control device

Abstract

The present invention provides a control device that can control the discharge of batteries installed in electric vehicles while suppressing a decline in drivability. [Solution] The control device 8 includes a control unit that controls the power discharged from a battery mounted on the electric vehicle that stores power for driving, according to the gradient of the road on which the electric vehicle travels, and the control unit reduces the power rate of the maximum battery discharge amount discharged from the battery when the gradient tends to increase.

Description

Technical Field

[0001] The present disclosure relates to a control device.

Background Art

[0002] Patent Document 1 discloses a technique capable of effectively avoiding an overload applied to a traveling motor during uphill driving or the like, even when controlling the motor speed in an open-loop manner according to the depression amount of an accelerator pedal. Patent Document 2 discloses a technique for ensuring a cruising range by using the remaining capacity of a battery without waste even when the outside air temperature is high in an electric vehicle powered by a secondary battery. Patent Document 3 discloses a technique for appropriately issuing a warning indicating that the output of the driving force for traveling is limited according to the road conditions.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] If the discharge power from the battery installed in an electric vehicle remains at a high output for a predetermined period of time, the maximum discharge capacity of the battery will decrease to prevent the battery from overheating, for example, and the vehicle speed will decrease accordingly. Here, if the maximum discharge capacity of the battery changes at a constant power rate regardless of driving conditions, the deceleration of the vehicle will increase as the gradient of the uphill slope increases. For example, if the power rate when an electric vehicle is driving on a road with a 0% uphill gradient and the discharge power remains at a high output for a predetermined period of time is the same as the power rate when the same vehicle is driving on a road with a 30% uphill gradient and the discharge power remains at a high output for a predetermined period of time, the vehicle speed will decrease as the gradient increases. In this way, the deceleration tends to increase on uphill slopes, so even if the accelerator is pressed harder, the vehicle speed will decrease, which may feel strange to the driver.

[0005] This disclosure provides a control device that can control the discharge of a battery installed in an electric vehicle while suppressing a decrease in drivability. [Means for solving the problem]

[0006] A control device according to one aspect of the present disclosure includes a control unit that controls the power discharged from a battery mounted on an electric vehicle for storing power for driving, according to the gradient of the road on which the electric vehicle travels, wherein the control unit reduces the power rate of the maximum battery discharge amount discharged from the battery when the gradient tends to increase. [Effects of the Invention]

[0007] According to this disclosure, it is possible to provide a control device that can control the discharge of a battery installed in an electric vehicle while suppressing a decrease in drivability. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a configuration diagram of a vehicle 100 including a control device 8 according to an embodiment of the present disclosure. [Figure 2] Figure 2 is a hardware configuration diagram of the control device 8 according to an embodiment of this disclosure. [Figure 3]Figure 3 is a hardware configuration diagram of the control device 8 according to an embodiment of this disclosure. [Figure 4] Figure 4 is a functional block diagram implemented by the processor 81a of the control unit 8. [Figure 5] Figure 5 is a diagram illustrating the function of the control device 8. [Figure 6] Figure 6 is a diagram illustrating the function of the control device 8. [Figure 7] Figure 7 is a flowchart illustrating the operation of the control device 8. [Figure 8] Figure 8 is a diagram illustrating the operation of the control device in the comparative example. [Figure 9] Figure 9 is a diagram illustrating the operation of the control device in the comparative example. [Figure 10] Figure 10 is a flowchart illustrating the operation of the control device 8 in a modified example. [Figure 11] Figure 11 is a diagram illustrating the operation of the control device 8 in a modified example. [Modes for carrying out the invention]

[0009] Hereinafter, one aspect of this disclosure will be described with reference to the drawings. Note that the drawings used in the following description are all schematic, and the dimensional relationships and ratios of the elements shown in the drawings do not necessarily correspond to reality. Furthermore, this disclosure is not limited in any way to the following embodiments, and can be implemented with appropriate modifications within the scope of this disclosure.

