In-vehicle cutting device

Abstract

A vehicle-mounted shutoff device (10) is provided with: a first shutoff unit (21) provided between a first power supply unit (for example, a voltage conversion unit (93)) and a conductive path (for example, a first conductive path (81)); and a control unit (30) for controlling the first shutoff unit (21). When the vehicle is in a first state, the control unit (30) switches the first cutoff unit (21) to a first cutoff state on the basis of the flow of a current exceeding a first threshold (TH1) from the second power supply unit side to the first power supply unit side, and when the vehicle is in a second state, switches the first cutoff unit (21) to a second cutoff state on the basis of the flow of a current exceeding the first threshold (TH1) from the second power supply unit side to the first power supply unit side. The first cut-off unit (21) is switched to a first cut-off state on the basis that a current exceeding a second threshold value (TH2) larger than the first threshold value (TH1) flows from the second power supply unit side to the first power supply unit side.

Description

Technical Field

[0001] This disclosure relates to a vehicle-mounted cutting device. Background Technology

[0002] Patent Document 1 discloses a power supply system that prevents current from flowing from a secondary power source to the primary power source in the event of a power outage from the primary power source. This power supply system determines the power outage from the primary power source, for example, based on the current flowing towards the primary power source.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-182318 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] In the structure of Patent Document 1, when it is desired to supply power from the secondary power source to the primary power source, it is also determined that the power supply from the primary power source is interrupted, and the power supply to the primary power source may be cut off. Therefore, when power is supplied from the secondary power source to the primary power source, it is considered to stop the cut-off function and allow the power supply to the primary power source. However, when the cut-off function is stopped, a problem arises where the cut-off cannot be interrupted even if an overcurrent flows.

[0008] The purpose of this disclosure is to provide a technique for easily and appropriately interrupting current.

[0009] Methods for solving problems

[0010] The vehicle-mounted disconnect device disclosed herein is included in a vehicle-mounted system, the vehicle-mounted system comprising a first power supply unit, a second power supply unit, a conductive circuit, and a load, wherein the conductive circuit is disposed between the first power supply unit and the second power supply unit, and the load is electrically connected to the conductive circuit. The vehicle-mounted cutting device includes: A first cutting-off portion is disposed between the first power supply portion and the conductive path; and The control unit controls the first cutting unit. The first cut-off section switches between a first allowable state and a first cut-off state. In the first allowable state, current flows from the second power supply side to the first power supply side, and in the first cut-off state, current flow from the second power supply side to the first power supply side is cut off. The control unit performs a cut-off control. When the vehicle is in a first state, the cut-off control switches the first cut-off unit to the first cut-off state based on the current flowing from the second power supply side to the first power supply side exceeding a first threshold. When the vehicle is in a second state, the first cut-off unit switches to the first cut-off state based on the current flowing from the second power supply side to the first power supply side exceeding a second threshold greater than the first threshold.

[0011] Invention Effects

[0012] The technology disclosed herein can easily and appropriately cut off the current. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of a vehicle-mounted system including the vehicle-mounted cutting device of the first embodiment.

[0014] Figure 2 This is an explanatory diagram showing the operation of the vehicle system during precharging according to the first embodiment.

[0015] Figure 3 This is an explanatory diagram showing the operation of the vehicle system during driving according to the first embodiment.

[0016] Figure 4 It means in Figure 2 The diagram illustrates the state in which a ground fault occurs in the second conductive path.

[0017] Figure 5 This indicates that the first cutting part is from Figure 4 The diagram shows the state transitioning to the first cut-off state.

[0018] Figure 6 It means in Figure 3 The diagram illustrates the state in which a ground fault occurs in the second conductive path.

[0019] Figure 7 This indicates that the first cutting part is from Figure 6 The diagram shows the state transitioning to the first cut-off state.

[0020] Figure 8 This is a schematic diagram of the structure of a vehicle-mounted system including the vehicle-mounted cutting device of the second embodiment.

[0021] Figure 9 This is an explanatory diagram showing the operation of the vehicle system during pre-charging according to the second embodiment.

[0022] Figure 10 This is an explanatory diagram showing the operation of the vehicle system during driving according to the second embodiment.

[0023] Figure 11 It means in Figure 9 The diagram illustrates the state in which a ground fault occurs in the second conductive path.

[0024] Figure 12 This indicates that the first cutting part is from Figure 11 The diagram shows the state transitioning to the first cut-off state.

[0025] Figure 13 It means in Figure 10 The diagram illustrates the state in which a ground fault occurs in the second conductive path.

[0026] Figure 14 This indicates that the first cutting part is from Figure 13 The diagram shows the state transitioning to the first cut-off state. Detailed Implementation

[0027] [Description of embodiments of this disclosure]

[0028] The following are examples and illustrations of embodiments of this disclosure.

[0029] [1] A vehicle-mounted disconnecting device, included in a vehicle system, the vehicle system comprising a first power supply unit, a second power supply unit, a conductive circuit, and a load, wherein the conductive circuit is disposed between the first power supply unit and the second power supply unit, and the load is electrically connected to the conductive circuit, wherein... The vehicle-mounted cutting device includes: A first cutting-off portion is disposed between the first power supply portion and the conductive path; and The control unit controls the first cutting unit. The first cut-off section switches between a first allowable state and a first cut-off state. In the first allowable state, current flows from the second power supply side to the first power supply side, and in the first cut-off state, current flow from the second power supply side to the first power supply side is cut off. The control unit performs a cut-off control. When the vehicle is in a first state, the cut-off control switches the first cut-off unit to the first cut-off state based on the current flowing from the second power supply side to the first power supply side exceeding a first threshold. When the vehicle is in a second state, the first cut-off unit switches to the first cut-off state based on the current flowing from the second power supply side to the first power supply side exceeding a second threshold greater than the first threshold.

