JP6673129B2 - Power converter - Google Patents

Description

  The technology disclosed in this specification relates to a power converter mounted on a vehicle and having a reactor and other electric components connected by a bus bar.

  Patent Documents 1 and 2 disclose a power converter in which a reactor and a capacitor are connected by a bus bar. Each of the power converters of the documents is a device mounted on an electric vehicle, and converts the power of a battery into the driving power of a driving motor. Reactors and capacitors are components of the voltage converter circuit. The bus bar is a conductive and elongated metal plate (metal rod) for electrically connecting two electric components. The bus bar is suitable for transmitting large power with low loss.

JP 2015-220789 A JP-A-2015-144522

  A vehicle-mounted power converter is affected by vehicle vibration during traveling. The capacitor itself of the voltage converter also oscillates. On the other hand, the lead wire of the coil of the reactor and the bus bar are often joined by welding. The welded portion is affected by vehicle vibration and capacitor vibration, causing fatigue deterioration. The present specification provides a technique for improving the vibration resistance of a weld between a lead wire of a coil of a reactor and a bus bar.

The power converter disclosed in this specification is one of vehicle-mounted components in which a reactor and other electrical components are connected by a bus bar. The reactor includes a resin cover that covers at least a part of the coil. The bus bar includes a welded portion welded to a lead wire (coil end) of the coil and a connection portion connected to an electric component. In the power converter disclosed in this specification, a tongue that is press-fitted into an insertion port provided in a resin cover is provided between a welded portion and a connection portion of a bus bar. By employing such a structure, the vibration energy of other electric components transmitted through the connection portion of the bus bar is attenuated through the tongue portion, so that the vibration energy reaching the welding portion can be reduced. Further, according to the above structure, the welded portion and the tongue vibrate integrally with the main body of the reactor (that is, the resin cover), so that the resonance frequency of the welded portion is increased, and the vibration resistance to vehicle vibration is improved. I do. The details and further improvements of the technology disclosed in this specification will be described in the following “Detailed description of the invention”.

It is a block diagram of a power converter of an example. It is a top view of the reactor fixed to the housing of the power converter. It is a side view of the reactor fixed to the housing of the power converter (viewed in the X direction). It is a side view of the reactor fixed to the housing of the power converter (viewed in the Y direction).

  A power converter 10 according to an embodiment will be described with reference to the drawings. The power converter 10 of the embodiment is a device that converts DC power of a battery into AC power for driving a traveling motor in an electric vehicle. First, the circuit configuration of the power converter 10 will be outlined with reference to FIG. The power converter 10 supplies AC power to the two traveling motors 90a and 90b. The power converter 10 includes a bidirectional DC-DC converter 8 and two inverters 9a and 9b. The bidirectional DC-DC converter 8 has both a step-up function of boosting the voltage of the power of the battery 2 and sending it to the inverters 9a and 9b, and a step-down function of stepping down the regenerative power sent from the inverter 9a or 9b and sending it to the battery 2 Having. The regenerative power is DC power obtained by converting the AC power generated by the reverse drive of the motor 90a or 90b into the DC power by the inverter 9a or 9b. Hereinafter, for simplicity of description, the bidirectional DC-DC converter 8 is simply referred to as a converter 8.

  The circuit configuration of the converter 8 will be described. The converter 8 includes a reactor 4, a filter capacitor 3, two transistors 5a and 5b, and two diodes 6a and 6b. The two transistors 5a and 5b are connected in series. Diodes 6a and 6b are connected to the transistors 5a and 5b in anti-parallel. The high potential end and the low potential end of the series connection of the two transistors 5a, 5b are connected to the high potential end and the low potential end of the inverters 9a, 9b, respectively. One end of the reactor 4 is connected to a high-potential end on the battery side of the converter 8, and the other end is connected to a midpoint of a series connection of two transistors 5a and 5b. The filter capacitor 3 is connected between the high potential terminal and the low potential terminal on the battery side. The transistor 5a and the diode 6b are mainly involved in the step-down operation, and the transistor 5b and the diode 6a are mainly involved in the step-up operation. The operation of converter 8 in FIG. 1 is well known and will not be described in detail.

  The description of the circuit configuration of the inverters 9a and 9b is omitted. Note that a smoothing capacitor 7 is connected between the converter 8 and the inverters 9a and 9b to suppress the pulsation of the current flowing between them.

