busbar structure and power conversion device which uses it

Abstract

A power conversion device designed to reduce noise superimposed on a DC voltage in the AM broadcast frequency band and the HF frequency band, comprising the following: a first capacitor unit (Cxp) that is connected between a positive terminal (HP) and a negative terminal (PH) of a current source (HVBT) and is designed to smooth out a voltage change superimposed on the DC voltage, a switching circuit (SWC) designed to convert direct current (DC) voltage into alternating current (AC) voltage, a first busbar (BSB1) that electrically connects the positive terminal of the power source to a first terminal (TCx1) of the first capacitor unit, a second busbar (BSB2) that electrically connects the negative terminal of the power source to a second terminal (TCx2) of the first capacitor unit, and a second capacitor unit (Cx) that electrically connects the first busbar and the second busbar, wherein the first busbar and the second busbar each have a U-shaped curved section between a first terminal (TC11, TC21) of the second capacitor unit and the first terminal of the first capacitor unit, or between a second terminal (TC12, TC22) of the second capacitor unit and the second terminal of the first capacitor unit, wherein the U-shaped curved sections of the first busbar and the second busbar are arranged and separated in opposite directions so that they face each other, and in turn have opposing sections in which the main surfaces of the first busbar and the second busbar face each other, and wherein the U-shaped curved sections of the first busbar and the second busbar are arranged so that a current can flow through the opposing sections in the same direction.

Description

Technical field

[0001] The present invention relates to a busbar structure and a power conversion device which uses the busbar structure, in the manner of a power conversion device mounted on an electric vehicle and a busbar structure used for the power conversion device. Technical background

[0002] A power conversion device mounted on an electric vehicle is connected to a high-voltage battery by a cable and converts the direct current (DC) supplied by the battery into alternating current (AC) to power an electric motor and cause it to rotate. To convert the DC voltage to AC, the power conversion device has several switching elements, which it switches periodically, for example. The power conversion device has a busbar to supply the DC voltage to the switching elements. The busbar electrically connects an input terminal of the power source, to which the cable is connected, to the switching elements.

[0003] An example of a power conversion device is described in PTL 1. List of citations from patent literature

[0004] PTL 1: JP 2007-53839 A

[0005] A power conversion device with busbars having U-shaped sections formed by slots and capacitor terminals formed in the bottom sections of the U-shaped sections is disclosed in WO 2016 / 084 136 A1. A three-point converter with a structure in which the current flows in the busbars in parallel and opposite directions section by section is disclosed in DE 10 2014 111 421 A1. Finally, DE 11 2017 004 401 T5 discloses a power conversion device similar to the invention, but which is not designed for noise suppression. Summary of the invention: Technical problem

[0006] When the switching elements of the power conversion device are activated, the voltage / current in the busbar fluctuates and generates electromagnetic noise. This generated electromagnetic noise leaks from the housing of the power conversion device. In other words, high-voltage line noise is produced.

[0007] Fig. Figure 10 is a characteristic curve diagram showing the noise frequency characteristic measured by the inventors of the present invention. In the drawing, the horizontal axis represents the frequency and the vertical axis represents peak voltage values ​​of the noise at that frequency. As indicated in the drawing, the noise occurs broadly across the frequency band. For the frequency band from Fig. For example, an AM broadcast frequency band extends from 0.52 to 1.73 MHz and a shortwave (HF) frequency band extends from 7.1 to 26.1 MHz.

[0008] There are plans to establish a specific international standard for high-voltage line noise, so automotive manufacturers tend to set their own standards that comply with international norms. In particular, these standards regulate noise in the AM broadcast frequency band and the HF frequency band, which are used in many applications, so that it is lower than in the other frequency bands.

[0009] To investigate the generated noise, the inventors of the present invention have separated and examined the voltage and current transmitted through the wiring harness (including cables and a busbar) connecting the high-voltage battery and the power conversion device into two types. Fig. Figure 11 is a diagram explaining the investigation carried out by the inventors. Fig. 11(A) and Fig. 11(B) are block diagrams to explain the relationship between the high-voltage battery and the power conversion device. Fig. Figure 11(C) shows the change in the current flowing through the wiring harness.

[0010] In Fig. 11(A) represents HVBT, a high-voltage battery; HP represents a positive terminal of the HVBT; and HN represents a negative terminal. Additionally, PWCS represents a power conversion device; PP represents a positive current input terminal (hereinafter also referred to as the input terminal or first current input terminal) of the PWCS; and PN represents a negative current input terminal (hereinafter also referred to as the input terminal or second current source input terminal). The housing of the HVBT and the PWCS is connected to ground via a ground wire, GND, as the frame ground, G. The positive terminal, HP, of the HVBT and the input terminal, PP, of the PWCS are electrically connected by a voltage cable harness, VLP.The negative terminal HN of the high-voltage battery HVBT and the input terminal PN of the power conversion device PWCS are electrically connected by a voltage cable harness VLN.

[0011] When the power conversion device PWCS initiates the conversion process, a current is supplied from the positive terminal HP of the high-voltage battery HVBT to the voltage wiring harness VLP. The current flowing through the positive terminal HP is considered to consist of a normal-mode current NMI and a common-mode current CMI. Similarly, the current flowing through the negative terminal HN of the high-voltage battery HVBT is considered to consist of the normal-mode current NMI and the common-mode current CMI. As shown, the common-mode current CMI, which is supplied to the voltage wiring harnesses VLP and VLN from the positive terminal HP and the negative terminal HN, respectively, flows through the power conversion device PWCS via the input terminals PP and PN, is fed from the frame ground G to the ground wire GND, and is returned via the ground wire GND to the frame ground G of the high-voltage battery HVBT.On the other hand, the normal mode current NMI is fed from the positive terminal HP through the voltage cable harness VLP to the input terminal PP and, after passing through the power conversion device PWCS, is returned from the input terminal PM to the voltage cable harness VLN and to the positive terminal HN.

[0012] Fig. Figure 11(B) shows a normal-mode voltage NMV corresponding to the normal-mode current NMI and a common-mode voltage CMV corresponding to the common-mode current CMI. Because the normal-mode current NMI flows back and forth between the voltage harnesses VLP and VLN and returns to the high-voltage battery HVBT, the normal-mode voltage NMV corresponds to the potential difference between the voltage harnesses VLP and VLN. On the other hand, the common-mode voltage CMV corresponds to a potential difference based on the voltage (ground voltage) of the ground line GND, because the common-mode current CMI returns from the voltage harnesses VLP and VLN through the ground line GND to the high-voltage battery HVBT.

[0013] As in Fig. As shown in Figure 11(C), a change in the common-mode voltage CMV appears as a change in the potential difference with respect to the ground voltage (ground line GND), and a change in the normal-mode voltage NMV appears as a change in the potential difference between the voltage cable harnesses VLP and VLN.

[0014] When noise is generated, the noise-generating harmonic components are superimposed on the normal-mode current (NMI) or common-mode current (CMI), and they change according to the noise. Similarly, the normal-mode voltage (NMV) and the common-mode voltage (CMV) are superimposed with harmonic components and change.

[0015] The inventors measured the noise generated in the PWCS power conversion device by dividing it into a common-mode mode and a normal-mode mode. Fig. Figure 12 is a characteristic curve diagram showing noise frequency characteristics measured by the inventors. In the diagram, the horizontal axis represents the frequency, and the vertical axis represents the peak current value of the noise at the frequency. In the diagram, the dashed line CMIn is a characteristic curve representing the common-mode current noise, and the solid line NMIn is a characteristic curve representing the normal-mode current noise. In other words, the CMIn characteristic curve represents a noise component (common-mode noise current) in the common-mode current CMI, superimposed on the harmonic component of the noise. The NMIn characteristic curve represents a noise component (normal-mode noise current) in the normal-mode current NMI, superimposed on the harmonic component of the noise. It should be noted that Fig. 12 of the in Fig. The noise frequency characteristic shown in Figure 10 corresponds to the noise frequency characteristic when it is divided into a normal-mode noise current and a common-mode noise current.

