discharge device

Abstract

To miniaturize a discharge device that discharges an electric charge of a smooth capacitor mounted on a driving device of a motor.SOLUTION: A discharge device 23 is provided with electronic components connected to each other, and discharges an electric charge of a smooth capacitor 21a installed on an electric conversion device 1 of a motor M. The discharge device 23 comprises: a wiring board 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.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a discharge device. [Background technology]

[0002] Electric vehicles, hybrid vehicles, and other electrically powered vehicles are equipped with a drive device for driving a motor. For example, Patent Document 1 discloses a discharge device that discharges the charge of a smoothing capacitor provided in the drive device. The discharge device disclosed in Patent Document 1 includes multiple discharge circuit transistors connected in parallel to the smoothing capacitor, and discharges the charge of the smoothing capacitor when the discharge circuit transistors are turned on. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-160954 Summary of the Invention [Problem to be solved by the invention]

[0004] The discharge device disclosed in Patent Document 1 includes multiple electronic components, such as a discharge circuit transistor and a current adjustment transistor that adjusts the amount of current flowing through the discharge circuit transistor. These electronic components are mounted on a substrate. However, in Patent Document 1, all of the electronic components, including the discharge circuit transistor and the current adjustment transistor, are mounted on one side of the substrate. This requires a large mounting space for the electronic components on one side of the substrate, which results in an increased size of the discharge device.

[0005] The present invention has been made in view of the above-mentioned problems, and has as its object to reduce the size of a discharge device that discharges the charge of a smoothing capacitor mounted in a motor drive device. [Means for solving the problem]

[0006] The present invention employs the following configuration as a means for solving the above problems.

[0007] The first aspect is a discharge device that includes a plurality of interconnected electronic components and discharges the charge of a smoothing capacitor installed in a motor drive device, and is configured to include a wiring board having a first surface and a second surface located on the back side of the first surface, the electronic components mounted on the first surface of the wiring board, and the electronic components mounted on the second surface of the wiring board.

[0008] The second aspect is the same as the first aspect, except that the electronic components include a discharge switching element connected in parallel to the smoothing capacitor and a current adjustment switching element that adjusts the amount of current flowing through the discharge switching element, and multiple set circuits including the discharge switching element and the current adjustment switching element are connected in series.

[0009] A third aspect is the second aspect, wherein the circuit groups include a first circuit group, a second circuit group, a third circuit group, and a fourth circuit group connected in sequence, the electronic components included in the second circuit group and the electronic components included in the third circuit group are mounted on the first surface of the wiring board, and the electronic components included in the first circuit group and the electronic components included in the fourth circuit group are mounted on the second surface of the wiring board.

[0010] 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 which receives heat from the discharge switching elements, and the heat dissipation pads provided on the first surface and the heat dissipation pads provided on the second surface are arranged so that at least a portion of them do not overlap when viewed in a projection along the normal direction of the first surface and the second surface.

[0011] A fifth aspect is any one of the first to fourth aspects, wherein the wiring board is provided with a gate driver connected to an inverter that converts power supplied to the motor. [Effects of the Invention]

[0012] According to the present invention, electronic components of the discharge device are mounted on both the first and second surfaces of the wiring board. Therefore, even if the wiring board is small, it is possible to ensure a mounting area for the electronic components. Therefore, according to the present invention, it is possible to miniaturize the discharge device that discharges the charge of the smoothing capacitor mounted on the motor drive device. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is an exploded perspective view schematically illustrating a general configuration of a power conversion device including a discharge device according to an embodiment of the present invention. [Figure 2] 1 is a circuit diagram illustrating a schematic configuration of a power conversion device including a discharge device according to an embodiment of the present invention. [Figure 3] FIG. 2 is an enlarged view of a discharge device according to an embodiment of the present invention. [Figure 4] 1A is a schematic enlarged view of a portion of the upper surface of the wiring board, and FIG. 1B is a schematic enlarged view of a portion of the lower surface of the wiring board. [Figure 5] 2 is a schematic perspective view of a wiring board provided in the discharge device according to an embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of a discharge device according to the present invention will be described with reference to the drawings.

