Vehicle control system
The vehicle control device addresses sudden deceleration risks by calculating deceleration torque and selectively performing SMR cutoff control, ensuring safe driving without reducing evacuation opportunities.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2023-02-13
- Publication Date
- 2026-05-19
AI Technical Summary
Existing vehicle control systems that block the SMR circuit during motor abnormalities can prevent back electromotive current from flowing into the battery, but this approach reduces the opportunity for evacuation driving by causing sudden deceleration, increasing the risk of rear-end collisions.
A vehicle control device that includes a processor to detect motor abnormalities and calculates the estimated deceleration torque; it only performs SMR cutoff control when the deceleration torque exceeds a predetermined value, otherwise, it maintains the SMR circuit connection to prevent sudden deceleration.
The solution effectively suppresses sudden deceleration during motor malfunctions while maintaining the opportunity for safe driving by selectively performing SMR cutoff control based on deceleration torque calculations.
Smart Images
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Abstract
Description
Technical Field
[0001] The present disclosure relates to a control device for a vehicle.
Background Art
[0002] Patent Document 1 discloses a technique for immediately shutting off an SMR (System Main Relay) circuit in order to suppress the flow of a back electromotive voltage into a battery when an abnormality of a motor is determined.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] Blocking the SMR circuit when a back electromotive current occurs, as in the technique disclosed in Patent Document 1, is effective in that the back electromotive current does not flow into the battery. If the SMR circuit is not blocked, deceleration torque (back electromotive torque) may occur in some cases, and there is a risk of a rear-end collision due to sudden deceleration. Therefore, it is desired to adopt blocking of the SMR circuit as a means for suppressing this, but if the SMR circuit is always blocked during an abnormality, there is a contradiction in that the opportunity for evacuation driving is reduced.
[0005] The present disclosure has been made in view of the above, and an object thereof is to provide a vehicle control device capable of suppressing sudden deceleration during an abnormality of a motor without reducing the opportunity for evacuation driving.
Means for Solving the Problems
[0006] The vehicle control device according to this disclosure includes a processor, which, when detecting an abnormality in the motor, performs SMR cutoff control to cut off an SMR circuit provided between the battery and the motor, calculates the deceleration torque that is estimated to be generated when the SMR cutoff control is performed, and if the calculated deceleration torque is less than a predetermined value, does not perform the SMR cutoff control. [Effects of the Invention]
[0007] According to this disclosure, it is possible to suppress sudden deceleration in the event of a motor malfunction without reducing the opportunity for safe running. [Brief explanation of the drawing]
[0008] [Figure 1] Figure 1 shows an example of control using a conventional vehicle control device. [Figure 2] Figure 2 is a time chart showing an example of control by a conventional vehicle control system. [Figure 3] Figure 3 is a flowchart showing an example of the control flow by a conventional vehicle control system. [Figure 4] Figure 4 shows an example of control by the vehicle control device according to this embodiment. [Figure 5] Figure 5 is a time chart showing an example of control by the vehicle control device according to this embodiment. [Figure 6] Figure 6 is a flowchart showing the flow of the vehicle control method 1 executed by the vehicle control device according to the embodiment. [Figure 7] Figure 7 is a flowchart showing the flow of the vehicle control method 2 executed by the vehicle control device according to the embodiment. [Modes for carrying out the invention]
[0009] A vehicle control device according to the embodiments of this disclosure will be described with reference to the drawings. Note that some of the components in the embodiments described below are substituted or substantially identical to those that can be easily replaced by a person skilled in the art.
[0010] First, before describing the vehicle control device according to this embodiment, we will explain the control using a conventional vehicle control device with reference to Figures 1 to 3.
[0011] In a vehicle (electric vehicle) like the one shown in Figure 1, if, for example, an abnormality in motor 1 (or a failure of MG-ECU 7) is detected (see (1) in Figures 1 and 2), the driving force of motor 1 is cut off. After the driving force of motor 1 is cut off, motor 1 is rotated by the wheels 6, generating a back electromotive force. When "battery voltage < back electromotive force", a back electromotive force torque (deceleration torque) is generated due to the back electromotive force current (see (2) in the same figure). If the SMR circuit 4 remains connected at that time (see (3) in the same figure), the negative torque will continue (see (4) in the same figure). As a result, the vehicle will decelerate rapidly, creating a risk of rear-end collision. Note that "ASIL-A" in Figure 2 means "Automotive Safety Integrity Level A".
[0012] Figure 3 is a flowchart showing the control flow by a conventional vehicle control device. As shown in the figure, if an abnormality is detected while the vehicle is running (Yes in step S1), the driving force of motor 1 is cut off (step S2), and the vehicle continues to run (step S3). If the vehicle continues to run with the driving force of motor 1 cut off, as in step S3, depending on the vehicle speed, a sudden deceleration may occur due to the deceleration torque.
