Vehicle control system

Abstract

The present invention provides a vehicle control device that can further suppress the decrease in durability of switching elements when a single-phase lock condition occurs. [Solution] When a single-phase lock condition is detected, lock protection control is performed to limit the torque of the motor. This suppresses the decrease in the durability of the switching element when a single-phase lock condition occurs. When a single-phase lock condition is detected, if the current position is a designated parking lot, or if the vehicle's posture is in a tilt state other than horizontal or rearward tilt, torque output stop control is performed instead of lock protection control to stop the torque output of the motor. This allows for appropriate determination of vehicle conditions in which lock protection control is necessary, and reduces the torque output of the motor that is not meaningful due to lock protection control, i.e., unnecessary torque output, thereby reducing the opportunities for the switching element to overheat.

Description

Technical Field

[0001] The present invention relates to a control device for a vehicle equipped with a three-phase AC motor.

Background Art

[0002] A control device for a vehicle including a three-phase AC motor functioning as a driving power source and an inverter having a plurality of switching elements for driving the motor is well known. For example, the control device for a vehicle described in Patent Document 1 is such a device. In this Patent Document 1, when the determination conditions that the torque of the motor is equal to or greater than a predetermined torque and the rotational speed of the motor is equal to or less than a predetermined rotational speed are satisfied during a determination time, torque limit control for limiting the torque of the motor is performed to protect the switching elements from temperature rise due to the motor lock state. The motor lock state is synonymous with a single-phase lock state in which current concentrates in one phase of the motor. The torque limit control is synonymous with lock protection control.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The single-phase lock state occurs in a vehicle state where the tires cannot rotate, for example, when the vehicle cannot cross a step or when a tire falls into a groove. On the other hand, when the vehicle state where the tires cannot rotate cannot be escaped with the maximum torque of the motor, it is meaningless to continue outputting the limit torque in the lock protection control after detecting the occurrence of the single-phase lock state, and it is often impossible to escape. At this time, even in the lock protection control, heat generation of the switching elements is continued by the output of the limit torque, which may affect the durability of the switching elements.

[0005] The present invention was made against the above circumstances, and its objective is to provide a vehicle control device that can further suppress the decrease in durability of the switching element when a single-phase lock condition occurs. [Means for solving the problem]

[0006] The gist of the first invention is a control device for a vehicle comprising (a) a three-phase AC motor that functions as a power source for driving, and an inverter having a plurality of switching elements that drives the motor, the control device comprising (b) a lock state detection unit that detects the occurrence of a single-phase lock state in which current is concentrated in one phase of the motor, (c) a protection control unit that performs lock protection control to limit the torque of the motor when the occurrence of the single-phase lock state is detected, and (d) a unit that acquires vehicle position information indicating the current position of the vehicle and determines whether the current position is a predetermined parking lot based on the vehicle position information. (e) a vehicle position determination unit that determines the vehicle's position, and a posture determination unit that determines whether the vehicle's posture is in a horizontal state, a rearward tilted state, or a tilted state other than the rearward tilted state, and (f) when the occurrence of the single-phase lock state is detected, the protection control unit will, if it is determined that the current position is in the predetermined parking lot, or if it is determined that the vehicle's posture is in a tilted state other than the horizontal state or the rearward tilted state, execute a torque output stop control that stops the torque output of the electric motor instead of the lock protection control. [Effects of the Invention]

[0007] According to the first invention, when a single-phase lock condition is detected, lock protection control is performed to limit the torque of the electric motor. This suppresses the deterioration of the durability of the switching element when a single-phase lock condition occurs. When a single-phase lock condition is detected, if the current position is a predetermined parking lot, or if the vehicle's attitude is in a tilt state other than horizontal or rearward tilt, torque output stop control is performed instead of lock protection control to stop the torque output of the electric motor. This allows for appropriate determination of vehicle conditions in which lock protection control is necessary, and reduces the torque output of the electric motor that is meaningless under lock protection control, i.e., unnecessary torque output, thereby reducing the opportunities for the switching element to overheat. Therefore, when a single-phase lock condition occurs, the deterioration of the durability of the switching element can be further suppressed. [Brief explanation of the drawing]

