JP6528083B2 - Power converter - Google Patents

Description

  The present invention relates to a power converter.

BACKGROUND ART Conventionally, for example, a power conversion device has been proposed which converts DC power output from a DC power source such as a solar cell or a storage battery into AC power and superimposes the converted AC power on a commercial power system.

Such a power conversion device includes a DC reactor or a switching element, a booster circuit for boosting a voltage of DC power, an inverter circuit for converting DC power into AC power by full bridge connection of a plurality of switching elements, and an AC reactor. It is comprised by the filter circuit etc. which remove the high frequency component of the alternating current power which an inverter circuit outputs, and various electronic components are mounted in a board | substrate etc.

In addition, in order to prevent condensation of the power conversion device, a sealed case is equipped with a fan-equipped inlet and outlet with a waterproof moisture permeable filter, and the difference between the temperature inside the case and the temperature outside the case is at a certain level or more. Start the fan (or increase the number of rotations) if the humidity inside the case is above a certain level
There has been proposed a technique for increasing the amount of air flowing from the outside of the case to the inside of the case and from the inside of the case to the outside of the case. (See Patent Document 2).

Unexamined-Japanese-Patent No. 2013-191772

By the way, in the power converter, the switching element is operated at high frequency, AC power is
When passing through the C reactor, noise (sound) of the switching frequency or the frequency band of the commercial power system is generated. For this reason, when arranging a power conversion device indoors, the power conversion device is not placed in a room such as a living room or a bedroom where it is usually active, but is arranged in a place slightly away from the place of daily activities such as a washroom or a dressing room There is a need to move away.

However, although the above-mentioned power conversion device may be able to prevent condensation due to a temperature difference, the air outside the housing will be taken into the housing in the washroom or bath room where hot water is often used Also, there has been a problem that the humidity in the case increases and the electronic components (for example, the substrate and the like) in the case may be corroded or shorted to cause failure.

The power conversion device of the present invention is an invention made in view of such a problem, and, for example, a power conversion device having a high degree of freedom of installation with low possibility of failure near baths such as washrooms and dressing rooms. Intended to provide.

A power conversion device according to the present invention is a power conversion device for converting direct current power into alternating current power, containing an electronic component that generates heat when converting the direct current power into the alternating current power, and the electronic component. A housing provided with a second hole at the top, a wall provided around the first hole of the front housing, and a wall disposed on the wall to absorb moisture in the air A hygroscopic member such that the heat generated by the electronic component warms the inside of the housing so that the air outside the housing is convected through the first hole, the first hygroscopic member, and the second hole A power conversion device, comprising: arranging a first hygroscopic member; drying the first hygroscopic member by the convection; and discharging the water absorbed by the first hygroscopic member to the outside of the casing.

  The power converter of the present invention can provide a power converter with a high degree of freedom in installation.

It is a circuit diagram of a power converter of this example. It is a perspective view of the power converter device of a present Example. It is a disassembled perspective view of the power converter device of a present Example. It is a perspective view of the upper side panel of a present Example. It is the perspective view which looked at the front panel of a present Example from the back side. It is a perspective view of the lower side panel of a modification, and a duct.

Even if the power converter of this embodiment is exposed to steam, it is less likely to fail.
A hygroscopic member is disposed in the housing, moisture such as steam is absorbed by the hygroscopic member, and the hygroscopic portion is dried when the power conversion device is operated.

The power conversion device 1 is connected to the solar cell 30 (DC power supply), converts DC power output from the solar cell 30 into AC power, and superimposes the converted AC power on the commercial power grid 40.

The power conversion device 1 includes a booster circuit 36 for boosting a DC voltage of a solar cell to a predetermined voltage, an inverter circuit 37 for converting DC power boosted by the booster circuit 36 into AC power, and an inverter circuit 3.
A filter circuit 38 for attenuating the high frequency component of the AC power output from 7 and a relay circuit 26 for connection / disconnection with the commercial power system are provided (see FIG. 1).

The booster circuit 36 is composed of a non-insulated boost chopper circuit, and is composed of a DC reactor DCL, a switch element 36a, a diode 36b and a capacitor CON. In addition, diode 36
b uses a parasitic diode connected in anti-parallel to the switch element 36 a. The boost circuit 36 boosts the DC voltage of the solar cell by adjusting the duty ratio of the switch element 36a and periodically turning on / off the switch element 36a.

The inverter circuit 37 is formed by full bridge connection of a plurality of switch elements 37 a (four), the DC side is connected to the booster circuit 36, and the AC side is connected to the filter circuit 38. A PWM signal (Pulse Width Modulation) is given to a plurality of switch elements, and DC power is converted into AC power by periodically turning ON / OFF.

The filter circuit 38 includes two AC reactors ACL and a capacitor CN 2, and is connected to the commercial power system 40 via the relay circuit 26. The relay circuit 26 is a power converter 1
Become connected when the system is linked, and become disconnected when the power converter stops.

