vehicle

Abstract

To provide a vehicle capable of ensuring braking force even when an input limitation of the electric power of a battery occurs.SOLUTION: A vehicle 1 comprises: a battery 6 capable of being charged by the electric power generated during regeneration by each of a plurality of motors; a detection device 11 configured to detect electric power information relating to the electric power state of the battery 6; and a control device 12 configured to regenerate using a motor that has a greater regenerative loss characteristic among the plurality of motors when it is determined that the input limitation of the electric power is performed in the battery 6 during the regeneration on the basis of the electric power information.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a vehicle.

Background Art

[0002] Patent Document 1 describes an electric vehicle in which one of an electric motor for driving the front wheels and an electric motor for driving the rear wheels is constituted by a permanent magnet type motor and the other is constituted by a magnetless motor. This electric vehicle drives the permanent magnet type motor at low vehicle speeds and drives only with the magnetless motor at high speeds.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in Patent Document 1, when there is a power input limit due to the battery being in a fully charged state or a low temperature state, etc., when the driver releases the accelerator and decelerates without using the hydraulic brake, the electric vehicle cannot decelerate by regeneration of the motor, and there is a problem that the deceleration is insufficient.

[0005] The present disclosure has been made in view of the above, and an object thereof is to provide a vehicle capable of ensuring braking force even when there is a power input limit of the battery.

Means for Solving the Problems

[0006] To solve the above-mentioned problems and achieve the objective, the vehicle according to this disclosure comprises a plurality of motors with different regenerative loss characteristics, a battery that can be charged by the power generated during regeneration of each of the plurality of motors, a detection device for detecting power information relating to the power state of the battery, and a control device that, based on the power information, determines that the battery is limiting the power input during regeneration, and then causes regeneration to be performed using the motor with the larger regenerative loss characteristics among the plurality of motors. [Effects of the Invention]

[0007] According to this disclosure, the braking force can be ensured even when battery input is limited. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram showing a vehicle according to one embodiment. [Figure 2] Figure 2 is a diagram illustrating the characteristics of a PM motor and an SR motor equipped in a vehicle according to one embodiment. [Figure 3] Figure 3 is a flowchart illustrating the overview of the processes performed by a control device in a vehicle according to one embodiment during deceleration. [Figure 4] Figure 4 is a diagram illustrating the characteristics of the PM motor and SR motor during regeneration while limiting the power input to the battery of a vehicle according to one embodiment. [Figure 5] Figure 5 is a diagram illustrating the characteristics of the PM motor and SR motor during regeneration in a vehicle according to one embodiment, without any input restrictions on the battery power. [Modes for carrying out the invention]

[0009] Hereinafter, a vehicle according to an embodiment of the present disclosure will be described with reference to the drawings. Note that the components in the following embodiments include those that are easily substituted or substantially identical to those that are easily substituted by a person skilled in the art. Furthermore, the figures referenced in the following description only schematically show the shape, size, and positional relationships to the extent that the contents of the present disclosure can be understood. In other words, the present disclosure is not limited to the shapes, sizes, and positional relationships exemplified in the figures.

[0010] [Vehicle configuration] Figure 1 is a schematic diagram showing a vehicle according to one embodiment. The vehicle 1 shown in Figure 1 is assumed to be an HEV (Hybrid Electric Vehicle), PHEV (Plug-in Hybrid Electric Vehicle), BEV (Battery Electric Vehicle), FCEV (Fuel Cell Electric Vehicle), etc., equipped with a motor and an engine. In the following description, vehicle 1 will be described as an electric vehicle in which all four wheels are driven by electric motors.

[0011] As shown in Figure 1, the vehicle 1 is equipped with a first motor-generator 2 (hereinafter simply referred to as "first MG2"), a second motor-generator 3 (hereinafter simply referred to as "second MG3"), a first inverter 4 (hereinafter simply referred to as "first INV4"), a second inverter 5 (hereinafter referred to as "second INV5"), a battery 6, a first reduction gear 7, a second reduction gear 8, front wheels 9, rear wheels 10, a detection device 11, and a control device 12.