[0010] Figure 1 is a diagram showing the configuration of a vehicle 100 including a control device 8 according to an embodiment of the present disclosure. The vehicle 100 may be interpreted as a battery electric vehicle (BEV) powered by a battery 6 for storing power for driving and a motor 7. However, the vehicle 100 is not limited to a BEV and may include hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), etc., equipped with a battery 6.

[0011] Vehicle 100 may include a battery 6, a motor 7, and a control device 8. The battery 6 may be interpreted as an energy storage device including multiple cells. The battery 6 may store power to drive the motor 7 and power regenerated from the motor 7.

[0012] Motor 7 may be interpreted as a main motor for vehicle propulsion, a three-phase AC motor, etc. Motor 7 rotates using AC power from the control device 8, thereby providing driving torque to the drive wheels 1 of the vehicle 100 and propelling the vehicle 100. Hereafter, motor 7 may be referred to as MG (Motor Generator).

[0013] The control device 8 can be interpreted as a device that controls the current, voltage, power, etc. that drives the MG based on information from the sensor group, such as torque commands, speed commands, and position commands for the MG. Specifically, the control device 8 may drive the MG by converting the DC voltage discharged from the battery 6 into a three-phase AC voltage and applying the three-phase AC voltage to the MG. The control device 8 may also have a function to charge the battery 6 by converting the AC power regenerated from the MG into DC power and supplying the DC power to the battery 6.

[0014] The sensor group may include an acceleration sensor 2, a steering angle sensor 3, a rotation sensor 4, a current sensor group 5, a gradient sensor 9, etc. The acceleration sensor 2 may detect the depression amount (acceleration opening) of the accelerator pedal and output a signal corresponding to the detected acceleration opening. The steering angle sensor 3 may detect the steering angle of the steering wheel (steering handle) and output a signal voltage corresponding to the detected steering angle. The rotation sensor 4 may detect the rotation angle of the MG and output a signal corresponding to the detected rotation angle.

[0015] The current sensor group 5 may include a current sensor that detects the current of the first phase of the three-phase alternating current, a current sensor that detects the current of the second phase of the three-phase alternating current, and a current sensor that detects the current of the third phase of the three-phase alternating current. The first phase may be interpreted as the U phase, the second phase as the V phase, and the third phase as the W phase. Each current sensor may be interpreted as a sensor that converts the phase current detected by, for example, a shunt resistor into a voltage and outputs a voltage corresponding to the value of the current. The shunt resistor may detect the current of the three-phase wiring provided between the control device 8 and the MG.

[0016] The gradient sensor 9 may detect the gradient of the road surface on which the vehicle 100 travels and output a signal indicating the detected gradient value.

[0017] Next, a configuration example of the control device 8 will be described with reference to FIGS. 2 and 3. FIGS. 2 and 3 are hardware configuration diagrams of the control device 8 according to an embodiment of the present disclosure.

[0018] As shown in Figure 2, the control device 8 may include an inverter 81 and a control unit 82. The inverter 81 may include a plurality of switching elements. Specifically, it may include three upper arm switching elements and three lower arm switching elements. The inverter 81 converts the control signal (which may be interpreted as a gate signal, PWM signal, etc.) output from the control unit 82 into a signal with a voltage capable of driving these switching elements (gate drive signal), and inputs the converted gate drive signal to the gate of each switching element. As a result, the upper arm switching elements and the lower arm switching elements switch complementaryly, and the DC voltage, which is the output voltage of the battery 6, is converted into a three-phase AC voltage and supplied to the MG. At this time, U-phase current (U-phase AC current), V-phase current (V-phase AC current), and W-phase current (W-phase AC current) flow through each of the three wires connected to the output of the inverter 81.

[0019] The current sensor group 5 may include a U-phase current sensor 51 for detecting U-phase current, a V-phase current sensor 52 for detecting V-phase current, and a W-phase current sensor 53 for detecting W-phase current. The U-phase current sensor 51 may be interpreted as a current sensor that detects the current of the first phase of a three-phase AC. The V-phase current sensor 52 may be interpreted as a current sensor that detects the current of the second phase of a three-phase AC. The W-phase current sensor 53 may be interpreted as a current sensor that detects the current of the third phase of a three-phase AC. Hereinafter, when the U-phase current sensor 51, V-phase current sensor 52, and W-phase current sensor 53 are not distinguished, they may simply be referred to as "current sensors". The current value output by each current sensor is the voltage corresponding to the detected current, and therefore may be interpreted as the sensor output voltage.

