JP2022072230A - Current detector and power conversion device - Google Patents

Abstract

To provide a low-cost, small man-hour current detector for power conversion devices.SOLUTION: This current detector is composed by having a bus bar 11 for voltage detection of a conductive member connected to a computation unit. The bus bar 11 for voltage detection has such an electric characteristic regarding two types of conductors 11a, 11b differing in length and width and equal in thickness, that resistance values R are different and inductance values L are the same. A differential voltage between the first voltage of a bus bar A detected using a voltage detection unit 13a and a reference potential unit 13b at points corresponding to both ends of the conductor 11a and the second voltage of a bus bar B detected using a voltage detection unit 13c and the reference potential unit 13b at points corresponding to both ends of the conductor 11b is divided by a differential resistance between the previously designed first resistance of the bus bar A and second resistance of the bus bar B by the computation unit, and current detection is carried out applying Ohm's law. The inductance component voltage is cancelled out at differential voltage computation time.SELECTED DRAWING: Figure 1

Description

The present invention relates to a current detector and a power converter.

In recent years, there has been a problem that the unit size increases with the increase in output of the power conversion device. In order to solve this problem, miniaturization of a current detector that measures the current flowing in the power converter is being studied.

In a power converter, a current detector that utilizes the Hall effect, which is generally used, has a small sensor sensitivity of the Hall element itself, and a sufficient output cannot be obtained by the element alone. For this reason, current detection is made possible by utilizing a magnetic core and an amplifier circuit, but on the other hand, such utilization causes an increase in the size of the current detector and hinders the miniaturization of the power conversion device. ..

Therefore, as a current detection method that can reduce the size of a current detector, a technique of detecting a current using a shunt resistor is known. As a well-known technique related to such current detection, "shunt resistor and its manufacturing method" (see Patent Document 1) having improved current detection accuracy in a resistor for large current detection with a low resistance value of 1 mΩ or less. , "Shunt resistor and shunt type current detector" for detecting the current flowing through the resistor (see Patent Document 2) and the like.

Japanese Unexamined Patent Publication No. 2011-3694 JP-A-2017-208475

In the techniques according to Patent Document 1 and Patent Document 2 described above, a shunt resistor is connected to a path for passing a current to detect the current. However, shunt resistors are generally constructed by joining two or more types of metal materials. Therefore, there are problems such as an increase in man-hours for joining metal materials and an increase in cost due to the use of a plurality of metal materials.

One method to solve these problems is to detect the voltage drop of the resistance component parasitic on the bus bar, which is used as the current path of the power converter instead of the shunt resistor, and detect the current according to Ohm's law. Conceivable. Since a bus bar is usually formed by pressing one type of metal, it can be said that the cost and man-hours are lower than that of a shunt resistor formed by joining two or more types of metal materials. However, busbars usually have an inductance component in addition to a resistance component. Therefore, when the current having an alternating current (AC) component is measured, the voltage generated in the bus bar is equal to the sum of the resistance component voltage and the inductance component voltage. In other words, it is impossible to simply apply Ohm's law to detect current. Due to these circumstances, no attempt has been made to detect alternating current using a bus bar.

The present invention has been made to solve such a problem. An object of the present invention is to provide a current detector capable of detecting a current having an AC component in a simplified configuration for a power conversion device, and a power conversion device using the current detector.

In order to solve the above problems, the bus bar of the present invention is a voltage detection bus bar that is connected so as to be conductive at a location where an AC current of a power conversion device passes, and the voltage detection bus bar is a first and second voltage detection bus bar. It has two conductor sections including a reference potential section, a first voltage detection section, and a second voltage detection section, and the two conductor sections have a first resistance value between the first voltage detection section and the first reference potential section. The ratio of the second resistance value between the second voltage detection unit and the second reference potential unit is the first inductance value between the first voltage detection unit and the first reference potential unit and the second voltage. It is characterized in that the ratio of the second inductance value between the detection unit and the second reference potential unit is different.