[0030] When the vehicle is in a first state, the aforementioned vehicle-mounted disconnect device switches the first disconnect section to a first disconnect state based on a current flowing from the second power supply side to the first power supply side exceeding a first threshold. Furthermore, when the vehicle is in a second state, the same device switches the first disconnect section to the first disconnect state based on a current flowing from the second power supply side to the first power supply side exceeding a second threshold greater than the first threshold. In other words, the aforementioned vehicle-mounted disconnect device can change the threshold for switching the first disconnect section to the first disconnect state according to the vehicle's state, thus enabling appropriate current disconnection based on the vehicle's condition.

[0031] [2] According to the vehicle-mounted cutting device described in [1], wherein, The vehicle-mounted cutting device has a second cutting section, which is disposed between the second power supply section and the conductive circuit. The second cutting-off section is controlled by the control section, and switches between a second permitted state and a second cutting-off state. In the second permitted state, current is allowed to flow from the first power supply side to the second power supply side, and in the second cutting-off state, the flow of current from the first power supply side to the second power supply side is cut off. The control unit performs the cutting control when the first cutting unit is in the first permitted state and the second cutting unit is in the second permitted state.

[0032] The aforementioned vehicle-mounted disconnect device performs the disconnection control when the first disconnection section is in the first permitted state and the second disconnection section is in the second permitted state. Therefore, even when the first disconnection section switches to the first disconnection state, the aforementioned vehicle-mounted disconnect device can supply power to the load from the second power supply section without interrupting the power supply to the load.

[0033] [3] The vehicle-mounted cutting device according to [1] or [2], wherein, The vehicle-mounted disconnect device includes a current detection unit that detects the current flowing from the second power supply side to the first power supply side. The control unit includes a first disconnect circuit. When the current detection value of the first cutting-off circuit exceeds the first threshold in the first state, the first cutting-off circuit switches the first cutting-off section to the first cutting-off state. When the current detection value of the first cutting-off circuit exceeds the second threshold in the second state, the first cutting-off section switches the first cutting-off section to the first cutting-off state.

[0034] In the first state, when the current flowing from the second power supply side to the first power supply side exceeds a first threshold, the aforementioned vehicle-mounted disconnect device can quickly switch the first disconnect section to the first disconnect state via the first disconnect circuit. Furthermore, in the second state, when the current flowing from the second power supply side to the first power supply side exceeds a second threshold, the aforementioned vehicle-mounted disconnect device can also quickly switch the first disconnect section to the first disconnect state via the first disconnect circuit.

[0035] [4] According to the vehicle-mounted cutting device described in [3], wherein, The first cut-off circuit includes a first comparator and a second comparator. If the current detection value of the first comparator exceeds the first threshold in the first state, the first comparator outputs a first cut-off signal. If the current detection value of the second comparator exceeds the second threshold in the second state, the second comparator outputs a second cut-off signal. The first cutting unit switches to the first cutting state when the first cutting signal is output from the first comparator, and also switches to the first cutting state when the second cutting signal is output from the second comparator. The first comparator is disconnected in the second state.

[0036] Based on this structure, the structure of the first cut-off circuit can be easily simplified.

[0037] [5] According to the vehicle-mounted cutting device described in [3], wherein, The control unit includes a circuit control unit. The first cut-off circuit includes a comparator. The comparator outputs a cut-off signal when the detected value of the current detection unit exceeds the input value input from the circuit control unit. The circuit control unit inputs the first threshold to the comparator in the first state, and inputs the second threshold to the comparator in the second state. The first cutting section switches to the first cutting state when the cutting signal is output from the comparator.

[0038] The aforementioned vehicle-mounted cut-off device can output a cut-off signal corresponding to the vehicle's state through a comparator.

[0039] [6] The vehicle-mounted cutting device according to any one of [1] to [5], wherein, The first state is the state in which power is supplied from the first power source to the conductive path side. The second state is the state of supplying power from the second power source to the first power source.

[0040] The aforementioned vehicle-mounted disconnect device can immediately switch the first disconnect section to a first disconnect state when a reverse current is generated in the case of a power supply circuit being supplied with power from the first power supply unit. Furthermore, the aforementioned vehicle-mounted disconnect device can switch the first disconnect section to a first disconnect state when an overcurrent is generated in the case of a power supply circuit being supplied with power from the second power supply unit to the first power supply unit.

[0041] [7] According to the vehicle-mounted cutting device described in [6], wherein, The on-board system includes a high-voltage battery, a main system relay, and a capacitor. The second power supply unit is a low-voltage battery. The first power supply unit is a voltage conversion unit disposed between the high-voltage battery and the low-voltage battery. The voltage conversion unit performs a first conversion operation and a second conversion operation. The first conversion operation boosts or bucks the voltage input from the high-voltage battery side and outputs it to the low-voltage battery side. The second conversion operation boosts or bucks the voltage input from the low-voltage battery side and outputs it to the high-voltage battery side. The system's main relay is located between the high-voltage battery and the voltage conversion unit. The capacitor is electrically connected in the electrical path between the system's main relay and the voltage conversion unit. In the vehicle system, when the vehicle's start switch is turned on, the voltage conversion unit performs the second conversion operation to precharge the capacitor while keeping the system's main relay off. After precharging the capacitor, the system's main relay is turned on. The first state is when the start switch is on and the system main relay is on. The second state is when the start switch is on and the system main relay is off.

[0042] The aforementioned vehicle-mounted disconnect device can immediately switch the first disconnect section to the first disconnect state when a reverse current is generated to the first power supply unit during vehicle operation. Furthermore, the aforementioned vehicle-mounted disconnect device can switch the first disconnect section to the first disconnect state when an overcurrent is generated during the pre-charging of the capacitor.

[0043] [8] The vehicle-mounted cutting device according to any one of [1] to [7], wherein after the control unit switches the first cutting section to the first cutting state, it restores the first cutting section to the first permitted state if the first restoration condition is met.

[0044] Even when the first cutting section is switched to the first cutting state, the above-mentioned vehicle-mounted cutting device can restore the first cutting section to the first permitted state if the first restoration condition is met.

