JP7678642B2 - Filter device and power conversion device - Google Patents

Description

The present invention relates to a filter device and a power conversion device.

Power conversion devices installed in hybrid and electric vehicles must meet the proprietary standards established by each car manufacturer based on the high-voltage conducted noise standard added to the international standard for dealing with conductive noise generated by leakage current. At the same time, in recent years, there has been an increasing demand for smaller and cheaper power conversion devices in line with the development of the electric vehicles in which they are installed. For this reason, there is a strong demand for filter devices installed in power conversion devices to improve their high-frequency noise attenuation performance while maintaining low cost and small size.

As background to the present invention, the following Patent Document 1 discloses a technology showing a structure in which an inductance component that passes low-frequency components and a resistance component that passes high-frequency components are connected in parallel for use with large currents.

JP 2010-273207 A

In the case of high-voltage, high-current applications such as vehicle inverters, the challenge is how to freely control the inductance component of the DC wiring and easily align it to the ESL (Equivalent Series Inductance) component of the capacitor in a limited installation space due to high-voltage, high-current applications and miniaturization. However, with the technology of Patent Document 1, it is difficult to align the inductance component of the DC wiring to the ESL component of the capacitor to improve high-frequency noise attenuation performance while maintaining low cost and miniaturization in a limited installation space due to high-voltage, high-current applications and miniaturization.

In view of this, the present invention aims to provide a filter device and a power conversion device that achieve low cost, small size, and low noise.

The filter device of the present invention and the power conversion device including the same are filter devices having one end connected to a DC power source side and the other end connected to a power conversion circuit side, and include a positive wiring, a negative wiring, and a first capacitor and a second capacitor connected in parallel between the positive wiring and the negative wiring, the positive wiring has a first positive electrode connection part that connects to the first capacitor on the one end side and a second positive electrode connection part that connects to the second capacitor on the other end side, the negative wiring has a first negative electrode connection part that connects to the second capacitor on the one end side and a second negative electrode connection part that connects to the second capacitor on the other end side, and the positive wiring and the negative wiring cross each other.

The present invention provides a filter device and a power conversion device that are low cost, compact, and have low noise.

1 is a block diagram showing an overall configuration of a power conversion device according to an embodiment of the present invention. FIG. 1 is an equivalent circuit diagram of a noise filter for reducing normal mode high voltage conduction noise. FIG. 2 is an equivalent circuit diagram including parasitic components of the noise filter. FIG. 4 is a characteristic diagram showing an insertion loss of the noise filter of FIG. 3 . FIG. 1 is a diagram illustrating an example of the structure of a noise filter. FIG. 1 is an equivalent circuit diagram including parasitic components of a noise filter to which a conventional technique is applied. FIG. 7 is a characteristic diagram showing an insertion loss of the noise filter of FIG. 6 . 1 is a diagram illustrating a structure of a noise filter according to a first embodiment. FIG. 9 is a characteristic diagram showing an insertion loss of the noise filter of FIG. 8 . 11A and 11B are diagrams illustrating a structure of a noise filter according to a second embodiment. 13A and 13B are diagrams illustrating a structure of a noise filter according to a third embodiment. FIG. 1 is a diagram showing a comparison between the prior art, the first embodiment, and the second embodiment.

The following describes an embodiment of the present invention with reference to the drawings. The following description and drawings are examples for explaining the present invention, and some parts have been omitted or simplified as appropriate for clarity of explanation. The present invention can also be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

The position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc., in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

(Overall configuration of the present invention)
FIG. 1 is a block diagram showing the overall configuration of a power conversion device according to an embodiment of the present invention.

The power conversion device 1 (hereinafter, inverter 1) contains various circuit blocks and elements. The inverter 1 is also connected to a high-voltage battery 2 that supplies high DC voltage, and an electric motor 6 that is driven by AC voltage converted from DC voltage by the inverter 1.

The housing of the inverter 1 is a metal case that is connected to a GND plane 9 via a GND strap 8, and is configured to be placed on an insulator 7 that is, for example, 5 mm high, in compliance with the international standard CISPR25.

