A compact rudder electronic system and rudder

Abstract

The present invention relates to a compact steering electronic system and a steering gear, including an integrated rigid-flexible printed circuit board; the rigid board area of ​​the rigid-flexible printed circuit board includes a control circuit carrier board, a drive circuit carrier board and a power circuit carrier board; the control circuit carrier board and the drive circuit carrier board are connected through a first flexible board; the drive circuit carrier board and the power circuit carrier board are connected through a second flexible board; by bending the first flexible board and the second flexible board, the installation positions of the control circuit carrier board and the drive circuit carrier board are made parallel, and the installation positions of the power circuit carrier board and the drive circuit carrier board are made vertical, so as to realize the compact installation of the rigid-flexible printed circuit board in the built-in space of the steering gear housing. The present invention adopts a planar design of a rigid-flexible printed circuit board, and a three-dimensional layout after bending, which replaces the internal cable connection, making the structure more compact, occupying less space, and more optimized in processability; saving personnel costs, ensuring quality, and reducing the probability of misoperation.

Description

Technical Field

[0001] The present invention relates to the technical field of steering gears, and in particular to a compact steering electronic system and a steering gear. Background Art

[0002] The physical layout of the mechanical actuators such as motors, reducers, sensors, lead screws, forks, etc. in the servo has resulted in a small and scattered space for the circuit part. The traditional circuit board stacking method does not have a high degree of electromechanical integration, resulting in a low space rate. Due to the particularity of its mechanical structure and the lack of dedicated circuit slots or circuit boxes, it is necessary to consider the connection between the circuit board and the motor sensor, or the connection between the circuit boards. The installation method of plug-in connectors is large in size and requires space for plug-in and unplug operations. Especially in the design of electromechanical products with limited space, how to reasonably use the limited space without making it difficult to produce and install accessories has become a key issue restricting the compactness of the product. Summary of the invention

[0003] In view of the above analysis, the present invention aims to provide a compact steering electronic system and a steering gear, so as to at least partially solve at least one of the above technical problems.

[0004] The technical solution provided by the present invention is:

[0005] The present invention discloses a compact rudder electronic system, comprising an integrated rigid-flexible printed circuit board; the rigid board area of ​​the rigid-flexible printed circuit board comprises a control circuit carrier board, a drive circuit carrier board and a power circuit carrier board;

[0006] The control circuit carrier board and the drive circuit carrier board are connected via a first flexible board; the drive circuit carrier board and the power circuit carrier board are connected via a second flexible board;

[0007] By bending the first flexible board and the second flexible board, the installation positions of the control circuit carrier board and the drive circuit carrier board are made parallel, and the installation positions of the power circuit carrier board and the drive circuit carrier board are made vertical, so as to realize the compact installation of the rigid-flexible printed circuit board in the built-in space of the servo housing.

[0008] Furthermore, the control circuit carrier board and the drive circuit carrier board are both a single rigid circuit board;

[0009] One end of the first flexible board is connected to the edge of the control circuit carrier board, and the other end is connected to the edge of the drive circuit carrier board; the control circuit carrier board is made parallel to the drive circuit carrier board by bending the first flexible board inwards twice by 90 degrees;

[0010] The power circuit carrier board includes four separate power circuit sub-boards with the same structure; the second flexible board includes four L-shaped flexible circuit boards with the same structure;

[0011] One end corresponding to the long sides of the four L-shaped flexible circuit boards is connected to the edge of the driving circuit carrier board, so that the four L-shaped flexible circuit boards are evenly distributed around the driving circuit carrier board; one end corresponding to the short sides of the four L-shaped flexible circuit boards is connected to the edge of the four power circuit sub-boards;

[0012] One end corresponding to the long side of each L-shaped flexible board is bent 90° in the opposite direction of the position of the control circuit carrier board, and one end of the short side is bent inward 90°, so that the four power circuit sub-boards are respectively perpendicular to the drive circuit carrier board, and the spatial positions between the four power circuit sub-boards are cross-shaped.

[0013] Furthermore, it also includes a mounting structure; the mounting structure includes a base, four vertical mounting plates and a horizontal mounting plate;

[0014] The mounting surface of the base is perpendicular to the steering gear housing and parallel to the horizontal mounting plate; the four vertical mounting plates are rectangular metal plates of the same shape; the four vertical mounting plates are respectively mounted between the mounting surface of the base and the horizontal mounting plate, and are kept perpendicular to the mounting surface of the horizontal mounting plate and the base; and the space between the four vertical mounting plates is in a cross shape;

[0015] Each rectangular metal plate is used to fix a power circuit sub-board and is in close contact with the power components on the power circuit sub-board, serving as a heat sink for the power components;

[0016] The horizontal mounting plate is provided with three mounting holes with equal angles and three mounting columns with equal angles and lengths;

[0017] The mounting holes are used to mount the drive circuit carrier board; the mounting posts are used to mount the control circuit carrier board.

