Current Sensor

Abstract

The current sensor may include a current detection unit that outputs a detection signal corresponding to a magnetic field generated in a conductor when a measurement current flows, and a signal processing unit that processes the detection signal to output an output signal. The signal processing unit may include a memory unit that stores a plurality of current sensitivity parameters corresponding to a plurality of current sensitivities that can be set for the current sensor, and a sensitivity setting unit that sets the current sensitivity of the current sensor based on one of the plurality of current sensitivity parameters stored in the memory unit.

Description

[Technical Field]

[0001] The present invention relates to a current sensor. [Background technology]

[0002] Patent Document 1 describes expanding the current measurement range by using two current sensors with different magnetic sensitivities. Patent Document 2 describes adjusting the current level of a current signal output from a Hall element using an amplifier. Patent Document 3 describes a sensitivity-switching sensor circuit that can significantly reduce sudden changes in signals when switching the amplification factor according to the magnitude of the input signal. [Prior art document] [Patent Documents] [Patent Document 1] Patent No. 6190537 specification [Patent Document 2] U.S. Patent Application Publication No. 2016 / 0313407 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-266738 Summary of the Invention [Problem to be solved by the invention]

[0003] There is a demand for a current sensor that can switch the current measurement range over a wide range. [Means for solving the problem]

[0004] A current sensor according to one aspect of the present invention may include a current detection unit that outputs a detection signal corresponding to a magnetic field generated in a conductor when a measurement current flows, and a signal processing unit that processes the detection signal to output an output signal. The signal processing unit may include a memory unit that stores a plurality of current sensitivity parameters corresponding to a plurality of current sensitivities that can be set for the current sensor. The signal processing unit may include a sensitivity setting unit that sets the current sensitivity of the current sensor based on one of the plurality of current sensitivity parameters stored in the memory unit.

[0005] In the current sensor, a plurality of current measurement ranges may be defined based on the plurality of current sensitivities, respectively.

[0006] In any of the current sensors, the signal processing unit may receive a selection signal from outside the current sensor, select one type of current sensitivity parameter from the plurality of current sensitivity parameters, and set the current sensitivity of the current sensor.

[0007] In any one of the current sensors, the sensitivity setting unit may include a receiving unit that receives a selection signal indicating information specifying the one type of current sensitivity parameter selected from the plurality of current sensitivity parameters.

[0008] In any of the current sensors, the multiple current measurement ranges may include a first current measurement range that defines a minimum range of current values ​​and a second current measurement range that defines a maximum range of current values, and the maximum range may be three times or more the minimum range.

[0009] In any of the current sensors, the plurality of current measurement ranges may include five or more types of current measurement ranges.

[0010] In any one of the current sensors, the current detection portion may include at least one magnetoelectric conversion element.

[0011] In any of the current sensors, the at least one magnetoelectric conversion element may be a Hall element, a magnetoresistive element, or a coil.

[0012] In any one of the current sensors, the sensitivity setting section may have an amplifier section that amplifies the detection signal output from the current detection section, and the plurality of current sensitivity parameters may include at least an amplification factor of the detection signal in the amplifier section.

[0013] In any of the current sensors, the sensitivity setting section may have a drive control section that outputs a drive current or a drive voltage to the current detection section, and the plurality of current sensitivity parameters may include at least a current value of the drive current or a voltage value of the drive voltage output from the drive control section.

[0014] In any of the current sensors, the at least one magnetoelectric conversion element may be a Hall element, and the Hall element may include a semiconductor made of group IV atoms or a compound semiconductor made of a combination of at least two types of group II, III, IV, V, and VI atoms.

[0015] In any one of the current sensors, the at least one magnetoelectric conversion element may be a TMR element having a first component of Co, Fe, and Ni, a second component of Mg and O, and a third component of Mn, and including at least one atom of the first component, at least one atom of the second component, and at least one atom of the third component.

[0016] In any of the current sensors, the sensitivity setting section may include an amplifier section that amplifies the detection signal output from the current detection section, and a drive control section that outputs a drive current to the current detection section, and the plurality of current sensitivity parameters may include an amplification factor of the detection signal in the amplifier section, and either a current value of the drive current or a voltage value of the drive voltage output from the drive control section.

