CN100410098C - Electric vehicle and its control method - Google Patents

Abstract

The invention relates to an electric vehicle and a control method thereof. An object of the present invention is to make creep torque corresponding to vehicle speed and brake operation act and ensure smooth braking. When it is determined that the accelerator is on and the brakes are on, and it is determined that the road is running and the road is not on a slope (S120-S142), the vehicle speed-corresponding torque Tv is set in a tendency to become smaller as the vehicle speed V increases (S110 ), at the same time set the braking force corresponding torque Tb (S150) that is set with the tendency that the braking torque Td becomes smaller as the braking torque becomes larger (S150), and the set vehicle speed corresponding torque Tv and braking force corresponding torque Tb The smaller one is set as the creep torque Tc (S160).

Description

Electric vehicle and its control method

technical field

The invention relates to an electric vehicle and a control method thereof.

Background technique

Conventionally, as such an electric vehicle, a type in which a torque inversely proportional to a brake operation amount is output from a motor as a creep torque, and a type in which a torque inversely proportional to a vehicle speed is output from a motor as a creep torque has been proposed. type (for example, refer to JP-A-2001-103618 and JP-A-2001-218303). In these electric vehicles, if the brake pedal is depressed without depressing the accelerator pedal (accelerator pedal) when the shift position (shift position) is within the travel range, the torque that is inversely proportional to the driver's brake operation amount will be An electric motor that outputs power to an axle is output as a creep torque, or a torque inversely proportional to a vehicle speed is output as a creep torque from an electric motor that outputs power to an axle.

Contents of the invention

In the above-mentioned electric vehicle, the control of the torque inversely proportional to the brake operation amount as the creep torque and the control of the torque inversely proportional to the vehicle speed as the creep torque are performed separately. In the control where the torque inversely proportional to the brake operation amount is used as the creep torque, the creep torque based on the vehicle speed cannot be output. The creep torque of the manipulated volume. Simultaneous execution of these two kinds of control is considered, but since the brake operation amount and the vehicle speed change during braking, the output creep torque also changes, and smooth braking may be hindered.

One of the objects of the electric vehicle and the control method of the present invention is to make a creep torque corresponding to the vehicle speed and brake operation act. In addition, another object of the electric vehicle and its control method of the present invention is to ensure smooth braking.

The electric vehicle and its control method according to the present invention adopt the following measures in order to achieve at least part of the above objects.

The electric vehicle of the present invention is an electric vehicle provided with an electric motor capable of outputting power to an axle, and is characterized in that it includes: a vehicle speed detecting device for detecting a vehicle speed; a vehicle speed corresponding torque setting device for setting a vehicle speed corresponding torque based on the detected vehicle speed; a braking force detection device for detecting the brake braking force generated based on the driver's operation on the brake; a braking force corresponding torque setting device for setting the braking force corresponding torque according to the detected brake braking force; according to a creep torque setting device for setting the creep torque to be output from the electric motor according to the above-set vehicle speed-corresponding torque and the above-set braking force-corresponding torque; and a motor control device for controlling the electric motor so that the axle shaft outputs the set creep torque.

In the electric vehicle of the present invention, the creep torque to be output from the electric motor capable of outputting power to the axle is set based on the vehicle speed corresponding torque based on the vehicle speed and the braking force corresponding torque based on the brake braking force , when a predetermined condition is satisfied, the motor is controlled so as to output the set creep torque to the axle. Therefore, creep torque corresponding to the vehicle speed and the braking force of the brake can be exerted.

In such an electric vehicle according to the present invention, the creep torque setting device may set the smaller of the above-mentioned set vehicle speed-corresponding torque and the above-mentioned set braking force-corresponding torque One torque is set as the above-mentioned creep torque. In this way, the creep torque can be varied according to either the vehicle speed or the braking force, and at the same time, the occurrence of an excessive creep torque action can be suppressed. As a result, smooth braking can be ensured.

In addition, in the electric vehicle of the present invention, it is also possible that the creep torque setting device responds to the set vehicle speed by using the set braking force corresponding torque as a limiting torque. The torque after the torque is limited is set as the above-mentioned creep torque. In this way, it is possible to set the creep torque by limiting the vehicle speed-corresponding torque based on the vehicle speed with the braking force-corresponding torque. As a result, even when the vehicle speed-corresponding torque becomes too large, it is restricted by the braking force-corresponding torque, thereby suppressing the excessive creep torque from acting, and as a result, smooth braking can be ensured.

