JP5352113B2 - Inverter module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inverter module that suppresses the generation of a common mode current. <P>SOLUTION: In the inverter module, each arm includes: a cooling device 28 provided on the high voltage side of a switching element TR and a diode D; a cooling device 36 provided on the low voltage side of the switching element TR and the diode D; and an insulated substrate 22 and an insulated substrate 32 respectively sandwiched between the switching element TR and diode D and the cooling device 28 and between the switching element TR and diode D and the cooling device 36. A capacitor C<SB>UU</SB>comprised of the insulated substrate 22 included in the upper arm and a capacitor C<SB>LL</SB>comprised of the insulated substrate 32 included in the lower arm are smaller than a capacitor C<SB>UL</SB>comprised of the insulated substrate 32 included in the upper arm and a capacitor C<SB>LU</SB>comprised of the insulated substrate 22 included in the lower arm. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an inverter module used in an inverter circuit.

  An inverter circuit for driving a load such as a motor mounted on an electric vehicle, a hybrid vehicle or the like is widely used. The inverter circuit includes a switching arm, and each switching arm of the high-power inverter circuit is provided with a cooling device.

  Patent Document 1 discloses an inverter for an automobile provided with a cooling member that cools a semiconductor module from both sides. Patent Document 2 discloses a power semiconductor element and an inverter device in which a semiconductor element is bonded onto a heat sink via an insulating sheet, and heat generated from the semiconductor element is cooled by the heat sink from both sides.

  In the inverter module of the power converter, a common mode voltage is generated between the inverter and a load (usually a motor). Since the common mode current flows due to the common mode voltage and causes problems such as radiation noise, a technique for suppressing the common mode current is also considered.

  In Patent Document 3, in a package including a series circuit of switching arms, a copper base for cooling is arranged outside the package, and the upper arm is mounted over the area of the copper base on which the lower arm in the series circuit of switching arms is mounted. A technique for reducing the generation of common mode current by increasing the area of the copper base to be produced is disclosed.

  In Patent Document 4, a common mode choke coil is connected between an inverter and an electric device, and a series connection body of a capacitor and a resistor is connected to a wiring between the choke coil and the electric device. A technique for reducing the generation of common mode current by connecting a series connection in common and connecting it to a virtual grounding portion having the same potential as the ground for a frequency higher than that of the power supply is disclosed.

  Patent Document 5 discloses a control device in which a noise filter provided on the input side of an inverter circuit is grounded via a housing of the device, and is provided between a capacitor connected to an AC line and the capacitor. Disclosed is a technique for reducing the occurrence of common mode current by providing a coil, a clamper provided between a connection point between the capacitor and the housing, and a capacitor connected in parallel to the clamper. ing.

JP 2005-65379 A JP 2007-67220 A JP 2007-181351 A JP 2001-69762 A JP 2003-143753 A

  In the technique of providing a filter including a choke coil or the like in the above prior art, a large current of several hundred A may flow between the inverter and the load (motor or the like), and a huge coil is used to prevent magnetic saturation of the inductance. It is necessary to use it. Accordingly, there is a problem that downsizing of the inverter module is hindered.

  In addition, the technique of providing an electromagnetic shield to prevent magnetic noise due to common mode current from leaking to the outside increases the manufacturing cost of the device, and does not eliminate the noise source, so there is a problem that it is not a fundamental measure. .

In one aspect of the present invention, an arm series connection body in which a switching element and a diode connected in reverse parallel to the switching element are used as one arm and two arms are connected in series as an upper arm and a lower arm, respectively. A modularized inverter module, wherein each arm has a first cooling device provided on a high voltage side of the switching element and the diode, and a second cooling device provided on a low voltage side of the switching element and the diode. A switching device included in the upper arm, and a first insulating substrate and a second insulating substrate sandwiched between the switching device and the diode, and the first cooling device and the second cooling device, respectively. The capacitor included between the diode and the first cooling device and the lower arm includes the capacitor A switching element and a capacitor between the diode and the second cooling device include the switching element included in the upper arm, a capacitor between the diode and the second cooling device, and the switching included in the lower arm. It is an inverter module characterized by being 33 times larger than the capacitor between the element and the diode and the first cooling device.

  Further, an external capacitor is connected between the switching element and the diode included in the upper arm and the first cooling device and between the switching element and the diode included in the lower arm and the second cooling device. It is preferable to do.

  A capacitor between the switching element and the diode included in the upper arm and the first cooling device; and a capacitor between the switching element and the diode included in the lower arm and the second cooling device; A capacitor between the switching element and diode included in the upper arm and the second cooling device, and a capacitor between the switching element and diode included in the lower arm and the first cooling device. It is preferable that the load case connected to the inverter module and the case of the inverter module have the same potential.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of the common mode electric current in an inverter module can be suppressed. Thereby, electromagnetic noise can be reduced.

  FIG. 1 is a diagram showing a basic inverter circuit 100. The inverter circuit 100 is connected between a power source 200 and a load (motor) 300. The inverter circuit 100 includes a rectifier module 10 including six diodes D1 to D6, a capacitor 12, an inverter module 14 including power switching elements TR1 to TR6 and diodes D7 to D12.

