CN1096604C - Method of regulating coil current of electromagnetic flow sensors - Google Patents
Method of regulating coil current of electromagnetic flow sensors Download PDFInfo
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- CN1096604C CN1096604C CN99110143A CN99110143A CN1096604C CN 1096604 C CN1096604 C CN 1096604C CN 99110143 A CN99110143 A CN 99110143A CN 99110143 A CN99110143 A CN 99110143A CN 1096604 C CN1096604 C CN 1096604C
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Abstract
This method completely eliminates the detrimental effect of eddy currents on the rise time of the magnetic field, so that it reaches its constant value already when the current assumes its maximum. In each current half-cycle, an initial voltage during a rise time of the current which is higher than a final voltage during a second subcycle is fed to the coil. The voltage drop across the resistor is used to maintain the final voltage constant for forming the first and second final current values, and to compensate for the effect of the eddy currents. To do so, in each half-cycle the voltage drop across the resistor after the maximum of the coil current until the attainment of the final current is sampled at least three times in succession to form a correction quantity for the voltage across the H or T network in the next half-cycle.
Description
The present invention relates to a kind of method that is used to regulate the coil current of electromagnetic flow sensors.
The coil current of electromagnetic flow sensors flows in coil device, and coil device has inductance L, and constitutes the parts of the magnetic system that contains cored and pole element.In first half cycle, coil current is positive, and has the first constant end value, and in second half cycle, as the result of switching, electric current is born, and has the second constant end value that amplitude equals first end value.
For example, coil device is a coil, if the electromagnetic current detecting device is as the stream probe, referring to US3529591, perhaps be made of two half coils, they are set at the relative position of diameter on the measuring tube, flow through its volumetric flow rate by measuring tube and want measured fluid.
United States Patent (USP) 4410926 has disclosed a kind of circuit arrangement that is used to produce this coil current.This device comprises:
-being the bridge circuit of H latticed form, it has
--first brachium pontis that constitutes by the controlled current path of the first transistor,
--second brachium pontis that constitutes by the controlled current path of transistor seconds,
--the 3rd brachium pontis that constitutes by the 3rd transistorized controlled current path, and
--the 4th brachium pontis that constitutes by the 4th transistorized controlled current path,
--be positioned at the transistor seconds that links to each other with the first transistor, with and the 4th transistor that links to each other of the 3rd transistor between the first bridge diagonal line, and
--be positioned at the 3rd transistor that links to each other with the first transistor, with and the 4th transistor that links to each other of transistor seconds between the second bridge diagonal line, wherein
---or the first and the 4th transistor,
---or the conducting simultaneously of the second and the 3rd transistor, alternately make its direction reverse so as to making coil current;
-above-mentioned coil device is positioned on the first bridge diagonal line;
-controlled current source has an output that is used for its electric current;
-resistance, its
--have an end of ground connection,
--so link to each other, make to form series circuit with the H network, and
--passed through by coil current;
-being interted at the output of current source and the diode between the series circuit, the forward of this diode equals the sense of current of current source; And
-and the electric capacity of series circuit parallel connection be the capacitor of C, this capacitor and above-mentioned inductance L form resonant circuit, its effect is, coil current each oppositely after,
--the resonance that voltage takes place at H network two ends rises, and
--between the rising stage of the coil current of the beginning of each above-mentioned half cycle, and do not have resonant circuit to compare, coil current has steeper forward position.
United States Patent (USP) 4410926 has also disclosed a kind of circuit arrangement that is used to produce coil current, and it comprises the T network, comprising:
-resistance, its
--have an end of ground connection, and so link to each other, make to form the series circuit that is passed through by coil current with coil device,
--first switching transistor, it has first end of its controlled current path that links to each other with second end of series circuit, and having second end of exporting its controlled current path that links to each other with first voltage of controlled current source, its first voltage output provides the positive voltage that is added on the series circuit two ends, and
--the second switch transistor, it has first end of its controlled current path that links to each other with second end of series circuit, and having second end of exporting its controlled current path that links to each other with second voltage of controlled current source, its second voltage output determines to be added on the negative voltage at series circuit two ends;
-be connected the-switching transistor second output and ground between electric capacity be C
1First capacitor; And
-be connected second switch transistorized second output and ground between electric capacity be C
2Second capacitor,
--described first and second capacitors and above-mentioned inductance L form resonant circuit, and its effect is, coil current each oppositely after,
--the resonance that voltage takes place at T network two ends rises, and
--between the rising stage of the coil current of the beginning of each above-mentioned half cycle, and do not have resonant circuit to compare, coil current has steeper forward position.
