JP5164133B2 - Power converter - Google Patents

Description

  The present invention relates to a power converter that adds or adds impedance to a circuit through which a noise current flows for the purpose of reducing conductive noise or radiated noise that is conducted or radiated during switching of a power semiconductor element.

  In recent years, EMC (electromagnetic interference) regulations have become stricter, and reduction of radiation and conduction noise (also simply referred to as noise) has become a technical problem in various industrial devices including general-purpose inverters. In particular, countermeasures are required for the reduction of noise generated by switching of these main components, which are power semiconductors, and power modules on which these are mounted. One countermeasure is the insertion of a ferrite core, which is disclosed in Patent Document 1, for example.

In addition, the loops that are the sources of noise are classified into two types, normal loops and common loops. Since these loop paths are different, in order to reduce the noise current, add impedances individually. In general, measures are taken.
Therefore, if the noise current generated by the normal loop and the common loop can be reduced at one time, it is possible to reduce the number of members such as ferrite cores required for adding impedance, and it is effective in reducing cost and installation space. As techniques aiming at such an effect, for example, there are those shown in Patent Documents 2 to 4.

Japanese Patent No. 2851268 Japanese Patent No. 2671434 JP 2005-116792 A JP 2001-237130 A

Usually, as countermeasures against common mode noise and normal mode noise, it is common to add impedances such as ferrite cores to the common loop and normal loop, respectively.
FIG. 5 shows an example of a core insertion location for suppressing common mode noise and normal mode noise. FIG. 5A shows an example of countermeasures for only common mode noise, FIG. 5B shows an example of countermeasures for only normal mode noise, and FIG. 5C shows an example of countermeasures for both common and normal noise. Moreover, each symbol shown to Fig.5 (a)-(c) and the specific example of the core corresponding to each are shown on the right side of Fig.6 (a)-(c).

In Patent Document 1, for example, an amorphous core is inserted into each terminal of a diode as a countermeasure against normal mode noise. In this method, since a core is required for each noise generation mode, the number of members used increases.
Therefore, as a method for collectively dealing with common mode noise and normal mode noise, cores having the shapes shown in Patent Documents 2 and 3 have been proposed.

FIG. 7 shows an example of the shape of the core used in Patent Documents 2 and 3.
As shown in the figure, the penetrating core 1 has a shape with a gap, and a wire (winding) 2 is wound around the leg without a gap to both normal and common. By creating a core loop, the shape can generate impedance in each mode. However, when the shape shown in FIG. 7 is adopted, it is difficult to achieve both the processing performance and strength of the core because a gap is provided at the center leg.

Specifically, since it is a process of the middle leg to form a simple gap, there are recurrent limitations in cutting, and the manufacturing accuracy is usually in the range of about ± 0.1 to 1 mm even in molding. Variation occurs. The gap length variation leads to impedance variation, and the variation becomes so large that it cannot be ignored even if the gap is very small. For example, when an error of ± 1 mm is generated by providing a gap in a general ring core having an outer diameter of 14 mm, an inner diameter of 8 mm, and a height of 7 mm, the impedance error increases as it exceeds 50%.
In addition, since many magnetic materials such as ferrite are not sticky like ceramics and are susceptible to brittle fracture, providing a gap in the middle leg causes a significant drop in strength and tends to cause microcracks. Therefore, it is easy to break with a slight impact, and the work is complicated in terms of handling.

  Furthermore, as for the core having the shape as described above, a split type of EI type or EE type is commercially available, but its use is almost limited to transformers, and in order to ensure the above gap accuracy, Chamfering is applied between mating surfaces and gaps. In addition, in order to use a combination of E-type and I-type or E-type cores, a jig for supporting and reinforcing them is required, and the periphery of the magnetic body is reinforced with resin, ceramics, metal materials, etc. used. As described above, problems remain in the EI core with a gap, the EE core, and the like by ensuring the accuracy of the gap and the mating surface and using the reinforcing jig.

  Accordingly, an object of the present invention is to reduce the number of general and inexpensive core members in view of the above-described problems of the core, and to easily reduce both common mode noise and normal mode noise.

Such problems in order to resolve, in the invention of claim 1, input with at least one of the output of the power converter the ring core for noise reduction, against the 2 or more phases lines not all phases of the three or more phases, Multiple noise reduction ring cores are installed together so that the combinations of phase wires do not overlap each other and the number of phase wires is the same for all ring cores, resulting in an unbalance in normal impedance between each phase. It is characterized by not.
In the above-described invention, in the power conversion device according to claim 1, the U-phase and V-phase lines are passed through the first noise reduction ring core with respect to the three-phase phase lines. The ring core for noise reduction is positioned between the V-phase and W-phase phase lines and between the U-phase and W-phase phase lines, and the second noise-reducing ring core has V-phase and W-phase. The second noise reduction ring core is located between the U-phase and V-phase phase lines and between the U-phase and W-phase phase lines, and the third noise reduction. The W-phase and U-phase phase lines are passed through the ring core for use, and the third noise-reducing ring core is connected between the V-phase and W-phase phase lines and between the U-phase and V-phase phase lines. Each said ring core can be arrange | positioned so that it may be located in between.

According to the present invention, both common mode and normal mode noise can be dealt with at the same time by devising the insertion method to the input / output line to the core of what has been individually countered in common mode and normal mode. It becomes possible to do. As in the past, a core having a gap in the middle of the core itself requires not only processing technology and processing accuracy to ensure impedance accuracy, but also has difficulty in handling in terms of cost and handling. However, since a versatile ring core is used in the present invention, it is inexpensive and easy to handle, and parts procurement and parts replacement are also easy.
Furthermore, since it is possible to cope with a small number of parts compared with the case where countermeasures are individually taken in the common mode and the normal mode, it is possible to easily cope with a low cost and a small number of parts.

