Vehicle control method and vehicle control device

Abstract

In a vehicle control method for a vehicle including an electric motor (14) that drives the vehicle, an engine (11) that drives a generator (12) that generates electric power to be supplied to the electric motor (14), and a battery (13) that is configured to be chargeable by the generator (12) and is also electrically connected to the electric motor (14), determination is made regarding whether or not the vehicle is traveling in a high-load state on the basis of the requested electric power requested by the vehicle and a travel load generated in the vehicle due to disturbance. In a case in which determination is made that the vehicle is traveling in the high-load state, electric power generation starting timing by the generator (12) is brought forward as compared with a case in which determination is made that the vehicle is not traveling in the high-load state.

Description

Vehicle control method and vehicle control device

[0001] The present invention relates to a vehicle control method and a vehicle control device.

[0002] 2. Description of the Related Art A control device for a hybrid vehicle is known that compensates for a decrease in power generation due to a decrease in engine output at high altitudes (see, for example, Patent Document 1).

[0003] JP 2014-133457 A

[0004] In the engine operation control device for a hybrid vehicle described in Patent Document 1, if the electric motor output remains high for a long period of time, such as when climbing a slope at high speed for a long period of time or driving on a highway at high altitude, the SOC (State of Charge), which indicates the battery's charge rate, may decrease, and the vehicle's driving force may decrease.

[0005] An object of the present invention is to provide a vehicle control method and a vehicle control device that can suppress a decrease in the SOC of a battery and prevent a decrease in the driving force of the vehicle.

[0006] One aspect of the present invention is a vehicle control method that determines whether the vehicle is running under high load based on the power required by the vehicle and the running load imposed on the vehicle due to external disturbances, and if it is determined that the vehicle is running under high load, advances the start of power generation by a generator driven by the engine compared to when it is determined that the vehicle is not running under high load.

[0007] 1 is a block diagram showing the configuration of a vehicle. FIG. 2 is a control block diagram of a drive system controller. FIG. 3 is a control block diagram of a power generation system controller. FIG. 4 is a diagram showing an example of a normal state charge / discharge map. FIG. 5 is a diagram showing an example of a high load state charge / discharge map. FIG. 6 is a diagram showing an example of vehicle speed, gradient, vehicle required power, SOC, and vehicle speed tracking ability during high load driving. FIG. 7 is a diagram showing the relationship between an air density correction coefficient and altitude. FIG. 8 is a diagram showing the relationship between engine output and altitude. FIG. 9 is a diagram showing the relationship between an upper limit of drive output of an electric motor and altitude. FIG. 10 is a diagram showing the relationship between the total value of engine output and battery output and altitude. FIG. 11 is a flowchart of control executed by the controller.

[0008] Hereinafter, an embodiment of a driving force request operation means of the present invention will be described with reference to the drawings. Note that, hereinafter, the driving force request operation by the driver using a driving force request operation means such as an accelerator pedal will be referred to as an "accelerator operation," and the amount of operation will be referred to as an "accelerator operation amount."

[0009] 1 is a block diagram showing the configuration of a vehicle 1. The vehicle 1 includes an engine 11, a generator 12, a battery 13, an electric motor 14, an inverter 15, and a control device 16.

[0010] The vehicle 1 is a so-called series-type hybrid vehicle in which electricity generated by a generator 12 using the power of an engine 11 is supplied to a battery 13 via an inverter 15, and wheels (not shown) are driven by rotating an electric motor 14 based on the power from the battery 13.

[0011] The engine 11 is a so-called internal combustion engine that uses gasoline or the like as fuel, and is mechanically connected to the generator 12. The engine 11 is used not as a power source for propelling the vehicle 1, but as a power source for driving the generator 12 to generate electricity.

[0012] The generator 12 is configured to generate electricity by rotating based on the power from the engine 11 and charge the battery 13. The generator 12 also powers the engine 11 (motoring) by rotating using the power of the battery 13. By executing motoring control to rotate the engine 11 using the power of the generator 12, it is possible to crank the engine 11 when starting it, or to close the throttle valve to generate negative pressure in the intake passage when negative pressure for brake pedal assist is required.

[0013] The control device 16 includes a vehicle speed sensor 16A, an accelerator position sensor 16B, an air pressure sensor 16C, an outside air temperature sensor 16D, a brake pressure sensor 16E, a drivetrain controller 100, and a power generation controller 200. The vehicle 1 also includes a kickdown switch (not shown) as a driving force request operating means that is activated when the accelerator pedal is depressed to a predetermined position. The kickdown switch is also sometimes referred to as a pedal force step pedal.

[0014] The accelerator position sensor 16B is configured by, for example, a pedal stroke sensor, and detects the amount of operation of the accelerator pedal (hereinafter referred to as accelerator operation amount).

[0015] The brake pressure sensor 16E detects the braking pressure (hereinafter referred to as brake pressure) generated by a brake such as a disc brake or a drum brake.