[0008] [Figure 1] This figure illustrates an example of a vehicle to which the present invention is applied. (a) shows the general configuration of the vehicle. (b) shows the electrical configuration related to the control of the electric motor, etc., and also shows the main parts of the control system for various controls in the vehicle. [Figure 2] This flowchart explains the key aspects of the control operation of an electronic control device, and specifically describes the control operation to further suppress the decrease in durability of the switching element when a single-phase lock condition occurs. [Figure 3] This figure shows an example of a time chart when the control operations shown in the flowchart of Figure 2 are performed. (a) shows an example when lock protection control is performed. (b) shows an example when torque output stop control is performed. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [Examples]

[0010] Figure 1 illustrates an example of a vehicle 10 to which the present invention is applied. Figure 1(a) shows the schematic configuration of the vehicle 10. Figure 1(b) shows the electrical configuration related to the control of the electric motor MG, etc., and also shows the main parts of the control system for various controls in the vehicle 10.

[0011] In Figure 1(a), the vehicle 10 includes an electric motor MG that functions as a power source for driving, drive wheels 12, and a power transmission device 14 that transmits power from the electric motor MG to the drive wheels 12. The electric motor MG is a known rotating electric machine (a so-called motor generator).

[0012] In Figure 1(b), the vehicle 10 includes a high-voltage battery 20 and an inverter 30 connected to the high-voltage battery 20. The high-voltage battery 20 is a rechargeable DC power source and is a drive battery. The stored power from the high-voltage battery 20 is supplied to the electric motor MG via the inverter 30.

[0013] The inverter 30 includes a power module 32, a capacitor 34, and the like. The power module 32 includes switching elements 36 (36u, 36v, 36w), 38 (38u, 38v, 38w), and the like. The power module 32, using the switching elements 36, 38, etc., constitutes a three-phase bridge circuit for U-phase, V-phase, and W-phase. The switching elements 36 and 38 are, for example, transistors that convert DC current to three-phase AC current by being driven on and off. The inverter 30 has multiple switching elements 36 and 38 to drive the motor MG, which is a three-phase AC synchronous motor.

[0014] Vehicle 10 is equipped with a busbar 40 (40u, 40v, 40w), which is a power line that electrically connects the electric motor MG and the inverter 30. The busbar 40 consists of three power lines that carry three-phase alternating currents: U-phase, V-phase, and W-phase.

[0015] Vehicle 10 is equipped with an electronic control unit 50 as a controller. The electronic control unit 50 is composed of a so-called microcomputer, for example, which includes a CPU, RAM, ROM, input / output interface, etc. The electronic control unit 50 is the control unit of the present invention.

[0016] The electronic control unit 50 is supplied with various signals based on detection values ​​from various sensors installed in the vehicle 10. Examples of these sensors include the motor rotation speed sensor 70, vehicle speed sensor 72, accelerator pedal position sensor 74, current sensor 76, acceleration sensor 78, vehicle position sensor 80, and navigation system 82. Examples of these signals include the motor rotation speed Nmg, vehicle speed V, accelerator pedal position θacc, motor applied current Img, longitudinal acceleration Gx of the vehicle 10, lateral acceleration Gy of the vehicle 10, position information INFvp, and navigation information INFnavi.

[0017] The current sensor 76 includes, for example, current sensors corresponding to each of the U-phase, V-phase, and W-phase power lines. The motor applied current Img includes signals of current values ​​in each of the U-phase, V-phase, and W-phase power lines. The vehicle position sensor 80 includes a GPS (Global Positioning System) antenna, etc. The position information INFvp includes vehicle position information, which is information indicating the current position of the vehicle 10 on the ground or on a map based on GPS signals (orbital signals) transmitted by GPS satellites, etc. The navigation system 82 is a known navigation system. The navigation information INFnavi includes, for example, map information such as road information and facility information based on map data pre-stored in the navigation system 82.

[0018] From the electronic control device 50, various command signals and the like are output to each device and the like provided in the vehicle 10. Each device and the like are, for example, the inverter 30, the information notification device 84, and the like. The various command signals and the like are, for example, the motor control command signal Smg for controlling the motor MG, the information notification control command signal Sinf for notifying the driver of various information, and the like. The information notification device 84 is a device that notifies the driver of various information. The information notification device 84 is, for example, a display device such as a monitor, and / or a sound output device such as a speaker.