The inverter 1 has a switching circuit 14 to convert DC voltage to AC voltage. The switching circuit 14 has three unit switching circuits SW1 to SW3 that have the same configuration, and switches these periodically. Each of the unit switching circuits SW1 to SW3 has insulated gate bipolar transistors (hereinafter referred to as transistors) TR1 and TR2, and diodes D1 and D2. Although not shown, the inverter 1 has a control circuit board that generates a control signal for the switching circuit 14.

Diodes D1 and D2 are connected between the collector and emitter of transistors TR1 and TR2, respectively. The collector of transistor TR1 is electrically connected to positive wiring 11, which is a DC wiring, and the emitter of transistor TR2 is electrically connected to negative wiring 12, which is also a DC wiring. The emitter of transistor TR1 is connected to the collector of transistor TR2. The connection node connected between the emitter and collector is an output node, which is connected from each of unit switching circuits SW1 to SW3 to coils 6-U to 6-W of electric motor 6 via high-voltage AC cables 5.

The flow of control signals for inverter 1 will now be described. A switch control signal from a control circuit board (not shown) is supplied to the gates of transistors TR1 and TR2 of unit switching circuits SW1 to SW3. This switch control signal controls the switching of transistors TR1 and TR2 so that they are complementarily turned on and off. Furthermore, as transistors TR1 and TR2 are complementarily turned on and off, positive and negative voltages, that is, AC voltages, are periodically output to the output node.

In addition, stray capacitance (parasitic capacitance) occurs between the switching circuit 14 and the housing of the inverter 1 due to voltage fluctuations in the output section caused by the cyclic on/off of transistors TR1 and TR2. In Figure 1, this stray capacitance is shown as stray capacitance 1-Cs.

The high voltage source impedance stabilization network (LISN) 3 will be described. The high voltage battery 2 supplies power to the inverter 1 via the high voltage source impedance stabilization network (LISN) 3. This housing 3 has a positive LISN circuit section 31 connected to the positive electrode terminal HVP of the high voltage battery 2, and a negative LISN circuit section 32 connected to the negative electrode terminal HVN of the high voltage battery 2, which are housed in a metal housing. The housing of the LISN 3 is connected to the GND plane 9. The positive LISN circuit section 31 and the negative LISN circuit section 32 are electrically connected to the positive wiring 11 and the negative wiring 12, which are the DC wiring of the inverter 1, via the high voltage DC cable 4.

The electric motor 6 will be described. The electric motor 6 is a three-phase electric motor, and includes a rotor and a stator (not shown). The housing of the electric motor 6 is connected to the GND plane 9. The electric motor 6 supplies three-phase AC voltage generated by the inverter 1 to three-phase coils 6-U, 6-V, and 6-W (U, V, and W) arranged on the stator via a high-voltage AC cable 5. As a result, the three-phase coils 6-U, 6-V, and 6-W generate magnetic fields corresponding to the three-phase AC voltages, and the rotor rotates. In FIG. 1, the stray capacitance (parasitic capacitance) generated between the three-phase coils 6-U, 6-V, and 6-W and the housing of the motor 6 is shown as stray capacitance 6-Cs. Although not particularly limited, the housing of the electric motor 6 is connected to the GND plane 9.

In the inverter 1, a smoothing capacitor Cx for smoothing the DC voltage and a noise filter device 13 are provided between the positive wiring 11 and the negative wiring 12. The smoothing capacitor Cx suppresses the ripple voltage and ripple current generated in the DC wirings 11 and 12, which are bus bars connected to the DC high voltage, during the switching operation of the switching circuit 14. The smoothing capacitors Cx1 and Cx2 are for reducing normal mode noise. The reduction effect or attenuation performance is generally expressed by the insertion loss of the filter. The reduction mechanism by the capacitors is explained below. The principle is to suppress the outflow of noise to the outside by providing a low impedance path between the DC wirings by implementing a noise filter. In addition, in order to suppress high voltage conduction noise in a wide frequency band, two capacitors with different capacities connected in parallel are generally used.

The noise filter device 13 has a magnetic core Lc that surrounds the DC wiring including the positive wiring 11 and the negative wiring 12, a first grounding capacitor Cy1 connected to the DC wiring 11, 12 in the front stage of the magnetic core Lc, and a second grounding capacitor Cy2 connected to the DC wiring 11, 12 in the rear stage of the magnetic core Lc. The grounding capacitors Cy1 and Cy2 and the magnetic core Lc are used to reduce common mode noise.

