Method for regulating a voltage or a current of an RLC filter, a recording medium and vehicles for this method

1. A method for regulating a voltage U c between a first and a second output point of a low-pass RLC filter of natural period T f , the RLC filter including two input points electrically connected, respectively, to conductors of a DC bus of an electric vehicle powered via a catenary, first and second output points being electrically connected to a controllable electric converter for controlling torque exerted by an electric traction motor of the electric vehicle, stator time constant τ of the electric traction motor being strictly less than the natural period T f , the method including measuring or estimating the intensity I li of a line current I l flowing through an inductance of the filter at an instant t i , of a voltage U ci between the first and second output points of the filter at the instant t i , and of a line voltage U l between the input points of the filter, wherein the method is a deadbeat control method comprising:

calculating a setting Ī uc for an average intensity Ī u of a DC current I u flowing through the first output point of the filter between the instant t i and an instant t i+1 , the setting Ī uc being established from discretized state equations of the filter in such a way that the voltage U c is equal to a predetermined voltage setting U cc at the instant t i+1 , the discretized state equations between them establishing relationships between the intensities and I li to I l,i+1 of a line current I l at the instants t i and t i+1 respectively, the voltages t ci and U c,i+1 between the first and second output points of the filter at the instants t i and t i+1 respectively, the average line voltage Ū l between the instants t i and t i+1 and the average intensity Ī u ; and

controlling the electric converter in order to produce a current I u flowing through the first output point of the filter, the average intensity Ī u of which between the instants t i and t i+1 is equal to the setting Ī uc , the time interval T between the instants t i and t i+1 being strictly less than 5τ.

2. The method according to claim 1 , wherein the voltage setting U cc is chosen always to be less than or equal to a limit U cmax , the limit U cmax corresponding to the maximum allowable voltage at the input of the electric converter or between the output points of the filter.

3. The method according to claim 1 , wherein the method includes:

constructing an estimate I lp of the line current I l which will be reached if the voltage U c is equal to the voltage setting U cc at the instant t i+1 ;

comparing the estimate I lp with at least one predetermined limit I lm ;

only if the predetermined limit I lm is crossed, modifying the voltage setting U cc so as to obtain a temporary voltage setting U ccm which corresponds to an estimate I lp that does not cross the predetermined limit I lm , and using the temporary voltage setting U ccm in place of the voltage setting U cc during the calculation of the setting Ī uc only for the interval T in progress; and

if the predetermined limit I lm is not crossed, using the voltage setting U cc for calculating the setting Ī uc for the interval T in progress.

4. The method according to claim 1 , wherein the setting Ī uc is a solution of the following system of equations:

I

lp

-

μ

2

·

C

·

U

cc

=

ⅇ

μ

1

·

T

·

(

I

li

-

μ

2

·

C

·

U

ci

)

+

a

1

·

(

μ

2

·

I

_

uc

+

1

L

·

U

_

l

)

I

lp

-

μ

1

·

C

·

U

cc

=

ⅇ

μ

2

·

T

·

(

I

li

-

μ

1

·

C

·

U

ci

)

+

a

2

·

(

μ

1

·

I

_

uc

+

1

L

·

U

_

l

)

where:

R and L are the values of the resistance and the inductance, respectively, of the RLC filter, and which are connected in series between the first input and output points;

C is the capacitance of the capacitor connected between the first and second output points;

μ 1 and μ 2 are the eigenvalues of an evolution matrix and are defined by the following relationships:

μ

1

=

-

R

·

C

+

R

2

·

C

2

-

4

·

L

·

C

2

·

L

·

C

μ

2

=

-

R

·

C

-

R

2

·

C

2

-

4

·

L

·

C

2

·

L

·

C

;

and

a 1 and a 2 are values defined by the following relationships:

a

1

=

⁢

ⅇ

μ

1

·

T

-

1

μ

1

a

2

=

⁢

ⅇ

μ

2

·

T

-

1

μ

2

.

5. The method according to claim 1 , wherein the voltage setting U cc is constructed from the line voltage U l in such a way that its power spectrum does not exhibit any harmonic beyond the frequency 0.9/T f .

6. The method according to claim 1 , wherein the method includes controlling a rheostat in order to produce, in combination with the control of the converter, the current I u flowing through the first output terminal of the filter, the average intensity Ī u of which between the instants t i and t i+1 is equal to the current setting Ī uc .

7. The method according to claim 1 , wherein the interval T is less than or equal to τ/5.

8. An information recording medium comprising instructions for executing a method as recited in claim 1 when these instructions are executed by an electronic computer.

