JP2013027282A - Power converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that since the physique of a capacitor being connected with the input terminals of inverters INV1, INV2, INV3 for connection with an on-vehicle auxiliary machine is large, the case on which the inverters INV1, INV2, INV3 are mounted is likely to be enlarged.SOLUTION: A power supply device PSC including a smoothing capacitor 18, and a normal mode choke coil 16 is shared by inverters INV1, INV2, INV3, and mounted on a substrate 40 for power supply different from substrates 42, 44, 46 for conversion on which the inverters INV1, INV2, INV3 are formed, respectively. A step-down converter 30, a photocoupler 21, and the like, are mounted additionally on the substrate 40 for power supply.

Description

  The present invention relates to a power conversion device including a power conversion circuit for supplying power from a power source to an in-vehicle auxiliary machine.

  For example, Patent Document 1 below proposes an apparatus in which a plurality of power conversion circuits are mounted. For example, Patent Document 2 below proposes a capacitor arrangement structure that suppresses vibration applied to a capacitor connected to an input terminal of an in-vehicle power conversion circuit.

JP 2002-345252 A JP 2009-26958 A

  By the way, in the vehicle, generally, the mounting space of the device is limited. For this reason, when mounting a power converter device provided with a plurality of power converter circuits in vehicles, it is required to reduce the physique. However, since capacitors are generally connected to the input terminals of each power conversion circuit, measures to improve the vibration isolation performance of each capacitor are desired so that each capacitor can withstand vibration. This may make it difficult to reduce the physique. In particular, since the capacitor is provided to smooth the input of the power conversion circuit, a relatively large capacity is required, so that it is difficult to reduce the physique.

  The present invention has been made in the course of solving the above-described problems, and an object thereof is to provide a new power conversion device including a power conversion circuit for supplying power from a power source to an in-vehicle auxiliary machine.

  Hereinafter, means for solving the above-described problems and the operation and effect thereof will be described.

  The invention according to claim 1 is a power conversion device including a power conversion circuit for supplying power of a power source to an in-vehicle auxiliary device, wherein the in-vehicle auxiliary device includes a plurality of in-vehicle auxiliary devices, and the power conversion circuit includes: The power conversion circuit is provided with a separate power conversion circuit for supplying power to each of the plurality of in-vehicle auxiliary devices, and a capacitor connected to a respective input terminal of the separate power conversion circuit is formed by the power conversion circuit. It is characterized in that it is mounted on one power supply substrate different from the substrate for operation.

  In the above-described invention, the capacitor disposed on the power supply substrate is shared by a plurality of power conversion circuits, thereby limiting the location of the capacitor that is a large component compared to the case where the capacitor is provided on the conversion substrate. be able to. For this reason, it is possible to intensively take measures against vibrations on the power supply substrate, and as a result, the power conversion device can be easily downsized as compared with the case where capacitors are distributed to each power conversion circuit.

  According to a second aspect of the present invention, in the first aspect of the present invention, the capacitor includes a plurality of capacitors of the same type.

  In the said invention, the limit which a capacitor | condenser can endure a vibration can be expanded by dividing | segmenting the same kind of capacitor | condenser.

  According to a third aspect of the present invention, in the first aspect of the present invention, the capacitor mounted on the power supply substrate is shared between the different power conversion circuits, and the plurality of power conversion circuits Includes a switching operation performed by switching frequencies different from each other.

  In the situation where capacitors are shared by multiple power conversion circuits, if the switching frequency related to the operation of these power conversion circuits is different, the effective sum of ripple currents caused by the respective switching operations of different power conversion circuits is effective. It has been found by the inventors that the value can be reduced compared to the sum of the effective values of the ripple current. When the effective value of the ripple current is small, it is possible to reduce the size of the shared capacitor or reduce the number of divisions when dividing the same type of capacitor. In the said invention, it was set as the said setting in view of this point.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, a filter circuit provided between the input terminal of the power conversion circuit and the power supply is provided on the power supply substrate. A coil is further mounted.

  The coil of the filter circuit is likely to be larger than the parts constituting the power conversion circuit. In this regard, in the above-described invention, by arranging the coil on the power supply substrate, large-sized components can be intensively mounted on the power supply substrate, and thus the power converter can be easily downsized.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the conversion substrate and the power supply substrate are housed in one case.

  In the above invention, by storing the power supply substrate and the conversion substrate in one case, the total volume can be reduced as compared with the case where they are stored in different cases.

  According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the in-vehicle auxiliary device is provided outside the case.

