CN112437593B

CN112437593B - High-power-density integrated PCU module and liquid cooling design method thereof

Info

Publication number: CN112437593B
Application number: CN202011332437.7A
Authority: CN
Inventors: 杨树; 张茂盛; 盛况
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang Semiharv Technology Co ltd
Priority date: 2020-11-24
Filing date: 2020-11-24
Publication date: 2022-03-25
Anticipated expiration: 2040-11-24
Also published as: CN112437593A

Abstract

A high power density integrated PCU module and a liquid cooling design method thereof are disclosed, which comprises a liquid cooling radiator structure design and a liquid cooling parameter optimization method. The liquid cooling design method solves the problem of overheating of a local power chip in the PCU module due to high integration of the PCU power module, and achieves optimized heat dissipation of the high-power-density integrated PCU module.

Description

High-power-density integrated PCU module and liquid cooling design method thereof

Technical Field

The present invention relates to electronic circuits, and more particularly, to a high power density integrated PCU module and a liquid cooling design method thereof.

Background

High integration has become a mainstream trend in development of Power Control Unit (PCU) modules of Electric Vehicles (EV) or Hybrid Electric Vehicles (HEV). The trend of high integration of PCU modules is mainly reflected in two aspects, namely that more circuit conversion function modules are integrated into the same module, and that more components are integrated into the same module.

For the PCU module of the plug-in hybrid electric vehicle, there are typical examples in the industry that more circuit conversion function modules are integrated into the same module, such as the PCU module used by the first Prius of the toyota vehicle, and the circuit conversion function module of the motor drive and the generator are integrated into the module, but when the second Prius is developed, the circuit conversion function module of boost is also integrated into the PCU module.

The integration of more components inside the module means that other components such as a liquid-cooled heat sink, a capacitor, an inductor or a current sensor, etc. inside the same module except for the increase of the types and the number of chips are integrated together and then are integrally packaged and formed.

The PCU module is connected with other parts in the HEV electric control system through power electrodes, input and output terminals, a water outlet and a water inlet of the liquid cooling radiator of the module. The location of these interfaces is fixed for a given HEV electrical control system, and the relative positioning of the interfaces imposes severe constraints on the integration of the components of the PCU module. The inconsistency of current levels among the PCU module circuit conversion function modules also causes inconsistency of sizes and parallel numbers of power chips used by basic power conversion units inside the PCU module circuit conversion function modules. In addition, the layout of the power chips on the DBC structures of the upper bridge and the lower bridge is not completely consistent when the bridge arms are interconnected through the DBC routing in the same basic power unit. These are the root cause of the differences in the thermal resistance of the power chip inside the high power density integrated PCU module between different circuit conversion function modules and between the upper and lower bridges inside the same basic function conversion unit.

The existing liquid cooling parameter optimization is only based on the optimization design rule of the highest temperature and the highest pressure of the cooling liquid limited by the junction temperature of the power chip, and the existing cooling liquid flow rate optimization does not consider the unique thermal resistance characteristic among the power chips of the high-power-density integrated PCU module, so that the designed cooling liquid flow rate deviates from the optimal value. Too high a flow rate will add extra cost to the heat dissipation, and too low a flow rate will risk overheating of the local power chip. In addition, because the difference of the thermal resistance of the PCU module is not considered, the design of the cooling liquid flowing space inside the liquid cooling radiator cavity is not optimized and adjusted correspondingly in different areas, which also results in an increased risk of local chip overheating of the module. Therefore, the existing liquid cooling design cannot effectively cope with the current situation that the thermal resistance characteristics of the PCU module are inconsistent due to high power density integration, so that the designed liquid cooling parameters are either too severe or too relaxed.

Disclosure of Invention

To solve one or more of the above-mentioned technical problems of the prior art, the present invention proposes a new method for heat dissipation of a high power density integrated PCU module. The method integrates the unique thermal characteristic of thermal resistance difference of a power chip in the PCU module into the design of the PCU module, and provides a liquid cooling design method of the PCU module with high power density based on the thermal resistance difference characteristic.

According to an embodiment of the present invention, there is provided a high power density integrated PCU module including: the liquid cooling radiator comprises cooling liquid, a cooling liquid inlet, a cooling liquid outlet, a liquid cooling radiator cavity and a liquid cooling heat sink plate, wherein the cooling liquid flows in a cooling liquid flowing space formed by the liquid cooling radiator cavity and the liquid cooling heat sink plate, enters the liquid cooling radiator from the cooling liquid inlet and flows out of the liquid cooling radiator from the cooling liquid outlet; the first solder layer is positioned above the liquid cooling heat sink plate; a plurality of circuit conversion function modules located above the first solder layer, each circuit conversion function module including a plurality of basic power conversion units, including: a DBC structure comprising an upper bridge DBC structure and a lower bridge DBC structure; the second solder layer is positioned on the upper surface of the DBC; the power chip is positioned on the upper surface of the second welding flux layer, wherein the heat generated by the power chip is transmitted to the cooling liquid through the second welding flux layer, the DBC structure, the first welding flux layer and the liquid cooling heat sink plate, and is transmitted out of the liquid cooling radiator through the cooling liquid; the difference value obtained by subtracting the temperature accumulation of the power chip with the highest temperature in the lower bridge and only related to the flowing of the cooling liquid from the temperature accumulation of the power chip with the highest temperature in the upper bridge and only related to the flowing of the cooling liquid in the same circuit conversion functional module is approximately equal to zero; and the difference between the temperature accumulation of the first power chip only associated with the flow of the cooling fluid minus the temperature accumulation of the second power chip only associated with the flow of the cooling fluid is approximately equal to zero.

According to still another embodiment of the present invention, there is provided a high power density integrated PCU module including: liquid cooling radiator, including coolant liquid, coolant liquid entry, coolant liquid export, liquid cooling radiator cavity and liquid cooling heat sink, the coolant liquid flows in the coolant liquid flow space that is formed by liquid cooling radiator cavity and the heavy board of liquid cold heat, gets into liquid cooling radiator by the coolant liquid entry to flow out liquid cooling radiator by the coolant liquid export, liquid cooling radiator still includes that liquid cold heat sinks the long banding protruding structure and the column protruding structure of board deep into coolant liquid flow space, and wherein the interval that long banding protruding structure is each other is not less than the interval that column protruding structure is each other, and long banding protruding structure is perpendicular with the coolant liquid flow direction and just to the area of the face of column protruding structure in the area that long banding protruding structure and column protruding structure are adjacent is less than the area of the cross section of other optional positions parallel with this face in the long banding protruding structure, and the interval that long banding protruding structure parallel direction is not more than and long banding protruding structure each other between the column protruding structure each other The distance between the structures in the vertical direction; the first solder layer is positioned on the upper surface of the liquid cooling heat sink plate; a plurality of circuit conversion function modules located above the first solder layer, each circuit conversion function module including a plurality of basic power conversion units, including: a DBC structure comprising an upper bridge DBC structure and a lower bridge DBC structure; the second solder layer is positioned on the upper surface of the DBC structure; and the power chip is positioned on the upper surface of the second solder layer, wherein the heat generated by the power chip is transmitted to the cooling liquid through the second solder layer, the DBC structure, the first solder layer and the liquid cooling heat sink plate, and the heat is transmitted out of the liquid cooling radiator through the cooling liquid.

The liquid cooling design method of the high-power-density integrated PCU module improves the liquid cooling heat dissipation efficiency or effectiveness of the PCU module on the premise of not increasing the liquid cooling heat dissipation cost, reduces the risk of overheating of a power chip in the PCU module, and shortens the product development period of the PCU module.