The two conductor portions may each be formed of one or more kinds of metal materials, and may have a shape obtained by changing at least two or more elements of a length, a width, and a thickness defining a shape.

The voltage detection bus bar may have a shape obtained by providing one or more types of notches in the substrate of the metal material.

The first and second reference potential portions may have the same potential.

The difference voltage between the voltage detection bus bar, the first voltage between the first voltage detection unit and the first reference potential unit, and the second voltage between the second voltage detection unit and the second reference potential unit. , The calculation unit that detects the current by dividing by the difference resistance value of the first resistance value and the second resistance value.

The current detector of the present invention may be provided at a place where an alternating current flows.

According to the above aspect of the present invention, a voltage detection bus bar is used as a current detector for a power conversion device. The two conductors of the voltage detection bus bar have different resistance values and have the same electrical characteristics as the inductance values. Therefore, in a situation where a current having an AC current component flows, only the inductance component voltage can be canceled by calculating the difference voltage of the voltages detected by the two conductor portions. Further, in the calculation unit, the difference voltage related to the voltage detected by using the voltage detection units provided at both ends of each conductor part of the voltage detection bus bar is divided by the difference resistance related to the resistance of each conductor part designed in advance. However, Ohm's law is applied to enable current detection. As a result, the current detector can be simplified and miniaturized, so that a miniaturized power conversion device can be provided in the configuration of the other aspect or the configuration of another aspect.

It is a perspective view which showed the appearance structure of the bus bar for voltage detection used in the current detector which concerns on Embodiment 1 of this invention from the upper side of one side surface. It is a perspective view which showed the appearance structure of the voltage detection bus bar which provided the voltage detection part and the reference potential part on the side surface from the upper side of one side surface. It is an equivalent circuit diagram about the bus bar of two conductors included in the bus bar for voltage detection shown in FIG. It is a perspective view which showed the appearance structure of the bus bar for voltage detection used in the current detector which concerns on Embodiment 2 of this invention from the upper side of one side surface. It is a perspective view which showed the appearance structure of the bus bar for voltage detection used in the current detector which concerns on Embodiment 3 of this invention from the upper side of one side surface. It is a figure which illustrates the basic structure of the power conversion apparatus which applied the bus bar for voltage detection shown in FIG. 1 and the current detector by the calculation part to the output stage of an inverter circuit part. It is a figure which showed the relationship of the current with respect to time under the condition that the current having an alternating current component flows to the bus bar for voltage detection shown in FIG. 1. (A) is a waveform diagram relating to the actual output current, and (b) is a waveform diagram relating to the detected current calculated by the arithmetic unit of the current detector based on the differential voltage of FIG. 8 (c). It is a figure which showed the waveform of the detection voltage under the condition that the current having an AC current component in the bus bar of the two conductors included in the bus bar for voltage detection shown in FIG. 1 is shown in the relationship of voltage with respect to time. (A) is a waveform diagram relating to the first voltage detected by the bus bar of one conductor portion, (b) is a waveform diagram relating to the second voltage detected by the bus bar of the other conductor portion, and (c) is a waveform diagram relating to the second voltage. It is a waveform diagram about the differential voltage which subtracted the 1st voltage of (a) from the 2nd voltage of (a).

As shown in FIG. 6, the current detector of the present invention is attached to a place where an alternating current of a power conversion device passes, and is composed of a voltage detection bus bar and a calculation unit. The current detector 100b in FIG. 6 is the current detector of the present invention, the voltage detection bus bar is the voltage detection bus bar 11, and the calculation unit is the calculation unit 110.

Hereinafter, the current detector according to some embodiments and the overall configuration example of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
In the present embodiment, the design method of the voltage detection bus bar used in the current detector of the present invention and the calculation method of the calculation unit are also described, but these contents are the same as those in the present embodiment in other embodiments, so they are omitted. do.

First, the shape of the voltage detection bus bar in this embodiment will be described.