[0017] In any of the current sensors, a plurality of current measurement ranges may be defined based on the plurality of current sensitivities. The plurality of current measurement ranges may include a first current measurement range group and a second current measurement range group. The amplification factors of the detection signals associated with the first current measurement range group may be different. The current values ​​of the drive currents or voltage values ​​of the drive voltages associated with the second current measurement range group may be different.

[0018] In any of the current sensors, the current values ​​of the drive currents or the voltage values ​​of the drive voltages associated with the first current measurement range group may be the same, and the amplification factors of the detection signals associated with the second current measurement range group may be the same.

[0019] The above summary of the invention does not list all of the features of the present invention, and subcombinations of these features may also be inventions. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 2 is a diagram illustrating an example of functional blocks of a current sensor according to the present embodiment. [Figure 2] FIG. 10 is a diagram showing an example of a table in which the current value of the drive current and the amplification factor of the amplifier are registered as current sensitivity parameters in association with each of a plurality of current measurement ranges. [Figure 3] 10 is a flowchart illustrating an example of a procedure for setting a current measurement range of a current sensor. DETAILED DESCRIPTION OF THE INVENTION

[0021] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the scope of the invention according to the claims. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0022] FIG. 1 is a diagram illustrating an example of functional blocks of a current sensor 10 according to this embodiment. The current sensor 10 measures a measurement current flowing through a conductor 20 disposed adjacent to the current sensor 10. The current sensor 10 includes a current detection unit 30 and a signal processing unit 100. The current detection unit 30 outputs a detection signal corresponding to a magnetic field generated in the conductor 20 when the measurement current flows. The current detection unit 30 includes at least one magnetoelectric conversion element. The at least one magnetoelectric conversion element may be a Hall element, a magnetoresistive element, or a coil. The Hall element may be a compound semiconductor made of at least two types of atoms from groups II, III, IV, V, and VI, such as InAs, GaAs, SiC, or ZnO, or a Hall element made of silicon (Si). The magnetoresistive element may be a giant magnetoresistive (GMR) element, a semiconductor magnetoresistive (SMR) element, an anisotropic magnetoresistive (AMR) element, or a tunneling magnetoresistive (TMR) element. The tunnel magnetoresistance (TMR) element may be, for example, a TMR element having Co, Fe, and Ni as a first component, Mg and O as a second component, and Mn as a third component, and including at least one of the atoms included in the first component, at least one of the atoms included in the second component, and all of the atoms included in the third component. The current sensor 10 of the magnetoresistance element has a selection signal input terminal that receives a current sensitivity selection signal. The current sensor 10 may have a VDD terminal and a VSS terminal that are connected to the high-voltage side and low-voltage side of a drive power supply. The current sensor 10 may also have an OUT terminal that outputs a current measurement signal.

[0023] The signal processing unit 100 processes the detection signal output from the current detection unit 30 to output an output signal. The signal processing unit 100 may be a signal processing IC configured with a large scale integrated circuit (LSI). The signal processing IC is a signal processing circuit configured with a Si monolithic semiconductor formed on a Si substrate. The signal processing circuit processes the detection signal output from the current detection unit 30 according to the magnitude of the magnetic field.

[0024] The signal processing unit 100 includes a sensitivity setting unit 110 and a storage unit 120. The storage unit 120 stores a plurality of current sensitivity parameters corresponding to a plurality of current sensitivities that can be set for the current sensor 10. The sensitivity setting unit 110 sets the current sensitivity of the current sensor 10 based on one type of current sensitivity parameter from the plurality of current sensitivity parameters stored in the storage unit 120. The signal processing unit 100 may receive a selection signal from outside the current sensor 10, select one type of current sensitivity parameter from the plurality of current sensitivity parameters, and set the current sensitivity of the current sensor 10.

[0025] The sensitivity setting unit 110 includes a drive control unit 102, an amplifier unit 104, and a reception unit 106. The drive control unit 102, the amplifier unit 104, and the reception unit 106 are an example of a sensitivity setting unit that sets the current sensitivity of the current sensor 10.

[0026] The drive control unit 102 supplies a drive current or drive voltage to the current detection unit 30 for driving the current detection unit 30. The drive control unit 102 has a constant current source or a constant voltage source, and supplies a drive current or drive voltage of a constant magnitude to the current detection unit 30. The drive control unit 102 refers to the memory unit 120, identifies the current value of the drive current or the voltage value of the drive voltage stored in the memory unit 120 as one of the current sensitivity parameters to be set, and supplies the current detection unit 30 with a drive current or drive voltage corresponding to the identified current value.