[0015] 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 automobile, and is provided between a motor (load) (not shown) and a battery. As shown in Fig. 1, the power conversion device 1 includes an intelligent power module 2, a capacitor 3, a reactor 4, a DC-DC converter 5, and a main body case 6.

[0016] The intelligent power module 2 includes a power module 10, a gate driver board 11, an ECU board 12, etc. The power module 10 includes a plurality of power devices 10a having power semiconductor elements, a resin power module case 10b that houses these power devices 10a, and bus bars 10c connected to the power devices 10a. The power module 10 also includes an insulating resin member that prevents short circuits of the bus bars 10c, a water jacket for cooling, etc.

[0017] The gate driver substrate 11 is a substrate on which a gate driver that generates drive signals for a step-up / step-down converter and an inverter formed by the power devices 10a is provided. In this embodiment, a discharge device 23 is formed on the gate driver substrate 11. The discharge device 23 will be described in detail later. The gate driver substrate 11 is stacked on the power module 10. The ECU substrate 12 is a substrate on which an ECU (Electronic Control Unit) that controls the gate driver substrate 11 is provided. The ECU substrate 12 is stacked on the gate driver substrate 11.

[0018] The capacitor 3 is connected to the intelligent power module 2 and is arranged on the side of the power module 10. The reactor 4 is arranged below the intelligent power module 2. The DC-DC converter 5 is arranged on the side of the reactor 4 and below the intelligent power module 2. The DC-DC converter 5 converts the battery power into a voltage suitable for surrounding electronic components (electronic components mounted on the gate driver board 11 and ECU board 12, etc.).

[0019] The main body case 6 is a case that houses the intelligent power module 2, the capacitor 3, the reactor 4, and the DC-DC converter 5, and is equipped with an upper case 6a, a center case 6b, and a lower case 6c. The upper case 6a, the center case 6b, and the lower case 6c are connected so as to be separable in the stacking direction of the power module 10, the gate driver board 11, and the ECU board 12. The upper case 6a covers the intelligent power module 2 from the ECU board 12 side, and is fastened to the center case 6b. The center case 6b covers the periphery of the intelligent power module 2, the capacitor 3, the reactor 4, and the DC-DC converter 5. The lower case 6c covers the reactor 4 and the DC-DC converter 5 from below, and is provided with a connector for connecting the intelligent power module 2 to the motor M (see FIG. 2), and is fastened to the center case 6b.

[0020] Fig. 2 is a circuit diagram showing a schematic configuration of the power conversion device 1. As shown in this figure, the power conversion device 1 includes a converter 20, a gate driver 30, and an ECU 40. As shown in Fig. 2, the converter 20 is disposed between a battery P and a motor M, and performs power conversion between the battery P and the motor M. The converter 20 includes a step-up / step-down converter 21, an inverter 22, and a discharge device 23.

[0021] The step-up / step-down converter 21 steps up the DC voltage output from the battery P at a predetermined step-up ratio. The step-up / step-down converter 21 also steps down the DC voltage output from the inverter 22 at a predetermined step-down ratio. As shown in FIG. 2, the 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.

[0022] In this embodiment, the smoothing capacitor 21a is formed by the capacitor 3 shown in Fig. 1. In addition, in this embodiment, the transformer 21b is formed by the reactor 4 shown in Fig. 1. In addition, in this embodiment, the transformer IGBT 21c is formed by the power device 10a shown in Fig. 1.

[0023] Such a buck-boost converter 21 is a power circuit known as a magnetically coupled interleaved chopper circuit. The buck-boost converter 21 selectively performs a boost operation in which it boosts the DC power input from the battery P via a pair of battery terminals and outputs the boosted power to the inverter 22, and a buck operation in which it lowers the DC power input from the inverter 22 and outputs the DC power to the battery P via a pair of battery terminals. In other words, the buck-boost converter 21 is a power conversion circuit that inputs and outputs DC power bidirectionally between the battery P and the inverter 22.

