Vehicle power supply device and abnormality detection method for vehicle power supply device

Abstract

The present application relates to a vehicle power supply device (1) including: a power supply line that constitutes a part of a power supply path that supplies power from an external power supply to a power supply target; a discharge line (Lsu) that branches from the power supply line; an auxiliary power supply (41) that is connected to the power supply line via the discharge line; a step-up circuit (42) that is provided in the discharge line; a backup relay that is provided on the output side of the step-up circuit in the discharge line; and a regeneration absorption circuit (46). The regeneration absorption circuit includes an absorption line (Lab) that connects the power supply line to ground, and a Zener diode (71) that is provided in the absorption line. The vehicle power supply device further includes a high-voltage generation diode (81) that is provided on the upstream side of the Zener diode in the absorption line, and a branch line (Lbr) that branches from a connection point between the step-up circuit and the backup relay in the discharge line, and is connected to a connection point between the high-voltage generation diode and the Zener diode in the absorption line.

Description

Technical Field

[0001] This invention relates to a power supply device for vehicles and a method for detecting abnormalities in the power supply device for vehicles. Background Technology

[0002] For example, Patent Document 1 discloses a vehicle power supply device that supplies power to the steering system of a vehicle. As described in that document, the motor used for the steering system sometimes generates regenerative power due to the reaction force when, for example, the wheel collides with a curb.

[0003] In view of this, the vehicle power supply device of Patent Document 1 includes a main battery, an auxiliary battery, a discharge circuit, a charging circuit, and a high-voltage suppression circuit. The discharge circuit and the charging circuit are connected in parallel between the auxiliary battery and the steering system. The discharge circuit operates when supplying power from the auxiliary battery to the steering system, and the charging circuit operates when charging the auxiliary battery based on power from the main battery. The high-voltage suppression circuit is provided on the power line connecting the discharge circuit and the charging circuit to the steering system. The high-voltage suppression circuit is configured to cause current to flow to ground when the voltage of the power line increases due to regenerative power generated by the steering system. This suppresses component failure of the vehicle power supply device caused by the voltage increase in the aforementioned power line.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2018-113814

[0005] When the high-voltage suppression circuit malfunctions, it may fail to operate properly and may be unable to absorb the regenerative power generated by the steering mechanism. However, Patent Document 1 does not mention the detection of malfunctions in the high-voltage suppression circuit, leaving room for improvement in this regard.

[0006] Furthermore, this problem is not limited to the case where the power supply object is a steering device; it can occur whenever the power supply object generates regenerative power. Summary of the Invention

[0007] One aspect of this disclosure provides a vehicle power supply device configured to supply power to a power source. The vehicle power supply device includes: a power line configured as part of a power supply path for supplying power from an external power source to the power source; a drive relay disposed on the power line; a discharge line extending from a connection point on the power line downstream of the drive relay; an auxiliary power source connected to the power line via the discharge line; a boost circuit disposed on the discharge line configured to boost and output the voltage of the auxiliary power source; a backup relay disposed on the output side of the boost circuit on the discharge line; and a regenerative absorption circuit configured to absorb regenerated power generated in the power source. The regenerative absorption circuit includes: an absorption line connecting a portion of the power line downstream of the drive relay to ground; and a Zener diode disposed on the absorption line configured to allow current to flow from the power line to ground when the reverse voltage applied to the Zener diode is greater than or equal to the Zener voltage. The vehicle power supply device further includes: a high-voltage generating diode disposed upstream of the Zener diode in the absorption line, configured to allow current to flow from the power line to the Zener diode and limit current to flow from the Zener diode to the power line; and a branch line extending from the connection point between the boost circuit and the backup relay in the discharge line and connecting to the connection point between the high-voltage generating diode and the Zener diode in the absorption line.

[0008] Another aspect of this disclosure provides a method for detecting anomalies in a vehicle power supply device configured to supply power to a power source. The vehicle power supply device includes: a power line, which forms part of a power supply path for supplying power from an external power source to the power source; a drive relay disposed on the power line; a discharge line extending from a connection point on the power line downstream of the drive relay; an auxiliary power source connected to the power line via the discharge line; a boost circuit disposed on the discharge line, configured to boost and output the voltage of the auxiliary power source; a backup relay disposed on the output side of the boost circuit on the discharge line; and a regenerative absorption circuit configured to absorb regenerated power generated in the power source. The regenerative absorption circuit includes: an absorption line connecting a portion of the power line downstream of the drive relay to ground; and a Zener diode disposed on the absorption line, configured to allow current to flow from the power line to ground when the reverse voltage applied to the Zener diode is greater than or equal to the Zener voltage. The vehicle power supply device further includes: a high-voltage generating diode disposed upstream of the Zener diode in the absorption line, configured to allow current to flow from the power line to the Zener diode and limit current to flow from the Zener diode to the power line; and a branch line extending from the connection point between the boost circuit and the backup relay in the discharge line, and connecting to the connection point between the high-voltage generating diode and the Zener diode in the absorption line. The anomaly detection method includes: detecting a determination voltage as the voltage on the branch line; and, when the determination voltage is outside a predetermined voltage range including the Zener voltage, and the backup relay is switched to an off state and the boost circuit is controlled to output a voltage higher than the Zener voltage, determining that the Zener diode has malfunctioned. Attached Figure Description

[0009] Figure 1 This is a schematic structural diagram of the vehicle power supply device and its power supply object, namely the steering device, according to the embodiment.

[0010] Figure 2 yes Figure 1 A block diagram of the electrical structure of a vehicle power supply unit.

[0011] Figure 3 It means by Figure 2 A flowchart showing the sequence of various processes performed by the power control circuit.

[0012] Figure 4 It means Figure 2 A graph illustrating the output voltage change of an example of a power control circuit performing backup processing. Detailed Implementation

[0013] Hereinafter, an embodiment of a vehicle power supply device and a method for detecting anomalies in a vehicle power supply device will be described with reference to the accompanying drawings.

