Voltage measuring device

Abstract

To provide a voltage measuring device that can suppress the decrease in voltage measurement accuracy. [Solution] The device comprises a plurality of first potential electrodes 131 connected to the potential of the object to be measured where an AC voltage is generated, and a second potential electrode 132 sandwiched between the first potential electrodes 131 and having a potential with respect to the first potential electrodes 131 via capacitance, and measures the potential between the housing and the second potential electrode 132. Since the second potential electrode 132 is sandwiched between the first potential electrodes 131, and the first potential electrodes 131 are connected to the potential of the object to be measured, they can form part of a voltage divider circuit. The first potential electrodes 131 act as guard electrodes, suppressing the detection of external noise by the second potential electrode 132.

Description

Technical Field

[0001] The present invention relates to a voltage measurement device, particularly to a voltage measurement device for measuring noise in a high-voltage system.

Background Art

[0002] Patent Document 1 discloses a voltage measurement device provided with a shield electrode (guard electrode) in order to reduce the influence of disturbance. The description of the prior art document is incorporated herein by reference as the explanation of the technical elements in this specification.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Consider measuring the voltage to be measured by dividing the voltage with a voltage dividing circuit. By using a voltage dividing circuit, elements not corresponding to high voltages can be used for the components of the voltage measurement circuit, and thus the voltage measurement circuit can be miniaturized and made to have a higher frequency.

[0005] The inventor has found that in voltage measurement using a voltage dividing circuit, when the guard electrode of the housing potential is close to the measurement target, the high-frequency noise of the measurement target is reduced due to the capacitive coupling between the signal line for detecting the voltage and the guard electrode, and there is a problem that the measurement accuracy of the voltage decreases.

[0006] The present disclosure has been made based on this situation, and an object thereof is to provide a voltage measurement device capable of suppressing a decrease in voltage measurement accuracy. <F [[ID=F0000033]]

Means for Solving the Problems

[0007] The above objectives are achieved by combinations of features described in the independent claims, and the subordinate claims provide further advantageous specific examples. The reference numerals in parentheses in the claims indicate a correspondence with specific embodiments described later as one aspect, and do not limit the disclosed technical scope.

[0008] One disclosure to achieve the above objective is: Multiple first potential electrodes (131) connected to the potential of the object to be measured, where an AC voltage is generated, It comprises a second potential electrode (132, 632, 732) sandwiched between first potential electrodes and having a potential with respect to the first potential electrode via capacitance, This is a voltage measuring device that measures the potential between the housing (110) and the second potential electrode.

[0009] Since the second potential electrode is sandwiched between the first potential electrodes, and the first potential electrode is connected to the potential of the object being measured, it can form part of a voltage divider circuit. Furthermore, because the second potential electrode is sandwiched between the first potential electrodes, the first potential electrode acts as a guard electrode, suppressing the detection of external noise by the second potential electrode. Therefore, a decrease in voltage measurement accuracy can be suppressed.

[0010] Furthermore, the first potential electrode is not connected to the housing potential. Therefore, capacitive coupling occurs between the first potential electrode and the housing, preventing current from flowing from the object being measured to the housing. In this respect as well, a decrease in voltage measurement accuracy can be suppressed. [Brief explanation of the drawing]

[0011] [Figure 1] A diagram showing the configuration of a voltage measurement system. [Figure 2] A diagram showing the equivalent circuit of a pressure measurement system. [Figure 3] Cross-sectional view of the voltage divider substrate of the first embodiment. [Figure 4] A plan view of the voltage divider substrate and a diagram showing the electrodes of each layer. [Figure 5] Cross-sectional view of the voltage divider substrate of the second embodiment. [Figure 6] A diagram showing the shape of the electrodes of each layer of the voltage dividing substrate of the second embodiment. [Figure 7] A diagram showing the shape of the electrodes of each layer of the voltage dividing substrate of the third embodiment. [Figure 8] A diagram showing the shape of the electrodes of each layer of the voltage dividing substrate of the fourth embodiment. [Figure 9] A cross-sectional view of the voltage dividing substrate of the fifth embodiment. [Figure 10] A diagram showing the shape of each layer of the voltage dividing substrate of the sixth embodiment. [Figure 11] A diagram showing the shape of the electrodes of each layer of the voltage dividing substrate of the seventh embodiment. [Figure 12] A diagram showing the connection form between the voltage dividing substrate and the DUT. [Figure 13] A diagram showing the voltage dividing substrate of the ninth embodiment. [Figure 14] A diagram showing the configuration of the housing substrate. [Figure 15] A diagram comparing the frequency characteristics of the attenuation amount for the tenth embodiment and the comparative example. [Figure 16] A configuration diagram of the voltage measurement system of the eleventh embodiment. [Figure 17] A cross-sectional view of the voltage dividing substrate. [Figure 18] A diagram showing the equivalent circuit of the voltage measurement system. [Figure 19] A configuration diagram of the voltage measurement system of the twelfth embodiment. [Figure 20] A diagram showing the equivalent circuit of the voltage measurement system.

Embodiments for Carrying out the Invention

[0012] <First Embodiment> Hereinafter, embodiments will be described based on the drawings. FIG. 1 shows the configuration of a voltage measurement system 10 including a voltage measurement device 100 according to this embodiment. The voltage measurement system 10 includes a voltage measurement device 100, an oscilloscope 20, and a differential probe 30.

[0013] The base end of the differential probe 30 is connected to the oscilloscope 20. One of the two tips of the differential probe 30 is connected to a connection part 123 provided on the housing substrate 120 of the voltage measuring device 100. The other of the two tips of the differential probe 30 is connected to another connection part 124 provided on the housing substrate 120.

[0014] The voltage measuring device 100 comprises a housing 110, a housing circuit board 120, a voltage divider circuit board 130, and a shielded wire 140. The shielded wire 140 has an outer conductor arranged around the signal line. For example, a coaxial cable can be used as the shielded wire 140.

[0015] The housing 110 is made of a conductive material and is larger than the housing substrate 120. The housing substrate 120 is made of an insulating material. A glass epoxy substrate can be used for the housing substrate 120. The housing 110 and the housing substrate 120 are joined by bolts 150.

[0016] A damping resistor 121 and a chip capacitor 122, which is the capacitance component, are fixed to the upper surface of the housing circuit board 120. The damping resistor 121 and the chip capacitor 122 are electrically connected by wiring formed on the housing circuit board 120.

