JP2009095128A - Semiconductor element module and power conversion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce thermal duty of a semiconductor element constituting a power conversion apparatus. <P>SOLUTION: When a circuit for one phase, which constitutes the power conversion apparatus, is shown like Fig.7(a) and thermal duty by current flowing in Qu of a U-phase arm IGBT and Dx of an X phase arm FWD becomes severe as shown in Fig.7(b), a cooling direction is changed to an opposite direction like Fig.7(c), and cooling to Qu of the U-phase arm IGBT and Dx of the X phase arm FWD is made to be stronger than Qx of the X phase arm IGBT and Du of the U-phase arm FWD. When thermal duty by current changes, the cooling direction is changed according thereto. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a voltage-driven semiconductor element module and a power conversion device using the same.

FIG. 8A shows an example of a general three-phase inverter as a power conversion device.
Here, a load M illustrated as a three-phase coil is connected to output terminals U, V, and W of a power conversion device Conv formed of semiconductor elements. In this circuit, the semiconductor elements Qu, Qv, Qw, Qx, Qy, and Qz can be arbitrarily turned on and off to obtain three-phase AC power from the DC power supply Vd and supply arbitrary AC power to the load M. can do.

  For example, using the load M as an electric motor, the electric motor can be driven by flowing a three-phase alternating current iu, iv, iw as shown in FIG. FIG. 8C shows one phase portion of FIG. When a current iu as shown in FIG. 8 (b) flows in this one phase, each semiconductor element IGBT (insulated gate bipolar transistor) and FWD (feedback diode), as shown in FIG. 8 (d), Balanced current flows. In the case of FIG. 8A, the DC power supply Vd is directly connected to the DC intermediate capacitor Cd of the three-phase inverter. In this case, since the output of the three-phase inverter fluctuates due to fluctuations in the DC power supply Vd, output control of the three-phase inverter that compensates for the DC voltage fluctuation is required.

  FIG. 9 shows an example in which a general boost chopper circuit Chop is added to the three-phase inverter of FIG. As shown in FIG. 9, semiconductor elements Qp and Qn and a reactor Lc are provided between the DC power supply Vd and the DC intermediate capacitor Cd of the three-phase inverter, and the semiconductor elements Qp and Qn are alternately turned on and off. Thus, the voltage Ed of the DC intermediate capacitor Cd can be adjusted higher than the voltage of the DC power supply Vd. For example, when a battery is assumed as the DC power supply Vd, the output of the three-phase inverter can be stabilized by making the DC intermediate voltage Ed of the three-phase inverter constant by the boost chopper circuit Chop even when the battery voltage drops.

FIG. 10A shows an example in which a DC power source Vd is connected between the neutral point of the load M and one end of the DC intermediate capacitor Cd of the three-phase inverter Conv. It is what.
This is because the step-up chopper circuit Chop as shown in FIG. 9 is not used, and the on / off of the three-phase inverter is performed by using the inductance of the load M and the semiconductor elements Qu to Qz of the three-phase inverter. The capacitor voltage Ed can be set to a value higher than the DC power supply Vd.

  In addition, when a three-phase AC current is supplied and supplied to the load M at the same time, for example, when the load M is an electric motor, the DC power source Vd is boosted and supplied to the DC intermediate capacitor voltage Ed, and at the same time the electric motor M is driven. Can do. In particular, since the step-up chopper circuit Chop shown in FIG. 9 can be eliminated, it is possible to contribute to reduction of the number of parts and cost reduction.

Japanese Patent No. 3219039 Japanese Patent No. 3223842

FIG. 10B shows an example of a three-phase current waveform when the circuit of FIG. 10A is used.
The three-phase AC currents iu, iv, iw are supplied from the DC power source Vd with a current corresponding to the power supplied to the load M. Here, if the current output from the DC power supply Vd is id, it is distributed to each phase coil of the load M. On the other hand, in order to supply power by supplying a three-phase current to the load M, a DC current of id / 3 is superimposed on the three-phase AC current waveform as shown in FIG.

  FIG. 10C shows one phase of FIG. When a current as shown in FIG. 10 (b) flows, a current flows through each IGBT (insulated gate bipolar transistor) and FWD (feedback diode) as shown in FIG. 10 (d). Unlike a three-phase inverter, the current flowing through each semiconductor element is different, and the current duty of a specific semiconductor element becomes severe. For example, in the example of FIG. 10 (d), a large amount of current flows through U-FWD and X-IGBT, the heat duty becomes severe, and the device may be destroyed.

  Therefore, an object of the present invention is to reduce the thermal duty generated by the current of the semiconductor element that changes according to the operating condition.

In order to solve such a problem, in the invention of claim 1, a load is connected to the output terminal of the power conversion device made of a semiconductor element, and a power source is connected between the neutral point of the load and the positive electrode or the negative electrode of the power conversion device. In the power conversion system connected to
Among the semiconductor elements constituting the power converter, an element having a large thermal duty is arranged on the upstream side of the cooling air.