[0019] The electronic control device 50 includes a drive control unit 52, a lock state detection unit 54, and a protection control unit 56 in order to realize various controls in the vehicle 10.

[0020] The drive control unit 52 calculates a required drive torque Twdem as a required value of the drive torque Tw by applying the accelerator opening θacc and the vehicle speed V to a predetermined drive requirement amount map, for example. The drive control unit 52 outputs a motor control command signal Smg for controlling the motor MG so that a motor torque Tmg for realizing the required drive torque Twdem can be obtained.

[0021] When a single-phase lock state occurs in which current concentrates in one phase of the motor MG due to the motor MG being locked (rotationally fixed), there is a concern that the temperatures of the switching elements 36 and 38 will rise and the durability of the switching elements 36 and 38 will decrease. As a countermeasure against this, a method of suppressing the motor applied current Img can be considered.

[0022] The lock state detection unit 54 detects the occurrence of a single-phase lock state. For example, the lock state detection unit 54 detects the current concentration in one phase of the motor MG based on the signal value of the motor applied current Img by the current sensor 76. When the state where the motor applied current Img in one phase of the motor MG becomes equal to or greater than a predetermined current value Imgf continues for more than a predetermined time TMf, the lock state detection unit 54 detects the current concentration in one phase of the motor MG and sets the current concentration determination flag to the on state. The lock state detection unit 54 determines whether the occurrence of the single-phase lock state is detected based on whether the current concentration in one phase of the motor MG is detected. The predetermined current value Imgf and the predetermined time TMf are respectively predetermined threshold values for determining the current concentration in one phase of the motor MG. Since the motor applied current Img and the motor torque Tmg are in a proportional relationship, the predetermined current value Imgf corresponds to a predetermined current concentration determination torque Tmgf for determining the current concentration in one phase of the motor MG.

[0023] When it is determined by the lock state detection unit 54 that the occurrence of the single-phase lock state is detected, the protection control unit 56 executes lock protection control to limit the motor torque Tmg. The lock protection control is a control that limits the motor torque Tmg to a constant torque and continues the output of the motor torque Tmg after the detection of the single-phase lock state. That is, the lock protection control is a control that limits the motor applied current Img when the motor applied current Img concentrates in one phase of the motor MG and suppresses the temperature rise of the switching elements 36 and 38 due to the motor applied current Img. In the lock protection control, the protection control unit 56 limits the motor torque Tmg with the current concentration determination torque Tmgf, that is, reduces it to the current concentration determination torque Tmgf. That is, in the lock protection control, the protection control unit 56 limits the motor applied current Img with the predetermined current value Imgf, that is, reduces it to the predetermined current value Imgf.

[0024] In lock protection control, a constant motor torque Tmg is output, meaning a constant motor current Img flows, so it is not possible to completely eliminate the heat generated by the switching elements 36 and 38. Alternatively, if the execution and non-execution of lock protection control are repeated, there is a period of time when the maximum torque of the motor torque Tmg is output, so the thermal load on the switching elements 36 and 38 continues. Depending on the vehicle condition when the motor MG locks, even if the motor MG continues to output maximum torque, the situation may not improve (the motor MG may not be able to escape the lock), and in that case, the thermal load will also continue. The motor MG locks when the vehicle is in a condition where the tires cannot rotate, such as when the vehicle 10 cannot get over a step or when the tires fall into a ditch. On the other hand, if the vehicle is in a condition where the tires cannot rotate and cannot escape with the maximum torque of the motor MG, it is often meaningless to continue outputting the limiting torque in the lock protection control after the motor MG locks, and it is not possible to escape. In this case, the heat generated by the switching elements 36 and 38 continues, which may affect the durability of the switching elements 36 and 38.

[0025] The aforementioned problems are thought to arise because the execution of lock protection control is determined solely by whether or not a single-phase lock condition is detected, and the vehicle state at the time of motor MG lock is unknown. The electronic control unit 50 takes into account the vehicle state at the time of motor MG lock and outputs an appropriate motor torque Tmg at the time of lock, thereby performing torque control that reduces the frequency of repeating between maximum torque and lock protection control.

[0026] The electronic control unit 50 further includes a vehicle position determination unit 58 and a vehicle attitude determination unit 60 in order to determine the vehicle state when the electric motor MG is locked.

