JP7247748B2 - power converter - Google Patents

Description

The present invention relates to a power conversion device used in electric vehicles and the like.

2. Description of the Related Art An electric vehicle is equipped with a power conversion device for supplying electric power to a load such as a vehicle-mounted device. A power conversion device has a configuration in which a power conversion circuit unit such as a converter and an inverter is housed in a housing, and converts DC power from a vehicle battery into power suitable for a load. In such a power conversion device, noise generation accompanying switching operation and noise invasion from the outside are problems. As a general countermeasure against noise, a filter circuit including a capacitor and a coil is arranged on the input side or the output side of the power conversion circuit unit to suppress the influence of noise.

For example, the noise filter disclosed in Patent Document 1 places a common mode choke coil in an input power supply line to a power conversion device including an inverter and a converter, and places a capacitor connected in series with the common mode choke coil as an output. A bypass circuit is formed by connecting to a low-impedance common-mode current extraction circuit placed on the power supply line. Furthermore, in order to suppress the leakage current flowing to the ground through the stray capacitance between the switching element and the cooler, the grounded cooler and the bypass path are directly connected with a capacitor and passed through a low-impedance common mode current extraction circuit. It is configured so that a common mode current flows through the path.

JP 2015-53835 A

In the configuration of Patent Document 1, a bypass circuit that does not pass through the housing is provided in order to prevent the common mode current from flowing through the housing at the ground potential to the power supply side and the load side. In this case, various filter circuits are added to the bypass circuit connecting the various parts of the device, which increases the number of parts and tends to complicate the circuit configuration or increase the size of the device. Further, when the power system circuit and the control system circuit are mounted on the same circuit board, a common mode current is superimposed on the control system circuit through stray capacitance between wirings or by electric field radiation. In that case, the common mode current may flow out from the signal path of the control system circuit.

SUMMARY OF THE INVENTION The present invention has been made in view of such problems, and provides a power conversion device that can suppress the outflow of common mode current to the outside of the device and that can simplify the device configuration and reduce the size. and

One aspect of the present invention is
At least part of a power conversion circuit unit (2) connected to power lines (Lp, Ln) and power of the power conversion circuit unit are connected to a circuit board (5) housed in a metal housing (10). A power converter (1) equipped with a control circuit (3) for controlling conversion operation and a filter circuit (4) including capacitors (41, 42) electrically connected to the housing,
The circuit board having a single-layer or multi-layer structure is supported by a plurality of board supports (11) integrally formed with the housing,
The control circuit unit includes a plurality of circuits (31, 32) formed on different surfaces of the circuit board, a plurality of ground patterns (GP1, GP2) corresponding to the plurality of circuits, and a plurality of housing grounds. has a part (GND1, GND2),
the plurality of ground patterns are located on different surfaces or different layers of the circuit board;
The plurality of housing ground portions, each of which also serves as the substrate support portion, is provided with at least one for each of the plurality of circuits, and is electrically connected to the ground pattern corresponding to each circuit, and,
At least one of the housing ground portions is configured as a housing ground portion (GND1) common to a plurality of the ground patterns, and each ground pattern has a housing ground plane (12) of the common housing ground portion. ) or individually connected to the connection conductor (M) electrically connected to the housing ground plane without coming into contact with the other ground pattern outside the housing ground plane or the connection conductor. is in the power converter.

In the above configuration, the circuit board is supported by a plurality of board support portions, and the ground patterns of the plurality of circuits of the control circuit are electrically connected to the housing through the board support portions that also serve as the housing ground portion. be done. At this time, power system circuits and control system circuits coexist on the circuit board, and there is a risk that common mode noise accompanying the power conversion operation may be superimposed on the control circuit section. The circuits are individually connected to the housing ground section, and a common housing ground section is provided so that common mode noise is recovered from the housing to the filter circuit side. In this case, since the ground patterns of the plurality of circuits are individually connected to the common ground plane of the housing or the connection conductor, it is possible to reduce the common impedance of the current path to the housing.

This makes it easier for the common mode current to flow to the housing via the housing ground section, and suppresses the flow of the common mode current to the outside via the signal path of the control circuit section. Therefore, common mode noise can be reduced while suppressing changes in the circuit configuration and an increase in the number of parts, so that the entire device can be made compact.

