JP2022179859A - discharge device - Google Patents

Abstract

A discharge device for discharging a smoothing capacitor mounted in a motor driving device is miniaturized.
A discharge device (23) includes a plurality of electronic components connected to each other and discharges electric charges in a smoothing capacitor (21a) installed in a power conversion device (1) of a motor (M), the wiring substrate having an upper surface and a lower surface. , an electronic component mounted on the upper surface of the wiring board, and an electronic component mounted on the lower surface of the wiring board.
[Selection drawing] Fig. 2

Description

The present invention relates to a discharge device.

2. Description of the Related Art An electric vehicle such as an electric vehicle or a hybrid vehicle is equipped with a drive device for driving a motor. For example, Patent Literature 1 discloses a discharging device that discharges electric charges from a smoothing capacitor provided in a driving device. The discharge device disclosed in Patent Document 1 includes a plurality of discharge circuit transistors connected in parallel to a smoothing capacitor. When the discharge circuit transistors are turned on, the smoothing capacitor is discharged.

JP 2018-160954 A

Incidentally, the discharge device disclosed in Patent Document 1 is provided with a plurality of electronic components such as a current adjusting transistor for adjusting the amount of current flowing through the discharge circuit transistor, in addition to the discharge circuit transistor. These electronic components are mounted on the board. However, in Patent Document 1, all electronic components including the discharge circuit transistor and the current adjustment transistor are mounted on one side of the substrate. For this reason, it is necessary to ensure a large mounting space for electronic components on one side of the substrate, resulting in an increase in the size of the discharge device.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the size of a discharging device for discharging a smoothing capacitor mounted on a motor driving device.

The present invention employs the following configurations as means for solving the above problems.

A first aspect is a discharge device comprising a plurality of interconnected electronic components and for discharging a smoothing capacitor installed in a motor driving device, comprising a first surface and a back side of the first surface. a wiring board having a second surface positioned on the second surface of the wiring board; the electronic component mounted on the first surface of the wiring board; and the electronic component mounted on the second surface of the wiring board. adopt.

In a second aspect, in the first aspect, the electronic components include a discharging switching element connected in parallel to the smoothing capacitor, and a current adjusting switching element for adjusting the amount of current flowing through the discharging switching element. are provided, and a plurality of set circuits including the discharge switching element and the current adjustment switching element are connected in series.

A third aspect is the above-described second aspect, wherein as the above-described grouped circuits, a first grouped circuit, a second grouped circuit, a third grouped circuit, and a fourth grouped circuit are connected in order. , the electronic component included in the second assembled circuit and the electronic component included in the third assembled circuit are mounted on the first surface of the wiring board, and the electronic component included in the first assembled circuit; A configuration is adopted in which the electronic component included in the fourth set circuit is mounted on the second surface of the wiring board.

A fourth aspect is the second or third aspect, wherein the wiring board has a heat dissipation pad provided for each of the discharge switching elements and receives heat from the discharge switching elements, and the first surface and the heat dissipation pads provided on the second surface do not at least partially overlap each other in a projected view along the normal direction of the first surface and the second surface. Adopt a configuration that is arranged in.

A fifth aspect adopts a configuration in which, in any one of the first to fourth aspects, the wiring board is provided with a gate driver connected to an inverter that converts power supplied to the motor. .

According to the present invention, the electronic components of the discharge device are mounted on both the first surface and the second surface of the wiring board. Therefore, even if the wiring board is small, it is possible to secure a mounting area for electronic components. Therefore, according to the present invention, it is possible to reduce the size of the discharging device that discharges the electric charge of the smoothing capacitor mounted on the motor driving device.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view schematically showing a schematic configuration of a power converter provided with a discharge device according to one embodiment of the present invention; 1 is a circuit diagram that schematically shows a schematic configuration of a power conversion device that includes a discharge device according to an embodiment of the present invention; FIG. 1 is an enlarged view of a discharge device in one embodiment of the present invention; FIG. (a) is a schematic diagram enlarging a part of the upper surface of the wiring board, and (b) is a schematic diagram enlarging a part of the lower surface of the wiring board. 1 is a schematic perspective view of a wiring substrate included in a discharge device according to one embodiment of the present invention; FIG.

