Current sensor, current measurement device, and current measurement method

Abstract

The invention provides a current sensor, a current measuring device and a current measuring method, which can suppress the reduction of the current measuring precision caused by the skin effect. This current sensor is provided with: a shield having an opening for introducing into the interior a magnetic field generated by a current flowing through a conductor; a magnetic field sensor which is disposed in the shield and outputs a sensor voltage corresponding to the magnetic field at the position of the magnetic field sensor; and a detection circuit that is disposed outside the shield and that detects a current on the basis of a sensor voltage of the magnetic field sensor, the magnetic field sensor including a first magnetic field sensor that detects a low-frequency magnetic field and a second magnetic field sensor that detects a high-frequency magnetic field, the detection circuit being configured to detect the current on the basis of the sensor voltage of the magnetic field sensor. The first magnetic field sensor is disposed near the opening, and the second magnetic field sensor is disposed farther from the opening than the first magnetic field sensor.

Description

Technical Field

[0001] This invention relates to current sensors, current measuring devices, and current measuring methods. Background Technology

[0002] There is a method for detecting the magnetic field generated by a current flowing in a conductor in order to measure the current flowing in the conductor. If the frequency of the current increases, a skin effect occurs in the conductor, which may reduce the accuracy of the magnetic field detection and, consequently, the accuracy of the current measurement. For example, in Patent Document 1, in order to reduce the influence of the skin effect, the output signals of the two electromagnetic conversion elements are subtracted from each other.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2014-115114

[0004] To prevent the influence of magnetic fields other than those generated by the current flowing in the conductor, it is considered to cover the conductor with a shield. However, Patent Document 1 does not specifically address countermeasures for the skin effect when using a shield. Summary of the Invention

[0005] One aspect of the present invention is to suppress the decrease in the accuracy of current measurement caused by the skin effect.

[0006] One aspect of the present invention relates to a current sensor comprising: a shield having an opening for introducing a magnetic field generated by a current flowing in a conductor into the interior; a magnetic field sensor disposed within the shield and outputting a sensor voltage corresponding to the magnetic field at its location; and a detection circuit disposed outside the shield for detecting the current based on the sensor voltage of the magnetic field sensor. The magnetic field sensor includes a first magnetic field sensor and a second magnetic field sensor, the first magnetic field sensor detecting low-frequency magnetic fields and the second magnetic field sensor detecting high-frequency magnetic fields. Compared to the second magnetic field sensor, the first magnetic field sensor is disposed closer to the opening, and compared to the first magnetic field sensor, the second magnetic field sensor is disposed farther from the opening.

[0007] One aspect of the present invention relates to a current sensor comprising: a shield having an opening for introducing a magnetic field generated by a current flowing in a conductor into the interior; a magnetic field sensor disposed within the shield and outputting a sensor voltage corresponding to the magnetic field at its location; a detection circuit disposed outside the shield for detecting the current based on the sensor voltage of the magnetic field sensor; and a moving mechanism for moving the magnetic field sensor, the magnetic field sensor comprising a first magnetic field sensor and a second magnetic field sensor, the first magnetic field sensor being disposed near the opening for detecting low-frequency magnetic fields, the second magnetic field sensor being for detecting high-frequency magnetic fields, and the moving mechanism moving the second magnetic field sensor between a position near the opening and a position far from the opening.

[0008] One aspect of the present invention relates to a current measuring device comprising: a shield having an opening for introducing a magnetic field generated by a current flowing in a conductor into the interior; a magnetic field sensor disposed within the shield and outputting a sensor voltage corresponding to the magnetic field at its location; a detection circuit disposed outside the shield and generating a detection voltage representing the value of the current based on the sensor voltage of the magnetic field sensor; and an external device disposed outside the shield for calibrating the detection voltage in a frequency region.

[0009] One aspect of the present invention relates to a current measurement method comprising the steps of: detecting a magnetic field at a location of a magnetic field sensor disposed within a shield having an opening for introducing a magnetic field generated by a current flowing in a conductor into the interior; and detecting the current based on the detection result of the magnetic field sensor, wherein the magnetic field sensor comprises a first magnetic field sensor and a second magnetic field sensor, the first magnetic field sensor detecting a low-frequency magnetic field and the second magnetic field sensor detecting a high-frequency magnetic field, the first magnetic field sensor being disposed closer to the opening than the second magnetic field sensor, and the second magnetic field sensor being disposed farther from the opening than the first magnetic field sensor.

[0010] The effects of the invention

[0011] According to the present invention, the decrease in the accuracy of current measurement caused by the skin effect can be suppressed. Attached Figure Description

[0012] Figure 1 This is a diagram illustrating an example of the schematic structure of the current measuring device 100 according to the embodiment.

[0013] Figure 2 This is a diagram showing an example of the general structure of shielding component 3.

[0014] Figure 3 This is a diagram showing an example of detection circuit 6.

[0015] Figure 4 This is a diagram showing an example of the schematic structure of current sensor 1.

[0016] Figure 5 This is a diagram representing examples of nearby and distant areas.

[0017] Figure 6 This is a diagram illustrating an example of an action.

[0018] Figure 7 This is a diagram illustrating an example of an action.

[0019] Figure 8 This is a diagram illustrating an example of frequency characteristics.

[0020] Figure 9 This is a flowchart illustrating an example of the processing (current measurement method) performed in current sensor 1.

[0021] Figure 10 This is a diagram showing an example of the schematic structure of current sensor 1.

[0022] Figure 11 This is a diagram showing an example of the schematic structure of detection circuit 6.

[0023] Figure 12 This is a diagram illustrating an example of how to determine the presence or absence of the skin effect.

[0024] Figure 13 This is a diagram illustrating an example of how to determine the presence or absence of the skin effect.

[0025] Figure 14 This is a flowchart illustrating an example of the processing (current measurement method) performed in current sensor 1.

[0026] Figure 15 This is a diagram showing an example of the schematic structure of current sensor 1.

[0027] Figure 16 This is a diagram showing an example of the schematic structure of detection circuit 6.

[0028] Figure 17 This is a flowchart illustrating an example of the processing (current measurement method) performed in current sensor 1.

[0029] Figure 18 This is a diagram showing an example of the schematic structure of current sensor 1.

[0030] Figure 19 This is a diagram showing an example of the schematic structure of the detection circuit 6 and the external device 2.

[0031] Figure 20 This is a diagram showing an example of the waveform of the detection voltage V3 before correction.

[0032] Figure 21 This is a diagram showing an example of the frequency components of the detection voltage V3 before correction.

[0033] Figure 22 This is a diagram illustrating an example of the correction of the frequency component of the detection voltage V3.

[0034] Figure 23 This is a diagram illustrating an example of the inverse Fourier transform.

[0035] Figure 24 This is a flowchart illustrating an example of a process (current measurement method) performed in the current measuring device 100. Detailed Implementation

[0036] Hereinafter, the embodiments will be described with reference to the accompanying drawings. The same reference numerals will be used for the same elements, and repeated descriptions will be omitted where appropriate.

[0037] Figure 1 This is a diagram illustrating an example of the schematic structure of the current measuring device 100 according to the embodiment. The current measuring device 100 includes a current sensor 1 and an external device 2.

[0038] Current sensor 1 detects the current flowing in conductor 9. Current sensor 1 is used in conjunction with external device 2. Figure 1 In the example shown, external device 2 is an oscilloscope, for example, displaying the waveform of the current detected by current sensor 1. Figure 1 The input terminal 21 and display unit 23 of the external device 2 are shown by the labels.

[0039] Conductor 9 is used, for example, in hybrid vehicles (HV) and electric vehicles (EV), to carry currents ranging from several amperes to tens of amperes or greater. Examples of conductor 9 are cables and buses used to connect batteries and power units, or to connect converters and inverters.