[0024] 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 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. As shown in FIG. 2, the inverter 22 has three switching legs and is equipped with a total of six drive IGBTs 22a. In this embodiment, the drive IGBTs 22a are formed by the power devices 10a shown in FIG. 1.

[0025] Such an inverter 22 has three (a plurality of) switching legs corresponding to the number of phases of the motor M. The inverter 22 is a power conversion circuit that selectively performs a powering operation and a regenerative operation. That is, the inverter 22 selectively performs a powering operation in which it converts DC power input from the step-up / step-down converter 21 into three-phase AC power and outputs it to the motor M via three motor terminals, and a regenerative operation in which it converts three-phase AC power input from the motor M via the three motor terminals into DC power and outputs it to the step-up / step-down converter 21. 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.

[0026] The discharge device 23 is a circuit connected in parallel to the smoothing capacitor 21a, and discharges the 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. 3, the discharge device 23 includes a discharge circuit 24 and a current adjustment circuit 25. The discharge circuit 24 and the current adjustment circuit 25 are connected in parallel to the smoothing capacitor 21a. That is, one end of each of the discharge circuit 24 and the current adjustment circuit 25 is connected to the positive terminal of the smoothing capacitor 21a, and the other end is connected to the negative terminal of the smoothing capacitor 21a.

[0027] The discharging circuit 24 is a circuit in which discharging resistors 24a and discharging transistors 24b (electronic components, discharging switching elements) are alternately connected in series. In this embodiment, the discharging circuit 24 includes five discharging resistors 24a and four discharging transistors 24b (a first discharging transistor 24c, a second discharging transistor 24d, a third discharging transistor 24e, and a fourth discharging transistor 24f).

[0028] The first discharging transistor 24c, the second discharging transistor 24d, the third discharging transistor 24e, and the fourth discharging transistor 24f are arranged in this order from the positive terminal side of the smoothing capacitor 21a. The first discharging transistor 24c, the second discharging transistor 24d, the third discharging transistor 24e, and the fourth discharging transistor 24f are, for example, bipolar transistors. The discharging resistor 24a is connected to the collector terminal and the emitter terminal of the discharging transistor 24b. The discharging circuit 24 thus configured constantly discharges the charge to the smoothing capacitor 21a.

[0029] The current adjustment circuit 25 is a circuit in which current adjustment resistors 25a and current adjustment transistors 25b (electronic components, current adjustment switching elements) are alternately connected in series. In this embodiment, the current adjustment circuit 25 includes four current adjustment resistors 25a and four current adjustment transistors 25b (a first current adjustment transistor 25c, a second current adjustment transistor 25d, a third current adjustment transistor 25e, and a fourth current adjustment transistor 25f).

[0030] The first current adjustment transistor 25c, the second current adjustment transistor 25d, the third current adjustment transistor 25e, and the fourth current adjustment transistor 25f are arranged in this order from the positive terminal side of the smoothing capacitor 21a. The first current adjustment transistor 25c, the second current adjustment transistor 25d, the third current adjustment transistor 25e, and the fourth current adjustment transistor 25f are, for example, bipolar transistors. A current adjustment resistor 25a is connected to the collector terminal of each current adjustment transistor 25b. Note that multiple current adjustment resistors 25a may be connected in series to the collector terminal of each current adjustment transistor 25b.

[0031] The base terminal of the discharge transistor 24b is connected between the current adjustment resistor 25a and the current adjustment transistor 25b. The base terminal of the current adjustment transistor 25b is connected between the emitter terminal of the discharge transistor 24b and the discharge transistor 24b. Such a current adjustment circuit 25 adjusts the amount of current flowing through each discharge transistor 24b.

[0032] One current adjustment transistor 25b is provided for each discharge transistor 24b. That is, in the discharge device 23 of this embodiment, four circuit sets 26, each including one discharge transistor 24b and one current adjustment transistor 25b, are provided. That is, the discharge device 23 of this embodiment includes four circuit sets 26 connected in series, as shown in FIG. 3.

