A method for controlling the bubble rate for the heat dissipation of the relay in a high-voltage control box

Abstract

The present invention proposes a method for controlling the bubble rate for the heat dissipation of the relay in the high-voltage control box, belonging to the high-voltage control box. A three-dimensional model of the high-voltage control box is established. It is preset that when the bubbles are distributed to the position that can most weaken the heat dissipation of the relay in the high-voltage control box, the temperature rise situation of the key heat source relay in the high-voltage control box when the bubble rate gradually increases is simulated by means of simulation, and the temperature rise change rate of the key heat source relay is calculated and obtained; through mathematical fitting means, the formula relationship between the bubble rate and the temperature rise change rate is obtained; according to the temperature rise situation of the key heat source relay in the product under different bubble rates, the bubble rate threshold of the product is determined according to the temperature rise requirement of the product; the temperature rise situation of the heat source relay under different bubble rates is obtained through the formula relationship between the bubble rate and the temperature rise change rate of the heat source relay, and the bubble rate threshold of the high-voltage control box under the safety margin is determined according to the actual temperature rise requirement of the product, so as to control the bubble rate of the high-voltage control box subsequently.

Description

Technical Field

[0001] The present invention relates to the technical field of high-voltage control boxes, and particularly to a method for controlling the bubble rate for the heat dissipation of a relay in a high-voltage control box. Background Art

[0002] The function of the high-voltage control box of a new energy vehicle is to distribute the high-voltage electricity of the power battery to high-voltage electrical equipment such as a motor controller, a drive motor, an electric air-conditioning compressor, a PTC heater, and a DC / DC. At the same time, the high-voltage charging current of the AC and DC charging interfaces is distributed to the power battery to charge the power battery. There is a set of high-voltage power distribution system on an electric vehicle.

[0003] In recent years, new energy vehicles have gradually popularized the super-fast charging function. The super-fast charging current is usually large, and the high-voltage control box that meets the super-fast charging function usually faces great heat dissipation challenges. The high-voltage control box adopts a homogenization design. The heat of the heat source is transferred to the cold plate of the battery pack at the bottom of the high-voltage control box through a heat-conducting pad. A coolant flow channel can also be arranged in the bottom plate of the high-voltage control box below the heat-conducting pad. In addition, the above heat dissipation method needs to consider the insulation performance of the high-voltage control box. Usually, an insulating film is pasted above or below the heat-conducting pad to ensure the insulation performance of the high-voltage control box.

[0004] During the process of pasting the insulating film, it is inevitable to generate a certain number and size of bubbles, and the bubbles will have a certain negative impact on the natural heat dissipation or forced heat dissipation effect of the relay in the high-voltage control box. However, the current control of the bubble rate of the insulating film pasted on the heat-conducting pad is usually empirical, and the visual observation method is used to judge whether the number, size and location of the bubbles will seriously affect the heat dissipation performance of the relay in the high-voltage control box. Therefore, researchers hope to find out the relationship between the bubble rate and the temperature rise change of the key heat source relay in the high-voltage control box, providing a theoretical basis for the control of the bubble rate in the actual production of the high-voltage control box. Summary of the Invention

[0005] In view of this, the present invention proposes a method for controlling the bubble rate for the heat dissipation of a relay in a high-voltage control box, which is used to solve the problem that the current control of the bubble rate of the insulating film pasted on the heat-conducting pad is usually an empirical method, and the relationship between the bubble rate and the temperature rise change of the key heat source relay in the high-voltage control box is not pointed out.

[0006] The technical solution of the present invention is implemented as follows: The present invention provides a method for controlling the bubble rate for the heat dissipation of a relay in a high-voltage control box, including the following steps. Step 1, perform three-dimensional modeling on the high-voltage control box. Preset that when the bubbles are distributed to the position where the heat dissipation of the relay in the high-voltage control box is most weakened, simulate the temperature rise of the key heat source relay in the high-voltage control box when the bubble rate gradually increases through simulation means, and calculate and obtain the temperature rise change rate of the key heat source relay. Step 2, obtain the formula relationship between the bubble rate and the temperature rise change rate through mathematical fitting means. Step 3, obtain the temperature rise result of the key heat source relay of the actual product when the bubble rate is zero through a temperature rise experiment, and convert it through the formula obtained in Step 2 to obtain the temperature rise situation of the key heat source relay in the product under different bubble rates, and determine the bubble rate threshold of the product according to the temperature rise requirement of the product.

