Inverter device

Abstract

The present invention provides an inverter device that can suppress the emission of high-frequency noise in a three-phase inverter. [Solution] An inverter device according to one embodiment comprises a first closed circuit and a second closed circuit. The first closed circuit and the second closed circuit are provided for each phase of a three-phase inverter and each includes a positive-side switching element, a negative-side switching element, a capacitor, a power supply connection part connected to a power supply, and a load connection part connected to a load. The power supply connection parts of the first closed circuit and the second closed circuit are connected to each other, and the load connection parts of the first closed circuit and the second closed circuit are connected to each other, and they are provided adjacent to each other on a circuit board. The currents flowing in adjacent wiring paths in the first closed circuit and the second closed circuit are configured to be in the same direction.

Description

Technical Field

[0001] The disclosed embodiments relate to an inverter device.

Background Art

[0002] Conventionally, in an inverter device for a three-phase motor mounted in an electric vehicle, a hybrid vehicle, etc., it is configured to input and output a large current of several hundred A to the motor. Therefore, in the inverter device, in the lines connecting switching elements, capacitors, etc., the current changes at the level of several hundred A during switching. This change in current is a high frequency from several hundred kHz to several MHz, and there is a possibility that the change in current causes a change in magnetic field and is emitted to the outside of the inverter device as high frequency noise.

[0003] Therefore, for example, it is conceivable to suppress the emission of high frequency noise by partially covering the inverter device with an iron plate or the like for electromagnetic shielding. However, in such a case, problems such as an increase in cost and an increase in the volume of the inverter device occur. Also, in a switching circuit, a technique has been proposed in which two current paths are arranged to face each other and magnetic fields in opposite directions are generated in the two current paths to cancel each other out (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the conventional technologies described above were not compatible with three-phase inverters. In other words, in a three-phase inverter, the direction and magnitude of the current flowing through each phase are different, so the magnetic fields generated by the current changes are also different for each phase. Therefore, even if the current paths in two phases are arranged to face each other, as in the conventional technology, the magnetic fields can only be canceled out if magnetic fields of the same magnitude are generated in both phases simultaneously, and the emission of high-frequency noise cannot be suppressed.

[0006] One embodiment of the invention has been made in view of the above, and aims to provide an inverter device that can suppress the emission of high-frequency noise in a three-phase inverter. [Means for solving the problem]

[0007] To solve the above problems and achieve the objective, an inverter device according to one embodiment comprises a first closed circuit and a second closed circuit. The first closed circuit and the second closed circuit are provided for each phase of a three-phase inverter and each includes a positive-side switching element, a negative-side switching element, a capacitor, a power supply connection part connected to a power supply, and a load connection part connected to a load. The first closed circuit and the second closed circuit are connected to each other at their respective power supply connection parts and to each other at their respective load connection parts, and are provided adjacent to each other on a circuit board. The currents flowing through adjacent wiring paths in the first closed circuit and the second closed circuit are configured to flow in the same direction. [Effects of the Invention]

[0008] In one embodiment, the inverter device is provided with a first closed circuit and a second closed circuit for each phase of the three-phase inverter, and the first and second closed circuits are provided adjacent to each other on the substrate. The currents flowing through the adjacent wiring paths in the first and second closed circuits are configured to flow in the same direction. As a result, the direction of the magnetic field generated in the first closed circuit and the direction of the magnetic field generated in the second closed circuit are opposite, thus canceling out the magnetic fields and suppressing the emission of high-frequency noise. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is an explanatory diagram showing an example of the configuration of an inverter device according to an embodiment. [Figure 2] Figure 2 is a diagram illustrating the magnetic field loop. [Figure 3] Figure 3 is a plan view showing a circuit board on which the inverter device according to the first embodiment is mounted. [Figure 4] Figure 4 is an exploded perspective view showing an example configuration of an inverter device according to the second embodiment. [Figure 5] Figure 5 is a plan view showing a power board according to the second embodiment. [Figure 6] Figure 6 is a plan view showing a capacitor board according to the second embodiment. [Figure 7] Figure 7 is a cross-sectional view taken along line VII-VII in Figure 4. [Figure 8] Figure 8 is a bottom view showing a modified capacitor substrate according to the second embodiment. [Modes for carrying out the invention]

[0010] The embodiments of the inverter device disclosed herein will be described in detail below with reference to the attached drawings. However, the present invention is not limited to the embodiments described below.

