JP2016111755A - Automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit electric charge of a capacitor from becoming unable to be quickly discharged when a motor stops rotation after a collision of a vehicle.SOLUTION: When a motor rotates (S110) after detection of a collision of a vehicle, three-phase switch control is executed (S130) to turn on all upper arms or all lower arms among plural transistors of an inverter. When the motor stops rotation (S110), discharge control is executed (S160) for switching the plural transistors to allow a d-axis current to flow in the motor. In an automobile conducting such control, when it is determined during rotation of the motor that a drive shaft is connected to the rotating shaft of the motor, the three phase switch control is stopped (prohibited) (S140).SELECTED DRAWING: Figure 2

Description

  The present invention relates to an automobile, and more particularly to an automobile including a motor, an inverter, and a capacitor.

  Conventionally, as this type of automobile, an automobile including a motor, an inverter, and a capacitor has been proposed (for example, see Patent Document 1). The motor is configured as a three-phase AC motor, and a rotating shaft is coupled to the axle. The inverter has six transistors composed of three upper arm transistors and three lower arm transistors, and six diodes connected in parallel in opposite directions to each of the six transistors, and switching of the six transistors To drive the motor. The capacitor is connected to the positive and negative buses of the power line to which the inverter is connected.

  In this automobile, when the number of rotations of the motor is equal to or higher than a predetermined number of times after the collision of the vehicle is detected, the three-phase on that turns on one of the three upper arm transistors and the three lower arm transistors of the inverter. Execute control. Here, when three upper arm transistors are turned on, it is referred to as upper arm three-phase on control, and when three lower arm transistors are turned on, it is referred to as lower arm three-phase on control. By executing this three-phase ON control, the motor is caused to generate torque in a direction to stop its rotation speed, thereby reducing the rotation of the motor. Then, the upper arm three-phase on control and the lower arm three-phase on control are switched every predetermined time. As a result, the current is prevented from continuing to flow through only one of the three upper arm transistors and the three lower arm transistors, and at least a part of the six transistors is prevented from being overheated. When the rotational speed of the motor is less than the predetermined rotational speed, discharge control is performed to control the six transistors so that d-axis current flows through the motor. Thereby, the electric charge of the capacitor is discharged.

JP2013-55822A

  In such an automobile, the vehicle may bounce or slide down on a slope after the collision of the vehicle, and the rotation of the axle may continue for a certain period of time. When the connection between the rotating shaft of the motor and the axle is not released (is still connected), the motor also rotates according to the rotation of the axle. In this case, even if the three-phase on control is executed, the rotation of the motor cannot be stopped, and the execution time of the three-phase on control may become long. When the execution time of the three-phase on control becomes longer, the temperature of the inverter rises. For this reason, when the discharge control is executed after the motor stops rotating, the inverter temperature reaches the drive limit temperature (the temperature at which the inverter is shut down to protect the inverter). In some cases, the battery cannot be discharged quickly.

  The main purpose of the automobile of the present invention is to prevent the capacitor from being quickly discharged when the motor stops rotating after a vehicle collision.

  The automobile of the present invention has taken the following means in order to achieve the main object described above.

The automobile of the present invention
A three-phase AC motor connected to the axle;
An inverter that drives the motor by switching of a plurality of switching elements;
A capacitor for smoothing the voltage between the terminals of the inverter;
After the vehicle collision is detected, when the motor is rotating, three-phase on control is performed to control the inverter so that all of the upper arms or all of the lower arms of the plurality of switching elements are turned on. And, when the rotation of the motor stops, a control means for performing discharge control for controlling the inverter so that the electric charge of the capacitor is discharged by passing a d-axis current to the motor;
A car equipped with
The control means prohibits execution of the three-phase on control when it is determined that the motor and the axle are connected when the motor is rotating after detection of a vehicle collision,
It is characterized by that.