[0045] [Details of the embodiments disclosed herein]

[0046] 1. First Implementation Method

[0047] 1-1. Overview of the vehicle-mounted system 100

[0048] exist Figure 1 The diagram shows an on-board system 100 including an on-board disconnect device 10. The on-board system 100 is a system mounted on a vehicle. The on-board system 100 includes a high-voltage battery 91, a low-voltage battery 92, a voltage conversion unit 93, a system main relay 94 (hereinafter also referred to as SMR 94), a capacitor 95, a load 96, a first conductive path 81, a second conductive path 82, and a third conductive path 83.

[0049] The output voltage of the high-voltage battery 91 is higher than that of the low-voltage battery 92. The high-voltage battery 91 is, for example, composed of a lithium-ion battery or a sodium-ion battery. The low-voltage battery 92 is, for example, composed of a lithium-ion battery or a lead-acid battery. The low-voltage battery 92 is an example of a second power supply unit.

[0050] The voltage conversion unit 93 is an example of the first power supply unit. The voltage conversion unit 93 is disposed between the high-voltage battery 91 and the low-voltage battery 92. The voltage conversion unit 93 performs a first conversion operation, boosting or bucking the voltage input from the high-voltage battery 91 side and outputting it to the low-voltage battery 92 side. Additionally, the voltage conversion unit 93 performs a second conversion operation, boosting or bucking the voltage input from the low-voltage battery 92 side and outputting it to the high-voltage battery 91 side. The voltage conversion unit 93 is, for example, configured as a DC-DC converter.

[0051] SMR94 is disposed between the high-voltage battery 91 and the voltage conversion unit 93.

[0052] Capacitor 95 is electrically connected to the electrical path between SMR94 and voltage conversion unit 93.

[0053] The first conductive path 81 is an example of a conductive path. The first conductive path 81 is disposed between the voltage conversion unit 93 and the low-voltage battery 92. A load 96 is electrically connected to the first conductive path 81. The second conductive path 82 is disposed between the voltage conversion unit 93 and the first conductive path 81. The third conductive path 83 is disposed between the low-voltage battery 92 and the first conductive path 81.

[0054] When the vehicle's start switch is turned on, the vehicle system 100, while keeping the SMR 94 off, causes the voltage conversion unit 93 to perform a second conversion operation to precharge the capacitor 95. Then, after precharging the capacitor 95, the vehicle system 100 switches the SMR 94 on. The start switch is the ignition switch for a motor-driven vehicle and the power switch for an electric vehicle.

[0055] 1-2. Structure of the vehicle-mounted cutting device 10

[0056] The vehicle-mounted disconnect device 10 is, for example, a junction box. The vehicle-mounted disconnect device 10 is electrically connected to the voltage conversion unit 93, the low-voltage battery 92, and the load 96.

[0057] The vehicle-mounted cutting device 10 includes a first cutting section 21, a second cutting section 22, a current detection section 23, and a control section 30.

[0058] A first cut-off section 21 is disposed between the first conductive path 81 and the second conductive path 82. The first cut-off section 21 is also disposed between the voltage conversion section 93 and the first conductive path 81. One end of the first cut-off section 21 is electrically connected to the first conductive path 81. The other end of the first cut-off section 21 is electrically connected to the voltage conversion section 93 via the second conductive path 82. The first cut-off section 21 switches between a first permitted state and a first cut-off state. The first permitted state allows bidirectional current flow through the first cut-off section 21 itself, while the first cut-off state cuts off current flow from the first conductive path 81 side to the voltage conversion section 93 side. In this embodiment, in the first cut-off state, the first cut-off section 21 allows current flow from the voltage conversion section 93 side to the first conductive path 81 side. The first cut-off section 21 includes a MOSFET 21A. The first cut-off section 21 is in the first permitted state when the MOSFET 21A is turned on. The first cut-off section 21 is in the first cut-off state when the MOSFET 21A is turned off. In this embodiment, the first cut-off section 21 is composed of a normally closed switching element.

[0059] The second cut-off section 22 is disposed between the first conductive path 81 and the third conductive path 83. The second cut-off section 22 is disposed between the low-voltage battery 92 and the first conductive path 81. One end of the second cut-off section 22 is electrically connected to the first conductive path 81. One end of the second cut-off section 22 is electrically connected to one end of the first cut-off section 21 via the first conductive path 81. The other end of the second cut-off section 22 is electrically connected to the low-voltage battery 92 via the third conductive path 83. The second cut-off section 22 switches between a second permitted state and a second cut-off state. The second permitted state allows bidirectional current flow through the second cut-off section 22 itself, while the second cut-off state cuts off current flow from the first conductive path 81 side to the low-voltage battery 92 side. In this embodiment, in the second cut-off state, the second cut-off section 22 allows current flow from the low-voltage battery 92 side to the first conductive path 81 side. The second cut-off section 22 includes a MOSFET 22A. The second cut-off section 22 is in the second permitted state when the MOSFET 22A is turned on. The second cut-off section 22 is in the second cut-off state when the MOSFET 22A is turned off. In this embodiment, the second cut-off section 22 is composed of a normally closed switching element.

[0060] The current detection unit 23 detects the current flowing from the first conductive path 81 side to the voltage conversion unit 93 side, and also detects the current flowing from the voltage conversion unit 93 side to the first conductive path 81 side. The current detection unit 23 is, for example, constructed using a known current sensor. The current detection unit 23 outputs a detected value within a specified range (e.g., 0~5V). For example, the current detection unit 23 outputs a reference voltage (e.g., 2.5V) when there is no current flow, outputs a voltage higher than the reference voltage when current flows from the first conductive path 81 side to the voltage conversion unit 93 side, and outputs a voltage lower than the reference voltage when current flows from the voltage conversion unit 93 side to the first conductive path 81 side. For example, the larger the current flowing from the first conductive path 81 side to the voltage conversion unit 93 side, the larger the voltage output; and the larger the current flowing from the voltage conversion unit 93 side to the first conductive path 81 side, the smaller the voltage output.