[0018] Further, the control circuit carrier board is used to carry the embedded control circuit, sensor conditioning circuit, communication circuit and first power conversion circuit of the rudder electronic system;

[0019] The sensor conditioning circuit is used to condition the sensor acquisition signals including temperature, angle, current and torque to obtain the steering gear sensor signal;

[0020] The embedded control circuit is used to adopt a "one-to-four" control program internally, and generate four-way steering gear control logic including PWM&DIR according to the steering gear sensor signal and the external control signal, which are respectively used to control the movement of the four brushless motors of the steering gear;

[0021] The communication circuit is used to receive external control signals and send status signals of the steering gear to the outside;

[0022] The first power conversion circuit is used to convert an external input voltage to supply power to the circuit units on the control circuit carrier board.

[0023] Furthermore, the embedded control circuit includes a processor STM32G474RET3 and corresponding peripheral circuits;

[0024] The sensor conditioning circuit is a constant current resistance-sensitive sensor signal conditioning circuit, which conditions the sensor signals collected by the resistive RTD temperature sensor, the strain gauge torque sensor and the power resistor bus current sensor;

[0025] The communication circuit includes RS422 and CAN dual communication interfaces.

[0026] Furthermore, the driving circuit carrier board is used to carry the brushless motor driving circuit, the current monitoring circuit and the second power conversion circuit of the steering electronic system;

[0027] The brushless motor drive circuit generates the three-phase drive voltage required for the rotation of the four brushless motors of the steering gear according to the collected brushless motor rotor Hall sensor information and the four-way steering gear control logic output by the embedded control circuit;

[0028] The current monitoring circuit is used to monitor the bus current of the four brushless motors of the servo to obtain current information;

[0029] The second power conversion circuit is used to convert the external input voltage to provide power for the circuit units on the driving circuit carrier board.

[0030] Furthermore, the brushless motor drive circuit includes four identical motor drive sub-circuits; each motor drive sub-circuit uses a drive logic generation chip UCC2626 to generate a three-phase drive voltage required for the rotation of the corresponding brushless motor according to the corresponding brushless motor rotor Hall sensor information and the PWM&DIR steering gear control logic output by the embedded control circuit;

[0031] The current monitoring circuit includes four identical current monitoring sub-circuits; each current monitoring sub-circuit adopts an isolated Σ-Δ modulator AD7403 to monitor the bus current of the corresponding brushless motor.

[0032] Furthermore, each power circuit sub-board is used to carry a three-phase inverter power circuit, a temperature monitoring circuit and a bottom power supply circuit of a brushless motor of the steering electronic system;

[0033] The three-phase inverter power circuit uses a drive tube and a power MOS tube in a DirectFET package to drive and amplify the input three-phase drive voltage and output it to the corresponding brushless motor;

[0034] The temperature monitoring circuit uses a resistive RTD temperature sensor to monitor the heat dissipation and temperature of the power device.

[0035] Furthermore, the first flexible board and the second flexible board are also used as a signal transmission channel between the rigid board areas;

[0036] The first flexible board and the second flexible board include at least three metal conductive layers, wherein the top and bottom layers are metal conductive layers for shielding external electromagnetic interference and avoiding signal distortion caused by signal transmission in the flexible board; the metal conductive layer in the middle layer is used to establish a signal transmission channel between rigid board areas.

[0037] The present invention also discloses a steering gear, comprising the compact steering electronic system as described above.

[0038] The present invention can achieve at least one of the following beneficial effects:

[0039] The present invention adopts the planar design of the rigid-flexible printed circuit board and the three-dimensional layout after bending, replacing the internal cable connection, making the structure more compact, occupying less space, and optimizing the processability;

[0040] The three-dimensional design of rigid-flex printed circuit boards saves assembly time, omits the process of electrical welding and on-site inspection, increases the design assurance ratio of product quality, and weakens the assurance of process; it saves personnel costs, ensures quality, and reduces the probability of misoperation.

[0041] It is conducive to mass production, has high efficiency and high yield rate, and ensures rapid design and rapid assembly, providing strong support for the modernization of equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The drawings are only for the purpose of illustrating specific embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0043] Figure 1 It is a front view schematic diagram of the compact rudder electronic system in this embodiment;

[0044] Figure 2 The figure is a reverse side schematic diagram of the compact rudder electronic system in this embodiment;

[0045] Figure 3 This is a schematic diagram of the structure of a compact rudder electronic system mounting bracket in this embodiment;

[0046] Figure 4 This is an overall assembly diagram of the compact rudder electronic system in this embodiment.

