JPH1023768A - Heat sink assembly for cooling power inverter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the temperature rise at the junctions of a plurality of power semiconductor module elements so as to reduce the size of a heat sink, by arranging those of the semiconductor elements which cause high temperature between joint surfaces and module cases at low-temperature positions on the mount surface of the heat sink. SOLUTION: On the mount surface of a heat sink 7, IGBT modules 5a, 5b, and 5c which cause high temperature between element junction surfaces and module cases are arranged upstream the cooling air, and a diode module 2a is arranged downstream the cooling air. As a result, the joint surface temperatures of the power semiconductor module elements which highly raise the joint surface temperatures can be set low. Therefore, the size of the heat sink 7 can be reduced by reducing the thermal resistance of the heat sink 7, because the temperature rise of the heat sink 7 is tolerable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter such as an inverter for driving a motor or an uninterruptible power supply.
More particularly, the present invention relates to a cooling heat sink assembly of a power conversion device in which a module type power semiconductor element connecting and configuring a power conversion circuit is mounted on a cooling heat sink.

[0002]

2. Description of the Related Art A module for connecting a power conversion circuit such as a motor drive inverter (hereinafter simply referred to as an inverter) or an uninterruptible power supply (hereinafter referred to as a UPS) to a power conversion circuit. 2. Description of the Related Art There is known a device in which a power semiconductor device is mounted on the same heat sink for cooling (hereinafter simply referred to as a heat sink). This will be described with reference to FIGS.

FIG. 7 shows an example of a connection configuration of a power converter.
1 is a three-phase AC power supply, 2 is a converter circuit composed of diodes 21, 22,..., 3 is a DC reactor, 4 is a smoothing capacitor, 5 is a power semiconductor element 511, 512, and its power semiconductor. Diodes connected in anti-parallel to devices
.., And 6 is a load circuit. Here, the converter circuit 2 has six diodes.
Diode module 2a composed of diodes 21, 22, ...
Is a diode converter having the form shown in FIG. Also, the inverter circuit 5 is provided with insulating gates for the power semiconductor elements 511 and 512.
A bipolar transistor (IGBT) is used. Diodes 521 and 522 have built-in anti-parallel diodes (hereinafter FWD).
IGBT module 5a having the connection configuration shown in the figure and a similar IGBT module.
Module 5b and an IGBT module 5c.

[0004] This type of power converter is commonly used, and detailed description of its operation is omitted. However, after converting the AC power from the three-phase AC power supply 1 into DC power by the converter circuit 2, the D power is converted to a DC power.
The power is smoothed by the C reactor 3 and the smoothing capacitor 4, converted into AC power again by the inverter circuit 5, and supplied to the load circuit 6. This is because, in the case of a motor driving inverter, the IGBT of the inverter circuit 5 is switched so that the inverter output has a variable voltage and variable frequency, thereby changing the speed of the motor as the load circuit 6. Control is performed.

FIG. 8 shows an example of the arrangement of a heat sink assembly in the case of constituting the circuit of FIG. 7, where 7 is a heat sink. Here, for convenience of description, the DC reactor 3, the smoothing capacitor 4, wiring materials for electric wiring, and the like are omitted. That is, the converter circuit 2 is in the form of a diode module 2a, and the inverter circuit 5
IGBT modules 5a, 5b and 5c each having two built-in anti-parallel circuits of IGBT and FWD, which constitute an assembly mounted on a heat sink 7.

The heat sink assembly is used when the converter circuit 2 converts AC power into DC power and when the inverter circuit 5 converts DC power into AC power.
In the diodes, IGBTs, and FWDs of each component, the loss caused by the conduction voltage caused by the current flowing, the so-called conduction loss, and the loss caused by the existence of the switch time during the switching operation for switching the current on and off Heat is generated due to so-called switching loss, and the temperature of the element rises. This element temperature (the problem is actually the temperature of the silicon PN junction: hereinafter referred to as the junction temperature)
If the temperature exceeds the maximum operating temperature, the device may be degraded or destroyed. Therefore, as shown in FIG.
The BT modules 5a, 5b, 5c are arranged on the heat sink 7 to radiate the heat generated by the above-mentioned loss to lower the junction temperature.