[0014] (Overall structure)

[0015] like Figure 1 As shown, the vehicle power supply unit 1 of this embodiment supplies power to the steering system 2 of the vehicle, which is the object of power supply. The steering system 2 is a steer-by-wire type steering system. The steering system 2 includes: an operating unit 4, which is operated by the driver via a steering wheel 3; a steering unit 6, which turns the steering wheels 5; and a steering control device 7, which controls the operation of the operating unit 4 and the steering unit 6. The steering system 2 may be a structure in which the power transmission paths between the operating unit 4 and the steering unit 6 are always mechanically separated, or it may be a structure in which the operating unit 4 and the steering unit 6 can be selectively mechanically separated by a clutch.

[0016] The operating unit 4 includes an operating-side motor 11. The operating-side motor 11 generates an operating reaction force against the driver's operation of the steering wheel 3. The steering unit 6 includes a steering-side motor 12. The steering-side motor 12 generates a steering force that turns the steering wheel 5.

[0017] The steering control unit 7 is connected to an operating-side motor 11 and a steering-side motor 12. The operating-side motor 11 may have multiple coil groups powered by multiple electrically independent power supply systems. That is, the operating-side motor 11 can be an electrically redundant motor. Similarly, the steering-side motor 12 can also be an electrically redundant motor. Alternatively, both the operating-side motor 11 and the steering-side motor 12 can be non-electrically redundant. In the illustrated example, the operating-side motor 11 and the steering-side motor 12 are non-electrically redundant. The steering control unit 7 controls the operation of the operating-side motor 11 and the steering-side motor 12 by supplying them with power. The power supplied to the operating-side motor 11 and the power supplied to the steering-side motor 12 are supplied from an external power source 13 mounted on the vehicle via a vehicle power supply unit 1.

[0018] In detail, the steering control device 7 has an operating-side control unit 21 and a steering-side control unit 22. The operating-side control unit 21 controls the operation of the operating-side motor 11. The steering-side control unit 22 controls the operation of the steering-side motor 12. The operating-side control unit 21 and the steering-side control unit 22 are connected to each other via a local network 23 such as a serial communication network. The steering control device 7 of this embodiment is a single control device having an operating-side control unit 21 and a steering-side control unit 22. In other embodiments, the steering control device 7 may also include a control device including an operating-side control unit 21 and another control device including a steering-side control unit 22 that is mechanically separate from the control device.

[0019] The operation-side control unit 21 includes an operation-side drive circuit 24 and an operation-side control circuit 25 that controls the operation-side drive circuit 24. When the operation-side motor 11 has an electrically redundant structure, the operation-side control unit 21 may have multiple operation-side drive circuits 24 corresponding to multiple coil groups. In this case, the operation-side control unit 21 may have multiple operation-side control circuits corresponding to multiple operation-side drive circuits 24, or it may have a single operation-side control circuit.

[0020] The operating-side drive circuit 24 is a typical PWM inverter, for example, with multiple switching elements such as FETs or IGBTs. The operating-side control circuit 25 controls the operation of the operating-side drive circuit 24 by outputting control signals that specify the duty cycle of each switching element. That is, the control signals are gate on / off signals that specify the on / off state. The duty cycle refers to the proportion of the on-time of the switching element in the pulse period.

[0021] The operation-side control circuit 25 may consist of (1) one or more processors that operate according to a computer program (software), (2) one or more dedicated hardware circuits (e.g., ASICs) that execute at least a portion of various processes, or (3) a combination thereof. The processor includes a central processing unit (CPU) and memories such as RAM and ROM, which store program code or instructions configured to cause the CPU to perform processes. Memory, i.e., non-transitory computer-readable media, includes any available media accessible by a general-purpose or special-purpose computer. The various controls performed by the operation-side control circuit 25 are implemented by the CPU executing programs stored in memory at predetermined operation cycles.

[0022] The operating side control circuit 25 calculates a reaction force control quantity as a target value for the operating reaction force based on the detection results of various sensors (not shown) and information obtained from the steering side control unit 22 via the local network 23. Then, the operating side control circuit 25 generates a control signal with a duty cycle corresponding to the reaction force control quantity. As a result, the operating side control circuit 25 controls the power supply to the operating side motor 11.

[0023] The steering side control unit 22 is configured the same as the operating side control unit 21. That is, the steering side control unit 22 includes a steering side drive circuit 26 and a steering side control circuit 27 that controls the steering side drive circuit 26.

[0024] The steering-side control circuit 27 calculates a steering control quantity as a target value for the steering force based on the detection results of various sensors and information obtained from the operation-side control unit 21 via the local network 23. Then, the steering-side control circuit 27 generates a control signal with a duty cycle corresponding to the steering control quantity. As a result, the steering-side control circuit 27 controls the power supply to the steering-side motor 12.

[0025] (Power supply path)

[0026] The steering control unit 7 is connected to an external power source 13 via the vehicle power supply unit 1. Power from the external power source 13 is then supplied to the steering control unit 7 via the vehicle power supply unit 1. The external power source 13 is, for example, a secondary battery. The external power source 13 can be charged using a generator such as an alternator (not shown).

[0027] Specifically, the steering control device 7 is connected to the external power supply 13 via the drive power line Lp and the control power line Lc. The control power line Lc branches off from the connection point PO of the drive power line Lp. The vehicle power supply unit 1 spans both the drive power line Lp and the control power line Lc. The drive power line Lp includes an upstream drive power line Lpu, which is a power supply path upstream of the vehicle power supply unit 1; and a downstream drive power line Lpd, which is a power supply path downstream of the vehicle power supply unit 1. The control power line Lc includes an upstream control power line Lcu, which is a power supply path upstream of the vehicle power supply unit 1; and a downstream control power line Lcd, which is a power supply path downstream of the vehicle power supply unit 1.