Drawings

Fig. 1 is a schematic diagram 1000 of a high power density integrated circuit module in a PCU according to an embodiment of the present invention;

fig. 2 is a schematic diagram 2000 of a high power density integrated structure of a basic power conversion unit in a PCU module according to an embodiment of the present invention;

fig. 3 is a schematic circuit topology diagram 3000 of a basic power conversion unit of a PCU module according to an embodiment of the present invention;

fig. 4 is a schematic structural diagram 4000 of a basic power conversion unit of a PCU module according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram 5000 of a high power density integrated PCU module according to an embodiment of the present invention;

FIG. 6 is a cross-sectional view 6000 of a high power density integrated PCU module at A1-A1 in accordance with an embodiment of the present invention;

fig. 7 is an enlarged partial schematic view 7000 of the area of the high power density integrated PCU module according to an embodiment of the present invention, as identified by the circular dashed box 6001 in the cross-sectional configuration at a1-a 1;

FIG. 8 is a cross-sectional view 8000 of a high power density integrated PCU module at A2-A2, in accordance with an embodiment of the present invention;

fig. 9 is a schematic structural design diagram 200 of a liquid-cooled heat sink 200 of the liquid-cooled heat dissipation structure of the high power density integrated PCU module according to an embodiment of the present invention;

fig. 10 is an enlarged schematic view 2001 of a partial area 2001 of the liquid-cooled heat sink 200 according to an embodiment of the present invention;

fig. 11 is an enlarged plan view 2002 of a part 2002 of a liquid-cooled heat sink part 2001 according to an embodiment of the present invention;

fig. 12 is a schematic reference diagram 9000 of liquid cooling parameter design for a high power density integrated PCU module according to an embodiment of the present invention;

fig. 13 is a schematic diagram 9100 of a liquid cooling parameter calculation method of a high power density integrated PCU module according to an embodiment of the present invention.

Detailed Description

Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings, and it should be noted that the embodiments described herein are only for illustration and are not intended to limit the present invention. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be understood by those of ordinary skill in the art that these specific details are not required in order to practice the present invention. In other instances, well-known circuits, materials, or methods have not been described in detail in order to avoid obscuring the present invention.

Throughout the specification, reference to "one embodiment," "an embodiment," "one example," or "an example" means: the particular features, structures, or characteristics described in connection with the embodiment or example are included in at least one embodiment of the invention. Thus, the appearances of the phrases "in one embodiment," "in an embodiment," "one example" or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combination and/or sub-combination in one or more embodiments or examples. Further, those of ordinary skill in the art will appreciate that the figures provided herein are for illustrative purposes, and wherein like reference numerals refer to like elements throughout. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The liquid cooling design method of the high power density integrated PCU module comprises but is not limited to the PCU module, and other high power modules are also applicable even if the liquid cooling radiator is not integrated.

Fig. 1 is a schematic diagram 1000 of a high power density integrated circuit module of a PCU according to an embodiment of the present invention. In the embodiment shown in fig. 1, the integrated PCU module with high power density includes a liquid-cooled heat sink cavity 100, a liquid-cooled heat sink plate 200 with a heat dissipating structure, a liquid-cooled heat sink cavity coolant inlet 101, a liquid-cooled heat sink cavity coolant outlet 102, and different circuit transforming function modules m (i) integrated on the liquid-cooled heat sink plate 200. Wherein the liquid-cooled radiator tank 100, the liquid-cooled hot sink plate 200 with the heat dissipating structure, the liquid-cooled radiator tank coolant inlet 101, and the liquid-cooled radiator tank coolant outlet 102 form a liquid-cooled radiator of the PCU module.

In this embodiment, the number of the circuit transformation function modules M (i) can be any number greater than 1 (i.e., i ≧ 1). To easily address the problem of thermal resistance inconsistency caused by high power density integration, an embodiment of the invention uses 3 sets of circuit transformation function modules, i.e., the circuit transformation function module M1, the circuit transformation function module M2, and the circuit transformation function module M3.

Fig. 2 is a schematic diagram 2000 of a high power density integrated structure of a basic power conversion unit of a PCU module according to an embodiment of the present invention. In the embodiment shown in fig. 2, the circuit transformation function modules are three groups, M1, M2 and M3, and each of the circuit transformation function modules has its own basic power transformation unit (e.g. basic power transformation unit 1, basic power transformation unit 2, basic power transformation unit 3) laid out in parallel on the PCU module liquid cooling and heating sinking plate 200.

In fig. 2, power electrode 13 and power electrode 14 are input power electrodes of basic power conversion cell 1, and power electrode 10 is an output power electrode of the basic power conversion cell. Similarly, the power electrode 23 and the power electrode 24 are input power electrodes of the basic power conversion unit 2, and the power electrode 20 is an output power electrode of the basic power conversion unit 2; power electrode 33 and power electrode 34 are input power electrodes of basic power conversion unit 3, and power electrode 30 is an output power electrode of basic power conversion unit 3.

Fig. 2 shows an embodiment of the present invention in which the circuit transforming function module M1 is formed by parallel-integrating the basic power transforming units 1, the parallel-connection number of the basic power transforming units 1 in the circuit transforming function module M1 is n1, similarly, the circuit transforming function module M2 is formed by parallel-integrating the basic power transforming units 2, and the parallel-connection number of the basic power transforming units 2 in the circuit transforming function module M2 is n 2; the circuit conversion function module M3 is formed by integrating the basic power conversion units 3 in parallel, and the number of the basic power conversion units 3 connected in parallel in the circuit conversion function module M3 is n 3. The parallel number n1, the parallel number n2, and the parallel number n3 shown in fig. 2 are all natural numbers greater than or equal to 1.

The circuit topology of the basic power conversion unit 1, the basic power conversion unit 2 and the basic power conversion unit 3 may be a half-bridge circuit, as shown in fig. 3. The port "DC +" and the port "DC-" are respectively used for connecting the high potential and the low potential of the direct current bus, and the port "AC" is mainly used for outputting an alternating current signal "AC". The dotted frame structure 3051 is a power chip of the upper bridge, and the parallel number n represents that the parallel number of the power chip of the upper bridge is n. The port "DC +", the n parallel structures 3051, the port "AC", and the connection lines to each other form an upper bridge of the basic power conversion cell circuit topology. The dashed-line frame structure 3050 is a power chip of the lower bridge, and the parallel number n represents that the parallel number of the power chips of the lower bridge is also n. The port "AC", the n parallel structures 3050, the port "DC-" and the connection lines between each other constitute a lower bridge of the basic power conversion cell circuit topology.

The upper bridge or the lower bridge of the half-bridge circuit is also referred to as a bridge arm of the half-bridge circuit, and therefore, the half-bridge circuit is also considered to be composed of two bridge arms, one of which is the upper bridge and the other of which is the lower bridge.

The structures shown in the dotted

line boxes

3051 and 3050 are power chips, and the material type of the power chip in the invention can be silicon carbide, silicon or gallium nitride. The structure type of the power chip may be a MOSFET (metal oxide semiconductor field effect transistor), an IGBT (insulated gate bipolar transistor), or a JFET (junction field effect transistor). The structure in the dotted line frame can also be composed of an MOSFET power chip and an anti-parallel diode power chip, an IGBT power chip and an anti-parallel diode power chip, or a structure composed of a JFET power chip and an anti-parallel diode power chip.

Fig. 4 shows a schematic configuration of the basic power conversion unit 1, the basic power conversion unit 2, and the basic power conversion unit 3. The

output power electrodes

11, 21 and 31 in fig. 4 correspond to the port "AC" in fig. 3, the

input power electrodes

15, 25 and 33 correspond to the port "DC +" connected to the high potential of the DC bus in fig. 3, and the

input power electrodes

16, 26 and 34 correspond to the port "DC-" connected to the low potential of the DC bus in fig. 3.

The basic power conversion unit 1 in fig. 4 is composed of an input power electrode 15 and an input power electrode 16, an output power electrode 11, an upper bridge DBC structure 303, a lower bridge DBC structure 304, and a power chip 51 of the upper bridge, a power chip 50 of the lower bridge, and a metal lead 9. The output power electrode 11 is located on an upper copper foil 3042 in the upper bridge DBC structure 303, the input power electrode 15 is located on an upper copper foil 3041 in the lower bridge DBC structure 304, the input power electrode 16 is located on an upper copper foil 3043 in the lower bridge DBC structure 304, the power chip 51 is located on the upper bridge DBC structure 303, the power chip 50 is located on the lower bridge DBC structure 304, and the copper bridge structure 8 is located on the upper copper foil 3041 in the upper bridge DBC structure 303 and the lower bridge DBC structure 304 for electrically connecting the upper bridge DBC structure and the lower bridge DBC structure.

