Vehicle control device

Abstract

A vehicle control device is realized which, in a vehicle control device using a semiconductor fuse, can suppress the large size of the semiconductor fuse, and can detect the generation of an abnormal current early and cut off. The vehicle control device includes a cut-off section (6) which performs power supply and cut-off to a plurality of load devices (4a to 4c), a current detection section (13) which detects current flowing through the plurality of load devices (4a to 4c), and a temperature detection section (13d) which detects the temperature of the cut-off section (6). Further, the vehicle control device is provided with a drive control section (13b) which, when the temperature of the cut-off section (6) detected by the temperature detection section (13d) exceeds a prescribed value, performs control and restriction of the operation of a load device (4a to 4c) having a low priority based on priorities respectively set for the plurality of load devices (4a to 4c).

Description

Technical Field

[0001] This invention relates to vehicle control devices. Background Technology

[0002] In recent years, functions such as opening and closing doors and parking brakes, which are manually operated by passengers such as drivers, have been electrified, and more electric actuators have been installed in vehicles.

[0003] Consequently, the number of sensors and actuators has increased, and the control units (ECUs) and wiring harnesses for each function have become bulky, posing challenges to vehicle space, weight, and manufacturing time. Furthermore, advancements in autonomous driving capabilities demand high vehicle reliability, requiring continuous operation until a safe state is reached when a vehicle malfunctions.

[0004] To achieve such diverse functions, integrating the ECUs that control various electric actuators is an effective way to reduce the number of ECUs and cut wiring harnesses. Integration allows direct access to various sensors and actuators, and centralized control of them improves functional scalability. Furthermore, integrating each area of ​​the vehicle reduces the amount of wiring required to connect to sensors and actuators.

[0005] In the power supply to the electric actuator, if an abnormal current flows through the power line for an extended period, a fuse is provided to cut off the power supply to prevent the device or wiring harness from catching fire. In addition, a relay is provided to turn the power supply to the electric actuator on / off.

[0006] Previously, these fuses and relays were housed in a separate power supply unit from the ECU. If an abnormal current flowed through, the existing fuses would blow due to Joule heating, cutting off the power supply. To restore power, the fuses needed to be replaced. Therefore, for ease of fuse replacement, the power supply unit was placed in a location easily accessible to the user.

[0007] On the other hand, ECUs are often located in places that are not easily accessible to users, and they are securely fastened to protect the internal electronic components from water droplets and other contaminants. When such ECUs are equipped with fuses and relays, replacement requires opening the unit to replace the blown fuse.

[0008] Therefore, semiconductor-type fuses, which implement the functions of existing fuses and relays using semiconductor transistors, are used. Semiconductor-type fuses utilize MOS transistors and microcomputers to achieve the functions of existing fuses and relays. In semiconductor fuses, the temperature of the wiring harness is estimated based on the current flowing through the power line. If the wiring harness poses a fire hazard due to abnormal current, the MOS transistor is turned off. If the abnormal current is eliminated, the MOS transistor can be turned on again, thus eliminating the need for replacement as required by fuses.

[0009] However, if the number of actuators requiring power increases, the current capacity of the MOS transistors needs to be increased. Furthermore, to ensure proper heat dissipation, multiple MOS transistors need to be connected in parallel, increasing cost and substrate mounting area.

[0010] Patent Document 1 discloses a technology for solving this problem. In a power supply system that supplies power to multiple loads based on the technology described in Patent Document 1, one end of a fuse is connected to a power source, and the other end of the fuse is connected to multiple load devices via semiconductor switches. Furthermore, it includes a receiving unit that receives indication signals for the semiconductor switches to turn on and off, and a control device that controls the turning on and off of the multiple semiconductor switches.

[0011] Upon receiving an indication signal that enables multiple semiconductor switches to conduct simultaneously, the control device staggers the timing of the activation of the multiple semiconductor switches to activate them.

[0012] According to the technology described in Patent Document 1, multiple semiconductor switches are turned on by staggering the timing, so the current flowing through the fuse is dispersed and the size of the fuse can be suppressed. Existing technical documents Patent documents

[0013] Patent Document 1: Japanese Patent Application Publication No. 2019-41508 Summary of the Invention The technical problem that the invention aims to solve

[0014] However, while the technology described in Patent Document 1 is effective in reducing the current capacity of existing fusible fuses, there is room for further improvement in systems using semiconductor fuses in the following aspects.