[0047] Reference numerals:

[0048] 1. Control circuit carrier board, 2. Drive circuit carrier board, 3. Power circuit carrier board, 4. First flexible board, 5. Second flexible board, 6. Vertical mounting board, 7. Horizontal mounting board, 71. Mounting column, 72. Mounting hole, 8. Brushless motor, 9. Mounting base. DETAILED DESCRIPTION

[0049] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used to illustrate the principles of the present invention together with the embodiments of the present invention.

[0050] This embodiment discloses a compact rudder electronic system, such as Figure 1 , 2 As shown, it includes an integrated rigid-flexible printed circuit board; the rigid board area of ​​the rigid-flexible printed circuit board includes a control circuit carrier board, a drive circuit carrier board and a power circuit carrier board;

[0051] The control circuit carrier board and the drive circuit carrier board are connected via a first flexible board; the drive circuit carrier board and the power circuit carrier board are connected via a second flexible board;

[0052] By bending the first flexible board and the second flexible board, the installation positions of the control circuit carrier board and the drive circuit carrier board are made parallel, and the installation positions of the power circuit carrier board and the drive circuit carrier board are made vertical, so as to realize the compact installation of the rigid-flexible printed circuit board in the built-in space of the servo housing.

[0053] Specifically, the control circuit carrier board and the drive circuit carrier board are both a whole rigid circuit board;

[0054] The shape and structure of the control circuit carrier board and the drive circuit carrier board can match the shape and structure of the built-in space of the steering gear housing. For example, if the built-in space of the steering gear housing is cylindrical, the control circuit carrier board and the drive circuit carrier board are circular plates; in order to meet the optimal layout and wiring of the circuit boards, the diameters of the control circuit carrier board and the drive circuit carrier board meet the maximum diameter of the built-in space of the steering gear housing to meet the installation tolerance.

[0055] One end of the first flexible board is connected to the edge of the control circuit carrier board, and the other end is connected to the edge of the drive circuit carrier board; after being bent inwards twice by 90 degrees, the control circuit carrier board is made parallel to the drive circuit carrier board;

[0056] The power circuit carrier board includes four separate, structurally identical, rigid power circuit sub-boards; the second flexible board includes four structurally identical L-shaped flexible circuit boards;

[0057] One end corresponding to the long sides of the four L-shaped flexible circuit boards is respectively connected to the edge of the driving circuit carrier board, so that the four L-shaped flexible circuit boards are evenly distributed around the driving circuit carrier board; one end corresponding to the short sides of the four L-shaped flexible circuit boards is respectively connected to the edge of the four power circuit sub-boards; the positions of the four L-shaped flexible circuit boards are distributed in a circle with an interval of 90° relative to the driving circuit carrier board.

[0058] One end corresponding to the long side of each L-shaped flexible board is bent 90° in the opposite direction of the position of the control circuit carrier board, and one end of the short side is bent inward 90°, so that the four power circuit sub-boards are respectively perpendicular to the drive circuit carrier board, and the spatial positions of the four power circuit sub-boards are cross-shaped.

[0059] In order to ensure that the flexible board of the rigid-flexible printed circuit board with a three-dimensional layout does not affect the installation in the built-in space of the servo housing after bending, the edge of the control circuit carrier board connected to the first flexible board and the edge of the drive circuit carrier board connected to the first flexible board and the second flexible board both include an inner groove, and the depth of the inner groove is such that when the first flexible board and the second flexible board are bent, the bent edges do not exceed the depth of the groove.

[0060] In order to ensure the stable installation of the rigid-flexible printed circuit board with a three-dimensional layout after bending, it also includes a mounting structure; Figure 3 As shown, the mounting structure includes a base, four vertical mounting plates and a horizontal mounting plate;

[0061] The mounting surface of the base is perpendicular to the steering gear housing and parallel to the horizontal mounting plate; the four vertical mounting plates are rectangular metal plates of the same shape; the four vertical mounting plates are respectively installed between the mounting surface of the base and the horizontal mounting plate, and remain perpendicular to the mounting surface of the horizontal mounting plate and the base; and the spatial positions of the four vertical mounting plates are cross-shaped; a mounting base is set at the outer corner of the vertical mounting plate that contacts the mounting surface of the base, and a mounting hole is set on the base for fixing the vertical mounting plate on the mounting surface of the base.

