WO2014006914A1 - 電流センサの製造方法及び電流センサ - Google Patents
電流センサの製造方法及び電流センサ Download PDFInfo
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- WO2014006914A1 WO2014006914A1 PCT/JP2013/004168 JP2013004168W WO2014006914A1 WO 2014006914 A1 WO2014006914 A1 WO 2014006914A1 JP 2013004168 W JP2013004168 W JP 2013004168W WO 2014006914 A1 WO2014006914 A1 WO 2014006914A1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R3/00—Apparatus or processes specially adapted for the manufacture or maintenance of measuring instruments, e.g. of probe tips
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/32—Compensating for temperature change
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
- G01R1/30—Structural combination of electric measuring instruments with basic electronic circuits, e.g. with amplifier
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/20—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices
- G01R15/207—Constructional details independent of the type of device used
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
- G01R33/09—Magnetoresistive devices
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/30—Modifications of amplifiers to reduce influence of variations of temperature or supply voltage or other physical parameters
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/45—Differential amplifiers
- H03F3/45071—Differential amplifiers with semiconductor devices only
- H03F3/45076—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier
- H03F3/45475—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier using IC blocks as the active amplifying circuit
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/45—Differential amplifiers
- H03F3/45071—Differential amplifiers with semiconductor devices only
- H03F3/45479—Differential amplifiers with semiconductor devices only characterised by the way of common mode signal rejection
- H03F3/45928—Differential amplifiers with semiconductor devices only characterised by the way of common mode signal rejection using IC blocks as the active amplifying circuit
- H03F3/45968—Differential amplifiers with semiconductor devices only characterised by the way of common mode signal rejection using IC blocks as the active amplifying circuit by offset reduction
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2200/00—Indexing scheme relating to amplifiers
- H03F2200/228—A measuring circuit being coupled to the input of an amplifier
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2200/00—Indexing scheme relating to amplifiers
- H03F2200/261—Amplifier which being suitable for instrumentation applications
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2200/00—Indexing scheme relating to amplifiers
- H03F2200/411—Indexing scheme relating to amplifiers the output amplifying stage of an amplifier comprising two power stages
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
- H03F2203/45—Indexing scheme relating to differential amplifiers
- H03F2203/45528—Indexing scheme relating to differential amplifiers the FBC comprising one or more passive resistors and being coupled between the LC and the IC
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49002—Electrical device making
- Y10T29/4902—Electromagnet, transformer or inductor
Definitions
- the present invention relates to a current sensor capable of contactlessly measuring a measured current, and a method of manufacturing the current sensor.
- the current sensor includes a magnetoelectric conversion element for detecting an induction magnetic field generated by the current to be measured, and calculates the current value of the measurement current based on the magnetic field intensity detected by the magnetoelectric conversion element.
- a magnetoelectric conversion element for example, a Hall element which converts magnetic field strength into an electric signal by utilizing a Hall effect, a magnetoresistance effect element which utilizes a change in electric resistance value by a magnetic field, or the like is used.
- Patent Document 1 proposes a current sensor in which a temperature change of an offset can be reduced by using a temperature sensing element whose resistance value varies with temperature.
- the current sensor described in Patent Document 1 achieves high current measurement accuracy by adjusting the offset using a temperature sensing element.
- a temperature sensing element is essential in order to adjust the temperature change of the offset.
- the present invention has been made in view of the foregoing, and it is an object of the present invention to provide a current sensor capable of realizing high current measurement accuracy with simple adjustment and a method of manufacturing the current sensor.
- a method of manufacturing a current sensor includes a current measurement circuit having a magnetoelectric conversion element, and a method of amplifying an output of the current measurement circuit and correcting a temperature characteristic of offset based on a set first correction amount. And a second amplification correction circuit that amplifies the output of the first amplification correction circuit to adjust the sensitivity and corrects the magnitude of the offset based on the set second correction amount.
- a method of manufacturing a current sensor comprising: the current measurement circuit, the first amplification correction circuit, and a substrate on which the second amplification correction circuit is provided, wherein the first measurement is performed based on the characteristics of the magnetoelectric conversion element. After setting the correction amount of 1, the magnetoelectric conversion element is mounted on the substrate, and the second correction amount is set.
