JP2006081323A - Electric vehicle and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make driving feeling good while maintaining acceleration performance, in an electric vehicle provided with a motor as a power source. <P>SOLUTION: A rate limit ΔTrl is set so as to have a tendency to become large (tendency of faster response speed) as the absolute value of a required torque variation ΔTd, as a variation per unit time of required torque Td* set based on accelerator opening Acc, is small (S120-S140). Rate processing is made to the required torque Td* with the set rate limit ΔTrl to set performance torque T* (S150-S180). The motor is driven and controlled by the performance torque T* (S190). Consequently, if the required torque Td* changes sharply, the response speed is made slow immediately after the sharp change. When the sharp change of the required torque Td* comes to an end, the response speed is made faster to set the performance torque T*. Thus, the driving feeling can be kept good with the acceleration performance maintained to an acceptable level. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

Conventionally, as this type of electric vehicle, one that delays a command signal to the motor with respect to an accelerator input signal when the vehicle speed (rotational speed of the motor) is equal to or lower than a predetermined speed has been proposed (for example, see Patent Document 1). . In this electric vehicle, when the vehicle speed is below a predetermined vehicle speed corresponding to when the vehicle is stopped or at a low vehicle speed, the accelerator signal is filtered to generate a motor command signal, and when the vehicle speed exceeds the predetermined speed, the filter processing is performed. By using the accelerator signal as it is as the motor command signal, the feeling at the time of start can be improved without degrading the acceleration performance.
JP-A-8-19109

  However, in the above-described electric vehicle, the accelerator operation (driving force request) by the driver is not considered when performing the filter process. In the above-mentioned electric vehicle, since the time constant of the filter processing is constant, when a large value is set for this time constant, the shock to the fluctuation of the accelerator operation can be reduced, but the response to the accelerator operation is lowered and the acceleration performance is impaired. When a small value is set for the time constant, the responsiveness to the accelerator operation can be improved and the acceleration performance can be improved, but the shock to the fluctuation of the accelerator operation becomes large. In other words, acceleration performance and driving feeling cannot be achieved at the same time, regardless of whether the time constant of the filter process is set large or small. In particular, when a small value is set for the time constant of the filter processing, an unexpected shock is caused to the vehicle in response to an operation in which the driver instantaneously turns on and off the accelerator pedal without intending to accelerate.

  An object of the electric vehicle and the control method thereof according to the present invention is to solve such problems and improve driving feeling while maintaining acceleration performance to some extent with respect to a driving force demand by a driver. Another object of the electric vehicle and the control method thereof according to the present invention is to suppress the occurrence of a shock with respect to a change in accelerator operation that does not intend to require a driving force while maintaining acceleration performance to some extent.

  The electric vehicle and the control method thereof according to the present invention employ the following means in order to achieve at least a part of the above object.

The electric vehicle of the present invention is
An electric vehicle that can be driven by power from an electric motor,
When the driver's driving force request changes suddenly, at least until the sudden change of the driving force request is converged, the driving force request is subjected to a gradual change process with the first response mode to set the execution driving force, After the sudden change of the driving force request has converged, the execution driving force is set by performing a gradual change process on the driving force request with the second response mode in which the response is faster than the first response mode. Execution driving force setting means;
And a drive control means for controlling the driving of the electric motor based on the set execution driving force.

  In the electric vehicle according to the present invention, when the driving force request by the driver suddenly changes, the driving force request is subjected to a slow change process and executed in a first response manner at least until the sudden change in the driving force request converges. After the driving force is set and the sudden change in the driving force request has converged, the driving force request is subjected to a gradual change process with a second response mode that is faster than the first response mode. And the drive control of the electric motor based on the set execution driving force. As a result, the driving feeling can be improved while maintaining the acceleration performance to some extent with respect to the driving force demand by the driver. For example, it is possible to suppress the occurrence of a shock with respect to a change in accelerator operation that does not intend a request for driving force while maintaining acceleration performance to some extent.

  In such an electric vehicle of the present invention, the effective driving force setting means performs the slow change process on the driving force request so that the response becomes faster as the amount of change per unit time of the driving force request becomes smaller. It may be a means for setting the execution driving force. If it carries out like this, driving | operation feeling can be made favorable, maintaining acceleration performance to some extent with respect to the driving force request | requirement by a driver | operator by simple process. In the electric vehicle of this aspect of the present invention, the execution driving force setting means may be means for setting the execution driving force by a smoothing process or a rate process as the slow change process.