[0012] The first MG2 is a front-wheel electric motor for driving the front wheels 9. The first MG2 consists of a permanent magnet type motor 21 (hereinafter simply referred to as "PM motor 21") using at least permanent magnets. The PM motor 21 is capable of functioning as both a motor and a generator. The PM motor 21 is electrically connected to the battery 6 via the first inverter 4. The PM motor 21 is power-transmittingly connected to the front wheels 9 via the first reduction gear 7 and a differential device (not shown). That is, the torque of the first MG2 is transmitted only to the front wheels 9.

[0013] The second MG3 is a rear-wheel electric motor for driving the rear wheels 10. The second MG3 is composed of at least a magnet-less synchronous reluctance motor 31 (hereinafter simply referred to as "SR motor 31") that does not use permanent magnets. For example, the SR motor 31 may be a wound-field motor, induction motor, switched reluctance motor, etc., as a magnet-less motor. The SR motor 31 can function as both a motor and a generator. The SR motor 31 is electrically connected to the battery 6 via the second inverter 5. The SR motor 31 is power-transmittingly connected to the rear wheels 10 via the second reduction gear 8 and differential device (not shown). That is, the torque of the second MG3 is transmitted only to the rear wheels 10. Note that the arrangement of the front and rear motors may be reversed. That is, a configuration with magnet-less motors for the front wheels and magnet motors for the rear wheels is also possible.

[0014] The first inverter 4, under the control of the control device 12, has the function of converting DC power supplied from the battery 6 into AC power and supplying it to drive, for example, the PM motor 21 which serves as a power source for driving, and the function of converting AC power supplied from the PM motor 21 into DC power for battery charging. Specifically, the first inverter 4 converts the DC power of the battery 6 into AC power and supplies it to the PM motor 21, generating driving force for the PM motor 21. The first inverter 4 also converts the regenerative AC power of the PM motor 21 back into DC power and supplies it to the battery 6 for charging. The first inverter 4 may further have a DC / DC conversion function to step up or step down the voltage of the DC power.

[0015] The second inverter 5, under the control of the control device 12, has the function of converting DC power supplied from the battery 6 into AC power and supplying it to drive, for example, an SR motor 31 which serves as a power source for driving, and the function of converting AC power supplied from the SR motor 31 into DC power for battery charging. Specifically, the first inverter 4 converts the DC power of the battery 6 into AC power and supplies it to the SR motor 31, generating driving force for the SR motor 31. The first inverter 4 also reverse-converts the regenerative AC power of the SR motor 31 into DC power and supplies it to the battery 6 for charging. The second inverter 5 may further have a DC / DC conversion function to step up or step down the voltage of the DC power.

[0016] Battery 6 is constructed using a battery pack in which multiple battery cells are connected in series. Battery 6 uses a rechargeable secondary battery such as a lithium-ion battery.

[0017] The detection device 11 detects the accelerator opening, the vehicle speed of the vehicle 1, power information related to the power status of the battery 6, the motor rotation speed of the PM motor 21, and the motor rotation speed of the SR motor 31. The detection device 11 is composed of various sensors. For example, the detection device 11 is composed of a voltmeter, ammeter, acceleration sensor, gyro sensor, temperature sensor, etc.

[0018] The control device 12 is composed of an ECU (Electronic Control Unit) using a processor having hardware such as a memory and a CPU (Central Processing Unit). The control device 12 controls each part constituting the vehicle 1. The control device 12 includes an acquisition unit 121, a calculation unit 122, a determination unit 123, and a drive control unit 124.

[0019] The acquisition unit 121 acquires, from the detection device 11, the accelerator opening degree, the vehicle speed of the vehicle 1, the motor rotation speeds of the PM motor 21 and the SR motor 31 respectively, and power information regarding the power state of the battery 6.

[0020] The calculation unit 122 calculates a driving force based on the accelerator opening degree acquired by the acquisition unit 121, the vehicle speed of the vehicle 1, and the motor rotation speeds of the PM motor 21 and the SR motor 31 respectively.