  In the first aspect of the present invention, the direction of the cooling air can be changed according to the driving situation (the second aspect of the invention). According to a third aspect of the invention, a power conversion device can be configured using the semiconductor element module of the first or second aspect.

  According to the present invention, by changing the cooling direction in accordance with the operating state of the apparatus, it is possible to perform efficient cooling and to bring about an advantage that the thermal duty of the semiconductor element can be reduced.

FIG. 1 is an explanatory view for explaining an embodiment of the present invention.
FIG. 1A shows a circuit for one phase of a power conversion device in the power conversion system as shown in FIG. 10A, and FIG. 1B shows a semiconductor module configuration example corresponding to FIG. Indicates. As is clear from these figures, the U-arm FWD Du and the X-arm IGBT Qx are located on the cooling wind, and the U-arm IGBT Qu and the X-arm FWD Dx are located on the cooling air lee. ing.

  As shown in FIG. 1B, each semiconductor element is connected to the copper patterns P, N, and AC by bonding wires to constitute one phase shown in FIG. These are arranged on the insulating substrate IsB and packaged as a module. The module is installed in a cooling body or the like, and the semiconductor element is cooled by applying air to the module.

FIG. 2 shows an example of an IGBT chip. From the manufacturing method of the IGBT chip, the front surface becomes an emitter electrode E and is connected by a bonding wire, and the back surface becomes a collector electrode C and is connected to a copper pattern.
FIG. 3 shows an example of the FWD chip. Similar to the IGBT chip, the front surface becomes an anode electrode A and is connected by a bonding wire, and the back surface becomes a cathode electrode K and is connected to a copper pattern.

  In the circuit as shown in FIG. 10 (a), a large amount of current flows through the U arm FWD and the X arm IGBT as shown in FIG. 4 (b). By placing it above, cooling is enhanced. On the other hand, since the U-arm IGBT and the X-arm FWD have a small current and a small temperature rise, the U-arm IGBT and the X-arm IGBT can be cooled without problems even when the cooling air rises due to the temperature rise of the U-arm FWD and the X-arm IGBT.

FIG. 5 shows a first modification of the present invention. This is characterized by the fact that each semiconductor element IGBT and FWD are connected in parallel two by two. In this case, too, two Dus of the U-arm FWD and two Qx of the X-arm IGBT where a large amount of current flows are used as cooling air. It is arranged upwind. Others are the same as in FIG.
FIG. 6 shows a second modification of the present invention. This is the same as the case of FIGS. 1 and 5 except that the number of parallel semiconductor elements is n (≧ 3). The values of i and j in FIG. 6 are arbitrarily selected according to the thermal design.

FIG. 7 is an explanatory diagram for explaining another embodiment of the present invention.
Here, as shown in FIG. 7 (b), the current duty of the U arm IGBT Qu and the X arm FWD Dx is strict, so the cooling direction as shown in FIG. Is changed in the opposite direction to enhance the cooling of U-arm IGBT Qu and X-arm FWD Dx. Since the U arm FWD and the X arm IGBT have a small current, the U arm FWD and the X arm FWD can be cooled without any problem even if the cooling air rises due to the temperature rise of the Qu of the U arm IGBT and the Dx of the X arm FWD.

  In the above description, the case where an IGBT element is exclusively used as the semiconductor switching element has been described, but it is needless to say that a MOSFET (metal oxide field effect transistor) or the like can be used as well.

Configuration diagram showing an embodiment of the present invention Schematic diagram of the IGBT element used in FIG. Schematic diagram of the FWD element used in FIG. A circuit diagram for one phase of FIG. 10A and a current waveform diagram flowing through each element. The block diagram which shows the 1st modification of FIG. The block diagram which shows the 2nd modification of FIG. The block diagram which shows another embodiment of this invention Three-phase inverter circuit and operation explanatory diagram Fig. 8 3-phase inverter circuit configuration with boost chopper added Circuit diagram of a three-phase inverter that uses the motor neutral point

Explanation of symbols

  Qu, Qx ... IGBT element, Du, Dx ... FWD element, P, N, AC ... Copper pattern, IsB ... Insulating substrate, A, C, E, K ... Electrode, Vd ... DC power supply, Ed ... Capacitor voltage.

Claims (3)

In a power conversion system in which a load is connected to an output end of a power conversion device made of a semiconductor element, and a power source is connected between a neutral point of the load and a positive electrode or a negative electrode of the power conversion device,
Of the semiconductor elements constituting the power conversion device, an element having a large thermal duty is arranged on the upstream side of the cooling air.   The semiconductor module according to claim 1, wherein the direction of the cooling air is changed according to an operation state.   A power conversion device comprising the semiconductor element module according to claim 1.

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