JP2012114998A - Electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a persistent state where a battery is charged over the predetermined storage ratio when imparting a braking force to a vehicle according to accelerator off.SOLUTION: When the braking force is imparted to a vehicle according to the accelerator off, if the storage ratio SOC exceeds the predetermined value SOCref and the time rate k of change of the storage ratio SOC exceeds the value 0 (S100), the value of the motor drive torque Tmref (the positive value) subtracted from the requested torque Tr* is set to be the brake torque Tb*, and a hydraulic brake device is controlled so that the set brake torque Tb* (braking force) is imparted to an electric vehicle (S110). Thereafter, the motor drive torque Tmref is set to the torque command Tm*, and an inverter and a boosting converter for boosting the voltage of a battery are controlled so that a motor is driven by the set torque command Tm* (S120).

Description

  The present invention relates to an electric vehicle, and more particularly to an electric vehicle including an electric motor that inputs and outputs driving power, a battery that can exchange electric power with the electric motor, and a brake device that applies braking force to the vehicle.

  Conventionally, in this type of electric vehicle, in an EV motor that outputs driving power and a battery that exchanges electric power with the EV motor, the EV motor is regeneratively operated while the vehicle is decelerating. Has been proposed to charge the battery (see, for example, Patent Document 1). In this automobile, when the battery remaining amount is equal to or greater than a predetermined determination value, the EV motor is controlled so that the EV motor is not regeneratively controlled, thereby suppressing the battery remaining amount from exceeding the predetermined remaining amount.

JP 2002-369305 A

  However, in the electric vehicle described above, even when the EV motor is controlled so that the EV motor is not regeneratively controlled, the EV motor may actually be regeneratively controlled to charge the battery. For example, when the EV motor is controlled so that the electric power for charging the battery with the EV motor becomes a value of 0, the EV motor is actually regeneratively controlled due to an error of the current sensor and the battery may be charged. is there. As described above, when the battery is charged even though the remaining amount of the battery is equal to or greater than the predetermined determination value, the deterioration of the battery is promoted.

  The main purpose of the electric vehicle of the present invention is to suppress a state in which the battery is charged beyond a predetermined power storage ratio when a braking force is applied to the vehicle as the accelerator is turned off.

  The electric vehicle of the present invention employs the following means in order to achieve the main object described above.

The electric vehicle of the present invention is
In an electric vehicle comprising: an electric motor that inputs and outputs driving power; a battery that can exchange electric power with the electric motor; and a brake device that applies braking force to the vehicle.
When the accelerator is off, when the storage ratio, which is the ratio of the stored capacity to the total capacity of the battery, is less than a predetermined ratio, the braking force by the brake device is not used and the motor is controlled by regenerative driving. The electric motor and the brake device are controlled so that the required braking force required for the vehicle is applied to the vehicle using power, and when the power storage ratio is equal to or higher than the predetermined ratio, power consumption by powering driving of the motor is consumed. Control means for controlling the electric motor and the brake device so that the required braking force is applied to the vehicle using the braking force by the brake device.
It is characterized by providing.

  In the electric vehicle according to the present invention, when the accelerator is off, the electric motor without using the braking force by the brake device when the storage ratio, which is the ratio of the stored capacity to the total capacity of the battery, is less than a predetermined ratio. The electric motor and the brake device are controlled so that the required braking force required for the vehicle is applied to the vehicle using the braking force generated by the regenerative drive. As a result, the braking force can be applied to the vehicle using the braking force generated by the regenerative drive of the electric motor. When the power storage ratio is equal to or higher than the predetermined ratio, the electric motor and the brake device are controlled such that the required braking force is applied to the vehicle using the braking force of the brake device with the consumption of electric power by the power running drive of the electric motor. Thereby, it can suppress that the state in which a battery is charged more than a predetermined ratio continues while giving braking power to vehicles with accelerator off.

