Control device

Abstract

To provide a control device capable of preventing failure propagation to another system.SOLUTION: An ECU 10 has a plurality of micro computers 150 and 250, inter-system communication circuits 152 and 252, internal power supply circuits 155 and 255, and protection circuits 160 and 260. The micro computers 150 and 250 control drive of a motor 80. A circuit configuration corresponding to each of the micro computers 150 and 250 is made a system. The internal power supply circuit 155 is provided for each system, and supplies power to the micro computer 150 and the inter-system communication circuit 152. The protection circuit 160 can block an internal power supply line Li1 from the internal power supply circuit 155 to the inter-system communication circuit 152 when an over-voltage abnormality that internal power supply voltage Vmi which is output voltage from the internal power supply circuit 155 becomes over-voltage occurs, or can control feeding to the inter-system communication circuit 152. Thus, failure propagation to another system can ben prevented.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a control device. [Background technology]

[0002] Conventionally, electric power steering systems with redundant drives are known. For example, in Patent Document 1, galvanic isolation exists between the two drive electronics. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] DE 102015104850 Summary of the Invention [Problem to be solved by the invention]

[0004] In a multi-system control circuit, if a fault occurs that causes an increase in the voltage of the internal power supply that supplies power to a microcomputer, etc., there is a risk that the normal control circuits will be destroyed by the voltage increase in the communication lines. As a countermeasure to this, it is possible to provide an insulating communication buffer such as a photocoupler for communication between the systems, but since the insulating communication buffer is a relatively large element, it is necessary to secure a relatively large mounting area on the board.

[0005] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a control device capable of preventing the propagation of a fault to other systems. [Means for solving the problem]

[0006] The control device of the present invention includes a plurality of control units (150, 250), an inter-system communication circuit (152, 252), an internal power supply circuit (155, 255), and a protection circuit (160, 260, 62-64). The control unit controls driving of a load (80). If a circuit configuration provided corresponding to each control unit is regarded as a system, the inter-system communication circuit is connected to another system that is a system corresponding to another control unit. An internal power supply circuit is provided for each system, and supplies power to the control units and the inter-system communication circuit. When an overvoltage abnormality occurs in which the output voltage from the internal power supply circuit becomes an overvoltage, the protection circuit can cut off an internal power supply line extending from the internal power supply circuit to the inter-system communication path, or limit the power supply to the inter-system communication circuit. This makes it possible to prevent the failure from propagating to the other system. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic configuration diagram of a steering system according to a first embodiment. [Diagram 2] FIG. 2 is a block diagram showing an ECU according to the first embodiment. [Diagram 3] 1 is a circuit diagram showing a protection circuit according to a first embodiment. [Figure 4] 1 is a circuit diagram showing a protection circuit according to a first embodiment. [Diagram 5] FIG. 2 is a circuit diagram showing a protection circuit for three systems according to the first embodiment. [Figure 6] FIG. 2 is a circuit diagram showing a protection circuit in the case of a common ground according to the first embodiment. [Figure 7] 1 is a schematic diagram showing an IC constituting an internal power supply circuit according to a first embodiment; [Figure 8] FIG. 2 is a schematic diagram showing a fuse pattern according to the first embodiment. [Figure 9] FIG. 11 is a circuit diagram showing a protection circuit according to a second embodiment. [Figure 10] FIG. 11 is a circuit diagram showing a protection circuit for three systems according to a second embodiment. [Figure 11] FIG. 11 is a circuit diagram showing a protection circuit in a case where a ground is common according to a second embodiment. [Figure 12] FIG. 11 is a circuit diagram showing a protection circuit according to a third embodiment. [Figure 13] FIG. 11 is a circuit diagram showing a protection circuit for three systems according to a third embodiment. [Figure 14] FIG. 11 is a circuit diagram showing a protection circuit in a case where a ground is common according to a third embodiment. [Figure 15] FIG. 13 is a circuit diagram showing a protection circuit according to a fourth embodiment. [Figure 16] FIG. 13 is an explanatory diagram showing the output characteristics of the overcurrent limiter circuit according to the fourth embodiment. [Figure 17] FIG. 13 is a circuit diagram showing a protection circuit for three systems according to a fourth embodiment. [Figure 18] FIG. 13 is a circuit diagram showing a protection circuit in a case where a ground is common according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the control according to the present invention will be described with reference to the drawings. In the following, in a plurality of embodiments, substantially the same configurations are given the same reference numerals and the description thereof will be omitted.