[0062] Each rectangular metal plate is provided with a mounting hole for mounting and fixing a power circuit sub-board; and the rectangular metal plate is in close contact with the power element on the power circuit sub-board to serve as a heat sink for the power element; preferably, thermal conductive silicone is applied on the contact surface between the power element and the heat sink to increase the thermal conductivity efficiency.

[0063] The horizontal mounting plate is provided with three mounting holes with equal angles and three mounting columns with equal angles and lengths; the mounting holes are used to mount the drive circuit carrier board; the mounting columns are used to mount the control circuit carrier board; the length of the mounting columns matches the length of the first flexible board.

[0064] The overall assembly diagram of the compact rudder electronic system is as follows: Figure 4 As shown, from top to bottom, there are horizontal control circuit carrier board, drive circuit carrier board, and four vertical power circuit sub-boards; brushless motors and related equipment corresponding to each power circuit sub-board are assembled in four independent spaces surrounded by the mounting base, the power circuit sub-board, and the drive circuit carrier board, so as to realize the compact installation of the steering gear electronic system. And the drive circuit carrier board is placed between the control circuit carrier board and the four power circuit sub-boards, so that the drive circuit carrier board plays an electromagnetic shielding role between the control circuit and the power circuit, and prevents the high-frequency electromagnetic signal when the power circuit is working from interfering with the control signal in the control circuit.

[0065] Preferably, the first flexible board and the second flexible board of the integrally formed rigid-flexible printed circuit board not only serve as a connection between the rigid board areas, but also serve as a signal transmission channel between the rigid board areas;

[0066] The first flexible board and the second flexible board include at least three metal conductive layers, wherein the top and bottom layers are metal conductive layers for shielding external electromagnetic interference and avoiding signal distortion caused by signal transmission in the flexible board; the metal conductive layer in the middle layer is used to establish a signal transmission channel between rigid board areas.

[0067] The three-dimensional layout of the rigid-flex PCB after bending replaces the internal cable connection, making the structure more compact, occupying less space, and optimizing the processability; the three-dimensional design of the rigid-flex PCB saves assembly time, omits the process of electrical welding and on-site inspection, increases the proportion of design assurance of product quality, and weakens the assurance of process; saves personnel costs, ensures quality, and reduces the probability of misoperation.

[0068] Specifically, the control circuit carrier board is used to carry the embedded control circuit, sensor conditioning circuit, communication circuit and first power conversion circuit of the rudder electronic system;

[0069] The sensor conditioning circuit is used to condition the sensor acquisition signals including temperature, angle, current and torque to obtain the steering gear sensor signal;

[0070] The embedded control circuit is used to internally adopt a "one-to-four" control program, and generates four-way steering gear control logic including PWM&DIR according to the steering gear sensor signal combined with the external control signal, which are respectively used to control the movement of the four brushless motors of the steering gear;

[0071] The communication circuit is used to receive external control signals and send status signals of the steering gear to the outside;

[0072] The first power conversion circuit is used to convert an external input voltage to supply power to the circuit units on the control circuit carrier board.

[0073] More specifically, the embedded control circuit includes a processor STM32G474RET3 and corresponding peripheral circuits;

[0074] The processor is the STM32G474RET3 of ST's STM32G4 series, based on the Cortex-M4 core, supporting FPU and DSP instruction sets, with a main frequency of up to 170KHz. The internal FLASH size is 128Kbyte, and the operating temperature range is -40 to 125℃.

[0075] Processor Capability Calculator

[0076] Serial number Software Unit name Running location use Response time 1 Timer interrupt service function ISR_TIMER Main.c Timing 0.5ms, 2ms, 4ms 120us 2 RS422 interrupt service function ISR_RS422 RS422.c Handle RS422 communication tasks 52us 3 CAN interrupt service function ISR_CAN CAN.c Handle CAN communication tasks 44us

[0077] The compiled code is about 120K, the FLASH capacity of the processor MCU is 320K, and the FLASH resource utilization rate is 37.5%; the RAM usage is about 56K, the RAM capacity of the MCU is 128K, and the RAM resource utilization rate is 43.75%.

[0078] The step-down switching power supply chip TPS73633 provides a stable DC voltage of 3.3V for the hardware system. In the TPS73633 linear regulator topology, an NMOS passes a voltage follower configuration element. Using low ESR as a stable output capacitor can even allow the chip to have no capacitors on the periphery, while maintaining a high-precision voltage output and providing a very low dropout voltage and a low-current ground terminal.

[0079] The analog-to-digital acquisition module uses internal high-precision, AD8066.

[0080] The isolation devices include HCPL7851 and ADuM1400. HCPL7851 is used to transmit the secondary voltage of the drive circuit in an isolated manner, and ADuM1400 is used to isolate the motor control quantity and direction signal.

