JPH03253202A - Driving force controller of electric vehicle - Google Patents

Abstract

PURPOSE:To eliminate a trouble of operating both an accelerator and brakes when a vehicle runs on a jammed road with a very low speed by a method wherein, if a running speed is declined close to zero, a required magnitude of a current is supplied to a motor from a battery to generate a minute driving force and driving wheels are driven a little. CONSTITUTION:A motor 16 is made to rotate by a current supplied from a battery 12 and driving wheels are driven by the motor 16 and the running speed of a vehicle is detected by a running speed detecting means 18. A signal from the running speed detecting means 18 is inputted to a control means 20 and, if the running speed is declined close to zero, the control means 20 controls an inverter 14 and a required magnitude of a current is supplied to the motor 16 and a minute driving force is generated by the motor 16 to drive the driving wheels a little. With this constitution, a speed can be controlled only by the operation of brakes when the vehicle advances on a jammed road with a very low speed.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a driving force control device for an electric vehicle using a motor as a driving means, particularly an electric vehicle that generates a minute driving force when the traveling speed decreases to around zero. This invention relates to an automobile driving force control device.

[Background Art] Recently, electric vehicles have been studied as pollution-free vehicles that do not produce harmful exhaust gases, and some of them have already been put into practical use.

Early electric vehicles used DC motors, which were easy to control, as the drive source, but DC motors had brushes and other parts that were difficult to maintain, so recently induction motors, which were easy to maintain, were used. It has become.

Motors used in electric vehicles are torque-controlled, unlike normal industrial motors, and induction motors are controlled by vector control or slip frequency control in order to perform the necessary torque control and stabilize the vehicle's maneuverability. .

When the accelerator pedal and the brake pedal are in operation, as shown in Fig. 8, when the brake pedal is OFF and the accelerator pedal is ON, the travel control (100
) is performed, and when the brake pedal is OFF and the accelerator pedal is OFF, or when the brake pedal is OFF (10
1°102) is the predetermined rotational speed (No.
) or more, the regenerative torque equivalent to engine braking (-To
), a regenerative torque command is issued linearly below a predetermined rotational speed (No), and when the motor rotational speed is zero, the motor torque is zero.

[Problem to be solved by the invention] Conventional electric vehicle driving force control devices are configured as described above, and because they do not have leap torque like automatic vehicles, they are different from internal combustion engine manual vehicles when starting on a slope. Similarly, if you don't pull the handbrake and then turn the accelerator ON, the vehicle will slide backwards, making it difficult for beginners to operate, and also the hassle of having to operate the accelerator and brake when driving at slow speeds in traffic jams. The problem is that it is complicated, and about 90% of owner-drivers purchase internal combustion engine automatic cars that are easy to start on hills and only require brake operation when driving at slow speeds in traffic jams. there were.

The present invention has been made in view of the above-mentioned conventional problems, and it is an object of the present invention to provide a driving force control device for an electric vehicle that generates creep torque when the traveling speed decreases to around zero.

[Means for Solving the Problems] A driving force control device for an electric vehicle according to the present invention includes a battery that charges and discharges electric power, an inverter that converts direct current supplied from the battery into alternating current, and an inverter that converts direct current supplied from the battery into alternating current. The vehicle is equipped with a motor that drives the drive wheels using an alternating current generated by the vehicle, a traveling speed detecting means for detecting the traveling speed of the vehicle, and a control means for inputting a signal from the traveling speed detecting means. Therefore, based on the signal from the travel speed detection means, the control means detects when the travel speed decreases to near zero.
The present invention is characterized in that the electric current supplied to the motor is controlled by an inverter so that a predetermined amount of electric current is supplied from the battery to the motor, and the minute driving force generated by the motor slightly drives the drive wheels.