  The hardware of the reactor 4 will be described with reference to FIGS. FIG. 2 is a plan view of the reactor 4 attached to the housing 12 of the power converter 10. FIG. 2 is a plan view showing a part of the housing 12 with the top cover removed. FIG. 3 is a side view of the reactor 4 attached to the housing 12 as viewed from the X direction of the coordinate system in the figure. FIG. 4 is a side view of the reactor 4 attached to the housing 12 as viewed from the Y direction. 3 and 4, the illustration of the lower part of the housing 12 is omitted. For convenience of explanation, the Z-axis positive direction in the figure will be referred to as “up”.

  The reactor 4 is a device in which a coil 41 wound around a core (not shown) is covered with a resin cover 42. Ribs 42 a extend from three places on the side surface of the resin cover 42, and the ribs 42 a are fixed to the housing 12 with bolts 52. Only the upper surface of the coil 41 and the lead wires 41 a and 41 b of the coil 41 are exposed from the resin cover 42. The first bus bar 31 is connected to the lead wire 41a. One end 31a of the first bus bar 31 is welded to the lead wire 41a. The other end 31b of the first bus bar 31 is jointly fastened to the housing 12 together with the terminal 13 by a bolt 51a. The terminal 13 is a terminal extending from a filter capacitor (not shown) housed in the housing 12. That is, the first bus bar 31 electrically connects one end of the reactor 4 to the filter capacitor 3.

  Since the power converter 10 handles a large amount of electric power for driving the traveling motor, a bus bar made of an elongated metal plate is used instead of a cable as a conductor for transmitting the electric power.

  The second bus bar 32 is connected to the lead wire 41b. One end 32a of the second bus bar 32 is joined to the lead wire 41b by welding. The other end 32b of the second bus bar 32 is fastened together with the relay bus bar 14 by a bolt 51b. The relay bus bar 14 is an end of another bus bar that connects the second bus bar 32 and the power card housed in the housing 12. The transistors 5a and 5b and the diodes 6a and 6b shown in FIG. 1 are sealed in the power card. In the power card, transistors 5a and 5b are connected in series, and diodes 6a and 6b are connected in anti-parallel to transistors 5a and 5b, respectively. The relay bus bar 14 is connected to a power card terminal corresponding to the midpoint of the series connection of the transistors 5a and 5b. That is, the second bus bar 32 is a conductor that electrically connects the reactor 4 and the transistors 5a and 5b.

  FIGS. 3 and 4 show the first bus bar 31 and the second bus bar 32 before mounting by phantom lines (two-dot chain lines). The first bus bar 31 is an elongated copper plate. One end 31a of the first bus bar 31 is connected to the lead wire 41a of the coil 41 by welding, and the other end 31b is connected to the terminal 13 of another electric component (the filter capacitor 3) via the bolt 51a. Is connected to A tongue 31c is provided between one end 31a and the other end 31b of the first bus bar 31. The tongue 31c is press-fitted and fixed to an insertion port 43a provided in the resin cover 42 of the reactor 4.

  The second bus bar 32 is also an elongated copper plate. One end 32a is connected to the lead wire 41b of the coil 41 by welding, and the other end 32b is connected to the relay bus bar 14 via a bolt 51b. As described above, the relay bus bar 14 is connected to the midpoint of the series connection of the transistors 5a and 5b. A tongue portion 32c is provided between one end 32a and the other end 32b of the second bus bar 32. The tongue portion 32c is press-fitted and fixed to an insertion opening 43b provided in the resin cover 42 of the reactor 4.

  In power converter 10, bus bars (first bus bar 31, second bus bar 32) of an elongated metal plate for conducting the lead wires 41 a, 41 b of reactor 4 and another electric component are provided on the side surface of resin cover 42 in the middle thereof. The sockets 43a and 43b are fixed. With this structure, the vibration resistance of the welded portions (one end 31a of the first bus bar 31 and one end 32a of the second bus bar 32) is improved. This will be described.

