Motor driver

Abstract

The invention discloses a motor driver. The motor driver comprises a PCB (Printed Circuit Board) and a high-frequency capacitor bypass, the PCB comprises an electric control device; the electric control device is electrically connected with the motor through the high-frequency capacitor bypass; the working frequency of the high-frequency capacitor bypass is different from that of the motor; and the high-frequency capacitance bypass is used for filtering frequency multiplication interference of higher harmonics generated by the electric control device. According to the motor driver, the high-frequency capacitor bypass is arranged in the motor driver, so that frequency multiplication interference of higher harmonics generated by an electric control device can be effectively filtered out, the working frequency of the motor cannot be interfered due to the fact that the working frequency of the high-frequency capacitor bypass is different from that of the motor, and effective operation of the motor can be ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic products, and in particular to a motor driver. Background Art

[0002] In the prior art, electronic devices that include wireless communication functions and electronic control functions, electronic control devices such as MOSFET used to implement the electronic control function will cause strong interference to antennas such as LTE antennas, Bluetooth antennas, GPS antennas, etc. used for wireless communication functions, affecting the communication function. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a motor driver in order to overcome the above-mentioned defects in the prior art.

[0004] The present invention solves the above technical problems through the following technical solutions:

[0005] A motor driver comprises a PCB board and a high-frequency capacitor bypass; the PCB board comprises an electronic control device;

[0006] The electric control device is electrically connected to the motor through the high-frequency capacitor bypass; wherein the operating frequency of the high-frequency capacitor bypass is different from the operating frequency of the motor;

[0007] The high-frequency capacitor bypass is used to filter out the frequency-multiplied interference of the higher-order harmonics generated by the electronic control device.

[0008] Optionally, the high-frequency capacitor bypass includes at least one capacitor connected in parallel: an energy storage capacitor, an electrolytic capacitor, and a PCB plane capacitor; the electronic control device includes a switch tube;

[0009] The switch tube is connected to the electrolytic capacitor through the power copper foil of the PCB board.

[0010] Optionally, the PCB board is a multi-layer PCB board; the motor driver further includes electrical components; the electrical components include at least one of the following: a power module, a Bluetooth module, a GPS module, a GPS antenna, an audio module, an LTE module, an LTE antenna, and a Bluetooth antenna;

[0011] A ground copper foil is provided in the projection area of ​​the electrical component on the second layer of the PCB board.

[0012] Optionally, a gap between the ground copper foil provided in the projection area and the ground copper foil of the motor is greater than or equal to 0.127 mm.

[0013] Optionally, an antenna is provided on the first surface of the PCB board and / or an antenna is provided above the first surface;

[0014] The electric control device is arranged on the second surface of the PCB board and is welded on the PCB board.

[0015] Optionally, the motor driver further comprises a thermally conductive pad and a metal bottom shell for accommodating the electronic control device and the PCB board;

[0016] The electric control device is attached to the inner wall surface of the metal bottom shell through the heat conductive pad.

[0017] Optionally, the insulating shell of the switch tube included in the electronic control device is attached to the second surface of the PCB board;

[0018] The pins of the switch tube are connected to the PCB board.

[0019] Optionally, the motor driver further comprises a thermally conductive pad and a metal bottom shell for accommodating the switch tube and the PCB board;

[0020] The metal substrate of the switch tube is attached to the inner wall surface of the metal bottom shell through the heat conductive pad.

[0021] Optionally, the metal bottom shell includes a metal base and a metal rack, and the metal rack is integrally formed with the metal base;

[0022] And / or, the metal bottom shell is an aluminum die-casting shell or an extruded shell;

[0023] And / or, the metal bottom shell further includes a metal side shell and an insulating side shell, the metal base, the metal side shell and the insulating side shell form an accommodating space for accommodating the switch tube and the PCB board; and the metal side shell is arranged away from the antenna.

[0024] Optionally, a wiring is provided in a projection area of ​​the insulating shell attached to the second surface.

[0025] Optionally, the motor driver further comprises a driving component, the driving component is disposed on the second surface, and the driving component is electrically connected to the switch tube;

[0026] The driving component is used to drive the switching tube.

[0027] Optionally, the electronic control device is provided with a ground copper foil in a projection area of ​​the first surface.

[0028] Optionally, the thermally conductive gasket is an elastic thermally conductive gasket;

[0029] and / or, the compression of the thermally conductive gasket is greater than 10%;

[0030] And / or, the thermally conductive gasket is a thermally conductive silicone grease sheet or a thermally conductive silica gel sheet;

[0031] And / or, the thermal conductivity of the thermally conductive gasket is in the range of 0.8W / (m·K) to 6W / (m·K);

[0032] And / or, the hardness of the thermally conductive pad is in the range of 1 g / cm to 5 g / cm;

[0033] And / or, the thermal impedance of the thermally conductive gasket is in the range of 0.1°C in2 / W to 0.4°C in2 / W;

[0034] And / or, the volume resistance of the thermal impedance of the thermally conductive gasket is >1013Ωcm;

[0035] And / or, the breakdown voltage of the thermally conductive gasket is >10 kV / mm;

[0036] and / or, the dielectric constant of the thermally conductive pad is approximately 8;

[0037] And / or, the operating temperature of the thermally conductive gasket is in the range of -50°C to 200°C;

[0038] And / or, the tensile strength of the thermally conductive gasket is in the range of 10 psi to 30 psi;

[0039] And / or, the elongation of the tensile strength of the thermally conductive gasket is in the range of 10% to 50%;

[0040] And / or, the vertical layer insulation strength of the thermally conductive gasket exceeds 10 kV / mm;

[0041] And / or, the thickness of the thermally conductive pad is in the range of 0.5 mm to 1 mm;

[0042] And / or, the warping rate of the PCB board is less than 0.7%.

[0043] Optionally, when the hardness of the thermally conductive gasket is greater than a hardness threshold, thermally conductive silicone grease is provided between the thermally conductive gasket and the metal substrate.

[0044] Optionally, the PCB board is fixed to the metal bottom shell by a screw assembly; the creepage distance between the switch tube and the screw assembly is in the range of 0.2 mm to 0.5 mm;

[0045] And / or, a creepage distance between an inner wall surface of the metal bottom shell and the electronic control device has a value range of ≧1.0 mm.

[0046] Optionally, the antenna includes a GPS antenna; the motor driver also includes a GPS module;

[0047] The GPS antenna is disposed on the first surface;

[0048] The GPS module is disposed on the second surface and is located in the projection area of ​​the GPS antenna on the first surface.

[0049] Optionally, the motor driver further comprises a plastic top shell and a Bluetooth module; the antenna comprises a Bluetooth antenna;

[0050] The plastic top shell is used to seal the opening of the metal bottom shell;

[0051] The Bluetooth module is disposed on the first surface;

[0052] The Bluetooth antenna is arranged on the inner wall surface of the plastic top shell and is located in the projection area of ​​the Bluetooth module on the plastic top shell.

[0053] Optionally, the antenna further includes an LTE antenna;

[0054] The LTE antenna and the Bluetooth antenna are arranged on the plastic top shell to intersect vertically.

[0055] Optionally, the PCB board is a multi-layer PCB board; the motor driver further includes electrical components; the electrical components include at least one of the following: a power module, a Bluetooth module, a GPS module, a GPS antenna, an audio module, an LTE module, an LTE antenna, and a Bluetooth antenna;

[0056] The electrical device is provided with a ground copper foil in the second layer projection area of ​​the PCB board.

[0057] Optionally, the switch tube includes an insulating housing, a metal substrate, a wafer and reverse-molded pins;

[0058] The wafer is arranged on the metal substrate, and the pin is electrically connected to the wafer;

[0059] The insulating housing is disposed on the metal substrate;

[0060] The pins are bent along the sealing plate direction of the insulating outer shell; wherein the sealing plate of the insulating outer shell is arranged opposite to the metal substrate.

[0061] Optionally, the pin includes an extension section and a welding section, and the welding section is electrically connected to the wafer through the extension section;

[0062] The welding section and the sealing plate are located at the same horizontal plane.

[0063] The positive progressive effect of the present invention is that in the embodiment of the present invention, by setting a high-frequency capacitor bypass in the motor driver, the frequency-multiplied interference of high-order harmonics generated by the electronic control device can be effectively filtered out, and because the operating frequency of the high-frequency capacitor bypass is different from the operating frequency of the motor, it will not interfere with the operating frequency of the motor, thereby ensuring the effective operation of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 A cross-sectional view of an electronic device with IOT function provided by the prior art;

[0065] Figure 2 A cross-sectional view of an electronic device including a TO-220 packaged MOSFET provided in the prior art;

[0066] Figure 3 An exploded schematic diagram of an electronic device provided by the prior art;

[0067] Figure 4 A cross-sectional view of an electronic device provided by an exemplary embodiment of the present invention;

[0068] Figure 5 A front view of a switch tube provided by an exemplary embodiment of the present invention;

[0069] Figure 6 A top view of a switch tube provided by an exemplary embodiment of the present invention;

[0070] Figure 7 A cross-sectional view of a switch tube provided by an exemplary embodiment of the present invention;

[0071] Figure 8 A schematic diagram of a switch tube provided by an exemplary embodiment of the present invention being installed on a PCB board;

[0072] Fig. 9 A schematic diagram of a switch tube installed on a PCB board provided by the prior art;

[0073] Fig.10 A cross-sectional view of another electronic device provided for an exemplary embodiment of the present invention;

[0074] Fig.11 A schematic diagram of a thermal resistance model of an electronic device provided by an exemplary embodiment of the present invention;

[0075] Fig.12 A schematic diagram of a thermal resistance model of an electronic device provided by an exemplary embodiment of the present invention;

[0076] Fig.13 A partial cross-sectional view of a D2pak packaged MOSFET, a thermal pad, and a metal bottom shell included in an electronic device provided by an exemplary embodiment of the present invention;

[0077] Fig.14 A schematic diagram of screws and plastic pads on a TO-220 packaged MOSFET for an electronic device provided by an exemplary embodiment of the present invention;

[0078] Fig.15 A schematic diagram of screws and plastic pads on another TO-220 packaged MOSFET for an electronic device provided by an exemplary embodiment of the present invention;

[0079] Fig.16 A partial circuit diagram of a W-phase MOSFET of a motor driver provided by an exemplary embodiment of the present invention;

[0080] Fig.17 A partial enlarged cross-sectional view of a motor electronic control and a motor driver using a D2pak packaged MOSFET 70 provided by an exemplary embodiment of the present invention;

[0081] Fig.18 A partial enlarged cross-sectional view of another motor electronic control and motor driver using a D2pak packaged MOSFET 70 provided by an exemplary embodiment of the present invention;

[0082] Fig.19 A top view of a motor electronic control and a motor driver using a D2pak packaged MOSFET 70 provided by an exemplary embodiment of the present invention;

[0083] Fig. 20 A curve diagram showing the corresponding relationship between the pore diameter and SE of a pore of an electronic device provided by an exemplary embodiment of the present invention;

[0084] Fig.21 A circuit diagram of a three-phase MOSFET motor drive circuit and a power supply system provided by an exemplary embodiment of the present invention;

[0085] Fig. 22 A schematic diagram of a model of a power supply system for a motor drive circuit provided by an exemplary embodiment of the present invention;

[0086] Fig.23 An impedance characteristic curve of an aluminum capacitor provided by an exemplary embodiment of the present invention;

[0087] Fig.24 An impedance frequency curve diagram of a ceramic capacitor provided by an exemplary embodiment of the present invention;

[0088] Fig.25 An impedance frequency curve diagram of another ceramic capacitor provided by an exemplary embodiment of the present invention;

[0089] Fig.26 An impedance frequency curve diagram of another ceramic capacitor provided by an exemplary embodiment of the present invention;

[0090] Fig. 27 An impedance frequency curve diagram of another ceramic capacitor provided by an exemplary embodiment of the present invention;

[0091] Fig.28 An impedance frequency curve diagram of another ceramic capacitor provided by an exemplary embodiment of the present invention;

[0092] Fig.29 An impedance frequency curve diagram of another ceramic capacitor provided by an exemplary embodiment of the present invention;

[0093] Fig.30 An impedance frequency curve diagram of another ceramic capacitor provided by an exemplary embodiment of the present invention;

[0094] Fig.31 A circuit diagram of another three-phase motor drive circuit and power supply system provided by an exemplary embodiment of the present invention;

[0095] Fig.32 A circuit diagram of another three-phase motor drive circuit and power supply system provided by an exemplary embodiment of the present invention;

[0096] Fig.33 A schematic diagram of test results of a static drift test of a GPS antenna of a motor electronic control device in an open space provided by an exemplary embodiment of the present invention;

[0097] Fig.34 The radiation value emitted by a motor driver in a test frequency band of 30 MHz to 1 GHz is provided as an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0098] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples.

[0099] As user demands continue to increase, many electronic devices now have IOT (Internet of Things) functions. For example, the motor drivers in electric bicycles and electric motorcycles may have, but are not limited to, built-in LTE (Long Term Evolution) modules, Bluetooth modules, Wi-Fi (wireless fidelity, a wireless network transmission technology) modules, GPS (Global Positioning System) modules, audio modules, etc. The motor driver has wireless functions (weak current, belonging to the sensitive signal area) and electronic control functions (strong current). The combination of the two puts very high requirements on the electromagnetic compatibility inside the motor driver.

[0100] Figure 1This is a cross-sectional view of a motor driver with IOT function provided by the prior art. The motor driver includes a metal side shell 301, a plastic shell, and a PCB board 406. The PCB board 406 contains a GPS antenna and an electric control device that realizes the electric control function. Figure 2 and 3 The electronic control components may include but are not limited to MOSFET400, MOSFET401, MOSFET402, MOSFET403, MOSFET404, and MOSFET405, wherein the MOSFET is a TO-220 package MOSFET, which is vertically mounted on a PCB board 406 by screws 303 and plastic pads 305.

[0101] The metal substrate 990 of the TO-220 packaged MOSFET is in close contact with the metal block 300 via the thermal pad 302, and then the metal block 300 is in close contact with the metal side shell 201 via screws 306 and 307. When MOSFET400, MOSFET401, MOSFET402, MOSFET403, MOSFET404, and MOSFET405 are working, the heat generated is conducted to the thermal pad 302 and the metal block 300, and then conducted to the metal side shell 201 via the metal block 300, and finally the heat is dissipated through the metal side shell 201. The MOSFET power circuit is set at the pin position of MOSFET400, MOSFET401, MOSFET402, MOSFET403, MOSFET404, and MOSFET405 on the back of the PCB board 406. MOSFET is used to drive the motor (electric motor).

[0102] The metal side shell is generally made of aluminum, while the top and right shell of the motor driver are made of plastic material (called plastic top shell), and an LTE antenna 408 / Bluetooth antenna 409 is set at the right plastic top shell. A GPS antenna 407 is set at the approximately center of the PCB board 406.

[0103] The pulse electric field and pulse magnetic field generated by the electronically controlled device will interfere with the surrounding antennas. Figures 1 to 3Taking the six MOSFETs (electrically controlled components) shown as an example, TO-220 packaged MOSFET 400, TO-220 packaged MOSFET 401, TO-220 packaged MOSFET 402, TO-220 packaged MOSFET 403, TO-220 packaged MOSFET 404, and TO-220 packaged MOSFET 405 are vertically mounted on PCB board 406, and the height of the TOP layer vertically protruding from PCB board 406 is as high as 20mm, and the height of the whole machine is also about 22mm. The length of the six TO-220 packaged MOSFETs arranged in a row is about 80mm. The six MOSFETs work at high voltage (working voltage up to 72V, pulse voltage) and large current (10A), and instantly generate a peak overshoot of 100V, that is, the MOSFET (strong interference source) with a height of about 20mm and a width of about 80mm protruding from PCB board 406 generates three sets of pulse electric field-pulse magnetic field-pulse electric field-pulse magnetic field with a phase shift of 120 degrees and a peak overshoot of 100V, which radiate into the whole machine housing. At the same time, a pulse magnetic field, pulse electric field and pulse magnetic field with a pulse current of 40A to 60A, which is 4 to 6 times the working current, radiates into the entire casing.

[0104] If GPS antenna 407 is installed on the TOP layer of PCB board 406, MOSFET (strong interference source) will generate three sets of pulse electric field - pulse magnetic field - pulse electric field - pulse magnetic field with phase shift of 120 degrees and 100V peak overshoot, which will seriously interfere with the normal operation of GPS antenna 407; pulse magnetic field - pulse electric field - pulse magnetic field with instantaneous pulse current of 40A to 60A, which is 4 to 6 times the working current, will also seriously interfere with the normal operation of GPS antenna 407.