[0011] (First Embodiment) The inverter device according to the first embodiment will be described with reference to Figure 1. Figure 1 is an explanatory diagram showing an example of the configuration of the inverter device 1 according to the embodiment.

[0012] As shown in Figure 1, the inverter device 1 is connected to the power supply 100 and the motor 200. The inverter device 1, power supply 100, and motor 200 according to this embodiment are installed in vehicles such as electric vehicles and hybrid vehicles, but are not limited to these.

[0013] Power supply 100 outputs DC power to inverter device 1. Power supply 100 can be, for example, a lithium-ion battery or a lead-acid battery. Inverter device 1 converts the DC power from power supply 100 into three-phase (U-phase, V-phase, W-phase) AC power and supplies it to motor 200, thereby driving motor 200.

[0014] Motor 200 is, for example, a three-phase motor that serves as the power source for a vehicle. Motor 200 is an example of a load. Note that the load to which power is supplied from the inverter device 1 is not limited to motor 200, but can be any device that is driven by three-phase AC power.

[0015] The inverter device 1 is a three-phase inverter and includes a U-phase circuit 10U, a V-phase circuit 10V, and a W-phase circuit 10W. In the following description, the components included in the U-phase, V-phase, and W-phase may be described with "U," "V," and "W" appended to the end of their symbols. In cases where the U-phase, V-phase, and W-phase are not specifically distinguished, the "U," "V," and "W" appended to the end of their symbols may be omitted.

[0016] The U-phase circuit 10U, V-phase circuit 10V, and W-phase circuit 10W each include power supply connection parts 20a and 20b, and the input sides are connected to the power supply 100 via the power supply connection parts 20a and 20b. Since the power supply connection part 20a is connected to the positive electrode of the power supply 100, it may be hereinafter referred to as the positive electrode side power supply connection part 20a. Since the power supply connection part 20b is connected to the negative electrode of the power supply 100, it may be hereinafter referred to as the negative electrode side power supply connection part 20b. Therefore, the input sides of the U-phase circuit 10U, V-phase circuit 10V, and W-phase circuit 10W are each connected to the positive electrode of the power supply 100 via the positive electrode side power supply connection part 20a and to the negative electrode of the power supply 100 via the negative electrode side power supply connection part 20b. The positive electrode side power supply connection parts 20a included in the U-phase circuit 10U, V-phase circuit 10V, and W-phase circuit 10W are electrically connected on the circuit, and thus are shown surrounded by a two-dot chain line in FIG. 1. Similarly, the negative electrode side power supply connection parts 20b included in the U-phase circuit 10U, V-phase circuit 10V, and W-phase circuit 10W are electrically connected on the circuit, and thus are shown surrounded by a two-dot chain line in FIG. 1.

[0017] The U-phase circuit 10U, V-phase circuit 10V, and W-phase circuit 10W each include a motor connection part 50, and the output sides are connected to the motor 200 via the motor connection part 50. The motor connection part 50 is an output part (output terminal) connected to the motor 200 and is an example of a load connection part.

[0018] Hereinafter, the W-phase circuit 10W will be described as an example. The W-phase circuit 10W includes a first closed circuit 30W and a second closed circuit 40W. The first closed circuit 30W includes a capacitor 31W, a positive-side power element 32W, a negative-side power element 33W, the above-described power connection portions 20a and 20b (positive-side power connection portion 20a and negative-side power connection portion 20b), and a motor connection portion 50W. The second closed circuit 40W includes a capacitor 41W, a positive-side power element 42W, a negative-side power element 43W, the above-described power connection portions 20a and 20b (positive-side power connection portion 20a and negative-side power connection portion 20b), and a motor connection portion 50W. Note that the motor connection portions 50W included in the first closed circuit 30W and the second closed circuit 40W are electrically connected on the circuit, and thus are shown surrounded by a two-dot chain line in FIG. 1. The motor connection portions 50V and 50U are also shown surrounded by a two-dot chain line in the same manner.

[0019] One end of the capacitors 31W and 41W is connected to the positive-side power connection portion 20a, and the other end is connected to the negative-side power connection portion 20b. The capacitors 31W and 41W are smoothing capacitors for smoothing the voltage.

[0020] One end of the positive-side power elements 32W and 42W is connected to the positive-side power connection portion 20a, and the other end is connected to the negative-side power elements 33W and 43W. One end of the negative-side power elements 33W and 43W is connected to the positive-side power elements 32W and 42W, and the other end is connected to the negative-side power connection portion 20b. A motor connection portion 50W is connected between the other end of the positive-side power elements 32W and 42W and one end of the negative-side power elements 33W and 43W.

