JP6326618B2 - Power converter - Google Patents

Description

The present invention relates to noise countermeasures for a power conversion device that converts DC power into AC power by turning on / off a plurality of switching elements.

Conventionally, the electromagnetic noise radiated when the switching element is turned ON / OFF is generally simply attenuated by a shielding plate. However, in a power converter having a large output, the amount of electromagnetic noise radiated is not sufficient. There wasn't. Japanese Patent Application Laid-Open No. H10-228561 describes a device in which a heat generating component such as an inverter coil is placed in a recess formed in a die-cast housing and then covered.

US Pat. No. 7,715,195

In the device described in Patent Document 1, when a coil is formed as a reactor of a booster circuit, or when it is formed as a reactor of a filter circuit that absorbs a high frequency component due to ON / OFF of a switching element, electromagnetic noise is generated from this coil. Radiated. This electromagnetic noise hits the inner wall of the recess and attenuates it, but does not attenuate the electromagnetic noise radiated from the switching element.

The present invention provides a power conversion device that attenuates electromagnetic noise radiated from a coil (reactor), a switching element disposed in the vicinity of the coil, and the like.

The power converter of the present invention is a power converter that converts DC power into a pseudo sine wave using a plurality of switching elements, and then converts the DC power into AC power through a low-pass filter and a noise filter. The electric circuit board is arranged in a first recess provided on the bottom surface of the die-cast housing so that at least the soldered wiring pattern side of the electric circuit board enters the first recess, and the electrical component is A first sheet metal having the same potential as that of the housing is arranged above the mounted anti-wiring pattern side, and a reactor that forms the low-pass filter is arranged in a second depression in the vicinity of the first depression. Is covered with a second sheet metal having the same potential as that of the first sheet metal.

In the power conversion device of the present invention, electromagnetic noise radiated from above and below the electrical board can be absorbed by making the die-cast casing and the sheet metal have the same potential.

FIG. 1 is an explanatory diagram of an electric circuit used in a power converter according to an embodiment of the present invention. FIG. 2 is a front view of the casing of the power conversion device according to the embodiment of the present invention. 3 is a rear view of the housing shown in FIG. FIG. 4 is an explanatory view showing a state in which the electrical board is attached to the housing shown in FIG. FIG. 5 is an explanatory view showing a state in which an electrical board is further attached to the housing shown in FIG. FIG. 6 is an explanatory view showing a cross section of the housing shown in FIG.

According to the present invention, a reactor is housed in a hollow of a die-cast casing, and an electrical board is housed in a nearby recess, and the upper part is covered with a sheet metal of the same potential to suppress noise.

FIG. 1 is an explanatory diagram of an electric circuit used in a power conversion apparatus according to an embodiment of the present invention. In this electric circuit, 1 is a DC power source such as a solar cell, 2 is a plurality of capacitors (not shown), a reactor 3 It is a noise filter comprised from these.

Reference numeral 4 is a diode, 5 is a reactor, 6 is a smoothing condenser, and 7 is a switching element, which constitutes a chopper type booster circuit and boosts DC power input via the noise filter 2. This boosting is performed by changing the ON duty when the switching element 7 is turned ON / OFF at a predetermined cycle, and the output is output to the intermediate voltage points 8 and 9.

A series of input circuits 10 corresponding to a DC power source (solar cell string) are constituted by a noise filter and a booster circuit, and in this embodiment, four input circuits (not shown) are mounted in this embodiment. The output is integrated at the intermediate voltage points 8 and 9 and supplied to the single-phase bridge circuit 11. Note that the capacitor 6 of the booster circuit can be used in common at the intermediate voltage position.

The single-phase bridge circuit 11 connects the switching elements 12 to 15 in a single-phase bridge shape, and each of them is periodically turned ON / OFF to convert DC power into AC power using a single-phase pseudo sine wave. Note that this DC power-AC power conversion method is not limited to this embodiment, and various methods such as an intermediate voltage clamp method and a gradation method can be used.

Reference numerals 17 and 18 denote reactors, which together with the capacitor 19 constitute a low-pass filter.
Reference numeral 20 denotes a noise filter, which is composed of a capacitor (reference numeral omitted) and a reactor (reference numeral omitted). The noise filters 2 and 20 are not limited to the circuit shown in FIG.
The effect can be achieved with just the condenser, and it can be designed appropriately according to the corresponding frequency and output.