[0040] The current flowing through conductor 9 is called current I and is illustrated. The arrows in the diagram schematically indicate the direction of current I. Current I can be either direct current or alternating current. The frequency (fundamental frequency) of current I is called frequency f. The current I flowing through conductor 9 generates a magnetic field. This magnetic field is called magnetic field H and is illustrated. The arrows in the diagram schematically indicate the direction of magnetic field H.

[0041] The diagram also illustrates the XYZ coordinate system. The Z-axis corresponds to the extension direction of conductor 9. The X-axis and Y-axis (XY plane directions) correspond to the cross-sectional directions of conductor 9. The positive and negative X-axis directions are also referred to as left-right directions, etc. The positive and negative Y-axis directions are also referred to as up-down directions, etc. The positive and negative Z-axis directions are also referred to as front-back directions, etc.

[0042] The current sensor 1 includes a shield 3, a magnetic field sensor 4, an external unit 5, and a detection circuit 6. Figure 1 In the example shown, shield 3 contains magnetic field sensor 4, and external unit 5 contains detection circuit 6. Shield 3 corresponds to the head portion (sensor head) of current sensor 1 and is used in close proximity to conductor 9. External unit 5 is connected to input terminal 21 of external device 2.

[0043] The shielding element 3 is configured to isolate the magnetic field. The shielding element 3 is also called a magnetic field shielding element. Various known materials, such as metals, can be used.

[0044] The shield 3 has an opening 37. The opening 37 is used to introduce a portion of the magnetic field H generated by the current flowing in the conductor 9 into the interior. In this example, the opening 37 is formed by cutting a portion of the lower part of the shield 3. The opening 37 is also referred to as a cut-out.

[0045] The shielding member 3 can be installed on the conductor 9 such that the conductor 9 passes through the opening 37 of the shielding member 3, or the shielding member 3 can be fixed in a way that keeps the position of the conductor 9 unchanged. There are no particular limitations on the installation and fixing methods. For example, near the opening 37 of the shielding member 3, a hook-shaped member, a ring-shaped member, or the like can be used to install the shielding member 3 (the sensor head) on the conductor 9, or a spring member or the like can be used to fix its mounting part.

[0046] Figure 2 This is a diagram illustrating an example of the schematic structure of the shielding member 3. The shielding member 3 has a hollow, approximately box-like shape. The shielding member 3 includes a base plate 31, a top plate 32, side plates 33, 34, 35, and 36. The shape of the shielding member 3, which is magnetically attached or coupled to the base plate 31 to the side plates 36 respectively, is defined such that the shielding member 3 has an internal space 30 and an opening 37.

[0047] The base plate 31 and the upper plate 32 are located on opposite sides of each other in the vertical direction (Y-axis direction) separated by the internal space 30, and extend relative to each other with the XZ plane as the surface direction. The base plate 31, the internal space 30 and the upper plate 32 are located sequentially in the positive Y-axis direction.

[0048] Side plates 33 and 34 are located on opposite sides of each other in the left-right direction (X-axis direction) separated by the internal space 30, and extend relative to each other with the YZ plane as the surface direction. Side plates 33, internal space 30 and side plates 34 are located sequentially in the positive X-axis direction.

[0049] Side plates 35 and 36 are located on opposite sides of each other in the front-to-back direction (Z-axis direction) separated by the internal space 30, and extend relative to each other with the XY plane as the surface direction. Side plates 35, internal space 30 and side plates 36 are located sequentially in the positive Z-axis direction.

[0050] In this example, the opening 37 is formed by cutting a portion of the base plate 31, side plate 35, and side plate 36, and is integrally present throughout the front-back direction (Z-axis direction) of the shield 3. The area (size) of the opening 37 in the XY plane direction is designed to allow the conductor 9 to pass through the opening 37.

[0051] Unless otherwise specified, the mention of "within shielding component 3" refers to the internal space 30 of shielding component 3. Where there is no contradiction, "within shielding component 3" and "internal space 30" can be appropriately substituted.

[0052] Return to Figure 1 The magnetic field H generated by the current I flowing in the conductor 9 in the portion of the shield 3 located at the opening 37 is introduced into the shield 3 through the opening 37.

[0053] A magnetic field sensor 4 is disposed within a shield 3 to detect the magnetic field at its location. Magnetic fields other than magnetic field H (which could potentially cause external interference) are isolated by the shield 3, thus the magnetic field sensor 4 detects magnetic field H at its location. The detection of magnetic field H includes detecting its magnitude and, possibly, its orientation.

[0054] Specifically, the magnetic field sensor 4 outputs a sensor voltage corresponding to the magnetic field H at its location. With the shield 3 installed and fixed to the conductor 9, the relationship between the current I (magnitude and orientation) flowing in the conductor 9 and the sensor voltage is uniquely determined. This relationship can be known in advance, for example, based on the design of the shield 3 and the magnetic field sensor 4, the specifications of the conductor 9, experimental data, etc.

[0055] Magnetic field sensor 4 can be multiple magnetic field sensors. Figure 1 In the example shown, there are two magnetic field sensors. The first magnetic field sensor is referred to as magnetic field sensor 41 and illustrated. The second magnetic field sensor is referred to as magnetic field sensor 42 and illustrated. Unless otherwise specified, they are simply referred to as magnetic field sensor 4.

[0056] Magnetic field sensors 41 and 42 have different detection characteristics. Magnetic field sensor 41 detects lower frequency magnetic fields (low-frequency magnetic fields). Low-frequency magnetic fields include DC magnetic fields. Magnetic field sensor 42 detects higher frequency magnetic fields (high-frequency magnetic fields). The cutoff frequencies of the low-frequency and high-frequency magnetic fields need to overlap.

[0057] Various known magnetic field sensors can be used. An example of magnetic field sensor 41 is an IC (Integrated Circuit) sensor containing a Hall element, also known as an analog Hall IC, etc. An example of magnetic field sensor 42 is a coil sensor containing a coil. Rogowski coils can be used, enabling miniaturization, and correspondingly, facilitating the placement of magnetic field sensor 42 within the shield 3.

[0058] Unless otherwise specified, magnetic field sensor 41 is configured to include an IC sensor. Magnetic field sensor 42 is configured to include a coil sensor. The sensor voltage output by magnetic field sensor 41 is referred to as sensor voltage V1. The sensor voltage output by magnetic field sensor 42 is referred to as sensor voltage V2. Unless otherwise specified, they are also simply referred to as sensor voltage, etc.

[0059] The sensor voltage V1 of magnetic field sensor 41 and the sensor voltage V2 of magnetic field sensor 42 are led out of the shield 3 and supplied to the detection circuit 6 inside the external unit 5. Figure 1 In the example shown, the shield 3 has a terminal 38. Inside the shield 3, magnetic field sensors 41 and 42 are connected to the terminal 38, for example, via wiring (not shown). Outside the shield 3, the terminal 38 is connected to the detection circuit 6 in the external unit 5 via wiring W1.

[0060] The detection circuit 6 is disposed outside the shield 3, and detects the current I based on the sensor voltage of the magnetic field sensor 4, and in this example, the sensor voltage V1 of the magnetic field sensor 41 and the sensor voltage V2 of the magnetic field sensor 42. See also... Figure 3 Please provide an explanation.

[0061] Figure 3 This diagram illustrates an example of detection circuit 6. Detection circuit 6 combines sensor voltage V1 and sensor voltage V2 to generate detection voltage V3. Detection voltage V3 is a voltage representing the value of current I, and more specifically, it can be a voltage representing its instantaneous value. This detection voltage V3 corresponds to the detection result of detection circuit 6, that is, the detection result of current sensor 1 on current I, and further, the measurement result of current measuring device 100 on current I.