[0021] Power devices such as MOS-FETs (Metal-Oxide-Semiconductor Field-Effect Transistors) and IGBTs (Insulated Gate Bipolar Transistors) can be used as the positive-side power elements 32W and 42W, and the negative-side power elements 33W and 43W. The positive-side power elements 32W and 42W and the negative-side power elements 33W and 43W convert DC power to AC power through switch control by a controller (not shown). Note that the positive-side power elements 32W and 42W are examples of positive-side switching elements, and the negative-side power elements 33W and 43W are examples of negative-side switching elements. The controller may be composed of a microcomputer (MCU) having a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc. Such a MCU may be composed of hardware such as an ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array), in whole or in part.

[0022] The first closed circuit 30W and the second closed circuit 40W are connected at their respective power supply connection points 20a and 20b. More specifically, the first closed circuit 30W and the second closed circuit 40W are connected at their respective positive-side power supply connection points 20a and their respective negative-side power supply connection points 20b. In addition, the first closed circuit 30W and the second closed circuit 40W are connected at their respective motor connection points 50W. Furthermore, the first closed circuit 30W and the second closed circuit 40W are arranged adjacent to each other on the circuit board (see Figure 3 described later).

[0023] In the first and second closed circuits 30W and 40W configured as described above, the controller controls the current flowing through adjacent wiring paths 34W and 44W in the first closed circuit 30W and the second closed circuit 40W to be in the same direction.

[0024] As illustrated in Figure 1, the current A1W flowing through the first closed circuit 30W is clockwise, and the current A2W flowing through the second closed circuit 40W is counterclockwise. As a result, the currents flowing through adjacent wiring paths 34W and 44W in the first and second closed circuits 30W and 40W are in the same direction (in this case, from the positive-side power supply connection 20a to the negative-side power supply connection 20b). By flowing the currents described above through the first and second closed circuits 30W and 40W, the direction of the change in the magnetic field is towards the back of the paper (see symbol B1W) in the first closed circuit 30W and towards the front of the paper (see symbol B2W) in the second closed circuit 40W. In other words, the direction of the change in the magnetic field is opposite in the first closed circuit 30W and the second closed circuit 40W.

[0025] As a result, the magnetic field generated by the change in current in the first closed circuit (30W) and the magnetic field generated by the change in current in the second closed circuit (40W) partially cancel each other out, thereby suppressing the emission of high-frequency noise. Furthermore, since the direction of the magnetic field changes is opposite in the first closed circuit (30W) and the second closed circuit (40W), a loop can be formed in the entire W-phase circuit (10W) between the magnetic fields of the first closed circuit (30W) and the second closed circuit (40W). Figure 2 is a diagram illustrating the magnetic field loop. Note that Figure 2 shows the direction of the magnetic field when the circuit shown in Figure 1 is viewed from the side of the negative electrode power supply connection part 20b. For ease of understanding, the circuit of Figure 1 is also shown in Figure 2.

[0026] As shown in Figure 2, the direction of the magnetic field B1W of the first closed circuit 30W and the direction of the magnetic field B2W of the second closed circuit 40W are opposite (reverse directions), so the magnetic field can be looped for the entire W-phase circuit 10W. This magnetic field loop can suppress the emission of high-frequency noise to the outside of the inverter device 1.

[0027] Regarding the V-phase circuit 10V, the current A1V flowing through the first closed circuit 30V is counterclockwise, and the current A2V flowing through the second closed circuit 40V is clockwise. As a result, the currents flowing through the adjacent wiring paths 34V and 44V in the first and second closed circuits 30V and 40V are in the same direction (here, from the negative-side power supply connection 20b to the positive-side power supply connection 20a). By flowing the currents described above through the first and second closed circuits 30V and 40V, the direction of the change in the magnetic field is towards the viewer on the page (see symbol B1V) in the first closed circuit 30V, and towards the back of the page (see symbol B2V) in the second closed circuit 40V. In other words, the direction of the change in the magnetic field is opposite in the first closed circuit 30V and the second closed circuit 40V.

