JP3307269B2 - Electric vehicle motor control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device for an electric vehicle, and more particularly to control of motor torque at the time of transition from regenerative braking control to power running control.

[0002]

2. Description of the Related Art It is well known that a motor mounted on an electric vehicle is controlled by regenerative braking to decelerate the vehicle and charge a battery. When an accelerator is operated, this type of motor control device generates a motor torque according to the accelerator operation amount. And when the accelerator is turned off or the brake is turned on,
Regenerative braking control for operating the motor as a generator is performed. As a result, a negative torque (torque in the direction opposite to the driving direction) is generated in the motor, and the vehicle is decelerated. At this time, deceleration corresponding to the engine brake state in the conventional engine-equipped vehicle is performed. The driver can decelerate the vehicle with the same feeling as using the engine brake. Further, the electric energy obtained by the regenerative braking is stored in the battery, and the energy efficiency is improved.
This type of motor control device is disclosed, for example, in Japanese Patent Laid-Open No. 5-122.
805 and JP-A-7-99704.

FIG. 1 shows a motor torque characteristic used in a conventional general motor control for performing regenerative braking control, and shows a motor torque according to a motor speed and an accelerator operation amount. The motor control device determines a motor torque command value according to FIG. 1 based on the detected values of the motor rotation speed and the accelerator operation amount, and controls the motor such that a torque corresponding to the determined command value is generated. As shown in FIG. 1, when the accelerator is operated, the motor torque command value is a positive value, and the motor torque generated at this time is called power running torque. The torque command value is changed according to the accelerator operation amount, and the powering torque increases or decreases.
The accelerator operation amount becomes 100% when, for example, the accelerator pedal is depressed to the maximum stroke.
On the other hand, when the accelerator is off (accelerator operation amount 0%),
The motor torque command value is set to a negative value. The motor torque at this time is called a regenerative torque, and is in a direction opposite to the powering torque. When the accelerator is turned off, regenerative torque is generated by regenerative braking control according to the characteristic of the accelerator operation amount of 0% in FIG. 1, and the motor is braked. When the motor speed is low, even if the accelerator operation amount is 0%,
The torque command value becomes positive. This is a setting for generating a power running torque corresponding to a creep torque in a vehicle equipped with a conventional engine and an automatic transmission at the time of stopping and slowing down.

[0004]

It is assumed that the driver is running on a downhill or the like by setting the accelerator operation amount to 0 and applying a brake by regenerative braking (regenerative braking). At this time, in FIG. 1, it is assumed that the motor rotation speed is N1 and the regenerative torque is T1. It is assumed that the deceleration has become slightly too large, so that it is necessary to make a fine adjustment so that the deceleration is slightly reduced, and the driver slightly operates the accelerator, and the accelerator operation amount becomes 20%. At this time, the motor torque rapidly changes from T1 (negative) on the regenerative side to T2 (positive) on the powering side.

FIG. 2 shows the change over time of the motor torque in the above example. Immediately before time t0, the accelerator operation amount is 0%, the motor speed is N1, and the regenerative torque is T1. At time t0, the accelerator is turned on to adjust the effectiveness of the regenerative brake, and
%become. At this time, the torque command value is the regenerative torque T1.
A sudden change from (negative) to powering torque T2 (positive). As shown in the figure, the regenerative torque is suddenly lost, and a power running torque is generated instead, and a large torque gap is generated before and after the accelerator operation.

The above situation typically occurs, for example, while traveling downhill. When the regenerative brake is used similarly to the conventional engine brake, it is necessary to adjust the deceleration according to a change in the situation such as a change in the gradient.

As described above, conventionally, when the accelerator operation for fine adjustment of the deceleration is performed during the regenerative braking, the regenerative torque is suddenly lost and the power running torque is generated, and the gap between the two torques is large. At the moment when the accelerator is operated, the deceleration up to that point ends suddenly, and the driver feels as if the vehicle jumps forward. Unlike when the driver depresses the accelerator strongly for full acceleration with his / her own will, the vehicle behavior changes suddenly even though the deceleration is finely adjusted, so the driver feels uncomfortable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to prevent the occurrence of discomfort when shifting from regenerative braking to power running, so that a driver can comfortably drive using regenerative braking. An object of the present invention is to provide a motor control device.

[0009]

In order to achieve the above object, a motor control device according to the present invention generates a power running torque corresponding to an accelerator operation amount to a motor and controls regenerative braking of the motor when an accelerator is turned off or a brake is turned on. And reduce the vehicle speed. Then, when the accelerator is operated during the regenerative braking control, the present device determines from the current regenerative torque:
Powering transition control is performed to continuously increase the motor torque up to the powering torque corresponding to the accelerator operation amount.

