Electronic control device and ground line wiring method

Abstract

This electronic control device comprises a plurality of substrates for transmitting signals to each other, and a power source connector for a direct-current power source. A ground line connected to a ground terminal of the power source connector is connected a ground of one of the plurality of substrates to a ground of another substrate. Through this configuration, it is possible to facilitate routing of a ground line and reduce the number of anti-noise components in an electronic control device in which a plurality of substrates are incorporated.

Description

[Technical field]

[0001] The present invention relates to an electronic control device incorporating a plurality of circuit boards, and a method for routing a ground line. [Background technology]

[0002] In an electronic control device incorporating multiple boards, it is necessary to connect the ground of the DC power supply to each board. As a method for connecting the ground of the DC power supply to each board, as described in JP 2019-187077 A (Patent Document 1), a technique has been proposed in which a ground line is branched inside a connector that detachably couples a harness of a DC power supply, and the branched line is connected to the ground of each board. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-187077 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, noise suppression components such as capacitors must be attached to the connection points of the ground line to the board. In the technology where the ground line is branched inside the connector and connected to each board, there are multiple connection points of the ground line to the board, and noise suppression components must be attached to each connection point. In this case, the routing of the ground line in the electronic control device becomes complicated, and the installation of the noise suppression components reduces the mounting space.

[0005] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide an electronic control device and a method for routing a ground line that can reduce the number of noise suppression components while facilitating the routing of the ground line. [Means for solving the problem]

[0006] The electronic control device includes a plurality of circuit boards for transmitting signals between each other, and a power connector for a DC power supply. A ground line connected to the ground line of the power connector is connected to the ground line of another circuit board via the ground of one of the plurality of circuit boards. At the same time, the power terminal of the power connector is connected only to the board to which the ground terminal of the power connector is directly connected. Furthermore, between the multiple boards, a power line that supplies a power supply voltage from one board to the other board, a step-down line that steps down the power supply voltage on the other board and supplies it to one of the boards, and a ground line are arranged closely. Here, instead of the step-down line, a signal line having a voltage approximately the same as the power supply voltage supplied from the other board to one of the boards may be used. Effect of the Invention

[0007] According to the present invention, in an electronic control device incorporating a plurality of circuit boards, it is possible to reduce the number of noise suppression components while facilitating the routing of ground lines. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing an example of an electric steering system. [Diagram 2] FIG. 2 is a perspective view showing an example of a motor unit. [Diagram 3] FIG. 2 is a perspective view showing an example of an internal structure of an electronic control device. [Figure 4] FIG. 2 is a plan view showing an example of a connector unit. [Diagram 5] 1 is a plan view showing an example of electronic components mounted on a surface of a power supply board. FIG. [Figure 6] FIG. 4 is a plan view showing an example of electronic components mounted on a surface of a control board. [Figure 7] 4 is a plan view showing an example of electronic components mounted on the rear surface of the control board. FIG. [Figure 8] FIG. 4 is a vertical cross-sectional view showing an example of a wiring layout of a ground line. [Figure 9] 4 is a vertical cross-sectional view showing an example of a supply path of a power supply voltage supplied from a power supply terminal to a control board; FIG. [Figure 10] FIG. 2 is a vertical cross-sectional view showing a first embodiment of a line arrangement for reducing noise. [Figure 11] FIG. 11 is a vertical cross-sectional view showing a second embodiment of a line arrangement for reducing noise. [Figure 12] FIG. 11 is a vertical cross-sectional view showing a third embodiment of a line arrangement for reducing noise. [Figure 13] FIG. 2 is a schematic circuit diagram showing an example of a control system of the electric steering system. [Figure 14] 10 is an explanatory diagram of a path of a ground current that flows when the ground of the second system is broken. FIG. [Figure 15] FIG. 11 is a vertical cross-sectional view showing another example of the wiring layout of the ground line. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an example of an electric power steering system 100 mounted on a vehicle such as a passenger car, a bus, a truck, or a construction machine, which is an example of an application target of this embodiment.

[0010] The electric power steering system 100 includes a rack-and-pinion steering gear box 200 and a motor unit 300 that assists the steering wheel operation force applied by the driver.