[0027] The amplifier 104 amplifies the detection signal output from the current detector 30 by a set amplification factor. The amplifier 104 is an example of an amplifier. The amplifier 104 may include multiple amplifiers. For example, if the amplifier is composed of a first amplifier and a second amplifier, the gain range that can be set in the first amplifier may be different from the gain range that can be set in the second amplifier. The gain range that can be set in the first amplifier may be wider than the gain range that can be set in the second amplifier. The setting interval of the gain that can be set in the first amplifier may be wider than the setting interval of the gain that can be set in the second amplifier. In this way, the gain adjustment is performed roughly by adjusting the gain of the first amplifier, and the gain adjustment is performed finely by adjusting the gain of the second amplifier.

[0028] The sensitivity setting unit 110 sets an amplification factor set in the amplifier unit 104. The sensitivity setting unit 110 refers to the storage unit 120, identifies the amplification factor of the amplifier unit 104 stored in the storage unit 120 as one of the current sensitivity parameters to be set, and sets the identified amplification factor in the amplifier unit 104. The sensitivity setting unit 110 also sets a current value of the drive current set in the drive control unit 102. The sensitivity setting unit 110 refers to the storage unit 120, identifies the current value of the drive current of the drive control unit 102 stored in the storage unit 120 as one of the current sensitivity parameters to be set, and sets the identified current value in the drive control unit 102.

[0029] The current sensor 10 may include an output unit that performs predetermined processing on the detection signal output from the amplifier unit 104 and outputs the processed output signal. The output unit may include an AD conversion unit that converts the detection signal, which is an analog signal output from the amplifier unit 104, into a digital signal. The output unit may include a ΔΣ AD converter or an integral AD converter as the AD conversion unit. The output unit may include a filter that filters the detection signal, which is an analog signal output from the amplifier unit 104. The output unit may include a low-pass filter that prevents aliasing errors from appearing in the detection signal converted into a digital signal by the AD conversion unit.

[0030] In the current sensor 10 configured as described above, the memory unit 120 stores multiple current sensitivity parameters for setting the current sensitivity of the current detection unit 30. For example, as shown in FIG. 2, the memory unit 120 may store a table in which the current sensitivity parameters, such as the current value (mA) of the drive current and the amplification factor of the amplifier unit 104, are registered. In addition to the current measurement range, the table may also store a magnetoelectric conversion coefficient (mT / A), which is the magnetic flux density incident on the current detection unit 30 when a measurement current flows through the conductor 20, and the magnetic sensitivity (mV / mT / mA) of the current detection unit 30. When multiple types of magnetoelectric conversion coefficients are registered in the table, the current sensor 10 may have multiple current detection units 30 with equivalent magnetic field sensitivities at different positions from the conductor 20. The concept of multiple magnetoelectric conversion elements with substantially the same magnetic field sensitivity includes not only multiple magnetoelectric conversion elements with the same magnetic sensitivity, but also multiple magnetoelectric conversion elements with variations in magnetic sensitivity due to manufacturing errors.

[0031] When multiple types of magnetic field sensitivities are registered in the table, the current sensor 10 may have multiple current detection units 30 with different sensitivities. The current sensitivity of the current sensor 10 is determined by the product of the magnetic sensitivity, the magnetoelectric conversion coefficient, the drive current, and the amplification factor.

[0032] The current sensor 10 thus configured has a plurality of current measurement ranges that are determined based on a plurality of current sensitivities, respectively. The plurality of current measurement ranges may be determined based on upper and lower limit values ​​at which the detection signal saturates according to the plurality of current sensitivities, for example.

[0033] The multiple current measurement ranges may include a first current measurement range group and a second current measurement range group. The gains associated with the first current measurement range group may be different, and the current values ​​of the drive currents may be the same. Meanwhile, the gains associated with the second current measurement range group may be the same, and the current values ​​of the drive currents or the voltage values ​​of the drive voltages may be different. The second current measurement range group may define a larger range of current values ​​than the first current measurement range group.