  In the electric vehicle of the present invention, the effective driving force setting means may be a means for setting the effective driving force by suppressing a frequency component of a predetermined frequency or higher with respect to the driving force request. . If it carries out like this, driving | operation feeling can be made favorable, maintaining acceleration performance to some extent with respect to the driving force request | requirement by a driver | operator by simple process. In this aspect of the electric vehicle of the present invention, the effective driving force setting means may be means for setting the effective driving force using a filter that attenuates a frequency component equal to or higher than the predetermined frequency.

The electric vehicle control method of the present invention includes:
A method of controlling an electric vehicle that can be driven by power from an electric motor,
(A) When the driver's driving force request suddenly changes, at least until the sudden change of the driving force request is converged, the driving force request is subjected to a gradual change process with the first response mode and the execution driving force is reduced. After the sudden change of the driving force request is set to converge, the driving force request is subjected to a gradual change process with a second response mode in which the response is faster than the first response mode. Set
(B) The gist is to drive and control the electric motor based on the set execution driving force.

  According to the electric vehicle control method of the present invention, when the driving force request by the driver changes suddenly, at least until the sudden change of the driving force request converges, the first response mode gradually changes with respect to the driving force request. The execution driving force is set by performing processing, and after the sudden change of the driving force request has converged, a slow change process is performed on the driving force request with the second response mode that is faster than the first response mode. The execution driving force is set, and the electric motor is driven and controlled based on the set execution driving force. As a result, the driving feeling can be improved while maintaining the acceleration performance to some extent with respect to the driving force demand by the driver. For example, it is possible to suppress the occurrence of a shock with respect to a change in accelerator operation that does not intend a request for driving force while maintaining acceleration performance to some extent.

  Next, the best mode for carrying out the present invention will be described using examples.

  FIG. 1 is a configuration diagram showing an outline of a configuration of an electric vehicle 20 as an embodiment of the present invention. As shown in the figure, the electric vehicle 20 of the embodiment includes a motor 22 having a rotation shaft connected to a drive shaft 30 connected to drive wheels 34 a and 34 b via a differential gear 32, and an inverter 24 connected to the motor 22. An electrically connected battery 26 and an electronic control unit 40 for controlling the entire vehicle are provided.

  The motor 22 is configured as, for example, a known synchronous generator motor that can function as an electric motor and can also function as a generator, and is driven to rotate by input / output of electric power from a battery 26 via an inverter 24 as a drive circuit.

  The electronic control unit 40 is configured as a microprocessor centered on the CPU 42. In addition to the CPU 42, a ROM 44 storing processing programs and the like, a RAM 46 temporarily storing data, and an input / output port (not shown) are provided. Prepare. The electronic control unit 40 includes an ignition signal from the ignition switch 50, a shift position from the shift position sensor 52 that detects the operation position of the shift lever 51, and an accelerator pedal position sensor 54 that detects the opening degree of the accelerator pedal 53. Acceleration opening degree Acc, brake pedal position from the brake pedal position sensor 56 that detects the opening degree of the brake pedal 55, vehicle speed V from the vehicle speed sensor 58, and rotation that detects the rotational position of the rotating shaft (drive shaft 30) of the motor 22 The rotational position from the position detection sensor 36 is input through an input port, and the electronic control unit 40 outputs a switching control signal to a switching element included in the inverter 24 through an output port.

  An operation of the thus configured electric vehicle 20 of the embodiment will be described. FIG. 2 is a flowchart illustrating an example of a drive control routine executed by the electronic control unit 40 of the electric vehicle 20 according to the embodiment. This routine is repeatedly executed every predetermined time (for example, every 8 msec).

  When the drive control routine is executed, the CPU 42 of the electronic control unit 40 first inputs data necessary for control such as the accelerator opening degree Acc from the accelerator pedal position sensor 54 and the vehicle speed V from the vehicle speed sensor 58 (step). S100), the required torque Td * required for the drive shaft 30 is set based on the input accelerator opening Acc and the vehicle speed V (step S110). Here, in the embodiment, the required torque Td * is obtained in advance by storing the relationship between the accelerator opening Acc, the vehicle speed V, and the required torque Td * in the ROM 44 as a required torque setting map. When the vehicle speed V is given, the corresponding required torque Td * is derived from the map. An example of the required torque setting map is shown in FIG.