  In the said invention, it becomes possible to arrange | position a power converter device and a vehicle-mounted auxiliary machine in the place away by providing a vehicle-mounted auxiliary machine in the exterior of a case. For this reason, it becomes easy to arrange | position a power converter device in the place which can maintain the function at the time of the collision accident of a vehicle, etc.

  The invention according to claim 7 is the invention according to claim 5 or 6, further comprising cooling means for cooling the case, and the power conversion circuit corresponding to each of the plurality of in-vehicle auxiliary machines is cooled by the cooling means. In a coordinate system defined by a vertical direction that is a direction from the upstream side to the downstream side of the route and an orthogonal direction of the direction, the coordinate components in the orthogonal direction are arranged so as to be different from each other, and the orthogonal direction The coordinate components in the vertical direction are arranged so that they are adjacent to each other, and the coordinate components in the vertical direction are different from each other.

  In the above invention, by arranging the power conversion circuits so that the coordinate components in the orthogonal direction are different from each other, it is possible to avoid a situation where another power conversion circuit is cooled by the cooling fluid that has cooled one power conversion circuit. Can do. However, even in this case, when the vertical coordinate components are the same, there is a concern that heat adjacent to each other in the orthogonal direction interferes and the cooling effect decreases. In the above invention, in view of this point, the cooling performance can be improved by making the coordinate components in the vertical direction different from each other in which the coordinate components in the orthogonal direction are adjacent to each other.

  The invention according to claim 8 is the invention according to claim 7, wherein among the power conversion circuits corresponding to each of the plurality of in-vehicle auxiliary machines, the one having a large heat generation amount is located upstream of the cooling path by the cooling means. It is arranged.

  As described above, by arranging the power conversion circuit so that the coordinate components in the orthogonal direction are different from each other, basically the situation where the other power conversion circuit is cooled by the cooling fluid that has cooled one power conversion circuit. Can be avoided. However, strictly speaking, the heat absorbed by the cooling fluid that has cooled the power conversion circuit on the upstream side of the cooling path can increase the temperature of the cooling fluid that cools the power conversion circuit on the downstream side. For this reason, the cooling performance of the upstream power conversion circuit is particularly high. In the above-described invention, in view of this point, the power conversion circuit having a large heat generation amount is arranged at the arrangement place where the cooling performance is high.

  The invention according to claim 9 is the power conversion circuit according to claim 7 or 8, wherein the plurality of in-vehicle auxiliary devices are three or more in-vehicle auxiliary devices, and each of the plurality of in-vehicle auxiliary devices corresponds to the plurality of in-vehicle auxiliary devices. A pair of power conversion circuits sandwiching one power conversion circuit in the orthogonal direction is arranged so as to have a portion overlapping the coordinate component in the vertical direction.

  In the above invention, it is easy to increase the vertical distance between the pair of power conversion circuits and the power conversion circuit sandwiching them.

  The invention according to claim 10 is the invention according to any one of claims 1 to 9, wherein the conversion board is provided for each power conversion circuit corresponding to each of the plurality of in-vehicle auxiliary machines. It is characterized in that it is a separate substrate to be mounted.

  In the said invention, the said board | substrate for conversion in which size reduction is desired from the restrictions of arrangement | positioning space etc. dared was formed for every power converter circuit corresponding to each of a some vehicle-mounted auxiliary machine. Thereby, it becomes easy to suppress an excessive stress being applied to the substrate.

  The invention according to claim 11 is the invention according to any one of claims 1 to 10, wherein the power source is a power source for an in-vehicle main engine.

  The invention according to claim 12 is the invention according to claim 11, further comprising operating means for operating the power conversion circuit, and a step-down converter for stepping down the voltage of the power source and outputting the stepped down voltage. The magnetic component of the step-down converter is provided on the power supply substrate, and the operation means uses the output of the step-down converter as a power source.

  The operating voltage of the operating means is generally much smaller than the terminal voltage of the main power supply. For this reason, in the above invention, a step-down converter is mounted. The magnetic components of the step-down converter tend to be larger than the components constituting the power conversion circuit. In the above invention, in view of this point, it is easy to downsize the power conversion device by mounting the magnetic component on the power supply substrate.

  The invention according to claim 13 is the invention according to claim 11 or 12, wherein the power source for the main engine constitutes an in-vehicle high voltage system insulated from an in-vehicle low voltage system having a vehicle body as a reference potential. Each of the plurality of power conversion circuits is further provided with separate operation means for operating each of the plurality of power conversion circuits. The power supply board is provided with an insulation means for receiving a command signal from the low voltage system, and is output via the insulation means. Allocation means for allocating a command signal to be assigned to the operation means.

