JP2685644B2 - Electric car - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electric vehicle, and more particularly to an electric vehicle suitable for drivability.

[Conventional technology]

2. Description of the Related Art In recent years, an electric vehicle that runs using an installed battery as a power source has been receiving attention. One of the reasons for this is that the internal combustion engine emits harmful exhaust gas, whereas the electric vehicle is excellent in environmental friendliness. In addition, an electric vehicle generally has a motor that drives wheels, and the traveling state is controlled by controlling the current supplied to the motor.

Control of the running state of such an electric vehicle is performed, for example,
It is known from JP-A-62-138002. According to this, first, the driving force of the motor is determined according to the accelerator position, and then the driving speed of the motor is determined according to the driving force of the motor and the vehicle speed. Are in control.

[Problems to be solved by the invention]

Generally, an elastic member such as a shaft for transmitting torque is often used in a vehicle, and the entire vehicle constitutes an elastic system. Therefore, when the rotation of the motor reaches a specific frequency, the vehicle resonates, giving the driver an extremely uncomfortable feeling. In the above-mentioned prior art, consideration for such vehicle resonance is lacking, and there is a problem that the driver feels uncomfortable.

In view of the above, an object of the present invention is to provide an electric vehicle capable of avoiding pulsation of the vehicle due to resonance of the motor mounted on the vehicle and the vehicle.

[Means for solving the problem]

The purpose is a battery, a motor for driving wheels,
Storage means for storing a traveling state of the vehicle when vibration occurs in the vehicle, and a current supplied from the battery to the motor are controlled, and when the vehicle approaches the traveling state stored in the storage means, An electric vehicle, comprising: a controller that adjusts at least one of a current value supplied to a motor and an inverter frequency.

[Action]

When the vibration of the vehicle is detected and the vibration of the vehicle occurs, the current value or the inverter frequency supplied to the motor is adjusted. For this reason, vibration of the vehicle is suppressed, and discomfort during driving is avoided.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. FIG. 1 is a system configuration diagram in which front wheels of an electric vehicle are independently driven by induction motors. The left front wheel 2a and the right front wheel 2b in the electric vehicle 1 are induction motors 3 respectively.
It is connected to a and 3b and is independently driven by the inverters 4a and 4b. These inverters are controlled by PWM pulses P _a and P _b , and convert electric power supplied to the motor using the battery 5 as a power source.

The control device 6 for generating the PWM pulses P _a and P _b inputs the access depression amount X _a and the brake depression amount X _b obtained from the accelerator pedal 7 and the brake pedal 8, respectively, which are the operation outputs of the driver. .

Other input signals to the controller 6, the forward, backward mode signal M _b operating mode lever 9 parking the driver instructs the steering angle signal of the steering angle sensor 11 for detecting a steering angle of the steering wheel 10 theta _s , left front wheel 2a, right front wheel 2b, left rear wheel 2c, right rear wheel 2d
Rotation detectors 12a, 12b, 12c, which detect the rotation speed of
12d rotation speed signals ω _a , ω _b , ω _c , ω _d , induction motors 3a, 3b
There are speeds ω _L and ω _R. The control device 6 further outputs the output signal of the G sensor 20 that detects the acceleration of the vehicle and the acceleration signal g, and the output signals of the torque sensors 22a and 22b that detect the torque of the axle and outputs the torque signals T _a and T _b. is there. With these input signals, the PWM pulses P _a and P _b for controlling the two induction motors 3a and 3b are calculated, and the corresponding inverters 4a and 4b are calculated.
Output to each.

 FIG. 2 shows the details of the control device 6.

The control device 6 includes a vehicle driving arithmetic circuit 16, a speed control circuit 17a,
17b, current control circuits 18a and 18b, and PWM control circuits 19a and 19b. The vehicle operation control circuit 16, an accelerator depression amount X _a, the brake depression amount X _b, a steering angle theta _s, each wheel left velocity command from the rotational speed of the ▲ omega ^* _L ▼, and the right speed command ▲ omega ^* _R ▼ the The speed control circuits 17a and 17
output to b.

The speed control circuits 17a and 17b perform feedback control so that the outputs of the rotation detectors 12a and 12b are equal to the speed commands ▲ ω ^* _L ▼ and ▲ ω ^* _R ▼, and the current commands ▲ i ^* _a ▼ and ▲ i ^* _b. Output ▼. The current commands ▲ i ^* _a ▼, ▲ i ^* _b ▼ are
Current commands for each of the three phases ▲ i ^* _au ▼, ▲ i ^* _ay ▼, ▲ i ^*
_aw ▼ and ▲ i ^* _bu ▼, ▲ i ^* _by ▼, and ▲ i ^* _bw ▼.