[0034] The receiving unit 106 receives a selection signal indicating information identifying a current sensitivity parameter to be set that has been selected from among a plurality of current sensitivity parameters. The receiving unit 106 may function as an input / output interface for inputting signals such as a selection signal from the outside or outputting signals to the outside. The receiving unit 106 may receive a selection signal indicating information identifying a current sensitivity parameter to be set that has been selected by a user from among the plurality of current sensitivity parameters. The receiving unit 106 may receive a selection signal indicating information identifying a current measurement range to be set from among a plurality of current measurement ranges. The plurality of current measurement ranges may be defined, for example, in five or more stages.

[0035] As shown in FIG. 2 , the multiple current measurement ranges are defined, for example, in five stages, including a first current measurement range defining a minimum range of current values ​​and a second current measurement range defining a maximum range of current values, with the maximum range of current values ​​being at least three times the minimum range of current values. Thus, with the current sensor 10 according to this embodiment, the current measurement range of the current sensor 10 is not fixed before shipment, and can be set to a more appropriate current measurement range desired by the user after shipment. This reduces the management costs and risks of inventory and procurement of the current sensor 10. Furthermore, since there is no need to set the current measurement range before shipment, the number of design steps required during the manufacturing stage of the current sensor 10 can be reduced.

[0036] FIG. 3 is a flowchart showing an example of a procedure for setting the current measurement range of the current sensor 10.

[0037] The receiving unit 106 receives a selection signal indicating information identifying a current sensitivity parameter to be set, selected from a plurality of current sensitivity parameters (S100). The selection signal may be included in a setting command signal output during an initial setting process or a setting update process of a system incorporating the current sensor 10. The selection signal may be included in a measurement command output when instructing the system incorporating the current sensor 10 to measure a current using the current sensor 10.

[0038] The sensitivity setting unit 110 refers to the storage unit 120 and, based on the information specifying the current sensitivity parameter to be set indicated by the selection signal, specifies the amplification factor of the amplifier unit 104 and the current value of the drive current of the drive control unit 102, which are stored in the storage unit 120 as the current sensitivity parameter to be set (S102). The sensitivity setting unit 110 sets the specified amplification factor in the amplifier unit 104 and sets the specified current value in the drive control unit 102 (S104).

[0039] As described above, according to the present embodiment, the current measurement range of the current sensor 10 is not fixed before shipping, and can be set to a more appropriate current measurement range desired by the user after shipping. This reduces the management costs and risks of inventory or procurement of the current sensor 10. Furthermore, since it is not necessary to set the current measurement range before shipping, the number of design steps required during the manufacturing stage of the current sensor 10 can be reduced.

[0040] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0041] It should be noted that the execution order of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not specifically stated as "before," "prior to," etc., and that the processes can be performed in any order unless the output of a previous process is used in a subsequent process. Even if the operational flow in the claims, specifications, and drawings is described using "first," "next," etc. for convenience, this does not mean that the processes must be performed in this order. [Explanation of symbols]

[0042] 10 Current Sensor 20 Conductors 30 Current detection section 100 signal processing section 102 Drive control unit 104 Amplification section 106 Reception 110 Sensitivity setting section 120 Storage section

Claims

1. a current detection unit that outputs a detection signal corresponding to a magnetic field generated in a conductor when a measurement current flows; A current sensor including a signal processing unit that processes the detection signal to output an output signal, The signal processing unit a storage unit that stores a plurality of current sensitivity parameters corresponding to a plurality of current sensitivities that can be set for the current sensor; a sensitivity setting unit that sets the current sensitivity of the current sensor based on one type of current sensitivity parameter among the plurality of current sensitivity parameters stored in the storage unit, The sensitivity setting unit a receiving unit that receives a selection signal indicating information that identifies the one type of current sensitivity parameter selected from the plurality of current sensitivity parameters; A current sensor that receives the selection signal from outside the current sensor via the receiving unit, selects the one type of current sensitivity parameter from the plurality of current sensitivity parameters, and sets the current sensitivity of the current sensor.

2. A current sensor as described in claim 1, wherein the selection signal is included in a setting command signal output during initial setting processing or setting update processing of a system equipped with the current sensor, or in a measurement command signal output when instructing the system to measure current using the current sensor.

3. The current sensor according to claim 1 , wherein a plurality of current measurement ranges are defined based on the plurality of current sensitivities, respectively.

4. A current sensor as described in Claim 3, wherein each of the multiple current measurement ranges is determined based on upper and lower limit values ​​at which the detection signal saturates according to multiple current sensitivities.