[0016] The drivetrain controller 100 and the power generation controller 200 are each configured by a microcomputer including, for example, a computing unit such as a CPU (Central Processing Unit) or a GPU (Central Graphics Processing Unit), a storage unit such as a ROM (Read Only Memory) or a RAM (Random Access Memory), and an input / output unit such as an input / output interface. The drivetrain controller 100 is electrically or communicatively connected to a vehicle speed sensor 16A, an accelerator position sensor 16B, an atmospheric pressure sensor 16C, and an outside air temperature sensor 16D. The power generation controller 200 is electrically or communicatively connected to the atmospheric pressure sensor 16C, the outside air temperature sensor 16D, and a brake pressure sensor 16E.

[0017] As shown in FIG. 2, the drive system controller 100 includes a memory unit 101, a target drive force calculation unit 102, a drive force conversion unit 103, a K / D determination unit 104, a drive force limiting unit 105, and a selection unit 106.

[0018] The memory unit 101 stores computer programs for causing the drivetrain controller 100 to function, various maps used for control, various thresholds, etc. By executing the programs stored in the memory unit 101, the drivetrain controller 100 functions as a control unit that controls the operation of various devices such as the battery 13, the electric motor 14, and the inverter 15. The maps stored in the memory unit 101 include, for example, maps that define the relationship between accelerator operation amount and vehicle speed and driving force.

[0019] The target driving force calculation unit 102 calculates the driving force required by the vehicle 1 based on the accelerator operation amount and the vehicle speed, and outputs the calculation result to the selection unit 106. The vehicle speed can be obtained by the vehicle speed sensor 16A, and the accelerator operation amount can be obtained by the accelerator position sensor 16B.

[0020] The driving force conversion unit 103 calculates the driving force that can be supplied from the battery 13 to the electric motor 14 based on the maximum power that can be supplied from the battery 13 , and outputs the calculation result to the selection unit 106 .

[0021] K / D determination unit 104 determines whether or not the kick-down switch has been turned on by the driver based on a signal from the kick-down switch, and outputs the determination result to driving force limiting unit 105 .

[0022] The driving force limiting unit 105 sets a limit value that limits the driving force of the electric motor 14 based on the altitude of the road on which the vehicle 1 is traveling and the determination result output from the K / D determination unit 104, and outputs the limit value to the selection unit 106. In this embodiment, the driving force limiting unit 105 calculates the air density based on the air pressure obtained from the air pressure sensor 16C and the outside air temperature obtained from the outside air temperature sensor 16D, and calculates the altitude of the road from the air density.

[0023] The selection unit 106 selects the driving force required by the vehicle 1 based on the driving force output from the target driving force calculation unit 102, the driving force output from the driving force conversion unit 103, and the limit value output from the driving force limiting unit 105, and outputs the selection result to the inverter 15 and the power generation system controller 200. Specifically, the selection unit 106 selects the smallest value from the values ​​output from the target driving force calculation unit 102, the driving force conversion unit 103, and the driving force limiting unit 105. The selection unit 106 also converts the selected driving force into a driving torque for the electric motor 14, and outputs the converted torque to the inverter 15 and the power generation system controller 200 as a torque command value for the electric motor 14.

[0024] As shown in FIG. 3, the power generation system controller 200 includes a memory unit 201, a disturbance running load calculation unit 202, a power conversion unit 203, a high-load running determination unit 204, a map selection unit 205, an addition unit 206, an alpha ray rotational speed calculation unit 207, a minimum value selection unit 208, a high-load rotational speed calculation unit 209, a rotational speed selection unit 210, and a maximum value selection unit 211.

[0025] The memory unit 201 stores computer programs for causing the power generation system controller 200 to function, various maps used for control, various thresholds, etc. By executing the programs stored in the memory unit 201, the power generation system controller 200 functions as a control unit that controls the operations of various devices such as the engine 11, the generator 12, and the battery 13. Examples of maps stored in the memory unit 201 include a normal charge / discharge map and a high-load charge / discharge map. The memory unit 201 also stores a gear shift number that is an optimal rotation speed for the engine 11 for each vehicle speed, taking into consideration the fuel efficiency and noise generated by the engine 11.

[0026] The disturbance running load calculation unit 202 calculates the running load caused by a disturbance on the vehicle 1 (hereinafter referred to as the disturbance running load) based on the torque command value, the acceleration resistance torque, and the brake torque, and outputs the calculation result to the high-load running determination unit 204. Examples of disturbances include the gradient of the road, the altitude, and a change in the weight of the vehicle 1. The disturbance running load calculation unit 202 filters the calculation result of the disturbance running load, and outputs the filtered disturbance running load to the high-load running determination unit 204.

[0027] In this embodiment, the disturbance running load calculation unit 202 calculates the disturbance running load using the following equation (1). The torque command value is a value output from the selection unit 106. The acceleration resistance torque is calculated based on the inertia and angular velocity of the drive system components of the vehicle 1, and the brake torque is calculated based on the brake pressure acquired from the brake pressure sensor 16E.

