JPH03261306A - Regenerative brake controller for electric car - Google Patents

Abstract

PURPOSE:To suppress vibration or noise due to collision of gears by increasing regenerative brake torque when the rotational fluctuation detected from the output shaft of decelerator in an electric car exceeds a predetermined reference value. CONSTITUTION:DC output from a battery 32 is inverted through an inverter main circuit 30 into AC power for driving a motor 10. Rotation of the motor 10 is decelerated 12 and transmitted through a hook joint 16 and a propeller shaft 14 to a differential 18 in order to rotate a wheel 20. A rotational speed detecting section 38 mounted on the decelerator 12 detects the rotation speed (n) at the time of OFF acceleration and during brake operation. Variation of the rotational speed (n) with time dn/dt is inputted to the rotational variation detecting means 40 in a controller 34 in order to detect rotational variation which is then subjected to comparison 42. When thus detected rotational variation exceeds a reference value, a brake torque control means 44 increases a regenerative brake torque.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a regenerative braking control device for an electric vehicle that performs braking using regenerative braking of a motor, and particularly relates to a gear shift of a reducer that occurs during coasting. This invention relates to a regenerative braking control device for electric vehicles that can prevent vibration and noise caused by hitting.

[Prior Art] Conventionally, in an electric vehicle, when an accelerator pedal is released, a braking force equivalent to engine braking in an engine vehicle is generated by regenerative braking of a driving motor, and a battery is charged with the generated energy. and,
This energy recovery is intended to increase the distance traveled per battery charge. Incidentally, an electric vehicle using such regenerative braking is disclosed in, for example, Japanese Patent Application Laid-open No. 59-2090.
This is shown in Publication No. 04 and the like.

FIG. 5 is a schematic diagram showing the drive mechanism of the conventional electric vehicle as described above.

In the figure, 10 is an induction motor for driving an electric vehicle (hereinafter referred to as a motor), 12 is a reducer, and the reducer 12 reduces the rotation of the motor 10. 14 is a propeller shaft, through Fuchs joints 16 provided at both ends,
One end is connected to the reducer 12, and the other end is connected to the differential 18.
It is connected to the. Reference numeral 20 denotes a wheel serving as a driving wheel, which is connected to the differential 18.

FIG. 6 is a structural diagram of the Fuchs joint 16.

The Fuchs joint 16 is an inconstant velocity type joint, and when the two axes, the driving shaft 22 and the driven shaft 24, intersect with each other at an angle θ, the relationship of angular velocities is as follows.

eO8θ However, ω: Drive shaft angular velocity, ω2: Driven shaft angular velocity,
θ: intersection angle of the two axes, φ: rotation angle of the drive shaft (note that 0 is the time when the yoke is perpendicular to the plane containing the two axes).

Therefore, even if the drive shaft angular velocity ω□ is constant, the driven shaft angular velocity ω2 varies depending on the intersection angle θ of the two axes and the rotation angle φ of the drive shaft.

[Problem 8 to be solved by the invention] That is, in the conventional electric vehicle drive mechanism as described above, for example, as shown in FIG. 7, the intersection angle θ of the two axes of the Fuchs joint 16 changes. As a result, the rotation speed of the driven shaft 24 fluctuates.

Therefore, during coasting, the driving gear and driven gear in the reducer 12 collide with each other due to the rotational fluctuations, causing vibration and noise.

The vibrations and noise of this gear are transmitted from the reducer 12 to the vehicle, and become the noise and vibration of the vehicle itself.

This invention was made to solve the problems of the prior art as described above, and its purpose is to provide regenerative braking for electric vehicles that can prevent vibration and noise caused by gear shifting of the reducer that occurs during coasting. The purpose of this invention is to provide a control device.

[Means for Solving the Problems] A regenerative braking control device for an electric vehicle according to the present invention includes an induction motor for driving an electric vehicle, and a reducer that decelerates the rotation of this motor and outputs it to the drive wheels. In an electric vehicle that performs braking using regenerative braking, the rotational variation detection means detects the rotational variation at the output shaft of the reduction gear, the arithmetic comparison means compares the rotational variation with a predetermined reference value, and the rotational The present invention is characterized in that it includes a braking torque control means for increasing the regenerative braking torque when the fluctuation becomes larger than a reference value.