[0062] As previously explained, the relationship between the current I flowing in conductor 9 and the sensor voltages of magnetic field sensors 4, namely, the sensor voltage V1 of magnetic field sensor 41 and the sensor voltage V2 of magnetic field sensor 42, is known in advance. Based on this relationship, the detection circuit 6 is designed to generate the detection voltage V3 according to the sensor voltages V1 and V2.

[0063] Specifically, in Figure 3 In the example shown, the detection circuit 6 includes a synthesis unit 61. The synthesis unit 61 synthesizes the sensor voltage V1 and the sensor voltage V2 to obtain the detection voltage V3. An example of synthesis is addition, more specifically, weighted addition. The synthesis unit 61 performs the operation shown, for example, in the following equation (1). In the equation, the coefficient α is the weighting coefficient (also called gain) multiplied by the sensor voltage V1. The coefficient β is the weighting coefficient multiplied by the sensor voltage V2.

[0064] V3=α×V1+β×V2 (1)

[0065] Return to Figure 1 External unit 5 outputs a detection voltage V3 generated by detection circuit 6. The output target is an external device 2 located outside shielding 3, an example of which is an oscilloscope. Based on the detection voltage V3 from detection circuit 6, the waveform of current I is displayed, or its calculated maximum, minimum, frequency, etc. are displayed.

[0066] Here, as the frequency f of the current I increases, the likelihood of the skin effect occurring in conductor 9 increases. Hereafter, the skin effect of conductor 9 will sometimes be simply referred to as the skin effect.

[0067] The distribution of the magnetic field H within the shield 3 differs between the case where the skin effect is present (with skin effect) and the case where it is absent (without skin effect). Depending on the location within the shield 3, even if the magnitude of the current I is the same, the magnitude of the magnetic field H at that location varies depending on whether the skin effect is present or not.

[0068] Due to the skin effect, the frequency characteristics in the high-frequency region change, particularly the sensor voltage V2 of the magnetic field sensor 42, which detects high-frequency magnetic fields, and consequently the detection voltage V3. As a result, the accuracy of current I measurement decreases. This problem can be addressed using publicly available techniques. Two main methods exist, which will be explained in sequence.

[0069] <Method 1>

[0070] In the first method, the configuration of the magnetic field sensor 41 and magnetic field sensor 42 within the shielding component 3 is investigated. (Refer to...) Figures 4 to 17 Please provide an explanation.

[0071] Figure 4 This is a diagram illustrating an example of the schematic structure of the current sensor 1. The diagram schematically shows the configuration of the magnetic field sensor 4 within the shield 3 when viewed in the front-to-back direction (Z-axis direction).

[0072] Compared to magnetic field sensor 42, magnetic field sensor 41 is positioned closer to opening 37. Compared to magnetic field sensor 41, magnetic field sensor 42 is positioned farther from opening 37. Conductor 9 passes through opening 37, so their positions can be considered substantially the same. In this sense, conductor 9 and opening 37 can be appropriately interchanged. That is, it can also be said that magnetic field sensor 41 is positioned closer to conductor 9, and magnetic field sensor 42 is positioned farther from conductor 9.

[0073] More specifically, the magnetic field sensor 41 is disposed in the vicinity of the conductor 9. The vicinity is the region where the magnitude of the magnetic field H varies depending on the presence or absence of the skin effect. The magnetic field sensor 42 is disposed in the distal region of the conductor 9. The distal region is the region where the magnitude of the magnetic field H does not vary depending on the presence or absence of the skin effect. Furthermore, the statement that the magnitude of the magnetic field H does not change can be interpreted as including (negligible) minute magnetic field variations that have almost no effect on the sensor voltage V2 of the magnetic field sensor 42. For the vicinity and distal regions, refer to... Figure 5 Please provide an explanation.

[0074] Figure 5 This is a diagram showing examples of nearby and distant regions. The horizontal axis of the graph represents the distance from the center of conductor 9. The vertical axis represents the magnitude of the magnetic field H. Furthermore, the magnitude of the magnetic field H can be magnetic flux density, and these can be interchanged as appropriate. The solid curve represents the magnetic field H when the skin effect is not present (no skin effect). The dashed curve represents the magnetic field H when the skin effect is present (skin effect present).

[0075] As understood, in the region near the surface of conductor 9, the magnetic field H varies depending on the presence or absence of the skin effect. This region corresponds to the vicinity region. In the region of conductor 9 that is somewhat separated from the surface, the magnetic field H does not vary depending on the presence or absence of the skin effect. This region corresponds to the distant region. Figure 5 In the example shown, the magnitude of the magnetic field H decreases in the vicinity due to the skin effect.

[0076] Return to Figure 4 Magnetic field sensor 41 is disposed in the nearby area as described above, and outputs a sensor voltage V1 corresponding to the magnetic field H at its location. Magnetic field sensor 42 is disposed in the distant area as described above, and outputs a sensor voltage V2 corresponding to the magnetic field H at its location.

[0077] Figure 6 and Figure 7 This is a diagram illustrating an example of an action. Figure 6 The diagram shows the magnetic field H within the shield 3 when the skin effect is not present. The magnetic field H at the location (nearby area) of the magnetic field sensor 41 is referred to as magnetic field H11 and illustrated. The magnetic field H at the location (far area) of the magnetic field sensor 42 is referred to as magnetic field H21 and illustrated. Figure 7 The diagram shows the magnetic field H within the shield 3 when the skin effect occurs. The magnetic field H at the location of the magnetic field sensor 41 at this time is referred to as magnetic field H12 and is illustrated. The magnetic field H at the location of the magnetic field sensor 42 is referred to as magnetic field H22 and is illustrated.

[0078] At the location of magnetic field sensor 41, the magnetic field H varies depending on the presence or absence of the skin effect. Therefore, magnetic field H12 is different from magnetic field H11. At the location of magnetic field sensor 42, the magnetic field H does not vary depending on the presence or absence of the skin effect. Therefore, magnetic field H22 is the same as magnetic field H21.

[0079] Based on the sensor voltages V1 and V2 of the magnetic field sensors 41 and 42 configured as described above, the detection circuit 6 generates a detection voltage V3. The synthesis unit 61 of the detection circuit 6, for example as described in equation (1) above, synthesizes the sensor voltages V1 and V2 to obtain the detection voltage V3.

[0080] In one embodiment, the synthesis unit 61 of the detection circuit 6 may also synthesize the sensor voltage V1 and the sensor voltage V2 in a manner that keeps the frequency gain characteristic of the detection voltage V3 constant relative to the current I. See also... Figure 8 Please provide an explanation.

[0081] Figure 8 This is a graph illustrating an example of frequency characteristics. The horizontal axis of the graph represents the frequency f of the current I. The vertical axis of the graph represents the gain. The gain represents the gain relative to the current I up to the output of the detection circuit 6 (corresponding to the output of the synthesis unit 61).

[0082] Curve Ce represents the frequency characteristics of the skin effect. Based on the skin effect, the detection level of the magnetic field is divided into a low-frequency region with constant gain and a high-frequency region with decreasing gain. The cutoff frequency is set between these two regions.

[0083] In the synthesis section 61 (e.g., the aforementioned) Figure 3 The following Figure 11 In the example (e.g.), a first-order low-pass filter is applied to the sensor voltage V1 as the cutoff frequency. Similarly, a first-order high-pass filter is applied to the sensor voltage V2 as the cutoff frequency.

[0084] Furthermore, in the synthesis unit 61, the gain of each sensor voltage V1 and sensor voltage V2 is adjusted so that their detection voltages are at the same level. The signal obtained by adding the signals of sensor voltage V1 and sensor voltage V2 after this level adjustment is synthesized is output as the detection voltage V3. Thus... Figure 8 As shown in curve V3, a frequency response with constant gain can be obtained.