[0011] The steering gear box 200 includes an input shaft 210 to which a steering wheel is connected via a steering shaft, a pinion (not shown) fixed to the tip of the input shaft 210, a rack (not shown) extending in the left-right direction and meshing with the pinion, and a gear housing 220 that houses the pinion and the rack. Tie rods 230 are connected to both ends of the rack, and tie rod ends 240 connected to the knuckle arms of the steering knuckle are connected to the both ends of the rack. Rubber boots 250 that can expand and contract in the left-right direction are attached to both ends of the gear housing 220 to prevent foreign matter such as rainwater and dust from entering the inside. Furthermore, a torque sensor 260 that detects steering torque as the operating force of the steering wheel by the driver is attached to the middle of the input shaft 210.

[0012] An attachment portion 270 for attaching the motor unit 300 is formed at a predetermined location of the gear housing 220 with the axis of the motor unit 300 being approximately parallel to the axis of the gear housing 220. The attachment portion 270 is formed, for example, on a protruding surface following the outline of the joint surface of the motor unit 300, and a reducer and ball nut gear (not shown) are disposed inside the attachment portion 270 for transmitting the rotational driving force of the motor unit 300 to the rack while reducing the speed.

[0013] 2, the motor unit 300 includes a motor 320 such as a brush motor or a brushless motor, and an electronic control device 340 incorporating an electronic circuit for controlling and driving the motor 320. The electronic control device 340 is attached integrally to the rear surface of the motor 320, that is, the rear surface located opposite to the joint surface to the steering gear box 200. An output shaft 322 of the motor 320 is connected to a reducer and a ball nut gear arranged in the mounting portion 270 of the gear housing 220, and a rotational driving force can be transmitted to the rack via the reducer and the ball nut gear. The electronic control device 340 may be separate from the motor unit 300.

[0014] Motor 320 of motor unit 300 includes a stator (not shown) having two coil systems, a rotor (not shown) integrated with output shaft 322, and a housing 324 that accommodates the stator and rotor. Therefore, motor 320 of motor unit 300 is driven by at least one of the two coil systems, and is configured to be able to assist the driver's steering wheel operation force even if a failure occurs in one of the two coil systems.

[0015] 2 to 4, the electronic control device 340 of the motor unit 300 includes a power supply board 350 and a control board 360 which transmit signals to each other, a connector unit 370 for supplying DC power and control signals to the power supply board 350 and the control board 360, and a cover 380 for accommodating the power supply board 350 and the control board 360. Here, the power supply board 350 and the control board 360 are connected to each other via, for example, lead wires, flexible cables, or a BtoB connector (board-to-board connector) so as to be able to transmit any signals to each other. In addition, the power supply board 350 and the control board 360 are detachably fastened to bosses 324A and 324B formed on the bottom wall of the housing 324 of the motor 320 by screws 326.

[0016] On the front surface of the power supply board 350, a smoothing circuit 350A and an inverter circuit 350B of the first system, and a smoothing circuit 350C and an inverter circuit 350D of the second system are mounted as shown in Fig. 5 in order to realize a redundant configuration. On the front surface and rear surface of the control board 360, a microcomputer 360A, a power supply circuit 360B, and an inverter drive signal generating circuit 360C of the first system, and a microcomputer 360D, a power supply circuit 360E, and an inverter drive signal generating circuit 360F of the second system are mounted as shown in Fig. 6 and Fig. 7 in order to realize a redundant configuration. The inverter drive signal generating circuit 360C of the first system and the inverter drive signal generating circuit 360F of the second system of the control board 360 are configured to supply drive signals to the inverter circuit 350B of the first system and the inverter circuit 350D of the second system of the power supply board 350 via a bus bar or the like (not shown).

[0017] The connector unit 370 includes a power connector 370A to which a harness of a first DC power supply is detachably connected, a power connector 370B to which a harness of a second DC power supply is detachably connected, and a control connector 370C to which harnesses for transmitting control signals of the first and second systems are detachably connected. The first power connector 370A, the second power connector 370B, and the control connector 370C are integrally formed upright on one surface of a flat connector base 370D, for example.