The current control circuits 18a and 18b use the current values i _a of the inverters 4a and 4b.
(I _au , i _av , i _aw ), i _b (i _au , i _ay , i _aw ) is the current command ▲ i
Feed back control is performed so that it becomes equal to ^* _a ▼, ▲ i ^* _b ▼, and voltage command ▲ V ^* _a ▼ (▲ V ^* _au ▼, ▲ V ^* _av ▼, ▲
V ^* _aw ▼), ▲ V ^* _b ▼ (▲ V ^* _bu ▼, ▲ V ^* _bv ▼, ▲
V ^* _bw ▼) is output.

The PWM control circuits 19a, 19b use voltage commands ▲ V ^* _a ▼, ▲ V ^* _b
Based on ▼, PWM pulse P _a (P _au , P _av , P _aw ), P _b (P _bu , P
Output P _bv , P _bw ). Inverters 4a and 4b are PWM P _a and P _b
The pulse cuts off the voltage from the battery 5 and supplies a predetermined voltage V _a , (V _au , V _av , V _aw ), V _b (V _bu , V _bv , V _bw ) to the induction motors 4a, 4b. To do.

In addition, the current command i _a (i
_au , i _av , i _aw ) command value is determined by calculating the current value so that the torque obtained from the result of the speed control calculation is obtained.In addition to this, in addition to this, the left front wheel 2a, the right front wheel 2b The torque sensor 22a, 22b is provided on the axle, and the torque signals T _a , T _b are fed back, and the torque obtained from the result of the speed control calculation is compared to determine the optimum current i _au , i _av , i _aw. You may.

FIG. 3 is a block diagram showing the operation of the vehicle motion calculation circuit 16. The vehicle motion calculation circuit 16 is composed of a digital computer, and the one shown in the block diagram of FIG. 3 is stored in advance as a program and operates according to this program. Note that this operation is repeatedly executed every 10 msec. Since the speed commands ▲ ^* _L ▼ and ▲ ω ^* _R ▼ are calculated in the same manner, the calculation of ω * will be described below.

First, in block 302, the first initial speed ω ₀ is obtained from the accelerator depression amount X _a . The first initial velocity ω ₀ is
Advance in association with the accelerator pedal depression amount X _a is stored in the storage means, can be in cowpea to be read sequentially.

In parallel with block 302, in block 304, determine the initial acceleration g 'from the accelerator depression amount X _a. Initial acceleration g '
Is stored in the storage means in association with the advance accelerator depression amount X _a, it can be in cowpea to be read sequentially.
Using this initial acceleration g ', a block 306 obtains the second initial velocity ω ₀ '. That is, the predetermined time (Δt)
It is calculated from the previous actual wheel speed (rear wheel) ω _s0 and the initial acceleration g ′ using the following equation (1).

ω ₀ ′ = ω _s0 + ∫g ′ dt (1) The calculation of the actual vehicle speed ω _s0 before the predetermined time will be described later.

In block 308, the first initial velocity ω ₀ obtained in block 302 and the second initial degree ω ₀ ′ obtained in block 306 are compared, and the smaller value is set as the target velocity ω.

The target speed ω obtained in block 308 is calculated in block 310.
Correct acceleration / deceleration. The acceleration / deceleration correction will be described in detail below. First, the output of the G sensor 20 is compared with a predetermined comparison value. When the output of the G sensor 20 is larger than the comparison value, the target speed is adjusted so that the acceleration / deceleration is reduced. That is, using the following addition / subtraction correction value ω _acc , it is obtained by the following equation (2).

ω = ω + ω _{acc During} deceleration (ω = ω−ω _acc : During acceleration) (2) Further, the acceleration correction value ω _acc is set so that it increases as the deviation between the output of the G sensor 20 and the comparison value increases. Is big. In this way, by performing acceleration / deceleration correction,
The shock during acceleration / deceleration is softened, and the acceleration / deceleration feeling is improved.