[0061] The control unit 30 controls the first cut-off unit 21 and the second cut-off unit 22. The control unit 30 performs cut-off control. The cut-off control is as follows: when the vehicle is in a first state, based on a current exceeding a first threshold TH1 flowing from the low-voltage battery 92 side to the voltage conversion unit 93 side, the first cut-off unit 21 is switched to a first cut-off state; when the vehicle is in a second state, based on a current exceeding a second threshold TH2 flowing from the low-voltage battery 92 side to the voltage conversion unit 93 side, the first cut-off unit 21 is switched to a first cut-off state. The second threshold TH2 is a value greater than the first threshold TH1.

[0062] When the vehicle is in the first state, the control unit 30 can immediately switch the first cut-off unit 21 to the first cut-off state when the current exceeding the first threshold TH1 flows from the low-voltage battery 92 side to the voltage conversion unit 93 side, or switch the first cut-off unit 21 to the first cut-off state when the current exceeding the first threshold TH1 flows for a predetermined time, or switch the first cut-off unit 21 to the first cut-off state when the average value during the predetermined period exceeds the first threshold TH1.

[0063] When the vehicle is in the second state, the control unit 30 can immediately switch the first cut-off unit 21 to the first cut-off state when the current exceeding the second threshold TH2 flows from the low-voltage battery 92 side to the voltage conversion unit 93 side, or switch the first cut-off unit 21 to the first cut-off state when the current exceeding the second threshold TH2 flows for a predetermined time, or switch the first cut-off unit 21 to the first cut-off state when the average value during the predetermined period exceeds the second threshold TH2.

[0064] The first state is the state in which power is supplied from the voltage conversion unit 93 to the first conductive circuit 81. In this embodiment, the first state is the state in which the start switch is on and the SMR 94 is on. The second state is the state in which power is supplied from the low-voltage battery 92 to the voltage conversion unit 93. In this embodiment, the second state is the state in which the start switch is on and the SMR 94 is off. That is, the vehicle is in the second state when the start switch is switched on, and in the first state when pre-charging is completed.

[0065] The control unit 30 performs the cut-off control when the first cut-off unit 21 is in a first permitted state and the second cut-off unit 22 is in a second permitted state. When both the first cut-off unit 21 and the second cut-off unit 22 are in the first permitted state, power can be supplied to the dual-direction load 96 from the voltage conversion unit 93 and the low-voltage battery 92. When both the first cut-off unit 21 and the second cut-off unit 22 are in the first permitted state, it is preferable to supply power to the load 96 from the voltage conversion unit 93.

[0066] After switching the first cut-off section 21 to the first cut-off state, the control unit 30 maintains the first cut-off section 21 in the first cut-off state even if current does not flow from the first conductive path 81 side to the voltage conversion section 93 side. After switching the first cut-off section 21 to the first cut-off state, the control unit 30 restores the first cut-off section 21 to the first allowed state if the first recovery condition is met. The first recovery condition may be, for example, a condition that is met every second time period shorter than the first time period before the first time period has elapsed. The first recovery condition may also be that the output voltage of the voltage conversion section 93 becomes a first recovery voltage or higher. The first recovery condition may also be that the temperature of the first cut-off section 21 becomes a first recovery temperature or higher.

[0067] When the cut-off condition is met, the control unit 30 switches the second cut-off section 22 to the second cut-off state. The cut-off condition may be, for example, a condition where the voltage at one end or the other end of the second cut-off section 22 falls below a threshold voltage, a condition where current flows from the first conductive path 81 side to the low-voltage battery 92 side, or other conditions. After switching the second cut-off section 22 to the second cut-off state, the control unit 30 maintains the second cut-off section 22 in the second cut-off state even if the cut-off condition is not met. After switching the second cut-off section 22 to the second cut-off state, the control unit 30 restores the second cut-off section 22 to the second permitted state when the second recovery condition is met. The second recovery condition may be, for example, a condition that is met every second time period shorter than the first time period before the first time period has elapsed. The second recovery condition may also be that the output voltage of the low-voltage battery 92 becomes a second recovery voltage or higher. The second recovery condition may also be that the temperature of the second cut-off section 22 becomes a second recovery temperature or higher.

[0068] The control unit 30 includes a first disconnect circuit 31, a second disconnect circuit 32, and a circuit control unit 33. The first disconnect circuit 31 and the second disconnect circuit 32 are composed of discrete components. The circuit control unit 33 includes a microcomputer 33A. The microcomputer 33A controls the first disconnect circuit 31 and the second disconnect circuit 32.

[0069] The first cutting-off circuit 31 switches the first cutting-off section 21 to the first cutting-off state based on the case where current flows from the first conductive path 81 side to the voltage conversion section 93 side when the first cutting-off section 21 is in the first permitted state and the second cutting-off section 22 is in the second permitted state.

[0070] In the first state, if the current detection value of the current detection unit 23 exceeds the first threshold TH1, the first cut-off circuit 31 switches the first cut-off unit 21 to the first cut-off state. In the second state, if the current detection value of the current detection unit 23 exceeds the second threshold TH2, the first cut-off circuit 31 switches the first cut-off unit 21 to the first cut-off state.

[0071] The first cut-off circuit 31 includes a first comparator 31A, a second comparator 31B, a NOR circuit 31C, and a latch circuit 31D.

[0072] The current detection value of the current detection unit 23 and the first threshold TH1 are input to the first comparator 31A. The current detection value of the current detection unit 23 is input to the non-inverting input terminal of the first comparator 31A. The first threshold TH1 is input to the inverting input terminal of the first comparator 31A. If the current detection value of the current detection unit 23 exceeds the first threshold TH1 in the first state, the first comparator 31A outputs a first cut-off signal. The first cut-off signal is a high-level signal. If the current detection value of the current detection unit 23 does not exceed the first threshold TH1 in the first state, the first comparator 31A does not output a first cut-off signal. That is, the first comparator 31A outputs a low-level signal. The first comparator 31A is turned on in the first state and turned off in the second state. That is, in the second state, the first comparator 31A never outputs a first cut-off signal, regardless of the current detection value of the current detection unit 23.