[0009] (First embodiment) A first embodiment is shown in Fig. 1 to Fig. 8. An ECU 10 as a control device of this embodiment is applied to, for example, an electric power steering device 8 for assisting the steering operation of a vehicle. Fig. 1 shows the configuration of a steering system 90 equipped with 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 gear 96, a rack shaft 97, wheels 98, the electric power steering device 8, etc.

[0010] The steering wheel 91 is connected to a steering shaft 92. A torque sensor 94 that detects steering torque is provided on the steering shaft 92. The torque sensor 94 has a first sensor unit 194 and a second sensor unit 294, and the sensors are duplicated so that each can detect its own failure. A pinion gear 96 is provided at the tip of the steering shaft 92. The pinion gear 96 meshes with a rack shaft 97. A pair of wheels 98 are connected to both ends of the rack shaft 97 via tie rods or the like.

[0011] When a driver turns a steering wheel 91, a steering shaft 92 connected to the steering wheel 91 rotates. The rotational motion of the steering shaft 92 is converted into linear motion of a rack shaft 97 by a pinion gear 96. A pair of wheels 98 are steered to an angle according to the amount of displacement of the rack shaft 97.

[0012] The electric power steering device 8 includes a drive device 40, a reduction gear 89, etc. The drive device 40 includes a motor 80, an ECU 10, etc. The reduction gear 89, which is a power transmission section, reduces the speed of rotation of the motor 80 and transmits it to a steering shaft 92. That is, the electric power steering device 8 of this embodiment is a so-called "column assist type", but it may also be a so-called "rack assist type" in which the rotation of the motor 80 is transmitted to a rack shaft 97, etc.

[0013] Motor 80 outputs all or part of the torque required for steering, and is driven by power supplied from batteries 190, 290 (see FIG. 2) serving as power sources, to rotate reduction gear 89 forward and reverse. Motor 80 is a three-phase brushless motor, but a motor other than a three-phase brushless motor may be used.

[0014] As shown in Fig. 2, the motor 80 has two sets of motor windings (not shown). Hereinafter, a configuration related to energization control of one of the motor windings is referred to as a first circuit section 100, and a configuration related to energization control of the other motor winding is referred to as a second circuit section 200. Electronic components constituting the first circuit section 100 and the second circuit section 200 are mounted on a board (not shown). All electronic components may be mounted on a single board, or may be mounted separately on multiple boards.

[0015] In this embodiment, since the first circuit section 100 and the second circuit section 200 are configured in substantially the same way, a detailed description of the second circuit section 200 will be omitted as appropriate, and the first circuit section 100 will be mainly described. Also, the combination of the first circuit section 100 and the motor windings connected thereto is referred to as a first system, and the combination of the second circuit section 200 and the motor windings connected thereto is referred to as a second system, and the first system will be mainly described as an own system and the second system as an other system. Also, when the second system is referred to as an own system, the corresponding configuration may be read differently.

[0016] The first circuit section 100 has an inverter 120, a motor relay section 123, an inverter driver circuit 125, a current detection section 130, a rotation angle sensor 135, a voltage detection section 136, a power supply relay 141, a reverse connection protection relay 142, a relay driver circuit 145, a communication driver circuit 147, a microcontroller 150, an integrated circuit section 151, an internal power supply circuit 155, and a protection circuit 160, etc.

[0017] The first circuit section 100 is supplied with power from a first battery 190. In this embodiment, the first battery 190 is, for example, a 48V power supply, and supplies power to the first circuit section 100 via a PIG terminal 191. The power of the first battery 190 is stepped down to, for example, 12V by a step-down circuit 193, and is supplied to the first circuit section 100 via an IG terminal 192. The configuration related to step-up and step-down can be designed appropriately according to the voltage of the first battery 190 and the voltage required by the first circuit section 100.

[0018] The first circuit section 100 is connected to a first sensor section 194 of the torque sensor 94 via a torque sensor terminal 195, and is connected to a vehicle communication network (not shown) via a communication terminal 196. The vehicle communication network is connected to the microcomputer 150 via a communication driver circuit 147 so as to be able to transmit and receive various information. Although the vehicle communication network in this embodiment is exemplified by a Controller Area Network (CAN), a network conforming to a standard other than CAN, such as CAN-FD (CAN with Flexible Data rate) or FlexRay, may also be used. The first circuit section 100 is connected to a ground G1 via a ground terminal 198.