[0020] The control unit 82 may generate a signal (corresponding to the control signal mentioned above) that converts a DC voltage to an AC voltage based on the output voltages of at least two of the three current sensors, and output it to the inverter 81. That is, the control unit 82 may use the output voltages from two current sensors that detect the current of any two of the three phases as detection currents, and may calculate the current of the remaining phase from the output voltages of these two current sensors, and use the calculated current as the detection current of the remaining phase.

[0021] As shown in Figure 3, the control unit 82 may include a processor 81a, memory 81b, communication interface 81c, and input / output interface 81d. These may be connected to each other via a bus 81e so as to be able to communicate with each other.

[0022] The processor 81a may be interpreted as a central processing unit. The processor 81a may execute various programs and control various parts. The processor 81a may read the motor control program 81b1 from memory 81b and execute specific processing by expanding the motor control program 81b1. The functions realized by the motor control program 81b1 will be described later.

[0023] The communication interface 81c can be interpreted as an interface for the control device 8 to communicate with other devices. Standards such as CAN (Controller Area Network), Ethernet (registered trademark), and Wi-Fi (registered trademark) may be used for the communication interface 81c. The input / output interface 81d may receive information detected by the accelerator sensor 2, steering angle sensor 3, rotation sensor 4, current sensor group 5, etc., as shown in Figure 1.

[0024] Next, the functions of the control device 8 will be described with reference to Figure 4 and the like. Figure 4 is a functional block diagram of the processor 81a of the control device 8. The processor 81a may include an input unit 81a1, a power rate control unit 81a2, and a drive processing unit 81a3. The input unit 81a1, the power rate control unit 81a2, and the drive processing unit 81a3 may be realized by the processor 81a executing a motor control program 81b1. The power rate control unit 81a2 may be interpreted as the control unit of this disclosure.

[0025] (Input section 81a1) The input unit 81a1 may receive information detected by the accelerator sensor 2, steering angle sensor 3, rotation sensor 4, current sensor group 5, gradient sensor 9, etc.

[0026] (Power rate control unit 81a2) The power rate control unit 81a2 may control the power discharged from the battery 6 mounted on the vehicle 100, which stores power for driving, according to the gradient detected by the gradient sensor 9. Specifically, the power rate control unit 81a2 may reduce the power rate of the maximum battery discharge amount discharged from the battery 6 when the gradient tends to increase. The power rate may be interpreted as the rate of change per unit time [kW / s] of the maximum battery discharge amount (Wout) [kW]. These units are, for example, kW / s. For example, the power rate control unit 81a2 may set the power rate to X when the gradient is 0%, set the power rate to X' which is smaller than X when the uphill gradient becomes +3%, and set the power rate to X'' which is even smaller than X' when the uphill gradient increases further to +5%. After setting the power rate in this way, the power rate control unit 81a2 may change the power rate from X'' to X' when the value of the uphill gradient decreases, for example from +5% to +3%.

[0027] Figure 5 shows the vehicle speed and power discharged from battery 6 when the gradient is 0%, and Figure 6 shows the vehicle speed and power discharged from battery 6 when the gradient is 30%. The dashed line represents vehicle speed, the regular solid line represents the power required for driving, the thick solid line represents battery power, the double-dash line represents the maximum battery discharge amount (Wout), and the dashed line represents the limit value.

[0028] As shown in Figure 5, when the gradient is 0%, the accelerator opening increases, causing the vehicle speed to increase until time t1. A high-power state is maintained from time t1 until a predetermined time ta has elapsed. At time 2, after the predetermined time ta has elapsed, the maximum battery discharge amount (Wout) decreases according to a specific power rate, as indicated by the symbol A, in order to protect the battery.