[0105] In addition, for the LTE antenna 408 / Bluetooth antenna 409 installed on the plastic top, the MOSFET (strong interference source) generates three sets of pulse electric field - pulse magnetic field - pulse electric field - pulse magnetic field with a phase shift of 120 degrees and a peak overshoot of 100V, which will seriously interfere with the normal operation of the LTE antenna 408 / Bluetooth antenna 409; the pulse magnetic field - pulse electric field - pulse magnetic field with an instantaneous pulse current of 40A to 60A, which is 4 to 6 times the working current, will also seriously interfere with the normal operation of the LTE antenna 408 / Bluetooth antenna 409.

[0106] In addition, since the six MOSFETs are through-hole devices, they need to go through a wave soldering process or a manual soldering process. Therefore, it is necessary to first install the six TO-220 packaged MOSFETs on the heat conductive block 300, and shape and arrange the six TO-220 packaged MOSFETs neatly into a whole. Then, the six TO-220 packaged MOSFETs with the heat conductive block 300 are inserted into the PCB board 406 (the surface-mount devices have been reflow-soldered on the PCB board 406) for wave soldering or manual soldering. The six TO-220 packaged MOSFETs with the heat conductive block 300 and the PCB board 406 (including the surface-mount devices) are fixed as a whole to the metal side shell 201 by screws 306 and screws 307. In addition, four screw columns (screw column 572, screw column 573, etc. in the figure) need to be set on the metal bottom shell, and the screw holes 571 and screw holes 574 of the PCB board 406 are aligned with the screw columns 572 and screw columns 573 one by one, and the screws 570 are inserted into the screw holes 571 and screw columns 572 of the PCB board 406, and the screws 575 are inserted into the screw holes 574 and screw columns 573 of the PCB board 406 to fix the PCB board 406 on the top of the metal bottom shell. In summary, the entire process of patch, plug-in, welding, and assembly is very complicated and cumbersome, and is prone to errors, with low production efficiency and very high cost.

[0107] In summary, existing motor drivers have defects such as complex and difficult production and assembly, high cost, and strong interference of electronic control devices such as MOSFET to LTE antennas, Bluetooth antennas, and GPS antennas. At the same time, they have complex structures, high costs, poor heat dissipation performance, and MOSFET cannot be added with a shielding cover.

[0108] In view of the above interference problem, an embodiment of the present invention provides an electronic device, which includes an electronic control device and a PCB board. An antenna is provided on the first surface of the PCB board and / or an antenna is provided above the first surface. The electronic control device is provided on the second surface of the PCB board and is welded on the PCB board.

[0109] In the embodiment of the present invention, since the electronically controlled device and the antenna are respectively arranged on two surfaces of the PCB board, the electronically controlled device and the antenna are spatially staggered through the PCB board, thereby achieving isolation between the two, thereby effectively avoiding interference of the pulse electric field and pulse magnetic field generated by the electronically controlled device on the antenna.

[0110] The electronic control device in this embodiment includes a switch tube, which can be a commercially available switch tube or a Figure 8 The reverse flip switch tube is shown.

[0111] The following takes an electronic device including a motor driver and a switch tube being a reverse flip-chip MOSFET as an example to further explain the structure and working principle of the electronic device.

[0112] See also Figure 4 , the reverse flip MOSFET 70 and other electronic control devices are arranged on the BOTTOM layer (second surface) of the PCB board 88, the D2pak packaged MOSFET 70 and other devices are arranged with ground copper foil G2 in the projection position K2 area of ​​the TOP layer of the PCB board 88, and the GPS antenna 14 is arranged on the TOP layer (first surface) of the PCB board 88, and the LTE antenna 17 is arranged on the plastic top shell 18. The reverse flip MOSFET 70 is closely contacted with the inner wall surface B1 of the metal bottom shell 200 through the thermal conductive pad 31, so as to achieve electrical isolation and heat conduction with the metal bottom shell 200, and at the same time, the reverse flip MOSFET 70 is isolated from the GPS antenna 14 on the TOP layer of the PCB board 88 and the LTE antenna 17 arranged on the plastic top shell through the ground copper foil G2 and staggered in space, so as to avoid the interference of the reverse flip MOSFET 70 and other devices on the GPS antenna 14 and the LTE antenna 17. The metal bottom shell 200 / metal side shell 201 is formed by low-cost extrusion in one piece, which not only reduces the cost of the metal shell, simplifies the SMT reflow soldering production process and the assembly production process, but also greatly reduces the thermal resistance between the reverse flip-chip MOSFET70 and the metal bottom shell 200 / metal side shell 201, thereby improving the heat dissipation performance.

[0113] The reverse flip MOSFET can be but not limited to the flip D2pak package. The flip D2pak package MOSFET70 + thermal pad + metal bottom shell / metal side shell solves the strict requirements of the withstand voltage test between the metal frame and the live parts (such as the motor drive circuit and IOT part are live parts), while the conventional TO-220 package MOSFET + thermal pad + thermal block + metal side shell solution cannot meet this safety requirement.

[0114] Figure 4 In the embodiment, the PCB board 88 is divided into two parts: one part is the IOT part (such as LTE module 15, MCU, GPS antenna 14, audio module 205, Bluetooth module, etc., which belongs to the sensitive area K1), MOS drive circuit 212, flip-chip MOSFET 70, input capacitor 19 (a device belonging to the motor drive area K2), etc., wherein the MOSFET adopts the surface mount D2pak package, and the pin 5 is reversely molded in the D2pak packaging process to form a reverse flip-chip MOSFET, see Figure 4 The pin 5 of the reverse flip-chip MOSFET 70 is soldered to the BOTTOM layer of the PCB board 88 , but the metal substrate 4 of the MOSFET 70 faces downward and is not close to the BOTTOM layer of the PCB board 88 , so the metal substrate 4 of the MOSFET 70 does not need to be soldered to the BOTTOM layer of the PCB board 88 .

[0115] In one embodiment, a soft thermally conductive gasket 31 is added to the metal substrate 4 of the MOSFET 70, and a metal bottom shell 200 (for example, an aluminum bottom shell with a rack) is arranged below the soft thermally conductive gasket 31. The metal substrate 4 of the MOSFET 70 is the part that generates more heat and cannot be welded on the BOTTOM layer of the PCB board 88. Instead, it is reversely installed on the PCB board 88, so that the pin 5 of the MOSFET 70 is welded on the BOTTOM layer of the PCB board 88 and is electrically connected to the MOSFET 70 control circuit or power circuit in the PCB board 88. The metal substrate 4 of the MOSFET 70 achieves low thermal resistance contact with the metal bottom shell 200 through the thermally conductive soft gasket 21, and at the same time, electrical isolation is achieved between the metal substrate 4 (which is electrically connected to the PCB board 88) and the metal bottom shell 200.

[0116] In addition, the electronic device provided by the embodiment of the present invention does not need to be Figure 2-3 The solution shown in the figure is first SMT patch and reflow soldering, and then it is necessary to add a thermal pad 302 between each MOSFET and the heat conductive block 300, and at the same time, screws 303 are driven into the MOSFET, and the plastic pad 305 is fixed to the screw hole 310 / screw hole 311 in the heat conductive block 300, and then the MOSFET with the heat conductive block 300 is installed and inserted into the PCB board 406, and the PCB board 406 is turned over, and a total of 18 pins of 6 TO-220 packaged MOSFETs are manually soldered one by one with an electric soldering iron and solder wire, and finally the PCB board 406 with the heat conductive block 300 and the MOSFET soldered is aligned with the screw column 572 / screw column 573 on the metal bottom shell 388, and the PCB board 406 is fixed by screws 570 / screws 575 and screw columns 572 / screw columns 573, and then the heat conductive block 300 is fixed to the metal side shell 201 by screws 307 / screws 306. The entire product assembly and welding process is very complicated, the production efficiency is very low, and the cost is very high. At the same time, the structural parts are very complicated: two metal parts are needed: a heat conduction block (aluminum extrusion forming process) + CNC processing of the side shell, and an aluminum extrusion forming bottom shell. The cost is very high, the processing efficiency of the bottom shell and the side shell is very low, and the heat dissipation performance is very poor, because the contact thermal resistance between the metal side shell and the metal bottom shell is very high, and the thermal conductivity performance is very poor.

[0117] In the embodiment of the present invention, Figure 4 The MOSFET 70 in the circuit board can be connected to the SMD components (such as Figure 4 The MOS driver component 212 of the BOTTOM layer of the PCB board 88 is mounted together with the chip mounter to complete the mounting at one time. At the same time, the MOSFET 70 and the chip components (such as the BOTTOM layer of the PCB board 88) of the BOTTOM layer of the PCB board 88 are mounted together. Figure 4The MOS driver components 212 of the BOTTOM layer of the PCB board 88 are put into the reflow oven together with the soldering to complete the soldering in one reflow process. The production efficiency is very high and no manual operation is required (such as manual soldering, manual plug-in, etc., which have very low production efficiency). Figure 2 The solution requires 6 screws to be installed between the 6 MOSFETs and the metal side shell, and then installed on the PCB board 88 through-hole soldering, and then the PCB board 88 is flipped over, and then 18 through-hole pads are manually soldered (1 MOSFET has 3 pins, that is, there are 18 through-hole pads).

[0118] The embodiment of the present invention provides a reverse flip-chip switch tube, which includes an insulating shell, a metal substrate, a wafer and reverse-molded pins. The wafer is arranged on the metal substrate, the pins are electrically connected to the wafer, the insulating shell cover is arranged on the metal substrate, and the pins are bent along the sealing plate direction of the insulating shell cover; wherein the sealing plate of the insulating shell cover is arranged opposite to the metal substrate.

[0119] The packaging method of the switch tube of the embodiment of the present invention can be, but is not limited to, the reverse flip-chip D2pak packaging. The electronic control device can be, but is not limited to, a high-power MOSFET, a high-power IGBT or a BJT (bipolar junction transistor).

[0120] The novel switch tube provided by the embodiment of the present invention is a switch tube in a reverse flip-chip D2pak package. The switch tube can be used, but is not limited to, in electronic devices with wireless functions and electronic control functions, such as motor drivers.

[0121] The following takes MOSFET as an example to further explain its structure.

[0122] like Figure 5 The front view of the switch tube is shown, and the gate pin G (chip pin 1), drain pin D (chip pin 2), and source pin S (chip pin 3) of the switch tube are arranged from left to right. Figure 6 The back side top view of the square switch tube is shown, and the source pin S (chip pin 3), drain pin D (chip pin 2), and gate pin G (chip pin 1) of the switch tube package are arranged from right to left. Figure 7 The internal cross-sectional view of the switch tube is given. The switch tube MOSFET is mainly composed of a die 27 (die), a bonding wire lead 29, a pin 5 (the pin 5 includes a gate pin G, a drain pin D, and a source pin S), a metal substrate 4, and an insulating shell 20. The metal substrate 4 on the back is a large copper block. The die 27 (die) of the MOSFET is set on the metal substrate 4. In this way, the die 27 of the MOSFET works at a high voltage and a large current, and the large heat generated is quickly transferred to the metal substrate 4, and then transferred to the thermal pad 31 through the metal substrate 4, and then transferred from the thermal pad 31 to the heat sink (for example Figure 4The metal bottom shell 200 + the metal side shell 201 are equivalent to the heat sink), and then through the heat sink (for example Figure 4 The convection and radiation of the metal bottom shell 200 and the metal side shell 201 (equivalent to the heat sink) dissipate the heat to the outside air, ensuring that the MOSFET wafer 27 works within a safe temperature range. The bonding wire leads are led from the MOSFET wafer 27 to the pin 5 (the pin 5 includes the source pin S, the drain pin D, and the gate pin G), and the pin 5 (the pin 5 includes the gate pin G, the drain pin D, and the source pin S) is soldered to the pad 8 in the PCB board 88, so that the MOSFET wafer 27 can be electrically connected to the PCB board 88.

[0123] like Fig. 9 As shown, the MOSFET provided by the prior art, generally the metal substrate 4 of the MOSFET is installed on the PCB board 88, and a large-area pad 9 needs to be set on the PCB board 88. However, since the copper thickness of the PCB board 88 is limited by the processing technology and cannot be too thick, the metal substrate 4 of the TO-263AA packaged MOSFET will generate a large amount of heat and conduct it to the PCB board 88. The heat conduction capacity is limited. Therefore, this solution is not suitable for high-power (high voltage, high current) application scenarios, and the MOSFET is easily damaged by overheating. Another problem is that the metal substrate 4 of the MOSFET is welded on the PCB board 88. The pad 9 occupies a large amount of space on the PCB board 88, which affects the wiring density of the PCB board 88, and the number of layers of the PCB board 88 needs to be increased to meet the application scenarios with more wiring and larger current.

[0124] In the embodiment of the present invention, see Figure 8 , the metal substrate 4 of the MOSFET faces the reverse side of the PCB board 88, and the pins 5 (the pins 5 include the gate pin G, the drain pin D, and the source pin S) are formed toward the reverse side of the horizontal side where the metal substrate 4 is located, so that the pins 5 and the insulating housing 20 are in the same horizontal plane, that is, the insulating housing 20 is attached to the PCB board 88, and the pins 5 can be soldered on the pads 8 in the PCB board 88, and the wiring is routed in the area where the insulating housing 20 is attached to the PCB board 88. The wiring includes the signal wiring 11, the ground wire 12, and the power wiring 12, which greatly increases the wiring density of the PCB board 88, and there is no need to increase the stacking or the area of ​​the PCB board 88 to meet the design requirements, which greatly saves costs. The cost of the PCB board 88 is proportional to the stacking of the PCB board 88 and the area of ​​the PCB board 88.

[0125] like Figure 4As shown, the LTE antenna 17 / Bluetooth antenna 117 is arranged at the inner wall surface A1 of the plastic top shell 18, and a metal bottom shell 200 is arranged at the bottom of the whole machine to dissipate heat for the D2pak packaged MOSFET 70 to reduce the thermal resistance between them. The metal rack 203 of the metal bottom shell 200 can significantly increase the heat dissipation area of ​​the metal bottom shell 200, and increase the convection heat dissipation and radiation heat dissipation to the outside air (the larger the area of ​​the metal bottom shell 200 exposed to the outside air, the stronger the convection heat dissipation and radiation heat dissipation performance). If the heat generation power of the six D2pak packaged MOSFETs 70 is too large, and the heat dissipation performance of the metal bottom shell 200 cannot meet the heat dissipation requirements of the six D2pak packaged MOSFETs 70, a metal side shell 201 can be added on the side away from the LTE antenna 17 / Bluetooth antenna 117 to further increase the heat dissipation area of ​​the metal shell 202 (equivalent to a radiator). The metal bottom shell 200 and the metal side shell 201 do not need to be processed separately, and can be completed by extrusion molding in one process, which has very high production efficiency and very low cost. It does not require two metal parts, and does not require expensive and inefficient CNC processing methods. At the same time, since the metal bottom shell 200 and the metal side shell 201 are integrally formed, the heat generated by the metal substrate 4 of the D2pak packaged MOSFET70 is transferred to the metal bottom shell 200 through the soft thermal pad 31, and 60% to 80% of the heat is transferred to the rack 203 of the metal bottom shell 200, and 20% to 40% of the heat is transferred to the metal side shell 201. Since the metal bottom shell 200 and the metal side shell 201 are integrally formed, heat conduction with low thermal resistance can be achieved between the metal bottom shell 200 and the metal side shell 201, that is, the heat dissipation area of ​​the metal bottom shell 200 and the metal side shell 201 integrally formed is very large, and they can achieve good air convection heat dissipation and radiation heat dissipation with the outside air, and quickly reduce the heat generated by the metal substrate 4 of the D2pak packaged MOSFET70.

[0126] In one embodiment, the thermally conductive gasket adopts a soft thermally conductive gasket, which can be compressed, and the compression amount is greater than 10%. The soft thermally conductive gasket 31 can fill the tiny gap between the back side of the metal substrate 4 of the D2pak packaged MOSFET 70 and the inner wall surface B1 of the metal bottom shell 200, which can greatly reduce the thermal resistance between them. The back side of the metal substrate 4 of the D2pak packaged MOSFET 70 is in direct contact with the inner wall surface B1 of the metal bottom shell 200, and the contact area between them only accounts for 8% to 30% of the total overlapping area between them. The contact thermal resistance is very large, so it is necessary to add a soft thermally conductive gasket 31 to the back side of the metal substrate 4 of the D2pak packaged MOSFET 70 and the inner wall surface B1 of the metal bottom shell 200. The soft thermally conductive gasket 31 can fill the tiny gap between the back side of the metal substrate 4 of the D2pak packaged MOSFET 70 and the inner wall surface B1 of the metal bottom shell 200, which can greatly reduce the thermal resistance between them.

