JP4323073B2 - Power module - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power module, and more particularly to a power module provided with a snubber circuit or a protection circuit.
[0002]
[Prior art]
Generally, a power semiconductor switching element such as an insulated gate bipolar transistor (hereinafter also referred to as “IGBT”) is used to absorb a surge voltage generated when the switching element is opened / closed (ON / OFF). A snubber circuit is provided.
[0003]
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.
[0004]
At this time, a large-capacity capacitor is used as a snubber capacitor in order to sufficiently absorb the surge voltage. Since the large-capacitance capacitor is large, the capacitor is further susceptible to heat. Therefore, the snubber capacitor is provided outside the case in which the power semiconductor switching element is accommodated.
[0005]
[Problems to be solved by the invention]
As described above, in the conventional snubber circuit, since the snubber capacitor is provided outside the case, it takes time until the snubber circuit operates due to the inductance of the wiring connecting the power semiconductor switching element and the snubber capacitor. It will take. Furthermore, the transient forward voltage of the diode constituting the snubber circuit can also contribute to the decrease in the response 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.
[0006]
Furthermore, since the snubber capacitor is large and provided outside the case as described above, there is a problem that the entire power module including the snubber circuit becomes large.
[0007]
This invention is made | formed in view of this point, and makes it the 1st objective to aim at the improvement of the responsiveness of a power module provided with the snubber circuit part, and size reduction.
[0008]
Furthermore, a second object of the present invention is to provide a power module with high versatility while realizing the first object.
[0009]
Furthermore, a third object of the present invention is to realize the first object and to provide the power module at a low cost.
[0010]
[Means for Solving the Problems]
(1) The power module according to claim 1 includes 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 unit provided in parallel with the switching unit between the first electrode and the second electrode, and a case, wherein the snubber circuit unit is connected to the first electrode. A semiconductor switching element for a snubber circuit portion having three electrodes, a fourth electrode connected to the second electrode, and a control electrode, a resistor connected between the third electrode and the control electrode, A selective conduction element connected between the fourth electrode and the control electrode and conducting when an applied voltage exceeds a predetermined value, at least the power semiconductor switching element and the snubber circuit portion semiconductor switching element Element and the resistor are housed in the casing, the selection conductive element and being provided detachably in the outside of the case.
[0013]
( 2 ) The power module according to claim 2 is 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. It is characterized by.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
<Embodiment 1>
FIG. 1 shows a schematic configuration diagram of a power module 101 according to the 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 simplification of description, the two switching units 50 have the same configuration, and FIG. 1 (and drawings to be described later) only shows a specific circuit configuration. The same applies to the snubber circuit unit 10.
[0015]
As shown in FIG. 1, each switching unit 50 includes a first electrode 51 and a second electrode 52. The first electrode 51 and the second electrode 52 are also simply referred to as “electrode 51” and “electrode 52”, respectively.
[0016]
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 the second electrode of the other switching unit 50 (right side in FIG. 1). One electrode 51 is connected. The second electrode 52 of the other switching unit is connected to the terminal 2. Further, the output terminal 3 is drawn from between the switching units 50 connected in series. The power module 101 is used by connecting the terminal 1 to the low potential side of the power source 90 and connecting the terminal 2 to the high potential side of the power source 90.
[0017]
Specifically, the switching unit 50 includes a power semiconductor switching element (hereinafter also referred to as “power switching element”) 53 connected between the electrodes 51 and 52, and the switching element 53 is an insulated gate bipolar transistor (hereinafter “IGBT”). And a diode 55. 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 cathode of the diode 55 is connected to the collector. Note that a transistor, a MOSFET, or the like may be used instead of the IGBT 54.
[0018]
And the snubber circuit part 10 is connected in parallel with each switching part 50 between the electrodes 51 and 52 of each switching part 50, respectively. Specifically, the snubber circuit unit 10 includes a snubber circuit unit semiconductor switching element (hereinafter also referred to as “snubber circuit unit switching element”) 11, a resistor 15, a selective conduction element 16, and a diode 19.
[0019]
Here, the case where the snubber circuit unit switching element 11 is made of an IGBT will be described, and the IGBT is also referred to as “IGBT 11” by the reference numeral of the snubber circuit unit switching element 11. In addition, you may apply another element (for example, a transistor, MOSFET, etc.) and a circuit to the switching element 11 for snubber circuit parts.