As described above, according to the above aspect, it is possible to provide a power conversion device that can suppress the outflow of common-mode current to the outside of the device, and that can simplify the configuration and reduce the size of the device.
It should be noted that the symbols in parentheses described in the claims and the means for solving the problems indicate the corresponding relationship with the specific means described in the embodiments described later, and limit the technical scope of the present invention. not a thing

FIG. 2 is a cross-sectional view in the plate thickness direction schematically showing the schematic configuration of the power conversion device according to the first embodiment; FIG. 2 is a cross-sectional view in the plate thickness direction schematically showing the main configuration of the power conversion device in the first embodiment; 1 is a block diagram showing the overall schematic configuration and circuit configuration of a power conversion device according to Embodiment 1. FIG. 2 is a circuit diagram of a filter circuit that constitutes the power conversion device according to the first embodiment; FIG. FIG. 2 is a cross-sectional view in the board surface direction showing an arrangement example of circuits mounted on the circuit board of the power conversion device and the housing ground in the first embodiment; FIG. 2 is a schematic cross-sectional view showing an arrangement example of a circuit board housed in a housing of the power conversion device and a housing ground according to the first embodiment; FIG. 4 is a schematic cross-sectional view showing the operational effects of the configuration of the power converter according to the first embodiment in comparison with a configuration that does not have a common housing ground portion; FIG. 2 is a cross-sectional view in the board surface direction for explaining the flow of common-mode currents occurring in the circuit board of the power conversion device according to the first embodiment; FIG. 2 is a cross-sectional view in the board surface direction for explaining recovery paths of common-mode currents generated in the circuit board of the power conversion device according to the first embodiment; FIG. 4 is a partially enlarged cross-sectional view showing a configuration example of a circuit board of the power conversion device and an example of a support structure to a housing ground portion according to the first embodiment; 4A and 4B are cross-sectional views in a plate surface direction and a plate thickness direction schematically showing a schematic configuration of a power converter according to Embodiment 2; Sectional drawing of the board|plate thickness direction which shows typically schematic structure of the power converter device in the modification of Embodiment 2. FIG. 3A and 3B are cross-sectional views in a plate surface direction and a plate thickness direction schematically showing a schematic configuration of a power conversion device according to a third embodiment;

(Embodiment 1)
A first embodiment of a power converter will be described with reference to FIGS. 1 to 10. FIG.
The power conversion device of this embodiment is configured as an in-vehicle power conversion device mounted on an electric vehicle such as an electric vehicle or a hybrid vehicle.
As schematically shown in FIG. 1, the power conversion device 1 includes a metal housing 10, a power conversion circuit section 2, a control circuit section 3, and a filter circuit 4 which are accommodated in the housing 10. , and a circuit board 5 on which these circuits are mounted. A positive line Lp and a negative line Ln, which are power lines, are connected to the power conversion circuit unit 2 , and the power conversion operation of the power conversion circuit unit 2 is controlled by the control circuit unit 3 . At least a part of the power conversion circuit unit 2 is mounted on the circuit board 5 . Filter circuit 4 includes common mode capacitors 41 and 42 that are capacitors electrically connected to housing 10 .

The circuit board 5 is supported by a plurality of substrate support portions 11 integrally formed with the housing 10, and the plurality of substrate support portions 11 are connected to a housing ground portion GND ( For example, GND1 to GND3) are configured. The number and arrangement of the plurality of substrate support portions 11, that is, the plurality of housing ground portions GND, can be arbitrarily set according to the circuit layout or the like.

The control circuit unit 3 includes an external connection circuit 31 and a main control circuit 32, which are a plurality of circuits formed in different regions of the circuit board 5, and a plurality of ground patterns GP (for example, GP1 , GP2). The multiple ground patterns GP are electrically connected to at least one of the multiple substrate support portions 11 . Here, as an example, two ground patterns GP1 and GP2 corresponding to the two circuits 31 and 32 are illustrated, but the configuration may include three or more circuits or ground patterns GP. can be set to

Here, the ground patterns GP1 and GP2 of the external connection circuit 31 and the main control circuit 32 are connected to the housing ground sections GND1 and GND2, respectively, and one of them is used as the common housing ground section GND1. there is A housing ground plane 12 is provided in the common housing ground part GND1, and a plurality of ground patterns GP1 and GP2 extend to the plane of the housing ground plane 12 or are electrically connected to the housing ground plane 12. are individually connected to the connection conductors M that are connected.

As shown in FIG. 2, the control circuit section 3 can be configured such that an external connection circuit 31 and a main control circuit 32 are arranged on different surfaces 51 and 52 of the circuit board 5, respectively. At this time, in the thickness direction X of the circuit board 5, an overlap region R is formed in which the formation region R1 of the external connection circuit 31 and the formation region R2 of the main control circuit 32 partly overlap with each other via the insulating layer 5A.
1 and 2, the direction orthogonal to the board thickness direction X of the circuit board 5, that is, the direction parallel to the board surface of the circuit board 5 is hereinafter referred to as the board surface direction Y. As shown in FIG.
2 is referred to as the lower side, and the opposite side thereof is referred to as the upper side. called.