[0018] The cover 380 has a cylindrical shape with a bottom that is open at one end in the axial direction, and the open end is press-fitted and fixed into a groove formed on the outer circumferential surface of the housing 324 of the motor 320. The bottom wall of the cover 380 is also formed with openings following the outer shapes of the first power connector 370A, the second power connector 370B, and the control connector 370C of the connector unit 370 so that these connectors are exposed to the outside. Note that it is desirable to ensure a seal between the cover 380 and the housing 324 of the motor 320 using, for example, liquid packing to prevent foreign matter such as moisture and dust from entering the interior of the cover 380.

[0019] In the electric power steering system 100, when the driver operates the steering wheel, the input shaft 210 rotates via the steering shaft, and the pinion fixed to the tip of the input shaft 210 rotates, causing the rack to slide left or right. When the rack slides left or right, the sliding force is transmitted to the steering arm of the steering knuckle via the tie rod 230 and the tie rod end 240, and the steered wheels rotate around the axis of the kingpin to be steered.

[0020] Furthermore, the electronic control device 340 specifies the operation direction (rotation direction) of the steering wheel according to the steering torque detected by the torque sensor 260, and calculates the operation amount of the motor 320 that assists the operation force of the driver according to the steering torque and the vehicle speed. Then, the electronic control device 340 supplies a drive current according to the operation amount of the motor 320 to the coil of the stator, and rotates and drives the output shaft 322 of the motor 320 to assist the operation force. At this time, the electronic control device 340 performs feedback control of the motor 320 using an output signal from a rotation angle sensor provided in addition to the motor 320.

[0021] 8, the ground terminal 370A1 of the first system power connector 370A is connected to the first system ground (not shown) of the power supply board 350 via a bus bar 370A2 that passes through the inside of the connector base 370D of the connector unit 370 and then bends and extends to the power supply board 350. The first system ground of the power supply board 350 is connected to the first system ground (not shown) of the control board 360 via a signal transmission path that transmits signals between the power supply board 350 and the control board 360, which is one of a plurality of lead wires 372 in the illustrated example (for example, the lead wire 372 located at the leftmost position). Therefore, the ground terminal 370A1 of the first system power connector 370A is connected to the first system ground of the control board 360 via the ground of the first system of the power supply board 350, via the ground line GL1 indicated by the dashed line in the figure, which is made up of the bus bar 370A2, the first system ground of the power supply board 350, and the lead wire 372. Furthermore, a capacitor 374 having a predetermined capacitance, which can be given as an example of a noise suppression component, is disposed between the bus bar 370A2 and the ground of the first system of the power supply board 350.

[0022] 8, the ground terminal 370B1 of the second power connector 370B is connected to the second ground (not shown) of the power supply board 350 via a bus bar 370B2 that passes through the inside of the connector base 370D of the connector unit 370 and then bends and extends to the power supply board 350. The second ground of the power supply board 350 is connected to the second ground (not shown) of the control board 360 via a signal transmission path that transmits signals between the power supply board 350 and the control board 360, which is one of a plurality of lead wires 372 (for example, the lead wire 372 located at the rightmost position) in the illustrated example. Therefore, the ground terminal 370B1 of the second power connector 370B is connected to the second ground of the control board 360 via the ground of the second power supply board 350 via the ground line GL2 indicated by the dashed line in the figure, which is made up of the bus bar 370B2, the ground of the second power supply board 350, and the lead wire 372. Furthermore, a capacitor 374 having a predetermined capacitance, which can be given as an example of a noise suppression component, is disposed between the bus bar 370B2 and the ground of the second system of the power supply board 350. Note that it is desirable that the ground of the first system and the ground of the second system of the power supply board 350 are insulated from each other.

[0023] According to this configuration, the ground line GL1 connected to the ground terminal 370A1 of the power connector 370A of the first system is connected to the ground of the first system of the control board 360 via the ground of the first system of the power supply board 350. Furthermore, since the capacitor 374 arranged at the connection point of the ground line GL1 of the first system to the power supply board 350 reduces noise, the noise superimposed on the current flowing through the lead wire 372 connecting the ground of the first system of the power supply board 350 and the ground of the first system of the control board 360 is reduced. Therefore, there is no need to arrange a noise countermeasure component at the connection point of the ground line GL1 of the first system to the control board 360, and the noise countermeasure components can be reduced while facilitating the wiring of the ground line GL1 compared to the conventional technology. Furthermore, since the noise countermeasure components can be reduced, the cost and size of the electronic control device 340 can be reduced, and the mounting space of the electronic components on the board can be effectively utilized. Note that the action and effect of the second system are the same as the action and effect of the first system, and therefore the description thereof will be omitted.

