JP7306297B2 - power conversion unit - Google Patents

Description

The disclosure provided herein relates to power conversion units.

2. Description of the Related Art As disclosed in Patent Literature 1, a power converter is known in which a condenser and a reactor are cooled by coolant flowing through a cooler.

JP 2013-51747 A

In the configuration described in Patent Document 1, the coolant channel for the coolant that cools the condenser and the coolant channel for the coolant that cools the reactor are shared. As a result, heat generated in one of the condenser and reactor may be transferred to the other of the condenser and reactor via the refrigerant.

Therefore, the disclosure described in this specification provides a power conversion unit that suppresses heat transfer of heat generated by one of the condenser and the reactor to the other of the condenser and the reactor via a refrigerant. aim.

One of the disclosures is
a power module (700) having a plurality of switches (524, 525, 614, 615);
a capacitor (305, 306) electrically connected to each of the plurality of switches;
a reactor (510) electrically connected to a plurality of switches;
a case (800) having a bottom (810) with a first main surface (810a) overlapping the power module, the capacitor, and the reactor, and a second main surface (810b) behind the first main surface;
a power module, a condenser, and a cooling passage (830) through which a coolant flows for cooling each of the reactors;
A cooling passage is configured inside between the first main surface and the second main surface at the bottom,
the cooling channel has a first channel (831), a second channel (833) and a third channel (835);
The first flow path, the second flow path, and the third flow path are arranged in series,
the first flow path only faces at least a portion of the capacitor;
The second flow path faces only at least part of the reactor,
The third flow path faces only at least part of the power module.

Thus, the present disclosure connects the channels in series. The capacitors (305, 306) face only the first channel (831). The reactor (510) faces only the second flow path (833). The power module (700) faces only the third channel (835). As a result, heat generated in one of the condensers (305, 306) and the reactor (510) is prevented from being conducted to the other of the condensers (305, 306) and the reactor (510) via the refrigerant. be done.

It should be noted that the reference numbers in parentheses above merely indicate the correspondence with the configurations described in the embodiments described later, and do not limit the technical scope in any way.

1 is a circuit diagram showing an in-vehicle system; FIG. It is a top view of a power conversion unit. FIG. 3 is a cross-sectional view of the power conversion unit corresponding to a cross-sectional line along line III-III shown in FIG. 2; It is a top view of a power conversion unit explaining a 1st modification. FIG. 5 is a top view of the power conversion unit corresponding to a cross-sectional line along line VV shown in FIG. 4; FIG. 11 is a top view of the power conversion unit for explaining a modification of the connecting form of the flow paths;

Embodiments will be described below with reference to the drawings.

(First embodiment)
A power conversion unit 300 according to the present embodiment will be described based on FIGS. 1 to 3. FIG.

<In-vehicle system>
First, an in-vehicle system 100 provided with a power conversion unit 300 will be described based on FIG. This in-vehicle system 100 constitutes a system for an electric vehicle. In-vehicle system 100 has battery 200 , power conversion unit 300 , and motor 400 .

In-vehicle system 100 also includes a plurality of ECUs (not shown). These multiple ECUs transmit and receive signals to and from each other via bus wiring. A plurality of ECUs cooperate to control the electric vehicle. A plurality of ECUs control regeneration and power running of motor 400 according to the SOC of battery 200 . SOC is an abbreviation for state of charge. ECU is an abbreviation for electronic control unit.

Battery 200 has a plurality of secondary batteries. These secondary batteries constitute a battery stack connected in series. The SOC of this battery stack corresponds to the SOC of battery 200 . A lithium-ion secondary battery, a nickel-hydrogen secondary battery, an organic radical battery, or the like can be used as the secondary battery.

Power conversion unit 300 performs power conversion between battery 200 and motor 400 . The power conversion unit 300 converts the DC power of the battery 200 into AC power at a voltage level suitable for powering the motor 400 . The power conversion unit 300 converts AC power generated by power generation (regeneration) of the motor 400 into DC power having a voltage level suitable for charging the battery 200 .