[0028] Disturbance running load = torque command value - acceleration resistance torque - brake torque ... (1)

[0029] In this embodiment, the disturbance running load calculation unit 202 calculates the gradient of the road on which the vehicle 1 is running based on the disturbance running load. The disturbance running load calculation unit 202 calculates the gradient from, for example, the disturbance running load and the weight of the vehicle 1.

[0030] Power conversion unit 203 converts the torque command value for electric motor 14 output from drivetrain controller 100 into a power value (output power value of battery 13). Power conversion unit 203 also filters the converted power value and outputs the filtered power value as the required power required by vehicle 1 (hereinafter referred to as vehicle required power) to high-load driving determination unit 204 and addition unit 206. The strength of the filter for the vehicle required power changes depending on the accelerator operation amount, and is set so that the filter is strong when the accelerator operation amount is small and weaker as the accelerator operation amount increases.

[0031] The high-load running determination unit 204 performs a high-load running determination based on the vehicle required power and the disturbance running load to determine whether the vehicle 1 is running under a high load, i.e., whether the vehicle is running under high load, and outputs the determination result to the map selection unit 205, the rotation speed selection unit 210, and the drivetrain controller 100. Specifically, the high-load running determination unit 204 determines that the vehicle is running under high load when the vehicle required power and the disturbance running load exceed their respective threshold values.

[0032] In this embodiment, the high-load driving determination unit 204 determines whether the vehicle is in high-load driving based on the electric power required by the vehicle and the gradient and altitude of the roadway, which correspond to the disturbance driving load. That is, the high-load driving determination unit 204 determines whether the vehicle is in high-load driving when the electric power required by the vehicle and the gradient exceed their respective thresholds THE and THS (see FIG. 6 ). The gradient threshold THS varies depending on the vehicle speed, being set to be large when the vehicle speed is low and to be small as the vehicle speed increases. Meanwhile, the vehicle-required electric power threshold THE varies depending on the altitude and the vehicle speed, being set to be large when the altitude is low and to be small as the altitude increases. The high-load driving determination unit 204 calculates the air density based on the air pressure obtained from the air pressure sensor 16C and the outside air temperature obtained from the outside air temperature sensor 16D, and calculates the altitude of the roadway from the air density.

[0033] The map selection unit 205 selects a charge / discharge map to be used for charging / discharging the battery 13 based on the determination result by the high-load running determination unit 204, and supplies the selected charge / discharge map to the addition unit 206. Specifically, when the high-load running determination unit 204 determines that the vehicle 1 is running in a high-load state, the map selection unit 205 selects the high-load charge / discharge map, and when the high-load running determination unit 204 determines that the vehicle 1 is not running in a high-load state, the map selection unit 205 selects the normal charge / discharge map.

[0034] The adder 206 adds the vehicle required power (power value corresponding to the torque command value of the electric motor 14) output from the power conversion unit 203 to a value specified by the charge / discharge map output from the map selection unit 205, and outputs the addition result to the alpha ray rotational speed calculation unit 207 and the high load rotational speed calculation unit 209. That is, calculations are performed by the alpha ray rotational speed calculation unit 207 and the high load rotational speed calculation unit 209 in consideration of the vehicle required power and the charge / discharge map corresponding to the result of the high load running determination.

[0035] The α-ray rotational speed calculation unit 207 calculates the rotational speed of α-rays based on the added value output from the addition unit 206, and outputs the calculation result to the minimum value selection unit 208. Here, α-rays indicate the rotational speed at which the engine 11 has the best fuel economy for each engine output. That is, the rotational speed at which the engine 11 has the best fuel economy due to α-rays can be determined for each added value.

[0036] The minimum value selection unit 208 selects the smaller value between the calculation result by the α-ray rotational speed calculation unit 207 and the gear speed stored in the storage unit 201, and supplies the selected value to the maximum value selection unit 211. That is, the minimum value selection unit 208 selects the smaller value between the α-ray rotational speed calculated according to the added value output from the addition unit 206 and the optimum rotational speed according to the speed of the vehicle 1. The gear speed is the optimum rotational speed of the engine 11 taking into consideration the fuel efficiency and noise generated by the engine 11, and is set for each vehicle speed.

[0037] The high-load rotation speed calculation unit 209 calculates the rotation speed of the engine 11 during high-load running based on the added value output from the addition unit 206, and outputs the calculation result to the rotation speed selection unit 210. The rotation speed of the engine 11 during high-load running is a value for outputting the torque required during high-load running at as low a rotation speed as possible.

[0038] Based on the determination result by the high-load traveling determination unit 204, the rotation speed selection unit 210 selects one of the calculation result by the high-load rotation speed calculation unit 209 or "0" as the rotation speed of the engine 11 that drives the generator 12, and supplies the selected value to the maximum value selection unit 211. Specifically, if it is determined that the vehicle is at high altitude, the rotation speed selection unit 210 selects the calculation result by the high-load rotation speed calculation unit 209, and if it is not determined that the vehicle is at high altitude, the rotation speed selection unit 210 selects "0".