[0015] First, in automotive systems using semiconductor fuses, the MOS transistors that cut off power supply must not fail. Specifically, if a MOS transistor becomes hot, its allowable current decreases, making it prone to damage. To ensure that the current flowing through the MOS transistor does not exceed the allowable current even at high temperatures, it is necessary to increase the size of the MOS transistors and to connect them in parallel.

[0016] Furthermore, even when multiple actuators are connected via a single semiconductor fuse, it is necessary to detect and cut off abnormal currents as early as possible.

[0017] The present invention was made to solve the above-mentioned problems, and its purpose is to realize a vehicle control device that, in a vehicle control device using a semiconductor fuse, can suppress the enlargement of the semiconductor fuse and can detect and cut off the generation of abnormal current as early as possible. Technical means for solving technical problems

[0018] To achieve the above objectives, the present invention is configured as follows.

[0019] The vehicle control device includes: a cut-off unit that cuts off power supply to and from multiple load devices; a current detection unit that detects the current flowing through the multiple load devices; a temperature detection unit that detects the temperature of the cut-off unit; and a drive control unit that, when the temperature of the cut-off unit detected by the temperature detection unit exceeds a predetermined value, controls and restricts the operation of the load devices with lower priority based on the priority set for each of the multiple load devices. Invention Effects

[0020] A vehicle control device can be implemented that, in a vehicle control device using a semiconductor fuse, can suppress the enlargement of the semiconductor fuse and can detect and cut off the generation of abnormal current as early as possible. Attached Figure Description

[0021] Figure 1 This is a structural diagram of the vehicle control device that applies Embodiment 1 of the present invention. Figure 2 This is a diagram showing the structure of the vehicle control device in Embodiment 1 of the present invention. Figure 3 This is a diagram illustrating the operation of the cutting device in Embodiment 1 of the present invention. Figure 4A This is a diagram illustrating the timing of the operation of the load device in an example different from that of the present invention. Figure 4B This is a diagram showing the timing of the operation of the load device in Embodiment 1 of the present invention. Figure 5 This is a table illustrating examples of the priority device in Embodiment 1 of the present invention. Figure 6 This is a diagram illustrating a more efficient method for timing the operation of the load device in Embodiment 1 of the present invention. Figure 7 This is a diagram illustrating a more efficient method for timing the operation of the load device in Embodiment 1 of the present invention. Figure 8 This is a diagram showing the structure of the vehicle control device in Embodiment 2 of the present invention. Figure 9 This is a diagram showing the structure of the vehicle control device in Embodiment 3 of the present invention. Detailed Implementation

[0022] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. [Example]

[0023] (Example 1) For the vehicle control device according to Embodiment 1 of the present invention, an example of supplying power to multiple electric actuators through a power supply system mounted on the vehicle will be described.

[0024] Figure 1 This is a simplified structural diagram of the power supply system 1 of the vehicle control device according to Embodiment 1 of the present invention. The power supply system 1 has control functions for supplying power to multiple load devices 4a, 4b, and 4c and issuing operation commands to the multiple load devices 4a, 4b, and 4c. The power supply system 1 supplies power to load devices such as lights, air conditioning compressors, PTC heaters, cooling pumps, and fans. The power supply system 1 includes a battery 2 mounted in the vehicle, a control unit 3, and load devices 4a, 4b, and 4c. The control unit 3 corresponds to the vehicle control device.

[0025] Battery 2 uses DC power sources such as lead-acid batteries, nickel-metal hydride batteries, and lithium-ion batteries that are installed in the vehicle.

[0026] The control unit 3 includes an arithmetic unit 5, a cutting-off device (cutting-off section) 6, a primary power supply line 7a, a secondary power supply line 7b, a control input line, and a control output line 8. Power from the battery 2 is supplied to the load devices 4a to 4c via the primary power supply line 7a, the cutting-off device 6, and the secondary power supply line 7b. One end of the primary power supply line 7a is connected to the battery 2, and the other end is connected to the cutting-off device 6. One end of the secondary power supply line 7b is connected to the cutting-off device 6, and the other end is connected to the load devices 4a to 4c. The secondary power supply line 7b connects from one cutting-off device 6 to multiple load devices 4a to 4c in a branched connection. The cutting-off device 6 performs power supply and cut-off operations to the multiple load devices 4a to 4a.

