KR100986836B1 - Electric braking system considering rail grade for electric rail car - Google Patents

Abstract

Disclosed is an electric braking system for an electric vehicle considering a gradient of a track. Electric braking system of the electric vehicle of the present invention, a traction motor; An inverter controlling the traction motor according to the set braking torque; A load torque estimator for estimating load torque of the traction motor according to the gradient of the track; A braking mode switch for switching from a first braking mode having a predetermined braking torque to a second braking mode in which the braking torque is gradually reduced; And a stop controller for reducing the set braking torque based on the rotational speed of the traction motor and the estimated load torque in the second braking mode. According to the present invention, it is possible to stably stop the electric vehicle without using air braking, thereby improving the performance of the electric vehicle such as riding comfort and contributing to environmentally friendly aspects.

Electric car, electric braking, air braking, gradient, stop

Description

ELECTRIC BRAKING SYSTEM CONSIDERING RAIL GRADE FOR ELECTRIC RAIL CAR}

The present invention relates to an electric braking system for an electric vehicle, and more particularly, to an electric braking system for an electric vehicle that stops the electric vehicle by electric braking.

Recently, as railway vehicles, especially subways, have been developed as an important means of public transportation, the reliability of driving of electric vehicles is required for the improvement of passenger convenience and safety, and more stable and economical Operation is required.

In general, when the vehicle is to be stopped, the electric vehicle is initially decelerated by electric braking and air braking is used to the stopping point in the low speed region of about 5 km / h or less.

Here, "electric braking" refers to a method of obtaining a braking force by operating a generator to convert kinetic energy into electrical energy to obtain a braking force, and "air braking" refers to a method of obtaining braking force by using friction of a disk by air pressure.

However, air braking causes the wear of the braking components and the resulting noise and dust, which ultimately degrades the performance of the vehicle, such as increased maintenance costs and reduced ride comfort. It is desirable to reduce.

Therefore, a new control system is required to stop the electric vehicle by electric braking in the low speed region without using air braking. When the electric vehicle is to be stopped by electric braking, the air braking stops after stopping. Only functions will be in charge.

On the other hand, in order to stop the electric vehicle by electric braking where there is a gradient of the track, the traction motor must prevent the rotation of the traction motor until the stop brake by air braking is used. Should be generated.

That is, in the control system which stops an electric vehicle by electric braking, it is necessary to consider the influence by the gradient of a track.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electric braking system for an electric vehicle that can stably stop an electric vehicle without using air braking, thereby improving the performance of an electric vehicle such as riding comfort and contributing to an environment-friendly aspect.

The object is, according to the present invention, a traction motor; An inverter controlling the traction motor according to a set braking torque; A load torque estimator for estimating load torque of the traction motor according to a gradient of a track; A braking mode switch for switching from a first braking mode having the set braking torque to a second braking mode in which the set braking torque is gradually reduced; And a stop controller for reducing the set braking torque based on the rotational speed of the traction motor and the estimated load torque in the second braking mode. Is achieved.

Here, the braking mode switcher may determine a time point for switching from the first braking mode to the second braking mode based on the rotation speed and the estimated load torque.

The braking mode switcher may switch to the second braking mode when the following Equation 1 is satisfied.

[Equation 1]

here,

T: Setting brake torque of the first braking mode

: 추정 부하토크

: Estimated load torque

k: proportionality constant

ω: Rotational speed of traction motor

The stop controller may reduce the set braking torque according to Equation 2 below.

[Equation 2]

here,

T ^* : Setting brake torque of the second braking mode

: 추정 부하토크

: Estimated load torque

k: proportionality constant

ω: Rotational speed of traction motor

The load torque estimator may estimate the load torque through a process of estimating the rotational speed of the traction motor using a proportional integral controller.

The load torque estimator may estimate the load torque by the following equations (3) and (4).

&Quot; (3) "

&Quot; (4) "

here,

J _e : Mean moment of inertia of train

: 견인전동기의 추정 회전속도

: Estimated rotation speed of traction motor

ω: Rotational speed of traction motor

T ^* : Setting brake torque of the second braking mode

: 추정 부하토크

: Estimated load torque

k _i : Integral gain of proportional integral controller

k _p : Proportional gain of proportional integral controller

The stop controller may use a first order delay filter for feedback of the rotational speed and the estimated load torque.