An embodiment of a discharge device according to the present invention will be described below with reference to the drawings.

FIG. 1 is an exploded perspective view showing a schematic configuration of a power conversion device 1 (drive device) including a discharge device 23 of this embodiment. The power conversion device 1 is mounted on a vehicle such as an electric vehicle, and is provided between a motor (load) (not shown) and a battery. Such a power conversion device 1 includes an intelligent power module 2, a capacitor 3, a reactor 4, a DCDC converter 5, and a body case 6, as shown in FIG.

The intelligent power module 2 includes a power module 10, a gate driver board 11, an ECU board 12, and the like. The power module 10 includes a plurality of power devices 10a having power semiconductor elements, a resin power module case 10b housing the power devices 10a, and a bus bar 10c connected to the power devices 10a. In addition, the power module 10 includes an insulating resin member that prevents a short circuit of the bus bar 10c, a water jacket for cooling, and the like.

The gate driver substrate 11 is a substrate provided with a gate driver for generating drive signals for the step-up/step-down converter and inverter formed by the power device 10a. In this embodiment, a discharge device 23 is formed on the gate driver substrate 11 . This discharge device 23 will be described later in detail. Such a gate driver substrate 11 is laminated on the power module 10 . The ECU board 12 is a board provided with an ECU (Electronic Control Unit) for controlling the gate driver board 11 . The ECU board 12 is laminated on the gate driver board 11 .

The capacitor 3 is connected to the intelligent power module 2 and arranged on the side of the power module 10 . The reactor 4 is arranged below the intelligent power module 2 . The DCDC converter 5 is arranged on the side of the reactor 4 and below the intelligent power module 2 . Note that the DCDC converter 5 converts the battery power into a voltage suitable for surrounding electronic components (such as electronic components mounted on the gate driver board 11 and the ECU board 12).

The body case 6 is a case that houses the intelligent power module 2, the capacitor 3, the reactor 4, and the DCDC converter 5, and includes an upper case 6a, a central case 6b, and a lower case 6c. These upper case 6a, center case 6b and lower case 6c are connected to the power module 10, the gate driver board 11 and the ECU board 12 so as to be separable in the stacking direction. The upper case 6a covers the intelligent power module 2 from the side of the ECU board 12 and is fastened to the central case 6b. The central case 6 b surrounds the intelligent power module 2 , capacitor 3 , reactor 4 and DCDC converter 5 . The lower case 6c covers the reactor 4 and the DCDC converter 5 from below, is provided with a connector for connecting the intelligent power module 2 and the motor M (see FIG. 2), and is fastened to the central case 6b. .

FIG. 2 is a circuit diagram schematically showing the schematic configuration of the power converter 1. As shown in FIG. As shown in this figure, the power converter 1 includes a converter 20, a gate driver 30, and an ECU 40. FIG. As shown in FIG. 2, the converter 20 is arranged between the battery P and the motor M, and performs power conversion between the battery P and the motor M. As shown in FIG. This converter 20 comprises a step-up/step-down converter 21 , an inverter 22 and a discharge device 23 .

The step-up/step-down converter 21 steps up the DC voltage output from the battery P at a predetermined step-up ratio. Further, the step-up/step-down converter 21 steps down the DC voltage output from the inverter 22 at a predetermined step-down ratio. Such a step-up/step-down converter 21 includes, for example, a smoothing capacitor 21a, a transformer 21b, and a plurality of transforming IGBTs (Insulated Gate Bipolar Transistors) 21c, as shown in FIG.

In this embodiment, the smoothing capacitor 21a is formed by the capacitor 3 shown in FIG. Moreover, in this embodiment, the transformer 21b is formed by the reactor 4 shown in FIG. Further, in the present embodiment, the transformer IGBT 21c is formed by the power device 10a shown in FIG.