  In the above invention, by providing the allocating means, it is possible to reduce the number of insulating means as compared with the case where the command signal is output to each different operating means via each different insulating means.

1 is a system configuration diagram according to a first embodiment. FIG. The figure which shows the structure of the power conversion unit concerning the embodiment. The figure which shows the structure of the power conversion unit concerning 2nd Embodiment.

<First Embodiment>
Hereinafter, a first embodiment in which a power converter according to the present invention is applied to a hybrid vehicle will be described with reference to the drawings.

  FIG. 1 shows a system configuration according to the present embodiment.

  The illustrated high voltage battery 20 is a secondary battery such as a lithium ion secondary battery or a nickel hydride secondary battery having a terminal voltage of, for example, 100 V or more. The high voltage battery 20 is a power source for an in-vehicle main unit (not shown). The high voltage battery 20 is insulated from the vehicle body. Specifically, for example, by connecting a pair of capacitors to both ends of the high-voltage battery 20 and connecting those connection points to the vehicle body, the median value between the positive electrode potential and the negative electrode potential of the high-voltage battery 20 becomes the vehicle potential. It is set to be equal.

  The high voltage battery 20 is connected to a pair of power supply lines Lp and Ln, and the power supply lines Lp and Ln are connected to the power supply device PSC. The power supply device PSC includes a normal mode choke coil 16 and a smoothing capacitor 18 connected to each of the power supply lines Lp and Ln. In the present embodiment, the smoothing capacitor 18 includes two types of capacitors 18a and 18b having different frequency characteristics. Here, the capacitor 18a is an aluminum electric field capacitor, and the capacitor 18b is a ceramic capacitor. Since the capacitor 18b has a smaller impedance in the high frequency band than the capacitor 18a, the capacitor 18b mainly absorbs noise in the high frequency band, and the capacitor 18a mainly absorbs noise in the low frequency band.

  Inverters INV1, INV2, and INV3 are connected in parallel to the power supply device PSC. Here, the inverter INV1 is for applying a three-phase alternating current to the heater 10 mounted on the in-vehicle air conditioner. The inverter INV2 is for applying a three-phase AC voltage to the blower fan motor 12 mounted on the in-vehicle air conditioner. Further, the inverter INV3 is for applying a three-phase AC voltage to the electric motor 14 mounted on the water pump that cools the cooling water in the cylinder block of the in-vehicle internal combustion engine. Although the heater 10 is an electric heater, in the present embodiment, the heater 10 is designed to be driven by a three-phase inverter similar to the inverters INV2 and INV3.

  Note that the inverters INV1, INV2, INV3 and the power supply device PSC are housed in a single case CA made of metal (for example, aluminum), and the in-vehicle loads (the electric motors 12, 14 and the heater 10) are placed in the case CA. It is externally attached. This is a setting made for the purpose of downsizing the case CA and arranging it in a place where it is not easily damaged even in the event of a vehicle collision or the like.

  In the case CA, microcomputers 24, 26, and 28 that generate operation signals for the inverters INV1, INV2, and INV3 and output the operation signals to the inverters INV1, INV2, and INV3, respectively, and a photocoupler 21 from the outside are provided. And a communication microcomputer 22 that allocates and outputs a command value of a control amount of each load (auxiliary machine) to the microcomputers 24, 26, and 28. Thus, when a corresponding command value input from the outside is input to each of the microcomputers 24, 26, and 28, the microcomputer 24, 26, and 28 performs an operation for setting the assigned command value. The voltage of each phase of the inverters INV1, INV2, and INV3 is manipulated as a quantity. This can be performed, for example, by generating operation signals for the inverters INV1, INV2, and INV3 in accordance with a magnitude comparison between a command voltage for each phase as an operation amount and a triangular wave carrier. Note that the switching frequencies fs1, fs2, and fs3 when operating the inverters INV1, INV2, and INV3 are set to different frequencies. This can be realized, for example, by performing the triangular wave PWM process and making the carrier frequencies different from each other.

  Note that each of the microcomputers 22, 24, 26, and 28 uses the step-down converter 30 that steps down the voltage of the high voltage battery 20 as a power source, and the output is supplied as electric power. Further, the microcomputer 22, the photocoupler 21, the power supply device PSC, and the step-down converter 30 are mounted on the power supply board 40, and the inverter INV1 and the microcomputer 24 are mounted on the conversion board 42, and the inverter INV2 The microcomputer 26 is mounted on the conversion board 44, and the inverter INV 3 and the microcomputer 28 are mounted on the conversion board 46.