[0028] The upstream control power line Lcu is equipped with a control relay 32 that is linked to the vehicle's start switch 31. The start switch 31 is a switch operated to start or stop the vehicle's driving source, such as an ignition switch or a power switch. When the start switch 31 is operated to the ON state, the control relay 32 switches to the ON state, and the control power line Lc is turned on. When the start switch 31 is operated to the OFF state, the control relay 32 switches to the OFF state, and the control power line Lc is turned off.

[0029] The downstream drive power line Lpd branches downstream and connects to the operating side drive circuit 24 and the steering side drive circuit 26. The downstream control power line Lcd branches downstream and connects to the operating side control circuit 25 and the steering side control circuit 27.

[0030] (Vehicle power supply unit 1)

[0031] The vehicle power supply unit 1 is input with a start signal Sig indicating the on / off state of the start switch 31, and an external power supply voltage signal Sve indicating the voltage of the external power supply 13, i.e., the external power supply voltage Vex. The external power supply voltage signal Sve is output from the voltage sensor 33. When the external power supply voltage Vex of the external power supply 13 is above the drop determination threshold Vthlo, the vehicle power supply unit 1 determines that the external power supply 13 is normal and supplies power from the external power supply 13 to the steering device 2. On the other hand, when the external power supply voltage Vex is below the drop determination threshold Vthlo, the vehicle power supply unit 1 supplies power from the auxiliary power supply 41 (described later) to the steering device 2.

[0032] In detail, such as Figure 2 As shown, the vehicle power supply unit 1 includes an auxiliary power supply 41, a boost circuit 42, a buck circuit 43, a regulator 44, a power control circuit 45 as an abnormality detection circuit, a regenerative absorption circuit 46, and wires that connect these circuit components to each other.

[0033] The wiring of the vehicle power supply unit 1 includes an internal drive power line Lpi, which forms part of the drive power line Lp, and an internal control power line Lci, which forms part of the control power line Lc. The internal drive power line Lpi is located between the upstream drive power line Lpu and the downstream drive power line Lpd. The internal drive power line Lpi is equipped with a drive relay 47. The internal control power line Lci is located between the upstream control power line Lcu and the downstream control power line Lcd.

[0034] The wiring of the vehicle power supply unit 1 includes: a discharge line Lsu extending from the internal drive power line Lpi; and a charging line Lsd branching from the internal drive power line Lpi and connected in parallel with the discharge line Lsu. Both the discharge line Lsu and the charging line Lsd branch from a connection point P1 downstream of the drive relay 47 in the internal drive power line Lpi. The discharge line Lsu and the charging line Lsd merge on the side opposite to the connection point P1.

[0035] The auxiliary power supply 41 is, for example, a capacitor. The auxiliary power supply 41 is capable of charging and discharging. The auxiliary power supply 41 is connected to the internal drive power supply line Lpi via the discharge line Lsu and the charging line Lsd.

[0036] A boost circuit 42 is provided on the discharge line Lsu. The boost circuit 42 boosts the auxiliary power supply voltage Vsp, which serves as the voltage of the auxiliary power supply 41, and outputs it. On the input side of the boost circuit 42 in the discharge line Lsu, i.e., the side connected to the auxiliary power supply 41, a first switching element 51 is provided. On the output side of the boost circuit 42 in the discharge line Lsu, i.e., the side where the connection point P1 is located, a second switching element 52, serving as a backup relay, is provided. That is, on the discharge line Lsu, the first switching element 51, the boost circuit 42, and the second switching element 52 are sequentially arranged from the auxiliary power supply 41 toward the connection point P1. The boost circuit 42 is, for example, a DC-DC converter. The boost circuit 42 includes a boost control circuit (not shown). The boost circuit 42 adjusts the on / off ratio of the internal switching elements through the boost control circuit to boost the input voltage to a preset boost voltage Vsu and output it. The operation and shutdown of the boost control circuit, i.e., the operation and shutdown of the boost circuit 42, are controlled by the power control circuit 45.

[0037] A step-down circuit 43 is provided on the charging cable Lsd. The step-down circuit 43 steps down the external power supply voltage Vex of the external power supply 13 and outputs it. On the input side of the step-down circuit 43 in the charging cable Lsd, i.e., on the side where the connection point P1 is located, a third switching element 53 is provided. On the output side of the step-down circuit 43 in the charging cable Lsd, i.e., on the side connected to the auxiliary power supply 41, a fourth switching element 54 is provided. That is, on the charging cable Lsd, from the connection point P1 toward the auxiliary power supply 41, the third switching element 53, the step-down circuit 43, and the fourth switching element 54 are arranged in sequence. The step-down circuit 43 is, for example, a DC-DC converter. The step-down circuit 43 has a step-down control circuit (not shown). The step-down circuit 43 adjusts the on / off ratio of the internal switching elements through the step-down control circuit to step down the input voltage to a preset step-down voltage Vsd and output it. The operation and stop of the step-down control circuit, i.e., the operation and stop of the step-down circuit 43, are controlled by the power control circuit 45.

[0038] The drive relay 47, the first switching element 51, the second switching element 52, the third switching element 53, and the fourth switching element 54 are semiconductor switches such as FETs or IGBTs. The on / off states of these switching elements are controlled by the power control circuit 45. Furthermore, for ease of illustration, the cables for signals output from the power control circuit 45 to each circuit component are not shown.

[0039] The internal control power line Lci branches downstream into a first internal control power line Lci1 and a second internal control power line Lci2. The first internal control power line Lci1 is connected to the regulator 44. The second internal control power line Lci2 is connected to the operating side control circuit 25 and the steering side control circuit 27 via the downstream control power line Lcd.

[0040] The wiring of the vehicle power supply unit 1 includes a first backup line Lbk1 and a second backup line Lbk2 branching from the discharge line Lsu. The first backup line Lbk1 and the second backup line Lbk2 branch off from the boost circuit 42 and the second switching element 52 in the discharge line Lsu. The first backup line Lbk1 is connected to the first internal control power line Lci1 at connection point P2. The second backup line Lbk2 is connected to the second internal control power line Lci2 at connection point P3.

