the vicinity of one of the thermal consumers 5 to control the fluid flow through that respec- 25 tive thermal energy consumer 5. The thermal energy consumers 5 are installed in parallel in the system 1, such that each of the thermal ener- gy consumers 5 has a fluid inlet connected to a feed line of the system 1 and a fluid outlet to a return line of the system 1. The associated tem- perature-controlled valve 9 is preferably installed at a fluid inlet of the30 thermal energy consumer 5. Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 [31] Usually, there is no direct control connection between the circu- lation pump 7 and the temperature-controlled valves 9. The tempera- ture-controlled valves 9 are each controlled by a closed-loop control using a thermostat, wherein a temperature sensor is used to determine 5 the current temperature and a target temperature can be set for the thermostat. In case of a heating system, for example, the valves 9 open when the measured temperature is below a target temperature in or- der to increase the flow of the heating fluid through the respective thermal energy consumer 5. Analogously, the valve 9 closes when the10 measured temperature is above a target temperature in order to re- duce the flow of the heating fluid through the thermal energy consum- er 5. [32] It is in principle known that it is useful to adapt the speed of the circulation pump 7 depending on the common degree of openness of 15 the temperature-controlled valves 9. As the circulation pump 7 is a stand-alone device without direct knowledge of the opening degree of the temperature-controlled valves 9, it would in principle run too fast when the common degree of openness of the valves 9 is low or too slow when the common degree of openness of the valves 9 is high. This 20 would lead to the undesirable situation that the circulation pump 7 consumes unnecessary power and produces unnecessary flow noise when the valves 9 are nearly closed. Furthermore, the circulation pump 7 may not provide sufficient flow when the valves 9 are open to a max- imum degree during times of high thermal energy demand. Therefore, 25 there may be a lack of comfort during times of high thermal energy demand, because it takes too long to reach the target temperature. It has shown that known “auto adapt”-algorithms do not react quickly enough to provide the required thermal energy flow in situations of high thermal energy demand. Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 [33] Figure 2 shows a circulation pump 7 as it is installed in a heating or cooling system 1 as shown in figure 1. The hardware of the circulation pump 7 as shown in figure 2 may not differ from a circulation pump as known in the prior art. However, it differs in the way it is programmed 5 and thus controlled to operate. The circulation pump 7 comprises a pump housing 11 with a suction inlet 13 and pressure outlet 14. The sec- tion inlet 13 and the pressure outlet 14 comprise coaxially aligned flanges directed into opposite directions in order to be installed in a piping system 4 of a cooling or heating system 1 as shown in figure 1. 10 The pump housing 11 accommodates an impeller (not visible) that is rotatable around a rotor axis R in order to drive a fluid flow (e.g. water flow) from the suction inlet 13 to the pressure outlet 14. The circulation pump 7 is a wet-running circulation pump with an integrated perma- nent magnet synchronous motor (PMSM) within a motor housing 15. 15 [34] Furthermore, the circulation pump 7 comprises control electron- ics (not visible) within the motor housing 15 in order to control the speed of the circulation pump 7. A lid 17 of the motor housing 15 comprises a front face 19 with human-machine-interface elements, such as a dis- play, LED indicators, one or more buttons or switchers. A user may man- 20 ually set the circulation pump 7 to follow a fixed control curve or to run in an “auto adapt” control mode to automatically adapt the applied control curve. For example, in case of a heating system 1 with radiators as thermal energy consumers 5, the circulation pump 7 may be set to one of three fixed proportional pressure curves PP1, PP2 and PP3. For 25 example, figure 8b shows an example of three fixed control curves as linear lines in a head(h)-flow(q)-diagram. [35] The circulation pump 7 may further comprise a wireless interface or a connector via which the control electronics within the circulation pump 7 can be programmed, reprogrammed or updated. The circula- 30 tion pump 7 may thus be programmed at the time of manufacturing Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 and assembly and/or when it is already installed in a cooling or heating system 1. [36] Figure 3 shows how the circulation pump 7 of figure 2 is pro- grammed to be controlled. As already mentioned above, it is known in 5 the prior art, for example from EP 0726396 B1 or EP 1323986 B1, to au- tomatically adapt the pump control curve in a closed loop control