[0039] Maximum value selection unit 211 selects the larger value from the value selected by minimum value selection unit 208 and the value selected by rotation speed selection unit 210, and outputs the selected value to engine 11. In other words, the rotation speed of engine 11 is controlled based on the value selected by maximum value selection unit 211.

[0040] [Examples of Normal-State Charge / Discharge Map and High-Load Charge / Discharge Map] Fig. 4 is a diagram showing an example of the normal-state charge / discharge map, and Fig. 5 is a diagram showing an example of the high-load charge / discharge map. Note that, for the normal-state charge / discharge map and the high-load charge / discharge map, a plurality of maps are stored in the storage unit 201 according to the vehicle speed, but for ease of explanation, Figs. 4 and 5 show an example of the map when the vehicle speed is V1 (kph (kilometers per hour)). V1 is, for example, the vehicle speed when traveling at high speed.

[0041] In Figures 4 and 5, the vertical axis represents the additional charge amount of the battery 13 in kW, and the horizontal axis represents the SOC (States Of Charge) in %. The additional charge amount refers to the amount of power generated by the generator 12 that is charged to the battery 13. For example, if the value of the additional charge amount is positive, the battery 13 is charged, and if the value of the additional charge amount is negative, the battery 13 is discharged. In other words, in the case of discharge, the electric motor 14 is driven using the power of the battery 13. Figures 4 and 5 also show an example of a case where the lower limit of the additional charge amount of the battery 13 is controlled. That is, Figures 4 and 5 show an example of a lower limit line of the additional charge amount during normal driving and an example of a lower limit line of the additional charge amount during high-load driving.

[0042] When it is not determined that the vehicle is running under high load (normal operation) and the vehicle speed is V1, as shown in the normal operation charge / discharge map of Figure 4, when the SOC is less than So1, the additional charge amount "kW" becomes a positive value. On the other hand, when the SOC becomes So1 or more, the additional charge amount "kW" becomes a negative value. In this way, when the vehicle is running under normal operation and the vehicle speed is V1, the SOC of the battery 13 is set to be at least So1 or more.

[0043] In contrast, when it is determined that the vehicle is running under high load and the vehicle speed is V1, as shown in the high load charge / discharge map of Figure 5, the additional charge amount "kW" becomes a positive value when the SOC is less than So2. Also, when it is determined that the vehicle is running under high load and the vehicle speed is V1, the additional charge amount "kW" becomes a negative value when the SOC becomes So2 or more. On the other hand, the SOC of the battery 13 is set to be at least So2 or more.

[0044] Here, as shown in Figures 4 and 5, So2 is a value greater than So1. That is, the SOC at which the additional charge amount shown in the high-load charge / discharge map is 0 kW is greater than the SOC at which the additional charge amount shown in the normal charge / discharge map is 0 kW. In this embodiment, the SOC at which the additional charge amount is 0 kW (So1 shown in Figure 4 and So2 shown in Figure 5) will be referred to as the "SOC center." The SOC center can be set using various experimental data such as the performance of the battery 13, engine 11, and generator 12.

[0045] [Examples of vehicle speed, gradient, SOC, vehicle required power, and vehicle speed tracking ability during high-load driving] Whether vehicle 1 is driving under a high load is determined based on the vehicle required power and a disturbance driving load. In this embodiment, the determination is based on the vehicle required power, the gradient of the road calculated according to the disturbance driving load, and the altitude of the road. If the vehicle required power exceeds the threshold THE and the gradient exceeds the threshold THS, it is determined that vehicle 1 is driving under a high load.

[0046] The vehicle required electric power is obtained by converting the torque command value of the electric motor 14 into a power value and then filtering it. The strength of the filter for the vehicle required electric power changes depending on the accelerator operation amount, and is set so that the filter is strong when the accelerator operation amount is small and weaker as the accelerator operation amount increases. As a result, when the driver of the vehicle 1 performs an acceleration operation by increasing the accelerator operation amount, the vehicle required electric power is quickly increased, making it easier to determine that the vehicle is in a high load state, and thereby bringing forward the timing at which power generation by the generator 12 begins.

[0047] The threshold THE for the vehicle required power varies depending on the altitude and the vehicle speed. Specifically, it is set to be large at low altitudes and to be small at higher altitudes. As the altitude increases, the air density decreases and the engine output decreases, causing the vehicle 1 to travel under a higher load than on flat ground. For this reason, the threshold is set to be smaller at higher altitudes, making it easier to determine that the vehicle is in a high-load state.

[0048] Furthermore, the threshold THE for the vehicle required power is set to be large when the vehicle speed is low and to be smaller as the vehicle speed increases. When the vehicle speed is high, the load on the engine 11 and the electric motor 14 increases and wind resistance increases compared to when the vehicle speed is low, so the vehicle 1 runs under a higher load than when it is running at a low speed. For this reason, the threshold THE is set to be smaller as the vehicle speed increases, making it easier to determine that the vehicle is in a high-load state.