Preferably, the common housing ground part GND1 is arranged inside the overlap region R or arranged close to it. The plurality of ground patterns GP1 and GP2 are located opposite to each other in the plate thickness direction X via the insulating layer 5A, and are connected directly to the housing ground plane 12 or are connection conductors embedded in the insulating layer 5A. It is connected via part M.
The details and effects of this configuration will be described later.

The board support portion 11 is provided so as to protrude in the plate thickness direction X from the bottom wall 10A, which is the first wall portion of the housing parallel to the circuit board. The board support part 11 is a columnar body or a block body having a housing ground plane 12 provided on the projecting end side. It is electrically connected to the ground plane 12 .

Next, the configuration of each part of the power conversion device 1 as a DC-DC converter will be described in detail.
As shown in FIG. 3, the power conversion circuit unit 2 includes a plurality of switching elements SW1 to SW6. These switching elements SW1 to SW6 are connected to the positive line Lp or the negative line Ln for power supply, or It is connected to the positive output line L1 or the negative output line L2, which are output lines. The positive line Lp and the negative line Ln are connected to the positive terminal and the negative terminal of the high-voltage battery BH, respectively, and the output lines L1 and L2 are connected to the positive terminal and the negative terminal of the auxiliary battery BL, respectively. Switching elements SW1 to SW6 are accommodated in housing 10 as switching module SM.

The power conversion device 1 is arranged between a vehicle high voltage battery BH (for example, 288 V) and an onboard equipment auxiliary battery BL (for example, 14 V), and steps down the high voltage for auxiliary equipment. Used as a DC-DC converter.
The control circuit unit 3 controls the power conversion operation in the power conversion circuit unit 2 to maintain the auxiliary battery BL at a predetermined voltage. A signal line Ls for inputting a signal from the outside is connected to the control circuit unit 3 via an external connection terminal 6. For example, a control command from an electronic control unit (hereinafter referred to as an ECU) on the vehicle side, , a detection signal or the like from a voltage sensor or a current sensor (not shown).

The power conversion circuit unit 2 includes a transformer T including a primary coil T1 and a secondary coil T2, switching elements SW1 to SW4 forming a primary side switching circuit of the transformer T, and a switching element SW5 forming a secondary side switching circuit. , SW6. As the switching elements SW1 to SW6, in addition to MOSFETs (ie, field effect transistors), power semiconductor switching elements such as IGBTs (ie, insulated gate bipolar transistors) can be used.

The primary side switching circuit has a series connection body of switching elements SW1 and SW2 that operate complementarily, and a series connection body of switching elements SW3 and SW4. They are arranged parallel to each other between the lines Ln. In the two sets of series-connected bodies, the drain terminals of the switching elements SW1 and SW3, which are upper arm elements, are connected to the positive line Lp, and the source terminals of the switching elements SW2, SW4, which are the lower arm elements, are connected to the negative line. Ln.

The upper arm element is a main switch for power conversion, and the lower arm element is a synchronous rectification switch that turns on and off alternately. A connection point between the source terminal of the switching element SW1 and the drain terminal of the switching element SW2 is connected to one end side of the primary coil T1, and a connection point between the source terminal of the switching element SW3 and the drain terminal of the switching element SW4 is It is connected to the other end side of the primary coil T1.

At this time, the switching elements SW1 and SW4 are turned on (that is, open), so that a current flows from the switching element SW1 through the primary coil T1 and the switching element SW4. Next, when these switching elements SW1 and SW4 are turned off (that is, closed) and the switching elements SW2 and SW3 are turned on (that is, opened), the switching element SW2 is switched from the switching element SW3 via the primary coil T1. through which a current flows in the opposite direction.

The secondary coil T2 has a structure having an intermediate tap T3, and a negative output line L2 drawn from the intermediate tap T3 is connected to the negative terminal of the auxiliary battery BL. In the secondary side switching circuit, the switching element SW5 is connected between one end of the secondary coil 62 and the positive electrode side output line L1, and the switching element SW6 is connected between the other end of the secondary coil 62 and the positive electrode side. It is connected between the output line L1. A reactor L is arranged on the positive electrode side output line L1 on the auxiliary battery BL side of the connection point between the switching element SW5 and the switching element SW6, and the positive electrode side is arranged between the reactor L and the auxiliary battery BL. A smoothing capacitor C is connected between the output line L1 and the negative output line L2.

As a result, when the primary current flowing through the primary coil T1 is energized, the auxiliary battery BL is charged through the reactor L and the smoothing capacitor C. As shown in FIG. Further, when the primary current flowing through the primary coil T1 is interrupted, the energy accumulated in the reactor L due to the energization of the primary current flowing through the primary coil T1 is released via the smoothing capacitor C to the auxiliary battery BL. At this time, by appropriately setting the turn ratio of the primary coil T1 and the secondary coil T2, the high voltage (for example, 288 V) of the high-voltage battery BH is stepped down to a voltage suitable for the on-vehicle auxiliary equipment. Charge the battery BL (eg, 14V).