[Function] The driving force control device for an electric vehicle according to the present invention rotates a motor using a current supplied from a battery, drives drive wheels by the motor, detects the traveling speed of the vehicle by a traveling speed detection means, and detects the traveling speed. The control means that inputs the signal from the detection means controls the inverter to supply a predetermined amount of current from the battery to the motor when the traveling speed drops to around zero, and the motor generates a minute driving force to drive the drive wheels. Drive slightly.

[Embodiments] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

The electric vehicle has a driving force control device 10, and the driving force control device 10, as shown in FIG. 1, is equipped with a battery 12 that charges and discharges electric power. An inverter 14 that converts the supplied DC current into AC is also connected.

A motor 16 that drives the drive wheels using the converted alternating current is connected to the inverter 14, and the inverter 14 is connected to a controller 20 as a control means, and the controller 20 includes a vehicle speed sensor 18,
An accelerator sensor 22 that detects the opening degree of the accelerator and a brake switch 24 that is turned on and off by operating the brake pedal are connected.

Next, the operation of this embodiment will be explained with reference to the flowchart of FIG.

When the vehicle is running or stopped, the controller 20 determines whether the brake switch 24 is turned on (5tepl), and if it is determined that the brake switch 24 is not turned on, it determines whether the accelerator sensor 22 is turned on. (Step 2).

Then, when it is confirmed that the accelerator sensor 22 is in the ON state, the controller 20 sets flagB to zero and sets it to 5.
step 3), the inverter 4 is controlled to drive the motor 6 within the range of the maximum constant rotation speed and maximum torque according to the driving conditions such as the accelerator opening and the load (Step 3).
p4).

Moreover, in the above-mentioned Step 2, the accelerator sensor 2
2 is not in the ON state, the controller 20
As shown in Fig. 3, when the number of revolutions is above a certain number of revolutions (No), it issues a command for regenerative torque (-t) equivalent to engine braking, and when the number of revolutions is less than a certain number of revolutions, it issues a regenerative torque command as shown by the chain line. When the motor rotation speed is zero, the motor torque is the creep torque T1 (Step 5).

This allows electric vehicles to control their speed by simply operating the brakes when moving forward on congested roads, eliminating the need to operate both the accelerator and brakes.

Furthermore, at the aforementioned 5 tepl, the brake switch 24
If it is determined that fl is turned on, the controller 20
agB is read (Step 6), and if flagB is not 1, a command is issued for regenerative torque (T ) equivalent to engine braking at a predetermined rotation speed (No) or higher, and
No) and below, a regenerative torque command is issued linearly, and when the motor rotation speed is zero, the motor torque is zero (Step 7
).

Then, the controller 20 determines whether the vehicle speed is zero based on the signal from the vehicle speed sensor 18 (Step 8).
, If it is determined that the vehicle speed is not zero, return to 5 step 1,
If it is determined that the vehicle speed is zero, flagB is set to 1 (5tep9) and the process returns to 5tepl.

In addition, in the above-mentioned 5tep6, if it is determined that flagB is 1, that is, if the vehicle is stopped, the controller 2
0, as shown in Figure 3, even when the motor rotation speed is zero, creep torque Tt does not occur as shown by the chain line.
plO), the creep torque TI and gravity maintain a balance so that the car does not back up due to gravity even when stopped on a slope. In this case, creep torque is produced even if the brake pedal is depressed until the accelerator pedal is depressed.

Next, the fourth example shows the case where the creep torque can be changed arbitrarily.
This will be explained with reference to FIG. 6.

As shown in FIG. 5, the driving force control device 10 has a volume (26) that allows the driver to arbitrarily select the amount of creep torque, and the volume (26) is controlled via an A/D converter (28). and is connected to the controller (20).

The driver adjusts the amount of creep torque to his/her preference using the volume (26).

As a result, the voltage output to the A/D converter (28) changes depending on the position of the volume (26), and the voltage value converted into a digital quantity by the A/D converter (28) is input to the controller (20). Controller (20)
changes the amount of creep torque according to the input voltage value in accordance with the position of the volume (26) as shown in FIGS. 4A, B, and C.

