Torque control device for electric vehicles

Abstract

Torque control device of an electric vehicle (1), comprising: a DC power source (4); a motor (2); and an inverter (3) for converting a DC power of the DC power source (4) into an AC power to supply the AC power to the motor (2) and for converting an AC power output from the motor (2) into a DC power to supply the DC power to the DC power source (4), the torque control device further comprising: a control unit (5) configured to instruct the motor (2) to output a torque in a direction reverse to a rotation direction of the motor (2) to reduce the regeneration current when it is detected that the motor (2) rotates in a direction reverse to a torque output direction of the motor (2) in a state in which a charge level of the DC power source (4) has exceeded a predetermined value, and when it is detected that the regeneration current flows from the motor (2) to the DC power source (4), and wherein the control unit (5) sets a torque to reduce the regeneration current in response to the change amount of the regeneration current.

Description

Technical area

[0001] This invention relates to a torque control device of an electric vehicle. Background of the invention

[0002] JP 2007-203975 A describes a method for preventing a vehicle from sliding down on a steeply uphill road using regeneration control when the vehicle is in a situation of sliding down with respect to a traveling direction. State of the art

[0003] JP 2013-163434 A discloses a control device for a hybrid vehicle capable of recovering regenerative energy. The hybrid vehicle is configured to operate a plurality of energy sources simultaneously or individually while driving. The electric motor is powered by electrical energy supplied by a generator and / or a battery during driving to drive wheels or the like. On the other hand, the electric motor in the hybrid vehicle functions as a generator during regeneration, and the regenerative electrical energy can be supplied to the battery.

[0004] JP 2006-262645 A discloses a control device for a vehicle, and in particular, a control device for controlling engine torque when starting uphill for a vehicle equipped with an electric motor as a driving power source and a secondary battery configured to be charged by regeneratively generated energy of the electric motor.

[0005] JP 2016-1959 A discloses a control device for an electric vehicle, wherein, when it is determined that the vehicle is in a coasting phase, a regenerative braking torque with the same torque value as a target drive torque is generated in the electric motor. If a target drive torque exceeds the allowable motor regeneration torque, an allowable motor regeneration torque is generated in the electric motor.

[0006] JP 2008-199716 A discloses a motor controller having a reversing control section for controlling the armature current of a motor by controlling the operation of an inverter so that the reversing speed is limited to a reversing speed limit value as a target speed by the driving force of the motor while reversing is maintained and the reversing speed exceeds the reversing speed limit value.

[0007] JP 2013-252023 A discloses a vehicle that travels and moves when torque is generated in a positive rotation direction of traction motors, the vehicle comprising a control device that generates a reverse braking force by intermittently generating torque in a reverse rotation direction of the traction motors.

[0008] JP 2009-40211 A discloses a method and apparatus for controlling the generator power for a hybrid vehicle to prevent the battery power from exceeding a set value while maintaining the desired vehicle deceleration. Summary of the inventionProblem to be solved by the invention

[0009] However, if regeneration control is performed when the state of charge of a battery is close to a fully charged state, the battery will be overcharged because the battery no longer has any capacity, which is a problem.

[0010] Additionally, in a situation where an electric vehicle's motor rotates in a direction opposite to a torque output direction, for example, in a situation where a shift position is in a forward drive range and the motor outputs torque in a forward direction, the vehicle slips down in reverse and the motor rotates in a negative direction (the negative direction is the motor rotation direction, which causes the vehicle to travel in reverse). Since regenerative braking is applied, as the battery charge level approaches a fully charged state, the battery will be overcharged, which is a problem.

[0011] As a similar event, when a driver switches a gear position from a reverse range to the forward range while the vehicle is traveling in the reverse direction, the motor is controlled to output torque in the forward direction because regenerative charging is performed, that is, in a state where the motor rotates in the negative direction, when the battery charge level approaches a fully charged state, the battery is overcharged, which is a problem.