[0019] The second circuit section 200 is supplied with power from a second battery 290. In this embodiment, the second battery 290 is, for example, a 48V power source, and supplies power to the second circuit section 200 via a PIG terminal 291. The power of the second battery 290 is stepped down to, for example, 12V by a step-down circuit 293, and is supplied to the second circuit section 200 via an IG terminal 292. The second circuit section 200 is connected to a second sensor section 294 of the torque sensor 94 via a torque sensor terminal 295, and is connected to a vehicle communication network (not shown) via a communication terminal 296. The vehicle communication network to which the first circuit section 100 is connected and the vehicle communication network to which the second circuit section 200 is connected may be the same or different. The second circuit section 200 is connected to a ground G2 via a ground terminal 298. In this embodiment, the grounds G1 and G2 are separated between the first system and the second system.

[0020] The inverter 120 is a three-phase inverter that converts the power of the motor windings of the first system. A motor relay unit 123 capable of switching between connection and disconnection of the inverter 120 and the motor windings is provided between the inverter 120 and the motor windings. The inverter driver circuit 125 outputs drive signals related to the on / off of switching elements (not shown) that constitute the inverter 120 and the motor relay unit 123, and the reverse connection protection relay 142. The capacitor 127 is connected in parallel with the inverter 120 and stores electric charge to smooth the power supplied to the inverter 120.

[0021] The current detection unit 130 is, for example, a shunt resistor provided in each phase, and detects the current flowing through each phase of the motor winding. The detection value is output to the microcomputer 150 via the integrated circuit unit 151. In Fig. 2, the integrated circuit unit 151 is described as "ASIC". The rotation angle sensor 135 detects the rotation of the motor 80, and outputs the detection value to the microcomputer 150.

[0022] The voltage detection unit 136 detects the voltage of the power supply line Lp1 connected to the PIG terminal 191, and outputs the detected value to the microcomputer 150. The power supply line Lp1 is connected to a choke coil 137 and a capacitor 138 that configure a filter circuit. The ground line Lg1 is provided with a break detection unit 139 that detects a ground break.

[0023] The power line Lp1 is provided with a power supply relay 141 and a reverse connection protection relay 142. When the relays 141 and 142 are configured with elements having parasitic diodes such as MOSFETs, it is desirable to connect the two elements in series so that the parasitic diodes are oriented in opposite directions. This makes it possible to prevent reverse current from flowing when the battery 190 is mistakenly connected in the opposite direction. The relays 141 and 142 may be mechanical relays. A relay driver circuit 145 outputs a drive signal related to the on / off of the power supply relay 141.

[0024] The microcomputers 150 and 250 perform various control calculations related to the drive control of the motor 80, and are provided so as to be able to transmit and receive information to and from each other. Power is supplied to the microcomputer 150 from an internal power supply circuit 155. A capacitor 156 is connected to the internal power supply circuit 155 (see FIG. 4). The capacitor 156 stabilizes the output voltage of the internal power supply circuit 155.

[0025] If a fault occurs that causes an increase in the output voltage (hereinafter referred to as "internal power supply voltage Vmi") of the internal power supply circuit 155 that supplies power to the microcomputer 150 and components related to inter-system communication, there is a risk that the fault will propagate as an overvoltage is applied to other systems that are normal via the inter-system communication line Lc. As a countermeasure against this, for example, an insulating communication buffer such as a photocoupler may be used for inter-system communication. If the insulating communication buffer is a large element, it will occupy a relatively large mounting area on the board.

[0026] Therefore, in this embodiment, a protection circuit 160 is provided for the internal power supply circuit 155. Details of the protection circuits 160, 260 are shown in Fig. 3 and Fig. 4. In Fig. 3 etc., interface circuits for signals connecting between systems, such as the SCI (Serial Communication Interface) and SPI (Serial Peripheral Interface) built into the microcomputer, general-purpose port signals, monitor signals of other ICs, CAN and LIN transceivers, and branches from the sensor I / F, are collectively referred to as inter-system communication circuits 152, 252. Also, Fig. 4 and subsequent figures mainly show the configuration for one system.