[0027] The control unit 3 includes an arithmetic logic unit (ALU) 5, which receives control signals from external sources from the control input line 8 and outputs drive commands to multiple load devices 4a to 4c based on the internal processing results of the ALU 5. The drive commands are output via the control output line 9, which connects the ALU 5 to the load devices 4a to 4c. The control input line 8 can use serial AC communication methods such as CAN or LIN, or a voltage input method that inputs voltage changes corresponding to the on / off state of a switch.

[0028] Furthermore, as the control output line 9, it can use serial AC communication methods such as CAN or LIN, or a voltage output method that outputs voltage changes corresponding to the on / off state of the drive.

[0029] In this embodiment 1, Figure 1 The example shown illustrates a structure with control input line 8 and control output line 9 provided in each load device 4a to 4c. However, it can also be configured to use a serial communication interface to connect control input line 8 and control output line 9 via a bus.

[0030] The current value Is flowing through the secondary power supply line 7b and the temperature Tb of the cutting device 6 are input to the arithmetic unit 5. Furthermore, the arithmetic unit 5 uses these current values ​​Is and the cutting device temperature Tb to determine the overcurrent state of the current flowing through the secondary power supply line 7b. If it is determined that the current flowing through the secondary power supply line 7b is in an overcurrent state, the arithmetic unit 5 outputs a cutting-off signal Sc to the cutting device 6, cutting off the current and restricting or limiting the current flowing through the secondary power supply line 7b.

[0031] The disconnection device 6 cuts off the current flowing from battery 2 to load devices 4a-4c when it becomes abnormal, to prevent the load devices 4a-4c and the secondary power supply line 7b from overheating, smoking, catching fire, and malfunctioning. The disconnection device 6 is formed by a semiconductor switch such as a MOS transistor.

[0032] The cutting device 6 has the functions of existing fuses and relays. Existing fuses blow when a current exceeding the rated current flows through them within a specified time. To restore the device, the fuse needs to be replaced. By using a semiconductor switch to form the cutting device, even if an abnormal current is generated and the device is cut off, it can be restored using the cutting signal Sc. Therefore, the replacement work required for existing fuse-type devices is eliminated.

[0033] Therefore, it becomes easy to integrate existing fuse boxes into the vehicle control unit without the need for a fuse replacement mechanism.

[0034] Figure 2 In the diagram, a specific example of a MOS transistor is shown as the cut-off device 6. The cut-off device 6 includes a source MOSFET 10a through which load current flows and a sensing MOSFET 10b for detecting current.

[0035] The source MOSFET 10a and the sensing MOSFET 10b are manufactured on the same semiconductor chip using the same process, resulting in good device matching accuracy. Therefore, the current flowing through these source MOSFETs 10a and sensing MOSFETs 10b is determined by the ratio of their resistance values. In other words, if the current flowing through the sensing MOSFET 10b is detected, the load current can be detected.

[0036] The gate terminals of the source MOSFET 10a and the sensing MOSFET 10b are connected to the arithmetic unit 5, providing a gate signal 11a. The arithmetic unit 6 controls the turn-on / turn-off of the source MOSFET 10a and the sensing MOSFET 10b via the gate signal 11a. The current flowing through the sensing MOSFET 10b is input to the current detection unit 13c of the arithmetic unit 5. Thus, the current detection unit 13c detects the current values ​​flowing through the multiple load devices 4a to 4c.

[0037] In addition, a temperature sensor 12 is provided to detect the temperature of the cutting device 6. The temperature sensor 12 can be configured to be disposed on the same substrate adjacent to the cutting device 6, or it can be built into the cutting device 6. Alternatively, the temperature sensor 12 can be disposed in another part, and the temperature of the cutting device 6 can be estimated based on the detected temperature. The temperature sensor 12 can also detect the temperature of the semiconductor transistor, i.e., the source MOSFET 10a, and set it as the temperature of the cutting device 6. Furthermore, it can be configured to measure the potential difference between the drain and source of the source MOSFET 10a and convert it into temperature, instead of the temperature sensor 12.

[0038] The temperature sensor 12 can be a thermistor, a resistance temperature detector, or the like. The signal detected by the temperature sensor 12 is input to the temperature detection unit 13d of the arithmetic unit 5.

