Method for controlling at least two fans

Abstract

A control device and a method for controlling a system having at least two fans (1) and/or fan groups for generating a defined setpoint value (VG,setpoint, ΔpG,setpoint), wherein, by changing the operating points of at least one fan (1) depending on which setpoint value is fixedly predetermined, at least one of the fans (1) is brought to an optimal operating point and thereby the efficiency ηG of the system is increased.

Claims

1. A method for controlling a system comprising a number n of at least two fans and/or fan groups for generating a setpoint value (V.sub.G,setpoint, Δp.sub.G,setpoint) of either a fixed volume flow V.sub.G,setpoint in the system with a variable pressure increase Δp.sub.G,setpoint or a fixed pressure increase Δp.sub.G,setpoint in the system with a variable volume flow V.sub.G,setpoint, as defined by the following steps: a) determining the current operating state for each of the fans; b) determining the power optimization potential for each of the fans as defined according to concrete operating states for which each fan is brought to a power optimized state; c) comparing the current operating state determined in the aforementioned step a) with the power optimization potential of the fans from step b), to obtain an optimization recommendation with respect to at least one of the fans, and d) correction of the setpoint value (V.sub.G,setpoint, Δp.sub.G,setpoint) by changing the operating state of the at least one of the fans, depending on which setpoint value is fixedly predetermined, thereby, bringing the at least one of the fans to the power optimized state and thereby increasing an efficiency ηG of the system, wherein in step a), the determination of the current operating state of each of the fans occurs in that at least the volume flow V and the rotation speed n of each fan is determined, and the pressure increase Δpst, the power consumption P and the efficiency ηG are determined as a function of the volume flow and of the rotation speed, which are stored in motor electronics associated with the plurality of fans, and wherein, in the determination of the optimization recommendation for the adjustment of the operating state for the at least one of the fans in step c), includes the fan that makes highest power contribution to air conveyance in the system.

2. The method according to claim 1, characterized in that step d) occurs in such a manner that a plurality of the fans are brought to the power optimized state.

3. The method according to claim 2, characterized in that, the efficiency ηG of the system is increased when one or more of the fans are switched off.

4. The method according to claim 1, characterized in that the efficiency ηG of the system is increased when one or more of the fans are switched off.

5. The method according to claim 1, wherein, determining the optimization potential in step b) includes identification of an optimized volume flow V.sub.opt and an optimized pressure increase Δp.sub.opt for each of the fans.

6. The method according claim 5, wherein, in step c) one of the following occurs: a. the optimization recommendation in the case of a defined volume flow V.sub.G,setpoint to be kept constant consists in carrying out a pressure increase or decrease, depending on whether the optimized pressure increase Δp.sub.opt is greater than or smaller than the determined pressure increase Δpst or b. the optimization recommendation in the case of a defined pressure P.sub.G,setpoint to be kept constant consists in increasing or lowering the volume flow, depending on whether the optimized volume flow V.sub.opt is greater than or smaller than the determined volume flow V.

7. The method according to claim 6, wherein steps a) through d) are cyclically repeated until the correction in step d) results in either a targeted total efficiency, a total efficiency optimized with respect to the previous cycle, or a targeted total efficiency that is asymptomatically approached, wherein the cyclic repetition of steps a) through d) are halted at the latest after a predefined number of cycles.

8. The method according to claim 1, wherein a measurement of power consumption P of each fan occurs before and after the correction in step d), and it is determined whether a total sum of all the power consumptions P of the fans, measured after the correction in step d), was reduced in comparison to the total sum of all the power consumptions P measured before the correction in step d).

9. The method according to claim 8, wherein if the total sum of all the power consumptions P after the correction in step d) was not reduced, the change in the operating state of the at least one fan that was made in the previously performed optimization step d) is reversed.

10. The method according to claim 9, wherein steps a) through d) are cyclically repeated until the correction in step d) results in either a targeted total efficiency, a total efficiency optimized with respect to the previous cycle, or a targeted total efficiency that is asymptomatically approached, wherein the cyclic repetition of steps a) through d) are halted at the latest after a predefined number of cycles.

11. The method according to claim 8, wherein steps a) through d) are cyclically repeated until the correction in step d) results in either a targeted total efficiency, a total efficiency optimized with respect to the previous cycle, or a targeted total efficiency that is asymptomatically approached, wherein the cyclic repetition of steps a) through d) are halted at the latest after a predefined number of cycles.

