Electric vehicle

Abstract

To achieve desired braking force through regenerative braking by a motor even when a vehicle is switched from driving operation to braking operation.SOLUTION: An electric vehicle comprises: a motor capable of outputting power for traveling and generating electricity; a power storage device connected to a power line to exchange electric power with the motor; an electrical load which operates with the electric power supplied through the power line; and a control device which controls the motor and the electric load. The control device estimates estimated braking force according to a vehicle speed when braking force is not applied to the vehicle, calculates estimated regenerative electric power when the estimated braking force is applied through regenerative control of the motor, and operates the electric load when the estimated regenerative electric power is larger than allowable charging electric power of the power storage device.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an electric vehicle, and more particularly to an electric vehicle equipped with an electric motor that outputs power for running and an electricity storage device. [Background technology]

[0002] Conventionally, for this type of electric vehicle, a system has been proposed that operates the heater of the air conditioner and increases the rotation speed of the compressor of the air conditioner when the power generated by the regenerative operation of the motor is greater than the power that can be charged to the battery (see, for example, Patent Document 1).This allows the regenerative operation of the motor to be performed more appropriately. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-087937 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned electric vehicle, when the vehicle switches from driving operation to braking operation, there are cases where the regenerative power generated by the motor cannot be consumed due to a delay in the operation of the air conditioning system, and the desired braking force cannot be obtained.

[0005] The electric vehicle of the present disclosure has as its main objective the ability to obtain a desired braking force through regenerative braking by the electric motor even when the vehicle switches from driving operation to braking operation. [Means for solving the problem]

[0006] The electric vehicle of the present disclosure employs the following measures to achieve the above-mentioned main object.

[0007] The electric vehicle disclosed herein is an electric motor capable of generating power to output power for running; a power storage device connected to a power line that exchanges power with the electric motor; an electrical load that operates using power supplied from the power line; a control device for controlling the electric motor and the electric load; An electric vehicle comprising: the control device estimates an estimated braking force in accordance with a vehicle speed when no braking force is being applied to the vehicle, calculates estimated regenerative power when the estimated braking force is applied by regenerative control of the electric motor, and operates the electric load when the estimated regenerative power is greater than an allowable charging power of the power storage device. It is characterized by:

[0008] In the electric vehicle disclosed herein, when no braking force is being applied to the vehicle, an estimated braking force is estimated according to the vehicle speed, and an estimated regenerative power is calculated when this estimated braking force is applied through regenerative control of the electric motor. Then, when the estimated regenerative power is greater than the allowable charging power of the power storage device, an electric load is activated. Because the electric load is activated during driving operation in this manner, it is possible to prevent a situation in which the regenerative power of the electric motor cannot be consumed due to a delay in the activation of the electric load when switching from driving operation to braking operation. As a result, the desired braking force can be obtained through regenerative braking by the electric motor even when the vehicle switches from driving operation to braking operation. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing an outline of the configuration of an electric vehicle 20 according to an embodiment of the present disclosure. [Figure 2] 4 is a flowchart showing an example of a braking force adjustment process executed by an electronic control unit 60 according to the embodiment. [Figure 3] 10 is an explanatory diagram showing an example of changes over time in torque Tm of the motor 22, charge / discharge power Wb of the high-voltage battery 30, and power consumption Wc of the temperature regulator 48. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Next, a mode (embodiment) for carrying out the present disclosure will be described. Fig. 1 is a configuration diagram showing an outline of the configuration of an electric vehicle 20 equipped with a control device according to an embodiment of the present disclosure. As shown in Fig. 1, the electric vehicle 20 of the embodiment includes a motor 22, an inverter 24, a high-voltage battery 30, a low-voltage battery 40, a DC / DC converter 44, an auxiliary device 46, a temperature adjustment device 48, and an electronic control unit 60.