[0039] As the arithmetic unit 5, a microprocessor or the like can be used. As a function of the arithmetic unit 5, a cut-off determination unit 13a is set up to perform cut-off determination using current signals and temperature signals from the cut-off device 6, change the voltage level of the gate signal 11a, and control the turn-on / turn-off of the source MOSFET 10a and the sensing MOSFET 10b.

[0040] Furthermore, the cut-off determination unit 13a sends a determination value 11b to the drive control unit 13b based on signals from the sensing MOSFET 10b and the temperature sensor 12. The drive control unit 13b, according to the determination value 11b (determination of whether a predetermined temperature has been exceeded), and based on the drive signal from the control input line 8 and the priority of the load devices 4a-4c, outputs a drive or stop command to the load devices 4a-4c via the control output line 9. The drive control unit 13b controls and limits the operation of the load devices 4a-4c.

[0041] Furthermore, as the cut-off device 6, it incorporates a semiconductor transistor, such as a MOS transistor. To utilize these transistors, their permissible characteristics must be considered. The permissible current value of a semiconductor transistor decreases as temperature increases. This is determined by factors such as the junction temperature of the semiconductor and the required lifespan of the device.

[0042] In particular, the permissible current value decreases at high temperatures. Therefore, it is necessary to design the system so that the sum of the maximum currents of the various load devices 4a to 4c does not exceed the permissible current of the semiconductor element.

[0043] However, it is very rare for the current of multiple load devices 4a to 4c to be at its maximum value simultaneously. In other words, if the design is to include events that occur at very low frequencies, multiple MOS transistors as cut-off devices 6 need to be connected in parallel, which increases the component cost.

[0044] Therefore, in this invention, the arithmetic unit 5 has the following functions.

[0045] The arithmetic unit 5 in the power supply system 1 stores the priorities of multiple loads 4a to 4c in the memory 13e. When the temperature of the cutting-off device 6 exceeds a specified value, it restricts the start-up of loads with lower priorities. Furthermore, when the temperature of the cutting-off device 6 exceeds a specified value, the cutting-off threshold calculated based on the current value and time is set lower than when the temperature is low.

[0046] That is, the cutting-off device 6 has a first current cutting-off threshold for cutting off power to multiple load devices 4a to 4c based on the current detection value detected by the current detection unit 13c, and a second current cutting-off threshold that is smaller than the first current cutting-off threshold. Then, when the temperature detected by the temperature detection unit 13c is below a predetermined value, the first current cutting-off threshold is set, and when the temperature detected by the temperature detection unit 13c exceeds the predetermined value, the second current cutting-off threshold is set.

[0047] use Figure 3 To illustrate the above actions. Figure 3 The cutoff threshold (at low temperatures) represents the load current and the time from when the load current flows through it until it is cut off. The larger the current flowing through the load, such as the inrush current when the load starts, the shorter the cutoff time should be set. Figure 3 The load current (at low temperature) indicates the maximum value of the load current when load devices 4a to 4c are operating normally, so that the tripping threshold is triggered when the current flowing through load devices 4a to 4c becomes abnormally high. The tripping threshold is set to a value higher than the load current (at low temperature) and is configured to interrupt abnormal overcurrents. For example, the tripping threshold is set to approximately 1.3 times the load current.

[0048] Figure 3 The allowable current (at low temperature) for the MOS transistor shown is the current value allowed for the source MOSFET 10a under low temperature conditions. The specifications of the source MOSFET 10a are selected based on the maximum load current (at low temperature). If the conditions change to high temperature, the allowable current value of the source MOSFET 10a is as follows: Figure 3As shown in the figure, the allowable current (at high temperature) of the MOS transistor decreases. Therefore, the load current exceeds the allowable current of the source MOS transistor 10a, causing the source MOSFET 10a to fail.

[0049] In the prior art, in order to prevent the source MOSFET10a from malfunctioning, it is necessary to select a current sensing MOS transistor that has a permissible current under high temperature conditions, or to connect multiple current sensing MOS transistors in parallel, which increases the component cost.

[0050] In this invention, such as Figure 3 As shown in the load current (at high temperature), if the temperature of the cut-off device 6 rises, the startup of lower-priority load devices is restricted. Furthermore, when the temperature of the cut-off device 6 exceeds a specified value, the cut-off threshold is set lower than at low temperatures. Therefore, even under high-temperature conditions, the current of the load device is ensured not to exceed the allowable current of the cut-off device 6. Moreover, regarding the cut-off threshold, by setting it lower at high temperatures than at low temperatures, abnormal currents can be detected and cut off earlier, even when the allowable current of the load device decreases. In other words, by dynamically changing the cut-off threshold based on the operating status of multiple load devices, an optimal cut-off threshold can be set, enabling early detection and cut-off of abnormal currents.