Next, a description will be given of a rise in the junction temperature of each element of the power conversion circuit. Here, the calculation of the temperature rise due to the conduction of heat is easy to understand when it is schematically illustrated in an electric circuit, and the calculation becomes clear. Therefore, the thermal circuit diagram shown in FIG. 9 will be referred to. The thermal resistance is a value obtained by dividing a temperature difference generated when heat passes from one point to another point by the amount of heat passed, and has a unit of (° C / W). RTJC, RD in Fig. 9
JC, RCFT, RRJC, RCFR are as follows. RTJC: Thermal resistance between IGBT junction, IGBT module and case RDJC: Thermal resistance between FWD junction of IGBT, IGBT module and case RCFT: Contact thermal resistance between IGBT module, case and heat sink RRJC: Thermal resistance between diode junction of diode module and diode module case RCFR: Contact thermal resistance between diode module case and heat sink RF: Thermal resistance of heat sink

In FIG. 9, reference numerals PT, PD and PR indicating the heat generation of each element are as follows. PT: Heat due to loss of IGBT PD: Heat due to loss of FWD PR: Heat due to loss of diode in the diode module Further, symbols TT, TD, TR, TT, TD, TR, etc. indicating junctions of each element
TF, TCT, TCR, TA are as follows. TT: Junction temperature of IGBT TD: Junction temperature of FWD TR: Junction temperature of diode in diode module TF: Mounting surface temperature of heat sink TCT: IGBT module case temperature TCR: Diode -Module case temperature TA: Ambient temperature Here, for the diode module, the heat generation and the average thermal resistance for six elements are shown for simplicity.

As can be seen from FIG. 9, the temperature rise of each part, that is, the temperature rise between the junction of TJCT: IGBT module case and IGBT TJCD: the junction of IGBT module case-FWD TJCR: Temperature rise between junctions of diodes in diode module case-diode module TCFT: Temperature rise of heat sink mounting surface-IGBT module case TCFR: The temperature rise of the heat sink mounting surface-diode module case TFA: the heat sink mounting surface-temperature rise of the ambient temperature is expressed by the following equations (1) to (6).

TJCT = TT− TCT = PT × RTJC (1) TJCD = TD− TCT = PD × RDJC (2) TJCR = TR− TCR = PR × RRJC ... (3) TCFT = TCT-TF = 2 (PT + PD) x RCFT ... (4) TCFR = TCR-TF = PR x RCFR ... (5) TFA = TF-TA = {3 × 2 (PT + PD)} + PR (6)

FIG. 10 shows an element junction temperature distribution when an ideal heat sink assembly is used. Here, IG
The BT module assumes that the junction surface temperature rise on the IGBT side is high, and the FWD is not shown. In FIG. 10, the point at which the temperature of TFA increased with respect to the ambient temperature TA is TF, the point at which the temperature of (TJCR + TCFR) increased with respect to TF was TR, and the temperature of (TJCT + TCFT) also increased with TF. The point is TT. TT, that is, the junction temperature TJMAX0 of the IGBT is the highest. Here, the maximum operating temperature of the power semiconductor element junction is generally set to about 125 to 150 ° C.

[0012]

By the way, for example, FIG.
The thermal resistance such as RTJC and RCFT of each element is determined by the element (module) used, and the temperature rise between the junction of each element and the heat sink mounting surface from the relationship between heat generation and thermal resistance in the operating condition Is determined. Therefore, the temperature rise from the heat sink to the surroundings is reduced, that is, the heat sink is reduced.
By reducing the thermal resistance of the tosink, it is necessary not to exceed the maximum temperature of the element junction. In an actual design, the setting is made so that the junction is kept at a temperature slightly above the maximum operating temperature. However, since the heat sink dissipates heat by utilizing the heat conduction action and the radiation action, it is inevitable that a temperature difference occurs in various parts of the heat sink.