  FIG. 2 shows the structure of the case CA according to the present embodiment and how the power supply substrate 40 and the conversion substrates 42, 44, and 46 are accommodated in the case CA.

  As shown in FIG. 2A, in the case CA, the power supply substrate 40 and the conversion substrates 42, 44, and 46 are arranged in a row so as to have a gap therebetween. Here, the connection member 50 is provided between the power supply substrate 40 and the conversion substrate 42, between the conversion substrate 42 and the conversion substrate 44, and between the conversion substrate 44 and the conversion substrate 46. Is electrically connected. Here, the connection member 50 is a conductive member fitted into each of the end portions of two adjacent substrates.

  Specifically, the connection member 50 between the power supply substrate 40 and the conversion substrate 42 includes a pair of power supply paths connected to the output terminals (the positive electrode side and the negative electrode side of the smoothing capacitor 18) of the power supply device PSC, and inverters INV1 and INV2. , INV3, a signal propagation path through which a command value for generating each operation signal is transmitted. Further, the connection member 50 between the conversion board 42 and the conversion board 44 has a pair of power supply paths connected to the output terminal of the power supply device PSC and command values for generating respective operation signals of the inverters INV2 and INV3. Is transmitted. Further, the connection member 50 between the conversion board 44 and the conversion board 46 transmits a command value for generating respective operation signals of the pair of power supply paths connected to the output terminal of the power supply device PSC and the inverter INV3. A signal propagation path.

  Connectors 60a, 60b, 60c, 60d, and 60e are formed in a row on one side surface of the case CA. Here, the connector 60 a is means for connecting the pair of power supply lines Lp, Ln and the power supply device PSC of the power supply substrate 40, and is disposed so as to face the power supply substrate 40. The connector 60 b is a means for connecting an external electronic control unit and the power supply substrate 40 (photocoupler 21), and is disposed so as to face the power supply substrate 40. The connector 60c is a means for connecting the heater 10 and the conversion board 42 (inverter INV1), and is disposed so as to face the conversion board 42. Further, the connector 60d is a means for connecting the blower motor 12 and the conversion board 44 (inverter INV2), and is arranged to face the conversion board 44. In addition, the connector 60e is a means for connecting the electric motor 14 of the water pump and the conversion board 46 (inverter INV3), and is disposed so as to face the conversion board 46.

  FIG. 2B shows the surface of the case CA. As shown in the figure, heat sinks (ribs 62a and 62b) are formed in the case CA along the arrangement direction of the connectors 60a to 60e. The ribs 62a and 62b are means for expanding the contact area with the surrounding gas in order to promote heat exchange with the surrounding gas. The rib 62a is formed so as to be orthogonal to the arrangement direction of the conversion substrates 42, 44, 46 (direction in which the substrates face each other: indicated by A in the figure). Thus, by setting the gas flow direction to the orthogonal direction, it is possible to avoid a situation in which the gas that has cooled any of the conversion substrates 42, 44, 46 subsequently cools another. As a result, the cooling capacity of each of the conversion substrates 42, 44, 46 can be made equal.

  As described above, in the present embodiment, the connectors 60a to 60e are arranged on one side surface of the case CA in order to improve workability when the case CA is attached to the in-vehicle system. That is, when there is a connector on each of the pair of side surfaces facing each other of the case CA, when the case is attached to the in-vehicle system, the case CA is connected depending on which side is connected to the connector formed. Therefore, it is necessary to change the support mode, and workability may be reduced.

  In the present embodiment, the power supply substrate 40 and the conversion substrates 42, 44, and 46 are used as separate substrates for the following reason. That is, there is a tendency for the substrate to warp, and in particular, when the members formed on the power supply substrate 40 and the conversion substrates 42, 44, 46 are mounted on one substrate, the surface area of the substrate increases. , Warpage tends to occur remarkably. If warping occurs on the substrate, even if the surface of the substrate is covered with a molding material or the like with the aim of avoiding insulation breakdown between the wiring in the substrate or between the electronic devices, this may be peeled off and the insulation breakdown avoidance function may be reduced. .

  The warp occurs when stress is applied to the substrate. Here, although the method of applying the stress varies depending on the fixing method of the substrate, in general, the stress applied to the smaller substrate is likely to be reduced.