Such a step-up/step-down converter 21 is a power circuit called a so-called magnetically coupled interleaved chopper circuit. The step-up/step-down converter 21 steps up the DC power input from the battery P via a pair of battery terminals and outputs the power to the inverter 22, and steps down the DC power input from the inverter 22 to output the power to the pair of batteries. Alternatively, the step-down operation of outputting to the battery P via the terminal for voltage reduction is performed. That is, the step-up/step-down converter 21 is a power conversion circuit that bidirectionally inputs and outputs DC power between the battery P and the inverter 22 .

The inverter 22 converts DC power output from the battery P into AC power based on a PWM (Pulse Width Modulation) signal from the gate driver 30 and supplies the AC power to the motor M. The inverter 22 also converts the AC power output from the motor M into DC power based on the PWM signal from the gate driver 30 and supplies the DC power to the step-up/step-down converter 21 . Such an inverter 22, as shown in FIG. 2, has three switching legs and a total of six driving IGBTs 22a. In this embodiment, the driving IGBT 22a is formed by the power device 10a shown in FIG.

Such an inverter 22 has three (a plurality of) switching legs corresponding to the number of phases of the motor M. As shown in FIG. This inverter 22 is a power conversion circuit that alternatively performs a power running operation and a regenerative operation. That is, the inverter 22 converts the DC power input from the step-up/step-down converter 21 into three-phase AC power, and outputs it to the motor M through the three motor terminals. Alternatively, a regenerative operation in which the three-phase AC power input from the motor M is converted into DC power and output to the step-up/step-down converter 21 is performed. That is, the inverter 22 is a power circuit that mutually converts DC power and three-phase AC power between the step-up/step-down converter 21 and the motor M.

The discharging device 23 is a circuit connected in parallel with the smoothing capacitor 21a, and discharges the electric charge of the smoothing capacitor 21a, for example, when the power conversion device 1 is stopped. FIG. 3 is an enlarged circuit diagram of the discharge device 23. As shown in FIG. As shown in FIG. 3 , the discharge device 23 includes a discharge circuit 24 and a current adjustment circuit 25 . These discharging circuit 24 and current adjusting circuit 25 are connected in parallel to the smoothing capacitor 21a. That is, each of the discharging circuit 24 and the current adjusting circuit 25 has one end connected to the positive terminal of the smoothing capacitor 21a and the other end connected to the negative terminal of the smoothing capacitor 21a.

The discharge circuit 24 is a circuit in which a discharge resistor 24a and a discharge transistor 24b (electronic component, discharge switching element) are alternately connected in series. In this embodiment, the discharging circuit 24 includes five discharging resistors 24a and four discharging transistors 24b (first discharging transistor 24c, second discharging transistor 24d, third discharging transistor 24e and fourth discharging transistor 24e). transistor 24f).

The first discharging transistor 24c, the second discharging transistor 24d, the third discharging transistor 24e, and the fourth discharging transistor 24f are arranged in order from the positive terminal side of the smoothing capacitor 21a. These first discharging transistor 24c, second discharging transistor 24d, third discharging transistor 24e and fourth discharging transistor 24f are, for example, bipolar transistors. Also, the discharging resistor 24a is connected to the collector terminal and the emitter terminal of the discharging transistor 24b. Such a discharging circuit 24 constantly discharges electric charges to the smoothing capacitor 21a.

The current adjusting circuit 25 is a circuit in which a current adjusting resistor 25a and a current adjusting transistor 25b (electronic component, current adjusting switching element) are alternately connected in series. In this embodiment, the current adjusting circuit 25 includes four current adjusting resistors 25a and four current adjusting transistors 25b (a first current adjusting transistor 25c, a second current adjusting transistor 25d, and a third current adjusting transistor 25d). 25e and a fourth current regulating transistor 25f).