[0017] The connection part 124 is electrically connected to the housing 110 via the housing substrate 120 and the bolt 150. Since the connection part 124 is electrically connected to the housing 110, the potential of the connection part 124 is the same as that of the housing 110. A chip capacitor 122 is located between this connection part 124 and the other connection part 123. Therefore, the potential of the connection part 123 is different from that of the housing.

[0018] The voltage divider board 130 is connected to a three-phase busbar 40, which is an example of a device to be measured, by a bolt 160. The three-phase busbar 40 is a busbar provided by an inverter and is a conductor that generates AC voltage. The voltage divider board 130 is connected to the device to be measured and forms capacitance between the device to be measured and the connection part 123. The configuration of the voltage divider board 130 will be described later with reference to Figure 3.

[0019] Figure 2 shows the equivalent circuit of the voltage measurement system 10. Capacitance Cb is the capacitance of the chip capacitor 122. Capacitance Ca is formed by the voltage divider substrate 130. Capacitance Cb is, for example, 1000pF, and capacitance Ca is, for example, 10pF. In Figure 2, the measurement target is the voltage between RU. The capacitance Cb of the chip capacitor 122 and the capacitance Ca formed by the voltage divider substrate 130 form a voltage divider circuit 170. The differential probe 30 measures the voltage across the chip capacitor 122.

[0020] If Vin is the voltage to be measured and Vout is the measured voltage, then Equation 1 holds true due to the voltage divider circuit 170. Note that since capacitance Cb is sufficiently larger than capacitance Ca, the denominator of Equation 1 may also be Cb. (Formula 1) Vout=Vin×Ca / (Ca+Cb)

[0021] Figure 3 is a cross-sectional view of the voltage divider substrate 130 of the first embodiment, taken along the line III-III in Figure 4. Figure 4(a) is a plan view of the voltage divider substrate 130, (b) shows the second layer of the voltage divider substrate 130, and (c) shows the third layer of the voltage divider substrate 130.

[0022] The voltage divider substrate 130 is flat overall. The voltage divider substrate 130 includes a first potential electrode 131 and a second potential electrode 132. The potential of the first potential electrode 131 is called the first potential, and the potential of the second potential electrode 132 is called the second potential. The first potential electrode 131 is, in detail, two first potential electrodes 131a and 131b. When these two first potential electrodes 131a and 131b are not distinguished, they are referred to simply as the first potential electrode 131.

[0023] Both the first potential electrodes 131a and 131b are flat plates. As can be seen from Figures 4(a) and (c), the external shapes of the first potential electrodes 131a and 131b are the same. The first potential electrode 131a is connected to the first potential input section 133. The first potential input section 133 is made of a conductive material. In addition to the first potential electrode 131a, the first potential input section 133 is also connected to the object to be measured. The potential of the object to be measured is the first potential. Therefore, the first potential input section 133 inputs the first potential to the first potential electrode 131a.

[0024] The first potential electrode 131a and the first potential electrode 131b are electrically connected by vias 134 and 135. Therefore, the potential of the first potential electrode 131b is also the first potential. The first potential electrode 131a and the first potential electrode 131b face each other and are arranged parallel to each other.

[0025] As shown in Figure 4(b), the second potential electrode 132 is rectangular in plan view. The second potential electrode 132 is smaller than the first potential electrodes 131a and 131b. When viewed from the stacking direction of the first potential electrode 131 and the second potential electrode 132, the second potential electrode 132 is located inside the contour of the first potential electrode 131.

[0026] The second potential electrode 132 is parallel to the first potential electrodes 131a and 131b, and is sandwiched between them. Therefore, the second potential electrode 132 and the first potential electrode 131a, and the second potential electrode 132 and the first potential electrode 131b form capacitance. In addition, the first potential electrodes 131a and 131b also function as guard electrodes to suppress the arrival of external noise to the second potential electrode 132.

[0027] An output electrode 136 is positioned on the surface of the voltage divider substrate 130. The output electrode 136 and the second potential electrode 132 are electrically connected by a via 137. The output electrode 136 is smaller than the second potential electrode 132. The output electrode 136 is formed on the surface of the voltage divider substrate 130 to connect a shield wire 140 to the second potential electrode 132. The shield wire 140 can be connected to the output electrode 136 via a connector.

[0028] A solid dielectric layer 138 separates the first potential electrode 131 and the second potential electrode 132. This configuration can be realized by forming the first potential electrode 131, the second potential electrode 132, and vias 134, 135, and 137 on a printed circuit board. The solid dielectric layer 138 is made of a material with higher insulation resistance than air.

[0029] In this configuration, the voltage measurement system 10 has a second potential electrode 132 sandwiched between the first potential electrode 131, and the first potential electrode 131 is connected to the potential of the object to be measured, thus forming part of the voltage divider circuit 170.

[0030] In addition, since much of the second potential electrode 132 is sandwiched between the first potential electrode 131, the first potential electrode 131 acts as a guard electrode, suppressing the detection of external noise by the second potential electrode 132. For example, when measuring the voltage between RUs, it is possible to suppress the detection of voltages from other adjacent phases as noise. Therefore, a decrease in voltage measurement accuracy can be suppressed.

[0031] As shown in Figure 2, parasitic capacitance Cp is generated by the potential between the measurement potential and SV. Parasitic capacitance Cp is also generated by the potential between the measurement potential and TW. However, these parasitic capacitances Cp are sufficiently small compared to the capacitance Ca formed by the first potential electrode 131 and the second potential electrode 132. Therefore, this parasitic capacitance Cp does not pose a problem in the measurement.

[0032] Furthermore, the first potential electrode 131 is not connected to the housing potential. Therefore, capacitive coupling occurs between the first potential electrode 131 and the housing 110, preventing current from flowing from the object being measured to the housing 110. In this respect as well, a decrease in voltage measurement accuracy can be suppressed.

[0033] A solid dielectric layer 138 is formed between the first potential electrode 131 and the second potential electrode 132. Since the solid dielectric layer 138 has a higher insulation resistance than air, it can suppress discharge caused by high voltage.

[0034] The second potential electrode 132 is positioned inside the contour of the first potential electrode 131 when viewed from the stacking direction of the first potential electrode 131 and the second potential electrode 132. In this way, the first potential electrode 131 has a particularly strong effect as a guard electrode.

