POWER SUPPLY SYSTEM

Abstract

Power supply system comprising: circuit units (101, 201) in a number of n or more systems, which are connected accordingly to n systems of power sources (191, 291), where n is an integer of two or more; a common ground (Gc) to which all of the circuit units are connected;and a ground wiring section (5) configured to provide a node-to-node connection between common ground nodes provided in a number of (n + α), where α is an integer of 1 or more, in the common ground, and ground plane nodes provided in a number of (n + α) in a ground plane (500), characterized in that when a number of multi-point failures ensuring functional safety is m (where m < n), a parallel resistance value between the ground plane and the common ground is specified based on a sum of minimum operating currents of (n - m) systems and a minimum value of a common ground potential.

Description

TECHNICAL FIELDThe invention relates to a power supply system.BACKGROUND INFORMATIONThe prior art includes a motor control device in which an external current source or external current source is formed redundantly. For example, in JP 2018-042 403 A, two separate external power sources are connected to two ECUs (i.e., electronic control units) via separate power-ground lines, respectively, and the configuration of the external power source is made redundant together with the configuration of an engine control system.If a ground is separately provided for each system, i.e., from system to system, as disclosed in JP 2018-042 403 A, a circuit for detecting a ground fault, a current limiting circuit for preventing a ground current from flowing from an abnormal system to a normal system in a ground fault, and the like are required, which complicates the circuit configuration.JP 2017-169 405 A and U.S. Pat. No. 2017 / 0 272 009 A1 disclose a motor control device and a steering control device. The motor control device includes a plurality of control systems including an abnormality detection circuit for detecting a ground abnormality.DE 10 2014 106 218 A1 discloses a rotating electric machine for a vehicle, which has a power system circuit and a control system circuit.BRIEF DESCRIPTIONAn object of the present invention is to provide a power supply system capable of simplifying a circuit configuration.The object is achieved by the power supply system having the features according to claim 1. Advantageous embodiments are given in the dependent claims.A power supply system according to the present invention includes circuit units of n or more (i.e., counted as a "system", respectively), a common ground, and a ground wiring unit. The circuit unit is connected to each of n power supply systems, where n is an integer of 2 or more. All of the circuit units are connected to the common ground, i.e. to a ground. The ground wiring unit connects, node to node, (i) (n+α) parts (i.e., n is an integer of 1 or more) of common ground nodes provided in the common ground, and (ii) (n+α) parts of ground plane nodes provided in a ground plane. Here, when a number of multipoint failures ensuring functional safety is m (where m<n), a parallel resistance value between the ground plane and the common ground is set based on a sum of minimum operating currents of (n-m) systems and a minimum value of a common ground potential. In this way, redundant circuits that can withstand multipoint failures when concentrating on a portion between the ground plane and the common ground can be provided with a simple configuration without disconnecting the ground for each system (i.e., without providing a separate ground for each of the multiple systems).BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a schematic structural diagram of a steering system including a driving device according to a first embodiment; FIG. 2 is a block diagram of a driving device according to the first embodiment; FIG. 3 is a block diagram of the driving device according to the first embodiment; FIG. 4 is a plan view of the driving device according to the first embodiment; FIG. 5 is a cross-sectional view taken along a line V-V in FIG. 4 ; FIG. 6 is a schematic diagram of a covering surface of a substrate according to the first embodiment; FIG. 7 is a schematic diagram of a motor surface of the substrate according to the first embodiment; FIG. 8 is a schematic diagram of a second layer of the substrate according to the first embodiment; FIG. 9 is a schematic diagram of a third layer of the substrate according to the first embodiment; FIG. 10 is a schematic diagram of a power supply system according to the first embodiment; FIG. 11 is an explanatory diagram of a wiring resistance of the power supply system according to the first embodiment; FIG. 12 is a block diagram of a driving device according to a second embodiment; FIG. 13 is a plan view of the driving device according to the second embodiment; FIG. 14 is a cross-sectional view taken along a line XIV-XIV in FIG. 13 ; FIG. 15 is a block diagram of the driving device according to a reference example; FIG. 16 is a schematic diagram of the covering surface of the substrate according to the reference example; FIG. 17 is a schematic diagram of the motor surface of the substrate according to the reference example; FIG. 18 is a schematic diagram of a second layer of the substrate according to the reference example; and FIG. 19 is a schematic diagram of a third layer of the substrate according to the reference example.DETAILED DESCRIPTION(First Embodiment)Hereinafter, a power system according to the invention will be described with reference to the drawings. In a plurality of embodiments described below, a substantially identical component is denoted by the same reference sign to avoid duplicate description.The first embodiment is shown in FIGS. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 to 11. A power supply system 1 (see FIG. 10 ) is applied to, for example, an electric power steering apparatus 8 for assisting a steering operation of a vehicle. FIG. 1 shows a configuration of a steering system 90 including the electric power steering device 8. the steering system 90 includes a steering wheel 91 which is a steering member, a steering shaft 92, a pinion 96, a rack 97, road wheels 98, the electric power steering device 8, and the like.The steering wheel 91 is connected to the steering shaft 92. A torque sensor 94 is provided to the steering shaft 92 to detect a steering torque. The torque sensor 94 includes a first sensor unit 194 and a second sensor unit 294, thereby forming a redundant configuration in which each of the sensor units is capable of detecting its own failure. The pinion 96 is provided at an axial end of the steering shaft 92. The pinion 96 engages the rack 97. A pair of wheels 98 are coupled to both ends of the rack 97 via, for example, tie rods.When a driver