JP5135420B2 - Power converter - Google Patents

Description

  The present invention relates to a technique for providing a power converter that supplies power to, for example, a motor.

  In a power conversion device, a power element semiconductor element including an IGBT or a diode that performs power conversion normally generates a large amount of heat, and therefore, by means of forced air cooling using air intake and exhaust by a fan in a heat dissipation part having fins. Dissipates heat.

  However, sufficient heat dissipation cannot be performed by the fan and the heat radiating section, and the temperature inside the casing rises, which may cause the temperature of elements other than the power element semiconductor element to increase.

  In particular, control semiconductor elements such as CPUs have a temperature that guarantees normal operation (hereinafter referred to as operation guarantee temperature) is lower than that of power element semiconductors. In some cases, normal control may not be possible due to thermal runaway or the like.

  In general, it is said that a semiconductor element is destroyed when it exceeds about 150 ° C., and there is a device for efficiently dissipating the semiconductor element such as the CPU, which is disclosed in Patent Document 1, for example.

  Patent Document 1 discloses a technique for cooling a low-temperature-use product other than the power semiconductor device by a cooling action of a cooling fan that cools the power semiconductor device.

JP 7-95771 A

  However, in the technique described in Patent Document 1, although the low-temperature product and CPU other than the power semiconductor device and the power element semiconductor are forcibly air-cooled by the cooling fan, the entire device has a complicated configuration, and the device itself It has a configuration that leads to an increase in size. For example, power semiconductor devices and low-temperature products are arranged separately in the housing using partition plates, and spaces are provided to provide air flow passages for forced air cooling of each, resulting in a large device. ing.

  Accordingly, an object of the present invention is to radiate heat inside the apparatus and the housing while taking into consideration the miniaturization of the apparatus.

  The present invention solves the above problem as follows.

  A base, a housing covering the base, a power semiconductor element disposed on the base and between the base and the housing, and a circuit board disposed between the base and the housing An MCU or CPU disposed on the circuit board between the housing and the circuit board; a fin having a height of 50 mm disposed on the back side of the surface on which the power semiconductor is disposed; Air that is connected to the housing and is sucked from one end side of a space formed by the base and the housing, the air that has cooled the power semiconductor element, the circuit board, and the housing A guide portion that guides air that has been sucked from one end side of the space formed between the two sides and cooled the MCU or CPU to the intake surface of the fin, and an exhaust surface side that faces the intake surface of the fin. And Taking of said fan power semiconductor is arranged on the back surface of the disposed surface, a structure that comprises a.

  ADVANTAGE OF THE INVENTION According to this invention, improvement can be aimed at about the reduction countermeasure of the temperature rise of the electronic component arrange | positioned inside an apparatus, or a thermal radiation part. It is also possible to reduce the size of the apparatus.

It is a conceptual diagram of the Example of this invention. It is an Example (side view) of this invention. It is the Example (the figure seen from the depth direction) of this invention. (A) It is a characteristic view by simulation at the time of changing the length of a guide part using a high air volume type cooling fan. (B) It is a characteristic view by simulation at the time of changing the length of a cooling fin and a guide part using a calming type cooling fan. It is a characteristic view by simulation at the time of changing the clearance gap between a cooling fin and a guide part using a calming type cooling fan. It is a characteristic view by another simulation at the time of changing the clearance gap between a cooling fin and a guide part using a calming type cooling fan. It is an actual machine comparison table between the conventional apparatus and the present invention apparatus. It is another Example of this invention.

FIG. 1 is a conceptual diagram of an embodiment according to the present invention, and shows a side view as viewed from the side in a state where a power conversion device is attached to an attachment surface such as a wall of equipment. Moreover, FIG. 2 shows the side view of the Example at the time of implementing with a product. (However, the left direction in FIG. 2 is the upper side when it is actually attached.)
In FIG. 1, the power conversion device includes a heat radiating portion 4, a cooling fan 5, a sealing material 7, a power element semiconductor 8 such as an IGBT or a diode, a metal substrate 9, a device case (housing) 10, and a substrate built in the device. 11, a base 20 of the heat radiating unit 4, fins 21 for radiating heat from the heat radiating unit 4, and a semiconductor 22 such as MCU (referred to as a Micro Controla Unit, including a semiconductor chip of a CPU). In general, the power element semiconductor 8 corresponds to a semiconductor element or substrate that generates a large amount of heat. The semiconductor element or substrate that generates a relatively small amount of heat is referred to as the MCU (Micro Controla Unit), which is a semiconductor chip of a CPU or the like. In the following, description will be made based on this.