The first ground capacitor Cy1 is composed of a ground capacitor Cy11 connected between the positive wiring 11 and the first ground point G1, and a ground capacitor Cy12 connected between the negative wiring 12 and the first ground point G1. Similarly, the second ground capacitor Cy2 is composed of a ground capacitor Cy21 connected between the positive wiring 11 and the second ground point G2, and a ground capacitor Cy22 connected between the negative wiring 12 and the second ground point G2.

The noise filter device 13 attenuates noise from the high DC voltage supplied from the high voltage battery 2, while inputting the high DC voltage to the switching circuit 14, which is a power conversion unit. The noise current that causes noise is a current leaking into the power wiring or cable connected between the high DC voltage battery 2 and the inverter 1, and is a common mode current because it flows between the GNDs.

The common mode current is caused by voltage fluctuations to ground that occur when the transistors TR1 and TR2 are switched on and off periodically. This voltage fluctuation at the output of the switching circuit 14 causes a common mode current to flow between the inverter 1 and the housing of the motor 6 through the stray capacitance 1-Cs that is parasitic between the switching circuit 14 and the housing of the inverter 1, and the stray capacitance 6-Cs that exists between the coils 6-U to 6-W of the motor 6 and the housing, and this current generates high-voltage conducted noise. Therefore, in order to reduce high-voltage conducted noise, it is necessary to reduce the common mode current. In the inverter 1, the configuration of the noise filter device 13 is used to address the noise current, which is the main cause of high-voltage conducted noise, and to attenuate the noise while complying with the high-voltage conducted noise standard.

(Regarding noise standards)
The high-voltage conducted noise standard will be explained. The noise standard generally specifies the regulation value in the frequency band from 0.15 MHz to 108 MHz. The high-voltage conducted noise standard is a standard added to CISPR25 Ed4, an international standard created by the International Special Committee on Radio Interference (CISPR) in October 2016. This regulates the noise in the FM broadcast frequency band (76 MHz to 108 MHz), which is used for various purposes, to be lower than other frequency bands. For example, high-voltage conducted noise may cause malfunction of in-vehicle electric and electronic devices. Therefore, the amount of high-voltage conducted noise generated by the inverter 1 must be measured before shipment, and the amount of noise must be equal to or less than the regulation value specified by the laws and regulations of each country and the customer's required specifications. Therefore, the inverter 1 employs a noise filter device 13 to comply with the high-voltage conducted noise standard and to have an effective filter configuration.

Figure 2 is an equivalent circuit diagram of a noise filter device 13 for reducing normal mode high voltage conduction noise.

Capacitors Cx1 and Cx2 are connected in parallel to the positive DC wiring 11 and the negative DC wiring 12. P1 and N1 are the connections between Cx1 and the positive DC wiring 11 and the negative DC wiring 12, respectively, and P2 and N2 are the connections between Cx2 and the positive DC wiring 11 and the negative DC wiring 12, respectively. Furthermore, Pin and Nin are the input terminals on the positive and negative sides, respectively, and represent the connections between the switching circuit 14, which is a noise source, and the positive DC wiring 11 and the negative wiring 12. Similarly, Pout and Nout are the output terminals on the positive and negative sides, respectively, and represent the connections between the positive DC wiring 11, the negative wiring 12, and the high-voltage DC cable 4.

The noise reduction effect NS is expressed by the following formula (1) using the input voltage Vin (simulating a noise source) input between Pin and Nin, and the output voltage Vout output between Pout and Nout.

NS=|Vout/Vin|...Formula (1)

In order to obtain the desired noise reduction effect NS, ideally it is sufficient to simply select constants for the capacitors Cx1 and Cx2 that provide low impedance in the target frequency band, but actual components (elements) have parasitic components. For example, capacitor components and DC wiring have parasitic inductance (ESL) components such as lead wires.

Figure 3 is an equivalent circuit diagram including the parasitic components of the noise filter device 13 in Figure 2.