Correspondingly, the basic power conversion unit 2 is composed of an input power electrode 25, an input power electrode 26, an output power electrode 21, an upper bridge DBC structure 309, a lower bridge DBC structure 310, a power chip 55 of the upper bridge, a power chip 54 of the lower bridge, and a metal lead 9. The power chip 55 is located on the upper bridge DBC structure 309, the power chip 54 is located on the lower bridge DBC structure 310, and the copper bridge structure 8 is located on the upper copper foil 3101 in the upper bridge DBC structure 309 and the lower bridge structure 310, and is used for electrically connecting the upper bridge DBC structure and the lower bridge DBC structure.

The basic power conversion unit 3 is composed of a power input electrode 33 and a power input electrode 34, a power output electrode 31, an upper bridge DBC structure 313, a lower bridge DBC structure 314, and a power chip 59 of the upper bridge, a power chip 58 of the lower bridge, and a metal lead 9. The power chip 59 is located on the upper bridge DBC structure 313, the power chip 58 is located on the lower bridge DBC structure 314, and the copper bridge structure 8 is located on the upper copper foil 3141 in the upper bridge DBC structure 313 and the lower bridge DBC structure 314, and is used for achieving electrical connection between the upper bridge DBC structure and the lower bridge DBC structure.

In the embodiment shown in fig. 4, the DBC structure, i.e., a Direct Bond Copper (DBC) structure, is mainly composed of three layers, wherein the middle layer is a ceramic layer, and the upper and lower surfaces of the ceramic layer are copper foil layers. The power chips 50, 51, 54, 55, 58, and 59 correspond to the power chips described in fig. 3.

The basic power conversion unit 1, the basic power conversion unit 2, and the basic power conversion unit 3 shown in fig. 4 are basic units in which the PCU module performs high power density integration. The basic power conversion unit 1 is taken as an example to describe a circulation path of current inside a module when the module operates.

When the basic power conversion unit 1 shown in fig. 4 is operated, current flows from the power electrode 15 into the upper copper foil 3041 in the lower bridge DBC structure 304, flows into the upper bridge DBC structure 303 through the copper bridge 8, then flows through the power chip 51 in the on state into the metal lead 9, the metal lead 9 is connected to the upper copper foil 3402 in the upper bridge DBC structure 303 for welding the power electrode 11, and finally is output from the power electrode 11, so that current flows in the upper bridge. When current enters the upper copper foil 3042 in the upper bridge DBC structure 303 from the power electrode 11, the current directly enters the lower bridge DBC structure 304 through the lead 9, then passes through the power chip 50 in the on state and enters the metal lead 9, the metal lead 9 connects the current to the upper copper foil 3043 of the lower bridge DBC structure 304 connected with the power electrode 16, and finally, the current is output from the power electrode 16, and the current flows in the lower bridge.

Since the upper copper foil of the upper bridge DBC structure 303 does not include the upper copper foil 3041 for electrical connection with the upper bridge DBC structure 303 like the lower bridge DBC structure 304, the layout of the power chip 50 in the lower bridge DBC structure 304 is denser than that of the power chip 51 in the upper bridge DBC structure 303. The lower bridge DBC structure 304 sacrifices a part of an area for laying out the upper copper foil 3401 in order to realize the electrical connection of the upper bridge, that is, the area of the lower bridge DBC structure 304 for laying out the power chip 50 is smaller than the corresponding area of the upper bridge DBC structure 303. This results in an increased coupling between the heat generated by the parallel power chips 50 in the lower bridge DBC structure 304 during operation and the heat transferred to the cooling fluid in the fluid-cooled heat sink, such that the thermal resistance of the power chips 50 in the lower bridge DBC structure 304 (from power chip to cooling fluid) is higher than the thermal resistance of the corresponding upper bridge power chip 51.

In addition, the upper bridge DBC structure (the upper bridge DBC structure 309 and the upper bridge DBC structure 313) and the lower bridge DBC structure (the lower bridge DBC structure 310 and the lower bridge DBC structure 314) in the basic power conversion unit 2 and the basic power conversion unit 3 are also similarly designed, so that the thermal resistance (from the power chip to the cooling liquid) of the power chip (including the power chip 54 and the power chip 58) of the lower bridge is also higher than that of the corresponding power chip (including the power chip 55 and the power chip 59) of the upper bridge.

The cooling liquid is located in the communicated cooling liquid flowing space formed by the liquid-cooled radiator tank 100 and the liquid-cooled radiator plate 200 as shown in fig. 2, and is used for absorbing heat generated by the power chip and removing the heat to the outside of the PCU module through the flow of the cooling liquid,

fig. 5 is a schematic structural diagram 5000 of a high power density integrated PCU module according to an embodiment of the present invention, where the PCU module is composed of 3 different circuit conversion function modules M1, M2, and M3, and the number of parallel connected basic power conversion units in each circuit conversion function module is also 3. The conversion powers of the circuit conversion functional modules M1, M2, and M3 may be different, and the areas of the corresponding liquid cooling heat sink plates 200 may also be different. The basic power conversion units in different circuit conversion function modules can be different from each other in structural design except for consistency in circuit topology.

The differences in the basic power conversion unit structure are mainly reflected in the DBC structure design (DBC plane size and pattern of the upper copper foil of the DBC structure) of the basic power conversion unit, the type and parallel number of the power chips (for example, the power chips 50, 51, 55, 58, and 58 shown in fig. 4) used (for example, the parallel number of the power chip 50 and the power chip 51 in the basic power conversion unit 1 shown in fig. 4 is 2, and the parallel number of the power chip 58 and the power chip 59 in the basic power conversion unit 3 is 1), and the like.

For convenience of description, in fig. 5, the output power electrode of each basic power conversion unit is used to refer to a corresponding basic function conversion unit, for example, the basic power conversion unit 11, the basic power conversion unit 12, and the basic power conversion unit 13 are all power conversion units based on the power rate conversion unit 1, and then the high power density integrated PCU module of this embodiment realizes high power density integration by 9 basic power conversion units, which are the basic power conversion unit 10, the basic power conversion unit 11, the basic power conversion unit 12, the basic power conversion unit 20, the basic power conversion unit 21, the basic power conversion unit 22, the basic power conversion unit 30, the basic power conversion unit 31, and the basic power conversion unit 32, respectively.

In the 9 power conversion units shown in fig. 5, each three groups of the same basic power conversion units form a circuit conversion functional module. On the premise that the circuit conversion function module is not multiplexed, the PCU module realizes the integration of at least three circuit conversion function modules. The three integrated circuit conversion function modules are a circuit conversion function module M1 composed of the basic

power conversion units

10, 11, and 12 numbered beginning with the number "1", a circuit conversion function module M2 composed of the basic

power conversion units

20, 21, and 22 numbered beginning with the number "2", and a circuit conversion function module M3 composed of the basic

power conversion units

30, 31, and 32 numbered beginning with the number "3", respectively.

Fig. 6 shows a schematic cross-sectional view 6000 at a1-a1 of an embodiment of the present invention (as shown in fig. 5), in which heat generated by the power chip 55 is transferred to the protrusion structure 210 of the liquid-cooled heat sink plate in the direction indicated by the arrow, and then transferred to the cooling liquid in the cooling liquid flowing space 220 formed by the liquid-cooled heat sink plate 200 and the liquid-cooled heat sink cavity 100. In the embodiment shown in fig. 6, the liquid-cooled heat sink plate protrusion structures 210 may be uniform protrusion structures at various positions, and the cross-sectional patterns thereof may be uniform, and the intervals between the protrusion structures may be uniform. The cooling fluid of the present invention may be any fluid, such as water, an aqueous solution of ethylene glycol, and the like.