The first current adjusting transistor 25c, the second current adjusting transistor 25d, the third current adjusting transistor 25e, and the fourth current adjusting transistor 25f are arranged in order from the positive terminal side of the smoothing capacitor 21a. These first current adjusting transistor 25c, second current adjusting transistor 25d, third current adjusting transistor 25e and fourth current adjusting transistor 25f are, for example, bipolar transistors. The current adjusting resistor 25a is connected to the collector terminal of each current adjusting transistor 25b. A plurality of current adjusting resistors 25a may be connected in series to the collector terminal of each current adjusting transistor 25b.

A base terminal of the discharging transistor 24b is connected between the current adjusting resistor 25a and the current adjusting transistor 25b. The base terminal of the current adjusting transistor 25b is connected between the emitter terminal of the discharging transistor 24b and the discharging transistor 24b. Such a current adjusting circuit 25 adjusts the amount of current flowing through each discharging transistor 24b.

One current adjusting transistor 25b is provided for one discharging transistor 24b. That is, in the discharge device 23 of this embodiment, four combined circuits 26 each including one discharge transistor 24b and one current adjustment transistor 25b are provided. That is, as shown in FIG. 3, the discharge device 23 of this embodiment has four combined circuits 26 connected in series.

The combined circuit 26 including the first discharging transistor 24c and the first current adjusting transistor 25c is referred to as a first combined circuit 26a. Also, the combined circuit 26 including the second discharging transistor 24d and the second current adjusting transistor 25d is referred to as a second combined circuit 26b. The combined circuit 26 including the third discharging transistor 24e and the third current adjusting transistor 25e is called a third combined circuit 26c. A combined circuit 26 including the fourth discharging transistor 24f and the fourth current adjusting transistor 25f is called a fourth combined circuit 26d.

FIG. 4A is a schematic diagram showing an enlarged part of the upper surface 11b of the wiring substrate 11a included in the gate driver substrate 11. FIG. Also, FIG. 4B is a schematic diagram showing an enlarged part of the lower surface 11c of the wiring substrate 11a included in the gate driver substrate 11. As shown in FIG. As shown in these figures, the gate driver board 11 includes a wiring board 11a on which wiring is provided. A discharge resistor 24a, a discharge transistor 24b, a current adjustment resistor 25a, and a current adjustment transistor 25b of the discharge device 23 are mounted on the wiring board 11a. The discharge resistor 24a, the discharge transistor 24b, the current adjustment resistor 25a, and the current adjustment transistor 25b are electrically connected to each other through the wiring layer of the wiring substrate 11a. Thus, the wiring board 11a also functions as part of the discharge device 23. As shown in FIG. That is, the discharge device 23 of this embodiment includes a wiring board 11a and electronic components (discharge resistor 24a, discharge transistor 24b, current adjustment resistor 25a, and current adjustment transistor 25b).

The wiring board 11a is a thin plate-shaped board having an upper surface 11b (first surface) and a lower surface 11c (second surface) facing the upper surface 11b. In this embodiment, the wiring board 11a is provided with the gate driver 30 connected to the inverter 22 for converting the power supplied to the motor M as described above.

As shown in FIG. 4A, a second discharging transistor 24d and a second current adjusting transistor 25d are arranged adjacent to each other on the upper surface 11b of the wiring board 11a. A third discharge transistor 24e and a third current adjustment transistor 25e are arranged adjacent to each other on the upper surface 11b of the wiring board 11a. That is, in this embodiment, the second combined circuit 26b and the third combined circuit 26c are mounted on the upper surface 11b of the wiring board 11a.

Further, as shown in FIG. 4B, a first discharge transistor 24c and a first current adjustment transistor 25c are arranged adjacent to each other on the lower surface 11c of the wiring board 11a. A fourth discharging transistor 24f and a fourth current adjusting transistor 25f are arranged adjacent to each other on the lower surface 11c of the wiring substrate 11a. That is, in the present embodiment, the first grouped circuit 26a and the fourth grouped circuit 26d are mounted on the lower surface 11c of the wiring substrate 11a.