[0073] The current detection value of the current detection unit 23 and the second threshold TH2 are input to the second comparator 31B. The current detection value of the current detection unit 23 is input to the non-inverting input terminal of the second comparator 31B. The second threshold TH2 is input to the inverting input terminal of the second comparator 31B. If the current detection value of the current detection unit 23 exceeds the second threshold TH2 in the second state, the second comparator 31B outputs a second cut-off signal. The second cut-off signal is a high-level signal. If the current detection value of the current detection unit 23 does not exceed the second threshold TH2 in the second state, the second comparator 31B does not output a second cut-off signal. That is, the second comparator 31B outputs a low-level signal. The second comparator 31B is disconnected in the first state and connected in the second state. That is, the second comparator 31B never outputs a second cut-off signal in the first state, regardless of the current detection value of the current detection unit 23.

[0074] The NOR circuit 31C receives signals from the first comparator 31A and the second comparator 31B. When neither the first cut-off signal from the first comparator 31A nor the second cut-off signal from the second comparator 31B is output, the NOR circuit 31C outputs a high-level signal. When both the first cut-off signal from the first comparator 31A and the second cut-off signal from the second comparator 31B are output, the NOR circuit 31C outputs a low-level signal.

[0075] A signal output from the NOR circuit 31C is input to the latch circuit 31D. The latch circuit 31D outputs a high-level signal (on signal) until a low-level signal is input from the NOR circuit 31C, maintaining the first cut-off section 21 in a first enabled state. When a high-level signal is input from the NOR circuit 31C, the latch circuit 31D outputs a low-level signal (off signal), switching the first cut-off section 21 to a first cut-off state. After switching the first cut-off section 21 to the first cut-off state, the latch circuit 31D maintains the first cut-off section 21 in the first cut-off state even if the signal input from the NOR circuit 31C returns to a high-level signal. That is, the latch circuit 31D maintains the first cut-off section 21 in the first enabled state until a first cut-off signal is output from the first comparator 31A or a second cut-off signal is output from the second comparator 31B. Furthermore, the latch circuit 31D switches the first cut-off section 21 to the first cut-off state when a first cut-off signal is output from the first comparator 31A or a second cut-off signal is output from the second comparator 31B.

[0076] As a result, the first cutting unit 21 switches to the first cutting state when the first cutting signal is output from the first comparator 31A, and also switches to the first cutting state when the second cutting signal is output from the second comparator 31B.

[0077] The second cutting-off circuit 32 switches the second cutting-off section 22 to the second cutting-off state when the cutting-off condition is met. After switching the second cutting-off section 22 to the second cutting-off state, the second cutting-off circuit 32 maintains the second cutting-off section 22 in the second cutting-off state even if the cutting-off condition is not met.

[0078] When the first cut-off section 21 switches to the first cut-off state, the microcomputer 33A determines whether the first recovery condition is met. For example, the microcomputer 33A begins determining whether the first recovery condition is met upon receiving a low-level signal output from the NOR circuit 31C. If the microcomputer 33A determines that the first recovery condition is met, it controls the first cut-off circuit 31 to restore the first cut-off section 21 to the first allowable state. Specifically, the microcomputer 33A releases the latch state of the latch circuit 31D, causing the latch circuit 31D to output an enable signal.

[0079] When the second cutting section 22 switches to the second cutting state, the microcomputer 33A determines whether the second recovery condition is met. If the microcomputer 33A determines that the second recovery condition is met, it controls the second cutting circuit 32 to restore the second cutting section 22 to the second allowable state.

[0080] 1-3. Examples of operation of vehicle-mounted system 100

[0081] When the vehicle's start switch is turned on, SMR94 remains off, the first cut-off section 21 is in a first permitted state, the second cut-off section 22 is in a second permitted state, and the voltage conversion section 93 performs a second conversion operation. Thus, as... Figure 2 As shown, power from the low-voltage battery 92 is pre-charged to the capacitor 95. When the voltage of the capacitor 95 reaches the target voltage, the pre-charging is complete, and the SMR 94 is switched on. Furthermore, a first conversion operation is performed via the voltage conversion unit 93, as... Figure 3 As shown, the load 96 is in a state where power from the high-voltage battery 91 and power from the low-voltage battery 92 can be supplied. Thus, during vehicle operation, the load 96 is in a state where power from the high-voltage battery 91 and power from the low-voltage battery 92 can be supplied.

[0082] During pre-charging, current needs to be allowed to flow from the low-voltage battery 92 to the voltage conversion unit 93. Therefore, as Figure 2 As shown, the first comparator 31A is off. However, in the event of an overcurrent, the second comparator 31B is turned on to interrupt the current. In this state, for example, as shown... Figure 4 As shown, in the event of a ground fault in the second conductive path 82, current from the low-voltage battery 92 flows to the ground fault location in the second conductive path 82. Then, when an overcurrent flows through the first conductive path 81, the second comparator 31B outputs a second cutoff signal, as shown. Figure 5 As shown, the first cutting-off section 21 is switched to the first cutting-off state. This suppresses overcurrent.

[0083] Furthermore, during vehicle operation, the system is configured to supply power to the load 96 from both the voltage conversion unit 93 and the low-voltage battery 92, and in the event of a reverse current flowing from the first conductive path 81 to the voltage conversion unit 93, it needs to be quickly disconnected. Therefore, as... Figure 3 As shown, the first comparator 31A is set to ON, and the second comparator 31B is set to OFF. In this state, for example... Figure 6 As shown, in the event of a ground fault in the second conductive path 82, the current from the low-voltage battery 92 flows to the ground fault location of the second conductive path 82. Then, when the current flowing from the first conductive path 81 to the voltage conversion unit 93 exceeds the first threshold TH1, the first comparator 31A outputs a first cutoff signal, as shown. Figure 7 As shown, the first cut-off section 21 is switched to the first cut-off state. As a result, the power supply source can be switched from the voltage conversion section 93 to the low-voltage battery 92 without interrupting the power supply to the load 96.