[0028] As a result, the magnetic field generated by the change in current in the first closed circuit 30V and the magnetic field generated by the change in current in the second closed circuit 40V partially cancel each other out, thereby suppressing the emission of high-frequency noise. Furthermore, since the direction of the change in magnetic field is opposite in the first closed circuit 30V and the second closed circuit 40V, a loop can be formed in the entire V-phase circuit 10V with the magnetic field of the first closed circuit 30V and the magnetic field of the second closed circuit 40V (see Figure 2). This magnetic field loop suppresses the emission of high-frequency noise to the outside of the inverter device 1.

[0029] To explain the U-phase circuit 10U, the current A1U flowing through the first closed circuit 30U is counterclockwise, and the current A2U flowing through the second closed circuit 40U is clockwise. As a result, the currents flowing through adjacent wiring paths 34U and 44U in the first and second closed circuits 30U and 40U are in the same direction (here, from the negative-side power supply connection 20b to the positive-side power supply connection 20a). By flowing the currents described above through the first and second closed circuits 30U and 40U, the direction of the change in the magnetic field is towards the viewer in the first closed circuit 30U (see symbol B1U) and towards the back of the page in the second closed circuit 40U (see symbol B2U). In other words, the direction of the change in the magnetic field is opposite in the first closed circuit 30U and the second closed circuit 40U.

[0030] As a result, the magnetic field generated by the change in current in the first closed circuit 30U and the magnetic field generated by the change in current in the second closed circuit 40U partially cancel each other out, thereby suppressing the emission of high-frequency noise. Furthermore, since the direction of the change in magnetic field is opposite in the first closed circuit 30U and the second closed circuit 40U, a loop can be formed in the entire U-phase circuit 10U with the magnetic field of the first closed circuit 30U and the magnetic field of the second closed circuit 40U (see Figure 2). This magnetic field loop can suppress the emission of high-frequency noise to the outside of the inverter device 1.

[0031] Next, the circuit board on which the inverter device 1 according to the first embodiment is mounted will be described with reference to Figure 3. Figure 3 is a plan view showing the circuit board 60 on which the inverter device 1 according to the first embodiment is mounted. Note that Figure 3 and the figures shown in Figure 4 and later, which will be described later, are all schematic diagrams. Also, in Figure 3, for the sake of understanding, a three-dimensional Cartesian coordinate system is shown, defined by the mutually orthogonal X-axis, Y-axis, and Z-axis directions. Such a Cartesian coordinate system may also be shown in other drawings used in the later explanation. Furthermore, the Cartesian coordinate system is the X-axis, Y-axis, and Z-axis directions when the inverter device 1 is in the illustrated state, and does not limit the mounting direction or arrangement direction of the inverter device 1.

[0032] As shown in Figure 3, the substrate 60 is formed in a rectangular shape in plan view, specifically with the X-axis direction being the longitudinal direction and the Y-axis direction being the short direction. The substrate 60 is equipped with a U-phase circuit 10U, a V-phase circuit 10V, a W-phase circuit 10W, a positive-side power supply connection part 20a, a negative-side power supply connection part 20b, and a motor connection part 50.

[0033] The positive electrode power supply connection portion 20a and the negative electrode power supply connection portion 20b are provided as conductive patterns on the main surface 60a of the substrate 60. The positive electrode power supply connection portion 20a and the negative electrode power supply connection portion 20b are provided in parallel and extend along the longitudinal direction of the substrate 60. In Figure 3, multiple (specifically four) positive electrode power supply connection portions 20a are shown side by side, and these multiple positive electrode power supply connection portions 20a are electrically connected by conductive patterns in the inner layer of the substrate 60 or by busbars (neither of which are shown).

[0034] Capacitors 31 and 41 are provided between the positive-side power supply connection 20a and the negative-side power supply connection 20b. Capacitors 31 and 41 are electrically connected to the positive-side power supply connection 20a and the negative-side power supply connection 20b.

[0035] The positive-side power connection section 20a is electrically connected to the positive-side power elements 32 and 42 of each phase (U phase, V phase, W phase). The negative-side power elements 33 and 43 of each phase are electrically connected to the negative-side power connection section 20b. The positive-side power elements 32 and 42 and the negative-side power elements 33 and 43 are electrically connected via a conductive pattern 60b. This conductive pattern 60b becomes adjacent wiring paths 34 and 44 in the first closed circuit 30 and the second closed circuit 40.