- the first amplification correction circuit that corrects the temperature characteristic of the offset and the second amplification correction circuit that corrects the magnitude of the offset are separately provided, and the first amplification correction circuit is used based on the characteristics of the magnetoelectric conversion element. Since the first correction amount is set in the amplification correction circuit to correct the temperature characteristic of the offset, the second correction amount is set in the second amplification correction circuit to correct the magnitude of the offset. The correction of the characteristics and the correction of the magnitude of the offset can be performed separately. As a result, it is not necessary to acquire temperature characteristics under many conditions, and high current measurement accuracy can be realized by simple adjustment.
- the first correction amount is preferably set so as to reduce the influence of the temperature characteristic of the offset.
- the first correction amount is set based on the characteristic of the magnetoelectric conversion element measured in advance so that the influence of the temperature characteristic of the offset is reduced. The influence of the temperature characteristic can be properly removed.
- the magnetoelectric conversion element is preferably a magnetoresistance effect element. Since the magnetoresistive effect elements have small characteristic variations in the same lot and the same wafer, the characteristics of representative samples can be commonly used for the magnetoresistive effect elements in the same lot and the same wafer. That is, according to the above configuration, it is not necessary to actually measure the characteristics of all the magnetoresistive elements, and the adjustment can be further simplified.
- a magnetic proportional expression that uses the output of the current measurement circuit that is proportional to the external magnetic field.
- the current sensor is a differential type that differentially calculates outputs of the plurality of current measurement circuits. According to this configuration, it is possible to offset the temperature characteristic of the offset by making the current sensor differential.
- a current sensor includes a current measurement circuit having a magnetoelectric conversion element, and a first amplification correction that amplifies the output of the current measurement circuit and corrects the temperature characteristic of the offset based on the set first correction amount.
- the first correction amount is set so as to reduce the influence of the temperature characteristic of the offset.
- the magnetoelectric conversion element is preferably a magnetoresistive effect element.
- the current sensor of the present invention it is preferable to use a magnetic proportional expression that uses the output of the current measurement circuit that is proportional to the external magnetic field.
- the current sensor of the present invention it is preferable to be of a differential type in which outputs of a plurality of the current measurement circuits are differentially operated.
- FIG. 2 is a block diagram showing a configuration example of a magnetic proportional type current sensor according to Embodiment 1;
- FIG. 1 is a circuit diagram showing a configuration example of a current measurement circuit according to a first embodiment.
- 5 is a graph showing the characteristic of the correction offset of the operational amplifier (first operational amplifier) according to the first embodiment.
- FIG. 5 is a block diagram showing the relationship between input and output of signals of the current sensor according to the first embodiment. It is a graph which shows the relationship between the correction
- FIG. 7A is a graph showing the relationship between the correction offset of the operational amplifier (second operational amplifier) according to Embodiment 1 and the sensor output
- FIG. 7B is a graph showing output change with respect to the current to be measured
- 5 is a graph showing the characteristics of the correction offset of the amplification correction circuit (first operational amplifier) according to the first embodiment.
- FIG. 7 is a block diagram showing a configuration example of a magnetic balance type current sensor according to a second embodiment.
- FIG. 8 is a block diagram showing the relationship between input and output of signals of the current sensor according to Embodiment 2.
- FIG. 16 is a block diagram showing an example of configuration of a differential type current sensor according to a third embodiment. It is a graph which shows the temperature characteristic of the output in the state where the to-be-measured electric current is zero in the current sensor which concerns on Embodiment 3.
- the gist of the present invention is to separately provide a first amplification correction circuit that corrects the temperature characteristic of the offset and a second amplification correction circuit that corrects the magnitude of the offset in the current sensor.
- a first amplification correction circuit that corrects the temperature characteristic of the offset
- a second amplification correction circuit that corrects the magnitude of the offset in the current sensor.
- FIG. 1 is a block diagram showing an example of the configuration of a magnetic proportional current sensor according to the present embodiment.
- the current sensor 1 of the present embodiment includes a current measurement circuit 11 that converts an induced magnetic field H generated by a current to be measured into an electrical signal.