[0127] At least one set of screw assemblies is disposed on the left and right ends of the PCB board 88 near the D2pak package MOSFET 70. A set of screw assemblies includes a screw (eg Fig.10 The screw 61 and screw 54 are shown as shown + a PCB screw hole (e.g., PCB screw hole 63 and PCB screw hole 56) + a screw column (e.g., screw hole 59 and screw hole 57), wherein the TOP layer of the PCB screw hole 63 is provided with a screw exposed copper 64 (i.e., the ink of the copper foil is removed to allow it to be electrically connected to the screw 61), and the BOTTOM layer is provided with a screw exposed copper 60 (i.e., the ink of the copper foil is removed to allow it to be electrically connected to the screw column 59), and the PCB screw hole 63 is located at the center of the screw exposed copper 64 and the screw exposed copper 60. The screw column 59 is firmly fixed on the metal bottom shell 200.

[0128] The TOP layer of the PCB screw hole 56 is provided with a screw exposed copper 55 (that is, the ink of the copper foil is removed to make it electrically connected to the screw 54), and the BOTTOM layer is provided with a screw exposed copper 53 (that is, the ink of the copper foil is removed to make it electrically connected to the screw column 57). The PCB screw hole 56 is located at the center of the screw exposed copper 55 and the screw exposed copper 53. The screw column 57 is firmly fixed on the metal bottom shell 200.

[0129] Insert the screw 61 into the PCB screw hole 63 and the screw column 59, and insert the screw 54 into the PCB screw hole 63 and the screw column 57. Rotate and tighten the screws 61 and 54 to firmly fix the D2pak packaged MOSFET 70 and the soft thermally conductive gasket 31 installed on the BOTTOM layer of the PCB board 88 between the inner wall surface B1 of the metal bottom shell 200 and the BOTTOM layer of the PCB board 88, and form the metal substrate 4 of the D2pak packaged MOSFET 70 and the soft thermally conductive gasket 31 into a low thermal resistance whole, greatly reducing the thermal resistance between the metal substrate 4 of the D2pak packaged MOSFET 70 and the inner wall surface B1 of the metal bottom shell 200. The thickness of D2pak packaged MOSFET 70 is h21, the thickness of soft thermal pad 31 is h22 (the thickness of soft thermal pad 31 after compression), and the thickness of screw column 59 and screw column 57 is h20 (that is, the distance between the BOTTOM layer of PCB board 88 and the inner wall surface B1 of metal bottom shell 200), so h20 = h21 + h22. Since the thickness of D2pak packaged MOSFET 70 is fixed, only the thickness h22 of soft thermal pad 31 can be appropriately compressed, so rotating screw 61 and screw 54 can compress the thickness h22 of soft thermal pad 31. The greater the thickness h22 of the soft thermally conductive gasket 31 or the elastic thermally conductive gasket, the greater the thermal resistance between the metal substrate 4 of the D2pak packaged MOSFET 70 and the inner wall surface B1 of the metal bottom shell 200 , that is, the thickness h22 of the soft thermally conductive gasket 31 is proportional to the thermal resistance between the metal substrate 4 of the D2pak packaged MOSFET 70 and the inner wall surface B1 of the metal bottom shell 200 .

[0130] The soft thermal pad 31 can be a thermal grease film or a thermal silica gel film. The thermal conductivity of the thermal grease film is 0.8W / (m·K) to 6W / (m·K). The following are the relevant parameters of a certain type of thermal grease film (a type of soft thermal pad): the surface viscosity is 2-side; color: gray; thickness is 0.3mm to 3.0mm; hardness is 3.24g / cm 3 ; Thermal impedance at 0.26℃in 2 / W; thermal conductivity is 4.5W / (m·K); volume resistivity>1013Ωcm; breakdown voltage>10kV / mm; dielectric constant is about 8; operating temperature is -50℃~200℃; tensile strength is 23psi; elongation is 50%; low molecular weight siloxane content Siloxane Volatiles D4~D20<0.005%; flame retardancy reaches UL94 level. In one embodiment, the surface of the inner wall surface B1 of the metal bottom shell 200 that is indirectly in contact with the back side of the metal substrate 4 of the D2pak packaged MOSFET 70 is flush with the back side of the metal substrate 4 of the D2pak packaged MOSFET 70 in the horizontal direction, and at the same time, the surface of the inner wall surface B1 of the metal bottom shell 200 that is indirectly in contact with the back side of the metal substrate 4 of the D2pak packaged MOSFET 70 is as flat as possible, which can also greatly reduce the gap between the inner wall surface B1 of the metal bottom shell 200, the back side of the metal substrate 4 of the D2pak packaged MOSFET 70 and the soft thermal conductive pad 31, and reduce the thermal resistance therebetween. The inner wall surface B1 of the metal bottom shell 200 can be formed by aluminum die casting to achieve very good flatness and this precision. In addition, the surface treatment of aluminum die casting will also affect the flatness of the surface of the inner wall surface B1 of the metal bottom shell 200 that is indirectly in contact with the back side of the metal substrate 4 of the D2pak packaged MOSFET 70. The surface treatment of aluminum die-casting mainly includes aluminum phosphating process, aluminum alkaline electrolytic polishing process, aluminum and aluminum alloy environmentally friendly chemical polishing process, aluminum and aluminum alloy electrochemical surface strengthening treatment, YL112 aluminum full gold surface oxidation treatment process, etc.

[0131] The thickness of the soft thermally conductive pad 31 can be calculated according to the Fourier equation:

[0132] Q = KA × ΔT / d;

[0133] R = A × ΔT / Q;

[0134] Among them, Q is heat, unit is W; K is thermal conductivity (thermal conductivity coefficient), unit is W / (m·K); A is contact area; d is heat transfer distance; T is temperature difference; R is thermal resistance value;

[0135] Combining the above two formulas, we can get K=d / R. Since the K value is constant, it can be concluded that the thermal resistance R value is proportional to the material thickness d, which means that the thicker the material, the greater the thermal resistance.

[0136] According to the properties of thermal conductive materials, it is found that the thermal resistance value R of many thermal conductive materials is not completely proportional to the thickness d. This is because most thermal conductive materials are not composed of a single component, and there will be nonlinear changes accordingly. As the thickness d increases, the thermal resistance value R will definitely increase, but it is not necessarily a completely proportional linear relationship, it may be a steeper curve relationship. Therefore, the thermal resistance value tested and calculated is not entirely the thermal resistance value of the material itself, but should be the sum of the thermal resistance value of the material itself and the thermal resistance value of the contact surface. Because the flatness, smoothness or roughness of the contact surface, and the pressure of installation and tightening are different, different contact surface thermal resistance values ​​will be generated, and different total thermal resistance values ​​will also be obtained. When testing thermal resistance, the contact area A, the heat value Q, and the pressure value applied to the contact surface are selected, and the same method is used to test different materials. The results obtained are meaningful for comparison.

[0137] The thermal resistance value R obtained through testing is not completely the real thermal resistance value. The thermal conductivity K value calculated based on the thermal resistance value and thickness is not completely the real thermal conductivity value. The Fourier equation is a completely idealized formula used to understand the principle of thermal conductive materials, but the actual application and thermal resistance calculation are complex mathematical models, and there will be many correction formulas to improve all possible problems in all links. It can be seen that for the same material, the thermal conductivity is a constant value, and the thermal resistance value will change with the thickness. For the same material, the greater the thickness, it can be simply understood that the heat transfer path through the material is longer, the more time it takes, and the worse the efficiency. For thermal conductive materials, the selection of appropriate thermal conductivity and thickness has a great relationship with the heat dissipation performance. For example, if a material with high thermal conductivity is selected, but the thickness is large, the performance is not good enough. The most ideal choice is: high thermal conductivity, thin thickness, and perfect contact pressure to ensure the best interface contact.

[0138] In one embodiment, a D2pak packaged MOSFET 70 with a larger metal substrate 4 is selected to increase the contact area between the metal substrate 4 of the D2pak packaged MOSFET 70 and the soft thermally conductive gasket 31 and the inner wall surface B1 of the metal bottom shell 200, thereby reducing the contact thermal resistance therebetween. At the same time, the thickness of the compressed soft thermally conductive gasket 31 is increased, and the compression amount of the soft thermally conductive gasket 31 is increased, which brings the following benefits: reducing the gap between the soft thermally conductive gasket 31 and the metal substrate 4 of the D2pak packaged MOSFET 70, thereby reducing the contact thermal resistance therebetween, because the thicker the soft thermally conductive gasket 31, the greater the thermal resistance.

[0139] In one embodiment, the metal bottom shell 200 and the metal side shell 201 are integrally formed, and both are aluminum die-casting shells or extrusion shells. The base 204 and the rack 203 are integrally formed. In this embodiment, the thickness of the metal base 204 is h30≧1mm, preferably h30≧3mm. The thicker the thickness h30 of the base 204 is, the stronger the lateral heat conduction capacity of the heat from the metal substrate 4+soft thermal pad 31 of the D2pak packaged MOSFET70 is, and the faster the lateral heat conduction speed is. A plurality of raised racks 203 are provided below the base 204 of the metal bottom shell 200 (outside the aluminum shell). The purpose of providing the racks 203 is to increase the surface area of ​​the metal bottom shell 200 in contact with the outside air, that is, to increase the heat transfer area, and to effectively transfer the heat from the metal substrate 4 + soft thermal pad 31 of the D2pak packaged MOSFET 70, the base 204 of the metal bottom shell 200, and the racks 203 to the air through convection heat dissipation, radiation heat dissipation, etc., so as to quickly reduce the temperature of the metal substrate 4 of the D2pak packaged MOSFET 70. This embodiment does not limit the addition of the raised racks 203 outside the base 204 of the metal bottom shell 200 (outside the aluminum shell), and it is also possible to make the bottom of the base 204 of the metal bottom shell 200 (outside the metal bottom shell 200) flat, and the external shape of the aluminum shell is not limited. That is, it is equivalent to exposing the heat sink to the outside air, which greatly reduces the thermal resistance from the D2pak packaged MOSFET 70 (a heat generating device), the metal bottom shell 200 / the metal side shell 201 to the outside air.

[0140] Preferably, a soft thermally conductive gasket 31 is arranged between the metal substrate 4 of the D2pak packaged MOSFET70 and the inner wall surface B1 of the metal bottom shell 200. Optionally, the soft thermally conductive gasket 31 includes a soft thermally conductive gasket (thermal conductive silicone grease film, which is the simplest to assemble, but has a slightly lower thermal conductivity) or a hard thermally conductive gasket (ceramic gasket, which requires adding thermal conductive silicone to the front and back sides of the ceramic gasket, and has a more complicated assembly method, but has a higher thermal conductivity). Since the inner wall surface B1 of the metal bottom shell 200 is in direct contact with the metal substrate 4 of the D2pak packaged MOSFET 70, the actual contact area is 10% to 30%, and the space between the inner wall surface B1 of the metal bottom shell 200 and the metal substrate 4 of the D2pak packaged MOSFET 70 is filled with air. Since air is a poor thermal conductor with a thermal conductivity of only 0.01W / (m·K) to 0.04W / (m·K), a soft thermally conductive pad 31 is added between the inner wall surface B1 of the metal bottom shell 200 and the metal substrate 4 of the D2pak packaged MOSFET 70 to fill the space between the inner wall surface B1 of the metal bottom shell 200 and the metal substrate 4 of the D2pak packaged MOSFET 70. The air between the metal substrate 4 and the soft thermally conductive gasket 31 can be a soft thermally conductive gasket or an insulating hard thermally conductive gasket. When the soft thermally conductive gasket is selected, the thickness of the unused soft thermally conductive gasket should be at least 10% thicker (i.e., 10%×h22) than the molding thickness of the soft thermally conductive gasket 31 assembled between the inner wall surface B1 of the metal bottom shell 200 and the metal substrate 4 of the D2pak packaged MOSFET70, preferably 30%, so that the soft thermally conductive gasket can fully fill the gap between the inner wall surface B1 of the metal bottom shell 200 and the metal substrate 4 of the D2pak packaged MOSFET70, because the tiny gap contains air, and the thermal resistance of air is very high, which will greatly reduce the heat conduction capacity. By compressing the molding thickness of the soft thermally conductive gasket between the inner wall surface B1 of the metal bottom shell 200 and the metal substrate 4 of the D2pak packaged MOSFET70, the thermal resistance between the inner wall surface B1 of the metal bottom shell 200 and the metal substrate 4 of the D2pak packaged MOSFET70 can be reduced as much as possible.

[0141] The compression of the thickness of the soft thermally conductive gasket determines the thermal resistance between the inner wall surface B1 of the metal bottom shell 200 and the metal substrate 4 of the D2pak packaged MOSFET 70 to a certain extent. The compression of the thickness of the soft thermally conductive gasket 31 is concluded to be more than 10%, preferably 30%. The metal substrate 4 of the D2pak packaged MOSFET 70 is installed on the BOTTOM layer of the PCB board 88. The screws 61 and screws 54 are installed around the PCB board 88 and are fixed on the screw columns 59 and screw columns 57 of the metal bottom shell 200 respectively. Under normal circumstances, under the gravity of the PCB board 88 and components, it will be slightly warped downward. If the compression of the thickness of the soft thermal pad 31 is far more than 30%, the PCB board 88 will further warp downward. When the PCB board 88 is severely warped, the PCB board 88 is prone to breakage during a 1-meter-high, 500-time drop test. In addition, if the GPS chip in the GPS module 801 and the baseband chip in the LTE module 15 soldered on the TOP layer or BOTTOM of the PCB board 88 are packaged in BGA or double-row pin QFN, when the PCB board 88 is severely warped, the pins of the BGA and the pins of the double-row pin QFN package are easily connected to each other. The pads are split, so strict requirements are put forward for the warpage rate of the PCB board 88 for the BGA packaged heater with a foot spacing of 0.5mm and 0.4mm or the double-row pin QFN heating device. After a large number of whole machine assembly experiments, it is concluded that the warpage rate of the PCB board 88 is within 0.7%, and the pins and pads of the BGA packaged heater with a foot spacing of 0.5mm and 0.4mm or the double-row pin QFN heating device in the PCB board 88 are not easy to split. At the same time, when doing a 1-meter-high, 500-time drop test, the PCB board 88 is not easy to break. When the compression amount of the thickness of the soft thermally conductive gasket 31 is preferably 30%, the warpage rate of the PCB board 88 can be controlled within 0.7%, and the thermal resistance of the soft thermally conductive gasket 31 between the inner wall surface B1 of the metal bottom shell 200 and the metal substrate 4 of the D2pak packaged MOSFET70 can be kept low. This is the best conclusion obtained after a large number of whole machine assembly experiments.

[0142] In this embodiment, a soft thermally conductive gasket 31 is added between the back side of the metal substrate 4 of the D2pak packaged MOSFET 70 and the inner wall surface B1 of the metal bottom shell 200, which has the following two functions: a. It is used to fill the gaps caused by the uneven surface of the inner wall surface B1 of the metal bottom shell 200 and the gaps caused by the uneven back side of the metal substrate 4 of the D2pak packaged MOSFET 70, thereby reducing the thermal resistance between the back side of the metal substrate 4 of the D2pak packaged MOSFET 70 and the inner wall surface B1 of the metal bottom shell 200, and improving the thermal conductivity, because there is air in the gap (air is a thermal insulating material with very high thermal resistance); b. The metal bottom shell 200 and the metal substrate 4 of the D2pak packaged MOSFET 70 need to be isolated to meet the insulation resistance between the ground of the controller power supply and the casing and the metal shell ≥ 20MΩ.

[0143] like Figure 4 As shown, when the thermally conductive gasket 21 is a soft thermally conductive gasket, the heat dissipation path of the D2pak packaged MOSFET (heat generating device) is divided into two paths: one path is the die of the D2pak packaged MOSFET → the internal insulation structure of the D2pak package → the soft thermally conductive gasket 31 → the metal bottom shell base 204 → the multiple raised racks 203 provided on the metal bottom shell base 204 → the surrounding air (metal bottom shell base 204 → the metal side shell 201 → the surrounding air); the other path is the die of the D2pak packaged MOSFET (heat generating device) → the internal insulation structure of the D2pak package → the pin 5 of the D2pak packaged MOSFET (heat generating device) → the pad 7 and solder 8 provided on the PCB board 88 (electrically connected to the pin of the D2pak packaged MOSFET) → the PCB via 50, the ground copper foil G2 and the outer copper foil → the air inside the shell → the plastic top shell 18. Since the thermal resistance of the air in the shell is very high, the thermal conductivity is only 0.01W / (m·K)~0.04W / (m·K), so the thermal resistance from the D2pak packaged MOSFET to the outside air mainly relies on the soft thermal pad 31, the metal bottom shell 200 and the metal side shell 201 for heat conduction.