Fig. 7 is an enlarged partial schematic view 7000 of a circular dashed frame structure 6001 in the cross-sectional structural view of a1-a1, in which the direction indicated by the arrow indicates the heat transfer direction of the power chip. When the current flows in the working process of the power chip 55, heat is generated, the generated heat sequentially passes through the second solder layer structure 1002, the upper copper foil layer 3091 of the upper bridge DBC structure 309, the middle ceramic layer 3092 of the upper bridge DBC structure 309, the lower copper foil layer 3093 of the upper bridge DBC structure 309 and the first solder layer 1001 to reach the liquid-cooled heat sink plate 200, finally, heat exchange is carried out between the surface of the liquid-cooled heat sink plate protruding structure 210 and the cooling liquid, the temperature of the cooling liquid in the cooling liquid flowing space 220 is gradually increased after the cooling liquid absorbs the heat, the heat is discharged out of the liquid-cooled heat sink along with the flowing of the cooling liquid in the cooling liquid flowing space 220, and the heat dissipation of the PCU module is realized.

Fig. 8 is a schematic cross-sectional view 8000 illustrating a structure of the liquid crystal cold and hot sink plate 200 at a point a2-a2 according to an embodiment of the present invention (as shown in fig. 5), wherein the convex structures include elongated convex structures 210 and columnar convex structures 230. The design of the convex structures with different shapes in the heat and cold heat sink plate 200 in the invention aims to solve the problem of inconsistent thermal resistance caused by high power density integration of the PCU module.

The high power density integration of the PCU power module's basic power conversion unit on the PCU module's liquid-cooled heat sink plate 200 according to the present invention has the following features,

first, the current or voltage level of each basic power conversion unit may be different, for example, the voltage level may be 600 volts, or 1200 volts; the current level may be 50 amps, 100 amps, or 200 amps;

second, the same type of basic power conversion units are connected in parallel to form the same circuit conversion functional module;

third, each basic power conversion unit is arranged in parallel above the first solder layer structure (such as the first solder layer structure 1001 shown in fig. 7), the bottom parts of the basic power conversion units (such as the surface of the DBC structure 309 in fig. 7 contacted with the lower copper foil layer 3093 and the first solder layer 1001) are all located in the same plane, and the same plane and the top plane of the first solder layer (such as the surface of the DBC structure 309 in fig. 7 contacted with the lower copper foil layer 3093) are the same plane;

the fourth, basic power conversion unit may include a power chip and a DBC structure, and may also include other components such as a capacitor and an inductor;

fifth, heat generated by the power chip (such as the power chip 55 in fig. 7) inside each basic power conversion unit is transferred to the cooling liquid through the second solder layer (such as the second solder layer structure 1002 shown in fig. 7), the DBC structure (such as the upper bridge DBC structure 309 in fig. 7), the first solder layer (such as the structure 1001 in fig. 7) and the liquid-cooled heat sink plate 200, and the heat is absorbed and transferred to and from the liquid-cooled heat sink (such as the structure jointly composed of the liquid-cooled heat sink cavity structure 100 and the liquid-cooled heat sink plate 200 in fig. 1) through the cooling liquid; and

and sixthly, the basic power conversion units are interconnected by using a busbar, and the busbar is a cable or a metal plate structure for realizing electrical connection between power electrodes.

The power chips used among the circuit conversion functional modules of the high-power-density integrated PCU module are not necessarily the same, the parallel number of the power chips in the basic power conversion unit is not necessarily the same, the coupling degree between the heat dissipation paths (as shown in fig. 7) corresponding to the multiple parallel power chips is also not the same, and there is a difference in the lateral expansion during the heat transfer process, so that the effective cross-sectional areas corresponding to the heat dissipation paths (as shown by downward arrows in fig. 8) of the chips are different, and there is a very large difference in the contact areas between the corresponding protruding structures (such as the protruding structure 210 or the protruding structure 230) of the liquid cooling/heating sink plate 200 and the cooling liquid in the cooling liquid flowing space 220 on the heat dissipation paths, so there is a significant difference in the thermal resistance from the junction to the cooling liquid of the power chips of the high-power-density integrated PCU module. The unique thermal resistance (thermal resistance from the power chip to the cooling liquid) is not only reflected between the power chips of different circuit conversion functional modules, but also reflected between the power chips of an upper bridge and a lower bridge of the same functional conversion unit in the same circuit functional module.

The PCU module causes the thermal resistance difference of a power chip due to high power density integration, so that the traditional liquid cooling design of the PCU module cannot solve the problem of overheating of a local chip at low cost effectively. If the power chip with the maximum thermal resistance is used as a reference, the liquid cooling parameters are optimized according to the traditional method, so that the liquid cooling parameters are too harsh, and the liquid cooling cost is greatly increased; if the design standard of the liquid cooling parameters is too widened, although the hot and cold cost is reduced, the overheating risk of the power chip is uncontrollable, and the design of the liquid cooling parameters has no reference basis for quantification. Therefore, the liquid cooling heat dissipation of the high power density integrated PCU module has to be differentially and optimally designed, so as to reduce the risk of overheating the PCU module due to the chip thermal resistance difference caused by the high power density integration.

After the heat generated by the power chip in the PCU module is transmitted to the liquid cooling heat sink structure 200, the heat is exchanged and transmitted at the interface where the liquid cooling heat sink structure 200 contacts with the cooling liquid, and the cooling liquid absorbs the heat and brings the heat out of the liquid cooling radiator along with the flow of the cooling liquid. The size of the contact area between the liquid-cooled heat sink structure 200 and the cooling liquid, and the flow characteristic parameters of the cooling liquid have a great influence on the heat transfer effect, and therefore, optimization of the liquid-cooling parameters for controlling the flow of the cooling liquid, optimization of the liquid-cooled heat sink structure and the contact area of the cooling liquid, and optimization of the flow performance of the cooling liquid in the cooling liquid flow space 220 are important components of the liquid-cooled design of the PCU module.

The liquid cooling radiator in the embodiment of the invention comprises cooling liquid, a cooling liquid inlet 101, a cooling liquid outlet 102, a liquid cooling radiator cavity 100 and a liquid cooling heat sinking plate 200, wherein the cooling liquid flows in a cooling liquid flowing space 220 formed by the liquid cooling radiator cavity and the liquid cooling heat sinking plate, enters the liquid cooling radiator from the cooling liquid inlet 101 and flows out of the liquid cooling radiator from the cooling liquid outlet 102; a first solder layer 1001 on the upper surface of the liquid-cooled heat sink plate; a plurality of circuit conversion function modules located above the first solder layer, each circuit conversion function module including a plurality of power conversion units, including: a DBC structure comprising an upper bridge DBC structure and a lower bridge DBC structure; a second solder layer 1002 on the upper surface of the DBC structure; and the power chip is positioned on the upper surface of the second solder layer, wherein the heat generated by the power chip is transmitted to the cooling liquid through the second solder layer 1002, the DBC structure, the first solder layer 1001 and the liquid cooling and heating sinking plate 200, and the heat is transmitted out of the liquid cooling radiator through the cooling liquid.

The plurality of circuit converting function modules in the PCU module (as shown in fig. 5) according to an embodiment of the present invention include a first circuit converting function module M1, a second circuit converting function module M2, and a third circuit converting function module M3, and the flow path of the coolant in the coolant flow space is: after entering the liquid-cooled radiator through the cooling liquid inlet 101, the cooling liquid firstly passes through the cooling liquid flowing space corresponding to the upper bridge DBC structure of the first circuit conversion function module, then reaches the cooling liquid flowing space corresponding to the upper bridge DBC structure of the second circuit conversion function module, then reaches the cooling liquid flowing space corresponding to the upper bridge DBC structure of the third circuit conversion function module, then sequentially enters the cooling liquid flowing space corresponding to the lower bridge DBC structure of the third circuit conversion function module, the cooling liquid flowing space corresponding to the lower bridge DBC structure of the second circuit conversion function module and the cooling liquid flowing space corresponding to the lower bridge DBC structure of the first circuit conversion function module, and finally flows out of the liquid-cooled radiator through the cooling liquid outlet 102.

The circuit conversion function module upper bridge DBC structure is a structure composed of the upper bridge DBC structures of all the basic power conversion units included in one circuit conversion function module, and for example, the first circuit conversion function module upper bridge DBC structure shown in fig. 5 is a structure composed of the upper bridge DBC structures of the basic power conversion unit 10, the basic power conversion unit 11, and the basic power conversion unit 12. The circuit conversion function module lower bridge DBC structure is a structure composed of DBC structures of lower bridges among all basic power conversion units included in one circuit conversion function module, for example, the first circuit conversion function module lower bridge DBC structure shown in fig. 5 is a structure composed of a basic power conversion unit 10, a basic power conversion unit 11, and a lower bridge DBC among the basic power conversion units 12.