[0049] On the other hand, the gradient threshold THS varies depending on the vehicle speed, being set to be large when the vehicle speed is low and to be small as the vehicle speed increases, for the same reason as explained above regarding the reason why the threshold THE of the vehicle required power varies depending on the vehicle speed.

[0050] Here, an example of a case where the vehicle 1 is running under a high load is when the vehicle 1 is running at a high altitude. However, even at high altitudes, the running load is low when the vehicle is running at a low speed on a flat road with no gradient. Conversely, even when the vehicle is running at a low altitude, the running load is high when, for example, the vehicle is climbing a slope or running on a highway at a high speed. For this reason, whether the vehicle 1 is running under a high load is determined based on the vehicle required power and the external disturbance running load.

[0051] 6 is a diagram showing an example of time transitions of vehicle speed, gradient, vehicle required power, SOC, and vehicle speed tracking ability relative to target vehicle speed during high-load driving. The gradient shown by the solid line in FIG. 6 is the gradient before filtering, and the gradient shown by the dashed line is the gradient after filtering. The SOC shown by the solid line in FIG. 6 is the SOC during normal driving, and the SOC shown by the dashed line is the SOC when it is determined that the vehicle 1 is driving under high load.

[0052] In FIG. 6 , the vehicle required power and gradient exceed the respective thresholds THE and THS at time T1, and it is determined that the vehicle 1 is traveling under a high load. At this time, the charge / discharge map is switched from the normal charge / discharge map to the high load charge / discharge map, and the SOC center of the battery 13, i.e., the SOC at which the additional charge amount becomes 0 kW, is set to a higher value, thereby advancing the timing of power generation by the generator 12. Furthermore, by switching from the normal charge / discharge map to the high load charge / discharge map, the additional charge amount is increased, thereby increasing the amount of power generated by the generator 12. As a result, the SOC, as shown by the dashed line in FIG. 6 , is maintained higher than the SOC shown by the solid line in FIG. 6 , ensuring an SOC that can withstand traveling under a high load. As a result, as shown in FIG. 6 , the vehicle speed difference from the target vehicle speed during high-load traveling, shown by the dashed line in FIG. 6 , is smaller than during normal traveling, shown by the solid line in FIG. 6 , thereby improving vehicle speed tracking capability. In Figure 6, the vehicle required power continues to exceed the threshold value THE, but at time T2 the gradient falls below the threshold value THS, so it is determined that the vehicle 1 is no longer running under high load at this point.

[0053] [Example of Driving Force Limitation] Figures 7 to 10 show examples of driving force limitations based on the high altitude determination threshold TH1. The high altitude determination threshold TH1 can be set using various experimental data such as the performance of the battery 13, engine 11, and generator 12 according to the altitude. The high altitude determination threshold TH1 can be set to, for example, about 2800 m. Note that for ease of explanation, each relationship is shown in a simplified form in Figures 7 to 10.

[0054] FIG. 7 is a diagram showing an example of the relationship between the air density correction coefficient and altitude [m]. Air density can be calculated based on atmospheric pressure and temperature. Furthermore, altitude can be determined based on air density. For ease of explanation, FIG. 7 shows the relationship between the air density correction coefficient and altitude [m] simply by using a straight line AD1.

[0055] The air density correction coefficient is a value that indicates the proportion of the amount of air that can be taken in by the engine 11, with the value being "1" when the altitude of the vehicle 1 is 0 m. For example, taking the engine 11 with a maximum output of 100 kW as an example, an engine output of 100 kW is possible when the air density correction coefficient is 1, and an engine output of 90 kW is possible when the air density correction coefficient is 0.9. As shown by the straight line AD1, the value of the air density correction coefficient decreases as the altitude of the vehicle 1 increases.

[0056] Fig. 8 is a diagram showing an example of the relationship between engine output [kW] and altitude [m]. The engine output corresponding to the altitude can be obtained by multiplying the maximum output of the engine 11 by the air density correction coefficient shown in Fig. 7. In other words, the engine output decreases as the altitude increases. Note that in Fig. 8, for ease of explanation, the relationship between engine output [kW] and altitude [m] is simplified and shown by a straight line EP1.

[0057] 9 is a diagram showing an example of the relationship between the upper limit of the drive output [kW] of the electric motor 14 and the altitude [m]. As shown by line DL1 in Fig. 9, when the altitude of the vehicle 1 is less than the high altitude determination threshold TH1, the drive force of the electric motor 14 is not limited. In other words, the minimum value of the drive forces calculated by the target drive force calculation unit 102 and the drive force conversion unit 103 is set as the drive force of the electric motor 14.