Motor 400 is connected to an output shaft of an electric vehicle (not shown). The rotational energy of motor 400 is transmitted to the running wheels of the electric vehicle via the output shaft. Conversely, the rotational energy of the running wheels is transmitted to motor 400 via the output shaft.

Motor 400 is powered by AC power supplied from power conversion unit 300 . As a result, a driving force is applied to the running wheels. Also, the motor 400 is regenerated by rotational energy transmitted from the running wheels. The AC power generated by this regeneration is converted into DC power and stepped down by the power conversion unit 300 . This DC power is supplied to battery 200 . The DC power is also supplied to various electrical loads mounted on the electric vehicle.

<Power conversion unit>
Next, the power conversion unit 300 will be explained. Power conversion unit 300 includes converter 500 and inverter 600 . Converter 500 boosts the DC power of battery 200 to a voltage level suitable for powering motor 400 . Inverter 600 converts this DC power to AC power. This AC power is supplied to the motor 400 . Inverter 600 converts AC power generated by motor 400 into DC power. Converter 500 steps down this DC power to a voltage level suitable for charging battery 200 .

As shown in FIG. 1, converter 500 is electrically connected to battery 200 via first power supply bus bar 301 and second power supply bus bar 302 . The first power supply busbar 301 is connected to the positive electrode of the battery 200 . The second power supply busbar 302 is connected to the negative electrode of the battery 200 . Converter 500 is electrically connected to inverter 600 via third power supply bus bar 303 and second power supply bus bar 302 .

<Converter circuit configuration>
Converter 500 has first capacitor 305 , reactor 510 , and first switch group 520 . One of the two electrodes of first capacitor 305 is connected to first power supply bus bar 301 . The other of the two electrodes of first capacitor 305 is connected to second power supply bus bar 302 . Reactor 510 is connected to first power supply bus bar 301 . Reactor 510 and first switch group 520 are electrically connected via coupling bus bar 530 . The first switch group 520 is connected to the third power supply bus bar 303 and the second power supply bus bar 302 respectively.

Reactor 510 has an A-phase reactor 511 , a B-phase reactor 512 and a C-phase reactor 513 . Accordingly, the first switch group 520 has an A-phase leg 521 , a B-phase leg 522 and a C-phase leg 523 . Connection bus bar 530 has A-phase connection bus bar 531 , B-phase connection bus bar 532 , and C-phase connection bus bar 533 .

As described above, converter 500 of the present embodiment includes three-phase reactors 510 of phases A to C, legs, and connecting busbars 530 . Each phase of the three-phase leg is independently driven and controlled by the ECU and the gate driver. Alternatively, the three-phase legs are synchronously driven and controlled by the ECU and the gate driver.

Each of the A-phase leg 521 to C-phase leg 523 has a first high-side switch 524, a first low-side switch 525, and a first high-side diode 524a and a first low-side diode 525a as semiconductor elements. Each of these A-phase legs 521 to C-phase legs 521 to C-phase leg 523 constitutes a package in which a semiconductor element is sealed with resin.

In this embodiment, n-channel IGBTs are used as the first high-side switch 524 and the first low-side switch 525 . The tips of the terminals connected to the collector electrodes, emitter electrodes and gate electrodes of the first high-side switch 524 and the first low-side switch 525 are exposed outside the package.

As shown in FIG. 1, the collector electrode of the first high-side switch 524 is connected to the third power supply busbar 303 . An emitter electrode of the first high-side switch 524 and a collector electrode of the first low-side switch 525 are connected. An emitter electrode of the first low-side switch 525 is connected to the second power supply busbar 302 . Thereby, the first high-side switch 524 and the first low-side switch 525 are serially connected in order from the third power supply bus bar 303 toward the second power supply bus bar 302 .

Also, the collector electrode of the first high-side switch 524 is connected to the cathode electrode of the first high-side diode 524a. The emitter electrode of the first high-side switch 524 is connected to the anode electrode of the first high-side diode 524a. As a result, the first high-side diode 524 a is connected in anti-parallel to the first high-side switch 524 .