The liquid cooling radiator design in the high power density integrated PCU module of the present invention includes three aspects, one is the position layout design of the cooling liquid inlet 101 and the cooling liquid outlet 102; a bonding method for forming a cooling liquid flowing space 220 by the liquid cooling radiator cavity 100 and the liquid cooling heat sinking plate 200; thirdly, the design of the communicated cooling liquid flowing space 220 formed by the liquid cooling radiator cavity 100 and the liquid cooling heat sinking plate 200 in a sealing way.

As for the layout design of the positions of the cooling liquid inlet 101 and the cooling liquid outlet 102, the design may be that the cooling liquid inlet 101 and the cooling liquid outlet 102 are on the same side of the liquid-cooled heat sink cavity 100 as shown in fig. 1, or the design may be that the cooling liquid inlet 101 is distributed on one side of the liquid-cooled heat sink cavity 100 (e.g., on the left side of the liquid-cooled heat sink cavity 100 in fig. 1) and the cooling liquid outlet 102 is distributed on the other side of the liquid-cooled heat sink cavity 100 (e.g., on the right side of the liquid-cooled heat sink cavity 100 in fig. 1); it is also possible to provide a design in which the positions of the coolant inlet 101 and the coolant outlet 102 are reversed.

The bonding method for forming the closed and communicated cooling liquid flowing space 220 between the liquid cooling heat sink cavity 100 and the liquid cooling heat sink plate 200 can be mechanical pressing by using screws or integral forming after welding, and any one of the two methods is adopted and belongs to a characteristic of the structural design of the liquid cooling heat sink cavity.

For the liquid-cooled heat sink plate 200 and the liquid-cooled heat sink chamber 100 to form a hermetically communicated fluid space, as shown by the coolant flow space 220 shown in fig. 6 and 8. The cooling liquid flows in the cooling liquid flowing space 220, and the characteristics of the cooling liquid flowing space 220 have a direct influence on the flowing efficiency (the flowing efficiency refers to the capability of the cooling liquid to flow rapidly) and the heat dissipation effect of the cooling liquid, and the characteristics of the cooling liquid flowing space depend on the design of the protruding structure of the liquid-cooled heat sink plate 200 deep into the cooling liquid flowing space.

Fig. 9 is a schematic structural design view of the liquid cooling/heating sinking plate 200 according to the embodiment of the present invention shown in fig. 1, wherein the protruding structures of the liquid cooling/heating sinking plate 200 extending into the cooling liquid flowing space 220 are composed of two different types of structures, namely, elongated protruding structures 210 and columnar protruding structures 230. In fig. 9, in the bump structure of the area corresponding to the liquid-cooled heat sink plate 200 where the difference in thermal resistance of the power chip is large, part of the elongated bump structure 210 is replaced with the columnar bump structure 230 to increase the contact area between the liquid-cooled heat sink plate structure 200 and the cooling liquid, so as to reduce the difference in thermal resistance from the junction (the power chip itself) to the cooling liquid of the corresponding power chip. In fig. 9, double-headed arrow 2201 indicates the direction of flow of the coolant in fluid space 220 corresponding to the upper bridge DBC structure of the PCU module, and double-headed arrow 2202 indicates the direction of flow of the coolant in fluid space 220 corresponding to the lower bridge DBC structure of the PCU module.

The liquid-cooled heat sink plate protrusion structure according to the present invention is designed to solve the problem of the thermal characteristic difference of the chip heat dissipation path due to the high power density integration of the PCU module, and includes a combination of different types of protrusion structures, and a design of the adjacent different types of protrusion structures and the coolant flow space 220 to ensure the coolant flow efficiency.

The array pair formed by the long-strip-shaped convex structures in the design of the combination of the convex structures of different types is beneficial to improving the flowing efficiency of the cooling liquid in the cooling liquid flowing space, while the array formed by the columnar convex structures is beneficial to improving the contact area between the liquid cooling heat sink plate structure 200 and the cooling liquid, reducing the thermal resistance and simultaneously reducing the difference of the thermal resistances between chips with different powers. The combination design of the different types of convex structures in the invention has consideration on the flowing efficiency of the cooling liquid and the reduction of the difference of the thermal resistance, and the layout characteristics of the long-strip convex structures 210 and the columnar convex structures 230 in the liquid cooling and heating sinking plate are as follows:

the columnar protruding structure 230 corresponds to a local area with larger thermal resistance of the power chip in the layout area of the liquid cooling and heating sinking plate, or corresponds to a local area with larger thermal resistance difference of the power chip in the same circuit conversion functional module; and

the elongated protrusion structures 210 correspond to the layout area of the liquid-cooled heat sink plate and the local area of the cooling liquid flowing space where the cooling liquid flowing efficiency needs to be accelerated.

In the liquid-cooled heat sink according to the embodiment of the present invention shown in fig. 9, the columnar protrusion structure 230 of the liquid-cooled heat sink plate is disposed in the local area of the liquid-cooled heat sink plate corresponding to the first circuit converting function module M1, and the local area of the liquid-cooled heat sink plate corresponding to the whole first circuit converting function module M1 is not disposed as the columnar protrusion structure, but the design of disposing the local area of the liquid-cooled heat sink plate corresponding to the whole first circuit converting function module M1 as the columnar protrusion structure 230 also belongs to the design covered by the present invention, and the design of disposing the columnar protrusion structure 230 in the local area of the liquid-cooled heat sink plate corresponding to other circuit converting function modules also belongs to the design covered by the present invention.

Fig. 10 is an enlarged schematic view of the region indicated by the dashed-line box 2001 in fig. 9, where the adjacent regions of the elongated protrusion structures 210 and the pillar protrusion structures 230 in fig. 10 are indicated by the square dashed-line box 2002 and the circular dashed-line box 2004. In the region indicated by the circular dashed-line box 2004 as indicated by an arrow 2201 in fig. 10, the cooling liquid flows from the cooling liquid flow spaces 220 divided by the columnar protruding structures 230 toward the cooling liquid flow spaces divided by the elongated protruding structures 210. The surface of the elongated projection structure 210 perpendicular to the flow direction of the coolant and facing the columnar projection structures 230 is a surface 2101, and any other cross section of the elongated projection structure 210 parallel to the surface 2101 is denoted by reference numeral 2102. In the region indicated by the square dashed-line box 2002 as indicated by an arrow 2202 in fig. 10, the coolant flow space into which the coolant is divided by the elongated protrusion 210 flows toward the coolant flow space into which the columnar protrusion structures 230 are divided, and the elongated protrusion structures 210 are designed in conformity with the elongated protrusion structures as indicated by the circular dashed-line box 2201.

Fig. 11 is a partially enlarged schematic plan view of the elongated protrusion structures 210 and the neighboring regions 2002 of the pillar bump structures 230 in the liquid-cooled heat sink plate 200 according to the embodiment of the present invention shown in fig. 10. The direction of parallel arrows 2201 is shown as the direction of coolant flow in the localized area described by area 2002.

In the design of the liquid-cooled heat sink plate in the liquid-cooled radiator in the high power density integrated PCU module according to the present invention, the combination design of the different types of projection structures employed for ensuring the flow efficiency of the cooling liquid, and the design of the cooling liquid flow space of the different types of projections in the adjacent local regions (as shown by the square dashed box 2002 and the circular dashed box 2004 in fig. 10) have the following characteristics:

first, as shown in FIG. 10, the area of the surface 2101 of the elongated protrusion structures 210 perpendicular to the flow direction of the cooling liquid and facing the stud protrusion structures 230 is smaller than that of the elongated protrusion structures 210 at any other position

(indicated by the face 2102 in FIG. 10) in cross-section, in order to facilitate coolant flow in the areas indicated by the square dashed box 2002 and the circular dashed box 2004 without local backflow or increased flow resistance due to lack of interfaces and abrupt transitions.