  The housing 10 is provided with a guide portion 19 that allows air to be taken in so as to generate an air flow that passes over the power element semiconductor 8 and cools the heat of the power element semiconductor 8.

  First, the heat radiating part 4 is composed of a base 20 and fins 21 (shown in FIG. 3 is a structural view seen from another angle). The base 20 is a portion that receives heat conduction from the heating element, and the fins 21 receive heat conduction from the base 20 and transfer heat to the ambient atmosphere to dissipate heat.

  Next, a power element semiconductor 8 such as an IGBT or a diode is mounted on a metal substrate 9 and is generally sealed with a sealing material (resin material) 7.

  In the power converter, in the power element semiconductor 8 such as IGBT or diode, most of the generated heat is thermally conducted to the base 20 of the heat radiating unit 4 due to conversion loss or the like.

  In the heat radiating unit 4, a gas such as air in the ambient atmosphere sucked from the intake surface shown in FIG. 1 is exhausted into the ambient atmosphere by the cooling fan 5 provided on the exhaust surface. When the gas such as the sucked air passes through the fins 21, the heat conducted to the fins 21 and the like of the heat radiating portion 4 is taken away by the sucked gas and exhausted into the surrounding atmosphere, thereby radiating heat. The part 4 is dissipated.

  On the other hand, the heat generated from the power element semiconductor 8 or the like toward the inside of the housing uses part of the wind generated by the cooling fan 5 by the guide portion 19 provided in the housing 10 as shown in FIG. Then, forced air cooling is performed.

  In this embodiment, as shown in FIG. 1, the apparatus is miniaturized by arranging a substrate including the power element semiconductor 8 and a substrate including the semiconductor 22 such as MCU in the same casing.

  However, since the power element semiconductor 8 generates a considerable amount of heat, when the gas heated by the power element semiconductor 8 flows into the substrate including the semiconductor 22 such as MCU during the forced air cooling, the power element semiconductor 8 is heated. As a result, the temperature of the semiconductor 22 such as MCU is increased.

  Therefore, the substrate including the power element semiconductor 8 is disposed apart from the substrate including the MCU or other semiconductor 22 within a range allowed for mounting. Then, the position of the substrate including the power element semiconductor 8 is made so-called leeward as the gas flow during forced air cooling than the substrate including the semiconductor 22 such as the MCU. Therefore, as shown in FIG. 1, the substrate including the power element semiconductor 8 is disposed closer to the intake surface of the heat radiating portion 4 than the substrate including the semiconductor 22 such as MCU.

  With this arrangement, the gas heated by the power element semiconductor 8 is prevented from flowing into the substrate including the semiconductor 22 such as the MCU and increasing the temperature.

  The arrangement is not limited to the position of each substrate, and the power element semiconductor 8 itself may be devised so as to be located closer to the intake surface even on the substrate.

  Next, the figure seen in the depth direction in the product of the thermal radiation part 4 in FIG. 3 is shown.

  As shown in FIG. 3, the heat radiating portion 4 has a base 20 and fins 21, and gas sucked from the intake surface passes through the fins 21.

  In addition, the height H of the heat radiating part 4 to be described later is the length to the position where the fins 21 are attached to the base 20 as shown in FIG.

  Here, FIG. 4 shows the result of verification by simulation about the length of the overlapping length of the heat radiating portion and the guide portion in the embodiment of FIG. FIG. 4 shows the temperature on the heat radiation part 4, the temperature on the sealing material 7, and the temperature on the MCU 22 (including the CPU semiconductor chip and the like). Since the power element semiconductor 8 is sealed with the sealing material 7, the measured temperature is also the temperature of the sealing material 7. Therefore, hereinafter, the temperature of the encapsulant 7 will be described instead of the temperature of the power element semiconductor 8.

  First, the simulation conditions in FIG. 4 (a) are as follows.

(A) Ambient temperature is 35 ° C
(A) The simulation temperature was the temperature on the heat radiating portion 14, the temperature on the sealing material 16, and the temperature on the MCU 22.

  (C) The distance between the heat radiation part and the guide part is constant at 10 mm.

  (D) Simulation was performed by changing the length of the overlapping length of the heat radiation part and the guide part.

  (E) The cooling fan to be used is generally called a high air flow type.