It is a block diagram which shows the outline of a structure of the electric vehicle 20 as one Example of this invention. 2 is a configuration diagram of an electric drive system centered on a motor 32 and an inverter 34. FIG. 3 is a flowchart showing an example of a high SOC charge control routine executed by an electronic control unit 50. The storage ratio SOC, the absolute value of the brake torque Tb * (the brake torque | Tb * | in the figure), and the torque command Tm * when the storage ratio SOC is equal to or greater than the predetermined ratio SOCref and the time change rate k exceeds the value 0 It is explanatory drawing which shows an example of a time change. It is explanatory drawing which shows an example of the control routine at the time of the high SOC charge of a modification. Absolute values of the storage ratio SOC, the charge / discharge current IB, and the brake torque Tb * when the storage ratio SOC is equal to or greater than the predetermined ratio SOCref and the charge / discharge current IB is less than 0 in the high SOC charge control routine of the modification. It is explanatory drawing which shows an example of the time change of (brake torque | Tb * |) in the figure, and torque command Tm *.

  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 shown in the figure, an electric vehicle 20 according to the embodiment includes, for example, a motor 32 that is configured as a synchronous generator motor and that can input and output power to a drive shaft 22 that is connected to drive wheels 26a and 26b via a differential gear 24. An inverter 34 for driving the motor 32, a battery 36 configured as a lithium ion secondary battery, a power line 42 connected to the inverter 34 (hereinafter referred to as a high voltage system power line), and a battery 36 are connected. It is connected to a power line (hereinafter referred to as a battery voltage system power line) 44 and adjusts the voltage VH of the high voltage system power line 42 within the range of the voltage VL of the battery voltage system power line 44 and the maximum allowable voltage VHmax. And a boost converter for exchanging power between the high voltage system power line 42 and the battery voltage system power line 44 0, and adjusts the hydraulic pressure to the hydro booster 92 that generates hydraulic pressure in response to the depression of the brake pedal 65 and the brake wheel cylinders 28a, 28b, 29a, 29b attached to the drive wheels 26a, 26b and the driven wheels 27a, 27b. A hydraulic brake device 90 having a brake actuator 94, an accelerator signal from the ignition switch 60, a shift position from a shift position sensor 62 that detects the position of the shift lever 61, and an accelerator pedal position sensor that detects the amount of depression of the accelerator pedal 63 The accelerator opening Acc from 64, the brake position BP from the brake pedal position sensor 66 for detecting the depression amount of the brake pedal 65, the vehicle speed V from the vehicle speed sensor 68 and the invar 34 and boost converter 40 includes an electronic control unit 50 for controlling the brake actuator 94, the. Here, as the maximum allowable voltage VHmax, a voltage that is predetermined as a voltage equal to or lower than the withstand voltage of the capacitor 46 described later can be used. The electronic control unit 50 manages the battery 36 based on the integrated value of the charge / discharge current IB (the current in the direction of charging the battery 36 is negative) detected by a current sensor (not shown). The storage ratio SOC, which is the ratio of the stored capacity to the total capacity, is calculated, or the time change rate k of the storage ratio SOC at a certain time is calculated. Further, the electronic control unit 50 has an anti-lock brake system function (ABS) that prevents any of the driving wheels 29a, 29b and the driven wheels 27a, 27b from slipping due to locking when the driver depresses the brake pedal 65. Or a traction control (TRC) that prevents one of the drive wheels 26a, 26b from slipping due to idling when the driver depresses the accelerator pedal 63, and a posture maintenance that holds the posture when the vehicle is turning. Control (VSC) is also performed.

  As shown in FIG. 2, boost converter 40 includes two transistors T1 and T2, two diodes D1 and D2 connected in parallel to transistors T1 and T2, and a reactor L. The two transistors T1 and T2 are respectively connected to the positive bus of the high voltage system power line 42 and the negative bus of the high voltage system power line 42 and the battery voltage system power line 44, and the connection of the two transistors T1 and T2 A reactor L is connected to the point. Further, the positive electrode terminal and the negative electrode terminal of the battery 36 are connected to the positive electrode bus 44 of the battery voltage system power line connected to the reactor L and the negative electrode bus of the high voltage system power line 42 and the battery voltage system power line 44, respectively. Has been. Therefore, by turning on and off the transistors T1 and T2, the power of the battery voltage system power line 44 is boosted and supplied to the high voltage system power line 42, or the power of the high voltage system power line 42 is stepped down to reduce the battery voltage. Or can be supplied to the system power line 44. A smoothing capacitor 46 is connected to the positive and negative buses of the high voltage system power line 42, and a smoothing capacitor 48 is connected to the positive and negative buses of the battery voltage system power line 44. Yes.