  Further, thermal stress is dominant as the stress. In particular, in this embodiment, since the connectors 60a to 60e are formed only on one side surface of the case CA, a power switching element (a component of the inverters INV1 to INV3) that increases the amount of heat generation is provided on one side surface of the case CA. As a result, the amount of heat generated in this portion increases. For this reason, in this embodiment, stress is easily applied to a specific portion of the substrate, and warpage is likely to occur. On the other hand, by dividing the substrate, it becomes easier to suppress the occurrence of warpage due to thermal stress as much as possible as compared with the case of a single substrate. In addition, by providing a gap between the substrates, the heat radiation area can be increased and the heat radiation performance can be increased as compared with the case where a single substrate is used, thereby also reducing the thermal stress.

  Further, in the present embodiment, the smoothing capacitor 18 and the magnetic components, which are components whose length extending in the vertical direction of the substrate is likely to be large, are integrated into one substrate (power supply substrate 40). FIG. 2 (c) shows how the components are aggregated onto the power supply substrate 40. As illustrated, capacitors 18 a and 18 b, normal mode choke coil 16, photocoupler 21, inductor 30 a of step-down converter 30, and the like are integrated on power supply substrate 40. For this reason, as shown in FIGS. 2 (c) and 2 (d), the vibration countermeasures are locally applied to these components requiring vibration countermeasures, as exemplified by the fact that the capacitor 18a is fixed by the rubber 70. Can do. Therefore, compared with the case where a capacitor is separately provided for each of the inverters INV1, INV2, and INV3, and the case in which the inverter and the capacitor are stored is filled with gel for insulation, etc. The amount can be reduced.

  Further, by mounting the power supply device PSC common to the inverters INV1, INV2, and INV3 mounted on the conversion substrates 42, 44, and 46 on the power supply substrate 40, the heat dissipation of the conversion substrates 42, 44, and 46 is improved. Further improvement can be achieved. That is, because of the physique of the smoothing capacitor 18 and the like, the members mounted on the power supply substrate 40 are higher than the members mounted on the conversion substrates 42, 44, and 46, so that FIG. As shown, the length of the rib 62b of the power supply substrate 40 portion extending radially from the case CA is set shorter than that of the rib 62a of the conversion substrate 42, 44, 46 portion. For this reason, when the power supply device PSC is mounted on each of the conversion substrates 42, 44, 46, the length of the rib 62a of the conversion substrate 42, 44, 46 is shortened, and as a result, the conversion substrates 42, 44. 46, the heat dissipation performance is reduced.

  Further, as described above, the power supply device PSC is shared by the inverters INV1, INV2, and INV3, and the switching frequencies fs1, fs2, and fs3 of the inverters INV1, INV2, and INV3 are made different from each other. It is possible to reduce the size and the number of divisions of the capacitor 18a. That is, when the switching frequencies fs1, fs2, and fs3 are different from each other, the effective value of the sum of ripple currents resulting from the switching operations of the inverters INV1, INV2, and INV3 is the ripple that accompanies the switching operations of the inverters INV1, INV2, and INV3. It becomes smaller than the sum of the effective values of the current. For this reason, the capacity | capacitance of the capacitor | condenser requested | required from the effective value of a ripple current can be reduced. In addition, since the internal resistance of a capacitor tends to increase as the capacitance increases, it is advantageous to divide the capacitor in order to reduce the loss determined according to the product of the effective value of the ripple current and the internal resistance value. On the other hand, if the number of divided capacitors is large, the mounting space increases. On the other hand, according to the above setting that can reduce the effective value of the ripple current, since the loss is reduced compared to the case where the switching frequency is the same, the number of divisions of the capacitor can be reduced, and consequently the mounting space. Can be reduced.

  Incidentally, as the number of divided capacitors increases, the length of the capacitor extending vertically from the substrate can be reduced, and the resistance to vibration is improved. For this reason, it is desirable to divide the number of capacitors into the number required by vibration countermeasures. Here, by making the switching frequencies fs1, fs2, and fs3 different from each other, it is possible to suppress a request to increase the number of divisions for the purpose of reducing loss. It is desirable to be determined so as to compromise both requests.

  As for the quantitative explanation that the effective value of the sum of the ripple currents caused by the respective switching operations of the inverters INV1, INV2, and INV3 is reduced by making the switching frequencies fs1, fs2, and fs3 different from each other, It is given in the “Remarks” column at the end of this specification.

Furthermore, by using the power supply substrate 40 on which the power supply device PSC is mounted as an end portion of the case CA, it becomes easy to miniaturize the power supply substrate 40 as much as possible. On the other hand, when the power supply substrate 40 is the center of the case CA, the power supply lines connected to the positive electrode and the negative electrode of the smoothing capacitor 18 are respectively provided on the pair of ends of the power supply substrate 40. Therefore, the power supply substrate 40 is likely to be enlarged.
<Second Embodiment>
Hereinafter, the second embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  FIG. 3 shows how the conversion substrates 42, 44, 46, etc. are accommodated in the case CA according to this embodiment. In FIG. 3, the same reference numerals are given for the sake of convenience for those corresponding to the members shown in FIG.