  The rectifier module 10 is configured by connecting in parallel three series-connected bodies in which two diodes D1 to D6 are connected in series. The rectifying module 10 is connected in parallel with the capacitor 12 and the inverter module 14. Further, each phase of the power source 200 is applied between two diodes included in the three series-connected bodies.

  The inverter module 14 includes six arms in which diodes D7 to D12 are connected in antiparallel to each of the switching elements TR1 to TR6. The switching elements TR1 to TR6 are high power switching elements such as insulated gate bipolar transistors (IGBTs) and field effect transistors (MOSFETs), for example. The diodes D7 to D12 are, for example, large-capacity PIN diodes. The six arms are two series-connected bodies connected in series as two upper arms and two lower arms, and three series-connected bodies are connected in parallel to constitute the inverter module 14. Each phase of the load 300 is connected between two arms included in three series-connected bodies.

  Each arm includes a switching element TR (TR1 to TR6), a diode D (D7 to D12), a first electrode 20, an insulating substrate 22, and a second electrode 24, as shown in the perspective view of FIG. 2 and the side view of FIG. , The solder material 26, the cooling device 28, the third electrode 30, the insulating substrate 32, the fourth electrode 34, and the cooling device 36.

  The high voltage side terminal (the collector of the N channel IGBT, the drain of the N channel MOSFET, etc.) of the switching element TR is connected to the first electrode 20 by the solder material 26. The high-voltage side terminal of the diode D (such as the cathode of the PIN diode) is also connected to the first electrode 20. The first electrode 20 is bonded to the surface of the insulating substrate 22, and the back surface of the insulating substrate 22 is bonded to the second electrode 24. Further, the second electrode 24 is bonded to the cooling device 28 by the solder material 26 while being electrically connected.

  The low voltage side terminal (the emitter of the N-channel IGBT, the source of the N-channel MOSFET, etc.) of the switching element TR is connected to the third electrode 30 by the solder material 26. The low-voltage side terminal of the diode D (such as the anode of the PIN diode) is also connected to the third electrode 30. The third electrode 30 is bonded to the surface of the insulating substrate 32, and the back surface of the insulating substrate 32 is bonded to the fourth electrode 34. Furthermore, the fourth electrode 34 is bonded to the cooling device 36 by the solder material 26 while being electrically connected.

With such a configuration, as shown in FIG. 3, the insulating substrate 22 sandwiched between the first electrode 20 and the second electrode 24 causes the first electrode 20 and the second electrode 24 to be interposed. Capacitor _CU is generated. Further, the capacitor _CL is generated between the third electrode 30 and the fourth electrode 34 by the insulating substrate 32 sandwiched between the third electrode 30 and the fourth electrode 34.

In the present embodiment, a capacitor generated between the first electrode 20 and the second electrode 24 of the upper arm is referred to as C _UU, and a capacitor generated between the third electrode 30 and the fourth electrode 34 of the upper arm is defined as C _UL. And A capacitor generated between the first electrode 20 and the second electrode 24 of the lower arm and C _LU, a capacitor generated between the third electrode 30 of the lower arm and the fourth electrode 34 and the C _LL.

In this embodiment, the capacitor C _LL and C _UU constitute the arms to be larger than capacitor C _LU and C _UL. For example, when the insulating substrate 22 and the insulating substrate 32 are all made of the same material, the insulating substrate 22 between the first electrode 20 and the second electrode 24 of the upper arm and the third electrode 30 and the fourth electrode 34 of the lower arm. The insulating substrate 32 between the lower electrode and the insulating substrate 22 between the first electrode 20 and the second electrode 24 of the lower arm and the insulating substrate 32 between the third electrode 30 and the fourth electrode 34 of the upper arm. Make it thinner .

  Specifically, an upper arm connected to the high voltage side terminal P and a lower arm connected to the low voltage side terminal N can be connected in series as shown in FIG. Moreover, it is good also as a structure which connected the upper arm connected to the high voltage side terminal P, and the lower arm connected to the low voltage side terminal N in series as shown in FIG. In this case, the upper arm insulating substrate 22, the second electrode 24, the cooling device 28, the third electrode 30, the insulating substrate 32, the fourth electrode 34, and the cooling device 36 are respectively the lower arm insulating substrate 32 and the fourth electrode 34. The cooling device 36, the first electrode 20, the insulating substrate 22, the second electrode 24, and the cooling device 28 are common.

The dielectric constants of the insulating substrate 22 between the first electrode 20 and the second electrode 24 of the upper arm and the insulating substrate 32 between the third electrode 30 and the fourth electrode 34 of the lower arm are set to It may be smaller than the dielectric constant of the insulating substrate 22 between the first electrode 20 and the second electrode 24 and the insulating substrate 32 between the third electrode 30 and the fourth electrode 34 of the upper arm.