[0020]
The selective conduction element is an element that conducts or exhibits good conductivity when an applied voltage exceeds a predetermined value. Specifically, when the absolute value of the applied voltage is increased, when the predetermined voltage is exceeded, the current value changes abruptly or becomes lower than that before the predetermined voltage, such as a breakdown characteristic. And elements 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 is applicable. Here, the case where the selective conduction element 16 is composed of a constant voltage diode will be described, and the constant voltage diode is also referred to as a “constant voltage diode 16” with the reference numeral of the selection conduction element 16.
[0021]
The snubber circuit switching element 11 includes 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 14 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, emitter, and 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.
[0022]
Further, a resistor 15 is connected between the electrodes 12 and 13. A diode 19 and a constant voltage diode 16 are connected in series between the electrodes 12 and 14. More specifically, the cathode of the diode 19 is connected to the electrode 12, the anode of the diode 19 is connected to the anode of the constant voltage diode 16, and the cathode of the constant voltage diode 16 is connected to the electrode 14. .
[0023]
In particular, in the power module 101, the entire switching unit 50 and snubber circuit unit 10 are accommodated in the case 40. That is, the power switching element 53, the snubber circuit section switching element 11, the resistor 15, the selective conduction element 16, and the diodes 55 and 19 are housed in the case 40.
[0024]
Next, FIG. 2 shows a schematic sectional view of the power module 101. As shown in FIG. 2, in the power module 101, a case 40 is configured by a frame 41, a lid 42, and a base plate 43.
[0025]
More specifically, for example, a ceramic substrate 71 is disposed on a heat dissipation base plate (hereinafter also simply referred to as “base plate”) 43 made of copper via a copper foil 72b, and the switching unit 50 or the snubber is disposed on the ceramic substrate 71. Each semiconductor chip on which the circuit unit 10 is formed is arranged via a copper foil 72a. The copper foils 72a and 72b are formed on each main surface of the ceramic substrate 71. For convenience of illustration, FIG. 2 shows each semiconductor chip of the switching unit 50 and the snubber circuit unit 10 one by one.
[0026]
A frame 41 surrounding both the semiconductor chip and the ceramic substrate 71 and in contact with the base plate 43 is disposed, and the base plate 43 and the frame 41 form a container shape. The frame 41 is made of an insulating material such as resin. In the frame 41, metal fittings for terminals 1 to 3 and terminals (not shown in FIG. 2) connected to the gate of the IGBT 54 are embedded, and portions exposed to the outside of the case 40 of each metal fitting are the terminals. Is made. The ends of the metal fittings in the case 40 are connected to predetermined locations such as the semiconductor chips and the copper foil 72a by wires 73.
[0027]
The container formed of 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, and further, an epoxy resin 45 is filled on the silicon gel 44. A lid 42 made of an insulating material such as a resin is disposed on the epoxy resin 45, whereby the vessel formed by the base plate 43 and the frame 41 is covered. As long as the power switching element 53, the snubber circuit switching element 11, the resistor 15, the selective conduction element 16, and the diodes 55 and 19 can be accommodated, other forms of cases may be applied.
[0028]
Next, the operation of the snubber circuit unit 10 will be described with reference to FIG. When the IGBT 54 of the power switching element 53 is turned on / off, a surge voltage is likely to be generated between the collector and the emitter of the IGBT 54. At this time, when the surge voltage is larger than the breakdown voltage of the constant voltage diode 16, a current flows through the constant voltage diode 16, the diode 19 and the resistor 15 in the snubber circuit unit 10. When the voltage between the gate and emitter (or between the electrodes 12 and 13) of the IGBT 11 of the snubber circuit portion 10 rises and the gate-emitter voltage exceeds the threshold voltage of the IGBT 11, the IGBT 11 is turned on. Thereby, the energy stored in the wiring is consumed by the IGBT 11, and the surge voltage is suppressed. In other words, based on the voltage value of the surge voltage to be suppressed, the breakdown voltage of the constant voltage diode 16 and the resistance value of the resistor 15 are set. 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 free wheeling diode.
[0029]
According to the power module 101, the following effects can be obtained. First, unlike the conventional snubber circuit, the snubber circuit unit 10 of the power module 101 does not have a snubber capacitor. For this reason, the whole snubber circuit part 10 can be accommodated in the case 40. Therefore, the power module can be reduced in size as compared with the conventional configuration having a snubber capacitor outside the case.