Further, when the electric brake (regenerative braking) is used when the vehicle is decelerated, the electric brake has a minimum rotation speed capable of generating a braking force. Below this rotation speed, the braking force suddenly cannot be obtained. At this time, the vehicle feels jerky. In order to eliminate this jerky feeling, the G sensor 20
It is also possible to keep the deceleration constant by using the detection signal g from

After the block 310, the calculated target speed is resonance-corrected by the block 312. The resonance correction will be described in detail below. First, the output of the G sensor is compared with a predetermined comparison value (the comparison value of the block 312 is set sufficiently larger than the comparison value of the block 310). If the output of the G sensor 20 is larger than the above comparison value, Using the resonance correction value ω _vib , it is calculated as in the following equation (3).

ω = ω + ω _vib : Acceleration (ω = ω-ω _vib : Deceleration) Furthermore, instead of the correction of the target speed described above, an actuator 21 that can change the resonance point of the suspension is installed in the vehicle suspension, When the vibration at the resonance point is sensed (when the output of the G sensor 20 is less than or equal to the comparison value), the actuator 21 is driven to change the resonance frequency of the suspension, so that the resonance point of the vehicle is changed. You can go.

Further, the actual vehicle speed (vehicle speed of the rear wheels) when the output of the G sensor becomes equal to or higher than the comparison value is stored (learned), and when approaching this vehicle speed, the target speed ω is corrected as described above,
Alternatively, the resonance frequency of the suspension 21 may be changed.

On the other hand, in block 320, the rotation speed signals ω _c and ω _b are arithmetically averaged. Further, at 322, the value obtained by the block 320 is fetched and updated at every predetermined time to store the actual vehicle speed ω _s0 before the predetermined time and output this value.

Further, in the block 314, the calculation shown in the following equation (4) is performed based on the actual vehicle speed ω _s0 before the predetermined time and the output g of the G sensor 20, and the wheel speed ω _s corresponding to the vehicle absolute speed is calculated.
Ask for.

ω _s = ω _s0 + ∫gdt (4) In block 316, a target speed that does not cause slipping is obtained using the wheel speed ω _s corresponding to the vehicle absolute speed determined in block 320.

First, the slip rate S _r is obtained by performing the calculation shown in the following equation (5).

Here, as shown in FIG. 4, when the slip ratio S _r becomes 0.3 or more, the friction coefficient H and the lateral drag coefficient τ become large, and slip easily occurs. In the block 316, if the slip ratio S _r obtained as described above is 0.3 or more, the target speed ω obtained up to the block 312 is used as it is as the command speed ω * (in FIG. 3, the control of the left wheel is shown. Therefore, ▲ ω ^* _L ▼ is output). On the other hand, if the slip ratio S _r is less than 0.3, the wheel speed ω _s corresponding to the vehicle absolute speed obtained in block 314 is set as the command speed ω *.

Finally, the command speed ▲ ω ^* _L ▼ obtained by the block 316 is corrected by the yaw rate correction value θ _y (value obtained according to the steering angle θ _s ) and output as the command speed ▲ ω ^* _L ▼.

Here, in order to improve the straight running stability of the vehicle
When it is determined by the steering angle signal θ _s of the steering angle sensor 11 of 10 that the vehicle is in a straight traveling state, the phase difference between the rotation intensity signals ω _c and ω _d of the left rear wheel 2c and the right rear wheel 2d is calculated, When a phase difference occurs, the designated speed ω * may be corrected so as to eliminate this phase difference.

In the present embodiment, the control device 6 controls the depression amount of the accelerator pedal and the brake pedal operated by the driver.
_Xa and _Xb , the steering angle θ _s of the steering wheel, etc. are input, and the vehicle speed command is calculated from the depression amount of the accelerator pedal _Xa and the brake pedal _Xb . In addition, the speed command for the left and right motors ▲ ω ^* _L
▼ and ▲ ω ^* _R ▼ are calculated by respectively correcting the vehicle speed command according to the steering angle θ _s of the steering wheel. With respect to the speed commands ▲ ω ^* _L ▼ and ▲ ω ^* _R ▼, the speed control of each motor is performed by feeding back the speed of each motor. Further, the respective currents are controlled based on the current commands ▲ i ^* _a ▼, ▲ i ^* _b ▼ obtained from the speed control circuits 18a, 18b to give voltage commands ▲ V ^* _a ▼, ▲ V ^* _b ▼. . The control pulses P _a and P _b are respectively output from the PWM control circuits 19a and 19b to the inverters so that the voltage commands ▲ V ^* _a ▼ and ▲ V ^* _b ▼ are obtained.
It is output to 4a and 4b. Each of the inverters 4a, the 4b, the control pulse P _a, the P _b, the motor 3a, which generates an output voltage supplied to 3b. This allows each motor 3
a and 3b drive left and right tires 2a and 2b.