One feature of the second array of stud bump structures 230 shown in fig. 11 is: the distance d3 between the columnar protruding structures in the direction parallel to the elongated protruding structures (the direction parallel to the flow direction of the cooling liquid indicated by the arrow 2201) does not exceed the distance d2 in the direction perpendicular to the elongated protruding structures (the direction perpendicular to the flow direction of the cooling liquid indicated by the arrow 2201), i.e., d3 is not more than d2, and such design facilitates the cooling liquid to receive less resistance when flowing in the cooling liquid flowing space 220.

Third, as shown in fig. 11, one feature of the array of elongated raised structures 210 and the array of pillar raised structures 230 is that the distance d1 between the elongated raised structures 210 is not less than the distance d2 between the pillar raised structures 230, i.e. d2 ≦ d 1.

In the integrated PCU module with high power density according to an embodiment of the present invention, heat generated by the power chip during operation is transferred to the cooling liquid in the cooling liquid flowing space 220 sequentially through the second solder layer 1002, the DBC structure (for example, the upper bridge DBC structure 309), the first solder layer 1001, and the liquid cooling/heating sinking plate 200, and then the heat is discharged from the liquid cooling outlet 102 to the PCU module by the flow of the cooling liquid, thereby achieving liquid cooling heat dissipation of the PCU module.

The flow path of the coolant flow space 220 of the coolant in the liquid-cooled heat sink is: after entering the liquid-cooled radiator through the cooling liquid inlet 101, the cooling liquid firstly passes through the cooling liquid flowing space corresponding to the upper bridge of the circuit conversion functional module M1, then reaches the cooling liquid flowing space corresponding to the upper bridge of the circuit conversion functional module M2, then reaches the cooling liquid flowing space corresponding to the upper bridge of the circuit conversion functional module M3, then sequentially enters the liquid-cooled fluid space corresponding to the lower bridge of M3, the liquid-cooled fluid space corresponding to the lower bridge of M2 and the liquid-cooled fluid space corresponding to the lower bridge of M1, and finally flows out through the cooling liquid outlet 102. Therefore, heat generated when the power chip works is removed from the liquid cooling radiator of the PCU module.

In an embodiment of the present invention, the initial position of the coolant flow path inside the liquid-cooled heat sink chamber 100 corresponds to a local area of the coolant flow space corresponding to the upper bridge of the circuit switching function module M1, and the final position corresponds to a local area of the coolant flow space corresponding to the lower bridge of the circuit switching function module M1, as shown in fig. 5.

The upper bridge of the circuit conversion functional module is composed of the upper bridges of all the basic power conversion units in the circuit conversion functional module. The region of the upper bridge of one circuit conversion function module in the coolant flow space on the coolant flow path corresponds to a local region of the coolant flow space directly below the DBC structure of the circuit conversion function module. For example, in fig. 5, the region corresponding to the upper bridge of the circuit converting function module M1 in the coolant flow path is a partial region corresponding to the coolant flow space directly below the upper bridge DBC structure connected to the

power electrodes

10, 11, and 12

Similarly, the lower bridge of the circuit conversion functional module is composed of the lower bridges of all the basic power conversion units in the circuit conversion functional module. The region of the lower bridge of one circuit conversion function module in the coolant flow space on the coolant flow path corresponds to a local region of the coolant flow space directly below the DBC structure of the circuit conversion function module. For example, in fig. 5, the region corresponding to the lower bridge of the circuit converting function module M1 in the coolant flow path is a partial region corresponding to the coolant flow space directly below the lower bridge DBC structure connected to the

power electrodes

13, 14, 15, 16, 17, and 18.

The liquid cooling parameter optimization method of the cooling liquid comprises the flow rate and the temperature of the cooling liquid at a cooling liquid inlet, wherein the reference standard takes the characteristic that thermal resistance parameters are inconsistent due to high power density integration of a PCU (Power control Unit) module as a core, and the liquid cooling parameter design method is jointly composed of a series of calculation steps.

Fig. 12 is a schematic diagram 9000 of a reference standard for designing liquid cooling parameters of a cooling liquid according to an embodiment of the present invention, which comprises: first, the highest temperature of the cooling liquid in the cooling liquid flowing space 220 is lower than the boiling point of the cooling liquid itself; secondly, the highest junction temperature of the power chip is lower than the maximum temperature allowed by the chip; thirdly, the highest pressure of the coolant in the coolant flowing space 220 is lower than the maximum pressure that the radiator cavity can bear or lower than a certain set value, and the value can be any value considered to be set; fourthly, the difference value obtained by subtracting the temperature accumulation of the power chip with the highest temperature in the lower bridge and only related to the flowing of the cooling liquid from the temperature accumulation of the power chip with the highest temperature in the upper bridge and only related to the flowing of the cooling liquid in the same circuit conversion functional module is approximately equal to zero; and the difference between the temperature accumulation of the fifth and first power chips only related to the flow of the cooling liquid and the temperature accumulation of the second power chip only related to the flow of the cooling liquid is equal to zero.

The first power chip refers to the power chip with the highest temperature in the power chips of the bridge arm (bridge arm refers to an upper bridge or a lower bridge) corresponding to the circuit conversion functional module next to the cooling liquid inlet 101 near the starting position of the cooling liquid flow path in the PCU module, for example, the power chip with the highest temperature in the power chip of the upper bridge of the circuit conversion functional module M1 in the embodiment of the present invention shown in fig. 5. The second power chip is a power chip with the highest temperature among the power chips of the bridge arm corresponding to the circuit switching function module next to the cooling liquid outlet 102 near the termination position of the cooling liquid flow path in the PCU module, for example, the power chip with the highest temperature among the power chips of the lower bridge of the circuit switching function module M1 in an embodiment of the present invention as shown in fig. 5.

The liquid cooling parameters of the cooling liquid comprise the flow speed and the temperature of the cooling liquid at a cooling liquid inlet, and the design method of the liquid cooling parameters comprises the following steps: setting the initial temperature and the initial flow rate of the cooling liquid; simulating the temperature of the PCU module to obtain the junction temperature of each power chip in the PCU module; selecting junction temperature of a first power chip in a bridge arm corresponding to a circuit conversion function module close to a cooling liquid inlet in the PCU module and junction temperature of a second power chip in a bridge arm corresponding to a circuit conversion function module close to a cooling liquid outlet; calculating a temperature difference on a heat transfer path of the first power chip from the junction to the cooling liquid and a temperature difference on a heat transfer path of the second power chip from the junction to the cooling liquid; calculating a temperature accumulation of the first power chip associated with the flow of the coolant only and a temperature accumulation of the second power chip associated with the flow of the coolant only; and calculating the difference between the temperature accumulation of the first power chip only related to the flowing of the cooling liquid and the temperature accumulation of the second power chip only related to the flowing of the cooling liquid, outputting the optimal flow rate of the cooling liquid when the difference is about zero, and otherwise, continuously repeating the steps after increasing the flow rate of the cooling liquid.

The core of the liquid cooling parameter design method is a calculation method consisting of temperature simulation of a PCU module and a series of calculation steps of the flow rate of cooling liquid based on the inconsistent characteristic of thermal resistance. In the optimization design process of the liquid cooling parameters, the simulation software and the method for obtaining the temperature (junction temperature) of the power chip in the PCU module are not particularly limited, and the method also comprises the step of directly obtaining the junction temperature of the power chip by using a test method without using a simulation means.

