JP2002095238A - Power module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size of a power module including a snubber circuit portion and enhance the responsiveness of the snubber circuit portion. SOLUTION: A snubber circuit 10 is placed in parallel with a switching portion 50. The snubber circuit 10 includes IGBT 11 as a switching element for the snubber circuit, a resistor 15, a constant-voltage diode 16 as a selective conducting element, and a diode 19. The electrodes 12, 13, and 14 of the switching element correspond to the gate, emitter, and collector of the IGBT 11. The resistor 15 is connected between the electrodes 12 and 13. The cathode and anode of the constant-voltage diode 16 are connected with the electrode 14 and the anode of the diode 19, respectively. The cathode of the diode 19 is connected with the electrode 12. As a power module 101, the switching portion 50 and the snubber circuit 10 are completely housed in a case 40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a power module, and more particularly to a power module having a snubber circuit or a protection circuit.

[0002]

2. Description of the Related Art In general, a power semiconductor switching element such as an insulated gate bipolar transistor (hereinafter, also referred to as "IGBT") has a surge voltage generated when the switching element opens and closes (ON / OFF). A snubber circuit is provided to absorb the noise.

A conventional snubber circuit includes a capacitor (so-called snubber capacitor) or a combination of a snubber capacitor and a diode, and is connected in parallel between main terminals of a power semiconductor switching element. The surge voltage is absorbed and suppressed by charging and discharging the snubber capacitor.

At this time, a large-capacity capacitor is used as a snubber capacitor to sufficiently absorb the surge voltage. Since the large-capacity capacitor is large, the capacitor is further vulnerable to heat. Therefore, the snubber capacitor is provided outside the case in which the power semiconductor switching element is housed.

[0005]

As described above, in the conventional snubber circuit, since the snubber capacitor is provided outside the above case, it is caused by the inductance of the wiring connecting the power semiconductor switching element and the snubber capacitor. Therefore, it takes time until the snubber circuit operates. Further, a transient forward voltage or the like of a diode constituting the snubber circuit may also contribute to a decrease in responsiveness of the snubber circuit. For this reason, the conventional snubber circuit has a problem that the surge voltage cannot be sufficiently absorbed due to low response.

Further, as described above, since the snubber capacitor is large and is provided outside the case,
There is a problem that the entire power module including the snubber circuit becomes large.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and a first object of the present invention is to improve the responsiveness and reduce the size of a power module having a snubber circuit.

A second object of the present invention is to realize a first object and to provide a highly versatile power module.

A third object of the present invention is to realize the first object and to provide the power module at low cost.

[0010]

According to a first aspect of the present invention, there is provided a power module comprising a first electrode, a second electrode, and at least one electrode provided between the first electrode and the second electrode.
A switching section having two power semiconductor switching elements, a snubber circuit section provided in parallel with the switching section between the first electrode and the second electrode, and a case, wherein the snubber circuit section includes A third electrode connected to the first electrode, a fourth electrode connected to the second electrode, a semiconductor switching element for a snubber circuit unit having a control electrode, the third electrode and the control electrode, And a selective conduction element connected between the fourth electrode and the control electrode, the conduction element being turned on when an applied voltage exceeds a predetermined value, and at least the power semiconductor switching element; The semiconductor switching element for the snubber circuit section and the resistor are housed in the case.

(2) A power module according to a second aspect is the power module according to the first aspect, wherein the selective conduction element is further housed in the case.

(3) The power module according to a third aspect is the power module according to the first aspect, wherein the selective conduction element is detachably provided outside the case. .

(4) A power module according to a fourth aspect is the power module according to any one of the first to third aspects, wherein the at least one power semiconductor switching element includes a plurality of serially connected power semiconductor switching elements. It is characterized by including a power semiconductor switching element.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment> FIG. 1 shows a schematic configuration diagram of a power module 101 according to a first embodiment. The power module 101 includes two switching units 50 connected in series, a snubber circuit unit 10 provided in parallel with each switching unit 50, and a case 40. Here, for the sake of simplicity, the two switching units 50 have the same configuration, and FIG. 1 (and drawings described later) shows only a specific circuit configuration for one of them. The same applies to the snubber circuit unit 10.

As shown in FIG. 1, each switching unit 50
Have a first electrode 51 and a second electrode 52, respectively. Note that the first electrode 51 and the second electrode 52 are also simply referred to as “electrode 51” and “electrode 52”, respectively.