9. A method for regulating a line current I l flowing through an inductance L of a low-pass RLC filter of natural period T f , this filter including:

two input points electrically connected, respectively, to the conductors of a DC bus of an electric vehicle powered via a catenary; and

first and second output points, the first output point being electrically connected to a controllable electric converter in order to cause the torque of an electric traction motor of the electric vehicle to vary, the stator time constant τ of this electric motor being strictly less than the natural period T f , the method including:

measuring or estimating of the intensity I li of the line current I l at an instant t i , of a voltage U ci between the output points of the filter at the instant t i , and of a line voltage U l between the input points of the filter, wherein the method is a deadbeat control method including:

calculating a setting Ī uc for the average intensity Ī u of a DC current I u flowing through the first output point of the filter between the instant t i and an instant t i+1 , the setting Ī uc being established from discretized state equations of the filter in such a way that the intensity of the line current I l is equal to a predetermined line current setting T lc at the instant t i+1 , the discretized state equations between them establishing relationships between the intensities I li and I l,i+1 of the line current I l at the instants t i and t i+1 respectively, the voltages U ci and U c,i+1 between the output points of the filter at the instants t i and t i+1 respectively, the average line voltage Ū l between the instants t i and t i+1 and the average intensity Ī u ; and

controlling the electric converter to produce a current I u flowing through the output point, the average intensity Ī u of which between the instants t i and t i+1 is equal to the setting Ī uc , the time interval T between the instants t i and t i+1 being strictly less than 5τ.

10. The method according to claim 9 , wherein the line current setting I lc is chosen always to be less than or equal to a limit I lmax , the limit I lmax corresponding to the intensity of the line current I l at which a circuit-breaker of a power substation of the catenary or of the electric vehicle is tripped.

11. The method according to claim 9 , wherein the line current setting I lc is chosen always to be greater than or equal to a limit I lmin the limit I lmin corresponding to the intensity of the line current below which the inductance L of the filter is desaturated.

12. The method according to claim 9 , wherein the method includes:

constructing an estimate U cp of the voltage U c which will be reached between the output points of the filter at the instant t i+1 if the intensity of the line current I l is equal to the line current setting I lc at the instant t i+1 ;

comparing the voltage estimate U cp with at least one predetermined voltage limit U cm ;

only if the predetermined voltage limit U cm is crossed, modifying the line current setting I lc so as to obtain a temporary line current setting I lcm which corresponds to a voltage estimate U cp that does not cross the predetermined voltage limit U cm , and using the temporary line current setting I lcm in place of the line current setting I lc during the control of the converter only over the interval T in progress; and

if the predetermined voltage limit U cm is not crossed, using the line current setting I lc during the calculation of the current setting Ī uc for the interval T in progress.

13. The method according to claim 9 , wherein the current setting Ī uc is a solution of the following system of equations:

I

lc

-

μ

2

·

C

·

U

cp

=

ⅇ

μ

1

·

T

·

(

I

li

-

μ

2

·

C

·

U

ci

)

+

a

1

·

(

μ

2

·

I

_

uc

+

1

L

·

U

_

l

)

I

lc

-

μ

1

·

C

·

U

cp

=

ⅇ

μ

2

·

T

·

(

I

li

-

μ

1

·

C

·

U

ci

)

+

a

2

·

(

μ

1

·

I

_

uc

+

1

L

·

U

_

l

)

where:

R and L are the values of the resistance and the inductance, respectively, of the RLC filter, and which are connected in series between the first input and output points;

C is the capacitance of the capacitor connected between the first and second output points;

μ 1 and μ 2 are the eigenvalues of an evolution matrix and are defined by the following relationships:

μ

1

=

-

R

·

C

+

R

2

·

C

2

-

4

·

L

·

C

2

·

L

·

C

μ

2

=

-

R

·

C

-

R

2

·

C

2

-

4

·

L

·

C

2

·

L

·

C

;

and

a 1 and a 2 are values defined by the following relationships:

a

1

=

⁢

ⅇ

μ

1

·

T

-

1

μ

1

a

2

=

⁢

ⅇ

μ

2

·

T

-

1

μ

2

.

