JPH03107305A - Motor controller for electric automobile during deceleration - Google Patents

Abstract

PURPOSE:To protect a decelerator against breakdown due to impact torque by estimating the impact torque to be produced in th decelerator through brake operation of vehicle and performing regenerative brake operation so that the impact torque is suppressed. CONSTITUTION:An impact torque operating means (e) estimates the torque to be produced in a decelerator when the wheel (c) is braked by means of a wheel brake (b) such as a hydraulic brake. A regenerative brake torque operating means (f) operates regenerative brake torque, required for bringing the torque produced in the decelerator (d) below a predetermined level, based on the torque operated by the impact torque operating means (e). A regenerative brake means (h) applies regenerative brake onto a motor (g) based on th regenerative brake torque.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electric vehicle deceleration motor control device that controls regenerative braking of a motor during deceleration of an electric vehicle.

[Prior Art] Electric vehicles driven by motors have been known in the past. For example, the driving force generated by a motor is reduced by a speed reducer made up of a predetermined number of gears, and is further supplied to the wheels via a shaft, thereby driving the wheels and thus the electric vehicle.

Furthermore, as braking means for such electric vehicles, wheel brakes that brake wheels using hydraulic pressure or the like, and regenerative braking devices that regeneratively brake the motor are known.

In an electric vehicle equipped with such wheel brakes and a regenerative braking device, when braking the electric vehicle, the wheels are braked by the wheel brakes, and the motor is regeneratively braked by the regenerative braking device.

Furthermore, conventionally, resin gears made of resin have been used as the gears of the reduction gear in order to reduce gear noise.

[Problem to be Solved by the Invention] In such an electric vehicle equipped with both wheel brakes and a regenerative braking device, when the wheels are braked by the wheel brakes, the gears that constitute the reducer may be damaged. The problem was that it was possible.

For example, when an electric vehicle is running on a road with a low coefficient of friction, such as an icy road surface, if sudden braking is applied using the wheel brakes, the motor will be decelerated beyond the natural deceleration due to its own frictional resistance. Since the speed is imparted by the wheel brakes (ie, the wheel brakes provide positive power to the rotation of the motor), excessive torque is generated in the reducer interposed between the wheels and the motor. At this time, if the torque generated in the reducer exceeds the strength of the gears constituting the reducer, the gears will be damaged and the electric vehicle will be unable to run. In particular, when a resin gear is used as a gear, the bending strength of the resin gear is only about 0.2 times that of a steel gear. high compared to

The present invention was made with the aim of solving these problems, and it is an object of the present invention to prevent excessive torque from being generated in the reducer during braking, thereby preventing the gears included in the reducer from being damaged. An object of the present invention is to provide a motor control device for controlling a motor during deceleration of an electric vehicle so as to prevent the motor from decelerating.

[Means for Solving the Problems] In order to achieve the above object, a deceleration motor control device a for an electric vehicle according to the present invention has a configuration as shown in FIG.

That is, the present invention provides a wheel brake b such as a hydraulic brake.
When the wheel C is braked, an impact torque calculation means e estimates and calculates the torque generated in the reducer d, which is connected to the wheel C and includes a predetermined number of gears; A regenerative braking torque calculating means f that calculates the regenerative braking torque necessary to suppress the torque actually generated in the reducer d to a predetermined value or less based on the torque, and a motor g that drives the wheels C via the reducer d. , a regenerative braking means that performs regenerative braking based on the regenerative braking torque calculated by the regenerative braking torque calculating means f.

[Operation] In the present invention, the torque generated in the reduction gear d due to braking of the wheel C by the wheel brake b is estimated and calculated by the impact torque calculation means e.

Next, a regenerative braking torque calculation means f calculates a regenerative braking torque based on the torque calculated by the impact torque calculation means e. This regenerative braking torque is a torque of a value necessary to suppress the torque generated in the reducer d to a predetermined value or less as described above, and the regenerative braking means regenerates the motor g based on this regenerative braking torque. Brake. Therefore, the torque of the speed reducer d generated due to the braking of the wheels C by the wheel brake b is suppressed by the regenerative braking of the motor g, and damage to gears and the like included in the speed reducer d is prevented.

[Example] Embodiments of the present invention will be described below based on the drawings.

FIG. 2 shows the configuration of a deceleration motor control device for an electric vehicle according to an embodiment of the present invention.

In this figure, a reducer 12 is connected to the motor 10, and the reducer 12 further includes a propeller shaft 14,
Wheels 20 with built-in wheel brakes are connected via a differential 16 and an axle shaft 18.

That is, when the electric vehicle is running, the driving force generated by the motor 10 is reduced in speed by the reduction gear 12 and supplied to the wheels 20 via the propeller shaft 14, differential 16, and axle shaft 18. The electric vehicle travels by driving the wheels 20.