[0081] More specifically, the sensor conditioning circuit is a constant current resistance-sensitive sensor signal conditioning circuit, which conditions sensor signals collected by a resistive RTD temperature sensor, a strain gauge torque sensor, and a power resistor bus current sensor;

[0082] Preferably, in the sensor conditioning circuit, since the sensor signals such as temperature, torque, and power are all resistive, the sensor conditioning circuit can use a stable constant current source to generate a variable voltage for signal acquisition. The high-precision controllable current source used in the present invention is LT3092, which has a maximum output current of 200mA. The current output of 0.5mA to 200mA is set externally through two resistors, and the current regulation performance is 10PPM / V. Taking the temperature sensor as an example, the system uses a Pt1000 platinum resistor as a temperature sensor. The resistance of the platinum resistor changes with the change of temperature, and the change in resistance is converted into a change in voltage, and then the temperature value is calculated. The circuit uses 100KΩ and 1KΩ resistors in conjunction with the LT3092 chip to generate a 1mA current. After the Pt1000 platinum resistor generates a corresponding voltage, the voltage is amplified by 3.5 times. The output voltage range of the first OPA2211 op amp is about 3 to 5.1V. By adding a subtraction circuit, the voltage of AD1 is reduced to 0.5 to 2.6V, which meets the design requirements.

[0083] The communication circuit includes RS422 and CAN dual communication interfaces and software protocols;

[0084] The dual communication interface and software protocol provide better product adaptability. The isolated communication chips are LTM2885 and LTM2889.

[0085] The LTM2885 is a full-duplex isolated RS422 transceiver. A single power supply powers both sides of the interface through an internally integrated isolated, low-noise, high-efficiency 5V output DCDC converter. The maximum data communication rate is 20Mbps, the receiver has a 1 / 8 unit load, and each bus can support up to 256 nodes.

[0086] The LTM2889 is a current-isolated CAN transceiver that also uses an internal DCDC converter to power both sides of the interface and supports flexible data rates up to 4Mbps.

[0087] The first power conversion circuit includes a secondary power conversion and power monitoring circuit.

[0088] Specifically, the power conversion chip LTM8067 for secondary power conversion uses a 9mm*11.25mm*4.92mm BGA package, which includes an isolation transformer, control circuit, power switch and other supporting components. Only a resistor and input and output capacitors are needed to complete the design.

[0089] The LTM8067 operates in the input voltage range of 2.8V to 40V, meeting the requirement of a primary power supply bias of 28V±3.5V. A flyback topology is used internally, and each device can adjust the output voltage to be higher, lower or equal to the input voltage. The LTM8067 has an adjustable output voltage range of 2.5V to 24V, and can provide a load current of up to 450mA from a 5V power supply. The LTC1983-5 charge pump inverter is used to obtain a negative power supply -5V from a 5V power supply, and the DCDC converter LTC1983-5 with a reverse charge pump is used. The chip has an input voltage range of 2.3V to 5.5V, a quiescent current of only 25uA, and can provide a load current of 100mA. It has short-circuit and overheat protection, and an output voltage of -5V, which meets the power supply requirements of bipolar operational amplifiers.

[0090] Power Monitoring LTC2947 has internal monitoring resistors and high-precision power energy monitors, and the internal analog-to-digital converter has 14-bit accuracy. It can measure current, voltage, power, charge, and energy. The voltage measurement range is -30A to 30A, the voltage measurement range is 0 to 15V, and the measurement accuracy is 0.5%. It monitors 6 types of power supplies in the electronic system and uploads them to the external controller in the form of data.

[0091] Power supply load capacity calculation table

[0092]

[0093] Specifically, the driving circuit carrier board is used to carry the brushless motor driving circuit, the current monitoring circuit and the second power conversion circuit of the steering electronic system;

[0094] The brushless motor drive circuit generates the three-phase drive voltage required for the rotation of the four brushless motors of the steering gear according to the collected brushless motor rotor Hall sensor information and the four-way steering gear control logic including PWM&DIR output by the embedded control circuit;

[0095] The current monitoring circuit is used to monitor the bus current of the four brushless motors of the servo to obtain current information;

[0096] The second power conversion circuit is used to convert the external input voltage to provide power for the circuit units on the driving circuit carrier board.

[0097] More specifically, the brushless motor drive circuit includes four identical motor drive sub-circuits; the drive logic generation chip UCC2626 of each motor drive sub-circuit generates the three-phase drive voltage required for the rotation of the corresponding brushless motor according to the corresponding brushless motor rotor Hall sensor information and the PWM&DIR servo control logic output by the embedded control circuit.