In FIG. 3, the parasitic inductances of the first capacitor Cx1 and the second capacitor Cx2 are represented by equivalent series inductances Lc1 and Lc2, respectively. The inductance component of the positive DC wiring 11 between the positive connection parts P1 and P2 is represented by equivalent series inductance Lp1, and the inductance component of the negative DC wiring 12 between the negative connection parts N1 and N2 is represented by equivalent series inductance Ln1. Similarly, Lp0 is the inductance component of the positive DC wiring between Pout-P1 and Lp2 is the inductance component of the positive DC wiring between Pin-P2, Ln0 is the inductance component of the negative DC wiring between Nout-N1 and Ln2 is the inductance component of the negative DC wiring between Nin-N2.

k1 is the coupling coefficient between inductors having inductances Lp1 and Ln1. Note that the coupling coefficients between inductors having inductance components Lp0 and Ln0, and Lp2 and Ln2 are not shown in the figure, but are used in the actual calculations. Also, the * marks attached to inductors Lp1 and Ln1 indicate the direction in which the magnetic field is generated.

Power supply Gn is an AC voltage source that simulates the noise voltage generated by the switching circuit 14, and V1 is a voltmeter that measures power supply Gn. Resistors R3 and R4 respectively simulate the internal resistance of power supply Gn and the equivalent resistance of the components connected to the output side. V2 is a voltmeter that measures the voltage of resistor R4.

Figure 4 is a characteristic diagram showing the insertion loss of the noise filter device 13 in Figure 3.

In the characteristic diagram of FIG. 4, the horizontal axis indicates frequency F (Frequency [MHz]), and the vertical axis indicates the insertion loss of the noise filter device 13, i.e., the ratio of voltages V2 and V1 shown in FIG. 3, expressed in decibels (dB). The smaller the ratio of voltages V2 and V1, the higher the insertion loss of the filter and the better the attenuation performance.

Characteristic curve GLb1 shows the change in insertion loss with a change in frequency F when the equivalent series inductances Lc1 and Lc2 of capacitors Cx1 and Cx2 are set to 0 nH, respectively. On the other hand, characteristic curve GLb0 shows the change in insertion loss when the equivalent series inductances Lc1 and Lc2 are set to a typical value of 40 nH, respectively. Note that the parameters of the circuit elements other than Lc1 and Lc2 when calculating characteristic curves GLb0 and GLb1 are the same.

Comparing characteristic curves GLb0 and GLb1, in the target frequency band of 20 MHz or higher, the filter insertion loss of characteristic curve GLb0 is worse than that of characteristic curve GLb1. As mentioned above, the high-voltage conducted noise standard prescribes regulation values for the frequency band from 0.15 MHz to 108 MHz, and in particular, in the high-frequency band of 20 MHz or higher, including the FM frequency band (76 MHz to 108 MHz) used for various applications, the regulation values are lower than those for other frequency bands, so it is necessary to improve the filter insertion loss.

Figure 5 shows an example of the structure of a noise filter.

In this example noise filter structure, the wiring 111 and 121 between the connection parts are each approximately 10 mm long and 15 mm wide, and their inductance components are calculated to be approximately 10 nH. Using these values, the equivalent circuit (Figure 6) is used to calculate the insertion loss of the filter. The calculation results are shown in Figure 7.

(Conventional technology and its problems)
FIG. 6 is an equivalent circuit diagram including parasitic components of a noise filter to which the conventional technology is applied.

In FIG. 6, in the equivalent circuit shown in FIG. 3, the connection wiring between the first capacitor Cx1 and the positive wiring 11 and the connection wiring between the second capacitor Cx2 and the positive wiring 11 are crossed. Note that an example in which the first capacitor Cx1 and the second capacitor Cx2 are structurally crossed using this circuit configuration is shown in FIG. 12(b) described below.

The purpose of this crossing of the connection wiring will now be explained. Conventional techniques for canceling out ESL components include using capacitors with short lead wires or cutting and shortening the lead wires, but this requires the addition of custom parts or cutting work, which creates a new issue of increased manufacturing costs for the power conversion device. To solve this issue, the circuit configuration shown in Figure 6 is used to cancel out the ESL components.

Another key feature of this configuration is that the inductance components Lp1 and Ln1 of the wiring between the connections can be made to match the ESL components Lc1 and Lc2 of the capacitor. This improves the insertion loss of the filter. For example, in low-voltage, low-current applications such as control boards, many capacitors are surface-mounted without leads and have an ESL component of around a few nH, so by adjusting the length and width of the board wiring traces, the inductance components of the wiring between the connections can be easily made to match the ESL components of the capacitor.