[0027] 3 and 4, the protection circuit 160 has a fusing portion 161 and a Zener diode 162. The fusing portion 161 is provided on the internal power supply line Li1 that connects the internal power supply circuit 155 and the inter-system communication circuit 152. The Zener diode 162 has a cathode connected to the internal power supply line Li1 and an anode connected to the ground G2, which is the other system ground, via a diode 163. The diode 163 is provided between the Zener diode 162 and the ground G2. The provision of the diode 163 prevents a current from flowing into the first system when the ground G2 is floated.

[0028] The protection circuit 260 includes a fuse part 261 and a Zener diode 262. The fuse part 261 is provided on an internal power line Li2 that connects the internal power supply circuit 255 and the inter-system communication circuit 252. The cathode side of the Zener diode 262 is connected to the internal power line Li2, and the anode side is connected to a ground G1, which is the ground of another system, via a diode 263. The diode 263 is provided between the Zener diode 262 and the ground G1. By providing the diode 263, current leakage to the second system when the ground G1 is floating is prevented.

[0029] Also, as shown in FIG. 5, when there are three or more systems and the grounds G1, G2, and G3 are separated for each system, Zener diodes 162 and diodes 163 are provided for each system and connected to the grounds G2 and G3 of other systems, respectively. Furthermore, as shown in FIG. 6, when the grounds are common for each system, the diode 163 provided on the ground side of the Zener diode 162 can be omitted.

[0030] Hereinafter, the protection circuit 160 will be mainly described. When the internal power line Li1 becomes overvoltage due to an abnormality in the internal power supply circuit 155, when the voltage of the internal power line Li1 becomes higher than the Zener voltage of the Zener diode 162, a large current flows, and the fuse part 161 is blown. Thereby, it is possible to prevent a high voltage due to an abnormality in the internal power supply circuit 155 from being applied to the second system, which is another system.

[0031] The protection circuit 160 is configured such that the fuse part 161 blows before the Zener diode 162 has an open failure. That is, when the fusing current of the fuse part 161 is If and the Zener disconnection current is Iz, the fuse part 161 and the Zener diode 162 are configured such that If < Iz.

[0032] Generally, when an overvoltage is applied to a bare chip of a Zener diode and the chip is overloaded, the cathode and anode are short-circuited and destroyed. If the current after the short circuit is large, the bonding may break, resulting in an open circuit failure. For this reason, it is preferable to use a Zener diode 162 in the protection circuit 160 that has a metal clip connection structure that is less susceptible to open circuit failure.

[0033] In this embodiment, for example, a board-mounted fuse such as a square chip current fuse or a mold-mounted current fuse is used as the fusing portion 161. Alternatively, a chip resistor with low resistance (for example, a few Ω) and low rated current may be used as the fusing portion 161.

[0034] 7, IC55 constituting internal power supply circuit 155 has die 551, output terminal 552 connected to inter-system communication circuit 152, and bonding wire 553 connecting die 551 and output terminal 552. Here, bonding wire 553 may be made to function as a fusing part by configuring bonding wire 553 so that its breakage current is smaller than that of Zener diode 162. In this case, the design is made so that dependent failures such as overheating and other system failures do not occur before bonding wire 553 breaks.

[0035] Also, as shown in Fig. 8, in the wiring pattern of the board constituting the internal power supply line Li1, a fuse pattern Pf, which is a locally thin pattern compared to other parts, may be formed at a portion of the current path P to function as a fusing portion. In this case, it is necessary to design the area above and below the portion where the fuse pattern Pf is formed so that no other wiring is provided. In Fig. 8, the portion where no pattern is formed is shown with a matte finish.

[0036] In this embodiment, a protection circuit 160 is configured by connecting a fusing part 161 and a Zener diode 162 in series between the internal power supply circuit 155 and the ground G2 of the other system, and by fusing the fusing part 161 when an abnormality occurs in the internal power supply circuit 155 causing an overvoltage, the overvoltage is prevented from being applied to the other system via the inter-system communication line Lc. This makes it possible to prevent the propagation of a fault to the other system via the inter-system communication circuit 152 when an overvoltage occurs in the internal power supply circuit 155.

[0037] As described above, the ECU 10 includes a plurality of microcomputers 150, 250, inter-system communication circuits 152, 252, internal power supply circuits 155, 255, and protection circuits 160, 260. The microcomputers 150, 250 control the driving of the motor 80. Here, the circuit configurations corresponding to the respective microcomputers 150, 250 are referred to as systems. The inter-system communication circuit 152 is connected to another system that is a system corresponding to the other microcomputer 250.

[0038] The internal power supply circuit 155 is provided for each system, and supplies power to the microcomputer 150 and the inter-system communication circuit 152. The protection circuit 160 can cut off the internal power supply line Li1 extending from the internal power supply circuit 155 to the inter-system communication circuit 152, or limit the power supply to the inter-system communication circuit 152, when an overvoltage abnormality occurs in which the internal power supply voltage Vmi, which is the output voltage from the internal power supply circuit 155, becomes an overvoltage.

[0039] This makes it possible to prevent the propagation of a fault to other systems due to an overvoltage caused by an abnormality in the internal power supply circuits 155 and 255 being applied to the other systems via the inter-system communication circuits 152 and 252 .

[0040] When the grounds are separated for each system, the protection circuits 160 and 260 are connected to the grounds of the other systems, which makes it possible to appropriately prevent an overvoltage caused by an abnormality in the internal power supply circuits 155 and 255 from being applied to the other systems.

[0041] The protection circuit 160 of this embodiment has a fusing part 161 provided on the internal power supply line Li1, and a Zener diode 162 provided on a wiring connecting the inter-system communication circuit 152 side of the fusing part 161 to the ground, and when an overvoltage abnormality occurs in which the internal power supply voltage Vmi becomes an overvoltage, the fusing part 161 melts to cut off the internal power supply line Li1. This makes it possible to appropriately prevent an overvoltage caused by an abnormality in the internal power supply circuits 155, 255 from being applied to the other system side.

[0042] The fusing parts 161, 261 are chip-type current fuses mounted on the substrate, or chip resistors that open at a lower voltage than a Zener diode, making it possible to configure the protection circuits 160, 260 using relatively small components.

[0043] Furthermore, fusion portion 161 may be a bonding wire 553 connected to an output terminal 552 connected to inter-system communication circuit 152 inside IC 55 constituting internal power supply circuit 155. This makes it possible to configure fusion portion 161 without increasing the number of components.

[0044] Furthermore, the fusing portion 161 may be a fuse pattern Pf that is locally formed thinner than other portions in a wiring pattern on a substrate that constitutes a current path P that connects the internal power supply circuit 155 and the inter-system communication circuit 152. This makes it possible to form the fusing portion 161 without increasing the number of components.

[0045] Second embodiment The second embodiment is shown in Figures 9 to 11. In the following embodiment, the protection circuit is mainly different from the above embodiment, so this point will be mainly described by taking the first system as an example. As shown in Figure 9, the protection circuit 62 has switching elements 621-623, a Zener diode 624, and resistors 625-627.

[0046] The switching elements 621 and 622 are P-channel MOSFETs, and are connected such that their sources are on the internal power supply circuit 155 side. The drain of the switching element 621 is connected such that it is on the inter-system communication circuit 152 side, and its gate is connected between the switching element 622 and a resistor 625. The drain of the switching element 622 is connected to the ground G1 via the resistor 625, and its gate is connected to the drain of the switching element 623.

[0047] The switching element 623 is an N-channel MOSFET, with its source connected to the ground G2, which is the other system ground, and its drain connected to the gate of the switching element 622. A wiring connecting the drain of the switching element 623 and the gate of the switching element 622 is connected to the internal power supply line Li1 via a resistor 626. The gate of the switching element 623 is connected to the anode side of a Zener diode 624. The Zener diode 624 has its cathode side connected to the internal power supply line Li1 and its anode side connected to the ground G2 via a resistor 627.

[0048] When the internal power supply circuit 155 is normal, no current flows through the Zener diode 624, so that a gate voltage is applied to the switching elements 622 and 621 via the resistor 626, turning on the switching elements 622 and 621. As a result, the power of the internal power supply circuit 155 is supplied to the inter-system communication circuit 152 via the switching element 621.

[0049] In the event that an overvoltage occurs on the internal power supply line Li1 due to an abnormality in the internal power supply circuit 155, when the internal power supply voltage Vmi becomes higher than the Zener voltage of the Zener diode 624, a gate voltage is applied to the switching element 623 via the Zener diode 624, and the switching element 623 is turned on. When a current flows from the internal power supply line Li1 to the switching element 623 side via the resistor 626, the voltage applied to the gate of the switching element 622 decreases, and the switching elements 622 and 621 are turned off. This makes it possible to prevent the overvoltage of the internal power supply circuit 155 from being applied to the other systems via the inter-system communication circuit 152.