[0007] On the basis of the above technical solution, preferably, the high-voltage control box includes a box body, on the inner bottom surface of which a heat dissipation part is laid; a bus bar, arranged in the box body and closely attached to the heat dissipation part; a relay, arranged on the surface of the bus bar away from the heat dissipation part; a heat conduction pad, clamped between the bus bar and the heat dissipation part; wherein, the surface of the heat conduction pad in contact with the bus bar is the effective heat conduction area; the part where the relay is connected to the bus bar is the heat source area, and the heat source area is not in contact with the heat conduction pad; there are bubbles on the heat conduction pad. When the bubbles are distributed to the position where the heat dissipation of the relay in the high-voltage control box is most weakened, the bubbles are arranged around the heat source area as a bubble area, and the bubble rate = bubble area / effective heat conduction area.

[0008] More preferably, the width of the bubble area increases with the increase of the bubble rate.

[0009] More preferably, the change range of the bubble rate is from 0% to 40%.

[0010] More preferably, in Step 2, obtain the formula relationship between the bubble rate and the temperature rise change rate under the forced heat dissipation condition with a fixed heat dissipation efficiency of the heat dissipation part and the natural heat dissipation condition with a fixed ambient temperature respectively.

[0011] More preferably, when the bubble rate changes in the range of 0% to 10%, the formula relationship between the bubble rate and the temperature rise change rate under the forced heat dissipation condition is Y = 0.6792×X, and the formula relationship between the bubble rate and the temperature rise change rate under the natural heat dissipation condition is Y = 0.14037×X, where X represents the bubble rate and Y represents the temperature rise change rate of the heat source relay.

[0012] Further preferably, when the bubble rate varies in the range of 10% to 20%, the formula relationship between the bubble rate and the temperature rise change rate under forced heat dissipation conditions is Y = 0.3859×X + 0.02932, and the formula relationship between the bubble rate and the temperature rise change rate under natural heat dissipation conditions is Y = 0.1988×X - 0.005843.

[0013] Further preferably, when the bubble rate varies in the range of 20% to 30%, the formula relationship between the bubble rate and the temperature rise change rate under forced heat dissipation conditions is Y = 0.4855×X + 0.00941, and the formula relationship between the bubble rate and the temperature rise change rate under natural heat dissipation conditions is Y = 0.29173×X - 0.02442.

[0014] Further preferably, when the bubble rate varies in the range of 30% to 40%, the formula relationship between the bubble rate and the temperature rise change rate under forced heat dissipation conditions is Y = 1.0689×X - 0.16562, and the formula relationship between the bubble rate and the temperature rise change rate under natural heat dissipation conditions is Y = 0.31133×X - 0.03031.

[0015] Further preferably, in step three, the actual bubble rate of the product is obtained through three-dimensional modeling means, the maximum temperature rise of the key heat source relay of the product under the actual bubble rate is obtained by conversion according to the actual bubble rate of the product, and the bubble rate threshold of the product is set according to whether the maximum temperature rise of the relay under the bubble rate condition exceeds the limit working temperature of the relay.

[0016] The bubble rate control method for the relay heat dissipation of the high-voltage control box of the present invention has the following beneficial effects compared with the prior art:

[0017] (1) The present invention proposes the formula relationship between the bubble rate and the temperature rise change rate of the heat source relay, and obtains the temperature rise situation of the key heat source relay of the high-voltage control box under different bubble rates through the formula, so as to determine the bubble rate threshold of the high-voltage control box under the safety margin according to the actual temperature rise requirement of the product, so as to control the bubble rate of the high-voltage control box subsequently.

[0018] (2) The present invention provides theoretical data support for the bubble rate control of the high-voltage control box, and can relax the bubble rate control threshold of the high-voltage control box based on evidence, significantly reducing the production process cost; since it is extremely difficult to conduct temperature rise experiments at different bubble rates of the high-voltage control box, mainly because it is difficult to manufacture sample parts, a large number of sample parts are required, and the position, size, and quantity of the bubble rate are randomly distributed, and it is difficult to represent all the states of the product under the same bubble rate, while the present invention can replace the temperature rise experiments at different bubble rates, significantly reducing the verification cost of the bubble rate control threshold of the high-voltage control box. Description of the Drawings

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0020] Figure 1 It is a perspective view of the high-voltage control box of the present invention;

[0021] Figure 2 It is a top view of the high-voltage control box of the present invention;

[0022] Figure 3 It is a perspective view of the bus bar and the heat-conducting pad of the present invention;

[0023] Figure 4 It is a schematic diagram of the area where the bus bar of the present invention is in contact with the heat-conducting pad under the condition that the bubble rate is 10%;

[0024] Figure 5 It is a schematic diagram of the area where the bus bar of the present invention is in contact with the heat-conducting pad under the condition that the bubble rate is 20%;

[0025] Figure 6 It is a schematic diagram of the area where the bus bar of the present invention is in contact with the heat-conducting pad under the condition that the bubble rate is 30%;

[0026] Figure 7 It is a schematic diagram of the area where the bus bar of the present invention is in contact with the heat-conducting pad under the condition that the bubble rate is 40%;

[0027] Figure 8 It is a curve graph of the relationship between the bubble rate and the temperature rise change of the heat source relay of the present invention.

[0028] In the figure: 1. box body; 11. heat dissipation part; 2. bus bar; 3. relay; 4. heat-conducting pad; 401. effective heat-conducting area; 402. heat source area; 403. bubble area. Detailed implementation manners

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in combination with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0030] As Figure 8 shown, a method for controlling the bubble rate for the heat dissipation of the relay in the high-voltage control box of the present invention includes the following steps.

[0031] Step 1: Conduct three-dimensional modeling on the high-voltage control box. Preset that when the bubbles are distributed to the position where they can most weaken the heat dissipation of the relay 3 in the high-voltage control box, simulate the temperature increase of the key heat source relay 3 in the high-voltage control box when the bubble rate gradually increases through simulation means, and calculate and obtain the temperature rise change rate of the key heat source relay 3. The purpose of this step is to establish a three-dimensional model of a commercially available standard high-voltage control box of a certain model through three-dimensional modeling means, and simulate the bubble distribution under different bubble rates in the three-dimensional model of the high-voltage control box; then, based on the temperature rise test through simulation means, the temperature data and its change under a certain bubble rate of this model of high-voltage control box can be obtained, thus providing a data basis for establishing the formula relationship between the bubble rate and the temperature rise change rate in the follow-up.

[0032] Step 2: Obtain the formula relationship between the bubble rate and the temperature rise change rate through mathematical fitting means. Since the more bubbles remaining in the insulating film attached to the heat-conducting pad, the more it will hinder the heat conduction and heat dissipation effect of the heat source relay through the heat-conducting pad, so in principle, the higher the bubble rate, the more significant the temperature increase of the relay. Therefore, fundamentally speaking, the bubble rate and the temperature rise change rate show a linear relationship, that is, when the bubble rate gradually increases, the temperature rise change rate also gradually increases; however, the bubble rate has different gradient change ranges, and the present invention finds that within different gradient ranges of the bubble rate, the bubble rate and the temperature rise change rate will show different linear relationships.

[0033] Step 3: Obtain the temperature rise result of the key heat source relay 3 of the actual product when the bubble rate is zero through the temperature rise experiment, and obtain the temperature rise situation of the key heat source relay 3 in the product under different bubble rates through conversion using the formula obtained in Step 2, and determine the bubble rate threshold of the product according to the temperature rise requirement of the product. The purpose of the present invention is ultimately to reduce production costs. Therefore, it is necessary to find the bubble rate threshold within the safe range for this model of relay, so that the temperature rise situation of the heat source relay in the high-voltage control box with the bubble rate within this threshold range can be effectively controlled, and at the same time, the bubble rate of this model does not need to be reduced to an extremely low level, thus achieving the purpose of reducing production costs.

[0034] As Figure 1 shown, in combination with Figure 2 and Figure 3 , the high-voltage control box includes a box body 1, a bus bar 2, a relay 3, and a heat-conducting pad 4.

[0035] Among them, the box body 1 is usually made of insulating material to prevent electric leakage. A heat dissipation part 11 is laid on the inner bottom surface of the box body 1. Specifically, a heat dissipation cold plate can be laid on the inner bottom surface of the box body 1, or a liquid cooling flow channel component can be embedded in the bottom plate of the box body 1.

[0036] The bus bar 2 is arranged in the box body 1 and closely attached to the heat dissipation part 11. The bus bar 2 is a copper bar. The bus bar 2 has a raised structure, which is the installation position of the relay 3.

[0037] The relay 3 is arranged on the surface of the bus bar 2 away from the heat dissipation part 11. The relay 3 is a key heat source component for the high-voltage control box to generate heat. Therefore, the part where the relay 3 is connected to the bus bar 2 is the heat source area 402. The heat source area 402 has a raised structure and thus does not contact the heat conduction pad 4. On the one hand, the bus bar 2 conducts electricity from the relay 3 to the entire circuit, and on the other hand, it conducts and dissipates the heat generated by the relay 3 through heat conduction to prevent the operating temperature of the relay from exceeding the limit temperature it can withstand and causing damage.

[0038] The heat conduction pad 4 is clamped between the bus bar 2 and the heat dissipation part 11; the surface of the heat conduction pad 4 in contact with the bus bar 2 is the effective heat conduction area 401. The front and back sides of the effective heat conduction area 401 are respectively closely attached to the bus bar 2 and the heat dissipation part 11 for effective heat conduction. Insulating films are pasted on both the front and back sides of the heat conduction pad 4. Therefore, countless small and large air bubbles will be formed between the insulating film and the heat conduction pad 4. These air bubbles are equivalent to blocking the heat conduction between the bus bar 2 and the heat conduction pad 4 and between the heat conduction pad 4 and the heat dissipation part 11. Therefore, the air bubbles will have an adverse impact on the heat dissipation of the relay. In actual situations, the positions, sizes, shapes, and numbers of the air bubbles on the heat conduction pad 4 are randomly distributed. It is difficult to evaluate the influence of different air bubbles at different positions on the heat conduction efficiency of the heat conduction pad 4. However, the situation where the air bubbles are distributed to the position that can most weaken the heat dissipation of the relay 3 in the high-voltage control box can be preset. In this case, the air bubbles are arranged around the heat source area 402 as the air bubble area 403, that is, all the air bubbles form a ring and surround the direct connection part of the relay 3 and the bus bar 2, so that the heat generated by the relay 3 is fully blocked by the air bubbles from the beginning of conduction to the bus bar 2. Therefore, the air bubble rate in the present invention refers to the air bubble rate in the most extreme case, and the air bubble rate = air bubble area 403 / effective heat conduction area 401.

[0039] In Figure 4 In a preferred embodiment shown, since in the extreme case, it can be regarded that the air bubbles are arranged around the heat source remainder 402, when the width of the air bubble area 403 increases, it means that the air bubble rate gradually increases.

[0040] In Figure 4 In a preferred embodiment shown, the change range of the air bubble rate is from 0% to 40%. The air bubble rate of the heat conduction pad 4 can be measured. In the experience of this field, products with an air bubble rate exceeding 40% are usually regarded as unqualified. Therefore, this application does not study the situation where the air bubble rate is greater than 40%.

[0041] In Figure 8In a preferred embodiment shown, in step two, the formula relationships between the bubble rate and the temperature rise change rate are obtained respectively under the forced heat dissipation condition with a fixed heat dissipation efficiency of the heat dissipation part 11 and under the natural heat dissipation condition with a fixed ambient temperature. The reason is that there are two heat dissipation situations for the relay in the working environment, namely natural heat dissipation and forced heat dissipation, and the working temperature of the relay must not exceed the limit temperature under both heat dissipation situations.

[0042] In Figures 4 to 7 In a preferred embodiment shown, taking a certain model of high-voltage control box as an example, the area of the effective heat conduction region 401 in this model of high-voltage control box is 11301.75 mm 2 , the perimeter of the heat source region 402 is 463.7 mm. Assuming the area of a single bubble is 10 mm 2 , the thickness of the bubble is 1 mm, and it is preset that there are six heat source regions 402 from P1 to P6 on the heat conduction pad 4. The data in Table 1 below can be obtained through the simulation in step one.

[0043] Table 1 Temperature Rise Table of High-Voltage Control Box

[0044]

[0045] Based on the data in Table 1, through mathematical fitting means, the formula relationships between the bubble rate and the temperature rise change rate under the forced heat dissipation condition and the formula relationships between the bubble rate and the temperature rise change rate under the natural heat dissipation condition can be obtained. Specifically, when the bubble rate varies in the range of 0% to 10%, the formula relationship between the bubble rate and the temperature rise change rate under the forced heat dissipation condition is Y = 0.6792×X, and the formula relationship between the bubble rate and the temperature rise change rate under the natural heat dissipation condition is Y = 0.14037×X.

[0046] When the bubble rate varies in the range of 10% to 20%, the formula relationship between the bubble rate and the temperature rise change rate under the forced heat dissipation condition is Y = 0.3859×X + 0.02932, and the formula relationship between the bubble rate and the temperature rise change rate under the natural heat dissipation condition is Y = 0.1988×X - 0.005843.

[0047] When the bubble rate varies in the range of 20% to 30%, the formula relationship between the bubble rate and the temperature rise change rate under the forced heat dissipation condition is Y = 0.4855×X + 0.00941, and the formula relationship between the bubble rate and the temperature rise change rate under the natural heat dissipation condition is Y = 0.29173×X - 0.02442.

[0048] When the bubble rate varies in the range of 30% to 40%, the formula relationship between the bubble rate and the temperature rise change rate under forced heat dissipation conditions is Y = 1.0689×X - 0.16562, and the formula relationship between the bubble rate and the temperature rise change rate under natural heat dissipation conditions is Y = 0.31133×X - 0.03031.

[0049] Among them, X represents the bubble rate, and Y represents the temperature rise change rate of the heat source relay 3. Through the above formula, the relay temperature rise data of this type of high-voltage control at different bubble rates can be converted and inversely deduced.

[0050] In Figure 8 In a preferred embodiment shown, in step three, the actual bubble rate of the product is obtained through three-dimensional modeling means, the maximum temperature rise of the key heat source relay 3 of the product at the actual bubble rate is obtained through conversion of the actual bubble rate of the product, and the bubble rate threshold of the product is set according to whether the maximum temperature rise of the relay 3 under this bubble rate condition exceeds the limit working temperature of the relay 3, so as to replace the current conventional temperature rise experiments at different bubble rates through the method of the present invention, and significantly reduce the verification cost of the bubble rate control threshold of the high-voltage control box.

[0051] The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for controlling the bubble rate of a high-voltage control box relay for heat dissipation, characterized in that: The following steps are involved: Step 1: Three-dimensional modeling of the high-voltage control box is performed, and when the bubbles are distributed to the position that can most weaken the heat dissipation of the high-voltage control box relay (3), the temperature rise of the key heat source relay (3) in the high-voltage control box is simulated by simulation means when the bubble rate gradually increases, and the temperature rise change rate of the key heat source relay (3) is calculated; Step 2, obtaining the formula relationship between the bubble rate and the temperature rise rate by mathematical fitting; Step three, obtaining the temperature rise result of the key heat source relay (3) of the actual product when the bubble rate is zero through a temperature rise experiment, and converting the temperature rise of the key heat source relay (3) in the product at different bubble rates through the formula obtained in step two, and determining the bubble rate threshold of the product according to the temperature rise requirement of the product; The high voltage control box comprises: The box body (1) has a heat dissipation portion (11) disposed on its inner bottom surface; A busbar (2) is arranged on the box body (1) and is closely attached to the heat dissipation portion (11); A relay (3) is arranged on a surface of the busbar (2) away from the heat dissipation portion (11); A thermal pad (4) is sandwiched between the bus bar (2) and the heat dissipation portion (11); Wherein, the surface of the thermal pad (4) in contact with the busbar (2) is an effective thermal conduction area (401); The portion where the relay (3) is connected to the busbar (2) is a heat source region (402), and the heat source region (402) is not in contact with the thermal pad (4); The heat conductive pad (4) has bubbles on it. When the bubbles are distributed to the position that can most weaken the heat dissipation of the high-voltage control box relay (3), the bubbles surround the heat source area (402) and are arranged as a bubble area (403). The bubble ratio = bubble area (403) / effective heat conductive area (401); The width of the bubble region (403) increases as the bubble rate increases.

2. A bubble rate control method for heat dissipation of a high-voltage control box relay according to claim 1, characterized in that: The bubble ratio varies in the range of 0% to 40%.

3. A bubble rate control method for heat dissipation of a high-voltage control box relay according to claim 2, characterized in that: In the second step, the formula relationship between the bubble rate and the temperature rise change rate under the forced heat dissipation condition with a fixed heat dissipation efficiency of the heat dissipation part (11) and the natural heat dissipation condition with a fixed ambient temperature is obtained respectively.

4. A bubble rate control method for heat dissipation of a high-voltage control box relay according to claim 3, characterized in that: When the bubble rate varies in the range of 0% to 10%, the formula relationship between the bubble rate and the temperature rise change rate under forced heat dissipation conditions is Y=0.6792×X, and the formula relationship between the bubble rate and the temperature rise change rate under natural heat dissipation conditions is Y=0.14037×X, wherein X represents the bubble rate and Y represents the temperature rise change rate of the heat source relay (3).

5. The method for controlling the bubble rate of heat dissipation of a high-voltage control box relay according to claim 4, characterized in that: When the bubble rate varies in the range of 10% to 20%, the formula relationship between the bubble rate and the temperature rise change rate under forced heat dissipation conditions is Y=0.3859×X+0.02932, and the formula relationship between the bubble rate and the temperature rise change rate under natural heat dissipation conditions is Y=0.1988×X-0.005843.

6. A bubble rate control method for heat dissipation of a high-voltage control box relay according to claim 5, characterized in that: When the bubble rate varies in the range of 20% to 30%, the formula relationship between the bubble rate and the temperature rise change rate under forced heat dissipation conditions is Y=0.4855×X+0.00941, and the formula relationship between the bubble rate and the temperature rise change rate under natural heat dissipation conditions is Y=0.29173×X-0.02442.

7. A bubble rate control method for heat dissipation of a high-voltage control box relay according to claim 6, characterized in that: When the bubble rate varies in the range of 30% to 40%, the formula relationship between the bubble rate and the temperature rise change rate under forced heat dissipation conditions is Y=1.0689×X-0.16562, and the formula relationship between the bubble rate and the temperature rise change rate under natural heat dissipation conditions is Y=0.31133×X-0.03031.

8. The method for controlling the bubble rate of heat dissipation of a high-voltage control box relay according to claim 3, characterized in that: In step three, the actual bubble rate of the product is obtained by means of three-dimensional modeling, and the maximum rising temperature of the key heat source relay (3) of the product under the actual bubble rate is obtained by converting the actual bubble rate of the product. The bubble rate threshold of the product is set according to whether the maximum rising temperature of the relay (3) under the bubble rate condition exceeds the limit operating temperature of the relay (3).

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