JP2018046195A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a countermeasure technique for refrigerant freezing in a semiconductor device having a laminated unit in which a semiconductor module and a cooler are laminated.SOLUTION: A power converter 2 comprises a laminated unit 20, a housing 30, a refrigerant conducting pipe 34 and a refrigerant discharging pipe 35. The laminated unit 20 is a laminate where a cooler 22 and a semiconductor module 3 which houses a transistor are laminated. The housing 30 houses the laminated unit 20. The refrigerant conducting pipe 34 conducts a liquid refrigerant from outside the housing 30 to the cooler 22. The refrigerant discharging pipe 35 discharges a liquid refrigerant from the cooler 22 to outside the housing. One ends of the refrigerant conducting pipe 34 and the refrigerant discharging pipe 35 are connected to a pair of through holes 30a formed in the housing 30, respectively; and the other ends of the refrigerant conducting pipe 34 and the refrigerant discharging pipe 35 are connected to the cooler 22. The refrigerant conducting pipe 34 and the refrigerant discharging pipe 35 are wound by heat storage materials 37, respectively.SELECTED DRAWING: Figure 2

Description

  The present specification discloses a semiconductor device including a stacked unit in which a semiconductor module containing a semiconductor element and a cooler in which a coolant channel is formed are stacked.

  For example, Patent Document 1 discloses a semiconductor device including a stacked unit in which a semiconductor module containing a semiconductor element and a cooler are stacked. The semiconductor device of Patent Document 1 is a power conversion device that converts battery power into driving power for a traveling motor. In a device in which a large current flows through a semiconductor element, such as a power conversion device for an electric vehicle, a stacked unit structure in which a semiconductor module and a cooler are stacked may be employed to cool the semiconductor module as described above. The cooler has a refrigerant flow path formed therein. A liquid refrigerant such as water or LLC (Long Life Coolant) is used as the refrigerant. Connected to the cooler of the stacked unit are an introduction pipe for introducing liquid refrigerant from the outside and a discharge pipe for discharging liquid refrigerant that has absorbed heat in the cooler to the outside. One end of the introduction pipe and the discharge pipe is connected to a through hole provided in the housing of the semiconductor device.

JP 2014-187827 A

  Although LLC is more difficult to freeze than simple water, there is a risk of freezing when semiconductor devices are used in extremely cold regions. When the semiconductor device is exposed to an extremely cold environment, the temperature of the housing first decreases, and then the temperature of the introduction pipe and the discharge pipe, and then the cooler of the stacked unit decreases. When the liquid refrigerant freezes in the introduction pipe and the discharge pipe, when the liquid refrigerant in the cooler next freezes and expands, there is no escape space for the frozen refrigerant, and the cooler expands and deforms. The present specification provides a technique for countermeasures against freezing of a refrigerant in a semiconductor device including a stacked unit.

  A semiconductor device disclosed in this specification includes a stacked unit, a housing that houses the stacked unit, an introduction pipe, and a discharge pipe. As described above, the stacked unit is a device in which a semiconductor module containing a semiconductor element and a cooler are stacked. The cooler is provided with a refrigerant flow path therein. The introduction pipe is a member that introduces liquid refrigerant into the cooler from the outside of the casing. The discharge pipe is a member that discharges the liquid refrigerant from the cooler to the outside of the housing. One end of each of the introduction pipe and the discharge pipe is connected to each of a pair of through holes provided in the housing, and the other end of each of the introduction pipe and the discharge pipe is connected to a cooler. In the semiconductor device disclosed in this specification, a heat storage material is wound around each of the introduction pipe and the discharge pipe.

  In the semiconductor device disclosed in this specification, the refrigerant freeze in the introduction pipe and the discharge pipe is delayed by winding the heat storage material. By doing so, the cooler can be made difficult to freeze at low cost. In addition, when the refrigerant begins to freeze in the cooler, if the introduction pipe and the discharge pipe are not blocked by the frozen refrigerant due to the heat storage material, at least one of the volume expansion of the refrigerant in the cooler. The part can be discharged to the outside through the introduction pipe and the discharge pipe, and the expansion deformation of the cooler can be reduced. Details and further improvements of the technology disclosed in this specification will be described in the following “DETAILED DESCRIPTION”.

It is a block diagram of the electric power system of the electric vehicle containing the semiconductor device (power converter) of an Example. It is a top view which shows the component layout inside the housing | casing of a power converter. It is a front view which shows the component layout inside the housing | casing of a power converter. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 2.