[0035] <Second Embodiment> Next, a second embodiment will be described. In this second embodiment and subsequent descriptions, elements having the same reference numerals as those used up to that point are identical to the elements with the same reference numerals in the previous embodiments, unless otherwise specified. Also, when only a part of the configuration is described, the previously described embodiments can be applied to the other parts of the configuration.

[0036] Figure 5 is a cross-sectional view of the voltage divider substrate 230 of the second embodiment, cut along the VV line in Figure 6. Figure 6 is a diagram showing the shape of the electrodes in each layer of the voltage divider substrate 230. The voltage divider substrate 230 of the second embodiment differs from the voltage divider substrate 130 of the first embodiment in that it also has first potential electrodes 131c and 131d on the same layer as the second potential electrode 132. The first potential electrodes 131c and 131d are positioned away from the second potential electrode 132 in the longitudinal direction of the voltage divider substrate 230.

[0037] The first potential electrodes 131c and 131d have equal lengths in the y-axis direction. The lengths of the first potential electrodes 131c and 131d in the y-axis direction are longer than those of the second potential electrode 132, and the y-axis range of the second potential electrode 132 is included within the y-axis range of the first potential electrodes 131c and 131d. The first potential electrodes 131c and 131d are electrically connected to the upper and lower first potential electrodes 131a and 131b by vias 134 and 135.

[0038] The first potential electrodes 131c and 131d provided in the second layer also function as guard electrodes. Therefore, by using the voltage divider substrate 230 of this second embodiment, it is possible to suppress the detection of noise from the side direction of the voltage divider substrate 230 by the second potential electrode 132.

[0039] The two first potential electrodes 131c and 131d are positioned on either side of the second potential electrode 132. In other words, two of the four sides of the second potential electrode 132 do not face the first potential electrodes 131c and 131d. With this configuration, the second potential electrode 132 can be made larger than in the third embodiment described next, and therefore the capacitance Ca can be increased.

[0040] <Third Embodiment> Figure 7 shows the shapes of the electrodes in each layer of the voltage divider substrate 330 of the third embodiment. The voltage divider substrate 330 of the third embodiment differs from the second embodiment in the shape of the electrodes in the second layer. In the third embodiment, the second layer comprises one first potential electrode 131e and one second potential electrode 132. The external shape of the first potential electrode 131e is the same as that of the first potential electrodes 131a and 131b. The first potential electrode 131e has a rectangular cutout hole 139. The second potential electrode 132 is housed in the hole 139. Therefore, the first potential electrode 131e completely surrounds the periphery of the second potential electrode 132 in the plane including the first potential electrode 131e. The second potential electrode 132 is positioned in the center of the hole 139.

[0041] Since the second potential electrode 132 is sized to fit into the hole 139, its length in the y-axis direction is shorter than that of the second potential electrode 132 in the second embodiment. As a result, the area of ​​the second potential electrode 132 in the third embodiment is smaller than that of the second potential electrode 132 in the second embodiment.

[0042] The first potential electrode 131e of the second layer also functions as a guard electrode. The first potential electrode 131e completely surrounds the second potential electrode 132. Therefore, it is possible to suppress the detection of noise from the side direction of the voltage divider substrate 330 by the second potential electrode 132 more effectively than with the first potential electrode 131c of the second embodiment.

[0043] <Fourth Embodiment> Figure 8 is a cross-sectional view of the voltage divider substrate 430 of the fourth embodiment. The voltage divider substrate 430 is configured to include a connector 440 on top of the voltage divider substrate 330 of the third embodiment. In order to include the connector 440 on top of the voltage divider substrate 330, the solid dielectric layer 438 is thicker than the solid dielectric layer 138 of the voltage divider substrate 330.

[0044] The voltage divider substrate 430 has all the electrodes that the voltage divider substrate 330 has. That is, the voltage divider substrate 430 has first potential electrodes 131a, 131b, 131e, a second potential electrode 132, and an output electrode 136. The first potential electrodes 131a, 131b, and 131e are connected by vias 134 and 135, similar to the voltage divider substrate 330.

[0045] In the fourth embodiment, the voltage divider substrate 430 has a first potential electrode 131b that is not on the surface, but a solid dielectric layer 438 extending over it, and a third potential electrode 450 is provided on the surface. Lands 460 are also provided on the surface of the voltage divider substrate 430. Figure 8 is a cross-sectional view of the voltage divider substrate 430 cut along line VIII-VIII in Figure 7, when it is replaced with the voltage divider substrate 330.

[0046] Land 460 is the area where the connector 440 is attached to the voltage divider board 430. An example of the connector 440 is an SMA connector. Pin 441 of the connector 440 is connected to via 137. The connector 440 is coupled to the shield wire 140, which is a signal line. The third potential electrode 450 is in contact with the connector case 442 of the connector 440. The third potential electrode 450 is at the same potential as the housing 110.

[0047] This voltage divider board 430 has a third potential electrode 450 on the connector 440 side of the first potential electrode 131 that is at the same potential as the housing 110. This third potential electrode 450 also functions as a guard electrode. Therefore, the decrease in voltage measurement accuracy can be further suppressed.

[0048] Furthermore, by using the shielded wire 140, the reduction in voltage measurement accuracy due to external noise flying into the signal path on the oscilloscope 20 side of the connector 440 is suppressed. The wire diameter of the signal line in the shielded wire 140 is made sufficiently small for the current flowing through it. In this way, even if a large current flows through the signal line, the signal line will function as a fuse, preventing a large current from flowing through the differential probe 30 or the oscilloscope 20.

[0049] <Fifth Embodiment> Figure 9 is a cross-sectional view of the voltage divider substrate 530 of the fifth embodiment. Figure 9 is a cross-sectional view of the voltage divider substrate 530 cut in the same cross-section as in Figure 8. The configuration of the first, third, and fourth surface layers of the voltage divider substrate 530 is the same as that of the voltage divider substrate 430 of the fourth embodiment.

[0050] A parasitic capacitance guard electrode 536 is positioned in the second layer. The parasitic capacitance guard electrode 536 is connected to the second potential electrode 132 via 137. Therefore, the potential of the parasitic capacitance guard electrode 536 is the second potential. The parasitic capacitance guard electrode 536 is positioned opposite the third potential electrode 450.