The first electrode 51 of one switching unit 50 (left side in FIG. 1) is connected to the terminal 1, and the second electrode 52 of the one switching unit 50 is connected to the other switching unit 50 (right side in FIG. 1). ) Is connected to the first electrode 51. The second electrode 52 of the other switching section is connected to the terminal 2. Further, the output terminal 3 is drawn out from between the two switching units 50 connected in series. The power module 101 has a terminal 1
Are connected to the low potential side of the power supply 90 and the terminal 2 is connected to the high potential side of the power supply 90 for use.

More specifically, the switching unit 50 includes the electrode 5
A power semiconductor switching element (hereinafter also referred to as “power switching element”) 53 connected between the first and second switching elements 53, and the switching element 53 includes an insulated gate bipolar transistor (hereinafter also referred to as “IGBT”) 54 and a diode 55. Contains. The emitter of the IGBT 54 is connected to the electrode 51, the collector is connected to the electrode 52, and the gate is drawn out of the case 40. The anode of the diode 55 is connected to the emitter of the IGBT 54, and the diode 55 is connected to the collector.
Are connected. Note that a transistor, a MOSFET, or the like may be used instead of the IGBT 54.

The electrode 5 of each switching unit 50
The snubber circuit units 10 are connected in parallel to the respective switching units 50 between 1 and 52. Specifically, the snubber circuit unit 10 includes a semiconductor switching element for a snubber circuit unit (hereinafter, also referred to as a “switching element for a snubber circuit unit”) 11.
, A resistor 15, a selective conducting element 16, and a diode 19
And

Here, a case will be described in which the switching element 11 for the snubber circuit section is formed of an IGBT, and the IGBT is also referred to as "IGBT 11" with the reference numeral of the switching element 11 for the snubber circuit section. Note that another element (for example, a transistor or a MOSFET) or a circuit may be applied to the switching element 11 for the snubber circuit unit.

The selective conducting element is an element that conducts or exhibits good conductivity when the applied voltage exceeds a predetermined value. In detail, when the absolute value of the applied voltage is increased, when the voltage exceeds a predetermined voltage, the current value changes sharply or becomes lower in resistance than before the predetermined voltage, for example, a breakdown characteristic. And devices and circuits having breakover characteristics. As the selective conduction element 16, for example, a constant voltage diode (for example, an avalanche diode or a zener diode) or a thyristor can be applied. Here, it is assumed that the selective conducting element 16 is formed of a constant voltage diode, and the constant voltage diode is also referred to as a “constant voltage diode 16” with the reference numeral of the selective conducting element 16.

The snubber circuit switching element 11 has a control electrode 12, a third electrode 13, and a fourth electrode 14. The control electrode 12, the third electrode 13, and the fourth electrode 1
4 are also simply referred to as “electrode 12”, “electrode 13”, and “electrode 14”, respectively. The third electrode 13 is connected to the first electrode 51 of the switching unit 50, and the fourth electrode 14 is connected to the second electrode 52. The gate, the emitter, and the collector of the IGBT 11 correspond to the control electrode 12, the third electrode 13, and the fourth electrode 14 of the snubber circuit switching element 11, respectively.

Further, a resistor 15 is connected between the electrodes 12 and 13. A diode 1 is provided between the electrodes 12 and 14.
9 and a constant voltage diode 16 are connected in series. More specifically, the cathode of a diode 19 is connected to the electrode 12, the anode of the diode 19 is connected to the anode of a constant voltage diode 16, and the cathode of the constant voltage diode 16 is connected to the electrode 14. .

In particular, in the power module 101, the entirety of the switching unit 50 and the snubber circuit unit 10 is the case 40.
Is housed inside. That is, the power switching element 5
3, snubber circuit switching element 11, resistor 15,
Case 4 is the selective conducting element 16 and diodes 55 and 19
It is stored in 0.

Next, FIG. 2 shows a schematic sectional view of the power module 101. As shown in FIG. As shown in FIG. 2, in the power module 101, a case 40 is configured by the frame 41, the lid 42, and the base plate 43.

More specifically, for example, a copper foil 72 is placed on a heat-dissipating base plate 43 (hereinafter simply referred to as a “base plate”) made of copper.
The ceramic substrate 71 is disposed via the “b”, and each semiconductor chip on which the switching unit 50 or the snubber circuit unit 10 is formed is disposed on the ceramic substrate 71 via the copper foil 72a. The copper foils 72 a and 72 b are formed on each main surface of the ceramic substrate 71. In FIG. 2, one semiconductor chip of each of the switching unit 50 and the snubber circuit unit 10 is shown for convenience of illustration.