[0029] On the other hand, as shown in Figure 6, when the gradient is 30%, the power rate decreases from time 2, as indicated by the sign B. However, the power rate at this time is lower than the power rate when the gradient is 0%, and the maximum battery discharge (Wout) is gradually limited. This prevents the vehicle speed from decreasing too much in relation to the driver's accelerator opening on an uphill slope, thus reducing the driver's sense of discomfort.

[0030] By reducing the power rate according to the gradient in this way, even if a power limit is imposed in situations where the vehicle speed tends to decrease easily, such as when driving uphill, it is possible to suppress a significant decrease in the power rate, thereby preventing abrupt changes in the deceleration of vehicle 100. Consequently, it is possible to suppress the decline in drivability that accompanies changes in deceleration.

[0031] Furthermore, the power rate control unit 81a2 may be configured to select to reduce the power rate according to the gradient under certain conditions. For example, when a driving mode prioritizing fuel-efficient driving is selected, the power rate control unit 81a2 may set the same power rate as when the gradient is 0%, and when a driving mode prioritizing drivability is selected, it may reduce the power rate as the gradient increases. This allows for driving that prioritizes drivability while reducing power consumption by increasing the power rate when fuel-efficient driving is desired.

[0032] (Another configuration example of the power rate control unit 81a2 1) The power rate control unit 81a2 may control the power rate using a map that associates gradients with power rates. The map may associate, for example, multiple gradient values ​​that differ by 1% increments from -10% to +10% with multiple power rates of different values ​​corresponding to each of these gradients. Here, the power rate may be set to decrease by, for example, a certain percentage as the gradient value increases. In other words, the power rate decreases as the gradient increases, and the power rate increases as the gradient decreases.

[0033] By using a map that correlates the gradient with the power rate in this way, the computational processing load on the control device 8 can be reduced, and the deterioration of drivability due to processing delays can be further suppressed.

[0034] (Drive processing unit 81a3) The drive processing unit 81a3 may control the driving force generated by the MG based on information detected by the accelerator sensor 2, steering angle sensor 3, rotation sensor 4, current sensor group 5, etc., and the power rate. For example, the driving force generated by the MG may be controlled by discharging battery power in response to the driving power required according to the accelerator opening.

[0035] Next, the operation of the control device 8 will be explained with reference to Figure 7. Figure 7 is a flowchart for explaining the operation of the control device 8. The process shown in Figure 7 may start, for example, when the vehicle 100 starts moving and, for example, when the accelerator opening is increased. In step S1, if the battery power is in a high output state due to, for example, the accelerator being pressed further, the control device 8 performs the process in step S2, and if the battery power is not in a high output state, it performs the process in step S4.

[0036] In step S2, the control device 8 determines whether there is a gradient based on the gradient information. If there is a gradient, it performs the process in step S3. If there is no gradient (for example, if the gradient is between +1° and -1°), it performs the process in step S4.

[0037] In step S3, the control device 8 reduces the power rate, and in step S4, it determines whether the high-output state continues for a predetermined time. If the high-output state continues for a predetermined time, in step S5, it limits the power (for example, limiting the battery power to the limit value shown in Figure 6). If the high-output state does not continue for a predetermined time, it terminates the series of processes without limiting the power.

[0038] Figures 8 and 9 are diagrams illustrating the operation of the control device in the comparative example. Figure 8 shows the vehicle speed and the power discharged from battery 6 when the gradient is 0%, and Figure 9 shows the vehicle speed and the power discharged from battery 6 when the gradient is 30%. The dashed line represents vehicle speed, the regular solid line represents the power required for driving, the thick solid line represents battery power, the double-dashed line represents the maximum battery discharge amount (Wout), and the dashed line represents the limit value.

[0039] When the gradient is 0%, the vehicle speed increases until time t1 as the accelerator opening increases when the gradient is 0%, and a high-power state is maintained from time t1 until a predetermined time ta has elapsed. At time 2, after the predetermined time ta has elapsed, the maximum battery discharge amount (Wout) decreases according to a specific power rate as indicated by the symbol A, in order to protect the battery.

