JPH0458246B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention divides a plurality of main motors into two groups, and connects these two groups in parallel at high speeds and in series at low speeds to apply regenerative braking. The present invention relates to a braking control device for an electric vehicle of a railway vehicle (hereinafter referred to as an electric vehicle).

[Conventional technology]

Conventionally, in electric vehicles, it has been common practice to use a motor as a generator to apply a generating brake or a regenerative brake. In electric vehicles where regenerative current is controlled by field control of a compound-wound motor or a series-wound motor, the effective speed range of the regenerative brake is often expanded by switching the two groups of main motors between parallel and series. .

Fig. 2 is a main circuit connection diagram of an electric car that performs such parallel-series control, and Fig. 3 shows the armature current for one electric car motor in the main circuit connection diagram of Fig. 2.
FIG. 3 is a diagram showing a speed characteristic curve.

First, the configuration of FIG. 2 will be explained. In the figure, 1
1 is a pantograph, 12 and 13 are main motors, 1
2A and 13A are the respective armatures of the main motors 12 and 13, 12B and 13B are the series-wound fields thereof,
Similarly, 12C and 13C respectively indicate the corresponding winding fields. 14 is a shunt field current regulator; 15;
16 is a parallel connection contactor that connects the main motors 12 and 13 in parallel; 17 is a series connection contactor that connects the main motors 12 and 13 in series; 18 is a resistor;
9 is an overhead line voltage detector, and 20 is an armature current detector.

In FIG. 3, the horizontal axis is the armature current of the main motor, and the vertical axis is its speed, which are indicated by symbols I _a and S, respectively. Curves A-A ₁ , B-B ₁ , and E-E ₁ are armature current-speed characteristic curves of the traction motor in which the shunt field current I _F of the traction motor is shown as a parameter. The overhead line voltage is assumed to be constant. The curves A-A ₁ and B-B ₁ are the characteristics of two groups of traction motors connected in parallel, and the curve E-E ₁ is the characteristics of the two groups connected in series. Curve E-E ₁ is the second
This is the characteristic when the resistor 18 in the figure is short-circuited, and when the resistor 18 is inserted, the characteristic becomes a curve D- _D1 .

When the regenerative brake is operating at point _B2 on the curve B- _B1 , that is, when the contactors 15 and 16 are closed in FIG. Assuming that its resistance value is R and the contact line voltage is V ₂ , a current V ₂ /R flows. If the resistance value of the resistor 18 is selected so that this current V ₂ /R is equal to the armature current I ₄ at point B ₂ , then the contactors 15 and 16 in FIG.
When opened, the armature current-speed characteristic is the curve D-D ₁
However, the armature current remains at I ₄ and parallel-series transfer is performed without any change. Thereafter, the resistance values of the resistors 18 are successively short-circuited, and the shunt field current is adjusted by the shunt field current regulator 14 to bring the armature current to a required value, and the regenerative braking is continued.

The armature current is curve C when two groups of main motors are in parallel.
- When the speed decreases on the line C ₁ , if parallel-series crossing is performed at the armature current I ₁ at point C ₁ , the armature current after contactors 15 and 16 are opened curves D - increases to point D ₂ on D ₁ , ie I ₃ .

In FIG. 3, S ₁ represents the speed at point D ₂ and point C ₁ , S ₂ represents the speed at point B ₂ , and I ₂ represents the armature current at point D ₁ .

Generally, in the above-mentioned parallel-series connection, the contactors 15, 1
After adjusting the value of resistor 18 so that the change in armature current before and after contactor 6 opens is small,
Open 16. However, as mentioned above, the contactors 15,1
If the armature current in the parallel state of two groups of motors with the resistor 18 closed is lower than that after the transition to the point on the curve D-D ₁ when the value of the resistor 18 is at its maximum, the braking force is originally Because of its small size, it was considered indispensable.

[Problem that the invention seeks to solve]

In an electric train that performs parallel-series control of two groups of traction motors as described above, if the regenerative load is insufficient, the contact line voltage exceeds the permissible upper limit during the parallel-series connection of the two traction motors, and The overvoltage detector was easy to operate. When the overvoltage detector was activated, regenerative braking was terminated, so the regenerative braking of the series stages was disabled from then on. Furthermore, since the contact line voltage exceeded the permissible upper limit, this was also a contributing factor to the deterioration of the commutation of the auxiliary rotating machine.

An object of the present invention is to reduce the possibility that an overvoltage detector will operate when parallel-series regenerative braking is performed near the permissible upper limit of overhead line voltage.

[Means and actions to solve the problem]

First of all, when considering why the overvoltage detector is likely to operate in the case of parallel-series connection in conventional equipment, the armature current I ₁ at point C ₁ in the third diagram and the armature current I ₃ at point D ₂ mentioned above. According to the relationship ｜2I ₁ ｜≧｜I ₃ ｜..., then the 2 groups of traction motors are connected in series to the regenerative load that accepts the current 2I ₁ flowing out from the pantograph to the overhead contact line when the 2 groups of traction motors are connected in parallel. Since the subsequent current I ₃ is sufficiently accepted, there will be no excessive rise in contact line voltage unless the regenerative load is dropped during the transfer. However, the armature current in two groups of traction motors in _{parallel is}
If I ₁ is squeezed to limit the contact line voltage, the parallel connection contactor 15 in FIG.
16 is opened, and there is no regenerative load to accept the increment of current after it passes to the first stage in series, that is, (|I ₃ | - | 2I ₁ |), causing the overhead line voltage to rise above the upper limit value.