[0084] 1-4. Examples of the effects of the vehicle-mounted cutting device 10

[0085] When the vehicle is in a first state, the on-board disconnector 10 switches the first disconnector 21 to a first disconnection state based on a current exceeding a first threshold TH1 flowing from the low-voltage battery 92 side to the voltage conversion unit 93 side. Furthermore, when the vehicle is in a second state, the on-board disconnector 10 switches the first disconnector 21 to a first disconnection state based on a current exceeding a second threshold TH2 (which is larger than the first threshold TH1) flowing from the low-voltage battery 92 side to the voltage conversion unit 93 side. In other words, the on-board disconnector 10 can change the threshold for switching the first disconnector 21 to the first disconnection state according to the vehicle's state, thus enabling appropriate current disconnection based on the vehicle's state.

[0086] The vehicle-mounted disconnect device 10 performs disconnection control when the first disconnection section 21 is in the first permitted state and the second disconnection section 22 is in the second permitted state. Therefore, even when the first disconnection section 21 is switched to the first disconnection state, the vehicle-mounted disconnect device 10 can supply power to the load 96 from the low-voltage battery 92 without interrupting the power supply to the load 96.

[0087] In the first state, when the current flowing from the low-voltage battery 92 side to the voltage conversion unit 93 side exceeds the first threshold TH1, the vehicle-mounted disconnect device 10 can quickly switch the first disconnect unit 21 to the first disconnect state via the first disconnect circuit 31. Furthermore, in the second state, when the current flowing from the low-voltage battery 92 side to the voltage conversion unit 93 side exceeds the second threshold TH2, the vehicle-mounted disconnect device 10 can also quickly switch the first disconnect unit 21 to the first disconnect state via the first disconnect circuit 31.

[0088] The first cutoff circuit 31 includes a first comparator 31A and a second comparator 31B. In the first state, the first comparator 31A of the vehicle-mounted cutoff device 10 outputs a first cutoff signal when the current detection unit 23 detects a value exceeding a first threshold TH1. In the second state, the second comparator 31B outputs a second cutoff signal when the current detection unit 23 detects a value exceeding a second threshold TH2. The first cutoff unit 21 switches to the first cutoff state when the first cutoff signal is output from the first comparator 31A, and also switches to the first cutoff state when the second cutoff signal is output from the second comparator 31B. The first comparator 31A is disconnected in the second state. This structure easily simplifies the structure of the first cutoff circuit 31.

[0089] When the vehicle-mounted disconnect device 10 is supplying power from the voltage conversion unit 93 to the first conductive circuit 81, it can immediately switch the first disconnect unit 21 to the first disconnect state in the event of a reverse current flowing back to the voltage conversion unit 93. Furthermore, when the vehicle-mounted disconnect device 10 is supplying power from the low-voltage battery 92 to the voltage conversion unit 93, it can switch the first disconnect unit 21 to the first disconnect state in the event of an overcurrent.

[0090] The vehicle-mounted disconnect device 10 can immediately switch the first disconnect section 21 to the first disconnect state if a reverse current is generated to the voltage conversion unit 93 during vehicle operation. Furthermore, the vehicle-mounted disconnect device 10 can switch the first disconnect section 21 to the first disconnect state if an overcurrent is generated during the pre-charging of the capacitor 95.

[0091] Even when the first cutting section 21 is switched to the first cutting state, the vehicle-mounted cutting device 10 can restore the first cutting section 21 to the first allowed state if the first restoration condition is met.

[0092] 2. Second Implementation Method

[0093] In the first embodiment, a structure having a first comparator 31A with a first threshold TH1 input and a second comparator 31B with a second threshold TH2 input is described. In the second embodiment, a structure that changes the threshold input to comparator 231A is described. Furthermore, structures identical to those in the first embodiment are labeled with the same reference numerals, and detailed descriptions are omitted.

[0094] 2-1. Overview of the vehicle system 200

[0095] like Figure 8 As shown, the vehicle system 200 of the second embodiment includes a high-voltage battery 91, a low-voltage battery 92, a voltage conversion unit 93, an SMR 94, a capacitor 95, a load 96, a first conductive path 81, a second conductive path 82, and a third conductive path 83.

[0096] 2-2. Structure of the vehicle-mounted cutting device 210

[0097] The vehicle system 200 includes a vehicle-mounted disconnect device 210. The vehicle-mounted disconnect device 210 has a first disconnection section 21, a second disconnection section 22, a current detection section 23, and a control section 230. The control section 230 includes a first disconnection circuit 231, a second disconnection circuit 32, and a circuit control section 233.

[0098] The first cutoff circuit 231 is composed of discrete components. The circuit control unit 233 includes a microcomputer 233A and a threshold changing circuit 233B. The microcomputer 233A controls the first cutoff circuit 231 and the second cutoff circuit 32. The threshold changing circuit 233B is composed of discrete components. The threshold changing circuit 233B receives instructions from the microcomputer 233A and selectively outputs a first threshold TH1 and a second threshold TH2. The threshold changing circuit 233B outputs the first threshold TH1 in a first state and outputs the second threshold TH2 in a second state. The value output from the threshold changing circuit 233B is input to the first cutoff circuit 231. The first cutoff circuit 231 switches the first cutoff unit 21 to a first cutoff state when the detection value of the current detection unit 23 exceeds the value input from the threshold changing circuit 233B.

[0099] The first cutting-off circuit 231 switches the first cutting-off section 21 to the first cutting-off state based on the case where current flows from the first conductive path 81 side to the voltage conversion section 93 side when the first cutting-off section 21 is in the first permitted state and the second cutting-off section 22 is in the second permitted state.

[0100] The first cut-off circuit 231 switches the first cut-off section 21 to the first cut-off state when the current detection unit 23 detects the value in the first state and exceeds the first threshold TH1. The first cut-off circuit 231 switches the first cut-off section 21 to the first cut-off state when the current detection unit 23 detects the value in the second state and exceeds the second threshold TH2.

[0101] The first cut-off circuit 231 includes a comparator 231A, a NOT circuit 231C, and a latch circuit 31D.

[0102] The current detection unit 23 and the output value of the threshold changing circuit 233B are input to comparator 231A. The current detection unit 23's detection value is input to the non-inverting input terminal of comparator 231A. The output value of the threshold changing circuit 233B is input to the inverting input terminal of comparator 231A. In a first state, the first threshold TH1 is input to the inverting input terminal of comparator 231A. In a second state, the second threshold TH2 is input to the inverting input terminal of comparator 231A.