On the other hand, when braking the electric vehicle, the brake pedal force of the driver is transmitted to the wheel brakes built into the wheels 20 by, for example, hydraulic pressure, and the wheels 20 are braked.

Further, the speed reducer 12 includes a predetermined number (four in the figure) of gears 22, and a gear 22-4 provided on the rotor shaft of the motor 10 and a gear 22 provided on the other shaft.
2-3 mesh with each other, and a gear 22-2 provided on the same axis as this gear 22-3 meshes with a gear 22-1 provided on the same axis as the propeller shaft 14.

That is, the speed reduction of the driving force supplied from the motor 10 by the speed reducer 12 is performed according to the gear ratio of the gears 22 determined based on the design.

An inverter main circuit 24, which is an inverter circuit that supplies driving power to the motor 10, is connected to the motor 10, and the inverter main circuit 24 is connected to the wheels 2.
A controller 28 is connected to which a rotation speed sensor 26 that detects a rotation speed of 0 is connected.

That is, when the accelerator signal is supplied to the controller 28, the controller 28 instructs the inverter main circuit 24 to provide the necessary driving force, and the inverter main circuit 24
drives the motor 10 with the commanded required driving force. Further, when a brake signal is supplied to the controller 28, a control operation according to a feature of the present invention is performed, and regenerative braking of the motor 10 is performed.

Next, the operation of this embodiment having such a configuration will be explained using FIGS. 3 to 5.

FIG. 3 shows the flow of control operations of the controller 28 in this embodiment.

First, immediately after the start of operation 100, initial value setting 102 of data such as gear ratio in the reduction gear 12 is performed, and it is further determined whether a brake signal is being supplied to the controller 28 (104).

That is, when the driver steps on the brake, a brake signal is supplied to the controller 28, but determination 1 is not made.
At step 04, it is determined whether a brake signal is being supplied to the controller 28, that is, whether the brake is being depressed.

In the determination 104, if it is determined that the brake is being depressed, the process moves to the next step 106, and in other cases, whether an accelerator signal is being supplied to the controller 28, that is, if the accelerator is being depressed by the driver. A determination 108 is made as to whether or not the is stepped on.

In the latter case, if it is determined that the accelerator is not depressed, the process returns to determination 104, and if it is determined that the accelerator is depressed, the motor 10 is activated in response to the accelerator signal.
The required driving force is calculated (110), and a vector calculation command is issued to the inverter main circuit 24 in accordance with this required driving force (112).

In the above-mentioned determination 104, when it is determined that the brake is depressed and the process moves to step 106, the step 106
In , the wheel angular deceleration is calculated.

This calculation is performed, for example, as follows.

When the braking force generated by the wheel brake built into the wheel 20 is multiplied by the effective radius of the wheel 20, the torque generated by the wheel brake is obtained. On the other hand, wheel 2
0, the moment of inertia of the gear 22 constituting the reducer 12, the moment of inertia of the rotor of the motor 10, the gear ratio between the gears 22, and the differential 16.
is converted into the value on the axle shaft 18 using the gear ratio. Then, by dividing the torque value of the wheel brake calculated as described above by the sum of the moments of inertia converted to the value on the axle shaft 18, the angular deceleration determined for the wheel 20, that is, the wheel angular deceleration is calculated.

Next, based on this wheel angular deceleration, the impact torque TB generated on the gear 22 is calculated (114).

For example, one of the four gears 22, for example gear 2
If only gear 2-3 is a resin gear made of resin and the others are steel gears, the strength of gear 22-3 is the weakest, so the impact torque T for gear 22-3 is
B is calculated.

This calculation is performed, for example, as follows.

The wheel angular deceleration calculated in step 106, the gear ratio of the differential 16, the gears 22-1 and 22-
Multiplying the gear ratio between 2 and 2, the gear 2 formed from resin
The angular deceleration at 2-3 is determined.

Moment of inertia of the rotor of the motor 10 and the gear 22-3
Converting the moment of inertia of to a value on the axis of gear 22-3 based on the gear ratio, and multiplying the moment of inertia obtained by this change by the angular deceleration of gear 22-3, The resulting torque is determined. This torque corresponds to the torque generated in the gear 22-3 when the wheel 20 is braked by the wheel brake, that is, the impact torque TB.

Next, this impact torque TB is set to a reference torque T which is set to a value smaller than the allowable maximum torque of the gear 22-3.
(116).

BM ^ Damage may occur.

When it is determined in the judgment 116 that the impact torque TB is less than or equal to the permissible reference torque T, the necessary braking force MAX is calculated (118), and vector calculation is instructed to the inverter main circuit 24 (112).

That is, in this case, regenerative braking of the motor 10 is performed as in the conventional case.

When it is determined in the judgment 116 that the impact torque To exceeds the reference maximum torque T, MAX calculates the required braking force 122 based on this impact torque TB.
will be held.

This required braking force calculation 120 is performed based on a model as shown in FIG. 4, for example.