[0036] The conductive pattern 60b extends to the end of the substrate 60 on the positive Y-axis side, and is electrically connected to the motor connection portion 50 near this end. In this way, the motor connection portion 50 is mounted on the substrate 60 at a different location from the adjacent wiring paths 34 and 44 in the first closed circuit 30 and the second closed circuit 40. In other words, the motor connection portion 50 is mounted on the substrate 60 at a location outside the positions where the positive-side power elements 32 and 42 and the negative-side power elements 33 and 43 are located.

[0037] With the motor connection section 50 mounted in this manner, it becomes easy to arrange the capacitors 31, 41, the positive-side power supply connection section 20a, the positive-side power elements 32, 42, the negative-side power elements 33, 43, and the negative-side power supply connection section 20b of the first and second closed circuits 30, 40 in a circular shape when viewed from above. This makes it possible to allow the current in the first and second closed circuits 30, 40 to flow in a clockwise or counterclockwise direction as shown in Figure 1, thereby ensuring that the direction of the magnetic field change is in opposite directions for the first closed circuit 30W and the second closed circuit 40W. Furthermore, since the motor connection section 50 is mounted in a position different from the wiring paths 34, 44, the wiring work for connecting to the motor 200 can be easily performed.

[0038] Furthermore, capacitors 31 and 41 are mounted on the same circuit board 60 on which the positive-side power supply connection section 20a, the negative-side power supply connection section 20b, and the motor connection section 50 are provided. In other words, by providing capacitors 31 and 41, the positive-side power supply connection section 20a, the negative-side power supply connection section 20b, and the motor connection section 50 on the same circuit board 60, the inverter device 1 can be miniaturized.

[0039] Furthermore, the inverter device 1 may be equipped with a heat sink 90 (see Figure 4). The heat sink 90 is positioned on the opposite side of the main surface 60a of the substrate 60 from where the first closed circuit 30W and the second closed circuit 40W are provided. As a result, the heat generated on the substrate 60 is released through the heat sink 90, thereby improving the heat dissipation performance of the inverter device 1.

[0040] As described above, the inverter device 1 according to the first embodiment includes a first closed circuit 30 and a second closed circuit 40. The first closed circuit 30 and the second closed circuit 40 are provided for each phase of the three-phase inverter and each includes positive-side power elements 32, 42, negative-side power elements 33, 43, capacitors 31, 41, power connection parts 20a, 20b connected to the power supply 100, and motor connection part 50 connected to the motor 200. The power connection parts 20a, 20b of the first closed circuit 30 and the second closed circuit 40 are connected to each other, and the motor connection parts 50 of the first closed circuit 30 and the second closed circuit 40 are connected to each other, and are provided adjacent to each other on the circuit board 60. The currents flowing in the adjacent wiring paths 34, 44 in the first closed circuit 30W and the second closed circuit 40W are configured to flow in the same direction.

[0041] As a result, the direction of the magnetic field generated in the first closed circuit 30 and the direction of the magnetic field generated in the second closed circuit 40 are opposite, thus canceling out the magnetic fields and suppressing the emission of high-frequency noise.

[0042] (Second Embodiment) Next, the inverter device 1 according to the second embodiment will be described with reference to Figure 4. Figure 4 is an exploded perspective view showing an example of the configuration of the inverter device 1 according to the second embodiment. In the following description, components common to the first embodiment will be denoted by the same reference numerals and their description may be omitted.

[0043] In the second embodiment, the number of capacitors 31 and 41 in each phase is set to multiple (for example, four). The inverter device 1 according to the second embodiment includes a capacitor board 70 on which multiple capacitors 31 and 41 are mounted. In the inverter device 1 according to the second embodiment, the capacitor board 70 and the board 60 (hereinafter sometimes referred to as "power board 60") are arranged in a stacked manner.

[0044] To explain in more detail, the inverter device 1 according to the second embodiment includes a power board 60, a capacitor board 70, a first busbar 81, a second busbar 82, and a heat sink 90.

[0045] The power board 60, capacitor board 70, etc., will be described below with reference to Figures 5 to 7. Figure 5 is a plan view showing the power board 60 according to the second embodiment. Figure 6 is a plan view showing the capacitor board 70 according to the second embodiment. Figure 7 is a cross-sectional view taken along line VII-VII in Figure 4, and is a longitudinal cross-sectional view of the assembled inverter device 1.

[0046] As shown in Figure 5, the power board 60 is equipped with a positive-side power supply connection section 20a, a negative-side power supply connection section 20b, positive-side power elements 32 and 42, negative-side power elements 33 and 43, and a motor connection section 50.