[0033] The circuit group 26 including the first discharging transistor 24c and the first current adjustment transistor 25c is referred to as the first circuit group 26a. The circuit group 26 including the second discharging transistor 24d and the second current adjustment transistor 25d is referred to as the second circuit group 26b. The circuit group 26 including the third discharging transistor 24e and the third current adjustment transistor 25e is referred to as the third circuit group 26c. The circuit group 26 including the fourth discharging transistor 24f and the fourth current adjustment transistor 25f is referred to as the fourth circuit group 26d.

[0034] FIG. 4(a) is a schematic enlarged view of a portion of the upper surface 11b of the wiring board 11a included in the gate driver board 11. FIG. 4(b) is a schematic enlarged view of a portion of the lower surface 11c of the wiring board 11a included in the gate driver board 11. As shown in these figures, the gate driver board 11 includes a wiring board 11a on which wiring is provided. The discharge resistor 24a, discharge transistor 24b, current adjustment resistor 25a, and current adjustment transistor 25b of the discharge device 23 are mounted on this wiring board 11a. The discharge resistor 24a, discharge transistor 24b, current adjustment resistor 25a, and current adjustment transistor 25b are electrically connected to one another via the wiring layer of the wiring board 11a. In this way, the wiring board 11a also functions as a part of the discharge device 23. That is, the discharge device 23 of this embodiment includes a wiring board 11a and electronic components (a discharge resistor 24a, a discharge transistor 24b, a current adjustment resistor 25a, and a current adjustment transistor 25b).

[0035] The wiring board 11a is a thin board having an upper surface 11b (first surface) and a lower surface 11c (second surface) opposite to the upper surface 11b. In this embodiment, the wiring board 11a is provided with the gate driver 30 connected to the inverter 22 that converts the power supplied to the motor M, as described above.

[0036] 4(a), the second discharge transistor 24d and the second current adjustment transistor 25d are arranged adjacent to each other on the upper surface 11b of the wiring board 11a. Also, the third discharge transistor 24e and the 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 circuit set 26b and the third circuit set 26c are mounted on the upper surface 11b of the wiring board 11a.

[0037] 4(b), the first discharging transistor 24c and the first current adjustment transistor 25c are arranged adjacent to each other on the lower surface 11c of the wiring board 11a. The fourth discharging transistor 24f and the fourth current adjustment transistor 25f are arranged adjacent to each other on the lower surface 11c of the wiring board 11a. In other words, in this embodiment, the first circuit set 26a and the fourth circuit set 26d are mounted on the lower surface 11c of the wiring board 11a.

[0038] 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 are arranged in a substantially linear manner in a direction (width direction) along the width (short side) of the wiring board 11a. 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 in this order, starting from the first circuit set, the second circuit set 26b, the fourth circuit set 26d, and the third circuit set 26c.

[0039] The distance between the first circuit set 26a and the fourth circuit set 26d is longer than the distance between the first circuit set 26a and the second circuit set 26b. Therefore, of the other series-connected discharging transistors 24b, the second discharging transistor 24d, which has the smallest potential difference, is arranged closest to the first discharging transistor 24c, and the fourth discharging transistor 24f, which has the largest potential difference, is arranged farther away than the second discharging transistor 24d. Similarly, of the other series-connected discharging transistors 24b, the third discharging transistor 24e, which has the smallest potential difference, is arranged closest to the fourth discharging transistor 24f, and the first discharging transistor 24c, which has the largest potential difference, is arranged farther away than the third transistor 24e. Therefore, according to the discharge device 23 of this embodiment, it is possible to arrange the first circuit set 26a, the second circuit set 26b, the third circuit set 26c, and the fourth circuit set 26d adjacent to each other in a straight line, while easily ensuring the insulation distance between the first discharge transistor 24c and the fourth discharge transistor 24f, which have the largest potential difference.