5. a VDD terminal and a VSS terminal connected to a drive power supply; an OUT terminal for outputting the output signal; The current sensor according to claim 1 , further comprising a selection signal input terminal that receives the selection signal from an external device.

6. 4. The current sensor according to claim 3, wherein the plurality of current measurement ranges include a first current measurement range that defines a minimum range of current values ​​and a second current measurement range that defines a maximum range of current values, and the maximum range is at least three times the minimum range.

7. The current sensor according to claim 6 , wherein the plurality of current measurement ranges include five or more types of current measurement ranges.

8. 8. The current sensor according to claim 1, wherein the current detection portion includes at least one magnetoelectric conversion element.

9. The current sensor according to claim 8 , wherein the at least one magnetoelectric transducer is a Hall element, a magnetoresistive element, or a coil.

10. the sensitivity setting unit has an amplifier unit that amplifies the detection signal output from the current detection unit, The current sensor according to claim 1 , wherein the plurality of current sensitivity parameters include at least an amplification factor of the detection signal in the amplifier section.

11. the sensitivity setting unit has a drive control unit that outputs a drive current or a drive voltage to the current detection unit, The current sensor according to claim 1 , wherein the plurality of current sensitivity parameters include at least a current value of a drive current or a voltage value of a drive voltage output from the drive control unit.

12. the at least one magnetoelectric conversion element is a Hall element, 10. The current sensor according to claim 9, wherein the Hall element includes a semiconductor made of group IV atoms or a compound semiconductor made of a combination of at least two types of group II, group III, group IV, group V, and group VI atoms.

13. the at least one magnetoelectric transducer is a magnetoresistive element; 10. The current sensor of claim 9, wherein the magnetoresistive element is a TMR having Co, Fe, and Ni as a first component, Mg and O as a second component, and Mn as a third component, and including at least one atom of the atoms contained in the first component, at least one atom of the atoms contained in the second component, and at least one atom of the atoms contained in the third component.

14. The sensitivity setting unit an amplifier that amplifies the detection signal output from the current detector; a drive control unit that outputs a drive current to the current detection unit; and 2. The current sensor according to claim 1, wherein the plurality of current sensitivity parameters include an amplification factor of the detection signal in the amplifier section, and either a current value of a drive current or a voltage value of a drive voltage output from the drive control section.

15. a plurality of current measurement ranges are determined based on the plurality of current sensitivities, respectively; the plurality of current measurement ranges include a first current measurement range group and a second current measurement range group; the amplification factors of the detection signals associated with the first current measurement range group are different; The current sensor according to claim 14 , wherein the current values ​​of the drive currents or voltage values ​​of the drive voltages associated with the second current measurement range group are different.

16. a current detection unit that outputs a detection signal corresponding to a magnetic field generated in a conductor when a measurement current flows; A current sensor including a signal processing unit that processes the detection signal to output an output signal, The signal processing unit a storage unit that stores a plurality of current sensitivity parameters corresponding to a plurality of current sensitivities that can be set for the current sensor; a sensitivity setting unit that sets the current sensitivity of the current sensor based on one type of current sensitivity parameter among the plurality of current sensitivity parameters stored in the storage unit, The sensitivity setting unit an amplifier that amplifies the detection signal output from the current detector; a drive control unit that outputs a drive current to the current detection unit; a receiving unit that receives a selection signal indicating information that identifies the one type of current sensitivity parameter selected from the plurality of current sensitivity parameters, the plurality of current sensitivity parameters include an amplification factor of the detection signal in the amplifier unit, and either a current value of a drive current or a voltage value of a drive voltage output from the drive control unit, a plurality of current measurement ranges are determined based on the plurality of current sensitivities, respectively; the plurality of current measurement ranges include a first current measurement range group and a second current measurement range group that defines a range of current values ​​larger than the first current measurement range group; the amplification factors of the detection signals associated with the first current measurement range group are different; the current values ​​of the driving currents or the voltage values ​​of the driving voltages associated with the second current measurement range group are different, The sensitivity setting unit receives the selection signal from outside the current sensor via the receiving unit, selects the one type of current sensitivity parameter from the plurality of current sensitivity parameters, and sets the current sensitivity of the current sensor.

17. the current values ​​of the driving currents or the voltage values ​​of the driving voltages associated with the first current measurement range group are the same, The current sensor according to claim 15 or 16, wherein the amplification factors of the detection signals associated with the second group of current measurement ranges are the same.

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