JP2006060986A - Conductor structure of power converter - Google Patents

Abstract

Radiation noise due to switching of a semiconductor switching element such as an IGBT is reduced without particularly increasing the size of a circuit or device.
In contrast to the conventional conductor C simplified as shown in FIG. 1A, in the present invention, the conductor C as shown in FIG. 1B or 1C (the former is a perspective view and the latter is a top view). The slit SL is formed in the side surface of the conductor C, thereby increasing the high-frequency resistance of the conductor C and increasing the radiation noise reduction effect. In addition to the slits, examples using the skin effect are also disclosed.
[Selection] Figure 1

Description

  The present invention relates to a conductor structure used for wiring of a power converter.

FIG. 4 shows an inverter main circuit representing the power converter.
Reference numeral 1 is a DC power supply circuit, 2 is a load such as a motor, and 3 is an inverter unit composed of a power semiconductor element, which can output a variable voltage and frequency. However, the DC power supply circuit 1 is usually composed of a large-capacity DC smoothing electrolytic capacitor via an AC power supply (not shown) and a diode rectifier. In addition, reference numeral 4 in the inverter unit 3 is a power semiconductor element such as an IGBT (insulated gate bipolar transistor), and 5 is a diode connected in antiparallel, and these are constituted by six circuits. In general, the power semiconductor modules 6a to 6c are a set of two elements for the upper and lower arms.

FIG. 5 shows an external view of the IGBT module, and FIG. 6 shows a schematic diagram of its internal wiring structure.
Reference numeral 7 in FIG. 5 is a positive DC output terminal (P terminal), 8 is a negative DC output terminal (N terminal), and 9 is an AC output terminal (U terminal). 6, 10, 11, and 12 are a positive side DC output wiring conductor, a negative side DC output wiring conductor, and an AC output wiring conductor inside the module, respectively. Become. The wiring conductor is generally a conductor having a thickness of approximately 1 mm and a width of 1 cm.

  6A, 14 on the copper base 13 is an insulating substrate, and the upper arm side IGBT chip 15, the lower arm side IGBT chip 16, and the upper arm side FWD (free wheeled) are formed on the substrate 14. Diode) chip 17 and lower arm side FWD chip 18 are mounted, and wiring is made with conductors 10 to 12 (not shown) by copper foil patterns 19 to 21 at each potential. This copper foil pattern is generally 0.1 mm thick. In FIG. 6B, reference numerals 22 to 25 denote wires, which are wired between the semiconductor chip and the copper foil pattern. FIG. 7 shows an equivalent circuit diagram inside the module based on the wiring structure of FIG. Each inductance indicated by a dotted line represents each inductance of the wiring conductor, the copper foil pattern, and the wire.

  Also, reference numerals 26a to 26c connected between the P terminal 7 and the N terminal 8 of the IGBT module in FIG. 4 are snubber capacitors, and when the IGBT switches, the wiring inductance 27 between the DC power supply circuit 1 and the IGBT modules 6a to 6c is 27. In order to absorb current energy (for suppressing surge voltage), each IGBT module is connected, and is essential for a device having a certain capacity or more.

  FIG. 8 shows an external view of a snubber capacitor, and FIG. 9 shows an example of a wiring structure in which an IGBT module and a snubber capacitor are connected. As shown in FIG. 9, the snubber capacitors 26a to 26c are usually installed on the IGBT modules 6a to 6c. FIG. 10 shows an equivalent circuit diagram inside the snubber capacitor. Mainly composed of inductance components 30 and 31 of the output terminals 28 and 29 and a capacitor 32 of the film element section. The internal structure of the IGBT module is disclosed in Patent Document 1, for example.

Japanese Patent Publication No. 08-010748 (2nd page, Fig. 1)

  When the IGBT or FWD switches, the fluctuation of the intermediate potential 33 of the IGBT (FWD) connected to the upper and lower arms (with the turn-on of the IGBT 16 in FIG. 11, the potential 33 changes from the P-side potential to the N-side potential). The current 36 for charging the output capacitors 34 and 35 of the IGBT 15 and the FWD 17 mainly flows from the snubber capacitor 26. The frequency of the current is generally determined by the resonance phenomenon (usually 10 MHz or more) due to the output capacitance of the semiconductor chip and the wiring inductance between the snubber capacitor (snubber capacitor and wiring inside the module). When the current 36 is i, an electric field E (radiation noise) as shown in the following formula (1) is radiated to the surroundings.

E = 1.32 · 10 ⁻¹⁴ · f ² · i · S / r (1)
f: Frequency i: Current S: Area of path through which current i flows r: Distance from noise source

  Usually, the radiation noise standard for a device defined in CISPR (International Radio Interference Special Committee) code is 30 MHz or more. For this reason, the resonance frequency of the current flowing between the chip and the snubber capacitor (the frequency at which the current i is the largest in the above equation (1)) substantially coincides with the minimum frequency of 30 MHz of the standard, and a high level of radiation in this frequency band. Noise is generated. For this reason, the above standards are often greatly exceeded, and noise reduction in this frequency band becomes a problem.