[0013] Therefore, in the vehicle control device according to this embodiment, the deceleration torque is suppressed by shutting off the SMR circuit 40 when an abnormality is detected. The vehicle control device according to this embodiment will be described below with reference to Figures 4 to 7.
[0014] (Vehicle control system) The vehicle control device according to the embodiment is realized by a vehicle as shown in FIG. 4. The vehicle in the figure includes a motor 1, an inverter 2, a battery 3, a SMR circuit 4, a transaxle 5, a pair of wheels 6, and a MG-ECU 7. Examples of the vehicle according to the embodiment include a plug-in hybrid electric vehicle (PHEV) and a battery electric vehicle (BEV).
[0015] The motor 1 is, for example, an AC synchronous motor and functions as an electric motor and a generator. When the motor 1 functions as an electric motor, it is driven using the electric power stored in the battery 3 as a power source. On the other hand, when the vehicle decelerates, etc., the motor 1 is driven by the rotation of the wheels 6. As a result, the motor 1 functions as a generator and generates regenerative power.
[0016] The inverter 2 converts the DC power supplied from the battery 3 into AC power and supplies the AC power to the motor 1. On the other hand, the inverter 2 converts the AC power (regenerative power) generated by the motor 1 into DC power and supplies the DC power to the battery 3.
[0017] The battery 3 is a rechargeable secondary battery and is composed of, for example, a lithium-ion battery, a nickel-hydrogen battery, etc. The battery 3 stores the electric power necessary for the vehicle to travel (for example, the driving power of the motor 1). Also, when the regenerative power generated by the motor 1 is supplied to the battery 3, the battery 3 is charged.
[0018] The SMR circuit 4 is provided between the battery 3 and the motor 1 and includes a plurality of SMRs 41. The MG-ECU 7 is an electronic control unit that controls the motor 1. The MG-ECU 7 is an electronic control unit (Electronic Control Unit: ECU) mainly composed of a microcomputer including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc., and executes various programs. The MG-ECU 7 realizes a function that matches a predetermined purpose by controlling each component and the like through the execution of the above programs.
[0019] For example, when an abnormality of the motor 1 is detected, the MG-ECU 7 performs SMR cutoff control to cut off the SMR circuit 4. Also, when performing this SMR cutoff control, the MG-ECU 7 calculates the deceleration torque that is estimated to occur when the SMR cutoff control is performed. Then, when the calculated deceleration torque is equal to or greater than a predetermined value, the MG-ECU 7 performs the SMR cutoff control, and when the calculated deceleration torque is less than the predetermined value, the MG-ECU 7 does not perform the SMR cutoff control. Further, when the calculated deceleration torque is equal to or greater than the predetermined value, and when the vehicle speed is less than the predetermined value when the SMR cutoff control is performed, the MG-ECU 7 reconnects the SMR circuit 4.
[0020] The control by the control device of the vehicle according to the embodiment will be described while referring to FIGS. 4 and 5.
[0021] In a vehicle (electric vehicle) as shown in FIG. 4, for example, when an abnormality of the motor 1 (or a failure of the MG-ECU 7) is detected (see (1) in FIGS. 4 and 5), the driving force of the motor 1 is cut off. After the driving force of the motor 1 is cut off, since the motor 1 is rotated by the wheels 6, a reverse electromotive voltage is generated. Then, when "battery voltage < reverse electromotive voltage", a reverse torque (deceleration torque) is generated (see (2) in the same figure). So far, it is the same as the conventional control.
[0022] On the other hand, in the vehicle control device according to the embodiment, when a back EMF torque is generated, the inverter 2 is shut off, thereby shutting off the SMR circuit 4 (see Figures 4 and 5 (3)). This makes the "back EMF torque = 0" (see Figure 5 (4)). As a result, the negative torque does not continue, and the rapid deceleration does not continue, so the vehicle decelerates gradually and the risk of rear-end collision is eliminated.
[0023] (Vehicle control method 1) The flow of the vehicle control method 1 executed by the vehicle control device according to the embodiment will be explained with reference to Figure 6. The control shown in the figure is mainly performed by the MG-ECU7.
[0024] First, the MG-ECU7 determines whether or not it has detected an abnormality (for example, a malfunction of motor 1 or the MG-ECU7) while the vehicle is running (step S11). If it determines in step S11 that an abnormality has been detected (Yes in step S11), the MG-ECU7 cuts off the driving force of motor 1 (step S12).
[0025] Next, the MG-ECU7 determines whether the estimated deceleration torque is less than a predetermined value (step S13). The "estimated deceleration torque" can be calculated based on, for example, the vehicle speed and the power supplied to the motor 1 (battery voltage, current value).