As shown in FIG. 4, the filter circuit 4 is configured as a common mode noise filter and has a common mode coil 43 and common mode capacitors 41 and 42 arranged at both ends thereof. The common mode coil 43 has a configuration in which two coils respectively inserted in the positive line Lp and the negative line Ln are wound around a core (not shown). Eliminate modal noise.

The common mode capacitors 41 and 42 are each composed of a plurality of capacitors 41a and 42a connected in series. connected to The common mode capacitors 41 and 42 each have an intermediate point of the series connection connected to the housing ground portion GND3 via a ground line 44, and suppresses common mode noise entering the positive line Lp or the negative line Ln from the board support portion. 11 can be bypassed and escaped to the housing 10 side (see FIG. 1, for example).
Note that the number of the plurality of capacitors 41a and 42a forming the common mode capacitors 41 and 42 can be set arbitrarily.

As shown in FIGS. 5 and 6, the housing 10 is in the shape of a flat rectangular container. Become. Inside the housing 10, a sealed housing space is formed in which device components are housed. In this accommodation space, a circuit board 5 is arranged so as to partition between the bottom wall 10A and the top wall 10C, and wiring patterns constituting the power conversion circuit unit 2, the control circuit unit 3, and the filter circuit 4 are arranged. is formed, and electronic components (not shown) that constitute a circuit are mounted.

In FIG. 5, the housing 10 has a substantially rectangular outer shape, and a high-voltage cable 13 connected to an external high-voltage battery BH (not shown) is attached to a short side wall 10B. Inside the housing 10, the high-voltage cable 13 is connected to the filter circuit 4 via a terminal block or the like (not shown). , supplies high-voltage DC power to the power conversion circuit unit 2 .

External connection terminals 6 are installed near corners on the side of the high-voltage cable 13 on side walls 10B, which are the long sides of the housing 10, and signal cables 14 connected to an external ECU (not shown) are attached. The signal line Ls extending from the external connection terminal 6 into the housing 10 is configured as, for example, a signal wire harness, and a signal connector 33 as a connector arranged at the extending end of the signal line Ls is connected to the external connection circuit 31. It transmits signals input/output to/from the main control circuit 32 .

The external connection circuit 31 can be arranged between the external connection terminal 6 and the main control circuit 32 and configured as a signal processing circuit for processing signals input from the outside through the signal connector 33 . The signal processing circuit can be configured to include, for example, a filter circuit for surge absorption, absorbs the surge voltage superimposed on the signal line Ls via the external connection terminal 6, and suppresses voltage fluctuations due to the surge voltage. Input to the control circuit 32 is prevented.

In addition, the main control circuit 32 can include, for example, a CPU that performs arithmetic processing, a microcomputer that has a memory that stores programs, a control power supply circuit, and the like. A control signal for driving the switching elements SW1 to SW6 of the section 2 is generated.

On the circuit board 5, the external connection circuit 31 and the main control circuit 32 of the control circuit section 3 are arranged near the side wall 10B on the long side to which the signal cable 14 is attached, and the short side to which the high voltage cable 13 is attached. A mounting region R1 for the external connection circuit 31 is provided at a corner portion near the side wall 10B. A region along the side wall 10B on the long side away from the corner becomes a mounting region R2 for the main control circuit 32, and a region adjacent to the external connection circuit 31 on the side wall 10B on the short side is a mounting region for the filter circuit 4. It has become R3. In the extension direction of the high voltage cable 13, the primary side or secondary side circuit section 21 (see FIG. 1, for example) of the power conversion circuit section 2 is arranged in a region following the mounting region R3.

Arranging the external connection circuit 31 and the signal connector 33 in the vicinity of the external connection terminal 6 in this manner is advantageous in terms of miniaturization of the device, and shortens the signal line Ls so that the signal line Ls is superimposed on the signal line Ls. radiated noise can be reduced.
At this time, the signal connector 33 of the external connection circuit 31 is mounted on the surface 51 of the circuit board 5 on the side of the top wall 10C, and the external connection circuit 31 is mainly mounted on the surface 52 of the circuit board 5 on the side of the bottom wall 10A. A region R1. The main control circuit 32 and the filter circuit 4 of the control circuit section 3 are arranged on the surface 51 of the circuit board 5 on the side of the top wall 10C.

In FIG. 6, the circuit board 5 is arranged in parallel with the bottom wall 10A of the housing 10, and is supported and fixed by fastening bolts 7 to a plurality of board supports 11 projecting from the bottom wall 10A. The substrate supporting portion 11 is provided integrally with the bottom wall 10A and can be a columnar body or a block body extending in the plate thickness direction X toward the top wall 10C. Here, for example, it has a cylindrical shape having a mounting hole 71 opening toward the top wall 10C side, and a threaded portion is formed on the inner periphery of the mounting hole 71 . As a result, the circuit board 5 is placed on the board support portion 11, and the fastening bolts 7 inserted into the mounting holes 71 through the through holes TH provided at positions facing the mounting holes 71 are screwed together. 5 can be fixed to the housing 10 .

