Vehicle control device

Abstract

To provide a vehicle control device that uses an electric motor as a power source, and is capable of detecting an actual decrease in the output of the electric motor and taking countermeasures.SOLUTION: A vehicle control device is configured to: when a torque difference ΔTmg between an instructed torque Tmgindi of an electric motor MG and an MG torque Tmg at a predetermined current value Ia is equal to or greater than a predetermined value ΔTlim, determine whether or not the output MG torque Tmg is equal to or more than a minimum guaranteed torque Tmgmin; and upon determining that it is equal to or more than the minimum guaranteed torque Tmgmin, correct a relationship between an instructed current Iindi and the instructed torque Tmgindi so as to take a countermeasure by correction, against the decrease in the output of the electric motor MG. Meanwhile, when the MG torque Tmg becomes less than the minimum guaranteed torque Tmgmin, a driver is notified that the correction cannot suppress output reduction of the electric motor MG, so that the driver can take appropriate measures.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control device for a vehicle powered by an electric motor. [Background technology]

[0002] Patent Document 1 describes that in order to detect abnormalities in an electric motor, inverter, etc., a first torque estimate calculated from an indicated current value is compared with a second torque estimate calculated from the actual current value actually supplied to the electric motor, and if the deviation between these values ​​exceeds a threshold value, the power supply to the electric motor is cut off. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-273500 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in Patent Document 1, since an abnormality is detected based on a value calculated from the command current value and the actual current value supplied to the motor, it is not possible to identify problems occurring in the motor, which poses a problem in that it is not possible to detect an actual decrease in motor output and take measures.

[0005] The present invention has been made against the background of the above circumstances, and its purpose is to provide a vehicle control device that can detect an actual decrease in the output of an electric motor in a vehicle powered by an electric motor and take appropriate measures. [Means for solving the problem]

[0006] The gist of the present invention is (a) Contains a permanent magnetA control device for a vehicle using an electric motor as a power source, wherein (b) a torque difference between an instruction torque of the electric motor when a predetermined current value is supplied to the electric motor and an actual torque actually output is for correcting the relationship of the indicated current to the indicated torque. If it is equal to or greater than a predetermined value and the actual torque of the electric motor when the predetermined current value is supplied to the electric motor is equal to or greater than a minimum guaranteed torque that is preset as a threshold value that can be addressed by correcting the relationship. When the torque is Relationship The relationship between the command current and the command torque is corrected using a torque correction control map for correcting the Torque compensation control is performed death, (c) The demagnetization of the motor becomes significant, The actual torque of the electric motor when the predetermined current value is supplied to the electric motor is The aforementioned If the torque is less than the preset minimum guaranteed torque, The torque correction control is not executed. The driver is notified of this. [Effects of the Invention]

[0007] According to the present invention, the torque difference between the command torque and the actual torque of the motor when a predetermined current value is supplied is for correcting the relationship of the indicated current to the indicated torque. If the actual torque is equal to or greater than the predetermined value, it is determined whether or not the actual torque is equal to or greater than the minimum guaranteed torque, and if the actual torque is equal to or greater than the minimum guaranteed torque, the relationship between the command current and the command torque is corrected, and the correction is used to take measures against the reduction in the output of the motor. When the demagnetization of the motor becomes significant, If the actual torque falls below the minimum guaranteed torque, The relationship between the indicated current and the indicated torque The driver is notified that the correction cannot suppress the reduction in the output of the electric motor, and the driver can take appropriate measures. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram illustrating a schematic configuration of an electric vehicle to which the present invention is applied, and is also a diagram for explaining a control system that controls the vehicle. [Figure 2] FIG. 10 is a diagram showing the relationship between the command torque and the MG torque with respect to the current supplied to the electric motor. [Figure 3] 4 is a flowchart for explaining the main control operations of the electronic control device. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios and shapes of the various parts are not necessarily drawn accurately. [Example]

[0010] FIG. 1 is a schematic diagram illustrating the general configuration of an electric vehicle 10 (hereinafter referred to as vehicle 10) to which the present invention is applied, and is also a diagram illustrating a control system that controls the vehicle 10. The vehicle 10 is equipped with an electric motor MG as a power source. The vehicle 10 also has a gearbox 16, a differential device 18, etc. on a power transmission path between the electric motor MG and drive wheels 12. The electric motor MG and gearbox 16 are housed in a case 19.

[0011] In the vehicle 10, the power of the electric motor MG is transmitted to the drive wheels 12 via a gearbox 16, a differential device 18, and the like.

[0012] The electric motor MG is connected to a battery 22 via an inverter 20. The inverter 20 is controlled by an electronic control device 40, which will be described later, to control the MG torque Tmg, which is the output torque of the electric motor MG.

[0013] The gear box 16 is a reduction gear mechanism that reduces the rotation speed of the electric motor MG. Oil discharged from an electric oil pump 28 driven by a pump motor 26, for example, is supplied to the electric motor MG and the gear box 16 as cooling oil or lubricating oil.