However, in the case of high-voltage, high-current applications such as vehicle inverters, the capacitors used in noise filters are high-voltage compatible types, and since they have lead wires and are larger in size than low-voltage compatible types, they are correspondingly larger than those for low-voltage, low-current applications such as ESL component control boards, at approximately 40 to 50 nH. In this case, the DC wiring needs to be made wider to maintain thermal stability, and since the space for arranging the DC wiring is limited due to the demand for miniaturization, the bus bar needs to be shortened. In other words, the inductance component of the DC wiring tends to become smaller, making it difficult to match the ESL component of the capacitor, which becomes larger. As a result, a problem arises in which the effect of improving the insertion loss of the filter cannot be obtained. The present invention is intended to structurally solve this problem while utilizing the properties of the circuit shown in Figure 6.

Figure 7 is a characteristic diagram showing the insertion loss of the noise filter in Figure 6.

Characteristic curve GLb2 shows the change in insertion loss of the filter with a change in frequency F when inductors Lp1 and Ln1 are set to 10 nH. Characteristic curve GLb0 shows the change in insertion loss when there are no crossing wires, and is the same as GLb0 in Figure 4. Note that the parameters of the circuit elements other than the crossing wire configuration when calculating characteristic curves GLb0 and GLb2 are the same as those in Figure 3.

As shown in Figure 7, if the parasitic inductance and capacitor ESL components are not aligned, there will be no improvement in the insertion loss of the filter, as shown by the characteristic curves GLb0 and GLb2, which show almost no change.

(First embodiment)
FIG. 8 is a diagram showing the structure of a noise filter device 13 according to the first embodiment.

Figure 8(a) is a circuit diagram of a noise filter device 13 according to a first embodiment of the present invention, and Figure 8(b) is a diagram showing the configuration of the three-dimensional structure. Figure 8(a) shows a noise filter device 13 in which, among the circuit blocks and components housed in the housing of the inverter 1, one end (left side of Figure 8(a)) is connected to the DC power source (high voltage battery 2) and the other end (right side of Figure 8(a)) is connected to the power conversion circuit (switching circuit 14).

The feature of the present invention is that the positive wiring 111 connecting the first positive connection part P1 and the second positive connection part P2 intersects with the negative wiring 121 connecting the first negative connection part N1 and the second negative connection part N2. This intersection is laminated as shown in FIG. 8(b), and by adjusting the area and spacing of this part and the length and width of the wiring, the inductance components of the positive wiring 111 and the negative wiring 121 can be controlled and aligned to the ESL components Lc1 and Lc2 of the first capacitor Cx1 and the second capacitor Cx2.

Figure 9 is a characteristic diagram showing the insertion loss of the noise filter in Figure 8.

The characteristic curve GLb3 of the present invention shows the change in insertion loss with a change in frequency F when the inductance components of Lp1 and Ln1 are approximately 40 nH, and an improvement of 20 dB or more in insertion loss can be obtained in the high frequency band of 20 MHz or higher.

Second Embodiment
10A and 10B are diagrams showing the structure of a noise filter device 13 according to the second embodiment. Note that Fig. 10A is the same as Fig. 8A.

In FIG. 10(b), the intersection of the positive wiring 111 and the negative wiring 121 is arranged so as to follow the multiple faces of the first capacitor Cx1 and the second capacitor Cx2, which are polyhedral capacitors. Furthermore, when the capacitance of the capacitor Cx2 is smaller than that of the capacitor Cx1, the busbar intersection follows the bottom surface of the capacitor Cx2. The bottom surface of the capacitor Cx2 is the side that is installed in the case (the housing of the inverter 1). This allows for a larger area to be secured for routing the busbar, and allows for a greater inductance component of the positive wiring 111 and the negative wiring 121.

The intersecting positive and negative wirings 111 and 121 are arranged along multiple faces of the first and second capacitors, and the busbar intersections are routed in a serpentine fashion. This further ensures a large area for routing the busbars.

For example, the busbar intersection may be arranged along only the side of the capacitor that is closer to the noise source or closer to the output terminal.

