JP2006294788A - Case molded capacitor, inverter circuit employing it, drive circuit of motor for driving vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a case molded capacitor being mounted on a vehicle in which the problem of sounding due to an applied current is solved and sounding can be suppressed. <P>SOLUTION: In the case molded capacitor where a plurality of capacitor elements 1 are connected by a bus bar having one end provided with a terminal for external connection and contained in a case 4 before being resin molded excepting at least the terminal of the bus bar, the mold resin 3 performing resin molding principally comprises epoxy resin and added with 3-25 wt.% of hollow and spherical inorganic substance. The inorganic substance can suppress sound being generated from the capacitor element 1 and can reduce the weight. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is used for various types of electrical equipment, industrial use, power use, and the like, and particularly relates to a case mold type capacitor that is optimal for in-vehicle use, an inverter circuit using the same, and a drive circuit for a vehicle drive motor.

  In recent years, all electrical devices are controlled by inverter circuits from the viewpoint of environmental protection, and energy saving and high efficiency have been promoted. Among them, in the automobile industry, electrically assisted vehicles (hereinafter referred to as HEV) and the like are marketed and energy saving. The development of technology for improving the efficiency and efficiency has been actively conducted.

  In the field used for such HEV, since the working voltage range is as high as several hundred volts and the current is very large, a metallized film capacitor having high withstand voltage and low loss electric characteristics has attracted attention. In addition, the trend toward adopting metalized film capacitors with a very long life is conspicuous due to the demand for maintenance-free in the market.

  In addition, such a metallized film capacitor is composed of a metallized film obtained by vapor-depositing a metal on a resin film, and the thickness of the metal vapor-deposited film is extremely thin, 20 to 30 nm. is doing. For this reason, when used for HEV, a method of using the metallized film capacitor in a resin case and resin molding is generally used, thereby ensuring environmental resistance such as moisture resistance. It was something like that.

  6 is an exploded perspective view showing the structure of this type of conventional case mold type capacitor, FIG. 7 is a cross-sectional view taken along the line AA of FIG. 6, and in FIGS. 6 and 7, 10 indicates a capacitor element. The capacitor element 10 is formed by winding a metallized film having a metal vapor-deposited electrode formed on one or both sides of a dielectric film made of polypropylene so that the pair of metal vapor-deposited electrodes face each other with the dielectric film interposed therebetween, and zinc By forming a metallicon electrode sprayed with a positive electrode, an anode electrode and a cathode electrode are respectively provided.

  Reference numeral 11 denotes an anode bus bar, and 11a denotes an anode terminal for external connection provided at one end of the anode bus bar 11. The anode bus bar 11 includes a plurality of capacitor elements 10 arranged in close contact with each other. The anode terminal 11a is joined to the anode electrode formed on one end face, and the anode terminal 11a is pulled out above the capacitor element 10 and exposed from a case 13 described later.

  Reference numeral 12 denotes a cathode bus bar, and 12a denotes a cathode terminal for external connection provided at one end of the cathode bus bar 12. The cathode bus bar 12 is also arranged in the same manner as the anode bus bar 11, with a plurality of the capacitor elements 10 arranged in close contact. In this state, it is joined to the cathode electrode formed on the other end face of each capacitor element 10, and the cathode terminal 12 a is pulled out above the capacitor element 10 and exposed from a case 13 described later. Thus, a plurality of capacitor elements 10 are connected.

  13 is a case made of polyphenylene sulfide (hereinafter referred to as PPS) resin, 14 is a mold resin filled in the case 13, and the mold resin 14 includes a plurality of pieces connected by the anode bus bar 11 and the cathode bus bar 12. The capacitor element 10 is resin-molded in a case 13.