[0085] For the sensor voltage V1 of the magnetic field sensor 41, since the frequency region above the cutoff frequency is cut off due to the skin effect, the magnetic field sensor 41 is not affected by the skin effect even when it is placed near the opening 37. By using the sensor voltage V1 of the magnetic field sensor 41 placed near the conductor 9, the magnetic field H can be detected with high accuracy, and thus the current I can be measured with high accuracy.

[0086] Regarding the sensor voltage V2 of the magnetic field sensor 42, since the magnetic field sensor 42 is located far from the opening 37, it is not affected by the skin effect. The frequency region lower than the cutoff frequency is cut off to supplement the frequency region cut off by the sensor voltage V1 of the magnetic field sensor 41, thereby ensuring the high-frequency region. Because the position (far region) of the magnetic field sensor 42 is not affected by the skin effect, the magnetic field H can be detected with high accuracy compared to the case where it is located in the nearby region, thus enabling high-accuracy measurement of the current I.

[0087] As explained above, by studying the configuration of the magnetic field sensor 41 and magnetic field sensor 42 within the shield 3, the decrease in the measurement accuracy of current I caused by the skin effect can be suppressed.

[0088] Figure 9 This is a flowchart illustrating an example of the processing (current measurement method) performed in current sensor 1. Content that is repeated in the preceding description has been appropriately omitted.

[0089] In step S1, magnetic field H is detected using magnetic field sensors 41 and 42. Magnetic field sensor 41 outputs a sensor voltage V1 corresponding to the magnetic field H at its location within the shielding member 3. Magnetic field sensor 42 outputs a sensor voltage V2 corresponding to the magnetic field H at its location within the shielding member 3.

[0090] In step S2, the current I is detected based on the detection results of magnetic field sensor 41 and magnetic field sensor 42. The detection circuit 6, located outside the shield 3, generates a detection voltage V3 representing the current I based on the sensor voltage V1 from magnetic field sensor 41 and the sensor voltage V2 from magnetic field sensor 42.

[0091] <Determination of the presence or absence of skin effect>

[0092] An effective technique can be obtained as long as it can be determined whether the skin effect of conductor 9 has occurred (whether the skin effect exists or not). For an example of a determination method, see [reference needed]. Figures 10 to 14 Please provide an explanation.

[0093] Figure 10This is a diagram showing an example of the schematic structure of the current sensor 1. In this example, the magnetic field sensor 41 is configured to include not only an IC sensor but also a coil sensor so that not only low-frequency magnetic fields but also high-frequency magnetic fields can be detected. The sensor voltage V1 of the magnetic field sensor 41 includes the sensor voltage V11 output by the IC sensor and the sensor voltage V12 output by the coil sensor. The magnetic field sensor 42 is configured to include a coil sensor as before and outputs the sensor voltage V2.

[0094] Figure 11 This is a diagram showing an example of the schematic structure of the detection circuit 6. The detection circuit 6 includes a determination unit 62 in addition to the synthesis unit 61.

[0095] The determination unit 62 determines whether skin effect has occurred based on the sensor voltage V1 of the magnetic field sensor 41 and the sensor voltage V2 of the magnetic field sensor 42. More specifically, the determination unit 62 determines the presence or absence of skin effect based on the ratio between the sensor voltage V12 of the coil sensor included in the magnetic field sensor 41 and the sensor voltage V2 of the coil sensor included in the magnetic field sensor 42. The ratio is called the ratio R. As an example, the ratio R is set as the ratio of the sensor voltage V2 to the sensor voltage V12 (i.e., R = V2 / V12).

[0096] Figure 12 and Figure 13 This is a diagram showing an example of the determination of the presence or absence of skin effect. Figure 12 The horizontal axis of the graph represents measurements under different conditions. Examples of conditions are the type of the conductor 9, the frequency f of the current I, etc. In this example, the measurements according to five different conditions are represented as measurements N1 to N5. The vertical axis of the graph represents the ratio R. The markings in the graph represent the ratio R in each measurement.

[0097] The value of the ratio R is roughly classified into two values according to the presence or absence of skin effect. This is because, according to the presence or absence of skin effect, the sensor voltage V12 of the magnetic field sensor 41 changes, while the sensor voltage V2 of the magnetic field sensor 42 does not change. The value of the ratio R when skin effect has not occurred is called the reference value R0.

[0098] When skin effect occurs, the magnitude of the magnetic field H in the nearby area changes, and thus the sensor voltage V12 of the magnetic field sensor 41 also changes. The ratio R deviates from the reference value R0. For example, as previously described Figure 5 when the magnitude of the magnetic field H in the nearby area becomes smaller, the ratio R becomes larger and deviates from the reference value R0.

[0099] When the ratio R is close to (or equal to) the reference value R0, the detection circuit 6 determines that no skin effect has occurred. When this is not the case, i.e., when the ratio R deviates from the reference value R0, the detection circuit 6 determines that a skin effect has occurred. The determination of whether the ratio R is close to the reference value R0 can, for example, use a threshold determination based on the absolute value of the difference between the ratio R and the reference value R0 (|R-R0|).

[0100] like Figure 13 As shown, in measurements N1, N3, and N4, the ratio R was close to the reference value R0, therefore it was determined that no skin effect occurred. Conversely, in measurements N2 and N5, the ratio R deviated from the reference value R0, therefore it was determined that a skin effect occurred.

[0101] Return to Figure 11 An application example of the determination result of the determination unit 62 will be described. In one embodiment, the detection circuit 6 can selectively use the sensor voltage V1 of the magnetic field sensor 41 and the sensor voltage V2 of the magnetic field sensor 42 according to the determination result of the determination unit 62.

[0102] Specifically, when the skin effect is not present, the synthesis unit 61 generates a detection voltage V3 based on the sensor voltage V1 of the magnetic field sensor 41. The sensor voltage V2 of the magnetic field sensor 42 can be omitted. By using the sensor voltage V1 of the magnetic field sensor 41, which is positioned close to the conductor 9, the magnetic field H can be detected with high precision, and therefore the current I can be measured with high precision.

[0103] On the other hand, when the skin effect occurs, the synthesis unit 61 generates a detection voltage V3 based on the sensor voltage V2 of the magnetic field sensor 42. The sensor voltage V1 of the magnetic field sensor 41 can be omitted. Since the magnetic field sensor 42 is unaffected by the skin effect, it can detect the magnetic field H with high precision, and therefore can measure the current I with high precision.

[0104] Figure 14 This is a flowchart illustrating an example of the processing (current measurement method) performed in current sensor 1. Content that is repeated in the preceding description has been appropriately omitted.

[0105] In step S11, magnetic field H is detected using magnetic field sensors 41 and 42. Magnetic field sensor 41 outputs sensor voltage V1, and more specifically, outputs sensor voltage V11 and sensor voltage V12. Magnetic field sensor 42 outputs sensor voltage V2.

[0106] In step S12, based on the detection results of magnetic field sensor 41 and magnetic field sensor 42, it is determined whether a skin effect has occurred in conductor 9. The determination unit 62 of the detection circuit 6 determines whether a skin effect exists based on the ratio R of sensor voltage V12 and sensor voltage V2.

[0107] In step S13, the process branches according to the determination result of step S12 above. If the skin effect of conductor 9 occurs (step S13: Yes), the process proceeds to step S15. If not (step S13: No), the process proceeds to step S14.

[0108] In step S14, the current I is detected based on the detection result of the magnetic field sensor 41. The determination unit 62 of the detection circuit 6 generates a detection voltage V3 based on the sensor voltage V1 of the magnetic field sensor 41 (e.g., the sensor voltage V11 of the IC sensor only).

[0109] In step S15, the current I is detected based on the detection result of the magnetic field sensor 42. The determination unit 62 of the detection circuit 6 generates a detection voltage V3 based on the sensor voltage V2 of the magnetic field sensor 42.