FIG. 1 shows an example of a voltage detection bus bar 11 used in the current detector of the present invention. The voltage detection bus bar 11 has two types of shapes, which are different in length (longitudinal direction in FIG. 1) and width (short direction in FIG. 1) and have the same thickness (depth direction in FIG. 1). The conductor portions 11a and 11b are included. The length of the conductor portion 11a here is longer than the length of the conductor portion 11b, and the width of the conductor portion 11a is wider than the width of the conductor portion 11b. The conductor portion 11a and the conductor portion 11b in the present embodiment are examples of the two conductor portions in the claims.

Further, the voltage detection bus bar 11 has voltage detection portions 13a, 13c and a reference potential portion 13b provided at both ends of a portion that divides one conductor portion 11a and a portion that divides the other conductor portion 11b. There is. That is, the voltage detection bus bar 11 includes a voltage detection unit 13a and a reference potential unit 13b at both ends corresponding to one conductor portion 11a, and a voltage detection unit 13c and a reference potential portion 13b at both ends corresponding to the other conductor portion 11b. have. In the present embodiment, the reference potential portion 13b is configured to be shared by one conductor portion 11a and the other conductor portion 11b. Further, the bus bar A is located between the voltage detection unit 13a and the reference potential unit 13b, and the bus bar B is located between the voltage detection unit 13c and the reference potential unit 13b of the other conductor unit 11b. It is designed so that the resistance values R are equal and different. The hole portion 12 is a hole provided for connection with another conductor. In the present embodiment, the first and second reference potential portions in the claim are 13b. That is, this embodiment is the present embodiment in which the first and second reference potential portions have the same potential.

Further, in the voltage detection bus bar 11 of FIG. 1, the voltage detection portions 13a and 13c and the reference potential portion 13b are formed by the surface of the voltage detection bus bar 11 (longitudinal direction in FIG. 1 and lateral direction in FIG. 1). It is provided on the surface), but this is not the case. As an example, FIG. 2 shows a configuration in which the voltage detection units 13a and 13c and the reference potential unit 13b are provided on the side surface of the voltage detection bus bar 11. With the configuration as shown in FIG. 2, the voltage detection unit and the reference potential unit can be formed at the same time as the press working to form the bus bar. Therefore, it can be said that the man-hours are further smaller than that of the voltage detection bus bar 11 of FIG.

The voltage detection bus bar 11 of FIG. 1 measures the voltage by connecting a lead terminal to the pin-shaped voltage detection units 13a and 13c and the reference potential unit 13b, but the present invention is not limited to this. Instead of the lead terminal, the voltage measuring wire may be screwed to the voltage detection units 13a and 13c and the reference potential unit 13b.

The configuration of the voltage detection unit and the reference potential unit described above can be applied to the shapes of other voltage detection bus bars described later.

As described above, the voltage detection bus bar 11 needs to be designed so that the conductor portions 11a and 11b, that is, the resistance values R of the bus bar A and the bus bar B and the respective inductance values L are equal and the resistance values R are different. ..

The design method will be explained. A design method is shown when copper Cu is selected as the conductive member having the resistance value R and the inductance value L of the conductor portions 11a and 11b. The resistance value R when the conductive member is copper Cu can be obtained by the relational expression (A).
R [mΩ] = (ρ × d) / (t × w) × 10 Relational expression (A)
However, in the relational expression (A), d is the length [mm] of the conductor portions 11a and 11b, w is the width [mm] of the conductor portions 11a and 11b, and t is the thickness [mm] and ρ of the conductor portions 11a and 11b. Is the specific resistance [μΩm] of Cu copper.
Further, the inductance value L when the conductor portions 11a and 11b are copper Cu can be obtained by the relational expression (B).
L [nH] = 0.2 × d × (ln (2 × d) / (w + t) + 0.2235 × (w + t) / d + 0.5) Relational expression (B)
However, in the relational expression (B), d is the length [mm] of the conductor portions 11a and 11b, w is the width [mm] of the conductor portions 11a and 11b, and t is the thickness [mm] of the conductor portions 11a and 11b. Is the natural logarithm.