  When the required torque Td * is set, the required torque change amount ΔTd is calculated by subtracting the set required torque Td * (previous value) by executing this routine last time from the set required torque Td * (current value) (step) S120). Here, the required torque change amount ΔTd can be considered as a change amount of the required torque Td * per unit time because this routine is executed every predetermined time (every 8 msec).

  When the required torque change amount ΔTd is calculated, a temporary rate limit ΔTrl1 is set based on the calculated required torque change amount ΔTd and the vehicle speed V input in step S100 (step S130), and the set temporary rate limit ΔTrl1 and other factors are set. Is set to the rate limit ΔTrl which is smaller than the provisional rate limit ΔTrl2 set from (step S140). Here, the provisional rate limit ΔTrl1 is calculated from the speed of response of the motor 22 when the execution torque T * is set as the torque to be output from the motor 22 based on the required torque Td *, as will be described later. In response to a sudden change in (accelerator opening Acc), the sudden change in the execution torque T * is suppressed to improve the driving feeling, and when the driver truly requests acceleration, the requested torque Td * is quickly increased. In order to ensure acceleration performance in response, in the embodiment, the absolute value of the required torque change amount ΔTd increases as the absolute value of the required torque change amount ΔTd decreases and increases as the vehicle speed V increases. Consider a state where the driver instantaneously turns on and off the accelerator pedal 53 without intending to accelerate. In this state, since the absolute value of the required torque change amount ΔTd is relatively large, a relatively small value is set as the temporary rate limit ΔTrl1. Therefore, even if the required torque Td * changes suddenly, the execution torque T * changes only slowly, and no shock occurs in the vehicle. Next, let us consider a state in which the driver depresses the accelerator pedal 53 with the intention of acceleration. In this state, immediately after the accelerator pedal 53 is depressed, the absolute value of the required torque T * is relatively large and the temporary rate limit ΔTrl1 is set to a relatively small value. The torque T * changes only slowly, but when the accelerator pedal 53 converges with a large opening, the required torque change amount ΔTd becomes relatively small and a relatively large value is set as the temporary rate limit ΔTrl1. The execution torque T * that quickly follows is set, and the vehicle is quickly accelerated. As described above, when the driver truly requests acceleration while suppressing the shock when the driver operates the accelerator pedal 53 without intending acceleration, the acceleration performance is improved by quickly responding to the operation of the accelerator pedal 53. In order to ensure, the provisional rate limit ΔTrl1 is set based on the required torque change amount ΔTd. In the embodiment, the temporary rate limit ΔTrl1 is obtained in advance by storing the relationship between the required torque change amount ΔTd, the vehicle speed V, and the temporary rate limit ΔTrl1 as a rate limit setting map in the ROM 44, and the required torque change amount ΔTd and the vehicle speed. When V is given, it is set by deriving the corresponding temporary rate limit ΔTrl1 from the map. An example of the trend of this rate limit setting map is shown in FIG. The temporary rate limit ΔTrl2 suppresses a change in the execution torque T * with respect to a change in the required torque Td * in order to keep the input / output from the battery 26 within the range of the input / output limit, for example. In order to suppress the rattling noise of the gear of the drive train that occurs when the current value exceeds the value 0 (when the sign differs between the current value and the previous value of the required torque Td *). It can be set as a value necessary to suppress the change of.

  When the rate limit ΔTrl is thus set, it is determined whether or not the required torque change amount ΔTd is within a range determined by the rate limit ΔTrl multiplied by −1 and the rate limit ΔTrl (step S150). When it is determined that the change amount ΔTd is within the range determined by multiplying the rate limit ΔTrl by −1 and the rate limit ΔTrl, the required torque Td * is set as it is to the execution torque T * (step S160). When the torque change amount ΔTd is smaller than the value obtained by multiplying the rate limit ΔTrl by −1, the value obtained by subtracting the rate limit ΔTrl from the previous value of the required torque Td * is set as the execution torque T * in order to perform the lower limit guard ( Step S170), the required torque change amount ΔTd is larger than the rate limit ΔTrl. The Itoki sets plus rate limit ΔTrl the previous value of the torque demand Td * to perform the upper limit guard to the actual torque T * (step S180).

  When the execution torque T * is set in this way, the motor 22 is driven and controlled with this execution torque T * (step S190), and this routine is finished. Specifically, the drive control of the motor 22 is performed by switching control of the switching element of the inverter 24 so that a torque corresponding to the execution torque T * is output from the motor 22.