That is, in FIG. 4, the wheels 20, the differential 16, the gears 22-1.22-2°22-3.22
-4 and the rotor of motor 10 have moments of inertia 1,1 1 11 2° 3'4'II and I7, respectively, and gears 22-15'
The gear ratio of gears 22-3 and 22-4 is R2, and the gear ratio of wheels 20.B and 22-2 is Rt. Differential 1
6. The gears 22-1.22-2.22-3.22-4 and the rotor of the motor 10 are coupled by a spring constant of 1 and a damping coefficient C, (i""1.2.3.4), respectively. has been done.

Here, wheels 20, differential 16, gear 22
-1, gear 22-2, and gear 22-4 are respectively θ and (i-1, 2, 3, 4, 5), the model shown in this figure is expressed by the following equation. be done.

l2(d/dt) 2 to θ2+ (θ2-03)+, θ2 + Ct dθ2/dt-C2(dθ3/dt
-dθ2/dt)-0 ... (1) ... (2) R2(1+I R2) (d/dt)21
5 6 2 /dt-dθ3/dt)-C4R12R22(dθ5/
dt-dθ4/dt)-0 (3) 2 2 2
2RR(θ4-θ5) C4R1R2 2 (dθ /dt-dθ4/at)-0 (4) Among these equations, the term KR(θ3-θ4 ) 1 is a term caused by the difference between the angular displacements θ3 and θ4 of the gears 22-3 and 22-4, and is a term representing the impact torque TB mentioned above. Therefore, in step 120,
The impact torque TB represented by this term is converted to a value T* on the rotor axis of motor 0, and this torque T*
Required B based on
B regenerative braking torque T--T'' is calculated. Then, based on the regenerative braking torque T calculated in this way, a vector calculation command is issued to the inverter main circuit 24 (112
).

In this embodiment, since the rotational speed of the wheel 20 is detected by the rotating sensor 26 and supplied to the controller 28, for example, as shown in FIG. Even in the case of sudden braking, the torque generated in the gear 22-3 does not reach the maximum allowable torque.

That is, the torque generated in the gear 22-3 is the reference torque T.
Even when the rotation speed exceeds the maximum allowable torque, feedback is applied to the controller 28 by the rotation speed sensor MAX 26, so that damage A to the gear 22-3, which conventionally occurs when the allowable maximum torque is reached at time tA, does not occur.

In this embodiment, the rotational speed of the wheels 20 is detected by the rotational speed sensor 26 and manually inputted to the controller 28, but the braking force from the wheel brakes is controlled by the brake oil pressure etc. without providing the rotational speed sensor 26. A configuration that calculates based on the brake signal of and performs motor 100 regenerative braking,
A so-called oven loop control configuration may also be used. In normal braking conditions other than special conditions where slippage occurs between the wheels and the road surface, this configuration can also provide the same effects as the present embodiment.

[Effects of the Invention] As explained above, in the electric vehicle deceleration motor control device of the present invention, the impact torque generated in the reduction gear due to wheel braking by the wheel brake is estimated and calculated by the impact torque calculation means, Since regenerative braking is performed to suppress the torque of the reducer based on the estimated torque, damage to the reducer due to this impact torque is prevented.

Furthermore, since it is possible to use gears with a lower allowable maximum torque, such as resin gears, as gears included in the reducer, it is possible to reduce gear noise, improve tone, and reduce weight.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing the configuration of a deceleration motor control device for an electric vehicle according to the present invention. FIG. 2 is a configuration diagram showing the configuration of a deceleration motor control device for an electric vehicle according to an embodiment of the present invention. , FIG. 3 is a flowchart showing the flow of operation of this embodiment, FIG. 4 is a model diagram showing an operation model of this embodiment, and FIG. 5 is a torque curve showing a torque change curve in this embodiment. It is a diagram. a... Motor control device for electric vehicle deceleration b.
... Wheel brake e ... Impact torque calculating means f ... Regenerative braking torque calculating means h ... Regenerative braking means g, 10 ... Motor d, 12 ... Speed reducer a, 20 ... Wheel 22 ... Gear 24 ... Inverter main circuit 26 ... Rotation speed sensor 28 ... Controller TB ... Impact torque TBMAX ... Reference torque T ... Required regenerative braking torque Configuration diagram of the invention Implementation (I vaporization of IF) Fig.

Claims (1)

[Scope of Claims] Impact torque calculation means that estimates and calculates the torque generated in a reduction gear connected to the wheel and including a predetermined number of gears when the wheel is braked by a wheel brake such as a hydraulic brake, and the impact torque regenerative braking torque calculation means for calculating regenerative braking torque necessary to suppress the torque actually generated in the reduction gear to a predetermined value or less based on the torque estimated and calculated by the calculation means; A motor control device for decelerating an electric vehicle, comprising: regenerative braking means for regeneratively braking a driving motor based on the regenerative braking torque calculated by the regenerative braking torque calculating means.