According to the present invention, when the accelerator is operated during the regeneration control, the motor torque continuously changes from the current regeneration torque to the power running torque. Therefore, when a time change of the motor torque is observed, a torque gap such as instantaneous switching from the regenerative torque to the power running torque does not occur as in the related art. Since the deceleration gradually changes when the accelerator is operated, the behavior of the vehicle does not change suddenly, and the occurrence of a sense of discomfort to the driver is avoided. Therefore, the driver can comfortably drive using the regenerative braking.

In one embodiment of the present invention, in the powering transition control, the motor torque is controlled according to the torque characteristic at the time of powering transition set so that the torque command value continuously changes from the regenerative torque to the powering torque in accordance with the accelerator operation amount. Controlled. Normally, a torque characteristic for generating a powering torque in accordance with the accelerator operation amount is applied as in the related art. But,
At the time of powering transition control, the torque characteristic at the time of powering transition is applied. That is, according to the driver's accelerator operation amount, the torque command value is determined to be a value in the range from the regenerative torque to the powering torque in accordance with the torque characteristic at the time of powering transition. In this aspect, the driver can usually adjust the powering torque by operating the accelerator, and can adjust the deceleration to a desired magnitude by operating the accelerator during regenerative braking. Then, the driver can smoothly shift the motor torque from the regenerative side to the power running side by operating the accelerator more than a certain degree. Therefore, at the time of transition to power running, unexpected vehicle behavior does not occur, and control according to the driver's will is performed.

In another aspect of the present invention, the amount of smoothing when changing the motor torque is defined as the amount during normal control,
A variable smoothing control is performed which is changed by the powering transfer control between the time of the transition from the regeneration side to the powering side.

The smoothing control itself is a well-known control in which the torque command value is changed stepwise in order to smoothly perform the motor control. When the accelerator operation amount is changed, the command value is changed in a plurality of steps from a certain torque command value to another torque command value. It is assumed that the larger the smoothing amount, the longer the time required for changing the torque command. The smoothing amount is defined by, for example, the number of steps at which the torque command value is changed. In the conventional smoothing control, the smoothing amount is set as small as possible in order to increase the torque response to the accelerator operation. Therefore, when the accelerator is operated during the regenerative braking, a large change in the torque command value is required. As a result, in the normal smoothing control, the change in the torque command value becomes sharp, and a torque gap occurs before and after the accelerator operation. . Since the driver does not expect the vehicle behavior at this time, the driver feels strange.

In the variable smoothing control according to the present invention, when shifting from regenerative braking to power running, the smoothing amount is changed so that the torque command value changes continuously. When the accelerator is operated during the regenerative braking control, the smoothing amount is changed to a larger value than during the normal control. Therefore, when changing the normal accelerator operation amount, the smoothing amount can be reduced to secure the torque responsiveness to the accelerator operation, and when the accelerator operation is performed during regenerative braking, the smoothing amount can be increased to increase the motor torque rapidly. It is possible to eliminate the change and prevent the driver from feeling uncomfortable.

In another aspect of the present invention, the motor is controlled using a motor torque characteristic in which a motor torque and an accelerator operation amount are associated with a motor torque. The regenerative torque is set to be generated in a region where the accelerator operation amount is small. In the above-described embodiment, the normal motor torque characteristic and the powering transition torque characteristic for powering transition control are used separately. On the other hand, in this embodiment, the above-described proper use is not performed. Therefore, with a simpler control, it is possible to avoid occurrence of a sense of discomfort at the time of shifting to power running.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 Hereinafter, a preferred embodiment of the present invention (hereinafter, referred to as an embodiment) will be described with reference to the drawings. FIG. 3 shows a drive system of an electric vehicle including the motor control device of the present invention. The motor 1 for generating vehicle propulsion is sequentially connected to the speed reducer 3 and the wheels 5. The powering torque generated by the motor 1 is transmitted to the wheels 5 via the reduction gear 3, a differential gear device (not shown), and the like. The motor 1 is connected to a battery 9 via an inverter 7. The inverter 7 is a current adjusting unit that includes a plurality of switching elements and adjusts a current supplied to the motor 1. The motor 1 is driven by a current supplied from the inverter 7.

The motor ECU 11 is a device that controls the motor 1 by supplying a switching signal to the inverter 7. The motor ECU 11 receives a motor rotation speed N from a rotation sensor 13 provided in the motor 1 and a current value I of a supply current to the motor 1 from a current sensor 15. Further, the motor ECU 11 receives an accelerator operation amount θ from the accelerator pedal sensor 17.
Is entered. When the accelerator is off, θ = 0%, and when the accelerator is fully open (when the accelerator pedal is depressed to the full stroke), θ = 100%. Further, information indicating ON / OFF of the brake pedal is input from the brake pedal sensor 19 to the motor ECU 11. When the brake pedal is depressed, the brake is on, and when the brake pedal is not depressed, the brake is off. The motor ECU 1
1, information indicating a vehicle speed V is input from a vehicle speed sensor 21 attached to the speed reducer 3. Vehicle speed sensor 21
Detects the rotation speed of the speed reducer 3. Motor ECU1
1 is provided with a well-known vector controller and a PWM controller, generates a switching signal based on input information, and supplies the switching signal to the inverter 7.