[0144] Fig.11 A thermal resistance model diagram of an electronic device provided in an embodiment of the present invention using a D2pak packaged MOSFET + thermal grease + insulating hard thermal pad + thermal grease + metal bottom shell solution. Fig.11The thermal resistance model in the heat dissipation scheme shown is divided into two paths: one path is the thermal resistance R1 of the D2pak package MOSFET (heat generating device), the thermal resistance R2 of the metal substrate, the thermal resistance R3 of the soft thermal pad 31, the thermal resistance 4 of the metal bottom shell 200 and the side shell 201 → the outside air. The other path is the thermal resistance R1 of the D2pak package MOSFET (heat generating device), the thermal resistance R5 of the metal pin, the thermal resistance R6 of the PCB solder and pad, the thermal resistance R7 of the PCB via and copper foil, the thermal resistance R8 of the air inside the shell, and the thermal resistance R9 of the plastic top shell → the outside air.

[0145] It should be noted that the electronic control device may include but is not limited to high-power MOSFET, high-power IGBT or BJT (bipolar junction transistor). When applied to the motor drive scenario, the three-phase motor drive circuit M1 may use high-power MOSFET, high-power IGBT or BJT (bipolar junction transistor).

[0146] In one embodiment, the thermally conductive gasket uses a hard thermally conductive gasket, that is, a hard thermally conductive gasket 21 (such as a ceramic gasket, a mica gasket, etc., the thickness of the hard thermally conductive gasket is fixed) is added between the D2pak packaged MOSFET70 and the inner wall surface B1 of the metal bottom shell 200 to achieve heat conduction and electrical isolation between the D2pak packaged MOSFET70 and the metal bottom shell 200. Since the back side of the metal substrate 4 of the D2pak packaged MOSFET 70, the front and back surfaces of the hard thermal gasket 21, and the inner wall surface B1 of the metal bottom shell 200 appear to be very flat, but in fact their surfaces all have many tiny pits and bumps. When the back side of the metal substrate 4 of the D2pak packaged MOSFET 70 is directly in contact with the front side of the hard thermal gasket 21, the contact area between them only accounts for 8% to 30% of the total overlapping area between them, and the thermal resistance of the contact is very large. Therefore, it is necessary to add thermal grease 221 between the back side of the metal substrate 4 of the D2pak packaged MOSFET 70 and the front side of the hard thermal gasket 21. The thermal grease 221 can fill the tiny gap between the back side of the metal substrate 4 of the D2pak packaged MOSFET 70 and the front side of the hard thermal gasket 21, which can greatly reduce the thermal resistance between them. The back side of the hard thermally conductive gasket 21 is in direct contact with the inner wall surface B1 of the metal bottom shell 200, and the contact area between them only accounts for 8% to 30% of the total overlapping area between them. The thermal resistance of the contact is very large, so it is necessary to add thermal grease 220 between the back side of the hard thermally conductive gasket 21 and the inner wall surface B1 of the metal bottom shell 200. The thermal grease 220 can fill the tiny gap between the back side of the hard thermally conductive gasket 21 and the inner wall surface B1 of the metal bottom shell 200, which can greatly reduce the thermal resistance between them.

[0147] At least one set of screw components is to be arranged near the left and right ends of the D2pak package MOSFET 70, wherein a set of screw components includes a screw, for example Fig.10 Screw 61, screw 54) + a PCB screw hole (e.g. Fig.10 Screw hole 56, screw hole 63) + a screw column (e.g. Fig.11 The screw column 59 and the screw column 57) are preferably two sets of screw assemblies. Fig.10 The solution shown in the figure shows that two sets of screw assemblies are added to the left and right ends of the D2pak package MOSFET 70: Screw assembly 1 (for example Fig.10 Screw 61+PCB screw hole 63+screw column 59), screw assembly 2 (e.g. Fig.10 The PCB screw hole 63 has a screw exposed copper 64 on the TOP layer (i.e., the ink of the copper foil is removed to make it electrically connected to the screw 61), and the PCB screw hole 63 has a screw exposed copper 64 on the BOTTOM layer (i.e., the ink of the copper foil is removed to make it electrically connected to the screw column 59). The PCB screw hole 63 is located at the center of the screw exposed copper 64 and the screw exposed copper 60. The screw column 59 is firmly fixed on the metal bottom shell 200.

[0148] The TOP layer of the PCB screw hole 56 is provided with a screw exposed copper 55 (that is, the ink of the copper foil is removed to make it electrically connected to the screw 54), and the BOTTOM layer is provided with a screw exposed copper 53 (that is, the ink of the copper foil is removed to make it electrically connected to the screw column 57). The PCB screw hole 56 is located at the center of the screw exposed copper 55 and the screw exposed copper 53. The screw column 57 is firmly fixed on the metal bottom shell 200. The screw 61 is inserted into the PCB screw hole 63 and the screw column 59, and the screw 54 is inserted into the PCB screw hole 63 and the screw column 57. By rotating and tightening screws 61 and screws 54, the D2pak packaged MOSFET 70 and thermal grease 221, hard thermal gasket 21, and thermal grease 220 installed on the BOTTOM layer of the PCB board 88 can be firmly fixed between the inner wall surface B1 of the metal bottom shell 200 and the BOTTOM layer of the PCB board 88, so that the metal substrate 4 of the D2pak packaged MOSFET 70 and the thermal grease 221, hard thermal gasket 21, and thermal grease 220 form a low thermal resistance whole, thereby greatly reducing the thermal resistance between the metal substrate 4 of the D2pak packaged MOSFET 70 and the inner wall surface B1 of the metal bottom shell 200. The thickness of D2pak packaged MOSFET70 is h21, the thickness of thermal grease 221+hard thermal pad 21+thermal grease 220 is h23, and the thickness of screw column 59 and screw column 57 is h20 (that is, the distance between the BOTTOM layer of PCB board 88 and the inner wall surface B1 of metal bottom shell 200), so h20=h21+h23. Since the thickness of hard thermal pad 21 and D2pak packaged MOSFET70 are fixed, only the thickness of thermal grease 221 and thermal grease 220 can be appropriately compressed, so rotating screw 61 and screw 54 can compress the thickness h23 of thermal grease 221+hard thermal pad 21+thermal grease 220. The greater the thickness h23 of the thermal grease 221 + hard thermal gasket 21 + thermal grease 220, the greater the thermal resistance between the metal substrate 4 of the D2pak-packaged MOSFET 70 and the inner wall surface B1 of the metal bottom shell 200. That is, the thickness h23 of the thermal grease 221 + hard thermal gasket 21 + thermal grease 220 is proportional to the thermal resistance between the metal substrate 4 of the D2pak-packaged MOSFET 70 and the inner wall surface B1 of the metal bottom shell 200.

[0149] The thermal conductivity of thermal grease is between 0.8W / (m·K) and 10W / (m·K)) and the thermal conductivity of insulating hard thermal gasket 21 (for example, the thermal conductivity of sesquioxide ceramic gasket is 20W / (m·K) to 30W / (m·K); the thermal conductivity of cubic boron nitride is 33W / (m·K); the thermal conductivity of boron carbide is 33W / (m·K); the thermal conductivity of single crystal aluminum nitride can reach 275W / (m·K), the thermal conductivity of diamond can reach 2000W / (m·K), the thermal conductivity of polycrystalline is 70 to 210W / (m·K), and the thermal conductivity of beryllium oxide ceramic gasket is close to that of metallic aluminum) are all relatively high.

[0150] like Fig.10 As shown in the figure, when the thermal pad 21 is an insulating hard thermal pad (such as a ceramic pad), the heat dissipation path of the D2pak packaged MOSFET 70 (heat generating device) is divided into two paths: one path is the die of the D2pak packaged MOSFET 70 → the internal insulation structure of the D2pak package → the thermal grease 220 → the insulating hard thermal pad 21 → the thermal grease 221 → the metal bottom shell base 204 → the multiple raised racks 203 set on the metal bottom shell base 204 → the surrounding air (the metal bottom shell base 204 → the metal side shell 201 → the surrounding air). The other path is the die of D2pak packaged MOSFET (heat generating device) → the insulation structure inside the D2pak package → the pin 5 (e.g., gate pin G, drain pin D, source pin S) of the D2pak packaged MOSFET 70 (heat generating device) → the pad 7 and solder 8 set on the PCB board 88 (electrically connected to the gate pin G1, drain pin D1, source pin S1 of the D2pak packaged MOSFET 70) → PCB via 50, ground copper foil G2 and outer copper foil → air inside the shell → plastic top shell 18.

[0151] Since the thermal resistance of the air in the shell is very high and the thermal conductivity is only 0.01W / (m·K)~0.04W / (m·K), the thermal resistance from the D2pak packaged MOSFET to the outside air mainly relies on thermal grease 221, insulating hard thermal gasket 21, thermal grease 220, metal bottom shell 200 and metal side shell 201 for heat conduction. Fig.10 Another thermal resistance model diagram of the electronic device provided in an embodiment of the present invention using a D2pak packaged MOSFET + thermal grease + insulating hard thermal pad + thermal grease + metal bottom shell solution. Fig.12The thermal resistance model in the heat dissipation scheme shown is divided into two paths: one path is the thermal resistance R1 of the D2pak package MOSFET (heat generating device), the thermal resistance R2 of the metal substrate, the thermal resistance R3 of the thermal grease, the thermal resistance R4 of the insulating hard thermal pad, the thermal resistance R5 of the thermal grease, the thermal resistance R6 of the metal bottom shell 200 and the side shell 201 → the outside air. The other path is the thermal resistance R1 of the D2pak package MOSFET (heat generating device), the thermal resistance R7 of the metal pin, the thermal resistance R8 of the PCB solder and pad, the thermal resistance R9 of the PCB via and copper foil, the thermal resistance R10 of the air inside the shell, and the thermal resistance R11 of the plastic top shell → the outside air.

[0152] The following takes an electronic device including a flip-chip D2pak package MOSFET70 + thermal pad + metal bottom shell / metal side shell as an example to introduce the voltage test requirements of the electronic device and the solution to the problem (one of the safety regulations).

[0153] According to the national standard GB24155-2009, strict requirements are put forward for the withstand voltage test of the electronic devices and metal frames of electric motorcycles / electric bicycles. Table 1 gives the withstand voltage test requirements of the national standard GB24155-2009 for the electronic devices and metal frames of electric motorcycles / electric bicycles. Fig.13 A partial cross-sectional view of the D2pak package MOSFET + thermal pad + metal bottom case is given. Figure 4 , Fig.13 , Table 1, because the metal shell 202 (including the metal bottom shell 200 + the metal side shell 201) is connected to the metal frame, the sensitive area K1 wiring, vias, devices (such as the power module 803, the Bluetooth module 802, the GPS module 801, the GPS antenna 14, the audio module 205, the LTE module, the LTE antenna 17, the Bluetooth antenna 117, etc.) in the PCB board 88, and the motor drive area K2 wiring, vias, devices (external power supply positive cable 331, external power supply positive cable 331, electrolytic capacitor 19, upper tube MOSFET74 + lower tube MOSFET75, upper tube MOSFET72 + lower tube MOSFET73, upper tube MOSFET70 + lower tube MOSFET71) must be insulated from the metal shell 202 (including the metal bottom shell 200 + the metal side shell 201).

[0154] Generally, 48V~72V batteries are used to power the motor driver. According to Table 2, if the basic insulation requirement is met, it is AC 1000V; if the additional insulation requirement is met, it is AC 2Umax+2250V=2×72V+2250V=2394V; if the reinforced insulation requirement is met, it is AC 2Umax+3750V=2×72V+3750V=3894V. Figure 4 , Fig.10In the shown scheme, since the D2pak-packaged MOSFET70~D2pak-packaged MOSFET75 generate a lot of heat when working, they need to be close to the metal bottom shell 200. Therefore, it is necessary to especially strengthen the safety gap (including creepage distance and electrical clearance) between the D2pak-packaged MOSFET70~D2pak-packaged MOSFET75 and the metal bottom shell 200, the metal side shell 201, the screw column 59, and the screw column 57.

[0155] The metal substrate 4 of the D2pak packaged MOSFET 70 in the PCB board 88 is electrically connected to the PCB board 88, and a thermally conductive gasket 31 is provided between the back surface B2 (including the metal substrate 4) of the D2pak packaged MOSFET 70 and the inner wall surface B1 of the metal bottom shell 200. As long as the high-voltage breakdown resistance of the thermally conductive gasket 31 between the back surface B2 of the D2pak packaged MOSFET 70 and the inner wall surface B1 of the metal bottom shell 200 can withstand the isolation test of 50Hz-60Hz / 1000V AC for 1 second (basic insulation requirement), the isolation test of 50Hz-60Hz / 2894V AC for 1 second (additional insulation requirement), and the isolation test of 50Hz-60Hz / 3894V AC for 1 second (reinforced insulation requirement), only the creepage distance of the surface discharge needs to be considered.

[0156] Figure 4 When the insulating soft thermally conductive pad 31 (or Fig.10 When the dielectric electric field strength of the medium insulating hard thermally conductive pad 21) is higher than a predetermined value, the insulating soft thermally conductive pad 31 (or Fig.10 The dielectric surface of the medium insulation hard thermal pad 21) will lose its insulation performance, which is called breakdown. The dielectric soft thermal pad 31 (or Fig.10 Medium Insulation Hard Thermal Conductive Gasket 21) The electric field strength when the dielectric surface is broken down is called the breakdown strength, and its unit is: kV / mm.

[0157] Under the action of high field strength, the initial electrons on the surface of the insulating soft thermally conductive pad medium between the back side B2 of the D2pak packaged MOSFET 70 and the metal bottom shell 200 are more likely to move, and with the impact of the initial electrons, more electrons are generated, thereby reducing the breakdown strength.

[0158] Specifically, the breakdown strength is calculated as EB = UB / d, where UB is the electric field strength (i.e., voltage) between two conductors, and d is the thickness of the dielectric between the two conductors or the distance between the surface dielectrics of the two conductors. The breakdown strength is proportional to the electric field strength and inversely proportional to the thickness or distance of the dielectric.

[0159] According to the above derivation formula and conclusion, the following analysis is carried out:

[0160] Taking the above-mentioned certain type of thermal grease film (a type of soft thermal gasket) medium as an example, according to the relevant requirements obtained from the test, the vertical layer insulation strength of the insulating soft thermal gasket must exceed 10kV / mm, that is, when the thickness after assembly and compression is 1mm, the interlayer breakdown voltage must exceed 10kV, and the medium of the insulating soft thermal gasket will be broken down. That is, the soft thermal gasket 31 adopts the above-mentioned certain type of thermal grease film, which can far meet the national standard GB24155-2009 for the voltage withstand test of live parts and metal frames of electric motorcycles / electric bicycles (calculated as 3894V). Even when the thickness after assembly compression is 0.5mm, the interlayer breakdown voltage must exceed 5kV before the dielectric of the insulating soft thermally conductive gasket is broken down. That is, the soft thermally conductive gasket 31 uses a certain type of thermally conductive silicone grease film provided above, which can far meet the national standard GB24155-2009 for the withstand voltage test of live parts and metal frames of electric motorcycles / electric bicycles (calculated as 3894V).

[0161] The creepage distance between the back surface B2 (including the metal substrate 4) of the D2pak packaged MOSFET 70 and the inner wall surface B1 of the metal bottom shell 200 is analyzed as follows:

[0162] The horizontal length of the back side B2 of the D2pak packaged MOSFET 70 is L63. The horizontal length of the thermal pad 31 is L60, and h22 is the compressed thickness of the thermal pad 31. In the horizontal direction, the length from the left edge of the thermal pad 31 to the left edge of the back side B2 of the D2pak packaged MOSFET 70 is L62, and the length from the right edge of the thermal pad 31 to the right edge of the back side B2 of the D2pak packaged MOSFET 70 is L61.

[0163] The horizontal length of the back surface B2 of the D2pak packaged MOSFET 70 is L63, and it is necessary to satisfy L60=L63+L62+L61.