[0058] As shown by line DL3 in Figure 9, when the altitude of the vehicle 1 exceeds the high altitude determination threshold TH1, the upper limit of the driving force of the electric motor 14 is limited. Furthermore, the limit amount is gradually increased until the altitude of the vehicle 1 exceeds the high altitude determination threshold TH1 and reaches a threshold TH2 (where TH1 < TH2). Furthermore, when the altitude of the vehicle 1 exceeds the threshold TH2, the limit amount is kept constant. In this way, by limiting the upper limit of the driving force of the electric motor 14, it is possible to prevent excessive use of the SOC of the battery 13.

[0059] When the driver depresses the accelerator pedal with the intention of accelerating, the kick-down switch is turned on. In this case, if the upper limit of the driving force of the electric motor 14 is limited, the driver may not get the acceleration feeling he or she intended, which may cause the driver to feel uncomfortable. Therefore, even if the altitude of the vehicle 1 exceeds the high altitude determination threshold TH1, when the kick-down switch is turned on, the limit on the driving force of the electric motor 14 is relaxed, as shown by line DL2 in Figure 9.

[0060] Fig. 10 is a diagram showing an example of the relationship between the total value [kW] of the engine output and the battery output and the altitude [m]. The vertical axis of Fig. 10 represents the output that can be used to drive the vehicle 1. That is, the diagram shows an example of the relationship when information related to the output of the engine 11 and the battery 13 is viewed on the power axis.

[0061] A straight line EB1 shown in Fig. 10 indicates the value obtained by adding the value of the straight line EP1 shown in Fig. 8 and the value of the line DL1 shown in Fig. 9. Similarly, a line EB2 shown in Fig. 10 indicates the value obtained by adding the value of the straight line EP1 shown in Fig. 8 and the value of the line DL2 shown in Fig. 9. Similarly, a line EB3 shown in Fig. 10 indicates the value obtained by adding the value of the straight line EP1 shown in Fig. 8 and the value of the line DL3 shown in Fig. 9. A dotted line EB4 shown in Fig. 10 indicates the value obtained when it is assumed that the restriction shown in Fig. 9 is not applied when the altitude of the vehicle 1 exceeds the high altitude determination threshold TH1.

[0062] The dotted line BT1 in FIG. 10 indicates the amount of electric power generated by the engine output corresponding to the line EP1 in FIG. 8 . As shown by the relationship between the dotted line BT1 and the line EB3 in FIG. 10 , when the altitude of the vehicle 1 exceeds the high-altitude determination threshold TH1 and approaches the threshold TH2, the value of the line EB3 becomes smaller than the value of the dotted line BT1. That is, by limiting the upper limit of the driving force of the electric motor 14, some of the electric power that can be generated by the engine output is not used to drive the electric motor 14. In other words, a charge reserve is created. Therefore, when the altitude of the vehicle 1 exceeds the threshold TH2 and the kickdown switch is not turned on, the electric power generated by the engine output can be charged to the battery 13, thereby preventing depletion of the battery 13. Note that depletion of the battery 13 refers to the state of charge (SOC) of the battery 13 falling below a predetermined value. For example, the SOC of the battery 13 is determined to be depleted when the SOC of the battery 13 falls below 40%.

[0063] 10, when the kickdown switch is turned on, the value of line EB2 is greater than the value of dotted line BT1, even if the altitude of vehicle 1 exceeds threshold value TH2. This allows the restriction on the driving force of electric motor 14 to be relaxed, even at high altitudes, thereby reflecting the driver's intention to accelerate.

[0064] Furthermore, in order to ensure the power generation of the battery 13, when it is determined that the vehicle is at high altitude, the rotation speed during high-load driving and the rotation speed of alpha rays during high-load driving are calculated, and the rotation speed required for high altitude is indicated. In this way, in the first embodiment, when it is determined that the vehicle is at high altitude, the driving force of the electric motor 14 is limited and the center of SOC of the battery 13 is shifted higher, thereby ensuring an SOC that can withstand the intention of accelerating at high altitude.

[0065] 11 is a flowchart showing an example of a processing procedure for vehicle control processing executed by the drive system controller 100 and the power generation system controller 200. Note that this processing procedure is executed based on programs stored in the memories 101 and 201 of the controllers 100 and 200.

[0066] In step S501, the high-load running determination unit 204 determines whether the vehicle 1 is running under a high load, i.e., whether the vehicle 1 is running under a high load. If it is determined that the vehicle 1 is running under a high load, the process proceeds to step S505, and if it is determined that the vehicle 1 is not running under a high load, the process proceeds to step S502.

[0067] In step S502, the power generation system controller 200 sets a target SOC center for normal operation. Specifically, the map selection unit 205 selects a normal charge / discharge map stored in the storage unit 201, and charging / discharging of the battery 13 based on the normal charge / discharge map is set. The target SOC center for normal operation means an SOC center that is targeted for normal operation.