The motor ECU 11 normally controls the motor 1 according to the torque characteristics shown in FIG. FIG. 1 defines the torque to be generated by the motor in association with the motor speed N and the accelerator operation amount θ%. Motor ECU1
1 determines a torque command value according to FIG. 1 based on the input information of the rotational speed N and the accelerator operation amount θ%. The motor ECU 11 obtains a current command corresponding to the determined torque command based on the motor rotation speed N and the motor current I, and further generates a switching signal corresponding to the current command. This switching signal is output to the inverter 7, and the switching element of the inverter 7 operates according to the switching signal. Thus, the DC current supplied from the battery 9 to the inverter 7 is converted into an AC current by the inverter 7 and supplied to the motor 1. here,
The switching signal is set based on the torque command value. Therefore, the motor 1 is driven by the current supplied from the inverter 7, thereby
A torque corresponding to the command value determined in 1 is generated.

As shown in FIG. 1, the accelerator operation amount is 0%
, The torque command value becomes regenerative (negative). The motor ECU 11 performs regenerative braking control by outputting a switching signal to the inverter 7. At this time, the motor 1 is rotated by the rotational force of the wheels 5 and operates as a generator. The generated current is converted into a DC current by an inverter 7 operating according to the switching signal, and the battery 9 is charged. The regenerative torque to be generated by the motor 1 is shown in the line of 0% of the accelerator operation amount in FIG. 1, and the motor 1 is controlled so that the regenerative torque on this line is generated. The regenerative torque is in the opposite direction to the power running torque, and the regenerative torque acts as a resistance to decelerate the vehicle.

By the way, when the accelerator is operated during the regenerative braking control, the regenerative torque up to that point suddenly disappears and a power running torque is generated instead, as described with reference to FIG. When the accelerator is operated relatively large, the driver demands rapid acceleration, and there is no major problem. But,
When the driver slightly operates the accelerator for the purpose of fine adjustment of the regenerative braking force, when the regenerative torque is suddenly lost, the driver has a feeling that the vehicle suddenly jumps out,
Feel something is wrong. Then, in order to cope with such a situation, the motor ECU 11 adjusts the torque command value as follows.

FIG. 4 shows a characteristic control of the present embodiment. The motor ECU 11 repeatedly executes the processing of FIG. 4 at predetermined intervals. First, it is determined whether or not the second flag (F2) is set (S10). If the second flag is already set, the process proceeds to step S24 described below. If the second flag has not been set, the current vehicle speed Vi is compared with the vehicle speed Vi-1 at the time of the previous control routine (one control cycle before) (S12). When Vi is equal to or greater than Vi-1, the vehicle is not decelerating, so the first flag and the second flag are cleared (S1).
4) Return. When Vi <Vi-1, it is determined whether or not the accelerator operation amount θ = 0% (S16). θ ≠ 0
At this time, it is determined whether or not the first flag (F1) is set (S18). If not, the process returns. If the first flag is set, the process proceeds to step S24. When θ = 0 in step S16, θ is 0 in the next step S20.
Is determined (whether the accelerator has been depressed since θ = 0), and if NO, the first flag is set (S22) and the routine returns. When the accelerator operation amount is detected in step S20, the process proceeds to step S24.

By the processing so far, occurrence of a situation where the accelerator is operated during deceleration and during regenerative braking control is detected. In other words, even during deceleration, the process of returning to step S16 is continued before the accelerator is turned off. When the accelerator is turned off, regenerative braking starts. At this time, the process proceeds from step S16 to step S20, and a first flag is set in step S22. While the accelerator-off state (θ = 0) is maintained, the processing returned in step S20 is repeated. However, when the accelerator is turned on from this state, step S
16 is NO (θ ≠ 0), and since the first flag has already been set, step S18 becomes YES and the process proceeds to step S24.

In step S24, it is determined whether or not the accelerator operation amount is equal to or less than a first threshold value θa (0 <θ ≦ θa). When the accelerator operation amount is equal to or less than the first threshold value θa, the motor ECU 11 does not follow the torque characteristic of FIG.
The motor torque characteristics are changed (S26). At this time, control according to the torque characteristic at the time of powering transition as shown in FIG. 5 is performed. The horizontal axis in FIG. 5 is the accelerator operation amount, and the vertical axis is the torque command value. The dotted line in FIG. 5 shows the relationship between the accelerator operation amount and the power running torque when the rotational speed is a certain value in FIG. According to FIG. 1 as in the case of the normal control, the torque command value T * becomes
T * = θ · Tmax / 100 is determined. However, in the torque characteristic at the time of powering transition, when θ = 0, T * = Tx, θ
= Θa, it is determined that T * = 0. That is, T *
= Θ × Tx / θa−Tx.