FIG. 11 is a schematic diagram showing a temperature distribution when the entire surface of the heat sink heating element is heated. In FIG. 11, in the case of a self-cooling heat sink, the cooling convection is determined by the installation direction of the heat sink 7, but here, the direction of the cooling air is illustrated for clarity. That is, the temperature of the mounting surface of the heat sink 7 gradually increases toward the leeward direction, and the end of the heat sink 7 has the highest temperature. Actually, since the heating element is separated and arranged on the heat sink mounting surface, the temperature immediately below the heating element increases, and the temperature of the heat sink mounting surface has a temperature distribution that produces a mountain immediately below the heating element. In this case, the temperature tends to be higher toward. In addition, in some cases, the heat distribution temperature may be assumed to be simplified for this temperature distribution.
The following explanation is based on the agreement with the TFA.

Now, in the power converter constructed as shown in FIG. 7, the IGBT 511 and the like of the inverter circuit 5 are operated with a high-frequency switch to improve the performance. This is intended to improve controllability and reduce noise by high frequency operation. As a result, the IGBT increases the switch loss in addition to the conduction loss, resulting in increased heat generation. As a result, the temperature of the junction increases. On the other hand, the converter circuit 2 is composed of a diode 21 and the like. Since the loss is determined only by the conduction loss, the diode converter generates little heat and the temperature rise at the junction is often low.

However, a heat sink assembly of this type of power converter is as shown in FIGS.
FIG. 12 and FIG. 13 show the structure of a conventional heat sink assembly and the temperature distribution of the heat sink assembly. That is, as shown in FIG. 12, the mounting surface of the heat sink 7 is
The module 2a and the IGBT modules 5a, 5b, 5c are arranged, and the cooling air flows in the direction shown in the figure. Is what happens.

In the temperature gradient of the heat sink mounting surface shown in FIG. 13, TF1 is the heat sink temperature of the diode module 2a mounting surface, and TF2 is the IGBT modules 5a, 5b, 5b.
5c is the heat sink temperature of the mounting surface. For each of these temperatures, the junction surface temperature of the element—the temperature rise between the module cases (TT-TCT, TR-TCR in FIG. 9) and the temperature rise on the module case-heat sink mounting surface (FIG. 9). , TCT-TF, TCR-TF) are added to the junction temperature rise TT1, TR1 of each element. Thus, if the junction surface temperature TT1 of the IGBT becomes the highest temperature and this is taken as TJMAX1, the temperature rise is higher than the junction temperature TJMAX0 of the IGBT shown in the figure, and the temperature with TR1 It can be seen that the difference dT2 is also increased by the presence of the heat sink temperature gradient.

Thus, in the case of the configuration as shown in FIG. 12, the temperature rise of the junction of the module type power semiconductor element arranged at a position where the temperature of the heat sink 7 is high becomes high, and therefore the temperature rises. There is a problem that reduces the margin. This means that when designing in consideration of these conditions, it is necessary to increase the heat sink capability and to lower the junction temperature, which leads to an increase in the size of the heat sink and an increase in the size of the device. Will be. In addition, one element has a severe thermal condition, and the other element has an uneconomical design in which a relatively marginal state is provided.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a special device which can reduce a rise in junction temperature of a module type power semiconductor device and can downsize a heat sink.

[0019]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has the following structure. In other words, of a plurality of module-type power semiconductor elements mounted on the same heat sink and having different operation states, the module-type power semiconductor element having an element having a large temperature rise between a junction surface and a case. Are arranged at a position where the temperature of the heat sink mounting surface is low.

