WO2012095595A2

WO2012095595A2 - Controlling voltage in a hybrid vehicle

Info

Publication number: WO2012095595A2
Application number: PCT/FR2012/050042
Authority: WO
Inventors: Yannick EVAIN; Frédéric Bechade; Michel BOUESSEAU
Original assignee: Societe Nationale Des Chemins De Fer Francais Sncf
Priority date: 2011-01-13
Filing date: 2012-01-06
Publication date: 2012-07-19
Also published as: WO2012095595A3; EP2663465A2; FR2970442B1; FR2970442A1

Abstract

The invention relates to a vehicle (2) including a plurality of onboard electrical power sources (6, 8, 10) connected together by a voltage bus (14), said vehicle further including a means for controlling the voltage of the bus (14), characterized in that the control means includes at least one ultracapacitor (10) connected to the voltage bus (14), said ultracapacitor (10) forming a part of the plurality of sources.

Description

Voltage regulation in a hybrid vehicle

The present invention relates to a vehicle comprising a plurality of on-board electrical power sources and connected by a voltage bus. It also relates to a method of regulating the voltage of the voltage bus.

The invention is particularly interested in the field of rail transport, particularly in the field of hybrid railway vehicles.

Currently, two main railway gear architectures are operated in Europe. The first architecture is based on electric locomotives and the second architecture is based on diesel locomotives. On electric locomotives, energy is distributed by sampling on a catenary through pantographs, transformers (in the case of alternative networks) and converters. On a diesel locomotive, energy is produced on site by a generator associated with a heat engine. Both

15 architectures have a common part consisting of traction motors and auxiliaries.

On the one hand, the hybridization of diesel locomotives promotes fuel economy resulting in a reduction of harmful emissions and noise pollution. On the other hand, for an electric locomotive, hybridization with

20 local storage of electricity allows the l issage consumption on the catenary and a better quality of the energy distribution network.

A hybrid railway vehicle conventionally comprises a plurality of sources and consumers of electrical energy on board and connected by a voltage bus. The sources of electrical energy generally include

A generator and / or a fuel cell and / or an external electrical supply of the catenary type, and / or a supercapacitor and / or a battery and / or a flywheel.

The voltage bus connecting the sources of electrical energy is generally defined in a range of operating voltage. Apart from

In this voltage range, the operation and safety of the sources connected to the bus can not be guaranteed. It is therefore essential to ensure the stability of the bus voltage by regulating this voltage in order to avoid overvoltages and under-voltages.

This problem is accentuated by the fact that rail vehicles are frequently used for frequent multi-stop m issions, for example yard and local and urban service missions. During these 5 uses, overvoltages and under-voltages may occur during the connection and / or disconnection of at least one consumer while the energy sources are supplying the voltage bus called transient operating of the machine. It is important to limit the occurrence of these overvoltages and undervoltage.

A conventional solution for imitating surges is to connect a consumer to the bus. This consumer is often in the form of a resistive block loss Joule effect.

This solution is however not optimal because of the dissipation of electrical energy in the form of heat.

The present invention aims to improve the situation.

To this end, the invention firstly relates to a vehicle comprising a plurality of on-board electrical power sources and connected by a voltage bus, said vehicle further comprising means for regulating the bus voltage, characterized in that the regulating means comprise at

At least one supercapacitor comprises at least one of said plurality of sources, said supercapacitor being one of the plurality of sources.

The use of one or more supercapacitors connected to the voltage bus and used as the source (s) of electrical energy to regulate the bus voltage minimizes the energy losses during operation. phases of

25 limitation of overvoltages. It also makes it possible to restore the energy absorbed during overvoltages during undervoltage. In addition, the use of supercapacitors connected to the voltage bus has a very stabilizing effect because it generates very little ripple and / or resonance. Moreover, the charging and discharging cycle time of a supercapacitor makes the latter

30 particularly suitable for regulating the voltage on the bus.

According to the invention, the regulation means comprise a device for correcting the bus voltage. This correction device comprises a first integral proportional corrector. Such a corrector allows indeed a high accuracy of the regulation.

Preferably, the first integral proportional corrector makes it possible to impose a bus voltage satisfying the achievement of the equilibrium of the currents entering and leaving the bus since the sum of these currents must be zero (law of the nodes or law of Kirchhoff). The bus voltage setpoint thus determined is assigned to the supercapacitor.

Advantageously, the regulation means also comprise means for controlling the charge level of the supercapacitor,

o The level or charge rate of a supercapacitor is defined as the percentage of the current load relative to the maximum load expected in the supercapacitor. Control of this level of charge ensures that the supercapacitor can at any time supply or absorb current from the voltage bus.