As shown in FIGS. 1(a) and 4(b), the first circuit set 26a, the second circuit set 26b, the third circuit set 26c, and the fourth circuit set 26d extend across the width (short side) of the wiring board 11a, as shown in FIGS. are arranged substantially linearly in the direction (width direction) along the . In this arrangement direction, the first circuit set 26a, the second circuit set 26b, the third circuit set 26c and the fourth circuit set 26d are arranged starting from the first circuit set, then the second circuit set 26b, the fourth circuit set 26d, and the second circuit set 26b. The grouped circuit 26d and the third grouped circuit 26c are arranged in this order.

The separation distance from the first group circuit 26a to the fourth group circuit 26d is longer than the separation distance from the first group circuit 26a to the second group circuit 26b. Therefore, the first discharging transistor 24c is arranged closest to the second discharging transistor 24d having the smallest potential difference among the other discharging transistors 24b connected in series, and the fourth discharging transistor 24c having the largest potential difference. 24f is located farther than the second discharging transistor 24d. Similarly, the fourth discharging transistor 24f is arranged closest to the third discharging transistor 24e having the smallest potential difference among the other discharging transistors 24b connected in series. transistor 24c is arranged farther than the third transistor 24e. Therefore, according to the discharge device 23 of the present embodiment, the potential difference is maintained while the first group circuit 26a, the second group circuit 26b, the third group circuit 26c, and the fourth group circuit 26d are arranged linearly adjacent to each other. It is possible to easily secure the largest insulating distance between the first discharging transistor 24c and the fourth discharging transistor 24f.

The wiring board 11a also has a heat dissipation pad 11d provided for each discharge transistor 24b. These heat dissipation pads 11d receive heat from the discharge transistor 24b, thereby suppressing temperature rise of the discharge transistor 24b. These heat dissipation pads 11d are connected to a heat dissipation portion (not shown) provided on the wiring substrate 11a via a conductive layer, for example.

The heat dissipation pad 11d provided for the first discharge transistor 24c is provided on the lower surface 11c of the wiring board 11a, which is the mounting surface of the first discharge transistor 24c. The heat dissipation pad 11d provided for the second discharge transistor 24d is provided on the upper surface 11b of the wiring substrate 11a, which is the mounting surface of the second discharge transistor 24d. The heat dissipation pad 11d provided for the third discharge transistor 24e is provided on the upper surface 11b of the wiring board 11a, which is the mounting surface of the third discharge transistor 24e. A heat dissipation pad 11d provided for the fourth discharge transistor 24f is provided on the lower surface 11c of the wiring board 11a, which is the mounting surface of the fourth discharge transistor 24f.

FIG. 5 is a schematic perspective view showing the positional relationship between the four discharge transistors 24b and the four heat dissipation pads 11d. Note that the current adjusting transistor 25b is omitted in FIG. As shown in this figure, the heat dissipation pad 11d does not overlap another heat dissipation pad 11d provided on the opposite surface of the wiring substrate 11a in a projection view along the normal direction of the upper surface 11b and the lower surface 11c. has parts. That is, at least a part of the heat radiation pad 11d is arranged without overlapping other heat radiation pads 11d when viewed from the normal direction of the upper surface 11b and the lower surface 11c of the wiring board 11a. Therefore, even if the temperature of the other heat radiation pad 11d provided on the opposite side of the wiring board 11a is high, the entire area of the heat radiation pad 11d is affected by the heat of the other heat radiation pad 11d. It is possible to suppress the increase in temperature. That is, at least a portion of the heat dissipation pad 11d is less susceptible to thermal interference from other heat dissipation pads 11d. Therefore, the heat of the discharge transistor 24b can be more reliably received by the heat dissipation pad 11d.