[0164] The creepage distance of the surface discharge from the inner wall surface B1 of the metal bottom shell 200 to the left side of the back surface B2 of the D2pak package MOSFET 70 is: L7 left = h22 + L62 + h54;

[0165] The creepage distance of the surface discharge from the inner wall surface B1 of the metal bottom shell 200 to the right side of the back surface B2 of the D2pak package MOSFET 70 is: L8 right = h22 + L61 + h54;

[0166] It is required that L7 left ≧ 2.5mm (preferably L left ≧ 3.0mm) to meet the relevant voltage withstand test requirements of the national standard GB24155-2009.

[0167] It is required that L8 right ≧1.0mm (preferably L left ≧2.0mm) to meet the relevant voltage withstand test requirements of the national standard GB24155-2009.

[0168] Table 1 National Standard GB24155-2009 Requirements for withstand voltage test of live parts and metal frames of electric motorcycles / electric bicycles

[0169]

[0170]

[0171] When installing a switch tube (such as MOSFET400, MOSFET401, MOSFET402, MOSFET403, MOSFET404, MOSFET405 in TO-220 package), a plastic pad 331 (such as Fig.14 , Fig.15 As shown in FIG. 3 ), the metal substrate 4 of the switch tube is prevented from contacting the metal block and the metal side shell 201 through the screw 303 to cause a short circuit. After adding the plastic pad 302, the creepage distance between the switch device and the screw 303 is 0.2 to 0.5 mm.

[0172] like Figure 2 , 3 As shown, in the prior art, the heat conducting block 300 needs to be in close contact with the metal side shell 201 to reduce the thermal resistance therebetween, and the metal side shell 201 and the metal frame ( Figure 3 The six MOSFETs and the thermal pad 302 of the TO-220 package can be firmly fixed on the thermal block 300 through screws 303 and plastic pads 305, that is, screws 303 are electrically connected to the metal frame, so the creepage distance between the metal substrate 990 of MOSFET4 and the metal frame is the creepage distance between the metal substrate 990 of MOSFET4 and the screws 303. The specific analysis is as follows:

[0173] Combination Figure 3 When the diameter d2 of the screw head of the screw 303 is smaller than the diameter d1 of the plastic pad 305 , the distance between the screw head 330 of the screw 303 and the edge of the plastic pad 305 is L10=(d1-d2) / 2.

[0174] The thickness of the thermal pad 302 is L88, and the thickness of the head 331 of the plastic pad 305 is L89.

[0175] The creepage distance between the metal substrate 990 of the TO-220 packaged MOSFET and the screw 303 is equal to L10+L89.

[0176] When the diameter d2 of the screw head of the screw 303 is greater than the diameter d1 of the plastic pad 305 , it is only necessary to calculate the thickness of the head 331 of the plastic pad 305 as L89, and the creepage distance between the metal substrate 990 of the TO-220 packaged MOSFET and the screw 303 is equal to L89.

[0177] The thermal pad 302 needs to be provided with an opening 2 (for passing the screw 303 ), so the creepage distance from the thermal block 300 to the metal substrate 990 of the TO-220 packaged MOSFET is equal to the thickness of the thermal pad 302 , which is L88.

[0178] As long as L10+L89>L88, the creepage distance from the metal frame to the metal substrate 990 of the TO-220 packaged MOSFET is L88, that is, the thickness L88 of the thermal pad 302 will become the bottleneck of the creepage distance from the metal frame to the metal substrate 990 of the TO-220 packaged MOSFET. However, the thickness L88 of the thermal pad 302 cannot be too thick, otherwise the thermal resistance of the thermal pad 302 will be very high. Generally, it should be 0.5mm to 1mm, so that the thermal pad 302 can have a lower thermal resistance, so that the heat of the metal substrate 990 of the TO-220 packaged MOSFET can be quickly transferred to the thermal block 300→metal side shell 201→external air.

[0179] According to the relevant withstand voltage test requirements of the national standard GB24155-2009, the isolation test of 50Hz-60Hz / 1000V AC for 1 second (basic insulation requirements), the isolation test of 50Hz-60Hz / 2894V AC for 1 second (additional insulation requirements), and the isolation test of 50Hz-60Hz / 3894V AC for 1 second (reinforced insulation requirements), it is obvious that the TO-220 packaged power MOS tube + thermal block + metal side shell solution cannot meet the above creepage distance requirements. Electric breakdown will occur during the isolation test of 50Hz-60Hz / 1000V AC for 1 second (basic insulation requirements), the isolation test of 50Hz-60Hz / 2894V AC for 1 second (additional insulation requirements), and the isolation test of 50Hz-60Hz / 3894V AC for 1 second (reinforced insulation requirements), resulting in damage to the TO-220 packaged MOSFET. This proves that the TO-220 packaged power MOSFET + thermal block + metal side shell solution cannot pass the voltage withstand test of live parts and metal frames, and has obvious defects.

[0180] pass Figure 3 and Figure 4 It is obvious from the comparison that the TO-220 package MOSFET+thermal pad+thermal block+metal in the prior art The side shell solution is difficult to pass the pressure test of live parts and metal frame, and the thermal resistance of the solution is high. Reverse installationThe D2pak packaged MOSFET70+metal bottom shell / metal side shell solution not only easily passes the electronic device and metal frame voltage withstand test, but also its thermal resistance is significantly lower than the TO-220 packaged MOSFET+thermal gasket+thermal block+metal side shell solution in the prior art, proving the superiority of the reverse-mounted D2pak packaged MOSFET70+metal bottom shell / metal side shell solution adopted in this embodiment.

[0181] According to the national standard QB / T2946-2020, strict requirements are put forward for the insulation resistance test of live parts and metal frames of electric motorcycles / electric bicycles. Table 2 gives the test requirements of the national standard QB / T2946-2020 for the insulation resistance test of live parts and metal frames of electric motorcycles / electric bicycles. It can be concluded from Table 2 that the insulation resistance of live parts and metal frames of electric motorcycles / electric bicycles is required to be 20MΩ under normal conditions (that is, room temperature), 20MΩ under low temperature, 5MΩ under high temperature, 2MΩ under constant temperature, and 2MΩ under splash-proof conditions. As shown in the relevant parameters of a certain model of thermal grease film provided above, the volume resistance of thermal grease film is >1013Ω·cm.

[0182] Thermally conductive silicone film is an excellent insulating material, and its volume resistivity is ≥1012Ω·cm. Some specially optimized and modified silicone raw materials even have a volume resistivity exceeding 1013~1014Ω·cm to meet the extremely demanding insulation requirements. Insulation resistance is the quotient of the DC voltage applied between the electrodes in contact with the sample and the steady-state current passing between the electrodes. It includes volume resistance and surface resistance. That is, the soft thermally conductive gasket 31 in the prior art solution adopts a certain type of thermally conductive silicone film provided above. The listed volume resistance is not a bottleneck. As long as the surface of the thermally conductive silicone film is large enough (affecting the surface resistance, the edge of the thermally conductive silicone film is larger than the back B2 of the D2pak packaged MOSFET70), surface resistance + volume resistance = insulation resistance, which meets the national standard QB / T2946-2020 insulation resistance test requirements of live parts and metal frames of electric motorcycles / electric bicycles in Table 2.

[0183] Table 2 National Standard QB / T2946-2020 Insulation resistance test requirements for live parts and metal frames of electric motorcycles / electric bicycles

[0184]

[0185] In the prior art, since the screw 303 (the screw 303 is electrically connected to the metal frame) is separated from the TO-220 packaged MOSFET only by the plastic pad 331, and the creepage distance between them is only 0.5mm to 1mm, the surface resistance cannot meet the insulation resistance test requirements of the national standard QB / T2946-2020 Electric Motorcycle / / Electric Bicycle for live parts and metal frames in Table 2.

[0186] Comparing the above two sets of analysis data, the solution of the embodiment of the present invention is more advantageous than the solution of the prior art, which proves that the solution of the embodiment of the present invention is more reasonable and scientific.

[0187] The following is a detailed analysis of electromagnetic leakage (analysis of the impact of motor drive circuit M1 leakage on various antennas)

[0188] Figure 4 The D2pak packaged MOSFET 70 is installed in a lying position on the BOTTOM layer of the PCB board 88. The height of the D2pak packaged MOSFET 70 protruding from the PCB board 88 is much lower than Figure 3 The height of the MOSFET (TO-220 package) mounted neutrally on the TOP layer of the PCB board 88 is Figure 4 The pulse electric field generated by the D2pak package MOSFET70 has a far lower radiation distance than the external electric field Figure 3 A MOSFET (TO-220 package) is mounted on the TOP layer of the PCB 88. Figure 4 , D2pak packaged MOSFET70 is a strong interference source. It is set at the lower right corner of the BOTTOM layer of PCB board 88, and the LTE antenna 17 / Bluetooth antenna 117 is set on the left inner wall of the plastic top shell 18 in the space above the PCB board 88. The D2pak packaged MOSFET70 is far away from the LTE antenna 17 / Bluetooth antenna 117, and there is a PCB board 88 between them, and there is also a ground plane in the PCB board 88. Therefore, the D2pak packaged MOSFET70 on the BOTTOM layer of the PCB board 88 A very small amount of pulse electric field from the packaged MOSFET 70 leaks to the vicinity of the LTE antenna 17 / Bluetooth antenna 117 / GPS antenna 14, causing damage to the plastic Top shell 18The interference from LTE antenna 17 / Bluetooth antenna 117 is almost negligible.

[0189] Continue reading Figure 4, the GPS antenna 14 is designed on the TOP layer of the PCB board 88, and the D2pak packaged MOSFET 70 installed on the BOTTOM layer of the PCB board 88 generates a pulse electric field on the BOTTOM layer of the PCB board 88, and there is a PCB board 88 between them (there is also a ground plane in the PCB board 88), and the projection of the GPS antenna 14 on the BOTTOM layer of the PCB board 88 does not overlap with the D2pak packaged MOSFET 70 on the BOTTOM layer of the PCB board 88, so the pulse electric field generated by the D2pak packaged MOSFET 70 on the BOTTOM layer of the PCB board 88 will not interfere with the GPS antenna 14. In the prior art solution, because the TO-220 packaged MOSFET protrudes very high from the PCB board, and the TO-220 packaged MOSFET and the GPS antenna 14 are arranged on the front of the PCB board, the pulse electric field generated by the TO-220 packaged MOSFET completely covers the GPS antenna 14, and the GPS antenna 14 receives very weak signals from satellites, and is easily interfered by the pulse electric field generated by the TO-220 packaged MOSFET.

[0190] Fig.16 The partial circuit diagram of the W-phase MOSFET of the motor driver is given. Figure 4 The motor driver W-phase MOSFET partial circuit diagram in the scheme, the motor drive circuit is divided into three phases: W phase, V phase, H phase (such as Fig.21 , Fig. 22 , Fig.31 , Fig.32 W phase, V phase, H phase in the scheme shown), Fig.16 Only the W phase is taken as an example for explanation. Fig.16 As shown, one end of the motor cable 313 is electrically connected to the W-phase winding of the motor 501 , and the other end of the motor cable 313 is electrically connected to the copper foil 33 . Fig.16 A partial enlarged cross-sectional view of the motor electronic control + IOT board using D2pak package MOSFET70 is given, that is, Figure 4 A partial enlarged cross-sectional view of the motor electronic control + IOT board of the D2pak packaged MOSFET70 in the solution. Fig.17 Another partial enlarged cross-sectional view of the motor electronic control + IOT board using the D2pak package MOSFET70 is given, that is, Figure 4 Another partial enlarged cross-sectional view of the motor electronic control + IOT board of the D2pak packaged MOSFET70 in the solution. Fig.19 The top view of the motor control + IOT board using D2pak package MOSFET70 is given, that is, Figure 4The top view of the motor electronic control + IOT board of the D2pak packaged MOSFET70 in the scheme. Because the top shell 18 is made of plastic material, the GPS antenna 14 is set on the TOP layer of the PCB board 88. The GPS antenna 14 can normally receive the GPS signal transmitted by the satellite signal after the satellite signal from the earth orbit penetrates the plastic top shell 18. The GPS module 801 is set near the projection position of the GPS antenna 14 on the BOTTOM layer of the PCB board 88, which facilitates the electrical connection of the RF link of the GPS module 801 and the minimum path of the GPS antenna 14, while saving PCB board space. The LTE module 15 is arranged near the left side of the PCB board, the GPS antenna 14 is arranged on the right side of the LTE module 15, the audio module 205 (such as the audio codec part, the audio amplifier, the microphone, etc.) is arranged on the right side of the GPS antenna 14, the Bluetooth module 802 is arranged on the right side of the audio module 205, and the power module 803 is arranged on the upper left side of the Bluetooth module 802, and the power module 803 provides various power supplies to various functional modules (such as providing various power supplies to the LTE module 15, the audio module 205, the GPS module 801, the Bluetooth module 802, etc.). The clearance area 804 of the LTE antenna 17 is arranged below the LTE module 15, the GPS antenna 14, and the audio module 205 of the PCB board 88, and the LTE antenna 17 is arranged at the position where the clearance area 804 of the LTE antenna 17 is projected on the plastic top shell 18. The clearance area 804 of the LTE antenna 17 creates good conditions for the radiation of the LTE antenna 17. The Bluetooth module 802 is projected on the plastic top shell 18 to set a Bluetooth antenna 117. The Bluetooth antenna 117 intersects vertically with the LTE antenna 17 to increase the isolation between the Bluetooth antenna 117 and the LTE antenna 17. The power module 803, Bluetooth module 802, GPS module 801, GPS antenna 14, audio module 205, LTE module, LTE antenna 17, Bluetooth antenna 117, etc. are all devices in the sensitive area K1. In the sensitive area K1, a ground copper foil G1 is projected on the second layer of the PCB board 88. The ground copper foil G1 is a reflow reference for the devices and pins in the sensitive area K1, the pads in the sensitive area K1, the signal routing and vias, and the power routing and vias. The sensitive area K1 of the PCB board 88 is separated from the motor drive area K2 (the motor drive area K2 is a strong interference source area). The motor drive area K2 is provided with an external power positive cable 331, an external power positive cable 331, an electrolytic capacitor 19, an upper MOSFET 74 + a lower MOSFET 75, an upper MOSFET 72 + a lower MOSFET 73, and an upper MOSFET 70 + a lower MOSFET 71.

[0191] One end of the external power positive cable 331 is electrically connected to the positive pole "+" of the battery 500, and the other end of the external power negative cable 341 is electrically connected to the positive pin 36 of the electrolytic capacitor 19 through the power copper foil 42, and the power copper foil 42 is electrically connected to the drain pin D5 of the upper MOSFET 74, the drain pin D3 of the upper MOSFET 72, and the drain pin D1 of the upper MOSFET 70. One end of the external power supply negative cable 341 is electrically connected to the negative electrode "-" of the battery 500, and the other end of the external power supply negative cable 341 is electrically connected to the negative electrode pin 37 of the electrolytic capacitor 19 through the second layer of ground copper foil G2, and the second layer of ground copper foil G2 is electrically connected to the source pin S5 of the lower tube MOSFET75 through the ground hole 302 (at least one ground hole), and the second layer of ground copper foil G2 is electrically connected to the source pin S4 of the lower tube MOSFET73 through the ground hole 301 (at least one ground hole), and the second layer of ground copper foil G2 is electrically connected to the source pin S2 of the lower tube MOSFET71 through the ground hole 300 (at least one ground hole).

[0192] The motor driver generally uses a three-phase MOSFET drive circuit M1 to drive the motor. Fig.16 The partial circuit diagram of the W-phase MOSFET of the motor driver is given. The drain pin D1 of the upper MOSFET 70 is electrically connected to the positive electrode of the electrolytic capacitor 19 (for energy storage and discharge) through the power copper foil 42, and the positive electrode 36 of the electrolytic capacitor 19 is electrically connected to the positive cable 331 of the external power supply. The negative electrode 37 of the electrolytic capacitor 19 is electrically connected to the negative cable 341 of the external power supply through the ground copper foil G2. The source pin S1 of the upper MOSFET 70 is electrically connected to the drain pin D2 of the lower MOSFET 71 and one end of the external motor cable 313 through the copper foil 33, forming the W-phase of the motor driver. The other end of the external motor cable 313 is electrically connected to the motor 501. The source pin S2 of the lower MOSFET 71 is electrically connected to the negative electrode of the electrolytic capacitor 19 through the ground copper foil G2.

