JP2020141540A - Power converter - Google Patents

Abstract

To provide a power converter in which a whole apparatus can be expected to be miniaturized by cooling a plurality of semiconductor modules and the other heating components with one kind of cooler.SOLUTION: A power converter 2 is provided with a plurality of cooling pipes 51, a plurality of semiconductor modules 8, and a heating component. Each of the cooling pipes 51 has a quadrangular cylinder shape or an octagonal cylinder shape. The cooling pipes 51 are extended in parallel while ensuring a gap. Each of the semiconductor modules 8 is interposed between cooling pipes 51 adjacent thereto. The heating component such as a reactor 7 is in contact with a surface of a cooling pipe 51 which faces a direction crossing both an alignment direction and an extension direction of the cooling pipes 51. The power converter 2 disclosed by the present specification can cool the semiconductor modules 8 and the heating component (the reactor 7 or the like) with one kind of cooler (the cooling pipes 51 having the quadrangular cylinder shape), and therefore a whole apparatus can be expected to be miniaturized.SELECTED DRAWING: Figure 2

Description

The techniques disclosed herein relate to power converters.

The power conversion device includes a large number of heat-generating components, and includes a cooler for cooling the heat-generating components. Typical heat-generating components are semiconductor modules for power conversion, reactors, capacitors, and the like. The power conversion devices of Patent Documents 1 and 2 employ a structure in which a plurality of semiconductor modules are cooled by a first cooler and a reactor and a capacitor are cooled by a second cooler. The plurality of semiconductor modules and the plurality of first coolers are alternately laminated one by one to form a lamination unit. The second cooler is larger and flatter than the first cooler, and heat-generating parts such as a reactor and a condenser are in contact with each of the pair of wide surfaces.

JP-A-2017-152612 Japanese Unexamined Patent Publication No. 2015-042131

The power conversion device of Patent Documents 1 and 2 includes two types of coolers, and it is difficult to miniaturize the device. The present specification provides a power conversion device that can be expected to reduce the size of the entire device by cooling a plurality of semiconductor modules and other heat-generating components with one type of cooler.

The power conversion device disclosed in the present specification includes a plurality of cooling pipes, a plurality of semiconductor modules, and heat generating components. Each of the plurality of cooling pipes has a square cylinder shape or an octagonal cylinder shape. Multiple cooling pipes extend in parallel. The plurality of semiconductor modules are arranged along the arrangement direction of the plurality of cooling pipes, and are sandwiched between adjacent cooling pipes. The heat generating component is in contact with the surface of the cooling pipes facing in a direction intersecting both the arrangement direction and the extension direction of the plurality of cooling pipes. The plurality of cooling pipes have a surface facing the alignment direction (first surface) and a surface facing both the arrangement direction and the extension direction (second surface), and the semiconductor module has a plurality of cooling surfaces. It is arranged so as to be in contact with the first surface of the pipe, and the heat generating component is arranged so as to be in contact with the second surface. In the power conversion device disclosed in the present specification, a plurality of semiconductor modules and heat generating parts can be cooled by one type of cooler (multiple cooling pipes of a square cylinder or an octagonal cylinder), so that the entire device can be miniaturized. You can expect it.

Details and further improvements to the techniques disclosed herein will be described in the "Modes for Carrying Out the Invention" section below.

It is a circuit diagram of the electric vehicle including the power conversion device of an Example. It is a top view of the power conversion device. It is a side view of the power conversion device. FIG. 2 is a cross-sectional view taken along the line IV-IV of FIG. It is a partial cross-sectional view of the power conversion apparatus of a modification.

The power conversion device of the embodiment will be described with reference to the drawings. The power conversion device 2 of the embodiment is mounted on an electric vehicle having two motors for traveling. FIG. 1 shows a circuit diagram of a power system of an electric vehicle 100 including the power conversion device 2 of the embodiment.

The electric power conversion device 2 of the embodiment is a device mounted on the electric vehicle 100 and converts the electric power of the main battery 81 into the driving electric power of the motors 83a and 83b for traveling. The power conversion device 2 includes two sets of inverter circuits 13a and 13b corresponding to the two traveling motors 83a and 83b. The outputs of the two motors 83a and 83b are combined by the gearbox 85 and transmitted to the axle 86 (that is, the drive wheels).

The power conversion device 2 is connected to the main battery 81 (described later, the power conversion device 2 is also connected to the sub battery 82). The power conversion device 2 includes a voltage converter circuit 12 that boosts the voltage of the main battery 81, two sets of inverter circuits 13a and 13b that convert DC power after boosting into alternating current, and a buck converter 27.