The booster circuit 36, the inverter circuit 37, the filter circuit 38, and the relay circuit 26.
Is appropriately mounted on the substrate 20 and housed in the housing 10.

The housing 10 includes a front cover 2, a rear panel 3, and a frame body including an upper panel 4, a lower panel 5, a right panel 7 and a left panel 8, and the periphery (end) of the rear panel 3
The frame rises up to form a rectangular box. A front opening is formed on the front side of the box, and components such as electronic components are accommodated from the front opening.

In addition, the back panel 3 includes a heat sink 2 including a base portion 21 b and a plurality of fins 21 a.
A plurality of fins 21a are formed to extend from the base portion 21b toward the back panel 3. A ventilation passage F is formed between the plurality of fins 21a. The heat sink 21 is disposed on the back panel 3 such that the ventilation path F is in the vertical direction (direction from the upper panel 4 to the lower panel 5).

Electronic components such as the booster circuit 36 and the diodes and switch elements of the inverter circuit 37 are integrated into one module IPM. Since the module IPM generates a particularly large amount of heat, it is attached to the base portion 21 b of the heat sink 21 so as to dissipate the heat of the module IPM to the outside through the fins 21 a of the heat sink 21. Heat sink 21
There are a number of spacers 23 attached to which the substrate 20 is attached. Further, the DC reactor DCL and the AC reactor ACL are disposed on the left rear panel 3 of the heat sink 21, and the relay circuit 26 is disposed on the right rear panel 3 of the heat sink 21.

Four claw portions 2 a are formed on the back side of the front cover 2, and the second claw portion 2 a is formed on the rear side of the front cover 2.
The hygroscopic sheet 27 (second hygroscopic member) is fitted and disposed (see FIG. 5). As the second hygroscopic sheet 27, a sheet containing a highly hygroscopic polymer or silica gel is used. In addition, as a material contained in the second hygroscopic sheet, materials other than silica gel (for example, quick lime, natura sorb, etc.) may be used.

The second hygroscopic sheet 27 is disposed on the front cover 2. Therefore, when the front cover 2 is attached to the box, the second hygroscopic sheet 27 is relative to electronic components such as the switch element 37a, the DC reactor DCL, and the AC reactor ACL. It will be arranged towards.

The power conversion device 1 is used by attaching the back panel 3 side to a wall of a building or the like. The lower panel 5 is formed with a plurality of first holes 5a leading to the placement location of the electronic component and a plurality of third holes 5b opposed to the inlet of the air passage F (see FIG. 3). . The upper panel 4 is formed with a plurality of second holes 4a leading to the placement location of the electronic component and a plurality of fourth holes 4b opposed to the outlet of the air passage F (see FIG. 4).

Further, a duct 29 for guiding the air entering from the outside of the housing 10 is provided at the location of the first hole 5a of the lower panel 5 (see FIG. 6). The duct 29 utilizes a columnar body having the same cross section as the shape in which the first holes 5a are distributed (in the present embodiment, an L-shaped cross section). The duct 29 has a hollow shape, and a slit 29 a is formed on the surface facing the lower panel 5. Further, a first wettable sheet 28 (first hygroscopic member) having the same physical properties as the second hygroscopic sheet 27 is provided by being attached to a wall (an example of a wall) of a duct surrounding the first hole 5a. There is. The first hygroscopic sheet 28
The physical properties of the second hygroscopic sheet may be different.

By providing such a duct 29, the moisture of the steam coming in through the slit 29 a is absorbed by the first hygroscopic sheet 28 before entering the housing 10 and then enters the housing 10. The inside of the case 10 can be dried, and the possibility of failure due to steaming is reduced.

In addition, when the power conversion device 1 operates and the electronic component comes to have heat, air outside the housing passing through the duct 29 passes through the first hygroscopic sheet 28 (or the vicinity thereof) and is provided to the lower panel 5. Taken from the first hole 5a, the first hole 5a, the inside of the housing (where the electronic component is arranged, between the electronic component and the second hygroscopic sheet 27), and the second hole 4a in this order Air convection through (
Natural convection is created, and the heat of the electronic component is released to the outside. In addition, convection (natural convection) of air passing through the third hole 5b, the air passage F, and the fourth hole 4b sequentially occurs, and the heat of the electronic component is also released to the outside by this. At this time, the moisture absorbed by the first hygroscopic sheet 28 is released from the first hygroscopic sheet 28 by the heat of the electronic component and is discharged to the outside of the housing through the first hole 5a and the second hole 4a. Ru.

When the power conversion device 1 is disposed in the bathroom or dressing room (near the bathroom), the first hole 5a
Even if steam (air with high humidity and much moisture) enters the inside of the housing through the second hygroscopic sheet 27, the moisture of the water is absorbed by the second hygroscopic sheet 27 and it is easy to keep the inside of the housing dry. .