[0040] The wiring board 11a also has heat dissipation pads 11d provided for each discharge transistor 24b. These heat dissipation pads 11d receive heat from the discharge transistors 24b to prevent the temperature of the discharge transistors 24b from rising. These heat dissipation pads 11d are connected to a heat dissipation section (not shown) provided on the wiring board 11a via a conductive layer, for example.

[0041] 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 for 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 board 11a, which is the mounting surface for 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 for the third discharge transistor 24e. The 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 for the fourth discharge transistor 24f.

[0042] 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 adjustment transistor 25b is omitted from FIG. 5. As shown in this figure, the heat dissipation pad 11d has a portion that does not overlap with other heat dissipation pads 11d provided on the opposite surface of the wiring board 11a when viewed from a projection along the normal direction to the upper surface 11b and the lower surface 11c. That is, the heat dissipation pad 11d is positioned so that at least a portion of the pad does not overlap with other pads 11d when viewed from the normal direction to the upper surface 11b and the lower surface 11c of the wiring board 11a. Therefore, even if the temperature of the other pads 11d provided on the opposite surface of the wiring board 11a is high, the entire area of ​​the pad 11d can be prevented from becoming too hot due to the heat from the other pads 11d. That is, at least a portion of the pad 11d is less susceptible to thermal interference from the other pads 11d. This makes it possible for the heat dissipation pad 11d to more reliably receive the heat from the discharge transistor 24b.

[0043] Returning to Fig. 2, as shown, a battery P and a motor M are connected to the converter 20. The converter 20 has a pair of battery terminals (a positive battery terminal E1 and a negative battery terminal E2) to which the battery P is connected as external connection terminals. The converter 20 also has 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.

[0044] A power conversion device 1 equipped with such a converter 20 is an electric device provided in an electrically powered 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 conversion device 1 controls the drive of the motor M based on the output of the battery P (battery power) and controls the charging of the battery P based on the regenerative power from the motor M.

[0045] The power conversion device 1 may also be configured such that the converter 20 is provided with a power generation inverter and a generator is connected to the converter 20. In this case, the power conversion device 1 controls charging of the battery P based on the power generated by the generator.

[0046] As shown in the figure, the positive electrode of the battery P is connected to the positive battery terminal E1, and the negative electrode is 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.

[0047] Motor M is a three-phase electric motor with three phases, and is a load of inverter 22. This motor M has a U-phase input terminal connected to U-phase motor terminal Fu, a V-phase input terminal connected to V-phase motor terminal Fv, and a W-phase input terminal connected to W-phase motor terminal Fw. The rotating shaft (drive shaft) of this motor M is connected to the wheels of an electric vehicle, and applies rotational power to the wheels to rotate them.

[0048] The gate driver 30 is a circuit that generates gate signals based on various duty command values ​​(a duty command value for voltage transformation and a duty command value for driving) input from the ECU 40. For example, the gate driver 30 generates gate signals to be supplied to the step-up / step-down converter 21 based on the duty command value for voltage transformation input from the ECU 40. The gate driver 30 also generates gate signals to be supplied to the inverter 22 based on the duty command value for driving input from the ECU 40.

[0049] The ECU 40 is a control circuit that performs predetermined control processing based on a pre-stored control program. The ECU 40 outputs various duty command values ​​(a duty command value for voltage transformation and a duty command value for driving) generated based on the control processing to the gate driver 30. The ECU 40 controls the driving of the motor M and the charging of the battery P via the converter 20 and the gate driver 30. That is, the ECU 40 generates various duty command values ​​(a duty command value for voltage transformation and a duty command value for driving) related to the step-up / step-down converter 21 and the inverter 22 based on the detected values ​​(detected voltage values) of a voltage sensor and the detected values ​​(detected current values) of a current sensor that are additionally provided to the step-up / step-down converter 21 and the inverter 22, as well as operation information of the electric vehicle, etc.

[0050] In such a power conversion device 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 power conversion is performed between the battery P and the motor M.