[0040] On the other hand, as shown in Figure 9, when the gradient is 30%, the power rate is equal to the power rate when the gradient is 0%, as indicated by the symbol B, and the maximum battery discharge (Wout) is abruptly limited. As a result, the vehicle speed drops too much in relation to the driver's accelerator opening on an uphill slope, causing the driver to feel uncomfortable.

[0041] In contrast, the control device 8 of this disclosure controls the power rate to decrease as the gradient increases, so that even if power limiting intervenes in situations where deceleration is likely to occur on an uphill slope, a large decrease in the power rate can be suppressed, thereby suppressing a decline in drivability.

[0042] (Modified version of the power rate control unit 81a2) The power rate control unit 81a2 may not change the timing at which it starts to reduce the power rate if it is not expected to reduce the power rate, but may advance the timing at which it starts to reduce the power rate if it is expected to reduce the power rate. Specifically, if it is expected to reduce the power rate, the power rate control unit 81a2 may advance the timing at which it intervenes in controlling the power rate as the gradient increases. For example, the power rate control unit 81a2 may use information on signs captured by an onboard camera, terrain information obtained from a map, etc., to predict that the gradient of the road on which the vehicle 100 is traveling may increase from the current gradient after a certain period of time has elapsed or after a certain distance has been traveled since the sign was detected, and may also predict the value of that gradient. The power rate control unit 81a2 may predict that the gradient of the road surface being traveled will increase from 0% to 3% 10 seconds after a specific time (the current time), and may change the power rate to a power rate corresponding to the predicted gradient between the time of prediction and the time the vehicle 100 reaches the point where the gradient actually begins to change.

[0043] By starting to reduce the power rate earlier in this way, discharge can be limited sooner, and because discharge suppression begins earlier, the amount of discharge from battery 6 is reduced. Therefore, the vehicle 100 can run for a longer time while minimizing the decrease in drivability.

[0044] Next, the operation of the control device 8 will be explained with reference to Figures 10 and 11. Figure 10 is a flowchart illustrating the operation of the control device 8 according to a modified example, and Figure 11 is a diagram illustrating the operation of the control device 8 according to a modified example. The process shown in Figure 10 may start, for example, when the vehicle 100 starts moving and, for example, when the accelerator opening becomes large. The difference from the flowchart in Figure 7 is that step S31 is added after step S2.

[0045] In step S2, the control device 8 determines whether there is a gradient based on the gradient information, and if there is a gradient, it performs the process in step S31. In step S31, if it is expected that the power rate will be reduced according to the gradient, the control device 8 performs a process to advance the timing at which it starts to reduce the power rate, that is, a process to advance the timing of limit intervention. For example, as shown in Figure 11, if the gradient is 30%, the timing at which it starts to reduce the power rate may be earlier than when the gradient is 0%. Specifically, the control device 8 may start to reduce the power rate at time t2, which is the time after time T2 has elapsed from time t1. Figure 11 shows an example in which the timing at which it starts to reduce the power rate is advanced by a predetermined time tb. The predetermined time tb may be interpreted as the time from time t4, when the battery power begins to be limited by the limit value, to time t2. In step S3, the control device 8 reduces the power rate as described above.

[0046] The reference point for the predetermined time tb may include, for example, a time period of approximately ±50% of time t4.

[0047] If the gradient is 0%, the power rate can be started to decrease at time t3, which is 1 time T1 after time t1.

[0048] Furthermore, the control device 8 may start reducing the power rate earlier as the gradient increases. In other words, as the gradient increases, the predetermined time tb may be increased to shorten the predetermined time T2 during which the high-output state continues. For example, the power rate control unit 81a2 of the control device 8 may set the power rate to X and the predetermined time tb to 0 seconds when the gradient is 0%. Also, the power rate control unit 81a2 may set the power rate to X' (smaller than X) and the predetermined time tb to 5 seconds when the uphill gradient becomes +1%, and set the power rate to X'' (smaller than X') and the predetermined time tb to 10 seconds when the uphill gradient becomes +2%. After setting the power rate in this way, the power rate control unit 81a2 may change the power rate from X'' to X' when the value of the uphill gradient decreases, for example, from +5% to +3%. This increases the time during which discharge can be suppressed before the gradient becomes steeper. As a result, even if the output power increases due to the reduction in the power rate, the discharge amount of battery 6 is suppressed, and the running time of vehicle 100 can be extended.