[0030]
Furthermore, since the snubber circuit unit 10 is housed in the case 40, the switching unit 50 and the snubber circuit unit 10 can be brought closer to each other than the conventional power module described above. For this reason, the wiring inductance between the switching part 50 and the snubber circuit part 10 can be reduced, and thereby the responsiveness of the snubber circuit part 10 can be improved.
[0031]
At this time, when the switching unit 50 and the snubber circuit unit 10 are arranged close to each other in the case 40, a surge voltage (internal surge voltage) generated between the semiconductor chip on which the switching unit 50 is formed and the terminals 1 and 2 is formed. ) Can be reduced. That is, in the above-described conventional power module, since the snubber capacitor is provided outside the case, the switching unit and the snubber circuit are separated from each other. Therefore, the wiring inductance between the semiconductor chip on which the switching unit is formed and each terminal is set to ( Therefore, the internal surge voltage could not be reduced.
[0032]
Further, by applying the IGBT to the snubber circuit portion switching element 11, the responsiveness of the snubber circuit portion 10 can be greatly improved as compared with the conventional case. This is because, unlike a diode (used in a conventional snubber circuit), an IGBT has almost no transient forward voltage.
[0033]
<Embodiment 2>
FIG. 3 shows a schematic configuration diagram of the power module 102 according to the 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 will be used. . Similar to the power module 101 in FIG. 1, the power module 102 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.
[0034]
As can be seen from a comparison between FIG. 3 and FIG. 1 described above, in the power module 102, a selective conducting element (here, a constant voltage diode) 16 is provided outside the case 40. Specifically, the case 40 of the power module 102 has a metal frame forming terminals 17 and 18 embedded in a frame 41 (see FIG. 2), and the terminals 17 and 18 are provided outside the case 40. As a result, the anode of the diode 19 is pulled out as the terminal 17, and the electrode 14 (or the collector of the IGBT 11) is pulled out as the terminal 18 to the outside of the case 40.
[0035]
The anode and cathode of the constant voltage diode 16 are electrically connected to the terminals 17 and 18, respectively. Moreover, the constant voltage diode 16 is detachably provided between the terminals 17 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. The terminal can also be attached / detached by soldering each terminal of the constant voltage diode 16 to each terminal 17, 18. The other configuration of the power module 102 is the same as that of the power module 101 (see FIG. 1).
[0036]
According to the power module 102, the same effect as that of the power module 101 in FIG. 1 can be obtained. It should be noted that the power module 101 described above is smaller in size 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 conduction element 16 of the power module 102 is detachably provided outside the case 40, the selective conduction element 16 can be easily replaced. For this reason, the energy consumed by the surge voltage and the snubber circuit unit switching element 11 can be adjusted. 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.
[0037]
<Embodiment 3>
FIG. 4 shows a schematic configuration diagram of the power module 103 according to the third embodiment. Similar to the power module 101 of FIG. 1, the power module 103 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.
[0038]
As can be seen from a comparison between FIG. 4 and FIG. 1 described above, in the power module 103, the switching unit 50 includes two power switching elements 53a and 53b connected in series. Specifically, the power switching elements 53a and 53b are composed of an IGBT 54 and a diode 55, like the power switching element 53 of FIG. The emitter of the IGBT 54 of the power switching element 53a 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. The collector of the IGBT 54 of the power switching element 53 b is connected to the electrode 52. An output terminal 3 is drawn 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).
[0039]
According to the power module 103, the same effect as that of the power module 101 in FIG. 1 can be obtained.
[0040]
Furthermore, according to the power module 103, since one snubber circuit unit 10 is provided for the two power switching elements 53a and 53b, the following effects can be obtained. That is, the number of snubber circuit units 10 can be reduced as compared to the case where the snubber circuit units 10 are provided in the power switching elements 53a and 53b, respectively. Therefore, according to the power module 103, an inexpensive power module can be provided by simplifying the configuration.
[0041]
The switching unit 50 may include three or more power switching elements connected in series.
[0042]
<Embodiment 4>
In view of the power module 103 in FIG. 4, the same effect as the power module 103 can be obtained by the power module 104 shown in FIG. 5. In other words, a power module can be configured by one switching unit 50 including two power switching elements 53 a and 53 b and one snubber circuit unit 10. In the power module 104, the output terminal 3 is drawn from between the power switching elements 53a and 53b connected in series.
[0043]
Also in the power module 104, the switching unit 50 may be configured to include three or more power switching elements connected in series, and the output terminal 3 is drawn from a predetermined position of the power switching elements connected in series. It is.