  The power converter 10 is mounted on an electric vehicle and vibrates during traveling. The reactor 4 also vibrates. Since the first bus bar 31 and the second bus bar 32 are fixed by the tongue portions 31c and 32c in the middle thereof, the natural frequency is higher than that in the case where the first bus bar 31 and the second bus bar 32 are fixed only at both ends. Therefore, the vibration resistance of the welded portion between the one end 31a of the first bus bar 31 and the one end 32a of the second bus bar 32 is improved. Further, the filter capacitor 3 vibrates because an alternating current flows in / out. The vibration of the filter capacitor 3 reaches the junction between the one end 31a of the first bus bar 31 and the lead wire 41a through the first bus bar 31. At this time, a part of the vibration energy is absorbed by the resin cover 42 through the tongue 31c fixed to the resin cover 42. As a result, the vibration resistance of the joint (joint between the one end 31a and the lead wire 41a) to the vibration of the filter capacitor 3 is improved.

  Since the first bus bar 31 is fixed to the resin cover 42 with the tongue portion 31c and the second bus bar 32 is fixed to the resin cover 42 with the tongue portion 32c, the following advantages can be obtained. The advantages will be described using the first bus bar 31 as an example. That is, the first bus bar 31 has one end 31a welded and the other end 31b fixed to the housing 12 with the bolt 51a. In the manufacturing process of the power converter 10, after one end 31a of the first bus bar 31 is welded to the lead wire 41a, the other end 31b of the first bus bar 31 is fixed to the housing 12 by a bolt 51a. When the first bus bar 31 is fixed to the housing 12 with the bolts 51a, it moves slightly. Since one end 31a of the first bus bar 31 is already fixed by welding, when the other end 31b moves, the first bus bar 31 is deformed, and an internal stress is generated. However, since the first bus bar 31 is fixed to the resin cover 42 by the tongue 31c between the one end 31a and the other end 31b, internal stress is generated between the other end 31b and the tongue 31c, and the first bus bar 31 is welded. Does not affect the one end 31a. Similarly, the effect of the fastening torque when fastening the bolt 51a is interrupted by the tongue 31c and does not reach the welded one end 31a. The same advantage can be obtained for the second bus bar 32 fixed to the resin cover 42 by the tongue 32c.

  Points to keep in mind regarding the technology described in the embodiment will be described. The first bus bar 31 and the second bus bar 32 include tongue portions 31c and 32c that branch off from the middle of the elongated metal plate, and the tongue portions 31c and 32c are inserted into the resin cover 42 of the reactor 4. It is press-fitted into 43a, 43b. The tongues 31c and 32c may be fixed to the resin cover 42 with bolts instead of press-fitting. Alternatively, the first bus bar 31 and the second bus bar 32 may not include a tongue portion, and may be configured such that the middle of the bus bar is locked and fixed to a slit provided in the resin cover 42.

  The one end 31a of the first bus bar 31 welded to the lead wire 41a of the coil 41 and the one end 32a of the second bus bar 32 welded to the lead wire 41b correspond to an example of a “welded portion” in the claims. The other end 31b of the first bus bar 31 fastened together with the terminal 13 and the other end 32b of the second bus bar 32 fastened together with the relay bus bar 14 correspond to an example of a connecting portion in the claims. The tongue portion 31c of the first bus bar 31 fixed to the insertion port 43a of the resin cover 42 and the tongue portion 32c of the second bus bar 32 fixed to the insertion port 43b correspond to an example of a fixing portion in the claims. I do.

  As described above, specific examples of the present invention have been described in detail, but these are merely examples, and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples illustrated above. The technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings can simultaneously achieve a plurality of objects, and has technical utility by achieving one of the objects.

2: Battery 3: Filter capacitor 4: Reactors 5a, 5b: Transistors 6a, 6b: Diode 7: Smoothing capacitor 8: Bidirectional DC-DC converter (converter)
9a, 9b: inverter 10: power converter 12: housing 13: terminal 14: relay bus bar 31: first bus bar 31a, 32a: one end 31b, 32b: other end 31c, 32c: tongue 32: second bus bar 41: Coil 41a, 41b: Lead wire 42: Resin cover 42a: Rib 43a, 43b: Insert port 51a, 51b, 52: Bolt 90a, 90b: Traveling motor

Claims (1)

It is a power converter that is mounted on the vehicle, and the reactor and other electric components are connected by a bus bar,
The reactor includes a resin cover that covers at least a part of the coil,
The bus bar includes a welded portion welded to the lead wire of the coil and a connection portion connected to the electric component, and is provided on the resin cover between the welded portion and the connection portion . A power converter having a tongue that is press-fitted into an insertion port .

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