Method for realizing heat dissipation of MOS (Metal Oxide Semiconductor) tube based on metal heat-conducting plate

Abstract

The invention relates to a method for realizing heat dissipation of an MOS (Metal Oxide Semiconductor) tube based on a metal heat-conducting plate, and belongs to the technical field of aviation electrics. A metal heat dissipation window is arranged on one side of a drain electrode of a power MOS tube, when the MOS tube is welded on a printed board, the metal heat dissipation window faces upwards, meanwhile, a metal heat conduction plate is designed to transmit heat of the MOS tube to a product case structure, and rapid heat dissipation of the multiple MOS tubes is achieved through the surface area of the case structure. The design is good in heat dissipation effect and simple in installation and electric fitting. The design is applied to the 270V driving control circuit of the power supply unit, the heat dissipation effect is good, the reliability is high, and the popularization and use value is very good.

Description

Technical Field

[0001] The invention belongs to the field of aviation electrical technology, and in particular relates to a method for realizing heat dissipation of MOS tubes based on a metal heat conducting plate. Background Art

[0002] The main power supply of aircraft is gradually developing towards DC high voltage. By increasing the driving power supply voltage and reducing the power current, the specifications of the cables on board can be reduced, so as to achieve the purpose of reducing the weight of the aircraft. The main power supply of aircraft has been upgraded from AC115V in the past to DC270V now, and will be upgraded to DC540V in the future. The 270V power drive uses power MOS tube as a switching device. The power MOS tube has a drain-source on-state resistance, and the larger the drain-source voltage, the larger the drain-source on-state resistance of the MOS tube. When the MOS tube is turned on, the conducting power will cause the tube shell to generate a large amount of heat. The airborne high-voltage and high-power switch needs to consider the heat dissipation of the drive module itself according to the high-altitude environment. To realize the control of MOS tube high-voltage and high-power switch, first, it is necessary to reduce the thermal power consumption of the product and reduce the conduction power of the MOS tube. The method adopted is to connect multiple MOS tubes in parallel; second, the product needs to optimize the active heat dissipation capability. The method adopted is to design a structural heat sink to export the heat of the MOS tube body in time. Summary of the invention

[0003] 1. Technical issues to be resolved

[0004] The technical problem to be solved by the present invention is to solve the heat dissipation problem of a high-voltage and high-power switch drive module in a small space and a closed chassis environment.

[0005] (II) Technical solution

[0006] In order to solve the above technical problems, the present invention provides a method for realizing heat dissipation of MOS tubes based on a metal heat conducting plate. In the method, a metal heat conducting plate is designed to connect the metal heat dissipation window on the tube shell of the MOS tube and the chassis of the equipment, and the metal heat conducting plate is in contact with the chassis, so that the surface area of ​​the chassis is used for heat exchange;

[0007] The metal heat conducting plate is a cubic structure and is made of aluminum alloy. It is processed according to the size of the MOS tube that needs to dissipate heat and the distance between the MOS tube and the upper cover plate of the chassis after electrical installation. A mechanical countersunk hole is processed at the position corresponding to the MOS tube mounting hole. After being fixed with a countersunk screw, there is no protrusion on the surface of the metal heat conducting plate. The metal heat dissipation window of the MOS tube is connected to the drain, and the metal heat conducting plate is subjected to insulation oxidation treatment.

[0008] Preferably, in the method, the pins of the MOS tube in the TO-247 package are also bent in reverse and welded on the printed circuit board, so that the metal heat dissipation window on the MOS tube shell faces upward and is welded on the reverse side. After the MOS tube is fixed to the printed circuit board by the tooling, it is bent in the same direction, and the metal heat conducting plate, the MOS tube and the printed circuit board are fixed by screws. After fixation, the tooling is removed, and then the pins of the MOS tube are fixed by welding.

[0009] Preferably, in the method, a heat dissipation tooth of a certain area is designed on the outer surface of the upper cover plate of the chassis on one side of the MOS tube, so as to facilitate heat exchange after the heat of the MOS tube is conducted out through the metal heat conducting plate.

[0010] Preferably, in the method, a thermally conductive insulating pad is also designed between the upper cover plate of the chassis and the metal heat conductive plate to cooperate with the metal heat conductive plate to increase the insulation and thermal conductivity of the MOS tube and the chassis.

[0011] Preferably, in the method, multiple MOS tubes are arranged in parallel.

[0012] Preferably, the MOS tube is a high-power MOS tube switch circuit.

[0013] Preferably, the method is applied in a 270V drive control circuit of a power supply unit.

[0014] The invention also provides a heat dissipation device designed and implemented based on the method.