Fig. 13 is a schematic view 9100 of a liquid cooling parameter calculation method according to an embodiment of the present invention. The specific steps and method for calculating the liquid cooling parameters are as follows:

first, the initial coolant level at the coolant inlet 101 is set at the start of the PCU module temperature simulationInitial temperature T_inletAnd an initial flow velocity V₀；

Secondly, simulating the temperature of the PCU module by using software to obtain the highest temperature corresponding to each power chip in the module, wherein the highest temperature of the power chip is also commonly referred to as the junction temperature of the power chip;

thirdly, selecting a first power chip with the highest temperature in a bridge arm corresponding to the circuit conversion function module close to the cooling liquid inlet 101; and selecting a second power chip with the highest temperature in the bridge arm corresponding to the circuit conversion functional module close to the cooling liquid outlet 102. For example, in the embodiment of the present invention as shown in fig. 5, the bridge arm corresponding to the circuit switching functional module next to the coolant inlet 101 is the upper bridge of M1, and the bridge arm corresponding to the circuit switching functional module next to the coolant outlet is the lower bridge of M1. The first power chip is the power chip with the highest temperature in the upper bridge of the circuit conversion functional module M1, and the corner mark "i" represents the number of the first power chip in the upper bridge of M1, so that the junction temperature of the first power chip is T_{i_max,1}(ii) a The second power chip is the power chip with the highest junction temperature in the down bridge of the circuit conversion function module M1, and the corner mark "j" represents the number of the first power chip in the M1 down bridge, so that the junction temperature of the second power chip is T_{j_max,2}。

Fourthly, calculating the temperature difference of the first power chip and the second power chip on the heat transmission path from the junction (the power chips themselves) to the cooling liquid, wherein the temperature difference of the first power chip is T'_i,1The temperature difference corresponding to the second power chip is T'_j,2. This temperature difference is independent of the temperature accumulation caused by the flow of the cooling liquid, and its value depends on the thermal resistance of the heat transfer flow path of the power chip from the junction (the power chip itself) to the cooling liquid and the heat generation power P of the power chip. The heating power P is the heating power set for the power chip when the temperature of the PCU module is simulated in the second step, wherein the heating power of the first power chip is P_i,1The heating power of the second power chip is P_j,2. The calculation formula of the temperature difference is as shown in the formula in the fourth step in fig. 13, and for the first power chip: t'_i,1＝P_i,1×R_{th_i,1}Wherein R is_{th_i,1}The thermal resistance from the junction to the cooling liquid corresponding to the first power chip; for the second power chip: t'_j,2＝P_j,2×R_{th_j,2}Wherein R is_{th_j,2}The thermal resistance from the junction to the cooling liquid corresponding to the second power chip. Due to high power density integration, the thermal resistances of different power chips from the junction to the cooling liquid have inconsistent characteristics, so that the temperature difference between the power chips from the junction to the cooling liquid can be different even under the condition of the same heating power when the module works.

Fifth, calculate the temperature accumulation Δ T of the first power chip related to the coolant flow only_i,1And a temperature accumulation Δ T of the second power chip related to the flow of the coolant only_j,2. For the first power chip, the calculation formula for the temperature accumulation associated with the coolant flow only is: delta T_i,1＝T_{i_max,1}-T′_i,1-T_inlet(ii) a For the second power chip, the calculation formula for the temperature accumulation associated with the coolant flow only is: delta T_j,2＝T_{j_max,2}-T′_j,2-T_inlet；

Sixth, calculate the temperature accumulation (Δ T) of the first power chip associated with coolant flow only_i,1) And temperature build-up (Δ T) of the second power chip associated with coolant flow only_j,2) The calculation formula of the difference value Δ T of (d) is: Δ T ═ Δ T_i,1-ΔT_j,2. If the difference Δ T is much less than zero, it indicates that the second power chip has a temperature accumulation Δ T associated only with the flow of coolant_j,2Temperature build-up Δ T higher than that of the first power chip associated with coolant flow only_i,1. That is, the extra temperature rise of the power chips in the bridge arm corresponding to the circuit conversion function module at the end position of the coolant flow path, which is caused by the low flow velocity of the coolant, is higher than the extra temperature rise of the power chips in the bridge arm corresponding to the circuit conversion function module at the start position. This means that for a given initial temperature (T) of the cooling liquid in the first step_inlet) In other words, the initial flow rate (V) of the coolant is set₀) Too low.

Maintaining the initial temperature of the coolant at the coolant inlet 101Degree T_inletUnder the unchangeable prerequisite, in order to improve the liquid cooling heat dissipation of module, need increase the initial velocity of flow of coolant liquid. I.e. increasing the initial flow rate V in the first step₀Then, according to the steps and flow chart shown in fig. 13, the simulation and calculation are carried out again until the temperature accumulation (Δ T) of the first power chip is only related to the flow of the cooling liquid_i,1) And temperature build-up (Δ T) of the second power chip associated with coolant flow only_j,2) Is approximately equal to zero. At this time, the flow rate of the coolant and the initial temperature T_inletAdapted to the optimum flow rate V of the cooling liquid at this temperature_opt。

The description of the liquid cooling parameter calculation method illustrated in fig. 13 is based on the design that the inlet 101 and the outlet 102 of the liquid cooling radiator cavity cooling liquid are on the same side of the module, and the circuit conversion function modules next to the inlet 101 and the outlet 102 of the hot cooling radiator cavity cooling liquid are the same. For the design that the cooling liquid inlet 101 and the cooling liquid outlet 102 are not on the same side of the liquid cooling cavity, the calculation method is also applicable, and only needs to find out the first power chip in the bridge arm corresponding to the circuit conversion functional module with the cooling liquid inlet 101 close to the second power chip in the bridge arm corresponding to the circuit conversion functional module with the cooling liquid outlet 102 close to the third step of the calculation step shown in fig. 13, and make corresponding adjustments in the subsequent calculation step. The calculation method is also applicable to the case where the cooling liquid inlet 101 and the cooling liquid outlet 102 are designed on the same side of the liquid cooling chamber, but the positions of the cooling liquid inlet and the cooling liquid outlet are just exchanged with those of the embodiment of the present invention, that is, the cooling liquid inlet 101 is changed into 102, and the cooling liquid outlet 102 is changed into 101.

In addition, the calculation of the temperature accumulation of the power chip with the highest junction temperature of the upper bridge only related to the flow of the cooling liquid and the calculation of the temperature accumulation of the power chip with the highest junction temperature of the lower bridge only related to the flow of the cooling liquid in the same circuit conversion functional module can refer to the calculation method shown in fig. 13. The fourth design item in fig. 12 for the liquid cooling parameters of the same circuit conversion function module in the PCU module is also an important component of the liquid cooling design of the present invention, and is mainly used for evaluating the difference between the temperature accumulations of the upper bridge and the lower bridge power chips in the same circuit conversion function module, which are only related to the flow of the cooling liquid.

The liquid-cooling parameter optimization method is obtained based on the PCU module according to an embodiment of the present invention, but the liquid-cooling parameter optimization method according to the present invention is not limited to the liquid-cooling heat dissipation structure design of the PCU module according to the present invention, and includes other types of liquid-cooling heat dissipation structure designs. Of course, the liquid cooling parameter optimization method of the present invention may also be independent of the specific liquid cooling heat dissipation structure, and may be only used as an independent liquid cooling parameter optimization method.

While the present invention has been described with reference to several exemplary embodiments, it is understood that the terminology used is intended to be in the nature of words of description and illustration, rather than of limitation. As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the meets and bounds of the claims, or equivalences of such meets and bounds are therefore intended to be embraced by the appended claims.

Claims

1. A high power density integrated PCU module, comprising:

the liquid cooling radiator comprises cooling liquid, a cooling liquid inlet, a cooling liquid outlet, a liquid cooling radiator cavity and a liquid cooling heat sink plate, wherein the cooling liquid flows in a cooling liquid flowing space formed by the liquid cooling radiator cavity and the liquid cooling heat sink plate, enters the liquid cooling radiator from the cooling liquid inlet and flows out of the liquid cooling radiator from the cooling liquid outlet;

the first solder layer is positioned on the upper surface of the liquid cooling heat sink plate;

the circuit conversion function modules are positioned above the first welding flux layer, each circuit conversion function module comprises a plurality of basic power conversion units, the circuit topological structure of each basic power conversion unit is a half-bridge topological structure formed by connecting an upper bridge arm and a lower bridge arm in series, and each upper bridge arm or each lower bridge arm comprises a DBC structure, a second welding flux layer, a power chip, a metal lead and a power electrode, wherein:

the DBC structure is positioned on the upper surface of the first solder layer;

the second solder layer is positioned on the upper surface of the DBC structure; and

the power chip is positioned on the upper surface of the second welding flux layer, heat generated in the work of the power chip is transmitted to cooling liquid from the power chip through the second welding flux layer, the DBC structure, the first welding flux layer and the liquid cooling heat sink plate, and the heat is transmitted out of the liquid cooling radiator through the flow of the cooling liquid; when the heat of the power chip cannot be timely transmitted out of the liquid cooling radiator, the temperature of the power chip will rise and form a temperature which tends to be stable, and the temperature of the power chip at the moment is junction temperature;