[0014] The vehicle 10 is equipped with an electronic control unit 40 that executes various controls including driving control. Various signals based on various sensors (42, 44, 46, 50, 52, 54, 56, 58, 60) are input to the electronic control unit 40. For example, signals representing the shift operation position Psh, the accelerator opening θacc, the brake signal Bon, the wheel speed Nr which is the rotational speed of the drive wheels 12 corresponding to the vehicle speed V, the vehicle acceleration G, the rotational angle θmg and the MG rotational speed Nmg of the electric motor MG, the current Img supplied to the electric motor MG, the battery temperature THbat of the battery 22, the battery charge / discharge current Ibat, the battery voltage Vbat, and the MG torque Tmg which is the actual torque of the electric motor MG are input.

[0015] The electronic control device 40 outputs various command signals to the devices provided in the vehicle 10. For example, an MG control command signal Sm for the electric motor MG, an oil pump control command signal Seop for the electric oil pump 28, etc. are output.

[0016] The electronic control device 40 functionally includes an electric motor control unit 80 that controls the electric motor MG, and a notification unit 82. The electric motor control unit 80 calculates the amount of drive demand of the vehicle 10 made by the driver (e.g., the required drive torque Trdem at the drive wheels 12) by applying, for example, the accelerator opening θacc and the vehicle speed V to a predetermined drive demand map. The electric motor control unit 80 outputs an MG control command signal Sm that controls the electric motor MG so as to realize the required drive torque Trdem, taking into consideration transmission loss, auxiliary load, gear ratio γg of the gearbox 16, etc. At this time, the electric motor control unit 80 determines the command current Iindi to be supplied to the electric motor MG based on a predetermined relationship between the command current Iindi of the electric motor MG and the command MG torque Tmgindi (command torque).

[0017] The electric motor MG includes a permanent magnet. For example, when demagnetization occurs, which reduces the magnetic flux of the permanent magnet, the actual torque (MG torque Tmg) of the electric motor MG may decrease relative to the commanded MG torque Tmgindi. To address this issue, the electric motor control unit 80 first calculates a torque difference ΔTmg (=|Tmgindi−Tmg|) between the commanded MG torque Tmgindi corresponding to a predetermined current value Ia and the actual torque (MG torque Tmg) actually output when a predetermined current value Ia is supplied to the electric motor MG, and determines whether the torque difference ΔTmg is equal to or greater than a predetermined value ΔTlim. The predetermined current value Ia is a predetermined value. The predetermined value ΔTlim is determined experimentally or by design and serves as a threshold value for determining whether to execute torque correction control (described later). The actual torque (MG torque Tmg) is detected at any time by, for example, a torque sensor 60 serving as a torque measurement unit.

[0018] If the torque difference ΔTmg is equal to or greater than the predetermined value ΔTlim, the motor control unit 80 further determines whether the MG torque Tmg, which is the actual torque when a predetermined current value Ia is supplied to the motor MG, is less than a preset minimum guaranteed torque Tmgmin. The minimum guaranteed torque Tmgmin is determined in advance experimentally or by design, and is set as a threshold value within a range where a reduction in the output of the motor MG can be addressed by correction.

[0019] When the MG torque Tmg is equal to or greater than the minimum guaranteed torque Tmgmin, the motor control unit 80 executes torque correction control to correct the relationship between the command current Iindi and the command MG torque Tmgindi. As a result, the life of the motor MG is extended. On the other hand, when the MG torque Tmg is less than the minimum guaranteed torque Tmgmin, the motor control unit 80 determines that the correction has reached its limit, and the notification unit 82 notifies the driver of this. Specifically, the notification unit 82 outputs a notification signal Sinfo to the sound device 62 or the in-vehicle display 64 to notify the driver that the correction has reached its limit.

[0020] Fig. 2 shows the relationship between the command current Iindi to the motor MG and the command MG torque Tmgindi and MG torque Tmg. Fig. 2(a) shows the relationship when the motor MG is normal, Fig. 2(b) shows the relationship when demagnetization occurs in the motor MG, and Fig. 2(c) shows the relationship when correction is at its limit.

[0021] When the electric motor MG is normal as shown in FIG. 2(a), the command MG torque Tmgindi indicated by the dashed line and the MG torque Tmg indicated by the solid line are approximately equal. On the other hand, when demagnetization occurs in the electric motor MG, a deviation occurs between the command MG torque Tmgindi and the MG torque Tmg, as shown in FIG. 2(b). In relation to this, at a predetermined current value Ia, the torque difference ΔTmg between the command MG torque Tmgindi and the MG torque Tmg becomes equal to or greater than a predetermined value ΔTlim. At this time, torque guarantee control is executed. FIG. 2(c) shows a case where correction is limited due to significant demagnetization. At this time, the command MG torque Tmgindi at the predetermined current value Ia becomes less than the minimum guaranteed torque Tmgmin, and a notification to the driver is required.

[0022] 3 is a flowchart for explaining the main control operations of the electronic control device 40, and is a flowchart for explaining the control operations that can take appropriate measures against a decrease in the MG torque Tmg of the electric motor MG. This flowchart is repeatedly executed while the vehicle is in operation.