The voltage converter circuit 12 boosts the voltage applied to the terminal on the battery side and outputs it to the terminal on the inverter side, and steps down the voltage applied to the terminal on the inverter side and outputs it to the terminal on the battery side. It is a bidirectional DC-DC converter capable of performing both step-down operations. For convenience of explanation, in the following, the terminal on the battery side (low voltage side) will be referred to as an input terminal 18, and the terminal on the inverter side (high voltage side) will be referred to as an output terminal 19. Further, the positive electrode and the negative electrode of the input end 18 are referred to as an input positive electrode end 18a and an input negative electrode end 18b, respectively. The positive electrode and the negative electrode of the output end 19 are referred to as an output positive electrode end 19a and an output negative electrode end 19b, respectively. The notations "input end 18" and "output end 19" are for convenience of explanation, and as described above, since the voltage converter circuit 12 is a bidirectional DC-DC converter, the output end Power may flow from 19 to the input end 18.

The voltage converter circuit 12 is composed of a series circuit of two switching elements 9a and 9b, a reactor 7, a filter capacitor 5, and a diode connected in antiparallel to each switching element. One end of the reactor 7 is connected to the input positive electrode end 18a, and the other end is connected to the midpoint of the series circuit. The filter capacitor 5 is connected between the input positive electrode end 18a and the input negative electrode end 18b. The input negative electrode end 18b is directly connected to the output negative electrode end 19b. The switching element 9b is mainly involved in the step-up operation, and the switching element 9a is mainly involved in the step-down operation. Since the voltage converter circuit 12 of FIG. 1 is well known, detailed description thereof will be omitted. The circuit in the range of the broken line rectangle indicated by reference numeral 8a corresponds to the semiconductor module 8a described later. Reference numerals 25a and 25b indicate power terminals extending from the semiconductor module 8a. Reference numeral 25a indicates a power terminal (positive electrode terminal 25a) conducting with the high potential side of the series circuit of the switching elements 9a and 9b. Reference numeral 25b represents a power terminal (negative electrode terminal 25b) conducting with the low potential side of the series circuit of the switching elements 9a and 9b. The notation of positive electrode terminal 25a and negative electrode terminal 25b is also used in other semiconductor modules.

The inverter circuit 13a has a configuration in which three sets of series circuits of two switching elements are connected in parallel. The switching elements 9c and 9d, the switching elements 9e and 9f, and the switching elements 9g and 9h form a series circuit, respectively. Diodes are connected in anti-parallel to each switching element. The high potential side terminal (positive electrode terminal 25a) of the three sets of series circuits is connected to the output positive electrode end 19a of the voltage converter circuit 12, and the low potential side terminal (negative electrode terminal 25b) of the three sets of series circuits is voltage. It is connected to the output negative electrode end 19b of the converter circuit 12. A three-phase alternating current (U phase, V phase, W phase) is output from the midpoint of the three sets of series circuits. Each of the three sets of series circuits corresponds to the semiconductor modules 8b, 8c, and 8d described later.

Since the configuration of the inverter circuit 13b is the same as that of the inverter circuit 13a, the specific circuit is not shown in FIG. Similar to the inverter circuit 13a, the inverter circuit 13b also has a configuration in which three sets of series circuits of two switching elements are connected in parallel. The terminal on the high potential side of the three sets of series circuits is connected to the output positive end 19a of the voltage converter circuit 12, and the terminal on the low potential side of the three sets of series circuits is connected to the output negative end 19b of the voltage converter circuit 12. Has been done. The hardware corresponding to each series circuit is referred to as a semiconductor module 8e, 8f, 8g.

A smoothing capacitor 6 is connected in parallel to the input ends of the inverter circuits 13a and 13b. In other words, the smoothing capacitor 6 is connected in parallel to the output terminal 19 of the voltage converter circuit 12. The smoothing capacitor 6 eliminates the pulsation of the current flowing between the voltage converter circuit 12 and the inverter circuits 13a and 13b.

The switching elements 9a-9h are transistors, typically IGBTs (Insulated Gate Bipolar Transistors), but may be other transistors, for example, MOSFETs (Metal Oxide Semiconductor Field Effect Transistors). Further, the switching element referred to here is used for power conversion, and is sometimes called a power semiconductor element. The same applies to the switching element included in the semiconductor module 8e-8g.