[0012] An object of this invention is to provide a torque control device of an electric vehicle that can prevent a battery from being overcharged when a motor rotates in a direction opposite to a torque output direction in a state where the battery is almost fully charged. Means of solving the problem

[0013] To achieve the above-mentioned object, according to one aspect of this invention, there is provided a torque control device of an electric vehicle, comprising: a DC power source; a motor;and an inverter for converting a direct current of the direct current source into an alternating current to supply the alternating current to the motor, and for converting an alternating current output from the motor into a direct current to supply the direct current to the direct current source. The device includes a control unit configured to instruct the motor to output torque in a direction reverse to a rotation direction of the motor to reduce the regeneration current when it is detected that the motor is rotating in a direction reverse to a torque output direction of the motor in a state where a charge level of the direct current source has exceeded a predetermined value, and when it is detected that the regeneration current is flowing from the motor to the direct current source, and the control unit adjusts a torque to reduce the regeneration current in response to the amount of change in the regeneration current. Effect of the invention

[0014] As described above, according to this invention, it is possible to prevent the battery from being overcharged when the motor rotates in the direction opposite to the torque output direction in a state where a battery is almost fully charged. Short description of the characters Fig. 1 is a block diagram of a torque control device of an electric vehicle according to an example of this invention. Fig. 2 is a flowchart showing the flow of a torque control process of the torque control device of the electric vehicle according to the example of this invention. Fig. 3 is a flowchart showing the flow of a torque control process of the torque control device of the electric vehicle according to another aspect of the example of this invention. Fig. 4 is a timing chart showing a change in the inverter current in the torque control process of the torque control device of the electric vehicle according to the other aspect of the example of this invention. Embodiment(s) of the invention

[0015] According to embodiments of this invention, there is provided a torque control device of an electric vehicle comprising: a DC power source; a motor;and an inverter for converting a direct current of the direct current source into an alternating current to supply the alternating current to the motor, and for converting an alternating current output from the motor into a direct current to supply the direct current to the direct current source. The device includes a control unit configured to instruct the motor to output torque in a direction reverse to a rotation direction of the motor to reduce the regeneration current when it is detected that the motor is rotating in a direction reverse to a torque output direction of the motor in a state where a charge level of the direct current source has exceeded a predetermined value, when it is detected that the regeneration current is flowing from the motor to the direct current source, and the control unit adjusts a torque to reduce the regeneration current in response to the amount of change in the regeneration current.

[0016] Therefore, the torque control device of the electric vehicle according to the embodiment of this invention can prevent a battery from being overcharged when the motor rotates in the direction opposite to the torque output direction in a state where the battery is almost fully charged. Examples

[0017] Hereinafter, a torque control device of an electric vehicle according to an example of this invention will be described in detail with reference to the drawings.

[0018] In Fig. 1, an electric vehicle 1 (hereinafter simply referred to as "vehicle") is an electric vehicle in which the torque control device of the electric vehicle according to the example of this invention is mounted, and which includes: a motor 2; an inverter 3; a battery 4 as a DC power source; and a control unit 5.

[0019] Motor 2, for example, is a synchronous motor with a rotor in which several permanent magnets are embedded, and a stator around which a stator coil is wound. When a three-phase alternating current is applied to the stator coil, a rotating magnetic field is created in the stator. The rotating magnetic field rotates the rotor, thus generating driving force for motor 2.

[0020] Furthermore, motor 2 is driven in such a way that rotational resistance induced during power generation is used to brake vehicle 1. Therefore, motor 2 can be used to generate electric power through regeneration. As described above, motor 2 also serves as a generator and can generate electric power to charge battery 4.

[0021] A rotating shaft of the motor 2 is connected to a drive shaft 11 via a speed reducer 21. The motor 2 drives a drive wheel 10 via the drive shaft 11.