  A semiconductor device according to an embodiment will be described with reference to the drawings. The semiconductor device according to the embodiment is a power converter 2 mounted on an electric vehicle. First, the electric system of the electric vehicle 100 including the power converter 2 will be described. FIG. 1 is a block diagram of a power system of an electric vehicle 100 including a power converter 2. The power converter 2 is a device that boosts the DC power of the battery 13, converts it to AC, and supplies it to the traveling motors 15 a and 15 b. The DC side of the power converter 2 is connected to the battery 13 via the system main relay 14, and the AC side is connected to the two motors 15a and 15b.

  The electric vehicle 100 combines the outputs of the two motors 15 a and 15 b with the gear box 16 and transmits power to the axle 17 to travel. The electric vehicle 100 can also generate electric power by reversely driving the motors 15a and 15b from the axle side using the kinetic energy of the vehicle. The battery 13 is charged with the power obtained by the power generation. The power obtained by power generation is sometimes called regenerative power.

  The power converter 2 includes a converter 12 that boosts the voltage of the battery 13 and two inverters 10a and 10b that convert DC power into AC power. The converter 12 includes a filter capacitor 4, a reactor 5, two transistors 9a and 9b, and two diodes. The two transistors 9a and 9b are connected in series, and a diode is connected in antiparallel to each of the transistors 9a and 9b. Transistors 9a and 9b and diodes, that is, a range surrounded by a broken line 3a in FIG. 1, corresponds to a semiconductor module 3a described later. In addition to the function of boosting the voltage of the battery 13, the converter 12 has a function of stepping down the voltage of the regenerative power sent from the inverters 10a and 10b and supplying the voltage to the battery 13, so-called bidirectional DC. -DC converter. Since the circuit configuration of the converter 12 in FIG. 1 is well known, detailed description thereof is omitted.

  The inverter 10a includes six transistors 9c-9h and a diode connected in antiparallel to each transistor. Two of the six transistors 9c-9h are connected in series (transistors 9c and 9d, 9e and 9f, and 9g and 9h are connected in series, respectively). The three sets of series connections are connected in parallel. AC is output from the midpoint of each series connection. Dashed lines 3b, 3c, and 3d correspond to semiconductor modules, respectively.

  The inverter 10b has the same configuration as the inverter 10a. That is, the inverter 10b also includes three semiconductor modules 3e, 3f, and 3g. Each semiconductor module 3e-3g includes two transistors and two diodes. A smoothing capacitor 6 is connected in parallel between the converter 12 and the inverters 10a and 10b.

  The transistors of the seven semiconductor modules 3a to 3g operate by receiving drive signals (PWM signals) from a controller (not shown). Hereinafter, when any one of the seven semiconductor modules 3a to 3g is shown without distinction, it is referred to as a semiconductor module 3.

  A hardware configuration of the power converter 2 will be described. FIG. 2 shows a plan view of the power converter 2. FIG. 2 is a plan view showing a component layout inside the housing 30 with the cover removed. FIG. 3 shows a front view of the power converter 2. FIG. 3 is a front view showing a component layout inside the housing 30 by cutting the right housing wall in FIG. 2.

  The seven semiconductor modules 3 together with the eight coolers 22 constitute a stacked unit 20. In FIG. 2, reference numeral 22 is given only to the coolers at both ends of the laminated unit 20, and reference numerals are omitted for the other coolers. The stacked unit 20 is a stacked body in which seven semiconductor modules 3 and eight coolers 22 are alternately stacked one by one. The cooler 22 is provided with a flow path through which the liquid refrigerant passes. A pair of coolers 22 adjacent to each other with one semiconductor module 3 interposed therebetween are connected by two connecting pipes 23. In FIG. 2, reference numeral 23 is attached to only one connecting pipe, and reference numerals are omitted for the other connecting pipes. All the coolers 22 communicate with each other through the connecting pipe 23.