14. A method comprising:

a first phase for regulating only a voltage U c between first and second output points of a low-pass RLC filter of natural period T f , the RLC filter including two input points electrically connected, respectively, to conductors of a DC bus of an electric vehicle powered via a catenary, first and second output points being electrically connected to a controllable electric converter for controlling torque exerted by an electric traction motor of the electric vehicle, stator time constant τ of the electric traction motor being strictly less than the natural period T f , the first phase method including measuring or estimating the intensity I li of a line current I l flowing through an inductance of the filter at an instant t i , of a voltage U ci between the first and second output points of the filter at the instant t i , and of a line voltage U l between the input points of the filter, wherein the first phase method is a deadbeat control method comprising:

calculating a setting Ī uc for an average intensity Ī u of a DC current I u flowing through the first output point of the filter between the instant t i and an instant t i+1 , the setting Ī uc being established from discretized state equations of the filter in such a way that the voltage U c is equal to a predetermined voltage setting U cc at the instant t i+1 , the discretized state equations between them establishing relationships between the intensities I li and I l,i+1 of a line current I l at the instants t i and t i+1 respectively, the voltages U ci and U c,i+1 between the first and second output points of the filter at the instants t i and t i+1 respectively, the average line voltage Ū l between the instants t i and t i+1 and the average intensity Ī u ;

controlling the electric converter in order to produce a current I u flowing through the first output point of the filter, the average intensity Ī u of which between the instants t i and t i+1 is equal to the setting Ī uc , the time interval T between the instants t i and t i+1 being strictly less than 5τ;

a second phase for regulating only the intensity of the line current I l in accordance with claim 9 ; and

switchover from the first phase to the second phase as soon as the intensity of the line current I l crosses a limit I lm and switchover from the second phase to the first phase as soon as the intensity of the line current I l crosses the same or another limit in the opposite direction.

15. An electric vehicle including:

a DC bus formed by two conductors;

at least one traction motor of the electric vehicle having a stator time constant τ;

a controllable electric converter intended to cause the torque of the traction motor to vary;

a low-pass RLC filter including two input points electrically connected, respectively, to the two conductors of the DC bus, and first and second output points electrically connected to the electric converter;

sensors or estimators intended to measure or estimate the intensity I li of a line current I l flowing through the inductance of the filter at the instant t i , a voltage U ci between the output points of the filter at the instant t i , and a line voltage U l between the input points of the filter;

a computer for calculating a current setting Ī uc for the average intensity Ī u of a DC current I u flowing through the first output point between the instant t i and an instant t i+1 , this current setting Ī uc being established from discretized state equations of the filter in such a way that the voltage U c is equal to a predetermined voltage setting U cc at the instant t i+1 , the discretized state equations between them establishing relationships between the intensities I li ; and I l,i+1 of the line current I l at the instants t i and t i+1 respectively, the voltages U ci and U c,i+1 between the output points of the filter at the instants t i and t i+1 respectively, the average line voltage Ū l between the instants t i and t i+1 and the average intensity Ī u ; and

a control unit for controlling the electric converter in order to produce a current I u flowing through the output point of the filter, the average intensity Ī u of which between the instants t i and t i+1 is equal to the setting Ī uc , the time interval T between the instants t i and t i+1 being strictly less than 5τ.

16. An electric vehicle including:

a DC bus formed by two conductors;

at least one traction motor of the electric vehicle having a stator time constant τ;

a controllable electric converter intended to cause the torque of the traction motor to vary;

a low-pass RLC filter including two input points electrically connected, respectively, to the two conductors of the DC bus, and first and second output points electrically connected to the electric converter;

sensors or estimators intended to measure or estimate the intensity I li of a line current I l flowing through the inductance (L) of the filter at the instant t i , a voltage U ci between the output points of the filter at the instant t i , a voltage U l between the input points of the filter;

a computer for calculating a current setting Ī uc for the average intensity Ī u of a DC current I u flowing through the first output point of the filter between the instant t; and an instant t i+1 , this current setting Ī uc being established from discretized state equations of the filter in such a way that the intensity of the line current I l is equal to a predetermined line current setting I lc at the instant t i+1 , these discretized state equations between them establishing relationships between the intensities and I li and I l,i+1 of the line current I l at the instants t i and t i+1 respectively, the voltages U ci and U c,i+1 between the output points of the filter at the instants t i and t i+1 respectively, the average line voltage Ū l between the instants t i and t i+1 and the average intensity Ī u ; and

a control unit for controlling the electric converter in order to produce a current I u flowing through the output point of the filter, the average intensity Ī u of which between the instants t i and t i+1 is equal to the current setting Ī uc , the time interval T between the instants t i and t i+1 being strictly less than 5τ.