[0011] The motor 22 is configured as, for example, a synchronous generator motor. A rotor (not shown) of the motor 22 is connected to a drive shaft 26 that is coupled to drive wheels 29a, 29b via a differential gear 28. A rotational position detection sensor 22a that detects the rotational position of the rotor is attached to the motor 22.

[0012] The inverter 24 is configured as a well-known inverter circuit having six transistors and six diodes. The inverter 24 is connected to a high-voltage power line 32 that is connected to a high-voltage battery 30. The inverter 24 converts DC power from the high-voltage battery 30 into three-phase AC power using PWM control and applies the AC power to the motor 22 to drive the motor 22.

[0013] The high-voltage battery 30 is configured as, for example, a lithium-ion battery. The high-voltage battery 30 is connected to a high-voltage power line 32. A voltage sensor 31a for detecting a battery voltage Vb is attached to both terminals of the high-voltage battery 30. A current sensor 31b for detecting a battery current Ib is attached to a terminal of the high-voltage battery 30. A system main relay 34 for connecting and disconnecting the high-voltage battery 30 is attached to the high-voltage power line 32. A smoothing capacitor 36 is also attached to the high-voltage power line 32. A voltage sensor 36a for detecting a high-voltage voltage VH is attached to the high-voltage power line 32.

[0014] The low-voltage battery 40 is configured as, for example, a lead-acid battery. The low-voltage battery 40 is connected to a low-voltage power line 42. Auxiliary equipment 46 is attached to the low-voltage power line 42. Examples of the auxiliary equipment 46 include wipers, lights, a seat heater, and a steering wheel heater. A smoothing capacitor 43 is also attached to the low-voltage power line 42. A voltage sensor 43a that detects the low-voltage voltage VL is attached to the low-voltage power line 42.

[0015] The DC / DC converter 44 is connected to the high-voltage power line 32 and the low-voltage power line 42. The DC / DC converter 44 is configured as a well-known DC / DC converter. The DC / DC converter 44 steps down the DC power of the high-voltage power line 32 and supplies it to the low-voltage power line 42.

[0016] The electronic control unit 60 is configured as a microcomputer centered around a CPU 62. In addition to the CPU 62, the electronic control unit 60 also includes a ROM 64, a RAM 66, a flash memory (not shown), an input port (not shown), an output port (not shown), and the like.

[0017] The electronic control unit 60 receives, via an input port, the rotational position θ detected by the rotational position detection sensor 22a, the battery voltage Vb detected by the voltage sensor 31a, the battery current Ib detected by the current sensor 31b, the high-voltage system voltage VH detected by the voltage sensor 36a, and the low-voltage system voltage VL detected by the voltage sensor 43a. The electronic control unit 60 also receives a start signal ST from a start switch 70, a shift position SP detected by a shift lever position sensor 72 attached to a shift lever 71, an accelerator opening Acc detected by an accelerator pedal position sensor 74 attached to an accelerator pedal 73, and a brake pedal position BP detected by a brake pedal position sensor 76 attached to a brake pedal 75. The electronic control unit 60 also receives the vehicle speed V detected by a vehicle speed sensor 78 and the acceleration α detected by an acceleration sensor 80. The electronic control unit 60 also receives the power consumption Wc of the temperature adjustment device 48 from the temperature adjustment device 48. The temperature control device 48 may include an air conditioner that conditions the air in the passenger compartment, a seat heater that heats the driver's seat and passenger seat, a steering wheel heater that heats the steering wheel, and the like.

[0018] The electronic control unit 60 outputs a switching control signal to the inverter 24, a drive control signal to the DC / DC converter 44, a drive control signal to the temperature regulator 48, a display control signal to the display 82, and the like via the output port.

[0019] The electronic control unit 60 calculates the rotation speed Nm of the motor 22 based on the rotational position θ of the rotor of the motor 22. The electronic control unit 60 calculates the power storage rate SOC of the high-voltage battery 30 based on the integrated value of the battery current Ib, and calculates input / output limits Win and Wout as the allowable maximum input / output power that may be input to and output from the high-voltage battery 30 based on the power storage rate SOC of the high-voltage battery 30 and the battery temperature Tb.

[0020] Next, the operation of the electric vehicle 20 of this embodiment, particularly the operation when the regenerative braking force of the motor 22 is effectively applied even when the input limit Win of the high-voltage battery 30 is small, will be described. Figure 2 is a flowchart showing an example of a braking force adjustment process executed by the electronic control unit 60.

[0021] When the braking force adjustment process is executed, the electronic control unit 60 first determines whether braking is in progress (step S100). This determination can be made based on whether regenerative control is being performed on the motor 22. If it is determined that braking is in progress, it is determined that this process is not applicable, and this process is terminated.

[0022] If it is determined in step S100 that braking is not in progress, the vehicle speed V from the vehicle speed sensor 78 and the calculated and stored input limit Win of the high-voltage battery 30 are input (step S110), and an estimated braking force Test is calculated based on the vehicle speed V (step S120). The estimated braking force Test may be the braking force that the user normally applies to the vehicle speed V, or may be the maximum braking force possible for the vehicle speed V. In this embodiment, the relationship between the vehicle speed V and the estimated braking force Test is determined in advance by experimentation, machine learning, or the like, and stored as a map for setting the estimated braking force, and when the vehicle speed V is given, the corresponding estimated braking force Test is calculated by deriving it from the map.

[0023] Next, the power regenerated by the motor 22 when the estimated braking force Test is applied by the motor 22 is calculated as the estimated regenerative power Wm (step S130). In this embodiment, the relationship between the estimated braking force Test and the estimated regenerative power Wm is determined in advance by experimentation, machine learning, or the like, and stored as an estimated regenerative power setting map, and when the estimated braking force Test is applied, the corresponding estimated regenerative power Wm is calculated by deriving it from the map.

[0024] Then, it is determined whether the estimated regenerative power Wm is greater than the input limit Win of the high-voltage battery 30 (step S140). If it is determined that the estimated regenerative power Wm is equal to or less than the input limit Win of the high-voltage battery 30, it is determined that the high-voltage battery 30 can accept the regenerative power of the motor 22 during subsequent braking, and this process is terminated. On the other hand, if it is determined that the estimated regenerative power Wm is greater than the input limit Win of the high-voltage battery 30, it is determined that the high-voltage battery 30 cannot accept the regenerative power of the motor 22 during subsequent braking, resulting in insufficient braking force. The temperature adjustment device 48 is operated (step S140), and this process is terminated. The temperature adjustment device 48 is operated so that it consumes power equal to or greater than the difference (Wm - Win) between the estimated regenerative power Wm and the input limit Win of the high-voltage battery 30. As a result, the regenerative power of the motor 22 during subsequent braking can be accepted by the high-voltage battery 30 and consumed by the temperature adjustment device 48, and braking force due to regenerative braking by the motor 22 can be applied to the vehicle.

[0025] FIG. 3 is an explanatory diagram showing an example of time-dependent changes in torque Tm of the motor 22, charging / discharging power Wb of the high-voltage battery 30, and power consumption Wc of the temperature regulator 48 when switching from driving to braking. In the diagram, the solid line represents the results obtained when the braking force adjustment process of the embodiment is performed, and the dashed-dotted line represents the results obtained when the temperature regulator 48 is activated after braking as a comparative example. In the embodiment, when the estimated regenerative power Wm exceeds the input limit Win of the high-voltage battery 30 at time T1, the temperature regulator 48 is activated. As the power consumption of the temperature regulator 48 increases, the discharge power Wb of the high-voltage battery 30 increases. When the driver releases the accelerator pedal 73 at time T2 and depresses the brake pedal 75 at time T3, torque Tm of the motor 22 becomes negative, and the charging power Wb of the high-voltage battery 30 is limited by the input limit Win. However, because the temperature regulator 48 is activated, the regenerative power generated by the regenerative control of the motor 22 is consumed by the temperature regulator 48. Therefore, the braking torque Tm of the motor 22 becomes the desired braking torque achieved by regeneratively controlling the motor 22. On the other hand, in the comparative example, the operation of the temperature adjustment device 48 starts after time T3 when the driver depresses the brake pedal 75, but due to this delay, the temperature adjustment device 48 is unable to consume sufficient power, and the braking torque Tm of the motor 22 becomes smaller than the desired braking torque achieved by regeneratively controlling the motor 22.

[0026] In the electric vehicle 20 of the embodiment described above, when not braking, an estimated braking force Test is calculated based on the vehicle speed V, and the power regenerated by the motor 22 when the estimated braking force Test is applied by the motor 22 is calculated as estimated regenerative power Wm, and when it is determined that the estimated regenerative power Wm is greater than the input limit Win of the high-voltage battery 30, the temperature adjustment device 48 is activated. As a result, the regenerative power of the motor 22 during subsequent braking can be consumed by the high-voltage battery 30 and the temperature adjustment device 48, and braking force due to regenerative braking by the motor 22 can be applied to the vehicle. As a result, a desired braking force can be obtained by regenerative braking by the motor 22 even when the vehicle switches from driving operation to braking operation.

[0027] In the embodiment, the electric vehicle 20 is configured to have a high-voltage battery 30, a motor 22, and a temperature control device 48, but it may also be configured as a hybrid vehicle having an engine, a battery, a motor, and a temperature control device, or as a fuel cell vehicle having a fuel cell, a battery, a motor, and a temperature control device.

[0028] The correspondence between the main elements of the embodiment and the main elements of the invention described in the "Means for Solving the Problem" section will be explained below. In the embodiment, the motor 22 corresponds to the "electric motor," the high-voltage battery 30 corresponds to the "electric storage device," the temperature regulator 48 corresponds to the "electric load," and the electronic control unit 60 corresponds to the "control device."

[0029] The correspondence between the main elements of the embodiments and the main elements of the invention described in the "Means for Solving the Problem" section does not limit the elements of the invention described in the "Means for Solving the Problem" section, because the embodiments are examples for specifically explaining the invention described in the "Means for Solving the Problem" section. In other words, the interpretation of the invention described in the "Means for Solving the Problem" section should be based on the description in that section, and the embodiments are merely specific examples of the invention described in the "Means for Solving the Problem" section.

[0030] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to these embodiments, and it goes without saying that the present disclosure can be embodied in various forms without departing from the spirit of the present disclosure. [Industrial Applicability]

[0031] The present disclosure is applicable to the electric vehicle manufacturing industry and the like. [Explanation of symbols]

[0032] 20 electric vehicle, 22 motor, 24 inverter, 26 drive shaft, 28 differential gear, 29a, 29b drive wheels, 30 high-voltage battery, 31a voltage sensor, 31b current sensor, 32 high-voltage power line, 34 system main relay, 36 capacitor, 36a voltage sensor, 40 low-voltage battery, 42 low-voltage power line, 43 capacitor, 43a voltage sensor, 44 DC / DC converter, 46 auxiliary equipment, 48 temperature control device, 60 electronic control unit, 62 CPU, 64 ROM, 66 RAM, 70 start switch, 71 accelerator pedal, 72 accelerator pedal position sensor, 73 brake pedal, 74 brake pedal position sensor, 75 shift lever, 76 shift position sensor, 78 vehicle speed sensor, 80 acceleration sensor, 82 display.

Claims

[Claim 1] an electric motor capable of generating power to output power for running; a power storage device connected to a power line that exchanges power with the electric motor; an electrical load that operates using power supplied from the power line; a control device for controlling the electric motor and the electric load; An electric vehicle comprising: the control device estimates an estimated braking force in accordance with a vehicle speed when no braking force is being applied to the vehicle, calculates estimated regenerative power when the estimated braking force is applied by regenerative control of the electric motor, and operates the electric load when the estimated regenerative power is greater than an allowable charging power of the power storage device. An electric vehicle characterized by:

Images