of the vehicle rotates the steering wheel 91, the steering shaft 92 connected to the steering wheel 91 rotates. a rotational movement of the steering shaft 92 is converted into a translational movement of the rack 97 by the pinion 96. The pair of the idlers 98 are directed at an angle corresponding to a displacement amount of the rack 97.The electric power steering apparatus 8 includes a driving device 40, a reduction gear 89, and the like. The drive device 40 includes a motor 80, an ECU 10, and the like. The reduction gear 89 serving as a power transmission unit reduces the rotation speed of the motor 80 and transmits the rotation to the steering shaft 92, The electric power steering apparatus 8 of the present embodiment operates according to the column assist principle and transmits the rotation to a steering column in the steering shaft 92, but may alternatively operate according to the rack assist principle that transmits the rotation of the motor 80 to the rack 97. In the present embodiment, the steering shaft 92 corresponds to a "driving object".Next, the electrical configuration of the driving device 40 will be described with reference to FIG. 2. The motor 80 outputs a part or all of the steering required torque(s) and is driven with electric power supplied from the batteries 191 and 291 as power sources, and rotates the reduction gear 89 forward and backward. The motor 80 is a three-phase brushless motor, but may be a motor other than the three-phase brushless motor.The motor 80 includes a first motor winding 180 and a second motor winding 280 as a winding set. The motor windings 180 and 280 have the same electrical characteristics and are wound abolishly around a common stator 840 (see FIG. 4 ) with a displacement of an electrical angle of 30 [degrees] from each other. Accordingly, the phase currents to be supplied to the motor windings 180 and 280 are controlled so that the phase currents have a phase shift φ of 30 degrees. By optimizing a current supply phase difference, the output torque is improved. Moreover, the sixth-order torque ripple can be reduced, and accompanying noise and vibration can be reduced. In addition, since the heat is dispersed and leveled by distributing the current to the systems, it is possible to reduce temperature-dependent system errors such as a detection value of each sensor and a torque, as well as increase the amount of electric current that can be supplied. The motor windings 180 and 280 need not be wound in a mutually raisable manner and may each have different electrical properties.Hereinafter, a combination of a first inverter 120 and a first microcomputer 150 with other components related to the energization control (i.e., the power supply control) of the first motor winding 180 will be referred to as a first system L 1, and a combination of a second inverter 220 and a second microcomputer 250 with other components related to the energization control of the second motor winding 280 will be referred to as a second system L 2. Further, the configuration related to the first system L 1 is basically indicated with reference numerals in the 100-ers, and the configuration related to the second system L 2 is basically indicated with reference numerals in the 200-ers. Further, in the first system L 1 and the second system L 2, the same or similar configuration is numbered so that the last two numerals are the same number, and the description regarding the configuration of the second system L 2, etc. is omitted accordingly. For the further configuration described below, the term "first" is referred to with the suffix "1" and the term "second" is referred to with the suffix "2".The first inverter 120 is connected to the first motor winding 180, and power is supplied from the first battery 191 via the first inverter 120. The first inverter 120 converts the electric power for the first motor winding 180, and has six switching elements 121 to 126. Although the switching elements 121 to 126 of the present embodiment are MOSFETs, the switching elements may be IGBTs, thyristors, or the like, and the same applies to motor relays 136 to 138 and power source relays 141 and 142 described later.The switching elements 121 to 123 are positioned on a high potential side, and the switching elements 124 to 126 are positioned on a low potential side. One end of a U-phase coil 181 is connected to a connection point of the U-phase switching elements 121 and 124 to be paired, and one end of a V-phase coil 182 is connected to a connection point of the V-phase switching elements 122 and 125 to be paired, and one end of a W-phase coil 183 is connected to a connection point of the W-phase switching elements 123 and 126 to be paired.A first current detector 130 is provided on a low potential side of the first inverter 120. The first current detector 130 includes current detection elements 131 to 133 provided in each phase. The current detection elements 131 to 133 of the present embodiment are shunt resistors, but may be Hall elements, and the position of the detector may be on the high potential side or on a load side (i.e., on a side close to the first motor winding 180).A motor relay unit 135 is provided at a position between the first inverter 120 and the first motor winding 180, and connection / disconnection between the switching elements 121 to 126 and the coils 181 to 183 can be switched. Specifically, a motor relay 136 is provided at a position between the U-phase switching elements 121 and 124 and the U-phase coil 181, and a motor relay 137 is provided at a position between the V-phase switching elements 122 and 125 and the V-phase coil 182, and a motor relay 138 is provided at a position between the W-phase switching elements 123 and 126 and the W-phase coil 183. The motor relays 136 to 138 may be mechanical relays, or may be semiconductor relays (e.g., MOSFETs). Further, the motor relay may be omitted when a regenerative braking mode is permitted in the system at the time of failure.The power source relays 141 and 142 are provided on a high potential side wiring Lp 1 that connects a positive electrode of the first battery 191 and a high potential side of the first inverter 120. When the current source relays 141 and 142 are configured by parasitic diode elements such as MOSFETs, it is desirable to connect the two elements in series so that the directions of the parasitic diodes are reversed. In this way, a reverse current can be prevented from flowing when the battery 191 is erroneously connected in the reverse direction. The power source relays 141 and 142 may be mechanical relays.A coil 145 is provided at a position between the first battery 191 and the power source relay 141. A capacitor 146 has a positive electrode connected at a position between the first battery 191 and the coil 145, and a negative electrode connected