Here, Tx is a torque command value when the accelerator operation amount is 0% in FIG. 1 and is a function of the motor speed. Therefore, the characteristic line in FIG.
Up and down in response to changes in

The first threshold value θa is a value for judging whether or not the driver desires fine adjustment of the regenerative braking force, and is determined in advance assuming a standard driver. I have. For this determination, the first threshold value is set to a relatively small accelerator operation amount. By appropriately adjusting the first threshold value θa, the driver can adjust the degree of regenerative braking to a desired level by operating the accelerator. However, if θa is too large, the response to the accelerator operation will be low. If θa is too small, the driver may feel uncomfortable due to a sudden change in torque. In consideration of these points, the first step is to obtain a comfortable driving feeling.
A threshold has been set. The first threshold value θa can be determined based on experiments. Although it varies depending on the vehicle, motor characteristics, etc., preferably, θa is preferably about 10 to 15.

After the characteristic change in step S26, a second flag is set (S28), and the routine returns. Therefore, while the accelerator operation amount is equal to or smaller than θa, Y is determined in step S10.
ES, since YES is determined in step S24, the control for generating the regenerative torque in accordance with the accelerator operation amount is continued. As described above, in the present embodiment, even when the accelerator is operated during the regenerative braking, if the accelerator operation amount is smaller than θa, the regenerative braking is continuously performed. Then, the motor torque, which was Tx before the accelerator operation, becomes θ
= Θa, the motor torque smoothly and gradually changes according to the accelerator operation amount so as to become 0 at θa.

On the other hand, when θ> θa in step S24, it is determined whether or not the second flag is set (S3).
0). It is assumed that the driver further depresses the accelerator while the characteristic change in step S26 is being performed. When the accelerator operation amount becomes larger than θa, step S
The determination at 30 is YES. Then, power running transition control based on the second characteristic change is performed (S32). The content of the characteristic change here is shown in FIG. 5, following the characteristic change in step S26 described above. As shown by the solid line in the figure, when θ = θa, T * = 0. And θ = θb
It is assumed that T * = θb · Tmax / 100. θb is referred to as a second threshold. That is, T * = (θb · Tmax / 100) · (θ−θ
b) / (θb−θa). Therefore, the characteristic line m2 indicating the torque command on the powering side according to the second characteristic change is represented by θ = θ
At a, it is continuous with the regenerative side characteristic line m1 according to the above-described first characteristic change, and at θ = θb, it is continuous with the normal torque characteristic line m3. Note that Tmax is
As shown in FIG. 1, it is a function of the motor speed N. Therefore, the characteristic lines m2 and m3 in FIG. 5 also rise and fall in accordance with the rotation speed, similarly to the characteristic line m1.

As described above, the characteristic line m2 is for smoothly connecting the regenerative-side characteristic line m1 and the characteristic line m3 for normal control. Second threshold value θb
Is appropriately adjusted, the return to the normal torque characteristic is smoothly performed after the shift to the power running control. Second
The threshold value θb can also be determined based on an experiment assuming a standard driver. Also, as described later, the second
The threshold may also be variable.

After the characteristic change in step S32, it is determined whether or not the accelerator operation amount θ = 0 or θ ≧ θb (S34). If YES, the flag is cleared (S14).
To return. If NO, that is, if 0 <θ <θb, it is determined whether the brake pedal is on or off (S36).
If the brake is off, the routine returns. If the brake is on, the flag is cleared (S14) and the routine returns.
As described above, when the accelerator is turned off again, when the accelerator is depressed by θb or more, and when the brake is depressed, the motor ECU 11 returns to the normal control and follows the torque map of FIG. While the accelerator operation amount is smaller than θb, the characteristic change according to FIG. 5 is continued. During this time, 0 <
If θ ≦ θa, the process proceeds to step S26 to perform regenerative braking control for generating a regenerative torque, and if θa <θ <θb, the process proceeds to step S32 to perform power running control.

The determination in step S30 becomes NO in the following cases. It is assumed that the driver attempts rapid acceleration during regenerative braking with the accelerator off. Since the driver suddenly steps on the accelerator greatly, the accelerator operation amount changes at once to a value larger than θa. In this case, the process proceeds to step S30 via steps S16, S18, and S24. NO because the second flag is not standing
After the flag clear (S14), the process returns. Therefore, the motor ECU 11 generates the powering torque according to the map of FIG. 1 by the normal control without changing the characteristics in step S26. In this case, since the driver desires rapid acceleration, there is no particular problem even if the torque suddenly changes. Rather, a quick torque response is required. In such a situation, the above processing realizes a fast torque response and a sudden acceleration.