United States Patent (USP) 4204240 has disclosed a kind of circuit arrangement with voltage source, be used to produce the coil current of electromagnetic flow sensors, it provides a voltage, during the rise time of coil current, this voltage has an initial voltage value-as first subcycle-its final magnitude of voltage during greater than second subcycle of the remainder of representing half cycle at every half cycle.
The iron core and the pole element of magnetic system are generally made by soft magnetic material, but also describe the magnetic system with ferromagnetic core.
In two types magnetic system, the conversion of coil current and the inductive loop in magnetic system that rises, eddy current stops magnetic field accurately to follow the rising of coil current as the situation that does not have iron core and pole element.In contrast, the rising in magnetic field is delayed and is flattened with respect to the rising of coil current.Although above-mentioned resonance step-up, also this adverse effect of eddy generation when having resonance step-up.
The influence of eddy current can illustrate that in equivalent circuit diagram, (pure) inductance L is by the shunt of eddy current source with an equivalent circuit diagram, and the electric current in eddy current source adds the electric current in (pure) inductance L, forms total electric current, and this electric current also flows through resistance.Thereby the voltage drop at the resistance two ends is measuring of total coil current, rather than the measuring of (pure) coil current.Yet for the holding coil electric current is a constant, this is necessary.
In United States Patent (USP) 4784000, the solution of common problem hereto has been described in Fig. 6.Yet its supposition is, under non-controlled condition, coil current is not constant between each total semiperiod, and coil current is constant scope under controlled condition in double sampling takes place.Yet the double sampling operation in this scope has been proved to be not enough.
The present invention is used for providing a kind of improved solution to this common problem, therefore, the present invention aims to provide a kind of eddy current of eliminating fully for the rising in magnetic field and the method for the deleterious effect of rise time, makes that magnetic field reaches its constant end value when coil current is in its maximal value.
For realizing purpose of the present invention, first modification of the present invention provides a kind of method that is used for being adjusted in the mobile coil current of coil device, described coil device:
-formation is comprised in the magnetic flow detecting device and the parts of the magnetic system in magnetic field is provided,
-it comprises iron core and pole element, and
-have an inductance L,
-be positive at the described coil current of first half cycle, and have the first constant ultimate current value, bear at the described coil current of second half cycle in described cycle, and have the second constant ultimate current value that amplitude and the first ultimate current value equate; And
-described coil current is produced by a kind of circuit arrangement, comprising:
--be the bridge circuit of H latticed form, it has
First brachium pontis that---by the controlled current path of the first transistor constitutes,
Second brachium pontis that---by the controlled current path of transistor seconds constitutes,
The 3rd brachium pontis that---by the 3rd transistorized controlled current path constitutes, and
The 4th brachium pontis that---by the 4th transistorized controlled current path constitutes,
The transistor seconds that---be positioned at links to each other with the first transistor, with and the 4th transistor that links to each other of the 3rd transistor between the first bridge diagonal line, and
The 3rd transistor that---be positioned at links to each other with the first transistor, with and the 4th transistor that links to each other of transistor seconds between the second bridge diagonal line, wherein
----be the first and the 4th transistor perhaps,
----perhaps the second and the 3rd transistor conducting simultaneously;
--above-mentioned coil device is positioned on the first bridge diagonal line;
--so be connected the feasible resistance that forms series circuit with the H network, its first end ground connection, and wherein pass through coil current; And
--controlled voltage source, its
Voltage output of---have, and
The voltage that---determine produces at the series circuit two ends;
----described voltage has an initial voltage value-as first subcycle-its final magnitude of voltage during greater than second subcycle of the remainder of representing half cycle during the rise time of every half cycle at coil current;
Described method is used the voltage drop at resistance two ends,
-on the one hand, be used to keep the constant final magnitude of voltage that is used to form the first and second ultimate current values, and
-on the other hand, be used for the influence of compensation of eddy currents, described eddy current is responded between the rising stage at coil current in iron core and/or pole element, and its forward position that makes described magnetic field postpones with respect to the forward position of coil current, described delay be by
--in every half cycle, influence the rise time of coil current and the amplitude of final magnitude of voltage by this way, make after coil current reaches maximum, coil current no longer rises, thereby make magnetic field will reach constant end value, the constant end value of this end value and the coil current after coil current reaches maximal value is corresponding
--after the maximal value of coil current, between the semiperiod that obtains the ultimate current value, the waveform of the voltage drop at resistance two ends is sampled 3 times at least continuously, thereby forms the correcting value of the H network both end voltage of next half cycle.