Returning to FIG. 2, a battery P and a motor M are connected to the converter 20 as shown. The converter 20 includes, as terminals for external connection, a pair of battery terminals (positive battery terminal E1 and negative battery terminal E2) to which the battery P is connected. The converter 20 also includes three motor terminals (a U-phase motor terminal Fu, a V-phase motor terminal Fv, and a W-phase motor terminal Fw) to which the motor M is connected.

The power conversion device 1 including such a converter 20 is an electrical device provided in an electric vehicle such as a hybrid vehicle or an electric vehicle, and controls a motor M, which is a rotating electric machine. That is, the power converter 1 performs drive control of the motor M based on the output of the battery P (battery power) and charging control of the battery P based on regenerated power from the motor M. FIG.

In addition, the power conversion device 1 may have a configuration in which the converter 20 is provided with an inverter for power generation and the converter 20 is connected to a generator. In this case, the power converter 1 controls charging of the battery P based on the power generated by the generator.

Here, as illustrated, the battery P has a positive electrode connected to the positive battery terminal E1 and a negative electrode connected to the negative battery terminal E2. The battery P is a secondary battery such as a lithium ion battery, and discharges DC power to the power conversion device 1 and charges DC power via the power conversion device 1 .

The motor M is a three-phase electric motor having three phases, and is the load of the inverter 22 . The motor M has a U-phase input terminal connected to a U-phase motor terminal Fu, a V-phase input terminal connected to a V-phase motor terminal Fv, and a W-phase input terminal connected to a W-phase motor terminal Fw. ing. Such a motor M has a rotating shaft (driving shaft) connected to the wheels of the electric vehicle, and rotates the wheels by applying rotational power to the wheels.

The gate driver 30 is a circuit that generates gate signals based on various duty command values (transformation duty command value and drive duty command value) input from the ECU 40 . For example, the gate driver 30 generates a gate signal to be supplied to the step-up/step-down converter 21 based on the transformation duty command value input from the ECU 40 . The gate driver 30 also generates a gate signal to be supplied to the inverter 22 based on the driving duty command value input from the ECU 40 .

The ECU 40 is a control circuit that performs predetermined control processing based on a prestored control program. The ECU 40 outputs to the gate driver 30 various duty command values (transformation duty command value and driving duty command value) generated based on the above control processing. Such an ECU 40 controls the driving of the motor M and the charging control of the battery P via the converter 20 and the gate driver 30 . That is, the ECU 40 operates based on the detection value (voltage detection value) of the voltage sensor (voltage detection value) and the detection value (current detection value) of the current sensor (current detection value) provided incidentally to the buck-boost converter 21 and the inverter 22, and the operation information of the electric vehicle. Various duty command values (transformation duty command value and drive duty command value) relating to the step-up/step-down converter 21 and the inverter 22 are generated.

In such a power converter 1, the converter 20 is driven based on the gate signal generated by the gate driver 30 under the control of the ECU 40 as described above, and the power is converted between the battery P and the motor M. is done.

As described above, the discharge device 23 of the present embodiment provided in the power conversion device 1 includes a plurality of mutually connected electronic components (the discharge transistor 24b and the current adjustment transistor 25b). Further, the discharging device 23 of the present embodiment discharges the electric charge to the smoothing capacitor 21a installed in the power conversion device 1 of the motor M. As shown in FIG. Further, the discharge device 23 of the present embodiment includes a wiring substrate 11a having an upper surface 11b and a lower surface 11c located behind the upper surface 11b. Further, the discharge device 23 of the present embodiment includes electronic components (the second discharge transistor 24d, the third discharge transistor 24e, the second current adjustment transistor 25d, the third current adjustment) mounted on the upper surface 11b of the wiring board 11a. transistor 25e), and electronic components (first discharging transistor 24c, fourth discharging transistor 24f, first current adjusting transistor 25c, fourth current adjusting transistor 25f) mounted on the lower surface 11c of the wiring board 11a. It has

According to the discharge device 23 of this embodiment, the electronic components of the discharge device 23 are mounted on both the upper surface 11b and the lower surface 11c of the wiring board 11a. Therefore, even if the wiring board 11a is small, it is possible to secure a mounting area for electronic components. Therefore, according to the discharge device 23 of the present embodiment, it is possible to reduce the size of the discharge device 23 that discharges the electric charge of the smoothing capacitor 21a.