to a common ground Gc. The coil 145 and the capacitor 146 form a filter circuit for reducing noise transmitted from other devices sharing the first battery 191 to the driving device 40 and for reducing noise transmitted from the driving device 40 to the other devices sharing the first battery 191. In FIG. 3 and the like, the coil 145 and the capacitor 146 are collectively described as "FLT" and are numbered "145, 146". A capacitor 147 has a positive electrode connected to a position between the power source relay 142 and the first inverter 120, and a negative electrode connected to the common ground Gc. The capacitor 147 smoothes the electric power supplied to the first inverter 120 by storing electric charge.The second inverter 220 is connected to the second motor winding 280, and power is supplied from the second battery 291 via the second inverter 220. The second inverter 220 includes switching elements 221 to 226. A second current detector 230 having current detecting elements 231 to 233 is provided on a low potential side of the second inverter 220. A motor relay unit 235 including motor relays 236 to 238 is provided at a position between the second inverter 220 and the second motor winding 280.Power source relays 241 and 242 are provided on a high potential side wiring Lp 2 that connects a positive electrode of the second battery 291 and a high potential side of the second inverter 220. A coil 245 is provided at a position between the second battery 291 and the power relay 241. A capacitor 246 has a positive electrode connected at a position between the second battery 291 and the coil 245 and a negative electrode connected to the common ground Gc. Further, a capacitor 247 has a positive electrode connected to a position between the power relay 242 and the second inverter 220, and a negative electrode connected to the common ground Gc. The details of the functions and the like of each component are the same as those of the first system, and thus, in FIG. 3 and the like, the coil 245 and the capacitor 246 are collectively referred to as "FLT" with reference numerals 245, 246.As shown in FIG. 3, the ECU 10 includes a first circuit unit 101 and a second circuit unit 201. The first circuit unit 101 includes a first vehicle communication circuit 111, a first torque sensor input circuit 112, the first inverter 120, the first current detector 130, a first angle detection unit 134, the first motor relay unit 135, the first power source relays 141 and 142, the first microcomputer 150, a first drive circuit 156, a first circuit power source 157, and the like. The second circuit unit 201 includes a second vehicle communication circuit 211, a second torque sensor input circuit 212, the second inverter 220, the second current detector 230, a second angle detector 234, the second motor relay unit 235, the second power source relays 241 and 242, the second microcomputer 250, a second drive circuit 256, a second circuit power source 257, and the like.The ECU 10 is provided with a first connector 103, a second connector 203, and a third connector 303. The first connector 103 is provided with a first power source terminal 105, a first ground terminal 106, a first ignition (IG) terminal 107, a first communication terminal 108, and a first torque terminal 109. The first IG port 107, the first communication port 108, and the first torque port 109 are referred to as a first control port 110 (see FIG. 4 ).The first power source terminal 105 is connected to the first battery 101 via a fuse (not shown). The electric power supplied from the positive electrode of the first battery 191 via the first power source terminal 105 reaches the first motor winding 180 through the filters 145 and 146, the power source relays 141 and 142, the inverter 120, and the motor relay unit 135. The first ground terminal 106 is connected to the common ground Gc and a ground plane Gp in the ECU 10. The ground plane Gp of the present embodiment is a vehicle body 500 (see FIG. 10 ).In the present embodiment, the first ground terminal 106 and the ground plane Gp are connected by a single wire harness. Depending on the current-carrying capacity or the like, however, for example, the first ground connection 106 and the ground plane Gp can be connected by a plurality of cable harnesses connected in parallel. The same applies to the connection between a second ground terminal 206 and the ground plane Gp and to the connection between a third ground terminal 306 and the ground plane Gp, which will be described later.The first IG terminal 107 is connected to the positive electrode of the first battery 101 via a first switch that is on / off controlled in conjunction with a vehicle start switch such as an ignition start switch (IG) switch. Electric power or a start signal is supplied from the first battery 191 to a first custom integrated circuit or IC 155 via the first IG terminal 107 (see FIG. 7 ). The first custom IC 135 includes a first driver circuit 156, the first power source 157, a microcomputer monitor (not shown), a current monitor amplifier (not shown), and the like.The first communication port 108 is connected to the first in-vehicle communication circuit 111 and a first in-vehicle communication network 195. The first in-vehicle communication network 195 and the first microcomputer 150 are connected via the first in-vehicle communication circuit 111 so that transmission / reception is possible. Further, the first in-vehicle communication network 195 and the second microcomputer 250 are connected so as to be able to be received only by the second microcomputer 250, so that even if the second circuit unit 201 fails, the first in-vehicle communication network 195 including the first microcomputer 150 is not affected. Further, either or both of the first microcomputer 150 and the second microcomputer 250 are configured so that failure of the communication line of at least one of the two can be detected. Note that reception by the second microcomputer 250 may be performed via a signal line 351. In this case, post-processing information may be transmitted instead of direct information. The first torque connection 109 is connected to the first sensor unit 194 of the torque sensor 94. The detection value of the first sensor unit 194 is input to the first microcomputer 150 via the first torque port 109 and the first torque sensor input circuit 112. Here, the first sensor unit 194 and the first microcomputer 150 are configured to detect a fault involving the torque sensor input circuit 112 and the like.A second connector 203 is provided with the second power source terminal 205, a second ground terminal 206, a second IG terminal 207, a second communication terminal 208, and a second torque terminal 209. The second IG terminal 207, the second communication terminal 208, and the second torque terminal 209 