Similarly, the collector electrode of the first low-side switch 525 is connected to the cathode electrode of the first low-side diode 525a. The emitter electrode of the first low-side switch 525 is connected to the anode electrode of the first low-side diode 525a. As a result, the first low-side diode 525 a is connected in anti-parallel to the first low-side switch 525 .

As the first high-side switch 524 and the first low-side switch 525, MOSFETs can be used instead of IGBTs. The type of switch to be used is not particularly limited. However, if MOSFETs are used as these switches, the above diodes may be omitted.

In addition, the semiconductor element that constitutes converter 500 can be manufactured from a semiconductor such as Si or a wide-gap semiconductor such as SiC. The constituent material of the semiconductor element is not particularly limited.

Furthermore, the types of switches and constituent materials of the A-phase legs 521 to C-phase legs 521 to C-phase legs 523 may be different. For example, the switches provided in the A-phase leg 521 may be MOSFETs made of SiC, and the switches provided in each of the B-phase legs 522 to C-phase legs 522 to 523 may be IGBTs made of Si.

As shown in FIG. 1 , one end of A-phase reactor 511 is connected to first power supply bus bar 301 . The other end of the A-phase reactor 511 is connected to the middle point between the first high-side switch 524 and the first low-side switch 525 of the A-phase leg 521 via the A-phase coupling busbar 531 . As described above, the A-phase reactor 511 is connected to the positive electrode of the battery 200 and the middle point between the first high-side switch 524 and the first low-side switch 525 of the A-phase leg 521 .

Similarly, one end of B-phase reactor 512 is connected to first power supply bus bar 301 . The other end of B-phase reactor 512 is connected to the midpoint between first high-side switch 524 and first low-side switch 525 of B-phase leg 522 via B-phase connecting bus bar 532 . As described above, the B-phase reactor 512 is connected to the positive electrode of the battery 200 and the middle point between the first high-side switch 524 and the first low-side switch 525 of the B-phase leg 522 .

One end of C-phase reactor 513 is connected to first power supply bus bar 301 . The other end of C-phase reactor 513 is connected to a midpoint between first high-side switch 524 and first low-side switch 525 of C-phase leg 523 via C-phase coupling bus bar 533 . As described above, the C-phase reactor 513 is connected to the positive terminal of the battery 200 and the middle point between the first high-side switch 524 and the first low-side switch 525 of the C-phase leg 523 .

The first high-side switch 524 and the first low-side switch 525 of the A-phase leg 521 to C-phase leg 523 are controlled to be opened and closed by the ECU and the gate driver. The ECU generates control signals and outputs them to the gate drivers. The gate driver amplifies the control signal and outputs it to the gate electrode of the switch. Accordingly, the ECU steps up or down the voltage level of the DC power input to converter 500 .

The ECU generates pulse signals as control signals. The ECU adjusts the step-up/step-down level of the DC power by adjusting the on-duty ratio and frequency of this pulse signal. The ECU adjusts the step-up/step-down level by selecting the number of legs to be driven among the A-phase leg 521 to C-phase leg 523 . This step-up/down level is determined according to the target torque of motor 400 and the SOC of battery 200 .

When boosting the DC power of battery 200 , the ECU alternately opens and closes first high-side switch 524 and first low-side switch 525 . Conversely, when stepping down the DC power supplied from inverter 600, the ECU fixes the control signal output to first low-side switch 525 at a low level. At the same time, the ECU sequentially switches the control signal output to the first high-side switch 524 between high level and low level.

<Inverter>
Inverter 600 has a second capacitor 306 and a second group of switches 610 . One of the two electrodes of second capacitor 306 is connected to third power supply bus bar 303 . The other of the two electrodes of second capacitor 306 is connected to second power supply bus bar 302 . The second switch group 610 is connected to each of the third power supply bus bar 303 and the second power supply bus bar 302 .

The second switch group 610 has a U-phase leg 611 , a V-phase leg 612 and a W-phase leg 613 . Each of these three-phase legs has two switch elements connected in series.