  The electric vehicle 20 according to the embodiment thus configured basically travels by normal drive control described below, which is executed by the electronic control unit 50. In the electronic control unit 50, first, a required torque Tr * to be output to the drive shaft 22 is set according to the accelerator opening Acc from the accelerator pedal position sensor 64 and the vehicle speed V from the vehicle speed sensor 68, and the set required torque is set. Tr * is set as a torque command Tm * to be output from the motor 32, and a voltage required to drive the motor 32 at the operating point consisting of the set torque command Tm * and the rotation speed Nm is set to the high voltage system power line 42. Is set as a target voltage VH * of the inverter 34, the switching element of the inverter 34 is controlled to be driven by the set torque command Tm *, and the voltage VH of the high voltage system power line 42 becomes the target voltage VH *. The transistors T1 and T2 of the boost converter 40 are switching-controlled. The electric vehicle 20 of the embodiment can travel with the required torque Tr * by such control.

  In the electric vehicle 20 of the embodiment, when the brake pedal 65 is depressed, the electronic control unit 50 executes brake control described below. In the electronic control unit 50, when the brake pedal 65 is depressed, the braking force to be applied to the vehicle by the hydraulic brake with respect to the depression force (brake depression force) of the brake pedal 65 is derived from a map (not shown) and the derived braking force is derived. The hydraulic pressures of the brake wheel cylinders 28a, 28b, 29a, 29b are adjusted by controlling the brake actuator 94 so as to be applied. In the electric vehicle 20 of the embodiment, a braking force corresponding to the brake depression force can be applied to the vehicle by such control.

  Next, the operation of the electric vehicle 20 of the embodiment, particularly when the accelerator pedal is turned off and the accelerator opening from the accelerator pedal position sensor 64 is 0%, the required torque Tr * is less than the value 0 and the vehicle is controlled. The operation at the time of accelerator-off braking which becomes a braking torque for applying power will be described. First, the electronic control unit 50 compares the storage ratio SOC of the battery 36 with a predetermined ratio SOCref (for example, 80%) that is a storage ratio slightly lower than the storage ratio SOC when the battery 36 is fully charged. When the storage ratio SOC is less than the predetermined ratio SOCref, it is determined that the battery 36 can be charged, the required torque Tr * is set as the torque command Tm * to be output from the motor 32, and the set torque command Tm The target voltage VH * of the high-voltage system power line 42 is set from * and the rotational speed Nm in the same process as normal drive control, and the inverter 34 is controlled so that the motor 32 is driven by the set torque command Tm *. At the same time, the boost converter 40 is controlled so that the voltage VH of the high voltage system power line 42 becomes the target voltage VH *. Now, since the case where the required torque Tr * is a braking torque is considered, the motor 32 is regeneratively driven to apply a braking force to the vehicle. At this time, when the brake pedal 65 is not depressed, the electronic control unit 50 does not apply the braking force by the hydraulic brake device 90 to the drive wheels 26a and 26b and the driven wheels 27a and 27b. The hydraulic pressure of 28b, 29a, 29b is controlled. With such control, the braking force can be applied to the vehicle by the braking force generated by the regenerative drive of the motor 32 without using the braking force by the hydraulic brake device 90.

  When the storage ratio SOC is equal to or greater than the predetermined ratio SOCref, it is determined that the battery 36 should not be charged any more, and the torque command Tm * is set to a value 0 and the set torque command Tm * and the rotation speed Nm are set. And set as the target voltage VH * of the high voltage system power line 42 by the same process as the normal drive control, and controls the inverter 34 so that the motor 32 is driven by the set torque command Tm * and the high voltage system power. Boost converter 40 is controlled so that voltage VH of line 42 becomes target voltage VH *. Thus, by controlling the motor 32 so that torque is not output from the motor 32, the battery 36 can be prevented from being charged.

