Current selection circuitry for magnetic flowmeter
First Claim
1. A magnetic flowmeter for measuring a fluid flow, comprising:
- a flowtube assembly receiving the flow having a coil with first and second coil wires for receiving a coil current producing a magnetic field generating an EMF in the field representative of flow;
EMF sensing means for sensing the EMF and generating an output indicating flow;
a power supply coupled to the coil wires providing the coil current to the coil in response to a feedback signal;
a sensor generating an output related to frequency response of the coil and the coil current and responsively providing a sensor output; and
control circuitry for providing the feedback signal to the power supply based upon the sensor output.
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Accused Products
Abstract
A magnetic flowmeter system provides a volumetric flow rate output and includes flowmeter electronics for coupling to a flowtube assembly. The flowtube assembly includes a coil which receives a magnetic field producing coil current from a supply circuit in the flowmeter electronics. The coil produces a magnetic field which generates an EMF in the field representative of flow. An EMF sensor senses the generated EMF and provides an output indicating flow. The supply circuitry is coupled to coil wires of the coil and is responsive to a control signal. A sensor senses the frequency response of the coil and generates a sensor output. A comparator compares the sensor output with a predetermined level and provides a comparator output based upon the comparison. Control circuitry provides the magnitude control signal to the current based upon the comparison.
26 Citations
17 Claims
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1. A magnetic flowmeter for measuring a fluid flow, comprising:
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a flowtube assembly receiving the flow having a coil with first and second coil wires for receiving a coil current producing a magnetic field generating an EMF in the field representative of flow; EMF sensing means for sensing the EMF and generating an output indicating flow; a power supply coupled to the coil wires providing the coil current to the coil in response to a feedback signal; a sensor generating an output related to frequency response of the coil and the coil current and responsively providing a sensor output; and control circuitry for providing the feedback signal to the power supply based upon the sensor output. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for selecting drive current for a flowtube in a magnetic flowmeter, comprising the steps of:
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driving the flowtube with an alternating signal; sensing current flowing through the flowtube; determining frequency response of the flowtube to the alternating signal based upon the sensed current; and setting the drive current for the flowtube based upon the frequency response. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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Specification