Method for detecting the flow rate of a centrifugal pump
Method for detecting the flow rate of a centrifugal pump
 CN 104,603,583 B
 Filed: 08/01/2013
 Issued: 01/29/2021
 Est. Priority Date: 08/07/2012
 Status: Active Grant
First Claim
1. A method for detecting the flow of a centrifugal pump, wherein the flow is determined from the rotational speed of the pump, a hydraulic variable of the pump and an electrical or mechanical variable of a drive motor of the pump, characterized in that a variable relating to the flow is determined by means of a mathematical relationship of terms of a formula describing the physical relationship of the pump and the drive motor, one term of the formula containing the rotational speed of the pump and the hydraulic variable of the pump and the other term containing the electrical or mechanical variable of the drive motor of the pump and the rotational speed of the pump, wherein the flow is determined from the flow and a functional relationship with a dependent variable,and wherein the dependent variable is a variable Y, which is determined by the formula:
Chinese PRB Reexamination
Abstract
A method for detecting the flow rate of a centrifugal pump, wherein the rotational speed of the pump or of a motor driving the pump, a hydraulic variable of the pump, usually the delivery pressure, and an electrical variable, for example the electrical power, driving the motor are determined and the flow rate is determined from these variables. For this purpose, the flowrelated variables are determined by means of a mathematical relationship of terms of a formula describing the physical relationship of the pump and the drive motor, wherein one term contains the rotational speed of the pump and the hydraulic variables of the pump and the other term contains the electrical or mechanical variables of the drive motor of the pump and the rotational speed of the pump. And determining the flow according to the functional relation between the flow and the dependent variable.
16 Claims

1. A method for detecting the flow of a centrifugal pump, wherein the flow is determined from the rotational speed of the pump, a hydraulic variable of the pump and an electrical or mechanical variable of a drive motor of the pump, characterized in that a variable relating to the flow is determined by means of a mathematical relationship of terms of a formula describing the physical relationship of the pump and the drive motor, one term of the formula containing the rotational speed of the pump and the hydraulic variable of the pump and the other term containing the electrical or mechanical variable of the drive motor of the pump and the rotational speed of the pump, wherein the flow is determined from the flow and a functional relationship with a dependent variable,
and wherein the dependent variable is a variable Y, which is determined by the formula:

2. The method of claim 1, wherein the hydraulic variable is a pressure variable.

3. The method of claim 2, wherein the pressure variable is a pressure at an outlet of the pump or a pressure differential between an inlet and an outlet of the pump.

4. The method of claim 1, wherein the electrical variable is a powerrelated variable.

5. Method according to claim 4, characterized in that the powerrelated variable is the absorbed power P of the drive motor.

6. The method of claim 1, wherein the mechanical variable is a torque of a motor.

7. The method of claim 1, wherein the mathematical relationship is an addition or subtraction of at least two terms.

8. A method according to any one of claims 1 to 7, wherein the mathematical relationship comprises one or more other terms that are constant or related to rotational speed.

9. The method according to any one of claims 1 to 7, characterized in that the terms, the number of terms and their mathematical relations are chosen as:
 the flow rate is made to constitute a monotonic function over the operating region of the pump.

10. The method according to any one of claims 1 to 7, characterized in that the flow rate is determined from a dependent variable y, wherein,

11. The method according to any one of claims 1 to 7, characterized in that the signal representing the flow is filtered with a lowpass filter.

12. Method according to any one of claims 1 to 7, characterized in that the dependent variable y determined according to the method is compared with a corresponding dependent variable y determined by means of model calculations_{est}Compared and passed through the assumed flow Q_{est}Until the error size yy_{est}So small that the assumed flow Q is_{est}Corresponding to the actual flow rate Q.

13. The method according to claim 12, characterized in that the rotational speed constitutes an input value in the model calculation.

14. The method of claim 12, wherein the error size is yy_{est}Over time, the added values represent the flow rate Q.

15. A centrifugal pump having an electric drive motor, a pressure or differential pressure sensor and an electronic controller, characterized in that the electronic controller is configured for carrying out the method according to any one of claims 1 to 14.

16. The centrifugal pump of claim 15, wherein the electronic controller has an observerbased regulator.
Specification(s)