[0027] The vehicle position determination unit 58 acquires the vehicle position information contained in the location information INFvp and determines whether the vehicle 10 is stopped in a predetermined parking lot based on that vehicle position information. In other words, the vehicle position determination unit 58 determines whether the vehicle position, as the current location of the vehicle 10, is in a predetermined parking lot based on the vehicle position information. The vehicle position is the location where the vehicle 10 is located. The predetermined parking lot is a predetermined parking lot that can be obtained from parking information such as map information contained in the navigation information INFnavi.

[0028] If the vehicle is located in a designated parking area, it can be determined that the motor (MG) has locked up due to, for example, a step or uneven surface. On the other hand, if the vehicle is located outside of a designated parking area, it can be determined that the motor (MG) has locked up due to, for example, being on a roadway.

[0029] The posture determination unit 60 determines whether the posture of the vehicle 10 is horizontal, tilted backward, or tilted in any other way. The posture determination unit 60 determines the posture of the vehicle 10 based, for example, on the signal values ​​of longitudinal acceleration Gx and lateral acceleration Gy from the acceleration sensor 78. Tilting conditions other than the rearward tilt may include, for example, a forward tilt, as well as a state where the left side is lowered or the right side is lowered.

[0030] If the vehicle 10 is in a horizontal position or any other tilted position other than a rearward tilted position, it can be determined that the electric motor MG has locked up due to, for example, a step, similar to the case where the vehicle is in a designated parking lot. On the other hand, if the vehicle 10 is in a rearward tilted position, it can be determined that the electric motor MG has locked up due to the balance between, for example, the force of sliding down a slope and the driving force Fw due to the electric motor torque Tmg.

[0031] When the protection control unit 56 determines that a single-phase lock condition has occurred, and the vehicle position determination unit 58 determines that the vehicle position is not in a designated parking area, and the attitude determination unit 60 determines that the vehicle 10 is tilted backward, the protection control unit 56 executes lock protection control. The protection control unit 56 continues to output the motor torque Tmg after torque limiting due to the lock protection control.

[0032] When the protection control unit 56 determines that a single-phase lock condition has occurred, as detected by the lock condition detection unit 54, and the vehicle position determination unit 58 determines that the vehicle is in a designated parking lot, the protection control unit 56 executes torque output stop control instead of lock protection control. Torque output stop control is a control that stops the output of the motor torque Tmg. Alternatively, when the protection control unit 56 determines that a single-phase lock condition has occurred, as detected by the lock condition detection unit 54, and the attitude determination unit 60 determines that the attitude of the vehicle 10 is in an inclined state other than horizontal or rearward tilt, the protection control unit 56 executes torque output stop control instead of lock protection control. The protection control unit 56 executes torque output stop control by outputting a command to the drive control unit 52 to gradually reduce the motor torque Tmg so that it becomes zero.

[0033] If the driver understands the vehicle's condition requiring torque output stop control, it is less likely to cause discomfort. The electronic control unit 50 is further equipped with a notification unit 62.

[0034] When torque output stop control is executed by the protection control unit 56, the notification unit 62 outputs an information notification control command signal Sinf to notify that the vehicle is in a state where torque output stop control needs to be executed. For example, the notification unit 62 displays on the information notification device 84 or outputs an audio message from the information notification device 84 indicating that the vehicle is in a state where the drive torque Tw is stopped.

[0035] Figure 2 is a flowchart illustrating the main part of the control operation of the electronic control device 50, and is a flowchart illustrating the control operation to further suppress the decrease in durability of the switching elements 36 and 38 when a single-phase lock condition occurs, and is, for example, executed repeatedly.

[0036] In Figure 2, first, in step S10, which corresponds to the function of the lock state detection unit 54 (the step is omitted hereafter), it is determined whether or not the occurrence of a single-phase lock state has been detected. If the determination in S10 is negative, this routine is terminated. If the determination in S10 is positive, the vehicle position is determined in S20, which corresponds to the function of the vehicle position determination unit 58. If the determination in S20 determines that the vehicle position is not in a designated parking lot, the attitude of the vehicle 10 is determined in S30, which corresponds to the function of the attitude determination unit 60. If the determination in S30 determines that the attitude of the vehicle 10 is tilted backward, lock protection control is executed in S40, which corresponds to the function of the protection control unit 56. Following S40, this routine is terminated. If the determination in S20 above determines that the vehicle is in a designated parking lot, or if the determination in S30 above determines that the vehicle 10 is in a tilted state other than horizontal or rearward tilted, the vehicle status is notified to the driver in S50, which corresponds to the functions of the protection control unit 56 and the notification unit 62, and torque output stop control is executed. Following S50, this routine is terminated.