  As shown in the figure, in the present embodiment, the arrangement direction of the inverters INV1, INV2, and INV3 (direction A in the figure) is not only orthogonal to the flow direction of the cooling fluid (direction B in the figure), but the following settings are made. To do. That is, the components in the flow direction in the coordinate system determined by the arrangement direction and the flow direction are different between the inverters INV1 and INV3 and the inverter INV2. Thereby, it becomes easy to improve cooling efficiency compared with the case where the flow direction components are the same in the inverters INV1, INV2, and INV3. That is, when the flow direction components are the same in the inverters INV1, INV2, and INV3, the cooling fluid receives heat in the region where the coordinate components in the flow direction are the same. For this reason, heat tends to flow from one of the adjacent inverters to the other, and as a result, the cooling efficiency tends to decrease. On the other hand, such a situation can be suitably suppressed by making the distribution direction component different between the adjacent coordinate components in the arrangement direction.

  In particular, in the present embodiment, the inverter INV2 having the largest heat generation amount qi (i = 1, 2, 3) is arranged on the upstream side of the cooling fluid. Thereby, cooling efficiency can be improved further. In other words, the cooling fluid that has cooled the inverter disposed on the upstream side can increase the temperature of the surrounding cooling fluid, and therefore the upstream side has a higher cooling capacity than the downstream side.

Incidentally, the inverter INV1 and the inverter INV3 are arranged so that the flow direction components are substantially the same. This is a setting for separating the distances in the flow direction between the inverters INV1 and INV3 and the inverter INV2 as much as possible.
<Other embodiments>
Each of the above embodiments may be modified as follows.

"About the coil of the filter circuit"
It is not limited to the normal mode choke coil 16. For example, a common mode choke coil may be used.

“Setting the switching frequency”
In the above embodiment, the switching frequencies fs1, fs2, and fs3 of the three inverters INV1, INV2, and INV3 are set so as not to be the same, but the present invention is not limited to this. For example, the switching frequency fs1 and the switching frequency fs2 may be different, and the switching frequency fs1 and the switching frequency fs3 may be the same. Even in this case, the effective value of the sum of the ripple currents associated with the switching operation of the inverters INV1, INV2, and INV3 can be reduced by making the switching frequency fs1 and the switching frequency fs2 different.

"About capacitors"
The number of divisions of the capacitor 18a is not limited to four and may be any number of divisions of 2 or more. However, if it can withstand vibration or fall below the upper limit of loss, dividing itself is not essential.

  The different types of capacitors 18a and 18b are not limited to aluminum electric field capacitors and ceramic capacitors. For example, three or more types of capacitors may be used in combination. For example, only one type of capacitor may be used.

  The setting is not limited to mounting all of the capacitors on the power supply board 40. For example, a part of the capacitor is connected to the input terminal of the inverter INV1 on the conversion board 42, connected to the input terminal of the inverter INV2 on the conversion board 44, or connected to the input terminal of the inverter INV3 on the conversion board 46. You may do it. Thereby, since the parasitic inductance in which the amount of current changes when switching the switching state in the inverters INV1, INV2, and INV3 can be reduced, surge can be reduced. The capacitors themselves mounted on the conversion boards 42, 44, and 46 have a function of suppressing fluctuations in the input voltage of the inverters INV1, INV2, and INV3. Therefore, in this case, in practice, fluctuations in the input voltage are reduced by cooperation of capacitors mounted on the power supply substrate 40 and the conversion substrates 42, 44, and 46, respectively. However, even in this case, by mounting a common capacitor on the inverters INV1, INV2, and INV3, it is possible to achieve an effect according to the effect of the above embodiment.

“Countermeasures against vibration of components of power supply board 40”
In the said embodiment, although the method of fixing separately using rubber | gum, such as fixing the circumference | surroundings of the capacitor | condenser 18a via the rubber | gum 70, was illustrated, it does not restrict to this. For example, the components in the power supply substrate 40 may be collectively covered with gel.

"About the case"
The case is not limited to one in which the substrates are arranged in a line, and may be arranged in two lines, for example. In this case, in order to avoid the interference of the wiring, it is desirable to form the connector on a pair of side surfaces facing each other of the hexahedron case.

  The case is not limited to a hexahedron, and may be an elliptical shape, for example.