Both semiconductor chips and ceramic substrate 7
A frame 41 that surrounds 1 and is in contact with the base plate 43 is arranged, and the base plate 43 and the frame 41 form a vessel shape. The frame 41 is made of, for example, an insulating material such as a resin. Frame 4
Metal fittings for the terminals 1 to 3 and terminals (not shown in FIG. 2) connected to the gate of the IGBT 54 are embedded in 1, and a portion of each metal fitting that is exposed to the outside of the case 40 is connected to each terminal. Make. The ends of the metal fittings in the case 40 are connected to predetermined locations such as semiconductor chips and copper foil 72a by wires 73.

A container formed by the base plate 43 and the frame 41 is filled with a silicon gel 44 so as to cover a semiconductor chip and the like. Further, the silicon gel 44 is filled with an epoxy resin 45. Then, a lid 42 made of an insulating material such as a resin is disposed on the epoxy resin 45, thereby closing the container formed by the base plate 43 and the frame 41. The power switching element 53,
As long as the snubber circuit switching element 11, the resistor 15, the selective conduction element 16, and the diodes 55 and 19 can be accommodated, another case may be applied.

Next, the operation of the snubber circuit section 10 will be described with reference to FIG. Power switching element 5
When the third IGBT 54 is turned ON / OFF, the IGBT 5
4 easily generates a surge voltage between the collector and the emitter. At this time, if the surge voltage is higher than the breakdown voltage of the constant voltage diode 16, the snubber circuit unit 10
Constant voltage diode 16, diode 19 and resistor 1
Current flows through 5. Then, between the gate and the emitter of the IGBT 11 of the snubber circuit unit 10 (or the electrode 1).
2, 13), and when the gate-emitter voltage exceeds the threshold voltage of the IGBT 11, the IGBT 11
Turns ON. Thereby, the energy stored in the wiring is consumed by the IGBT 11, and the surge voltage is suppressed. Conversely, the breakdown voltage of the constant voltage diode 16, the resistance value of the resistor 15, and the like are set based on the voltage value of the surge voltage to be suppressed. The diode 19 is provided to prevent a thermal problem caused by a forward current flowing through the constant voltage diode 16. The diode 55 is a freewheeling diode.

According to the power module 101, the following effects can be obtained. First, the power module 101
Is different from a conventional snubber circuit,
Does not have a snubber capacitor. For this reason, the entire snubber circuit unit 10 can be housed in the case 40. Therefore, the power module can be reduced in size as compared with a conventional configuration having a snubber capacitor outside the case.

Further, since the snubber circuit section 10 is housed in the case 40, the switching section 50 and the snubber circuit section 10 can be closer to each other than in the above-described conventional power module. For this reason, the wiring inductance between the switching unit 50 and the snubber circuit unit 10 can be reduced, and the responsiveness of the snubber circuit unit 10 can be improved.

At this time, since the switching unit 50 and the snubber circuit unit 10 are arranged close to each other in the case 40, a surge voltage (a voltage generated between the semiconductor chip on which the switching unit 50 is formed and the terminals 1 and 2). Internal surge voltage). That is, in the above-mentioned conventional power module, since the snubber capacitor is provided outside the case, the switching unit is separated from the snubber circuit,
For this reason, the wiring inductance between the semiconductor chip on which the switching section is formed and each terminal (and therefore the internal surge voltage) cannot be reduced.

Further, the switching element 1 for the snubber circuit section
1 by applying the IGBT to the snubber circuit unit 1
The responsiveness of 0 can be greatly improved as compared with the related art.
This is due to the fact that, unlike diodes (used in conventional snubber circuits), IGBTs have little transient forward voltage.

<Second Embodiment> FIG. 3 is a schematic configuration diagram of a power module 102 according to a second embodiment. In the following description, differences from the power module 101 shown in FIG. 1 described above will be mainly described, and the same components as those described above will be denoted by the same reference numerals and the description thereof will be used. . Like the power module 101 in FIG. 1, the power module 102 includes two switching units 50 connected in series, the snubber circuit unit 10 provided in parallel with each switching unit 50, and the case 40.