[0193] Assuming that the PCB board is a 4-layer board, and the ground copper foil G2 is set on the second layer of the PCB board 88, and the power copper foil 42 is set on the BOTTOM layer and / or the third layer of the PCB board 88, the projection of the power copper foil 42 of the BOTTOM layer and / or the third layer on the second layer of the PCB board 88 must completely fall within the range of the ground copper foil G2 and cannot exceed the range of the ground copper foil G2, that is, the projection of the ground copper foil G2 on the BOTTOM layer and / or the third layer must completely cover the power copper foil 42. The ground copper foil G1 is set on the second layer of the sensitive area K1 (the sensitive area K1 is arranged with the LTE module 15, IOTMCU, GPS antenna 14, audio module 205, Bluetooth module, etc.), and the ground copper foil G1 is used as the return path for the sensitive area K1 devices, power traces, signal traces, power vias, and signal vias. It is required that the projection of the components (such as LTE module 15, IOTMCU, GPS antenna 14, audio module 205, Bluetooth module, etc.) and pins in the sensitive area K1, the pads, signal vias, power vias, power traces, signal traces, etc. of the components in the sensitive area K1 on the second layer of the PCB board 88 should completely fall within the scope of the ground copper foil G1 and should not exceed the scope of the ground copper foil G1. That is, the ground copper foil G1 of the second layer should completely cover the components (such as LTE module 15, IOTMCU, GPS antenna 14, audio module 205, Bluetooth module, etc.) and pins in the sensitive area K1 of the TOP layer and the BOTTOM layer, the pads, signal vias, power vias, power traces, signal traces of the components in the sensitive area K1, and the pins (such as plug-in pins) in the sensitive area K1 of the third layer, the pads, signal vias, power vias, power traces, signal traces, etc. of the components in the sensitive area K1. The components (such as LTE module 15, IOTMCU, GPS antenna 14, audio module 205, Bluetooth module, etc.) and pins in the sensitive area K1 of the TOP layer and the BOTTOM layer, the pads, signal vias, power vias, power traces, signal traces of the components in the sensitive area K1, and the pins (such as plug-in pins) in the sensitive area K1 of the third layer, the pads, signal vias, power vias, power traces, signal traces of the components in the sensitive area K1 of the second layer cannot be connected. The ground copper foil G2 overlaps in the direction perpendicular to the PCB board 88, so that the layers projected on the ground copper foil G2 and the motor-related power copper foil, routing, vias, pins, pads and sensitive area K1 can be prevented from overlapping, and the layers projected on the ground copper foil G2 and the motor-related power copper foil, routing, vias, pins, pads can be prevented from interfering with the components and pins of the sensitive area K1, the component pads of the sensitive area K1, signal vias, power vias, power routing, signal routing, etc. through strong pulse electric fields and pulse magnetic fields. (Important technical features, layout requirements)

[0194] like Fig.18As shown, the ground copper foil G1 set in the sensitive area K1 and the ground copper foil G2 related to the motor 501 are not directly grounded (for example, one of the solutions: single-point connection through the negative pole of the electrolytic capacitor 19, and no electrical connection at other positions, etc.), so the noise generated by the ground copper foil G2 related to the motor 501 cannot be directly transmitted to the ground copper foil G1 in the sensitive area K1, so the ground copper foil G1 in the sensitive area K1 is clean and does not affect the normal operation of the components, pins, signals, and power supply in the sensitive area K1. However, there is no high voltage difference between them, so there is no electrical breakdown safety problem between the ground copper foil G1 in the sensitive area K1 and the ground copper foil G2 related to the motor 501. The distance of the gap 800 between the ground copper foil G1 in the sensitive area K1 and the ground copper foil G2 related to the motor 501 is L20, and L20 only needs to meet the minimum processing distance of the PCB manufacturer, for example, L20≧0.127mm (5mil), preferably L20=6mil, L20<20mm. The smaller the distance L20 between the ground copper foil G1 of the sensitive area K1 and the ground copper foil G2 associated with the motor 501, the smaller the pulse electric field and pulse magnetic field leaked from the gap 800 between the ground copper foil G1 of the sensitive area K1 and the ground copper foil G2 associated with the motor 501. When L20 = 6 mil, the pulse electric field and pulse magnetic field are basically within the controllable range, and the leakage from the gap 800 between the ground copper foil G1 of the sensitive area K1 and the ground copper foil G2 associated with the motor 501 will neither affect the normal operation of the GPS antenna 14 nor interfere with the normal operation of the LTE antenna 17 / Bluetooth antenna 117 set on the inner wall surface A1 of the plastic top shell 18.

[0195] Continue reading Fig.16 , Fig.17 In the scheme shown, when the upper MOSFET 70 is turned on and the driving motor 501 is working (the lower MOSFET 71 is turned off), a pulse current will be generated in the power copper foil 42 and the copper foil 33, and a reverse power supply i1 will be generated in the ground copper foil G2. At the same time, a magnetic field B1 will be generated in the power copper foil 42, the copper foil 33, and the power circuit of the upper MOSFET 70. When the upper MOSFET 70 is turned off, the lower MOSFET 71 is turned on, and a pulse current will be generated in the copper foil 33, and a reverse power supply i2 will be generated in the ground copper foil G2, and a magnetic field B2 will be generated in the power circuit. Since the area of ​​the ground copper foil G2 set on the second layer is greater than or equal to the power copper foil 42, and the projection of the power copper foil 42, the copper foil 33, and the upper MOSFET 70 on the second layer is completely covered by the ground copper foil G2, that is, the magnetic field B1 generated in the power copper foil 42, the copper foil 33, and the power circuit of the upper MOSFET 70 is limited to this very narrow loop, and the magnetic field generated by external radiation is very small. The specific analysis is as follows:

[0196] Table 3 shows the stacking structure of a 4-layer through-hole board. If the thickness H6 of the entire PCB is calculated as 1.2mm (67.244mil), the thickness between the TOP layer and the 2nd layer and the thickness between the 3rd layer and the BOTTOM layer are given by the industry as 4mil, that is, the PP thickness H1 between the TOP layer and the 2nd layer is 4mil, and the PP thickness H3 between the 3rd layer and the BOTTOM layer is 3mil. The core thickness between the L2 layer and the L3 layer is set to 33.6mil, the TOP layer and the BOTTOM layer are the surface layers, and the surface copper thickness is 1.59mil; the 2nd and 3rd layers are the inner layers, and the inner copper thickness is 1.2mil. The ink thickness covering the TOP layer and the BOTTOM layer is 0.4mil.

[0197] When the power copper foil 42 and the copper foil 33 are arranged on the second layer, the projection position of the power copper foil 42 and the copper foil 33 on the TOP layer must be set to the ground copper foil G2, and the power copper foil 42 and the copper foil 33 are prohibited from being arranged on the TOP layer to prevent the power copper foil 42 and the copper foil 33 from generating pulse magnetic field and pulse electric field to the outside world on the TOP layer, thereby interfering with the LTE antenna 17 and the Bluetooth antenna 117 on the inner wall surface A1 of the plastic top shell 18.

[0198] When the power copper foil 42 and copper foil 33 are arranged on the second layer, the ground copper foil G2 is arranged at the projection position of the power copper foil 42 and copper foil 33 on the TOP layer, and the PP thickness of the power copper foil 42 and copper foil 33 of the second layer to the ground copper foil G2 of the TOP layer is 4 mil (about 0.1 mm), that is, the spacing between the power copper foil 42 and copper foil 33 of the second layer and the ground copper foil G2 of the TOP layer is 4 mil (about 0.1 mm).

[0199] Combined with Table 1, Fig.16 , Fig.17 As shown, when the upper MOSFET 70 is turned on and the motor is driven (the lower MOSFET 71 is turned off), a pulse current will be generated in the power copper foil 42 and copper foil 33, and a reverse power supply i1 will be generated in the ground copper foil G2. A magnetic field B1 will be generated in the power copper foil 42, copper foil 33, and the power circuit of the upper MOSFET 70. The pulse magnetic field radiated outward in the very narrow power loop with a limited spacing of 4 mil (about 0.1 mm) is almost negligible. The operating frequency of the motor driver is relatively low (the main frequency is 10KHz to 25KHz, preferably 16KHz), and is not in the same frequency band as the LTE antenna 17 and the Bluetooth antenna 117. The very small amount of multiple harmonics leaked from the power copper foil 42 and copper foil 33 will cause negligible interference to the LTE antenna 17 and the Bluetooth antenna 117.

[0200] When the upper MOSFET 70 is turned off, the lower MOSFET 71 is turned on, which will generate a pulse current in the copper foil 33, generate a reverse power supply i2 in the ground copper foil G2, and generate a magnetic field B2 in the power loop. In a very narrow power loop with a limited spacing of 4 mil (about 0.1 mm), the pulse magnetic field radiated outward is almost negligible. The operating frequency of the motor driver is relatively low (the main frequency is 10KHz to 25KHz, preferably 16KHz), and is not in the same frequency band as the LTE antenna 17 and the Bluetooth antenna 117. The very small amount of multiple harmonics leaking out of the copper foil 33 can cause negligible interference to the LTE antenna 17 and the Bluetooth antenna 117.

[0201] More specifically, the power copper foil 42 is taken as an example to be arranged in a straight line in the horizontal direction of the second layer. The horizontal length of the power copper foil 42 from point a to point b in the second layer is L50 (eg Fig.17 As shown in FIG. 1 , the distance from the power copper foil 42 in the second layer to the ground copper foil G2 in the TOP layer is H50, and the return area from the power copper foil 42 in the second layer to the ground copper foil G2 in the TOP layer is S1=h50×L50. According to the magnetic field strength calculation formula: B=Φ / S, the magnetic field generated by the power copper foil 42 in the second layer to the ground copper foil G2 in the TOP layer is B2=Φ / S1=Φ / h50×L5.

[0202] Table 3 Stacking structure of 4-layer through-hole board with a thickness of 1.2 mm

[0203]

[0204] Continue to see Fig.18 When the upper MOSFET 70 is turned on (the lower MOSFET 71 is turned off), the second layer of power copper foil 42 generates a pulse electric field E5 to the ground copper foil G2 of the TOP layer, and the second layer of power copper foil 42 generates a pulse electric field E1 to the ground copper foil G1 of the second layer (the ground copper foil G1 belongs to the sensitive area K1).

[0205] When the lower MOSFET 71 is turned on (the upper MOSFET 70 is turned off), the copper foil 33 generates a pulse electric field E2 to the ground copper foil G2 of the TOP layer.

[0206] According to the electric field strength calculation formula: E = U / d.

[0207] Where d is the distance H5 between the second power copper foil 42 and the ground copper foil G2 of the TOP layer. The pulse electric field E1 = U1 / d = U1 / H5 generated by the second power copper foil 42 on the ground copper foil G2 of the TOP layer.

[0208] Since the projection of the second power copper foil 42 on the TOP layer falls within the area of ​​the ground copper foil G2, and the distance between the second power copper foil 42 and the TOP ground copper foil G2 is only 4 mil (about 0.1 mm), the pulse electric field generated by the second power copper foil 42 to the TOP ground copper foil G2 is limited to a very small space of 4 mil (about 0.1 mm), and the pulse electric field radiated externally is almost negligible. The operating frequency of the motor driver is relatively low (the main frequency is 12KHz to 25KHz, preferably 16KHz), and is not in the same frequency band as the LTE antenna 17 and the Bluetooth antenna 117. The very small amount of multiple harmonics leaked from the copper foil 33 can cause negligible interference to the LTE antenna 17 and the Bluetooth antenna 117.

[0209] Where d is the distance H5 between the second copper foil 33 and the ground copper foil G2 of the TOP layer. The pulse electric field E2 = U3 / d = U2 / H5 generated by the second copper foil 33 on the ground copper foil G2 of the TOP layer.

[0210] Since the projection of the second copper foil 33 on the TOP layer falls within the area of ​​the ground copper foil G2, and the distance between the second copper foil 33 and the TOP ground copper foil G2 is only 4 mil (about 0.1 mm), the pulse electric field generated by the second copper foil 33 to the TOP ground copper foil G2 is limited to a very small space of 4 mil (about 0.1 mm), and the pulse electric field radiated externally is almost negligible. The operating frequency of the motor driver is relatively low (the main frequency is 12KHz to 25KHz, preferably 16KHz), and is not in the same frequency band as the LTE antenna 17 and the Bluetooth antenna 117. The very small amount of multiple harmonics leaked from the copper foil 33 can cause negligible interference to the LTE antenna 17 and the Bluetooth antenna 117.

[0211] The following introduces the leakage relationship analysis between pulse electric field and pulse magnetic field (shielding energy efficiency calculation method)

[0212] The leakage relationship between pulse electric field and pulse magnetic field is analyzed as follows:

[0213] For 30MHz electromagnetic waves (i.e. pulse electric field, pulse magnetic field), 100dB attenuation effect can be achieved. However, there is a gap 800 between the ground copper foil G1 of the sensitive area K1 and the ground copper foil G2 related to the motor 501. The gap 800 is related to the half-wave resonant slot antenna. The shielding effectiveness SE is related to the maximum size d of the gap 800 and the electromagnetic wave wavelength λ as follows:

[0214] SE = 20log(λ / 2d);

[0215] For example: for 30MHz, the wavelength is 10m, assuming the gap 800 is 10mm long, the converted SE is 54dB. The larger d is, the smaller SE is.

[0216] The approximate relationship between pores (gap), frequency, and shielding effectiveness SE:

[0217] Shielding Effectiveness (SE for short). Fig. 20 A curve diagram showing the relationship between the pore size and SE is given. Fig. 20 The middle coordinate C means that for 1 GHz electromagnetic waves, to achieve a SE of 40 dB (conventional for civilian use), the pore (gap) must be less than 1.6 mm. Fig. 20 The middle coordinate D means that for 1 GHz electromagnetic waves, to achieve a SE of 20 dB, the pore (gap) must be less than 16 mm.

[0218] like Fig.19 As shown, the gap 800 between the TOP layer and / or the second layer ground copper foil G2 and the ground copper foil G1 of the sensitive area K1 has a width of L21 and a length of L50. Since L50 is obviously larger than L21, the d in the formula SE=20log(λ / 2d) should be calculated based on the length L50.

[0219] The power copper foil 42 and copper foil 33 are set on the BOTTOM layer and / or the third layer of the PCB board 88. Attention should be paid to the distance between the power copper foil 42, copper foil 33 and the TOP layer and / or the second layer of the ground copper foil G2, and the distance between the power copper foil 42, copper foil 33 and the ground copper foil G1 of the sensitive area K1 and the ground copper foil G2 related to the motor 501, where there is a gap 800.

[0220] The following is an introduction to the power supply system in the motor drive (involving the integrity of the power supply system, EMI radiation and conduction, RF stray, and capacitor selection)

[0221] Fig.21 The composition of the three-phase MOSFET motor drive circuit and power supply system is given. Fig.21The power supply system model of the motor drive circuit is given. The battery 500 is electrically connected to the upper MOSFET 70, the upper MOSFET 72, and the upper MOSFET 73 through a relatively long external power positive cable 331 and an external power negative cable 341, respectively. The upper MOSFET 70 and the lower MOSFET 71 form a W phase, the upper MOSFET 72 and the lower MOSFET 71 form a V phase, and the upper MOSFET 72 and the lower MOSFET 71 form an H phase, that is, the battery 500 is very far away from the upper MOSFET 70, the upper MOSFET 72, and the upper MOSFET 74 in the PCB board 88, and the battery 500 cannot quickly connect to the upper MOSFET 70. , upper MOSFET 72, and upper MOSFET 74 provide instantaneous dynamic large current discharge. A large-capacity input capacitor 19 (energy storage capacitor) is connected in parallel near the upper MOSFET 70, upper MOSFET 72, and upper MOSFET 74 on the PCB board 88 to provide the Δi current required for instantaneous dynamic discharge to the three-phase motor drive circuit M1. In addition, it is recommended to connect one or two small-capacity, low-ESL (ESL is the crosstalk equivalent inductance, a distributed parameter of the capacitor), low-ESR (ESR is the crosstalk equivalent resistance, a distributed parameter of the capacitor) capacitors 399 in parallel with the input capacitor 19 to provide a low-impedance path for high-frequency current and reduce power supply noise and ripple. BULK capacitors are generally aluminum capacitors. High-frequency capacitors are generally ceramic capacitors, also known as sheet ceramic capacitors or sheet capacitors.