That is, it is possible to change at least two or more elements of the length, width, and thickness that define the shape of the two conductor portions of the voltage detection bus bar into different forms. The voltage detection bus bar of FIG. 1 has a structure in which the lengths and widths of the two conductors are changed to be different and the thicknesses are the same, but instead, the lengths of the two conductors are the same. A shape having a different width and a thickness, or a shape having the same width but a different length and a thickness may be applied. Even in such a case, if the resistance value R differs depending on the obtained shape and the inductance value L has the same electrical characteristics, the same effect can be obtained.

Although copper Cu is exemplified as one kind of metal material used for the voltage detection bus bar, another metal material may be used. For example, as an alternative metal material, a case where an alloy material such as Cu—Mn—Ni-based, Cu—Ni-based, or Ni—Cr-based is used can be exemplified.

Further, the method of deriving the resistance value R by the relational expression (A) and deriving the inductance value L by the relational expression (B) has been described. May be.

The above-mentioned design method can also be applied to the shapes of other voltage detection bus bars described later.

Next, the calculation method of the calculation unit will be described.

FIG. 3 is an equivalent circuit diagram of the bus bars A and B of the two conductor portions 11a and 11b included in the voltage detection bus bar 11. As described above, the bus bar A and the bus bar B are designed so that the inductance value L is the same and the resistance value R is different. Therefore, in the equivalent circuit of the bus bar A, the resistance value R1 and the inductance value L exist between the voltage detection unit 13a and the reference potential unit 13b, and the sum of the resistance component voltage VR1 and the inductance component voltage VL is detected. It is the first voltage VA. Further, also in the equivalent circuit of the bus bar B, the resistance value R2 and the inductance value L exist between the voltage detection unit 13c and the reference potential unit 13b, and the sum of the resistance component voltage VR2 and the inductance component voltage VL is detected. It is the second voltage VB.

Based on the above, the current calculation method in the current detector of the present invention will be described.

When an alternating current i flows through the voltage detection bus bar 11, the first voltage VA generated in the bus bar A and the bus bar B is represented by the relational expression (C) and the second voltage VB is represented by the relational expression (D) from FIG. be able to.
VA = (R1 × i) + L (di / dt) relational expression (C)
VB = (R2 × i) + L (di / dt) relational expression (D)

As described above, the bus bar A and the bus bar B are designed so that the inductance value L is the same and the resistance value R is different. Therefore, the difference voltage between the first voltage VA and the second voltage VB can be expressed by the relational expression (E) from the relational expression (C) and the relational expression (D).
(VB-VA) = (R2-R1) × i relational expression (E)
From the relational expression (E), it can be seen that the influence of the inductance component on the detected voltage can be eliminated by calculating the difference voltage between the first voltage VA and the second voltage VB. Further, when the relational expression (E) is solved for the alternating current i, the current flowing through the voltage detection bus bar 11 can be expressed by the relational expression (F).
i = (VB-VA) / (R2-R1) Relational expression (F)
From the relational expression (F), Ohm's law is applied by dividing the difference voltage between the first voltage VA and the second voltage VB by the difference between the first resistance R1 and the second resistance R2. It can be said that the current can be detected without being affected by the inductance component.

The calculation unit reads the value of the first voltage VA and the value of the second voltage VB as the detection values from the voltage detection bus bar, and calculates the relational expression (E) and the relational expression (F) using the arithmetic unit.
The arithmetic unit may be configured by using a digital arithmetic unit such as a microcomputer, or an analog arithmetic unit may be configured by using an operational amplifier or the like.