[0051] The second layer also contains the first potential electrode 131f. The external shape of the first potential electrode 131f is the same as that of the first potential electrode 131a located in the fourth layer. Similar to the voltage divider substrate 330, the first potential electrode 131f is connected to the first potential electrode 131e in the third layer and the first potential electrode 131a in the fourth layer via vias 134 and 135.

[0052] Because of the parasitic capacitance guard electrode 536, the first potential electrode 131f is smaller than the first potential electrode 131b in the fourth embodiment. Therefore, when viewed from the stacking direction of the first potential electrode 131 and the second potential electrode 132, the third potential electrode 450 is sized so as not to overlap with the parasitic capacitance guard electrode 536 and the first potential electrode 131f, which is on the same layer. Furthermore, the third potential electrode 450 is approximately the same size as the parasitic capacitance guard electrode 536, and when viewed from the stacking direction of the first potential electrode 131 and the second potential electrode 132, the third potential electrode 450 covers the parasitic capacitance guard electrode 536.

[0053] In the embodiment described above, as shown in Figure 8, capacitive coupling occurs between the third potential electrode 450 and the first potential electrode 131b. As a result, noise generated in the voltage to be measured is fed back to GND. Depending on the capacitance generated between the third potential electrode 450 and the first potential electrode 131b, the measurement accuracy of the voltage to be measured may decrease.

[0054] On the other hand, in this embodiment, the parasitic capacitance guard electrode 536 and the third potential electrode 450 are capacitively coupled. Since the parasitic capacitance guard electrode 536 is at the same potential as the second potential electrode 132 and not at the potential of the housing 110, the return of noise generated in the voltage to be measured to GND is suppressed. Therefore, it is possible to suppress the reduction in voltage measurement accuracy caused by noise generated in the voltage to be measured being returned to GND.

[0055] Furthermore, the capacitance generated by the capacitive coupling between the parasitic capacitance guard electrode 536 and the third potential electrode 450 is sufficiently smaller than the capacitance of the chip capacitor 122, and therefore does not pose a problem in voltage measurement.

[0056] Furthermore, the third potential electrode 450 is sized to cover the parasitic capacitance guard electrode 536 when viewed from the stacking direction of the first potential electrode 131 and the second potential electrode 132, and not to overlap with the first potential electrode 131f. Therefore, while suppressing capacitive coupling between the third potential electrode 450 and the first potential electrode 131f, the third potential electrode 450 can suppress the propagation of external noise to the second potential electrode 132.

[0057] <Sixth Embodiment> Figure 10 shows the shape of each layer of the voltage divider substrate 630 of the sixth embodiment. The first layer is provided with a third potential electrode 650 and an output electrode 660. The third potential electrode 650 is at the same potential as the housing 110. A connector 440 is installed on the upper surface of the third potential electrode 650, similar to the fifth embodiment.

[0058] The output electrode 660 comprises a connector connection portion 661, a via connection portion 662, and a connecting portion 663. The connector connection portion 661 is circular and surrounded by the third potential electrode 650, except for the portion where the connecting portion 663 protrudes. The connector connection portion 661 is connected to pin 441 of the connector 440. The via connection portion 662 is ring-shaped and connects to via 137. The connecting portion 663 connects the connector connection portion 661 and the via connection portion 662. The output electrode 660 is connected to the second potential electrode 632 of the third layer by via 137. Therefore, the potential of the output electrode 660 is the second potential.

[0059] The second layer contains a parasitic capacitance guard electrode 636 and a first potential electrode 131g. The parasitic capacitance guard electrode 636 is connected to the second potential electrode 632 by a via 137. Therefore, the potential of the parasitic capacitance guard electrode 636 is also the second potential. The parasitic capacitance guard electrode 636 faces the third potential electrode 650 and, when viewed from the direction of electrode stacking, is sized to include the third potential electrode 650. The external shape of the first potential electrode 131g is the same as that of the first potential electrode 131a of the fourth layer. The first potential electrode 131g has a hole 638 formed therein for accommodating the parasitic capacitance guard electrode 636.

[0060] The third layer contains a second potential electrode 632 and a first potential electrode 131h. The second potential electrode 632 extends further in the x-axis direction than the previous second potential electrode 132. This is to increase the portion that faces the first potential electrode 131g of the second layer.

[0061] According to this sixth embodiment, the parasitic capacitance guard electrode 636 is large, and when viewed from the direction of electrode stacking, the size of the parasitic capacitance guard electrode 636 includes the third potential electrode 650. Therefore, the parasitic capacitance guard electrode 636 can sufficiently suppress capacitive coupling between the third potential electrode 650 and the first potential electrode 131g.

[0062] <Seventh Embodiment> Figure 11 shows the shape of the electrodes in each layer of the voltage divider substrate 730 of the seventh embodiment. The voltage divider substrate 730 of the seventh embodiment differs from the second potential electrode 132 of the third embodiment in the shape of the second potential electrode 732. Otherwise, it is the same as the third embodiment.

[0063] The second potential electrode 732 comprises a via connection portion 732a, a main second potential electrode portion 732b, and a connecting portion 732c. The via connection portion 732a is ring-shaped and in contact with via 137. The via connection portion 732a faces the output electrode 136. The main second potential electrode portion 732b is provided separately from the via connection portion 732a and occupies most of the area of ​​the second potential electrode 732. The connecting portion 732c connects the via connection portion 732a and the main second potential electrode portion 732b.

[0064] With this configuration, when the voltage divider substrate 730 is viewed from the stacking direction of the first potential electrode 131, the main second potential electrode portion 732b has less overlap with the output electrode 136, which is in the same layer as the first potential electrode 131b. In other words, with this configuration, the second potential electrode 732 has a larger portion facing the first potential electrode 131b. This makes it easier to form capacitance between the first potential electrode 131b and the second potential electrode 732.

[0065] <Eighth Embodiment> In the eighth embodiment, the connection configuration between the voltage divider board and the device under test (DUT) will be described. Figure 12 shows a voltage divider board 530 as the voltage divider board. However, the voltage divider board 530 may be replaced with a voltage divider board described in another embodiment. An example of a DUT is a three-phase busbar 40.