Preferably, the charge level control means of the supercapacitor comprise a second integral proportional corrector, in particular distinct from the first integral proportional corrector.

According to a preferred embodiment, the second integral proportional corrector reacts slowly, its action being realized over durations ranging from one second to several tens of seconds.

Advantageously, the plurality of on-board electrical energy sources comprises a generator.

This generating set, comprising an internal combustion engine, in particular diesel, produces the energy required for the traction and supply of the vehicle auxiliaries.

Advantageously, the bus voltage is regulated to be between 520 and 600 V, preferably to be equal to 540 V.

The invention also relates to a method for regulating the voltage of a voltage bus connecting a plurality of electrical energy sources 30 mounted on a vehicle, said plurality of sources comprising at least one supercapacitor and a generator. characterized in that it comprises the steps of: -definition of a current setpoint at the output of the generator;

- measurement of the output current of the generator;

comparing the current setpoint and the measured current to obtain a current error value;

applying a first proportional integral corrector to the current error value to obtain a bus voltage setpoint; and

-supplying the voltage setpoint to the supercapacitor.

Advantageously, this process comprises the steps of:

-definition of a charge level of the charge of the supercapacitor;

- measurement of the charge level of the supercapacitor;

comparing the charge level setpoint and the measured charge level to obtain a charge level error value of the supercapacitor;

applying a second integral proportional corrector to the supercapacitor charge level error value to obtain an imbalance current; and

charging or discharging the supercapacitor according to the sign of the imbalance current.

Exemplary embodiments of the invention will now be described more specifically, but not limitatively, with reference to the accompanying drawings in which:

- Figure 1 is a diagram illustrating the structure of a vehicle according to one embodiment of the invention;

FIG. 2 is a diagram illustrating the means for regulating the voltage of the vehicle voltage bus of FIG. 1 according to one embodiment of the invention;

FIG. 3 is a diagram illustrating the structure and operation of the voltage correction device according to one embodiment of the invention; and FIG. 4 is a diagram illustrating the structure and operation of the charge level control means of the supercapacitor according to one embodiment of the invention.

FIG. 1 illustrates a vehicle 2 of hybrid type, such a vehicle being advantageously a railway vehicle. The vehicle 2 is provided with traction motors 4 for driving the vehicle. These motors 4 consume electrical energy produced by a plurality of electrical sources on board the vehicle 2. These onboard sources produce energy on board the vehicle 2.

In the example of FIG. 1, these sources comprise a generator 6, a battery pack 8 and a block of supercapacitors 10.

The generator 6 comprises in particular a diesel internal combustion engine providing a power equal to 230 kW, for example. It is the main source of electrical energy.

Alternatively, this main source may comprise a fuel cell, or a combination of a generator with a fuel cell.

The battery pack 8 preferably comprises Ni-Cd batteries (cadmium-nickel), which allows them to be charged quickly. For example, the battery pack 8 comprises 12 modules of 48 battery cell elements.

With a capacity of 135 Ah.

The supercapacitor block 10 includes a plurality of supercapacitors, for example 200 5000 F / 2.5V supercapacitors connected in series. The total capacitance of the block of supercapacitors is then equal, in this example to 25 F.

The vehicle 2 also comprises a set of auxiliaries 12 which include, in particular, a tractio n 4, an air compressor for operating the vehicle brakes 2, and a charger of battery coupled to an electric accumulator supplying energy to a low voltage circuit (72 V) of the vehicle 2.

The set of electric energy sources, ie, the electric generator 6, the battery pack 8 and the supercapacitor block 10, and the consumers of electrical energy, that is, traction motors 4 and 12, are connected together via a high voltage bus 14, otherwise called power bus.

The electric power sources 6, 8, 10 are further connected to a CAN bus 16, otherwise called a control bus, to which a calculator 18 is connected.

The main function of the computer 18 is to distribute optimally the energy supplied from the available energy sources to the consumers and the energy supplied by the generator 6 to the battery pack 8 and the supercapacitor block 10.

Preferably, the computer 18 operates so that:

the generator 6 supplies the energy corresponding to the average regime required for the mission, that is to say the continuous component of the energy;

- The battery pack 8 provides the energy relative to the solicitations whose duration is long in addition to the generator 6, that is to say the energy 15 at low frequencies; and

the block of supercapacitors 10 supplies the energy corresponding to the power demands of short durations and whose activation is very fast, that is to say the energy at high frequencies.

In the vehicle 2, the generator 6 is not able to regulate its output current. The current delivered by the generator 6 is therefore directly dependent on the voltage of the voltage bus 14.