[0021] The determination unit 123 determines whether the battery 6 is under power input restriction based on the power information acquired by the acquisition unit 121. Further, the determination unit 123 determines whether the driving mode of the vehicle 1 determined by the drive control unit 124 described later is a single-motor driving mode.

[0022] The drive control unit 124 determines a driving mode based on the driving force calculated by the calculation unit 122. The drive control unit 124 determines a dual-motor driving mode in which the PM motor 21 and the SR motor 31 are each driven or a single-motor driving mode in which one of the PM motor 21 and the SR motor 31 is driven based on whether the driving force calculated by the calculation unit 122 is greater than a predetermined value.

[0023] 〔Characteristics of Each Motor〕 Next, the characteristics of the PM motor 21 and the SR motor 31 will be explained. Figure 2 is a diagram for comparing and explaining the characteristics of the PM motor 21 and the SR motor 31. In Figure 2, the horizontal axis represents motor rotation speed (vehicle speed), and the vertical axis represents motor torque (driving force). In Figure 2, curve L1 shows the deceleration when the accelerator is released (deceleration due to engine braking). Curve L2 shows the boundary timing for switching between the PM motor 21 and the SR motor 31. In the example shown in Figure 2, the explanation assumes that the PM motor 21 and the SR motor 31 have the same maximum output and size.

[0024] As shown in regions D1 and D2 of Figure 2, the PM motor 21 is efficient at low rotation speeds and medium to high loads. However, at high rotation speeds, it uses back electromotive force to control a weaker magnetic field, which worsens losses due to current generation and heat generation. Furthermore, the PM motor 21 has greater losses than the SR motor 31 even during no-load operation due to magnet drag losses. In contrast, as shown in region D3 of Figure 2, the SR motor 31 has no magnet drag losses and no back electromotive force, resulting in better no-load losses and high-speed losses than the PM motor 21. Thus, the PM motor 21 and the SR motor 31 have different loss characteristics in their regenerative output during regeneration.

[0025] [Processing by the control device] Next, we will explain the processes that the control device 12 performs during deceleration. Figure 3 is a flowchart showing an overview of the processes that the control device 12 performs during deceleration.

[0026] As shown in Figure 3, the acquisition unit 121 acquires power information from the detection device 11, including the accelerator opening, the vehicle speed of the vehicle 1, the motor rotation speeds of the PM motor 21 and the SR motor 31 respectively, and the power status of the battery 6 (step S101).

[0027] Next, the calculation unit 122 calculates the driving force based on the accelerator opening, vehicle speed of vehicle 1, and motor rotation speeds of the PM motor 21 and SR motor 31 respectively, acquired by the acquisition unit 121 (step S102). Specifically, the calculation unit 122 calculates the torque of the PM motor 21 and SR motor 31 respectively, based on the accelerator opening, vehicle speed of vehicle 1, motor rotation speed of the PM motor 21, and motor rotation speed of the SR motor 31 acquired by the acquisition unit 121. The calculation unit 122 may also calculate the driving force by further taking into account the driving state of vehicle 1 using the acceleration detected by the detection device 11. For example, the calculation unit 122 may determine whether vehicle 1 is going uphill or downhill based on the acceleration detected by the detection device 11, and calculate the driving force based on the information obtained by adding the accelerator opening, vehicle speed of vehicle 1, and motor rotation speeds of the PM motor 21 and SR motor 31 respectively, acquired by the acquisition unit 121 to this determination result.

[0028] Subsequently, the drive control unit 124 determines the driving mode based on the driving force calculated by the calculation unit 122 (step S103). Specifically, if the driving force calculated by the calculation unit 122 is greater than a predetermined value, the drive control unit 124 determines a dual-motor driving mode in which both the PM motor 21 and the SR motor 31 are driven. Conversely, if the driving force calculated by the calculation unit 122 is not greater than a predetermined value, the drive control unit 124 determines a single-motor driving mode in which either the PM motor 21 or the SR motor 31 is driven.