- an amplification correction circuit (first amplification correction circuit) 12 that amplifies and corrects the output of the current measurement circuit 11 is connected.
- an amplification and correction circuit (second amplification and correction circuit) 13 that amplifies and corrects the output of the amplification and correction circuit 12 is connected to the subsequent stage of the amplification and correction circuit 12.
- FIG. 2 is a circuit diagram showing a configuration example of the current measurement circuit 11 according to the present embodiment.
- the current measurement circuit 11 is a bridge circuit including magnetoresistance effect elements M1 to M4 which are magnetoelectric conversion elements, and can output a voltage corresponding to the magnitude of the induced magnetic field H by the measured current. Is configured.
- the magnetoresistance effect elements M1 to M4 are, for example, GMR (Giant Magneto Resistance) elements whose resistance value changes when a magnetic field is applied.
- connection point between the magnetoresistive elements M1 and M3 is connected to the terminal T1, and a power supply that supplies a power supply voltage is connected to the terminal T1.
- the connection point of the magnetoresistive elements M2 and M4 is connected to a terminal T2, and a ground for applying a ground voltage is connected to the terminal T2.
- the connection point of the magnetoresistive elements M1 and M2 is connected to the output terminal O1 of the current measurement circuit 11, and the connection point of the magnetoresistive elements M3 and M4 is connected to the output terminal O2 of the current measurement circuit 11.
- the voltage difference generated at the two output terminals O1 and O2 fluctuates in response to the magnetic field applied to the current measurement circuit 11, and is sent to the subsequent stage as the output of the current measurement circuit 11.
- the two output terminals O1 and O2 of the current measurement circuit 11 are respectively connected to the non-inverted input terminal (+) and the inverted input terminal (-) of the operational amplifier 121 included in the amplification correction circuit 12.
- a correction circuit 122 for correcting the output of the current measurement circuit 11 is connected to the operational amplifier 121.
- the correction circuit 122 outputs a correction voltage (first correction voltage V 1 ) according to the set correction amount (first correction amount), and the operational amplifier 121 receives the first correction voltage supplied from the correction circuit 122. It corrects the output of the current measuring circuit 11 according to the correction voltage V 1.
- the amplification correction circuit 12 has an amplification function, and the output of the current measurement circuit 11 is amplified at a predetermined amplification factor.
- FIG. 3 is a graph showing the characteristics of the correction offset added by the operational amplifier 121. 3, the vertical axis represents the temperature coefficient of the correction offset, the horizontal axis represents the first correction voltages V 1 supplied to the operational amplifier 121. The temperature coefficient of the correction offset represents the degree of temperature dependence of the correction offset.
- the correction offset generated by the operational amplifier 121 has a temperature coefficient proportional to the first correction voltage V1. 3, the temperature coefficient of the correction offset generated by the operational amplifier 121 is made smaller as the first correction voltage V 1 is increased. By supplying the appropriate first correction voltage V 1 from the correction circuit 122 to the operational amplifier 121 having such temperature characteristics, it is possible to reduce the temperature-dependent influence of the offset by the current measurement circuit 11.
- the output terminal (the output terminal of the operational amplifier 121) of the amplification correction circuit 12 is connected to the input terminal of the operational amplifier 131 provided in the amplification correction circuit 13.
- the operational amplifier 131 is connected to a correction circuit 132 for correcting the output of the amplification correction circuit 12 to adjust the sensitivity, and for correcting the magnitude of the offset.
- the correction circuit 132 outputs a correction voltage (second correction voltage V 2 ) and a correction signal (correction signal S) according to the correction amount (second correction amount, third correction amount) to be set, and performs calculation.
- the amplifier 131 corrects the output according to the second correction voltage V 2 supplied from the correction circuit 132 and the correction signal S.
- the operational amplifier 131 corrects the magnitude of the offset in accordance with the second correction voltage V2 supplied from the correction circuit 132, and the sensitivity (in accordance with the correction signal S supplied from the correction circuit 132). Correct the amplification factor).