[0041] Diodes 61 and 62 are provided upstream of the connection point P2 in the first internal control power line Lci1 and the first backup line Lbk1. Diodes 61 and 62 allow current to flow from the upstream side to the downstream side and restrict current flow from the downstream side to the upstream side. Diodes 61 and 62 constitute a selection circuit that supplies the larger of the voltage supplied by the external power supply 13 and the voltage supplied by the auxiliary power supply 41 to the regulator 44.

[0042] Diodes 63 and 64 are provided upstream of the connection point P3 in the second internal control power line Lci2 and the second backup line Lbk2. Diodes 63 and 64 allow current to flow from the upstream side to the downstream side and restrict current flow from the downstream side to the upstream side. Diodes 63 and 64 constitute a selection circuit that supplies the larger of the voltage supplied by the external power supply 13 and the voltage supplied by the auxiliary power supply 41 to the operating side control circuit 25 and the steering side control circuit 27.

[0043] The regulator 44 adjusts the input voltage to a preset control circuit voltage. The power control circuit 45 is connected to the regulator 44 and operates based on the power supplied from the regulator 44. The hardware structure of the power control circuit 45 can be the same as that of the operation-side control circuit 25.

[0044] The power control circuit 45 is input with the aforementioned start signal Sig and the external power supply voltage signal Sve. Furthermore, the power control circuit 45 is connected to a voltage sensor 65 that detects the auxiliary power supply voltage Vsp of the auxiliary power supply 41. Based on the input signals and the detected auxiliary power supply voltage Vsp, the power control circuit 45 performs various processes (controls).

[0045] The regenerative absorption circuit 46 absorbs regenerative power generated in the steering motor 12, for example, by the reaction force when the steering wheel 5 collides with a curb. The regenerative absorption circuit 46 includes an absorption line Lab, a Zener diode 71, a fuse 72, a regeneration switching element 73, and an absorption operation switching circuit 74.

[0046] The absorber line Lab connects the portion of the internal drive power line Lpi that is downstream of the drive relay 47 to ground. In the illustrated example, the absorber line Lab extends from the connection point in the internal drive power line Lpi that is downstream of the connection point P1.

[0047] Zener diode 71 is located on the absorption line Lab. When the applied reverse voltage exceeds a preset Zener voltage Vze (also known as the breakdown voltage), Zener diode 71 allows current to flow from the cathode to the anode while maintaining the voltage near the Zener voltage Vze. Applying a reverse voltage to Zener diode 71 means applying a voltage with the cathode at a higher potential than the anode. Specifically, the cathode of Zener diode 71 is connected to the internal drive power line Lpi via a high-voltage generating diode 81 (described later) and a fuse 72, while the anode is connected to ground via a regeneration switching element 73. Thus, when the reverse voltage applied to Zener diode 71 reaches or exceeds the Zener voltage Vze, current begins to flow through Zener diode 71 to ground.

[0048] Fuse 72 is located upstream of Zener diode 71 in the snubber line Lab. Fuse 72 melts when a predetermined current flows through the snubber line Lab, thereby disconnecting the snubber line Lab. The predetermined current is, for example, the current flowing through the internal drive power line Lpi via the snubber line Lab when a ground fault occurs while the external power supply 13 is supplying power to the internal drive power line Lpi.

[0049] The regeneration switching element 73 is disposed downstream of the Zener diode 71 in the absorption line Lab. The regeneration switching element 73 is a semiconductor switch such as a FET or an IGBT.

[0050] The absorption action switching circuit 74 controls the on / off state of the regeneration switching element 73 based on the output voltage Vout from the internal drive power line Lpi to the operation-side drive circuit 24 (operation-side motor 11) and the steering-side drive circuit 26 (steering-side motor 12). In the illustrated example, a voltage sensor 75 for detecting the output voltage Vout is provided downstream of the connection point P1 in the internal drive power line Lpi. The voltage sensor 75 outputs the detected output voltage Vout to the absorption action switching circuit 74. When the output voltage Vout reaches or exceeds a preset turn-on voltage Von, the absorption action switching circuit 74 controls the regeneration switching element 73 to be in the on state. When the output voltage Vout is lower than a preset cut-off voltage Voff while the regeneration switching element 73 is in the on state, the absorption action switching circuit 74 controls the regeneration switching element 73 to be in the off state. The turn-on voltage Von is initially set to be greater than the external power supply voltage Vex, the boost voltage Vsu, and the Zener voltage Vze. In other embodiments, the on-state voltage Von can be set to approximately the same value as the Zener voltage Vze. The off-state voltage Voff is initially set to a value less than the on-state voltage Von. In this embodiment, the on-state voltage Von and the off-state voltage Voff can be changed from their initial values ​​by the power control circuit 45.

[0051] Next, the various processes performed by the power control circuit 45 will be explained.

[0052] When the start switch 31 is activated and the control relay 32 switches to the ON state, power from the external power supply 13 is supplied to the power control circuit 45. Thus, the power control circuit 45 begins to operate.

[0053] like Figure 3 As shown, after the power control circuit 45 starts operating, it performs an initial check process (step 101). In the initial check process, it performs one or more anomaly determinations to detect abnormalities in the vehicle power supply unit 1. These anomaly determinations include, for example, determining whether a short circuit fault has occurred in the first switching element 51, the second switching element 52, the third switching element 53, and the fourth switching element 54. Furthermore, one or more anomaly determinations include an anomaly determination in the regenerative absorption circuit 46, which will be described later. If the power control circuit 45 determines that an abnormality has occurred in the vehicle power supply unit 1, it may display its indication on a display (not shown).

[0054] Next, after the initial inspection process is completed, the power control circuit 45 performs a charging process (step 102). The charging process is to charge the auxiliary power supply 41 until the auxiliary power supply voltage Vsp of the auxiliary power supply 41 reaches the standby voltage Vsb.