Each of the U-phase leg 611 to W-phase leg 613 has a second high-side switch 614 and a second low-side switch 615 as switching elements. Each of the U-phase leg 611 to W-phase leg 613 has a second high-side diode 614a and a second low-side diode 615a. These semiconductor elements are resin-sealed to form a package.

In this embodiment, n-channel IGBTs are used as the second high-side switch 614 and the second low-side switch 615 . The tips of the terminals connected to the collector electrodes, emitter electrodes, and gate electrodes of the second high-side switch 614 and the second low-side switch 615 are exposed from the package.

As shown in FIG. 1, the collector electrode of the second high-side switch 614 is connected to the third power supply busbar 303 . The emitter electrode of the second high side switch 614 and the collector electrode of the second low side switch 615 are connected. An emitter electrode of the second low-side switch 615 is connected to the second power supply busbar 302 . Thereby, the second high-side switch 614 and the second low-side switch 615 are serially connected in order from the third power supply bus bar 303 toward the second power supply bus bar 302 .

A midpoint between the second high-side switch 614 and the second low-side switch 615 of the U-phase leg 611 is connected to the U-phase stator coil of the motor 400 . A midpoint between the second high-side switch 614 and the second low-side switch 615 of the V-phase leg 612 is connected to the V-phase stator coil of the motor 400 . A midpoint between the second high-side switch 614 and the second low-side switch 615 of the W-phase leg 613 is connected to the W-phase stator coil of the motor 400 .

Also, the collector electrode of the second high side switch 614 is connected to the cathode electrode of the second high side diode 614a. The emitter electrode of the second high side switch 614 is connected to the anode electrode of the second high side diode 614a. As a result, the second high-side diode 614 a is connected in anti-parallel to the second high-side switch 614 .

Similarly, the collector electrode of the second low-side switch 615 is connected to the cathode electrode of the second low-side diode 615a. The emitter electrode of the second low-side switch 615 is connected to the anode electrode of the second low-side diode 615a. As a result, the second low-side diode 615 a is connected in anti-parallel to the second low-side switch 615 .

Incidentally, as the second high-side switch 614 and the second low-side switch 615, similarly to the converter 500, MOSFETs can be used instead of IGBTs. When MOSFETs are used as these switch elements, the above diodes may be omitted.

A semiconductor element forming inverter 600 can be manufactured from a semiconductor such as Si or a wide-gap semiconductor such as SiC in the same manner as converter 500 .

As described above, inverter 600 has three-phase legs corresponding to the U-phase to W-phase stator coils of motor 400, respectively. The ECU control signal amplified by the gate driver is input to the gate electrodes of the second high-side switch 614 and the second low-side switch 615 provided in these three-phase legs.

When the motor 400 is powered, the second high-side switch 614 and the second low-side switch 615 of the three-phase leg are PWM-controlled by control signals from the ECU. As a result, inverter 600 generates a three-phase alternating current. When the motor 400 generates (regenerates) power, the ECU stops outputting the control signal, for example. Accordingly, the AC power generated by the power generation of the motor 400 passes through the diodes provided in the three-phase leg. As a result, AC power is converted to DC power.

<Configuration of power conversion unit>
Next, the configuration of the power conversion unit 300 will be described with reference to FIGS. 2 to 5. FIG. In FIGS. 2 to 5, the directions of flow, which will be described later, are indicated by black arrows.

In the following description, the power module 700 includes the A-phase leg 521, the B-phase leg 522, the C-phase leg 523, the U-phase leg 611, the V-phase leg 612, and the W-phase leg 613.

In FIG. 1, this power module 700 is indicated by a region enclosed by a dashed line. In FIG. 1 , for convenience of notation, the second capacitor 306 is included in the area surrounded by the dashed line indicating the power module 700 . Strictly speaking inclusive relation, the second capacitor 306 is not included in the power module 700 .

As shown in FIG. 2, power conversion unit 300 has a case 800 that accommodates these components in addition to the components of converter 500 and inverter 600 that have been described with reference to FIG. The three orthogonal directions are hereinafter referred to as the x direction, the y direction, and the z direction.