The apparatus may further include a speed detector configured to detect a rotation speed of the traction motor.

The traction motor may be a permanent magnet traction motor, and the inverter may be a variable voltage variable frequency (VVVF) inverter.

According to the present invention, by electrically connecting a resistance between the traction motor and the inverter during electric braking of the electric vehicle, it is possible to secure sufficient electric braking force of a constant torque operating region in a high speed region exceeding the maximum output voltage of the inverter, thus eliminating air braking. Can be.

In order to fully understand the present invention, the operational advantages of the present invention, and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings which illustrate preferred embodiments of the present invention and the contents described in the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in order to avoid unnecessary obscuration of the present invention.

1 is a schematic configuration diagram of an electric braking system of an electric vehicle according to an embodiment of the present invention, FIG. 2 is a graph for explaining switching of a braking mode in the electric braking system of FIG. 1, and FIG. Control block diagram for a second braking mode of the electric braking system.

)와 부하토크 추정기(130)에 의해 추정된 부하토크(

)에 기초하여 설정제동토크를 감소시키는 정지 제어기(150)를 구비한다.Referring to FIG. 1, the electric braking system 100 of the electric vehicle according to the present embodiment includes a traction motor 110, an inverter 120 for controlling driving of the traction motor 110 according to a set braking torque, and a line. The load torque estimator 130 for estimating the load torque of the traction motor 110 according to the gradient of, the brake mode switch 140 for switching the braking mode, and the rotational speed of the traction motor 110 (

) And the load torque estimated by the load torque estimator 130

And a stop controller 150 for reducing the set braking torque.

In this case, the load torque estimator 130, the braking mode changer 140, and the stop controller 150 are means for controlling the vehicle to stop the electric vehicle. The inverter 120 may use a microprocessor or the like. It may be modular inside or implemented as a separate device.

)는 속도검출기(미도시)에 의해 검출되어 부하토크 추정기(130), 제동모드 전환기(140) 및 정지 제어기(150)에 입력된다. 이때, 속도검출기(미도시)는 레졸바 방식 또는 엔코더 방식으로 구현될 수 있다.And, the rotational speed of the traction motor 110 (

) Is detected by a speed detector (not shown) and input to the load torque estimator 130, the braking mode switcher 140, and the stop controller 150. In this case, the speed detector (not shown) may be implemented in a resolba method or an encoder method.

Referring to FIG. 1, the traction motor 110 is a means for providing a driving force to an electric vehicle, and drives a driving wheel of the electric vehicle to drive the electric vehicle. In this embodiment, a permanent magnet motor (PMSM), which is widely used in electric vehicles, is used as the traction motor 110.

Permanent magnet motor is one of the AC motors. It has a three-phase winding stator (an armature) consisting of a sine wave and a rotor for generating NS magnetic flux with permanent magnets. Like other AC motors, it is required for DC motors. The maintenance cost is low because the commutator and brush are omitted, and the output is larger than the size of DC motor. In addition, since the rotor is a permanent magnet, the volume and weight of the rotor are relatively small, so the inertia is reduced. It has the advantage of being excellent.

However, in the present invention, the traction motor 110 is not limited to the permanent magnet motor, and other AC motors such as induction motors and synchronous motors may be used as the traction motors 110.

On the other hand, during electric braking of the electric vehicle, the traction motor 110 is converted into a generator to generate power. Here, the electric braking is to stop the power supply to the traction motor 110, stop the normal driving and transfer the rotation of the normal wheel to the traction motor 110 in the opposite direction, the traction motor 110 is a generator It is a braking method that converts kinetic energy into electric energy and operates to obtain braking force.

Such electric braking converts power generated during braking into thermal energy through a braking resistor and dissipates it to the outside to generate braking power, and sends power generated during braking to the electric wire to be applied to other electric vehicles running around or to electric energy. It is divided into regenerative braking which obtains braking force by charging the storage device.