Third Embodiment
11A and 11B are diagrams showing the structure of a noise filter device 13 according to a third embodiment of the present invention. Note that Fig. 11A is the same as Fig. 8A and Fig. 10A.

In Figure 11(b), the intersection is arranged only along the side of the capacitor that is closer to the noise source (the power conversion device side). This prevents the height from becoming too large.

Figure 12 is a diagram showing a comparison between the prior art, the first embodiment, and the second embodiment. Note that Figure 12(a) shows a noise filter with the same structure as Figure 5, and Figure 12(b) shows a noise filter that is a structured version of the circuit diagram in Figure 6. Figure 12(c) shows the first embodiment, and Figure 12(d) shows the second embodiment.

In FIG. 12, the inductance component is increased in the first embodiment shown in FIG. 12(c) and the second embodiment shown in FIG. 12(d) compared to the cases shown in FIG. 12(a) and FIG. 12(b). Furthermore, the second embodiment, which has a larger busbar area than the first embodiment, has an even greater inductance component than the first embodiment.

As can be seen from the wiring structures in Figures 12(c) and 12(d), the current flows in the same direction at the intersections, generating a magnetic field in the same direction. As a result, the mutual coefficient and mutual inductance at these points are positive values, and the inductance component of the entire wiring becomes larger. In other words, as mentioned above, by adjusting the area and spacing of the intersections and the length and width of the wiring, the inductance component of the wiring can be controlled to match the ESL component of the capacitor. This cancels out the ESL component of the capacitor, improving the insertion loss characteristics of the filter and suppressing high-frequency normal mode high-voltage conductive noise.

The first to third embodiments of the present invention described above provide the following advantages.

(1) The filter device 13 has one end connected to the DC power supply side and the other end connected to the power conversion circuit side, and includes a positive wiring 11, a negative wiring 12, and a first capacitor Cx1 and a second capacitor Cx2 connected in parallel between the positive wiring 11 and the negative wiring 12. The positive wiring 11 has a first positive electrode connection part P1 connected to the first capacitor Cx1 at one end and a second positive electrode connection part P2 connected to the second capacitor Cx2 at the other end. The negative wiring 12 has a first negative electrode connection part N1 connected to the second capacitor Cx2 at one end and a second negative electrode connection part N2 connected to the second capacitor Cx2 at the other end. The positive wiring 11 and the negative wiring 12 cross each other. In this way, a filter device and a power conversion device that achieve low cost, small size, and low noise can be provided.

(2) In the filter device 13, the intersections between the positive and negative wiring 11 and 12 are laminated. By doing so, the area and spacing of this portion and the length and width of the wiring can be adjusted to control the inductance components of the positive and negative wiring 11 and 12, and can be made equal to Lc1 and Lc2, which are the ESL components of the first capacitor Cx1 and the second capacitor Cx2.

(3) In the filter device 13, the positive electrode wiring 11 and the negative electrode wiring 12 are arranged along multiple faces of the first capacitor Cx1 and the second capacitor Cx2. In this way, it is possible to ensure a wiring area for the busbars 11 and 12.

(4) In the filter device 13, when the capacitance of the second capacitor Cx2 is smaller than the capacitance of the first capacitor Cx1, the positive electrode wiring 11 and the negative electrode wiring 12 intersect on the underside of the second capacitor Cx2. This makes it possible to ensure a wiring area for the busbars 11 and 12.

(5) In the filter device 13, the intersection between the positive electrode wiring 11 and the negative electrode wiring 12 is serpentine. This makes it possible to ensure a sufficient routing area for the bus bars 11 and 12.

(6) In the filter device 13, the inductance between the positive wiring 11 and the negative wiring 12 is approximately equal to the inductance of the first capacitor Cx1 or the second capacitor Cx2. This improves the insertion loss of the filter.

The present invention is not limited to the above-described embodiment, and various modifications and other configurations can be combined without departing from the spirit of the invention. Furthermore, the present invention is not limited to having all of the configurations described in the above-described embodiment, and includes configurations in which some of the configurations have been omitted. For example, the above-described embodiment has been described using a power conversion device mounted on a vehicle such as a hybrid vehicle or an electric vehicle, but the present invention is not limited to these and can also be applied to power conversion devices used in construction machinery and railway vehicles.