[0103] When the current detection value of the current detection unit 23 exceeds the input value from the threshold changing circuit 233B, comparator 231A outputs a cut-off signal. The cut-off signal is a high-level signal. When the current detection value of the current detection unit 23 does not exceed the input value from the threshold changing circuit 233B, comparator 231A does not output a cut-off signal. That is, comparator 231A outputs a low-level signal.

[0104] The signal output from comparator 231A is input to NOT circuit 231C. NOT circuit 231C outputs a high-level signal when no cut-off signal is output from comparator 231A. NOT circuit 231C outputs a low-level signal when a cut-off signal is output from comparator 231A.

[0105] A signal output from the NOT circuit 231C is input to the latch circuit 31D. The latch circuit 31D outputs a high-level signal (on signal) until a low-level signal is input from the NOT circuit 231C, maintaining the first cut-off section 21 in a first enabled state. When a low-level signal is input from the NOT circuit 231C, the latch circuit 31D outputs a low-level signal (off signal), switching the first cut-off section 21 to a first cut-off state. After switching the first cut-off section 21 to the first cut-off state, the latch circuit 31D maintains the first cut-off section 21 in the first cut-off state even if the signal input from the NOT circuit 231C returns to a high-level signal. That is, the latch circuit 31D maintains the first cut-off section 21 in the first enabled state until a cut-off signal is output from the comparator 231A. Furthermore, when a cut-off signal is output from the comparator 231A, the latch circuit 31D switches the first cut-off section 21 to the first cut-off state.

[0106] As a result, the first cutting unit 21 switches to the first cutting state when a cutting signal is output from the comparator 231A.

[0107] When the first cut-off section 21 switches to the first cut-off state, the microcomputer 233A determines whether the first recovery condition is met. For example, the microcomputer 233A begins determining whether the first recovery condition is met upon receiving a low-level signal output from the NOT circuit 231C. If the microcomputer 233A determines that the first recovery condition is met, it controls the first cut-off circuit 231 to restore the first cut-off section 21 to the first allowable state. Specifically, the microcomputer 233A releases the latch state of the latch circuit 31D, causing the latch circuit 31D to output an enable signal.

[0108] 2-3. Operational Examples of Vehicle-Mounted System 200

[0109] When the start switch is switched to ON, SMR94 remains OFF, the first cut-off section 21 is in the first enabled state, the second cut-off section 22 is in the second enabled state, and the voltage conversion section 93 performs the second conversion operation. Thus, as... Figure 9 As shown, power from the low-voltage battery 92 is pre-charged to the capacitor 95. When the voltage of the capacitor 95 reaches the target voltage, the pre-charging is complete, and the SMR 94 is switched on. Furthermore, a first conversion operation is performed via the voltage conversion unit 93, as... Figure 10As shown, the load 96 is in a state where power from the high-voltage battery 91 and power from the low-voltage battery 92 can be supplied. Thus, during vehicle operation, the load 96 is in a state where power from the high-voltage battery 91 and power from the low-voltage battery 92 can be supplied.

[0110] During pre-charging, current needs to be allowed to flow from the low-voltage battery 92 to the voltage conversion unit 93. Therefore, as Figure 9 As shown, a second threshold TH2 is input to comparator 231A. In this state, for example, as... Figure 11 As shown, in the event of a ground fault in the second conductive path 82, current from the low-voltage battery 92 flows to the ground fault location in the second conductive path 82. Then, when an overcurrent flows through the first conductive path 81, comparator 231A outputs a cutoff signal, as shown. Figure 12 As shown, the first cutting-off section 21 is switched to the first cutting-off state. This suppresses overcurrent.

[0111] Furthermore, during vehicle operation, the system is configured to supply power to the load 96 from both the voltage conversion unit 93 and the low-voltage battery 92, and in the event of a reverse current flowing from the first conductive path 81 to the voltage conversion unit 93, it needs to be quickly disconnected. Therefore, as... Figure 10 As shown, a first threshold TH1 is input to comparator 231A. In this state, for example, as... Figure 13 As shown, in the event of a ground fault in the second conductive path 82, the current from the low-voltage battery 92 flows to the ground fault location in the second conductive path 82. Then, when the current flowing from the first conductive path 81 to the voltage conversion unit 93 exceeds the first threshold TH1, the comparator 231A outputs a cutoff signal, as shown. Figure 14 As shown, the first cut-off section 21 is switched to the first cut-off state. As a result, the power supply source can be switched from the voltage conversion section 93 to the low-voltage battery 92 without interrupting the power supply to the load 96.

[0112] 2-4. Examples of the effects of the vehicle-mounted cutting device 210

[0113] The vehicle-mounted cut-off device 210 can output a cut-off signal corresponding to the vehicle's state through a comparator 231A.

[0114] <Other Implementation Methods>

[0115] This disclosure is not limited to the embodiments described above and the accompanying drawings. For example, the features of the embodiments described above or later can be combined in all possible ways without contradiction. Furthermore, any feature in the embodiments described above or later can be omitted unless explicitly stated as essential. Moreover, the embodiments described above can also be modified as follows.

[0116] In the embodiments described above, the first cut-off section 21 is composed solely of MOSFET 21A. Alternatively, the first cut-off section 21 may also be composed of a pair of MOSFETs connected in reverse order. In this case, the first cut-off section 21 cuts off the bidirectional current flow through itself during the first cut-off state. Furthermore, the first cut-off section 21 may also be composed of a switch other than a MOSFET.

[0117] In the embodiments described above, the second cut-off section 22 is composed solely of MOSFET 22A. Alternatively, the second cut-off section 22 may be composed of a pair of MOSFETs connected in reverse order. In this case, the second cut-off section 22 cuts off the bidirectional current flow through itself during the second cut-off state. Furthermore, the second cut-off section 22 may also be composed of a switch other than a MOSFET.

[0118] Furthermore, the embodiments disclosed herein should be considered illustrative rather than restrictive in all respects. The scope of the invention is not limited to the embodiments disclosed herein, and is intended to include all modifications within the scope defined by or equivalent to the claims.