  In FIG. 4 (a), the vertical axis represents the temperature of the heat radiating part, the MCU and the sealing material, and the horizontal axis represents the length of the overlapping length of the heat radiating part and the guide part. The height of the heat radiating part is 50 mm.

  In the above (e), the high air volume type fan is used for industrial products, and is a type used in an environment where the loudness of the cooling fan does not matter even if the noise is loud. It is.

  In FIG. 4B, in the same simulation as FIG. 4A, the cooling fan used under the condition (e) is generally called a calming type.

  Quiet type is used in products used in offices and homes, etc. If the noise of the cooling fan is loud, it causes problems such as unpleasantness in human hearing, so calming is necessary. This is the type used when

  4 (a) and 4 (b), it can be seen that the temperature on the sealing material is lowered only by providing the guide portion, and the length of the overlap between the heat radiating portion and the guide portion is the length of the heat radiating portion. This indicates that the temperature on the encapsulant decreases until the length is substantially the same. However, when the length of the guide part becomes longer than the length of the heat radiating part, the temperatures of the sealing material, the heat radiating part, and the MCU all rise. From this, it can be seen that making the length of the guide portion longer than the length of the heat dissipation portion has no effect on temperature rise.

  Therefore, from these results, in order to reduce the temperature rise on the sealing material, the length of the overlapping portion of the guide portion should first be approximately the same length as the length of the heat radiating portion. I understand. Therefore, the length K of the length of the guide portion with respect to the height of the heat radiating portion is expressed by the following formula 1.

K ≤ H (Formula 1)
H: Height of the fin of the heat dissipating part (length to the position where the fin 21 is attached to the base 20: see FIG. 3)
In addition, description of "open | release" of Fig.4 (a) (b) means not providing a guide part.

  By the way, as mentioned above, it is said that a semiconductor element is generally destroyed when it exceeds about 150 ° C. Therefore, in order to prevent the temperature of the semiconductor mounted on the heat dissipation part from exceeding 150 ° C., the temperature and conditions of the environment in which it is used should be considered. It can be said that it is preferable not to exceed.

  From this, it can be seen from FIG. 4B that the length of the guide portion needs to be 30 mm or less so that the temperature of the heat radiating portion does not exceed 100 ° C. Generally speaking, this is expressed by the following formula 2.

K ≤ (3/5) * H (Formula 2)
In the conventional apparatus, the MCU on the substrate arranged on the downstream side of the wind flow is also radiated from the sealing material by the wind flowing in the direction opposite to the wind flowing by natural convection. As the temperature rises, the temperature of the MCU decreases until the length of the heat dissipating part and the guide part are substantially the same as the length of the cooling fin, as in the case of the sealing material. It is shown that.

  Next, another simulation result is shown in FIGS. In the simulations of FIGS. 5 and 6, the simulation conditions are changed from FIG. 4 as follows. Other than that is the same as FIG.

  (C) A simulation was performed by changing the distance between the heat radiation part and the guide part.

  (D) The length of the overlapping length of the heat radiating part and the guide part is made constant at 15 mm.

  (E) The cooling fan to be used is generally called a calming type.

  5 and 6, the vertical axis represents the temperature of the heat radiating portion, the MCU and the sealing material, and the horizontal axis represents the gap distance between the heat radiating portion and the guide portion.

  From FIG. 5, it can be seen that the temperature on the sealing material and the MCU is lowered only by providing a gap between the heat radiating part and the guide part. It can be seen that the reduction effect is not significantly changed.

  Furthermore, it can be seen that even if the size of the gap between the heat radiating portion and the guide portion changes, there is little change in the heat radiating portion, and even if the guide portion is provided, the heat radiating effect of the heat radiating portion does not decrease.

  In order to maintain the original heat dissipation function of the heat dissipation part by the fan and to obtain the heat dissipation effect of the substrate with much heat generation or the substrate with relatively little heat generation, the guide is to avoid the enlargement of the device. Limit the area of overlapping parts. Moreover, it can be said that it is preferable that the gap is not limited to an unlimited size but is about 10 mm.

  On the other hand, referring to FIG. 6, it can be seen that the gap between the heat radiation portion and the guide portion has a heat radiation effect from a value of about 2 mm. Therefore, it can be said that the gap between the heat radiating portion and the guide portion needs to be at least about 2 mm or more.