[0066] The voltage divider substrate 530 and the DUT are interconnected via an intermediate fastening member 810. The intermediate fastening member 810 is conductive. The intermediate fastening member 810 comprises a substrate support portion 810a and a measurement target coupling portion 810b. The substrate support portion 810a is in contact with the first potential electrode 131a. The substrate support portion 810a is coupled to the voltage divider substrate 530 by a bolt 820 that penetrates the voltage divider substrate 530 from the thickness direction of the electrode. The measurement target coupling portion 810b is in contact with the DUT and is coupled to the DUT by a bolt 830. The bolts 820 and 830 correspond to the first fastening member and the second fastening member, respectively.

[0067] In this configuration, the intermediate fastening member 810 electrically connects the first potential electrode 131a and the DUT, and also supports the voltage divider substrate 530. By including the intermediate fastening member 810, it is possible to increase the axial force by the bolts 820 and 830, and to electrically connect the voltage divider substrate 530 and the DUT.

[0068] <Ninth Embodiment> Figure 13 shows the voltage divider board 930 of the ninth embodiment. The voltage divider board 930 has a chip capacitor 922, which is a capacitance component, on its upper surface. This chip capacitor 922 is provided in place of the chip capacitor 122 that was provided on the housing board 120 in the previous embodiments.

[0069] The chip capacitor 922 is connected to the third potential electrode 450 and the top electrode 931. The top electrode 931 is connected to the parasitic capacitance guard electrode 936 via 932. The parasitic capacitance guard electrode 936 is larger than the parasitic capacitance guard electrode 536 in order to connect to the via 932. The parasitic capacitance guard electrode 936 is connected to the second potential electrode 132 via 137.

[0070] As in this ninth embodiment, by providing the chip capacitor 922 on the upper surface of the voltage divider board 930, it becomes easier to obtain the potential of the housing side of the chip capacitor 922.

[0071] <Tenth Embodiment> The tenth embodiment is an embodiment that describes the configuration of the housing substrate 120. Figure 14 shows the configuration of the housing substrate 120. The housing substrate 120 includes a second potential section 111 in part, which is connected to the second potential electrode 132 via a shield wire 140. The remaining part is a housing potential section 112, which is at the housing potential, i.e., the third potential. The chip capacitor 122 is connected to the second potential section 111 and the housing potential section 112.

[0072] In this configuration, the chip capacitor 122 is placed on the housing substrate 120, and the housing substrate 120 is electrically connected to the voltage divider substrate 530 by a shield wire 140. By doing so, the resonance peak of the voltage divider circuit 170 is on the high-frequency side, compared to when the chip capacitor 922 is placed on the voltage divider substrate 530, making it less likely for the measured voltage and the resonance peak to overlap.

[0073] In addition, by providing the chip capacitor 122 on the housing substrate 120, the influence of parasitic inductance on the frequency characteristics can be reduced compared to providing the chip capacitor 122 on the voltage divider substrate 530. Figure 15 is a diagram comparing the frequency characteristics of the attenuation when the chip capacitor 122 is provided on the housing substrate 120 as in the 10th embodiment, and when the chip capacitor 122 is provided on the voltage divider substrate 530 as a comparative example. LC resonance occurs due to the presence of parasitic inductance in the shield wire 140. However, it can be seen that resonance can be suppressed by providing the chip capacitor 122 on the housing substrate 120 as in the embodiment.

[0074] <Embodiment 11> Figure 16 shows a configuration diagram of the voltage measurement system 1000 according to the 11th embodiment. The voltage measurement system 1000 comprises two voltage divider boards 130 and 1130. The voltage divider board 130 is the same as described in the first embodiment. The voltage divider board 1130 has the same structure as the voltage divider board 130.

[0075] Figure 17 shows a cross-sectional view of the voltage divider substrate 1130. The voltage divider substrate 1130 has the same structure as the voltage divider substrate 130, but to distinguish it from the electrodes of the voltage divider substrate 130, the electrode corresponding to the first electrode 131 in the voltage divider substrate 130 is called the fourth potential electrode 1131 in the voltage divider substrate 1130. Also, the electrode corresponding to the second electrode 132 in the voltage divider substrate 130 is called the fifth potential electrode 1132 in the voltage divider substrate 1130. Note that instead of the voltage divider substrates 130 and 1130, the voltage divider substrates 230, 330, 440, 530, 630, and 730 described in other embodiments may be used.

[0076] Let's return to the explanation in Figure 16. The measuring potential section 130a on the voltage divider board 130 is the part that will be measured. For example, the voltage 160 is the measuring potential section. The measuring potential section 130a is connected to, for example, the three-phase busbar 40.

[0077] The measuring potential section 1130a on the voltage divider board 1130 is also a part of the potential to be measured. For example, the bolt 160 fixed to the voltage divider board 1130 is the measuring potential section. The measuring potential section 1130a is connected to the PN busbar of the inverter.

[0078] The enclosure board 1120 has a configuration that adds a chip capacitor 1122 to the configuration of the enclosure board 120 described in the first embodiment. The capacitance of the chip capacitor 1122 is the same as the capacitance of the chip capacitor 122.

[0079] The housing substrate 1120 is provided separately from the voltage divider substrates 130 and 1130 and is connected to them by shield wires 140 and 1140. Shield wire 140 is the same as in the first embodiment and connects the second potential electrode 132 to the chip capacitor 122 provided on the housing substrate 120. Another shield wire 1140 connects the fifth potential electrode 1132 to the chip capacitor 1122 provided on the housing substrate 120. The same shield wire 140 can be used for shield wire 1140. One end of the chip capacitors 122 and 1122 is connected to the housing potential section 1130.

[0080] The housing potential section 1130 is electrically connected to the housing 110 and is at the same potential as the housing 110. The housing potential section 1130 is, for example, a bolt that fixes the housing substrate 1120 to the housing 110.

[0081] One end of chip capacitors 122 and 1122 is connected to the housing potential section 1130. In this embodiment, chip capacitor 122 is the first capacitance section and is located in the electrical path between the second potential electrode 132 of the voltage divider substrate 130 and the housing potential section 1130, which is at the potential of the housing 110. Chip capacitor 1122 is the second capacitance section and is located in the electrical path between the fifth potential electrode 1132 of the voltage divider substrate 1130 and the housing potential section 1130.

