Method for setting a constant magnetic field strength of a magnetic field and a flowmeter
원문보기
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
G01F-001/58
G01F-001/00
G01F-001/60
출원번호
US-0282241
(2016-09-30)
등록번호
US-9983035
(2018-05-29)
우선권정보
DE-10 2015 116 771 (2015-10-02)
발명자
/ 주소
Dabrowski, Markus
Florin, Wilhelm
출원인 / 주소
KROHNE Messtechnik GmbH
대리인 / 주소
Safran, David S.
인용정보
피인용 횟수 :
1인용 특허 :
5
초록▼
A method for setting a constant magnetic field strength of a magnetic field within a commutation interval using a magnetic-inductive flowmeter having a current controller with which time for setting the constant magnetic field strength of a magnetic field is relatively shorter. Additionally, a first
A method for setting a constant magnetic field strength of a magnetic field within a commutation interval using a magnetic-inductive flowmeter having a current controller with which time for setting the constant magnetic field strength of a magnetic field is relatively shorter. Additionally, a first interval having a starting point in time and an ending point in time and a second interval having a starting point in time and an ending point in time are arranged within a commutation interval. A first setpoint current curve for the first interval differs by a difference current curve to effectuate a higher rate of change. A second setpoint current curve is assigned to the constant setpoint current. The current controller is fed the first and second setpoint current curves.
대표청구항▼
1. A method for setting a constant magnetic field strength of a magnetic field within a commutation interval, the method comprising: using a magnetic-inductive flowmeter having a measuring tube and an electromagnet to generate a magnetic field,wherein the electromagnet has a current controller and a
1. A method for setting a constant magnetic field strength of a magnetic field within a commutation interval, the method comprising: using a magnetic-inductive flowmeter having a measuring tube and an electromagnet to generate a magnetic field,wherein the electromagnet has a current controller and a coil arrangement, the current controller generating a coil current and the generated coil current effectuating the magnetic field in the coil arrangement,the coil current is commutated at the commutation interval,wherein when a constant setpoint current of the current controller is preset, the electromagnet generates the constant magnetic field strength in steady state,a first interval has a first starting point in time and a first ending point in time and a second interval has a second starting point in time and a second ending point in time, the first and second starting points and the first and second ending points are arranged within the commutation interval, anda first setpoint current curve is defined for the first interval,wherein the first setpoint current curve differs by a difference current curve from the constant setpoint current such that the difference current curve, with reference to the constant setpoint current, effectuates a higher rate of change of a magnetic field strength towards the constant magnetic field strength,a second setpoint current curve is defined for the second interval, in that the constant setpoint current is assigned to the second setpoint current curve, andthe current controller is fed the first setpoint current curve in the first interval and the second setpoint current curve in the second interval. 2. The method according to claim 1, wherein the current controller is overdriven by the first setpoint current curve at a beginning of the first interval. 3. The method according to claim 1, wherein the first interval is shorter than a settling time constant of the magnetic field. 4. The method according to claim 1, wherein the first setpoint current curve is constant. 5. The method according to claim 1, wherein the coil current is measured such that a point in time is determined in which the measured coil current has reached the first setpoint current curve or the second setpoint current curve, andthe determined point in time is adopted as the first ending point in time of the first interval and as the second starting point in time of the second interval. 6. The method according to claim 1, wherein the first setpoint current curve is set so a magnitude of the difference current curve does not exceed 15% of a magnitude of the constant setpoint current. 7. The method according to claim 1, wherein the magnetic field strength, an induction voltage induced in a medium by the magnetic field by a flow of the medium in the measuring tube, the coil current, a coil voltage generated from the coil current in the coil arrangement measured as an indicator quantity, the first interval, and the first setpoint current curve are defined using the indicator quantity. 8. The method according to claim 7, wherein the indicator quantity is measured in a third interval within the second interval. 9. The method according to claim 7, wherein a first measured value and a second measured value of the indicator quantity are measured to form an evaluation quantity,a mean value is formed and subtracted from the first measured value, andthe first interval and/or the first setpoint current curve is/are defined using the evaluation quantity. 10. The method according to claim 9, wherein a trend quantity is determined from the evaluation quantity,a change of the evaluation quantity is determined from the second interval of the commutation interval and a second interval of at least one additional commutation interval, andthe first interval and/or the first setpoint current curve is/are defined using the trend quantity. 11. The method according to claim 1, wherein a temperature at the magnetic-inductive flowmeter is measured and that the measured temperature is used in determining the first interval and/or the first setpoint current curve. 12. The method according to claim 11, wherein a temperature of the coil arrangement and/or of the medium is also measured. 13. A magnetic-inductive flowmeter, comprising: a measuring tube;an electromagnet for generating a magnetic field; anda control unit,wherein the electromagnet comprises a current controller and a coil arrangement, the current controller generating a coil current and the generated coil current effectuates the magnetic field in the coil arrangement,the electromagnet commutates the coil current at a commutation interval,wherein, when a constant setpoint current of the current controller is preset and the electromagnet generates a constant magnetic field strength in a steady state,the control unit sets the constant magnetic field strength of the magnetic field within the commutation interval,the control unit arranges a first interval having a first starting point in time and a first ending point in time and a second interval having a second starting point in time and a second ending point in time within the commutation interval, andthe control unit defines a first setpoint current curve for the first interval, wherein the first setpoint current curve differs by a difference current curve from the constant setpoint current such that the difference current curve with reference to the constant setpoint current effectuates a higher rate of change of the magnetic field strength towards the constant magnetic field strength,the control unit defines a second setpoint current curve for the second interval in that the constant setpoint current is assigned to the second setpoint current curve, andthe control unit is fed the first setpoint current curve in the first interval and the second setpoint current curve in the second interval. 14. The magnetic-inductive flowmeter according to claim 13, wherein the electromagnet comprises a commutation unit which commutates the coil current. 15. A magnetic-inductive flowmeter comprising a control unit configured to perform the method according to claim 1.
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