[0022] The motor 2 is provided with a speed sensor 91 that detects the speed of the rotating shaft of the motor 2. The drive wheel 10 is provided with a wheel speed sensor 96 that detects the speed of the drive wheel 10. The speed sensor 91 and the wheel speed sensor 96 output a positive speed when rotation is detected in a direction in which the vehicle 1 is traveling forward.

[0023] The inverter 3 is controlled by the control unit 5 to supply the motor 2 with three-phase alternating current. In addition, the inverter 3 converts the three-phase alternating current generated by the motor 2 into direct current and charges the battery 4 with the direct current.

[0024] The battery 4 is a nickel battery, a lithium battery, or the like, and is formed by connecting multiple cells in series. The battery 4 supplies electric power to the motor 2 via the inverter 3. A current sensor 92 is provided between the inverter 3 and the battery 4 and detects the direct current of the inverter 3. The current sensor 92 outputs a positive current value when it detects that a current flows in a direction (a direction from the battery 4 to the inverter 3) in which the battery 4 is discharged.

[0025] The control unit 5 is capable of detecting the cell voltage or temperature of each cell of the battery 4. The control unit 5 is capable of detecting the state of charge (SOC) of the battery 4 based on detected cell voltage or temperature values ​​and an output of the current sensor 92.

[0026] The control unit 5 is a computer unit including a central processing unit (CPU), a random access memory (RAM), a read-only memory (ROM), an input port, and an output port.

[0027] The ROM of the control unit 5 stores a program that enables the computer unit to function as the control unit 5 along with various control constants, various maps, and the like. That is, the computer unit functions as the control unit 5 by causing the CPU to execute the program stored in the ROM.

[0028] The input terminal of the control unit 5 is connected to various sensors, including a shift position sensor 93, an accelerator position sensor 94, and a brake switch 95, in addition to the speed sensor 91, the current sensor 92, and the wheel speed sensor 96 described above. Furthermore, the output terminal of the control unit 5 is connected to various control targets, including the inverter 3 described above.

[0029] The shift position sensor 93 detects a shift position selected by a driver by operating a shift lever (not shown). The shift position is selected, for example, from one of the following ranges: a forward drive range (D range), an engine speed limit range (L range), a reverse drive range (R range), a stop range (N range), and a parking range (P range). The D range and the L range are forward shift positions of the vehicle 1, and the R range is a reverse shift position of the vehicle 1.

[0030] The accelerator pedal position sensor 94 detects an accelerator pedal position, which is the position of an accelerator pedal (not shown) operated by the driver.

[0031] The brake switch 95 detects whether a brake pedal (not shown) has been pressed by the driver.

[0032] According to this example, when it is detected that the motor 2 rotates in a direction opposite to a torque output direction of the motor 2 in a state where the state of charge of the battery 4 has exceeded a predetermined value, if it is determined that a regeneration current flows from the motor 2 to the battery 4, the control unit 5 instructs the motor 2 to output torque in a direction opposite to the rotation direction of the motor 2 to reduce the regeneration current.

[0033] For example, when the rotation of the motor 2 in the torque output direction is a positive rotation, if the rotation speed of the motor 2 detected by the rotation speed sensor 91 is less than a threshold value for determining that the motor 2 is rotating backward, the control unit 5 determines that the rotation of the motor 2 is detected in the direction opposite to the torque output direction of the motor 2.

[0034] For example, when the current value of the inverter current detected by the current sensor 92 is less than a charge determination threshold, the control unit 5 determines that a regeneration current flowing from the motor 2 to the battery 4 is detected.

[0035] The control unit 5 can determine the increased torque value output by the motor 2 in response to the regeneration current flowing from the motor 2 to the battery 4. The control unit 5 can determine the increased torque value based, for example, on the amount of change in the inverter current. More preferably, it is possible to enhance the effect of preventing the vehicle 1 from skidding if the increased torque value is set large.