based on a pipe resistance value as a feedback value. So, the circula- tion pump 7 is known to react to a change of the opening degree of the valves 9 and to set the pump control curve accordingly. As this has 10 shown to be too slow to provide sufficient comfort in situations of high thermal energy demand, the idea of the present invention to use a sys- tem variable, e.g. a pipe resistance or a kv-value, as an input to pro- vide a feed forward signal to automatically adjust the control curve in a feed forward control. In other words, the circulation pump 7 is more 15 proactively used to indirectly control the valve position. It should be noted that there is no direct control communication between the circu- lation pump 7 and the valves 9. The circulation pump 7, however, knows that the valves 9 open when they do not get sufficient thermal energy flow and that they close when they get too much thermal en- 20 ergy flow. [37] Therefore, the control schematics shown in figure 3 comprise a valve position control 21 and an opening degree estimation 23. It is the goal of the valve position control 21 to automatically adjust the control curve when the pipe resistance changes in order to keep the common 25 degree of openness OD of the valves 9 in a desired range between a minimum common degree of openness ODmin and a maximum com- mon degree of openness ODmax. Here, the common degree of open- ness OD in kept as close as possible to a predetermined fixed reference or target opening degree ODref, e.g. ODref = 0.55, wherein ODmin = 0 and30 ODmax = 1. A central range of the common degree of openness is de- Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 sirable, because it leaves upward and downward control room to ad- just the valve position to the current thermal energy demand. [38] The valve position control 21 takes two variables as an input, i.e. a current system variable in form of a kv-value and an estimated value 5 ^^ of the current common degree of openness OD. The opening de- gree estimation 23 provides both the kv-value and the estimated common degree of openness value ^^ as an output to provide these values as input into the valve position control 21. The opening degree estimation 23 takes as input a head value ℎ^{^} and a flow value ^. The¹⁰ circulation pump 7 continuously or regularly monitors the head value ℎ^{^} which is indicative of the head h currently provided by the circulation pump 7. In the same way, the circulation pump 7 continuously or regu- larly monitors the flow value ^ which is indicative of the flow q currently provided by the circulation pump 7. It should be noted, however, that 15 neither the head h nor the flow q is necessarily measured by a pressure sensor and/or a flow sensor. Instead, electronic performance variables of the circulation pump 7, e.g. current motor speed, current consumed electric power, or drawn electric motor current, may be used to esti- mate the current head value ℎ^{^} and the current flow value ^. The open- 20 ing degree estimation 23 is explained in more detail with reference to figures 4 and 5. The details of the valve position control 21 are ex- plained in more detail with reference to figure 6. The output of the valve position 21 is a reference value href indicating which proportional pressure curve is to be applied by the circulation pump 7. The refer- 25 ence value href is the sum of the outputs from a PI controller 25 and an adaptive feed forward signal 27. [39] Figure 4 shows the opening degree estimation 23 in more detail. It starts with calculating a kv-value based on the monitored head value ℎ^{^} and monitored flow value ^. The kv-value, also denoted as flow fac- 30 tor, is used as system variable to express the amount of water flow in Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 units of cubic meters per hour through the system 1 at a given common degree of openness OD of the valves 9 with a pressure drop of one bar ^^ across the valves 9. So, the kv-value is calculated as ^^ = ^{^} _^ . The kv- value is further limited to be above a predetermined minimum value, 5 e.g. 3.5 m³/h. If the head value ℎ^{^} is below a lower limit, e.g. 0.5 mH2O, the kv-value may be set to ^^ = ^^_^^^ (^^_^^^^- ^^_^^^) +^^_^^^. Figure 5 describes how a filter is applied to the calculated kv-value in order to determine the current maximum kv-value ^^_^^^^ and the current mini- mum kv-value ^^_^^^. A timer is implemented to ensure that the system 110 has stabilised since the control authorism has been started. The esti- mated opening degree value ^^ is only estimated if a predetermined minimum time duration, e.g. 10 minutes, has passed since the control algorithm was started. [40] If the start delay has passed, it is checked whether the kv-value 15 shows a spike, for example after a start-up following a night set back. The opening degree estimation 23 is suppressed as long as the kv-value shows such a high gradient that indicates a kv-spike. If there is no kv- spike, the