As shown in FIG. 3, case 800 has support portion 810 and frame portion 820 . The support portion 810 has a flat shape with a thin thickness in the z direction. The support portion 810 has a first main surface 810a and a second main surface 810b on the back side, which are aligned in the z-direction. A frame portion 820 is connected to the first main surface 810a.

As shown in FIGS. 2 and 3, the frame portion 820 stands up in the z-direction from the first major surface 810a. The frame portion 820 has an annular shape surrounding the first main surface 810a. Thus, the annular inner surface 820a of the frame portion 820 and the first main surface 810a define a storage space that opens in the z direction. A first capacitor 305, a second capacitor 306, a reactor 510, and a power module 700 are housed in this housing space. A first capacitor 305 and a second capacitor 306 are housed in a capacitor case 307 . Note that the capacitor case 307 may accommodate either one of the first capacitor 305 and the second capacitor 306 instead of both.

A substrate (not shown) is provided on the opening side of the frame portion 820 . This substrate and a plurality of terminals exposed from the package of the power module 700 are connected by soldering or the like. The above-described ECU and gate driver are mounted on this substrate. The substrate is protected by a cover (not shown) or the like. The substrate is fixed to the frame 820 or the cover.

As shown in FIG. 3, capacitor case 307, reactor 510, and power module 700 face first main surface 810a. These are fixed to at least one of the first major surface 810a and the inner ring surface 820a. Note that, hereinafter, the capacitor, reactor 510, and power module 700 will be referred to as electrical equipment without distinguishing between them as necessary.

As shown in FIGS. 2 and 3, a cooling passage 830 is formed inside between the first main surface 810a and the second main surface 810b of the support portion 810 to allow the coolant to flow. A side surface 810c connecting the first main surface 810a and the second main surface 810b has an inlet 830a for supplying coolant to the cooling path 830 and an outlet 830b for discharging the coolant from the cooling path 830, respectively. The inflow port 830a and the outflow port 830b are spaced apart in the y-direction.

As schematically shown by broken lines in FIG. 2, the cooling path 830 extends along the x-direction away from the inlet 830a, then bends and extends along the y-direction. The channel then bends again and extends along the x-direction toward the outlet 830b. Thus, the cooling path 830 has a U shape on the plane perpendicular to the z-direction.

<Arrangement of flow channels>
The cooling path 830 will be subdivided and explained. As shown in FIG. 2, in the direction extending from the inlet 830a toward the outlet 830b, the first channel 831, the first connecting channel 832, the second channel 833, the second connecting channel 834, the third channel 835 are connected in series. A first connection channel 832 is positioned between the first channel 831 and the second channel 833 . A second connecting channel 834 is positioned between the second channel 833 and the third channel 835 . Note that the first flow path 831 and the second flow path 833 may be connected without the first connection flow path 832 interposed therebetween. The second flow path 833 and the third flow path 835 may be connected without the second connection flow path 834 interposed therebetween.

One end of the first channel 831 is connected to the inlet 830a. The other end of the first channel 831 is connected to one end of the second channel 833 via the first connecting channel 832 . The other end of the second channel 833 is connected to one end of the third channel 835 via a second connecting channel 834 . The other end of the third channel 835 is connected to the outflow port 830b.

<Positioning state between flow path and electric device>
As shown in FIG. 2, at least part of the capacitor case 307 faces only the first flow path 831 on the first main surface 810a side in the z direction. The capacitor case 307 is not opposed to other flow paths. However, the capacitor case 307 faces the other flow paths in a direction inclined in the z direction.

The distance between the condenser case 307 and the first flow path 831 is shorter than the distance between the condenser case 307 and the other flow paths of the cooling path 830 . The thermal resistance between capacitor case 307 and first flow path 831 is lower than the thermal resistance between capacitor case 307 and other flow paths. The condenser case 307 can easily and positively exchange heat with the first flow path 831 .

At least part of the reactor 510 faces only the second flow path 833 on the first main surface 810a side in the z direction. Reactor 510 is not opposed to other flow paths. However, the reactor 510 faces the other flow path in a direction inclined in the z direction.