- the operational amplifier 131 is configured such that its output is independent of temperature (does not have temperature characteristics). Thereby, in the amplification correction circuit 13, only the magnitude and sensitivity of the offset can be corrected without changing the temperature characteristic.
- the output of the amplification correction circuit 13 after correction (the output of the operational amplifier 131) is the output of the current sensor 1.
- the current sensor 1 is manufactured by mounting the magnetoresistance effect elements M1 to M4 constituting the current measurement circuit 11 on a substrate (not shown) on which the amplification correction circuits 12 and 13 are mounted.
- the magnetoresistance effect elements M1 to M4 have characteristic variations for each individual.
- the first correction is made to the amplification correction circuit 12 (correction circuit 122) before the magnetoresistive effect elements M1 to M4 are mounted. Set the amount.
- the first correction amount can be set based on the temperature characteristics of the magnetoresistive elements M1 to M4.
- FIG. 4 is a block diagram showing the relationship between the input and output of the signal of the current sensor 1 of the present embodiment.
- I x represents the input signal (corresponding to the current to be measured) to the current measurement circuit 11
- K 0 represents the sensitivity of the current measurement circuit 11
- K 1 represents the amplification factor of the amplification correction circuit 12.
- K 2 indicates the amplification factor of the amplification correction circuit 13
- V out indicates the output (voltage) of the current sensor 1.
- V ofs indicates an offset (voltage) generated in the current measurement circuit 11
- V trim indicates a correction offset (voltage) of the amplification correction circuit 12.
- the offset of V out has temperature characteristics. Assuming that the temperature is T (° C.), the temperature characteristic of V ofs (first-order coefficient of temperature) is ⁇ (1 / ° C.), and the temperature characteristic of V trim (first-order coefficient of temperature) is ⁇ (1 / ° C.)
- the offset of V out can be expressed by a linear equation of temperature. If the conditions under which the offset of Vout is zero at room temperature (here, 25 ° C.) and the conditions under which the temperature characteristic is minimum at temperature T are applied, it is necessary to minimize the temperature characteristic of the offset of Vout.
- a correction offset V Trim_min of Do amplifying correcting circuit 12 the relationship between the correction offset V Trim_RT amplifying correcting circuit 12 required for the offset of V out to zero at room temperature, for example, as the following equation (1) Become.
- V trim — RT corresponds to the correction offset necessary to obtain an output V out — 0 at which the offset is zero at room temperature. Therefore, V trim — RT of the above equation (1) can be obtained from the graph of FIG.
- the graph shown in FIG. 5 can be derived based on, for example, the output characteristics of the amplification correction circuit 12 acquired in advance in the state where pseudo circuits corresponding to the magnetoresistance effect elements M1 to M4 are connected.
- ⁇ is a first-order coefficient representing the temperature characteristic of V trim and corresponds to the ratio b / a of the slope a of the graph shown in FIG. 5 to the slope b of the graph shown in FIG. Therefore, ⁇ can be obtained from the above-mentioned FIG. 5 and FIG. FIG. 6 can be derived from the characteristics of the operational amplifier 121 obtained in advance.
- ⁇ is a first-order coefficient representing the temperature characteristic of V ofs and can be derived based on the characteristics of the magnetoresistive elements M1 to M4 obtained at the wafer stage.
- the correction offset of the amplification correction circuit 12 necessary to minimize the temperature characteristic of the offset V trim_min can be calculated. Therefore, before the magnetoresistive elements M1 to M4 are mounted, the first correction amount that generates the first correction voltage V1 corresponding to the correction offset V trim_min is set in the amplification correction circuit 12 (correction circuit 122). By doing so, the temperature dependency of the offset can be easily reduced.
- the magnetoresistive effect elements M1 to M4 have small characteristic variations in the same lot and the same wafer, if the characteristic of a representative sample is obtained in advance, even when adjusting the other current sensors 1, The characteristics can be commonly used. This eliminates the need to measure the temperature characteristics of all the magnetoresistance effect elements M1 to M4 for each current sensor, so that the adjustment can be further simplified.
