JPH05292605A - Control system for electric vehicle - Google Patents

Abstract

PURPOSE:To provide a control system for an electric vehicle employing rubber tire wheels and traveling while driving an induction motor through a VVVF inverter wherein imstability in control due to difference of the number of revolution between right and left wheels is eliminated. CONSTITUTION:Inverters 51, 52 are installed, respectively, for right and left wheels. Induction motors 1, 3 coupled with right wheels are fed with power from the inverter 51 whereas induction motors 2, 4 coupled with left wheels are fed with power from the inverter 52. Number of revolution of the induction motors 1-4 are detected, respectively, through number of revolution detectors 71-74 and then torque command values 81, 82 are delivered from an output torque commander 8 to the inverters 51, 52.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system for an electric vehicle equipped with wheels such as rubber tires and traveling along a guide track.

[0002]

2. Description of the Related Art In order to promote maintenance-free railway vehicles, various methods have been developed and put to practical use, in which an induction motor is used as a main motor, and the induction motor is controlled and driven by an inverter having a variable voltage and a variable frequency. Figure 2 shows, for example, "Science of Electric Vehicles", February 1991, Vol.
l. 44, No. 2, P.I. It is a figure which shows the main circuit basic structure of this kind of conventional electric vehicle disclosed by 48, and arrangement | positioning of a main motor.

In FIG. 1A, 1 to 4 are induction motors which are main motors, and 5 are induction motors 1 to 4 by converting DC power from a DC power supply 6 into three-phase AC power of variable voltage variable frequency. It is an inverter for drive control. Same figure (2)
Is a plan view showing a state in which a main motor is mounted on an electric vehicle,
Four induction motors 1 to 4 are connected to wheels (axles) 11 to 14 via reduction gears 21 to 24, respectively. The induction motors 1 to 4 are supplied with power converted into a voltage and a frequency required for propulsion control by the inverter 5 to obtain a desired rotation output torque. This output torque is applied to the speed reducers 21 to 2
The rotation speed is reduced by 4 to rotate the wheels 11 to 14.

FIG. 3 is a plan view showing a mounting state in an electric vehicle having a configuration different from that shown in FIG. 2 (2). For example, a new transportation system with low pollution, an advanced automatic driving method or an unmanned driving method in the suburbs of the city, etc. It is applied to the adopted system.
As shown in FIG. 1, a wheel 1 made of a low-rigidity material such as a rubber tire
1, 2, etc. are used to run along a guide track 31 installed at the center of a concrete track. In the curved portion of the track, the concave portion 33 formed in the lower portion of the vehicle body 32 is opposed to the convex portion of the guide track 31 and slides on the convex portion of the guide track 31, so that the direction of the vehicle is changed to the guide track 31. Drive along. In this type of vehicle, the left and right wheels 11 and 1 are different from each other in FIG.
2 and the differential adjusters (differential) 41 and 42 are provided between the wheels 13 and 14 to adopt a structure capable of absorbing the difference in rotational speed.

[0005]

As described above, the conventional electric vehicle control system, particularly when the wheel is made of a material having a relatively low rigidity such as a rubber tire as shown in FIG. When traveling on a curved portion, a difference in diameter between left and right wheels is likely to occur. In this case, as shown in FIG. 3, by adopting a differential adjuster, it is possible to compensate the twisting force of the wheel shaft based on the diameter difference between the left and right wheels, but the induction motors 1 to 1 having different rotational speeds are different. The common inverter 5 supplies the power of the same frequency to each of the four.
As a result, there is a problem that an electric motor that obtains an acceleration force and an electric motor that produces a deceleration force are mixed, and control is apt to occur.

However, an electric vehicle using an induction motor is disclosed in, for example, Japanese Patent Application Laid-Open No. 61-88704, in which four induction motors are divided into two and electric power is supplied by two inverters. Has been done. However, this system aims to reduce the alternating current component to the direct current circuit by providing a phase difference between the respective inverters, and it is a common practice to run on a rail as shown in FIG. 2 (2). In an electric vehicle using wheels, the induction motor is not divided into left and right in consideration of the rotational speed difference between the left and right wheels.

The present invention has been made to solve the above problems, and an object thereof is to obtain an electric vehicle control system in which stable control characteristics are obtained as an inverter and wheel generated torque is also stabilized.

[0008]

In the control system for an electric vehicle according to the present invention, the wheels are supported by a structure that allows a difference in the rotational speeds of the wheels on the left and right in the traveling direction, and the inverter and the induction motor are provided on the left and right sides. It is provided for each wheel.

Further, the rotational speeds of the left and right wheels are detected, the bending direction of the vehicle is discriminated from the rotational speed difference, and the absolute values of the torque command values for the outer wheel inverter and the inner wheel inverter are determined. The former is higher than the latter during power running, and the former is lower than the latter during braking.

[0010]

When a vehicle travels on a curved portion, even if there is a considerable difference in diameter between the left and right wheels, the induction motors that drive the left and right wheels are controlled by separate inverters, so that each of them will generate an appropriate value. Torque is obtained.

When the vehicle bending direction is detected from the difference between the left and right rotational speeds and the left and right torque command values are adjusted in a predetermined manner, the radius of curvature of the bending is controlled to be small. Smooth running on curved parts of the vehicle.