are referred to as a second control terminal 210 (see FIG. 4 ). The second power source terminal 205 is connected to the positive electrode of the second battery 201 via a fuse (not shown). The electric current from the second battery 291 via the second power source terminal 205 is supplied to the second motor winding 280 via the filters 245 and 246, the power source relays 241 and 242, the inverter 220, and the motor relay unit 235. The second ground terminal 206 is connected to the common ground Gc and the ground plane Gp in the ECU 10. The ground plane Gp of the present embodiment is a vehicle body 500 (see FIG. 10 ).The second IG terminal 207 is connected to the positive electrode of the second battery 201 via a second switch that is on / off controlled in conjunction with the start switch of the vehicle. Electric power or a start signal is supplied from the second battery 291 to the second custom IC 255 via the second IG terminal 207 (see FIG. 7 ). The second custom IC 235 includes a second drive circuit 236, a second circuit power source 237, a microcomputer monitor (not shown), a current monitor amplifier (not shown), and the like.The second communication port 208 is connected to the second vehicle communication circuit 211 and a second vehicle communication network 295. The second in-vehicle communication network 295 and the second microcomputer 250 are connected via the second in-vehicle communication circuit 211 so as to enable transmission and reception. Further, the second in-vehicle communication network 295 and the first microcomputer 150 are connected so as to be able to be received only by the first microcomputer 150, so that even if the first circuit unit 101 fails, the second in-vehicle communication network 295 including the second microcomputer 250 is not affected. Further, either or both of the first microcomputer 150 and the second microcomputer 250 are configured so that failure of the communication line can be detected by at least one of the two. Note that reception by the first microcomputer 150 may be performed via a signal line 352 used for communication between microcomputers. In this case, post-processing information may be transmitted instead of direct information.The second torque connection 209 is connected to the second sensor unit 294 of the torque sensor 94. The detection value of the second sensor 294 is input to the second microcomputer 250 via the second torque port 209 and the second torque sensor input circuit 212. Here, the second sensor unit 294 and the first microcomputer 150 are configured to be capable of detecting a failure involving the torque sensor input circuit 212 and the like.In FIG. 3, communication ports 108 and 208 are connected to separate (i.e., respectively different) vehicle communication networks 195 and 295, but may also be connected to the same vehicle communication network. With respect to the vehicle communication networks 195 and 295 in FIG. 3, CAN (Controller Area Network) is exemplarily illustrated. However, the network may use any other standard such as CAN-FD (CAN with flexible data rate), FlexRay, or the like.The third connector unit 303 is provided with the third ground terminal 306. The third ground terminal 306 is connected to the common ground Gc and the ground plane Gp in the ECU 10. The ground terminals 106, 206, and 306 are each connected to separate nodes of the vehicle body 500. In other words, three different nodes of the common ground Gc are connected to different nodes in the ground plane Gp via the separate, i.e. independent, connectors 103, 203 and 303, respectively.The first current detector 130 detects the electric current of the first motor winding 180. The detection value of the first current detector 130 is amplified by an amplifier circuit in the custom IC 155 and output to the first microcomputer 150. The second current detector 230 detects the electric current of the second motor winding 280. The detection value of the second current detector 230 is amplified by an amplifier circuit in the custom IC 255 and output to the second microcomputer 250.The first angle detector 134 detects the rotation angle of the motor 80 and outputs the detection value to the first microcomputer 150. The second angle detector 234 detects the rotation angle of the motor 80 and outputs the detection value to the second microcomputer 250. The first angle detection unit 134 and the first microcomputer 150 are configured to be capable of detecting a fault involving an angle sensor input circuit and the like of the relevant (e.g., subject) system. Further, the second angle detector 234 and the second microcomputer 250 are configured to be capable of detecting a fault involving the angle sensor input circuit and the like in the relevant (e.g., related) system.The microcomputers 150 and 250 each include a CPU, a ROM, a RAM, an I / O (not shown), a bus line connecting these components, and the like. Each processing in the microcomputers 150 and 250 may be software processing by executing a program previously stored in a substantial storage device such as a ROM (i.e., a readable non-volatile tangible recording medium) by the CPU, or may be hardware processing by a dedicated electronic circuit. Here, as the microcomputers 150 and 250, a lock-step dual microcomputer or the like is used, and each of the microcomputers 150 and 250 is capable of detecting its own failure.The first microcomputer 150 controls energization, or power supply, of the first motor winding 180 by controlling the turn-on / turn-off operation of the switching elements 121 to 126. Specifically, in accordance with a control signal output from the first microcomputer 150 to the first drive circuit 156 and a drive signal output from the first drive circuit 156 to each element, the turn-on / turn-off operation of each of the switching elements is controlled. The same applies to the motor relays 136 to 138 and the power source relays 141 and 142.The second microcomputer 250 controls energization of the second motor winding 280 by controlling the turn-on / turn-off operation of the switching elements 221 to 226. Specifically, in accordance with the control signal output from the second microcomputer 250 to the second drive circuit 256 and the drive signal output from the second drive circuit 256 to each element, the turn-on / turn-off operation of these elements is controlled. At this time, the driving of the motor 80 is controlled by the microcomputers 150 and 250. The same applies to the motor relays 236 to 238 and the power source relays 241 and 242.The first microcomputer 150 controls the on / off operation of the motor relay 135 and the power source relays 141 and 142. The first microcomputer 150 and the first custom IC 155 monitor an abnormality of the first system L 1 that is the subject system and when an abnormality