  In the automobile of the present invention, when the motor is rotating after detecting the collision of the vehicle, the three-phase for controlling the inverter so that all of the upper arms or all of the lower arms among the plurality of switching elements are turned on. Perform on-control. As a result, it is possible to stop the rotation of the motor by generating a torque in the direction in which the rotational speed of the motor is reduced (a drag torque). Then, when the rotation of the motor stops, discharge control is performed to control the inverter so that the electric charge of the capacitor is discharged by passing a d-axis current through the motor. When the motor stops rotating, no back electromotive force is generated in the motor. By executing the discharge control, the electric charge of the capacitor can be discharged without outputting torque from the motor. In such a control, when it is determined that the motor and the axle are connected when the motor is rotating after the collision of the vehicle is detected, the execution of the three-phase on control is prohibited. When the motor and the axle are connected, the motor continues to rotate as the vehicle continues to rotate. Therefore, by prohibiting the execution of the three-phase on control, it is possible to suppress an increase in the temperature of the inverter due to a long execution time of the three-phase on control. Thereby, when performing discharge control, it can suppress that the temperature of an inverter reaches more than drive limit temperature. Here, the “drive limit temperature” may be a temperature at which the inverter is shut down in order to suppress overheating of the inverter. As a result, it is possible to suppress the discharge control from being stopped. That is, it is possible to prevent the capacitor from being quickly discharged when the motor stops rotating after a vehicle collision.

  In such an automobile of the present invention, the control means may determine that the motor and the axle are connected when the execution time of the three-phase on control reaches a predetermined time or more.

  Further, in the automobile of the present invention, the difference between the first calculated vehicle speed calculated based on the wheel speed of the wheel to which the axle is attached, and the second calculated vehicle speed calculated based on the rotational speed of the motor. It is good also as what determines with the said motor and the said axle shaft being connected when is below a threshold value.

  Furthermore, the automobile of the present invention includes a battery capable of exchanging electric power with the inverter, and a relay that connects and disconnects the inverter, the capacitor, and the battery, and the control means includes a vehicle collision When this is detected, the relay may be controlled so that the connection between the inverter and the capacitor and the battery is released.

It is a block diagram which shows the outline of a structure of the electric vehicle 20 as one Example of this invention. It is a flowchart which shows an example of the control routine after a collision performed by ECU50 of an Example.

  Next, the form for implementing this invention is demonstrated using an Example.

  FIG. 1 is a configuration diagram showing an outline of a configuration of an electric vehicle 20 as an embodiment of the present invention. As illustrated, the electric vehicle 20 of the embodiment includes a motor 32, an inverter 34, a battery 36, a relay 42, a capacitor 44, a cooling device 70, an electronic control unit (hereinafter referred to as ECU) 50, Is provided.

  The motor 32 is configured as a known synchronous generator motor having a rotor in which a permanent magnet is embedded and a stator around which a three-phase coil is wound. The motor 32 is connected to a drive shaft 26 connected to the drive wheels 22 a and 22 b via a drive shaft (axle) 23 and a differential gear 24. The motor 32 generates a counter electromotive voltage as it rotates.

  The inverter 34 is connected to the battery 36 by the power line 40. The inverter 34 includes six transistors T11 to T16 and six diodes D11 to D16. Two transistors T11 to T16 are arranged in pairs so as to be on the source side and the sink side with respect to the positive electrode bus 40a and the negative electrode bus 40b of the power line 40, respectively. The six diodes D11 to D16 are respectively connected in parallel to the transistors T11 to T16 in the reverse direction. Each of the three-phase coils (U-phase, V-phase, W-phase) of the motor 32 is connected to each connection point between the transistors T11 to T16 as a pair. Therefore, when the voltage is applied to the inverter 34, the ECU 50 adjusts the ratio of the on-time of the paired transistors T11 to T16, thereby forming a rotating magnetic field in the three-phase coil and rotating the motor 32. Driven. Hereinafter, the transistors T11 to T13 may be referred to as U-phase, V-phase, and W-phase upper arms, and the transistors T14 to T16 may be referred to as U-phase, V-phase, and W-phase lower arms.