[0024] As shown in Fig. 9, the power terminal 370A3 of the power connector 370A of the first system is connected to the smoothing circuit 350A of the first system of the power board 350 via a bus bar 370A4 that penetrates the inside of the connector base 370D of the connector unit 370 and then bends and extends to the power board 350 (see the dashed line on the left). The power supply voltage smoothed by the smoothing circuit 350A of the first system of the power board 350 is supplied to the first system of the control board 360 via a power line PL1 consisting of one of the multiple lead wires 372 (for example, the lead wire 372 located second from the left). Therefore, the power supply voltage supplied to the power terminal 370A3 of the power connector 370A of the first system is supplied to the smoothing circuit 350A of the first system of the power board 350 via the bus bar 370A4 and smoothed, and then supplied to the first system of the control board 360 via the power line PL1. In short, the power terminal 370A3 of the first system of the power connector 370A is connected only to the first system of the power supply board 350 to which the ground terminal 370A1 of the first system is directly connected via the bus bar 370A2.

[0025] As shown in Fig. 9, the power terminal 370B3 of the power connector 370B of the second system is connected to the smoothing circuit 350C of the second system of the power board 350 via a bus bar 370B4 that penetrates the inside of the connector base 370D of the connector unit 370 and then bends and extends to the power board 350 (see the dashed line on the right). The power supply voltage smoothed by the smoothing circuit 350C of the second system of the power board 350 is supplied to the second system of the control board 360 via a power line PL2 consisting of one of the multiple lead wires 372 (for example, the lead wire 372 located second from the right). Therefore, the power supply voltage supplied to the power terminal 370B3 of the power connector 370B of the second system is supplied to the smoothing circuit 350C of the second system of the power board 350 via the bus bar 370B4 and smoothed, and then supplied to the second system of the control board 360 via the power line PL2. In short, the power terminal 370B3 of the second system of the power connector 370B is connected only to the second system of the power supply board 350 to which the ground terminal 370B1 of the second system is directly connected via the bus bar 370B2.

[0026] Here, in the multiple lead wires 372 that transmit signals between the power supply board 350 and the control board 360, the ground line GL1 and the power line PL1 of the first system may be arranged close to each other, and the ground line GL2 and the power line PL2 of the second system may be arranged close to each other, as shown in Fig. 10. In this way, the directions of the current flowing through the ground line GL1 of the first system and the current flowing through the power line PL1 of the first system are opposite to each other, so that noises superimposed on the currents cancel each other out and become smaller, thereby improving, for example, the noise resistance performance of the first system. Also, the directions of the current flowing through the ground line GL2 of the second system and the current flowing through the power line PL2 of the second system are opposite to each other, so that noises superimposed on the currents cancel each other out and become smaller, thereby improving, for example, the noise resistance performance of the second system.

[0027] In this case, the ground line GL1 and power line PL1 of the first system, and the ground line GL2 and power line PL2 of the second system may be arranged at a distance smaller than the thickness (board thickness) of the power supply board 350 and the control board 360. In this way, noises with large amplitudes and opposite phases interfere with each other and cancel each other out, making it possible to further reduce noise and improve noise resistance.

[0028] Incidentally, in the control board 360, it is necessary to generate a step-down voltage by stepping down the power supply voltage to a predetermined voltage using the power supply circuit 360B of the first system and the power supply circuit 360E of the second system, and to supply this to the power supply board 350. In this case, it is preferable to arrange the power supply line PL1, the ground line GL1, and the step-down line DL1 that supplies the step-down voltage from the control board 360 to the power supply board 350 in close proximity to each other in the multiple lead wires 372, as shown in FIG. 11. In this way, the current flowing through the power supply line PL1 from the power supply board 350 to the control board 360 and the current flowing through the step-down line DL1 and the ground line GL1 from the control board 360 to the power supply board 350 are opposed to each other, so that the noises superimposed on each current are mutually cancelled out and reduced. At this time, if the power supply line PL1, the ground line GL1, and the step-down line DL1 are arranged at a distance smaller than the thickness (board thickness) of the power supply board 350 and the control board 360, the noise can be effectively reduced. The same applies to the second system.