Referring to FIG. 1, the inverter 120 is a device that converts DC power into AC power, and controls driving of the traction motor 110. Inverter 120 used in the present embodiment is a VVVF (Variable Voltage Variable Frequency) inverter 120, the voltage and frequency required for the DC power input through the pantograph (current collector) provided at the upper end of the electric vehicle The drive of the traction motor 110 is controlled by converting it into AC power and applying the same to the traction motor 110. At this time, the speed and torque of the traction motor 110 is controlled by the voltage and frequency determined by the inverter 120. On the other hand, when AC power is input through the pantograph, AC power is converted into DC power by a converter (not shown) and then input to the inverter 120.

On the other hand, the inverter 120 controls the traction motor 110 based on the set braking torque that is input differently according to the braking mode during electric braking of the electric vehicle. That is, the inverter 120 controls the driving of the traction motor 110 so that the braking torque generated by the traction motor 110 follows the set braking torque during electric braking of the electric vehicle.

)와 인버터(120)의 설정제동토크에 기초하여 선로의 구배에 따른 견인전동기(110)의 부하토크를 추정한다. 부하토크 추정기(130)의 세부적인 구성과 원리에 대한 설명은 후술하기로 한다.1 and 2, the load torque estimator 130 is a means for estimating the load torque of the traction motor 110 according to the gradient of the track, and the rotational speed of the traction motor 110 (

) And the load torque of the traction motor 110 according to the gradient of the track based on the set braking torque of the inverter 120. Details of the configuration and principle of the load torque estimator 130 will be described later.

The slope of the track means that the track on which the electric vehicle runs is inclined. Since the slope of the track affects the traction of the electric vehicle, it is preferable to level the track so that there is no gradient as much as possible, but the slope of the track is inevitably caused by the geographic environment such as mountains or hilly areas. The slope of the track is divided into an upward slope (uphill) and a downward slope (downhill) according to the traveling direction.

On the other hand, in order to stop the electric vehicle by electric braking, the slope of the line as above should be considered, in this specification, the load torque, the traction motor 110 required to compensate for the movement of the electric vehicle caused by the gradient of the line during electric braking ) Torque. That is, the inverter 120 should control the traction motor 110 so that the traction motor 110 generates torque corresponding to the load torque according to the gradient of the track at the time when the electric vehicle stops.

은 부하토크 추정기(130)에 의해 추정된 부하토크이며, 도 2에서 T_L 와

는 실질적으로 동일한 값을 갖는 것으로 도시되어 있다.For reference, Figure 2 shows the set braking torque and the load torque in the down gradient, T _L is the actual load torque,

Is the load torque estimated by the load torque estimator 130, and T _L in FIG. Wow

Is shown to have substantially the same value.

)가 대략 3rpm 정도에서 시작된다.1 and 2, in the electric braking system 100 according to the present embodiment, the braking mode includes a first braking mode in which the set braking torque has a constant value, and a second braking in which the set braking torque gradually decreases. Includes a mode. In this case, the second braking mode is a braking mode for controlling the electric braking of the electric vehicle in the extremely low speed region close to the stop point of the electric vehicle, and is performed for a relatively short time compared to the time of performing the first braking mode. For reference, according to the experiment, the second braking mode is the rotational speed of the traction motor 110 (

) Starts at about 3 rpm.

Hereinafter, for convenience of explanation, the set braking torque T in the first braking mode is referred to as the first set braking torque and the set braking torque T ^* in the second braking mode as the second set braking torque.

)와 부하토크 추정기(130)에 의해 추정된 부하토크(

이하 '추정 부하토크'라 함)에 기초하여 제1 제동모드에서 제2 제동모드로 전환하는 시점을 결정한다.1 and 2, the braking mode switch 140 is a means for switching from the first braking mode to the second braking mode having the above characteristics, and the rotational speed of the traction motor 110 (

) And the load torque estimated by the load torque estimator 130

Based on the " estimated load torque " below, a time point for switching from the first braking mode to the second braking mode is determined.