[0055] After the charging process is completed, the power control circuit 45 supplies power from the external power source 13 to the steering control device 7 while performing standby processing (step 103). Standby processing includes: determining whether the external power supply voltage Vex of the external power source 13 has decreased (step 103a); and determining whether the start switch 31 has been switched to the off state (step 103b). Whether the external power supply voltage Vex has decreased is determined based on whether the external power supply voltage Vex is above the decrease determination threshold Vthlo.

[0056] During charging and standby processing, the power control circuit 45 controls the first switching element 51, the third switching element 53, and the fourth switching element 54 to be in the on state, while simultaneously controlling the second switching element 52 to be in the off state. Furthermore, the power control circuit 45 activates the boost circuit 42 and the buck circuit 43. As a result, the auxiliary power supply 41 is charged based on the buck voltage Vsd output from the buck circuit 43.

[0057] When the external power supply voltage Vex of the external power supply 13 drops during standby processing, i.e., when the external power supply voltage Vex is less than the drop determination threshold Vthlo (step 103a: no), the power control circuit 45 performs backup processing (step 104). Backup processing is the process of stopping the power supply from the external power supply 13 to the steering control device 7 and supplying power from the auxiliary power supply 41 to the steering control device 7.

[0058] In backup processing, the power control circuit 45 controls the first switching element 51 and the second switching element 52 to be in the conducting state, while controlling the drive relay 47, the third switching element 53, and the fourth switching element 54 to be in the de-energized state. Furthermore, the power control circuit 45 keeps the boost circuit 42 operating while stopping the buck circuit 43. Thus, the voltage output from the boost circuit 42 is supplied to the steering control device 7. As described above, since the boost circuit 42 has also been activated during standby processing, by executing backup processing, when the second switching element 52 is switched to the conducting state, power is immediately supplied to the steering control device 7 from the auxiliary power supply 41.

[0059] In this embodiment, the power control circuit 45 continues backup processing as long as the power of the auxiliary power supply 41 is available, and stops when the power of the auxiliary power supply 41 is exhausted. In other embodiments, the power control circuit 45 may also determine during backup processing whether the external power supply voltage Vex of the external power supply 13 has reached or exceeded the drop determination threshold Vthlo. In this embodiment, when the external power supply voltage Vex reaches or exceeds the drop determination threshold Vthlo, the power control circuit 45 resumes standby processing.

[0060] When the start switch 31 is operated to the off state during standby processing (step 103b: Yes), the power control circuit 45 performs a discharge process (step 105). The discharge process is to discharge the auxiliary power supply 41 until the auxiliary power supply voltage Vsp of the auxiliary power supply 41 reaches the stop voltage Vst. The stop voltage Vst is set to a value lower than the standby voltage Vsb.

[0061] During the discharge process, the power control circuit 45 controls the first switching element 51 to be in the on state, while simultaneously controlling the second switching element 52, the third switching element 53, and the fourth switching element 54 to be in the off state. Then, the power control circuit 45 discharges the power from the auxiliary power supply 41 by activating the boost circuit 42 and continuing to supply power to the power control circuit 45 itself.

[0062] After the discharge process is completed, the power control circuit 45 stops supplying power to itself (step 106). Specifically, when the discharge progresses to the point where the voltage of the auxiliary power supply 41 reaches the stop voltage Vst, the power control circuit 45 controls the first switching element 51 to be in the open state, and simultaneously stops the operation of the boost circuit 42. Thus, power is no longer supplied to the power control circuit 45, and the power control circuit 45 stops.

[0063] When the external power supply voltage Vex of the external power supply 13 during standby processing is above the drop threshold Vthlo (step 103a: Yes), and the start switch 31 is not operated to the off state (step 103b: No), repeat the processing of steps 103a and 103b.

[0064] Here, we assume, for example, that regenerative power is generated in the steering-side motor 12. When regenerative power is generated during charging and standby processing, since the drive relay 47 is in the ON state, the regenerative power generated by the steering device 2 is absorbed by the external power supply 13. Therefore, the output voltage Vout does not rise, and the regeneration switching element 73 does not switch to the ON state. That is, the regeneration absorption circuit 46 does not operate. On the other hand, when regenerative power is generated during backup processing, since the drive relay 47 is in the OFF state, the regenerative power is not absorbed by the external power supply 13. Furthermore, since the switching element inside the boost circuit 42 repeatedly turns on and off, the regenerative power is not absorbed by the auxiliary power supply 41. Therefore, the output voltage Vout rises, the regeneration switching element 73 switches to the ON state, and the regenerative power is absorbed by the regeneration absorption circuit 46.

[0065] Next, refer to Figure 4 The change in output voltage Vout when regenerated power is generated during backup processing is explained. Figure 4This is an example of how the output voltage Vout of the steering-side motor 12 and the on / off state of the regeneration switching element 73 change over time when the motor generates regenerative power at time t1.

[0066] like Figure 4 As shown in (a), at time points before t1, the output voltage Vout is equal to the boost voltage Vsu output from boost circuit 42. Since the boost voltage Vsu is less than the turn-on voltage Von, therefore... Figure 4 As shown in (b), the regeneration switching element 73 is in the off state. Figure 4 As shown in (a), when the steering-side motor 12 generates regenerative power at time t1, the output voltage Vout rises. Then, at time t2, when the output voltage Vout reaches the turn-on voltage Von, as... Figure 4 As shown in (b), the regeneration switching element 73 is switched to the ON state. Thus, while the output voltage Vout is maintained near the Zener voltage Vze, current flows to ground via the Zener diode 71. That is, the regeneration power generated by the steering-side motor 12 is absorbed by the regeneration absorption circuit 46. Afterwards, as... Figure 4 As shown in (a), the regenerative power generated by the steering-side motor 12 is gradually absorbed. When the output voltage Vout is lower than the cutoff voltage Voff at time t3, as... Figure 4 As shown in (b), the regeneration switching element 73 is switched to the off state.