In the electric vehicle of the present invention, the vehicle speed-corresponding torque setting device may be configured to set the vehicle speed-corresponding torque with a tendency that the detected vehicle speed becomes smaller as the vehicle speed increases; The braking force corresponding torque setting device is a device for setting the braking force corresponding torque in a tendency that the detected braking force becomes smaller as it increases.

The electric vehicle according to the present invention may also include an internal combustion engine and a power generator capable of generating electric power that can be supplied to the electric motor by using a part of the power from the internal combustion engine. In this case, the above-mentioned power generating device may be connected to the output shaft of the above-mentioned internal combustion engine and the above-mentioned drive shaft, and at least part of the power from the internal combustion engine may be output along with the input and output of electric power and power. device for the drive shaft. Furthermore, in this case, the above-mentioned power generating device may also be configured as a device having a three-shaft power input and output device and a generator, and the three-shaft power input and output device is connected to the output shaft of the above-mentioned internal combustion engine, the above-mentioned drive A three-axis power input and output device that connects the three shafts, the three shafts and the third shaft, and performs power input and output to the remaining shafts according to the power input and output to any two shafts of the three shafts. The generator is a generator that performs power input and output with respect to the third shaft; and the generator may also be configured to include a first rotor mounted on the output shaft of the internal combustion engine and a first rotor mounted on the drive shaft. The second rotor transfers at least part of the power from the internal combustion engine through the input and output of electric power generated by the electromagnetic action between the first rotor and the second rotor as the second rotor rotates relative to the first rotor. A portion of the output goes to the twin rotor generators of the drive shaft.

The control method of the electric vehicle of the present invention is a control method of the electric vehicle equipped with an electric motor capable of outputting power to the axle, which includes the following steps: (a) detecting the vehicle speed; (b) setting the corresponding speed of the vehicle according to the detected vehicle speed; (c) detect the brake braking force generated based on the driver’s operation on the brake; (d) set the braking force corresponding torque according to the detected brake braking force; (e) correspond the above set vehicle speed to The smaller one of the torque and the torque corresponding to the braking force set above is set as the creep torque to be output from the above-mentioned motor; (f) to output the above-mentioned torque to the axle under specified conditions The above motor is controlled by means of the set creep torque.

According to the control method of the electric vehicle of the present invention, the torque corresponding to the vehicle speed based on the vehicle speed and the torque corresponding to the braking force based on the braking force of the brake are set so that the torque should be changed from the The creep torque output by the motor that outputs power to the axle controls the motor in such a way that it outputs the set creep torque to the axle under specified conditions. Therefore, either the vehicle speed or the braking force of the brake The variation of the creep torque can be influenced, and at the same time, the action of excessive creep torque can be suppressed, as a result, smooth braking can be ensured.

In such an electric vehicle control method of the present invention, the step (b) may be a step of setting the vehicle speed-corresponding torque with a tendency that the detected vehicle speed becomes smaller as the vehicle speed increases. The above-mentioned step (d) is a step of setting the above-mentioned braking force-corresponding torque with a tendency that the detected braking force becomes smaller as it is larger.

Description of drawings

FIG. 1 is a configuration diagram showing a schematic configuration of an electric vehicle 20 according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an example of a creep torque setting program executed by the electronic control unit 40 .

3 is an explanatory diagram showing an example of a vehicle speed versus torque setting map.

FIG. 4 is an explanatory diagram showing an example of a braking force versus torque setting map.

5 is an explanatory diagram showing an example of temporal changes of braking torque Td, vehicle speed V, vehicle speed-corresponding torque Tv, braking force-corresponding torque Tb, and creep torque Tc during braking.

FIG. 6 is a configuration diagram showing a schematic configuration of an electric vehicle 120 according to a modified example.

FIG. 7 is a configuration diagram showing a schematic configuration of an electric vehicle 220 according to a modified example.

FIG. 8 is a configuration diagram showing a schematic configuration of an electric vehicle 320 according to a modified example.