[0098] The control chip UCC2626 serves as the control core. It has hardware resources such as Hall signal decoding circuit, triangle wave oscillator and comparator, a current sensing amplifier and absolute value circuit, which simplifies the design of the control circuit. UCC2626 converts the Hall signal received by the rotor position input into six outputs for controlling the external power tube. The triangle wave oscillator and comparison latch can provide voltage or current PWM control. UCC2626 can control the operation mode of the power tube. The internal integrated current amplifier can be used for current closed-loop control. The duty cycle output is precisely controlled. The internal precision oscillator is synchronized with the main clock source.

[0099] The gate drive of the driving power MOS of the brushless motor with Hall in this embodiment adopts STM32 chip, and the output voltage of the pin is 3.3V, which is much lower than the gate opening voltage of MOSFET, and when MOSFET is turned on, the drain-source level is the same, so it is necessary to form the gate-source voltage difference through voltage bootstrapping. At present, the integrated MOSFET driver chip has the following schemes to realize the chip output level to drive MOSFET:

[0100] MOSFET uses a dedicated gate driver chip, such as TI's DRV8353M, DRV10970; Infineon's TLE7189F, IRS23365DM; Allegro's A3946K and A4935K; VISHAY's SI9979. Compared with the DRV835X series, DRV8353M has a new current feedback function, so the MOSFET gate driver of this embodiment uses DRV8353M.

[0101] The current monitoring circuit includes four identical current monitoring sub-circuits; each current monitoring sub-circuit adopts an isolated Σ-Δ modulator AD7403 to monitor the bus current of the corresponding brushless motor.

[0102] The AD7403 isolated Σ-Δ modulator is suitable for precision current and voltage measurement in DC / AC power conversion applications. The higher signal-to-noise ratio enables more accurate current and voltage measurement, improving the performance of the motor drive by reducing torque ripple on the motor shaft.

[0103] The use of isolated Σ-Δ modulators allows the use of smaller shunt resistors, thereby reducing heat loss in the shunt resistors while maintaining measurement accuracy. Main features of the AD7403 isolated Σ-Δ modulator: 5MHz to 20MHz external clock input rate; 16 bits without missing codes; typical offset drift: 1.5uV / ℃; on-chip digital isolator; on-chip reference voltage source; true bipolar analog input range: ±320mV.

[0104] The second power conversion circuit uses LTM8068, which is a series product of TM8067 and adopts 9mm*11.25mm*4.92mmBGA package. Both contain isolation transformer, control circuit, power switch and other supporting components. Only one resistor and input and output capacitors are needed to complete the design. The pin creepage distance and clearance and other features enable these two devices to meet the requirements of the national standard. LTM8068 includes an additional low-noise linear regulator.

[0105] The TM8068 has a low-noise linear regulator at the output with an output voltage range of 1.2V to 18V. The linear regulator reduces the output voltage ripple to 20VRMS at 300mA, thereby improving noise performance when powering high-accuracy signal conditioning and mixed-signal chips. It provides 5V and 15V power for the driver's brushless motor logic chip UCC2626.

[0106] Specifically, each power circuit sub-board is used to carry a three-phase inverter power circuit, a temperature monitoring circuit and a bottom power supply circuit of a brushless motor of the steering electronic system;

[0107] The three-phase inverter power circuit uses a drive tube and a power MOS tube in a DirectFET package to drive and amplify the input three-phase drive voltage and output it to the corresponding brushless motor;

[0108] More specifically, the dual N-MOS tube is integrated in a DirectFET package. DirectFET uses surface mount technology to enable the source and gate to be directly connected to the surface of the silicon wafer. The surface is coated with passivation material for protection, and the position, shape and size of the solder joints between the device and the substrate can be controlled. The use of DirectFET packaging technology realizes high power density application design, and effectively improves the inductance and impedance in terms of thermal and electrical characteristics. DirectFET devices have a variety of shell sizes and device shapes. There are currently 3 sizes: S size 4.88*3.95; M size 6.35*5.05; S size 9.15*7.10. There are 19 products in 3 sizes to choose from, including 7 small-size packages such as ST, SQ, SJ, SH, S1, S2, SB, etc., 9 medium-size packages such as MT, MX, MP, MQ, MN, MZ, MU, M2, M4, etc., and 3 large-size packages such as L4, L6, L8.

[0109] MOSFET Selection Table

[0110]

[0111]

[0112] Among them, the energy storage capacitor of the power MOS tube adopts CAK39H-T3-60150uF-K. CAK39H-T3-60150uF-K is a small-volume, long-life, airtight non-solid electrolyte all-tantalum capacitor with reliability indicators. The size of T2 is 16.28*7.14mm. When the withstand voltage is 60V or 63V, the capacitance reaches 150uF. One is installed on each circuit board, a total of 4, with a total capacitance of 450uF, which meets the design requirements.