Note that part of the circuit components may be housed in the space between the circuit board 5 and the bottom wall 10A. is placed on the bottom wall 10A. The switching module SM is connected to the primary-side or secondary-side circuit unit 21 of the power conversion circuit unit 2 arranged on the circuit board 5 by a wiring module or the like (not shown) (see FIG. 1, for example).

The housing 10 is made of metal such as aluminum or an aluminum alloy, and is in electrical contact with a vehicle body (not shown) to have a ground potential. The plurality of substrate support portions 11 are provided integrally with the bottom wall 10A, have the same potential as the housing 10, and function as a housing ground portion GND by being connected to the ground pattern GP of the circuit. . In FIG. 5, the substrate supporting portion 11 which becomes a housing ground portion GND1 corresponding to the external connection circuit 31, a housing ground portion GND2 corresponding to the main control circuit 32, and a housing ground portion GND3 corresponding to the filter circuit 4 is shown. An arrangement example is shown, and they are arranged in the mounting regions R1 to R3 of the corresponding circuits.

In this manner, at least one housing ground portion GND (for example, GND1 to GND3) is provided for each circuit mounting region R1 to R3 mounted on the circuit board 5, and is individually connected to each circuit. be done. Further, at least one of the plurality of housing ground portions GND1 and GND2 corresponding to the control circuit section 3 is configured to serve as a common housing ground portion GND. The housing ground parts GND1 to GND3 are arranged close to the side wall 10B, for example.
It should be noted that the illustrated arrangement of the housing ground parts GND1 to GND3 is an example, and can be changed as appropriate. In addition, the board supporting portion 11 can be provided at any position other than the position shown in the drawing, corresponding to the circuit configuration, arrangement, etc. of the circuit board 5 .

7, the external connection circuit 31 is mainly mounted on the lower surface 52 of the circuit board 5, and the main control circuit 32 mounted on the upper surface 51 of the circuit board 5. , and the mounting regions R1 and R2 partially overlap each other in the thickness direction X of the circuit board 5, thus forming an overlapping region R. As shown in FIG. At this time, the housing ground part GND1 of the external connection circuit 31 arranged in the overlap region R or arranged close thereto is further connected to both the ground pattern GP1 of the external connection circuit 31 and the ground pattern GP2 of the main control circuit 32, It is desirable to function as a low-impedance common housing ground portion GND1.

The surface 52 of the circuit board 5 on which the external connection circuit 31 is mounted is arranged in contact with the housing ground plane 12, which is the projecting end surface of the housing ground portions GND1 and GND2. At this time, the ground pattern GP1 of the external connection circuit 31 is directly connected to the housing ground plane 12 of the housing ground portion GND1. On the other hand, the surface 51 on which the main control circuit 32 is mounted faces the housing ground surface 12 with the insulating layer 5A serving as the base of the circuit board 5 interposed therebetween. The ground pattern GP2 of the main control circuit 32 is directly connected to the housing ground plane 12 through the connection conductor portion M arranged through the insulating layer 5A, or is grounded on the housing ground plane 12. It can be electrically connected to the housing ground plane 12 via the pattern GP1.

As shown in the lower diagram of FIG. 7, even in a configuration in which the housing ground portion GND1 is not shared, the ground patterns GP1 and GP2 are separated on the circuit board 5 and individually connected to the housing ground portions GND1 and GND2, respectively. This suppresses the mutual influence of voltage fluctuations. For example, it is possible to suppress direct transmission to the main control circuit 32 of voltage fluctuations in the external connection circuit 31 to which the signal line Ls is connected, with respect to surges applied from the outside. However, when the high-frequency common mode noise generated with the switching operation of the power conversion circuit unit 2 is superimposed on the main control circuit 32 and transmitted to the overlap region R near the signal connector 33, the ground pattern GP2 Common mode noise is transmitted to the signal line Ls and easily leaks to the outside.

As shown in FIG. 8, when power conversion is performed in the power conversion circuit unit 2 with high-voltage power input from the high-voltage cable 13 (the current path is indicated by a solid arrow a), the common mode associated with switching operation etc. Noise occurs. In that case, normally, a filter circuit 4 having common mode capacitors 41 and 42 is installed between the high-voltage cable 13 and the power conversion circuit unit 2 (for example, see FIG. 1), so that the case ground unit GND3 recovered from. However, when high-frequency common mode noise is superimposed on the control circuit unit 3 arranged near the circuit unit 21 of the power conversion circuit unit 2 on the circuit board 5, the signal line Ls from the circuit board 5 to the outside (dotted line arrow b).