[0026] In step S13, if it is determined that the estimated deceleration torque is less than a predetermined value (Yes in step S13), the MG-ECU7 continues to operate the vehicle without shutting off the SMR circuit 4 (step S14), and completes this process.
[0027] On the other hand, if in step S13 it is determined that the estimated deceleration torque is not less than a predetermined value (i.e., greater than or equal to a predetermined value) (No in step S13), the MG-ECU7 shuts off the inverter 2, thereby shutting off the SMR circuit 4 (step S15), ending the vehicle's operation (step S16), and completing this process. If in step S11 it is determined that no abnormality has been detected (No in step S11), the MG-ECU7 completes this process.
[0028] Thus, in vehicle control method 1, when an abnormality in motor 1 is detected, the SMR circuit 4 is shut off to suppress the sudden deceleration of the vehicle due to the deceleration torque. Furthermore, by shutting off the SMR circuit 4 only when the estimated deceleration torque is large, the number of vehicle driving scenarios in the event of an abnormality is increased.
[0029] (Vehicle control method 2) The flow of the vehicle control method 2 executed by the vehicle control device according to the embodiment will be explained with reference to Figure 7. The control shown in the figure is mainly performed by the MG-ECU7.
[0030] First, the MG-ECU7 determines whether or not it has detected an abnormality (for example, a malfunction of motor 1 or the MG-ECU7) while the vehicle is running (step S21). If it determines in step S21 that an abnormality has been detected (Yes in step S21), the MG-ECU7 cuts off the driving force of motor 1 (step S22).
[0031] Next, the MG-ECU7 shuts off the SMR circuit 4 by shutting off the inverter 2 (step S23). Subsequently, the MG-ECU7 determines whether or not the vehicle speed is below a predetermined value (step S24).
[0032] In step S24, if it is determined that the vehicle speed is below a predetermined value (Yes in step S24), the MG-ECU7 reconnects the SMR circuit 4 (step S25), continues driving the vehicle (step S26), and completes this process.
[0033] On the other hand, if in step S24 it is determined that the vehicle speed is not below a predetermined value (i.e., above a predetermined value) (No in step S24), the MG-ECU7 returns to the process in step S24. If in step S21 it is determined that no abnormality is detected (No in step S21), the MG-ECU7 completes this process.
[0034] Thus, in vehicle control method 2, when an abnormality in motor 1 is detected, the SMR circuit 4 is shut off to suppress the sudden deceleration of the vehicle due to the deceleration torque. Furthermore, in scenes where it is not expected that deceleration torque will be generated after the SMR circuit 4 is shut off (low vehicle speed scenes), the SMR circuit 4 is reconnected.
[0035] In the vehicle control device according to the embodiment described above, SMR shut-off control is performed only when the estimated deceleration torque of the vehicle is equal to or greater than a predetermined value, and SMR shut-off control is not performed when the estimated deceleration torque is less than the predetermined value. In this way, the vehicle control device according to the embodiment does not shut off the SMR circuit 4 in scenes where no deceleration torque is generated, thereby increasing the number of scenes in which evasive driving is possible.
[0036] Furthermore, in the vehicle control device according to the embodiment, if SMR disconnection control is performed and the vehicle speed is below a predetermined value, the SMR circuit 4 is reconnected. In this way, even if the SMR circuit 4 is disconnected due to a large deceleration torque, the vehicle control device according to the embodiment will attempt to reconnect the SMR circuit 4 in scenes where the deceleration torque that occurs afterward is expected to be small (i.e., low vehicle speed). As a result, an opportunity to resume driving can be created.
[0037] As described above, the vehicle control device according to the embodiment can suppress sudden deceleration in the event of a motor 1 malfunction without reducing the opportunity for evasive driving.
[0038] Further effects and modifications can be readily derived by those skilled in the art. Therefore, broader aspects of the present invention are not limited to the specific details and representative embodiments expressed and described above. Accordingly, various modifications are possible without departing from the spirit or scope of the overall concept of the invention as defined by the appended claims and their equivalents. [Explanation of symbols]
[0039] 1 motor 2 Inverter (INV) 3 Batteries 4 SMR circuit 41 SMR 5 Transaxle (T / A) 6 wheels 7 MG-ECU
Claims
1. Equipped with a processor, The aforementioned processor, When an abnormality is detected in the motor that drives the vehicle, SMR cutoff control is performed to shut off the SMR circuit installed between the battery and the motor. During the SMR cutoff control, the deceleration torque estimated to be generated when the SMR cutoff control is performed is calculated. If the calculated deceleration torque is less than a predetermined value, the SMR cutoff control will not be performed. Vehicle control system.
2. When the processor performs the SMR cutoff control because the calculated deceleration torque is equal to or greater than the predetermined value, if the vehicle speed is less than the predetermined value, it reconnects the SMR circuit. A vehicle control device according to claim 1.