occurs that should stop the subject system, and turn off at least the first inverter 120, the first motor relay unit 135, or the first power source relays 141 and 142. Here, the first inverter 120, the first motor relay unit 135, and the first power source relays 141 and 142 are referred to as a "circuit for stopping the subject system in an abnormality".The second microcomputer 250 controls the on / off operation of the motor relay 235 and the power source relays 241 and 242. The second microcomputer 250 and the second custom IC 255 monitor the second system L 2 that is the subject system, and when an abnormality occurs that should stop the subject system, turn off at least the second inverter 220 or the second motor relay unit 235 and then at least one of the power source relays 241 and 242. Here, the second inverter 220, the second motor relay unit 235, and the second power source relays 241 and 242 are referred to as a "circuit for stopping the subject system at the time of abnormality".The first microcomputer 150 monitors, for monitoring the operation state of the second system L 2, at least one of the circuit for stopping the subject system at the time of abnormality stopped when abnormality is detected in the second system L 2 and the signal line 352. In the present embodiment, by monitoring the state of the second power source relays 241 and 242, it is monitored whether or not the second system L 2 is brought to an emergency stop based on a second relay gate signal Vrg 2 output from the second drive circuit 256 to the power source relays 241 and 242.The second microcomputer 250 monitors, for monitoring the operation state of the first system L 1, at least one of the circuit for stopping the subject system in an abnormality and the signal line 351 stopped when an abnormality is detected in the first system L 1. In the present embodiment, by monitoring the state of the first power source relays 141 and 142, it is monitored whether or not the first system L 1 is brought to an emergency stop based on a first relay gate signal Vrg 1 output from the first drive circuit 156 to the first power source relays 141 and 142.Other system monitoring may also be performed based on an intermediate voltage between the two power relay elements, a relay drive signal output from the control unit (i.e., the microcomputer), or a voltage after the relay at a position between the power relay and the inverter based instead on the relay gate signal.The first microcomputer 150 and the second microcomputer 250 are connected by the signal lines 351 and 352 and can transmit / receive information to / from each other via communication between microcomputers. The signal line 351 has the first microcomputer 150 on an output side and has the second microcomputer 250 on an input side, and the signal line 352 has the second microcomputer 250 on an output side and has the first microcomputer 150 on an input side.As shown in FIGS. 4 and 5, the driving device 40 is integrally provided on one side in the axial direction of the motor 80 with the ECU 10, which is a so-called "mechanism-electronics integrated type", but the ECU 10 and the motor 80 may also be separately provided. The ECU 10 is disposed coaxially with a shaft 870 on a side opposite to an output shaft of the motor 80. The ECU 10 may alternatively be provided on the output shaft side of the engine 80. By employing the mechanism-electronics integrated type configuration, it is possible to efficiently arrange the ECU 10 and the motor 80 in a vehicle with limited installation space.The motor 80 includes the stator 840, a rotor 860, a motor housing 830 that houses them, and the like. The stator 840 is fixedly connected to the motor housing 830, and the motor windings 180 and 280 are wound thereon. The rotor 860 is provided radially inside the stator 840 so as to be rotatable relative to the stator 840.The shaft 870 is fitted into the rotor 860 to rotate integrally with the rotor 860. The shaft 870 is rotatably supported by the motor housing 830 through bearings 836 and 837. An end of the shaft 870 on a side of the ECU 10 protrudes from the motor housing 830 toward the ECU 10. A magnet (not shown) is located at the end of the shaft 870 on the side of the ECU 10.The motor housing 830 has a cylindrical housing main body 831 having a bottom and a rear frame end 835. The housing main body 831 is disposed such that a bottom portion is positioned on a driven end 871 side and an opening is positioned on the ECU 10 side. The housing main body 831 is formed with a plurality of protrusions 832 protruding radially outward on the lower side. In the protrusions 832, an opening (not shown) through which a fastening member 881 such as a bolt is inserted is formed. The fixing member 881 is screwed into a gear case (not shown) of the reduction gear 89. Thereby, the motor housing 830 and the gear housing are fixed to each other.The frame rear end 835 is inserted into the opening of the housing main body 831 and press-fitted and fixed. The rear frame end 835 is provided with a motor wire insertion opening (not shown). The motor coils 180 and 280 are inserted into the motor wire insertion hole while being insulated from the frame rear end 835, led out to the ECU 10, and connected to the substrate 470.The ECU 10 includes a connector unit 460, a cover 465, a substrate 470, various electronic components mounted on the substrate 470, and the like. The connector unit 460 includes a connector main body 461 and leg portions 462. The connector main body 461 is provided with the connectors 103, 203, and 303. In FIG. 5, the description of the connector terminals is omitted. The leg portions 462 are formed to extend from the connector main body 461 toward the motor 80 side and come into contact with the substrate 470. The connector unit 460 is fixed to the frame rear end 835 with the substrate 470 therebetween by a fixing member 882 which is a continuous bolt passed through the leg portion 462.The cover 465 is formed substantially in a cylindrical shape having a bottom, and an opening 466 into which the connector main body 461 is inserted is formed at the bottom. On an outer edge of the opening 466, a protrusion 467 inserted into a groove of the connector unit 460 is formed. The cover 465 covers an assembly of the connector unit 460 and the frame rear end 835 from a side opposite to the motor 80, and a tip of the cylindrical portion of the cover 465 is inserted into a gap between the housing main body 831 and the frame rear end 835, and the protrusion 467 is inserted into the groove of the connector unit 460 and fixed by a sealing member (not shown) such as an adhesive.The substrate 470 is, for example, a printed circuit board and is fixed to the rear frame end 835. On the substrate 470, the electronic components of the first and second systems for each system