calculated kv-value is filtered to determine the minimum kv- value ^^ low and the maximum kv-value ^^_^^^^ which represent the low-20 est and highest kv-value within a certain time frame. They are calculat- ed using a peak detection filter with a forgetting factor. This is imple- mented by low-pass filtering the kv-value, wherein the time constants for the filtering change based on the relation between ^^, ^^_^^^ and ^^_^^^^. For ^^_^^^^, the changing time constants give a signal that is fast 25 changing towards higher values and slower towards lower values. For ^^_^^^, the changing time constants give a signal that is fast changing towards lower values and slow towards higher values. The filtering is illus- trated in figure 5. The opening degree ^^ is estimated according to the following formula: Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 [41] It should be noted that ^_^^^^^^^^ is used to protect the algorithm against divisions by zero and may be set to 0.03 for example. ^_{^,^^^^^^^,^^^} may be used to stop a re-estimation when the kv-value 5 variations are too small, i.e. ^_{^,^^^^^^^,^^^} may be set to 0.05. The esti- mated opening degree value ^^ is set to the reference value ODref in case of very small variations of the kv-value. This is done to ensure that the values ^^_^^^and ^^_^^^^ have initialised and that there is sufficient signal-to-noise ratio in the kv-signal to perform a meaningful control. 10 [42] Figure 6 shows the valve position control 21 in more detail. When it starts, it receives the calculated kv-value and the estimated opening degree value ^^ as input variables. The kv-value is used to calculate an output ^^^_^^ of an adaptive feed forward control 29 as a feed forward signal 27. The adaptive feed forward control 29 comprises using a15 stored adaptable mapping between the kv-value and the feed for- ward signal 27 ^^^_^^ . Figure 8a shows an example of such an adapta- ble mapping as it is initially stored in the control electronics of the circu- lation pump 7. The feed forward signal 27 ^^^_^^ may be calculated as a linear interpolation between the stored mapping points as 20 wherein ^^_^^,^ is the point just below the current kv-value and ^^_^^^^,^ is the corresponding relative proportional pressure curve. ^^_^^,^ is the point Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 that is just above the current kv-value ^^ and ^^_^^^^,^ is the correspond- ing relative proportional pressure curve. The relative proportional pres- sure curve value of the first and the last point in the mapping are used if the kv-value is outside the range of the mapping. 5 [43] The PI controller 25 takes the difference between the reference common degree of openness ODref and the estimated common de- gree of openness value ^^ as an input error to be minimised. The PI controller 25 may comprise controller parameters, such as gain, time constants and controller limitation parameter that may be predeter- 10 mined for normal operation. However, the controller parameters may be set to specific values when the system 1 is in a boost area as shown in figure 7. In particular, the controller gain and controller limitation pa- rameter may be multiplied by a certain factor when a boost control is activated in the PI controller 25 when the system 1 is in the boost area. 15 The boost of the PI controller 25 by applying a gain factor is a first boost mode according to an embodiment of the present disclosure. The cir- culation pump may in situations of particularly high thermal energy demand be operated in a second boost mode, in which the circulation pump 7 is set to maximum speed if the kv-value is within a boost area20 adjacent to the ^^max-value and a maximum pump control curve is ap- plied and a predetermined period of maximum boosting time has not lapsed. [44] The output 28 ^^^_^^ of the PI controller 25, i.e. a deviation of the estimated common degree of openness ^^ from the predetermined ²⁵ reference common degree of openness OD^ref is used to update the stored adaptable mapping of the feed forward control 29. Further- more, the output of the valve position control 21 href is the sum of the feed forward signal 27 ^^^_^^ and the output 28 ^^^_^^ of the PI controller 25. It should be noted, however, that the output 28 ^^^_^^ of the PI con- 30 troller 25 provides under normal operation, i.e. outside of any of the Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 boost modes, a much smaller contribution, e.g. +/- 5%, to the output of the valve position control 21 href than the feed forward signal 27 ^^^_^^ which ranges from 0% to 100% and is based on the kv-value that is used as input into the feed forward control 29. 