[0068] In the next step S503, the power generation system controller 200 sets the engine rotation speed during normal operation. Specifically, the α-ray rotation speed calculation unit 207 calculates the α-ray rotation speed based on the normal charge / discharge map. The rotation speed selection unit 210 selects "0". Then, the maximum value selection unit 211 selects the value selected by the minimum value selection unit 208 (the smaller value between the α-ray rotation speed based on the normal charge / discharge map and the optimal rotation speed according to the speed of the vehicle 1) as the engine rotation speed.

[0069] In the next step S504, the drivetrain controller 100 outputs an instruction to the inverter 15 to control the drive force of the vehicle 1 based on the value selected by the selection unit 106. That is, the drivetrain controller 100 performs normal control of the drive force based on the vehicle speed and the accelerator operation amount. Note that, because it has not been determined that the vehicle is running under high load, the selection unit 106 selects the smallest value of the drive forces calculated by the target driveforce calculation unit 102 and the driveforce conversion unit 103.

[0070] On the other hand, in step S505, the power generation system controller 200 sets a target SOC center for a high load. Specifically, the map selection unit 205 selects a high load charge / discharge map stored in the storage unit 201, and charging / discharging of the battery 13 is set based on the high load charge / discharge map. The target SOC center for a high load means the SOC center that is targeted when it is determined that the vehicle is at high altitude. In this way, when it is determined that the vehicle is at high altitude, the target SOC center of the battery 13 is set to a value greater than that before it was determined that the vehicle was at high altitude.

[0071] In step S506, the power generation system controller 200 sets the engine rotation speed under high load. Specifically, the alpha ray rotation speed calculation unit 207 calculates the alpha ray rotation speed based on the high load charge / discharge map. The minimum value selection unit 208 selects the smaller value between the alpha ray rotation speed based on the high load charge / discharge map and the optimum rotation speed according to the vehicle speed of the vehicle 1. The rotation speed selection unit 210 selects the rotation speed of the engine 11 under high load calculated by the high load rotation speed calculation unit 209. The maximum value selection unit 211 selects the larger value between the value selected by the minimum value selection unit 208 and the value selected by the rotation speed selection unit 210 (the rotation speed of the engine 11 under high load) as the engine rotation speed.

[0072] In step S507, K / D determination unit 104 performs K / D determination to determine whether or not the kick-down switch has been turned on. If the kick-down switch has been turned on, the process proceeds to step S509, and if the kick-down switch has not been turned on, the process proceeds to step S508.

[0073] In step S508, the driving force limiting unit 105 sets a limit value for driving force for high altitudes. Specifically, the limit value for driving force for high altitudes is set as shown by line DL3 in FIG.

[0074] In step S509, the driving force limiting unit 105 increases the driving force limit for high altitude by a predetermined value. Specifically, the driving force limit for high altitude when the kick-down switch is turned on is set as shown by line DL2 in FIG.

[0075] In step S510, the selection unit 106 performs a vehicle speed determination to determine whether the vehicle speed is equal to or greater than a predetermined value. If the vehicle speed is equal to or greater than the predetermined value, the selection unit 106 selects the high-altitude driving force limit value set by the driving force limiting unit 105 in step S508 or S509, and then proceeds to step S508. However, if the value set by the driving force limiting unit 105 is greater than the value calculated by the target driving force calculation unit 102 or the driving force conversion unit 103, the minimum value of the driving forces calculated by the target driving force calculation unit 102 and the driving force conversion unit 103 is selected. On the other hand, if the vehicle speed is less than the predetermined value, the selection unit 106 selects the minimum value of the driving forces calculated by the target driving force calculation unit 102 and the driving force conversion unit 103, and then proceeds to step S504.

[0076] That is, when the vehicle speed is below a predetermined value, the driving force is not limited even if the vehicle is determined to be at high altitude. For example, a series hybrid vehicle can provide a comfortable acceleration feeling. Furthermore, the accelerator pedal is often depressed less frequently on expressways, but the accelerator pedal is likely to be depressed more frequently in urban areas. Thus, when traveling at a vehicle speed below a predetermined value, such as in urban areas, moderate acceleration is often required. Therefore, in urban areas where traveling at relatively low speeds is expected, the driving force is not limited in order to take advantage of the characteristics of a series hybrid vehicle. However, regardless of whether the vehicle speed is below a predetermined value, when the vehicle is determined to be at high altitude, a target SOC center for high load is set, and an engine speed for high load is set.

[0077] In step S511, the drivetrain controller 100 outputs to the inverter 15 an instruction to control the drive force of the vehicle 1 based on the value selected by the selection unit 106. That is, the drivetrain controller 100 performs control during high-load running to limit the drive force based on the setting contents.

[0078] [Effects of the embodiment] According to the above-described embodiment, when it is determined that the vehicle 1 is running under high load based on the vehicle required power and the external disturbance running load, the timing at which power generation by the generator 12 starts is advanced compared to when it is determined that the vehicle is not running under high load, thereby suppressing a decrease in the SOC of the battery 13 and preventing a decrease in the driving force of the vehicle 1.