  In FIG. 2, a refrigerant introduction pipe 34 and a refrigerant discharge pipe 35 are connected to the rightmost cooler 22. One of the two connecting pipes 23 is positioned so as to overlap the refrigerant introduction pipe 34 as viewed from the stacking direction (X direction in the figure), and the other connecting pipe 23 is positioned so as to overlap the refrigerant discharge pipe 35. doing. The refrigerant introduction pipe 34 and the refrigerant discharge pipe 35 pass through a through hole 30 a provided in the casing 30, and one end protrudes to the outside of the casing 30. A refrigerant circulation device (not shown) is connected to the refrigerant introduction pipe 34 and the refrigerant discharge pipe 35. The liquid refrigerant supplied through the refrigerant introduction pipe 34 is distributed to all the coolers 22 through one connection pipe 23 that connects the adjacent coolers 22. The liquid refrigerant absorbs heat from the adjacent semiconductor module 3 while passing through each cooler 22 and is discharged out of the power converter 2 through the other connecting pipe 23 and the refrigerant discharge pipe 35 (to the refrigerant circulation device). Is returned).

  Three power terminals 25 (a positive terminal 25a, a negative terminal 25b, and a midpoint terminal 25c) extend from the upper surface of each semiconductor module 3. A plurality of control terminals 27 extend from the lower surface of each semiconductor module 3 (see FIG. 3). Each semiconductor module 3 accommodates a series connection of two transistors, and the positive electrode terminal 25 a is connected to the high potential side of the series connection inside the main body 21 of the semiconductor module 3. The negative electrode terminal 25b is connected to the low potential side in series connection inside the main body 21, and the midpoint terminal 25c is connected to the midpoint of series connection. The positive terminal 25a and the negative terminal 25b of each semiconductor module 3 are connected to the smoothing capacitor 6 via the positive bus bar 31 and the negative bus bar 32, respectively. 2 and 3, the connection destination of the midpoint terminal 25c of each semiconductor module 3 is not shown.

  The control terminal 27 is connected to a gate terminal connected to the gate of each transistor inside the semiconductor module 3, a sense emitter terminal connected to the sense emitter of each transistor, and a temperature sensor built in the semiconductor module 3. Sensor terminals. The control terminal is connected to the control unit 29 disposed below the stacked unit 20. The control board 29 receives a command from an upper controller (not shown) and supplies a drive signal to each transistor housed in each semiconductor module 3.

  One end of the stacking unit 20 of the plurality of semiconductor modules 3 and the plurality of coolers 22 in the stacking direction is in contact with the support wall 36 provided in the housing 30, and the other end is in contact with the support pillar 38 via the leaf spring 33. It is supported. The laminated unit 20 receives a load in the laminating direction by the leaf spring 33. Due to the load in the stacking direction, the cooler 22 and the semiconductor module 3 are in close contact with each other, and the efficiency of heat transfer from the semiconductor module 3 to the cooler 22 is increased. A filter capacitor 4, a reactor 5, and a smoothing capacitor 6 are disposed around the multilayer unit 20. The connection between them and the laminated unit 20 is omitted except for the bus bars 31 and 32.

  As described above, one end of each of the refrigerant introduction pipe 34 and the refrigerant discharge pipe 35 is connected to each of the pair of through holes 30a provided in the housing 30, and the refrigerant introduction pipe 34 and the refrigerant discharge pipe Each other end of 35 is connected to a cooler 22 at the end of the laminated unit 20. A heat storage material 37 is wound around each of the refrigerant introduction pipe 34 and the refrigerant discharge pipe 35. The heat storage material 37 is made of, for example, zeolite or paraffin.

  A temperature sensor 39 is attached to the surface of the heat storage material 37 wound around the refrigerant discharge pipe 35. The temperature sensor 39 measures the surface temperature of the heat storage material 37. The signal line of the temperature sensor 39 is connected to the control board 29 located below the laminated unit 20.

  The advantages of the heat storage material 37 will be described. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. FIG. 4 shows a cross section of the laminated unit 20 in which the refrigerant introduction pipe 34 is cut in parallel to the axis thereof. FIG. 4 shows a cross section of the laminated unit 20 and a partial cross section of the housing 30, and other components are not shown. Each cooler 22 is made of an aluminum plate, and its inside is a simple cavity. The cooler 22 is a simple container having several holes, and the internal space serves as a refrigerant flow path. A plurality of fins that contact the inner surface of the case of the cooler 22 may be provided in the internal space of the cooler 22.