[0016] How based Fig. As is understandable, the normal-mode noise current in the AM broadcast frequency band and the shortwave frequency band is greater than the common-mode noise current. Therefore, the inventors concluded that it is important to reduce the normal-mode noise current.

[0017] PTL 1 shows a power conversion device that incorporates a miniaturizable snubber circuit. However, PTL 1 does not disclose the reduction of noise in the AM broadcast frequency band and the HF frequency band.

[0018] One object of the present invention is to provide a busbar structure which can reduce noise in an AM broadcast frequency band and a shortwave frequency band, and a power conversion device comprising the busbar structure.

[0019] The foregoing and other tasks and novel features of the present invention will become understandable with reference to the description in this patent specification and the accompanying drawing. Solution to the problem

[0020] The power conversion device according to the present invention is defined in claim 1. Further advantageous embodiments are described in the dependent claims. Advantageous effects of the invention

[0021] An effect obtained through the representative embodiment of the invention disclosed in the present application is briefly mentioned below.

[0022] A power conversion device is provided that is capable of reducing noise in the AM broadcast frequency band and the HF frequency band. Brief description of the drawings

[0023] They show: Fig. 1 a block diagram of a configuration of a power conversion device according to a first embodiment, Fig. 2 a schematic top view of the structure of a power conversion device according to the first embodiment, the Fig. 3(A) to 3(C) the construction of a busbar according to the third embodiment, Fig. 4 the relationship between the structure of the busbar and its inductance according to the first embodiment, Fig. 5 a characteristic curve diagram showing the attenuation of an LCL filter according to the first embodiment, Fig. 6 a perspective view of the structure of a busbar according to a second embodiment, the Fig. 7(A) to 7(C) the construction of the busbar according to the second embodiment, the Fig. 8(A) to 8(C) the construction of a busbar according to a third embodiment, the Fig. 9(A) and Fig. 9(B) Perspective views of the construction of a busbar according to a fourth embodiment, Fig. 10 a characteristic curve diagram from the inventors of measured noise frequency characteristics, the Fig. 11(A) to 11(C) Diagrams explaining the investigation carried out by the inventors, Fig. 12 a characteristic curve diagram from the inventors of measured noise frequency characteristics, Fig. 13 a circuit diagram of an equivalent circuit of a noise filter developed by the inventors and Fig. 14 a characteristic curve diagram of the attenuation of an LCL filter. Description of embodiments

[0024] Embodiments of the present invention are described below with reference to the accompanying drawing. In principle, the same reference numerals are attached to the same sections in all drawings that explain the embodiments, and their descriptions are not repeated. Although no specific limitation exists, a power conversion device mounted in an electric vehicle is described below by way of example. (First embodiment) <rauschfilter>

[0025] The inventors considered connecting a noise filter to a busbar to reduce noise in the AM broadcast and shortwave frequency bands by lowering the normal-mode noise current. In other words, they considered connecting a capacitor assembly to a busbar electrically connected between a positive input terminal of a power conversion device and a switching element, and to a busbar electrically connecting a negative input terminal and a switching element. In this case, the capacitor assembly would consist, for example, of a capacitor element connected between the busbars and a capacitor element connected between each busbar and a frame ground. The busbars have a parasitic inductor because they are made of copper plates, for example. Therefore, the noise filter is formed by the capacitor assembly and the busbar inductor.

[0026] Fig. Figure 13 is a circuit diagram of an equivalent circuit of the noise filter considered by the inventors. This drawing also shows a high-voltage battery (HVBT) and a switching element as equivalent circuits. A current source V2 represents an equivalent circuit of the high-voltage battery (HVBT), Gn represents the equivalent circuit of the switching element (circuit), and V1 represents the current source generated by conversion through a power conversion circuit (PWCS). The current source V2 generates a DC high voltage, and the current source V1 generates an AC voltage generated by switching the switching element Gn. Furthermore, resistors R4 and R5 denote impedance matching resistors. In the drawing, the switching element Gn is depicted as the noise-generating source.

[0027] In Fig. 13 connects a first busbar BSB1 between an input terminal PP and the switching element Gn of the power conversion device PWCS and connects a second busbar BSB2 between an input terminal PN and the switching element Gn of the power conversion device PWCS. A smoothing capacitor element (a smoothing capacitor unit) Cxp is connected between the first busbar BSB1 and the second busbar BSB2 and smooths a voltage change superimposed by noise in the DC voltage V2. A capacitor unit Cyp comprises a capacitor element Cyp1 (not shown) connected between the first busbar BSB1 and the frame ground G, and a capacitor element Cyp2 (not shown) connected between the second busbar BSB2 and the frame ground G.In the case of common-mode noise current, the capacitor elements Cyp1 and Cyp2 are equivalently connected in series between the first busbar BSB1 and the second busbar BSB2. Therefore, the capacitor elements Cyp1 and Cyp2 are represented as the capacitor unit Cyp connected between the first busbar BSB1 and the second busbar BSB2 in the equivalent circuit diagram.

[0028] In Fig. 13. The noise filter-forming capacitor unit (filter capacitor unit) Cx is connected to predetermined positions on the first bus BSB1 and the second bus BSB2, respectively. In other words, the capacitor unit Cx is connected to the position between the input terminals PP and PN and the switching element Gn on the first bus BSB1 and the second bus BSB2. The first bus BSB1 consists equivalently of two inductors (a first and a second inductor unit) Lp1 and Lp2 around the position to which the capacitor unit Cx is connected. Similarly, the second bus BSB2 consists equivalently of two inductors (a third and a fourth inductor unit) Ln1 and Ln2 around the position to which the capacitor unit Cx is connected. The directions in which magnetic fields are generated are indicated by the stars attached to the inductors Lp1, Lp2, Ln1, and Ln2.A mutual coupling coefficient K1 (hereinafter also referred to simply as the coupling coefficient) is a coupling coefficient between the inductors Lp1 and Ln1, and a mutual coupling coefficient K2 is a coupling coefficient between the inductors Lp2 and Ln2.

[0029] The capacitor unit Cx comprises capacitor elements C1 to C3 and resistors R1 to R3. Here, capacitor element C1 and resistor R1 are connected in series between the first busbar BSB1 and the second busbar BSB2. Similarly, capacitor element C2 and resistor R2 are also connected in series between the first busbar BSB1 and the second busbar BSB2.

[0030] Capacitor element C3 comprises two capacitor elements, C31 (not shown) and C32 (not shown), and resistor R3 also comprises two resistors, R31 (not shown) and R32 (not shown). Capacitor element C31 and resistor R31 are connected in series between the first busbar BSB1 and the frame ground G, and capacitor element C32 and resistor R32 are also connected in series between the second busbar BSB2 and the frame ground G. Similar to the capacitor unit Cyp described above, in the case of common-mode noise current, capacitor element C31, resistor R31, capacitor element C32, and resistor R32 are equivalently connected in series between the first busbar BSB1 and the second busbar BSB2.Similar to capacitor unit Cyp, these capacitor elements C31 and C32 and resistors R31 and R32 are therefore represented as capacitor element C3 and resistor R3, which are connected in series between the first busbar BSB1 and the second busbar BSB2. Resistors R1 to R3 contained in capacitor unit Cx act as a dump resistor to suppress the noise peak.