For achieving the above object, second remodeling of the present invention is, provides a kind of method that is used for the coil current of regulating winding device, wherein said coil device
-be formed in the parts of the magnetic system that comprises in the electromagnetic flow sensors, and produce magnetic field,
-comprise iron core and pole element, and
-have an inductance L,
-at first half cycle of one-period, described coil current is positive, and have the first constant ultimate current value, and second half cycle in the described cycle, described coil current is born, and has the second constant ultimate current value, and its amplitude and the first ultimate current value equate; And
-described coil current is produced by a circuit arrangement, and described circuit arrangement comprises:
--controlled voltage source, it has first voltage output end and second voltage output end, and
--T-network, it comprises:
---resistance, it so links to each other with coil device, makes to form series circuit, its first end ground connection, and wherein by coil current,
---the first switching transistor, it has first end of its controlled current path that links to each other with second end of series circuit, and having second end of exporting its controlled current path that links to each other with first voltage of controlled current source, the output of first voltage provides a positive voltage on described series circuit, and
---second switch transistor, it has first end of its controlled current path that links to each other with second end of series circuit, and having second end of exporting its controlled current path that links to each other with second voltage of controlled current source, the output of second voltage provides a negative voltage on described series circuit
----described generating positive and negative voltage has positive initial voltage value and negative initial voltage value respectively in every half cycle, at coil current between the rising stage-as first subcycle-it is respectively greater than at the positive final magnitude of voltage as second subcycle of the remainder of half cycle, and less than the negative final magnitude of voltage during described second subcycle; Described method is used described ohmically voltage drop,
-on the one hand, be used to make described positive and negative final magnitude of voltage to keep constant, be used for forming respectively the first and second ultimate current values, and
-on the other hand, being used for compensating the influence of the eddy current of responding at iron core and pole element between the rising stage at coil current, the forward position that described eddy current makes magnetic field is delayed with respect to the forward position of coil current,
--in each half cycle, influence the rise time of coil current and the amplitude of positive and negative final magnitude of voltage by this way, make coil current just no longer rise after reaching maximal value, thereby make magnetic field will reach constant end value, it is corresponding to the constant end value of the coil current that has existed when coil current reaches maximal value
--after the maximal value of coil current, reach between the semiperiod of ultimate current value, the waveform of the voltage drop at resistance two ends is sampled 3 times at least continuously, thereby forms the correcting value of the T network both end voltage of next half cycle.
According to the further improvement of first remodeling of the present invention,
First end of-resistance and the voltage output end of voltage source link to each other,
Second end of-resistance links to each other by first and second transistorized tie point of a diode and H network, and the forward of described diode equals the direction of coil current, while the second and the 4th transistorized tie point ground connection, and
-H network is the capacitor bypass of C by electric capacity,
--described capacitor and inductance L form resonant circuit, and its effect is
The voltage generation resonance at---make H network two ends raises, and
During---thereon rises, and do not have resonant circuit to compare, coil current has steep front.
According to the further improvement of second remodeling of the present invention,
-coil device ground connection;
-resistance is connected between the tie point and coil device of first and second switching transistor;
Second end of-the first switching transistor
--link to each other by the K-A path of first diode and first voltage output of controlled voltage source, and
--by electric capacity is C
1First capacitor grounding; And
Transistorized second end of-second switch
--link to each other by the anode-cathode path of second diode and second voltage output of controlled voltage source, and
--by electric capacity is C
2Second capacitor grounding,
---described first and second capacitors and inductance L form resonant circuit respectively, and its effect is
The voltage generation resonance at---make series circuit two ends raises, and
During---thereon rises, and do not have resonant circuit to compare, coil current has steep front.
The basic design of two kinds of remodeling of the present invention is, use is in previous half cycle, to the variation of the coil current that keeps taking place during the constant ultimate current value, selectively precomputation produces the time variation of the required voltage of coil current and this voltage in every half cycle after the maximal value of coil current.
An advantage of the present invention is, a kind of method is provided first, and this method guarantees that the rising in magnetic field accurately follows the rising of coil current, as in the coil system that does not have iron core and pole element.Thereby, and there is not situation of the present invention to compare, magnetic field is reaching its constant end value in the moment early.