[0067] Here, the regenerative absorption circuit 46 may sometimes experience the following malfunctions. One malfunction of the regenerative absorption circuit 46 is a malfunction of the Zener diode 71. When the Zener diode 71 malfunctions, for example, no current flows even if the reverse voltage applied to the Zener diode 71 exceeds the Zener voltage Vze, or current flows even if the reverse voltage is lower than the Zener voltage Vze. Another malfunction of the regenerative absorption circuit 46 is a malfunction in the path of absorbing regenerated power, such as a break in the absorption line Lab. Other malfunctions of the regenerative absorption circuit 46 are malfunctions in at least one of the regeneration switching element 73 and the absorption operation switching circuit 74, causing the regeneration switching element 73 to switch to the on state even though the output voltage Vout is lower than the turn-on voltage Von.

[0068] When the regenerative absorption circuit 46 malfunctions, it cannot absorb regenerative power generated during backup processing, and the output voltage Vout may significantly exceed the Zener voltage Vze. As a result, components of the vehicle power supply unit 1, such as the boost control circuit, may malfunction. In view of this, the vehicle power supply unit 1 of this embodiment includes a structure for detecting malfunctions in the regenerative absorption circuit 46.

[0069] In detail, such as Figure 2As shown, the vehicle power supply unit 1 includes a high-voltage generating diode 81 disposed on the absorption line Lab, and a branch line Lbr branching from the discharge line Lsu. The vehicle power supply unit 1 also includes a resistor 82 disposed on the branch line Lbr and a fifth switching element 83.

[0070] A high-voltage generating diode 81 is positioned between the fuse 72 and the Zener diode 71 in the absorption line Lab. The high-voltage generating diode 81 allows current to flow from the upstream side to the downstream side and restricts current flow from the downstream side to the upstream side. That is, the high-voltage generating diode 81 allows current to flow from the internal drive power line Lpi to the Zener diode 71, while restricting the current flowing from the Zener diode 71 to the internal drive power line Lpi.

[0071] Branch line Lbr extends from the connection point P4 between the boost circuit 42 and the second switching element 52 in the discharge line Lsu, and connects to the connection point P5 between the high-voltage generating diode 81 and the Zener diode 71 in the absorption line Lab. A resistor 82 and a fifth switching element 83 are sequentially arranged on branch line Lbr from connection point P4 toward connection point P5.

[0072] The fifth switching element 83 is a semiconductor switch such as a FET or IGBT. The on / off state of the fifth switching element 83 is controlled by the power control circuit 45. Furthermore, for ease of explanation, the cable connecting the signal output from the power control circuit 45 to the fifth switching element 83 is not shown. The fifth switching element 83 is controlled to be turned on only when an abnormality is detected in the regenerative absorption circuit 46, and otherwise controlled to be turned off. Therefore, the structure used to detect abnormalities in the regenerative absorption circuit 46 does not affect the execution of charging, standby, backup, and discharging processes.

[0073] Furthermore, the branch line Lbr is equipped with a voltage sensor 84 that detects a determination voltage Vde between the resistor 82 in the branch line Lbr and the fifth switching element 83. The determination voltage Vde detected by the voltage sensor 84 is output to the power control circuit 45, which serves as an abnormality detection circuit.

[0074] The power control circuit 45 performs an anomaly determination on the regenerative absorption circuit 46 based on the input determination voltage Vde. As described above, one of the anomaly determinations performed by the power control circuit 45 in the initial check process of this embodiment is the anomaly determination on the regenerative absorption circuit 46. The power control circuit 45 performs the three anomaly determinations described above: an anomaly in the Zener diode 71, an anomaly in the path for absorbing regenerative power, and an anomaly in the operation of the regenerative switching element 73. The power control circuit 45 performs the determinations, for example, in the order of anomaly in the path for absorbing regenerative power, an anomaly in the operation of the regenerative switching element 73, and an anomaly in the Zener diode 71, but the order of anomaly determination can be appropriately changed.

[0075] In detail, when the power control circuit 45 determines that the Zener diode 71 is malfunctioning, it controls the second switching element 52 to be in the off state and the fifth switching element 83 to be in the on state, and controls the boost circuit 42 to output a voltage higher than the Zener voltage Vze. At this time, the power control circuit 45 of this embodiment controls the drive relay 47 to be in the on state, and simultaneously changes the on-state voltage Von of the absorption action switching circuit 74 from its initial value to a value lower than the external power supply voltage Vex. As a result, the output voltage Vout reaches above the on-state voltage Von, and therefore the regeneration switching element 73 is controlled to be in the on state by the absorption action switching circuit 74. In this state, the power control circuit 45 determines that the Zener diode 71 is malfunctioning based on whether the determination voltage Vde is outside a predetermined voltage range including the Zener voltage Vze. The predetermined voltage range is the voltage range within which the normal maintenance voltage of the Zener diode 71 can be determined when current flows through the Zener diode 71, and it is preset. When the determination voltage Vde is outside the predetermined voltage range, the power control circuit 45 determines that the Zener diode 71 has malfunctioned.

[0076] When the power control circuit 45 determines an anomaly in the path for absorbing regenerated power, it controls the drive relay 47 and the fifth switching element 83 to be in the on state, controls the second switching element 52 (which serves as a backup relay) to be in the off state, and controls the boost circuit 42 to stop. In this state, the power control circuit 45 determines the anomaly in the path for absorbing regenerated power based on whether the determination voltage Vde is less than the open anomaly determination threshold Vthop. In this state, for example, if no anomaly such as a broken wire occurs in the absorption line Lab, a voltage based on the external power supply voltage Vex will be generated on the branch line Lbr. The open anomaly determination threshold Vthop is, for example, a value that can be considered as the determination voltage Vde being zero, but is set to a value slightly greater than zero to account for the influence of noise, etc. When the determination voltage Vde is less than the open anomaly determination threshold Vthop, the power control circuit 45 determines that an anomaly has occurred in the path for absorbing regenerated power.