  The refrigerant supplied via the refrigerant introduction pipe 34 is distributed to each cooler 22 via the connection pipe 23. The refrigerant is liquid LLC (Long Life Coolant), but may freeze when the outside air temperature becomes extremely low. If the electric vehicle 100 is employed in an extremely cold region, the refrigerant may freeze. When the power converter 2 is exposed to an extremely cold environment, the temperature of the casing 30 first decreases, and then the temperature of the refrigerant introduction pipe 34 and the refrigerant discharge pipe 35 that are in contact with the casing 30 and the stacked unit 20 in that order. Will go down. If the liquid refrigerant freezes in the refrigerant introduction pipe 34 and the refrigerant discharge pipe 35, the next time the liquid refrigerant in the cooler 22 freezes and expands, there is no escape space for the refrigerant, and the cooler 22 expands and deforms. By winding the heat storage material 37, it is possible to delay the refrigerant freezing in the refrigerant introduction pipe 34 and the refrigerant discharge pipe 35 (location indicated by reference numeral S1 in FIG. 4). By doing so, it is possible to make the refrigerant inside the cooler 22 difficult to freeze at a low cost. Further, when the refrigerant begins to freeze in the cooler 22 (for example, the location indicated by S2 in FIG. 4), the refrigerant introduction pipe 34 and the refrigerant discharge pipe 35 are blocked by the frozen refrigerant because of the heat storage material 37. If not, at least a part of the volume expansion of the refrigerant in the cooler 22 can be discharged to the outside through the refrigerant introduction pipe 34 and the refrigerant discharge pipe 35, and expansion deformation of the cooler 22 can be reduced.

  Further, when the refrigerant inside the refrigerant introduction pipe 34 is likely to freeze, the power converter 2 operates an external refrigerant circulation device (not shown) connected to the refrigerant introduction pipe 34 and the refrigerant discharge pipe 35, thereby To prevent freezing. As described above, the temperature sensor 39 is attached to the surface of the heat storage material 37 wound around the refrigerant introduction pipe 34 (see FIGS. 2 and 3). A freeze prevention program is mounted on the control board 29 and periodically monitors the temperature of the temperature sensor 39. When the surface temperature of the heat storage material 37 acquired by the temperature sensor 39 falls below a predetermined temperature (for example, minus 20 ° C.), the freeze prevention program for the control board 29 operates the external refrigerant circulation device for a certain time (for example, 30 minutes). . By operating the refrigerant circulation device, the refrigerant in the plurality of coolers 22 of the stacked unit 20 is circulated and agitated, and the refrigerant is prevented from freezing.

  As a modification, the control board 29 may operate the transistor inside the semiconductor module 3 when the surface temperature of the heat storage material 37 falls below a predetermined temperature. The heat generation of the transistor prevents the refrigerant from freezing.

  Points to be noted regarding the technology described in the embodiments will be described. The power converter 2 of the embodiment corresponds to an example of “semiconductor device” in the claims. The technology disclosed in this specification is not limited to a power converter for an electric vehicle, and may be another device. The refrigerant introduction pipe 34 and the refrigerant discharge pipe 35 of the embodiment correspond to examples of “introduction pipe” and “discharge pipe” in the claims, respectively. The transistors 9a to 9h in the example correspond to an example of “semiconductor element” in the claims.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

2: Power converter 3, 3a-3g: Semiconductor module 4: Filter capacitor 5: Reactor 6: Smoothing capacitor 9a-9h: Transistor 10a, 10b: Inverter 12: Converter 13: Battery 14: System main relay 15a, 15b: Motor 16: Gearbox 17: Axle 20: Laminating unit 21: Main body 22: Cooler 23: Connecting pipe 25a: Positive terminal 25b: Negative terminal 25c: Midpoint terminal 27: Control terminal 29: Control board 30: Housing 30a: Through hole 31: Positive electrode bus bar 32: Negative electrode bus bar 33: Leaf spring 34: Refrigerant introduction pipe 35: Refrigerant discharge pipe 36: Support wall 37: Thermal storage material 38: Support column 39: Temperature sensor 100: Electric vehicle

Claims (1)

A laminated unit in which a semiconductor module containing a semiconductor element and a cooler in which a coolant channel is formed are laminated;
A housing for accommodating the laminated unit;
An introduction pipe for introducing liquid refrigerant into the cooler from the outside of the housing;
A discharge pipe for discharging the liquid refrigerant from the cooler to the outside of the housing;
With
One end of each of the introduction pipe and the discharge pipe is connected to each of a pair of through holes provided in the casing, and the other end of each of the introduction pipe and the discharge pipe is connected to the cooler. Has been
A semiconductor device in which a heat storage material is wound around each of the introduction pipe and the discharge pipe.

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