[0031] In Fig. Figure 13 describes a noise filter in which the capacitor unit Cx is sandwiched between the first inductor unit La, consisting of inductors Lp1 and Ln1, and the second inductor unit Lb, consisting of inductors Lp2 and Ln2. Hereinafter, the filter in which the capacitor unit Cx is sandwiched between the two inductor units La and Lb is also referred to as the LCL filter. Furthermore, it can be assumed that the capacitor unit (for convenience, denoted as capacitor unit Cxx) consists of the capacitor unit Cyp and the smoothing capacitor element Cxp. In this case, the first filter circuit is considered to be formed by the first inductor unit La and the capacitor unit Cx, and the second filter circuit is considered to be formed by the second inductor unit Lb and the capacitor unit Cxx.In this case, the first and second filter circuits are connected in series between the input terminals PP and PN and the switching element Gn, in that order. Such a filter is subsequently referred to as an LCLC filter. This type of filter can reduce the normal-mode noise current in the AM broadcast frequency band and the shortwave frequency band.

[0032] However, the capacitance of the capacitor element forming capacitor unit Cx must be reduced to lower the normal-mode noise current. Therefore, capacitor elements C1 to C3 are either enlarged or each capacitor element is composed of more capacitor elements. This prevents the miniaturization of the power-to-water conversion device (PWCS) and also increases the manufacturing costs of the PWCS.

[0033] In recent years, however, there has been a high demand for miniaturization and cost reduction of the power conversion devices mounted on electric vehicles. Therefore, in order to meet this demand, inventors have further optimized the configuration of the... Fig. The power conversion device shown in section 13 was examined.

[0034] The inventors' investigation revealed that the reduction of the normal-mode noise current when using the LCL(LCLC) filter can be achieved by placing the inductor unit Lb between the capacitor unit Cx and the switching element Gn (or the capacitor unit Cyp and / or the smoothing capacitor unit Cxp). In other words, it was found that the effectiveness of the LCL(LCLC) filter in reducing the normal-mode noise current can be increased by increasing the inductance of the inductor unit Lb.

[0035] Fig. 14 is a characteristic curve diagram showing the attenuation of the in Fig. Figure 13 shows the LCL(LCLC) filter. The horizontal axis represents the frequency F, and the vertical axis represents the ratio between the values ​​shown in Figure 13. Fig. The voltages V1 and V2 shown in Figure 13 are in decibels (dBV). A characteristic curve GLb0, indicated by a dashed line, represents the change in attenuation with a change in frequency F when the inductance of inductors Lp2 and Ln2 is 0 nH. A characteristic curve GLb1, indicated by a solid line, represents the change in attenuation when the inductance of inductors Lp2 and Ln2 is greater than 0 nH. A characteristic curve GLb2, indicated by a double-dotted line, represents the change in attenuation when inductors Lp2 and Ln2 are used whose inductance is three times greater than that used in measuring characteristic curve GLb1. The inductance of the inductor unit La and the capacitance of the capacitor unit Cx are the same as in determining characteristic curves GLb0 to GLb2.

[0036] As in Fig. As shown in Figure 14, the attenuation is increased by increasing the inductance of the inductor unit Lb forming the LCL(LCLC) filter. In other words, the attenuation is effectively increased by increasing the value of the inductor unit Lb, which is arranged between the capacitor unit Cx and the capacitor element Cyp and / or the smoothing capacitor unit Cxp in the inductors forming the LCL(LCLC) filter. The resonant frequency fp can be obtained from equation (1). In equation (1), CCx denotes the capacitance of the capacitor unit Cx and HLb denotes the inductance of the inductor unit Lb. fp=1 / 2πCCx×HLb

[0037] To achieve a large attenuation in the AM broadcast frequency band and the SW frequency band, the values ​​of the capacitor unit CX and the inductor unit Lb are set such that the resonant frequency fp is less than the lowest frequency of 0.52 MHz in the AM broadcast frequency band.

[0038] The inductance HLb of the inductor unit Lb can be obtained by equation (2). HLp2 represents the inductance of inductor Lp2, HLn2 represents the inductance of inductor Ln2, and k2 represents the coupling coefficient of inductors Lp2 and Ln2. ??? HLb=HLp2+HLn2±2×k2HLp2×HLn2

[0039] As can be seen from equation (2), the inductance HLb of the inductor unit Lb is obtained by adding or subtracting the mutual inductance, which is obtained by multiplying the product of the inductances HLp2 and HLn2 by the coupling coefficient, from the sum of the inductances HLp2 and HLn2 of the two inductors Lp2 and Ln2. Whether an addition or subtraction is performed depends on whether the magnetic fields generated by the inductors Lp2 and Ln2 are oriented in the same or opposite directions.

[0040] According to the first embodiment, each of the inductors Lp2 and Ln2 is considered to consist of several sub-inductors, as will be described in detail later. The first busbar BSB1 and the second busbar BSB2 are arranged such that magnetic fields in the same direction are generated in some of the several sub-inductors. This increases the inductance HLb in the inductor unit Lb. <leistungswandlungsvorrichtung>

[0041] Fig. Figure 1 is a block diagram of a configuration of a power conversion device according to the first embodiment. Fig. Figure 1 shows a housing 1 of the power conversion device PWCS. Various circuit blocks and elements are housed in the housing 1 of the power conversion device PWCS. Fig. Figure 1 shows only those circuit blocks and elements necessary for the explanation that are included in the housing 1. The drawing also shows a high-voltage battery HVBT for supplying a DC voltage to the power conversion device PWCS and an electric motor 4, which is driven by an AC voltage generated by the power conversion device PWCS.

[0042] The high-voltage battery HVBT has a battery BT whose positive electrode is connected to a positive terminal HP of the high-voltage battery HVBT and whose negative electrode is connected to a negative terminal HN of the high-voltage battery HVBT.

[0043] Although there is no specific restriction, the housing of the high-voltage battery HVBT is defined as the frame ground G and connected to the ground wire GND. The positive terminal HP and the negative terminal HN of the high-voltage battery HVBT are electrically connected via cable 2 to the input terminal (positive power source input terminal) PP and the input terminal (negative power source input terminal) PN of the power conversion device PWCS.

[0044] The electric motor 4 consists of, but is not limited to, a three-phase electric motor. The electric motor 4 comprises a rotor (not shown) and a stator (not shown), and three coils 5-U, 5-V, ​​and 5-W are arranged on the stator. The power conversion device PWCS generates a three-phase alternating voltage and supplies it to the three coils 5-U, 5-V, ​​and 5-W via cable 3. This causes the coils 5-U, 5-V, ​​and 5-W to generate a magnetic field corresponding to the three-phase alternating voltage, thereby rotating the rotor. Although there is no specific restriction, the housing of the electric motor 4 also acts as the frame ground G and is connected to the ground wire GND.

[0045] Next, the configuration of the power conversion device PWCS is described. The power conversion device PWCS comprises a switching circuit SWC, the first busbar BSB1 and the second busbar BSB2, which electrically connect the switching circuit SWC to the respective input terminals PP and PN, capacitor elements C1, C2, C31, C32, Cxp, Cyp1 and Cyp2, and resistors R1, R2, R31 and R32.

[0046] The switching circuit SWC comprises three unit circuits USW1 to USW3 with identical configurations. Unit circuit USW1 is described as an example. Unit circuit USW1 includes insulated-gate bipolar transistors (hereinafter referred to simply as transistors) TR1 and TR2 and diodes D1 and D2. Diodes D1 and D2 are connected between the collectors and emitters of transistors TR1 and TR2, respectively. The emitter of transistor TR1 is connected to the collector of transistor TR2. A connection node between the emitter and the collector serves as the output node and is connected to the coil of electric motor 4 via cable 3. The collector of transistor TR1 is electrically connected to input terminal PP via the first bus bar BSB1, and the emitter of transistor TR2 is electrically connected to input terminal PN via the second bus bar BSB2.