  The conventional case mold type capacitor configured as described above is obtained by molding the capacitor element 10 in the case 13 with the mold resin 14 having excellent heat resistance, moisture resistance, and insulation resistance. By using PPS which is excellent in mechanical strength, heat resistance and water resistance and can withstand harsh use conditions, it is possible to provide a case mold type capacitor with higher reliability than before.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
JP 2004-146724 A

  However, in the conventional case mold type capacitor, there is a so-called sounding phenomenon in which the metallized film forming the capacitor element 10 vibrates due to the electromagnetic mechanical force caused by the applied current, and this phenomenon occurs during inverter control. There has been a problem that the voltage increases when a rectangular wave voltage flowing through the capacitor element 10 is applied.

  Therefore, conventionally, as a means for controlling such sound generation, for example, as in the technique described in JP-A-63-268401 and JP-A-5-29178, the vibration of the metallized film itself is suppressed, Another proposal has been made to control sound generation by preventing it.

  As another problem, in the field used for HEV, weight reduction is a major problem from the viewpoint of protecting the global environment, and there is a problem that an increase in weight is not allowed.

  The present invention solves such conventional problems, and provides a case mold type capacitor capable of suppressing noise and exhibiting good performance, an inverter circuit using the same, and a drive circuit for a vehicle drive motor. It is for the purpose.

  In order to solve the above-described problems, the present invention provides a resin in which a plurality of capacitor elements are connected by a bus bar provided with a terminal portion for external connection at one end, accommodated in a case, and at least the terminal portion of the bus bar is removed. In the molded case mold type capacitor, the mold resin for performing the resin molding is mainly composed of an epoxy resin, and 3 to 25 wt% of a hollow and spherical inorganic substance is added thereto.

  As described above, the case mold type capacitor according to the present invention can suppress and reduce the sound generated from the capacitor element by the inorganic material by adding the hollow and spherical inorganic material to the mold resin, and In addition, the effect that the weight can be reduced can be obtained.

(Embodiment)
Hereinafter, the invention described in the entire claims of the present invention will be described by using embodiments.

  FIG. 1 is a cross-sectional view showing a configuration of a case mold type capacitor according to an embodiment of the present invention. In FIG. 1, 1 is a capacitor element, and 2 is an external connection connected to both end faces of the capacitor element 1. , 4 is a case made of PPS, and 3 is a mold resin filled in the case 4 together with the capacitor element 1.

  FIG. 2 is a conceptual diagram showing a test apparatus for measuring the sound generated from such a case mold type capacitor. In FIG. 2, 5 is a case mold type capacitor, 6 is a high frequency power source, 7 is a sound level meter, Reference numeral 8 denotes a Fourier transformer (FFT analyzer), and the microphone of the sound level meter 7 is installed at a position 100 mm away from the case mold type capacitor 5.

  Hereinafter, specific examples will be described.

Example 1
A capacitor element having a capacitance of 100 μF was produced using a metallized film made of polypropylene (PP) having a thickness of 3.5 μm. A pair of lead terminals are connected to both end faces of this capacitor element, and a case (vertical x horizontal x height: 100 x 50) made of PPS resin (manufactured by Tosoh Corp., Sastil P-60: containing 40% glass fiber). × 75 mm) and sealed with an epoxy resin as a mold resin to produce a case mold type capacitor. As for this epoxy resin, the main agent is H-399 manufactured by Sanyu Rec Co., Ltd., Glass Bubbles S22 manufactured by Sumitomo 3M Co. as an inorganic filler (true density; 0.220 ± 0.03 g / cm ³ , bulk density; 0.135 g / cm ³ , 50% particle size distribution; 35 μm) added to the epoxy resin by 10% by weight.

(Example 2)
A case mold type capacitor was produced in the same manner as in Example 1 except that Shirasu Balloon WB601 manufactured by Axes Chemical Co. was used as the inorganic filler.

(Comparative Example 1)
A case mold type capacitor was produced in the same manner as in Example 1 except that a spherical aluminum oxide-based material added to the epoxy resin in an amount of 60% by weight was used as the inorganic filler.

  A 10 kHz current was applied to the case mold type capacitors of Examples 1 and 2 and Comparative Example 1 thus produced using a rectangular wave as the 10 kHz current using the test apparatus shown in FIG. The result of measuring the pressure (dB) (n = 5) is shown in FIG.