[0029] In addition, the control board 360 needs to use the inverter drive signal generating circuit 360C of the first system and the inverter drive signal generating circuit 360F of the second system to generate a drive signal having a voltage equivalent to the power supply voltage for driving the inverter circuit 350B of the first system and the inverter circuit 350D of the second system of the power supply board 350, and supply this to the power supply board 350. In this case, it is preferable to arrange the power line PL1, ground line GL1, and signal line SL1 for supplying the drive signal from the control board 360 to the power supply board 350 in close proximity to each other in the multiple lead wires 372, as shown in FIG. 12. In this way, the current flowing through the power line PL1 from the power supply board 350 to the control board 360 and the current flowing through the signal line SL1 and ground line GL1 from the control board 360 to the power supply board 350 are opposite to each other, and the voltages of these currents are equivalent, so that noises superimposed on each current are mutually cancelled out and reduced. At this time, noise can be effectively reduced by arranging the power supply line PL1, the ground line GL1, and the signal line SL1 at a distance smaller than the thickness (board thickness) of the power supply board 350 and the control board 360. The same applies to the second system.

[0030] 13 shows a schematic circuit diagram of a control system of an electronic control device 340 having a common ground 360G in which the ground of the first system and the ground of the second system of the control board 360 are integrated, based on the various embodiments described above. Here, the stator of the motor 320 in the motor unit 300 includes a first coil 320A that is driven and controlled by an inverter circuit 350B of the first system, and a second coil 320B that is driven and controlled by an inverter circuit 350D of the second system. The control system of the motor 320 is divided into a first system and a second system, as will be described in detail below.

[0031] [1st system] The ground terminal and power terminal of the battery BAT1, which can be given as an example of a DC power supply, are connected to the ground terminal 370A1 and power terminal 370A3 of the power connector 370A, respectively. The ground terminal 370A1 of the power connector 370A is connected to the ground terminal of the inverter circuit 350B mounted on the power supply board 350, and is also connected to the common ground 360G of the control board 360. The power terminal 370A3 of the power connector 370A is connected to the power terminal of the inverter circuit 350B mounted on the power supply board 350, and is also connected to the power terminal of the power circuit 360B mounted on the control board 360. The inverter circuit 350B mounted on the power supply board 350 outputs a drive current to the first coil 320A of the motor 320. The power circuit 360B of the control board 360 supplies a DC power supply of a predetermined voltage to the microcomputer 360A and the inverter drive signal generating circuit 360C.

[0032] The ground terminals of the microcomputer 360A, the power supply circuit 360B, and the inverter drive signal generating circuit 360C mounted on the control board 360 are each connected to a common ground 360G. The microcomputer 360A mounted on the control board 360 outputs a control signal to the inverter drive signal generating circuit 360C, and is also connected to the microcomputer 360D of the second system. Therefore, the microcomputer 360A of the first system is configured to be able to transmit any signal to and from the microcomputer 360D of the second system (and vice versa). The inverter drive signal generating circuit 360C mounted on the control board 360 outputs a drive signal to the inverter circuit 350B mounted on the power supply board 350 in response to a control signal from the microcomputer 360A.

[0033] [Second system] The ground terminal and power terminal of the battery BAT2, which can be given as an example of a DC power supply, are connected to the ground terminal 370B1 and power terminal 370B3 of the power connector 370B, respectively. The ground terminal 370B1 of the power connector 370B is connected to the ground terminal of the inverter circuit 350D mounted on the power supply board 350, and is also connected to the common ground 360G of the control board 360. The power terminal 370B3 of the power connector 370B is connected to the power terminal of the inverter circuit 350D mounted on the power supply board 350, and is also connected to the power terminal of the power circuit 360E mounted on the control board 360. The inverter circuit 350D mounted on the power supply board 350 outputs a drive current to the second coil 320B of the motor 320. The power circuit 360E of the control board 360 supplies a DC power supply of a predetermined voltage to the microcomputer 360D and the inverter drive signal generating circuit 360F.