[0036] After the control unit 5 instructs the motor 2 to output torque in the direction opposite to the rotation direction of the motor 2, when it is determined that the motor 2 rotates in the direction opposite to the torque output direction of the motor 2 and that a discharge current flows from the battery 4 to the motor 2, the control unit 5 instructs the motor 2 to maintain the output of torque in the direction opposite to the rotation direction of the motor 2.

[0037] For example, if the rotation of the motor 2 in the torque output direction is positive rotation, when the rotational speed of the motor 2 detected by the rotational speed sensor 91 is less than or equal to a threshold value, the control unit 5 determines that the rotation of the motor 2 is detected in the direction opposite to the torque output direction of the motor 2 to determine that the motor 2 is positively rotating. The positive rotational speed determination threshold value is the value of the rotational speed by which it can be determined that the motor 2 is rotating in the torque output direction of the motor 2.

[0038] When the control unit 5 instructs the motor 2 to output the torque in the direction opposite to the rotation direction of the motor 2 and it is determined that the motor 2 is rotating in the torque output direction, the control unit 5 instructs the motor 2 to maintain the torque output.

[0039] For example, when the rotation of the motor 2 in the torque output direction is positive rotation, if the speed of the motor 2 detected by the speed sensor 91 is greater than the threshold, the control unit 5 determines that the rotation of the motor 2 in the torque output direction is detected to determine that the motor 2 is positively rotating.

[0040] After the control unit 5 instructs the motor 2 to output torque in the direction opposite to the rotation direction of the motor 2 and determines that the motor 2 is rotating in the torque output direction, the control unit 5 may instruct the motor 2 to reduce torque output if the rotational speed of the motor 2 is not within a stop range or if it is not detected that a discharge current is flowing from the battery 4 to the motor 2. The control unit 5 may determine the reduced torque value based on, for example, the amount of change in the inverter current.

[0041] Since the determination is made as such, it is possible to prevent an excessive increase in the speed of the engine 2.

[0042] For example, if the rotation of the motor 2 in the torque output direction is a positive rotation, to determine that the motor 2 stops rotating, if the rotational speed of the motor 2 detected by the rotational speed sensor 91 is greater than a threshold, the control unit 5 determines that the rotational speed of the motor 2 is not in the stop range. The rotational stop threshold is a threshold for setting the stop range of the motor 2 and may include a creep speed range or a very low speed range in the direction opposite to the torque output direction of the motor 2.

[0043] For example, when a discharge determination threshold is not equal to a current value detected by the current sensor 92, the control unit 5 determines that a discharge current flowing from the battery 4 to the motor 2 is not detected.

[0044] After the control unit 5 instructs the motor 2 to output torque in the direction opposite to the rotation direction of the motor 2, and determines that the motor 2 is rotating in the torque output direction when the rotational speed of the motor 2 is in a stop range, and detects that a discharge current is flowing from the battery 4 to the motor 2, the control unit 5 instructs the motor 2 to maintain torque output. At this time, the rotation of the motor is equivalent to being in the stop range, but the motor 2 is slightly discharged.

[0045] For example, when the rotation of the motor 2 in the torque output direction is a positive rotation to determine that the motor 2 stops rotating, when the rotational speed of the motor 2 detected by the rotational speed sensor 91 is less than or equal to the threshold value, the control unit 5 determines that the rotational speed of the motor 2 is in the stop range.

[0046] For example, when the discharge determination threshold is equal to the current value detected by the current sensor 92, the control unit 5 determines that a discharge current flowing from the battery 4 to the motor 2 is detected.

[0047] When an operation of the accelerator pedal is detected by the accelerator pedal position sensor 94 or an operation of the brake pedal is detected by the brake switch 95, the control unit 5 can instruct the motor 2 to stop outputting the torque in the direction opposite to the direction of rotation of the motor 2.