- the magnetoresistance effect elements M1 to M4 constituting the current measurement circuit 11 are mounted on the substrate. In this state, the temperature dependence of the offset is minimal. Therefore, the second correction amount and the third correction amount can be set in the amplification correction circuit 13 by simple measurement. For example, as shown in FIG. 7B, a desired sensitivity (gain_set) is realized from the ratio of changes in output by measuring the change in output with respect to the current to be measured at two levels (gain_a, gain_b) with different correction amounts. It is possible to determine a third correction amount for Further, as shown in FIG.
- the second correction amount and the third correction amount are set in the amplification correction circuit 13, the current sensor 1 is completed.
- the first amplification correction circuit 12 that corrects the temperature characteristic of the offset and the second amplification correction circuit 13 that corrects the magnitude of the offset are described.
- the temperature characteristic of the offset is corrected by setting the first correction amount in the first amplification correction circuit 12 based on the characteristics of the magnetoelectric conversion elements M1 to M4 separately provided, and then the second amplification correction circuit 13 Since the amount of correction is set to correct the magnitude of the offset, correction of the temperature characteristic of the offset and correction of the magnitude of the offset can be performed separately. As a result, it is not necessary to acquire temperature characteristics under many conditions, and high current measurement accuracy can be realized by simple adjustment.
- the first correction amount of the first amplification correction circuit 12 is set so that the influence of the temperature characteristic of the offset is reduced. Properly remove the influence of the property. Further, since the current sensor 1 is a magnetic proportional expression that uses the output of the current measurement circuit 11 that is proportional to the external magnetic field, the offset can be adjusted by a simple correction process using the above equation (1).
- the magnetoelectric conversion elements M1 to M4 constituting the current measurement circuit 11 are provided. Is mounted on the substrate and the second correction amount is set in the second amplification correction circuit 13, but the method of manufacturing the current sensor 1 is not limited to this. After the magnetoresistive effect elements (magnetoelectric conversion elements) M1 to M4 are mounted on the substrate, the first correction amount of the first amplification correction circuit 12 and the second correction amount of the second amplification correction circuit 13 are set. It is good.
- FIG. 8 is a graph showing the characteristic of the correction offset of the amplification correction circuit 12.
- FIG. 9 is a block diagram showing a configuration example of the magnetic balance type current sensor 2 according to the present embodiment.
- the current sensor 2 according to the present embodiment and the current sensor 1 according to the first embodiment are common in many points. Therefore, the common components are denoted by the same reference numerals and the detailed description thereof is omitted.
- the current sensor 2 of the present embodiment includes a current measurement circuit 11 that converts an induced magnetic field generated by the current to be measured into an electric signal.
- An amplification correction circuit (first amplification correction circuit) 12 is connected to the rear stage of the current measurement circuit 11.
- the feedback coil 21 is connected to the output terminal of the operational amplifier 121 of the amplification correction circuit 12.
- the feedback coil 21 is formed of, for example, a spiral planar conductive pattern. When a current (feedback current) flows from the operational amplifier 121 into this conductive pattern, a reverse cancellation magnetic field corresponding to the induced magnetic field is generated.
- the shape of the feedback coil 21 is not particularly limited.
- the I / V amplifier 22 Connected to the feedback coil 21 is an I / V amplifier 22 that converts the feedback current into a voltage.
- the I / V amplifier 22 is configured to include an operational amplifier 221, and its inverting input terminal ( ⁇ ) is connected to the feedback coil 21.
- a reference voltage is given to the non-inverting input terminal (+) of the operational amplifier 221.
- the output terminal of the operational amplifier 221 is connected to the inverting input terminal ( ⁇ ) of the operational amplifier 221 via the resistance element 222.
- the output terminal of the operational amplifier 221 is connected to the amplification correction circuit (second amplification correction circuit) 13.
- the current sensor 2 of the present embodiment is also manufactured by the same method as the current sensor 1. That is, the current sensor 2 is manufactured by mounting the magnetoresistance effect elements M1 to M4 constituting the current measurement circuit 11 on a substrate (not shown) on which the amplification correction circuits 12 and 13 are mounted. Also in the present embodiment, the first correction amount is set in the amplification correction circuit 12 (correction circuit 122) before the magnetoresistive elements M1 to M4 are mounted. The first correction amount can be set based on the temperature characteristics of the magnetoresistive elements M1 to M4.