are mounted independently of each other, so that the two systems are provided in a fully redundant configuration. In accordance with the present embodiment, the electronic components are mounted on a substrate 470. However, the electronic components can alternatively also be mounted on a plurality of substrates.In the present embodiment, the substrate 470 is a four-layer substrate, and of two main surfaces, the main surface opposite to the motor 80 is a cover surface 471, and the main surface on the motor 80 side is a motor surface 474. Further, the side layer of the cover surface 471 is the first layer, the side layer of the motor surface 474 is the fourth layer, and a second layer 472 and a third layer 473 are provided therebetween. The cover surface 471 is shown in FIG. 6, the motor surface 474 is shown in FIG. 7, the second layer 472 is shown in FIG. 8, and the third layer 473 is shown in FIG. 9. The cover surface 471 in FIG. 6 and the second layer 472 in FIG. 8 are seen from the side opposite to the motor 80, and the left side of the drawing is a first system region E 1, and the right side of the drawing is a second system region E 2. The motor surface 474 in FIG. 7 and the third layer 473 in FIG. 9 are seen from the motor 80 side, and the right side of the drawing is the first system region E 1, and the left side of the drawing is the second system region E 2.The components of the first system L 1 are mounted in the first system region E 1, and the components of the second system L 2 are mounted in the second system region E 2. In FIGS. 6, 7, 8 to 9, the common ground pattern Gc is indicated by a matt pattern, and the wiring patterns corresponding to the high potential side wirings Lp 1 and Lp 2 are indicated by hatching. In order to avoid complication, the description of some components, signal wirings, etc. is also omitted.As shown in FIG. 6, the coils 145 and 245, the capacitors 146, 147, 246, and 247, and the microcomputers 150 and 250 are mounted on the cover surface 471. In the present embodiment, the capacitors 147 and 247 are disposed at positions near the center of each system region, the inductors 145 and 245 and the capacitors 146 and 246 are positioned on one side of the capacitors 147 and 247, and the microcomputers 150 and 250 are positioned on the other side thereof.As shown in FIG. 7, the inverters 120 and 220, the current detectors 130 and 230, the motor relays 135 and 235, the power source relays 141, 142, 241, and 241, and the custom ICs 155 and 255 are mounted on the motor surface 474. Moreover, in order to avoid complication, the numbers for the elements are omitted.The inverters 120 and 220 are mounted approximately on the back of the capacitors 147 and 247, and the custom ICs 155 and 255 are mounted approximately on the back of the microcomputers 150 and 250. Further, from a region separation line ED side toward the outer periphery of the substrate 470, the switching elements 121 to 123, 221 to 223 on the high potential side, the switching elements 124 to 126, 224 to 226 on the low potential side, the current detection elements 131 to 133, 231 to 233, the motor relays 136 to 138, and 236 to 238 are arranged in the written-down order. Further, the power source relays 141 and 142 are positioned on the opposite side of the custom ICs 155 and 255, which are the high potential side elements of the inverters 120 and 220.A rotation angle sensor 334 is mounted at a position that is substantially at the center of the motor surface 474 and faces the shaft 870. The rotation angle sensor 334 is mounted across the range dividing line ED. The rotation angle sensor 334 includes angle detectors 134 and 234 in an electrically independent state in its inside. In FIG. 7, the angle detectors 134 and 234 are provided in a case, but the detectors 134 and 234 may be packaged separately.In the present embodiment, a region along the outer edge of the substrate 470, which is on the outside of a component region in which various electronic components are mounted, is referred to as an outer region. As shown in FIGS. 6, 7, 8 to 9, motor line connection portions 171 and 271 are respectively formed in the outer regions on both sides of the intermediate region cut line ED substantially parallel to the region cut line ED. The motor windings 180 and 280 are connected to the motor line connection portions 171 and 271, respectively, phase by phase.A control terminal connection region ES is provided via the first system region E 1 and the second system region E 2 in the outside region on a surface on which the microcomputers 150 and 250 and the custom ICs 155 and 255 are disposed. In the control terminal connection region ES, a first control terminal connection portion 172 is provided in the first system region E 1, and a second control terminal connection portion 272 is provided in the second system region E 2. The first control terminal 110 is connected to the first control terminal connection portion 172. The second control terminal 210 is connected to the second control terminal connection portion 272.A power terminal connection region EP is an outer region opposite to the control terminal connection region ES with respect to the center of the substrate, and outside the coils 145 and 245 and the capacitors 146 and 246 across the first system region E 1 and the second system region E 2. In the power terminal connection region EP, a first power source terminal connection portion 175 and a first ground terminal connection portion 176 are formed in the first system region E 1, and a second power source terminal connection portion 275 and a second ground terminal connection portion 276 are formed in the second system region E 2. Further, in the power terminal connection region EP, a third ground terminal connection portion 376 is formed across the first system region E 1 and the second system region E 2. The first power source terminal 105 is connected to the first power source terminal connection portion 175, and the first ground terminal 106 is connected to the first ground terminal connection portion 176, and the second power source terminal 205 is connected to the second power source terminal connection portion 275, and the second ground terminal 206 is connected to the second ground terminal connection portion 276, and the third ground terminal 306 is connected to the third ground terminal connection portion 376. For easy understanding, the power source terminal and the ground terminal are indicated by broken lines in FIGS. 8 and 9.In the present embodiment, the first system L 1 and the second system L 2 are connected to the common ground Gc. Therefore, as shown in FIG. 9, it is not necessary to separate the ground pattern for each system, and the common ground Gc may be formed in a single pattern across the first system region E 1 and the second system