[0110] <Sensor Movement>

[0111] In one embodiment, the magnetic field sensor 42 can be dynamically positioned near or far from the opening 37 within the shield 3. (See also...) Figure 15 Please provide an explanation.

[0112] Figure 15 This is a diagram illustrating an example of the schematic structure of the current sensor 1. The magnetic field sensor 41 is positioned near the opening 37. The magnetic field sensor 42 is movable within the shield 3 and can be positioned near or far from the opening 37.

[0113] The current sensor 1 includes a moving mechanism 7 that moves the magnetic field sensor 4, more specifically, the magnetic field sensor 42. The moving mechanism 7 moves the magnetic field sensor 42 between a position near the opening 37 and a position far from the opening 37. The specific structure of the moving mechanism 7 is not particularly limited, and any structure capable of physically moving the magnetic field sensor 42 can be adopted. For example, the moving mechanism 7 may be configured to include a support portion for supporting the magnetic field sensor 42 and a drive portion (actuator, etc.) for moving the support portion.

[0114] The moving mechanism 7 moves the magnetic field sensor 42 such that when no skin effect occurs, the magnetic field sensor 42 is positioned near the opening 37, and when a skin effect occurs, the magnetic field sensor 42 is positioned far from the opening 37. The determination of whether a skin effect is present or absent is performed by the detection circuit 6 as previously described.

[0115] The movement of the magnetic field sensor 42 based on the moving mechanism 7 can be controlled by the detection circuit 6. See also... Figure 16 Please provide an explanation.

[0116] Figure 16 This is a diagram illustrating an example of the schematic structure of the detection circuit 6. The detection circuit 6 also includes a control unit 63. The control unit 63 controls the moving mechanism 7. For example, the control unit 63 generates a control signal and sends it to the moving mechanism 7, which moves the magnetic field sensor 42 according to the control signal.

[0117] The determination result of the determination unit 62 can also be applied to the control unit 63's control of the moving mechanism 7. In this case, the control unit 63 controls the moving mechanism 7 based on the determination result of the determination unit 62. Specifically, the control unit 63 controls the moving mechanism 7 such that when the skin effect does not occur, the magnetic field sensor 42 is positioned near the opening 37, and when the skin effect occurs, the magnetic field sensor 42 is positioned at the opening 37.

[0118] Figure 17 This is a flowchart illustrating an example of the processing (current measurement method) performed in current sensor 1. Content that is repeated in the preceding description has been appropriately omitted.

[0119] In step S21, it is determined whether a skin effect has occurred in conductor 9. This determination is performed by the determination unit 62 of the detection circuit 6. If a skin effect has occurred (step S21: Yes), the process proceeds to step S22. If not (step S21: No), the process proceeds to step S23.

[0120] In step S22, the magnetic field sensor 42 is positioned at a distance from the opening 37. The control unit 63 of the detection circuit 6 generates a control signal and sends it to the moving mechanism 7 to position the magnetic field sensor 42 at a distance from the opening 37. The moving mechanism 7 moves the magnetic field sensor 42 so that it is positioned at a distance from the opening 37. Alternatively, if the magnetic field sensor 42 is already positioned at a distance from the opening 37, step S22 can be skipped.

[0121] In step S23, the magnetic field sensor 42 is disposed near the opening 37. The control unit 63 generates a control signal to send to the moving mechanism 7 in order to dispose the magnetic field sensor 42 near the opening 37. The moving mechanism 7 moves the magnetic field sensor 42 so that the magnetic field sensor 42 is disposed near the opening 37. Further, in the case where the magnetic field sensor 42 has already been disposed near the opening 37, the processing of step S23 may be skipped.

[0122] After the processing of step S22 or step S23 is completed, the processing is performed in the order of step S 24 and step S 25. These processes may be the same as the processes of step S1 and step S2 described previously. That is, the magnetic field H is detected by the magnetic field sensor 41 and the magnetic field sensor 42, and the current I is detected based on the detection results of the magnetic field sensor 41 and the magnetic field sensor 42. Figure 9 As described above, in the first method, by studying the dispositions of the magnetic field sensors 41 and 42 in the shield 3, it is possible to suppress the degradation of the measurement accuracy of the current I caused by the skin effect.

[0123]

[0124]

[0125] Figures 18 to 24 In the second method, the detection voltage V3 output from the detection circuit 6 is corrected. This will be described with reference to

[0126] Figure 18

[0127] Figure 19 FIG. is an example showing a schematic configuration of the current sensor 1. The magnetic field sensor 41 for detecting a low-frequency magnetic field and the magnetic field sensor 42 for detecting a high-frequency magnetic field are both disposed near the opening 37. The sensor voltage V2 of the magnetic field sensor 42 is affected by the skin effect.

[0128] [[ID=2 / 3]]

[0129] FIG. is an example showing a schematic configuration of the detection circuit 6 and the external device 2. The detection circuit 6 includes a combining unit 61 that generates a detection voltage V3 based on the sensor voltage V1 and the sensor voltage V2. The sensor voltage V2 varies depending on the presence or absence of the skin effect, and thus the detection voltage V3 also varies. In order to eliminate the variation of the detection voltage V3, the external device 2 corrects the detection voltage V3.

[0130]

[0131] A detection voltage V3 from the detection circuit 6 is input to the input terminal 21. As previously described, the detection voltage V3 represents the value of the current I, more specifically, the instantaneous value. The detection voltage V3 corresponding to the instantaneous value of the current I that changes with time is input to the input terminal 21.

[0130] In order to eliminate the variation of the detection voltage V3 caused by the influence of the skin effect, that is, the variation of the sensor voltage V2, the processing unit 22 corrects the detection voltage V3. For example, in the processing unit 22, the detection voltage V3 is converted into digital value data, and various data processes are performed on it. A storage unit for storing various data required for processing may also be included in the external device 2.

[0131] The processing unit 22 may be composed of, for example, a general or special-purpose processor, a memory, etc. The function of the processing unit 22 can be realized by hardware design, can also be realized by software design, or can be realized by both hardware design and software design. As one of the disclosed technologies, there is also a program for making the processing unit 22 execute various processes.

[0132] Specifically, the processing unit 22 corrects the detection voltage V3 in the frequency domain. In Figure 19 the example shown, the processing unit 22 includes a waveform generation unit 221, a Fourier transform unit 222, a correction unit 223, and a Fourier inverse transform unit 224.

[0133] The waveform generation unit 221 generates the waveform of the detection voltage V3. The waveform of the detection voltage V3 is the waveform before the processing unit 22 performs correction. For an example, refer to Figure 20 for description.

[0134] Figure 20 is a diagram showing an example of the waveform of the detection voltage V3 before correction. The horizontal axis of the graph represents time. The vertical axis of the graph represents the detection voltage V3. The waveform of the detection voltage V3 is affected by the skin effect (for example, waveform deterioration), so it does not accurately represent the waveform of the current I.

[0135] Return to Figure 19 , the Fourier transform unit 222 performs a Fourier transform on the waveform of the detection voltage V3 generated by the waveform generation unit 221. Thereby, the frequency components of the detection voltage V3 are obtained. The frequency components may include the amplitude value of each frequency, and may also include the phase of each frequency. The frequency components of the detection voltage V3 are the frequency components before the processing unit 22 performs correction. For an example, refer to Figure 21 for description.

[0136] Figure 21This is a graph showing an example of the frequency components of the detection voltage V3 before correction. The horizontal axis of the graph represents frequency. The vertical axis represents component A3. Component A3 can be interpreted as including both amplitude and phase components. The frequency components of this detection voltage V3 are affected by the skin effect, and therefore do not accurately represent the frequency components of the current I.