[0222] The power supply system of the three-phase motor drive circuit M1 requires to ensure that the voltage V1 fluctuation is within the allowable range. Power supply requirements: ideal voltage source V1, no matter how large the output current is, the power supply voltage V1 of the three-phase motor drive circuit M1 remains unchanged. Actual battery 500, external power positive cable 331 ( Fig. 22 L80 in the figure is the series equivalent inductance of the external power supply positive cable 331), the external power supply negative cable 341 ( Fig. 22 L81 is the series equivalent inductance of the positive cable 341 of the external power supply), the power copper foil 42, etc. all have internal resistance. Therefore, when the current absorbed by the three-phase motor drive circuit M1 jumps, a changing voltage will inevitably be generated on the internal resistance, which also manifests as corresponding fluctuations. After adding capacitance, the input capacitor 19 and capacitor 399 are similar to a power supply at the moment of discharge, but there are also impedances in the form of ESR (series equivalent resistance) and ESL (series equivalent inductance), which produce a voltage drop in the discharge impedance, causing fluctuations in the power supply of the three-phase motor drive circuit M1. Fig.21The power supply system model of the motor drive circuit is given. The input capacitor 19 model is mainly composed of a series equivalent inductance L82 (series equivalent inductance is also called parasitic inductance), a series equivalent resistance R1, and an actual capacitance value C1, while the capacitor 399 is mainly composed of a series equivalent inductance L83, a series equivalent resistance R2, and an actual capacitance value C2.

[0223] The power distribution system of the power supply system model of the three-phase motor drive circuit M1 is mainly divided into five components: DC power supply (battery 500), external power cable (external power positive cable 331, external power negative cable 341), energy storage capacitor (input capacitor 19), capacitor (capacitor 399, also known as electrolytic capacitor), and PCB plane capacitor (PCB plane capacitor 889).

[0224] Input capacitor 19 (energy storage capacitor) generally uses aluminum capacitors for medium and low frequency energy storage and filtering, providing the Δi current required for instantaneous dynamic discharge for the three-phase motor drive circuit M1. Capacitor 399 can be a ceramic capacitor to supplement the fast flipping current of the three-phase motor drive circuit M1 and filter relatively high frequency noise.

[0225] The operating current in the three-phase motor drive circuit M1 is Δi, and the causes of noise in the power supply system are analyzed as follows:

[0226] Δi=C·dV / dt≈C·△V / △t

[0227] Among them, △V=(Voh-Vol)·90%-(Voh-Vol)·10%=0.8(Voh-Vol); and △t is the rise time Tr of the three-phase motor drive circuit M1 after flipping. C is the equivalent capacitance of the load of the three-phase motor drive circuit M1. The dynamic power consumption of the three-phase motor drive circuit M1 also includes the power consumption caused by the flip crossover current of the three-phase motor drive circuit M1, the flip current of the three-phase motor drive circuit M1, etc. These instantaneous currents are prone to cause power supply noise. The noise generated by the power supply system will cause the conduction and / or radiation indicators of the product EMI to exceed the standard.

[0228] The purpose of power supply filtering of the three-phase motor drive circuit M1 is to ensure that the voltage fluctuation of the device is small enough in the entire operating frequency range. The realization idea of ​​power supply filtering is to provide a sufficiently low loop impedance for the power supply of the three-phase motor drive circuit M1, so the unique impedance characteristics of the capacitor can be used to achieve this purpose.

[0229] Because the power supply paths when the power supply jumps instantly are:

[0230] PCB plane capacitor 899 → capacitor 399 → input capacitor 19 → external power supply positive cable 331 / external power supply negative cable 341 → battery 500.

[0231] In the above system, the energy for the three-phase motor driving circuit M1 to flip is provided by the capacitor between the power supply and the ground plane.

[0232] The following introduces the selection considerations of the input capacitor 19 at the power supply end of the three-phase motor drive circuit.

[0233] For the selection of input capacitor 19, aluminum capacitors are generally used. The following introduces various characteristics of aluminum capacitors: At low frequencies, aluminum capacitors are determined by 1 / WC. Since the capacity of electrolytic capacitors can be made very large, aluminum capacitors are widely used in low-frequency filtering situations; at tens of kHz to hundreds of kHz, it is determined by ESR; at 100kHz / 25℃, the ESR value of aluminum capacitors is generally tens of mΩ to 2.5Ω, and the LowESR model is generally tens of mΩ. The ESR value changes with temperature. Generally, from 25℃ to the high temperature limit, the ESR will drop by about 35% to 50%; and from 25℃ to the low temperature limit, the ESR will increase by 10 to 100 times; Fig.23The impedance characteristic curve of aluminum capacitor is given. Aluminum capacitor has a large ESR, and its impedance frequency characteristic curve is generally U-shaped, unlike ceramic capacitor, which has a V-shaped curve with a clear downward tip at the resonant frequency point due to its small ESR. At MHz, aluminum capacitor is determined by WL, and the ESL of ordinary aluminum capacitor is relatively large, which greatly limits its application at high frequencies. The parasitic series inductance value ESL of aluminum capacitor is relatively stable and does not change with frequency and temperature. For general aluminum capacitor, ESL will not exceed 100nH, such as SMT packaging, its value is in the range of 2nH to 8nH; radial plug-in 10nH to 30nH; spiral (screw-terminal): 20nH to 50nH; and axial plug-in packaging, its value can reach 200nH; the high ESR value and large ESL limit the application of aluminum capacitors in high frequency occasions. The impedance frequency amplitude curve of aluminum capacitors is determined by 1 / WC at low frequencies. Due to the large capacity, aluminum capacitors are widely used in low-frequency filtering. At a few kHz to hundreds of kHz, it is determined by ESR. When aluminum capacitors are used for filtering, their capacity should not be too small. On the one hand, if the capacity is too small, its life span is short at high temperatures; on the other hand, the large capacity characteristics of electrolytic capacitors are not brought into play; from the comparison with other capacitor characteristics, pay attention to the influence of temperature and frequency on capacity, as well as the working voltage and installation process requirements of the occasion of use. However, if used for filtering, its capacity requirements are not strict, and it is required to be as large as possible, so as to reduce ESR. Due to the large ESL restrictions and capacity considerations, the upper limit of the use frequency of aluminum capacitors cannot be very high. It is generally believed that it is not suitable for use above 200kHz. At present, the switching frequency of most power modules is above several hundred kHz, so aluminum capacitors are not suitable for output filtering of high-frequency switching power supplies. The reliability of aluminum capacitors focuses on temperature, but in actual use, volatilization and drying only affect small-volume (small-capacity) aluminum capacitors (less electrolyte) running in high-temperature situations (in high-temperature situations greater than 75°C, small-sized aluminum capacitors should be used as little as possible), while for large-capacity aluminum capacitors, in most applications (except for ESR, ripple capacitance, which causes excessive temperature rise, or high ambient temperature), drying failure will not occur within 10 to 20 years. In addition, the capacitance of aluminum capacitors is generally from 0.1μF to 3F, and the working voltage is from 5V to 500V. From 25°C to the high temperature limit, the capacity increases by no more than 5%. For -40°C limit capacitors, at -40°C, the low-voltage capacitor capacity will drop by 20%, and the high-voltage capacitor will drop by as much as 40%; in the temperature range of -20°C to 40°C, the capacity drops fastest. For -55°C limit capacitors, at -40°C, the drop is usually more than 10%, and at -55°C, it does not exceed 20%.The reliability of aluminum capacitors mainly focuses on temperature, because the electrolyte of aluminum capacitors is liquid, and the heating of the core will cause the electrolyte to volatilize, and eventually dry up and fail in the long run. When the capacitor is used in a pulse AC circuit, the loss and heat generated by the ripple current flowing through the ESR will seriously affect the service life of the device. Based on the above characteristics of aluminum capacitors, the following usage suggestions are given: A. In high temperature occasions greater than 65°C, small-sized aluminum capacitors should be used as little as possible; try to choose specifications with larger capacity to give full play to the advantages of aluminum capacitors; B. Pay attention to the ripple current at high temperature not to exceed the use specifications, especially for small-volume / small-capacity aluminum capacitors; use the expected life calculation formula to evaluate whether the use of capacitors is suitable; C. Aluminum capacitors are suitable for power frequency rectification smoothing filtering, switching power supplies and output filtering of ordinary switching power supply modules.

[0234] The operating frequency of the motor driver is relatively low, with the main frequency being between 10KHz and 25KHz (preferably 16KHz), which is just within the operating bandwidth range of aluminum capacitors from a few kHz to hundreds of kHz.

[0235] The following introduces the selection considerations of capacitor 399 at the power supply end of the three-phase motor drive circuit.

[0236] Capacitor 399 generally adopts ceramic capacitor (MLCC, Multi-layer Ceramic Capacitors, chip multilayer ceramic capacitor). The various characteristics of ceramic capacitors are introduced below: the first type of ceramic capacitor (NP0 or COG), the capacity ranges from 0.5pF to 68000pF, with high stability, basically not changing with temperature, voltage and time; the second type of ceramic capacitor (X7R / X5R), the capacity ranges from 100pF to 22μF (X5R can reach 100μF), but when the temperature changes from -55℃ to 125℃, the capacity change is generally ±10%, (X5R can reach a maximum of ±15% to -25%); the third type of ceramic capacitor (Z5U), a commonly used large-capacity capacitor product, has poorer stability than X7R, with a capacity ranging from 0.47μF to 22μF (can be larger), but the capacity and loss are more sensitive to temperature, voltage, etc., and the stability is poor. When the temperature changes from -25℃ to 85℃, the capacity changes from +20% to -65%. The ESR of ceramic capacitors ranges from a few mΩ to several hundred mΩ. The smaller the capacity, the greater the ESR. ESR changes linearly with temperature. For X7R dielectric, the ESR is 20% of room temperature at 125°C and more than three times of room temperature at -55°C. NP0 is relatively stable, with a coefficient of variation of about 1 / 3 of X7R. The ESL of ceramic capacitors varies with the package. Generally, the ESL of 0603 and 0805 packages is about 1.5 to 1.8 nH under good wiring conditions. 1206 and 1210 are about 1.8 to 2 nH. Due to the small ESR of ceramic capacitors, there will be an obvious downward tip at the resonant frequency point and present a V shape. In the 0402 package, the impedance of 0.1uF ceramic capacitors is lower than that of 0.01uF capacitors in all frequency bands. Figure 24-Figure 30 These are the impedance frequency curves of ceramic capacitors with different capacitance values. Figure 24-Figure 30 As shown, the impedance frequency characteristic curve of ceramic capacitors is V-shaped. Fig.24 The impedance frequency curve of a 10pF ceramic capacitor is given. The lowest point of the impedance frequency curve represents the self-resonance frequency. The self-resonance frequency of a 10pF ceramic capacitor is about 2.8GHz, and the impedance at the self-resonance frequency is 400mΩ, at which point the impedance is minimum. Before the self-resonance point, the capacitor is capacitive, and beyond the self-resonance point, the capacitor gradually becomes inductive. Fig.25 The impedance frequency curve of a 30pF ceramic capacitor is given. The self-resonance frequency of the 30pF ceramic capacitor is about 1.67GHz, and the impedance at the self-resonance frequency is 89mΩ, at which point the impedance is minimum. Before the self-resonance point, it is capacitive, and beyond the self-resonance point, the capacitor gradually becomes inductive. Fig.26 The impedance frequency curve of a 100pF ceramic capacitor is given. The self-resonance frequency of the 100pF ceramic capacitor is about 1.25GHz, and the impedance at the self-resonance frequency is 89mΩ, at which point the impedance is minimum. Before the self-resonance point, it is capacitive, and beyond the self-resonance point, the capacitor gradually becomes inductive. Fig. 27 The impedance frequency curve of a 1nF ceramic capacitor is given. The self-resonance frequency of a 1nF ceramic capacitor is about 420MHz, and the impedance at the self-resonance frequency is 280mΩ, at which point the impedance is minimum. Before the self-resonance point, the capacitor is capacitive, and beyond the self-resonance point, the capacitor gradually becomes inductive. Fig.28 The impedance frequency curve of a 10nF ceramic capacitor is given. The self-resonance frequency of the 10nF ceramic capacitor is about 85MHz, and the impedance at the self-resonance frequency is 15mΩ, at which point the impedance is minimum. Before the self-resonance point, it is capacitive, and beyond the self-resonance point, the capacitor gradually becomes inductive. Fig.29 The impedance frequency curve of a 100nF ceramic capacitor is given. The self-resonance frequency of the 100nF ceramic capacitor is about 38MHz, and the impedance at the self-resonance frequency is 34mΩ, at which point the impedance is minimum. Before the self-resonance point, it is capacitive, and beyond the self-resonance point, the capacitor gradually becomes inductive. Fig.30The impedance frequency curve of 1uF ceramic capacitor is given. The self-resonance frequency point of 1uF ceramic capacitor is about 13MHz, and the impedance at the self-resonance frequency point is 15mΩ, at which the impedance is the smallest; before the self-resonance point, it is capacitive, and beyond the self-resonance point, the capacitance gradually becomes inductive. Among them, the impedance of ceramic capacitor at the self-resonance point is the smallest, and at this time it shows the characteristics of resistance, and its absorption effect at the self-resonance point is the best. Ceramic capacitors are widely used in high-frequency filtering, from several MHz to hundreds of MHz / 1GHz. Ceramic capacitors are easily cracked by temperature shock, mainly due to temperature shock during welding, especially wave soldering, and improper rework welding is also the main cause of temperature shock. The characteristic of multilayer ceramic capacitors is that they can withstand greater mechanical pressure, but operations that resist bending and deformation may cause device cracking. Based on the characteristics of the above ceramic capacitors, the use suggestions are given: when wiring a single board, do not place the ceramic capacitor in the stress area, such as the edge of the single board, near the fasteners, etc., to minimize the mechanical stress of the multilayer ceramic capacitor during the process. In addition to the relatively stable NP0 capacitor, the capacitance of X7R capacitor and Z5U capacitor (or Y5V) has the characteristics of changing with temperature and bias voltage.

[0237] Capacitor 399 can be a single capacitor or a combination of multiple capacitors with different capacitances in parallel. Capacitor 399 can select ceramic capacitors with different capacitances to filter out noise in the corresponding frequency bands, so as to suppress the noise in each frequency band from radiating to the three-phase motor drive circuit M1 on the power supply system to interfere with the LTE antenna 17, Bluetooth antenna 117, GPS antenna 14, etc., and reduce external EMI radiation and conduction, and RF spurious.

[0238] The following describes how to add capacitors to each phase of a three-phase motor drive circuit to reduce EMI radiation, stray and interference with various antennas.

[0239] In a conventional three-phase MOSFET motor drive circuit M1, the W phase, V phase, and H phase are electrically connected to the windings in the motor 501 through the motor cable 313, the motor cable 30, and the motor cable 323 respectively. Under normal circumstances, the voltage waveform phases between the W phase, V phase, and H phase in the three-phase MOSFET motor drive circuit M1 need to be staggered by 180 degrees. Therefore, no capacitance is added between the W phase, V phase, H phase, the motor cable 313, the motor cable 30, the motor cable 323 and the motor 501 in the three-phase MOSFET motor drive circuit M1 (adding capacitance will cause a delay, resulting in a phase deviation between the W phase, V phase, and H phase) to affect the phase between them.

[0240] Fig.31 Another three-phase MOSFET motor drive circuit and power supply system is given. Fig.32 Another power supply system model of a motor drive circuit is given. Fig.21 Compare, Fig.31 , Fig.32 The high-frequency capacitor bypass 400, high-frequency capacitor bypass 401, and high-frequency capacitor bypass 402 are added to the W phase, V phase, and H phase, respectively. The operating frequency of the three-phase MOSFET motor drive circuit M1 is 10kHz to 25kHz, which is a very low frequency band. The capacitance of the high-frequency capacitor bypass 400, high-frequency capacitor bypass 401, and high-frequency capacitor bypass 402 is very small (less than or equal to 1nF), and the influence on the W phase, V phase, and H phase in the three-phase MOSFET motor drive circuit M1 is almost negligible, and the capacitances between them are equal, and no phase difference will be generated. The capacitance selection of high-frequency capacitor bypass 400, high-frequency capacitor bypass 401, and high-frequency capacitor bypass 402 cannot affect the operating frequency of the three-phase MOSFET motor drive circuit M1, that is, the operating frequency of the high-frequency capacitor bypass is different from the operating frequency of the motor, but it is necessary to filter out the frequency multiplication interference of high-order harmonics generated by the three-phase MOSFET motor drive circuit M1 to reduce the radiation and stray generated by the three-phase MOSFET motor drive circuit M1 to the outside, and at the same time reduce the interference to the LTE antenna 17, the Bluetooth antenna 117, and the GPS antenna 14.