[0015] (III) Beneficial effects

[0016] In the present invention, a metal heat dissipation window is arranged on one side of the drain of the power MOS tube. When the MOS tube is welded on the printed circuit board, the metal heat dissipation window is facing upwards. At the same time, a metal heat conduction plate is designed to transfer the heat of the MOS tube to the product chassis structure, and multiple MOS tubes are quickly cooled through the surface area of ​​the chassis structure. The design has good heat dissipation effect and is simple to install and install. The design has been applied to the 270V drive control circuit of the power supply unit, has good heat dissipation effect, high reliability, and has great promotion and use value. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is N-channel MOS tube LB65N030J;

[0018] Figure 2 This is a schematic diagram of the power printed circuit board;

[0019] Figure 3 This is a schematic diagram of the metal heat conducting plate (heat sink) and the upper cover of the chassis;

[0020] Figure 4 This is a schematic diagram of the heat dissipation teeth on the chassis cover. Among them, 1 MOS tube heat dissipation window; 2 homemade metal heat sink; 3 power bus bar (copper core tinned); 4 MOS tube reverse side welding (with the heat dissipation window facing upwards). DETAILED DESCRIPTION

[0021] In order to make the purpose, content and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below in conjunction with the drawings and examples.

[0022] The requirements for the weight of aviation airborne products are getting higher and higher. At the same time, in order to improve the maintainability of airborne equipment, more standardized requirements are put forward for the structural design of airborne equipment in new large airborne platforms, such as "HB7390-1996 Civil Aircraft Electronic Equipment Interface Requirements", "GJB441-1988 Airborne Electronic Equipment Chassis, Installation Form and Basic Dimensions of Mounting Frames" and other standards to adapt to the field replaceable units and system modular equipment in the aircraft equipment compartment. Based on the design method of the MOS tube heat sink of the metal heat conducting plate, the product adopts the standard size chassis design of 2MCU in the LRU design method that can be quickly disassembled. The MCU is a rectangular block with a fixed height and length. The size (volume) of the LRU changes according to the increase of the standard unit width of the chassis. The width of 2MCU is 57.2mm. The power consumption of airborne equipment is getting larger and larger. The voltage of a distribution device channel is 270V, the rated current is 50A, and the maximum startup current can even reach 90A.

[0023] The DC270V power drive circuit of the power distribution device uses N-channel MOS tube LB65N030J, TO-247 package, and device height 21mm. The MOS tube body is designed with a heat dissipation window. In general power supply equipment, the MOS tube is vertically installed, and the tube body is designed with a heat sink, and the heat dissipation design is carried out through the air duct. The vertical installation design of the MOS tube requires a large space and has poor vibration resistance; or an aluminum substrate is used to make a printed circuit board, and the heat is dissipated through the aluminum substrate, but the aluminum substrate can only be used to mount devices on the surface, which has certain limitations.

[0024] Airborne equipment requires a sealed chassis design due to the high-altitude environment, and the MOS tube heat dissipation design needs to be carried out based on the airborne equipment chassis sealing and vibration resistance requirements.

[0025] To this end, the present invention provides a method for realizing MOS tube heat dissipation based on a metal heat conducting plate, which is a heat dissipation method suitable for high-power MOS tube switch circuits. Figure 1 Design of medium and large power MOS tubes. Figure 1 It is a high-power N-channel MOS tube LB65N030J with a drain-source on-state resistance of 26mΩ. When the rated current is 50A, the tube body conduction power is 65W.

[0026] The design of the present invention includes three parts: the metal heat-conducting plate itself and the corresponding design of the MOS tube electrical equipment and chassis structure. The heat dissipation window of the MOS tube and the equipment chassis are tightly connected through the metal heat-conducting plate, so as to realize heat transfer by utilizing the chassis area. The whole design needs to consider the consistency of high-voltage insulation processing and multi-channel MOS tube electrical equipment process.

[0027] The metal heat conducting plate is a cubic structure. Figure 3 Schematic diagram of the design of the metal heat conducting plate designed for the MOS tube radiator. The metal heat conducting plate is made of aluminum alloy and is processed according to the size of the MOS tube module circuit that needs to dissipate heat and the distance between the MOS tube and the upper cover of the chassis after electrical installation. Mechanical countersunk holes are processed at the positions of the MOS tube mounting holes (there is no protrusion on the surface of the metal heat conducting plate after fixing with countersunk screws). Since the metal heat dissipation window of the MOS tube is connected to the drain, the metal heat conducting plate needs to be insulated and oxidized.

[0028] Furthermore, the pins of the MOS tube in the TO-247 package are bent in reverse and welded on the printed circuit board, so that the metal heat dissipation window on the tube shell of the MOS tube faces upward and is welded on the reverse side. Figure 2 This is a schematic diagram of the MOS tube printed circuit board after welding. The MOS tube has three pins: source, gate, and drain. After the MOS tube is fixed to the printed circuit board through the tooling, it is bent in the same direction, and the metal heat conductive plate, MOS tube, and printed circuit board are fixed by screws. After fixation, the tooling is removed, and then the pins of the MOS tube are welded and fixed. This can prevent the pins of the MOS tube from being stressed due to welding first and then screwing.