[0082] The voltage detection unit 1030 detects the potential difference between the potential of wiring 1140 and the potential of wiring 1150. Wiring 1140 connects the shield wire 140 and the chip capacitor 122. Wiring 1150 connects the shield wire 1140 and the chip capacitor 1122. Therefore, the voltage detection unit 1030 detects the potential difference between the potential between the housing 110 and the second potential electrode 132 and the potential between the housing 110 and the fifth potential electrode 1132. A differential probe can be used in the voltage detection unit 1030.

[0083] Figure 18 shows the equivalent circuit of the voltage measurement system 1000. Capacitance Cb is the capacitance of chip capacitors 122 and 1222. Capacitance Ca is formed by the voltage divider boards 130 and 1130. As shown in Figure 18, the voltage measurement system 1000 measures differential voltage. The measurement potential section 130a of the voltage divider board 130 is connected to the U phase of the inverter circuit 1200, and the measurement potential section 1130a of the voltage divider board 1130 is connected to the N terminal of the inverter circuit 1200. Therefore, the fourth potential electrode 1131 provided on the voltage divider board 1130 is connected to a potential different from the potential to which the first potential electrode 131 provided on the voltage divider board 130 is connected.

[0084] A voltage divider circuit 170 is formed by the capacitance Cb of the chip capacitor 122 and the capacitance Ca formed by the voltage divider substrate 130. A voltage divider circuit 1170 is also formed by the capacitance Cb of the chip capacitor 1122 and the capacitance Ca formed by the voltage divider substrate 1130. The voltage divider circuit 170 inputs the potential between the housing 110 and the second potential electrode 132 to the voltage detection unit 1030. The voltage divider circuit 1170 inputs the potential between the housing 110 and the fifth potential electrode 1132 to the voltage detection unit 1030.

[0085] The smaller the capacitance ratio Ca / Cb, the more the voltage divider circuits 170 and 1170 can step down the input voltage. Therefore, it is preferable that capacitance Ca is small compared to capacitance Cb. Capacitors Ca and Cb are determined such that the capacitance ratio Ca / Cb is, for example, about 1 / 100. In this case, the voltage divider circuits 170 and 1170 can step down the input voltage to 1 / 100.

[0086] Since the capacitance ratio Ca / Cb is approximately 1 / 100, the voltage divider circuit 1170 steps down the voltage at the N terminal to approximately 1 / 100. For example, if the potential at the N terminal is -200V, the voltage divided by the voltage divider circuit 1170 steps down to -2V, which is input to the voltage detection unit 1030. In addition, the voltage divider circuit 170 steps down the potential of the U phase to approximately 1 / 100. For example, if the potential at the P terminal is 200V, the potential of the U phase will be up to 200V, but the voltage divider circuit 170 steps down the potential to a maximum of 2V, which is input to the voltage detection unit 1030. By stepping down the potential input to the voltage detection unit 1030 in this way, it is possible to prevent the potential and potential difference input to the voltage detection unit 1030 from exceeding the voltage withstand voltage of the voltage detection unit 1030. The capacitance values ​​Ca and Cb are determined, from one perspective, so that the potential and potential difference input to the voltage detection unit 1030 do not exceed the withstand voltage of the voltage detection unit 1030.

[0087] The voltage detection unit 1030 detects the potential difference between the potential of the N terminal, which is stepped down by the voltage divider circuit 1170, and the potential of the U phase, which is stepped down by the voltage divider circuit 170. The voltage detection unit 1030 is operational and can detect the output voltage of the inverter 1200 circuit as a potential difference even if the potential of the housing 110 is not grounded.

[0088] In addition, even if the input potential (the potential of the N terminal in Figure 18) and the output potential (the potential of the U phase in Figure 18) are at high potentials, the voltage divider circuits 1170 and 170 step down both the input potential and the output potential before they are input to the voltage detection unit 1030. Therefore, it is possible to prevent components of the voltage detection unit 1030 (for example, the voltage probe) from being damaged by high voltage.

[0089] Since the structures of the two voltage divider boards 130 and 1130 are the same, the capacitance between the first potential electrode 131 and the second potential electrode 132 is the same as the capacitance between the fourth potential electrode 1131 and the fifth potential electrode 1132. Also, the capacitances of the two chip capacitors 122 and 1122 are the same. Therefore, the voltage division ratios of the two voltage divider circuits 170 and 1170 are the same. By stepping down the two potentials input to the voltage detection unit 1030 using the two voltage divider circuits 170 and 1170, which have the same voltage division ratio, the accuracy of voltage detection by the voltage detection unit 1030 is improved.

[0090] The capacitances Ca and Cb of the voltage divider circuits 170 and 1170 are determined such that the potential and potential difference input to the voltage detection unit 1030 are lower than the voltage withstand capability of the voltage detection unit 1030, thereby preventing damage to the voltage detection unit 1030.

[0091] The capacitance of the voltage divider substrate 130, that is, the capacitance between the first potential electrode 131 and the second potential electrode 132, is smaller than the capacitance of the chip capacitor 122, which is the first capacitance section. Similarly, the capacitance of the voltage divider substrate 1130, that is, the capacitance between the fourth potential electrode 1131 and the fifth potential electrode 1132, is smaller than the capacitance of the chip capacitor 1122, which is the second capacitance section. By doing this, the input voltage in the voltage divider circuits 170 and 1170 can be stepped down to a lower voltage compared to when the relationship between the magnitudes of the capacitances is reversed.

[0092] <Twelfth Embodiment> Figure 19 shows a configuration diagram of the voltage measurement system 2000 according to the twelfth embodiment. The voltage measurement system 2000 includes two voltage divider boards 2130, which are different from the voltage divider boards 130 and 1130 that are included in the voltage measurement system 1000 of the eleventh embodiment. The two voltage divider boards 2130 have the same configuration, but one is designated as the first voltage divider board 2130A and the other as the second voltage divider board 2130B. The other configurations of the voltage measurement system 2000 are the same as those of the eleventh embodiment.

[0093] The first voltage dividing board 2130A is provided in place of the voltage dividing board 130 of the 11th embodiment. The first voltage dividing board 2130A differs from the voltage dividing board 130 in that it includes a voltage dividing board side first capacitance section 2131A, which is a voltage dividing board side capacitance section 2131. The configuration of the first voltage dividing board 2130A is the same as that of the voltage dividing board 130, except for the voltage dividing board side first capacitance section 2131A and the configuration related to the voltage dividing board side first capacitance section 2131A. Therefore, the first voltage dividing board 2130A includes a first potential electrode 131 and a second potential electrode 132.