  FIG. 5 shows an example of how the accelerator opening Acc and the execution torque T * change with time. In the figure, (A) shows how the required torque Td * (accelerator opening degree Acc) changes with time, and (B) in the figure shows the rate when the rate limit ΔTrl is constant and the required torque Td * is subjected to rate processing. FIG. 9C shows the time variation of the execution torque T *, and (C) in the figure sets a rate limit ΔTrl based on the absolute value (| ΔTd |) of the required torque change amount ΔTd and performs rate processing on the required torque Td *. The state of the time change of the execution torque T * when applied is shown. As shown in the figure, when the driver instantaneously turns on and off the accelerator pedal 53 without accelerating from time t1 to t2, when the execution torque T * is set with the rate limit ΔTrl constant, the accelerator pedal 53 (requested torque) Since the execution torque T * also changes suddenly to some extent in response to a sudden change in Td *), a shock occurs in the vehicle (see (B) in the figure). On the other hand, when the rate limit ΔTrl is set based on the required torque change amount ΔTd, the absolute value of the required torque change amount ΔTd is relatively large, so the rate limit ΔTrl is set to a relatively small value. Even if the accelerator pedal 53 (requested torque Td *) changes suddenly, the effective torque T * changes only slowly, and no shock occurs in the vehicle (see (C) in the figure). When the accelerator pedal 53 is greatly depressed at time t3 in order to truly request acceleration, when the execution torque T * is set with the rate limit ΔTrl constant, the execution torque T * becomes the required torque Td * at a constant rate. The vehicle rises toward the vehicle and accelerates (see (B) in the figure). In contrast, when the rate limit ΔTrl is set based on the required torque change amount ΔTd, the absolute value of the required torque change amount ΔTd is relatively large immediately after the accelerator pedal 53 is depressed, and the rate limit ΔTrl is relatively small. Since the value is set to a value, the rise of the execution torque T * is temporarily delayed as compared with the case where the execution torque T * is set with the rate limit ΔTrl constant (see (C) in the figure). However, since the absolute value of the required torque change amount ΔTd becomes relatively small and a large value is set in the rate limit ΔTrl after time t4 when the sudden change in the required torque Td * converges, the execution torque T * is quickly determined as the required torque. The vehicle stands up toward Td * and accelerates quickly.

  According to the electric vehicle 20 of the embodiment described above, the rate limit ΔTrl is set based on the absolute value of the required torque change amount ΔTd (deviation between the current value and the previous value of the required torque Td *), that is, the required torque Td. When * changes suddenly, the absolute value of the required torque change amount ΔTd is relatively large. Immediately after the sudden change, a relatively small value is set as the rate limit ΔTrl, and the absolute value of the required torque change amount ΔTd decreases and the required torque Td *. A relatively large value is set in the rate limit ΔTrl when the sudden change in the value converges, the requested torque Td * is subjected to rate processing with the set rate limit ΔTrl, the execution torque T * is set, and the motor 22 is driven. Therefore, when the driver does not intend to accelerate, such as when the accelerator pedal 53 is momentarily turned on / off, the response of the motor 22 is slowed down. When the shock of the vehicle is suppressed and the accelerator pedal 53 is greatly depressed and the driver truly requests acceleration, the execution torque T * is quickly reached when the sudden change in the required torque Td * (accelerator opening Acc) has converged. The vehicle can be accelerated quickly by following the required torque Td *. As a result, driving feeling can be further improved while maintaining acceleration performance to some extent with respect to the operation of the accelerator pedal 53.

  In the electric vehicle 20 of the embodiment, the execution torque T * is set using the rate process for the required torque Td *. However, the execution torque T * is not limited to the rate process, and other slow change processes such as an annealing process are used. It is also possible to set the execution torque T *. When the execution torque T * is set using the annealing process, the annealing time constant tends to decrease (the response speed tends to increase) as the absolute value of the required torque change amount ΔTd decreases instead of setting the rate limit ΔTrl. Should be set.

  In the electric vehicle 20 of the embodiment, the temporary rate limit ΔTrl1 is set based on the required torque change amount ΔTd. However, only the high frequency component of the required torque Td * is suppressed and the execution torque T * is set. Good. The execution torque T * in this case can be set by applying a low-pass filter that attenuates a high-frequency component that causes a shock to the vehicle to the required torque Td *.