By the explanation of carrying out below in conjunction with accompanying drawing to embodiments of the invention, can be clear that the present invention more, wherein:
Fig. 1 is the circuit theory diagrams with first embodiment of H network;
Fig. 2 is the circuit theory diagrams with second embodiment of H network;
Fig. 3 is the circuit theory diagrams with first embodiment of T network;
Fig. 4 is the circuit theory diagrams with second embodiment of T network;
Fig. 5 a represents the curve of coil current and magnetic induction;
Fig. 5 b represents the waveform of the voltage of voltage source;
Fig. 6 is the program flow diagram that is applied to microprocessor of the present invention;
Fig. 7 a is a process flow diagram, wherein only contains the decision piece, and because the note that wherein comprises, makes it become the self type; And
Fig. 7 b is a similar process flow diagram that will be connected to the some A of Fig. 7 a.
Each bridge circuit is realized as H network 2 among the embodiment that Fig. 1 and Fig. 2 represent.First brachium pontis contains the controlled current path of the first transistor 13, and second brachium pontis contains the controlled current path of transistor seconds 14, and the 3rd brachium pontis contains the controlled current path of the 3rd transistor 15, and the 4th brachium pontis contains the controlled current path of the 4th transistor 16.
Utilize this structure, obtain 4 angle point 2a of H network, 2b, 2c, 2d: transistor 13,14 is by angle point 2c interconnection, and transistor 14,16 is by angle point 2b interconnection, and transistor 15,16 is by angle point 2d interconnection, and transistor 13,15 is interconnected by angle point 2a.
The first bridge diagonal interconnect angle point 2a, 2b, the second bridge diagonal interconnect angle point 2c, 2d.The second bridge diagonal line comprises coil device 1, that is, first end of coil device and second end respectively with angle point 2c, 2d links to each other.
When operation, the first and the 4th transistor 13,16 or 14,15 conductings simultaneously of the second and the 3rd transistor.Like this, under first kind of situation (transistor 13,16 conductings), electric current (supposition is positive) flows to angle point 2b from angle point 2a by coil device 1 along the solid arrow indicated direction.If transistor 14,15 conductings, identical electric current flows through coil device 1 along opposite direction, shown in dotted arrow.
Just as well known to the skilled person, by transistor 13,16 and 14,15 produce coil current according to above-mentioned alternate conduction, can be so that at first half cycle of one-period, electric current is positive, and have first a constant ultimate current value, and at second half cycle in this cycle, electric current is born, and having the second constant ultimate current value, its amplitude and the first ultimate current value equate." the ultimate current value " of Shi Yonging refers to the steady state value of coil current herein, 85mA for example, and it flowed along another direction of current before commutation.
In Fig. 1, angle point 2c links to each other with ground SN by resistance 10.Resistance 10 and H network 2 form series circuit, and resistance 10 flows through coil current.
Fig. 1 also represents controlled voltage source 7, and it has voltage output 7c, and determines to be added on the voltage at series circuit two ends, i.e. voltage between angle point 2a and the ground SN; Supposing that herein this voltage is positive, is positive sign at output terminal 7c promptly.Controlled voltage source 7 is by two input end 7a, and 7b provides primary power by AC power; It links to each other with ground SN by output terminal 7d.
Voltage on output terminal 7c is applied to angle point 2a by the anode-cathode path of diode 9.Electric capacity is that the capacitor 12 of C links to each other with ground SN with angle point 2a from the negative electrode of diode 9.
In Fig. 2, the order of coil device and resistance in series circuit has been exchanged: the angle point 2b of H network 2 directly links to each other with ground now, and the label of resistance is 10 ' now, is connected between the anode of the output terminal 7c of controlled voltage source 7 and diode 9.
Be connected advantage like this and be, at angle point 2c, between the 2d, i.e. any short circuit in coil device 1 can not destroy the transistor 13,16 or 14,15 of current conducting, because coil current has been limited by resistance 10 '.
Each bridge circuit is realized as T network 3,3 ' among the embodiment that Fig. 3 and Fig. 4 represent.Resistance 22,22 ' and coil device 1 form series circuit 4,4 '.In the embodiments of figure 3, coil device 1 links to each other by resistance 22 with ground SN, and coil current passes through series circuit.In Fig. 4, first end of series circuit 4 ' links to each other with ground SN.
Second end of first end of the controlled current path of first switching transistor 25 and series circuit 4,4 ' links to each other.The first output terminal 30c of second end of this controlled current path and controlled voltage source 30 links to each other; This output terminal 30c determines to be added on the positive voltage on the series circuit, that is, be positive sign at output terminal 30c.