the difference between the junction temperature and the temperature of the cooling liquid at the cooling liquid inlet of the liquid cooling radiator cavity is temperature accumulation, and the temperature accumulation comprises temperature accumulation related to a heat transmission path from the power chip to the cooling liquid and temperature accumulation related to flowing of the cooling liquid;

the temperature accumulation related to the heat transfer path from the power chip to the cooling liquid refers to the temperature accumulation caused by the thermal resistance of the heat transfer path from the power chip to the cooling liquid; the temperature accumulation related to the flowing of the cooling liquid refers to the temperature accumulation related to the additional temperature rise of the local cooling liquid caused by the transmission heat from other power chips on the path of the cooling liquid flowing from the liquid cooling liquid inlet to the cooling liquid outlet in the cooling liquid flowing space;

the difference value obtained by subtracting the temperature accumulation of the power chip with the highest temperature in the lower bridge arm and only related to the flowing of the cooling liquid from the temperature accumulation of the power chip with the highest temperature in the upper bridge arm in the same circuit conversion functional module is approximately equal to zero; and

the difference between the temperature accumulation of the first power chip associated with coolant flow only minus the temperature accumulation of the second power chip associated with coolant flow only is approximately equal to zero: the first power chip is a power chip with the highest temperature in a bridge arm corresponding to a circuit conversion function module next to a cooling liquid inlet in the vicinity of the starting position of a cooling liquid flow path, and the second power chip is a power chip with the highest temperature in a bridge arm corresponding to a circuit conversion function module next to a cooling liquid outlet in the vicinity of the ending position of the cooling liquid flow path.

2. The PCU module as claimed in claim 1, wherein the respective basic power conversion units are arranged in parallel above the first solder layer, the bases thereof are all located in the same plane, the plane is the same plane as the top plane of the first solder layer, and the respective basic power conversion units are interconnected using bus bars.

3. The PCU module as set forth in claim 1, wherein the liquid-cooled radiator further comprises: the liquid cooling and heating sinking plate goes deep into the long strip-shaped protruding structures and the columnar protruding structures in the cooling liquid flowing space, the distance between the long strip-shaped protruding structures is not smaller than the distance between the columnar protruding structures, the area of the surface, perpendicular to the flowing direction of cooling liquid and facing the columnar protruding structures, of the long strip-shaped protruding structures in the area where the long strip-shaped protruding structures are adjacent to the columnar protruding structures is smaller than the area of cross sections of other optional positions, parallel to the surface, in the long strip-shaped protruding structures, and the distance between the columnar protruding structures in the direction parallel to the long strip-shaped protruding structures is not larger than the distance between the columnar protruding structures in the direction perpendicular to the long strip-shaped protruding structures.

4. The PCU module according to claim 3, wherein the columnar projection structure corresponds to a local area where thermal resistance of the power chip is large in a layout area of the liquid-cooled heat sink plate, or corresponds to a local area where a difference in thermal resistance of the power chip is large in the same circuit conversion function module, and the elongated projection structure corresponds to a local area of a coolant flow space where coolant flow efficiency is required to be increased in the layout area of the liquid-cooled heat sink plate.

5. The PCU module as set forth in claim 1, wherein

The highest temperature of the cooling liquid in the cooling liquid flowing space is lower than the boiling point of the cooling liquid;

the highest junction temperature of the power chip is lower than the maximum temperature allowed by the power chip; and

the highest pressure of the cooling liquid in the cooling liquid flowing space is lower than the maximum pressure which can be borne by the radiator cavity or a certain set value.

6. The PCU module as set forth in claim 1, wherein the liquid cooling parameters of the coolant include a flow rate and a temperature of the coolant at a coolant inlet, and the method of designing the liquid cooling parameters includes:

setting the initial temperature and the initial flow rate of the cooling liquid;

simulating the temperature of the PCU module to obtain the junction temperature of each power chip in the PCU module;

selecting junction temperature of a first power chip in a bridge arm corresponding to a circuit conversion function module close to a cooling liquid inlet in the PCU module and junction temperature of a second power chip in a bridge arm corresponding to a circuit conversion function module close to a cooling liquid outlet;

calculating a temperature accumulation of the first power chip only in relation to a heat transfer path from the power chip itself to the cooling liquid and calculating a temperature accumulation of the second power chip only in relation to a heat transfer path from the power chip itself to the cooling liquid;

calculating a temperature accumulation of the first power chip associated with the flow of the coolant only and a temperature accumulation of the second power chip associated with the flow of the coolant only; and

and calculating the difference value between the temperature accumulation of the first power chip only related to the flowing of the cooling liquid and the temperature accumulation of the second power chip only related to the flowing of the cooling liquid, wherein the flow rate of the cooling liquid corresponding to the difference value is about zero and is the optimal flow rate of the cooling liquid, and otherwise, continuously repeating the steps after increasing the flow rate of the cooling liquid.

7. The PCU module according to claim 1, wherein the plurality of circuit transforming function modules include a first circuit transforming function module, a second circuit transforming function module, and a third circuit transforming function module, and a flow path of the coolant in the coolant flow space is: after entering the liquid-cooled radiator through the cooling liquid inlet, the cooling liquid firstly passes through the cooling liquid flowing space corresponding to the upper bridge DBC structure of the first circuit conversion function module, then reaches the cooling liquid flowing space corresponding to the upper bridge DBC structure of the second circuit conversion function module, then reaches the cooling liquid flowing space corresponding to the upper bridge DBC structure of the third circuit conversion function module, then sequentially enters the cooling liquid flowing space corresponding to the lower bridge DBC structure of the third circuit conversion function module, the cooling liquid flowing space corresponding to the lower bridge DBC structure of the second circuit conversion function module and the cooling liquid flowing space corresponding to the lower bridge DBC structure of the first circuit conversion function module, and finally flows out of the liquid-cooled radiator through the cooling liquid outlet.

8. A high power density integrated PCU module, comprising:

liquid cooling radiator, including coolant liquid, coolant liquid entry, coolant liquid export, liquid cooling radiator cavity and liquid cooling heat sink, the coolant liquid flows in the coolant liquid flow space that is formed by liquid cooling radiator cavity and the heavy board of liquid cold heat, gets into liquid cooling radiator by the coolant liquid entry to flow out liquid cooling radiator by the coolant liquid export, liquid cooling radiator still includes that liquid cold heat sinks the long banding protruding structure and the column protruding structure of board deep into coolant liquid flow space, and wherein the interval that long banding protruding structure is each other is not less than the interval that column protruding structure is each other, and long banding protruding structure is perpendicular with the coolant liquid flow direction and just to the area of the face of column protruding structure in the area that long banding protruding structure and column protruding structure are adjacent is less than the area of the cross section of other optional positions parallel with this face in the long banding protruding structure, and the interval that long banding protruding structure parallel direction is not more than and long banding protruding structure each other between the column protruding structure each other The distance between the structures in the vertical direction;

the circuit conversion function modules are positioned above the first welding flux layer, each circuit conversion function module comprises a plurality of basic power conversion units, the circuit topological structure of each basic power conversion unit is a half-bridge topological structure formed by connecting an upper bridge arm and a lower bridge arm in series, and each upper bridge arm or each lower bridge arm comprises a DBC structure, a second welding flux layer and a power chip, wherein:

the DBC structure is positioned on the upper surface of the first solder layer;

the power chip is located on the upper surface of the second solder layer, wherein heat generated by the power chip is transmitted to the cooling liquid through the second solder layer, the DBC structure, the first solder layer and the liquid cooling heat sink plate, and the heat is transmitted out of the liquid cooling radiator through the cooling liquid.

9. The PCU module according to claim 8, wherein the columnar bump structure corresponds to a local area where thermal resistance of the power chip is large in a layout area of the liquid-cooled heat sink plate, or corresponds to a local area where a difference in thermal resistance of the power chip is large in the same circuit conversion function module.

10. The PCU module according to claim 8, wherein the elongated projection structure corresponds to a layout area of the liquid-cooled heat sink plate and a local area of the cooling liquid flow space where the cooling liquid flow efficiency needs to be increased.