[0049] As described above, the control device 8 of this disclosure has a control unit (power rate control unit 81a2) that controls the power discharged from the battery 6 according to the gradient of the road on which the vehicle 100 is traveling. When the gradient tends to increase, the power rate of the maximum battery discharge amount discharged from the battery 6 is reduced. With this configuration, even if the gradient increases and the vehicle's deceleration increases, for example, a sudden change in the deceleration of the vehicle 100 can be prevented. Therefore, the deterioration of drivability associated with changes in deceleration can be suppressed.

[0050] The following additional information is disclosed regarding the above-described embodiments.

[0051] (Note 1) The electric vehicle is equipped with a control unit that controls the power discharged from a battery mounted on the electric vehicle that stores power for driving, according to the gradient of the road on which the electric vehicle travels. The control unit is a control device that reduces the power rate of the maximum battery discharge amount discharged from the battery when the gradient tends to increase.

[0052] (Note 2) The control device according to Appendix 1, wherein the control unit controls the power rate using a map that associates the gradient with the power rate.

[0053] (Note 3) The control device according to Appendix 1, wherein the control unit does not change the timing for starting to reduce the power rate when it is not expected that the power rate will be reduced, and advances the timing for starting to reduce the power rate when it is expected that the power rate will be reduced.

[0054] (Note 4) The control device according to Appendix 3, wherein, when it is expected that the power rate will be reduced, the timing at which the power rate control is initiated will be advanced as the gradient increases.

[0055] (Note 5) At least one processor, The system controls the power discharged from the battery installed in the electric vehicle, which stores power for driving, according to the gradient of the road on which the electric vehicle travels. If the aforementioned gradient tends to increase, the power rate of the maximum battery discharge amount discharged from the battery is reduced. A control program that executes a process that includes the following.

[0056] (Note 6) At least one processor, The system controls the power discharged from the battery installed in the electric vehicle, which stores power for driving, according to the gradient of the road on which the electric vehicle travels. If the aforementioned gradient tends to increase, the power rate of the maximum battery discharge amount discharged from the battery is reduced. A control method for executing a process that includes the following.

[0057] The control unit and method described herein may be implemented by a dedicated computer comprising a processor programmed to perform one or more functions embodied by a computer program. Alternatively, the apparatus and method described herein may be implemented by a dedicated computer comprising a processor composed of dedicated hardware logic circuits. Alternatively, the apparatus and method described herein may be implemented by one or more dedicated computers comprising a combination of a processor that executes a computer program and one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium. [Explanation of Symbols]

[0058] 1 drive wheel 2. Accelerator sensor 3. Steering angle sensor 4. Rotation sensor 5 Current Sensor Group 6 batteries 7 Motor 8 Control device 9. Gradient sensor 51-phase current sensor 52-phase current sensor 53-phase current sensor 81 Inverter 81a processor 81a1 Input section 81a2 Power Rate Control Unit 81a3 Drive Unit 81b Memory 81b1 Motor control program 81e bus 82 Control Unit 100 vehicles

Claims

1. The electric vehicle is equipped with a control unit that controls the power discharged from a battery mounted on the electric vehicle that stores power for driving, according to the gradient of the road on which the electric vehicle travels. The control unit is a control device that reduces the power rate of the maximum battery discharge amount discharged from the battery when the gradient tends to increase.

2. The control device according to claim 1, wherein the control unit does not change the timing for starting to reduce the power rate when it is not expected to reduce the power rate, and advances the timing for starting to reduce the power rate when it is expected to reduce the power rate.

3. The control device according to claim 2, wherein, when it is expected that the power rate will be reduced, the control unit advances the timing at which the power rate control is intervened as the gradient increases.

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