1...Power conversion device (inverter)
1-Cs... switching circuit-casing stray capacitance 2... high voltage battery 3... high voltage power supply impedance stabilization circuit network (LISN)
31...Positive LISN circuit section 32...Negative LISN circuit section 4...High voltage DC cable 5...High voltage AC cable 6...Electric motor 6-U...U-phase coil 6-V...V-phase coil 6-W...W-phase coil 6-Cs...Frayed capacitance between coil and housing 7...Insulator 8...GND strap 9...GND plane 10...Current 10a...Reverse current 10b... currents in the same direction 11... positive (DC) wiring 12... negative (DC) wiring 13... noise filter device 14... switching circuit 111... positive wiring 121 connecting the first positive connection part P1 and the second positive connection part P2... negative wiring SW1 to SW3 connecting the first negative connection part N1 and the second negative connection part N2... unit switching circuits TR1, TR2... insulated gate bipolar transistors D1, D2... diode Cx... smoothing capacitor Gn... power supply Lc... magnetic cores Lc1, Lc2... equivalent series inductances Lp0 to Lp3... equivalent series inductances (positive wiring)
Ln0 to Ln3: equivalent series inductance (negative wiring)
k1...coupling coefficient between the positive DC wiring and the negative DC wiring Cy1, Cy2...ground capacitor Cy11, Cy21...ground capacitor between the positive DC wiring and the housing Cy12, Cy22...ground capacitor between the negative DC wiring and the housing Cx1...first capacitor Cx2 between the positive DC wiring and the negative DC wiring...second capacitor P1 between the positive DC wiring and the negative DC wiring...first positive connection part P2 which is the connection part between the first capacitor Cx1 and the positive wiring 11...second positive connection part N1...first negative connection part N2 which is the connection part between the first capacitor Cx1 and the negative wiring 12...second negative connection part which is the connection part between the second capacitor Cx2 and the negative wiring 12

Claims (7)

A filter device having one end connected to a DC power supply side and the other end connected to a power conversion circuit side,
A positive electrode wiring, a negative electrode wiring, and a first capacitor and a second capacitor connected in parallel between the positive electrode wiring and the negative electrode wiring,
The positive wiring has a first positive electrode connection portion connected to the first capacitor on one end side of the positive wiring , and a second positive electrode connection portion connected to the second capacitor on the other end side of the positive wiring ,
The negative wiring has a first negative electrode connection portion connected to the second capacitor on one end side of the negative wiring , and a second negative electrode connection portion connected to the first capacitor on the other end side of the negative wiring ,
When a virtual plane is provided that passes through a midpoint between the first positive electrode connection portion and the first negative electrode connection portion and is perpendicular to a virtual line that connects the first positive electrode connection portion and the first negative electrode connection portion, the first positive electrode connection portion and the second positive electrode connection portion are located on different sides of the virtual plane, and the first negative electrode connection portion and the second negative electrode connection portion are located on different sides of the virtual plane.
Filter device. 2. The filter device according to claim 1,
The positive electrode wiring and the negative electrode wiring are stacked on each other at least between the first capacitor and the second capacitor . 3. A filter device according to claim 2,
the positive electrode wiring and the negative electrode wiring are arranged along at least a plurality of surfaces of the first capacitor and the second capacitor, respectively . 3. A filter device according to claim 2,
When a surface of the first capacitor on which the first positive electrode connection portion and the second positive electrode connection portion are formed and a surface of the second capacitor on which the first negative electrode connection portion and the second negative electrode connection portion are formed are defined as upper surfaces, and a surface opposite to the upper surfaces is defined as a lower surface,
When the capacitance of the second capacitor is smaller than the capacitance of the first capacitor, the positive electrode wiring and the negative electrode wiring are stacked on the lower surface of the second capacitor.
Filter device. 5. A filter device according to claim 4 ,
The portion where the first capacitor and the second capacitor are stacked on each other is disposed from the upper surface of the first capacitor, passing between the first capacitor and the second capacitor, to the lower surface of the second capacitor.
Filter device. 2. The filter device according to claim 1,
A filter device, wherein an inductance between the positive wiring and the negative wiring is approximately equal to an inductance of the first capacitor or the second capacitor. A power conversion device comprising the filter device according to any one of claims 1 to 6.

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