The distance between reactor 510 and second flow path 833 is shorter than the distance between reactor 510 and the other flow paths of cooling path 830 . The thermal resistance between reactor 510 and second flow path 833 is lower than the thermal resistance between reactor 510 and other flow paths. Reactor 510 is more likely to positively exchange heat with second flow path 833 .

At least part of the power module 700 faces only the third flow path 835 on the first main surface 810a side in the z direction. The power module 700 is not opposed to other flow paths. However, the power module 700 faces the other flow path in a direction inclined in the z direction.

The distance between the power module 700 and the third channel 835 is shorter than the distance between the power module 700 and the other channels of the cooling channel 830 . The thermal resistance between the power module 700 and the third channel 835 is lower than the thermal resistance between the power module 700 and other channels. The power module 700 can easily exchange heat positively with the third flow path 835 .

To put it another way, the facing state between the flow path and the electric device is that the entire surface of the capacitor case 307 facing the first flow path 831 is larger than the entire surface of the reactor 510 facing the second flow path 833. Located upstream. All of the surfaces of the reactor 510 facing the second flow path 833 are located upstream of all of the surfaces of the power module 700 facing the third flow path 835 .

Also, the first connecting channel 832 and the second connecting channel 834 are not opposed to each of the three electric devices in the z direction. However, the first connecting channel 832 and the second connecting channel 834 face the three electric devices in a direction inclined in the z direction. Hereinafter, the first connecting channel 832 and the second connecting channel 834 will be referred to as connecting channels without distinguishing between them, as required.

The distance between the electrical device and the connecting channel is longer than the distance between the electrical device and the channel facing the electrical device itself. The thermal resistance between the electrical device and the connecting channel tends to be higher than the thermal resistance between the electrical device and the channel facing the electrical device itself. In the cooling path 830, it is more difficult for the electrical equipment to exchange heat with the connecting flow path than with the flow path facing the electrical equipment itself.

<Heat Exchange Between Refrigerant and Electrical Equipment>
In the first channel 831, the coolant flows from the inlet 830a to the first connecting channel 832 side. The heat generated by the condenser housed in the condenser case 307 exchanges heat with the refrigerant flowing through the first flow path 831 . The refrigerant heat-exchanged with the condenser flows to the first connecting channel 832 .

The coolant flowing into the first connection channel 832 flows from the first channel 831 side toward the second channel 833 side. The first connection channel 832 does not face any electric device in the z direction. Therefore, the coolant flowing through the first connection channel 832 is less susceptible to thermal interference from electrical equipment.

In the second flow path 833, the coolant flows from the first connection flow path 832 side to the second connection flow path 834 side. The heat generated in reactor 510 exchanges heat with the refrigerant flowing through second flow path 833 . The refrigerant heat-exchanged with reactor 510 flows to second connection flow path 834 . In this way, after the refrigerant is heat-exchanged with the condenser in the first flow path 831 , it is further heat-exchanged with the reactor 510 in the second flow path 833 and flows to the second connecting flow path 834 .

The coolant flowing to the second connecting channel 834 flows from the second channel 833 side toward the third channel 835 side. The second connection channel 834 does not face any electric device in the z direction. Therefore, the coolant flowing through the second connection channel 834 is less susceptible to heat interference from the outside.

In the third channel 835, the coolant flows from the second connecting channel 834 side to the outlet 830b. The heat generated by the power module 700 exchanges heat with the coolant flowing through the third flow path 835 . The refrigerant heat-exchanged with power module 700 is discharged to the outside from outlet 830b.

In this way, the refrigerant undergoes heat exchange with the condenser in the first flow path 831 and then heat exchanges with the reactor 510 in the second flow path 833 . The refrigerant heat-exchanged with reactor 510 in second flow path 833 heat-exchanges with power module 700 in third flow path 835 . The refrigerant heat-exchanged with the power module 700 in the third flow path 835 flows to the outlet 830b. As described above, heat is exchanged with the refrigerant flowing through the flow path in the order of the condenser, reactor 510, and power module 700 from the upstream side to the downstream side of the flow path.