[0048] The threshold for determining that motor 2 is rotating in the opposite direction, the charge determination threshold, the threshold for determining that motor 2 is rotating positively, the threshold for determining that motor 2 has stopped rotating, and the discharge determination threshold are acquired through experiments or the like and stored in the ROM of the control unit 5. The rotation stop threshold is set to a value greater than the positive rotation determination threshold.

[0049] A torque control process executed by the torque control device of the electric vehicle having the above-mentioned configuration according to the example will be described with reference to Fig. 2. Note that when the state of charge of the battery 4 exceeds the predetermined value, the torque control process described below starts and is executed at predetermined time intervals.

[0050] In step S1, the control unit 5 determines whether, when the rotation of the motor 2 in the torque output direction is positive rotation, the rotational speed of the motor 2 detected by the rotational speed sensor 91 is less than a threshold A to determine that the motor 2 is rotating in the opposite direction, and the inverter current detected by the current sensor 92 is less than a charge determination threshold B. If the control unit 5 determines that it is not detected that the rotational speed of the motor 2 is less than the threshold A to determine that the motor 2 is rotating in the opposite direction and the inverter current is less than the charge determination threshold B, the control unit 5 ends the process.

[0051] When the control unit 5 determines that it is detected that the rotational speed of the motor 2 is less than the threshold A to determine that the motor 2 is rotating in the opposite direction and the inverter current is less than the charge determination threshold B, the control unit 5 determines the increased value of the torque of the motor 2 in step S2 based on the amount of change between the inverter current of the previous process and the inverter current of the current process.

[0052] In step S3, the control unit 5 determines whether the rotational speed of the engine 2 detected by the rotational speed sensor 91 is greater than a threshold value C to determine that the engine 2 is rotating positively. If it is determined that the rotational speed of the engine 2 is not greater than the threshold value C to determine that the engine 2 is rotating positively, the control unit 5 causes the process to return to step S2 and repeats the process.

[0053] If it is determined that the rotational speed of the motor 2 is greater than the threshold value C to determine that the motor 2 is rotating positively, the control unit 5 determines in step S4 whether it is detected that the rotational speed of the motor 2 detected by the rotational speed sensor 91 is less than or equal to a threshold value D to determine that the motor 2 stops rotating, and that the inverter current detected by the current sensor 92 is equal to a discharge determination threshold value E. If the control unit 5 determines that it is detected that the rotational speed of the motor 2 is less than or equal to the threshold value D to determine that the motor 2 stops rotating, and that the inverter current is equal to the discharge determination threshold value E, the control unit 5 ends the process.

[0054] At this time, the rotation of the motor is equivalent to being in the stop range, but the motor 2 is slightly unloaded. Note that the rotation stop threshold D is a threshold for setting the stop range of the motor 2 and may also include a creep speed range or a very low speed range in the direction opposite to the torque output direction of the motor 2.

[0055] When the control unit 5 determines that it is not detected that the rotational speed of the motor 2 is less than or equal to the threshold value D for determining that the motor 2 stops rotating, and the inverter current is equal to the discharge determination threshold value E, the control unit 5 determines the reduced value of the torque of the motor 2 based on the amount of change between the inverter current of the previous process and the inverter current of the current process in step S5, causes the process to return to step S4, and repeats the process.

[0056] As described above, in the example, when it is detected that the motor 2 rotates in the direction opposite to the torque output direction of the motor 2 in a state where the state of charge of the battery 4 has exceeded the predetermined value, if it is determined that a regeneration current flows from the motor 2 to the battery 4, the motor 2 is instructed to output a torque in the direction opposite to the rotation direction of the motor 2 to reduce the regeneration current.

[0057] Therefore, when it is detected that the regeneration current is flowing from the motor 2 to the battery 4, it is possible to reduce the regeneration current and prevent the battery 4 from being overcharged by outputting torque in the direction opposite to the rotation direction of the motor 2 to reduce the regeneration current. In addition, it is possible to prevent the vehicle 1 from skidding.