Second end of first end of the controlled current path of second switch transistor 26 and series circuit 4,4 ' links to each other.The second output terminal 30d of second end of this current path and controlled voltage source 30 links to each other; This second output terminal 30d determines to be added on the negative voltage on the series circuit, that is, be negative sign at output terminal 30d.
In Fig. 3 and Fig. 4, be applied to second end of switching transistor 25 by the anode-cathode path of first diode at the positive voltage of the output terminal 30c of voltage source 30.Capacitance is C
1First electric capacity 33 link to each other with ground SN from this end of switching transistor 25 and the negative electrode of diode 31.
Be applied to second end of switching transistor 26 by the K-A path of second diode 32 at the negative voltage of the output terminal 30d of voltage source 30.Capacitance is C
2Second electric capacity 34 link to each other with ground SN from this end of switching transistor 26 and the negative electrode of diode 32.
At Fig. 1 and Fig. 2 or in Fig. 3 and embodiment shown in Figure 4, by the inductance L of coil device 1 and the capacitor C of capacitor 12, perhaps by the capacitor C of inductance L and capacitor 33 and 34
1And C
2Constitute each resonant circuit respectively.As a result, resonance step-up take place to take place on series circuit, and the coil current when every half cycle begins is between the rising stage, coil current is compared when not having resonant circuit has steep forward position.
In the present invention, voltage source 7,30th, controlled, as described below, so that, be called " rise time t later at first subcycle of each half cycle of coil current
a", initial voltage value U is provided
a, it is than the constant final magnitude of voltage U during second subcycle
cBig several times, second subcycle is called " excess time t later on
c", as Fig. 5 a, shown in the 5b.
In addition, be added on resistance 10, the voltage drop on 10 ', 22,22 ' is used for compensating the influence of the eddy current of responding at iron core and pole element between the rising stage at coil current, and the forward position that described eddy current makes magnetic field is delayed with respect to the forward position of coil current.
This passes through the rise time t of control coil electric current in this manner
aWith positive and negative final magnitude of voltage U in every half cycle
cAmplitude realize, make on the one hand, reach maximal value I at coil current
mAfterwards, coil current no longer rises, thereby makes magnetic field reach constant end value B
m, itself and reach maximal value I when coil current
mThe time coil current constant end value corresponding, shown in Fig. 5 a, on the other hand, positive or negative final magnitude of voltage U
cAmplitude total produce constant ultimate current value I
c, 85mA for example.
This is by reaching I at coil current between the semiperiod
mAfterwards, the waveform of the voltage drop at resistance two ends is sampled 3 times at least, realize so that form the correcting value that is added on H network and the T network at lower half.
In Fig. 5 a, show the curve of the induction B in coil current I and magnetic field to the time.In first half cycle, have positive coil current I, as can be seen, this half cycle comprises rise time t
aWith t excess time
c, the induction B that equals magnetic field described excess time is the constant time.
At rise time t
aDuring this time, coil current I on the one hand, rises precipitously, then, is reaching maximal value I
mDescend afterwards, and its reach constant end value the time be engraved in after the moment that magnetic induction B reaches constant end value, promptly coil current is at maximal value I
mLittle by little reduce afterwards.This behavior of coil current is because due to the above-mentioned eddy current of responding in iron core and pole element.Reach coil current maximal value I
mThe moment determine rise time t
aWith t excess time
cBetween the border.
At rise time t
a, on the other hand, magnetic induction B is at first almost the same with coil current to rise precipitously, becomes more flat then, and as desired, at rise time t
aDuring end, reached its constant end value B
m
At remainder t
cArrow shown in during this time above the decay part of coil current curve is represented to ultimate current value I
mThe coil current waveform of decay is sampled 3 times at least, for example every millisecond of once sampling; In the example shown in Fig. 5 a, the decay of coil current partly is sampled 4 times.According to the present invention, utilize these sampled values to obtain being used for the control signal of controlled voltage source, also to describe in detail below.
In Fig. 5 b, show the voltage that is added on the series circuit two ends that comprise H network or T network curve to time t.The first peak value U
sBe because above-mentioned resonance step-up obtains.Steady state value subsequently is above-mentioned initial voltage value U
a, it rises coil current precipitously.