By doing the above, it is possible to obtain creep torque according to the driver's preference.

Also, instead of the volume (26), the tilt angle of the vehicle (
The inclinometer (30) that detects θ) is connected to the A/D converter (2
8) to the controller (20) (see FIG. 6), the amount of creep torque may be changed depending on the inclination angle (θ).

The selection of the amount of creep torque in this case will be explained with reference to the flowchart of FIG.

The controller (20) stores in advance the rotation speed-torque relational expressions (A, B, C) in the storage unit.

The inclinometer (30) detects the inclination angle (θ) of the vehicle, and its output is converted into a digital quantity by the A/D converter (28) and input to the controller (20) (Ste
p 11).

Then, the controller (20) determines whether the input tilt angle (θ) of the vehicle is smaller than the predetermined angle (θ1) (5tep12), and determines whether the input tilt angle (θ) is smaller than the predetermined angle (θ) (θ< θl), the relational expression A (fourth
(see figure) (Step 13).

Furthermore, if it is determined that the tilt angle (θ) of the vehicle is not smaller than the predetermined angle (θ1), the controller (20) determines whether the tilt angle (θ) is within the predetermined angle range.
), the inclination angle (θ) is within the specified angle range (θ1≦θ≦02)
If it is determined that this is the case, then relational expression B (see FIG. 4) is selected (Step 15).

Further, if it is determined that the inclination angle (θ) is not within the predetermined angle range, the controller (20) selects relational expression C (see FIG. 4) (Step 16).

By doing so, it is possible to obtain a creep torque depending on the driving situation.

In addition, in the embodiment of FIG. 5, if the position of the volume (26) is set to θ, it is possible to apply the operation of the flowchart of FIG. 7 to the embodiment of FIG.

[Effects of the Invention] As explained above, according to the present invention, when the traveling speed decreases to around zero, a predetermined amount of current is supplied from the battery to the motor to generate a minute driving force to slightly move the drive wheels. Since it is configured to drive, it generates creep torque when starting on a slope, preventing the vehicle from sliding backwards unless the accelerator is turned ON while pulling the sight brake, and when driving at a slow speed in traffic jams, it is possible to generate creep torque. This eliminates the hassle of operating both the automatic transmission and the brakes, meeting the needs of owners and drivers who are accustomed to automatic transmissions.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a driving force control device according to an embodiment of the invention, FIG. 2 is a flowchart showing the operation of an embodiment of the invention, and FIG. 3 is an embodiment of the invention. FIG. 4 is a diagram showing the rotation speed-torque relationship of another embodiment of the present invention. FIGS. 5 and 6 are diagrams showing the rotation speed-torque relationship of another embodiment of the present invention. FIG. 7 is a block diagram showing the configuration of the driving force control device according to the embodiment; FIG. 7 is a flowchart showing the operation of another embodiment of the present invention; FIG. 8 is a flowchart showing the operation of the conventional example; FIG. 1 is a diagram showing the relationship between rotation speed and torque in a conventional example. 10... Driving force control device 12... Battery 14... Inverter 16... Motor 18... Traveling speed detection means 20... Control means a

Claims (1)

[Claims] An electric vehicle that includes a battery that charges and discharges power, an inverter that converts direct current supplied from the battery into alternating current, and a motor that drives drive wheels using the alternating current converted by the inverter. The driving force control device includes a traveling speed detecting means for detecting the traveling speed of the vehicle, and a control means for inputting a signal from the traveling speed detecting means, and the control means is configured to detect the traveling speed based on the signal from the traveling speed detecting means. When the running speed drops to around zero, the inverter controls the current supplied to the motor so that a predetermined amount of current is supplied from the battery to the motor, and the minute drive force generated by the motor slightly drives the drive wheels. A driving force control device for an electric vehicle characterized by: