KR20210091107A - Method of calculating cooling performance of motor controller cooling apparatus of water cooling type - Google Patents

Abstract

The present invention proposes a method of calculating a cooling performance index in accordance with the shape of a coolant flow path using a water-cooled cooling device for effective cooling of a driving motor controller of an electric vehicle and a 1D simulation tool. To this end, a metal PCB for cooling a heat generating element for motor control in the motor controller is installed, and a heat sink having a concave cooling channel forming the coolant flow path is in direct contact with the metal PCB to configure the motor controller cooling device. In order to calculate the cooling performance of the cooling device of the above configuration, the method comprises: an FE modeling process for calculating the temperature distribution of components and a discretization process for identifying the flow characteristics for each channel of the coolant flow path; a heat transfer coefficient selection process in accordance with the material and temperature characteristics of each part in the 1D model derived from the above process; and a process of deriving cooling performance from the above process.

Description

{Method of calculating cooling performance of motor controller cooling apparatus of water cooling type}

The present invention relates to a method for calculating the cooling performance of a water-cooled cooling device for a drive motor controller for an electric vehicle, such as an electric two-wheeled vehicle.

Drive motors of electric vehicles, including electric two-wheeled vehicles, control their rotational speed and torque through a separate motor controller. The motor controller receives power from the battery to control the motor, and the temperature around the circuit rises due to a heating element such as an IGBT in the control circuit. Since the motor controller is composed of a number of power parts and is located in a space sealed by a housing or cover for watertightness with the outside, it has no choice but to generate heat, and therefore a cooling structure must be applied accordingly.

There are two types of cooling methods: air cooling and water cooling. In the case of air cooling, a number of heat dissipation fins are installed on the heat sink to maximize the heat dissipation area to improve cooling efficiency, and heat is dissipated by conduction and convection heat transfer. It has a structure that installs a heat sink nearby and dissipates heat through the coolant flow path.

In the case of the air-cooling type of the prior art, although the cooling structure is simple, it is difficult to control the temperature of the heating element due to natural and forced convection by the heat-dissipating fins. In the water cooling type, a heat sink must be installed locally for cooling a specific heating element, and an unavoidable air layer is formed between the heat sink to which the heat sink is attached and the main PCB, so that the heat transfer effect by this air layer affects the temperature control and cooling performance of the heating element. may have an adverse effect.

The conventional cooling method of a motor controller for a two-wheeled vehicle is mainly an air cooling type. That is, the heating element located in the circuit unit is cooled in the manner of conduction and convective heat transfer by the heat sink and the heat dissipation fins located on the heat sink. As mentioned above, this air cooling method has a simple cooling structure because there is no medium such as cooling water in the water cooling method, but is disadvantageous in terms of temperature control and cooling efficiency.

The present invention proposes a water-cooled cooling device for effective cooling of a driving motor controller of an electric vehicle, and uses a 1D simulation tool to calculate the cooling performance of the device. The purpose is to quantitatively compare the amount of pressure drop, etc.) to derive the optimal coolant flow path shape.

In order to solve the above problems, according to the present invention, there is provided a structure capable of directly cooling a heating element on a main PCB by deleting an unnecessary air layer and a heat sink in the motor controller structure, and using 1D simulation to determine the shape of the coolant flow path. A method for calculating quantitative cooling performance by diversifying is provided.

To this end, a metal PCB for cooling the motor control heating element in the motor controller is installed, and a heat sink with a cooling channel concave forming a cooling water flow path is in direct contact with the metal PCB to configure the motor controller cooling device. In order to calculate the cooling performance of the cooling device of the configuration, the FE modeling process for calculating the temperature distribution of the component parts and the discretization process for identifying the flow rate characteristics for each channel of the cooling water flow path; A heat transfer coefficient selection process according to the material and temperature characteristics of each part in the 1D model derived from the above process; and deriving cooling performance from the above process.

The configuration and operation of the present invention introduced above will become clearer through specific embodiments described later with drawings.

According to the present invention, in configuring the cooling device of the motor controller, the heat sink is eliminated and the heat sink is removed, unlike the conventional water cooling device using a protruding shape such as a heat sink, and the heat sink having the cooling water flow path is directly contacted with the PCB where the heating element is located. efficiency can be increased. In addition, the cooling performance can be easily calculated by quantitatively comparing the cooling performance index (inlet/outlet temperature difference, pressure drop, etc.) according to the shape of the coolant flow path of the water-cooled cooling device of the motor controller.

1 is a structural diagram of a water-cooled cooling device of a conventional motor controller.
2 is a conceptual diagram of a structure of a water-cooled cooling device for a motor controller according to the present invention.
3 is an exploded view of an embodiment of the motor controller cooling apparatus of FIG. 2 .
4 is a flowchart of a cooling performance calculation process in which 1D simulation is applied to the water-cooled motor controller cooling device.
5 is an exemplary view of the FE model of the housing.
6 is an exemplary diagram of a discretization model of a cooling water flow path.
7A, 7B, and 7C are diagrams illustrating various embodiments of the coolant flow path 30 formed in the heat sink 26 .
8 shows the Reynolds number simulation results for CASE#1, CASE#2, and CASE#3 of FIGS. 7a to 7c.
9A, 9B, and 9C show simulation results of the differential pressure at the inlet/outlet end of the cooling water and the temperature at the outlet end.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the detailed description in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in a variety of different forms, only this embodiment allows the disclosure of the present invention to be complete, and those of ordinary skill in the art to which the present invention pertains. It is provided to fully inform the person of the scope of the invention, and the present invention is defined by the description of the claims. On the other hand, the terms used herein are for the purpose of describing the embodiment, not intended to limit the present invention. As used herein, the singular also includes the plural unless specifically stated otherwise in the phrase. As used herein, 'comprise' or 'comprising' refers to the presence or absence of one or more other components, steps, operations and/or elements other than the stated elements, steps, acts and/or elements. addition is not excluded.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In adding reference numerals to the components of each drawing, the same components are given the same reference numerals as much as possible even though they are shown in different drawings, and in explaining the present invention, detailed descriptions of related known components or functions In the case where the gist of the present invention may be obscured, the detailed description thereof will be omitted.

1 is a structural diagram of a water-cooled cooling device of a conventional motor controller.

Thermal grease 14 is applied to the main PCB 10 for cooling the FET 12 , which is a power device mounted on the main PCB 10 , and a heat sink 16 is installed. The heat sink 16 is attached to a heat sink 18 having a relatively large area, such as a controller housing. Finally, the main PCB 10 and the heat sink 18 are fastened with a screw 19 . A cooling water flow path 20 is formed in the heat sink 18, and cooling water flows through this flow path. At this time, since a number of layers are interposed between the heat sink 18 and the main PCB 10, an unavoidable air layer is formed in these several layers, and the temperature control and cooling performance of the FET 12 are affected by heat loss due to the air layer. receive

2 is a conceptual diagram of a structure of a cooling device for a motor controller subject to a method according to the present invention. What is different from the prior art is that the material of the PCB 22 on which the heating element 24 (eg, FET, IGBT, etc.) is mounted is replaced with FR-4, which is a conventional phenol or epoxy substrate material, and the coolant is directly used on the PCB. Substitute a metal material (eg, AL5754) to cool the heating element including the PCB in contact with the 22, and the PCB 22 for cooling the heating element 24 mounted on the PCB 22 ) and the heat sink 26, there is no protruding shape (eg, a heat sink) for thermal conduction cooling, and therefore there is no unnecessary air layer therebetween. The heat sink 26 is directly brought into contact with the metal PCB 22 on which the heating element 24 is mounted without a heat sink, and the heat sink 26 is closely coupled with the screw 28 . A plurality of grooves are formed in the heat sink 26 to form a space between the metal PCB 22 and the heat sink. This space becomes the cooling water flow path 30 .

3 is an exploded view of the structure of one embodiment of the motor controller cooling apparatus of FIG. 2 .

Heating elements 24 are mounted on the metal PCB 22 , and a heat sink 26 is attached to the opposite side of the metal PCB 22 on which the heating element 24 is mounted. The controller housing 36 is positioned on the side of the metal PCB 22 on which the heating element 24 is mounted, and is fastened together with the assembly of the metal PCB 22 and the heat sink 26 using a screw 28 .

A cooling water flow path 30 is formed on the heat sink 26 to occupy the entire area of the heat sink, and cooling water is supplied from the cooling inlet 32 at the front end of the cooling water flow path 30 to the cooling water outlet 34 at the end of the cooling water flow path 30 . The cooling water was allowed to uniformly cool the entire metal PCB 22 by flowing it.

Various embodiments of the coolant flow path 30 formed in the heat sink 26 are shown in FIGS. 7A, 7B, and 7C (CASE#1, CASE#2, and CASE#3, respectively).

In case of CASE #1, the cooling water introduced into the inlet is simultaneously distributed through 10 flow pipes, that is, channels 1 to 10, and discharged toward the outlet. 50°C marked on the inlet and 57°C marked on the outlet are exemplary, and the cooling water entering the cooling water flow path 30 is heat-exchanged while cooling the metal PCB 22 and the temperature increases when exiting the outlet.

In case of CASE#2, the channels are composed of 2 groups of 5 each. Cooling water flows into the first group (1~5) at the same time, and the cooling water that comes out at the same time through this group is the second group (6~10) ) and simultaneously discharged from this group toward the outlet.

In case of CASE#3, a total of 9 channels are composed of 3 groups of 3 each. Cooling water flows into the first group (1~3) at the same time, and the cooling water that comes out simultaneously through this group flows into the second group (4~ 6) and the cooling water from this group simultaneously flows into the last third group (7~9) and simultaneously discharges toward the outlet.

The channel cross-section of the cooling water passage 30 is rectangular, and the cross-sectional size of each channel is formed to be 8 cm in width and 3 cm in length.

The above-mentioned shape of the coolant flow path and the cross-sectional shape and size of the channel are exemplary, and may be arbitrarily designed by those skilled in the art according to various conditions or requirements.

4 shows a cooling performance calculation process by applying 1D simulation to the above-described motor controller cooling device. The following cooling performance calculation process may be performed by a cooling performance calculation system constructed by a computer to calculate cooling performance.

110: preprocessing operation

In this process, a 1D model of the cooling device, that is, an FE model of the housing 36 and a discretized model of the coolant flow path 30 are generated, and a thermal mass of the heating element is generated. In order to calculate the thermal mass of the heating element, position information on the PCB for each heating element and the amount of heat generated by the heating element are required. In this embodiment, it was assumed that the heating value of the heating element = 50 W/EA, and the thermal mass was generated.

5 is an exemplary view of a housing FE model generated in the pretreatment operation, and FIG. 6 is an exemplary view of a discretization model of a coolant flow path.

120: heat transfer mode definition

Select the convective (or conduction) heat transfer coefficient between components. Here, the heat transfer coefficient is selected according to the material and temperature of each component. Then, the heat mass generated in step 110 is applied (in this embodiment, location information and heat amount (50W/EA) on the PCB for each heat generating element are input). The heat transfer mode is defined by the above heat transfer coefficient and heat mass.

In this case, when the heat transfer mode is defined, the process of inputting the vehicle driving condition in step 130 may be accompanied.

130: vehicle driving condition input

In order to reflect vehicle driving conditions, eg, vehicle speed and ambient temperature, when defining the heat transfer mode in step 120 , the cooling performance calculation system receives the input vehicle driving conditions. This process is to consider the amount of heat lost by heat transfer from the motor controller to the atmosphere.

140: system flow definition

The system flow rate is the required flow rate value calculated through the entire vehicle system analysis. In this example, it was defined as 6.8L/min.

150: derived cooling performance

The derived cooling performance index includes the temperature difference between the inlet and outlet ends, the amount of pressure drop, the temperature distribution of the heat sink and the housing, and the amount of heat absorbed by the cooling water. Here, the cooling performance is derived for each shape of the cooling water flow path.

Hereinafter, the cooling performance analysis results derived through the above process will be described.

- Flow rate value flowing through each channel for each shape of the coolant flow path

The measurement of the flow rate was performed for three types of cooling water flow paths, that is, CASE#1 of FIG. 7A, CASE#2 of FIG. 7B, and CASE#3 of FIG. 7C. The average flow rate value for the coolant flow path type of CASE#1 of FIG. 7A is in Table 1 below, the average flow rate value for the cooling water flow path type of CASE#2 of FIG. 7B is in Table 2, and the cooling water flow path of CASE#3 of FIG. 7C is shown in Table 1 below. The average flow rate values for the shapes are shown in Table 3.

The cooling performance is advantageous as the flow rate flowing through each channel of the flow path increases. When the flow path shape is divided into three specifications as above and the same system flow rate of 6.8L/min is applied, the flow rate value of CASE#3 is the largest and it is predicted to show the best cooling performance.

In the flow path shape of CASE#3, the cooling water flowing in from the inlet is concentrated in 3 channels out of 10 channels, and it is bent twice in a U shape, so that an average of 36g/s of cooling water flows, whereas CASE#2 and CASE In the case of #1, since the coolant introduced into the inlet is distributed over 5 to 10 wide channels at the same time and flows, the pressure of the coolant is lower than that of CASE#3 and the flow rate is reduced, so the flow rate through the channel is 2/3 compared to CASE#3 will be reduced to 1/3.

- Reynolds Number of coolant

The flow pattern of the coolant is defined by the Reynolds number, which is the ratio of the viscous and inertial forces of the fluid. In a laminar flow with a low flow velocity, only conduction of the coolant flow is performed, and in a turbulent flow with a high flow velocity, conduction and convection occur simultaneously, improving cooling performance. These cooling water flow patterns are shown in Table 4.

The flow path shape of CASE #3 has a Reynolds number of 3,690, which corresponds to turbulent flow in Table 4. Compared to CASE#1 of laminar flow and CASE#2, which is the boundary of turbulent flow, it can be seen that the cooling performance of CASE#3 specification, which facilitates heat transfer (conduction and convection) of the cooling water passage, is the best. Therefore, when the diameters of the cooling channels are the same, it is advantageous to the cooling performance to secure a large flow rate as mentioned above.

8 shows the Reynolds number simulation results of CASE#1, CASE#2, and CASE#3.

- Differential pressure at the inlet and outlet of cooling water and temperature at the outlet

The cooling performance is determined by how much heat transferred from the heat generating element has been subtracted from the cooling water flowing through the flow path, and the outlet temperature is an indicator of the cooling performance.

9A, 9B, and 9C show simulation results of the differential pressure at the inlet/outlet end of the cooling water and the temperature at the outlet end. In each result graph, curves a, b, c, d, and e show the change of the outlet temperature when the differential pressure at the coolant inlet and outlet is ΔP=5kPa, ΔP=10kPa, ΔP=15kPa, ΔP=20kPa, ΔP=25kPa, respectively. indicates. As a result of calculating the temperature at the outlet end while increasing the differential pressure at the inlet and outlet ends in 5 kPa increments from 5 kPa to 25 kPa, the outlet temperature of CASE # 3 shows the highest temperature in all differential pressure standards. It is expected to show the best cooling performance. In the case of the coolant flow path shape of CASE#3, it can be seen that the temperature difference at the outlet end with time is the highest from ΔP=5kPa to ΔT=38℃, and the lowest from ΔP=25kPa to ΔT=16℃.

As mentioned above, although the configuration of the present invention has been described in detail through preferred embodiments of the present invention, those of ordinary skill in the art to which the present invention pertains will appreciate the content disclosed in the present specification without changing the technical spirit or essential features of the present invention It will be understood that the present invention may be implemented in a specific form other than the above. It should be understood that the embodiments described above are illustrative in all respects and not restrictive. The scope of protection of the present invention is defined by the following claims rather than the above detailed description, and all changes or modifications derived from the claims and their equivalent concepts should be construed as being included in the technical scope of the present invention. .

Claims (9)

a heat sink for cooling the heating element mounted on the PCB; a cooling water passage formed in the heat sink; and a method performed by a cooling performance calculation system constructed by a computer to calculate cooling performance of a water-cooled cooling device of a motor controller including a housing assembled to be in contact with the heat sink,
a pre-processing step of generating, by the cooling performance calculation system, a 1D model of the cooling device and generating a thermal mass of the heating element;
selecting, by the cooling performance calculation system, a heat transfer coefficient of the heat sink and the PCB of the cooling device, and defining a heat transfer mode using the heat transfer coefficient and the heat mass generated in the pre-processing step;
defining, by the cooling performance calculation system, a system flow rate that is a required flow rate value of the cooling device; and
Deriving, by the cooling performance calculation system, cooling performance using the defined heat transfer mode and system flow rate
containing A method of calculating the cooling performance of a water-cooled cooling device of a motor controller. According to claim 1, wherein the 1D model of the cooling device generated in the pre-processing step is
A method for calculating cooling performance of a water-cooled cooling device for a motor controller, including a FE model of the housing and a discrete model of the cooling water flow path. The cooling performance of the water-cooled cooling device of the motor controller according to claim 1, wherein position information on the PCB for each heating element and the amount of heat generated by the heating element are used to generate the thermal mass of the heating element generated in the pre-processing step. calculation method. According to claim 1, wherein the heat transfer coefficient generated in the step of defining the heat transfer mode is
A method for calculating cooling performance of a water-cooled cooling device for a motor controller, including a convective heat transfer coefficient and a conduction heat transfer coefficient of the cooling device. The method of claim 1 , wherein the defining the heat transfer mode comprises:
Water-cooling cooling of the motor controller further comprising the step of receiving, by the cooling performance calculation system, an input of vehicle driving conditions including vehicle speed and ambient temperature in order to consider the amount of heat lost due to heat transfer from the motor controller to the atmosphere How to calculate the cooling performance of the device. The method of claim 1, wherein in the step of defining the system flow rate
The system flow rate is calculated using a system analysis of the entire vehicle, the cooling performance calculation method of the water-cooled cooling device of the motor controller. The cooling of the water-cooled cooling device of the motor controller according to claim 1, wherein the cooling performance index derived in the cooling performance deriving step includes at least one of an inlet/outlet temperature difference, a pressure drop, a temperature distribution of a heat sink and a housing, and an amount of heat absorbed by the cooling water. Performance calculation method. According to claim 1, wherein in the step of deriving the cooling performance, the cooling performance is derived for each shape of the cooling water flow path,
Here, the shape of the coolant flow path is
a cooling inlet located at the front end of the cooling water passage through which cooling water is introduced; a cooling water outlet located at the end of the cooling water passage through which the cooling water is discharged; and a plurality of channels discharged to the cooling outlet after cooling water introduced through the cooling inlet passes and cools the PCB, and after the cooling water introduced through the cooling inlet is simultaneously introduced through the plurality of channels, the After cooling the PCB, the cooling performance calculation method of the water-cooled cooling device of the motor controller, characterized in that it is configured to be discharged from the plurality of channels through the cooling outlet. According to claim 1, wherein in the step of deriving the cooling performance, the cooling performance is derived for each shape of the cooling water flow path,
Here, the shape of the coolant flow path is
a cooling inlet located at the front end of the cooling water passage through which cooling water is introduced; a cooling water outlet located at the end of the cooling water passage through which the cooling water is discharged; and a plurality of channels discharged to the cooling water outlet after cooling the PCB through the cooling water flowing in through the cooling inlet,
The plurality of channels includes at least one group, and the cooling water introduced through the cooling inlet simultaneously flows into a first group and the cooling water simultaneously flows through this group into the next group at the same time in this group. Cooling performance calculation method of the water-cooled cooling device of the motor controller, characterized in that it is configured to be discharged to the outlet.

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