[0037] Figure 3 shows an example of a time chart when the control operation shown in the flowchart of Figure 2 is performed. Figure 3(a) shows an example when lock protection control is performed. Figure 3(b) shows an example when torque output stop control is performed. In Figure 3(a), when the current concentration judgment flag is turned on, lock protection control is started (see time t1a), and the motor torque Tmg is reduced to the current concentration judgment torque Tmgf (see time t1a-t2a). When the motor torque Tmg is reduced to less than the current concentration judgment torque Tmgf, the lock protection control is terminated (see time t2a). Figure 3(a) shows a state in which lock protection control is repeatedly executed (see time t3a and t4a). In Figure 3(b), when the current concentration determination flag is turned ON, if the vehicle is in a designated parking lot, or if the vehicle 10 is in a tilt state other than horizontal or rearward tilt, torque output stop control is initiated (see time t1b), and the motor torque Tmg is reduced to zero, as shown by the solid line (see time t1b onwards). The dashed line indicates the case when lock protection control is performed.

[0038] As described above, according to this embodiment, when a single-phase lock condition is detected, lock protection control is executed. This makes it possible to suppress the decrease in durability of the switching elements 36 and 38 when a single-phase lock condition occurs. When a single-phase lock condition is detected, if the vehicle is in a predetermined parking lot, or if the vehicle 10 is in a tilted state other than horizontal or rearward tilted, torque output stop control is executed instead of lock protection control. This makes it possible to appropriately determine the vehicle condition in which lock protection control is necessary, and by reducing the torque output of the electric motor MG that is not relevant to lock protection control, i.e., unnecessary torque output, the opportunities for the switching elements 36 and 38 to overheat can be reduced. Therefore, when a single-phase lock condition occurs, the decrease in durability of the switching elements 36 and 38 can be further suppressed.

[0039] Suppressing the deterioration of the durability of the switching elements 36 and 38 leads to extending the lifespan of the switching elements 36 and 38. In other words, by reducing unnecessary heat generation from the switching elements 36 and 38, the thermal stress on the switching elements 36 and 38 can be reduced, thus extending the lifespan of the switching elements 36 and 38.

[0040] Furthermore, according to this embodiment, when torque output stop control is performed, the vehicle status is notified to the driver, so the driver can understand the situation.

[0041] In the case of an electric vehicle (HEV, BEV, etc.) that is equipped with the various sensors of this embodiment and has a lock protection control function, and is driven by a three-phase AC motor, it is not necessary to install any new components.

[0042] Although embodiments of the present invention have been described in detail above with reference to the drawings, the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art. [Explanation of Symbols]

[0043] 10: Vehicle 30: Inverter 36 (36u, 36v, 36w): Switching element 38 (38u, 38v, 38w): Switching element 50: Electronic control unit (control unit) 54: Lock state detection unit 56: Protection control unit 58: Vehicle position determination unit 60: Attitude determination unit MG: Electric motor

Claims

[Claim 1] A control device for a vehicle comprising a three-phase AC motor that functions as a power source for propulsion, and an inverter having a plurality of switching elements that drives the motor, A lock state detection unit that detects the occurrence of a single-phase lock state, which is a state in which current is concentrated in one phase of the aforementioned electric motor, When the occurrence of the single-phase lock condition is detected, a protection control unit performs lock protection control to limit the torque of the electric motor, A vehicle location determination unit acquires vehicle location information indicating the current location of the vehicle and determines whether the current location is a predetermined parking lot based on the vehicle location information. A posture determination unit that determines whether the vehicle's posture is horizontal, tilted backward, or tilted in any other way than the aforementioned tilted backward, It includes, A vehicle control device characterized in that, when the occurrence of the single-phase lock state is detected, if the current position is determined to be the predetermined parking lot, or if the vehicle's posture is determined to be in an inclined state other than the horizontal state or the rearward tilt state, the protection control unit performs torque output stop control, which stops the torque output of the electric motor, instead of the lock protection control.

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