[0058] In addition, the increased value of the torque output by the motor 2 is determined in response to the regeneration current flowing from the motor 2 to the battery 4.

[0059] Therefore, by outputting the same amount of torque as the change amount of the regeneration current, it is possible to reduce the regeneration current and prevent the battery 4 from being overcharged. In addition, it is possible to prevent the vehicle 1 from slipping down.

[0060] In addition, when it is detected that the motor 2 rotates in the direction opposite to the torque output direction of the motor 2 after the motor 2 is instructed to output torque in the direction opposite to the rotation direction of the motor 2, and that a discharge current flows from the battery 4 to the motor 2, the motor 2 is instructed to maintain the torque in the direction opposite to the rotation direction of the motor 2.

[0061] Therefore, it is possible to prevent the battery 4 from being overcharged when it is detected that the rotation direction of the motor 2 is opposite to the torque output direction of the motor 2 and a discharge current flows from the battery 4 to the motor 2 because no regeneration current is generated.

[0062] When the number of revolutions of the motor 2 is very small and the motor 2 rotates in the direction opposite to the torque output direction, a discharge current flows in the entire system because the power consumption for driving the motor 2 and the inverter 3 exceeds the regenerative electric power recovered by the motor 2.

[0063] In addition, since the motor 2 rotates at a low speed and in the direction opposite to the torque output direction of the motor 2, it is possible to mitigate a tendency to slip down.

[0064] In addition, when an operation of the accelerator pedal or an operation of the brake pedal is detected, the motor 2 is instructed to stop outputting the torque in the direction opposite to the direction of rotation of the motor 2.

[0065] Therefore, when it is detected that the vehicle 1 is prevented from sliding down by the driver by operating the accelerator pedal or the brake pedal, it is possible to stop the output of the torque and prevent the battery 4 from being discharged.

[0066] According to another aspect of the example, when a shift position detected by the shift position sensor 93 is changed from a forward shift position of the vehicle 1 to a reverse shift position or is changed from the reverse shift position to the forward shift position in a state where the charge level of the battery 4 has exceeded the predetermined value, and when it is determined that a regeneration current flows from the motor 2 to the battery 4, the control unit 5 instructs the motor 2 to output torque in the direction opposite to the rotation direction of the motor 2 to reduce the regeneration current.

[0067] For example, when a current value detected by the current sensor 92 is smaller than the charge determination threshold, the control unit 5 determines that a regeneration current flowing from the motor 2 to the battery 4 is detected.

[0068] The control unit 5 can determine the increased value of the torque output by the motor 2 in response to the regeneration current flowing from the motor 2 to the battery 4. The control unit 5 can determine the increased value of the torque based, for example, on the amount of change in the inverter current.

[0069] More preferably, it is desirable that the increased torque value be set small by multiplying the change in the inverter current by a constant. Since the adjustment is made as such, it is possible to reduce vehicle vibrations that occur when the shift position is switched. In addition, it is possible to mitigate the increase in the regeneration amount when the rotation of the motor 2 is switched from reverse rotation to forward rotation.

[0070] After the motor 2 is instructed to output torque in the direction opposite to the rotation direction of the motor 2, it is detected that the motor 2 rotates in the direction opposite to the torque output direction of the motor 2 and a discharge current flows from the battery 4 to the motor 2, whereby the control unit 5 can maintain output of the torque.

[0071] After the motor 2 is instructed to output torque in the direction opposite to the rotation direction of the motor 2, the control unit 5 instructs the motor 2 to stop outputting the torque in the direction opposite to the rotation direction of the motor 2 when a discharge current flowing from the battery 4 to the motor 2 is detected.

[0072] After the motor 2 is instructed to output torque in the direction opposite to the rotation direction of the motor 2, when a current value detected by the current sensor 92 is greater than or equal to the discharge determination threshold, the control unit 5 determines that a discharge current flowing from the battery 4 to the motor 2 is detected.