If a phase difference occurs between the rotations of the respective motors 3a and 3b, a rotation sensor is attached to the respective motors 3a and 3b, the phase difference between the left and right motors 3a and 3b is detected, and the speed command ▲ ω ^* Correct _L ▼, ▲ ω ^* _R ▼.

Further, in order to improve the straight running stability of the vehicle, when it is determined that the vehicle is in a straight running state from the steering angle θ _s of the steering wheel, the rotation sensors 12a, 2b are respectively attached to the front wheels 2a, 2b and the rear wheels 2c, 2d.
12b, 12c, and 12d are provided, the phase difference is sensed, and when the phase difference occurs, control is performed to eliminate the phase difference.

In addition, a G sensor 20 is attached to the vehicle to improve the feeling of acceleration and deceleration, and speed control commands ▲ ω ^* _L ▼, ▲.
ω ^* _R ▼ is corrected by the output of the G sensor 20.

Further, in order to eliminate the vertical vibration and jerky feeling of the vehicle that occur when the electric brake (regenerative braking) and the mechanical brake are used together when the vehicle is decelerated, the deceleration is controlled to be constant by using the signal from the G sensor 20.

In addition, the inverter frequency is set to be higher than the frequency at the resonance point during acceleration so as to avoid the driving at the resonance point by providing a learning function of sensing the resonance point of the vehicle by the G sensor 20 and storing the resonance point. The control is performed such that the inverter frequency is lowered below the resonance point frequency during deceleration.

As another means for using the resonance point learning function of the G sensor 20, an actuator 21 is provided in the vehicle suspension, and the actuator is detected when the resonance point is detected.
By operating 21 and changing the resonance frequency of the suspension, control is performed to change the resonance point of the vehicle.

Further, by providing the torque sensors 22a and 22b on the respective drive wheels, the torque is sensed and the vehicle speed is controlled by correcting the speed control commands ▲ ω ^* _L ▼ and ▲ ω ^* _R ▼.

FIG. 5 shows the second embodiment and is an explanatory diagram of automatic unmanned garage entry control for improving the garage entry property of the vehicle. In FIG. 5, an optical sensor 24 (shown in FIG. 2) that detects a preset guideline 23 for putting in a garage is attached to the lower part of the vehicle. The control device 5 performs control such that automatic unmanned garage parking can be performed along the guideline 23 with a single button according to a preset automatic running program for garage parking.

In the second embodiment, in order to improve the garage entry performance of a vehicle, a guideline for entering the garage is set in advance, and a sensor capable of sensing the guideline is attached to the vehicle. , Unmanned automatic driving is possible so that the vehicle can be put in the garage even if it is unmanned.

According to the present invention, vibration of the vehicle is suppressed, and driving discomfort is avoided.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram, FIG. 2 is a diagram showing details of a control device, FIG. 3 is a block diagram showing operation of the control device, and FIG.
The figure is an illustration of the second embodiment. 2a …… left front wheel, 2b …… right front wheel, 2c …… left rear wheel, 2d …… right rear wheel, 3a, 3b …… induction motor, 4a, 4b …… inverter, 5 …… battery, 6 …… control Device, 20 ... G sensor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeki Morinaga 4026 Kujimachi, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Hideaki Masaki 2520 Takaba, Katsuta City, Ibaraki Hitachi Ltd. Sawa Factory (72) Inventor Masanori Kami 2520, Takaba, Katsuta, Ibaraki, Takaba Stock Company, Hitachi Ltd.Sawa Factory (72) Nobuo Inoue, 2520, Takaba, Katsuta, Ibaraki Hitachi, Ltd., Sawa Factory (56) References Japanese Unexamined Patent Publication No. 1-74005 (JP, A) Actually opened 48-48302 (JP, U) Actually opened 2-92305 (JP, U) Actually opened 60-192937 (JP, U)

Claims (2)

(57) [Claims] 1. A battery, a motor for driving a wheel, a storage means for storing a traveling state of the vehicle when vibration occurs in the vehicle, and a current supplied from the battery to the motor to control the vehicle. And a control device that adjusts at least one of a current value supplied to the motor and an inverter frequency when the vehicle approaches the running state stored in the storage means. 2. The electric vehicle according to claim 1, wherein the storage means stores the speed of the vehicle when vibration occurs in the vehicle.