12. A control device for carrying out a method of controlling a ventilation system comprising a number n of at least two fans and/or fan groups according to claim 1, wherein the control device comprises the following: a. an acquisition system configured to determine the volume flow of individual fans and all the fans; b. a collector for determining of a power optimization potential V.sub.opt or Δp.sub.st,opt for the respective fans, which can be achieved with constant rotation speed with the rotation speed n; c. a comparator for comparing the determined operating states with the power optimization potential states determined by the collector in order to obtain a specific optimization recommendation therefrom; and d. a central ventilation station configured to adjust a respective variable setpoint value by changing the operating state of at least one fan depending on which setpoint value in the system is fixedly predetermined, in order to bring at least one of the fans to a power optimized or optimal operating point and thereby increase the efficiency ηG of the ventilation system.

13. The control device according to claim 12, characterized in that step d) occurs in such a manner that a plurality of the fans are brought to a power optimized state.

14. The control device according to claim 12, characterized in that the efficiency ηG of the ventilation system is increased when one or more of the fans are switched off.

15. The control device according to claim 12, wherein, in step c) one of the following occurs: a. the optimization recommendation in the case of a defined volume flow V.sub.G,setpoint to be kept constant consists in carrying out a pressure increase or decrease, depending on whether the optimized pressure increase Δp.sub.opt is greater than or smaller than the determined pressure increase Δpst or b. the optimization recommendation in the case of a defined pressure P.sub.G,setpoint to be kept constant consists in increasing or lowering the volume flow, depending on whether the optimized volume flow V.sub.opt is greater than or smaller than the determined volume flow V.

16. The control device according to claim 12, wherein a measurement of power consumption P of each fan occurs before and after the correction in step d), and it is determined whether a total sum of all the power consumptions P of the fans, measured after the correction in step d), was reduced in comparison to the total sum of all the power consumptions P measured before the correction in step d); wherein if the total sum of all the power consumptions P after the correction in step d) was not reduced, the change in the operating state of the at least one fan that was made in the previously performed optimization step d) is reversed.

17. The control device according to claim 12, wherein steps a) through d) are cyclically repeated until the correction in step d) results in either a targeted total efficiency, a total efficiency optimized with respect to the previous cycle, or a targeted total efficiency that is asymptomatically approached, wherein the cyclic repetition of steps a) through d) are halted at the latest after a predefined number of cycles.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which:

(2) FIG. 1 shows a diagram which shows the correlation of the power consumption P with the volume flow V and the rotation speed n of an exemplary fan;

(3) FIG. 2 shows a diagram which shows the correlation of the pressure increase Δp.sub.st (static pressure) with the volume flow V and the rotation speed n of an exemplary fan;

(4) FIG. 3 shows a diagram which shows the correlation of the efficiency η.sub.st with the volume flow V and the rotation speed n of an exemplary fan;

(5) FIG. 4 shows a diagram which represents the course of the optimal volume flow as a function of the rotation speed of a fan;

(6) FIG. 5 shows a diagram which represents the course of the optimal static pressure Δp.sub.opt as a function of the rotation speed of a fan;

(7) FIG. 6 shows a diagram which represents the course of the optimal efficiency η.sub.opt as a function of the rotation speed of a fan;

(8) FIG. 7 shows a comparison of two states of a fan at a constant volume flow in the system, wherein the static pressure in the system was reduced in order to increase the pressure availability Δp.sub.st for the fan in order to thereby increase the efficiency;

(9) FIG. 8 shows a diagrammatic view of a decentralized fan system with fans as volume flow controller;

(10) FIG. 9 shows an example of variable pressure;

(11) FIG. 10 shows three diagrams of an embodiment example of 6 fans which are connected together in parallel in a fan grid, of which, however, in each case a different number of fans is actively switched on; and

(12) FIG. 11 shows an example of variable volume flow.

(13) The drawings are provided herewith for purely illustrative purposes and are not intended to limit the scope of the present invention. In the figures, identical reference numerals refer to identical structural and/or functional features.

DETAILED DESCRIPTION

(14) The following description is merely exemplary in nature and is in no way intended to limit the present disclosure or its application or uses. It should be understood that throughout the description, corresponding reference numerals indicate like or corresponding parts and features.

(15) According to an embodiment example of the method according to the invention, for the determining of the operating state, reference is made to FIGS. 1 to 3. For this purpose, in FIGS. 1 to 3, a diagram is shown which in each case shows the correlation between the power consumption P or the pressure increase Δpst (static pressure) and the efficiency ηst as well as the volume flow V and the rotation speed n of an exemplary fan from the group of the fans. These variables n, V, P, Δpst and ηst represent acquired operating states or values correlated therewith, which are used in the control method.