Since the calculation unit calculates the current using the relational expression (F), it is desirable that the resistance value R1 and the resistance value R2 are fixed values, but the resistance value of the voltage detection bus bar changes depending on its own temperature. Therefore, in order to improve the current detection accuracy, it is advisable to incorporate an algorithm for correcting the detected current according to the temperature in the arithmetic unit. For example, if the temperature of the bus bar for voltage detection is estimated based on the ambient temperature and the detection voltage, and the specific resistance value of the metal material corresponding to the obtained temperature is used in the calculation of current detection, the temperature can be corrected. be. Further, instead of estimating the temperature of the voltage detection bus bar, a temperature sensor may be installed near the voltage detection bus bar to actually measure the temperature of the voltage detection bus bar.

It is also an effective means to keep the temperature of the voltage detection bus bar constant by using a cooler such as a fan.

The current calculation method in the current detector, the calculation method of the calculation unit, the configuration of the calculation unit, and the temperature correction method of the calculation unit described above can also be applied to the embodiment of the voltage detection bus bar described later.

Regarding one embodiment of the current detector of the present invention, the structure of the voltage detection bus bar, the design method of the voltage detection bus bar, and the calculation method of the calculation unit have been described. As described above, the design method of the voltage detection bus bar and the calculation method of the calculation unit do not change even if the structure of the voltage detection bus bar changes, but various forms can be considered for the structure of the voltage detection bus bar. The embodiment is shown below as another embodiment.

(Embodiment 2)
FIG. 4 is a perspective view showing the external shape of the voltage detection bus bar 14 used in the current detector according to the second embodiment of the present invention from the upper side of one side surface.

Referring to FIG. 4, the voltage detection bus bar 14 has a different length (longitudinal direction in FIG. 4) and width (tall direction in FIG. 4) and a thickness (FIG. 4). It contains two types of conductor portions 14a and 14b having the same depth direction in 4. Here, the length of the conductor portion 14a is longer than the length of the conductor portion 14b, and the width of the conductor portion 14a is wider than the width of the conductor portion 14b. Further, a shallow notch 17 is provided above the conductor portion 14a in the width direction, and a deep notch 18 is separated from the shallow notch 17 above the conductor portion 14b in the width direction. It is provided. As a result, the two conductor portions 14a and 14b have electrical characteristics in which the resistance value R is different and the inductance value L is the same. That is, the voltage detection bus bar 14 has electrical characteristics due to the shape in which the notches 17 and 18 are provided with respect to the metal material. The conductor portion 14a and the conductor portion 14b in the present embodiment are examples of the two conductor portions in the claims.

Further, the voltage detection bus bar 14 has voltage detection units 16a, 16b, 16c, 16d provided at both ends of a portion that divides one conductor portion 14a and a portion that divides the other conductor portion 14b. .. That is, the voltage detection bus bar 14 has voltage detection units 16a and 16b at both ends corresponding to one conductor portion 14a and voltage detection portions 16c and 16d at both ends corresponding to the other conductor portion 14b. In the present embodiment, the reference potential portion of the conductor portion 14a may be selected from any one of the voltage detection portions 16a and 16b, and the reference potential portion of the conductor portion 14b may be any one of the voltage detection portions 16c and 16d. You just have to select. That is, the difference between the present embodiment and the voltage detection bus bar 11 of the first embodiment is that the voltage detection unit does not have a common reference potential unit. Due to this difference, the length between the voltage detection unit 16b and the voltage detection unit 16c can be freely changed, and it can be said that the degree of freedom in terms of structure is higher than in the case of the first embodiment.

(Embodiment 3)
FIG. 5 is a perspective view showing the external shape of the voltage detection bus bar 20 used in the current detector according to the third embodiment of the present invention from the upper side of one side surface.