Specifically, the braking mode switcher 140 switches the braking mode when the following Equation 1 is satisfied.

[Equation 1]

here,

T: 1st set braking torque

: 추정 부하토크

: Estimated load torque

k: proportionality constant

: 견인전동기의 회전속도

: Rotational speed of traction motor

= 0)에 근접하게 되므로 전동차 승차감은 향상되나 제어 정밀도는 떨어지는 경향을 보인다.Proportional constant k is determined experimentally in consideration of ride comfort, control accuracy and the like. At this time, as k increases, the switching point of the braking mode is a stop point (

= 0), the driving comfort is improved, but control accuracy tends to be inferior.

)와 추정 부하토크(

)에 기초하여 제2 설정제동토크를 감소시킨다. 즉, 제2 제동모드에서 인버터(120)에 입력되는 제2 설정제동토크는 일정한 값으로 고정되는 것이 아니라, 견인전동기(110)의 회전속도(

)와 추정 부하토크( )에 대한 함수로 표현되고, 전동차의 정차점에 가까워질수록 감소하여 최종적으로 추정 부하토크(

)에 수렴한다.1 to 3, the stop controller 150 is a means for inputting the second set braking torque to the inverter 120 in the second braking mode.

) And estimated load torque (

Decreases the second set braking torque. That is, the second set braking torque input to the inverter 120 in the second braking mode is not fixed to a constant value, but the rotational speed of the traction motor 110 (

) And estimated load torque ( It is expressed as a function of), and decreases as it approaches the stop point of the train. Finally, the estimated load torque (

Converge)

Specifically, the stop controller 150 reduces the second set braking torque according to Equation 2 below.

[Equation 2]

here,

T ^* : 2nd set braking torque

: 추정 부하토크

: Estimated load torque

k: proportionality constant

: 견인전동기의 회전속도

: Rotational speed of traction motor

)와 추정 부하토크(

)의 궤환에 1차 지연필터(151)를 사용하는데, 이는 견인전동기(110)의 회전속도(

)의 검출 및 부하토크의 추정에 있어서 발생하는 오차와 노이즈 등을 최소화하기 위함이다.On the other hand, the stop controller 150 according to the present embodiment, as shown in Figure 3, the rotational speed of the input traction motor 110 (

) And estimated load torque (

The first delay filter 151 is used for the feedback of), which is the rotational speed of the traction motor 110 (

This is to minimize the error and noise that occur in the detection of) and the estimation of the load torque.

Hereinafter, a method of estimating the load torque according to the gradient of the line in the second braking mode will be described with reference to FIG. 3.

)를 추정하는 과정을 통해 제2 제동모드에서 선로의 구배에 따른 견인전동기(110)의 부하토크를 추정한다.As shown in FIG. 3, the load torque estimator 130 uses a proportional integral controller (PI controller) to rotate the rotational speed of the traction motor 110.

) Estimates the load torque of the traction motor 110 according to the gradient of the track in the second braking mode.

Specifically, the load torque estimator 130 estimates the load torque according to the gradient of the line in the second braking mode by the following Equations 3 and 4 below.

&Quot; (3) "

&Quot; (4) "

here,

J _e : Mean moment of inertia of train

: 견인전동기의 추정 회전속도

: Estimated rotation speed of traction motor

ω: Rotational speed of traction motor

T ^* : 2nd set braking torque

: 추정 부하토크

: Estimated load torque

k _i : Integral gain of proportional integral controller

k _p : Proportional gain of proportional integral controller

In [Equation 3] J _e represents the average moment of inertia of the train, the actual moment of inertia (J, see Fig. 3) of the train depends on the number of passengers in the train, so the exact moment of inertia (J) In the calculation process of estimating load torque according to the gradient of the track, the average moment of inertia of the train (J _e ) is used.

In equation 4, the control parameter k _i And k _p is the integral gain and the proportional gain, respectively, determined by mathematical or experimental / empirical methods.