[0137] Return to Figure 19 The correction unit 223 corrects the frequency components of the detected voltage V3 obtained by Fourier transform in the Fourier transform unit 222. Specifically, the correction unit 223 corrects the frequency components of the detected voltage V3 by adding or multiplying a correction value with the frequency components of the detected voltage V3. The correction value may include an amplitude correction value for amplitude correction and a phase correction value for phase correction. For example, the amplitude correction value is multiplied by the amplitude component of the detected voltage V3, and the phase correction value is added to the phase component of the detected voltage V3. For an example, refer to... Figure 22 Please provide an explanation.

[0138] Figure 22 This is a diagram illustrating an example of the correction of the frequency component of the detection voltage V3. Figure 22 The top left graph shows the frequency components of the detection voltage V3 before correction, which are consistent with those previously described. Figure 21 The graphics are the same.

[0139] Figure 22 The lower left graphic represents the correction values ​​(amplitude correction value and phase correction value). The correction values ​​are determined based on the frequency characteristics of the detection voltage V3 caused by the skin effect. For example, the amount of variation (amplitude and phase variation) of the detection voltage V3 in the frequency region when the skin effect occurs is predetermined. The correction value used to offset this variation is calculated and stored in the storage unit within the external device 2 so that it can be used in the correction unit 223. Using this correction value, the frequency components of the detection voltage V3 are corrected. Figure 22 The graph on the right shows the frequency components of the corrected detection voltage V3. The frequency components of this detection voltage V3 have been freed from the skin effect, thus accurately representing the frequency components of the current I.

[0140] Return to Figure 19 The inverse Fourier transform unit 224 performs an inverse Fourier transform on the frequency components of the detected voltage V3 after correction by the correction unit 223. This yields the waveform of the detected voltage V3. This waveform of the detected voltage V3 eliminates the skin effect and accurately represents the waveform of the current I. For an example, refer to... Figure 23 Please provide an explanation.

[0141] Figure 23 This is a diagram illustrating an example of the inverse Fourier transform. Figure 23The graph on the left shows the frequency components of the corrected detection voltage V3, which is consistent with the previously described... Figure 22 The graphic on the right is the same. Figure 23 The right side shows the waveform of the detection voltage V3 obtained through inverse Fourier transform. This waveform of the detection voltage V3 is the corrected waveform of the detection voltage V3, which is consistent with the previously described waveform. Figure 20 The waveform of the detection voltage V3 before correction is different (e.g., the waveform degradation disappears).

[0142] Return to Figure 19 The display unit 23 displays the waveform of the detection voltage V3, corrected by the processing unit 22, as the waveform of the current I. It can display the accurate measurement result of the current I, after eliminating the influence of the skin effect.

[0143] As explained above, by calibrating the detection voltage V3 using the external device 2, the decrease in the measurement accuracy of the current I caused by the skin effect can also be suppressed.

[0144] Figure 24 This is a flowchart illustrating an example of the processing (current measurement method) performed in the current measuring device 100. Content that is repeated in the description so far has been appropriately omitted.

[0145] In step S31, the magnetic field H is detected using the magnetic field sensor 4. The magnetic field sensors 41 and 42, which are positioned near the opening 37, output sensor voltages V1 and V2 corresponding to the magnetic field H at their respective positions.

[0146] In step S32, a waveform is generated based on the detection result of the magnetic field sensor 4. The detection circuit 6 generates a detection voltage V3 based on the sensor voltage V1 and the sensor voltage V2. The waveform generation unit 221 of the processing unit 22 of the external device 2 generates the waveform of the detection voltage V3.

[0147] In step S33, a Fourier transform is performed on the waveform. The Fourier transform unit 222 of the processing unit 22 of the external device 2 performs a Fourier transform on the waveform of the detection voltage V3. The frequency components of the detection voltage V3 can be obtained.

[0148] In step S34, the frequency components are corrected. The correction unit 223 of the processing unit 22 of the external device 2 corrects the frequency components of the detection voltage V3 using the correction value.

[0149] In step S35, an inverse Fourier transform is performed on the corrected frequency components. The inverse Fourier transform unit 224 of the processing unit 22 of the external device 2 performs an inverse Fourier transform on the frequency components of the corrected detection voltage V3. The waveform of the corrected detection voltage V3 can be obtained.

[0150] In step S36, the waveform is displayed. The display unit 23 of the external device 2 displays the waveform of the corrected detection voltage V3.

[0151] As explained above, in the second method, by correcting the detection voltage V3 output by the detection circuit 6, the decrease in the measurement accuracy of the current I caused by the skin effect can be suppressed.

[0152] <Summary>

[0153] The techniques described above are determined, for example, in the following manner. One of the disclosed techniques is a current sensor 1. (See reference...) Figures 1 to 17 As described above, the current sensor 1 includes: a shield 3 having an opening 37 for introducing a magnetic field H generated by the current I flowing in the conductor 9 into its interior; a magnetic field sensor 4 disposed within the shield 3, outputting a sensor voltage corresponding to the magnetic field H at its location; and a detection circuit 6 disposed outside the shield 3, detecting the current I based on the sensor voltage of the magnetic field sensor 4. The magnetic field sensor 4 includes a magnetic field sensor 41 (first magnetic field sensor) for detecting low-frequency magnetic fields and a magnetic field sensor 42 (second magnetic field sensor) for detecting high-frequency magnetic fields. Compared to the magnetic field sensor 42, the magnetic field sensor 41 is disposed near the opening 37, and compared to the magnetic field sensor 41, the magnetic field sensor 42 is disposed far from the opening 37. More specifically, the magnetic field sensor 41 is disposed in the vicinity of the conductor 9, and the magnetic field sensor 42 is disposed in the far region of the conductor 9. The vicinity is a region where the magnitude of the magnetic field H varies depending on the presence or absence of the skin effect of the conductor 9, and the far region is a region where the magnitude of the magnetic field H does not vary depending on the presence or absence of the skin effect of the conductor 9.

[0154] According to the current sensor 1 described above, the magnetic field sensor 42, which detects high-frequency magnetic fields, is positioned at a distance from the opening 37, compared to the magnetic field sensor 41, which detects low-frequency magnetic fields. The magnetic field sensor 42 is unaffected by the skin effect of the conductor 9. When the frequency f of the current I is high and the skin effect occurs, the sensor voltage V2 of the magnetic field sensor 42, which detects high-frequency magnetic fields, dominates the sensor voltage of the magnetic field sensor 4. The current I is detected based on this sensor voltage. Therefore, the decrease in the measurement accuracy of the current I caused by the skin effect can be suppressed.

[0155] For reference Figures 10 to 14As explained below, the detection circuit 6 can determine whether a skin effect of conductor 9 has occurred based on the sensor voltage of magnetic field sensor 4. When no skin effect of conductor 9 has occurred, the current I is detected based on the sensor voltage V1 of magnetic field sensor 41. When a skin effect of conductor 9 has occurred, the current I is detected based on the sensor voltage V2 of magnetic field sensor 42. Thus, the current I can be measured selectively using the sensor voltage V1 of magnetic field sensor 41 and the sensor voltage V2 of magnetic field sensor 42, depending on whether a skin effect is present.

[0156] For reference Figures 10 to 14 As explained above, magnetic field sensor 41 also detects high-frequency magnetic fields. Both magnetic field sensor 41 and magnetic field sensor 42 include coil sensors for detecting high-frequency magnetic fields. Detection circuit 6 can determine whether a skin effect of conductor 9 has occurred based on the sensor voltage V12 of the coil sensor of magnetic field sensor 41 and the sensor voltage V2 of the coil sensor of magnetic field sensor 42 (e.g., based on their ratio R). For example, it is possible to determine whether a skin effect of conductor 9 exists, as described above.