[0023] First, in step S10 (hereinafter, "step" is omitted) corresponding to the control function of the motor control unit 80, it is determined whether the torque difference ΔTmg between the command MG torque Tmgindi and the MG torque Tmg when a predetermined current value Ia is supplied is equal to or greater than a predetermined value ΔTlim. If the determination in S10 is negative, this routine is terminated. If the determination in S10 is positive, it is determined in S20 corresponding to the control function of the motor control unit 80 whether the MG torque Tmg (actual torque) at the predetermined current value Ia is less than a minimum guaranteed torque Tmgmin. If the determination in S20 is positive, it is determined in S30 corresponding to the control function of the notification unit 82 that the correction limit has been reached, and this fact is notified to the driver via the sound device 62 or the in-vehicle display 64. If the determination in S20 is negative, torque correction control is executed in S40 corresponding to the control function of the motor control unit 80.

[0024] Torque correction control is control that corrects (updates) the relationship between the command current Iindi and the command MG torque Tmgindi of the electric motor MG to a new relationship. Torque correction control corrects the relationship using a torque correction control map. The torque correction control map is created by constantly storing the MG torque Tmg (actual torque) relative to the command current Iindi during traveling, as shown in S40 of FIG. 3. For example, if the command current Iindi is at a current value I1 and the MG torque Tmg is at a torque value T1, the current value I1 and the torque value T1 are stored in the torque correction control map. When torque correction control is performed, the relationship between the command current Iindi and the command torque Tmgindi is updated to a new one based on the torque correction control map. For example, the MG torque Tmg in the torque correction control map is replaced with the command torque Tmgindi to obtain a new relationship between the command current Iindi and the command torque Tmgindi.

[0025] As described above, according to this embodiment, when the torque difference ΔTmg between the command torque Tmgindi of the electric motor MG and the MG torque Tmg at a predetermined current value Ia is equal to or greater than a predetermined value ΔTlim, it is determined whether the MG torque Tmg is equal to or greater than the minimum guaranteed torque Tmgmin, and when the MG torque Tmg is equal to or greater than the minimum guaranteed torque Tmgmin, the relationship between the command current Iindi and the command torque Tmgindi is newly corrected, thereby taking corrective measures against the decrease in the output of the electric motor MG. Furthermore, when the MG torque Tmg falls below the minimum guaranteed torque Tmgmin, the driver is notified that the correction cannot suppress the decrease in the output of the electric motor MG, and appropriate measures, such as part replacement, can be taken.

[0026] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the present invention can also be applied to other embodiments.

[0027] For example, in the above-described embodiment, the vehicle 10 is an electric vehicle powered only by an electric motor MG. However, the present invention can also be applied to a hybrid vehicle powered by an engine and an electric motor. For example, the present invention may be applied to a hybrid vehicle including an engine, a first electric motor, a power distribution mechanism that distributes engine power to the first electric motor and an output shaft, and a second electric motor connected to the output shaft so as to be capable of transmitting power. Alternatively, the present invention may be applied to a hybrid vehicle including an engine, an electric motor, a clutch interposed between the engine and the electric motor, and a torque converter and an automatic transmission interposed between the electric motor and the drive wheels. However, the present invention may be applied to a hybrid vehicle of the above type that does not include a torque converter. Alternatively, the present invention may be applied to a hybrid vehicle including an engine, a belt-type continuously variable transmission interposed between the engine and the drive wheels, and an electric motor connected to a primary pulley or a secondary pulley of the continuously variable transmission so as to be capable of transmitting power. Alternatively, the vehicle may be a hybrid vehicle having an engine, a first electric motor connected to the engine so as to be able to transmit power, a second electric motor connected to the drive wheels so as to be able to transmit power, and a clutch and a gearbox interposed in the power transmission path between the first electric motor and the second electric motor.

[0028] In addition, in the above-described embodiment, the MG torque Tmg, which is the actual torque of the electric motor MG, is directly detected by the torque sensor 60, but the MG torque Tmg may also be calculated indirectly based on the angular acceleration αmg of the electric motor MG.

[0029] It should be noted that the above is merely one embodiment, and the present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art. [Explanation of symbols]

[0030] 10: Vehicle 40: Electronic control unit (control unit) MG: Electric motor

Claims

[Claim 1] A control device for a vehicle powered by an electric motor incorporating a permanent magnet, when a torque difference between a command torque of the electric motor when a predetermined current value is supplied to the electric motor and an actual torque actually output is equal to or greater than a predetermined value that is set in advance for correcting the relationship of the command current with respect to the command torque, and when the actual torque of the electric motor when the predetermined current value is supplied to the electric motor is equal to or greater than a minimum guaranteed torque that is set in advance as a threshold value that can be addressed by correcting the relationship, a torque correction control is executed to correct the relationship between the command current and the command torque using a torque correction control map for correcting the relationship of the command current with respect to the command torque, When the demagnetization of the motor becomes significant and the actual torque of the motor when the predetermined current value is supplied to the motor is less than the preset minimum guaranteed torque, the torque correction control is not executed and a driver is notified of this. A vehicle control device comprising:

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