  The battery 36 is configured as, for example, a lithium ion secondary battery or a nickel hydride secondary battery. The capacitor 44 is connected to the positive electrode bus 40 a and the negative electrode bus 40 b of the power line 40. The relay 42 is provided on the battery 36 side from the connection point of the positive electrode bus 40a and the negative electrode bus 40b with the capacitor 44. This relay 42 connects and disconnects the inverter 34 side (inverter 34 and capacitor 44) and the battery 36 side.

  The cooling device 70 includes a radiator 72, a circulation flow path 74, and an electric pump 76. Radiator 72 performs heat exchange between cooling water (LLC (long life coolant)) and outside air. The circulation channel 74 is a channel for circulating cooling water through the radiator 72, the inverter 34, and the motor 32. The electric pump 76 pumps the cooling water.

  Although not shown, the ECU 50 is configured as a microprocessor centered on a CPU, and includes a ROM for storing processing programs, a RAM for temporarily storing data, an input / output port, and a communication port in addition to the CPU.

  Signals from various sensors are input to the ECU 50 via input ports. Examples of signals from various sensors include the following. The rotational position θm from the rotational position detection sensor 32a that detects the rotational position of the rotor of the motor 32. Phase currents Iu, Iv, Iw of each phase of the motor 32 from a current sensor attached to a power line connecting the motor 32 and the inverter 34. Inverter temperature Tinv from temperature sensor 34a that detects the temperature of inverter 34. A battery voltage Vb from a voltage sensor attached between the terminals of the battery 36. Battery current Ib from a current sensor attached to the output terminal of battery 36. A battery temperature Tb from a temperature sensor attached to the battery 36. Capacitor voltage VH from voltage sensor 44a attached between terminals of capacitor 44. Cooling water temperature Tw from the temperature sensor 78 attached to the circulation flow path 74 of the cooling device 70. An ignition signal from the ignition switch 60. A shift position SP from the shift position sensor 62 that detects the operation position of the shift lever 61. Accelerator opening degree Acc from the accelerator pedal position sensor 64 that detects the depression amount of the accelerator pedal 63. The brake pedal position BP from the brake pedal position sensor 66 that detects the amount of depression of the brake pedal 65. Vehicle speed V from the vehicle speed sensor 68. Vehicle acceleration α from the acceleration sensor 69 attached to the center or both sides of the vehicle front side. Wheel speeds Vwa, Vwb, Vwc, Vwd from wheel speed sensors 28a-28d attached to the drive wheels 22a, 22b and driven wheels 22c, 22d.

  Various control signals are output from the ECU 50 via an output port. Examples of various control signals include the following. Switching control signal to transistors T11 to T16 of inverter 34. Control signal to relay 42. A control signal to the electric pump 76 of the cooling device 70.

  The ECU 50 calculates the rotational speed Nm of the motor 32 based on the rotational position θm of the rotor of the motor 32 detected by the rotational position detection sensor 32a. Further, the ECU 50 calculates the storage ratio SOC of the battery 36 based on the integrated value of the battery current Ib detected by the current sensor.

  In the electric vehicle 20 of the embodiment configured as described above, the ECU 50 first requires the required torque Td * required for traveling based on the accelerator opening Acc from the accelerator pedal position sensor 64 and the vehicle speed V from the vehicle speed sensor 68. Set. Subsequently, the required torque Td * is set to the torque command Tm * of the motor 32. Then, switching control of the transistors T11 to T16 of the inverter 34 is performed so that the motor 32 is driven by the torque command Tm *.

  Next, the operation of the electric vehicle 20 according to the embodiment thus configured, particularly the operation after detection of a vehicle collision will be described. FIG. 2 is a flowchart illustrating an example of a post-collision control routine executed by the ECU 50 of the embodiment. This routine is repeatedly executed after detection of a vehicle collision. In the embodiment, when the vehicle body acceleration α detected by the acceleration sensor 69 exceeds the collision determination threshold value αref, a vehicle collision is detected and the relay 42 is turned off.

