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

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 uc for controlling the at least one electric actuating device with the at least one controller,
• providing an electric excitation signal udr 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 us,
• applying a drive voltage udr and a drive current idr 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 udr,soll for the drive voltage udr, and thus also a target phasing φdr,soll of the drive voltage udr, by defining a zero phasing (φs=0) of the output signal us and
• determining the target specification udr,soll for the drive voltage udr using the equation
• udr,soll=e−jφidr(udr−KB·us)+kB·us
• wherein kB is a real number mutual induction factor,
• determining the output signal us of the at least one oscillation sensor,
• determining the drive voltage udr at the drive coil,
• determining phasing φidr of the drive current idr in relation to phasing φs of the output signal us of the oscillation sensor, and
• deriving a new target phasing φdr,soll for the drive voltage udr 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 udr with the determined new target phasing (φdr,soll) via the electric actuating device so that the at least one controller produces resonance operation of the flowmeter.