Reference numeral 21 denotes an electric power system, and the noise filter 20 is connected via the contact pieces 22 and 23 of the grid interconnection relay.
AC power output from is supplied.

In such an electric circuit, the switching element 7 of the booster circuit and the switching elements 12 to 15 of the single-phase bridge circuit 11 are turned ON / OFF at high speed, whereby electromagnetic noise is radiated from these switching elements and these electromagnetic noises (high frequency The component) is also radiated to the surroundings from coil portions such as the low-pass filter reactors 17 and 18 and the boosting reactor 5.

FIG. 2 is a front view of the casing 31 of the power conversion device according to the embodiment of the present invention, and FIG.
1 is a rear view of FIG. The housing 31 is integrally formed by die casting of aluminum or aluminum alloy, but can be integrally formed by assembling a plurality of parts.

A recess 32 (corresponding to a first recess) for housing an electrical component board to which electrical components constituting a low-pass filter capacitor 19 and a noise filter 20 are soldered and reactors 17 and 18 constituting the low-pass filter are formed on the inner surface of the housing 31. A recess 33 (corresponding to a second recess) to be housed is configured. Further, the wiring board is soldered to the wiring pattern so that the side of the wiring pattern enters the recess 32.

Further, a recess 34 for storing the reactor 5 constituting the booster circuit of the input circuit 10 (the reactor for four input circuits is stored in this recess) and the switching elements 12 to 15 on the bottom surface inside the casing 31. A base 35 for mounting the module containing the battery is configured.

Reference numeral 36 denotes a wiring port, which is configured so that a DC wiring can be drawn from the DC power source 1 and an AC wiring connected to the power system 21 can be taken out. Reference numeral 37 denotes an attachment portion of an electrical board that constitutes the noise filter 2, the input circuit 10, and the like. A rising portion 38 is die-cast integrally with the housing 31 between the electrical board and the electrical board housed in the recess 32.

A plurality of heat dissipating fins 39 are integrally formed on the back surface of the housing 31 in the vertical direction. These fins 39 are mainly formed corresponding to the depressions 33 and 34 and the base 25, and the reactors 5, 17, 1
8. Contributes to heat dissipation of the switching elements 12-15. Further, the heat dissipation of the switching element 7 is also configured.

In FIG. 4, reference numeral 40 denotes an electrical board that constitutes four circuits by combining at least the input circuit 10 and other input circuits. The reactor 3 of the noise filter 2 and the reactor 3 b of the other input circuit.
~ 3d and electrical components such as capacitors are mounted. The electrical board 40 is screwed to the bottom surface of the housing 31 via a spacer.

The reactor 5 constituting the booster circuit is housed in the recess 34 together with booster reactors 5b to 5d of other input circuits. The recess 34 is filled with a synthetic resin having good thermal conductivity to improve heat dissipation to the fins 39 on the back surface, and suppresses vibrations that resonate or synchronize with the high frequency period when the switching element 7 is turned ON / OFF. ing.

The module 41 containing the switching elements 12 to 15 constituting the inverter circuit 11 is attached to the base portion 35 of the casing 31 with good thermal conductivity using thermal conductive grease or the like.

Reactors 17 and 18 constituting a low-pass filter are configured to share a core and are accommodated in a recess 33. The depression 33 is filled with the same synthetic resin as the depression 34 and has the same effect.

Reference numeral 42 denotes an electrical board that constitutes at least the noise filter 20, and it is possible to mount a capacitor constituting the low-pass filter and a part of its electronic components. The electrical board 42 is arranged so that at least the soldered wiring pattern side enters the recess 32 and is screwed in the same manner as the electrical board 40. The depression 33 is configured in the vicinity of the depression 32, and the reactors 17 and 18 and the electrical board 42 are connected by wiring. In addition, reactors 43 and 44 of the noise filter 20 are mounted on the electrical board 42.

5 and 6, reference numeral 45 denotes a sheet metal that covers the upper portion of the recess 34 and is screwed to the housing 31. By screwing, the metal plate 45 and the casing 31 become the same potential, and the reactors 5, 5b
The electromagnetic noise radiated from 5c and 5d is absorbed and attenuated to the ground potential of the casing 31 through the sheet metal 45.