[0113] The temperature monitoring circuit uses a resistive RTD temperature sensor to monitor the heat dissipation and temperature of the power device;

[0114] RTD is a passive sensor that requires an excitation current to generate an output voltage. The output level of RTD varies from tens of millivolts to hundreds of millivolts, depending on the RTD selected. AD7124-8 uses a 500uA constant current source. The conversion rate of AD7124-8 is: 192KSPS. Designed for slow applications that require extremely high accuracy, such as temperature and pressure measurement. AD conversion chips with built-in constant current sources include AD7785, AD7793, AD7794, AD7124, and MAX1403. Dedicated thermistor temperature measurement chips: LTC2983, MAX31865.

[0115] The bottom power supply circuit is used to convert the external input voltage to supply power to the circuit units on the power circuit sub-board.

[0116] The bottom power supply cable is shielded with a soft tape, which distributes the external 28V power supply circuit to four "bottom power supply circuits". The shielded soft tape is wrapped by a shielding layer. The normal sudden change of current in the power module will cause electromagnetic compatibility problems. The power MOS tube is sealed by the heat dissipation shell to achieve effective wrapping of electromagnetic signals.

[0117] A specific technical solution of this embodiment also includes a steering gear; the steering gear adopts the compact steering electronic system in the technical solution of the above embodiment as its electronic system, including an integrated rigid-flexible printed circuit board; the rigid board area of ​​the rigid-flexible printed circuit board includes a control circuit carrier board, a drive circuit carrier board and a power circuit carrier board;

[0118] The control circuit carrier board and the drive circuit carrier board are connected via a first flexible board; the drive circuit carrier board and the power circuit carrier board are connected via a second flexible board;

[0119] By bending the first flexible board and the second flexible board, the installation positions of the control circuit carrier board and the drive circuit carrier board are made parallel, and the installation positions of the power circuit carrier board and the drive circuit carrier board are made vertical, so as to realize the compact installation of the rigid-flexible printed circuit board in the built-in space of the servo housing.

[0120] In summary, the compact rudder electronic system and servo disclosed in the embodiment of the present invention adopts the planar design of rigid-flex printed circuit boards, and the three-dimensional layout after bending replaces the internal cable connection, making the structure more compact, occupying less space, and optimizing the processability; the three-dimensional design of the rigid-flex printed circuit board saves assembly time, omits the process of electrical welding and on-site inspection, the design guarantee of product quality becomes more important, and the guarantee of the process is weakened; it saves personnel costs, guarantees quality, and reduces the probability of misoperation. It is conducive to mass production, with high efficiency and high yield, and ensures rapid design and rapid assembly, providing strong support for the modernization of equipment.

[0121] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A compact rudder electronic system, characterized in that: It includes an integrated rigid-flexible printed circuit board; the rigid board area of ​​the rigid-flexible printed circuit board includes a control circuit carrier board, a drive circuit carrier board and a power circuit carrier board; The control circuit carrier board and the drive circuit carrier board are connected via a first flexible board; the drive circuit carrier board and the power circuit carrier board are connected via a second flexible board; By bending the first flexible board and the second flexible board, the installation positions of the control circuit carrier board and the drive circuit carrier board are made parallel, and the installation positions of the power circuit carrier board and the drive circuit carrier board are made vertical, so as to realize the compact installation of the rigid-flexible printed circuit board in the built-in space of the steering gear housing; The control circuit carrier board and the drive circuit carrier board are both a whole rigid circuit board; One end of the first flexible board is connected to the edge of the control circuit carrier board, and the other end is connected to the edge of the drive circuit carrier board; the control circuit carrier board is made parallel to the drive circuit carrier board by bending the first flexible board inwards twice by 90 degrees; The power circuit carrier board includes four separate power circuit sub-boards with the same structure; the second flexible board includes four L-shaped flexible circuit boards with the same structure; One end corresponding to the long sides of the four L-shaped flexible circuit boards is connected to the edge of the driving circuit carrier board, so that the four L-shaped flexible circuit boards are evenly distributed around the driving circuit carrier board; one end corresponding to the short sides of the four L-shaped flexible circuit boards is connected to the edge of the four power circuit sub-boards; One end corresponding to the long side of each L-shaped flexible board is bent 90° in the opposite direction of the control circuit carrier board, and one end of the short side is bent inward 90°, so that the four power circuit sub-boards are respectively perpendicular to the drive circuit carrier board, and the space between the four power circuit sub-boards is in a cross shape; The drive circuit carrier board is placed between the control circuit carrier board and the four power circuit sub-boards, so that the drive circuit carrier board plays an electromagnetic shielding role between the control circuit and the power circuit, preventing the high-frequency electromagnetic signal when the power circuit is working from interfering with the control signal in the control circuit.