At the AC output ends of the two sets of inverter circuits 13a and 13b, a current sensor 26 for measuring the three-phase AC current output by each inverter circuit is provided. The measured value of the current sensor is sent to a controller (not shown). The controller controls the switching elements 9a-9h so that the outputs of the two sets of inverter circuits 13a and 13b follow the target current while monitoring the measured values of the current sensor 26.

In FIG. 1, each of the broken lines 8a-8g corresponds to a semiconductor module. The power conversion device 2 includes seven sets of a series circuit of two switching elements. As hardware, two switching elements constituting a series circuit and diodes connected in antiparallel to each switching element are housed in one package (that is, the main body of the semiconductor module). Hereinafter, when any one of the semiconductor modules 8a to 8g is shown without distinction, it is referred to as the semiconductor module 8.

The high potential side terminal (positive electrode terminal 25a) of the seven semiconductor modules (7 sets of series circuits) is connected to the positive electrode of the smoothing capacitor 6, and the low potential side terminal (negative electrode terminal 25b) is the negative electrode of the smoothing capacitor 6. Connected to the electrode. In FIG. 1, the conductive path in the broken line indicated by reference numeral 30 corresponds to a bus bar (positive electrode bus bar 30) that interconnects the positive electrode terminals 25a of the plurality of semiconductor modules 8 and the positive electrode electrodes of the smoothing capacitor 6. The conductive path in the broken line indicated by reference numeral 40 corresponds to a bus bar (negative electrode bus bar 40) that connects the plurality of negative electrode terminals 25b and the negative electrode electrodes of the smoothing capacitor 6 to each other.

A step-down converter 27 is connected to the input terminal 18 of the voltage converter circuit 12. The step-down converter 27 steps down the voltage of the main battery 81 and supplies it to the sub-battery 82. The sub-battery 82 supplies power to an in-vehicle low-power device. An in-vehicle low-power device means a device that operates at a voltage much lower than the output voltage of the main battery 81, such as a room lamp or a car navigation system. Such low power equipment is sometimes called an auxiliary machine. The output voltage of the sub-battery 82 is typically 12 or 24 volts. Although the circuit diagram is omitted in FIG. 1, the step-down converter 27 is an isolated converter that uses a transformer to maintain and transform the insulation between the input end and the output end.

The switching element 9a-9h (semiconductor module 8), the reactor 7, the smoothing capacitor 6, and the buck converter 27 generate a large amount of heat because a large amount of power flows from the main battery 81. The power conversion device 2 also includes a cooler for cooling those heat-generating components. Next, the hardware structure of the heat generating component and the cooler described above will be described.

FIG. 2 shows a plan view of the power conversion device 2. FIG. 3 shows a side view of the power conversion device 2. FIG. 4 shows a cross-sectional view taken along the line IV-IV of FIG. In FIG. 2-4, the housing of the power conversion device 2 is not shown. Further, since the structure of the heat generating component and the cooler will be mainly described below, some components such as the control board that realizes the controller are not shown and described in FIG. 2-4.

The power conversion device 2 includes a cooler 50 having a plurality of cooling pipes 51. The cooler 50 cools the semiconductor module 8, the reactor 7, the smoothing capacitor 6, and the buck converter 27. The cooler 50 also cools the current sensor 26 and the terminal block 28 (described later).

The cooler 50 includes a plurality of cooling pipes 51 extending along the X direction of the coordinate system in the drawing. Both ends of the plurality of cooling pipes 51 are connected by a pair of connecting pipes 52. The pair of connecting pipes 52 support the plurality of cooling pipes 51 so as to be parallel to each other. The adjacent cooling pipes 51 are supported so that the facing surfaces are parallel to each other. The plurality of cooling pipes 51 are arranged in the Y direction of the coordinate system in the figure. A gap G is secured between the adjacent cooling pipes 51 (see FIG. 2).

One connecting pipe 52 is provided with a refrigerant supply port 53a, and the other connecting pipe 52 is provided with a refrigerant discharge port 53b. As shown in FIG. 4, the cooling pipe 51 has a square tubular shape, and the refrigerant passes through the internal space. The connecting pipe 52 also has a hollow inside, and communicates the refrigerant supply port 53a (refrigerant discharge port 53b) with each cooling pipe 51. The refrigerant supplied from the refrigerant supply port 53a is distributed to all the cooling pipes 51 through one connecting pipe 52. The refrigerant that has passed through the cooling pipe 51 is discharged from the refrigerant discharge port 53b through the other connecting pipe 52.