If do not have resonance to rise, then at whole rise time t
aIn have only initial voltage value U
aExist.At t excess time
cDuring this time, there is constant final magnitude of voltage U
cCan be clear that by Fig. 5 b, as mentioned above, initial voltage value U
aGreater than final magnitude of voltage U
b
In Fig. 4, the control of voltage source 7,30 is respectively by controller 41,42 at Fig. 1, and 43,44 represent.Controller 41,42 is inserted in resistance 10 respectively, 10 ' and the control of voltage source 7 input 7e between.Controller 43,44 is inserted in resistance 22 respectively, 22 ' and the control of voltage source 30 input 30e between.Controller 41,42 is also controlled the resistance 13,14,15,16 of H network, and controller 43,44 is also controlled the resistance 25,26 of T network.
Preferably microprocessor has illustrated suitable functional block and decision piece according to the flow chart programming of Fig. 6 among Fig. 6.Use lowercase alphabet registration word signal, this is important for process flow diagram.
Utilize above-mentioned analog-digital converter to make ohmically voltage drop digitizing, thereby obtain to represent the digital signal i of coil current I.Digital signal i is applied in the input end of maximum value detector 61 and the input end of controlled stage 62, and controlled stage 62 also is transfused to the peak signal i from maximum value detector 61
m62 of controlled stages are by occurring in these parts as the digital signal i of current sample s after the peak signal im.
The first decision level 63 is checked continuous, adjacent current sample s, so that whether determine a back sampling greater than previous sampling, that is, whether the coil current between two samplings raises; If, then provide control signal y at YES output terminal Y, if not, then provide control signal n at NO output terminal N.
Control signal y makes pulse persistance level 64 prolong rise time t
a, control signal n makes pulse persistance level 64 prolong t excess time
cThe output of pulse persistance level and voltage source 7,30 link to each other.
The second decision level 65 continues to check current sample s, determine its whether greater than, be equal to or less than current reference value i
r, itself and ultimate current value Ic are directly proportional, and definite ultimate current value Ic.In these cases, then determine level 65 at GREATER output terminal G output control signal g, or at EQUAL output terminal GL output control signal g1, or at LESS output terminal K output control signal k.
These control signals g, gl, k are transfused to voltage source 7,30, if desired, then import by D-A converter, and the initial voltage value U that is provided in the one-period of coil current by voltage source is provided
a: control signal g increases the initial voltage U of next cycle
a, perhaps control signal gl makes it remain unchanged at next cycle, and perhaps control signal k makes it reduce at next cycle.
It will be understood by those of skill in the art that the transistor 13,14,15,16 of Fig. 1-4,25 and 26 control and operation can realize that this patent is drawn at this and is reference according to the instruction of United States Patent (USP) 4410926..In addition, transistor 13,14,15,16,25 and 26 controlled current path be respectively by discharge diode 17,18,19,20,27 and 28 bypasses.
Shown transistor is a bipolar transistor, but can certainly make field-effect transistors, particularly insulated-gate type field effect transistor.
Fig. 7 a contains the decision square with note in the process flow diagram of 7b, thereby is the self type, and it is the process flow diagram that makes it possible to understand further Fig. 6, and Fig. 7 b must be connected in the some A of Fig. 7 a.
Claims (4)
1. method that is used for being adjusted in the coil current that coil device flows, described coil device:
-formation is comprised in the magnetic flow detecting device and the parts of the magnetic system in magnetic field is provided,
-it comprises iron core and pole element, and
-it has inductance L,
-be positive at the described coil current of first half cycle of one-period, and has first a constant ultimate current value, the described coil current of second half cycle in the described cycle is born, and has amplitude and the equal second constant ultimate current value of the first ultimate current value; And
-described coil current is produced by a kind of circuit arrangement, comprising:
--be the bridge circuit of H latticed form, it has
First brachium pontis that---by the controlled current path of the first transistor constitutes,
Second brachium pontis that---by the controlled current path of transistor seconds constitutes,
The 3rd brachium pontis that---by the 3rd transistorized controlled current path constitutes, and
The 4th brachium pontis that---by the 4th transistorized controlled current path constitutes,
The transistor seconds that---be positioned at links to each other with the first transistor, with and the 4th transistor that links to each other of the 3rd transistor between the first bridge diagonal line, and
The 3rd transistor that---be positioned at links to each other with the first transistor, with and the 4th transistor that links to each other of transistor seconds between the second bridge diagonal line, wherein
----be the first and the 4th transistor perhaps,
----perhaps the second and the 3rd transistor conducting simultaneously;
--above-mentioned coil device is positioned on the first bridge diagonal line;
--so be connected the feasible resistance that forms series circuit with the H network, its first end ground connection, and wherein pass through coil current; And
--controlled voltage source, its
Voltage output of---have, and
The voltage that---determine produces at the series circuit two ends;
----described voltage has an initial voltage value-as first subcycle-its final magnitude of voltage during greater than second subcycle of the remainder of representing half cycle during the rise time of every half cycle at coil current;
Described method is used the voltage drop at resistance two ends,
-on the one hand, be used to keep the constant final magnitude of voltage that is used to form the first and second ultimate current values, and
-on the other hand, be used for the influence of compensation of eddy currents, described eddy current iron core/and or pole element in respond between the rising stage at coil current, and its forward position that makes described magnetic field postpones with respect to the forward position of coil current, described delay be by
--in every half cycle, influence the rise time of coil current and the amplitude of final magnitude of voltage by this way, make after coil current reaches maximum, coil current no longer rises, thereby make magnetic field will reach constant end value, the constant end value of this end value and the coil current when coil current reaches maximal value is corresponding
--after the maximal value of coil current, reach between the semiperiod of ultimate current value, the waveform of the voltage drop at resistance two ends is sampled 3 times at least continuously, thereby forms the correcting value of the H network both end voltage of next half cycle.