5 [45] Figure 7 shows a head(h)-flow(q)-diagram with a pump charac- teristic curve 31 of maximum pump speed and three displayed system characteristic curves 33a-c. The system characteristic curve 33a repre- sents the situation when the valves 9 have a minimum degree of open- ness (OD = 0) and the kv-value is at its minimum ^^min. The system char-10 acteristic curve 33b represents the situation in which the common de- gree of openness OD of the valves 9 is at the reference value ODref, e.g. ODref = 0.55. It is the goal of the valve position control 21 to operate the circulation pump 7 in such a way that the common degree of open- ness of the valves 9 is at or around the reference value ODref. The sys-15 tem characteristic curve 33c represents a situation in which the com- mon degree of openness OD is at a maximum (OD = 1) and the kv- value is at its maximum ^^max. The boost areas for applying the first boost mode of the PI controller 25 are the bands close to the extreme system characteristic curves 33a and 33c. 20 [46] Figure 8a shows an initial mapping of 26 kv-values between zero and 2.5 m³/h to the relative proportional pressure curve to be applied in terms of percent. A 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 pro-25 portional pressure curve PP1. The feed forward signal ^^^_^^ as the out- put 27 of the feed forward control 29 is an interpolation between the mapping points in figure 8a. The mapping of figure 8a is then stored in the control electronics of the circulation pump 7. Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 [47] Fig. 8b shows an example of a control curve in a head(h)- flow(q)-diagram after it has been adapted to the heating system 1. The lowest proportional pressure curve PP1 is only followed for a flow below or 0.1 m³/h. For flows between 0.1 and 0.2 m³/h, the proportional pres- 5 sure curve is gradually increased to apply the proportional pressure curve PP3 for flow values between 0.2 and 0.9 m³/h. Above 0.9 m³/h, the circulation pump 7 reaches in the shown example its maximum and follows its maximum pump characteristic curve 31 for flow values above 0.9 m³/h. As the pump has reached its maximum speed limit, the head10 drops with an increase of flow above 0.9 m³/h. [48] Figure 9 shows how the mapping of figure 8a as used by the feed forward control 29 is adapted based on the output 28 ^^^_^^ of the PI controller 25. The output 28 ^^^_^^ of the PI controller 25 is used as an indicator to decide whether the feed forward signal 27 ^^^_^^ is too high 15 or too low. If the current feed forward signal 27 ^^^_^^ is perfect for the current thermal energy demand, the output 28 ^^^_^^ of the PI controller 25 is zero. If the output of PI controller 25 is positive, there is a need to increase the feed forward signal 27 ^^^_^^ . Likewise, a negative output 28 ^^^_^^ of the PI controller 25 suggests a decrease of the feed forward20 signal 27 ^^^_^^ . The stored mapping is adapted by changing the map- ping points located closest to the current kv-value. Over time, the mapping is adapted to give the appropriate relative proportional pres- sure curve value href needed for a certain kv-value. [49] The adaptation of the feed forward control 29 is only performed²⁵ if the variation of the kv-value is above a noise level, i.e. ^_^,∆ ≥ ^_{^,^^^^^^^,^^^} and there is no kv-spike currently detected. A limitation of the output 28 ^^^_^^ of the PI controller 25 based on a PI controller limit- ing parameter prevents a too aggressive adaptation when the PI con- troller 25 is operated in the first boost mode. A non-zero output 28 30 ^^^_^^ of the PI controller 25 shows as a deviation of the current kv-value Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 from the interpolated mapping and triggers a correction of the closest two mapping points in proportion to the output 28 ^^^_^^ of the PI con- troller 25 such that the interpolation between those two corrected mapping points lies on the current kv-value. If the current kv-value is 5 outside of the mapped range of kv-values, only the lowest or highest mapping point is adapted accordingly. The adapted mapping points are limited to relative proportional pressure curve values between 0% and 100%. [50] In order to avoid a negative gradient in the mapping, the map- 10 ping points at all kv-values above the adapted higher closest mapping point are shifted upward by the minimum amount that is needed to avoid the updated mapping from having a negative gradient. Similarly, in case of a downward adaptation of the lower closest mapping point, all mapping points with kv-values below said downward adapted clos- 15 est lower mapping point are shifted downward by an amount that is needed to avoid the updated mapping from having a negative gradi- ent. Finally, the updated mapping is stored for the subsequent iteration of the feed forward control 29. [51] Figure 10 shows an example how the mapping may look like be- 20 fore an update (on the left), after an update (in the middle) and after the mapping is adapted to avoid a negative gradient (on the right). Figure 10 shows on the left the mapping as it is stored before it is updat- ed. A positive output 28 ^^^_^^ of the PI controller, however, suggests that the mapping around the current kv-value should be increased. 