As described above, a gap G is secured between the adjacent cooling pipes 51. The semiconductor module 8 is arranged in the gap G. In other words, the semiconductor module 8 is sandwiched between the adjacent cooling pipes 51. The semiconductor module 8 is flat and is sandwiched between adjacent cooling pipes 51 in a posture in which the lateral direction coincides with the arrangement direction of the cooling pipes 51 (the Y direction of the coordinate system in the drawing). As shown in FIG. 2, the cooler 50 has seven gaps G, and one semiconductor module 8 is sandwiched in each gap G. The plurality of semiconductor modules 8 are arranged along the arrangement direction of the cooling pipes 51 (Y direction in the drawing), and are sandwiched between the adjacent cooling pipes 51. Each semiconductor module 8 is cooled from both sides by two adjacent cooling pipes 51.

The cooling pipe 51 has a square tubular shape and has a pair of parallel surfaces 51a and 51b (see FIG. 4). For convenience of explanation, the surfaces of the cooling pipe 51 facing the Y direction are referred to as side surfaces 51a and 51b, the surfaces facing the + Z direction are referred to as the upper surface 51c, and the surfaces facing the −Z direction are referred to as the lower surface 51d. In FIG. 4, the side surface 51a and the lower surface 51d are shown by the cooling pipe 51 at the right end, the side surface 51b and the upper surface 51c are shown by the cooling pipe 51 at the left end, and the remaining surfaces are designated by reference numerals. Omitted. All cooling pipes have side surfaces 51a, 51b, an upper surface 51c and a lower surface 51d. The semiconductor module 8 is sandwiched between the side surfaces 51a and 51b of the adjacent cooling pipes 51.

The upper surfaces 51c of the plurality of cooling pipes 51 are aligned on one plane, and the condenser module 31, the reactor 7, and the terminal block 28 are in contact with the upper surfaces 51c. The smoothing capacitor 6 of FIG. 1 is stored in the capacitor module 31. The positive electrode bus bar 30 described above extends from the capacitor module 31 in a branch shape, and each branch is connected to the positive electrode terminal 25a of the semiconductor module 8. The negative electrode bus bar 40 described above extends from the capacitor module 31 in a branch shape, and each branch is connected to the negative electrode terminal 25b of the semiconductor module 8. The branched positive electrode bus bar 30 is connected inside the capacitor module 31 and is connected to one electrode of the smoothing capacitor 6. The branched negative electrode bus bar 40 is also connected inside the capacitor module 31 and is connected to the other electrode of the smoothing capacitor 6.

In addition to the condenser module 31, the reactor 7 and the terminal block 28 are also in contact with the upper surfaces 51c of the plurality of cooling pipes 51. The terminal block 28 is a module for connecting the AC output terminals of the two sets of inverter circuits 13a and 13b of FIG. 1 and the power cable extending from the motors 83a and 83b (see FIG. 1). The condenser module 31, the reactor 7, and the terminal block 28 come into contact with the upper surfaces 51c of the plurality of cooling pipes 51 and are cooled.

The lower surfaces 51d of the plurality of cooling pipes 51 are also aligned on one plane, and the current sensor 26 and the step-down converter 27 are in contact with the lower surfaces 51d. Another bus bar extends from the current sensor 26 and is connected to a power terminal 25c extending from the lower surface of the semiconductor module 8. The power terminal 25c is electrically connected to the midpoint of the series circuit of the two switching elements housed in the semiconductor module 8.

The current sensor 26 and the step-down converter 27 are in contact with the lower surfaces 51d of the plurality of cooling pipes 51 and are cooled.

As described above, in the power conversion device 2, the plurality of semiconductor modules 8 and other heat generating components (capacitor module 31, reactor 7, current sensor 26, buck converter 27) are one cooling having a plurality of cooling pipes 51. It is cooled by the vessel 50. The cooling pipe 51 has a square tubular shape. The plurality of cooling pipes 51 extend in parallel while ensuring a gap G. The plurality of semiconductor modules 8 are arranged in a row along the arrangement direction of the cooling pipes 51 (Y direction of the coordinate system in the drawing), and are sandwiched between the adjacent cooling pipes 51. The semiconductor module 8 is cooled in contact with the surfaces (side surfaces 51a and 51b) facing the arrangement direction of the cooling pipes 51.

Some heat-generating components (capacitor module 31, reactor 7, terminal block 28) face in a direction (Z direction) that intersects both the arrangement direction (Y direction) and the extension direction (X direction) of the cooling pipe 51. It is cooled in contact with (upper surface 51c).