[0012]

EXAMPLES Example 1. 1 is a circuit configuration diagram showing a control system for an electric vehicle according to a first embodiment of the present invention. In the figure, 51 and 52 are variable-voltage variable-frequency inverters whose input sides are connected in parallel and are connected to the DC power supply 6, and 1 and 3 are induction motors connected to the wheels 11 and 13 on the right side in the vehicle traveling direction. The two induction motors 1 and 3 are connected in parallel to each other and supplied with electric power from the inverter 51. Similarly, the induction motors 2 and 4 connected to the wheels 12 and 14 on the left side in the vehicle traveling direction are connected in parallel and supplied with electric power from the inverter 52. 71 to 74 are rotation speed detectors that detect the rotation speeds of the induction motors 1 to 4, 8 is an output torque commander, and predetermined torque command values 81 and 82 based on signals from the rotation speed detectors 71 to 74. The inverter 5
1 to 52.

Next, the operation will be described. Now the vehicle is
As shown in FIG. 4 (2), it is assumed that a straight line portion enters a curved portion to the right. In this case, the center of gravity of the vehicle moves from the left-right center to the right, and as a result, the diameters of the right wheels 11 and 13 become smaller, while the diameters of the left wheels 12 and 14 become larger. The inverter 51 determines the required output frequency from the rotation speeds of the induction motors 1 and 3 from the rotation speed detectors 71 and 73 and the torque command value 81 of the output torque command device 8.
Similarly, the inverter 52 determines the required output frequency from the rotation speeds of the induction motors 2 and 4 from the rotation speed detectors 72 and 74 and the torque command value 82 of the output torque commander 8.

Taking the inverter 51 as an example, the output frequency is determined according to the following equation. f _1INV = f _r13 + f _S Here, f _1INV is the output frequency of the inverter 51, f
_r13 is a frequency determined from the induction motor 3 speed f _r3 Metropolitan the rotational speed f _r1 of the induction motor 1 is not almost difference in value between both f _r1 and f _r3, as the f _r13, usually, the power running The lowest value of both is adopted at the time, and the highest value of both is adopted at the time of braking. Further, f _S is the slip frequency required to generate the required torque, and is uniquely determined from the motor characteristics.

The output frequency of the inverter 52 is determined in the same manner as described above, but since the left and right induction motors, which may have a large difference in rotational speed, are provided with two inverters 51 and 52 to be controlled and driven individually. By setting an appropriate torque command, smooth and stable control characteristics can be obtained.

Example 2. By setting the torque command to the inverters 51 and 52 particularly as described below, traveling on a curved portion becomes smoother. That is, first, the bending direction of the running vehicle is determined based on the difference between the rotational speeds of the left and right induction motors 1 and 3 and the induction motors 2 and 4, which are the outputs of the rotation speed detectors 71 and 73 and the rotation speed detectors 72 and 74. Determine. Then, when the vehicle is in the power running state, the torque command value 82 to the wheels located outside the curved portion, for example, the wheels 12 and 14 is changed to the wheel located inside the curved portion, such as the wheel 11. Inverter 5 for driving
It is set to be larger than the torque command value 81 which is the normal value for 1.

As a result, the vehicle tries to bend the curved portion with a smaller radius of curvature, and as a result, friction between the guide track 31 and the recess 33 in the lower part of the vehicle body which slides on the guide track 31 and guides the traveling direction of the vehicle. Is reduced, the vehicle smoothly travels in the curved portion, and the frictional force is reduced. Therefore, wear and damage of the guide track 31 and the vehicle body recess 33 are reduced, and maintenance of the portion is simplified.

In the setting of the torque command value,
When the vehicle is in the braking state, naturally, the torque command value to the inverter that drives the wheels located outside the curved portion is set to be smaller (its absolute value is smaller).

Example 3. In the above embodiment, the case where only one vehicle is used has been described, but a system may be used in which electric power is supplied to the induction motor from two or more vehicles provided separately for the left and right vehicles.

[0020]

As described above, according to the present invention, the inverter and the induction motor are provided for each of the left and right wheels, so that the instability of the inverter control due to the deviation of the rotational speeds of the left and right wheels can be eliminated. it can.

Further, when the curving direction of the vehicle is detected from the deviation of the left and right rotational speeds and a predetermined deviation is provided for the left and right torque command values, the vehicle smoothly runs especially in the curved portion, and the guidance is provided. The burden on structural parts such as tracks is also reduced.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing a control system for an electric vehicle according to an embodiment of the present invention.

FIG. 2 is a diagram showing a circuit configuration showing a conventional electric vehicle control system and a mounting state in a vehicle.

FIG. 3 is a diagram showing a state in which a conventional electric vehicle provided with a differential adjuster is mounted on a vehicle.

FIG. 4 is a diagram for explaining a guide mechanism of a vehicle traveling on a curved portion.

[Explanation of symbols]

 1 etc. Induction motor 51 etc. Inverter 6 DC power supply 8 Output torque commander 11 etc. Wheels 31 Guide track 41 etc. Differential adjuster 71 etc. Rotation speed detector 81 etc. Torque command value

Claims (2)

[Claims] 1. An electric vehicle equipped with a variable voltage variable frequency inverter, an induction motor driven by the inverter, and wheels made of a low-rigidity material such as rubber tires connected to the induction motor, the electric vehicle traveling along a guide track. Control system of the electric vehicle, wherein the wheels are supported in a configuration that allows a difference in rotational speed between the left and right wheels in the traveling direction, and the inverter and the induction motor are provided for each of the left and right wheels. method. 2. The rotational speeds of the left and right wheels are detected, the bending direction of the vehicle is discriminated from the rotational speed difference, and the absolute value of the torque command value to the outer wheel inverter and the inner wheel inverter is obtained. The former is higher than the latter during powering,
The control system for an electric vehicle according to claim 1, wherein the former is set to be lower than the latter during braking.