  When the post-collision control routine is executed, the ECU 50 first inputs data such as the rotational speed Nm of the motor 32 and the capacitor voltage VH (step S100). Here, as the rotational speed Nm of the motor 32, a value calculated based on the rotational position of the rotor of the motor 32 detected by the rotational position detection sensor 32a is input. As the capacitor voltage VH, a value detected by the voltage sensor 44a is input.

  When the data is thus input, it is determined whether the motor 32 is rotating or stopped using the rotation speed Nm of the motor 32 (step S110). When the vehicle collides, normally, the rotation of the motor 32 also stops as the vehicle stops (the rotation of the drive wheels 22a and 22b). However, if the connection between the drive shaft 26 and the drive shaft 23 is released due to the influence of the collision, the rotation of the motor 32 may continue even if the vehicle stops. In addition, after the vehicle collides, the vehicle may bounce or slide down on a slope, and the drive shaft may continue to rotate for some time. In this case, if the connection between the drive shaft 26 and the drive shaft 23 is not released, the rotation of the motor 32 is continued as the drive shaft 23 continues to rotate. The process of step S110 is a process for determining whether or not these states are present.

  When it is determined in step S110 that the motor 32 is rotating, the duration time ton of the three-phase on control is compared with a threshold value tref (step S120). When the duration time ton of the three-phase on control is less than the threshold value tref, the three-phase on control is executed (step S130), and this routine is terminated.

  Here, in the three-phase ON control, all of the upper arms (T11 to T13) of the transistors T11 to T16 of the inverter 34 are turned on and all of the lower arms (T14 to T16) are turned off. In this control, all the arms (T11 to T13) are turned off and all the lower arms (T14 to T16) are turned on. When the three-phase on control is executed, torque (drag torque) in a direction to reduce the absolute value of the rotational speed Nm of the motor 32 is generated. Accordingly, when the connection between the drive shaft 23 and the rotating shaft of the motor 32 is released due to the influence of the collision, the rotation of the motor 32 is performed by executing the three-phase on control while the motor 32 is rotating. The rotation of the motor 32 can be stopped by reducing the number Nm.

  Further, as the duration time ton of the three-phase on control, the duration from the start of the execution of the three-phase on control is measured and input by a timer (not shown).

  Further, the threshold value tref is determined as the time required to determine (determine) that the drive shaft 23 and the rotating shaft (drive shaft 26) of the motor 32 are connected. According to the study by the present inventors, it has been found that when the connection is released, the motor 32 stops rotating in a relatively short time (for example, 2 seconds or 3 seconds) by executing the three-phase on control. Therefore, when the duration time ton of the three-phase on control becomes longer, it is considered that the connection is continued, and the motor 32 continues to rotate due to the bounce of the vehicle after the collision or the downhill on the slope. Based on this, the threshold value tref is a time slightly longer than the time required for the motor 32 to stop rotating due to the execution of the three-phase on control when the connection is released. In the embodiment, the threshold value tref is determined in consideration of the estimated duration time of the discharge control so that the inverter temperature Tinv does not reach the drive limit temperature Tlim when the discharge control described later is executed. As the threshold value tref, for example, 5 seconds, 6 seconds, 7 seconds, or the like can be used. As the drive limit temperature Tlim, a temperature (for example, 150 ° C. or 160 ° C.) that shuts down the inverter 34 (turns off all of the transistors T11 to T16) in order to suppress overheating of the inverter 34 can be used.

  When the execution of the three-phase on control is continued and the duration ton reaches the threshold value tref (step S120), it is determined (confirmed) that the connection is continuing, and the three-phase on control is stopped (step S140). ), This routine is terminated. When the motor 32 continues to rotate due to the bounce of the vehicle after the collision or the downhill on the slope when the connection is continued, the rotation of the motor 32 cannot be stopped even if the three-phase on control is executed. The execution time of the three-phase on control may become long. Therefore, the temperature increase of the inverter 34 can be suppressed by stopping the three-phase on control.