[0119] Label Explanation

[0120] 10…Vehicle-mounted cutting device

[0121] 21…First Cutting Section

[0122] 21A…MOSFET

[0123] 22…Second Cutting Section

[0124] 22A…MOSFET

[0125] 23… Current Detection Section

[0126] 30…Control Department

[0127] 31…First circuit cutoff

[0128] 31A…First Comparator

[0129] 31B…Second Comparator

[0130] 31C…NOR circuit

[0131] 31D…Latch Circuit

[0132] 32…Second Cut-off Circuit

[0133] 33…Circuit Control Section

[0134] 33A… Microcomputer

[0135] 81…First conductive path (conductive path)

[0136] 82…Second Conductive Circuit

[0137] 83…Third conductive path

[0138] 91…High-voltage storage battery

[0139] 92…Low-voltage storage battery (second power supply unit)

[0140] 93…Voltage Conversion Section (First Power Supply Section)

[0141] 94…System Main Relay

[0142] 95… capacitor

[0143] 96…load

[0144] 100…in-vehicle system

[0145] 200…in-vehicle system

[0146] 210…Vehicle-mounted cutting device

[0147] 230…Control Department

[0148] 231…First circuit cutoff

[0149] 231A… Comparator

[0150] 231C…NOT circuit

[0151] 233…Circuit Control Section

[0152] 233A… Microcomputer

[0153] 233B…Threshold Changing Circuit

[0154] TH1…First Threshold

[0155] TH2…Second threshold.

Claims

1. A vehicle-mounted disconnect device, included in a vehicle system, the vehicle system comprising a first power supply unit, a second power supply unit, a conductive circuit, and a load, wherein the conductive circuit is disposed between the first power supply unit and the second power supply unit, and the load is electrically connected to the conductive circuit, wherein... The vehicle-mounted cutting device includes: A first cutting-off portion is disposed between the first power supply portion and the conductive path; and The control unit controls the first cutting unit. The first cut-off section switches between a first allowable state and a first cut-off state. In the first allowable state, current flows from the second power supply side to the first power supply side, and in the first cut-off state, current flow from the second power supply side to the first power supply side is cut off. The control unit performs a cut-off control. When the vehicle is in a first state, the cut-off control switches the first cut-off unit to the first cut-off state based on the current flowing from the second power supply side to the first power supply side exceeding a first threshold. When the vehicle is in a second state, the first cut-off unit switches to the first cut-off state based on the current flowing from the second power supply side to the first power supply side exceeding a second threshold greater than the first threshold.

2. The vehicle-mounted cutting device according to claim 1, wherein, The vehicle-mounted cutting device has a second cutting section, which is disposed between the second power supply section and the conductive circuit. The second cutting-off section is controlled by the control section, and switches between a second permitted state and a second cutting-off state. In the second permitted state, current is allowed to flow from the first power supply side to the second power supply side, and in the second cutting-off state, the flow of current from the first power supply side to the second power supply side is cut off. The control unit performs the cutting control when the first cutting unit is in the first permitted state and the second cutting unit is in the second permitted state.

3. The vehicle-mounted cutting device according to claim 1 or claim 2, wherein, The vehicle-mounted disconnect device includes a current detection unit that detects the current flowing from the second power supply side to the first power supply side. The control unit includes a first disconnect circuit. When the current detection value of the first cutting-off circuit exceeds the first threshold in the first state, the first cutting-off circuit switches the first cutting-off section to the first cutting-off state. When the current detection value of the first cutting-off circuit exceeds the second threshold in the second state, the first cutting-off section switches the first cutting-off section to the first cutting-off state.

4. The vehicle-mounted cutting device according to claim 3, wherein, The first cut-off circuit includes a first comparator and a second comparator. If the current detection value of the first comparator exceeds the first threshold in the first state, the first comparator outputs a first cut-off signal. If the current detection value of the second comparator exceeds the second threshold in the second state, the second comparator outputs a second cut-off signal. The first cutting unit switches to the first cutting state when the first cutting signal is output from the first comparator, and also switches to the first cutting state when the second cutting signal is output from the second comparator. The first comparator is disconnected in the second state.

5. The vehicle-mounted cutting device according to claim 3, wherein, The control unit includes a circuit control unit. The first cut-off circuit includes a comparator. The comparator outputs a cut-off signal when the detected value of the current detection unit exceeds the input value input from the circuit control unit. The circuit control unit inputs the first threshold to the comparator in the first state, and inputs the second threshold to the comparator in the second state. The first cutting section switches to the first cutting state when the cutting signal is output from the comparator.

6. The vehicle-mounted cutting device according to claim 1 or claim 2, wherein, The first state is the state in which power is supplied from the first power source to the conductive path side. The second state is the state of supplying power from the second power source to the first power source.

7. The vehicle-mounted cutting device according to claim 6, wherein, The on-board system includes a high-voltage battery, a main system relay, and a capacitor. The second power supply unit is a low-voltage battery. The first power supply unit is a voltage conversion unit disposed between the high-voltage battery and the low-voltage battery. The voltage conversion unit performs a first conversion operation and a second conversion operation. The first conversion operation boosts or bucks the voltage input from the high-voltage battery side and outputs it to the low-voltage battery side. The second conversion operation boosts or bucks the voltage input from the low-voltage battery side and outputs it to the high-voltage battery side. The system's main relay is located between the high-voltage battery and the voltage conversion unit. The capacitor is electrically connected in the electrical path between the system's main relay and the voltage conversion unit. In the vehicle system, when the vehicle's start switch is turned on, the voltage conversion unit performs the second conversion operation to precharge the capacitor while keeping the system's main relay off. After precharging the capacitor, the system's main relay is turned on. The first state is when the start switch is on and the system main relay is on. The second state is when the start switch is on and the system main relay is off.

8. The vehicle-mounted cutting device according to claim 1 or claim 2, wherein, After switching the first cutting section to the first cutting state, the control unit restores the first cutting section to the first allowed state if the first recovery condition is met.

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