In order to absorb a surge voltage superimposed on the external connection terminal 6 for signal transmission in the configuration of the control circuit section 3, the external connection circuit 31 having a filter circuit is arranged in the immediate vicinity of the connector 33, It is connected to the body ground portion GND1. This configuration is configured to avoid connection with the housing ground section GND2 so that the voltage fluctuation does not go to the main control circuit 32. FIG. In that case, when the above-mentioned common mode noise is superimposed on the main control circuit 32 , it is transmitted to the overlapping region R near the connector 33 through the ground pattern GP2. Furthermore, it is easy to flow outside from the external connection terminal 6 through the signal line Ls connected to the external connection circuit 31 via the stray capacitance (dotted line arrow c).

Therefore, in this embodiment, as shown in FIG. 9, a common housing ground portion GND1 is provided in the vicinity of the overlapping region R that is closest to the external connection terminal 6, and both the ground pattern GP2 and the ground pattern GP1 are connected. . As a result, the common mode noise transmitted to the overlap region R can be absorbed from the common housing ground portion GND1 (dotted line arrow d). The absorbed common mode noise is collected from the housing ground section GND3 in the same manner as the common mode noise that returns from the housing 10 on the power conversion circuit section 2 side to the housing ground section GND3 (solid line arrow e).
In this way, the common mode noise superimposed on the control circuit section 3 can be absorbed into the housing 10 also from the housing ground section GND1, and can be suppressed from flowing out to the outside.

Further, the ground pattern GP2 of the main control circuit 32 and the ground pattern GP1 of the external connection circuit 31 are configured so that only the pattern portion of the bottom layer of the substrate that contacts the housing ground surface 12 of the housing ground portion GND1 is common. (see, eg, FIG. 2), the common impedance can be reduced. At this time, even if voltage fluctuation due to the surge voltage occurs in the ground pattern GP1, it can be absorbed by the housing 10 without being transmitted to the ground pattern GP2.

In this way, when connecting the ground pattern GP2 of the main control circuit 32 and the ground pattern GP1 of the external connection circuit 31 to the common case ground portion GND1, the connection path should be made as short as possible, and the connecting portion should be connected to the case. It is desirable to have a connection structure in which the common impedance of the path leading to the housing 10 via the body ground portion GND1 is as small as possible.

The connection structure to the housing ground portion GND1 can be appropriately set according to the configuration of the circuit board 5, the support structure to the substrate support portion 11, and the like.
For example, the connection position between the ground pattern GP1 positioned on the bottom layer of the substrate and the ground pattern GP2 via the connection conductor portion M does not necessarily have to be within the plane of the housing ground plane 12 . That is, it is also possible to adopt a configuration in which the connection conductor portion M is connected to the ground pattern GP1 outside the outer diameter of the housing ground portion GND1. In that case, for example, the connection position should be on the housing ground part GND1 side of half the distance between the housing ground part GND1 and the housing ground part GND2.

Specifically, as shown in the upper diagram of FIG. 10, when the circuit board 5 is a double-sided board, the ground pattern of the external connection circuit 31 is formed by the conductive layers 5B formed on both sides of the insulating layer 5A. GP1 and a ground pattern GP2 of the main control circuit 32 are formed. A through-hole TH is formed in the circuit board 5 at a position corresponding to the housing ground portion GND1, and a cylindrical conductor M1, which serves as a connection conductor portion M, is fitted to the inner peripheral side of the through-hole TH. . The tubular conductor M1 has a tubular portion along the inner peripheral surface of the through hole TH and flange portions M2 projecting outward from the outer peripheral edges of both ends of the through hole TH. They are connected to ground patterns GP1 and GP2, respectively.

A fastening bolt 7 (see, for example, FIG. 6) is inserted into the mounting hole 1 of the housing ground portion GND1 that is continuous with the through hole TH, and the circuit board 5 is fixed to the housing ground plane 12 . At this time, the ground pattern GP1 is directly connected to the housing ground plane 12 of the housing ground section GND1 via the flange section M2 on the surface 52 side of the circuit board 5, or as shown in the figure. On the other hand, the ground pattern GP2 is connected to the housing ground plane 12 of the housing ground section GND1 via the flange section M2 and the tubular section M1 on the surface 51 side of the circuit board 5 . By connecting the ground patterns GP1 and GP2 to the housing ground plane 12 in this way, the effect of reducing the common impedance can be obtained.

Further, as shown in the lower diagram of FIG. 10, the circuit board 5 may be a multi-layer board, for example, a configuration in which conductive layers 5B and insulating layers 5A are alternately arranged on both sides of an insulating layer 5A serving as a core. have In that case, for example, on the surface 51 or 52, which is the outermost surface, the flange portion M2 of the cylindrical conductor M1, which is the connection conductor portion M, and the ground patterns GP1 and GP2 are connected to each other. be able to.