Further, when the power conversion device 1 operates, heat is emitted from the electronic component and the inside of the case is warmed, so the moisture (water vapor) absorbed by the second hygroscopic sheet 27 and the moisture absorbed by the first hygroscopic sheet 28 Is released from the respective sheets, and the released moisture is convected from the second holes 4a (the moisture released from the first hygroscopic sheet 28 also passes through the first holes 5a) by the convection of air to the outside of the housing As it is released, the first hygroscopic sheet 28 and the second hygroscopic sheet 27 again absorb water easily, and the inside of the housing also tends to be kept dry. As described above, since the inside of the power conversion device 1 can be easily kept dry, even if the power conversion device 1 is placed near a bathroom such as a washroom or a dressing room, the possibility of failure due to steam is reduced. At this time, the moisture released from the first hygroscopic sheet 28 and the second hygroscopic sheet 27 is very small and is gradually released from the first and second hygroscopic sheets, so that the inside of the case is It does not adversely affect the electronic components of the

Further, since the second hygroscopic sheet 27 is disposed on the front cover 2, a gap is created between the heat-generating electronic component and the second hygroscopic sheet 27, and the passage of steam and the power conversion device 1 operate. Because it is a path of air convection that is generated by the water, it is easy to absorb water from the steam,
In addition, the second hygroscopic sheet can be easily dried.

Further, since the second hygroscopic sheet 27 and the electronic component generating heat are disposed to face each other, the distance between the second hygroscopic sheet 27 and the electronic component is reduced, and the heat of the power conversion device 1 is easily transmitted. , Makes it easy to dry the second hygroscopic sheet.

As mentioned above, although one Embodiment of this invention was described, the above description is for making an understanding of this invention easy, and does not limit this invention. It goes without saying that the present invention can be modified and improved without departing from the gist thereof and includes the equivalents thereof.

For example, although the duct 29 is provided on the outside of the lower panel 5 of the housing in the present embodiment, the duct 29 may be provided to extend from the lower panel 5 toward the inside (inside).

For example, in the present embodiment, the first hygroscopic sheet 28 is provided in the duct.
The first hygroscopic sheet 28 may be attached to the lower panel 5 side of the base portion 21b. The base portion 21 b of the heat sink 21 is also a wall provided around (around) the first hole 5 a, so the first portion before the moisture of the steam (air outside the housing) enters the housing 10. It can be absorbed by the hygroscopic sheet 28 to dry the inside of the case. Also,
The heat sink generates heat when the power conversion device operates, so the first hygroscopic sheet 28 is likely to be dehumidified by the heat.

Alternatively, the heat sink may be extended to the outside of the housing 10 and the first hygroscopic sheet 28 may be provided to the extended end. Furthermore, the duct 29 may be configured to hide the heat sink extended by the duct 29, and the first hygroscopic sheet 28 may be provided on the wall of the duct 29 to absorb more moisture.

The power conversion device 1 of the present embodiment can also be used as a power conversion system having a solar cell 30.

DESCRIPTION OF SYMBOLS 1 power converter 2 front cover 3 back panel 4 upper side panel 4a 2nd hole 4b 4th hole 5 lower side panel 5a 1st hole 5b 3rd hole 7 right side panel 8 left side panel 10 case 20 board 21 heat sink 21a Fin 21b Base 23 Spacer IPM Module 26 Relay Circuit 27 2nd Hygroscopic Sheet 28 1st Hygroscopic Sheet 29 Duct 30 Solar Battery 36 Boost Circuit 36a Switch Element 36b Diode 37 Inverter Circuit 37a Switch Element 38 Filter Circuit 40 Commercial Power System ACL AC reactor DCL DC reactor

Claims (5)

In a power converter that converts DC power into AC power,
An electronic component that generates heat when converting the DC power into the AC power;
A housing that accommodates the electronic component and is provided with a first hole in the lower portion and a second hole in the upper portion;
A wall provided around the first hole of the front case;
A first hygroscopic member disposed on the wall and absorbing moisture in the air;
The inside of the case is warmed by the heat generation of the electronic component, and the air outside the case is the first hole, the first
A hygroscopic member, the first hygroscopic member is disposed so as to convect through the second hole, and the moisture absorbed by the first hygroscopic member by drying the first hygroscopic member by the convection is said to be A power converter characterized by discharging to the outside of a case. A heat sink having a base portion on which the electronic component is disposed and fins for radiating the heat of the electronic component;
The power converter according to claim 1, wherein a base portion of the heat sink is provided around the first hole to form the wall. The power conversion device according to claim 1 or 2, wherein a duct for guiding air outside the housing to the first hole of the housing is provided, and a wall of the duct forms the wall. The housing comprises a box having a front opening and a front cover closing the front opening,
The power conversion device according to any one of claims 1 to 3, wherein the front cover is provided with a second hygroscopic member. The power converter according to claim 4, wherein the second hygroscopic member and the electronic component are disposed to face each other.

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