According to this solution, in the power conversion circuit, the junction temperature of the module-type power semiconductor element having a high junction temperature rise can be set low. Furthermore, the fact that the junction surface temperature can be set low in this way allows the heat sink to rise in temperature, thereby reducing the thermal resistance of the heat sink and making it possible to design the heat sink in a small size.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, FIG. 1, FIG. 2 and FIG.
It will be described with reference to FIG. FIG. 1 shows an embodiment of the present invention in a manner similar to FIG. 12, and FIGS. 2 and 3 show one example and another example of an element junction temperature distribution for explaining FIG. That is, FIG. 1 shows an application example of the power conversion circuit shown in FIG. 7, in which the IGBT modules 5a, 5b and 5c are placed on the windward side of the cooling air on the mounting surface of the heat sink 7, and the
The module 2a is arranged on the leeward side.

Further, in FIG. 2, the heat sink mounting surface temperature of each module does not change between TF1 and TF2 as in FIG. 13, but the IGBT module having a high temperature rise between the element junction surface and the module case. TF1 with low temperature
Diode module 2 with low temperature rise
By setting a at the high temperature TF2 point, the maximum junction temperature TJMAX2 becomes the TR2 point of the element in the diode module, but compared to the maximum junction temperature TJMAX1 according to FIG. 13 shown in FIG. Only the temperature rise can be suppressed. Also, the difference from the IGBT module junction surface temperature is only dT3, and is obviously reduced.

FIG. 13 shows the maximum junction temperature TJ.
If MAX1 is within the allowable range for the junction temperature,
As described above, the maximum junction surface temperature TJMAX2 may be positively increased and used. That is, in FIG.
In the case where TJMAX2 is raised to a level equal to TJMAX1, a temperature rise corresponding to the difference dT4 of the maximum junction surface temperature in FIG. 2 is added, and the temperature rise of the heat sink 7 mounting surface is raised to TFA3 and TFA4. It is all possible. That is, for the heat sink, the fact that the temperature rise can be increased despite the same amount of processing heat means that the heat resistance of the heat sink increases. Here, increasing the thermal resistance means reducing the surface area, and as a result, it is possible to reduce the outer shape of the heat sink.

Next, a description will be given with reference to FIGS.
FIG. 4 shows another example of the connection configuration of the power converter according to the present invention in a manner similar to FIG. 7, in which 8 is an AC reactor, 9 is a converter circuit, and 10 is a smoothing capacitor.
In the converter circuit 9, 911, 912,.
21, 922 ... are FWD, and 9a, 9b, 9c are IG
BT module. That is, this is a power converter in which the converter circuit 9 is a sine-wave current input converter circuit using high frequency PWM control or the like. Examination of Performance AC Vehicle System ", IEE of Japan, Volume D, Vol. 07, No. 3,
Details were reported in 1987, and the detailed description is omitted here.

FIG. 5 shows another embodiment of the present invention applied to FIG. 4. In FIG. 5, capacitors, reactors, wiring materials for electric wiring and the like are omitted as in FIG. It is. That is, as can be seen from FIG. 4, the connection states of the IGBT module 5a and the IGBT module 9a are exactly the same in both the inverter circuit 5 and the converter circuit 9. Are different in the junction surface temperature rise of the internal elements. This depends on the AC input voltage and the inverter.
The difference in the processing current due to the difference in the output voltage of the inverter and the difference in the operation state in which a large amount of current flows in the FWD of the IGBT module in the converter circuit 9 and a large amount of current flows in the IGBT side in the inverter circuit 9 And the difference in thermal resistance between the junction of the IGBT and the FWD and the case.

FIG. 5 shows the IGBT module 9
The converter circuit 9 composed of a, 9b and 9c is
Inverter composed of IGBT modules 5a, 5b, 5c
This is an example of a case where an element having a larger junction surface temperature rise than the circuit 5 is provided. Therefore, it is clear that a circuit constituted by an IGBT module having a large rise in the junction temperature is disposed in a place where the heat sink 7 mounting surface temperature is low.