)는 위와 같은 원리로 얻어진다. 다만, [수학식 3]에서 제2 설정제동토크(T^*)는 제1 설정제동토크(T)로 대체된다.On the other hand, as described above, in determining the timing at which the braking mode switcher 140 switches from the first braking mode to the second braking mode, it is required to estimate the load torque according to the gradient of the line (see Equation 1). ), Also in this case, the estimated load torque (

) Is obtained on the same principle as above. However, in [Equation 3], the second set braking torque (T ^* ) is replaced by the first set braking torque (T).

As described above, the electric braking system 100 according to the present embodiment does not use air braking by gradually decreasing the set braking torque input to the inverter 120 in the extremely low speed region close to the stop point of the electric vehicle. It is possible to stop the electric vehicle stably without using it.

Accordingly, the electric braking system 100 according to the present embodiment can suppress abrasion of the braking components generated during air braking and noise and dust caused by the braking components, thereby improving the performance of the electric vehicle such as riding comfort and improving the environment. Can contribute.

It is apparent to those skilled in the art that the present invention is not limited to the above-described embodiments, and that various modifications and changes can be made without departing from the spirit and scope of the present invention. Therefore, such modifications or variations will have to be belong to the claims of the present invention.

1 is a schematic configuration diagram of an electric braking system of an electric vehicle according to an embodiment of the present invention.

FIG. 2 is a graph for explaining switching of the braking mode in the electric braking system of FIG. 1.

3 is a control block diagram of a second braking mode of the electric braking system of FIG.

<Explanation of symbols for the main parts of the drawings>

100: electric braking system for electric vehicles.

110: traction motor

120: inverter

130: load torque estimator

140: braking mode switch

150: stop controller

Claims (10)

Traction motors; An inverter controlling the traction motor according to a set braking torque; A load torque estimator for estimating load torque of the traction motor according to a gradient of a track; A braking mode switch for switching from a first braking mode having the set braking torque to a second braking mode in which the set braking torque is gradually reduced; And And a stop controller for reducing the set braking torque based on the rotational speed of the traction motor and the estimated load torque in the second braking mode. The method of claim 1, The braking mode switcher, And a time point for switching from the first braking mode to the second braking mode based on the rotation speed and the estimated load torque. The method of claim 2, The braking mode switcher, An electric braking system for an electric vehicle in consideration of a gradient of a line, characterized in that the switching to the second braking mode when the following Equation 1 is satisfied. [Equation 1]

here, T: Setting brake torque of the first braking mode

: Estimated load torque k: proportionality constant ω: Rotational speed of traction motor The method of claim 1, The stop controller, An electric braking system for an electric vehicle in consideration of a gradient of a track according to Equation 2 below, wherein the set braking torque is reduced. [Equation 2]

here, T ^* : Setting brake torque of the second braking mode

: Estimated load torque k: proportionality constant ω: Rotational speed of traction motor The method of claim 1, The load torque estimator, An electric braking system for an electric vehicle in consideration of a gradient of a track, wherein the load torque is estimated by estimating the rotational speed of the traction motor using a proportional integral controller. The method of claim 5, The load torque estimator, An electric braking system for an electric vehicle in consideration of a gradient of a track, characterized in that the load torque is estimated by the following equations (3) and (4). &Quot; (3) &quot;

&Quot; (4) &quot;

here, J _e : Mean moment of inertia of train

: Estimated rotation speed of traction motor ω: Rotational speed of traction motor T ^* : Setting brake torque of the second braking mode

: Estimated load torque k _i : Integral gain of proportional integral controller k _p : Proportional gain of proportional integral controller The method of claim 1, The stop controller, An electric braking system for an electric vehicle in consideration of a gradient of a line, wherein the first delay filter is used for the feedback of the rotational speed and the estimated load torque. The method of claim 1, The electric brake system of the electric vehicle in consideration of the gradient of the track, characterized in that it further comprises a speed detector for detecting the rotational speed of the traction motor. The method of claim 1, The traction motor is an electric braking system of an electric vehicle in consideration of the gradient of the track, characterized in that the permanent magnet traction motor. The method of claim 1, The inverter is a VVVF (Variable Voltage Variable Frequency) inverter electric braking system of the electric vehicle in consideration of the gradient of the line.

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