Further, the discharging device 23 of the present embodiment includes, as an electronic component, discharging transistors 24b (first discharging transistor 24c, second discharging transistor 24d, third discharging transistor 24e, and A fourth discharging transistor 24f) and a current adjusting transistor 25b for adjusting the amount of current flowing through the discharging transistor 24b are provided. A plurality of combination circuits 26 each including a discharging transistor 24b and a current adjusting transistor 25b are connected in series. According to the discharging device 23 of this embodiment, it is possible to discharge the electric charge of the smoothing capacitor 21a and adjust the amount of current flowing through the discharging transistor 24b.

Further, the discharge device 23 of the present embodiment includes, as the grouped circuit 26, a first grouped circuit 26a, a second grouped circuit 26b, a third grouped circuit 26c, and a fourth grouped circuit 26d, which are connected in order. have. Further, the electronic components included in the second group circuit 26b (the second discharging transistor 24d and the second current adjusting transistor 25d) and the third group circuit 26c (the third discharging transistor 24e and the third current adjusting transistor 25e) are mounted on the upper surface 11b of the wiring board 11a, and the electronic components (the first discharging transistor 24c and the first current adjusting transistor 25c) included in the first group circuit 26a and the fourth group circuit 26d ( Electronic parts included in the fourth discharging transistor 24f and the fourth current adjusting transistor 25f) are mounted on the lower surface 11c of the wiring board 11a.

According to the discharge device 23 of this embodiment, the first discharge transistor 24c is arranged closest to the second discharge transistor 24d having the smallest potential difference among the other discharge transistors 24b connected in series. , can be arranged far from the fourth discharging transistor 24f having the largest potential difference. Further, the fourth discharging transistor 24f is arranged closest to the third discharging transistor 24e having the smallest potential difference among the other discharging transistors 24b connected in series, and the first discharging transistor 24c having the largest potential difference is arranged. can be placed far from Therefore, according to the discharge device 23 of the present embodiment, the potential difference is maintained while the first group circuit 26a, the second group circuit 26b, the third group circuit 26c, and the fourth group circuit 26d are arranged linearly adjacent to each other. It is possible to easily secure the largest insulating distance between the first discharging transistor 24c and the fourth discharging transistor 24f.

In addition, in the discharge device 23 of the present embodiment, the wiring board 11a has a heat dissipation pad provided for each discharge switching element and receiving heat from the discharge switching element. Moreover, at least a portion of the heat radiation pad 11d provided on the upper surface 11b and the heat radiation pad 11d provided on the lower surface 11c do not overlap when viewed in projection along the normal direction of the upper surface 11b and the lower surface 11c. are placed in

According to the discharge device 23 of this embodiment, at least a portion of the heat dissipation pad 11d overlaps another heat dissipation pad 11d when viewed from the normal direction of the upper surface 11b and the lower surface 11c of the wiring board 11a. are placed without Therefore, even if the temperature of the other heat radiation pad 11d provided on the opposite side of the wiring board 11a is high, the entire area of the heat radiation pad 11d is affected by the heat of the other heat radiation pad 11d. It is possible to suppress the increase in temperature. Therefore, at least part of the heat dissipation pad 11d is less susceptible to thermal interference from other heat dissipation pads 11d. Therefore, according to the discharge device 23 of the present embodiment, the heat of the discharge transistor 24b can be more reliably received by the heat dissipation pad 11d.

Further, in the discharge device 23 of the present embodiment, the wiring substrate 11a is provided with a gate driver 30 connected to an inverter 22 for converting electric power supplied to the motor M. As shown in FIG. Therefore, it is not necessary to provide the wiring board 11 a of the discharge device 23 separately from the gate driver board 11 . Therefore, it is possible to reduce the size of the device (power conversion device 1) on which the discharge device 23 is mounted.

Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to the above embodiments. The various shapes, combinations, and the like of the constituent members shown in the above-described embodiment are merely examples, and can be variously changed based on design requirements and the like without departing from the gist of the present invention.

For example, in the above embodiment, the electronic components included in the second group circuit 26b (the second discharging transistor 24d and the second current adjusting transistor 25d) and the third group circuit 26c (the third discharging transistor 24e and the third The electronic components included in the current adjusting transistor 25e) are mounted on the upper surface 11b of the wiring board 11a, and the electronic components included in the first set circuit 26a (the first discharging transistor 24c and the first current adjusting transistor 25c) Electronic components included in the fourth group circuit 26d (fourth discharging transistor 24f and fourth current adjusting transistor 25f) are mounted on the lower surface 11c of the wiring board 11a. However, the invention is not limited to this. The present invention includes the electronic components included in the first group circuit 26a, the electronic components included in the second group circuit 26b, the electronic components contained in the third group circuit 26c, and the electronic components included in the fourth group circuit 26d. are dispersed on the upper surface 11b and the lower surface 11c of the wiring board 11a.

Further, in the above-described embodiment, the configuration in which there are four combined circuits 26 has been described. However, in the present invention, the number of grouped circuits 26 may be 1 to 3, or may be 5 or more, and can be changed.

DESCRIPTION OF SYMBOLS 1... Power converter (drive apparatus), 2... Intelligent power module, 3... Capacitor, 4... Reactor, 5... DCDC converter, 6... Main body case, 10... Power module, 11... Gate Driver board 11a Wiring board 11b Upper surface (first surface) 11c Lower surface (second surface) 11d Thermal pad 21a Smoothing capacitor 21b Transformer 22 Inverter 23 Discharge device 24 Discharge circuit 24a Discharge resistor 24b Discharge transistor (electronic component, discharge switching element) 24c First discharge transistor 24d Second discharging transistor 24e Third discharging transistor 24f Fourth discharging transistor 25 Current adjusting circuit 25a Current adjusting resistor 25b Current adjusting transistor (electronic component , current adjusting switching element), 25c... first current adjusting transistor, 25d... second current adjusting transistor, 25e... third current adjusting transistor, 25f... fourth current adjusting transistor, 26... . . Group circuit 26a . battery

Claims (5)

A discharge device comprising a plurality of interconnected electronic components and discharging a smoothing capacitor installed in a motor driving device,
a wiring board having a first surface and a second surface located behind the first surface;
the electronic component mounted on the first surface of the wiring board;
and the electronic component mounted on the second surface of the wiring board. As the electronic component, a discharge switching element connected in parallel to the smoothing capacitor and a current adjustment switching element for adjusting the amount of current flowing through the discharge switching element are provided,
2. The discharge device according to claim 1, wherein a plurality of set circuits each including the discharge switching element and the current adjustment switching element are connected in series. The grouped circuits include a first grouped circuit, a second grouped circuit, a third grouped circuit, and a fourth grouped circuit, which are connected in order,
The electronic component included in the second assembled circuit and the electronic component included in the third assembled circuit are mounted on the first surface of the wiring board,
3. The discharge device according to claim 2, wherein the electronic component included in the first group circuit and the electronic component included in the fourth group circuit are mounted on the second surface of the wiring board. . The wiring board has a heat dissipation pad provided for each of the discharge switching elements and receiving heat from the discharge switching elements,
At least a part of the heat dissipation pad provided on the first surface and the heat dissipation pad provided on the second surface are viewed in projection along the normal direction of the first surface and the second surface. 4. The discharge device according to claim 2, wherein the are arranged without overlapping each other. 5. The discharge device according to claim 1, wherein the wiring board is provided with a gate driver connected to an inverter that converts power supplied to the motor.

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