  When it is determined in step S110 that the motor 32 has stopped rotating, the capacitor voltage VH is compared with the threshold value VHref (step S150). Here, the threshold value VHref is a threshold value used for determining whether or not the discharge of the electric charge of the capacitor 44 may be terminated. As this threshold value VHref, for example, when the voltage VH of the capacitor 44 is about several hundred V when the relay 42 is on, a value of about several V to several tens V can be used.

  When the capacitor voltage VH is higher than the threshold value VHref, discharge control is executed (step S160), and this routine is terminated. Here, the discharge control is a control for performing switching control of the transistors T11 to T16 of the inverter 34 so that the d-axis current flows through the motor 32. When the motor 32 stops rotating, no counter electromotive force is generated in the motor 32. By executing the discharge control, the electric charge of the capacitor 44 can be discharged without outputting torque from the motor 32. When the capacitor voltage VH reaches the threshold value VHref or less, the discharge control is finished (step S170), and this routine is finished.

  In the embodiment, when the duration time ton of the three-phase on control reaches the threshold value tref or more, it is determined (determined) that the connection is continuing, and the three-phase on control is stopped. Thereby, the temperature rise of the inverter 34 can be suppressed. Therefore, when the discharge control is executed after the rotation of the motor 32 is stopped, the inverter temperature Tinv can be prevented from reaching the drive limit temperature Tlim or more. As a result, it is possible to suppress the discharge control from being stopped. That is, it is possible to prevent the capacitor 44 from being quickly discharged when the rotation of the motor 32 is stopped after a vehicle collision. In particular, when the circulation flow path 74 is damaged due to the influence of a collision, the cooling water may not circulate sufficiently to the inverter 34 or the cooling water itself may decrease, and the inverter temperature Tinv may be more likely to rise. In this case, when the discharge control is executed after the rotation of the motor 32 is stopped, the inverter temperature Tinv is more likely to reach the drive limit temperature Tlim or more. Therefore, the significance of performing the control of the above-described embodiment is greater. Note that the above-described threshold value tref is preferably determined so that the inverter temperature Tinv does not reach the drive limit temperature Tlim or higher when the discharge control is performed even when an abnormality occurs in the cooling device 70 due to the influence of the collision.

  In the electric vehicle 20 according to the embodiment described above, when the motor 32 is rotating after detection of a vehicle collision, all of the upper arms (T11 to T13) of the transistors T11 to T16 of the inverter 34 or the lower arm ( Three-phase on control is performed to turn on all of T14 to T16). When the motor 32 stops rotating, discharge control is performed to switch the transistors T11 to T16 so that the d-axis current flows through the motor 32. In such a control, when it is determined (determined) that the motor 32 is rotating and the drive shaft 23 and the rotation shaft (drive shaft 26) of the motor 32 are connected, the connection is continued. Stop (prohibit) three-phase on control. Thereby, the temperature rise of the inverter 34 can be suppressed. Therefore, when the discharge control is executed after the rotation of the motor 32 is stopped, the inverter temperature Tinv can be prevented from reaching the drive limit temperature Tlim or more. As a result, it is possible to suppress the discharge control from being stopped. That is, it is possible to prevent the capacitor 44 from being quickly discharged when the rotation of the motor 32 is stopped after a vehicle collision.

