Method for operating a coriolis mass flowmeter and corresponding coriolis mass flowmeter

Patent metadata

Field	Value
Publication number	US-10378942-B2
Application number	US-201715410269-A
Country	US
Kind code	B2
Filing date	Jan 19, 2017
Priority date	Jan 20, 2016
Publication date	Aug 13, 2019
Grant date	Aug 13, 2019

Abstract

A method for operating a Coriolis mass flowmeter having at least one controller, at least one electric actuating device, at least one electromagnetic driving mechanism with a drive coil as oscillation generator, at least one measuring tube and at least one oscillation sensor involves excited oscillation of the measuring tube being detected by the oscillation sensor and emitted as at least one output signal and the electric actuating device causing the electromagnetic driving mechanism to produce oscillation of the measuring tube largely in resonance by the output signal of the oscillation sensor, the drive voltage at the drive coil, and phasing of the drive current in relation to the phasing of the output signal of the oscillation sensor being determined and a new target phasing for the drive voltage derived from the determinations and supplied to the controller to generate a drive voltage with the new target phasing.

First claim

What is claimed is:

1. Method for operating a Coriolis mass flowmeter having at least one controller, at least one electric actuating device, at least one electromagnetic driving mechanism with a drive coil as an oscillation generator, at least one measuring tube and at least one oscillation sensor, the method comprising the following steps:
generating a controller output signal u c for controlling the at least one electric actuating device with the at least one controller,
providing an electric excitation signal u dr for exciting the at least one electromagnetic drive mechanism with the at least one electric actuating device,
exciting the at least one measuring tube to oscillation in at least one eigenform with the at least one electromagnetic drive mechanism,
detecting excited oscillation of the measuring tube with the at least one oscillation sensor and emitting the detected oscillation as at least one output signal u s ,
applying a drive voltage u dr and a drive current i dr to the drive coil of the at least one electromagnetic driving mechanism with the at least one electric actuating device so that the oscillation of the measuring tube occurs largely in resonance,
determining a target specification u dr,soll for the drive voltage u dr , and thus also a target phasing φ dr,soll of the drive voltage u dr , by defining a zero phasing (φ s =0) of the output signal u s and
determining the target specification u dr,soll for the drive voltage u dr using the equation
u dr,soll =e −jφ idr ( u dr −K B ·u s )+ k B ·u s

wherein k B is a real number mutual induction factor,
determining the output signal u s of the at least one oscillation sensor,
determining the drive voltage u dr at the drive coil,
determining phasing φ idr of the drive current i dr in relation to phasing φ s of the output signal u s of the oscillation sensor, and
deriving a new target phasing φ dr,soll for the drive voltage u dr based on the determinations and supplying the new target phasing to the at least one controller,
using the at least one controller for generating a drive voltage u dr with the determined new target phasing (φ dr,soll ) via the electric actuating device so that the at least one controller produces resonance operation of the flowmeter.

2. The method for operating a Coriolis mass flowmeter according to claim 1 , wherein the impedance Z S of the drive coil is determined outside of resonance operation, wherein a quotient of the drive voltage and an adjusting drive current i dr is calculated, and the mutual induction factor k B is determined without taking the mutual induction voltage u B at the drive coil into account using measuring equation for a measuring network of the output of the electric actuating device and the electromagnetic driving mechanism with the drive coil.

3. The method for operating a Coriolis mass flowmeter according to claim 2 , characterized in that, in order to determine the mutual induction factor k B , the following relation is used with the impedance Z S of the drive coil, the drive current i dr and the output signal u s of the oscillation sensor

k
B

=

u
_

dr

-

Z
_

S

·

i
_

dr

u
_

S

.

4. The method for operating a Coriolis mass flowmeter according to claim 1 , wherein a control mode in resonance is temporarily interrupted, wherein the controller is provided another phasing specification as a target value for the phasing of the drive current i dr corresponds to a phase difference of +−45° as compared to the phasing of the output signal u s .

5. A Coriolis mass flowmeter, comprising:
at least one controller,
at least one electric actuating device,
at least one electromagnetic driving mechanism with a drive coil as oscillation generator,
at least one measuring tube, and
at least one oscillation sensor,
wherein the at least one controller is adapted for generating a controller output signal u c for controlling the at least one electric actuating device,
wherein the at least one electric actuating device is adapted to provide an electric excitation signal u dr for exciting the at least one electromagnetic drive mechanism,
wherein the at least one electromagnetic drive mechanism is adapted for exciting the measuring tube to oscillation in at least one eigenform,
wherein the at least one oscillation sensor is adapted for detecting excited oscillation of the measuring tube and emitting as at least one output signal u s based thereon,
wherein the at least one electric actuating device is adapted to apply a drive voltage u dr and a drive current i dr to the drive coil of the at least one electromagnetic driving mechanism so that the oscillation of the measuring tube occurs largely in resonance,
wherein a target specification u dr,soll for the drive voltage u dr , and thus also a target phasing φ dr,soll of the drive voltage u dr , is determined by defining a zero phasing (φ s =0) of the output signal u s and
wherein the target specification u dr,soll for the drive voltage u dr is determined using the equation
u dr,soll =e −jφ idr ( u dr −K B ·u s )+ k B ·u s

wherein a mutual induction factor k B is a real number,
further comprising means for determining the output signal u s of the at least one oscillation sensor, the drive voltage u dr at the drive coil, phasing φ idr of the drive current i dr in relation to phasing φ s of the output signal u s of the oscillation sensor, and for setting a new target phasing φ dr,soll for the drive voltage u dr derived from the determinations and for supplying the new target phasing φ dr,soll to the controller, and wherein the controller is adapted for generating a drive voltage u dr with the new target phasing φ dr,soll via the electric actuating device by which operation in resonance is achieved.

Assignees

• Krohne Messtechnik Gmbh

Inventors

• Kunze Johannes

Classifications

• G01F1/8431 Primary

  electronic circuits · CPC title

• G01F1/8413 Primary

  means for influencing the flowmeter's motional or vibrational behaviour, e.g., conduit support or fixing means, or conduit attachments · CPC title

• G01F1/8436

  signal processing · CPC title

• G01F1/849 Primary

  having straight measuring conduits · CPC title