[0047] A switching control signal from a switching control circuit (not shown) is applied to the gates of transistors TR1 and TR2, and switching control is performed so that transistors TR1 and TR2 are switched on / off in a complementary manner according to the switching control signal. When transistors TR1 and TR2 are switched on / off in a complementary manner, the positive and negative voltages are periodically output at the output node. In other words, an alternating voltage is output from the output node. The same applies to the other unit circuits USW2 and USW3, and therefore their description is omitted. Because the transistors are switched on / off periodically as described above, the voltage / current in the first bus BSB1 and the second bus BSB2 changes, and noise is generated.

[0048] The first busbar BSB1 and the second busbar BSB2 are made of copper plates, although there is no specific restriction on this, and both ends of the first and second busbars BSB1 and BSB2 form a terminal pair. One terminal of the first busbar BSB1 is connected to the input terminal PP of the power conversion device PWCS, and the other terminal PPO is connected to the first terminal TCx1 of the smoothing capacitor element (the first capacitor unit) Cxp, which acts as a smoothing capacitor, the first terminal TCy11 of the capacitor element Cyp1, and the first terminal TCy21 of the capacitor element Cyp2. The other terminal PPO is also connected to the collector of transistor TR1 in the unit circuits USW1 to USW3.

[0049] Similar to the first busbar BSB1, one terminal of the second busbar BSB2 is connected to the input terminal PN of the power conversion device PWCS, and the other terminal PNO is connected to the second terminal TCx2 of the smoothing capacitor element Cxp, the second terminal TCy12 of the capacitor element Cyp1, and the second terminal TCy22 of the capacitor element Cyp2. The other terminal PPO is also connected to the emitter of transistor TR2 in the unit circuits USW1 to USW3.

[0050] In Fig. For the sake of clarity, the other terminals PPO and PNO of the first bus BSB1 and the second bus BSB2 are shown separately from the capacitor elements Cxp, Cyp1, and Cyp2, and the collector and emitter of the transistor, but without restriction. For example, the first bus BSB1 and the second bus BSB2 extend to the collector of transistor TR1 and the emitter of transistor TR2, and the other terminal PPO is located at the collector of transistor TR1, and the other terminal PPN is located at the emitter of transistor TR2. In this case, the terminals of the capacitor elements Cxp, Cyp1, and Cyp2 are connected to the extended section.Because the input terminals PP and PN of the power conversion device PWCS are connected to one of the terminals of the first busbar BSB1 and the second busbar BSB2, the input terminals PP and PN are considered to represent the respective terminal of the first busbar BSB1 and the second busbar.

[0051] The second terminals TCy12 and TCy22 of the capacitor elements Cyp1 and Cyp2 are connected to the housing 1 and the ground wire GND. The in Fig. The smoothing capacitor element Cxp shown corresponds to the one in connection with Fig. 13 smoothing capacitor element Cxp described. The capacitor elements Cyp1 and Cyp2 correspond to those in Fig. 13 shown capacitor unit Cyp, and for the common-mode noise current the capacitor elements Cyp1 and Cyp2 are equivalently connected in series between the first busbar BSB1 and the second busbar BSB2.

[0052] On the first busbar BSB1, the first terminals TC11, TC21, and TC311 of the filter capacitor elements C1, C2, and C31 are electrically connected to a section (first section) PT1 between terminal pair PP and PPO. On the second busbar BSB2, the terminals TRC1 and TRC2 of resistors R1 and R2, which are connected to the second terminals TC12 and TC22 of the filter capacitor elements C1 and C2, are connected to a section (second section) PT2 between terminal pair PN and PNO. In other words, the second terminals TC12 and TC22 of the filter capacitor elements C1 and C2 are electrically connected to the second busbar BSB2 via resistors R1 and R2 at section PT2. Similarly, the first terminal TC321 of the filter capacitor element C32 is electrically connected to a section PT2 of the second busbar BSB2.

[0053] The second terminals TC312 and TC322 of the filter capacitor elements C31 and C32 are connected to the housing 1 via the respective resistors R31 and R32 and to the ground line GND. Fig. 1. The filter capacitor elements C1 and C2 correspond to those in Fig. 13 capacitor elements C1 and C2 described, and do the resistors R1 and R2 also correspond to those described in Fig. 13 described resistors R1 and R2. Furthermore, the filter capacitor elements C31 and C32 correspond to those in Fig. The capacitor element C3 described in 13 corresponds to the resistors R31 and R32 in the diagram. Fig. The resistor R3 described in section 13. In other words, for the common-mode noise current, the second terminals TC312 and TC322 of the filter capacitor elements C31 and C32 are equivalently connected via resistors R31 and R32. Accordingly, the filter capacitor elements C31 and C32 and the resistors R31 and R32 are equivalently connected in series between the first busbar BSB1 and the second busbar BSB2.

[0054] Therefore, it can be assumed that the first terminal of the capacitor unit Cx is connected to the first section PT1 of the first busbar BSB1 and the second terminal of the capacitor unit Cx is connected to the second section PT2 of the second busbar BSB2.

[0055] Fig. Figure 1 shows a parasitic inductor Lp1 of the first busbar BSB1 between one terminal PP and section PT1, to which the filter capacitor element is connected. Also shown is a parasitic inductor Ln1 of the second busbar BSB2 between one terminal PN and section PT2, to which the filter capacitor element is connected. Similarly, a parasitic inductor Lp2 of the first busbar BSB1 between the other terminal PPO and section PT1, to which the filter capacitor element is connected, is shown. Also shown is a parasitic inductor Ln2 of the second busbar BSB2 between the other terminal PNO and section PT2, to which the filter capacitor element is connected.

[0056] The parasitic inducers Lp1 and Lp2 and Ln1 and Ln2 correspond to those in Fig. 13 inductors described. Therefore, the capacitor unit (the second capacitor element) Cx consists of sections PT1 and PT2, and the inductor units La and Lb are arranged so that they sandwich the capacitor unit Cx. <Aufbau der Leistungswandlungsvorrichtung>

[0057] Fig. Figure 2 is a top view schematically illustrating the construction of the power conversion device according to the first embodiment. Of the circuit blocks and parts enclosed in the housing 1 of the power conversion device PWCS, the drawing shows only the first busbar BSB1, the second busbar BSB2, the filter capacitor elements C1 and C2, the capacitor elements Cyp1 and Cyp2, the smoothing capacitor element Cxp, and the switching circuit SWC; the other parts are omitted. The shape of the first busbar BSB1 and the second busbar BSB2, and the arrangement and shape of the filter capacitor elements C1 and C2, the capacitor elements Cyp1 and Cyp2, and the smoothing capacitor element Cxp are shown according to their actual dimensions and shapes, albeit schematically.

[0058] When viewed from above, the power conversion device PWCS consists of the first busbar BSB1 and the second busbar BSB2, each comprising a flat copper plate of a predetermined width. According to the first embodiment, the main surface of the first busbar BSB1 extends between the input terminal PP and the smoothing capacitor element Cxp and has a U-shaped curved section in its center. Similarly, the main surface of the second busbar BSB2 extends between the input terminal PN and the smoothing capacitor element Cxp and also has a U-shaped curved section in its center. Viewed from above, the U-shaped curved section of the first busbar BSB1 and the U-shaped curved section of the second busbar BSB2 partially overlap, and an insulating material is positioned between them in the overlapping section.The insulating material corresponds, for example, to a gap between the first busbar BSB1 and the second busbar BSB2.