  Further, FIG. 7 shows an actual measurement comparison between a conventional apparatus and an apparatus based on this embodiment. In this example, the length of the guide portion was 10 mm, and the distance from the guide portion was 10 mm. From this result, it was confirmed that the temperature rise of the sealing material was reduced by -9.5 ° C. and the temperature of the MCU was reduced by −14.9 ° C. while suppressing the temperature rise of the heat radiating portion. Since the MCU is equipped with a semiconductor element having a relatively low operation guaranteed temperature such as a CPU, the reduction in the temperature rise can contribute to stable control of the apparatus.

The reason why the temperature rise of the MCU is greatly reduced in this way is considered to be due to the provision of the guide portion, which has the following effects.
(A) The temperature rise of the sealing material was reduced by forced air cooling of the sealing material as a heat source.
(A) Gas heated by the sealing material is no longer suitable for the MCU.
(C) Forced air cooling of the MCU was also performed, and the temperature rise of the MCU was reduced.

  The above-described embodiment is achieved only by providing a guide portion for these effects.

  FIG. 8 shows another embodiment.

  FIG. 8 shows an embodiment similar to FIG. 2, except that an inclined portion 23 is provided in the guide portion 19 so that gas from a semiconductor such as a sealing material or MCU can easily flow to the intake surface. Therefore, the inclined portion 23 may be a curved surface based on the fluid flow or the like so as to make it easier to flow.

  As in the above embodiment, by providing an appropriate amount of overlap and distance between the heat radiating part and the guide part, the size of the housing is optimized, and it is possible to install other equipment for promoting cooling, Temperature rise inside the housing can be prevented.

  Therefore, it is suitable for an apparatus in which no other cooling fan can be disposed, such as a particularly small apparatus, and a useful effect of reducing the temperature rise can be obtained.

  In addition, in the said Example, it demonstrated based on the Example of a power converter device. However, it is not limited to these. For example, it is useful when mounting a device having a semiconductor element, a module, a substrate, or the like that generates a large amount of heat compared to a semiconductor element, module, or substrate that generates a large amount of heat.

  In this case, according to the embodiment of the present invention, the semiconductor element, the module, the substrate, etc. that generate a small amount of heat are mounted on the first substrate, while the semiconductor element, the module, the substrate, etc. that generate a large amount of heat are mounted on the second substrate. To be implemented. The second substrate is fixed at a position separated from the first substrate by a predetermined length. In this way, heat conduction from a semiconductor element or the like that generates a large amount of heat can be cut off.

  Next, the second substrate is fixed to a heat radiating portion having fins, and heat generated from the second substrate is radiated by forced air cooling using a fan in the heat radiating portion.

  Furthermore, a guide part is provided in the housing so as to create a gas flow for directing the gas around the first substrate and the second substrate toward the intake surface of the heat radiating unit. By this guide portion, when the fan operates, the first substrate and the second substrate can be forcedly cooled by air. As a result, the temperature rise in the first substrate, the second substrate, and the housing can be reduced without providing a new fan. Note that the second substrate is arranged to be leeward when forced air cooling is performed as compared with the substrate of the first substrate.

  By mounting a semiconductor having a relatively low guaranteed operating temperature of a semiconductor or a control element such as a CPU on the first substrate, it is possible to obtain a temperature rise reduction effect.

DESCRIPTION OF SYMBOLS 1 ... Diode three-phase bridge circuit, 2 ... Current smoothing capacitor, 3 ... Inverter circuit (IGBT), 4 ... Heat radiation part, 5 ... Cooling fan, 7 ... Sealing material (resin material), 8 ... Power semiconductor element, 9 DESCRIPTION OF SYMBOLS ... Metal substrate, 10 ... Apparatus case (casing), 11 ... Board | substrate incorporated in apparatus, 19 ... Guide part. 20 ... Base, 21 ... Fin, 22 ... MCU

Claims (2)

Base and
A housing covering the base;
A power semiconductor element disposed on the base and between the base and the housing;
A circuit board disposed between the base and the housing;
An MCU or CPU on the circuit board and disposed between the housing and the circuit board;
A fin having a height of 50 mm disposed on the back side of the surface on which the power semiconductor is disposed;
Connected to the housing,
Air sucked from one end side of a space formed by the base and the housing, from the one end side of the space formed between the air that has cooled the power semiconductor element and the circuit board and the housing. A guide portion that guides air sucked and cooled by the MCU or CPU to the intake surface of the fin;
A fan disposed on the back surface of the surface on which the power semiconductor of the base is disposed, on the exhaust surface side of the fin facing the intake surface;
A power conversion device comprising:   The power converter according to claim 1, wherein a size of a gap between the guide portion and the intake surface of the fin is 2 mm or more.

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