JP2010029002A - Inverter device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small and highly efficient inverter device by providing a highly efficient LC filter so as to correspond to the high efficiency of an inverter circuit. <P>SOLUTION: The inverter device 1 is provided with an inverter 11 having a switching element configured of MOSFET and converting DC power into AC power; and an LC filter 12 provided on an output stage of the inverter 11. In the inverter device 1, a reactor 12a configuring the LC filter 12 employs a core material B made of a magnetic material having a large inherent resistance, and the reactor 12a is configured of two core materials B independent from each other. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an inverter device that is connected to a power source that outputs DC power and converts DC power to AC power.

  In general, an inverter device includes an inverter circuit that converts DC power into AC power and an LC filter that removes harmonic components from the AC power output from the inverter circuit. Therefore, in order to increase the efficiency of the inverter device, it is necessary to consider the efficiency of each of the inverter circuit and the LC filter.

  Among these, for the inverter circuit, for example, an IGBT has been adopted as a switching element constituting the conventional circuit. Therefore, in order to increase the efficiency of the inverter circuit, the invention disclosed in the following Patent Document 1 employs the following configuration.

That is, a MOSFET is used as a switching element, and each parasitic diode is blocked in the inverter circuit in order to reduce a loss due to a reverse current generated in the parasitic diode connected in reverse parallel to the MOSFET by turning the MOSFET on and off. In this case, a reverse voltage application circuit for applying a reverse voltage smaller than that of the DC voltage source to each parasitic diode is provided.
Japanese Patent Laid-Open No. 10-327585

  However, in the configuration disclosed in Patent Document 1 described above, although the efficiency of the inverter circuit can be increased, the efficiency of the LC filter is not mentioned, and as a result, the entire inverter device The feeling of dropping one hand is undeniable when considering the improvement of the efficiency.

  In particular, when a MOSFET or the like is used as the switching element of the inverter circuit, the switching speed is increased. On the other hand, the increase in the switching speed increases the iron loss of the reactor that constitutes the LC filter, for example, a core material made of a silicon steel plate. This lowers the efficiency of the LC filter, and as a result, lowers the efficiency of the entire inverter device.

  Therefore, it is also conceivable to employ ferrite having a small iron loss instead of a silicon steel plate as the core material. Certainly, by using ferrite as a core material, the iron loss is reduced and the efficiency can be maintained.

  However, even if ferrite is used as a core material, if the core material is a coupling type, it is likely to be magnetically saturated, and in order to satisfy the specifications required as an LC filter, the reactor is enlarged or a capacitor is used. It will be necessary to have a large capacity. In any of these cases, the entire inverter device becomes larger and the accompanying increase in weight is inevitable.

  The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a small and high-efficiency inverter device by providing an efficient LC filter in accordance with the high efficiency of the inverter circuit. Is to provide.

  According to an embodiment of the present invention, there is provided an inverter device including an inverter configured with a switching element formed of a MOSFET and converting DC power into AC power, and an LC filter provided at an output stage of the inverter, wherein the LC filter Is used as a core material made of a magnetic material having a large specific resistance, and the reactor is made up of two core materials independent of each other.

  ADVANTAGE OF THE INVENTION According to this invention, a small and highly efficient inverter apparatus can be provided by providing efficient LC filter according to the high efficiency of an inverter circuit.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, an inverter device 1 according to an embodiment of the present invention is connected to a power source 2 that outputs DC power and a commercial power system 3 to configure a grid interconnection system S, for example. The inverter device 1 converts DC power output from the power source 2 into AC power, supplies power to a load facility (not shown) connected to the AC system, and reversely flows surplus power to the commercial power system 3. To do.

  The power source 2 is a device that outputs DC power, and may be any power generation device such as a solar cell, biomass, a fuel cell, a wind power generator, or the like.

  As shown in FIG. 1, the inverter device 1 includes an inverter 11 that converts DC power supplied from the power source 2 into AC power, and an LC filter 12 that is provided at the output stage of the inverter 11.

  The inverter 11 uses a MOSFET as a switching element. Further, a reverse voltage application circuit may be incorporated in the switching element to reduce the loss due to the reverse current generated in the parasitic diode. Furthermore, it is possible to use a super junction MOSFET having a low ON resistance instead of a MOSFET as the switching element. By doing so, it is possible to improve the characteristics particularly in the low load region.