- FIG. 10 is a block diagram showing the relationship between the input and output of the signal of the current sensor 2 of the present embodiment.
- I x represents an input signal (corresponding to the current to be measured) to the current measurement circuit 11
- H x represents a conversion coefficient of the magnetic field in the current measurement circuit 11
- K 0 represents the sensitivity of the current measurement circuit 11.
- K 1 represents the amplification factor of the amplification correction circuit 12
- R c represents the impedance of the feedback coil
- H c represents the conversion coefficient of the magnetic field in the feedback coil 21
- R s represents the resistance value of the resistive element 222.
- K 2 indicates the amplification factor of the amplification correction circuit 13
- V out indicates the output (voltage) of the current sensor 1.
- V ofs indicates an offset (voltage) generated in the current measurement circuit 11
- V trim indicates a correction offset (voltage) of the amplification correction circuit 12.
- the offset of V out has temperature characteristics.
- the temperature is T (° C)
- the temperature characteristic of V ofs is ⁇ (1 / ° C)
- the temperature characteristic of V trim is ⁇ (1 / ° C)
- the temperature characteristic of the sensitivity of the current measurement circuit 11 is ⁇ (1 / ° C)
- the offset of V out can be expressed by a linear equation of temperature. If the conditions under which the offset of V out becomes zero at room temperature (here, 25 ° C.) and the conditions under which the temperature characteristic becomes minimum at temperature T are applied, it is necessary to minimize the temperature characteristic of V out offset.
- a correction offset V Trim_min amplifying correcting circuit 12 the relationship between the correction offset V Trim_RT amplifying correcting circuit 12 required for the offset zero at room temperature, for example, as the following equation (2).
- the correction offset V trim — min of the amplification correction circuit 12 necessary to minimize the temperature characteristic of the offset can be calculated from various characteristics that can be acquired in advance. Therefore, before the magnetoresistive elements M1 to M4 are mounted, the first correction amount that generates the first correction voltage V1 corresponding to the correction offset V trim_min is set in the amplification correction circuit 12 (correction circuit 122). By doing so, the temperature dependency of the offset can be easily reduced.
- the magnetoresistance effect elements M1 to M4 constituting the current measurement circuit 11 are mounted on the substrate. In this state, the temperature dependence of the offset is minimal. Therefore, the second correction amount and the third correction amount can be set in the amplification correction circuit 13 by simple measurement. When the second correction amount and the third correction amount are set in the amplification correction circuit 13, the current sensor 2 is completed.
- the first amplification correction circuit 12 that corrects the temperature characteristic of the offset and the second amplification correction circuit 13 that corrects the magnitude of the offset are separately provided.
- the first correction amount is set in the first amplification correction circuit 12 based on the characteristics of the conversion elements M1 to M4 to correct the temperature characteristic of the offset
- the second correction amount is output to the second amplification correction circuit 13. Since setting is performed to correct the magnitude of the offset, correction of the temperature characteristic of the offset and correction of the magnitude of the offset can be performed separately. As a result, it is not necessary to acquire temperature characteristics under many conditions, and high current measurement accuracy can be realized by simple adjustment.
- the structures or methods described in this embodiment can be implemented in appropriate combination with the structures or methods described in the other embodiments.
- FIG. 11 is a block diagram showing a configuration example of a differential type current sensor 3 according to the present embodiment.
- the current sensor 3 according to the present embodiment and the current sensor 1 according to the first embodiment are common in many points. Therefore, the common components are denoted by the same reference numerals and the detailed description thereof is omitted.
- the current sensor 3 of the present embodiment includes current measurement circuits 11a and 11b that convert an induced magnetic field generated by a current to be measured into an electric signal.
- Amplification correction circuits (first amplification correction circuits) 12a and 12b are connected to the subsequent stages of the current measurement circuits 11a and 11b, respectively.
- the configurations of the current measurement circuits 11a and 11b are the same as those of the current measurement circuit 11 of the first embodiment, and the configurations of the amplification correction circuits 12a and 12b are the same as that of the amplification correction circuit 12 of the first embodiment.