[0044]
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 50 of the power module 105 includes a power switching element 53 c made of an IGBT 54 and a diode 56. Specifically, the power switching element 53c corresponds to 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 connected to the collector of the IGBT 54, and the cathode is connected to the electrode 52. The diode 56 is a free wheeling diode. Other configurations are the same as those of the power module 104 shown in FIG. The power module 105 can provide the same effects as the power modules 103 and 104.
[0045]
The connection positions of the power switching element 53c and the diode 56 may be interchanged.
[0046]
<Modification 1>
As described above, an element or a circuit having a breakover characteristic can be applied to the selective conductive element 16. For example, the breakover characteristic of a thyristor 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. A Shockley diode (also called a PNPN switch or a four-layer diode) may be used.
[0047]
<Modification 2>
In addition, you may provide the selection conduction | electrical_connection element 16 of power modules 103-105 (refer FIGS. 4-6) outside the case 40 like the power module 102 shown in above-mentioned FIG.
[0048]
<Modification 3>
Moreover, you may mutually differ in the structure of the two snubber circuit parts 10 of the power modules 101-103 (refer FIG.1, FIG3 and FIG.4). For example, only the selective conduction element 16 of one snubber circuit unit 10 may be provided outside the case 40. Moreover, you may mutually differ in the structure of the two switching parts 50 of the power modules 101-103. The same applies to the configuration of the two power switching elements 53a and 53b of the power module 104 (see FIG. 5).
[0049]
【The invention's effect】
(1) According to the first aspect of the present invention, unlike the conventional snubber circuit, the snubber circuit portion does not have a snubber capacitor, so that the snubber circuit portion can be accommodated in the case. For this reason, a power module can be reduced in size compared with the conventional structure in which the snubber capacitor is provided outside the power module.
[0050]
Furthermore, since the snubber circuit unit is housed in the case, the switching unit and the snubber circuit unit can be brought closer to each other than the above-described conventional power module. For this reason, the wiring inductance between a switching part and a snubber circuit part can be reduced, and, thereby, the responsiveness of a snubber circuit part can be improved. At this time, according to the power module, an internal surge voltage that cannot be removed by a conventional snubber circuit can be reduced.
[0052]
Moreover, according to the invention which concerns on Claim 1 , a selective conduction element can be replaced | exchanged easily. For this reason, since it can respond flexibly to the change of the power supply voltage connected with a power module, a highly versatile power module can be provided.
[0053]
( 2 ) According to the invention of claim 2 , one snubber circuit section is provided for a plurality of power semiconductor switching elements. For this reason, compared with the case where a snubber circuit part is provided in each of a plurality of power semiconductor switching elements, the number of snubber circuit parts can be reduced. 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.
2 is a schematic cross-sectional view of a power module according to Embodiment 1. FIG.
FIG. 3 is a schematic configuration diagram of a power module according to a second embodiment.
4 is a schematic configuration diagram of a power module according to Embodiment 3. FIG.
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 the fourth embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Snubber circuit part, 11 Snubber circuit part semiconductor switching element, 12 Control electrode, 13 3rd electrode, 14 4th electrode, 15 Resistance, 16 Selective conduction element, 17, 18 terminal, 19, 55,56 Diode, 40 Case , 41 frame, 42 lid, 43 heat radiating base plate, 50 switching part, 51 first electrode, 52 second electrode, 53, 53a, 53b, 53c power semiconductor switching element, 54 IGBT, 101, 102, 103, 104 , 105 Power module.

Claims (2)

A switching unit having a first electrode and a second electrode, and at least one power semiconductor switching element provided between the first electrode and the second electrode;
A snubber circuit unit provided in parallel with the switching unit between the first electrode and the second electrode;
With a case,
The snubber circuit section is
A semiconductor switching element for a snubber circuit unit, comprising: a third electrode connected to the first electrode; a fourth electrode connected to the second electrode; and a control electrode;
A resistor connected between the third electrode and the control electrode;
A selective conduction element connected between the fourth electrode and the control electrode and conducting when an applied voltage exceeds a predetermined value;
At least the power semiconductor switching element, the semiconductor switching element for the snubber circuit portion, and the resistor are housed in the case ,
The selective conduction element is detachably provided outside the case ,
Power module. The power module according to claim 1,
The at least one power semiconductor switching element includes a plurality of power semiconductor switching elements connected in series .
Power module.

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