2. The compact steering electronic system according to claim 1, characterized in that: Also included is a mounting structure; the mounting structure includes a base, four vertical mounting plates and a horizontal mounting plate; The mounting surface of the base is perpendicular to the steering gear housing and parallel to the horizontal mounting plate; the four vertical mounting plates are rectangular metal plates of the same shape; the four vertical mounting plates are respectively mounted between the mounting surface of the base and the horizontal mounting plate, and are kept perpendicular to the mounting surface of the horizontal mounting plate and the base; and the space between the four vertical mounting plates is in a cross shape; Each rectangular metal plate is used to fix a power circuit sub-board and is in close contact with the power components on the power circuit sub-board, serving as a heat sink for the power components; The horizontal mounting plate is provided with three mounting holes with equal angles and three mounting columns with equal angles and lengths; The mounting holes are used to mount the drive circuit carrier board; the mounting posts are used to mount the control circuit carrier board.

3. The compact steering electronic system according to claim 1, characterized in that: The control circuit carrier board is used to carry the embedded control circuit, sensor conditioning circuit, communication circuit and first power conversion circuit of the rudder electronic system; The sensor conditioning circuit is used to condition the sensor acquisition signals including temperature, angle, current and torque to obtain the steering gear sensor signal; The embedded control circuit is used to adopt a "one-to-four" control program internally, and generate four-way steering gear control logic including PWM&DIR according to the steering gear sensor signal and the external control signal, which are used to control the movement of the four brushless motors of the steering gear respectively; The communication circuit is used to receive external control signals and send status signals of the steering gear to the outside; The first power conversion circuit is used to convert an external input voltage to supply power to the circuit units on the control circuit carrier board.

4. The compact steering electronic system according to claim 3, characterized in that: The embedded control circuit includes a processor STM32G474RET3 and corresponding peripheral circuits; The sensor conditioning circuit is a constant current resistance-sensitive sensor signal conditioning circuit, which conditions the sensor signals collected by the resistive RTD temperature sensor, the strain gauge torque sensor and the power resistor bus current sensor; The communication circuit includes RS422 and CAN dual communication interfaces.

5. The compact steering electronic system according to claim 1, characterized in that: The drive circuit carrier board is used to carry the brushless motor drive circuit, current monitoring circuit and second power conversion circuit of the steering electronic system; The brushless motor drive circuit generates the three-phase drive voltage required for the rotation of the four brushless motors of the steering gear according to the collected brushless motor rotor Hall sensor information and the four-way steering gear control logic output by the embedded control circuit; The current monitoring circuit is used to monitor the bus current of the four brushless motors of the servo to obtain current information; The second power conversion circuit is used to convert the external input voltage to provide power for the circuit units on the driving circuit carrier board.

6. The compact steering electronic system according to claim 5, characterized in that: The brushless motor drive circuit includes four identical motor drive sub-circuits; each motor drive sub-circuit uses a drive logic generation chip UCC2626 to generate a three-phase drive voltage required for the rotation of the corresponding brushless motor according to the corresponding brushless motor rotor Hall sensor information and the PWM&DIR steering gear control logic output by the embedded control circuit; The current monitoring circuit includes four identical current monitoring sub-circuits; each current monitoring sub-circuit adopts an isolated Σ-Δ modulator AD7403 to monitor the bus current of the corresponding brushless motor.

7. The compact steering electronic system according to claim 1, characterized in that: Each power circuit sub-board is used to carry a three-phase inverter power circuit, a temperature monitoring circuit and a bottom power supply circuit of a brushless motor of the steering electronic system; The three-phase inverter power circuit uses a drive tube and a power MOS tube in a DirectFET package to drive and amplify the input three-phase drive voltage and output it to the corresponding brushless motor; The temperature monitoring circuit uses a resistive RTD temperature sensor to monitor the heat dissipation and temperature of the power device.

8. The compact steering electronic system according to any one of claims 1 to 7, characterized in that: The first flexible board and the second flexible board are also used as signal transmission channels between rigid board areas; The first flexible board and the second flexible board include at least three metal conductive layers, wherein the top and bottom layers are metal conductive layers for shielding external electromagnetic interference and avoiding signal distortion caused by signal transmission in the flexible board; the metal conductive layer in the middle layer is used to establish a signal transmission channel between rigid board areas.

9. A steering gear, characterized in that: A compact rudder electronic system comprising the following:

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