2. method that is used for the coil current of regulating winding device, wherein said coil device
-be formed in the parts of the magnetic system that comprises in the electromagnetic flow sensors, and produce magnetic field,
-comprise iron core and pole element, and
-have an inductance L,
-at first half cycle of one-period, described coil current is positive, and have the first constant ultimate current value, and second half cycle in the described cycle, described coil current is born, and has the second constant ultimate current value, and its amplitude and the first ultimate current value equate; And
-described coil current is produced by a circuit arrangement, and described circuit arrangement comprises:
--controlled voltage source, it has first voltage output end and second voltage output end, and
--T-network, it comprises:
---resistance, it so links to each other with coil device, makes to form series circuit, its first end ground connection, and wherein by coil current,
---the first switching transistor, it has first end of its controlled current path that links to each other with second end of series circuit, and having second end of exporting its controlled current path that links to each other with first voltage of controlled current source, the output of first voltage provides a positive voltage on described series circuit, and
---second switch transistor, it has first end of its controlled current path that links to each other with second end of series circuit, and having second end of exporting its controlled current path that links to each other with second voltage of controlled current source, the output of second voltage provides a negative voltage on described series circuit
----described generating positive and negative voltage has positive initial voltage value and negative initial voltage value respectively in every half cycle, at coil current between the rising stage-as first subcycle-it is respectively greater than at the positive final magnitude of voltage as second subcycle of the remainder of half cycle, and less than the negative final magnitude of voltage during described second subcycle;
Described method is used described ohmically voltage drop,
-on the one hand, be used to make described positive and negative final magnitude of voltage to keep constant, be used for forming respectively the first and second ultimate current values, and
-on the other hand, being used for compensating the influence of the eddy current of responding at iron core and pole element between the rising stage at coil current, the forward position that described eddy current makes magnetic field is delayed with respect to the forward position of coil current,
--in each half cycle, influence the rise time of coil current and the amplitude of positive and negative final magnitude of voltage by this way, make coil current just no longer rise after reaching maximal value, thereby make magnetic field will reach constant end value, it is corresponding to the constant end value of the coil current that has existed when coil current reaches maximal value
--after the maximal value of coil current, reach between the semiperiod of ultimate current value, the waveform of the voltage drop at resistance two ends is sampled 3 times at least continuously, thereby forms the correcting value of the T network both end voltage of next half cycle.
3. the method for claim 1, wherein
First end of-resistance and the voltage output end of voltage source link to each other,
Second end of-resistance links to each other by first and second transistorized tie point of a diode and H network, and the forward of described diode equals the direction of coil current, while the second and the 4th transistorized tie point ground connection, and
-H network is the capacitor bypass of C by electric capacity,
--described capacitor and inductance L form resonant circuit, and its effect is
The voltage generation resonance at---make H network two ends raises, and
During---thereon rises, and do not have resonant circuit to compare, coil current has steep front.