  The electric vehicle 20 according to the embodiment is described as applied to a normal electric vehicle including only the motor 22 as a power source, but may be applied to a hybrid electric vehicle including a motor and an engine as power sources. For example, as shown in a modified electric vehicle 120 in FIG. 6, the present invention may be applied to a hybrid electric vehicle 120 in which an engine 140 and a motor 130 are connected to a drive shaft 30 via a planetary gear mechanism 135. 7, the motor 22B is connected to wheels 35a and 35b different from the drive wheels 34a and 34b to which the drive shaft 30 is coupled in addition to the configuration of the electric vehicle 120 of FIG. As shown in the electric vehicle 220 of the modified example of FIG. 8, the engine 240, an inner rotor 232 connected to the crankshaft of the engine 240, and an outer rotor 234 connected to the drive shaft 30 are included. And a counter-rotor motor 230 that relatively rotates both rotors by electromagnetic action. As shown in the electric vehicle 320 of the modified example, the motor 22 by a clutch CL with via a transmission 330 to the drive shaft 30 connecting the motor 22 may be used to connect the engine 340.

  The best mode for carrying out the present invention has been described with reference to the embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made without departing from the gist of the present invention. Of course, it can be implemented in the form.

  The present invention is applicable to the automobile industry.

It is a block diagram which shows the outline of a structure of the electric vehicle 20 as one Embodiment of this invention. It is a flowchart which shows an example of the drive control routine performed by the electronic control unit 40 of the electric vehicle 20 of an Example. It is explanatory drawing which shows an example of the map for request | requirement torque setting. It is explanatory drawing which shows an example of the map for a rate limit setting. It is explanatory drawing which shows the mode of the time change of accelerator opening Acc and execution torque T *. It is a block diagram which shows the outline of a structure of the electric vehicle 120 of a modification. It is a block diagram which shows the outline of a structure of the electric vehicle 120B of a modification. It is a block diagram which shows the outline of a structure of the electric vehicle 220 of a modification. FIG. 11 is a configuration diagram illustrating an outline of a configuration of a modified example of an electric vehicle 320.

Explanation of symbols

20, 120, 120B, 220, 320 Electric vehicle, 22, 22B motor, 24 inverter, 26 battery, 30 drive shaft, 32 differential gear, 34a, 34b drive wheel, 35a, 35b wheel, 36 rotational position detection sensor, 40 electrons Control unit, 42 CPU, 44 ROM, 46 RAM, 50 ignition switch, 51 shift lever, 52 shift position sensor, 53 accelerator pedal, 54 accelerator pedal position sensor, 55 brake pedal, 58 vehicle speed sensor, 130 motor, 135 planetary gear mechanism , 140 engine, 230 rotor motor, 232 inner rotor, 234 outer rotor, 240 engine, 330 transmission, 340 engine, CL clutch.

Claims (6)

An electric vehicle that can be driven by power from an electric motor,
When the driver's driving force request changes suddenly, at least until the sudden change of the driving force request is converged, the driving force request is subjected to a gradual change process with the first response mode to set the execution driving force, After the sudden change of the driving force request has converged, the execution driving force is set by performing a gradual change process on the driving force request with the second response mode in which the response is faster than the first response mode. Execution driving force setting means;
An electric vehicle comprising: drive control means for driving and controlling the electric motor based on the set execution driving force.   The execution driving force setting means sets the execution driving force by applying the slow change process to the driving force request so that the response becomes faster as the amount of change per unit time of the driving force request decreases. The electric vehicle according to claim 1.   3. The electric vehicle according to claim 2, wherein the execution driving force setting means is means for setting the execution driving force by a smoothing process or a rate process as the slow change process.   The electric vehicle according to claim 1, wherein the effective driving force setting unit is a unit that sets the effective driving force by suppressing a frequency component of a predetermined frequency or higher with respect to the driving force request.   The electric vehicle according to claim 4, wherein the effective driving force setting unit is a unit that sets the effective driving force using a filter that attenuates a frequency component equal to or higher than the predetermined frequency. A method of controlling an electric vehicle that can be driven by power from an electric motor,
(A) When the driver's driving force request suddenly changes, at least until the sudden change of the driving force request is converged, the driving force request is subjected to a gradual change process with the first response mode and the execution driving force is reduced. After the sudden change of the driving force request is set to converge, the driving force request is subjected to a gradual change process with a second response mode in which the response is faster than the first response mode. Set
(B) A method for controlling an electric vehicle that controls driving of the electric motor based on the set execution driving force.

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