[0059] At sections PT1 and PT2 ( Fig. 1) Between the curved sections of the first busbar BSB1 and the second busbar BSB2 and the respective input terminals PP and PN, the first busbar BSB1 and the second busbar BSB2 are connected to the capacitor unit Cx forming the noise filter ( Fig. 1). Fig. Figure 2 shows only the filter capacitor elements C1 and C2, which form the capacitor unit Cx as a capacitor block, and the terminals TC11 and TC21 of the filter capacitor elements C1 and C2 are indicated by circles and connected to the first busbar BSB1.

[0060] The other terminals TC12 and TC22 of the filter capacitor elements C1 and C2 are indicated by circles and by resistors R1 and R2 ( Fig. 1) connected to the second busbar BSB2 (not shown).

[0061] The first busbar BSB1 and the second busbar BSB2 are connected to the filter capacitor elements and resistors by metal screws, for example, and without limitation. For instance, the sections of terminals TC11 and TC21, indicated by circles, are attached to the first busbar BSB1 by screws. This allows the first busbar BSB1 to be electrically connected to terminals TC11 and TC21 of capacitor elements C1 and C2. Terminals TC12 and TC22, indicated by circles, are connected to terminals TRC1 and TRC2 ( Fig. 1) the resistors R1 and R2, which are attached to the second busbar BSB2 by screws, are electrically connected to the second busbar BSB2.

[0062] Although this in Fig. As shown in Figure 2, the terminals TC311 and TC321 of the filter capacitor elements C31 and C32 are also connected to the first busbar BSB1 and the second busbar BSB2 at the same positions on sections PT1 and PT2 as the filter capacitor elements C1 and C2, and are electrically connected by screws. Resistors R31 and R32 (not shown) are electrically connected between the housing 1 and the terminals TC312 and TC322 of the filter capacitor elements C31 and C32.

[0063] One of the terminals TCy11 and TCy21 of the capacitor elements Cyp1 and Cyp2, indicated by circles, is screwed and electrically connected at the positions between the curved sections of the first busbar BSB1 and the second busbar BSB2 and the smoothing capacitor element Cxp. The other terminals TCy12 and TCy22 of the capacitor elements Cyp1 and Cyp2 are connected to the housing 1.

[0064] The smoothing capacitor element Cxp is larger than the other capacitor elements when viewed from above. Although there is no specific restriction, the first busbar BSB1 and the second busbar BSB2 extend such that they overlap one electrode pair of the smoothing capacitor element Cxp. The electrode pair of the smoothing capacitor element Cxp has several terminals TCx1 and TCx2, indicated by circles, which are attached to and electrically connected by screws to the overlapping first busbar BSB1 and the second busbar BSB2. Additionally, the first busbar BSB1 and the second busbar BSB2 are electrically connected to the switching circuit SWC. The input terminals PP and PN are attached by screws to... Fig. 1. Cables 2 shown are attached and electrically connected to them.

[0065] Fig. Figure 3 shows the construction of a busbar according to the first embodiment. Fig. Figure 3(A) shows the structure of the first busbar BSB1 and the second busbar BSB2 in detail in a top view. Fig. 3(B) is a sectional view along a line AA' from Fig. 3(A), and Fig. 3(C) is a sectional view along a line BB' from Fig. 3(A). Between the Fig. 3(A), Fig. 3(B) and Fig. 3(C) shows broken lines indicating reciprocal relationships. Fig. 3(A) For the sake of simplicity, the lengths of the first busbar BSB1 and the second busbar BSB2 are shown shorter than in Figure 3(A). Fig. 2. The first busbar BSB1 and the second busbar BSB2, which are in Fig. 3 are shown, however, they are not the same as those from Fig. 2 are identical. Also, in Fig. 3(A) the capacitor elements Cyp1 and Cyp2 and the switching circuit SWC, which are in Fig. Items shown in 1 have been omitted.

[0066] In Fig. 3(A) BW1 specifies the width of the first busbar BSB1 and BW2 specifies the width of the second busbar BSB2. As in Fig. As shown in Figure 2, the first busbar BSB1 and the second busbar BSB2 have U-shaped curved sections. Fig. 3(A) Busbar BSB1 is bent to the left and then to the right as it extends from the top to the bottom of the drawing, forming a U-shaped curved section BU1. Similarly, busbar BSB2 is bent to the right and then to the left as it extends parallel to busbar BSB1 from the top to the bottom of the drawing when viewed from above, forming a U-shaped curved section BU2. Viewed from above, U-shaped curved sections BU1 and BU2 each comprise side sections corresponding to the sides of the U-shape, a bottom section corresponding to the base of the U-shape and connecting the side sections, and an opening that does not connect the side sections.Viewed in this way, the curved section BU1 formed in the first busbar BSB1 is U-shaped, with the opening on the right side and the base on the left side, while the curved section BU2 formed in the second busbar BSB2 is U-shaped, with the opening on the left side and the base on the right side.

[0067] In other words, the U-shaped curved section BU1 formed in the first busbar BSB1 and the U-shaped curved section BU2 formed in the second busbar BSB2 overlap each other laterally and are oriented in opposite directions when viewed from above. In other words, according to the first embodiment, the curved section BU1 and the curved section BU2 are arranged to overlap each other when viewed from above, except for the opening sections.

[0068] As seen in the A-A' section view from Fig. As shown in Figure 3(B), an insulating layer ISO2, made of an insulating material, is arranged in the overlapping curved sections BU1 and BU2 between the first busbar BSB1 and the second busbar BSB2. The housing 1 is made of a metal material. The insulating layer ISO1 is arranged between the second busbar BSB2 and the housing 1, and an insulating layer ISO2 is arranged between the first busbar BSB1 and the second busbar BSB2. Accordingly, the first busbar BSB1, the second busbar BSB2, and the housing 1 are not directly connected to each other. Fig. 3(B) BD1 and BD2 specify the thickness of the first busbar BSB1 and the second busbar BSB2, respectively.

[0069] Because the U-shaped curved sections BU1 and BU2 are arranged in opposite directions according to the first embodiment, the opening of one curved section (for example, curved section BU1) overlaps the base of the other curved section (BU2), and the sides of both curved sections overlap each other. Accordingly, the side sections of the U-shaped curved sections BU1 and BU2 overlap each other, as shown in Fig. 3(C) is shown. The insulating film ISO2 is arranged between the first busbar BSB1 and the second busbar BSB2 in the curved sections BU1 and BU2, but in Fig. 3(C) omitted. Because the filter capacitor elements C1 and C2 and the smoothing capacitor element Cxp are not directly connected to the housing 1, the insulating layer ISO1 is arranged between the housing 1 and the capacitor elements.

[0070] The insulating material of the insulating layers ISO1 and ISO2 is not particularly restricted. For example, it is only necessary to physically separate the busbars BSB1 and BSB2 from the housing 1.

[0071] According to the first embodiment, when viewed from above, as shown in the Fig. 2 and Fig. As shown in Figure 3, the main surfaces of the first busbar BSB1 and the second busbar BSB2 are adjacent to each other and face each other at the side sections of the curved sections BU1 and BU2, and other sections do not overlap. In contrast, the positive terminal HP is connected to the input terminal PP via cable 2, and the negative terminal HN is connected to the input terminal PN via cable 2. Therefore, the normal-mode current (and the normal-mode noise current) flows in this order from the input terminal PP to the first busbar BSB1, to the switching circuit SWC, to the second busbar BSB2, and to the input terminal PN.

[0072] In other words, the normal-mode current flows from the input terminal PP to the terminal TCx1 of the smoothing capacitor element Cxp in the first busbar BSB1. Conversely, the normal-mode current in the second busbar BSB2 flows from the terminal TCx2 of the smoothing capacitor element Cxp to the input terminal PN. Therefore, the normal-mode current flows in the direction indicated by a solid arrow in the curved section BU1 of the first busbar BSB1, and in the direction indicated by a dashed arrow in the curved section BU2 of the second busbar BSB2. Thus, the normal-mode current flows in the side sections of the U-shaped curved sections BU1 and BU2 in the same direction.