  When the control of the motor 32 is started so that the storage ratio SOC becomes equal to or greater than the predetermined ratio SOCref and the torque from the motor 32 becomes 0, the electronic control unit 50 executes the high SOC charge control described below. FIG. 3 is a flowchart illustrating an example of a high SOC control routine that is repeatedly executed by the electronic control unit 50 at predetermined time intervals. First, the electronic control unit 50 executes a process for checking whether or not the time change rate k exceeds the value 0 (step S100). When the time change rate k does not exceed the value 0, that is, the battery 36 When the power storage rate SOC is not increased, it is determined that the motor 32 can be continuously controlled so that the torque from the motor 32 becomes 0, and the torque command Tm * is set to 0 and set. The torque command Tm * and the rotation speed Nm are used to set the target voltage VH * of the high-voltage power line 42 in the same process as in normal drive control, and the motor 32 is driven with the set torque command Tm *. In this routine, the inverter 34 is controlled and the boost converter 40 is controlled so that the voltage VH of the high voltage system power line 42 becomes the target voltage VH * (step S120). To the end. Thus, by controlling the motor 32 so that torque is not output from the motor 32, the battery 36 can be prevented from being charged.

  When the time rate of change k of the power storage rate SOC exceeds the value 0 (step S100), that is, although the motor 32 is controlled so that the torque becomes the value 0 from the motor 32, for example, for example, When the motor 32 is actually driven regeneratively due to an error such as a current sensor that detects the phase current of the motor 32 when controlling the motor 32, the motor 32 is driven when the accelerator 32 is powered off from the required torque Tr *. The brake actuator Tmref obtained by subtracting the motor drive torque Tmref (positive value) to be output from the brake torque Tb * is set as the brake torque Tb * so that the set brake torque Tb * (braking force) is applied to the electric vehicle 20. 94 (step S110), and then when the motor drive torque Tmref is set in the torque command Tm * Is set as the target voltage VH * of the high voltage system power line 42 by the same process as in the normal drive control using the torque command Tm * and the rotation speed Nm, and the motor 32 is driven by the set torque command Tm *. Then, the inverter 34 is controlled and the boost converter 40 is controlled so that the voltage VH of the high voltage system power line 42 becomes the target voltage VH * (step S120), and this routine is finished. In the processing of steps S110 and S120, the motor driving torque Tmref is assumed to be a torque that increases with time. With this control, the required torque Tr * can be applied to the vehicle using the braking force of the hydraulic brake device 90 while the motor 32 is driven by power running and electric power is consumed by the motor 32. The reason why the motor 32 is controlled after the hydraulic brake device 90 is controlled in the processing of steps S110 and S120 is that the control response of the hydraulic brake device 90 is poorer than that of the motor 32.

  The storage ratio SOC, the absolute value of the brake torque Tb * (the brake torque | Tb * | in the figure), and the torque command Tm * when the storage ratio SOC is equal to or greater than the predetermined ratio SOCref and the time change rate k exceeds the value 0 An example of the time change is shown in FIG. When the storage rate SOC is equal to or greater than the predetermined rate SOCref and the time rate of change k exceeds the value 0, the motor 32 is driven to power and the power is consumed by the motor 32 as shown in the figure, and the storage rate SOC decreases. Turn. As described above, when the power storage rate SOC is equal to or higher than the predetermined rate SOCref and the time rate of change k exceeds the value 0, the state where the power storage rate SOC is equal to or higher than the predetermined rate SOCref continues by driving the motor 32. It is possible to suppress the deterioration of the battery 36.

  According to the electric vehicle 20 of the embodiment described above, when the power storage rate SOC is equal to or greater than the predetermined rate SOCref, the motor 32 is driven by power and the electric power is consumed by the motor 32, and the braking force by the hydraulic brake device 90 is used. Since the motor 32 and the hydraulic brake device 90 are controlled so that the required torque Tr * is applied to the vehicle, it is possible to prevent the battery 36 from deteriorating due to the state where the storage ratio SOC is equal to or higher than the predetermined ratio SOCref.