In the regenerative braking control device for an electric vehicle having the above-mentioned configuration, the rotational fluctuation detection means detects the rotational fluctuation at the output shaft of the reducer, and the calculation comparison means compares this rotational fluctuation with a predetermined reference value. The regenerative braking torque is increased by the braking torque control means when the rotational fluctuation becomes larger than a reference value.

[Embodiments] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 is a schematic configuration diagram showing a regenerative braking control device for an electric vehicle according to an embodiment of the present invention, and the same or corresponding parts as in FIG. 5 are given the same reference numerals, and a description thereof will be omitted.

In FIG. 1, a motor 10 is connected to an inverter main circuit 30 that converts DC power from a battery 32 into AC power, and is rotationally driven by AC power supplied from the inverter main circuit 30. The rotation of the motor 10 is
The speed is reduced by the reducer 12, and the Fuchs joint 16
The signal is transmitted to the differential 18 via the propeller shaft 14 using the propeller shaft 14, which rotates the wheel 20.

A controller 34 executes processing such as travel control and regenerative braking I11 control. When the vehicle is running, the controller 34 causes the inverter main circuit 30 to generate an AC voltage and frequency corresponding to the speed and driving force of the vehicle, and controls the rotation speed and output of the motor 10. Additionally, when the accelerator is off, regenerative braking equivalent to engine braking is performed.

A rotation speed sensor 36 detects the rotation speed N of the motor 10. Reference numeral 38 denotes a rotational speed detection unit that detects the rotational speed of the output shaft of the reducer 12 when the accelerator is turned off or during braking.

FIG. 2 shows an embodiment of the rotation speed detecting section 38. The illustrated rotation speed detection unit 38 includes a gear 52 mounted on the output shaft 50 of the reducer 12 and a pulse detector 54 that detects a pulse signal according to the tooth arrangement shape of the gear 52.
It is composed of.

The rotation speed detection unit 38 of this embodiment detects the rotation speed n of the speed reducer output shaft 50 based on the pulse signal detected by the pulse detector 54. Note that in order to accurately calculate the rotational fluctuation dn/dt by the rotational fluctuation detecting means 40, which will be described later, it is desirable that the number of teeth of the gear 52 be 60 or more.

The rotational speed n thus detected is input to the rotational fluctuation detection means 40 of the controller 34 shown in FIG. The rotational speed fluctuation detection means 40, which is the first characteristic component of the present invention, calculates the rotational speed fluctuation dn/dt by differentiating the rotational speed n with respect to time. In addition, the calculation comparison means 4 described later
2, when comparing it with a predetermined (fixed) rotational fluctuation reference value, the rotational speed fluctuation detecting means 40 may output this rotational fluctuation dn/dt as it is, but in this embodiment, the reference value is used as the reference value at that time. In order to correlate this with the value of the braking torque, the rotational fluctuation detection means 40 multiplies this rotational fluctuation dn/dt by the moment of inertia J of the rotating system, converts it into a rotational fluctuation torque t, and outputs the result. (Instead of calculating the rotational fluctuation torque t with the rotational speed fluctuation detection means 40, a torque meter is added to the drive system to directly detect the torque, and then
You may also ask for ) Rotation fluctuation torque t calculated by the rotation speed fluctuation detection means 40
is input to the arithmetic comparison means 42. The calculation comparison means 42, which is the second characteristic component of the present invention, calculates the ratio (t/T
) is determined, and this torque ratio (t/T) is compared with a predetermined reference ratio α.

The comparison result of the arithmetic comparison means 42 is transmitted to the braking torque control means 44.
is input. The braking torque control means 44, which is the third characteristic component of the present invention, controls the torque ratio (t/T) as described above.
is larger than the reference value α, the regenerative braking torque T is increased by ΔT.

Here, the reason why we decided to judge the increase in regenerative braking torque based on the reference ratio α is that under the situation where regenerative braking is applied sufficiently, the regenerative braking torque T
This is because it is possible to prevent the driving and driven gears from separating, so there is no need to increase the regenerative braking torque T (see Figure 4).
. The maximum value of the regenerative braking torque T is defined, for example, by differentiating the motor rotational speed N at the start of braking detected by the rotation sensor 36.