At this time, it is not necessary to use the bottom layer of the multilayer board on the side of the housing ground part GND1 as the connection part. It may be configured to be connected to the flange portion M21 located in the inner layer. Also in this case, it is desirable that the path connected to the housing ground plane 12 via the cylindrical conductor M1 has a configuration in which the common impedance portion is as small as possible. Preferably, the number of common layers is half or less. For example, in the case of a four-layer board, two layers or less on the housing ground plane 12 side are used, and in the case of a six-layer board, the number of layers is three or less. A similar effect can be obtained by being connected.

As described above, according to the configuration of this embodiment, the filter circuit 4 and the power conversion circuit unit 2 to which high-voltage power is input, and the control circuit unit 3 to which signals are input are mixed on the circuit board 5. Also in the configuration, the common mode noise superimposed on the control circuit section 3 can be absorbed into the housing 10 from the common housing ground section GND1. Therefore, it is possible to suppress the common mode noise from leaking out from the signal line Ls without changing the layout of the circuit board 5, the device configuration, or increasing the number of components.

(Embodiment 2)
A second embodiment of the power converter will be described with reference to FIG. 11 .
In the first embodiment, each of the plurality of substrate support portions 11 is formed in a columnar shape having the mounting hole 71, but may be formed in a different shape. For example, at least the substrate supporting portion 11, which is the common housing ground portion GND1, may be shaped like a prism or a block, and the housing ground surface 12 may be made larger.
Note that, of the reference numerals used in the second and subsequent embodiments, the same reference numerals as those used in the previous embodiments represent the same components as those in the previous embodiments, unless otherwise specified.

In Embodiment 2 shown in FIG. 11, the common housing ground portion GND1 is configured by a rectangular parallelepiped block, and a mounting hole 71 (not shown) into which the fastening bolt 7 is screwed into one of the corners thereof. are placed. The positions of the fastening bolts 7 and the mounting holes 71 can be the same as in the first embodiment (for example, see FIG. 6), and the housing ground plane 12 extends from the fastening bolts 7 to the signal connector 33 side. The signal connector 33 is supported on the ground plane 12 of the housing.

As a result, in the common housing ground portion GND1, the area of the housing ground surface 12 is larger than that of the other cylindrical housing ground portions GND. The ground pattern GP1 located at the bottom layer of the circuit board 5 is arranged, for example, so as to extend from the side of the fastening bolt 7 to the side of the side wall 10B while covering the lower side of the signal connector 33. The contact area is also large. The shape and arrangement of the housing ground parts GND other than the common housing ground part GND1, and the circuit configuration and arrangement mounted on the circuit board 5 can be the same as in the above-described embodiment, and the description thereof will be omitted.

According to the configuration of this embodiment, since the common case ground portion GND1 has the case ground surface 12 with a large area, the impedance of the path of common mode noise flowing from the circuit board 5 to the case 10 can be reduced. can. In addition, since the housing ground plane 12 is arranged close to the path of the common mode noise flowing out from the signal connector 33, the common mode noise flows into the housing 10 via the stray capacitance, thereby suppressing the common mode noise. Further reduction is possible. Therefore, it is possible to enhance the effect of suppressing common mode noise from leaking out from the signal connector 33 via the signal line Ls.

At this time, as shown as a modified example in FIG. 12, the ground pattern GP1 in contact with the common housing ground portion GND1 is arranged on the housing ground surface 12 around the fastening bolt 7, and extends to the lower surface side of the signal connector 33. It may be a configuration in which it is not formed to extend. Even in this case, since the lower surface of the signal connector 33 faces the housing ground surface 12, common mode noise can flow through the stray capacitance.

(Embodiment 3)
A third embodiment of the power converter will be described with reference to FIG. 13 .
In the present embodiment, as in the second embodiment, the substrate supporting portion 11, which serves as the common housing ground portion GND1, is configured by a rectangular parallelepiped block, and extends from the signal connector 33 to the lower side of the signal line Ls. Furthermore, it is configured to be connected to the side wall 10B in the extension direction. At this time, it is connected not only to the side wall 10B on the long side to which the signal line Ls is connected, but also to the side wall 10B on the short side following it, and integrally with the corners formed by these side walls 10B, a common casing is formed. A body ground portion GND1 can be arranged. The housing ground plane 12 has a rectangular parallelepiped shape covering the entire lower surface of the signal connector 33 and the signal line Ls, and the signal connector 33 and the signal line Ls are supported on this housing ground plane 12 .