FIG. 6 is a time chart showing an operation example of an electric vehicle provided with the motor control device of the present embodiment.
From the top, the accelerator operation amount, the torque command value, the acceleration / deceleration of the vehicle, and the vehicle speed are shown. In FIG. 6, the solid line indicates the operation of the present embodiment. On the other hand, the dotted line shows the operation of the conventional vehicle drive system, and shows the control result when only the torque map of FIG. 1 is used. Here, for simplicity of description, it is assumed that the running resistance of the vehicle is zero.
Therefore, if the torque command value is positive (powering side), the vehicle accelerates,
If the torque command value is negative (regeneration side), decelerate.

(Period A) Before time ta, the accelerator operation amount is 0%. During this time, regenerative braking control according to the torque map of FIG. 1 is performed. Then, as the vehicle decelerates with the passage of time and the motor speed decreases, the regenerative torque also gradually decreases.

(Period B) The driver steps on the accelerator at time ta to adjust the effectiveness of the regenerative brake, and the accelerator operation amount reaches the first threshold value θa at time tc. At this time, conventionally, a power running torque is generated as shown by a dotted line. Then, the acceleration is suddenly generated after the deceleration disappears, and the vehicle speed also starts to increase from decreasing. The driver feels that the vehicle jumps out. However, in this embodiment,
The characteristic changing process in step S26 in FIG. 4 is performed, and a regenerative torque is generated according to the accelerator operation amount according to FIG. Accordingly, the acceleration / deceleration also changes on the deceleration side. The vehicle speed continues to decrease at a slower pace than before time ta. Since the driver has increased the accelerator pedal depressing speed at time tb before reaching time tc, the speed at which the torque command value changes also increases.

(Period C) After the accelerator operation amount exceeds the first threshold value θa at time tc, the operation amount becomes θc at time td.
Reach The operation amount θc is a value slightly smaller than the second threshold value θb. Here, the process of step S32 in FIG. 4 is performed, and the power running control in the range of θa <θ <θb is performed according to FIG. 5, and the vehicle speed also increases. If the torque map of FIG. 1 is used as in the related art during this period, a sudden change in torque occurs as shown by a dashed line n in the figure. However, in the present embodiment, as shown, the torque changes continuously.

(Period D) At time td, the driver determines that necessary brake adjustment has been completed, and releases the accelerator. As a result, the accelerator operation amount decreases, and the time t
e = θa, accelerator off at time tf (θ = 0)
become. During this period, in the conventional case, the torque command value changes as indicated by a dotted line. That is, the torque command value is positive until the accelerator is turned off, and a regenerative torque is generated at the moment when the accelerator is turned off. Therefore, the driver feels a shock accompanying the sudden deceleration. However, according to the present embodiment, the characteristic change in step S32 in FIG. 4 is performed from td to te, and the characteristic change in step S26 in FIG. 4 is performed from te to tf. Therefore, the torque command value continuously decreases according to the accelerator operation. Accordingly, the acceleration / deceleration also changes continuously. When the accelerator is turned off, the motor E
The CU 11 returns to the normal control, and the torque command value becomes a value on the line of the operation amount 0% in FIG.

Next, an example in which the threshold value of the accelerator operation amount is made variable will be described with reference to FIGS. As shown in FIG. 7, as the vehicle speed V increases, the first threshold value θa,
Each of the second threshold values θb is increased. Each line in FIG. 7 is set based on the fact that the higher the vehicle speed, the easier it is to drive if the response of the torque change to the accelerator operation is lowered. Each line can be set based on experiments assuming a standard driver. By applying the variable setting in FIG. 7, the torque command value is determined as shown in FIG. That is, when the vehicle speed is V1, T * = θa1.
0, and returns to normal powering torque control at θb1. When the vehicle speed is high (V3), both the accelerator operation amount that shifts to the power running side and the accelerator operation amount that returns to the normal control increase.

In FIG. 9, the first threshold value θa and the second threshold value θb are increased as the deceleration of the vehicle increases. The deceleration is based on the detection result of the vehicle speed V, and the motor EC
It is calculated in U11. Each line in FIG. 9 is set based on the fact that it is easier to drive when the responsiveness of the torque change to the accelerator operation is reduced during rapid deceleration. As above, each line can be set based on an experiment assuming a standard driver. When FIG. 9 is applied, FIG.
Is determined as shown in FIG. In addition,
The threshold change according to the vehicle speed in FIG. 7 and the threshold change according to the deceleration in FIG. 8 may be performed in combination.

In this embodiment, the torque command value is changed linearly during the powering transition control. On the other hand, as shown by a curve L in FIG. 10, a map in which the torque command value changes along the curve L is set in advance,
The torque command value may be determined according to the line of this map. Note that FIG. 10 shows only the torque characteristics on the powering side (for step S32 in FIG. 4) in which the operation amount is larger than θa, but the same applies to the regenerative side with θa or less.
Further, the shape of the curve L may be changed according to the vehicle situation. For example, according to the speed of accelerator operation,
Curves of different shapes may be employed for control.