[0051] Next, use Figure 4A and Figure 4B This is an example illustrating a method for suppressing the maximum current of the load device when the temperature of the cutting device 6 rises.

[0052] Figure 4A These are examples that differ from the present invention and are used for comparison with the present invention. Figure 4A The diagram shows the drive current of the load devices when driving multiple load devices at low temperatures, and the sum of the drive currents of these multiple load devices. Figure 4A Load device RL1 is an actuator that operates intermittently, such as a brake light. Load device RL2 is an actuator that draws a large current at startup, which then gradually decreases and reaches a steady state, such as a heater. Load device RL3 is an actuator that habitually draws a large current at startup, such as a fan motor.

[0053] At low temperatures, load devices RL1, RL2, and RL3 are driven via control input line 8 according to their drive requests. If the timing of the drive requests from control input line 8 overlaps, load devices RL1, RL2, and RL3 start simultaneously. Therefore, the current flowing through the disconnect device 6 becomes the sum of the inrush currents Ipa during the startup of load devices RL1, RL2, and RL3.

[0054] Figure 4BThe current flowing through the cutting device 6 is shown when Embodiment 1 of the present invention is applied. Figure 4B In this configuration, load device RL1 is the brake light, which requires immediate activation in response to the driver's braking action and is therefore a high-priority load device. Load devices RL2 and RL3 are the vehicle's cooling systems or air conditioning units, which do not require immediate response to start commands. This configuration involves priority devices such as vehicle driving (driving force, braking force) and safety devices, while on the other hand, there are non-priority devices such as air conditioning, whose start-up timing is not critical.

[0055] Therefore, in Embodiment 1 of the present invention, the priority device is driven immediately in response to a drive request from the control input line 8, while the non-priority device RL2 is started after a time interval following the driving of the priority device RL1. Furthermore, the non-priority device RL3 is started after the large current decreases when the non-priority device RL2 is driven and started.

[0056] In other words, when the temperature of the cutting device 6 exceeds the specified value, the drive control unit 13b sets a time difference for the start-up timing of the multiple load devices 4a to 4c based on the reduction characteristics of the drive current when each of the multiple load devices 4a to 4c starts up and the aforementioned priority.

[0057] Therefore, the timing of startup is distributed, which can suppress the peak current Ipb of the sum of the load currents. Furthermore, for priority critical equipment, the drive timing is not restricted, thus ensuring vehicle safety during operation.

[0058] Next, use Figure 5 An example of a priority device is provided. Figure 5 This is an example of equipment mounted on a vehicle. Priority equipment includes, in particular, fuel pumps for powertrain systems related to vehicle operation and safety-related equipment such as headlights, parking lights, taillights, and windshield wipers.

[0059] As a non-priority device, it refers to devices that can be replaced by other devices such as small lights or fog lights, or devices such as cooling systems or air conditioning systems whose start-up timings are staggered by a few seconds, and whose substantial impact is small.

[0060] Furthermore, the priority settings can be adjusted based on factors such as driving time and weather. For example, headlights and taillights are prioritized at night, but their priority can be reduced during the day. Additionally, even during the day, headlights and taillights are prioritized in near-nighttime conditions such as tunnels. Moreover, windshield wipers are prioritized in rainy weather, but their priority can be reduced otherwise.

[0061] Therefore, even in the presence of multiple priority devices (load devices), the priority can be changed according to the vehicle's travel time, driving environment, and driving status, thereby further distributing the startup timing and reducing the peak current required by the power supply. Furthermore, the operation of particularly priority devices is not restricted according to the vehicle's driving status, thus ensuring vehicle safety during operation.

[0062] Regarding peak current suppression, utilizing Figure 6 To illustrate a more effective method. For example... Figure 6 As shown, if the priority device RL1 is driven, the driving of other non-priority devices RL2 and RL3 will be stopped, and the non-priority devices RL2 and RL3 will be driven again after the priority device RL1 stops.