[0241] High-frequency capacitor bypass 400, high-frequency capacitor bypass 401, and high-frequency capacitor bypass 402 are preferably NP0 material (also called COG material) ceramic capacitors with a capacity ranging from 0.5pF to 68000pF, high stability, and basically no change with temperature, voltage and time; X7R material ceramic capacitors are second choice, with a capacity ranging from 100pF to 22μF, but when the temperature changes in the range of -55°C to 125°C, the capacity changes generally within ±10%. L85 is the series equivalent inductance of the high-frequency capacitor bypass 400, R4 is the series equivalent resistance of the high-frequency capacitor bypass 400, and C4 is the bulk capacitance of the high-frequency capacitor bypass 400; L86 is the series equivalent inductance of the high-frequency capacitor bypass 401, R5 is the series equivalent resistance of the high-frequency capacitor bypass 401, and C5 is the bulk capacitance of the high-frequency capacitor bypass 401; L87 is the series equivalent inductance of the high-frequency capacitor bypass 402, R5 is the series equivalent resistance of the high-frequency capacitor bypass 402, and C5 is the bulk capacitance of the high-frequency capacitor bypass 402. In the high-frequency capacitor bypass 400, the high-frequency capacitor bypass 401, and the high-frequency capacitor bypass 402, ceramic capacitors with small ESL (series equivalent inductance) and ESR (series equivalent resistance) should be selected as much as possible to reduce the influence of ESL (series equivalent inductance) and ESR (series equivalent resistance) on the high-frequency filtering performance.

[0242] The following describes how the power copper foil 42, copper foil 33 and ground copper foil G2 form a PCB flat capacitor.

[0243] Continue to refer to Table 1. Fig.18 , Fig.19 , Fig. 22, taking the example that the power copper foil 42 and copper foil 33 are arranged on the second layer of the PCB board 88, and the ground copper foil G2 and ground copper foil G1 are arranged on the TOP layer, the power copper foil 42, copper foil 33 and ground copper foil G2 form a PCB flat capacitor, and the ESL of the PCB flat capacitor is very small, which can filter out noise up to GHz, so as to reduce the noise radiation generated by the power copper foil 42, copper foil 33 and the spatial interference to the LTE antenna 17, Bluetooth antenna 117, GPS antenna 14 and the like, and at the same time reduce external EMI radiation and conduction, and RF spurious. Taking the example that the power copper foil 42 and the ground copper foil G2 form a PCB flat capacitor 889, L84 is the series equivalent inductance of the PCB flat capacitor 889, and R3 is the series equivalent resistance of the PCB flat capacitor 889. As shown in Table 1, there is PP (prepreg, a sheet-shaped adhesive material synthesized from resin and carrier, that is, glass fiber epoxy resin material, referred to as FR-4 medium) between the power copper foil 42 of the second layer of PCB board 88 and the ground copper foil G1 of the TOP layer. The dielectric constant of FR-4 medium is 3.5 to 4.5. The flat plate capacitor 889 formed between the power copper foil 42 of the second layer of PCB board 88 and the ground copper foil G1 of the TOP layer is as follows:

[0244] C = ε × ε0 × S / d;

[0245] Wherein: the plate capacitor C, unit F; ε is the PP (prepreg, a sheet-like adhesive material synthesized from resin and carrier, that is, glass fiber epoxy resin material, referred to as FR-4 medium) dielectric constant between the power copper foil 42 of the second layer of the PCB board 88 and the ground copper foil G1 of the TOP layer of the PCB board 88. Usually, the dielectric constant of the FR-4 medium is 3.5 to 4.5;

[0246] ε0 is the dielectric constant of vacuum: 8.86×10-12F / m;

[0247] S is the area, that is, the overlapping area between the power copper foil 42 of the second layer of the PCB board 88 and the ground copper foil G1 of the TOP layer. Since the projection of the power copper foil 42 of the second layer on the TOP layer is required to fall within the range of the ground copper foil G1 of the TOP layer, it is sufficient to calculate the area of ​​the power copper foil 42 of the second layer.

[0248] d is the distance between the plates, that is, the distance H50 between the power copper foil 42 of the second layer and the ground copper foil G1 of the TOP layer (e.g. Fig.17 h50), the distance between the plates is in meters;

[0249] The following describes the distance requirements between LTE antennas, Bluetooth antennas, GPS antennas and metal parts.

[0250] The metal side shell 201 is close to A2 of the plastic top shell 18, and the LTE antenna 17 / Bluetooth antenna 117 is kept more than 4 mm away from the metal side shell 201, that is, the metal parts (such as the heat dissipation shell of the metal material, the ground copper foil G1 of the PCB board 88, the LTE module 15, the electrolytic capacitor 19, the external power positive cable 331 / the external power negative cable 341, etc.) must be kept at a distance L8 of more than 4 mm, preferably more than 5 mm, from the LTE antenna 17 / Bluetooth antenna 117. The purpose is to avoid metal parts (such as metal The radiation generated by the LTE antenna 17 / Bluetooth antenna 117 is reflected by the metal parts (such as the heat dissipation shell of the metal material, the ground copper foil G1 of the PCB board 88, the LTE module 15, the electrolytic capacitor 19, the external cable 331 / 341, etc.), which affects the directional pattern and gain and other parameters of the LTE antenna 17 / Bluetooth antenna 117. Therefore, the spacing setting between the metal parts (such as the heat dissipation shell of the metal material, the ground copper foil G1 of the PCB board 88, the LTE module 15, etc.) and the LTE antenna 17 / Bluetooth antenna 117 becomes crucial.

[0251] The following introduces the GPS antenna, LTE antenna, and EMI radiation test data of the whole product.

[0252] The following is a motor electronic control + IOT board solution using a D2pak packaged MOSFET 70 according to an embodiment of the present invention. Figure 4 As shown, the reverse flip-chip D2pak packaged MOSFET 70 and the like are arranged on the BOTTOM layer of the PCB board 88, and the D2pak packaged MOSFET 70 and the like are arranged with a ground copper foil G2 in the projection position K1 area of ​​the TOP layer of the PCB board 88, and the GPS antenna 14 is arranged on the TOP layer of the PCB board 88, and the LTE antenna 17 is arranged on the plastic top shell. The reverse flip-chip D2pak packaged MOSFET 70 is closely contacted with the inner wall surface B1 of the metal bottom shell 200 through the thermal conductive gasket 31, so as to achieve electrical isolation and heat conduction with the metal bottom shell 200, and at the same time, the reverse flip-chip D2pak packaged MOSFET 70 is isolated from the GPS antenna 14 on the TOP layer of the PCB board 88 and the LTE antenna 17 arranged on the plastic top shell through the ground copper foil G2 and spaced apart, so as to avoid the reverse flip-chip D2pak packaged MOSFET 70 and the like from interfering with the GPS antenna 14 and the LTE antenna 17. The metal bottom shell 200 / metal side shell 201 is formed by low-cost extrusion, which not only reduces the cost of the metal shell, simplifies the SMT reflow soldering production process and the assembly production process, but also greatly reduces the thermal resistance between the reverse flip-chip D2pak package MOSFET70 and the metal bottom shell 200 / metal side shell 201, improving the heat dissipation performance. Good performance has been achieved through various tests. The following are specific test details.

[0253] A. Static test of GPS antenna

[0254] Fig.33 The static test of the motor electronic control device (three-phase motor driver + three-phase motor) in a certain open space GPS antenna is given, and the situation of each satellite in the sky that the motor electronic control device can search at a certain time point is given. Fig.33 It can be concluded that there are 9 satellites that meet the C / No value ≧40, while the specification requires 4 or more satellites to meet the C / No value ≧40 for accurate positioning, which far meets this requirement.

[0255] Fig.33 Where "PRN" is the specific GPS satellite number that the motor electronic control device can search for in a certain open location and at a certain point in time, which are: GPS satellite 1, GPS satellite 2, GPS satellite 3, GPS satellite 6, GPS satellite 11, GPS satellite 14, GPS satellite 17, GPS satellite 19, GPS satellite 30, GPS satellite 28, GPS satellite 199, GPS satellite 50, GPS satellite 40, GPS satellite 41; and "BAND" is the corresponding; "AZI" is the corresponding satellite's overhead viewing angle, which are: 43, 249, 52, 271, 244, 157, 5, 329, 195, -, 148, 148, 257, 237; "ELE" is the corresponding satellite's elevation angle, which are: 8, 11, 34, 48, 16, 75, 48, 38, 16, -, 59, 59, 20, 46.

[0256] B. LTE antenna in the whole machine 4 bands transmit and receive active test

[0257] Table 4 LTE antenna in the whole machine 4 band transmission and reception active test data table

[0258]

[0259] As can be seen from Table 4, the transmission test selected 4 LTE Bands: LTEBand1, LTEBand3, LTEBand5, and LTEBand8. Among them, when LTEBand1 selected 18550 channels, the operating frequency was 1975MHz, and the transmission power was 20.90dBm in TRP mode; when LTEBand1 selected 550 channels, the operating frequency was 2165MHz, and the receiving sensitivity was -93.64dBm in TIS mode. When LTEBand3 selected 19900 channels, the operating frequency was 1780MHz, and the transmitting power was 20.07dBm in TRP mode; when LTEBand3 selected 1900 channels, the operating frequency was 1900MHz, and the receiving sensitivity was -93.48dBm in TIS mode. When LTEBand5 selects channel 21750, the operating frequency is 844MHz, and the transmit power is 20.10dBm in TRP mode; when LTEBand5 selects channel 2600, the operating frequency is 889MHz, and the receiving sensitivity is -93.64dBm in TIS mode. When LTEBand8 selects channel 21750, the operating frequency is 910MHz, and the transmit power is 20.91dBm in TRP mode; when LTEBand8 selects channel 3750, the operating frequency is 955MHz, and the receiving sensitivity is -94.68dBm in TIS mode.

[0260] The above test data, regardless of the transmission power in TRP mode or the receiving sensitivity in TIS mode, are within the LTE allowable range and meet the design requirements of motor electronic control equipment.

[0261] C. EMI radiation test

[0262] The EMI radiation test mainly uses the motor driver + fixed rotating motor as an example to explain its performance test. Both the RE radiation test standard and the CE conducted emission test standard adopt the EN55022-2008 / GB9254-2008 standard, and the motor driver is tested in the 0.15MHz~0.5MHz / 0.5MHz~30MHz / 30MHz~1GHz / 1GHz~6GHz frequency bands. These frequency bands meet the Class B test requirements in the EN55022-2008 / GB9254-2008 standard. Fig.34 The radiation values ​​emitted by the motor driver in the test frequency band of 30MHz to 1GHz are given. Fig.34 A refers to the safety limit of the 3C standard. If it is lower than this safety limit, it is qualified; B refers to the fluctuation curve of the radiation data of the tested product. Fig.34 It can be seen that line B is far away from line A and there is a large margin, which is much smaller than the safety standard value, indicating that EMI radiation is well controlled.

[0263] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0264] D. Heat dissipation test verification

[0265] Since the metal shell is exposed to the outside air, it has good convection and radiation heat dissipation conditions. Figure 4 D2pak packaged MOSFET) and metal case (such as Figure 4 The rationality and practicality of the metal bottom shell 200 and the metal side shell 201 in the embodiment of the present invention are as follows: Figure 4 , Fig.18 Taking the motor electronic control device (three-phase motor driver + three-phase motor) as an example, the metal bottom shell 200 has a size of 55mmx140mmx8.5mm, the metal side shell 200 has a size of 140mmx70mm, and the metal bottom shell 200 and the metal side shell 200 are integrally formed. Table 5 shows the operating temperatures of six D2pak packaged MOSFETs of the motor electronic control device under the ambient temperature of 25°C and natural heat dissipation conditions. From the data in Table 5, it can be concluded that MOSFET70, MOSFET71, MOSFET72, MOSFET73, MOSFET74, and MOSFET75 work at a temperature between 53.55℃ and 56.14℃. The motor electronic control equipment is required to work at an ambient temperature of 60℃, and a temperature rise of 35℃ must be added. It can be roughly concluded that the operating temperatures of MOSFET70, MOSFET71, MOSFET72, MOSFET73, MOSFET74, and MOSFET75 are between 88.55℃ and 91.14℃, and the maximum operating temperature of the MOSFET packaged in D2pak is 160℃, that is, all MOSFETs packaged in D2pak can meet the requirements of motor electronic control equipment under an ambient temperature of 60℃, and at the same time meet the mandatory requirements of the national standard QB / T2946-2020 for running at an ambient temperature of 60℃ for 2 hours. This proves that this solution has excellent heat dissipation performance and is scientific and practical.

[0266] Table 5 Operating temperature of 6 D2pak packaged MOSFETs in motor electronic control equipment under ambient temperature of 25°C and natural heat dissipation conditions

[0267] Device number Operating temperature MOSFET70 55.35℃ MOSFET71 56.14℃ MOSFET72 53.55℃ MOSFET73 54.90℃ MOSFET74 56.01℃ MOSFET75 55.05℃

[0268] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that this is only for illustration and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A motor driver, characterized in that: It includes a PCB board and a high-frequency capacitor bypass; the PCB board includes an electronic control device; The electric control device is electrically connected to the motor through the high-frequency capacitor bypass; wherein the operating frequency of the high-frequency capacitor bypass is different from the operating frequency of the motor; The high-frequency capacitor bypass is used to filter out the frequency-multiplied interference of the higher-order harmonics generated by the electronic control device.

2. The motor driver according to claim 1, characterized in that: The high-frequency capacitor bypass includes at least one capacitor connected in parallel: an energy storage capacitor, an electrolytic capacitor, and a PCB plane capacitor; the electronic control device includes a switch tube; The switch tube is connected to the electrolytic capacitor through the power copper foil of the PCB board.

3. The motor driver according to claim 1, characterized in that: The PCB board is a multi-layer PCB board; the motor driver also includes electrical components; the electrical components include at least one of the following: a power module, a Bluetooth module, a GPS module, a GPS antenna, an audio module, an LTE module, an LTE antenna, and a Bluetooth antenna; A ground copper foil is provided in the projection area of ​​the electrical component on the second layer of the PCB board.

4. The motor driver according to any one of claims 1 to 3, characterized in that: An antenna is disposed on the first surface of the PCB board and / or an antenna is disposed above the first surface; The electric control device is arranged on the second surface of the PCB board and is welded on the PCB board.

5. The motor driver according to claim 4, characterized in that: The motor driver also includes a heat-conducting pad and a metal bottom shell for accommodating the electronic control device and the PCB board; The electric control device is attached to the inner wall surface of the metal bottom shell through the heat conductive pad.

6. The motor driver according to claim 4, characterized in that: The insulating shell of the switch tube included in the electric control device is attached to the second surface of the PCB board; The pins of the switch tube are connected to the PCB board.

7. The motor driver according to claim 6, characterized in that: A wiring is arranged in a projection area of ​​the insulating shell attached to the second surface.

8. The motor driver according to claim 6, characterized in that: The motor driver further comprises a driving component, the driving component is disposed on the second surface, and the driving component is electrically connected to the switch tube; The driving component is used to drive the switching tube.

9. The motor driver according to claim 4, characterized in that: The electric control device is provided with a ground copper foil in the projection area of ​​the first surface.

10. The motor driver according to claim 5, characterized in that: The PCB board is fixed to the metal bottom shell by a screw assembly; the creepage distance between the switch tube of the electronic control device and the screw assembly is in the range of 0.2 mm to 0.5 mm; And / or, a creepage distance between an inner wall surface of the metal bottom shell and the electronic control device has a value range of ≧1.0 mm.

11. The motor driver according to claim 4, characterized in that: The antenna includes a GPS antenna; the motor driver also includes a GPS module; The GPS antenna is arranged on the first surface; the GPS module is arranged on the second surface and is located in the projection area of ​​the GPS antenna on the first surface.

12. The motor driver according to claim 5, characterized in that: The motor driver further comprises a plastic top shell and a Bluetooth module; the antenna comprises a Bluetooth antenna; The plastic top shell is used to seal the opening of the metal bottom shell; The Bluetooth module is disposed on the first surface; The Bluetooth antenna is disposed on the inner wall surface of the plastic top shell and is located in the projection area of ​​the Bluetooth module on the plastic top shell; And / or, the antenna further includes an LTE antenna; The LTE antenna and the Bluetooth antenna are arranged on the plastic top shell to intersect vertically.

13. The motor driver according to claim 2, characterized in that: The switch tube comprises an insulating shell, a metal substrate, a wafer and a reverse-molded pin; The wafer is arranged on the metal substrate, and the pin is electrically connected to the wafer; The insulating housing is disposed on the metal substrate; The pins are bent along the sealing plate direction of the insulating outer shell; wherein the sealing plate of the insulating outer shell is arranged opposite to the metal substrate.

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