Detailed ways

Next, specific embodiments of the present invention will be described using examples. FIG. 1 is a configuration diagram showing a schematic configuration of an electric vehicle 20 according to an embodiment of the present invention. The electric vehicle 20 of the embodiment, as shown in the figure, includes a traveling motor 30 that outputs power to a drive shaft 26 connected to drive wheels 22 a and 22 b via a differential 24 , and supplies power to the motor 30 via a converter 34 . A storage battery 36 for electric power, and an electronic control unit 40 for controlling the entire vehicle.

For example, the motor 30 is configured as a well-known PM type synchronous generator motor, and is driven by three-phase AC power from a converter 34 . The converter 34 is also configured as a well-known conversion circuit having six switching elements, and supplies DC power from the battery 36 to the motor 30 as a simulated three-phase AC power by PWM control.

The electronic control unit 40 is configured as a microprocessor centered on a CPU 42 , and includes, in addition to the CPU 42 , a ROM 44 storing processing programs, a RAM 46 temporarily storing data, and input/output ports not shown. A detection signal from the rotational position detection sensor 32 for detecting the rotational position of the rotor of the motor 30 , a phase current from a current sensor (not shown) attached to each phase of the converter 34 , and a shifting signal for detecting the operating position of the shift lever 51 . The shift position SP of the position sensor 52 , the accelerator opening Acc from the accelerator pedal position sensor 54 that detects the depression amount of the accelerator pedal (accelerator pedal) 53 , and the brake pedal position sensor 56 that detects the depression amount of the brake pedal 55 The brake pedal position BP, the vehicle speed V from the vehicle speed sensor 58, etc. are input into the electronic control unit 40 through the input port. From the electronic control unit 40 , a switch control signal to the converter 34 and the like are output via an output port.

The electric vehicle 20 of the embodiment thus constituted is outputted from the motor 30 according to the accelerator opening Acc detected by the accelerator pedal position sensor 54 when the driver depresses the accelerator pedal 53 and the accelerator opening Acc detected by the vehicle speed sensor 58. The motor 30 is driven and controlled according to the required torque T* set by the detected vehicle speed V, and the motor 30 is output in the following manner according to the driver's depressing of the brake pedal 55. The motor 30 is driven and controlled to perform braking in accordance with the brake pedal position BP detected by the brake pedal position sensor 56 and the brake torque Td set by the vehicle speed V detected by the vehicle speed sensor 58 .

Next, the operation of the electric vehicle 20 of this embodiment, particularly the operation at the time of setting the creep torque at the time of braking, will be described. FIG. 2 is a flowchart showing an example of a creep torque setting program executed by the electronic control unit 40 . This program is repeatedly executed at predetermined intervals (for example, every 8 msec).

When the creep torque setting program starts to execute, the CPU 42 of the electronic control unit 40 first executes the accelerator opening Acc from the accelerator pedal position sensor 54, the brake pedal position BP from the brake pedal position sensor 56, the vehicle speed A process of inputting data necessary for setting the creep torque, such as the vehicle speed V and the braking torque Td of the sensor 58 (step S100 ). Here, braking torque Td is a value set according to accelerator opening Acc, brake pedal position BP, and vehicle speed V by a drive control program (not shown) that drives and controls motor 30 in the embodiment. The braking torque Td is set by, for example, storing in the ROM 44 in advance the relationship between the accelerator opening degree Acc, the brake pedal position BP, the vehicle speed V, and the braking torque Td as a table in advance, for example, When the accelerator opening Acc, the brake pedal position BP and the vehicle speed V are given, the corresponding braking torque Td is derived from the map.

When the data is input in this way, the vehicle speed corresponding torque Tv is set based on the input vehicle speed V (step S110). Here, the vehicle speed-corresponding torque Tv is, in the embodiment, as shown in FIG. 3 , a vehicle-speed-corresponding torque setting table that is set in such a manner that the vehicle speed-corresponding torque becomes smaller as the vehicle speed increases. It is stored in the ROM 44 in advance, and when the vehicle speed V is given, the corresponding vehicle speed-corresponding torque Tv is derived from a map and set.

Next, determine whether the accelerator is closed (disconnected) according to the read-in accelerator opening Acc (step S120), and simultaneously determine whether the brake is opened (connected) according to the brake pedal position BP (step S130), and then determine whether it is Traveling (step S140), when it is determined that the accelerator is open (connected) or the brake is closed (disconnected), the currently set creep torque Tc is still used, and when it is determined that there is no travel, the creep The torque Tc is set to zero value (step 170).