[0063] That is, when the temperature of the cutting device 6 exceeds the specified value, the drive control unit 13b sets the time difference for starting and stopping the multiple load devices 4a to 4c based on the priority of the multiple load devices 4a to 4c, the reduction characteristics of the drive current when the load devices 4a to 4c start, and the current characteristics when the load devices 4a to 4c stop.

[0064] This structure can further suppress peak current and ensure the current supplied to critical equipment. To ensure the power supply current of critical equipment, use Figure 7 To illustrate a more effective method. Figure 7 This is an effective method when the temperature of the cutting device 6 rises further and the available current drops significantly.

[0065] Figure 7 In this configuration, load device RL2 is configured to cool the vehicle's powertrain, including the engine, while load device RL3 is configured to power the vehicle's air conditioning system. The powertrain cooling device could be, for example, a radiator fan motor. If the powertrain temperature continues to rise, the fan motor is driven to cool the powertrain. Because the powertrain temperature gradually increases, temperature prediction is relatively easy.

[0066] Therefore, when it is predicted that the powertrain temperature will rise and approach the state of the drive motor fan, other load devices RL3 are preemptively disconnected, causing the current flowing through the disconnection device 6 to decrease, thereby lowering the temperature of the disconnection device 6. If the temperature of the disconnection device 6 decreases, the available current increases, ensuring the current required by the load device RL2, i.e., the fan motor.

[0067] That is, when the operation of important equipment can be predicted, the drive control unit 13b calculates the estimated start-up timing of high-priority load devices. By stopping low-priority load devices before the estimated start-up timing, the temperature of the cut-off device 6 can be reduced in advance, ensuring the current used to drive the high-priority load devices. Thus, even if the temperature of the cut-off device 6 further increases and the available current decreases significantly, the important equipment can still be operated.

[0068] The above methods can achieve the same effect by stopping the operation of non-critical equipment when critical equipment has operated or when operation is predicted, but by limiting the supplied current so as not to completely stop it.

[0069] Furthermore, in this embodiment 1, a structure was described in which the start-up timing of the multiple load devices 4a to 4c is not restricted when the temperature of the cutting device 6 is low. However, it can also be configured to stagger the drive timing of the priority devices and non-priority devices even at low temperatures, and to further strictly restrict the start-up timing when the temperature rises. In other words, even if the configuration is such that the drive of the non-priority devices is subject to greater restrictions due to the rise in temperature of the cutting device 6 than at low temperatures, the same effect of the present invention can be obtained.

[0070] As described above, according to Embodiment 1 of the present invention, a vehicle control device can be implemented that, in a vehicle control device using a semiconductor fuse, can suppress the enlargement of the semiconductor fuse and can detect and cut off the generation of abnormal current in advance.

[0071] (Example 2) In Example 1, the structure using a MOS transistor as the cutting-off device 6 was described, but in Example 2, as... Figure 8 As shown, the configuration uses a MOS transistor 14a and a shunt resistor 14b. Other structures are the same as in Example 1.

[0072] Figure 8 The cutoff device 60 shown consists of a MOS transistor 14a through which the load current flows and a shunt resistor 14b for detecting the current. The MOS transistor 14a and the shunt resistor 14b are connected in series and carry the same load current. The gate terminal of the MOS transistor 14a is connected to the cutoff determination unit 13a of the arithmetic unit 5 and is provided with a gate signal 11a. The cutoff determination unit 13a of the arithmetic unit controls the on / off state of the MOS transistor 14a through the gate signal 11a. The voltage across the shunt resistor 14b is input to the current detection unit 13c of the arithmetic unit 5. The voltage across the shunt resistor 14b changes according to the current, thus enabling the detection of the load current.

[0073] In addition, a temperature sensor 12 is provided to detect the temperature of the MOS transistor 14a. The temperature sensor 12 can be configured to be disposed on the same substrate adjacent to the MOS transistor 14a, or it can be embedded within the MOS transistor 14a. A thermistor, a resistance temperature detector, or the like can be used as the temperature sensor 12. The signal detected by the temperature sensor 12 is input to the temperature detection unit 13d of the arithmetic unit 5.

[0074] Figure 8 The structure shown illustrates an example with a single MOS transistor 14a, but it can also be configured to have multiple MOS transistors connected in parallel. In this case, the gate terminals of the multiple MOS transistors are provided with gate signals 11a.

[0075] In Example 2, in addition to achieving the same effects as in Example 1, it also has the effect of being able to construct the cutting device 60 with inexpensive components.