[0157] Reference Figures 1 to 3 and Figures 15 to 17 The current sensor 1 described above is also one of the disclosed technologies. The current sensor 1 includes: a shield 3 having an opening 37 for introducing a magnetic field H generated by a current I flowing in a conductor 9 into its interior; a magnetic field sensor 4 disposed within the shield 3, outputting a sensor voltage corresponding to the magnetic field H at its location; a detection circuit 6 disposed outside the shield 3, detecting the current I based on the sensor voltage of the magnetic field sensor 4; and a moving mechanism 7 for moving the magnetic field sensor 4. The magnetic field sensor 4 includes a magnetic field sensor 41 (first magnetic field sensor) disposed near the opening 37 for detecting low-frequency magnetic fields and a magnetic field sensor 42 (second magnetic field sensor) for detecting high-frequency magnetic fields. The moving mechanism 7 moves the magnetic field sensor 42 between a position near the opening 37 and a position far from the opening 37. In this case, the detection circuit 6 determines whether a skin effect of conductor 9 has occurred based on the sensor voltage of the magnetic field sensor 4. The moving mechanism 7 can move the magnetic field sensor 42 such that when no skin effect of conductor 9 is generated, the magnetic field sensor 42 is positioned near the opening 37, and when a skin effect of conductor 9 is generated, the magnetic field sensor 42 is positioned far from the opening 37. As described above, by means of a structure that allows the magnetic field sensor 42 to move, the magnetic field sensor 42 can also be positioned far from the opening 37. Therefore, as explained so far, the decrease in the measurement accuracy of current I caused by the skin effect can be suppressed.

[0158] Reference Figures 1 to 3 and Figures 18 to 24The current measuring device 100 described above is also one of the disclosed technologies. The current measuring device 100 includes: a shield 3 having an opening 37 for introducing a magnetic field H generated by the current I flowing in the conductor 9 into its interior; a magnetic field sensor 4 disposed within the shield 3, outputting a sensor voltage corresponding to the magnetic field H at its location; a detection circuit 6 disposed outside the shield 3, generating a detection voltage V3 representing the value of the current I based on the sensor voltage of the magnetic field sensor 4; and an external device 2 disposed outside the shield 3, calibrating the detection voltage V3 in the frequency region. More specifically, the sensor voltage (e.g., the sensor voltage V2 of the magnetic field sensor 42) varies according to the skin effect of the conductor 9, the detection voltage V3 varies according to the variation of the sensor voltage, and the external device 2 can calibrate the detection voltage V3 in a manner that eliminates the variation of the detection voltage V3. External device 2 may include: a waveform generation unit 221 that generates a waveform of the detection voltage V3; a Fourier transform unit 222 that performs a Fourier transform on the waveform of the detection voltage V3; a correction unit 223 that corrects the frequency components of the detection voltage V3 obtained through the Fourier transform; and an inverse Fourier transform unit 224 that performs an inverse Fourier transform on the frequency components of the corrected detection voltage V3. For example, by correcting the detection voltage V3 output by the detection circuit 6 in the frequency region as described above, the decrease in the measurement accuracy of the current I caused by the skin effect can also be suppressed.

[0159] The current measurement method is also one of the disclosed technologies. The current measurement method includes the following steps: using a magnetic field sensor 4 disposed within a shield 3, the magnetic field H at its location is detected (e.g., ...). Figure 9 In step S1), the shield 3 has an opening 37 for introducing the magnetic field H generated by the current I flowing in the conductor 9 into the interior; and for detecting the current I based on the detection result of the magnetic field sensor 4 (e.g., Figure 9 (Step S2). As described herein, the magnetic field sensor 4 includes a magnetic field sensor 41 and a magnetic field sensor 42. This current measurement method, as described herein, can suppress the decrease in the measurement accuracy of current I caused by the skin effect.

[0160] The following are some examples of combinations of disclosed technical features. (1)

[0162] A current sensor having:

[0163] A shielding element having an opening for introducing a magnetic field generated by a current flowing in a conductor into the interior;

[0164] A magnetic field sensor, disposed within the shielding member, outputs a sensor voltage corresponding to the magnetic field at its location; and

[0165] A detection circuit, disposed outside the shielding component, detects the current based on the sensor voltage of the magnetic field sensor.

[0166] The magnetic field sensor includes a first magnetic field sensor and a second magnetic field sensor.

[0167] The first magnetic field sensor detects low-frequency magnetic fields, and the second magnetic field sensor detects high-frequency magnetic fields.

[0168] Compared to the second magnetic field sensor, the first magnetic field sensor is positioned closer to the opening.

[0169] Compared to the first magnetic field sensor, the second magnetic field sensor is positioned at a distance from the opening. (2)

[0171] According to the current sensor described in (1), wherein,

[0172] The first magnetic field sensor is disposed in the vicinity of the conductor.

[0173] The second magnetic field sensor is positioned in the distal region of the conductor.

[0174] The vicinity region is the area where the magnitude of the magnetic field varies depending on the presence or absence of the skin effect of the conductor.

[0175] The distant region is the area where the magnitude of the magnetic field does not change based on the presence or absence of the skin effect of the conductor. (3)

[0177] According to the current sensor described in (1) or (2), wherein,

[0178] The detection circuit determines whether the skin effect of the conductor has occurred based on the sensor voltage of the magnetic field sensor.

[0179] When the skin effect of the conductor is not present, the current is detected based on the sensor voltage of the first magnetic field sensor.

[0180] When the skin effect of the conductor is generated, the current is detected based on the sensor voltage of the second magnetic field sensor. (4)

[0182] According to the current sensor described in (3), wherein,

[0183] The first magnetic field sensor also detects high-frequency magnetic fields.

[0184] The first magnetic field sensor and the second magnetic field sensor each include a coil sensor for detecting high-frequency magnetic fields.

[0185] The detection circuit determines whether the skin effect of the conductor has occurred based on the sensor voltage of the coil sensor of the first magnetic field sensor and the sensor voltage of the coil sensor of the second magnetic field sensor. (5)

[0187] According to the current sensor described in (4), the detection circuit determines whether the skin effect of the conductor has occurred based on the ratio between the sensor voltage of the coil sensor of the first magnetic field sensor and the sensor voltage of the coil sensor of the second magnetic field sensor. (6)

[0189] A current sensor having:

[0190] A shielding element having an opening for introducing a magnetic field generated by a current flowing in a conductor into the interior;

[0191] A magnetic field sensor, which is disposed within the shielding component, outputs a sensor voltage corresponding to the magnetic field at its location;

[0192] A detection circuit, disposed outside the shielding member, detects the current based on the sensor voltage of the magnetic field sensor; and

[0193] A moving mechanism that moves the magnetic field sensor.

[0194] The magnetic field sensor includes a first magnetic field sensor and a second magnetic field sensor.

[0195] The first magnetic field sensor is positioned near the opening to detect low-frequency magnetic fields, while the second magnetic field sensor detects high-frequency magnetic fields.

[0196] The moving mechanism moves the second magnetic field sensor between a position near the opening and a position far from the opening. (7)

[0198] According to the current sensor described in (6), wherein,

[0199] The detection circuit determines whether the skin effect of the conductor has occurred based on the sensor voltage of the magnetic field sensor.

[0200] The moving mechanism moves the second magnetic field sensor such that when the skin effect of the conductor is not generated, the second magnetic field sensor is positioned near the opening, and when the skin effect of the conductor is generated, the second magnetic field sensor is positioned far from the opening. (8)

[0202] A current measuring device, comprising:

[0203] A shielding element having an opening for introducing a magnetic field generated by a current flowing in a conductor into the interior;

[0204] A magnetic field sensor, which is disposed within the shielding component, outputs a sensor voltage corresponding to the magnetic field at its location;

[0205] A detection circuit, disposed outside the shielding member, generates a detection voltage representing the value of the current based on the sensor voltage of the magnetic field sensor; and

[0206] An external device, disposed outside the shield, calibrates the detected voltage in the frequency range. (9)

[0208] According to the current measuring device described in (8), wherein,

[0209] The sensor voltage varies according to the skin effect of the conductor.