region E 2.Case connection portions 177 and 277 are formed on the substrate 470. In the present embodiment, there are two case connecting portions 177 and two case connecting portions 277, but the number of case connecting portions 177 and 277 is optional, and the number may be different from system to system. A fastener 882 (see FIG. 5 ) such as a screw is inserted through the housing connecting portions 177 and 277, and the substrate 470 is fixed to the frame rear end 835 by the fastener 882. In the present embodiment, the common ground Gc is exposed along the outer edges of the case connection portions 177 and 277 on the cover surface 471 and the motor surface 474. Here, using a conductive member as the fixing member 882, the common ground Gc and the motor housing 830 are electrically connected. Thereby, noises leaking outside from the driving device 40 can be reduced.Here, reference examples in which the mass is separated for each system are shown in FIGS. 15, 16, 17, 18 to 19. FIG. 15 is a block diagram corresponding to FIG. 3, and FIGS. 16, 17, 18 to 19 correspond to FIGS. 6, 7, 8 to 9, among which FIG. 16 shows the cover surface 471, FIG. 17 shows the motor surface 474, FIG. 18 shows the second layer 472, and FIG. 19 shows the third layer 473.When the first system ground G 1 and the second system ground G 2 are disconnected as in an ECU 19 of a drive device 49 according to the reference example, if there is a difference in ground potential between the systems due to ground fault or ground disconnection, there is a possibility that failure of circuit components or the like may occur due to leakage current via the signal lines 351 and 352. Therefore, it is necessary to provide a ground abnormality detection circuit, an inter-system communication interface circuit 391 such as a photo coupler for reducing leakage current, and the like. Moreover, components such as an inter-system connection capacitor 392 and package ground connection capacitors 197 and 297 may additionally be required to prevent the emission of high frequency electromagnetic noise generated by the mutual inductance and conduction capacitance of the motor windings 180 and 280, which may result in an increase in the number of components and / or limitations on the substrate mounting surface.Therefore, in the present embodiment, all the systems are connected to the common ground Gc in the ECU 10, and a redundant ground is provided by connecting the common ground Gc and the ground plane Gp to node connections between the number of nodes larger than the number of systems of the power sources. FIGS. 10 and 11 are diagrams schematically showing a redundant system including n number of systems. Redundant current sources VB(1) to VB(n) in n systems are connected to n or more systems of redundant circuits SYS(1) to SYS(n). Subscriptions "(1)" to "(n)" denote system numbers, where n is an integer of 2 or more. When a power supply system 1 is applied to the electric power steering apparatus 8 where n=2, the redundant circuits SYS( 1) to SYS(n) correspond to the circuit units 101 and 201, and the redundant power supplies VB( 1) to VB(n) correspond to the batteries 191, 291. In other words, the electric power steering apparatus 8 is a redundant system with n=2.The redundant circuits SYS( 1) to SYS(n) are each a circuit with functional redundancy in the sense of functional safety. Functional redundancy means that the circuit configuration and performance may be different between the redundant circuits as long as there is a minimum redundancy function for functional safety. All of the redundant circuits SYS(1) to SYS(n) are connected to the common ground Gc. Further, the common ground Gc and the vehicle body 500 serving as a ground plane are connected by a ground wiring portion 5 independently connecting (n+α) nodes. The node "+ α" may be considered as a "redundant node".Specifically, nodes NC( 1) to NC(n+α) in the common ground Gc and nodes NP( 1) to NP(n+α) on the vehicle body 500 that is the ground plane are connected by independent wirings. α is an integer equal to or greater than 1, and here, α is assumed to be 1. By connecting the common ground Gc and the vehicle body 500 to (n + α) independent wirings, the operation can be continued even when multipoint failures up to (α + 1) points have occurred.FIG. 11 shows resistances rB( 1) to rB(n) of the power supply line and resistances rG( 1) to rG(n+1) of the redundant ground wiring. The resistors rB( 1) to rB(n) and rG( 1) to rG(n+1) are wiring resistors and include contact resistors and harness resistors of wiring system connectors and terminals. Further, the resistors rB( 1) to rB(n) include the ground plane resistance and the negative electrode resistance of the battery.When the number of redundant systems is denoted by n, the number of functional safety guaranteed multipoint failures is denoted by m, the minimum operating voltage required for operation of each of the systems is denoted by VS#safe, the minimum operating current required for each of the systems at such time is denoted by IS#safe, and the guaranteed minimum battery voltage is denoted by VB#safe, the wiring resistance is set to satisfy an equation (1). Here, # is 1 to n and m<n. The term VGsafe in the equation (1) is a potential of the common ground Gc with respect to the potential of the vehicle body 500 which is a ground plane.As for the ground wiring, the worst case is that all failures concentrate on the ground wiring portion 5, thus, to avoid it, as a sum of the remaining operating currents IS#safe, when the (n-m) systems remain operating, a common ground potential VGsafe is set to be equal to or less than a minimum voltage VGsafe_min. Here, when the wiring resistor is referred to as rG( 1), rG(2),.. rG(n), rG(n+1) in descending order, the upper (n-m) parts of parallel resistance values rGsafe are each set to be equal to or lower than a value represented by an equation (2). In an actual circuit, for continuing normal operation even in other failures, in addition to the above, other considerations such as the degree of reliability of the terminal connection and / or the wire harness, the short circuit of each of the redundant system circuits is taken into account.As described above, the power supply system 1 of the present embodiment includes the n or more systems of the circuit units 101 and 201, the common ground Gc, and the ground wiring portion 5. the circuit units 101 and 201 are connected to each of the n systems of the batteries 191 and 291, respectively (where n is an integer of 2 or more). The common ground Gc is connected to all of the circuit units 101 and 201 in common. The ground wiring portion 5 connects the (n+α) parts of the common ground nodes NC( 1) to NC(n+α) provided in the common ground Gc and the (n+α) parts of the ground plane nodes NP( 1) to