On the other hand, when it is determined that the accelerator is on and the brakes are on, and that the vehicle is traveling, it is determined whether or not the vehicle is traveling on a slope (step S142 ). The determination of driving on a slope can be carried out by using a road gradient sensor that detects the gradient of the road, or by using the vehicle acceleration calculated from the vehicle speed V and the torque output by the motor 30 to calculate the balance torque of the vehicle that changes due to the gradient of the road, Then judge according to the size of the balance torque. When it is determined that the vehicle is traveling on a slope, creep torque setting processing for slopes (not shown in the figure) is executed (step S144 ). Since the setting of the creep torque on the slope is not the core of the present invention, a detailed description of this process will be omitted.

When it is determined that the vehicle is not traveling on a slope, the braking force corresponding torque Tb is set according to the input braking torque Td (step S150), and the set vehicle speed corresponding torque Tv is compared with the braking force corresponding torque Tb, The smaller one, that is, the braking force corresponding torque Tb is used as the limiting torque, and the vehicle speed corresponding torque Tv is limited to set as the creep torque Tc (step S160). Here, the braking force-corresponding torque Tb is a braking force set in such a manner that the larger the braking torque Td is, the smaller the braking force-corresponding torque is, as shown in FIG. 4 in the embodiment. The corresponding torque setting table is stored in the ROM 44 in advance, and the corresponding braking force corresponding torque Tb is derived from the table when the braking torque Td is given.

After the creep torque Tc is set in this way, a gradual change process such as smoothing process is performed so that the creep torque Tc changes smoothly (step S180 ), and then the creep torque setting process ends. The creep torque subjected to the gradual change process in this way is read by a drive control program (not shown) that drives and controls the motor 30 , and is used to calculate the torque to be output from the motor 30 .

5 is an explanatory diagram showing an example of temporal changes in braking torque Td, vehicle speed V, vehicle speed-corresponding torque Tv, braking force-corresponding torque Tb, and creep torque Tc during braking. When the driver depresses the brake pedal 55 at time T1, the brake torque Td is calculated from the brake pedal position BP and the vehicle speed V at that time, and is output by the motor 30, so the vehicle decelerates. The vehicle speed corresponding torque Tv increases as the vehicle speed V decreases, and the braking force corresponding torque Tb, if considering that the braking torque Td is constant, maintains a constant value as shown in the figure. For the creep torque Tc, before the time T2 when the vehicle speed corresponding torque Tv is smaller than the braking force corresponding torque Tb, the vehicle speed corresponding torque Tv is directly set as the creep torque Tc, after time T2 due to the braking force Since the corresponding torque Tb is smaller than the vehicle speed corresponding torque Tv, the braking force corresponding torque Tb is directly set as the creep torque Tc. That is, the set creep torque Tc increases smoothly before time T2 and maintains its value after time T2. As a result, smooth braking can be ensured.

According to the electric vehicle 20 of the embodiment described above, the vehicle speed-corresponding torque Tv is set in a tendency to decrease as the vehicle speed V increases, and the restraint is set in an inclination that decreases as the braking torque Td increases. The power-corresponding torque Tb is compared, and the smaller one is set as the creep torque Tc, whereby the creep torque Tc corresponding to the vehicle speed V and the braking torque Td can be made to act.

Although the electric vehicle 20 of the embodiment is configured as a vehicle that travels only by the motor 30 that directly outputs power to the drive shaft 26, and the drive shaft 26 is connected to the drive wheels 22a, 22b; however, any structure is possible as long as it has a motor capable of outputting power to the drive wheels 22a, 22b. For example, like the electric vehicle 120 shown in FIG. 6 , it may be equipped with an engine 122, a planetary gear mechanism 124 connected to the crankshaft of the engine 122 and the drive shaft 26 connected to the drive wheels 22a, 22b, and a planetary gear mechanism. The electric motor 126 that can generate electricity that the mechanism 124 is connected, along with the electric motor 130 that carries out the input and output of power with the drive shaft 26 along with the exchange of electric power with the storage battery 36, the automobile of the electric motor 130 that can also be shown in Figure 7 as the electric automobile 220, An automobile provided with an engine 222, a pair of rotor motors 226, and a motor 230 for inputting and outputting power with the drive shaft 26 in accordance with the exchange of electric power with the storage battery 36. The inner rotor 226a attached to the crankshaft of the engine 222 and the outer rotor 226b attached to the drive shaft 26 connected to the drive wheels 22a and 22b are paired rotor motors driven by electromagnetic action caused by relative rotation. In addition, like the electric vehicle 320 shown in FIG. The engine 322 is connected to the rotating shaft of the motor 330 via a clutch. In addition, in essence, the motor 30 only needs to be a prime mover capable of outputting power to the drive wheels 22a, 22b, and therefore, even a prime mover other than the motor will not be affected.