Referring to FIG. 5, the voltage detection bus bar 20 has a different length (longitudinal direction in FIG. 5) and width (tall direction in FIG. 5) and a thickness (FIG. 5). It includes two types of conductor portions 20a and 20b having the same depth direction in 5. The length of the conductor portion 20a here is longer than the length of the conductor portion 20b, and the width of the conductor portion 20a is wider than the width of the conductor portion 20b. Further, a shallow notch 23a is provided above the conductor portion 20a in the width direction, and a deep notch 23b is connected to the shallow notch 23a above the conductor portion 20b in the width direction to form a step. A notch 23 having a shape is provided. As a result, the two conductor portions 20a and 20b have electrical characteristics in which the resistance value R is different and the inductance value L is the same. That is, the voltage detection bus bar 20 has electrical characteristics due to the shape obtained by providing the notch 23 with respect to the metal material. The conductor portion 20a and the conductor portion 20b in the present embodiment are examples of the two conductor portions in the claims.

Further, the voltage detection bus bar 20 has voltage detection portions 22a, 22c and a reference potential portion 22b provided at both ends of a portion that divides one conductor portion 20a and a portion that divides the other conductor portion 20b. ing. That is, the voltage detection bus bar 20 includes a voltage detection unit 22a and a reference potential unit 22b at both ends corresponding to one conductor portion 20a, a voltage detection unit 22c at both ends corresponding to the other conductor portion 20b, and a reference potential portion 22b. have. This embodiment is an embodiment in which the reference potential portion has the same potential as in the first embodiment.

The current detector including the bus bar for voltage detection and the calculation unit presented in all the above-described embodiments is presented. Compared with the current detector using the Hall element, all the above-described embodiments do not require a magnetic core or an amplifier circuit, and the current detector can be expected to be downsized.
Further, since all the above-described embodiments are bus bars made of one material, it can be said that the cost and man-hours are lower than those of the shunt resistor.

(Application example)
Finally, an example in which the current detector of the present invention is applied to a power conversion device is shown. FIG. 6 is a diagram illustrating a basic configuration of a power conversion device 100 to which the current detector according to each of the above-described embodiments is applied to the output stage of the inverter circuit unit 100a.

Referring to FIG. 6, the power conversion device 100 generally has a function of converting the DC power supplied by the DC power supply 101 into AC power by the inverter circuit unit 100a and supplying it to the load 102. In the case of the power conversion device 100, specifically, the DC current supplied by the DC power supply 101 is converted into a three-phase AC current by the inverter circuit unit 100a and supplied to the load 102. The power conversion device 100 is configured by interposing and connecting a current detector 100b between the output side of the inverter circuit unit 100a and the load 102 connected to the output side. In the current detector 100b here, three AC bus bars 11 for voltage detection are used, and a calculation unit 110 is connected to these.

The inverter circuit unit 100a includes a DC capacitor C and power semiconductor devices M1, M2, and M3 provided on the main circuit wiring board, and the input side is connected to the DC power supply 101 via the input terminals P and N. The power semiconductor devices M1, M2, and M3 have input terminals P1, P2, and P3 connected to the input terminal P, respectively, and input terminals N1, N2, and N3 connected to the input terminal N, respectively. Further, the power semiconductor devices M1, M2, and M3 have output terminals O1, O2, and O3 connected to the u-phase, v-phase, and w-phase output terminals u, v, and w of the inverter circuit unit 100a, respectively. ..

Next, voltage detection in the voltage detection bus bar 11 will be described with reference to FIGS. 7 to 8. 7 to 8 show one phase of the current flowing through the power conversion device 100 and the load 102. FIG. 7 is a waveform obtained by detecting the current output to the load 102 by the power conversion device 100 and the current by the voltage detection bus bar 11 of the present invention and calculating by the calculation unit 110. FIG. 7A is an output current of the inverter circuit unit 100a of FIG. Further, FIG. 7 (b) is based on the difference voltage (VB-VA) of the voltage generated in the bus bars A and B of the voltage detection bus bar 11 when the current of FIG. 7 (a) flows through the voltage detection bus bar 11. It is a current waveform calculated by the calculation unit 110 of the current detector.