[0051] As described above, the discharge device 23 of this embodiment provided in the power conversion device 1 includes a plurality of interconnected electronic components (the discharge transistor 24b and the current adjustment transistor 25b). The discharge device 23 of this embodiment discharges electric charge to the smoothing capacitor 21a provided in the power conversion device 1 of the motor M. The discharge device 23 of this embodiment also includes a wiring board 11a having an upper surface 11b and a lower surface 11c located on the reverse side of the upper surface 11b. The discharge device 23 of this embodiment also includes electronic components (the second discharge transistor 24d, the third discharge transistor 24e, the second current adjustment transistor 25d, and the third current adjustment transistor 25e) mounted on the upper surface 11b of the wiring board 11a, and electronic components (the first discharge transistor 24c, the fourth discharge transistor 24f, the first current adjustment transistor 25c, and the fourth current adjustment transistor 25f) mounted on the lower surface 11c of the wiring board 11a.

[0052] According to the discharge device 23 of this embodiment, 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 ensure a mounting area for the electronic components. Therefore, according to the discharge device 23 of this embodiment, it is possible to miniaturize the discharge device 23 that discharges the charge of the smoothing capacitor 21a.

[0053] Furthermore, the discharging device 23 of this embodiment is provided with, as electronic components, discharging transistors 24b (first discharging transistor 24c, second discharging transistor 24d, third discharging transistor 24e, and fourth discharging transistor 24f) connected in parallel to the smoothing capacitor 21a, and a current adjustment transistor 25b that adjusts the amount of current flowing through the discharging transistor 24b. Furthermore, a plurality of set circuits 26, each including the discharging transistor 24b and the current adjustment transistor 25b, are provided and connected in series. The discharging device 23 of this embodiment is capable of discharging the charge in the smoothing capacitor 21a and adjusting the amount of current flowing through the discharging transistor 24b.

[0054] The discharge device 23 of this embodiment also includes a first circuit assembly 26a, a second circuit assembly 26b, a third circuit assembly 26c, and a fourth circuit assembly 26d, which are connected in sequence, as the circuit assembly 26. The electronic components included in the second circuit assembly 26b (the second discharging transistor 24d and the second current adjustment transistor 25d) and the electronic components included in the third circuit assembly 26c (the third discharging transistor 24e and the third current adjustment transistor 25e) are mounted on the upper surface 11b of the wiring board 11a, and the electronic components included in the first circuit assembly 26a (the first discharging transistor 24c and the first current adjustment transistor 25c) and the electronic components included in the fourth circuit assembly 26d (the fourth discharging transistor 24f and the fourth current adjustment transistor 25f) are mounted on the lower surface 11c of the wiring board 11a.

[0055] According to the discharge device 23 of this embodiment, the first discharging transistor 24c can be arranged closest to the second discharging transistor 24d, which has the smallest potential difference among the other series-connected discharging transistors 24b, and far from the fourth discharging transistor 24f, which has the largest potential difference. Furthermore, the fourth discharging transistor 24f can be arranged closest to the third discharging transistor 24e, which has the smallest potential difference among the other series-connected discharging transistors 24b, and far from the first discharging transistor 24c, which has the largest potential difference. Therefore, according to the discharge device 23 of this embodiment, it is possible to easily ensure an insulation distance between the first discharging transistor 24c and the fourth discharging transistor 24f, which have the largest potential difference, while arranging the first circuit set 26a, the second circuit set 26b, the third circuit set 26c, and the fourth circuit set 26d adjacent to each other in a straight line.

[0056] In the discharge device 23 of this embodiment, the wiring board 11a has a heat dissipation pad provided for each discharge switching element and that receives heat from the discharge switching elements. The heat dissipation pad 11d provided on the upper surface 11b and the heat dissipation pad 11d provided on the lower surface 11c are arranged so that they do not overlap at least partially when viewed in a projection view along the normal direction of the upper surface 11b and the lower surface 11c.

[0057] According to the discharge device 23 of this embodiment, the heat dissipation pad 11d is arranged so that at least a portion of the pad does not overlap with other 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 pads 11d on the opposite side of the wiring board 11a is high, the entire area of ​​the pad 11d is prevented from becoming too hot due to the heat from the other pads 11d. Therefore, at least a portion of the pad 11d is less susceptible to thermal interference from the other pads 11d. Therefore, according to the discharge device 23 of this embodiment, the pads 11d can more reliably receive the heat from the discharge transistor 24b.