[0029] The metal heat conductive plate needs to be in contact with the product chassis to utilize the chassis surface area for heat exchange. Figure 3 This is a schematic diagram of the upper cover of the product chassis that uses this design. The outer surface of the upper cover of the chassis on one side of the MOS tube is designed with large-area heat dissipation teeth, which is conducive to quickly realizing heat exchange after the heat of the MOS tube is discharged through the metal heat conduction plate. Figure 4 This is a schematic diagram of the heat dissipation teeth on the upper cover of the chassis. A thermal insulation pad is also designed between the upper cover of the chassis and the metal heat conductive plate to increase the insulation and thermal conductivity between the MOS tube and the chassis. The entire structure can achieve good heat dissipation performance with the metal heat conductive plate.

[0030] The present invention reduces the power consumption of the power switch driving module itself by connecting MOS tubes in parallel, and designs a metal heat conducting plate according to the structural characteristics of the chassis to increase the heat dissipation effect of the product, thereby enabling the application of high-voltage and high-power driving modules in airborne equipment.

[0031] The technical solution of the present invention will be further described in detail below with reference to an example of a power supply unit:

[0032] 1) Multiple MOS tubes are connected in parallel to reduce the power consumption of the drive module

[0033] Taking the selected N-channel MOS tube LB65N030J as an example, the drain-source on-state resistance is 26mΩ. When the rated current is 50A, the tube body conduction power is:

[0034] P1=I 2 R = 50A × 50A × 26mΩ = 65W;

[0035] The 270V power switch control is realized by connecting 4 MOS tubes in parallel. When the rated current is 50A, the conduction power is:

[0036] P2=I 2 R=50A×50A×26M / 4=16.25W;

[0037] 2) Add metal heat conduction plate design

[0038] Under normal temperature conditions, the two designs of the power supply unit were loaded and tested. After the product started to work stably after adding the radiator, the temperature rise measured by a thermal imager was 30°C lower than that of the corresponding design without adding the radiator.

[0039] It can be seen that the present invention uses a metal heat dissipation window to be set on the drain side of the power MOS tube. When the MOS tube is welded on the printed circuit board, the metal heat dissipation window is facing upwards. At the same time, a metal heat conductive plate is designed to transfer the heat of the MOS tube to the product chassis structure, and multiple MOS tubes can quickly dissipate heat through the surface area of ​​the chassis structure. According to the above analysis, the design has good heat dissipation effect and is simple to install and install. In specific applications, it can be adjusted accordingly according to the structure of the airborne product. The design has been applied to the 270V drive control circuit of the power supply unit, with good heat dissipation effect and high reliability, and has great value for promotion and use.

[0040] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for realizing heat dissipation of MOS tube based on metal heat conducting plate, characterized in that: In this method, a metal heat-conducting plate is designed to connect the metal heat-dissipating window on the MOS tube shell and the chassis of the device, and the metal heat-conducting plate is in contact with the chassis, so that the surface area of ​​the chassis is used for heat exchange; The metal heat conducting plate is a cubic structure and is made of aluminum alloy. It is processed according to the size of the MOS tube that needs to dissipate heat and the distance between the MOS tube and the upper cover plate of the chassis after electrical installation. A mechanical countersunk hole is processed at the position corresponding to the MOS tube mounting hole. After being fixed with a countersunk screw, there is no protrusion on the surface of the metal heat conducting plate. The metal heat dissipation window of the MOS tube is connected to the drain, and the metal heat conducting plate is subjected to insulation oxidation treatment.

2. The method according to claim 1, characterized in that In this method, the pins of the MOS tube in the TO-247 package are also bent in reverse and welded on the printed circuit board, so that the metal heat dissipation window on the MOS tube shell faces upward and is welded on the reverse side. After the MOS tube is fixed to the printed circuit board through the tooling, it is bent in the same direction, and the metal heat conductive plate, MOS tube, and printed circuit board are fixed by screws. After fixation, the tooling is removed, and then the pins of the MOS tube are welded and fixed.

3. The method according to claim 2, characterized in that In this method, a heat dissipation tooth of a certain area is designed on the outer surface of the upper cover plate of the chassis on one side of the MOS tube, so as to facilitate heat exchange after the heat of the MOS tube is conducted out through the metal heat conducting plate.

4. The method according to claim 3, characterized in that In this method, a thermally conductive insulating pad is also designed between the upper cover plate of the chassis and the metal heat conductive plate, and cooperates with the metal heat conductive plate to increase the insulation and thermal conductivity of the MOS tube and the chassis.

5. The method according to claim 4, characterized in that In this method, multiple MOS tubes are connected in parallel.

6. The method according to claim 1, characterized in that The MOS tube is a high-power MOS tube switch circuit.

7. The method according to claim 1, characterized in that The method is applied in a 270V drive control circuit of a power supply unit.

8. The method according to claim 1, characterized in that The method is applied in the field of aviation electrical technology.

9. A heat dissipation device designed and implemented based on the method according to any one of claims 1 to 8.

10. The device according to claim 9, characterized in that For example, the device is used in the field of aviation electrical technology.

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