[0047] The positive-side power connection section 20a is electrically connected to the positive-side power elements 32 and 42 of each phase (U phase, V phase, W phase). The negative-side power elements 33 and 43 of each phase are electrically connected to the negative-side power connection section 20b. The positive-side power elements 32 and 42 and the negative-side power elements 33 and 43 are electrically connected via a conductive pattern 60b. This conductive pattern 60b becomes adjacent wiring paths 34 and 44 in the first closed circuit 30 and the second closed circuit 40.

[0048] As shown in Figures 4 and 7, the motor connection portion 50 is formed in a columnar shape (for example, cylindrical). The motor connection portion 50 is mounted on the power board 60 on adjacent wiring paths 34 and 44 of the first closed circuit 30W and the second closed circuit 40W. In other words, the motor connection portion 50 is mounted so as to stand upright on the conductive pattern 60b of the power board 60.

[0049] The positive terminal power connection section 20a has an insertion hole 61a through which a screw 301 for connecting the power board 60 to the first bus bar 81 and the heat sink 90 is inserted. The negative terminal power connection section 20b has an insertion hole 61b through which a screw 301 for connecting the power board 60 to the second bus bar 82 and the heat sink 90 is inserted.

[0050] As shown in Figure 6, the capacitor board 70 has multiple capacitors 31 and 41 mounted on it. Note that the number of capacitors 31 and 41 shown in Figure 6 is merely an example and is not limited to this number.

[0051] Specifically, the capacitor board 70 has four capacitors 31 included in the first closed circuit 30 (see Figure 5) and four capacitors 41 included in the second closed circuit 40 (see Figure 5) mounted on it for each phase. In addition, the capacitor board 70 has through holes 72 through which the motor connection portion 50 of the power board 60 is inserted. For ease of understanding, in Figure 6, the motor connection portion 50 inserted through the through holes 72 is shown with dashed lines.

[0052] In the second embodiment, the capacitors 31 and 41 are mounted on the capacitor substrate 70 so as to surround the motor connection portion 50 when viewed in the stacking direction (viewed in the Z-axis direction). In other words, the capacitors 31 and 41 are mounted so as to form a circle surrounding the motor connection portion 50 when viewed in the stacking direction. Note that the capacitors 31 and 41 of each phase may be provided at a distance from the capacitors 31 and 41 of other phases in order to reduce the influence of the capacitors 31 and 41 of other phases.

[0053] On the capacitor substrate 70, a conductive pattern (not shown) is formed on the surface opposite to the main surface 70a on which the capacitors 31 and 41 are mounted, and this conductive pattern is electrically connected to the capacitors 31 and 41. In addition, the capacitor substrate 70 has through holes 71 through which screws 302 for connecting to the first bus bar 81 and the second bus bar 82 are inserted.

[0054] The first busbar 81 (see Figure 4) is formed from a conductive material. The first busbar 81 is positioned between the power board 60 and the capacitor board 70, connecting the power board 60 and the capacitor board 70.

[0055] Specifically, the first busbar 81 has a through hole 81a through which a screw 301 is inserted for connecting the first busbar 81 to the power board 60 and the heat sink 90. ​​The heat sink 90 also has a screw hole 91 through which the screw 301 is inserted (see Figure 4). In addition, the first busbar 81 has a screw hole 81b through which a screw 302 is inserted for connecting the first busbar 81 to the capacitor board 70.

[0056] The screws 301 are then inserted through the through-hole 81a of the first busbar 81, the through-hole 61a of the power board 60, and the screw hole 91 of the heat sink 90 and fastened. The screws 302 are also inserted through the through-hole 71 of the capacitor board 70 and the screw hole 81b of the first busbar 81 and fastened. As a result, the lower surface of the first busbar 81 is electrically connected to the positive terminal power supply connection part 20a of the power board 60, and the upper surface is electrically connected to the conductive pattern of the capacitor board 70, thereby electrically connecting the power board 60 and the capacitor board 70.

[0057] Furthermore, the first busbar 81 is provided with a recess 81c. The recess 81c is formed on the lower side of the first busbar 81. More specifically, the recess 81c of the first busbar 81 is formed at a position corresponding to the positive-side power elements 32 and 42 of the power substrate 60. In other words, the recess 81c is formed at a position that covers the positive-side power elements 32 and 42 when the first busbar 81 and the power substrate 60 are connected. That is, as shown by the dashed line in Figure 5, the positive-side power elements 32 and 42 are arranged in the recess 81c of the first busbar 81 so that they overlap when viewed in the stacking direction.