As can be seen by comparing FIG. 3 with FIG. 1 described above, in the power module 102, the selective conducting element (here, a constant voltage diode) 16 is provided outside the case 40. More specifically, the case 40 of the power module 102 has metal fittings for the terminals 17 and 18 embedded in a frame 41 (see FIG. 2), and the terminals 17 and 18 are provided outside the case 40. Thus, the anode of the diode 19 serves as the terminal 17 and the electrode 14 (or I
The collector of the GBT 11 as the terminal 18 and the case 40
Has been pulled out.

The anode and cathode of the constant voltage diode 16 are electrically connected to terminals 17 and 18, respectively. Moreover, the constant voltage diode 16 is connected to the terminal 1
It is provided detachably between 7 and 18. For example, the constant voltage diode 16 can be detachably provided by screwing the anode and cathode terminals of the constant voltage diode 16 to the terminals 17 and 18.
Further, each terminal of the constant voltage diode 16 is connected to each terminal 17, 1.
8 can also be detached by soldering. The other configuration of the power module 102 is the same as that of the power module 101 (see FIG. 1).

According to the power module 102, effects similar to those of the power module 101 of FIG. 1 can be obtained. Note that the power module 101 described above is smaller because the selective conduction element 16 is provided in the case 40. On the other hand, the power module 102 has the following effects compared to the power module 101. That is, since the selective conducting element 16 of the power module 102 is detachably provided outside the case 40,
The selection conduction element 16 can be easily replaced. Therefore, the surge voltage and the snubber circuit unit switching element 1
The energy dissipated by 1 is adjustable.
In other words, the power module 102 can flexibly cope with a change in the voltage of the power supply 90 connected to the power module. Therefore, according to the power module 102, a highly versatile power module can be provided.

<Third Embodiment> FIG. 4 shows a schematic configuration diagram of a power module 103 according to a third embodiment. Like the power module 101 of FIG. 1, the power module 103 includes two switching units 50 connected in series.
And a snubber circuit section 10 provided in parallel with each switching section 50 and a case 40.

As can be seen from a comparison between FIG. 4 and FIG.
Are two power switching elements 53 connected in series
a, 53b. More specifically, the power switching elements 53a and 53b include an IGBT 54 and a diode 55, similarly to the power switching element 53 of FIG. Then, I of the power switching element 53a is
The emitter of the GBT 54 is connected to the electrode 51, and the collector of the IGBT 54 of the power switching element 53a is connected to the emitter of the IGBT 54 of the power switching element 53b. Power switching element 5
The collector of the IGBT 3b is connected to the electrode 52. An output terminal 3 is drawn out from between the power switching elements 53a and 53b connected in series. The other configuration of the power module 103 is the same as that of the power module 101 (see FIG. 1).

According to the power module 103, the same effect as the power module 101 of FIG. 1 can be obtained.

Further, according to the power module 103,
Since one snubber circuit section 10 is provided for two power switching elements 53a and 53b, the following effects can be obtained. That is, each power switching element 53
The number of snubber circuit units 10 can be reduced as compared with the case where snubber circuit units 10 are provided in a and 53b, respectively. Therefore, according to the power module 103, an inexpensive power module can be provided by simplifying the configuration.

The switching section 50 may include three or more power switching elements connected in series.

<Embodiment 4> In view of the power module 103 shown in FIG. 4, the power module 104 shown in FIG.
Accordingly, the same effect as that of the power module 103 can be obtained. That is, two power switching elements 5
It is also possible to configure a power module with one switching unit 50 including 3a and 53b and one snubber circuit unit 10. In the power module 104, the output terminal 3 is a dual power switching element 5 connected in series.
It is drawn out from between 3a and 53b.

Also in the power module 104, the switching unit 50 may include three or more power switching elements connected in series, and a terminal for output from a predetermined position of the power switching elements connected in series. 3
Is pulled out.

FIG. 6 shows a schematic configuration diagram of another power module 105 according to the fourth embodiment. As shown in FIG. 6, the switching unit 5 of the power module 105
0 is a power switching element 5 composed of an IGBT 54
3c and the diode 56. Specifically, the power switching element 53c has a form in which the diode 55 is removed from the power switching element 53 illustrated in FIG. The anode of the diode 56 is IGB
The collector is connected to T54, and the cathode is connected to the electrode 52. Note that the diode 56 is a freewheeling diode. Other configurations are the same as those of the power module 104 shown in FIG. The power modules 103 and 104 are also provided by the power module 105.
The same effect as described above can be obtained.