[0050] As shown in Fig. 10, when there are three or more systems and the ground is separate for each system, the switching element 623, the Zener diode 624, and the resistor 627 are provided for each system and connected to the ground of each system. Also, when the ground is common to multiple systems as shown in Fig. 11, the source of the switching element 623 and the anode side of the Zener diode 624 are connected to the common ground.

[0051] The protection circuit 62 has a switching element 621 provided on the internal power supply line Li1, and a Zener diode 624 connected to the internal power supply line Li1 and ground. The switching element 621 is turned on when the internal power supply voltage Vmi is normal, and is turned off by a current flowing to the Zener diode 624 side when the internal power supply voltage Vmi is an overvoltage. This makes it possible to properly cut off the internal power supply line Li1 when an overvoltage occurs in the internal power supply voltage Vmi. In addition, the same effects as those of the above embodiment are achieved.

[0052] Third embodiment The third embodiment is shown in Fig. 12 to Fig. 14. As shown in Fig. 12, the protection circuit 63 has an overvoltage detection circuit 631, an overvoltage threshold generation circuit 632, and a cutoff relay 635. The overvoltage detection circuit 631 compares an internal power supply voltage Vmi, which is the voltage of the internal power supply line Li1, with a comparison voltage Vref generated by the overvoltage threshold generation circuit 632, and turns off the cutoff relay 635 when the internal power supply voltage Vmi is higher than the comparison voltage Vref. The cutoff relay 635 in this embodiment is a semiconductor relay, but may be a mechanical relay.

[0053] The overvoltage threshold generation circuit 632 is a circuit that generates an overvoltage threshold based on the ground G2, which is the ground of the other system, and for example, a circuit using a Zener diode or a circuit that generates an arbitrary voltage by amplifying a bandgap voltage using an amplifier or the like is used, and a value that does not exceed the circuit withstand voltage on the other system side is generated as a comparison voltage Vref.

[0054] As shown in Fig. 13, when there are three or more systems and the ground is separate for each system, an overvoltage threshold generation circuit 632 is provided for each system and connected to the ground of each system. A diode 633 is provided for each system. By providing the diode 633, the lowest value of the comparison voltages Vref generated by the overvoltage threshold generation circuits 632 of each system is output to the overvoltage detection circuit 631. This prevents circuit breakdown between the systems. Also, as shown in Fig. 14, when the ground is common to multiple systems, the overvoltage threshold generation circuit 632 is connected to the common ground.

[0055] When the internal power supply voltage Vmi exceeds the comparison voltage Vref, the cut-off relay 635 is turned off. Therefore, even if the internal power supply line Li1 becomes overvoltage, a high voltage exceeding the comparison voltage Vref can be prevented from being applied to other systems via the inter-system communication circuit 152.

[0056] The protection circuit 63 includes an overvoltage detection circuit 631 that monitors the internal power supply voltage Vmi, and a cutoff relay 635 that is provided in the internal power supply line Li1 and is turned off when an overvoltage of the internal power supply voltage Vmi is detected. This makes it possible to properly cut off the internal power supply line Li1 when an overvoltage of the internal power supply voltage Vmi occurs. In addition, the same effects as those of the above embodiment are achieved.

[0057] (Fourth embodiment) A fourth embodiment is shown in Fig. 15 to Fig. 18. As shown in Fig. 15, a protection circuit 64 has an overcurrent limiter circuit 641 and a Zener diode 642. The overcurrent limiter circuit 641 detects the current of the output line by a current mirror circuit of the output element or a current detection element (for example, a Hall IC or a shunt resistor) and limits the output circuit. The overcurrent limiter circuit 641 may be built into the internal power supply circuit 155 as long as its independence is maintained.

[0058] The Zener diode 642 is provided between the overcurrent limiter circuit 641 and the ground G2, which is the ground of the other system. By providing the Zener diode 642, chain destruction of the other system due to an overvoltage is prevented.

[0059] The output current limit value Ilim of the overcurrent limiter circuit 641 is set to a value that is greater than the maximum value Imax of the total current consumption of the circuits that supply power from the internal power supply circuit 155, and that does not cause the Zener diode 642 to open circuit and does not cause overheating that affects other systems. By designing the output limit characteristic of the overcurrent limiter circuit 641 to have a fold-back type drooping characteristic as shown in Fig. 16, the protection circuit 64 can be configured with a Zener diode 642 that is relatively small in size.