  As is apparent from FIG. 3, Examples 1 and 2 according to the present embodiment, in which a hollow spherical inorganic substance is added as a mold resin, has a sound pressure lower by about 10 dB than the comparative example, and the effect appears. I understand that.

  FIG. 4 shows the amount of addition to the epoxy resin of Sumitomo 3M Glass Bubbles S22 (50% particle size distribution; 35 μm), which is the hollow and spherical inorganic filler shown in Example 1, and is generated from the case mold type capacitor. The result of measuring the relationship between sound pressures (n = 3) is shown, and the measurement conditions are the same as those described with reference to FIG.

  As is clear from FIG. 3, the effect of suppressing the sound pressure is recognized when the amount of the inorganic filler added is 3% by weight or more, and the remarkable effect is recognized particularly when the amount is 10% by weight or more. However, when the addition amount exceeds 20% by weight, the viscosity of the resin increases and mass productivity decreases. In particular, at 25% by weight or more, the viscosity of the resin becomes extremely high. Therefore, the addition amount of the inorganic filler is most preferably in the range of 3 to 25% by weight, preferably 5 to 15% by weight.

  FIG. 5 shows the result of measuring the weight of the case mold type capacitors of Examples 1 and 2 and Comparative Example 1, and as is apparent from FIG. It can be seen that Examples 1 and 2 according to the embodiment are significantly lighter in weight than the comparative example, and the effect is exhibited.

  As described above, the case mold type capacitor according to the present invention can suppress the sound generated from the capacitor element by the hollow and spherical inorganic substance added to the mold resin, and can reduce the weight.

  Therefore, a greater effect can be obtained by using the case mold type capacitor according to the present invention thus configured for smoothing the inverter circuit or for smoothing the drive circuit of the vehicle drive motor.

  In the present embodiment, glass is described as an example of a hollow and spherical inorganic substance. However, the present invention is not limited to this, and the same effect can be obtained as long as it is an inorganic substance such as aluminum oxide. It is something that can be done.

  Further, the sound pressure at a specific frequency can be reduced by changing the size of the hollow and spherical inorganic filler according to the sound pressure frequency.

  In the present embodiment, the epoxy resin is described as an example of the mold resin. However, the present invention is not limited to this, and a hollow spherical inorganic filler such as silicon resin or urethane resin is mixed. It goes without saying that any resin can be used.

  The case mold type capacitor according to the present invention has the effect of suppressing the sound generated from the capacitor element and reducing the weight, and in particular, for smoothing an in-vehicle inverter circuit and a vehicle driving motor. This is useful for smoothing the drive circuit.

Sectional drawing which showed the structure of the case mold type capacitor by one embodiment of this invention Conceptual diagram showing the same sound pressure test equipment Characteristic diagram showing the same sound pressure test results Characteristic diagram showing the relationship between the amount of inorganic filler added and sound pressure Characteristic diagram showing the weight of the same case mold type capacitor An exploded perspective view showing a configuration of a conventional case mold type capacitor AA sectional view of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Capacitor element 2 Lead terminal 3 Mold resin 4 Case 5 Case mold type capacitor 6 High frequency power supply 7 Sound level meter 8 Fourier transformer

Claims (5)

In a case mold type capacitor in which a plurality of capacitor elements are connected by a bus bar provided with a terminal portion for external connection at one end, and this is accommodated in a case and at least the terminal portion of the bus bar is removed, the resin mold A case mold type capacitor in which the mold resin that performs is mainly composed of an epoxy resin and 3 to 25 wt% of a hollow and spherical inorganic substance is added thereto. The case mold type capacitor according to claim 1, wherein the inorganic substance added to the epoxy resin is a silicon oxide-based substance. The case mold type capacitor according to claim 1, wherein the inorganic substance added to the epoxy resin is an aluminum oxide material. An inverter circuit using the case mold type capacitor according to claim 1 for smoothing. A drive circuit for a vehicle drive motor using the case mold type capacitor according to any one of claims 1 to 3 for smoothing.

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