[0029] Next, the determination unit 123 determines whether the driving mode of vehicle 1 determined by the drive control unit 124 is a single-motor driving mode (step S104). If the determination unit 123 determines that the driving mode of vehicle 1 determined by the drive control unit 124 is a single-motor driving mode (step S104: Yes), the control device 12 proceeds to step S105, which will be described later. On the other hand, if the determination unit 123 determines that the driving mode of vehicle 1 determined by the drive control unit 124 is not a single-motor driving mode (step S104: No), the control device 12 proceeds to step S108, which will be described later.

[0030] In step S105, the determination unit 123 determines whether or not the battery 6 is under power input restriction based on the power information acquired by the acquisition unit 121. If the determination unit 123 determines that the battery 6 is under power input restriction (step S105: Yes), the control device 12 proceeds to step S106, which will be described later. On the other hand, if the determination unit 123 determines that the battery 6 is not under power input restriction (step S105: No), the control device 12 proceeds to step S107, which will be described later.

[0031] In step S106, the drive control unit 124 regenerates power using the motor with the greater loss characteristics at the current vehicle speed, among the PM motor 21 and SR motor 31, based on the vehicle speed of the vehicle 1 and the required torque.

[0032] Figure 4 is a diagram for comparing and explaining the characteristics of the PM motor 21 and the SR motor 31 during regeneration while limiting the power input to the battery 6. As shown in Figure 4, even in region D2 where regeneration with the PM motor 21 is more efficient when the motor torque is low and the motor rotation speed is low, the drive control unit 124 uses the SR motor 31, which has a larger loss characteristic at the current vehicle speed, as shown in region D10 of Figure 4. Similarly, even in region D3 where regeneration with the SR motor 31 is more efficient when the motor torque is low and the motor rotation speed is high, the drive control unit 124 uses the PM motor 21, which has a larger loss characteristic at the current vehicle speed, as shown in region D11 of Figure 4. In this way, the drive control unit 124 can secure braking force equal to the increase in regenerative loss by deliberately using the motor with the worse loss characteristic among the PM motor 21 and the SR motor 31 for regeneration, compared to using the motor with the better loss characteristic. After step S106, the control device 12 proceeds to step S109, which will be described later.

[0033] In step S107, the drive control unit 124 regenerates power using the motor with the lower loss characteristics at the current vehicle speed, from among the PM motor 21 and SR motor 31, based on the vehicle speed of the vehicle 1 and the required torque.

[0034] Figure 5 is a diagram for comparing and explaining the characteristics of the PM motor 21 and the SR motor 31 during regeneration without limiting the power input of the battery 6. As shown in Figure 5, when the motor torque is low and the motor rotation speed is low, the drive control unit 124 determines that regeneration with the PM motor 21 is more efficient in region D2, and therefore regenerates with the PM motor 21 at the current vehicle speed, as shown in region D21 of Figure 5. Similarly, when the motor torque is low and the motor rotation speed is high, the drive control unit 124 determines that regeneration with the SR motor 31 is more efficient in region D3, and therefore regenerates with the SR motor 31, as shown in region D22 of Figure 5. After step S107, the control device 12 proceeds to step S109, which will be described later.

[0035] In step S108, the drive control unit 124 regenerates power using multiple motors based on the vehicle speed and required torque of the vehicle 1. Specifically, the drive control unit 124 regenerates power using the PM motor 21 and the SR motor 31, respectively. After step S108, the control device 12 proceeds to step S109, which will be described later.

[0036] In step S109, the determination unit 123 determines whether or not vehicle 1 has stopped. If the determination unit 123 determines that vehicle 1 has stopped (step S109: Yes), the control device 12 terminates this process. On the other hand, if the determination unit 123 determines that vehicle 1 has not stopped (step S109: No), the control device 12 returns to step S101.

[0037] According to the embodiment described above, if the control device 12 determines, based on the power information of the battery 6, that the battery 6 is limiting the power input during regeneration of the vehicle 1, then regeneration is performed using the motor with the larger loss characteristics at the current vehicle speed among the PM motor 21 and SR motor 31. This ensures that braking force can be secured even when the power input of the battery 6 is limited.