[0076] (Example 3) Figure 9 This is a simplified structural diagram of the power supply system 20 according to Embodiment 3 of the present invention. The power supply system 20 is configured to include a main unit 26 having control functions for managing the drive of multiple load devices 4a to 4c, and a subunit 27 supplying power to the multiple load devices 4a to 4c. The main unit 26 and the subunit 27 are the vehicle control device of Embodiment 3.

[0077] The main unit 26 includes an arithmetic unit 21, a cut-off device 28, a primary power supply line 29a, a secondary power supply line 29b, a control input line 30, and a communication line 31. Power from the battery 2 is supplied to the subunit 27 via the primary power supply line 29a, the cut-off device 28, and the secondary power supply line 29b. One end of the primary power supply line 29a is connected to the battery 2, and the other end is connected to the cut-off device 28. One end of the secondary power supply line 29b is connected to the cut-off device 28, and the other end is connected to the subunit 27.

[0078] Subunit 27 includes an arithmetic unit 22, switches 32a-32c, a secondary power supply line 29b, a communication line 31, and a control output line 33. Power from the secondary power supply line 29b is supplied to the load devices 4a-4c via switches 32a-32b. The secondary power supply line 29b is connected from a disconnector 28 to a plurality of load devices 4a-4c in a branched connection.

[0079] The main unit 26 is equipped with an arithmetic unit 21, which receives control signals from the outside via the control input line 30 and outputs drive commands to multiple load devices 4a to 4c based on the internal processing results of the arithmetic unit 21. The output of the drive commands is transmitted to the arithmetic unit 22 of the sub-unit 27 via the communication line 31. The arithmetic unit 21 has the same cut-off determination unit 13a and drive control unit 13b as in Embodiment 1. The communication line 31 can use serial AC communication methods such as CAN or LIN. The cut-off device 28 can adopt the same structure as the cut-off device 6 in Embodiment 1 or the cut-off device 60 in Embodiment 2.

[0080] The arithmetic logic unit 22, located in subunit 27, controls the switches 32a-32c that supply power to or disconnect from the load devices 4a-4b based on drive commands received from the communication line 31. Therefore, the arithmetic logic unit 22 also functions as the drive control unit. The on / off control of switches 32a-32c is transmitted via the control output line 33. Switches 32a-32c are formed of semiconductor switches such as MOS transistors.

[0081] In Embodiment 3, the drive control unit of the arithmetic unit 21 of the main unit 26 and the arithmetic unit 22 of the subunit 27 control and limit the drive of the load devices 4a to 4c. Therefore, the main unit 26 can be defined as having a first drive control unit and the subunit 27 as having a second drive control unit. Furthermore, the drive control unit in Embodiment 3 can be defined as having a first drive control unit that outputs drive commands and a second drive control unit that controls and limits the operation of the load devices 4a to 4c based on the drive commands from the first drive control unit.

[0082] In the above structure, the current value Is based on the current flowing in the secondary power supply line 29b and the cutting device temperature Tb based on the temperature of the cutting device 28 are input to the arithmetic unit 21 of the main unit 26. Furthermore, the arithmetic unit 21 uses these current values ​​Is and the cutting device temperature Tb to estimate the overcurrent state.

[0083] If it is determined that there is an overcurrent, the arithmetic unit 21 will output the cut-off signal Sc to the cut-off device 28, cut off the cut-off device 28, and cut off or limit the current flowing through the secondary power supply line 29b.

[0084] The disconnection device 28 disconnects the current flowing from battery 2 to sub-cell 27 when it becomes abnormal, to prevent the load devices 4a-4c and secondary power supply line 29b from overheating, smoking, catching fire, and malfunctioning. The disconnection device 28 is formed by a semiconductor switch such as a MOS transistor.

[0085] In this embodiment 3, the arithmetic unit 26 of the main unit 26 has the following functions as shown in embodiment 1.

[0086] The arithmetic unit 21 has a memory 13e, which stores the preset priorities of the multiple load devices 4a to 4b connected to the subunit 27. When the temperature of the cutting device 28 exceeds a specified value, it restricts the start-up of load devices with lower priorities.

[0087] Furthermore, when the temperature of the cutting device 28 exceeds a predetermined value, the cutting threshold calculated based on the current value and time is set lower than that at low temperatures. The operation of the arithmetic unit 21 is the same as that of the arithmetic unit 5 shown in Embodiment 1.