  In the electric vehicle 20 of the embodiment, it is determined in the process of step S100 whether or not the time change rate k of the power storage ratio SOC is larger than the value 0. However, the control routine at the time of high SOC charging in the modified example of FIG. As illustrated, it may be determined whether or not the charge / discharge current IB detected by the current sensor to manage the battery 36 is smaller than 0, that is, whether or not the battery 36 is charged (step). S100B). In this case, the absolute values of the storage ratio SOC, the charge / discharge current IB, and the brake torque Tb * when the storage ratio SOC is equal to or greater than the predetermined ratio SOCref and the charge / discharge current IB is less than 0 (brake torque | Tb in the figure) * |), An example of the time change of the torque command Tm * is shown in FIG.

  In the electric vehicle 20 of the embodiment, the motor 32 is controlled such that the electric power from the motor 32 becomes 0 when the storage ratio SOC is equal to or greater than the predetermined ratio SOCref, and thus the rate of change with time during the control of the motor 32. When k exceeds the value 0, the motor 32 and the hydraulic brake device are driven so that the required torque Tr * is applied to the vehicle using the braking force of the hydraulic brake device 90 while the motor 32 is driven to power and consumes electric power. 90 is controlled, but when the storage ratio SOC is equal to or greater than the predetermined ratio SOCref, the motor 32 is immediately driven to power and the motor 32 consumes electric power while using the braking force of the hydraulic brake device 90 to request torque Tr The motor 32 and the hydraulic brake device 90 may be controlled so that * is given to the vehicle.

  In the embodiment, the present invention is applied to an electric vehicle equipped with a motor as a power source for traveling, but may be applied to a hybrid vehicle equipped with an engine and a motor as a power source for traveling.

  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 the “electric motor”, the battery 36 corresponds to the “battery”, the hydraulic brake device 90 corresponds to the “brake device”, and the storage rate SOC is less than the predetermined rate SOCref. The motor 32 and the hydraulic brake device 90 are controlled so that the required torque Tr * is applied to the vehicle using the braking force generated by the regenerative drive of 32, and when the power storage rate SOC is equal to or higher than the predetermined rate SOCref, the motor 32 is driven by power running. The electronic control unit 50 that controls the motor 32 and the hydraulic brake device 90 so that the required torque Tr * is applied to the vehicle using the braking force of the hydraulic brake device 90 while the electric power is consumed by the motor 32 corresponds to “control means”. To do.

  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 manufacturing industry of electric vehicles.

  1 electric vehicle, 22 drive shaft, 24 differential gear, 26 battery, 26a, 26b drive wheel, 27a, 27b driven wheel, 28a, 28b, 29a, 29b brake wheel cylinder, 32 motor, 32a rotational position detection sensor, 34 inverter, 36 battery, 40 boost converter, 42 high voltage power line, 44 battery voltage power line, 46, 48 capacitor, 50 electronic control unit, 52 CPU, 54 ROM, 56 RAM, 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, 90 Hydraulic brake device, 92 Hydro booster , 94 Brake actuator, D1, D2 diode, L reactor, T1, T2 transistors.

Claims (1)

In an electric vehicle comprising: an electric motor that inputs and outputs driving power; a battery that can exchange electric power with the electric motor; and a brake device that applies braking force to the vehicle.
When the accelerator is off, when the storage ratio, which is the ratio of the stored capacity to the total capacity of the battery, is less than a predetermined ratio, the braking force by the brake device is not used and the motor is controlled by regenerative driving. The electric motor and the brake device are controlled so that the required braking force required for the vehicle is applied to the vehicle using power, and when the power storage ratio is equal to or higher than the predetermined ratio, power consumption by powering driving of the motor is consumed. Control means for controlling the electric motor and the brake device so that the required braking force is applied to the vehicle using the braking force by the brake device.
An electric vehicle comprising:

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