FIG. 8 is a waveform when the current of FIG. 7A flows through the bus bars A and B of the two conductor portions 11a and 11b included in the voltage detection bus bar 11. FIG. 8A is a waveform of the first voltage VA [V] detected by the bus bar A, and FIG. 8B is a waveform of the second voltage VB [V] detected by the bus bar B. .. Further, FIG. 8 (c) is a waveform of a differential voltage (VB-VA) [V] obtained by subtracting the first voltage VA of FIG. 8 (a) from the second voltage VB of FIG. 8 (b).

The output current of the inverter circuit unit 100a shown in FIG. 7A includes a current of a high frequency component generated by the switching operation of the inverter in addition to the current of the sinusoidal component controlled by the inverter circuit unit 100a. The high frequency component generated by the switching operation is a current having a large time change with respect to the current of the sinusoidal component controlled by the inverter circuit unit 100a. When such a current flows through the voltage detection bus bar 11, the peak value is high at high frequencies due to the inductance component parasitic on the bus bars A and B from the relational expressions (C) and (D) in the two conductor portions 11a and 11b. Voltage is generated. Therefore, as shown in FIGS. 8A and 8B, the waveform is such that the high frequency component is superimposed on the sine wave component.

On the other hand, referring to FIG. 8C, it can be seen that the differential voltage (VB-VA) of the bus bars A and B has a sinusoidal waveform. This is because the inductance values L of the bus bars A and B are the same, so that the inductance component voltages of the bus bars A and B are canceled out from the relational expression (E).

Further, referring to FIG. 7 (b), the detection current IC calculated based on the relational expression (F) calculated by the calculation unit 110 matches the actual output current IOUT of FIG. 7 (a). I understand. From the above, it can be said that the output current of the inverter can be detected with high accuracy by applying the present invention. Although FIGS. 7 (a) to 7 (b) and FIGS. 8 (a) to 8 (c) have described one phase of the three-phase alternating current, other phases can be measured in the same manner.

The above has presented an example in which the current detector of the present invention is applied between the output unit of the inverter that outputs an alternating current and the load, that is, a place where the alternating current flows, using FIGS. 6 to 8. The current detector of the present invention can be applied between a power source and an input portion of a converter to which an AC current is supplied from an AC power source, that is, a place where an AC current flows.

11, 14, 20 Voltage detection bus bar 11a, 11b, 14a, 14b, 20a, 20b Conductor part 12, 15, 21 Hole part 13a, 13c, 16a, 16b, 16c, 16d, 22a, 22c Voltage detection part 13b, 22b Reference potential unit 17, 18, 23, 23a, 23b Notch 100 Power converter 100a Inverter circuit unit 100b Current detector 101 DC power supply 102 Load 110 Calculation unit

Claims (6)

It is a voltage detection bus bar that is connected so as to be conductive at the place where the alternating current of the power converter passes.
The voltage detection bus bar includes two conductor sections including a first and second reference potential section, a first voltage detection section, and a second voltage detection section.
The two conductor portions have a first resistance value between the first voltage detection unit and the first reference potential portion and a second resistance value between the second voltage detection unit and the second reference potential portion. Is the ratio of the first inductance value between the first voltage detection unit and the first reference potential unit and the second inductance value between the second voltage detection unit and the second reference potential unit. A bus bar for voltage detection characterized by being different. The two conductor portions are each formed of one or more kinds of metal materials, and have a shape obtained by changing at least two or more elements of the length, width, and thickness that define the shape. The voltage detection bus bar according to claim 1. The voltage detection bus bar according to claim 2, wherein the voltage detection bus bar has a shape obtained by providing one or more types of notches in a substrate of the metal material. The first and second reference potential portions are
The voltage detection bus bar according to any one of claims 1 to 3, wherein the bus bar has the same potential. The voltage detection bus bar according to any one of claims 1 to 4.
The difference voltage between the first voltage detection unit and the first reference potential unit and the second voltage between the second voltage detection unit and the second reference potential unit is defined as the difference voltage. An arithmetic unit that detects current by dividing by the first resistance value and the difference resistance value of the second resistance value, and
A current detector characterized by including. A power conversion device comprising the current detector according to claim 5 at a location where an alternating current flows.

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