[0073] When an operation of the accelerator pedal is detected by the accelerator pedal position sensor 94 or an operation of the brake pedal is detected by the brake switch 95, the control unit 5 can instruct the motor 2 to stop outputting the torque in the direction opposite to the direction of rotation of the motor 2.

[0074] The charge determination threshold value and the discharge determination threshold value are acquired by experiments or the like and stored in the ROM of the control unit 5.

[0075] A torque control process executed by the torque control device of the electric vehicle having the above-mentioned configuration according to the other aspect of the example will be described with reference to Fig. 3. Note that when the state of charge of the battery 4 exceeds the predetermined value, the torque control process described below starts and is executed at predetermined time intervals.

[0076] In step S11, the control unit 5 determines whether the shift position sensor 93 detects that the shift position is being changed from the R range to the D range or the L range, or that the shift position is being changed from the D range or the L range to the R range. If the control unit 5 determines that it is not detecting that the shift position is being changed from the R range to the D range or the L range, or that the shift position is being changed from the D range or the L range to the R range, the control unit 5 ends the process.

[0077] When the control unit 5 determines that it is detected that the switching position is changed from the R range to the D range or the L range, or the switching position is changed from the D range or the L range to the R range, the control unit 5 determines in step S12 whether the inverter current detected by the current sensor 92 is less than a charge determination threshold F. If it is determined that the inverter current is not less than the charge determination threshold F, the control unit 5 repeats the process in step S12.

[0078] If it is determined that the inverter current is less than the charge determination threshold F, in step S13, the control unit 5 determines the increased value of the torque of the motor 2 based on the amount of change between the inverter current of the previous process and the inverter current of the current process.

[0079] In step S14, the control unit 5 determines whether the inverter current detected by the current sensor 92 is greater than or equal to a discharge determination threshold G. If it is determined that the inverter current is not greater than or equal to the discharge determination threshold G, the control unit 5 causes the process to return to step S13 and repeats the process.

[0080] When it is determined that the inverter current is greater than or equal to the discharge determination threshold G, the control unit 5 terminates the process.

[0081] The operation of the torque control process is described with reference to Fig. 4 described.

[0082] When a driver switches the shift position from the R range to the D range at a time T1 while the vehicle 1 is reversing by bringing the shift position into the R range, regenerative charging is performed when the rotational speed of the motor 2 is switched from a negative value to a positive value (assuming that the driver drives away by changing the shift position to the D range while parking in a parking lot or the like) because the vehicle 1 moves to output torque in a positive direction.

[0083] At this time, the motor torque is switched from negative torque to positive torque, but the inverter current is changed from discharged to regenerated.

[0084] When the inverter current becomes smaller than the charge determination threshold F, since the battery 4 is overcharged, particularly brought closer to a fully charged state, a motor torque is applied to the motor 2 to reduce the regeneration current, whereby the battery 4 transitions from a regenerated to a discharged state.

[0085] When the inverter current becomes greater than or equal to the discharge determination threshold G, the application of the motor torque is stopped to cause the battery 4 to make a transition to discharge, and a creep torque or the like is output.

[0086] As described above, according to the other aspect of the example, when it is detected that the shift position is changed from the forward shift position to the reverse shift position or from the reverse shift position to the forward shift position in a state where the charge level of the battery 4 has exceeded the predetermined value, and when it is detected that a regeneration current flows from the motor 2 to the battery 4, the motor 2 is instructed to output torque in the direction opposite to the rotation direction of the motor 2 to reduce the regeneration current.

[0087] Therefore, when it is detected that the regeneration current flows from the motor 2 to the battery 4, it is possible to reduce the regeneration current and prevent the battery 4 from being overcharged by outputting a torque to reduce the regeneration current.

[0088] In addition, the increased value of the torque output by the motor 2 is determined in response to the regeneration current flowing from the motor 2 to the battery 4.