The braking torque control processing procedure of this embodiment having the above configuration will be explained according to the flowchart of FIG. 3.

First, the controller 34 sets an initial value based on each detected value input from the rotation speed sensor 36, the rotation speed detection section 38, etc. (step 101). Next, the controller 34 determines the timing to perform regenerative braking based on the ON/OFF state of the accelerator (step 102), and if the accelerator is OFF, the rotational fluctuation detection means 40 detects the rotational fluctuation torque t (step 103).

As shown in FIG. 4, this rotational fluctuation torque t appears as a rotational fluctuation torque t1 with a small amplitude when the above-mentioned intersection angle θ of the two axes is small. Furthermore, when the intersection angle θ of the two axes is large, the rotational fluctuation torque t2 appears to have a large amplitude. In the conventional technology, when the ratio of the rotational fluctuation torque t to the regenerative braking torque T of the engine brake increases, the vibration of the gears of the reducer 12,
It was causing noise.

Therefore, in the present invention, it is determined by the arithmetic comparison means 42 whether the torque ratio t/T is larger than the reference ratio α (step 104), and if YES, the braking torque control means 44 sets the regenerative braking torque to Te- It is defined by T+ΔT (step 105), and if No, it is defined by Te-T (step 106).

Next, the controller 34 outputs a vector calculation command to the inverter main circuit 30 for generating the regenerative braking torque Te (step 107), and returns to step 102.

On the other hand, if the determination in step 102 is YES, the controller 34 calculates the necessary driving force according to the amount of depression of the accelerator (step 108), and proceeds to step 107.

By switching the regenerative braking torque in this manner, it is possible to reduce vehicle vibration and noise caused by rotational fluctuations of the propeller shaft 14, thereby improving the ride comfort of the vehicle.

In addition, in the above embodiment, whether or not the reference value of the rotational fluctuation was set in relation to the value of the regenerative braking torque at that time, the reference value was set to a certain fixed value and the detected value of the rotational fluctuation was set to this value. The regenerative braking torque may be controlled to be increased when the torque is exceeded. In addition, since rotational fluctuations occur when the Fuchs joint intersection angle θ of the propeller shaft becomes large, such conditions are mechanically detected from the suspension stroke, etc., and the intersection angle θ is
The regenerative braking force may be controlled to be increased when the regenerative braking force becomes large.

[Effects of the Invention] As explained above, according to the regenerative braking control device for an electric vehicle according to the present invention, by increasing the regenerative braking torque, the influence of the rotational fluctuation torque that causes gear shift of the reduction gear is reduced. The force can be absorbed and reduced, and the vibration and noise caused by the above-mentioned gear shifting can be reduced.

[Brief Description of the Drawings] Fig. 1 is a schematic diagram showing a regenerative braking control device for an electric vehicle according to an embodiment of the present invention, and Fig. 2 is a schematic diagram showing an embodiment of a rotation speed fluctuation detection section. , Fig. 3 is a flowchart showing the braking torque control processing procedure of this embodiment, and Fig. 4 shows the relationship between regenerative braking torque and rotational fluctuation torque when the vehicle is decelerating by receiving regenerative braking force equivalent to engine braking. Characteristic diagram shown as the vehicle speed decreases, Figure 5 is a schematic configuration diagram showing the drive mechanism of a conventional electric vehicle, Figure 6 is a structural diagram of the Fuchs joint, and Figure 7 is the intersection angle of the two axes of the Fuchs joint. FIG. 4 is a characteristic diagram showing the variation in the rotational speed of the driven shaft due to changes in θ and the rotation angle φ of the drive shaft. 0...Motor 2...Reducer O...Rotation fluctuation detection means 2...Calculation comparison means 4...Control torque control means

Claims (1)

[Scope of Claims] An electric vehicle that includes an induction motor for driving the electric vehicle and a reducer that decelerates the rotation of this motor and outputs it to the drive wheels, and performs braking using regenerative braking of the motor, a rotational fluctuation detection means for detecting rotational fluctuation in the output shaft of the machine; an arithmetic comparison means for comparing the rotational fluctuation with a predetermined reference value; and an increase in regenerative braking torque when the rotational fluctuation becomes larger than the reference value. A regenerative braking control device for an electric vehicle, comprising: braking torque control means.