[0077] When the power control circuit 45 determines that the regeneration switching element 73 is malfunctioning, it controls the second switching element 52 to be in the off state and the regeneration switching element 73 to be in the off state, and controls the boost circuit 42 to output a voltage higher than the Zener voltage Vze. In this state, the power control circuit 45 determines whether at least one of the regeneration switching element 73 and the absorption operation switching circuit 74 has malfunctioned based on whether the voltage Vde is less than the conduction malfunction determination threshold Vthco. Specifically, when the regeneration switching element 73 is normally in the off state, no path is formed from the boost circuit 42 through the branch line Lbr, the Zener diode 71, and the regeneration switching element 73 to ground, so the voltage Vde is determined to be near 0V. On the other hand, when the regeneration switching element 73 cannot switch to the off state and abnormally remains in the on state, a path is formed from the boost circuit 42 through the branch line Lbr, the Zener diode 71, and the regeneration switching element 73 to ground. In this case, current flows through the Zener diode 71, so the voltage is maintained at a value near the Zener voltage Vze while the current flows. Based on this, the conduction failure determination threshold Vthco is, for example, preset to a value near the upper limit of the aforementioned predetermined voltage range. When the determination voltage Vde is less than the conduction failure determination threshold Vthco, the power control circuit 45 determines that at least one of the regeneration switching element 73 and the absorption operation switching circuit 74 has malfunctioned.

[0078] Next, the function and effects of this implementation method will be explained.

[0079] (1) The vehicle power supply device 1 includes: a high voltage generating diode 81, which is disposed upstream of the Zener diode 71 in the absorption line Lab; and a branch line Lbr, which branches out from the connection point P4 of the discharge line Lsu and connects to the connection point P5 of the absorption line Lab.

[0080] According to the above structure, when the second switching element 52 is switched to the off state, a reverse voltage exceeding the Zener voltage Vze can be applied to the Zener diode 71 through the boost circuit 42. Therefore, an abnormality in the Zener diode 71 can be determined.

[0081] (2) When the second switching element 52 is switched to the off state, the regeneration switching element 73 is controlled to the on state, and the boost circuit 42 is controlled to output a voltage higher than the Zener voltage Vze, the power control circuit 45 determines that the Zener diode 71 has malfunctioned when the determination voltage Vde is outside the predetermined voltage range. Thus, the malfunction of the regeneration absorption circuit 46 can be appropriately determined.

[0082] (3) When the power control circuit 45 is in a state where the drive relay 47 is switched to the on state, the second switching element 52 is switched to the off state, and the boost circuit 42 is controlled to stop, if the determination voltage Vde is less than the open abnormality determination threshold Vthop, it determines that an abnormality has occurred on the path of absorbing regenerated power. Thus, the abnormality of the regenerated absorption circuit 46 can be appropriately determined.

[0083] (4) The regeneration absorption circuit 46 includes: a regeneration switching element 73 disposed downstream of the Zener diode 71 in the absorption line Lab; and an absorption action switching circuit 74 configured to control the on / off state of the regeneration switching element 73 based on the output voltage Vout.

[0084] Depending on the vehicle's condition, the external power supply voltage Vex may temporarily increase. In such a case, if the Zener diode 71 experiences an abnormal decrease in Zener voltage Vze, the internal drive power line Lpi will experience a ground fault via the absorption line Lab. As a result, the power from the external power supply 13 may not be properly supplied to the steering device 2. In this regard, in the above structure, as long as the output voltage Vout does not rise to a high voltage that would adversely affect the boost control circuit and the like due to the generation of regenerative power, the regeneration switching element 73 remains in the open state. Thus, the occurrence of ground faults in the internal drive power line Lpi can be suppressed, and power can be stably supplied from the external power supply 13 to the steering device 2.

[0085] Furthermore, the fault determination of the Zener diode 71 is performed when the regeneration switching element 73 is controlled to be in the on state. Therefore, even if the regeneration switching element 73 is provided, the fault determination of the Zener diode 71 can be performed appropriately.

[0086] (5) When the second switching element 52 is switched to the off state and the regeneration switching element 73 is switched to the off state, and the boost circuit 42 is controlled to output a voltage higher than the Zener voltage Vze, the power control circuit 45 determines that at least one of the regeneration switching element 73 and the absorption operation switching circuit 74 has malfunctioned when the determination voltage Vde is less than the conduction fault determination threshold Vthco. Thus, the malfunction of the regeneration absorption circuit 46 can be appropriately determined.

[0087] (6) The vehicle power supply unit 1 is equipped with a fuse 72 installed on the absorption line Lab.

[0088] For example, if a short-circuit fault occurs in the regeneration switching element 73 and the Zener diode 71 experiences an abnormal decrease in its Zener voltage Vze, and the external power supply voltage Vex temporarily increases, the internal drive power line Lpi may experience a ground fault via the snubber line Lab. In the above structure, under such circumstances, the fuse 72 blows due to the large current flowing through the snubber line Lab. Therefore, the occurrence of a ground fault in the internal drive power line Lpi can be suppressed, and power can be stably supplied from the external power supply 13 to the steering device 2.

[0089] This embodiment can be implemented with the following modifications. This embodiment and the following variations can be combined and implemented within the scope of technical inconsistency.

[0090] In the above embodiment, the fuse 72 is disposed upstream of the high-voltage generating diode 81 in the absorption line Lab, but it is not limited thereto; for example, it may also be disposed downstream of the high-voltage generating diode 81. Alternatively, the fuse 72 may not be disposed in the absorption line Lab.

[0091] In the above embodiment, the power control circuit 45 may also acquire the output voltage Vout and control the on / off state of the regeneration switching element 73 based on the acquired output voltage Vout. In this case, the regeneration absorption circuit 46 may not include the absorption operation switching circuit 74.

[0092] In the above embodiments, the regeneration absorption circuit 46 may also be without the regeneration switching element 73 and the absorption action switching circuit 74.

[0093] In the above embodiment, the power control circuit 45 is configured to perform three types of fault determination: fault of Zener diode 71, fault of the path for absorbing regenerated power, and fault of operation of regeneration switching element 73. However, it is not limited to this; the power control circuit 45 may perform at least one of these three fault determinations.