The embodiment has been described above. In this embodiment, when the accelerator is operated during regenerative braking,
Powering transfer control as shown in FIG. 5 is performed. Since the magnitude of the regenerative torque can be adjusted by operating the accelerator, the occurrence of a sense of discomfort due to the instantaneous loss of the regenerative torque is avoided. When the control immediately shifts to the conventional control immediately after the accelerator operation amount exceeds θa, the torque suddenly changes as shown by a dashed line n in FIG. However, in the powering transition control of the present embodiment, as shown in FIG.
The control is shifted to the normal control after the continuous torque change during the period of, so that there is no sudden change in the torque. As described above, according to the present embodiment, when the accelerator is operated during the regenerative control, the motor torque continuously and smoothly changes from the regenerative torque to the power running torque, so that the vehicle behavior does not suddenly change. Therefore, occurrence of a feeling of strangeness to the driver is avoided, and the driver can comfortably drive using regenerative braking.

[Embodiment 2] Next, the second preferred embodiment of the present invention will be described.
An embodiment will be described. In the first embodiment, the torque characteristics for determining the torque command value are changed as the powering transfer control. In the second embodiment, as described below, the smoothing amount for the smoothing control is changed as the powering transfer control. Note that the configuration of the vehicle drive system including the motor control device of the present embodiment is the same as that of FIG. 3, and a description thereof will be omitted.

First, a conventionally known smoothing control will be described with reference to FIG. When the driver changes the accelerator operation amount,
The motor ECU 11 changes the motor torque according to FIG. At this time, the torque command value is changed from Tp to Tq (Tp <Tq). In order to perform the control smoothly, the torque command value is changed stepwise as shown in FIG. This stepwise change is the smoothing control. In the smoothing control, the amount of torque change (Tq−T
The number of divisions of p) is determined. FIG.
In the example of 1, the smoothing amount is 4. Then, the torque command value is changed by (Tq-Tp) / 4 for each control cycle. After four cycles, a switching signal based on the torque command value Tq is generated.

The above-described smoothing control is conventionally performed by the motor E
This is executed at the time of a normal torque change in the CU 11. However, if the smoothing amount is increased, the responsiveness of the motor torque to the accelerator operation decreases. Therefore, the smoothing amount is usually set as small as possible within a range where the motor can be smoothly controlled. In FIG. 2 described above, normal averaging control is performed, but the averaging amount is small. Therefore, the motor torque changes substantially instantaneously from the regenerative torque T1 to the power running torque T2, and the smoothing effect is not shown in the drawing.

In this embodiment, during normal control, the smoothing amount is set to a small value d0 as in the conventional case. Thereby, the response of the torque to the change of the accelerator operation amount is increased.
At the time of powering transition control, that is, when the accelerator is operated during the regenerative braking control, the smoothing value is changed by the following control. Thereby, a sudden change in torque can be avoided.

FIG. 12 shows the characteristic control of this embodiment. The motor ECU 11 repeatedly executes the processing of FIG. 12 at predetermined intervals. Referring to FIG.
The processing of 0 to S22 is the same as the processing described with reference to FIG. Through these processes, occurrence of a situation where the accelerator is operated during deceleration and during regenerative braking control is detected.

In step S40, it is determined whether or not the accelerator operation amount is equal to or less than the first threshold value θa (0 <θ ≦ θa). The first threshold is set in the same manner as in the first embodiment. When θ> θa, the case where the driver suddenly steps on the accelerator greatly and the accelerator operation amount changes to a value larger than θa from the accelerator off state.
At this time, it is determined that the driver desires rapid acceleration. Therefore, in order to perform normal smoothing control (smoothing amount d0) to realize a high torque response, the flag clear (S
After 14), return.

In step S40, the accelerator operation amount becomes the first
When the threshold value θa or less (0 <θ ≦ θa), the motor EC
U11 changes the amount of smoothing (S42). This process will be described with reference to FIGS. FIG. 13 is a map for determining the smoothing amount.
Remembers. In FIG. 13, the horizontal axis represents the elapsed time from the accelerator operation, and the vertical axis represents the smoothing amount at each time point. As illustrated, in step S40, the smoothing amount is set to be larger than the normal time d0. And it is greatly changed sequentially in each cycle. Further, the smoothing amount is determined to be different according to the magnitude of the accelerator operation amount of the driver.
In the figure, there is a relationship of 0 <θ1 <θ2 <θ3 <θa.

FIG. 14 shows a time change of the torque command value when the control is performed using the smoothing amount determined based on the map of FIG. FIG. 14 shows only a part of the torque command value changing process. As shown in FIG. 13, the smoothing amount increases every one cycle. The larger the smoothing amount, the smaller the torque command value change width for one step. The torque command value change width for one step is
This is because the total torque change width is reduced by the smoothing amount. Therefore, as shown in FIG. 14, the torque command value changes along an upwardly convex curve as a whole. That is, the speed of change of the torque command value gradually decreases.