[0073] In contrast, the normal-mode current flows from input terminal PP to the section where, for example, terminals TC11 and TC21 of filter capacitor elements C1 and C2 are connected between input terminal PP and the section where terminals TC11 and TC21 are connected to the first busbar BSB1. At the same time, in the second busbar BSB2, the normal-mode current flows from the section where terminals TC12 and TC22 are connected to input terminal PN. In other words, the normal-mode current between terminals TC11 and TC21 of filter capacitor elements C1 and C2 and input terminal PP flows in the opposite direction to the normal-mode current flowing between terminals TC12 and TC22 of filter capacitor elements C1 and C2 and input terminal PN.

[0074] Fig. Figure 4 shows the relationship between the busbar configuration and the inductance according to the first embodiment. Fig. Figure 4 shows the value of the inductance measured by the inventors. Fig. Figure 4 shows the inductance values ​​obtained when changing the configuration of the first busbar BSB1 between the section to which terminals TC11 and TC21 are connected and the section to which terminal TCx1 is connected, and those obtained when changing the configuration of the second busbar BSB2 between the section to which terminals TC12 and TC22 are connected and the section to which terminal TCx2 is connected. Fig. 2 and Fig. 3 is connected, obtained inductance values. In other words, the inductance values ​​of the in Fig. The inductor unit Lb is shown in Figure 1. Fig. 4 is the first busbar, to indicate that it is a busbar section which corresponds to the inductor unit Lb, designated BSB1(Lb) and the second busbar is designated BSB2(Lb).

[0075] In Fig. 4. The “busbar structure” designated #1 comprises the first busbar BSB1(Lb) and the second busbar BSB2(Lb), which overlap each other so that their main surfaces face each other when viewed from above. In this case, assume that the widths BW1 and BW2 of the first busbar BSB1(Lb) and the second busbar BSB2(Lb) are 30 mm and that the length (the section of the inductor unit Lb) is Fig. 1) 70 mm. The first busbar BSB1(Lb) and the second busbar BSB2(Lb) are separated by 3 mm. Additionally, the first busbar BSB1(Lb) and the second busbar BSB2(Lb) are made of copper and have thicknesses BD1 and BD2 of 1.2 mm. In this case, the coupling coefficient k2 between the parasitic inductors Lp2 and Ln2, which form the inductor unit Lb, is 0.814. Furthermore, the normal-mode current flows in the first busbar BSB1(Lb) in the direction indicated by the solid arrow and in the second busbar BSB2(Lb) in the direction indicated by the dashed arrow.

[0076] In a busbar structure marked #2, the first busbar BSB1(Lb) and the second busbar BSB2(Lb) extend parallel to each other. The first busbar BSB1(Lb) and the second busbar BSB2(Lb) are offset from each other by 3 mm, so that they occupy the same volume as busbar structure #1, and the first busbar BSB1(Lb) and the second busbar BSB2(Lb) are arranged in an area 30 mm wide and 70 mm long. The first busbar BSB1(Lb) and the second busbar BSB2(Lb) have the same material and thickness as busbar structure #1, except that their widths BW1 and BW2 are 10 mm. In this case, the coupling coefficient k2 between the parasitic inductors Lp2 and Ln2 is 0.418.Furthermore, the normal mode current flows in the first busbar BSB1(Lb) in the direction indicated by the arrow with a solid line and in the second busbar BSB2(Lb) in the direction indicated by the arrow with a dashed line.

[0077] In busbar structures #1 and #2, the normal-mode current flowing through the first busbar BSB1(Lb) and the normal-mode current flowing through the second busbar BSB2(Lb) flow in opposite directions. This reverses the direction of the magnetic field generated by inductors Lp2 and Ln2 in an equivalent circuit. Consequently, in equation (2), the value of the mutual inductance becomes negative, and the inductance HLb of inductor unit Lb decreases. Therefore, the inductance HLb of inductor unit Lb in busbar structure #1 is 10.4 nH, and the inductance HLb in busbar structure #2 is 46.8 nH.

[0078] On the other hand, as in the Fig. 2 and Fig. As shown in Figure 3, the first busbar BSB1(Lb) and the second busbar BSB2(Lb) in a busbar structure marked #3 have U-shaped curved sections. In busbar structure #3, the first busbar BSB1(Lb) and the second busbar BSB2(Lb) are also arranged in the area with a width of 30 mm and a length of 70 mm, so that the first busbar BSB1(Lb) and the second busbar BSB2(Lb) are arranged in the same volume as in #1 and #2. The first busbar BSB1(Lb) and the second busbar BSB2(Lb) are separated by 3 mm. The first busbar BSB1(Lb) and the second busbar BSB2(Lb) have widths BW1 and BW2 respectively and thicknesses BD1 and BD2, which are the same as those of busbar structure #2. The same copper material is also used.

[0079] In this case, the normal-mode current flows in the same direction, at least in the side sections of the U-shaped curved sections. However, in the sections of the first busbar BSB1(Lb) and the second busbar BSB2(Lb) that differ from the curved sections, the normal-mode current flows in opposite directions. The equivalent circuit assumes that the parasitic inductor Lp2 of the first busbar BSB1(Lb) has several partial parasitic inductors (hereinafter also referred to as partial inductors) Lp2-1 to Lp2-3. Similarly, it can also be assumed that the parasitic inductor Ln2 of the second busbar BSB2(Lb) has several partial inductors Ln2-1 to Ln2-3.

[0080] In the “equivalent circuit diagram” from Fig. Section 4, where the normal-mode current flows in the same direction, is indicated by a dashed line. The partial inductors Lp2-2 and Ln2-2 in the section enclosed by the dashed line generate magnetic fields in the same direction because the normal-mode current flows in the same direction. Therefore, the mutual inductance in this section has a positive value. Conversely, when the normal-mode current flows in the partial inductors Lp2-1 and Lp2-3, as well as Ln2-1 and Ln2-3, in opposite directions, a magnetic field in the opposite direction is generated, and the mutual inductance assumes a negative value. The sum of the mutual inductance values ​​is the mutual inductance of the total inductors Lp2 and Ln2. Therefore, the inductance HLb of the inductor unit L2 with the busbar structure according to the first embodiment can be increased.This corresponds to the reduction of the overall coupling coefficient, which is obtained as the sum of the coupling coefficient k2-1 between the partial inductors Lp2-1 and Ln2-1, the coupling coefficient k2-2 between the partial inductors Lp2-2 and Ln2-2, and the coupling coefficient k2-3 between the partial inductors Lp2-3 and Ln2-3. This allows the inductance of the inductor unit Lb in the busbar structure #3 according to the first embodiment to be increased to 52.2 nH.

[0081] Furthermore, the first busbar BSB1(Lb) and the second busbar BSB2(Lb) are configured so that they are integrated into the "busbar structures" #1 to #3, which are described in Fig. The components shown in Figure 4 occupy the same volume. In other words, the inductance HLb of the inductor unit L2 can be increased while preventing an increase in size. The values ​​of the coupling coefficient k2 and the inductance HLb, as shown in Figure 4, are shown in Figure 4. Fig. Figure 4 describes the case in which the frequency of the normal mode current is 10 MHz.

[0082] Fig. Figure 5 is a characteristic curve diagram showing the attenuation amount of the LCL(LCLC) filter according to the first embodiment. Similarly Fig. 14 represents the horizontal axis in Fig. 5 represents the frequency F and the vertical axis represents the ratio between the in Fig. 13 shown voltages V1 and V2 in decibels (dBV).