The connection positions of the power switching element 53c and the diode 56 may be interchanged.

<Modification 1> As described above, it is also possible to apply an element or circuit having a breakover characteristic to the selected conductive element 16. For example, a thyristor breakover characteristic can be used between the electrodes 12 and 14, and in this case, a predetermined gate current is applied to the gate of the thyristor for use. Shockley diode (also called PNPN switch or 4-layer diode)
May be used.

<Modification 2> The power module 10
3 to 105 (see FIGS. 4 to 6)
May be provided outside the case 40 like the power module 102 shown in FIG. 3 described above.

<Modification 3> The power module 10
The configurations of the two snubber circuit units 10 of 1 to 103 (see FIGS. 1, 3 and 4) may be different from each other. For example, only the selective conducting element 16 of one snubber circuit unit 10 may be provided outside the case 40. Further, the configurations of the two switching units 50 of the power modules 101 to 103 may be different from each other. The same applies to the configuration of the two power switching elements 53a and 53b of the power module 104 (see FIG. 5).

[0049]

(1) According to the first aspect of the present invention, unlike the conventional snubber circuit, the snubber circuit does not have a snubber capacitor, so that the snubber circuit can be housed in the case. . Therefore, the size of the power module can be reduced as compared with the conventional configuration in which the snubber capacitor is provided outside the power module.

Further, since the snubber circuit section is housed in the case, the switching section and the snubber circuit section can be closer to each other than the above-described conventional power module. For this reason, the wiring inductance between the switching unit and the snubber circuit unit can be reduced, thereby improving the responsiveness of the snubber circuit unit. At this time, according to the power module, the internal surge voltage that cannot be removed by the conventional snubber circuit can be reduced.

(2) According to the second aspect of the present invention, since the selective conducting element of the snubber circuit portion is housed in the case, it is possible to further promote the above-described effects of downsizing and improving responsiveness. it can.

(3) According to the third aspect of the invention, the selective conducting element can be easily replaced. For this reason, it is possible to flexibly cope with a change in the power supply voltage connected to the power module, so that a highly versatile power module can be provided.

(4) According to the invention of claim 4, one snubber circuit section is provided for a plurality of power semiconductor switching elements. Therefore, the number of snubber circuit sections can be reduced as compared with the case where a snubber circuit section is provided for each of the plurality of power semiconductor switching elements. Therefore, the configuration of the power module can be simplified, and an inexpensive power module can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a power module according to a first embodiment.

FIG. 2 is a schematic sectional view of the power module according to the first embodiment.

FIG. 3 is a schematic configuration diagram of a power module according to a second embodiment.

FIG. 4 is a schematic configuration diagram of a power module according to a third embodiment.

FIG. 5 is a schematic configuration diagram of a power module according to a fourth embodiment.

FIG. 6 is a schematic configuration diagram of another power module according to Embodiment 4.

[Explanation of symbols]

Reference Signs List 10 snubber circuit section, 11 semiconductor switching element for snubber circuit section, 12 control electrode, 13 third electrode, 14
4th electrode, 15 resistance, 16 selective conduction element, 17, 1
8 terminals, 19, 55, 56 diode, 40 case, 41 frame, 42 lid, 43 base plate for heat radiation, 50
Switching unit, 51 first electrode, 52 second electrode,
53, 53a, 53b, 53c power semiconductor switching element, 54 IGBT, 101, 102, 103,
104, 105 power module.

Claims (4)

[Claims] A switching unit having a first electrode, a second electrode, and at least one power semiconductor switching element provided between the first electrode and the second electrode; A snubber circuit portion provided in parallel with the switching portion between the second electrode and the case; and a snubber circuit portion, a third electrode connected to the first electrode, and a second electrode. A semiconductor switching element for a snubber circuit unit having a fourth electrode connected to the control electrode; a resistor connected between the third electrode and the control electrode; and a fourth electrode and the control electrode. A selective conduction element connected between the power semiconductor switching element and the snubber circuit unit, and the resistance is selected from the group consisting of: Characterized in that it is housed in the over scan, the power module. 2. The power module according to claim 1, wherein the selective conduction element is further housed in the case. 3. The power module according to claim 1, wherein the selective conduction element is detachably provided outside the case. 4. The power module according to claim 1, wherein the at least one power semiconductor switching element includes a plurality of power semiconductor switching elements connected in series. Power module.