[0060] As shown in Fig. 17, when there are three or more systems and the ground is separate for each system, a Zener diode 642 is provided for each system and connected to the ground of each system. Also, as shown in Fig. 18, when the ground is common to multiple systems, the anode side of the Zener diode 642 is connected to the common ground.

[0061] The protection circuit 64 of this embodiment has an overcurrent limiter circuit 641 provided at the output section of the internal power supply circuit 155, and is capable of limiting power supply to the inter-system communication circuit 152 when an overvoltage abnormality occurs. This makes it possible to appropriately limit the voltage to the inter-system communication circuit 152 when an overvoltage occurs in the internal power supply voltage Vmi. In addition, the same effects as those of the above embodiment are achieved.

[0062] In the embodiment, the ECU 10 corresponds to the "control device", the motor 80 corresponds to the "load", the microcomputers 150 and 250 correspond to the "controller", the switching element 621 corresponds to the "switching element", and the internal power supply voltage Vmi corresponds to the "output voltage from the internal power supply circuit".

[0063] (Other embodiments) In the above embodiment, an example in which the number of systems is two or three has been described. In other embodiments, the number of systems may be four or more. In the above embodiment, the load is a motor. In other embodiments, the load may be a so-called motor generator that combines the functions of an electric motor and a generator, or may be something other than a motor. In the above embodiment, the control device is applied to an electric power steering device. In other embodiments, the control device may be applied to a device other than an electric power steering device.

[0064] The control unit and the method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor and a memory programmed to execute one or more functions embodied in a computer program. Alternatively, the control unit and the method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described in the present disclosure may be realized by one or more dedicated computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured with one or more hardware logic circuits. In addition, the computer program may be stored in a computer-readable non-transient tangible recording medium as instructions executed by a computer. As described above, the present invention is not limited to the above embodiment, and can be implemented in various forms within the scope of the invention. [Explanation of symbols]

[0065] 10 ECU (control unit) 150, 250... Microcomputer (control unit) 152, 252...Intersystem communication circuit 155, 255...Internal power supply circuit 160, 260, 62~64...protection circuit 161, 261...Fusing part 162, 262...Zener diode 621: Switching element 624: Zener diode 631: Overvoltage detection circuit 635: Cut-off relay

Claims

1. A plurality of control units (150, 250) for controlling the driving of the load (80); When the circuit configuration provided corresponding to each of the control units is regarded as a system, an inter-system communication circuit (152, 252) connected to another system corresponding to the other control unit, An internal power supply circuit (155, 255) provided for each system and supplying power to the control unit and the inter-system communication circuit; a protection circuit (160, 260, 62 to 64) capable of cutting off an internal power line extending from the internal power supply circuit to the inter-system communication circuit or limiting power supply to the inter-system communication circuit when an overvoltage abnormality occurs in which the output voltage from the internal power supply circuit becomes an overvoltage; A control device comprising:

2. The ground is separated for each system, The control device according to claim 1 , wherein the protection circuit is connected to a ground of another system.

3. 3. The control device according to claim 1, wherein the protection circuit has a fusion portion (161, 261) provided in the internal power supply line, and a Zener diode (162, 262) provided in a wiring connecting the inter-system communication circuit side of the fusion portion to ground.

4. 4. The control device according to claim 3, wherein the fusing portion is a chip-type current fuse mounted on a substrate, or a chip resistor that breaks down at a lower voltage than the Zener diode.

5. 4. The control device according to claim 3, wherein the fused portion is a bonding wire (553) connected to an output terminal (552) connected to the inter-system communication circuit inside an IC (55) constituting the internal power supply circuit.

6. 4. The control device according to claim 3, wherein the fusion portion is a fuse pattern that is locally thinner than other portions in a wiring pattern on a substrate that constitutes a current path connecting the internal power supply circuit and the inter-system communication circuit.

7. The protection circuit (62) has a switching element (621) provided on the internal power supply line, and a Zener diode (624) connected to the internal power supply line and ground, 3. The control device according to claim 1, wherein the switching element is turned on when the output voltage is normal, and turned off when the output voltage is an overvoltage by allowing a current to flow to the Zener diode.

8. 3. The control device according to claim 1, wherein the protection circuit (63) includes an overvoltage detection circuit (631) that monitors the output voltage, and a cut-off relay (635) that is provided in the internal power supply line and is turned off when an overvoltage of the output voltage is detected.

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