Furthermore, in the process of successively shorting the resistors 18 in FIG. 3, the overhead line voltage may be momentarily increased by the amount of voltage drop reduction due to the change in resistance value.

Therefore, in the present invention, when the contact line voltage is close to the allowable upper limit value and the current value immediately before crossing is in the relationship according to the above formula, the armature current is temporarily reduced and regenerative braking is stopped, or the regenerative braking is stopped. After that, the shunt field current is weakened to a value that reduces the voltage generated by the main motor by half, and then the two groups of main motors are connected in series.

〔Example〕

Hereinafter, the present invention will be explained using a compound-wound motor as an example, similar to the description of the prior art described above, but the present invention provides field control that allows the series-wound field of a series-wound motor to be controlled independently of the armature current. It can also be applied to cars.

FIG. 1 is a flowchart of an embodiment in which the control of the present invention is performed by a microprocessor. In the figure, I _F is the shunt field current, and I _F2 is the shunt field current at the end of the parallel stage. current, I _a is the armature current, I ₃ is the planned armature current just after entering the series stage, V _L is the contact line voltage,
V _L0 is the permissible upper limit value of overhead line voltage. 1 to 3 are determined as regenerative brake control means X, 4 is regenerative brake discontinuation, 5 is parallel stage brake control continuation,
6 is a block showing transfer control.

In the flowchart of FIG. 1, determination 1 is a determination of the shunt field current I _F , and if it reaches the parallel control limit shunt field current I _F2 , a path in the YES direction is taken.
Determination 2 is to determine the armature current I _a when I _F ≧ I _F2 , and when connecting parallel to series, check the magnitude relationship with 1/2 of the expected value I ₃ of the current immediately after entering the series. , |
When I _a | < 1/2 | I ₃ |, take the path in the YES direction. Judgment 3 is to determine whether or not the contact line voltage limit is applied when I _F ≧ I _F2 , that is, |I _a | < 1/2 | I ₃ | when entering parallel-series crossover. The voltage V _L is compared with the permissible upper limit value V _L0 of the overhead line voltage,
When V _L ≧ V _L0 , the path in the YES direction is taken and regenerative braking is terminated.

In determination 1, if I _F ≧ I _F2 , parallel braking is continued using the path in the NO direction. If the path in the NO direction is taken in determinations 2 and 3, normal parallel-series crossing is performed.

After the regenerative brake termination control is performed in the flowchart of FIG. 1, the shunt field may be weakened to reduce the main motor generated voltage by half, and then the series brake may be applied again. Note that the difference between I ₃ and I ₄ in FIG. 3 is slight, and I ₃ in determination 2 may be represented by I ₄ . Furthermore, the regenerative brake can be smoothly terminated under control.

〔Effect of the invention〕

According to the present invention described above, by determining the contact line voltage and armature current conditions at the end of parallel stage braking, it is possible to prevent the overvoltage relay from operating immediately after it is transferred to the series, thereby reducing the driver's anxiety. Moreover, it is possible to eliminate the negative influence on the auxiliary rotary machine, which helps to prevent failures of electric vehicles. The regenerative brake can be smoothly terminated under control, and the regenerative brake does not expire instantaneously like the operation of an overvoltage relay, making it possible to smoothly switch to the air brake and improving riding comfort.

[Brief explanation of drawings]

Fig. 1 is a control flowchart showing one embodiment of the present invention, Fig. 2 is a main circuit contact diagram of an electric vehicle that performs regenerative braking by field control that performs parallel-series control, and Fig. 3 is an armature current of the electric motor. FIG. 3 is a characteristic curve diagram showing speed characteristics. I _F ...Shunt field current, I _F2 ...Shunt field current at the end of parallel stage, I _a ...Armature current, I ₃ ...Planned armature current immediately after entering series stage, V _L ...Telephone line voltage,
V _L0 ... Permissible upper limit value of contact line voltage, 1 to 3... Discrimination block, X... Regenerative brake control means.

Claims (1)

[Scope of Claims] 1. A braking control device for an electric vehicle having a regenerative brake control means The regenerative brake control means X controls the detected value of the field current.
Input I _F , determine the magnitude relationship between this and the predetermined limit value I _F2 of the field current, input the detected armature current value I _a , and connect this and the transfer control to the series stage. Determine the magnitude relationship with 1/2 of the planned current value _I3 calculated in advance immediately after proceeding 2, input the detected value of the overhead line voltage, and compare this with the predetermined upper limit value V of the overhead line voltage. Determine the size relationship with _L0 3
However, when the above operation mode is in parallel stage, the above determination is (I _F )>(I _F2 ) or (I _F )=(I _F2 ), and (I _a )<(1/2)×( I ₃ ), and when (V _L ) > (V _L0 ) or (V _L ) = (V _L0 ), the regenerative brake is discontinued, and when (I _F ) < (I _F2 ), the regenerative brake of the parallel stage is applied. , (I _F ) > (I _F2 ) or (I _F ) = (I _F2 ), and (I _a ) > (1/2) × (I ₃ ) or (I _a ) = (1 /2)×(I ₃ ) or (V _L )<(V _L0 ), the electric vehicle braking control device 2 connects the regenerative brake of the parallel-series transfer stage. The braking control device for an electric vehicle according to claim 1, which is capable of restarting the series-stage braking after stopping the braking and reducing the motor voltage by half.