Next, when increasing the capacity of the power converter shown in FIG. 4, an IGBT and an FWD are connected in parallel to increase the current. An example of increasing the current by connecting the IGBT modules in parallel will be described. FIG. 6 shows another example of the connection configuration for one phase of the three-element parallel connection of the power converter according to the present invention.
Is a smoothing capacitor, and 13 is an inverter circuit. Here, 11a1, 11a2, 11a3, 13a1, 13a2, 13a3
Is an IGBT module.

That is, the converter circuit 11 and the inverter circuit 13 composed of each IGBT module having the connection configuration as shown in the figure are applied as one unit, and three circuits are used. It is clear that the three-phase structure is constituted by When the connection example of FIG. 6 is mounted on the same heat sink, the configuration is exactly the same as that shown in FIG. 5, and therefore, as in FIG. It is apparent that the same effect as that shown in FIGS. 2 and 3 can be obtained by arranging the module of the circuit having a higher temperature at a position where the temperature of the heat sink mounting surface is lower. The power converters constituting the converter circuit and the inverter circuit have been described. However, the present invention is not limited to this circuit configuration. Needless to say, the application of the present invention is effective when there is a thermal margin difference between the pumps.

[0029]

As described above in detail, according to the present invention, the heat sink of the power semiconductor element can be designed economically and compactly, and the power converter can be reduced in size and weight and can be realized at low cost. A device having a simple configuration can be provided.

[Brief description of the drawings]

FIG. 1 is a structural diagram showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of an element junction temperature distribution for explaining FIG. 1;

FIG. 3 is an explanatory diagram showing another example of an element junction temperature distribution for explaining FIG. 1;

FIG. 4 is a circuit diagram showing another connection configuration example of the power conversion device according to the present invention.

FIG. 5 is a structural view showing another embodiment of the present invention.

FIG. 6 is a circuit diagram showing another example of a connection configuration for one phase of a three-element parallel connection of the power converter according to the present invention.

FIG. 7 is a circuit diagram illustrating a connection configuration example of a power converter.

FIG. 8 is a structural diagram showing an example of disposing a heat sink assembly when configuring the circuit of FIG. 7;

FIG. 9 is a thermal circuit diagram shown for the explanation of FIG. 8;

FIG. 10 is an explanatory diagram showing an element junction temperature distribution when an ideal heat sink assembly for explaining FIG. 8 is used.

FIG. 11 is a schematic diagram illustrating a temperature distribution when the entire surface of the heat sink heating element is heated.

FIG. 12 is a structural diagram showing a conventional example used in the power converter of FIG. 7.

FIG. 13 is an explanatory diagram showing a temperature distribution of the heat sink assembly for explaining FIG. 12;

[Explanation of symbols]

1. Three-phase AC power supply 2. Converter consisting of diode module 2a
21 Diode 3 DC reactor 4 Smoothing capacitor 5 Inverter circuit composed of IGBT module 5a, etc. 511 Power semiconductor element (IGBT) 521 Diode (FWD) 6 Load circuit 7 Cooling heat sink ( Heat sink) 8 AC reactor 9 Converter composed of IGBT module 9a etc.
911 Power semiconductor device (IGBT) 921 Diode (FWD) 10 Smoothing capacitor 11 Converter circuit 12 Smoothing capacitor 13 Inverter circuit

Claims (1)

[Claims] 1. A power converter comprising a plurality of modular power semiconductor elements connected to a power conversion circuit and mounting the plurality of modular power semiconductor elements on the same heat sink for cooling. A module-type power semiconductor element having a large junction-case temperature rise among the plurality of module-type power semiconductor elements is placed at a position where the cooling heat sink mounting surface temperature is low. A heat sink assembly for cooling a power converter, wherein the heat sink assembly is provided.