4. method as claimed in claim 2, wherein
-coil device links to each other with ground;
-resistance is connected between the tie point and coil device of first and second switching transistor;
Second end of-the first switching transistor
--link to each other by the K-A path of first diode and first voltage output of controlled voltage source, and
--by electric capacity is C
1First capacitor grounding; And
Transistorized second end of-second switch
--link to each other by the anode-cathode path of second diode and second voltage output of controlled voltage source, and
--by electric capacity is C
2Second capacitor grounding,
---described first and second capacitors and inductance L form resonant circuit respectively, and its effect is
The voltage generation resonance at---make series circuit two ends raises, and
During---thereon rises, and do not have resonant circuit to compare, coil current has steep front.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP98112321.9 | 1998-07-03 | ||
| EP98112321 | 1998-07-03 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1241714A CN1241714A (en) | 2000-01-19 |
| CN1096604C true CN1096604C (en) | 2002-12-18 |
Family
ID=8232211
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN99110143A Expired - Fee Related CN1096604C (en) | 1998-07-03 | 1999-07-02 | Method of regulating coil current of electromagnetic flow sensors |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JP3043757B2 (en) |
| CN (1) | CN1096604C (en) |
| HK (1) | HK1024293A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100451563C (en) * | 2004-09-22 | 2009-01-14 | 恩德斯+豪斯流量技术股份有限公司 | Method for testing a magnetic inductive flow meter |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5843670B2 (en) * | 2012-03-15 | 2016-01-13 | アズビル株式会社 | Excitation circuit of electromagnetic flow meter |
| CN103759773B (en) * | 2014-02-18 | 2016-03-09 | 北京中锐智诚科技有限公司 | Field voltage method of adjustment, control circuit and electromagnetic flowmeter field circuit |
| KR101591851B1 (en) * | 2014-03-11 | 2016-02-04 | 코리아쌀베지 주식회사 | Pipe blocking prevention device for dredged soil transfer |
| DE102014107200A1 (en) | 2014-05-22 | 2015-11-26 | Endress + Hauser Flowtec Ag | Device for measuring the volume flow of a fluid |
| CN104579069B (en) * | 2015-01-30 | 2020-05-26 | 天津工业大学 | Multifunctional magnetic field generation control circuit |
| JP6835539B2 (en) * | 2016-11-09 | 2021-02-24 | アズビル株式会社 | Excitation circuit of electromagnetic flowmeter, and electromagnetic flowmeter |
| JP6806532B2 (en) * | 2016-11-09 | 2021-01-06 | アズビル株式会社 | Excitation circuit of electromagnetic flowmeter, and electromagnetic flowmeter |
| US11365995B2 (en) | 2018-09-28 | 2022-06-21 | Georg Fischer Signet Llc | Magnetic flowmeter including auxiliary electrodes upstream and downstream of the pair of measuring electrodes and an adjustable brace |
| US10712184B1 (en) | 2019-01-09 | 2020-07-14 | Georg Fischer Signet Llc | Magnetic flowmeter assembly having independent coil drive and control system |
| CN111351536B (en) * | 2020-04-30 | 2021-08-17 | 合肥工业大学 | Electromagnetic flowmeter excitation control system based on series resonance |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4204240A (en) * | 1978-10-26 | 1980-05-20 | Fischer & Porter Co. | High-voltage impulse driver for electromagnetic flowmeter |
| US4410926A (en) * | 1980-10-02 | 1983-10-18 | Flowtec Ag | Arrangement for generating DC magnetic fields of alternating polarity for the magnetic-inductive flow measurement |
| US4784000A (en) * | 1987-01-15 | 1988-11-15 | Emerson Electric Co. | Magnetic flowmeter coil driver and method |
-
1999
- 1999-07-02 CN CN99110143A patent/CN1096604C/en not_active Expired - Fee Related
- 1999-07-02 JP JP11189425A patent/JP3043757B2/en not_active Expired - Fee Related
-
2000
- 2000-05-30 HK HK00103192A patent/HK1024293A1/en not_active IP Right Cessation
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4204240A (en) * | 1978-10-26 | 1980-05-20 | Fischer & Porter Co. | High-voltage impulse driver for electromagnetic flowmeter |
| US4410926A (en) * | 1980-10-02 | 1983-10-18 | Flowtec Ag | Arrangement for generating DC magnetic fields of alternating polarity for the magnetic-inductive flow measurement |
| US4784000A (en) * | 1987-01-15 | 1988-11-15 | Emerson Electric Co. | Magnetic flowmeter coil driver and method |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100451563C (en) * | 2004-09-22 | 2009-01-14 | 恩德斯+豪斯流量技术股份有限公司 | Method for testing a magnetic inductive flow meter |
Also Published As
| Publication number | Publication date |
|---|---|
| HK1024293A1 (en) | 2000-10-05 |
| CN1241714A (en) | 2000-01-19 |
| JP2000035352A (en) | 2000-02-02 |
| JP3043757B2 (en) | 2000-05-22 |
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