(16) In FIGS. 4 to 6 shows the optimal points of the volume flow V.sub.opt and the pressure increase Δp.sub.opt and the correspondingly associated efficiency η.sub.opt and the pressure increase Δp.sub.opt which can be achieved at constant rotation speed with the measured rotation speed. For this purpose, FIG. 4 shows a diagram which shows the optimization potential of the volume flow V.sub.opt in m.sup.3/h as a function of the rotation speed n of a fan in a range from the rotation speed n=0 to approximately n=3200 rotations per minute.

(17) FIG. 5 shows a diagram which represents the optimization potential of the static pressure Δp.sub.opt as a function of the rotation speed n of a fan, and FIG. 6 shows the optimization potential of the efficiency η.sub.opt in % as a function of the rotation speed n of a fan.

(18) FIG. 7 shows a comparison of two states of a fan at constant volume flow in the system, wherein the static pressure in the system was reduced in order to increase the pressure availability Δp.sub.st for the fan and thus increase the efficiency, as shown in the right figure.

(19) In FIG. 8, a diagrammatic view of a decentralized fan system with fans as volume current controller is shown. Shown is a ventilation system consisting of a central ventilation station 10 comprising an air filter 11, a fan 1, two heat registers 13 and a cold register 14 located in between, which are connected via a ventilation channel 15 to a damper 16. From the damper 16, the ventilation channel 15 leads to two ventilation stacks 15a, 15b in which a fan 1 with a damper 16 and an air passage 17 are provided in each case. Furthermore, a collector Δp.sub.sys is provided. The fans 1 are connected by control technology to acquisition means 19, wherein this system is formed, for example, as a volume flow control system, in which the volume flow is variably controlled via the decentralized fans 1 with the described method, in order to adjust the pressure in the system.

(20) Via the central ventilation station 10, the system pressure for the decentralized fans 1 can be set according to an optimization recommendation. This means: Δp.sub.st<Δp.sub.opt: The central ventilation station 10 should reduce the system pressure in the collector Δp.sub.sys so that the individual fans 1 have to overcome more pressure or Δp.sub.st>Δp.sub.opt: The central ventilation station 10 should increase the system pressure in the collector Δp.sub.sys so that the individual fans 1 are relieved and have to generate less pressure.

(21) In another embodiment example, not represented in further detail, for example, 6 fans are connected in parallel operation to form a fan grid for volume flow-variable application.

(22) If the volume flow V is to the left of the optimum, i.e., if the condition V<V.sub.opt is met, then an optimization can be achieved in that participating fans 1 are switched off. In FIG. 8, from top to bottom, the situations are represented in which first 6 fans 1 are working in the fan grid, and then only 5 fans 1, and below only 4 fans 1, wherein the other fans 1 have then been switched off.

(23) In the sense of the optimization recommendation, the fans 1 remaining in the fan grid have to deliver in each case more volume at identical system pressure (in this example 500 Pa), but therefore they work optimally overall, so that a higher efficiency is reached in the system.

(24) At the operating point with a volume flow V of 10,000 m.sup.3/h at 500 Pa, the individual fans work in each case optimally. An operating point with a volume flow V of 40,000 m.sup.3/h at 500 Pa can selectively be achieved with 6 or 5 or 4 fans in parallel operation. This results in the following data: total efficiency with respect to the static pressure increase with 6 fans η.sub.st=56%, power 100% (P=9846 W); total efficiency with respect to the static pressure increase with 5 active fans η.sub.st=59%, power reduction −5% (P=9374 W) and total efficiency with respect to the static pressure increase with 4 active fans η.sub.st=62%, power reduction −10% (P=8988 W).

(25) In FIGS. 9 and 11, the correlations between volume flow V.sub.sys and pressure Δp.sub.sys for the examples of variable pressure at constant volume flow or variable volume flow at constant pressure are represented for 6 or 4 fans in each case.

(26) Such a solution represents an exemplary implementation of the invention, wherein the control method for the fans is based on the fact that multiple fans of the fan grid know their operating state as well as their respective power optimization potential. On this basis, the distribution of the air quantities to the individual fans at constant system pressure occurs so that an operation of only four fans leads to an optimized efficiency of η.sub.st=62%.

(27) Within this specification, embodiments have been described in a way which enables a clear and concise specification to be written, but it is intended and will be appreciated that embodiments may be variously combined or separated without parting from the invention. For example, it will be appreciated that all preferred features described herein are applicable to all aspects of the invention described herein.

(28) While the above description constitutes the preferred embodiments of the present invention, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope and fair meaning of the accompanying claims.