NP(n+α) provided in the vehicle body 500 independently, i.e., from node to node, by one-to-one connection. In this way, redundant circuits capable of withstanding multipoint failures are possible with a simple configuration without disconnection of the ground for each system.The common mass Gc and the vehicle body 500 are connected via the connectors 103, 203, and 303. Thereby, the common mass Gc and the vehicle body 500 can be suitably connected. Further, the connectors 103, 203, and 303 are independently provided for each of the nodes. Thereby, even when a connector is disconnected, the connection between the common mass Gc and the vehicle body 500 can be maintained by other connectors.When the number of multipoint failures ensuring the functional safety is referred to as m (where m<n), the parallel resistance value rGsafe between the vehicle body 500 and the common ground Gc is set based on the sum of the minimum operating currents IS#safe of the (n-m) systems and the minimum value of the common ground potential VGsafe. In this way, the operation can be continued even when multipoint failures concentrate on the ground wiring portion 5.(Second Embodiment)The second embodiment is shown in Figs. 12 to 14. In the above embodiment, connectors are provided according to the number of systems + α, and the common mass Gc and the vehicle body 500 are connected via independent connectors, i.e., different connectors, respectively. As shown in FIGS. 12 and 13, in an ECU 11 of a driving device 41 of the present embodiment, the number of connectors is 2, and the third connector 303 of the above embodiment is omitted. Instead, in the present embodiment, the redundant ground is provided by electrically connecting the motor housing 830 and the vehicle body 500.Specifically, as shown in FIG. 14, a connector 885 is disposed between the protrusion 832 and the fixing member 881, and a wire harness 886 electrically connected to the connector 885 is connected to the vehicle body 500 through a ground plane node NP 3, which is a node different from the ground plane nodes NP 1 and NP 2 connected to the ground terminals 106 and 206. In this way, as indicated by an arrow AG, the common mass Gc of the substrate 470 passes through the fixing member 882, the frame rear end 835, the case main body 831, the fixing member 881, the connection member 885, and the wire harness 886 to be connected to the vehicle body 500. In the present embodiment, the case main body 831 is connected to the vehicle body 500 via the wire harness 886. However, the housing main body 831 may be connected to the vehicle body 500 via a transmission case which is part of the reduction gear 89 to which the housing main body 831 is coupled.In the present embodiment, at least one common ground node is connected to the ground plane Gp via the motor case 830, which is a case for accommodating the circuit units 101 and 201. Thereby, the number of connectors can be reduced. Further, the present embodiment also provides the same advantages as those of the above-described embodiment.(Other Embodiments)In the first embodiment, the common ground node and the ground plane node are connected via separate connectors. In other embodiments, multiple terminals connecting the common ground node and the ground plane node may be provided in one connector. Moreover, the common ground node and the ground plane node may be directly connected by wiring such as a wire harness without passing through a connector.In the second embodiment, the common ground and the ground plane are connected via the motor housing. In other embodiments, the common ground and ground plane may be connected via a housing on the ECU side instead of via the motor housing. In other embodiments, the ECU may be provided independently of a control object such as an engine, and the common ground and the ground plane may be connected via a housing of the ECU. In such a case, the housing accommodating the circuit unit corresponds to a "housing". In the above embodiments, the ground plane is the vehicle body. In other embodiments, the ground plane may be different than the vehicle body.In the above embodiments, the number n of systems in the electric power steering apparatus is 2. Moreover, multiple parts may be provided for each system, such as multiple inverters and winding sets for a control unit. A set of motor windings may be provided for a plurality of inverters. In the above embodiment, the number of redundant nodes α is 1. in other embodiments, α may be two or more depending on the number of systems and the number of multipoint failures that ensure functional safety.In the above embodiment, the redundant current source is always supplied to each redundant circuit. Normally, however, only the main power source is connected to each redundant circuit, and is switched to the redundant power source only when an abnormality of the main power source is detected. Moreover, for each redundant system, the number of redundant power sources is reduced, and when a power failure occurs in one system, the power source of the abnormal system is turned off and various power supply systems are used. Moreover, the invention is applicable.In the above embodiments, the power supply system is applied to an electric power steering apparatus. In other embodiments, the power supply system may be applied to an on-vehicle device other than the electric power steering device or the electric power steering system, respectively, or to a device other than the on-vehicle device. The invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention.

Claims

A power supply system comprising: circuit units (101, 201) in a number of n or more systems respectively connected to n systems of power sources (191, 291), where n is an integer of two or more; a common ground (Gc) to which all of the circuit units are commonly connected; and a ground wiring portion (5) configured to provide node-to-node connection between common ground nodes provided in a number of (n+α), where α is an integer of 1 or more, in the common ground and ground plane nodes provided in a number of (n+α) in a ground plane (500), characterized in that when a number of multipoint failures ensuring functional safety is m (where m<n), a parallel resistance value between the ground plane and the common ground is set based on a sum of minimum operating currents of (n-m) systems and a minimum value of a common ground potential.The power supply system of claim 1, wherein the common ground node and the ground plane are connected via a connector (103, 203, 303).The power supply system according to claim 2, wherein the connector is independently provided for each of the nodes.The power supply system of claim 1, wherein at least one of the common ground nodes is connected to the ground plane via a housing (830) that houses the circuit unit.

Images