[0094] The first capacitance section 2131A on the voltage divider substrate side is provided on the surface of the first voltage divider substrate 2130A. A chip capacitor can be used for the first capacitance section 2131A on the voltage divider substrate side. The first capacitance section 2131A on the voltage divider substrate side is located in the path between the second potential electrode 132 and the shield wire 140.

[0095] The second voltage divider board 2130B is provided in place of the voltage divider board 1130 of the 11th embodiment. The second voltage divider board 2130B differs from the voltage divider board 1130 in that it includes a voltage divider board side second capacitance section 2131B, which is a voltage divider board side capacitance section 2131. The configuration of the second voltage divider board 2130B is the same as that of the voltage divider board 1130 except for the voltage divider board side second capacitance section 2131B and the configuration related to the voltage divider board side second capacitance section 2131B. Therefore, the second voltage divider board 2130B includes a fourth potential electrode 1131 and a fifth potential electrode 1132.

[0096] The second capacitance section 2131B on the voltage divider substrate side is provided on the surface of the second voltage divider substrate 2130B. A chip capacitor can be used for the second capacitance section 2131B on the voltage divider substrate side. The second capacitance section 2131B on the voltage divider substrate side is located in the path between the fifth potential electrode 1132 and the shield wire 1140.

[0097] The configuration of the enclosure board 1120 is the same as in the 11th embodiment. In this 12th embodiment, the chip capacitors 122 and 1112 correspond to the enclosure-side capacitance section. More specifically, the chip capacitor 122 corresponds to the first enclosure-side capacitance section, and the chip capacitor 1112 corresponds to the second enclosure-side capacitance section. Also, the shield wire 140 corresponds to the first shield wire, and the shield wire 1140 corresponds to the second shield wire.

[0098] Figure 20 shows the equivalent circuit of the voltage measurement system 2000. Capacitance Ca1 is the same as capacitance Ca in Figure 18, and is the capacitance between the first potential electrode 131 and the second potential electrode 132, or the capacitance between the fourth potential electrode 1131 and the fifth potential electrode 1132. Capacitance Ca2 is the capacitance of the first capacitance section 2131A or the second capacitance section 2131B on the voltage divider substrate side.

[0099] As shown in Figure 20, voltage divider circuits 2170A and 2170B are formed by capacitors Ca1, Ca2, and Cb connected in series. The voltage detection unit 1030 detects the potential difference between the first capacitor section 2131A on the voltage divider board side and the housing 110, and the potential difference between the second capacitor section 2131B on the voltage divider board side and the housing 110.

[0100] Therefore, in the voltage divider circuits 2170A and 2170B, capacitances Ca1 and Ca2 can be considered as a single capacitance. If both capacitances Ca1 and Ca2 are 5pF, the combined capacitance of Ca1 and Ca2 will be 2.5pF.

[0101] In this twelfth embodiment, since the first capacitance units 2131A and 2131B on the voltage divider substrate side are provided on the surfaces of the first voltage divider substrate 2130A and the second voltage divider substrate 2130B, the first capacitance units 2131A and 2131B on the voltage divider substrate side can be easily replaced. Therefore, the capacitance ratio can be easily adjusted.

[0102] Furthermore, in this embodiment, the capacitance of the first capacitance section 2131A on the voltage divider substrate side is the same as the capacitance between the first potential electrode 131 and the second potential electrode 132. Also, the capacitance of the second capacitance section 2131B on the voltage divider substrate side is the same as the capacitance between the fourth potential electrode 1131 and the fifth potential electrode 1132. By doing so, it is possible to suppress the influence of the capacitances of the first capacitance section 2131A and the second capacitance section 2131B on the voltage divider substrate side on the capacitance ratio. Therefore, it is particularly easy to adjust the capacitance ratio by replacing the first capacitance sections 2131A and 2131B on the voltage divider substrate side.

[0103] Furthermore, the capacitance Ca2 of the first capacitance section 2131A and the second capacitance section 2131B on the voltage divider substrate side may be made smaller. By making the capacitance Ca2 smaller, the influence of the capacitance of the first capacitance section 2131A and the second capacitance section 2131B on the voltage divider substrate side on the capacitance ratio can be increased.

[0104] Although embodiments have been described above, the disclosed technology is not limited to the embodiments described above and can be implemented with various modifications without departing from the gist of the invention. For example, other capacitors that are not chip capacitors may be used instead of the chip capacitors described in the embodiments. [Explanation of symbols]

[0105] 110...Housing, 122...Chip capacitor (capacitance section, first capacitance section, housing-side first capacitance section), 131...First potential electrode, 132...Second potential electrode, 136...Output electrode, 137...Via, 138...Solid dielectric layer, 438...Solid dielectric layer, 440...Connector, 450...Third potential electrode, 536...Parasitic capacitance guard electrode, 632...Second potential electrode, 636...Parasitic capacitance guard electrode, 732...Second potential electrode, 732a...Via connection section, 732b...Main second potential electrode section, 732c...Connecting section, 81 0…Intermediate fastening member, 820…Bolt (first fastening member), 830…Bolt (second fastening member), 922…Chip capacitor (capacitance part), 936…Parasitic capacitance guard electrode, 1122…Chip capacitor (second capacitance part, housing side second capacitance part), 1130…Voltage detection unit, 1131…Fourth potential electrode, 1132…Fifth potential electrode, 2130…Voltage divider board, 2130A…First voltage divider board, 2130B…Second voltage divider board, 2131A…Voltage divider board side first capacitance part, 2131B…Voltage divider board side second capacitance part

Claims

1. Multiple first potential electrodes (131) connected to the potential of the object to be measured, where an AC voltage is generated, It comprises a second potential electrode (132, 632, 732) sandwiched between the first potential electrodes and having a potential with respect to the first potential electrodes via capacitance, A voltage measuring device for measuring the potential between the housing (110) and the second potential electrode.

2. A solid dielectric layer (138, 438) is formed between the first potential electrode and the second potential electrode. The voltage measuring device according to claim 1.

3. When viewed from the stacking direction of the first potential electrode and the second potential electrode, the second potential electrode is located inside the contour of the first potential electrode. The voltage measuring device according to claim 1 or 2.