[0094] In the above embodiment, the absorption line Lab extends from a connection point in the internal drive power line Lpi that is further downstream than the connection point P1, but it is not limited thereto. For example, it may also extend from the portion between the drive relay 47 and the connection point P1 in the internal drive power line Lpi. Furthermore, the absorption line Lab may also extend from the connection point P1 and the second switching element 52 in the discharge line Lsu, or it may extend from the connection point P1 and the third switching element 53 in the charging line Lsd.

[0095] In the above embodiments, the power control circuit 45 can also perform the abnormality determination of the regeneration absorption circuit 46 at any time other than the execution of the initial check process.

[0096] In the above embodiments, an abnormality detection circuit that performs the abnormality determination of the regenerative absorption circuit 46 may also be provided separately from the power control circuit 45 in the vehicle power supply device 1, and the power control circuit 45 may not perform the abnormality determination of the regenerative absorption circuit 46.

[0097] In the above embodiments, the vehicle power supply device 1 may also be without the charging cable Lsd, the step-down circuit 43, the third switching element 53 and the fourth switching element 54.

[0098] In the above embodiments, the steering device 2 may also be an electric power steering device that applies the torque of the motor to the steering shaft or rack shaft.

[0099] In the above embodiment, the vehicle power supply device 1 supplies power to the steering device 2, but is not limited thereto; for example, it may also supply power to a motor used as a driving source for driving.

Claims

1. A power supply device for a vehicle, configured to supply power to a power source, wherein, It includes: a power cord, which forms part of the power supply path for supplying power from an external power source to the object being powered; a drive relay, which is disposed on the power cord; and a discharge line, which branches off from a connection point in the power cord that is further downstream than the drive relay. An auxiliary power supply, which is connected to the power supply line via the discharge line; A boost circuit, which is disposed on the discharge line, is configured to boost the voltage of the auxiliary power supply and output it; A backup relay is provided on the output side of the boost circuit in the discharge line; And a regenerative absorption circuit configured to absorb regenerative power generated in the power supply object, the regenerative absorption circuit including: an absorption line that connects a portion of the power line downstream of the drive relay to ground; The vehicle power supply device also includes: a high-voltage generating diode disposed on the absorption line, configured to allow current to flow from the power line to ground when the reverse voltage applied to the Zener diode is above the Zener voltage; and a high-voltage generating diode disposed on the absorption line upstream of the Zener diode, configured to allow current to flow from the power line to the Zener diode and limit current to flow from the Zener diode to the power line; and a branch line extending from the connection point between the boost circuit and the backup relay in the discharge line, and connecting to the connection point between the high-voltage generating diode and the Zener diode in the absorption line.

2. The vehicle power supply device according to claim 1, wherein, It also includes: a voltage sensor that detects a voltage used for determining the voltage on the branch line; and an anomaly detection circuit configured to perform one or more anomaly determinations to detect an anomaly in the regenerative absorption circuit, wherein the anomaly detection circuit is further configured to determine that the Zener diode has malfunctioned when the voltage used for determining the anomaly is outside a predetermined voltage range including the Zener voltage, provided that the backup relay is controlled to switch to an off state and the boost circuit is controlled to output a voltage higher than the Zener voltage.

3. The vehicle power supply device according to claim 2, wherein, The anomaly detection circuit is further configured such that, when the driving relay is controlled to switch to the on state, the backup relay is controlled to switch to the off state, and the boost circuit is controlled to stop, if the determination voltage is less than the open anomaly determination threshold, an anomaly is determined to have occurred on the path absorbing the regenerated power.

4. The vehicle power supply device according to claim 2 or 3, wherein, The regenerative absorption circuit further includes: a regeneration switching element disposed downstream of the Zener diode in the absorption line; and an absorption action switching circuit configured to control the on / off state of the regeneration switching element based on the output voltage output from the power line to the power supply object.

5. The vehicle power supply device according to claim 4, wherein, The anomaly detection circuit is further configured such that, when the backup relay is controlled to switch to the off state, the regeneration switching element is controlled to switch to the off state, and the boost circuit is controlled to output a voltage higher than the Zener voltage, if the determination voltage is less than the conduction anomaly determination threshold, it is determined that at least one of the regeneration switching element and the absorption action switching circuit has an anomaly.

6. The vehicle power supply device according to any one of claims 1 to 3, wherein, It also includes a fuse located on the absorption line.

7. A method for detecting an anomaly in a vehicle power supply device, the vehicle power supply device being configured to supply power to a power source, the vehicle power supply device comprising: a power line, which constitutes part of a power supply path for supplying power from an external power source to the power source; a drive relay disposed on the power line; and a discharge line extending from a connection point in the power line that is downstream of the drive relay. An auxiliary power supply, which is connected to the power supply line via the discharge line; A boost circuit, which is disposed on the discharge line, is configured to boost the voltage of the auxiliary power supply and output it; A backup relay is provided on the output side of the boost circuit in the discharge line; The vehicle power supply device also includes a regenerative absorption circuit configured to absorb regenerative power generated in the powered object. The regenerative absorption circuit includes: an absorption line connecting a portion of the power line downstream of the drive relay to ground; and a Zener diode disposed on the absorption line, configured to allow current to flow from the power line to ground when the reverse voltage applied to the Zener diode is above the Zener voltage. The vehicle power supply device further includes: a high-voltage generating diode disposed on the absorption line upstream of the Zener diode, configured to allow current to flow from the power line to the Zener diode and limit current from the drive relay to ground. The current flowing from the Zener diode to the power line; and a branch line extending from the connection point between the boost circuit and the backup relay in the discharge line, connecting to the connection point between the high-voltage generating diode and the Zener diode in the absorption line, the anomaly detection method comprising: detecting a determination voltage as the voltage on the branch line; and, when the determination voltage is outside a predetermined voltage range including the Zener voltage, and the backup relay is switched to an off state and the boost circuit is controlled to output a voltage higher than the Zener voltage, determining that the Zener diode has malfunctioned.

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