In step S42, the torque command for one stage shown in FIG. 14 is changed for one process (process for one control cycle). Next, it is determined whether or not the smoothing control has been completed (S44).
After 4), return. The smoothing control ends when
This is when the torque command value reaches a value corresponding to the actual accelerator operation amount. If the smoothing control is not completed, the second flag is set to determine whether the brake pedal is on or off (S48). If the brake is off, the process returns as it is; if the brake is on, the flag is cleared (S48).
14) Return. Until the smoothing control ends without the brake being depressed, step S10 is YES, and the control shown in FIGS. 13 and 14 is performed.

FIG. 15 shows a time change of the motor torque when the powering transition control of the second embodiment is performed in the same situation as in FIG. Conventionally, even when an accelerator is operated during regenerative braking, normal smoothing control is performed, so that the motor torque rapidly changes as shown by a dotted line. In the second embodiment, as a result of increasing the amount of smoothing in such a situation, the motor torque continuously changes from the regenerative torque T1 to the powering torque T2 as shown by the solid line.
Also, by changing the smoothing amount for each control cycle,
The speed at which the torque command value changes gradually decreases. Therefore, at the time of transition from the smoothing control state to the normal power running control state, the motor torque changes smoothly, so that the driving feeling is further improved.

The motor control device according to the present embodiment has been described above. According to the present embodiment, when changing the normal accelerator operation amount, the smoothing amount can be reduced to secure the torque responsiveness to the accelerator operation, and by increasing the smoothing amount during the accelerator operation during regenerative braking. In addition, a sudden change in the motor torque is eliminated, and the driver can be prevented from feeling uncomfortable.

Embodiment 3 Next, the third preferred embodiment of the present invention will be described.
An embodiment will be described. The configuration of the vehicle drive system including the motor control device of the present embodiment is the same as that of FIG.
The description here is omitted.

In the first embodiment, the torque characteristic for normal control (FIG. 1) and the torque characteristic for powering transition control are selectively used. As a result, normally, a powering torque corresponding to the accelerator operation is generated as in the related art, and a regenerative torque is generated according to the accelerator operation at the time of the powering transfer control. On the other hand, in the third embodiment, the torque characteristics as described above are not properly used. Then, the conventional torque map of FIG. 1 is not used, and the processing according to the flowchart of FIG. 4 is not performed. In the third embodiment, FIG.
The motor 1 is controlled according to the torque map shown in FIG.

As shown in FIG. 16, the accelerator operation amount is 0%
The motor torque at the time of (1) is positive (power running side) due to the generation of creep torque in a region where the rotation speed corresponding to the slow running of the vehicle is low. When the rotation speed becomes higher than a certain level, the motor torque becomes negative (regeneration side) and decreases according to the rotation speed. Then, the torque changes to a value corresponding to a negative torque generated by pumping loss or friction of a normal gasoline engine, or to a torque determined by an experiment or the like.

When the accelerator operation amount is 20%, conventionally, as shown in FIG. 1, the motor torque is positive in the entire rotation speed range. On the other hand, in the third embodiment, as shown in FIG. 16, the motor torque becomes negative in a region where the rotation speed is larger than Nα. Similarly, when the accelerator operation amount is 40%, the motor torque becomes negative in a region higher than the rotation speed Nβ. Above the maximum speed (Nγ) of the power running control, the motor torque becomes negative even when the accelerator operation amount is 80% or 100%.

As a general rule, the motor ECU 11 always
The motor 1 is controlled according to the torque characteristics shown in FIG. The motor ECU 11 determines the torque command value according to FIG. 16 based on the input rotation speed N and the accelerator operation amount θ%. Then, a switching signal corresponding to the torque command value is generated and output to the inverter 7. When the inverter 7 performs current adjustment according to the switching signal, a torque corresponding to the determined command value is generated in the motor 1. In the region where the motor torque is negative, the motor EC
U <b> 11 performs regenerative braking control by outputting a switching signal to the inverter 7. At this time, the motor 1
Operate as a generator, and a regenerative torque according to FIG. 16 is generated. The vehicle is decelerated due to regenerative torque.

For example, the rotation speed N1 and the accelerator operation amount 0%
Assume that In this state, when the driver operates the accelerator to an operation amount of 20%, conventionally, the driver suddenly generates a power running torque, and the driver feels strange. On the other hand, as shown in FIG. 16, in the third embodiment, even if the accelerator is operated up to the operation amount of 20%, the motor torque is still negative. When the accelerator operation amount reaches 40%, the motor torque becomes positive. Accordingly, there is no sudden loss of regenerative torque even when the accelerator is depressed. The driver can adjust the magnitude of the regenerative torque by operating the accelerator.