As mentioned above, although the concrete embodiment of this invention was demonstrated using an Example, this invention is not limited to such an Example at all, It is obvious that it can implement in various forms in the range which does not deviate from the summary of this invention.

Claims (8)

1. An electric vehicle, which is an electric vehicle with an electric motor capable of outputting power to an axle, equipped with a vehicle speed detection device for detecting the vehicle speed and a brake braking force detection device for detecting the brake braking force generated based on the operation of the brake by the driver; It is characterized in that it also has: a vehicle speed corresponding torque setting device for setting a vehicle speed corresponding torque according to the detected vehicle speed; a braking force corresponding torque setting device for setting a braking force corresponding torque according to the detected brake braking force; A creep torque setting device that sets the smaller torque among the above-set vehicle speed-corresponding torque and the above-set braking force-corresponding torque as the creep torque to be output from the electric motor ;as well as A motor control device that controls the electric motor so as to output the above-mentioned set creep torque to the axle when a predetermined condition is satisfied. 2. The electric vehicle according to claim 1, wherein said vehicle speed-corresponding torque setting means is a device for setting said vehicle speed-corresponding torque with a tendency that said detected vehicle speed becomes smaller as the vehicle speed increases. ; The braking force-corresponding torque setting means is a device for setting the braking force-corresponding torque in a tendency to decrease as the detected braking force increases. 3. The electric vehicle according to claim 1, comprising an internal combustion engine, and a power generator capable of generating electric power that can be supplied to the electric motor by using a part of the power from the internal combustion engine. 4. The electric vehicle as claimed in claim 3, wherein the power generating device is connected with the output shaft of the internal combustion engine and the drive shaft, and can transfer at least part of the power from the internal combustion engine along with the input and output of electric power and power. A part of the output to the device of the drive shaft. 5. The electric vehicle as claimed in claim 4, wherein the above-mentioned power generating device is a device with a three-shaft power input and output device and a generator, and the three-shaft power input and output device is connected to the output shaft of the above-mentioned internal combustion engine, the above-mentioned A three-axis power input and output device that is connected to three shafts, the drive shaft and the third shaft, and performs power input and output to the remaining shafts based on the power input and output to any two shafts of the three shafts, This generator is a generator for inputting and outputting power to and from the third shaft. 6. The electric vehicle according to claim 4, wherein the power generating device has a first rotor mounted on the output shaft of the internal combustion engine and a second rotor mounted on the drive shaft, and the second rotor With respect to the relative rotation of the first rotor, input and output of electric power generated by the electromagnetic action of the first rotor and the second rotor output at least part of the power from the internal combustion engine to the generator for the drive shaft. 7. A control method for an electric vehicle, which is a control method for an electric vehicle with an electric motor capable of outputting power to an axle, comprising the following steps: (a) detecting the speed of the vehicle; (b) setting the vehicle speed corresponding torque according to the detected vehicle speed; (c) detecting the brake braking force generated based on the driver's operation of the brake; (d) setting the torque corresponding to the braking force according to the detected braking force; (e) Set the torque corresponding to the smaller one of the above-mentioned set vehicle speed-corresponding torque and the above-mentioned set braking force-corresponding torque as the creep torque to be output from the above-mentioned electric motor; (f) The electric motor is controlled so as to output the above-mentioned set creep torque to the axle under predetermined conditions. 8. The control method for an electric vehicle as claimed in claim 7, wherein said step (b) is a step of setting said torque corresponding to said vehicle speed with a tendency that said detected vehicle speed is larger, making it smaller; The step (d) is a step of setting the braking force corresponding torque with a tendency to make the detected braking force smaller as the detected braking force increases.

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