  As a general countermeasure, a noise shield material is used, or dv / dt at the time of switching of IGBT or FWD is moderated. In these cases, however, the cost increases and the switching loss of the IGBT increases, which causes problems such as an increase in the size of the radiator. In general, a snubber capacitor or an IGBT module itself becomes an antenna that becomes a noise source, and problems such as malfunction of peripheral circuits and devices also occur.

  Accordingly, an object of the present invention is to reduce radiation noise due to switching of a power semiconductor element such as an IGBT without increasing the size of a circuit or an apparatus.

In order to solve such a problem, in the invention of claim 1, in the wiring conductor or copper foil pattern inside the power semiconductor module used in the power converter,
A conductor structure of a power converter, wherein a notch or a protrusion or a depression is formed so as to increase the resistance value.
In invention of Claim 2, in the wiring conductor between the semiconductor module for electric power used with a power converter, and the capacitor connected to the direct current middle part,
A notch or a protrusion or a depression is formed so as to increase the resistance value.

In the invention of claim 3, in the conductor for leading out the surge voltage suppressing snubber capacitor used in the power converter,
A notch or a protrusion or a depression is formed so as to increase the resistance value.
In the invention according to any one of the first to third aspects, the cuts or protrusions or depressions formed in the conductor can be irregularly formed (the invention of claim 4) or formed in the conductor. The protrusion or the depression can be formed on at least one surface of the conductor (the invention of claim 5).

  According to the present invention, unnecessary radiation noise at the time of switching of a power semiconductor element such as an IGBT can be reduced, so that not only a noise shielding material becomes unnecessary, but also it can be easily adapted to a radiation noise standard. Become. Since the peripheral circuit does not malfunction, the reliability is improved.

FIG. 1 is an explanatory diagram for explaining a first embodiment of the present invention.
FIG. 1 (a) shows a conductor C having a conventional shape with a simplified conductor, and FIG. 1 (b) or FIG. 1B is a perspective view, and FIG. 1C is a top view.
That is, the overall shape is substantially the same as the conventional shape, and the slit SL is formed in the side surface portion. By doing so, the path length of the current flowing in the conductor becomes longer than that in the case of a mere flat plate, particularly as shown by the dotted line in FIG. 1C, so that the resistance value can be increased accordingly.

FIG. 2 is an explanatory view for explaining a second embodiment of the present invention.
This is a shape example in which the positive potential conductor and the negative potential conductor are brought close to each other with the insulating band I interposed therebetween to reduce the inductance. In the conventional shape of FIG. 2A, both conductors C are arranged in a substantially linear manner, whereas FIG. 2B shows an example in which the wavy shapes W are staggered, FIG. c) is an example in which a slit SL is provided. By doing so, the current flowing in the conductor flows along the wave shape W or the slit SL with the insulating band I interposed therebetween so that the negative mutual inductance between the two conductors C becomes large. The length becomes longer, and the resistance value is increased as compared with the conventional one.

FIG. 3 is an explanatory diagram for explaining a third embodiment of the present invention.
3 (a) shows a comb-shaped (convex) projection T, FIG. 3 (b) shows a concave slit SL, and FIG. 3 (c) shows a convex projection B. FIG. 3 (d) shows a concave depression H formed.
By doing as described above, the high-frequency current that causes radiation noise increases the path length of the current due to the skin effect of the protrusions T and B, the slit SL, and the depression H formed on the conductor C, and as a result. The resistance of the conductor increases. These protrusions, slits, and dents can be formed not only on one side of the conductor C but also on both sides.

The conductor described in FIGS. 1 to 3 can be applied to the following cases.
1) Copper pattern inside IGBT module 2) Wiring conductor inside IGBT module 3) Wiring conductor between IGBT module and snubber capacitor 4) Output conductor of snubber capacitor itself and internal wiring conductor 5) Between IGBT module and DC power supply circuit (DC) Wiring conductor between intermediate capacitors)

1st Embodiment explanatory drawing of this invention Explanatory drawing of 2nd Embodiment of this invention Explanatory drawing of 3rd Embodiment of this invention General inverter main circuit diagram External view showing an example of an IGBT module Example of internal wiring structure of IGBT module Internal equivalent circuit diagram of IGBT module External view of snubber capacitor Connection diagram of IGBT module and snubber capacitor Capacitor internal equivalent circuit diagram Charging current path diagram to output capacity

Explanation of symbols

  C ... conductor, SL ... slit, W ... corrugated shape, I ... insulation band, T ... comb-like projection, B ... convex projection, H ... concave depression.

Claims (5)

In the wiring conductor or copper foil pattern inside the power semiconductor module used in the power converter,
A conductor structure of a power converter, wherein a notch or a protrusion or a depression is formed so as to increase the resistance value. In the wiring conductor between the power semiconductor module used in the power conversion device and the capacitor connected to the DC intermediate part thereof,
A conductor structure of a power converter, wherein a notch or a protrusion or a depression is formed so as to increase the resistance value. In the lead conductor of the snubber capacitor for surge voltage suppression used in the power converter,
A conductor structure of a power converter, wherein a notch or a protrusion or a depression is formed so as to increase the resistance value.   The conductor structure of the power converter according to any one of claims 1 to 3, wherein the cuts, protrusions, or depressions formed in the conductor are irregularly formed.   The conductor structure of the power converter according to claim 1, wherein a protrusion or a depression formed in the conductor is formed on at least one surface of the conductor.

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