Each line in FIG. 16 is determined assuming a standard driver. In a conventional engine-equipped vehicle, the degree of effectiveness of the engine brake could be adjusted by operating the accelerator. In the present embodiment, the same brake force adjustment is realized by the regenerative brake based on the characteristics shown in FIG. Therefore, the line with the accelerator operation amount of 20% and 40% indicates that "when the accelerator operation is performed at what vehicle speed, the driver will try to adjust the regenerative braking effect as well as the engine brake. Is it set as a reference? When the rotational speed is equal to or higher than Nα, the regenerative braking is effective when the accelerator operation amount is 20%, and when the rotational speed is Nβ or more, the regenerative brake is effective when the accelerator operation amount is 40% or less. If the rotation speeds Nα and Nβ are too large, the driver feels that the response to the accelerator operation is low. If the rotation speeds Nα and Nβ are too small, the driver may feel uncomfortable due to a sudden change in torque. In consideration of such points, each line is set so that a comfortable driving feeling is obtained. Each line can be determined based on experiments.

The motor control device according to the present embodiment has been described above. According to the present embodiment, similarly to the first embodiment, when the accelerator is operated during the regenerative braking, the motor torque does not change suddenly, so that a feeling of strangeness to the driver is avoided.

In this embodiment, the regenerative braking control is performed when the accelerator operation amount becomes small even when the accelerator is not operated during the regenerative braking. For example, if the accelerator is operated 100%
Even when it is lowered, regenerative braking starts when it falls below a certain level. This is a difference in operation from the first embodiment. In the first embodiment, a regenerative torque corresponding to the accelerator operation is generated only when the accelerator is operated during the regenerative braking.

In the first embodiment, normally, a powering torque corresponding to the accelerator operation is generated, and only during the powering transition control,
It is characterized in that a regenerative torque is generated according to the accelerator operation. Embodiment 3 does not have such a feature. However, in the third embodiment, since the torque command value may be determined always using the map of FIG. 16, there is an advantage that the control is simple.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing the magnitude of motor torque according to the number of revolutions as a conventional general motor torque characteristic.

FIG. 2 is a time chart showing a change in motor torque when control is performed according to the torque characteristics of FIG. 1 and an accelerator is operated during regenerative braking.

FIG. 3 is a block diagram of a drive system of an electric vehicle including the motor control device according to the first embodiment of the present invention.

FIG. 4 is a flowchart showing an operation relating to powering transition control of the motor control device of FIG. 3;

FIG. 5 is an explanatory diagram showing torque characteristics for powering transfer control used in the control of FIG. 4;

FIG. 6 is a time chart illustrating an operation example of the motor control device of FIG. 3 and a vehicle including the motor control device.

FIG. 7 is an explanatory diagram showing variable setting of torque characteristics in powering transfer control of FIG. 4;

FIG. 8 is an explanatory diagram showing variable setting of torque characteristics in the powering transfer control of FIG. 4;

FIG. 9 is an explanatory diagram showing variable setting of torque characteristics in the powering transfer control of FIG. 4;

FIG. 10 is an explanatory diagram showing variable setting of torque characteristics in the powering transfer control of FIG. 4;

FIG. 11 is an explanatory view showing a conventionally known smoothing control according to the second embodiment of the present invention.

FIG. 12 is a flowchart illustrating an operation related to powering transition control of the motor control device according to the second embodiment.

FIG. 13 is an explanatory diagram showing a map for determining a smoothing amount by variable smoothing control according to the second embodiment.

FIG. 14 is an explanatory diagram showing a change in a torque command value when performing variable tempering control using FIG. 13;

FIG. 15 is an explanatory diagram showing a time change of a motor torque when the powering transfer control according to the second embodiment is executed.

FIG. 16 is an explanatory diagram illustrating torque characteristics applied to the motor control device according to the third embodiment.

[Explanation of symbols]

1 motor, 3 reduction gears, 5 wheels, 7 inverters,
9 battery, 11 motor ECU, 13 rotation sensor,
15 Current sensor, 17 Accelerator pedal sensor, 19
Brake pedal sensor.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Naoki Moriguchi 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (56) References JP-A-5-191904 (JP, A) JP-A-60-134707 (JP, A) JP-A-62-221805 (JP, A) JP-A-10-201013 (JP, A) JP-A-6-343207 (JP, A) JP-A-6-245314 (JP, A) ( 58) Field surveyed (Int.Cl. ⁷ , DB name) B60L 7/14 B60L 7/16 B60L 15/20

Claims (2)

(57) [Claims] 1. A motor control device for an electric vehicle that generates a powering torque corresponding to an accelerator operation amount to a motor and controls regenerative braking of the motor when an accelerator is off or a brake is on to reduce a vehicle speed. when the accelerator is operated, the current state of the regenerative torque, to power torque corresponding to the accelerator operation amount, have <br/> line powering transition control for increasing the motor torque continuously, in the power running migration control, regenerative Running torque from torque
Torque command value continuously according to the accelerator operation amount until
According to the torque characteristics at the time of powering transition set to change.
A motor control device for an electric vehicle, wherein the motor torque is controlled . 2. The motor control device for an electric vehicle according to claim 1, wherein a change speed of the motor torque during the powering transfer control changes with time.