[0210] The detection voltage varies according to the change in the sensor voltage.

[0211] The external device corrects the detection voltage by eliminating variations in the detection voltage. (10)

[0213] According to the current measuring device described in (8) or (9), wherein,

[0214] The external device includes:

[0215] A waveform generation unit generates the waveform of the detected voltage;

[0216] The Fourier transform unit performs a Fourier transform on the waveform of the detected voltage;

[0217] A correction unit that corrects the frequency components of the detected voltage obtained through the Fourier transform; and

[0218] The inverse Fourier transform unit performs an inverse Fourier transform on the frequency components of the corrected detection voltage. (11)

[0220] A method for measuring current, comprising the following steps:

[0221] A magnetic field sensor disposed within a shielding member is used to detect the magnetic field at its location. The shielding member has an opening for introducing the magnetic field generated by the current flowing in the conductor into its interior.

[0222] Based on the detection results of the magnetic field sensor, the current is detected.

[0223] In the current measurement method,

[0224] The magnetic field sensor includes a first magnetic field sensor and a second magnetic field sensor. The first magnetic field sensor detects low-frequency magnetic fields, and the second magnetic field sensor detects high-frequency magnetic fields.

[0225] Compared to the second magnetic field sensor, the first magnetic field sensor is positioned closer to the opening.

[0226] Compared to the first magnetic field sensor, the second magnetic field sensor is positioned at a distance from the opening.

[0227] Explanation of the label

[0228] 1 Current sensor

[0229] 2 External devices

[0230] 3 Shielding components

[0231] 30 Interior Space

[0232] 31 Base Plate

[0233] 32 board

[0234] 33 Side panels

[0235] 34 Side panels

[0236] 35 Side panels

[0237] 36 side panels

[0238] 37. Opening

[0239] 38 terminals

[0240] 4. Magnetic field sensor

[0241] 41 Magnetic field sensor

[0242] 42 Magnetic field sensor

[0243] 5 External Units

[0244] 6. Detection Circuit

[0245] 61 Synthesis Department

[0246] 62 Judgment Department

[0247] 63 Control Department

[0248] 7. Mobile mechanism

[0249] 9 conductors

[0250] H magnetic field

[0251] H11 magnetic field

[0252] H12 magnetic field

[0253] H21 magnetic field

[0254] H22 magnetic field

[0255] I Current

[0256] V1 sensor voltage

[0257] V11 sensor voltage

[0258] V12 sensor voltage

[0259] V2 sensor voltage

[0260] W1 wiring

Claims

1. A current sensor, comprising: A shielding element having an opening for introducing a magnetic field generated by a current flowing in a conductor into the interior; A magnetic field sensor, which is disposed within the shielding component, outputs a sensor voltage corresponding to the magnetic field at its location; as well as A detection circuit, disposed outside the shielding component, detects the current based on the sensor voltage of the magnetic field sensor. The magnetic field sensor includes a first magnetic field sensor and a second magnetic field sensor. The first magnetic field sensor detects low-frequency magnetic fields, and the second magnetic field sensor detects high-frequency magnetic fields. Compared to the second magnetic field sensor, the first magnetic field sensor is positioned closer to the opening. Compared to the first magnetic field sensor, the second magnetic field sensor is positioned at a distance from the opening.

2. The current sensor according to claim 1, wherein, The first magnetic field sensor is disposed in the vicinity of the conductor. The second magnetic field sensor is positioned in the distal region of the conductor. The vicinity region is the area where the magnitude of the magnetic field varies depending on the presence or absence of the skin effect of the conductor. The distant region is the area where the magnitude of the magnetic field does not change based on the presence or absence of the skin effect of the conductor.

3. The current sensor according to claim 1 or 2, wherein, The detection circuit determines whether the skin effect of the conductor has occurred based on the sensor voltage of the magnetic field sensor. When the skin effect of the conductor is not present, the current is detected based on the sensor voltage of the first magnetic field sensor. When the skin effect of the conductor is generated, the current is detected based on the sensor voltage of the second magnetic field sensor.

4. The current sensor according to claim 3, wherein, The first magnetic field sensor also detects high-frequency magnetic fields. The first magnetic field sensor and the second magnetic field sensor each include a coil sensor for detecting high-frequency magnetic fields. The detection circuit determines whether the skin effect of the conductor has occurred based on the sensor voltage of the coil sensor of the first magnetic field sensor and the sensor voltage of the coil sensor of the second magnetic field sensor.

5. The current sensor according to claim 4, wherein, The detection circuit determines whether the skin effect of the conductor has occurred based on the ratio between the sensor voltage of the coil sensor of the first magnetic field sensor and the sensor voltage of the coil sensor of the second magnetic field sensor.

6. A current sensor, comprising: A shielding element having an opening for introducing a magnetic field generated by a current flowing in a conductor into the interior; A magnetic field sensor, which is disposed within the shielding component, outputs a sensor voltage corresponding to the magnetic field at its location; A detection circuit, disposed outside the shielding component, detects the current based on the sensor voltage of the magnetic field sensor; as well as A moving mechanism that moves the magnetic field sensor. The magnetic field sensor includes a first magnetic field sensor and a second magnetic field sensor. The first magnetic field sensor is positioned near the opening to detect low-frequency magnetic fields, while the second magnetic field sensor detects high-frequency magnetic fields. The moving mechanism moves the second magnetic field sensor between a position near the opening and a position far from the opening.

7. The current sensor according to claim 6, wherein, The detection circuit determines whether the skin effect of the conductor has occurred based on the sensor voltage of the magnetic field sensor. The moving mechanism moves the second magnetic field sensor such that when the skin effect of the conductor is not generated, the second magnetic field sensor is positioned near the opening, and when the skin effect of the conductor is generated, the second magnetic field sensor is positioned far from the opening.

8. A current measuring device, comprising: A shielding element having an opening for introducing a magnetic field generated by a current flowing in a conductor into the interior; A magnetic field sensor, which is disposed within the shielding component, outputs a sensor voltage corresponding to the magnetic field at its location; A detection circuit, disposed outside the shielding member, generates a detection voltage representing the value of the current based on the sensor voltage of the magnetic field sensor; as well as An external device, disposed outside the shield, calibrates the detected voltage in the frequency range.

9. The current measuring device according to claim 8, wherein, The sensor voltage varies according to the skin effect of the conductor. The detection voltage varies according to the change in the sensor voltage. The external device corrects the detection voltage by eliminating variations in the detection voltage.

10. The current measuring device according to claim 8 or 9, wherein, The external device includes: A waveform generation unit generates the waveform of the detected voltage; The Fourier transform unit performs a Fourier transform on the waveform of the detected voltage; The correction unit corrects the frequency components of the detected voltage obtained through the Fourier transform; as well as The inverse Fourier transform unit performs an inverse Fourier transform on the frequency components of the corrected detection voltage.

11. A method for measuring current, comprising the following steps: A magnetic field sensor disposed within a shielding member is used to detect the magnetic field at its location. The shielding member has an opening for introducing the magnetic field generated by the current flowing in the conductor into its interior. Based on the detection results of the magnetic field sensor, the current is detected. In the current measurement method, The magnetic field sensor includes a first magnetic field sensor and a second magnetic field sensor. The first magnetic field sensor detects low-frequency magnetic fields, and the second magnetic field sensor detects high-frequency magnetic fields. Compared to the second magnetic field sensor, the first magnetic field sensor is positioned closer to the opening. Compared to the first magnetic field sensor, the second magnetic field sensor is positioned at a distance from the opening.

Images