- the output terminals of the operational amplifiers 121a and 121b are connected to the non-inverted input terminal (+) and the inverted input terminal (-) of the operational amplifier 131, respectively.
- the amplification correction circuit 13 calculates the difference between the output V a of the amplification correction circuit 12 a and the output V b of the amplification correction circuit 12 b and corrects the magnitude and sensitivity of the offset.
- the temperature characteristics of the offset can be offset by performing correction so that the temperature characteristics of the offset become equal in the amplification correction circuits 12 a and 12 b.
- FIG. 12 is a graph showing the temperature characteristics of the output in the state where the measured current is zero. As shown in FIG. 12, the output V a of the amplifier correction circuit 12a, so that the difference between the output V b of the output of the amplifier correction circuit 12b becomes constant without depending on the temperature, the amplification correcting circuit 12a, an offset in the 12b Correct the temperature characteristics of
- the temperature characteristics of the offsets generated in the current measurement circuits 11a and 11b can be offset. That is, by setting the current sensor 3 as a differential type using the plurality of current measurement circuits 11a and 11b, offset temperature characteristics can be offset to realize high current measurement accuracy.
- the temperature characteristics of the offset can be offset, the temperature characteristics of the offset need not necessarily be minimized in the amplification correction circuits 12a and 12b.
- the structures or methods described in this embodiment can be implemented in appropriate combination with the structures or methods described in the other embodiments.
- an amplification correction circuit (second amplification correction circuit) 13 for correcting the temperature characteristics of the offset and a first correction amount is set in the amplification correction circuits 12, 12a and 12b based on the characteristics of the magnetoelectric conversion element. Since the second correction amount is set in the amplification correction circuit 13 to correct the magnitude of the offset after correction, the correction of the temperature characteristic of the offset and the correction of the magnitude of the offset can be performed separately. As a result, it is not necessary to acquire temperature characteristics under many conditions, and high current measurement accuracy can be realized by simple adjustment.
- the bridge circuit constituting the current measurement circuit exemplifies a current sensor constituted by four magnetoresistance effect elements, but in the bridge circuit, the resistance value does not change due to the external magnetic field.
- a fixed resistance element or the like may be included.
- the current measurement circuit may be a circuit other than the bridge circuit as long as it can detect an induced magnetic field.
- connection relation, the size, and the like of each element in the above embodiment can be changed without changing the gist of the invention.
- the configurations, methods, and the like described in the above embodiments can be implemented in combination as appropriate.