  FIG. 6 is a diagram showing an equivalent circuit when the inverter module 14 is applied to the inverter circuit 100. Here, the parasitic inductance in the inverter module 14 is ignored.

  The operation mode of the inverter is divided into two modes: (1) the upper arm 1 phase and the lower arm 2 phase are conductive, and (2) the upper arm 2 phase and the lower arm 1 phase are conductive, and these two states are repeated.

  FIG. 7 is an equivalent circuit of the inverter in a state where (1) the upper arm 1 phase and the lower arm 2 phase are conductive. FIG. 8 is an equivalent circuit of the inverter when (2) the upper arm 2 phase and the lower arm 1 phase are conductive.

7 and 8, two paths are generated from the high voltage side to the low voltage side of the inverter. That is, the first path is a conductive upper arm → parasitic inductor Lc of the cable to the motor → parasitic capacitor C _M between the motor winding and the motor case → motor case → parasitic capacitor C _M between the motor case and the motor winding. → The parasitic inductor Lc of the cable to the motor → the path of the lower arm that conducts. The second path is a path that leads from either the parasitic capacitor C _UU of each upper arm, the upper arm that conducts to the parasitic capacitor C _UL of the upper arm that conducts to the cooling device 28 or 36, and the cooling device 28 or 36. , The path connecting to any one of the parasitic capacitor C _LL of each lower arm and the parasitic capacitor C _{LU of} the lower arm that conducts → the lower arm that conducts.

9, as a bridge circuit across the parasitic inductance L _G between the first and second paths of the cooling apparatus 28, 36 a path for common mode current case and the motor case in the conducting state of FIG. 7 It is the rewritten figure.

Figure 10 is a bridge circuit across the parasitic inductance L _G between the first and second paths of the cooling apparatus 28, 36 a path for common mode current case and the motor case in the conducting state of FIG. 8 It is the rewritten figure.

FIG. 11 is a simplified diagram of these circuits. In this circuit, when the formula (1) holds, the common mode current does not flow.
Za: Zb = Zc: Zd (1)

In either state of FIGS. 9 and 10, the condition for satisfying the formula (1) is that the capacitors _CLL and _CUU are sufficiently larger than the capacitors _CLU and _CUL .

  In this embodiment, an N-channel switching element is used for both the upper arm and the lower arm. However, as shown in FIG. 12, a P-channel switching element may be used for the upper arm. Thereby, the parasitic capacitor on the collector side can be reduced.

It is a figure which shows the basic composition of the inverter circuit in embodiment of this invention. It is a perspective view which shows the structure of the inverter module in embodiment of this invention. It is a side view which shows the structure of the inverter module in embodiment of this invention. It is a figure which shows the example of a combination of the upper arm and lower arm in embodiment of this invention. It is a figure which shows the example of a combination of the upper arm and lower arm in embodiment of this invention. It is a figure which shows the equivalent circuit of the inverter circuit in embodiment of this invention. It is a figure which shows the operation mode of the inverter circuit in embodiment of this invention. It is a figure which shows the operation mode of the inverter circuit in embodiment of this invention. It is a figure which shows the bridge circuit with respect to the common mode current of the inverter circuit in embodiment of this invention. It is a figure which shows the bridge circuit with respect to the common mode current of the inverter circuit in embodiment of this invention. It is a figure which shows the equivalent circuit of the bridge circuit in embodiment of this invention It is a figure which shows the modification of the inverter circuit in embodiment of this invention. It is a figure which shows the modification in embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Rectifier module, 12 Capacitor, 14 Inverter module, 20 1st electrode, 22 Insulating board, 24 2nd electrode, 26 Solder material, 28 Cooling device, 30 3rd electrode, 32 Insulating board, 34 4th electrode, 100 Inverter circuit , 200 power supply, 300 load (motor).

Claims (2)

An inverter module in which a switching element and a diode connected in reverse parallel to the switching element are used as one arm, and an arm series connection body in which two arms are connected in series as an upper arm and a lower arm, respectively, is modularized. ,
Each arm includes a first cooling device provided on a high voltage side of the switching element and the diode, a second cooling device provided on a low voltage side of the switching element and the diode, the switching element and the diode. And a first insulating substrate and a second insulating substrate sandwiched between the first cooling device and the second cooling device, respectively,
The switching element included in the upper arm and the capacitor between the diode and the first cooling device, and the switching element included in the lower arm and the capacitor between the diode and the second cooling device are 33 times or more than the capacitor between the switching element and the diode included in the upper arm and the capacitor between the second cooling device and the capacitor between the switching element and the diode included in the lower arm and the first cooling device Inverter module characterized by being large . The inverter module according to claim 1 ,
A capacitor between the switching element and the diode included in the upper arm and the first cooling device; a capacitor between the switching element and the diode included in the lower arm; and the second cooling device; The switching element included in the upper arm and the capacitor between the diode and the second cooling device, and the switching element included in the lower arm and the capacitor between the diode and the first cooling device are connected to an inverter. An inverter module characterized in that a load case connected to the module and an inverter module case have the same potential.

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