[0083] Fig. Figure 14 shows the characteristic curve if the in Fig. 13 Inductor unit Lb shown in Fig. The “busbar structure” shown in #2 is shown in section 4. Fig. 5 represents the characteristic curve GLb1, the characteristic curve in the case where the inductor unit Lb forms the "busbar structure" #2. Fig. 4 has.

[0084] As in the Fig. 2 and Fig. The figure shown in 3 represents the Fig. Figure 5, GLp, is a characteristic curve of the LCL(LCLC) filter, which has the first busbar BSB1(Lb) and the second busbar BSB2(Lb), each with the opposite and opposite sections (side sections of the U-shape), respectively, in which the main areas are opposite each other. In other words, the GLp characteristic curve represents the change in attenuation with respect to frequency. Fig. 13, if the inductor unit Lb is like the "equivalent circuit" #3 in Fig. 4 is configured. Here, the first busbar and the second busbar occupy the same volume as when measuring the characteristic curves GLb1 and GLp.

[0085] As described above, the first busbar BSB1 and the second busbar BSB2 are arranged such that the normal-mode current flows in the opposite direction in the section where the main areas in the section forming the inductor unit Lb face each other, thereby increasing the inductance in the inductor unit Lb. Accordingly, the attenuation in the AM broadcast frequency band and the HF frequency band can be increased while preventing an increase in size. Therefore, the noise leakage in the AM broadcast frequency band and the HF frequency band of the power conversion device PWCS can be reduced. (Second embodiment)

[0086] Fig. Figure 6 is a perspective view of the structure of a first busbar BSB1 and a second busbar BSB2 according to a second embodiment. According to the second embodiment, the first busbar BSB1 and the second busbar BSB2 are arranged three-dimensionally, and an opposing section, where the main surfaces face each other, is formed on two sections. The drawing shows a first opposing section BOV1 and a second opposing section BOV2.

[0087] The first busbar BSB1 and the second busbar BSB2 comprise a first layer section extending towards the rear of the drawing (referred to as the first layer for convenience) and a second layer section extending towards the near side of the drawing (referred to as the second layer for convenience). In the first opposing section BOV1, an intermediate layer connection section is formed to connect the first layer section and the second layer section. According to this embodiment, the intermediate layer connection section of the first busbar BSB1 and the intermediate layer connection section of the second busbar BSB2 are arranged opposite each other.In the second layer section of the first busbar BSB1 and the second busbar BSB2, the opposite section BOV2 is designed such that the first busbar BSB1 and the second busbar BSB2 overlap each other when viewed from above and are positioned opposite each other at a predetermined location.

[0088] Therefore, the normal-mode current, indicated by the solid arrow flowing through the first busbar BSB1, and the normal-mode current, indicated by the dashed arrow flowing through the second busbar BSB2, are caused to flow in the same direction at the first opposite section BOV1 and the second opposite section BOV2. It should be noted that the normal-mode current flows in opposite directions in the section of the first busbar BSB1 and the section of the second busbar BSB2 that extend substantially parallel to the first layer section and the second layer section, respectively.

[0089] Fig. Figure 7 shows the construction of a busbar according to the second embodiment. Fig. 7(A) is a top view showing the structure of the first busbar BSB1 and the second busbar BSB2, as shown in Fig. Figure 6 shows in detail. Fig. 7(B) is a sectional view along a line AA' from Fig. 7(A), and Fig. 7(C) is a sectional view along a line BB' from Fig. 7(A). Between the Fig. 7(A), Fig. 7(B) and Fig. 7(C) shows broken lines indicating reciprocal relationships. Fig. 7(A) are the lengths of the first busbar BSB1 and the second busbar BSB2 for the sake of simplicity, as in Fig. 3 shorter than in Fig. 6 shown. The first busbar BSB1 and the second busbar BSB2, which are in Fig. However, those shown in 7 are not identical to those from Fig. 6 identical. Because Fig. 7 Fig. 4 is similar; only the differences are described.

[0090] As in Fig. As shown in Figure 7(A), the first busbar BSB1 and the second busbar BSB2 do not overlap in the opposite section BOV1 when viewed from above. As shown in Fig. As shown in Figure 7(C), in the opposite section BOV1, part of the main area of ​​the first busbar BSB1 and part of the main area of ​​the second busbar BSB2 are arranged opposite each other. If the normal-mode current flows in the same direction through the part of the opposite main area, the impedance of this section can be further increased.

[0091] Furthermore, it overlaps, as in Fig. As shown in Figure 7(B), the first busbar BSB1 and the second busbar BSB2 are located on the opposite side of section BOV2, and the main area of ​​the first busbar BSB1 is opposite the main area of ​​the second busbar BSB2. The normal-mode current flows in the same direction in the opposite section, which can increase the impedance of this section.

[0092] As in the second embodiment, the intermediate layer connection section can be the curved section of the first busbar BSB1 and the second busbar BSB2. The first busbar BSB1 and the second busbar BSB2 are arranged three-dimensionally, which allows the area occupied by the busbars BSB1 and BSB2 to be reduced when viewed from above. (Third embodiment)

[0093] According to the first and second embodiments, the first busbar BSB1 and the second busbar BSB2 have several opposing sections; however, the embodiments are not limited to these. A third embodiment provides a busbar structure having one opposing section.

[0094] Fig. Figure 8 shows the construction of a busbar according to the third embodiment. Fig. Figure 8(A) is a top view of the structure of the first busbar BSB1 and the second busbar BSB2. Fig. 8(B) is a sectional view along a line AA' from Fig. 8(A), and Fig. 8(C) is a sectional view along a line BB' from Fig. 8(A). Between the Fig. 8(A), Fig. 8(B) and Fig. 8(C) shows broken lines indicating reciprocal relationships. Because Fig. 8 also Fig. 4 is similar; only the differences are described.

[0095] According to the third embodiment, the first busbar BSB1 and the second busbar BSB2, when viewed from above, each have L-shaped curved sections BL1 and BL2, respectively. In other words, as shown in Fig. As shown in Figure 8(A), the first busbar BSB1 extends from the top to the bottom and is bent to the left along its path, forming an L-shaped curved section BL1. The first busbar BSB1 then extends downwards again and is connected to the smoothing capacitor element Cxp. In contrast, the second busbar BSB2 extends from the top to the bottom parallel to the first busbar BSB1 and is bent to the right along its path, forming an L-shaped curved section BL2. The first busbar BSB1 then extends downwards again and is connected to the smoothing capacitor element Cxp.

[0096] As in Fig. As shown in Figure 8(C), the main surfaces of the first busbar BSB1 and the second busbar BSB2 overlap, so that they face each other in the L-shaped curved sections BL1 and BL2. The normal-mode current flows through the first busbar BSB1 in the direction indicated by the solid arrow and through the second busbar BSB2 in the direction indicated by the dashed arrow. The main surfaces of the first busbar BSB1 section and the second busbar BSB2 section face each other at the curved sections BL1 and BL2, so that the normal-mode current flows in the same direction, thus enabling an increase in inductance in the opposite section. Accordingly, as in the first embodiment, the noise leakage in the AM broadcast frequency band and the HF frequency band of the power conversion device PWCS can be reduced.

[0097] According to the third embodiment, further miniaturization can be achieved because there are fewer curved sections. In this third embodiment, the first busbar BSB1 is configured on the side of the housing 1 relative to the second busbar BSB2; however, the second busbar BSB2 can be configured on the side of the housing 1 as in the first and second embodiments. (Fourth embodiment)

[0098] The example in which the first busbar BSB1 and the second busbar BSB2 have the identical U-shaped curved section was described according to the first embodiment. However, the first busbar BSB1 and the second busbar BSB2 cannot have curved sections of the same shape.