[0058] Furthermore, in the discharge device 23 of this embodiment, the wiring board 11a is provided with a gate driver 30 connected to an inverter 22 that converts the power supplied to the motor M. Therefore, it is not necessary to provide the wiring board 11a of the discharge device 23 separately from the gate driver board 11. This makes it possible to reduce the size of the device (power conversion device 1) on which the discharge device 23 is mounted.

[0059] While 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-described embodiments. The shapes and combinations of the components shown in the above-described embodiments are merely examples, and various modifications can be made based on design requirements, etc., without departing from the spirit of the present invention.

[0060] For example, in the above embodiment, the electronic components included in the second circuit group 26b (the second discharging transistor 24d and the second current adjustment transistor 25d) and the electronic components included in the third circuit group 26c (the third discharging transistor 24e and the third current adjustment transistor 25e) are mounted on the upper surface 11b of the wiring board 11a, and the electronic components included in the first circuit group 26a (the first discharging transistor 24c and the first current adjustment transistor 25c) and the electronic components included in the fourth circuit group 26d (the fourth discharging transistor 24f and the fourth current adjustment transistor 25f) are mounted on the lower surface 11c of the wiring board 11a. However, the present invention is not limited to this. The present invention may be configured so that the electronic components included in the first circuit group 26a, the electronic components included in the second circuit group 26b, the electronic components included in the third circuit group 26c, and the electronic components included in the fourth circuit group 26d are distributed across the upper surface 11b and the lower surface 11c of the wiring board 11a.

[0061] In the above embodiment, the configuration has been described in which there are four circuit groups 26. However, in the present invention, the number of circuit groups 26 may be one to three, or may be five or more, and may be changed. [Explanation of symbols]

[0062] 1...power conversion device (drive device), 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...heat dissipation 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 discharge transistor, 24e...Third discharge transistor, 24f...Fourth discharge transistor, 25...Current adjustment circuit, 25a...Current adjustment resistor, 25b...Current adjustment transistor (electronic component, current adjustment switching element), 25c...First current adjustment transistor, 25d...Second current adjustment transistor, 25e...Third current adjustment transistor, 25f...Fourth current adjustment transistor, 26...Combined circuit, 26a...First combined circuit, 26b...Second combined circuit, 26c...Third combined circuit, 26d...Fourth combined circuit, 30...Gate driver, M...Motor, P...Battery

Claims

1. A discharge device that includes a plurality of electronic components connected to each other and that discharges a charge from a smoothing capacitor installed in a drive device of a motor, a wiring substrate having a first surface and a second surface located on the back side of the first surface; the electronic component mounted on the first surface of the wiring board; the electronic component mounted on the second surface of the wiring board; Equipped with At least one of the electronic components mounted on the first surface at least partially overlaps with the electronic component mounted on the second surface of the wiring board in a projection view along a normal direction of the first surface and the second surface, The electronic components include a discharging switching element connected in parallel to the smoothing capacitor, and a current adjusting switching element that adjusts the amount of current flowing through the discharging switching element, a plurality of set circuits each including the discharge switching element and the current adjustment switching element are provided and connected in series; The circuit groups include a first circuit group, a second circuit group, a third circuit group, and a fourth circuit group that are connected in series, the electronic components included in the second circuit set and the electronic components included in the third circuit set are mounted on the first surface of the wiring board; the electronic components included in the first circuit set and the electronic components included in the fourth circuit set 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 configured to receive heat from the discharge switching elements, The heat dissipation pads provided on the first surface and the heat dissipation pads provided on the second surface are arranged so as not to overlap at least partially when viewed in a projection along a normal direction of the first surface and the second surface. A discharge device characterized by:

2. 2. The discharge device according to claim 1, wherein the wiring board is provided with a gate driver connected to an inverter that converts the power supplied to the motor.

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