  The case is not limited to a single case. For example, the case for storing the power supply substrate 40, the case for storing the conversion substrate 42, the case for storing the conversion substrate 44, and the conversion substrate 46 are stored. Each case to be performed may be provided as a separate case, and a means for enabling the cases to be connected to each other on the side surfaces of these cases may be provided. In this case, although the total volume of the case tends to increase, the heat dissipation performance of each substrate can be further enhanced.

About power supply boards
The arrangement of the power supply substrate is not limited to the end of the case.

  Further, the power supply board is not limited to the one having only the microcomputer 22 but may be one having the microcomputers 24, 26 and 28.

“Disposition of auxiliary equipment and power conversion circuit”
In the above embodiment, the auxiliary machine is provided outside the case, but the present invention is not limited to this. For example, any one of a plurality of in-vehicle auxiliary devices, the power supply substrate 40 and the conversion substrates 42, 44, and 46 of the above embodiment may be housed in one case.

“Conversion Substrate”
The number of conversion substrates accommodated in one case is not limited to three, and may be two, or four or more. Moreover, you may form the inverter corresponding to each of the some vehicle-mounted auxiliary machine which is mutually different in one conversion board | substrate.

"Allocation method"
If each of the microcomputers 24, 26, and 28 is equipped with a function for identifying a command signal corresponding to itself, the allocating means (the microcomputer 22) may be deleted. Further, each of the microcomputers 24, 26, and 28 may receive the command signal from the low-voltage system via a separate insulating means, so that the allocating means may be deleted.

"Insulation means"
The photocoupler 21 or the like is not limited to the optical insulating element, and may be a magnetic insulating element, for example.

"About connectors"
The invention is not limited to arranging all the connectors on one surface of the hexahedral case. For example, it may be formed on side surfaces facing each other. In this case, since it is possible to reduce the difference between the average value of the distance between one of the pair of surfaces facing each inverter and the average value of the distance to the other, it is possible to alleviate the bias of the heat generation location. .
"Cooling means"
It is not limited to an air-cooled type that is cooled by gas, but may be a water-cooled type that is cooled using a cooling liquid, for example.

"Power conversion circuit"
It is not limited to a three-phase inverter. For example, the heater 10 may be a one-phase inverter. For example, if a 5-phase motor is used as the blower fan motor 12, the inverter is a 5-phase inverter.

  Note that the present invention is not limited to a DC / AC conversion circuit including a switching element that selectively connects each of a positive electrode and a negative electrode of a DC voltage source and a terminal of an auxiliary machine.

"others"
Not only the hybrid vehicle but also a means for storing electric energy (secondary battery, fuel cell), for example, may be provided as a means for storing energy supplied to the onboard main engine. Even in this case, the application of the present invention is effective when the power source of a plurality of in-vehicle auxiliary machines such as a blower fan and a heater is used as the storage means.

As a power supply, it is not restricted to the power supply for vehicle-mounted main machines.
<Remarks>
Hereinafter, a quantitative explanation will be given that the effective value of the sum of ripple currents can be reduced by making the switching frequencies of a plurality of inverters different from each other.

  Here, in order to simplify the discussion, a case will be described in which there are two inverters, an inverter INV1 and an inverter INV2. The ripple current I1 of the inverter INV1 and the ripple current I2 of the inverter INV2 are expressed by the following equations using angular velocities ω1 and ω2 corresponding to the switching frequency.

I1 = A1 · sin (ω1 · t−θ1) (c1)
I2 = A2 · sin (ω2 · t−θ2) (c2)
When the time T is used, the effective value Irms of the sum of the ripple current I1 and the ripple current I2 is expressed by the following equation (c3).

上記の式（ｃ３）の右辺の平方根内の第２項は、「ω１=ω２」である場合には、時間Ｔが長くなるにつれてゼロに収束する。このため、実効値Ｉｒｍｓは、以下の式（ｃ４）にて表現される。

The second term in the square root of the right side of the above equation (c3) converges to zero as the time T becomes longer when “ω1 = ω2”. Therefore, the effective value Irms is expressed by the following formula (c4).

一方、インバータＩＮＶ１とインバータＩＮＶ２とのそれぞれのリップル電流Ｉ１，Ｉ２の実効値Ｉ１ｒｍｓ，Ｉ２ｒｍｓは、時間Ｔを角速度ω１，ω２のそれぞれに対応する周期の公倍数とすることで、以下の式（ｃ５）、（ｃ６）にて表現される。

On the other hand, the effective values I1rms and I2rms of the ripple currents I1 and I2 of the inverter INV1 and the inverter INV2 are expressed by the following formula (c5) by setting the time T as a common multiple of the period corresponding to each of the angular velocities ω1 and ω2. , (C6).