25 Therefore, the neighbouring mapping points are shifted upward ac- cordingly. The shifting is weighted according to the distance of the cur- rent kv-value to the mapping point. In the shown case, the closest higher neighbouring mapping point is shifted more upward than the closest lower neighbouring mapping point. As this would lead to a30 negative gradient in the mapping between the closest higher neigh- Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 bouring mapping point and the next-to-closest higher mapping point, all mapping points with kv-values above the closest higher neighbour- ing mapping point are shifted upward by the least amount A that is necessary to avoid a negative gradient. 5 [52] Where, in the foregoing description, integers or elements are mentioned which have 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 so as to 10 encompass any such equivalents. It will also be appreciated by the reader that integers or features of the disclosure that are described as optional, preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. 15 [53] The above embodiments are to be understood as illustrative ex- amples of the disclosure. It is to be understood that any feature de- scribed 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 embodi- 20 ments, 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 alter- natives are apparent to one of ordinary skill in the art and may be changed without departing from the scope of the subject matter de-25 scribed herein, and this application is intended to cover any adapta- tions or variations of the specific embodiments discussed herein. [54] In addition, "comprising" does not exclude other elements or steps, and "a" or "one" does not exclude a plural number. Furthermore, 30 characteristics or steps which have been described with reference to one of the above exemplary embodiments may also be used in com- bination with other characteristics or steps of other exemplary embod- Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 iments described above. Method steps may be applied in any order or in parallel or may constitute a part or a more detailed version of anoth- er method step. It should be understood that there should be embod- ied within the scope of the patent warranted hereon all such modifica- 5 tions as reasonably and properly come within the scope of the contri- bution 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. 10 [55] List of reference numerals: 1 cooling or heating system 3 thermal energy source 15 4 piping system 5 thermal energy consumer 7 circulation pump 9 temperature-controlled valve 11 pump housing 20 13 suction inlet 14 pressure outlet 15 motor housing 17 motor housing lead 19 front face of motor housing lead 25 R rotor axis 21 valve position control 23 opening degree estimation 25 PI controller 27 output ^^^_^^ of the feed forward control 30 28 output ^^^_^^ of the PI controller 29 adaptive feed forward control 31 pump characteristic curve of maximum speed 33a-c system characteristic curves Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 PP1 proportional pressure curve PP2 proportional pressure curve PP3 proportional pressure curve A shifting amount needed to avoid negative gradient Patentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024

Claims

Claims 1. A method for controlling a circulation pump (7) being installed in a system (1) for heating or cooling, wherein the system (1) is equipped with one or more temperature-controlled valves (9), 5 wherein the method comprises: - operating the pump at an operating point, wherein the current operating point is defined as the intersection point of an adaptable pump characteristic curve and a variable system characteristic curve (33a-c), wherein the system characteristic 10 curve (33a-c) varies with a common degree of openness (OD) of the one or more temperature-controlled 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 con- trolled in such a way that the operating point follows an ad-15 justable control curve; and - automatically adjusting the control curve when the system characteristic curve (33a-c) changes in order to keep the common degree of openness (OD) of the one or more tem- perature-controlled valves (9) in a desired range between a20 minimum common degree of openness (ODmin) and a maxi- mum common degree of openness (ODmax), characterised in that automatically adjusting the control curve comprises determining a system variable (^^) being susceptible to system characteristic 25 curve changes, and using the system variable (^^) as an input to provide a feed forward signal (27) to automatically adjust the control curve in a feed forward control (29). 2. The method of claim 1, further comprising continuously or regularly ³⁰ monitoring a head value (ℎ^{^} ) indicative of the head (h) currently provided by the circulation pump (7) and a flow value (^ ) indica- atentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 tive of the flow (q) currently provided by the circulation pump (7), wherein the head value (ℎ^{^} ) and the flow value (^ ) are used to determine the system variable (^^). 