[0034] The ground terminals of the microcomputer 360D, the power supply circuit 360E, and the inverter drive signal generating circuit 360F mounted on the control board 360 are each connected to a common ground 360G. The microcomputer 360D mounted on the control board 360 outputs a control signal to the inverter drive signal generating circuit 360F. The inverter drive signal generating circuit 360F mounted on the control board 360 outputs a drive signal to the inverter circuit 350D mounted on the power supply board 350 in response to the control signal from the microcomputer 360D.

[0035] Here, when the ground of either the power connector 370A of the first system or the power connector 370B of the second system is disconnected, a current that flows in the ground line of the circuit shown in Fig. 13 will be considered. For example, as shown in Fig. 14, when the ground terminal 370B1 of the power connector 370B in the second system is disconnected, the ground current from the inverter circuit 350D of the power supply board 350 in the second system cannot return to the battery BAT2. In this case, the ground current from the inverter circuit 350D of the power supply board 350 flows into the ground line of the first system via the electric path that connects the ground of the power supply board 350 and the common ground 360G of the control board 360, and the common ground 360G, as shown by the dashed line A in the figure.

[0036] In the ground line of the first system, a ground current (indicated by dashed line B in the figure) from the inverter circuit 350B of the power supply board 350 and a ground current (indicated by dashed line C in the figure) from the microcomputer 360A, the power supply circuit 360B, and the inverter drive signal generating circuit 360C of the control board 360 normally flows. If a break occurs in the ground terminal 370B1 of the power connector 370B of the second system and the ground current of the second system further flows in the ground line of the first system, the above-mentioned ground currents A, B, and C flow in the ground terminal 370A1 of the power connector 370A of the first system, and for example, the rated power capacity is exceeded. For this reason, the normal power connector 370A may also break down, and the electric power steering system 100 may experience, for example, a sudden loss of assist. Note that when the ground terminal 370A1 of the power connector 370A of the first system breaks down, an excessive current similarly flows in the ground line of the second system.

[0037] For this reason, it is necessary to detect whether or not an open circuit has occurred in the ground of the first system power connector 370A and the second system power connector 370B, and to stop the operation of the inverter circuit of the system in which the open circuit has occurred, thereby preventing failure from occurring in even normal power connectors.

[0038] Therefore, as shown in FIG. 13 and FIG. 14, for each of the first and second systems, current detection elements 400 and 420 such as shunt resistors are disposed in the electric path (on the ground line) connecting the ground of the power supply board 350 and the common ground 360G of the control board 360. Then, the microcomputer 360A of the first system and the microcomputer 360D of the second system constantly monitor the output from the current detection elements 400 and 420, and when the output becomes equal to or exceeds a predetermined value, the operation of the inverter circuit is stopped. At this time, the microcomputer of the system in which the failure has occurred notifies the microcomputer of the normal system that the failure has occurred, and if necessary, requests the microcomputer to take over the control of the motor 320. In this way, the robustness of the function of detecting a ground break can be improved. Even if a failure occurs in one system, the normal system continues to control the motor 320, so the function of the electric power steering system 100 is not impaired.

[0039] In the embodiment described above, the motor 320 and the electronic control device 340 in the motor unit 300 have a redundant configuration, but the present invention can also be applied to a motor and an electronic control device that do not employ a redundant configuration. In this case, the motor 320 has only one coil, and the power supply board 350 and the control board 360 of the electronic control device 340 have only one control system.

[0040] 15 shows another embodiment of the electronic control device 340. In addition, in order to avoid confusion with the previous embodiment, in the description of the other embodiment, configurations different from the previous embodiment will be described with a prime (').