  The LC filter 12 includes a reactor 12a and a capacitor 12b, and removes harmonic components in the output current from the inverter 11. In the embodiment of the present invention, ferrite having less iron loss than a silicon steel plate is employed as the core material of the reactor. In addition, the core material of a reactor should just be a magnetic material with a large specific resistance in which an iron loss is less than a silicon steel plate, For example, a dust core can also be employ | adopted.

  Moreover, the core material of the reactor 12a is not couple | bonded, and as shown in FIG.2 and FIG.3, two core materials are mutually independent. FIG. 2 is a schematic view showing a state where coils are wound around two independent core materials, and FIG. 3 is a cross-sectional view taken along line AA in FIG. As shown in FIGS. 2 and 3, the core materials B and B using ferrite are independent from each other without being coupled, and a coil C is wound around each of the core materials B and B.

  That is, when the core materials are joined, the coils are wound so that the magnetic fields generated by the currents flowing through the coils strengthen each other. An equivalent inductance value as a circuit can be improved by the mutual inductance generated when wound in this way.

  On the other hand, since the magnetic flux density generated in the core material is doubled due to the coupling of the core material, depending on the material used for the core material, when the load current increases (in the high load region), the magnetic saturation May occur.

  As described in the embodiment of the present invention, when ferrite is used for the core material B, the magnetic saturation is likely to occur because the saturation magnetic flux density of ferrite is generally low. Therefore, in order to eliminate such an adverse effect, for example, it is necessary to make the cross section of the core material B very large. For example, the reactor is large and expensive compared to the case where a silicon steel plate is used for the core material B. End up.

  In addition, instead of reducing the magnetic flux density generated by suppressing the inductance in the reactor, it is conceivable to increase the capacitance of the capacitor. However, it is difficult to increase the efficiency of the LC filter after all due to the reactive current flowing through the capacitor. It is.

  As described in the embodiment of the present invention, by forming the reactor 12a by making the two core materials B independent from each other, even if ferrite is used as the core material B, it becomes difficult to be in a magnetic saturation state. Moreover, since the eddy current loss of the iron loss is proportional to the square of the magnetic flux density, the core material B is made independent of the core material B without combining the core material B and the core material B is reduced. This can be reduced as compared with the case of bonding. Further, as described above, the core material B is connected to the reactor 12a by dividing the core material B into a plurality of core materials B and B, in order to achieve a desired specification. Therefore, the size of the reactor 12a can be made smaller than before.

  The reactor 12a can further fix two core materials to a frame made of a common nonmagnetic material. For example, as shown in FIG. 4, in the reactor 12a, for example, a coil C is wound around a frame D made of a nonmagnetic material such as brass, and an independent core material B is fixed. As described above, by fixing the plurality of core materials B and B to the same frame and forming a single unit, it is possible to easily attach and detach the inverter device 1 and improve workability such as maintenance.

  By adopting the configuration as described above, it is possible to provide an LC filter that is efficient in conformity with the high efficiency of the inverter circuit and can contribute to downsizing, and thus is small in size and highly efficient as a whole. An inverter device can be provided.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine the component covering different embodiment suitably.

It is a block diagram which shows the whole structure of the grid connection system which concerns on embodiment of this invention. It is a schematic diagram which shows the core material of the reactor which concerns on embodiment of this invention. It is sectional drawing which cuts and shows a core material by the AA line shown in FIG. It is a schematic diagram which shows the state which fixed the independent core material and was made into one unit.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Inverter apparatus, 2 ... Power supply, 3 ... Commercial power system, 11 ... Inverter, 12 ... LC filter, 12a ... Reactor, 12b ... Capacitor, B ... Core material, C ... Coil, D ... Unit, S ... Grid connection system

Claims (3)

An inverter device comprising: an inverter configured by a MOSFET and converting DC power to AC power; and an LC filter provided at an output stage of the inverter,
The reactor which comprises the said LC filter uses the core material which consists of a magnetic material with a large specific resistance, and the said reactor is comprised from two core materials mutually independent, The inverter apparatus characterized by the above-mentioned.   The inverter device according to claim 1, wherein the reactor is configured by fixing the two core members to a frame made of a common nonmagnetic material.   The inverter device according to claim 1, wherein the core material of the reactor is ferrite.

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