The other heat-generating components (current sensor 26, buck converter 27) are cooled in contact with another surface (lower surface 51d) of the cooling pipe 51 facing the Z direction.

As described above, in the power conversion device 2, one type of cooler 50 can cool a plurality of semiconductor modules 8 and other heat-generating components (capacitor module 31, reactor 7, terminal block 28, etc.). it can. Therefore, there is a possibility that the overall size of the power converter 2 can be reduced.

Further, the plurality of cooling pipes 51 extending in parallel across the gap G have surfaces in four directions in contact with separate heat generating parts. Since the four surfaces of each cooling pipe 51 are used for cooling, the cooler 50 has good space efficiency. Further, a bus bar or a cable for electrically connecting the upper surface side component and the lower surface side component of the cooling pipe 51 can be passed through the gap G between the adjacent cooling pipes 51. That is, the plurality of cooling pipes 51 extending in parallel while securing the gap G are also advantageous in arranging the bus bar and the cable for connecting the parts. Further, when a bus bar or the like is passed between adjacent cooling pipes 51, the bus bar can be cooled by bringing the bus bar into contact with the cooling pipe 51 via an insulating layer.

FIG. 5 shows a partially enlarged cross-sectional view of the power conversion device 2a of the modified example. The power conversion device 2a includes a cooler 60. The cooler 60 includes a plurality of cooling pipes 61 extending parallel to the X direction of the coordinate system in the drawing. FIG. 5 is a cross-sectional view of the power conversion device 2a cut in a plane orthogonal to the extending direction (X direction) of the cooling pipe 61.

Each of the plurality of cooling pipes 61 has an octagonal tubular shape. Refrigerant flows inside the cooling pipe 61. The plurality of cooling pipes 61 are arranged so that the side surfaces 61a and 61b are parallel to each other. The semiconductor module 8 is sandwiched between adjacent cooling pipes 61. The upper surfaces 61c of the plurality of cooling pipes 61 are aligned on one plane, and another heat generating component 64 is in contact with the upper surfaces 61c. The lower surfaces 61d of the plurality of cooling pipes 61 are also aligned on another plane, and another heat generating component 65 is in contact with the lower surface 61d. The heat generating components 64 and 65 are, for example, the reactor 7 of the power conversion device 2 of the embodiment, the capacitor module 31, the terminal block 28, the current sensor 26, and the buck converter 27. The power conversion device 2a of the modified example also has the same effect as the power conversion device 2 of the embodiment.

The points to be noted regarding the technique described in the examples will be described. The octagonal tubular cooling pipe 61 shown in FIG. 5 may be described as having a square tubular shape with the corners cut off. For the cooler 50, a plurality of square tubular pipes having rounded corners and chamfers may be used.

The plurality of cooling pipes 51 may be made of a material having high thermal conductivity (for example, aluminum or copper). On the other hand, the connecting pipe 52, the refrigerant supply port 53a, and the refrigerant discharge port 53b, which do not contribute to the cooling of the parts, are preferably made of a material (for example, resin) having a low thermal conductivity. The temperature rise of the refrigerant can be suppressed when passing through the connecting pipe 52, the refrigerant supply port 53a, and the refrigerant discharge port 53b.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples illustrated above. The technical elements described in the present specification or 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 techniques illustrated in the present specification or drawings can achieve a plurality of purposes at the same time, and achieving one of the purposes itself has technical usefulness.

2, 2a: Power converter 5: Filter capacitor 6: Smoothing capacitor 7: Reactor 8, 8a-8g: Semiconductor module 9a-9h: Switching element 12: Voltage converter circuit 13a, 13b: Inverter circuit 25a: Positive electrode terminal 25b: Negative electrode Terminal 25c: Power terminal 26: Current sensor 27: Step-down converter 28: Terminal block 30: Positive electrode bus bar 31: Capacitor module 40: Negative electrode bus bar 50, 60: Cooler 51, 61: Cooling pipe 52: Connecting pipe 53a: Refrigerator supply port 53b: Capacitor discharge ports 64, 65: Heat generating parts 81: Main battery 82: Sub battery 100: Electric vehicle G: Gap

Claims (1)

Multiple cooling pipes in the shape of a square or octagon, which extend in parallel,
A plurality of semiconductor modules for power conversion arranged along the arrangement direction of the plurality of cooling pipes, each of which is sandwiched between adjacent cooling pipes, and a plurality of semiconductor modules.
A heat-generating component in contact with the surface of the cooling pipe facing a direction intersecting both the alignment direction and the extension direction of the cooling pipe.
Equipped with a power converter.

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