In addition, in acceleration mode, hill-climbing mode, etc., when the vehicle is running, the amount of heat generated by the electric devices included in the power conversion circuit of the present embodiment increases in the order of the capacitor, reactor 510, and power module 700. FIG. In particular, the amount of heat generated from a capacitor, regardless of the running mode, is smaller than that of any electrical equipment forming a power conversion circuit.

<Effect>
As described above, in the z-direction, the capacitor case 307 faces only the first flow path 831 , the reactor 510 faces only the second flow path 833 , and the power module 700 faces only the third flow path 835 .

When two of the electrical devices face one flow path, the two electrical devices share the coolant flowing through the one flow path. As a result, heat is easily transferred from the electrical device with the larger amount of heat generation to the electrical device with the smaller amount of heat generation through the refrigerant. The temperature of electrical equipment that generates less heat tends to rise.

However, in this embodiment, each of the three electrical devices faces only one channel. An electrical device tends to actively exchange heat only with a coolant flowing through one flow path that it faces. In other words, it is difficult for the electrical equipment to positively exchange heat with the non-facing flow path. Therefore, heat conduction between electrical devices is suppressed via the coolant flowing through one flow path.

As shown in FIG. 2, in particular, the first flow path 831 is located upstream of the second flow path 833 and the third flow path 835, respectively. As described above, in the z-direction, the capacitor case 307 faces only the first flow path 831, the reactor 510 faces only the second flow path 833, and the power module 700 faces only the third flow path 835. FIG.

Therefore, among the capacitor, reactor 510, and power module 700, the capacitor that generates the least amount of heat is positioned upstream of reactor 510 and power module 700, respectively. Therefore, the heat of each of reactor 510 and power module 700 located downstream is suppressed from being conducted to the condenser located upstream via the refrigerant.

Also, the condenser exchanges heat between the surface of the condenser case 307 and the outside air. The larger the surface area of the capacitor case 307, the higher the heat dissipation effect, and the smaller the surface area, the lower the heat dissipation effect. As described above, in the capacitor, heat conduction from reactor 510 and power module 700 provided downstream is suppressed. This makes it difficult for the temperature of the capacitor to rise. Thereby, the surface area of the capacitor case 307 can be reduced. An increase in the size of capacitor case 307 is suppressed.

As shown in FIG. 2, on the downstream side of the first flow path 831 of the cooling path 830, the second flow path 833 and the third flow path 835 are connected in order from the inlet 830a to the outlet 830b. The reactor 510 faces the second flow path 833 as described above. The power module 700 faces the third channel 835 . Therefore, the electric devices are arranged in the order of the reactor 510 and the power module 700 in the direction from the inflow port 830a to the outflow port 830b. In this way, the three electrical devices are cooled by the coolant in order from the electrical device with the least amount of heat generation.

Reactor 510 is cooled by the refrigerant that has exchanged heat with the condenser. Power module 700 is cooled by the refrigerant heat-exchanged with condenser and reactor 510 . The temperature of the coolant flowing between reactor 510 and power module 700 located downstream of reactor 510 is higher than the temperature of the coolant flowing between the condenser and reactor 510 located downstream of the condenser.

In this way, the electrical devices that generate less heat are cooled by the coolant from the upstream side to the downstream side, so that the temperature of the coolant that flows downstream is less likely to rise. As a result, it is possible to suppress the difficulty of heat exchange between the electrical equipment provided downstream and the refrigerant. A rise in the temperature of electrical equipment provided on the downstream side is suppressed.

Although the preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present disclosure.

(First modification)
As shown in FIG. 4, the power conversion unit 300 has a cooler 710 in addition to the constituent elements described so far. Cooler 710 has a supply pipe 710a, a discharge pipe 710c, and a plurality of relay pipes 710b.

The supply pipe 710a and the discharge pipe 710c extend in the x direction. The supply pipe 710a and the discharge pipe 710c are separated in the y direction. Each of the plurality of relay pipes 710b extends along the y direction from the supply pipe 710a toward the discharge pipe 710c.