[0041] A power connector 370A' and a control connector (not shown) are formed in a connector base 370D' of the connector unit 370'. A ground terminal 370A1' of the power connector 370A' is connected to the ground (not shown) of the power supply board 350' via a bus bar 370A2' that passes through the inside of the connector base 370D' of the connector unit 370' and then curves and extends to the power supply board 350'. The ground of the power supply board 350' is connected to the ground (not shown) of the control board 360 via a signal transmission path that transmits signals between the power supply board 350' and the control board 360', which is one of a plurality of lead wires 372' (for example, the lead wire 372' located at the leftmost position in the illustrated example). Therefore, ground terminal 370A1' of power connector 370A' is connected to the ground of control board 360' via ground line GL' indicated by a dashed line on the left side of the drawing, which is made up of bus bar 370A2', the ground of power supply board 350', and lead wire 372', and via the ground of power supply board 350'. Furthermore, capacitor 374' of a predetermined capacitance, which can be given as an example of a noise suppression component, is disposed between bus bar 370A2' and the ground of power supply board 350'.

[0042] The power terminal 370A3' of the power connector 370A' is connected to the smoothing circuit of the power supply board 350' via a bus bar 370A4' that penetrates the inside of the connector base 370D' of the connector unit 370' and then bends and extends to the power supply board 350' (see the dashed line on the right side of the figure). The power supply voltage smoothed by the smoothing circuit of the power supply board 350' is supplied to the control board 360' via a power supply line PL' consisting of one of the multiple lead wires 372' (for example, the lead wire 272' located second from the left). Therefore, the power supply voltage supplied to the power terminal 370A3' of the power connector 370A' is supplied to the smoothing circuit of the power supply board 350' via the bus bar 370A4' and smoothed, and then supplied to the control board 360' via the power supply line PL'. In short, the power terminal 370A3' of the power connector 370A' is connected only to the power supply board 350' to which the ground terminal 370A1' is directly connected via the bus bar 370A2'.

[0043] According to this configuration, the ground line GL' connected to the ground terminal 370A1' of the power connector 370A' is connected to the ground of the control board 360' via the ground of the power supply board 350'. Furthermore, since the capacitor 374' arranged at the connection point of the ground line GL' to the power supply board 350' reduces noise, the noise superimposed on the current flowing through the lead wire 372' connecting the ground of the power supply board 350' and the ground of the control board 360' is reduced. Therefore, there is no need to arrange a noise countermeasure component at the connection point of the ground line GL' to the control board 360', and the number of noise countermeasure components can be reduced while facilitating the routing of the ground line GL' compared to the conventional technology. Furthermore, since the number of noise countermeasure components can be reduced, the cost and size of the electronic control device 340 can be reduced, and the mounting space of the electronic components on the board can be effectively utilized.

[0044] It should be noted that the other embodiments of electronic control unit 340 that do not employ a redundant configuration are also applicable to electronic control unit 340 that employs a redundant configuration.

[0045] Furthermore, a person skilled in the art will easily understand that new embodiments can be created by omitting parts of the technical ideas of the various above-mentioned embodiments, combining parts of them appropriately, or replacing parts of them with well-known technology.

[0046] As one example, the electronic control device 340 according to this embodiment can be applied not only to the electric power steering system 100 but also to known systems such as an engine control system, an automatic transmission control system, an autonomous driving system, etc. In this case, at least smoothing circuits 350A and 350C are mounted on the power supply board 350, and at least microcomputers 360A and 360D are mounted on the control board 360.

[0047] Furthermore, the electronic control device 340 is not limited to the power supply board 350 and the control board 360, and may have three or more boards suitable for the system to be controlled. Furthermore, in the control system of the electric power steering system 100 shown in Fig. 13 and Fig. 14, a battery common to the first system and the second system may be used. [Explanation of symbols]

[0048] 340...Electronic control device 350, 350'...Power supply board 350A, 350C...Smoothing circuit 360, 360'...Control board 360A, 360D...Microcomputer 360G...Common ground 370A, 370A', 370B...Power supply connector 370A1, 370A1', 370B1...Ground terminal 370A3, 370A3', 370B3...Power supply terminal 400, 420...Current detection element DL1, DL2...Step-down line GL1, GL2, GL'...Ground line PL1, PL2, PL'...Power supply line SL1, SL2...Signal line

Claims

1. An electronic control device including a plurality of boards for transmitting signals to each other and a power connector for a DC power supply, a ground line connected to a ground terminal of the power connector is connected to a ground of another board via a ground of one of the plurality of boards; a power terminal of the power connector is connected only to the board to which a ground terminal of the power connector is directly connected; a power supply line for supplying a power supply voltage from one of the substrates to the other of the substrates, a step-down line for stepping down the power supply voltage in the other of the substrates and supplying the power supply voltage to the one of the substrates, and the ground line are disposed adjacent to each other among the plurality of substrates; Electronic control unit.