ここで、簡素化のために、リップル電流Ｉ１，Ｉ２の振幅Ａ１，Ａ２が互いに等しいとすると、「Ｉｒｍｓ／（Ｉ１ｒｍｓ＋Ｉ２ｒｍｓ）」は、「１／√２」となる。なお、帰納的な議論によって、インバータがＮ個（＞３）ある場合については、リップル電流の実効値の各別の和に対するリップル電流の和の実効値の比は、「１／√Ｎ」となる。

Here, for simplification, assuming that the amplitudes A1 and A2 of the ripple currents I1 and I2 are equal to each other, “Irms / (I1rms + I2rms)” is “1 / √2”. By inductive discussion, when there are N inverters (> 3), the ratio of the effective value of the sum of the ripple currents to the sum of the effective values of the ripple currents is “1 / √N”. Become.

  16 ... Normal mode choke coil, 18 ... Smoothing capacitor, 40 ... Power supply substrate, 42, 44, 46 ... Conversion substrate, PSC ... Power supply device, CA ... Case.

Claims (13)

In a power conversion device including a power conversion circuit for supplying power from a power source to an in-vehicle auxiliary machine,
The in-vehicle auxiliary machine includes a plurality of in-vehicle auxiliary machines,
The power conversion circuit includes separate power conversion circuits for supplying power to each of the plurality of in-vehicle auxiliary machines,
A power conversion device, wherein a capacitor connected to each input terminal of each of the different power conversion circuits is mounted on one power supply substrate different from the conversion substrate on which the power conversion circuit is formed. .   The power converter according to claim 1, wherein the capacitor includes a plurality of capacitors of the same type. The capacitor mounted on the power supply substrate is shared between the different power conversion circuits,
The power conversion device according to claim 1, wherein the plurality of power conversion circuits include a circuit that is operated to be switched at different switching frequencies.   The coil for a filter circuit provided between the input terminal of the power conversion circuit and the power supply is further mounted on the power supply substrate. Power converter.   The power conversion device according to claim 1, wherein the conversion substrate and the power supply substrate are housed in one case.   The power converter according to claim 5, wherein the in-vehicle auxiliary device is provided outside the case. A cooling means for cooling the case;
The power conversion circuit corresponding to each of the plurality of in-vehicle auxiliary machines is a coordinate system defined by a vertical direction that is a direction from the upstream side to the downstream side of the cooling path by the cooling means and an orthogonal direction of the direction, The orthogonal coordinate components are arranged different from each other, and the orthogonal coordinate components are adjacent to each other, and the vertical coordinate components are arranged different from each other. The power converter according to claim 5 or 6, characterized in that   8. The power conversion according to claim 7, wherein among the power conversion circuits corresponding to each of the plurality of in-vehicle auxiliary machines, a circuit that generates a large amount of heat is disposed upstream of a cooling path by the cooling unit. apparatus. The plurality of in-vehicle auxiliary machines are three or more in-vehicle auxiliary machines,
A pair of power conversion circuits sandwiching one power conversion circuit in the orthogonal direction among the power conversion circuits corresponding to each of the plurality of in-vehicle auxiliary machines is arranged so as to have a portion overlapping the coordinate component in the vertical direction The power converter according to claim 7 or 8, wherein the power converter is configured.   10. The conversion board according to any one of claims 1 to 9, wherein each of the plurality of in-vehicle auxiliary machines is a different board on which the circuit is mounted for each power conversion circuit corresponding to each of the plurality of in-vehicle auxiliary machines. The power converter according to item.   The said power supply is a power supply for vehicle-mounted main machines, The power converter device of any one of Claims 1-10 characterized by the above-mentioned. Operating means for operating the power conversion circuit;
A step-down converter that steps down the voltage of the power source and outputs the stepped down voltage; and
The magnetic component of the step-down converter is provided on the power supply substrate,
12. The power conversion apparatus according to claim 11, wherein the operation means uses the output of the step-down converter as a power source. The power supply for the main engine constitutes an in-vehicle high voltage system that is insulated from an in-vehicle low voltage system having a vehicle body as a reference potential,
Each further comprising a separate operation means for operating each of the plurality of power conversion circuits,
The power supply board further includes an insulating unit to which a command signal from the low voltage system is input, and an allocation unit that allocates a command signal output through the insulating unit to the operation unit. The power converter according to claim 11 or 12.

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