FIG. 1 is an explanatory diagram for explaining the principle of the present invention, and FIG. 2 is a circuit diagram showing an embodiment of the present invention.
In FIG. 1, 11 to 13 are cores, 21 to 23 are electric wires (phase wires), and are examples applied in the case of three phases. That is, the core 11 is used in combination with the electric wires 21 and 23, the core 12 is used in combination with the electric wires 21 and 22, and the core 13 is used in combination with the electric wires 22 and 23.
The cores 11 to 13 are ring-shaped (annular), but are not limited to this, and may be polygonal or elliptical. Since a general-purpose ring core can be applied, it is cheap and easy to handle when this is selected. One core has an inner diameter (inner dimension) through which a necessary number of wires to be described later can pass.

In FIG. 1, the wires 21 and 23 are inserted into the core 11, but the combinations of the wires 12 and 13 are not overlapped so that the wires 21 and 23 are not inserted into the cores 12 and 13. It is necessary to equalize the number of phase wires inserted into the core so that the two electric wires are respectively inserted. The total number of input / output lines to be dealt with is not limited to three phases, but may be any number, but the case of one phase or two phases does not hold, so the case of three or more phases is targeted.
Moreover, by passing an electric wire through the cores 11-13 as mentioned above, the effect | action of a normal mode core and a common mode core is obtained using three cores.

The reason why the arrangement as shown in FIG. 1 is effective in both the normal mode and the common mode will be described. As an example, consider using inductance.
In the arrangement of FIG. 1, assuming that the inductance per core is L, two wires are connected to one core, so the inductance given to one line by one core as a normal mode is (1/2 ) L. In FIG. 1, since one core passes through two cores,
(1/2) L + (1/2) L = L (1)
A normal mode inductance of a value of

On the other hand, regarding the common mode, when the three phases are considered as one wiring, the inductance given by one core as the common mode L is (2/3) L because only two phases pass. However, because three are arranged so that there is no imbalance in each phase,
(2/3) L + (2/3) L + (2/3) L = 2L ... (2)
A common mode inductance of the value can be given.
Therefore, by arranging the cores 11 to 13 as shown in FIG. 1, both normal mode noise and common mode noise can be simultaneously suppressed without providing a normal mode core and a common mode core.

An example in which the present invention is applied as an input filter of an inverter is shown in FIG.
FIG. 2A shows a case where no countermeasure is taken (only the L-type filter), and FIG. 2B shows a case where only the normal mode filter is taken (the normal mode countermeasure core Ld and the capacitor Cx are added). FIG. 2C shows an inverter circuit in which the cores 11 to 13 arranged according to the present invention are equivalently shown as a normal mode countermeasure core Ld and a common mode countermeasure core Lc. The input line has three phases, and shows a case where three ring cores 11 to 13 having a configuration as shown in FIG. The core to be inserted is not limited to the input side but may be the output side.

An example of the conduction noise vector when the countermeasure of FIG. 2B is taken is shown in FIG. 3, and an example of the conduction noise vector when the countermeasure of FIG. 2C is taken is shown in FIG.
That is, when the countermeasure only for the normal mode filter is applied as shown in FIG. 3, the noise around 600 kHz is reduced by about 7 dB and the noise at 4 MHz is reduced by about 10 dB compared to the case of only the L-type filter (see Y). However, the 4 MHz peak remains unrestrained (see Z).

On the other hand, in FIG. 4, by inserting the core of the present invention shown in FIG. 1, it is possible to reduce the 4 MHz peak by about 15 dB in addition to the noise near 600 kHz without adding the normal mode core and the common mode core individually. (See Z).
The line X in FIGS. 3 and 4 indicates IEC61800-3 Cat. It shows international standard values for electrical equipment such as C3 inverters, and it is required to prevent conduction noise from exceeding line X. As shown in the figure, the conventional measure (Y curve) could not satisfy this standard, but by applying this invention, it can be kept within the standard. In particular, a peak around 4 MHz with almost no margin with respect to the standard can be reduced by about 10 dB.

Explanatory drawing explaining the principle of this invention Inverter circuit diagram showing an embodiment of the present invention Explanatory drawing explaining the conduction noise evaluation result of the circuit of FIG.2 (b) Explanatory drawing explaining the conduction noise evaluation result of the circuit of FIG.2 (c) Noise generation circuit explanatory diagram Explanatory drawing explaining the specific example of the core for noise countermeasures Structural diagram showing examples of cores used in Patent Documents 2 and 3

Explanation of symbols

  1, 11-13 ... Core, 2, 21-23 ... Electric wire.

Claims (2)

Input at least one of the output of the power converter the ring core for noise reduction, against the 2 or more phases lines not all phases of the three or more phases, do not overlap the combination of the phase line each other, and the number of phase lines A power conversion device , wherein a plurality of noise reduction ring cores are collectively installed so that all ring cores are equal to each other, so that no imbalance occurs in normal impedance between phases. The power conversion device according to claim 1,
For three phase lines
The U-phase and V-phase phase wires are passed through the first noise-reducing ring core, and the first noise-reducing ring core is placed between the V-phase and W-phase phase lines and between the U-phase and W-phase. Located between the phase line of
The V-phase and W-phase phase wires are passed through the second noise-reducing ring core, and the second noise-reducing ring core is placed between the U-phase and V-phase phase lines and between the U-phase and W-phase. Located between the phase line of
The W-phase and U-phase phase wires are passed through the third noise-reducing ring core, and the third noise-reducing ring core is placed between the V-phase and W-phase phase lines and between the U-phase and V-phase. Each of the ring cores is disposed so as to be positioned between the phase line of the power converter .

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