[0038] Furthermore, according to one embodiment, if the control device 12 determines, based on the power information of the battery 6, that the battery 6 is limiting the power input during regeneration of the vehicle 1, then among the PM motor 21 and SR motor 31, the SR motor 31, which has the largest loss characteristics at the current vehicle speed, will be used for regeneration. In this way, even if the power input of the battery 6 is limited, the braking force can be secured with the motor that has the greatest braking force.

[0039] Furthermore, according to one embodiment, since the vehicle 1 is composed of either the PM motor 21 or the SR motor 31, which have different loss characteristics during regeneration, braking force can be secured without using hydraulic brakes, thus reducing the frequency of use of hydraulic brakes and improving the durability of hydraulic brakes.

[0040] Furthermore, according to one embodiment, if the battery 6 determines that it is limiting the power input during regeneration of the vehicle 1, the control device 12 will regenerate using only the SR motor 31, which has the largest loss characteristics at the current vehicle speed, among the PM motor 21 and SR motor 31. Therefore, even if the power input of the battery 6 is limited, braking force can be ensured.

[0041] Furthermore, in a vehicle according to one embodiment, the "control device" described above can be replaced with "control circuit," "control means," and "control unit," etc.

[0042] In this specification, the flowcharts have used expressions such as "first," "then," and "next" to indicate the sequence of processes between steps. However, the order of processes necessary to implement this embodiment is not uniquely determined by these expressions. In other words, the order of processes in the flowcharts described herein can be changed within a reasonable range.

[0043] Further effects and modifications can be readily derived by those skilled in the art. Broader aspects of the present invention are not limited to the specific details and representative embodiments expressed and described above. Accordingly, various modifications are possible without departing from the spirit or scope of the overall concept of the invention as defined by the appended claims and their equivalents.

[0044] Although some embodiments of this application have been described in detail above with reference to the drawings, these are illustrative examples, and the present invention can be implemented in various other forms with modifications and improvements based on the knowledge of those skilled in the art, starting with the embodiments described in the disclosure section of the present invention. [Explanation of symbols]

[0045] 1 vehicle 2. First Motor Generator 3. Second motor generator 4. First inverter 5. Second inverter 6 batteries 7. First Reducer 8. Second reduction gear 9 Front wheels 10 Rear wheels 11 Detection device 12 Control device 21 Permanent magnet motor 31 Synchronous reluctance motor 121 Acquisition Department 122 Calculation Section 123 Judgment section 124 Drive control unit

Claims

[Claim 1] Multiple motors with different loss characteristics during regeneration, A battery that can be charged by the power generated during the regeneration of each of the aforementioned multiple motors, A detection device that detects power information related to the battery's power state, accelerator opening, vehicle speed, and the motor rotation speed of each of the multiple motors, A front-wheel electric motor for driving the front wheels, A rear-wheel electric motor for driving the rear wheels, If, based on the power information, it is determined that the battery is limiting the power input during regeneration, a control device is provided that causes regeneration to be performed using the motor with the largest regenerative loss characteristics among the plurality of motors, Equipped with, Of the aforementioned front wheel motor and rear wheel motor, one is configured as a permanent magnet type motor, and the other is configured as a magnetless motor. The regenerative output of the aforementioned permanent magnet motor is Smaller than the regenerative output of the aforementioned magnetless motor, The control device is Based on the accelerator opening, the speed, and the rotational speed of each of the multiple motors, the driving force is calculated. Based on the aforementioned driving force, the vehicle's driving mode is determined to be either a dual-motor driving mode in which both the permanent magnet motor and the magnet-less motor are driven, or a single-motor driving mode in which either the permanent magnet motor or the magnet-less motor is driven. When the vehicle's driving mode is determined to be the single-motor driving mode, and it is determined that the battery is limiting the power input during regeneration, regeneration is performed only on the magnet-less motor, which has a large regeneration loss characteristic. vehicle.

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