A sheet metal 46 covers the upper portion of the recess 33 and is screwed to the housing 31. The sheet metal 46 has the same potential as the casing 31 like the sheet metal 45, and similarly electromagnetic noise radiated from the reactors 17 and 18 is attenuated.

A sheet metal 47 is disposed so as to cover the upper side of the electrical board 40 and is screwed to the casing 31 so that the sheet metal 47 and the casing 31 are at the same potential. Therefore, the electrical board 40 is sandwiched between the casing 31 and the sheet metal 47 having the same potential, and the emission of electromagnetic noise and the propagation of noise from surrounding components are suppressed.

An electrical board 48 that constitutes a control circuit such as a switching element is attached above the sheet metal 47 via a spacer. The electrical board 48 has a lid (not shown) that covers the sheet metal 47 and the open front of the housing 31. Since the lid is configured at the same potential as the casing 31, the electrical board 48 is sandwiched between the sheet metal 47 and the lid at the same potential, and electromagnetic noise is emitted and noise from surrounding components is Propagation is suppressed.

A sheet metal 49 is disposed so as to cover the upper side of the anti-wiring pattern side on which the electrical components of the electrical board 42 are mounted. The sheet metal 49 is screwed to the casing 31 so that the sheet metal 49 and the casing 31 have the same potential. Yes. Therefore, the electrical board 42 is sandwiched between the casing 31 and the sheet metal 49 having the same potential, and the emission of electromagnetic noise and the propagation of noise from surrounding components are suppressed.

An electrical board 50 that constitutes a control circuit such as a switching element is attached above the sheet metal 49 via a spacer, and the electrical board 50 is positioned between the sheet metal 49 and a cover that covers the open front surface of the housing 31. In addition, the electrical board 50 is sandwiched between the sheet metal 49 and the lid having the same potential, so that the emission of electromagnetic noise and the propagation of noise from surrounding components are suppressed.

Further, the rising portion 38 is located between the electrical board 40 and the electrical board 42 to suppress the emission and propagation of noise between these electrical boards.

Further, the electric circuit board 42 is substantially surrounded by the recess 32, the casing 31, the rising portion 38, and the sheet metal 49, and is particularly effective in suppressing the emission of electromagnetic noise. Furthermore, reactors 17 and 18
Since both are surrounded by the same potential via the housing 31, an electromagnetic noise absorbing effect can be obtained. Further, the electromagnetic noise coming out of the wiring pattern of the electrical board 42 is a depression 32.
Is absorbed.

INDUSTRIAL APPLICABILITY The present invention is suitable for reducing radiated noise of a power conversion device or the like in which a casing die-cast with an electrically conductive member such as aluminum is used to house components that easily radiate electromagnetic noise or the like. .

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 changed and improved without departing from the gist thereof, and that the present invention includes equivalents thereof.

DESCRIPTION OF SYMBOLS 1 DC power supply 17, 18 Reactor 20 Noise filter 31 Case 32 Indentation 33 Indentation 42 Electrical board 46 Sheet metal 49 Sheet metal 50 Electrical board

Claims (3)

In the power converter for converting DC power to pseudo sine wave using a plurality of switching elements and then converting the DC power to AC power through a low-pass filter and a noise filter ,
Attach the grayed element on the bottom surface of the die-cast housing, the electrical component mounted circuit board which forms the low-pass filter and said noise filter different from the location where the switching element is attached to the bottom surface
The wiring pattern soldered to the electrical circuit board is disposed so that at least the soldered wiring pattern side of the electrical circuit board enters the first cavity, and above the wiring pattern side on which the electrical component is mounted. A first sheet metal having the same potential as that of the casing is disposed, and a reactor that forms the low-pass filter is disposed in a second recess in the vicinity of the first recess, and the upper portion of the reactor has the same potential as that of the first sheet metal. A power converter characterized by covering with a second sheet metal. 2. A rising portion formed by die casting is formed around the first depression.
The power converter device described in 1. An electrical board that forms a control circuit such as a switching element is disposed above the first sheet metal,
The power conversion device according to claim 1, wherein a lid that covers an upper surface of the casing provided above the electrical board is formed at the same potential as the casing.

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