[0088] Therefore, similar to Embodiment 1, even under high-temperature conditions, the current flowing through the load devices 4a-4c can be kept below the allowable current of the cutting-off device 28. Furthermore, by setting the cutting-off threshold lower at high temperatures than at low temperatures, abnormal currents can be detected and cut off earlier, even when the maximum current of the load devices 4a-4c is lower. In other words, by dynamically changing the cutting-off threshold based on the operating states of the multiple load devices 4a-4c, an optimal cutting-off threshold can be set, enabling early detection and cutting off of abnormal currents.

[0089] In this embodiment 3, a structure with one sub-unit 27 is shown, but it can also be configured as multiple sub-units 27 connected to the secondary power supply line 29b and the communication line 31.

[0090] According to Embodiment 3, in addition to obtaining the same effect as in Embodiment 1, the following effect can also be obtained: when configured to include a main unit 26 and multiple sub-units 27, when changing the cut-off determination value, etc., only the setting value of the main unit 26 needs to be changed. Label Explanation

[0091] 1 Power supply system 2 batteries 3 Control Unit 4a, 4b, 4c load devices 5. Arithmetic Unit 6. Cutting device 7a Primary power supply line 7b Secondary power supply line 8 control input lines 9 Control output lines 10A Source MOSFET 10b sensing MOSFET 11a Gate signal 11b Judgment Value 12 Temperature Sensors 13a Cut-off determination unit 13b Drive Control Unit 13c Current Detection Unit 13c Temperature Detection Section 14 Cutting device 14a MOS transistor 14b Shunt resistor 20 Power Supply System 21, 22 Arithmetic Units 26 Main Units 27 sub-units 28 Cutting device 29a Primary power supply line 29b secondary power supply line 30 control input lines 31 Communication Line 32a~32c switches 33 Control output line.

Claims

1. A vehicle control device, characterized in that, include: A cutting-off section that performs power supply and disconnection to multiple load devices; A current detection unit that detects the current flowing through the plurality of load devices; A temperature detection unit detects the temperature of the cut section; as well as The drive control unit, when the temperature of the cutting section detected by the temperature detection unit exceeds a predetermined value, controls and restricts the operation of the load devices with lower priority based on the priority settings assigned to each of the plurality of load devices. When the temperature of the cutting section exceeds the predetermined value, the drive control unit sets a time difference for the start-up timing of the multiple load devices based on the reduction characteristics of the drive current when each of the multiple load devices starts up and the priority.

2. The vehicle control device as described in claim 1, characterized in that, The cutting-off unit has a first current cutting-off threshold for cutting off power to the plurality of load devices based on the current detection value detected by the current detection unit, and a second current cutting-off threshold that is smaller than the first current cutting-off threshold. The first current cutting-off threshold is set when the temperature detected by the temperature detection unit is below the predetermined value, and the second current cutting-off threshold is set when the temperature exceeds the predetermined value.

3. The vehicle control device as described in claim 1, characterized in that, The cutting section has a semiconductor transistor, and the temperature of the cutting section is the temperature of the semiconductor transistor.

4. The vehicle control device as described in claim 1, characterized in that, The priority level is adjusted based on the vehicle's driving environment and driving status.

5. The vehicle control device as described in claim 1, characterized in that, The cut-off portion has a semiconductor transistor and a shunt resistor connected to the semiconductor transistor.

6. The vehicle control device as claimed in claim 1, characterized in that, The drive control unit includes a first drive control unit that outputs drive commands, and a second drive control unit that controls and limits the operation of the plurality of load devices according to the drive commands from the first drive control unit. The vehicle control device includes: a main unit having the cut-off section, the current detection section, the temperature detection section and the first drive control section; and a sub-unit having the second drive control section.

7. The vehicle control device as claimed in claim 1, characterized in that, When the temperature of the cutting section exceeds a predetermined value, the drive control unit sets a time difference for the timing of starting and stopping the plurality of load devices based on the priority of the plurality of load devices, the reduction characteristics of the drive current when the plurality of load devices are started, and the current characteristics when the plurality of load devices are stopped.

8. The vehicle control device as claimed in claim 1, characterized in that, The drive control unit calculates the estimated start time of the load device with high priority in the future, and stops the load device with low priority before the estimated start time.

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