As shown in FIG. 5, one end of the supply pipe 710a protrudes outside the frame portion 820. As shown in FIG. One end of the supply pipe 710a and one end of the third channel 835 on the outflow port 830b side are connected by a connecting pipe (not shown). Therefore, the refrigerant discharged from the outlet 830b is supplied to the supply pipe 710a through this connecting pipe. The coolant supplied to the supply pipe 710a flows through a plurality of relay pipes 710b to the discharge pipe 710c and is discharged to the outside.

A plurality of relay pipes 710b are spaced apart in the x direction and arranged side by side. A gap is formed between two adjacent relay pipes 710b. Cooler 710 has a total of six air gaps. An A-phase leg 521, a B-phase leg 522, a C-phase leg 523, a U-phase leg 611, a V-phase leg 612, and a W-phase leg 613, which constitute a package, are individually provided in each of these gaps.

Each of these six packages contacts the junction tube 710b in the x-direction. As a result, the heat generated in the six-phase leg can be radiated to the refrigerant through the relay pipe 710b.

Therefore, power module 700 can exchange heat with cooler 710 in addition to heat exchange with the refrigerant flowing through third flow path 835 . Heat is easily dissipated from the legs of the power module 700 . As a result, the temperature rise of power module 700 is easily suppressed.

Note that the form of connection of the first to third flow paths 831 to 835 is not limited to the above. For example, as shown in FIG. 6, the first channel 831, the third channel 835, and the second channel 833 may be connected and arranged in series in the direction extending from the inlet 830a toward the outlet 830b.

(Other modifications)
In this embodiment, an example in which the power conversion unit 300 has all the components of the power conversion circuit shown in FIG. 1 is shown. However, power conversion unit 300 may include the components of converter 500 and may not include the components of inverter 600 .

In this embodiment, an example in which the power conversion unit 300 is included in the vehicle-mounted system 100 for an electric vehicle is shown. However, application of the power conversion unit 300 is not particularly limited to the above example. For example, a configuration in which power conversion unit 300 is included in a hybrid system that includes motor 400 and an internal combustion engine may be employed.

In this embodiment, the configuration in which the power conversion unit 300 is connected to one motor 400 is shown. However, a configuration in which power conversion unit 300 is connected to a plurality of motors 400 can also be adopted. In this case, power conversion unit 300 includes a plurality of inverters 600 .

305... First capacitor, 306... Second capacitor, 510... Reactor, 524... First high side switch, 525... First low side switch, 614... Second high side switch, 615... Second low side switch, 700... Power module , 830... cooling path, 831... first flow path, 832... first connection flow path, 833... second flow path, 834... second connection flow path, 835... third flow path

Claims (4)

a power module (700) having a plurality of switches (524, 525, 614, 615);
a capacitor (305, 306) electrically connected to each of the plurality of switches;
a reactor (510) electrically connected to the plurality of switches;
A case (800) having a bottom (810) having a first main surface (810a) overlapping with the power module, the capacitor, and the reactor, and a second main surface (810b) behind the first main surface. )and,
a cooling passage (830) through which a coolant for cooling each of the power module, the condenser, and the reactor flows;
The cooling path is configured inside the bottom portion between the first main surface and the second main surface,
the cooling channel has a first channel (831), a second channel (833) and a third channel (835);
the first flow path, the second flow path, and the third flow path are arranged in series;
the first flow path only faces at least a portion of the condenser;
the second flow path faces only at least part of the reactor,
A power conversion unit in which the third flow path faces only at least part of the power module. the amount of heat generated by the capacitor is less than the amount of heat generated by each of the reactor and the power module;
2. The power conversion unit according to claim 1, wherein a coolant is supplied to said first flow path from the outside. the amount of heat generated by the reactor is less than the amount of heat generated by the power module;
3. The power conversion unit according to claim 2, wherein the first flow path, the second flow path, and the third flow path are serially connected in order. The cooling channel has a first connecting channel (832) and a second connecting channel (834) in addition to the first channel, the second channel, and the third channel,
The first flow path is connected to the second flow path via the first connection flow path,
4. The power conversion unit according to claim 3, wherein said second flow path is connected to said third flow path via said second connection flow path.

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