  In the embodiment, when the motor 32 is rotating and the duration time ton of the three-phase on control reaches the threshold value tref or more, it is determined (determined) that the connection is continuing, and the three-phase on control is performed. It was decided to cancel (prohibit). However, the three-phase on control may be stopped (prohibited) when it is determined (confirmed) that the connection is to be continued by another method, for example, the following second method. In the second method, first, the vehicle speed is calculated from the wheel speed Vw to obtain the first calculated vehicle speed V1, and the vehicle speed is calculated from the rotational speed Nm of the motor 32 to obtain the second calculated vehicle speed V2. When the difference ΔV between the first calculated vehicle speed V1 and the second calculated vehicle speed V2 is larger than the threshold value Vref, it is determined (determined) that the connection is being released. On the other hand, when the difference ΔV is equal to or smaller than the threshold value Vref (when the value is near 0), it is determined (confirmed) that the connection is being continued. Here, the average value of the wheel speeds Vwa to Vwd is used as the wheel speed Vw. When the collision mode is a frontal collision, the wheel speed sensors 28a and 28b may fail. Therefore, the average value of the wheel speeds Vwc and Vwd from the wheel speed sensors 28c and 28d is used as the wheel speed Vw. It is good. The calculation of the first calculation vehicle speed V1 can be performed by multiplying the wheel speed Vw by the conversion coefficient k1. The calculation of the second calculation vehicle speed V2 can be performed by multiplying the rotation speed Nm of the motor 32 by the conversion coefficient k2.

  It should be noted that only the second method may be used instead of the method of the embodiment, and the three-phase on control may be stopped (prohibited) when it is determined (confirmed) that the connection is being continued. Further, the three-phase on control may be stopped (prohibited) when it is determined that the connection is being continued by either the method of the embodiment or the second method (whichever is earlier).

  In the embodiment, the electric vehicle includes the motor 32 connected to the drive shaft 26 connected to the drive shaft 23. However, it is good also as a structure of an electric vehicle provided with two or more motors. Moreover, it is good also as a structure of a parallel type or a series type hybrid vehicle.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems will be described. In the embodiment, the motor 32 corresponds to “motor”, the inverter 34 corresponds to “inverter”, the capacitor 44 corresponds to “capacitor”, and the ECU 50 corresponds to “control means”.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problem is the same as that of the embodiment described in the column of means for solving the problem. Therefore, the elements of the invention described in the column of means for solving the problems are not limited. That is, the interpretation of the invention described in the column of means for solving the problems should be made based on the description of the column, and the examples are those of the invention described in the column of means for solving the problems. It is only a specific example.

  As mentioned above, although the form for implementing this invention was demonstrated using the Example, this invention is not limited at all to such an Example, In the range which does not deviate from the summary of this invention, it is with various forms. Of course, it can be implemented.

  The present invention can be used in the automobile manufacturing industry.

  20 electric vehicle, 22a, 22b drive wheel, 23 drive shaft, 24 differential gear, 26 drive shaft, 28a-28d wheel speed sensor, 32 motor, 32a rotational position detection sensor, 34 inverter, 34a temperature sensor, 36 battery, 40 power Line, 40a positive bus, 40b negative bus, 42 relay, 44 capacitor, 44a voltage sensor, 50 electric control unit (ECU), 60 ignition switch, 61 shift lever, 62 shift position sensor, 63 accelerator pedal, 64 accelerator pedal position sensor , 65 Brake pedal, 66 Brake pedal position sensor, 68 Vehicle speed sensor, 69 Acceleration sensor, 70 Cooling device, 72 Radiator, 74 Circulating flow path, 76 Electric pump, 78 Temperature Sensor, D11-D16 diode, T11-T16 transistor.

Claims (1)

A three-phase AC motor connected to the axle;
An inverter that drives the motor by switching of a plurality of switching elements;
A capacitor for smoothing the voltage between the terminals of the inverter;
After the vehicle collision is detected, when the motor is rotating, three-phase on control is performed to control the inverter so that all of the upper arms or all of the lower arms of the plurality of switching elements are turned on. And, when the rotation of the motor stops, a control means for performing discharge control for controlling the inverter so that the electric charge of the capacitor is discharged by passing a d-axis current to the motor;
A car equipped with
The control means prohibits execution of the three-phase on control when it is determined that the motor and the axle are connected when the motor is rotating after detection of a vehicle collision,
A car characterized by that.

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