The present invention aims to regulate the voltage of the voltage bus 14 and thereby control the current produced by the generator 6.

FIG. 2 illustrates the use of the supercapacitor block 10 as a means of regulating the voltage bus 14 in accordance with the invention. This figure only shows the generator 6, the voltage bus 14 and the block of supercapacitors 10.

In FIG. 2, _ge means the current delivered by the generator 6, which is the current delivered or absorbed by the block of supercapacitors 10 and 1 _x denotes the current delivered and / or consumed by the other energy sources and / or consumers connected to the voltage bus 14. According to the law of the nodes, the sum of the currents _lge , l _SC a _P and l _x is null. In addition, the computer 18 controls the electrical sources in order to have the _ge = - l _x . Thus, the average current _sca p delivered by the block of supercapacitors 10 must remain zero over a relatively long time, of the order of a few minutes, in order to avoid the complete charge of the supercapacitors or, conversely, their complete discharge. The objective is to maintain the charge of the supercapacitors at a constant average level, equal to 50% of the maximum load, for example, to allow them to absorb the energy of overvoltages or to restore energy during brownouts. .

The choice of the voltage of the bus 14, denoted by Ui ₄ , is therefore directly related to the current that is desired at the output of the generator 6.

Generator 6 produces a voltage comparable to that of a three-phase alternating network industrial type 20. This voltage is supplied to the voltage bus 14 through a rectifier 22, in particular unmanned, simple to implement.

According to a preferred embodiment, the generator set 6 delivers an industrial-type AC voltage of 400 volts between phases so that the voltage of the bus 14 corresponds to the 400 V rectified double-wave voltage, ie 540 V DC at rated power, equal to 230kW in our example.

Thus, the bus voltage 14 is regulated by the supercapacitor block

10 to be preferably between 520 V and 590 V and ideally equal to 540 V at rated power.

In addition, the block of supercapacitors 1 0 is connected to the bus 1 4 through a static converter 24 for controlling the charging current 25 and discharging supercapacitors. This static converter 24 also makes it possible to impose, by its operation as a step-down or step-up chopper, the voltage on the bus 14 according to a set voltage U _C ons assigned to it.

According to a preferred embodiment of the invention, the means for regulating the voltage of the bus 14 comprise a correction device implementing a first proportional integral corrector.

This correction device 30 is illustrated in FIG. The correction device 30 comprises means for comparing 32 a current setpoint Ι _∞η8 and the current I _ge measured at the output of the generator 6, using a current sensor for example.

The cons ig not currently informed of the output dug rou pe ns generating the _CO 5 is previously set according to the desired current output from the generator 6 and needed to satisfy the needs of the m ission to perform, for traction, the supply auxiliaries and charging batteries, for example.

The comparison means 32 output an error value En _ge which is supplied to the first integral proportional corrector 34.

The first integral proportional corrector 34 conducts the main source of electrical energy, that is to say the generator 6 in the described embodiment, to its desired operating point in a few seconds, especially in 10 seconds. maximum.

The result obtained at the output of the first integral proportional corrector 34 is then limited in its amplitude through a clipper 36.

The result then obtained at the output of the correction device 30 is the instruction U _C ons of the voltage of the bus 14 which must be supplied to the block of supercapacitors 10.

L a t i n d i n i n i n i n i n i n i n i n i n i n i n i n i n i n i n i n i n i n i o n 20 supercapacitors 10.

According to a preferred embodiment of the invention, the means for regulating the voltage of the bus 14 also comprise a device for controlling the charge level of the block of supercapacitors 10 in order to guarantee that the block of supercapacitors 10 can at any time supply or absorb current of the voltage bus 14.

FIG. 4 illustrates this control device 40.

The control device 40 comprises means 42 for comparing a charge level setpoint of the supercapacitor block SOC.sub.1 and the charge level of the supercapacitor block SOC ₂ measured from a measurement of voltage across the terminal block. supercapacitors 10, the charge Q and the energy quantity E of a supercapacitor being related to the voltage U at its terminals and to the capacitance C according to the relations Q = CU and E = 1 / 2CU ² The charge level setpoint SOC1 supercapacitor block is previously defined so that the block of supercapacitors 10 can at any time supply or absorb current of the voltage bus 14. This charge level setpoint is for example set at 50% of the maximum load expected in the block of supercapacitors 10.

The comparison means 42 output an Er _S oc error value, which is supplied to a second integral proportional corrector 44.