[0058] The second busbar 82 (see Figure 4) is formed from a conductive material. The second busbar 82 is positioned between the power board 60 and the capacitor board 70 and connects the power board 60 and the capacitor board 70.

[0059] Specifically, the second busbar 82 has an insertion hole 82a through which a screw 301 for connecting the second busbar 82 to the power board 60 and the heat sink 90 is inserted. The second busbar 82 also has a screw hole 82b through which a screw 302 for connecting the second busbar 82 to the capacitor board 70 is inserted.

[0060] The screws 301 are then inserted through the through-hole 82a of the second busbar 82, the through-hole 61a of the power board 60, and the screw hole 91 of the heat sink 90 and fastened. The screws 302 are also inserted through the through-hole 71 of the capacitor board 70 and the screw hole 82b of the second busbar 82 and fastened. As a result, the lower surface of the second busbar 82 is electrically connected to the negative terminal power supply connection part 20b of the power board 60, and the upper surface is electrically connected to the conductive pattern of the capacitor board 70, thereby electrically connecting the power board 60 and the capacitor board 70.

[0061] Furthermore, the second bus bar 82 is provided with a recess 82c. The recess 82c is formed on the lower side of the second bus bar 82. More specifically, the recess 82c of the second bus bar 82 is formed at a position corresponding to the negative electrode power elements 33 and 43 of the power substrate 60. In other words, the recess 82c is formed at a position that covers the negative electrode power elements 33 and 43 when the second bus bar 82 and the power substrate 60 are connected. That is, as shown by dashed lines in Figure 5, the negative electrode power elements 33 and 43 are arranged in the recess 82c of the second bus bar 82 so that they overlap when viewed in the stacking direction.

[0062] As described above, in the inverter device 1 according to the second embodiment, the capacitor board 70, the first and second busbars 81 and 82, the power board 60, and the heat sink 90 are stacked in that order from top to bottom. When stacked in this state, the motor connection portion 50 of the power board 60 is inserted through the insertion hole 72 of the capacitor board 70 and protrudes above the capacitor board 70 (see Figure 7). In this way, the motor connection portion 50 protrudes above the capacitor board 70, making it easy to perform wiring work to connect to the motor 200.

[0063] As described above, the motor connection section 50 according to the second embodiment is mounted on the power board 60 as a columnar member on adjacent wiring paths 34 and 44 of the first closed circuit 30W and the second closed circuit 40W. The capacitors 31 and 41 are mounted on a capacitor board 70 which is stacked with the power board 60, so as to surround the motor connection section 50 when viewed in the stacking direction.

[0064] As a result, even in a configuration where the capacitor board 70 is stacked with the power board 60, it becomes possible to allow the current in the first and second closed circuits 30 and 40 to flow clockwise or counterclockwise as shown in Figure 1. Therefore, the direction of the change in the magnetic field can be reliably made to be opposite in the first closed circuit 30W and the second closed circuit 40W, and the emission of high-frequency noise can be suppressed.

[0065] Furthermore, the power board 60 according to the second embodiment is equipped with first and second busbars 81 and 82, which are connected to power supply connection sections 20a and 20b. The capacitor board 70 is fixed to the first and second busbars 81 and 82.

[0066] As a result, even in a configuration where the capacitor board 70 is stacked with the power board 60, the power connection sections 20a and 20b of the power board 60 and the capacitor board 70 can be easily connected via the first and second busbars 81 and 82.

[0067] The first and second busbars 81 and 82 are provided with recesses 81c and 82c formed on the side (bottom surface) facing the power substrate 60. The recesses 81c and 82c are arranged so that the positive-side power elements 32 and 42 and the negative-side power elements 33 and 43 overlap when viewed in the stacking direction.

[0068] This prevents the first and second busbars 81 and 82 from interfering with the positive-side power elements 32 and 42 and the negative-side power elements 33 and 43, even in a configuration where the first and second busbars 81 and 82 are placed between the capacitor board 70 and the power board 60.

[0069] (modified version) In the second embodiment described above, one example of making the capacitors 31 and 41 of each phase less susceptible to the influence of the capacitors 31 and 41 of other phases is to provide them at a distance from the capacitors 31 and 41 of other phases, but this is not the only example. Figure 8 is a bottom view showing a modified capacitor board 70 according to the second embodiment. In Figure 8, the side (bottom surface) 70b opposite to the main surface 70a on which the capacitors 31 and 41 are mounted is shown. Also in Figure 8, the capacitors 31 and 41 mounted on the main surface 70a are shown by dashed lines.