[0079] In addition, by limiting the driving force of the electric motor 14 in response to a decrease in engine output at high altitudes, the decrease in the SOC of the battery 13 is suppressed, thereby further preventing a decrease in the driving force of the vehicle 1.

[0080] Furthermore, when it is determined that the vehicle 1 is traveling under a high load, the amount of power generated by the generator 12 is increased, so that the decrease in the SOC of the battery 13 can be further suppressed.

[0081] In addition, the gradient of the road on which vehicle 1 is traveling is estimated based on the required power and the external driving load, and whether vehicle 1 is traveling under high load is determined based on the gradient, required power, and altitude of the road, so that it is possible to determine with greater accuracy whether vehicle 1 is traveling under high load.

[0082] In addition, the timing at which the generator 12 starts generating electricity is advanced based on the driver's acceleration operation of the vehicle 1, thereby suppressing the decrease in the SOC of the battery 13 at an early stage during acceleration, and allowing the vehicle 1 to accelerate according to the driver's intention to accelerate.

[0083] Furthermore, when it is determined that the vehicle 1 is running under high load conditions, the SOC at which the additional charge amount of the battery 13 becomes 0 kW is set to a larger value than when it is determined that the vehicle 1 is not running under high load conditions, so that the SOC can be controlled to a higher value.

[0084] As described above, the best configurations, methods, and the like for implementing the present invention have been disclosed in the above description, but the present invention is not limited thereto. That is, although the present invention has been particularly illustrated and described mainly with reference to specific embodiments, those skilled in the art can make various modifications to the above-described embodiments in terms of shape, material, quantity, and other detailed configurations without departing from the scope of the technical idea and purpose of the present invention. Furthermore, the above-disclosed descriptions limiting the shape, material, and the like are provided as examples to facilitate understanding of the present invention and are not intended to limit the present invention. Therefore, descriptions using names of components that are free from some or all of the limitations on shape, material, and the like are included in the present invention.

[0085] In the vehicle 1, the driving force request operation means is configured as the accelerator pedal, and the sensor for detecting the accelerator operation amount is configured as the accelerator position sensor 16B, but other configurations may be used. For example, the driving force request operation means may be configured as an operation lever or an operation dial, and the accelerator operation amount may be detected by a sensor such as a stroke sensor or potentiometer that detects the operation amount of these.

[0086] The vehicle 1 may be equipped with a navigation device. In this case, the drive system controller 100 and the power generation system controller 200 may acquire information about the gradient and altitude of the road from the navigation device and use the information for various calculations and determinations.

[0087] The control device 16 may include, for example, a gradient sensor that detects a gradient, a weight sensor that detects the weight of the vehicle 1, and a towing determination sensor that determines whether the vehicle 1 is being towed. In this case, the disturbance running load calculation unit 202 may calculate the disturbance running load using these sensors.

[0088] The drive system controller 100 and the power generation system controller 200 may be configured as a single computer having both, or may be configured as separate computers.

[0089] 1...vehicle, 11...engine, 12...generator, 13...battery, 16...controller, 100...drive system controller (controller), 200...power generation system controller (controller)

Claims

1. A method for controlling a vehicle that includes an electric motor that drives the vehicle, an engine that drives a generator that generates electricity to be supplied to the electric motor, and a battery that is configured to be chargeable by the generator and is electrically connected to the electric motor, the method determining whether the vehicle is running under high load based on the power required by the vehicle and the running load imposed on the vehicle by external disturbances, and if it is determined that the vehicle is running under high load, causing the generator to start generating electricity earlier than if it is determined that the vehicle is not running under high load.

2. A vehicle control method according to claim 1, wherein the amount of power generated by the generator is increased when it is determined that the vehicle is running under a high load.

3. A vehicle control method as claimed in claim 1, comprising: estimating the gradient of the road on which the vehicle is traveling based on the required power and the road load; determining whether the vehicle is traveling under high load based on the gradient, the required power, and the altitude of the road; and increasing the amount of power generated by the generator if it is determined that the vehicle is traveling under high load.

4. A vehicle control method according to claim 1, wherein the timing at which the generator starts generating electricity is advanced based on the driver's operation to accelerate the vehicle.

5. A vehicle control method as claimed in claim 1, wherein, when it is determined that the vehicle is running under high load, the SOC at which the additional charge amount of the battery becomes 0 kW is set to a larger value than when it is determined that the vehicle is not running under high load.

6. A control device for a vehicle comprising an electric motor that drives the vehicle, an engine that drives a generator that generates electricity to be supplied to the electric motor, and a battery that is configured to be chargeable by the generator and is electrically connected to the electric motor, the control device comprising a controller that determines whether the vehicle is running under high load based on the power required by the vehicle and the running load imposed on the vehicle by external disturbances, and that, if it is determined that the vehicle is running under high load, causes the generator to start generating electricity earlier than when it is determined that the vehicle is not running under high load.

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