According to the configuration of this embodiment, the housing ground plane 12 has a larger area and covers the entire lower surface of the signal connector 33 and the signal line Ls, so that the impedance of the housing 10 is further reduced. In addition, by being close to the path of common mode noise flowing out from the signal connector 33 to the signal line Ls, common mode noise can easily flow from the signal line Ls to the housing 10 . Further, since the common casing ground portion GND1 is provided integrally with the side wall 10B, the space between the common casing ground portion GND1 and the side wall 10B is reduced, so that the common mode radiated into the space The effect from noise is also reduced.
As a result, the common mode noise can be further reduced, and the effect of suppressing the outflow from the signal line Ls to the outside can be enhanced.

The present invention is not limited to the above embodiments, and can be applied to various embodiments without departing from the scope of the invention.
For example, the circuit configurations of the power conversion circuit unit 2, the control circuit unit 3, and the filter circuit 4 of the power conversion device 1 are not limited to those described above, and can be changed as appropriate. The same applies to the shape of the housing and circuit board, and other device configurations.
Further, the power conversion device 1 is not limited to a step-down DC-DC converter, but can also be applied to an inverter that converts DC power into AC power, a boost converter that boosts DC power and supplies it to an inverter, and the like. Furthermore, the power conversion device 1 is not limited to vehicles such as electric vehicles and hybrid vehicles, and can be used for any purpose.

Reference Signs List 1 power conversion device 10 housing 11 substrate support 12 housing ground plane 2 power conversion circuit section 3 control circuit section 4 filter circuit 5 circuit board GP ground pattern GND1 to GND3 housing ground section

Claims (8)

At least part of a power conversion circuit unit (2) connected to power lines (Lp, Ln) and power of the power conversion circuit unit are connected to a circuit board (5) housed in a metal housing (10). A power converter (1) equipped with a control circuit (3) for controlling conversion operation and a filter circuit (4) including capacitors (41, 42) electrically connected to the housing,
The circuit board having a single-layer or multi-layer structure is supported by a plurality of board supports (11) integrally formed with the housing,
The control circuit unit includes a plurality of circuits (31, 32) formed on different surfaces of the circuit board, a plurality of ground patterns (GP1, GP2) corresponding to the plurality of circuits, and a plurality of housing grounds. has a part (GND1, GND2),
the plurality of ground patterns are located on different surfaces or different layers of the circuit board;
The plurality of housing ground portions, each of which also serves as the substrate support portion, is provided with at least one for each of the plurality of circuits, and is electrically connected to the ground pattern corresponding to each circuit, and,
At least one of the housing ground portions is configured as a housing ground portion (GND1) common to a plurality of the ground patterns, and each ground pattern has a housing ground plane (12) of the common housing ground portion. ) or individually connected to the connection conductor (M) electrically connected to the housing ground plane without coming into contact with the other ground pattern outside the housing ground plane or the connection conductor. power converter. The control circuit section has a plurality of circuits arranged on different surfaces (51, 52) of the circuit board, and a plurality of circuit forming regions (R1, R2) in the board thickness direction (X) of the circuit board. ) has an overlapping region (R) that overlaps with a part of the insulating layer (5A) via the insulating layer (5A), and the common housing ground portion is arranged in or near the overlapping region. , The power conversion device according to claim 1 . In the plate thickness direction, the plurality of ground patterns are positioned to face each other with the insulating layer interposed therebetween, and are connected directly to the housing ground surface or via the connection conductor embedded in the insulating layer. 3. The power conversion device according to claim 2. The substrate supporting portion is a columnar body or a block that protrudes from the first wall portion (10A) of the housing parallel to the circuit board and has the housing ground surface on the projecting end side, and the housing ground surface. 4. The power conversion device according to claim 1, wherein the plurality of ground patterns are electrically connected to the housing ground plane by placing the circuit board on. The power conversion circuit unit includes a plurality of switching elements (SW1 to SW6) connected to the power line or output line (L1, L2),
The control circuit section includes, as the plurality of circuits, an external connection circuit (31) connected to an external connection terminal (6) for signal transmission, and a main control circuit (32) for generating a control signal for the switching element. and
The external connection circuit is arranged in the vicinity of the second wall (10B) of the housing to which the external connection terminal is attached, and the common housing ground section is located closer to the housing ground section than the other housing ground sections. 5 . The power conversion device according to claim 4 , wherein is also located near the second wall. 6. The power converter according to claim 5, wherein the common housing ground portion has a larger area of the housing ground plane than other housing ground portions. The external connection circuit is connected to the external connection terminal via a connector (33),
7. The power converter according to claim 6, wherein said connector is supported on said housing ground surface of said common housing ground portion. The external connection circuit is connected to the external connection terminal via a connector (33) and a signal line (Ls), and the common housing ground portion is integrated with the first wall portion and the second wall portion. is provided in
7. The power conversion device according to claim 6, wherein said connector and said signal line are supported on said housing ground plane of said common housing ground section.

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