The second integral proportional corrector 44 is chosen very slowly in order to allow the load or the discharge of the supercapacitor block 10 to drift slowly without reaching the complete charge or the complete discharge and without causing sudden variations in the equilibrium of the voltage bus 14 under trouble creating unwanted surges.

The amount of stored electricity Q in a supercapacitor responds to the physical law described by the relation Q = I x t where I is the current that charges or discharges the supercapacitor, and t is the duration of the charge or discharge. Given the value of the capacitance C equal to 25F of the block of supercapacitors 10 in our example, the current can reach a few tens of amps and the time can be several seconds.

The result obtained at the output of the second integral proportional corrector 44 is then limited in amplitude through a limiter 46.

The result then obtained at the output of the control device 40 is a current of imbalance _{of the} -

The current l _{of the} is added to the previous equation of the law of the nodes which becomes thus:

Ige ~ * ~ Ιχ ~ * ~ I scap ~ * ~ Ides ^- 0.

This equation is used by the computer 18 which controls the electric sources in order to have:

It should be noted that the imbalance current I _of s is neither consumed nor produced by any block since it is introduced only in calculations. This small imbalance of current has the effect of raising or lowering the bus voltage 14. Since the voltage of the bus 14 is regulated by the supercapacitors block 1 0 co mmed é critc i above, the supercapacitors block 10 supplies or absorbs this current imbalance _l - Thus, the block Supercapacitors 10 will charge or discharge depending on the sign of the Ides unbalance current. The regulation of the bus voltage 14 using the block of supercapacitors 10 and the correction and control devices of FIGS. no return of energy absorbed during overvoltages during undervoltage. In addition, the use of supercapacitors 10 is very stabilizing because it generates very little ripple or resonance.

Of course, other embodiments may be envisaged. By way of example, the capacitor block described comprises 200 5000F / 2.5 V supercapacitors, the total resulting capacitance being 25F.

It can be provided that the supercapacitor block comprises several modules connected in parallel with 200 5000F / 2.5V supercapacitors each.

By implementing 4 modules, for example, the total resulting capacity is then 100 F.

It is also possible to use supercapacitors of different capacity, for example 2600F or 9000F.

The object of the invention is a vehicle. More restrictively, such an object is a land vehicle, including a eng eng rail or automotive ve ve icule.

25

Claims

A vehicle (2) comprising a plurality of on-board electrical power sources (6,8, 1 0) connected by a voltage bus (1 4), said vehicle further comprising means for regulating the bus voltage (1 4), the regulating means comprise at least one supercapacitor (1 0) connected to the voltage bus (1 4), said supercapacitor (1 0) forming part of the plurality of sources, the regulating means comprising a device correction device (30) for the bus voltage (1 4), characterized in that the correction device (30) comprises a first integral proportional corrector (34).

2. Vehicle (2) according to claim 1, wherein the regulating means comprise means (40) for controlling the charge level of the supercapacitor (1 0).

3. Vehicle (2) according to claim 2, wherein the control means (40) comprises a second proportional integral corrector (44).

4. Vehicle (2) according to any one of the preceding claims, wherein the plurality of on-board electrical energy sources comprises a generator (6).

5. Vehicle (2) according to any one of the preceding claims, characterized in that it is a railway vehicle.

6. A method of regulating the voltage of a voltage bus (1 4) connecting a plurality of sources (6, 8, 1 0) of electrical energy on board a vehicle (2), said plurality of sources comprising at least one less a supercapacitor (1 0) and a generator (6), characterized in that it comprises the steps of:

25 - challenge of a power consumption (l _con s) at the output of the generator (6);

- measurement of the current ( _lge ) at the output of the generator (6);

- comparison of the current setpoint (l _con s) and the measured current ( _lge ) to obtain a current error value (in _ge );

30 - application of a first integral proportional corrector (34) to the current error value (in _ge ) to obtain a bus voltage setpoint (U _C ons); and

supply of the voltage setpoint (U _C ons) to the supercapacitor (1 0).

The method of claim 6, further comprising the steps of:

- Definition of a charge level setpoint (SOd) of the supercapacitor (10);

measuring the charge level (SOC ₂ ) of the supercapacitor (10);

comparing the charge level setpoint (SOd) and the measured charge level (SOC ₂ ) to obtain a charge level error value (Er _S oc) of the supercapacitor (10);

- applying a second integral proportional corrector (44) to the load level error value (Er _S oc) of the supercapacitor (10) to obtain an unbalance current (I _of s); and

- charge or discharge of the supercapacitor (10) according to the sign of the imbalance current (l _of s) -

8. Method according to any one of claims 6 or 7, wherein the vehicle (2) is a railway vehicle.