4. The first potential electrode is also provided on the same layer as the second potential electrode. The voltage measuring device according to claim 1.

5. Two of the first potential electrodes are provided on the same layer as the second potential electrode, with the second potential electrode in between. The voltage measuring device according to claim 4.

6. The first potential electrode is provided on the same layer as the second potential electrode, surrounding the second potential electrode. The voltage measuring device according to claim 4.

7. The device includes a connector (440) that connects to a signal line connected to the second potential electrode, A third potential electrode (450) having the same potential as the housing is provided on the connector side of the first potential electrode. The voltage measuring device according to claim 1 or 2.

8. A parasitic capacitance guard electrode (536, 636, 936) having the same potential as the second potential electrode is provided at a position opposite to the third potential electrode. The voltage measuring device according to claim 7.

9. The first potential electrode is provided in the same layer as the parasitic capacitance guard electrode, The third potential electrode is sized such that, when viewed from the stacking direction of the first potential electrode and the second potential electrode, it does not overlap with the first potential electrode, which is in the same layer as the parasitic capacitance guard electrode, and is sized to cover the parasitic capacitance guard electrode. The voltage measuring device according to claim 8.

10. The output electrode (136) is located in the same layer as the first potential electrode, The system includes a via (137) connecting the output electrode and the second potential electrode, The second potential electrode (732) is A via connection portion (732a) that is in contact with the via and facing the output electrode, A main second potential electrode portion (732b) is provided away from the via connection portion, The system includes a connecting portion (732c) that connects the via connection portion and the main second potential electrode portion. The voltage measuring device according to claim 1 or 2.

11. A relay fastening member (810) that supports the first potential electrode and connects to the object to be measured, A first fastening member (820) connects the relay fastening member and the first potential electrode, The device comprises a second fastening member (830) that connects the aforementioned relay fastening member to the object to be measured. The voltage measuring device according to claim 1 or 2.

12. The second potential electrode is connected to the potential of the housing and comprises a capacitance section (122, 922) having capacitance. The voltage measuring device according to claim 1 or 2.

13. The first potential electrode and the second potential electrode are arranged on a single voltage divider substrate. The capacitance unit (922) is arranged on the voltage divider substrate. The voltage measuring device according to claim 12.

14. The first potential electrode and the second potential electrode are arranged on a single voltage divider substrate. The capacitance unit (122) is located on a housing substrate which is electrically connected to the voltage divider substrate by a shield wire. The voltage measuring device according to claim 12.

15. Multiple fourth potential electrodes (1131) connected to a potential different from the potential to which the first potential electrode is connected, It comprises a fifth potential electrode (1132) sandwiched between the fourth potential electrodes and having a potential with respect to the fourth potential electrode via capacitance, The potential difference between the potential between the housing and the second potential electrode and the potential between the housing and the fifth potential electrode is measured. The voltage measuring device according to claim 1.

16. A first capacitance section (122) having capacitance is located in the path between the second potential electrode and the potential of the housing, It comprises a second capacitance portion (1122) having capacitance, located in the path between the fifth potential electrode and the potential of the housing, The capacitance between the first potential electrode and the second potential electrode is the same as the capacitance between the fourth potential electrode and the fifth potential electrode. The capacitance of the first capacitance section and the capacitance of the second capacitance section are the same. The voltage measuring device according to claim 15.

17. The system includes a voltage detection unit (1030) that detects the potential difference between the potential between the housing and the second potential electrode and the potential between the housing and the fifth potential electrode. The capacitance between the first potential electrode and the second potential electrode, the capacitance between the fourth potential electrode and the fifth potential electrode, the capacitance of the first capacitance section, and the capacitance of the second capacitance section are such that the potential between the housing and the second potential electrode and the potential between the housing and the fifth potential electrode are lower than the withstand voltage of the voltage detection section. The voltage measuring device according to claim 16.

18. A first capacitance section (122) having capacitance is located in the path between the second potential electrode and the potential of the housing, It comprises a second capacitance portion (1122) having capacitance, located in the path between the fifth potential electrode and the potential of the housing, The capacitance between the first potential electrode and the second potential electrode is smaller than the capacitance of the first capacitance portion. The capacitance between the fourth potential electrode and the fifth potential electrode is smaller than the capacitance of the second capacitance portion. The voltage measuring device according to claim 15.

19. The first potential electrode and the second potential electrode are arranged on the first voltage dividing substrate (2130A). The fourth potential electrode and the fifth potential electrode are arranged on the second voltage dividing substrate (2130B). A housing substrate (1120) is separated from the first and second voltage dividing substrates, connected to the first voltage dividing substrate by a first shield wire (140), and connected to the second voltage dividing substrate by a second shield wire (1140), In the housing substrate, a housing-side first capacitance portion (122) having capacitance is located in the path between the second potential electrode and the potential of the housing, In the housing substrate, a second housing-side capacitance portion (1112) having capacitance is located in the path between the fourth potential electrode and the potential of the housing, On the first voltage dividing substrate, a first capacitance portion (2131A) on the voltage dividing substrate side is located in the path between the second potential electrode and the first shield wire, On the second voltage dividing substrate, a second capacitance portion (2131B) on the voltage dividing substrate side is located in the path between the fourth potential electrode and the second shield wire, The voltage measuring device according to claim 15, comprising:

20. The capacitance of the first capacitance portion on the voltage divider substrate side is less than or equal to the capacitance between the first potential electrode and the second potential electrode. The capacitance of the second capacitance portion on the voltage divider substrate side is less than or equal to the capacitance between the fourth potential electrode and the fifth potential electrode. The voltage measuring device according to claim 19.

21. The first potential electrode and the second potential electrode are arranged on a voltage dividing substrate (2130). A housing substrate (1120) is separated from the voltage divider substrate and connected to the voltage divider substrate by a shielded wire, In the housing substrate, there are housing-side capacitance portions (122, 1112) located in the path between the second potential electrode and the potential of the housing, and having capacitance, On the voltage divider substrate, a voltage divider substrate-side capacitance portion (2131) located in the path between the second potential electrode and the shield wire, The voltage measuring device according to claim 1, comprising:

22. The capacitance of the voltage divider substrate side capacitance portion is less than or equal to the capacitance between the first potential electrode and the second potential electrode. The voltage measuring device according to claim 21.

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