2. An electronic control device having a plurality of circuit boards for transmitting signals to each other and a power connector for a DC power supply, a ground line connected to a ground terminal of the power connector is connected to a ground of another board via a ground of one of the plurality of boards; a power terminal of the power connector is connected only to the board to which a ground terminal of the power connector is directly connected; a power supply line for supplying a power supply voltage from one of the substrates to the other of the substrates, a signal line having a voltage approximately equal to the power supply voltage for supplying from the other of the substrates to the one of the substrates, and the ground line are arranged close to each other among the substrates; Electronic control unit.

3. the plurality of boards include a control board on which at least a microcomputer is mounted, and a power supply board on which at least a power supply voltage smoothing circuit is mounted, the ground line is connected to the ground of the control board via the ground of the power supply board; The electronic control device according to claim 1 or 2.

4. the plurality of boards include a control board on which at least a microcomputer is mounted, and a power supply board on which at least a power supply voltage smoothing circuit is mounted, the ground line is connected to the ground of the power supply board via the ground of the control board; The electronic control device according to claim 1 or 2.

5. the power connector, the microcomputer, and the smoothing circuit have a duplicated redundant system; The ground of the control board is a common ground shared between each system, In each system, a current detection element is disposed in the ground line connecting the ground of the power supply board and the common ground of the control board, the current detection element detecting a current flowing in the ground line. The electronic control device according to claim 3 or 4.

6. the power supply line, the ground line and the step-down line are arranged at a distance smaller than a thickness of the substrate; The electronic control device according to claim 1 .

7. The power supply line, the ground line, and the signal line are arranged at a distance smaller than a thickness of the substrate. The electronic control device according to claim 2 .

8. A method for wiring a ground line of an electronic control device having a plurality of circuit boards for transmitting signals between each other and a power connector for a DC power supply, comprising the steps of: a ground line connected to a ground terminal of the power connector is connected to a ground of one of the plurality of boards via the ground of the other board; a power terminal of the power connector is connected only to the board to which a ground terminal of the power connector is directly connected; a power supply line for supplying a power supply voltage from one of the substrates to the other of the substrates, a step-down line for stepping down the power supply voltage in the other of the substrates and supplying it to the one of the substrates, and the ground line are disposed adjacent to each other among the plurality of substrates; How the Grand Line is arranged.

9. A method for wiring a ground line of an electronic control device having a plurality of circuit boards for transmitting signals to each other and a power connector for a DC power supply, comprising: a ground line connected to a ground terminal of the power connector is connected to a ground of one of the plurality of boards via the ground of the other board; a power terminal of the power connector is connected only to the board to which a ground terminal of the power connector is directly connected; a power supply line for supplying a power supply voltage from one of the substrates to the other of the substrates, a signal line having a voltage approximately equal to the power supply voltage for supplying from the other of the substrates to the one of the substrates, and the ground line are disposed in close proximity to each other between the substrates; How the Grand Line is arranged.

10. the plurality of boards include a control board on which at least a microcomputer is mounted, and a power supply board on which at least a power supply voltage smoothing circuit is mounted, the ground line is connected to the ground of the control board via the ground of the power supply board; 10. The method for routing a ground line according to claim 8 or 9.

11. the plurality of boards include a control board on which at least a microcomputer is mounted, and a power supply board on which at least a power supply voltage smoothing circuit is mounted, the ground line is connected to the ground of the power supply board via the ground of the control board; 10. The method for routing a ground line according to claim 8 or 9.

12. the power connector, the microcomputer, and the smoothing circuit have a duplicated redundant system; The ground of the control board is a common ground shared between each system, a current detection element is disposed on the ground line connecting the ground of the power supply board and the common ground of the control board in each system, the current detection element detecting a current flowing through the ground line; The method for routing a ground line according to claim 10 or 11.

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