[0070] As described above, in the capacitor substrate 70, a conductive pattern 73 is formed on the surface 70b opposite to the main surface 70a (see Figure 6) on which the capacitors 31 and 41 are mounted. In the modified capacitor substrate 70, slits 74 are formed in the conductive pattern 73 at the portions corresponding to the boundaries of each phase. These slits 74 can efficiently suppress the emission of high-frequency noise.

[0071] To elaborate, if there are multiple capacitors 31 and 41 in each phase and the conductive pattern 73 is common, the magnitude of the current in the first closed circuit 30 and the magnitude of the current in the second closed circuit 40 may not be the same due to the influence of the capacitors 31 and 41 in other phases (see Figure 1). In such cases, even if the currents in the first and second closed circuits 30 and 40 are passed in a clockwise or counterclockwise direction as shown in Figure 1, the magnitudes of the magnetic fields generated will differ from each other.

[0072] Therefore, in the modified version, a slit 74 is provided in the conductive pattern 73 to separate the multiple capacitors 31 and 41 into corresponding phases. This slit 74 makes it possible to isolate the capacitors 31 and 41 in the first and second closed circuits 30 and 40 of each phase, preventing them from interfering with each other. As a result, the capacitors 31 and 41 of each phase are less affected by the capacitors 31 and 41 of the other phases, and the magnitude of the current in the first closed circuit 30 and the magnitude of the current in the second closed circuit 40 can be made the same or approximately the same. Therefore, the magnitude of the magnetic fields generated in the first and second closed circuits 30 and 40 can be made the same or approximately the same, and the emission of high-frequency noise can be efficiently suppressed.

[0073] The shape of the slit 74 shown in Figure 8 is merely an example and not limited to it. In other words, the slit 74 may have any other shape, such as cutting out a portion of the part corresponding to the boundary of each phase in the conductive pattern 73.

[0074] Further effects and modifications can be readily derived by those skilled in the art. Therefore, broader aspects of the present invention are not limited to the specific details and representative embodiments expressed and described above. Accordingly, various modifications are possible without departing from the spirit or scope of the overall concept of the invention as defined by the appended claims and their equivalents. [Explanation of Symbols]

[0075] 1. Inverter device 20a, 20b Power connection section 30 1st closed circuit 31, 41 Capacitors 32, 42 Positive side power element 33, 43 Negative electrode power element 34, 44 Wiring routes 40 2nd closed circuit 50 Motor connection section

Claims

1. A first closed circuit and a second closed circuit are provided for each phase of a three-phase inverter, each including a positive-side switching element, a negative-side switching element, a capacitor, a power supply connection part connected to a power supply, and a load connection part connected to a load, respectively. Equipped with, The first closed circuit and the second closed circuit are connected to each other at their power supply connection points and to each other at their load connection points, and are provided adjacent to each other on the circuit board. The first closed circuit and the second closed circuit are configured such that the currents flowing through adjacent wiring paths are in the same direction. Inverter device.

2. The load connection portion is mounted on the substrate at a position different from the adjacent wiring paths of the first closed circuit and the second closed circuit. The inverter device according to claim 1.

3. The capacitor is mounted on the circuit board on which the power supply connection section and the load connection section are provided. The inverter device according to claim 1.

4. The load connection portion is mounted on the substrate as a columnar member on the adjacent wiring paths of the first closed circuit and the second closed circuit. The capacitor is mounted on a capacitor substrate arranged to be stacked with the substrate, so as to surround the load connection portion when viewed in the stacking direction. The inverter device according to claim 1.

5. The aforementioned circuit board has a busbar mounted on it that is connected to the power supply connection section. The capacitor board is fixed to the busbar. The inverter device according to claim 4.

6. The busbar has a recess formed on the substrate side, The positive electrode switching element and the negative electrode switching element are arranged in the recess such that they overlap when viewed in the stacking direction. The inverter device according to claim 5.

7. In the conductive pattern formed on the capacitor substrate, slits are formed in the portions corresponding to the boundaries of each phase. The inverter device according to claim 4.

8. A heat sink is disposed on the side of the substrate opposite to the side on which the first closed circuit and the second closed circuit are provided. The inverter device according to claim 1, comprising:

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