[0089] Therefore, it is possible to reduce the regeneration current and prevent the battery 4 from being overcharged by outputting the same amount of torque as the amount of change in the regeneration current.

[0090] After the motor 2 has output a torque in the direction opposite to the rotation direction of the motor 2, the motor 2 additionally maintains the torque in the direction opposite to the rotation direction of the motor 2 when it is detected that the motor 2 is rotating in the direction opposite to the torque output direction of the motor 2 and a discharge current flows from the battery 4 to the motor 2.

[0091] Therefore, when it is detected that the rotation direction of the motor 2 is opposite to the torque output direction of the motor 2 and a discharge current flows from the battery 4 to the motor 2, it is possible to prevent the battery 4 from being overcharged because no regeneration current is generated.

[0092] When the speed of motor 2 is very low and motor 2 rotates in a negative direction, a discharge current flows in the entire system because the power consumption to drive motor 2 and inverter 3 exceeds the regeneration current regenerated by motor 2.

[0093] In addition, when an operation of the accelerator pedal or an operation of the brake pedal is detected, the motor 2 is instructed to stop outputting the torque in the direction opposite to the direction of rotation of the motor 2.

[0094] Therefore, when it is detected that the vehicle 1 is prevented from sliding down by the driver by operating the accelerator pedal or the brake pedal, it is possible to stop the output of the torque and prevent the battery 4 from being discharged.

[0095] According to the example and the other aspect of the example, the rotational direction of the engine 2 is detected by the speed sensor 91, but may be detected by the wheel speed sensor 96.

[0096] According to the example, the control unit 5 performs various determinations or calculations based on information from various sensors, but this invention is not limited to such a configuration. The electric vehicle 1 may include a communication unit capable of communicating with a device not mounted in the vehicle, such as an external server. The device not mounted in the vehicle may perform various determinations or calculations based on detection information from various sensors transmitted from the communication unit. The control unit 5 may receive determination results or calculation results via the communication unit and perform various controls using the received determination results or calculation results.

[0097] While the example of this invention has been described, it is obvious that one skilled in the art could make changes without departing from the scope of this invention. Any and all such modifications and equivalents are intended to be included in the present invention. DESCRIPTION OF REFERENCE NUMBERS 1 electric vehicle 2 engines 3 inverters 4 Battery (DC power source) 5 Control unit 91 Speed ​​sensor 92 Current sensor 93 Switch position sensor 94 Accelerator pedal position sensor 95 brake switch

Claims

[1] Torque control device of an electric vehicle (1), comprising: a DC power source (4); a motor (2); and an inverter (3) for converting a DC power of the DC power source (4) into an AC power to supply the AC power to the motor (2) and for converting an AC power output from the motor (2) into a DC power to supply the DC power to the DC power source (4), the torque control device further comprising: a control unit (5) configured to instruct the motor (2) to output a torque in a direction reverse to a rotation direction of the motor (2) to reduce the regeneration current when it is detected that the motor (2) rotates in a direction reverse to a torque output direction of the motor (2) in a state in which a charge level of the DC power source (4) has exceeded a predetermined value, and when it is detected that the regeneration current flows from the motor (2) to the DC power source (4), and wherein the control unit (5) sets a torque to reduce the regeneration current in response to the change amount of the regeneration current. [2] The torque control device of the electric vehicle (1) according to claim 1, wherein, when the motor (2) outputs the torque in a direction opposite to the rotation direction of the motor (2), when it is detected that the motor (2) rotates in the direction opposite to the torque output direction of the motor (2) and a discharge current flows from the DC power source (4) to the motor (2), the control unit (5) instructs the motor (2) to maintain output of the torque in the direction opposite to the rotation direction of the motor (2). [3] The torque control device of the electric vehicle (1) according to claim 1, wherein, when an operation of an accelerator pedal or a brake pedal is detected, the control unit (5) instructs the motor (2) to stop outputting the torque in the direction opposite to the rotation direction of the motor (2).

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