Method for operating a resonance-measuring system and a resonance-measuring system
A method for operating a resonance-measuring system, in particular, a Coriolis mass flowmeter, having at least one oscillation element, at least one oscillation driver and at least one oscillation sensor, the oscillation element being excited to oscillation in at least one control using at least one control loop by at least one oscillation driver being excited by at least one excitation signal and the excited oscillations of the oscillation element being detected by the oscillation sensors as at least one response signal. At least one set variable of the closed loop is varied in a pre-determined manner and by evaluating at least one resulting excitation signal and/or at least one resulting response signal with the help of a mathematical model of the resonance-measuring system, at least one parameter of the excited eigenform is selectively identified.
1. Method for operating a resonance-measuring system wherein the resonance-measuring system includes at least one oscillation element, at least one oscillation driver and at least one oscillation sensor, comprising the steps of:
exciting the oscillation element to oscillation in at least one eigenform from at least one control in at least one control loop by at least one oscillation driver excited by at least one excitation signal F i (t)
detecting the excited oscillations of the oscillation element with the oscillation sensors as at least one response signal y i (t),
varying at least one set variable of the closed loop in a pre-determined manner, and
selectively identifying at least one parameter of the excited eigenform by evaluating at least one of at least one resulting excitation signal F i (t) and at least one resulting response signal y i (t) with the help of a mathematical model of the resonance-measuring system.
2. Method according to claim 1 , wherein the set variable is constantly varied during normal operation and wherein identification of the parameters of the excited eigenform is constantly carried out.
3. Method according to claim 1 , wherein the control comprises a multi-variable loop for every excited eigenform.
4. Method according to claim 3 , wherein the excitation signal F i (t) is adjusted in an amplitude loop so that the amplitude A i of the oscillation of the oscillation element is essentially constant.
5. Method according to claim 1 , wherein the phase φ i between the excitation signal F i (t) and the response signal y i (t) of the respective eigenform is used as a set variable.
6. Method according to claim 5 , wherein the set phase φ i of each eigenform is achieved by variation of the frequency of the excited oscillation.
7. Method according to claim 1 , wherein the selective identification of each parameter of the excited eigenform occurs in a steadily oscillating state.
8. Method according to claim 1 , wherein an analytical-mechanical model is used for each excited eigenform as a mathematical model for the resonance-measuring system.
9. Method according to claim 8 , wherein damping is selectively identified as the first parameter.
10. Method according to claim 1 , wherein derived parameters are identified from the selectively identified parameters.
11. Method according to claim 10 , wherein the eigen angular frequency ω 0i of each eigenform is determined as a derived parameter.
12. Method according to claim 10 , wherein a quality factor Q i of the excited eigenform is determined as a derived parameter.
13. Method according to claim 10 , wherein an instationarity of the resonance-measuring system is determined as a derived parameter.
14. Method according claim 1 , wherein the resonance-measuring system is a Coriolis mass flowmeter, at least one of a Coriolis coupling k Cor12 and an acceleration coupling k b12 of the first excited eigenform to the second excited eigenform are identified.
15. Method according to claim 1 , wherein derived parameters are identified from the selectively identified parameters and wherein the resonance-measuring system is a Coriolis mass flowmeter, and the derived parameters are at least one of mass flow, density, pressure, viscosity, multi-phase flow.
16. Resonance-measuring system, comprising
an oscillation element
at least one measuring tube with a flowing medium as an oscillation element,
at least one oscillation driver,
at least one oscillation sensor,
wherein the oscillation element is excitable to oscillation in at least one eigenform from at least one control in at least one control loop by the at least one oscillation driver excited by at least one excitation signal F i (t) and the oscillation sensors being adapted to detect the excited oscillations of the oscillation element as at least one response signal y i (t), and
an evaluation means for selectively identifying at least one parameter of the excited eigenform by evaluating at least one of at least one resulting excitation signal F i (t) and at least one resulting response signal y i (t) using a mathematical model of the resonance-measuring system.