5 3. The method of claim 1 or 2, wherein automatically adjusting the control curve further comprises: - logging a maximum (^^_^^^^) and a minimum (^^_^^^) of the sys- tem variable (^^) that has been determined over a past period of time; and 10 - determining a common degree of openness value (^^) indic- ative of the common degree of openness (OD) of the one or more temperature-controlled valves (9) in dependence of the distance of the system variable (^^) from the logged maximum logged minimum (^^_^^^). 15 4. The method of any of the preceding claims, wherein automatical- ly adjusting the control curve further comprises using a stored adaptable mapping between the system variable (^^) and the feed forward signal (27) to be applied for the feed forward control 20 (29). 5. The method of claim 4, wherein a deviation of the determined common degree of openness value (^^) from a pre-determined reference common degree of openness (ODref) is used as a further 25 input to provide the feed forward signal (27), and wherein said deviation is used to update the stored adaptable mapping. 6. The method of claim 4 or 5, wherein the stored adaptable map- ping comprises a list of relative values defining which control 30 curve is applied within a total range of applicable control curves at pre-determined system variable points, wherein the relative atentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 values are interpolated between the pre-determined system vari- able points. 7. The method of claim 6, wherein the stored adaptable mapping is 5 updated only for the one or two relative value(s) at those pre- determined system variable point(s) that are closest to the cur- rently determined system (1) variable (^^) if the updated mapping has a throughout non-negative gradient, and wherein otherwise the stored adaptable mapping is updated in addition 10 - for the relative values at all higher pre-determined system vari- able points by shifting those relative values upward by an amount that is needed to avoid the updated mapping from having a negative gradient, and/or - for the relative values at all lower pre-determined system vari- 15 able points by shifting those relative values downward by an amount that is needed to avoid the updated mapping from having a negative gradient. 8. The method of any of the preceding claims, wherein the adjusta-20 ble control curve is a proportional pressure curve (PP1, PP2, PP3). 9. The method of 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 25 and/or thermostatically actuated valves installed at said thermal energy consumers (5). 10. The method of any of the preceding claims, the feed forward sig- nal (27) is low-pass filtered with a predetermined time constant 30 before it is used to automatically adjust the control curve in the feed forward control (29) if the determined system variable (^^) is smaller than the previously determined system variable (^^). atentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 11. The method of any of the preceding claims, wherein the control curve is adjustable without steps within a total range of applicable pump characteristic curves. 5 12. The method of any of the preceding claims, further comprising operating the pump in a first boost mode and/or in a second boost mode, wherein a gain factor is applied in the first boost mode for stronger adjust- ing the control curve as long as a determined common degree of10 openness value (^^) indicative of the common degree of open- ness (OD) of the one or more temperature-controlled valves (9) is within a pre-determined low boost area adjacent to a minimum common degree of openness (ODmin) or within a pre-determined high boost area adjacent to a maximum common degree of 15 openness (ODmax), and wherein the pump is operated at maximum speed in the second boost mode if - the system variable (^^) is within a pre-determined speed boost area adjacent to a logged maximum (^^_^^^^) of the sys-20 tem variable (^^), and - a maximum control curve is currently applied, and - a pre-determined period of maximum boosting time has not lapsed. 25 13. A computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method of any of the preceding claims. 14. A circulation pump (7) for being installed in a system (1) for heat- 30 ing or cooling, wherein the circulation pump (7) comprises control electronics being configured to carry out the method of any of the claims 1 to 12 or to execute the program of claim 13. atentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024 15. The circulation pump (7) of claim 14, wherein the circulation pump (7) is automatically programmed at a manufacturing site of the circulation pump (7) to carry out the method of any of the claims 1 to 12 or to execute the program of claim 13. atentanwälte Vollmann Hemmer Lindfeld GP 3722 WO, 16/04/2024