[0099] Fig. Figure 9 is a perspective view of the busbar assembly according to a fourth embodiment. Fig. Figure 9(A) is a perspective view of the structure of a busbar, wherein the first busbar BSB1 and the second busbar BSB2 have curved sections with different shapes. According to the first embodiment, as shown in Fig. As shown in Figure 2, the input terminals PP and PN are located on the top of the housing 1. In contrast, according to the fourth embodiment, the input terminals PP and PN are located on the left side of the housing 1. Fig. 2 of the illustrated housing 1 arranged.

[0100] As in Fig. As shown in Figure 9(A), the first busbar BSB1 extends to the right from the input terminal PP, which is provided on the left side of housing 1, and is bent in a Z-shape. After bending into a Z-shape, the first busbar BSB1 is connected to the terminal TCx2 of the smoothing capacitor element Cxp. The second busbar BSB2, on the other hand, extends to the right from the input terminal PN, is bent in a U-shape, and then in an L-shape. In this case, part of the Z-shaped bent section of the first busbar BSB1 and part of the L-shaped bent section of the second busbar BSB2 overlap, so that, viewed from above, a first opposite section BOV3 is formed.Part of the Z-shaped curved section of the first busbar BSB1 and part of the U-shaped curved section of the second busbar BSB2 also overlap, so that when viewed from above, a second opposite section BOV4 is formed.

[0101] The normal-mode currents flowing through the first busbar BSB1 and the second busbar BSB2 flow in the same direction in the first opposite section BOV3 and the second opposite section BOV4, thereby increasing the inductance of the first opposite section BOV3 and the second opposite section BOV4. According to the fourth embodiment, the normal-mode current flows through the first busbar BSB1 in the direction indicated by the solid arrow, and the normal-mode current flows through the second busbar BSB2 in the direction indicated by the dashed arrows.

[0102] In Fig. 9(A) Two opposing sections are provided which are capable of increasing the inductance, so that the inductance can be increased more than in the case where a single opposing section is provided. Assuming that the lateral length BL1 of the first busbar BSB1 and the second busbar BSB2 is, for example, 160 mm, and that the width, thickness, and material of the first busbar BSB1 and the second busbar BSB2 are the same as with reference to #3 in Fig. As described in section 4, the inductance of the first busbar BSB1 is 126.83 nH and the inductance of the second busbar BSB2 is 123.45 nH. The coupling coefficient is 0.36, and the total inductance is 158.4 nH. The frequency of the normal-mode current is 10 MHz.

[0103] Fig. Figure 9(B) shows a case in which the first busbar BSB1 and the second busbar BSB2 have a curved section, so that only an opposite section is provided. In Fig. 9(B) The first busbar BSB1 extends to the right and is then bent into an L-shape. On the other hand, the second busbar BSB2 extends to the right, is bent into an L-shape, and is then bent again into an L-shape. In Fig. 9(B) The L-shaped curved section of the first busbar BSB1 and the second L-shaped curved section of the second busbar BSB2 partially overlap when viewed from above, forming the opposite section BOV5. At the opposite section BOV5, the normal-mode currents flow in the same direction through the first busbar BSB1 and the second busbar BSB2, which can increase the inductance at the opposite section BOV5.

[0104] The first busbar BSB1 and the second busbar BSB2, as shown in Fig. 9(B) shown, have the same width, thickness and material as the first busbar BSB1 and the second busbar BSB2, as shown in Fig. 9(A) is shown. To achieve the total inductance of 158.7 nH as shown in Fig. 9(A) with the in Fig. To achieve the form shown in 9(B), the lateral length BL2 of the first busbar BSB1 and the second busbar BSB2 must be 176 mm. In other words, the inductance effect is increased compared to that shown in Fig. The shape shown in Figure 9(A) is reduced by about 10% due to a small opposing section, so the length BL2 of the busbar must be about 10% greater. In other words, miniaturization can be achieved by increasing the size of the opposing section.

[0105] If the frequency of the normal-mode current is 10 MHz, the inductance of the first busbar BSB1 is, as shown in Fig. As shown in 9(B), the inductance of the second busbar BSB2 is 140.7 nH, and the inductance of the second busbar is 128.6 nH. In this case, the coupling coefficient is 0.41.

[0106] Although the present invention has been specifically described according to the embodiments described above, it is not limited to these embodiments, and various modifications can of course be made without deviating from the scope of protection of the invention. For example, the first busbar BSB1 and the second busbar BSB2 can be connected to the terminals of the capacitor elements by soldering or the like instead of by metal screws. Reference symbol list 1 case 2, 3 cables 4 electric motor BSB1 first busbar BSB2 second busbar C1, C2 filter capacitor element Cxp smoothing capacitor element HVBT high-voltage battery SWC switching circuit< / leistungswandlungsvorrichtung> < / rauschfilter>

Claims

[1] Power conversion device designed to reduce noise superimposed on a DC voltage in the AM broadcast frequency band and the HF frequency band, comprising the following: a first capacitor unit (Cxp) that is connected between a positive terminal (HP) and a negative terminal (PH) of a current source (HVBT) and is designed to smooth out a voltage change superimposed on the DC voltage, a switching circuit (SWC) designed to convert direct current (DC) voltage into alternating current (AC) voltage, a first busbar (BSB1) that electrically connects the positive terminal of the power source to a first terminal (TCx1) of the first capacitor unit, a second busbar (BSB2) that electrically connects the negative terminal of the power source to a second terminal (TCx2) of the first capacitor unit, and a second capacitor unit (Cx) that electrically connects the first busbar and the second busbar, wherein the first busbar and the second busbar each have a U-shaped curved section between a first terminal (TC11, TC21) of the second capacitor unit and the first terminal of the first capacitor unit, or between a second terminal (TC12, TC22) of the second capacitor unit and the second terminal of the first capacitor unit, wherein the U-shaped curved sections of the first busbar and the second busbar are arranged and separated in opposite directions so that they face each other, and in turn have opposing sections in which the main surfaces of the first busbar and the second busbar face each other, and wherein the U-shaped curved sections of the first busbar and the second busbar are arranged so that a current can flow through the opposing sections in the same direction. [2] Power conversion device according to claim 1, which further comprises: a first power input terminal (PP) and a second power input terminal (PN) which are connected via a cable (2) to the positive terminal (HP) and the negative terminal (HN), respectively, wherein the first busbar (BSB1) is connected between the first power input terminal and the first terminal (TCx1) of the first capacitor unit (Cxp), and the second busbar (BSB2) is connected between the second power input terminal and the second terminal (TCx2) of the first capacitor unit, and the first terminal (TC11, TC21) of the second capacitor unit (Cx) is connected to a first section (PT1) in the first busbar between the first power input terminal and the first terminal of the first capacitor unit, and the second terminal (TC21, TC22) of the second capacitor unit is connected to a second section (PT2) in the second busbar between the second power input terminal and the second terminal of the first capacitor unit. [3] Power conversion device according to claim 2, wherein the first busbar (BSB1) has an equivalent first inductor unit (Lp1) formed between the first current input terminal (PP) and the first section (PT1), and an equivalent second inductor unit (Lp2) formed between the first section and the section to which the first terminal (TCx1) of the first capacitor unit (Cxp) is connected, and the second busbar (BSB2) has an equivalent third inductor unit (Ln1) formed between the second current input terminal (PN) and the second section (PT2), and an equivalent fourth inductor unit (Ln2) formed between the second section and the section to which the second terminal (TCx2) of the first capacitor unit is connected, the power conversion device further comprises the following: a first filter circuit comprising the first inductor unit, the third inductor unit and the second capacitor unit (Cx), and a second filter circuit, which includes the second inductor unit, the fourth inductor unit and the first capacitor unit and is connected in series with the first filter circuit.

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