- the present invention can be modified as appropriate without departing from the scope of the present invention.
- the current sensor of the present invention can be used, for example, to detect the magnitude of the current for driving a motor such as an electric car or a hybrid car.
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
- Measurement Of Current Or Voltage (AREA)
Abstract
Description
図1は、本実施の形態に係る磁気比例式の電流センサの構成例を示すブロック図である。図1に示すように、本実施の形態の電流センサ1は、被測定電流により生じる誘導磁界Hを電気信号に変換する電流測定回路11を備えている。電流測定回路11の後段には、電流測定回路11の出力を増幅して補正する増幅補正回路(第1の増幅補正回路)12が接続されている。また、増幅補正回路12の後段には、増幅補正回路12の出力を増幅して補正する増幅補正回路(第2の増幅補正回路)13が接続されている。
本実施の形態では、上記実施の形態とは異なる態様の電流センサについて説明する。図9は、本実施の形態に係る磁気平衡式の電流センサ2の構成例を示すブロック図である。なお、本実施の形態に係る電流センサ2と、実施の形態1に係る電流センサ1とは多くの点で共通する。このため、共通する構成については共通の符号を付して詳細な説明を省略する。
本実施の形態では、上記実施の形態とは異なる態様の電流センサについて説明する。図11は、本実施の形態に係る差動型の電流センサ3の構成例を示すブロック図である。なお、本実施の形態に係る電流センサ3と、実施の形態1に係る電流センサ1とは多くの点で共通する。このため、共通する構成については共通の符号を付して詳細な説明を省略する。
11,11a,11b 電流測定回路
12,12a,12b 増幅補正回路(第1の増幅補正回路)
13 増幅補正回路(第2の増幅補正回路)
21 フィードバックコイル
22 I/Vアンプ
121,121a,121b 演算増幅器
122,122a,122b 補正回路
131 演算増幅器
132 補正回路
221 演算増幅器
222 抵抗素子
M1~M4 磁気抵抗効果素子(磁電変換素子)
Claims (10)
- 磁電変換素子を有する電流測定回路と、前記電流測定回路の出力を増幅し、設定された第1の補正量に基づいてオフセットの温度特性を補正する第1の増幅補正回路と、前記第1の増幅補正回路の出力を増幅して感度を調整すると共に設定された第2の補正量に基づいて前記オフセットの大きさを補正する第2の増幅補正回路と、前記電流測定回路、前記第1の増幅補正回路、及び前記第2の増幅補正回路が設けられる基板と、を備える電流センサの製造方法であって、
前記磁電変換素子の特性に基づいて前記第1の補正量を設定した後、前記磁電変換素子を前記基板に実装し、前記第2の補正量を設定することを特徴とする電流センサの製造方法。 - 前記第1の補正量は、前記オフセットの温度特性の影響が小さくなるように設定されることを特徴とする請求項1記載の電流センサの製造方法。
- 前記磁電変換素子は、磁気抵抗効果素子であることを特徴とする請求項1又は請求項2記載の電流センサの製造方法。
- 前記電流センサは、外部磁界に比例する前記電流測定回路の出力を用いる磁気比例式であることを特徴とする請求項1から請求項3のいずれかに記載の電流センサの製造方法。
- 前記電流センサは、複数の前記電流測定回路の出力を差動演算する差動型であることを特徴とする請求項1から請求項4のいずれかに記載の電流センサの製造方法。
- 磁電変換素子を有する電流測定回路と、
前記電流測定回路の出力を増幅し、設定された第1の補正量に基づいてオフセットの温度特性を補正する第1の増幅補正回路と、
前記第1の増幅補正回路の出力を増幅して感度を調整すると共に設定された第2の補正量に基づいてオフセットの大きさを補正する第2の増幅補正回路と、
前記電流測定回路、前記第1の増幅補正回路、及び前記第2の増幅補正回路が設けられる基板と、を備えたことを特徴とする電流センサ。 - 前記第1の補正量は、前記オフセットの温度特性の影響が小さくなるように設定されたことを特徴とする請求項6記載の電流センサ。
- 前記磁電変換素子は、磁気抵抗効果素子であることを特徴とする請求項6又は請求項7記載の電流センサ。
- 外部磁界に比例する前記電流測定回路の出力を用いる磁気比例式であることを特徴とする請求項6から請求項8のいずれかに記載の電流センサ。
- 複数の前記電流測定回路の出力を差動演算する差動型であることを特徴とする請求項6から請求項9のいずれかに記載の電流センサ。
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EP13813725.2A EP2871486A4 (en) | 2012-07-06 | 2013-07-04 | METHOD FOR MANUFACTURING CURRENT SENSOR, AND CURRENT SENSOR |
JP2014523610A JP6143752B2 (ja) | 2012-07-06 | 2013-07-04 | 電流センサの製造方法及び電流センサ |
US14/540,978 US9702909B2 (en) | 2012-07-06 | 2014-11-13 | Manufacturing method for current sensor and current sensor |
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WO2019049410A1 (ja) * | 2017-09-06 | 2019-03-14 | 株式会社村田製作所 | 電流センサ及び電流センサの製造方法 |
JP2019174436A (ja) * | 2018-03-27 | 2019-10-10 | Tdk株式会社 | 磁気センサ |
US11099218B2 (en) | 2017-09-27 | 2021-08-24 | Murata Manufacturing Co., Ltd. | Current sensor |
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US8362807B2 (en) * | 2010-10-13 | 2013-01-29 | Taiwan Semiconductor Manufacturing Company, Ltd. | Offset compensation for sense amplifiers |
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US10516955B2 (en) * | 2017-03-31 | 2019-12-24 | Synaptics Incorporated | Correction of current measurement in an amplifier |
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