FR2970442A1 - VOLTAGE REGULATION IN A HYBRID RAIL VEHICLE - Google Patents

Abstract

Railway engine (2) comprising a plurality of on-board electrical power sources (6, 8, 10, 10) connected by a voltage bus (14), said apparatus further comprising bus voltage regulation means (14) , characterized in that the regulating means comprise at least one supercapacitor (10) connected to the voltage bus (14), said supercapacitor (10) being part of the plurality of sources.

Description

The present invention relates to a rail vehicle comprising a plurality of on-board electrical power sources and connected by a voltage bus. It also relates to a method for 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 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, the hybridization by local electricity storage allows the smoothing of the consumption on the catenary and a better quality of the distribution network of the energy. 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 comprise a generator and / or a fuel cell and / or an external power 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. Outside this voltage range, the operation and safety of 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 missions, such as yard and local and urban service missions. During these uses, overvoltages and undervoltages may occur during the connection and / or disconnection of at least one consumer while the power sources supply the voltage bus called transient operating the machine. It is important to limit the occurrence of these overvoltages and undervoltage.

A conventional solution to limit overvoltages 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. For this purpose, the invention relates first of all to a rail vehicle comprising a plurality of on-board electrical power sources connected by a voltage bus, said machine further comprising means for regulating the bus voltage, characterized in that the regulating means comprise at least one supercapacitor connected to the voltage bus, said supercapacitor being part 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. overvoltage limiting phases. 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 charge and discharge cycle time of a supercapacitor makes it particularly suitable for regulating the voltage on the bus. Advantageously, the regulation means comprise a device for correcting the bus voltage.

This correction device comprises in particular 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 that satisfies the achievement of the balance of currents entering and leaving the bus since the sum of these currents must be zero (law of the nodes or Kirchhoff's law). ). The bus voltage setpoint thus determined is assigned to the supercapacitor. Advantageously, the regulating means also comprise means for controlling the charge level of the supercapacitor. 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 20 reacts slowly, its action taking place over periods ranging from the second to several tens of seconds. Advantageously, the plurality of on-board electrical energy sources comprises a generator. This generating set, comprising a diesel engine, produces the energy necessary for the traction and supply of auxiliaries of the railway vehicle. 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 power sources. electrical energy 30 embedded in a railway 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 integral proportional corrector to the current error value to obtain a bus voltage setpoint; and - supply of the voltage setpoint to the supercapacitor. Advantageously, this method comprises the steps of: -defining a charge level setpoint 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. Embodiments of the invention will now be described more specifically, but not limitatively, with reference to the accompanying drawings, in which: FIG. 1 is a diagram illustrating the structure of a railway vehicle according to an embodiment of FIG. the invention; FIG. 2 is a diagram illustrating the means for regulating the voltage of the voltage bus of the machine 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. Figure 1 illustrates a rail vehicle 2 hybrid type. The machine 2 is provided with traction motors 4 for driving the machine. 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 craft 2. In the example of Figure 1, these sources comprise a generator 1 o 6, a battery pack 8 and a block of supercapacitors 10. The generator 6 includes a diesel heat 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 includes 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 comprises a plurality of supercapacitors, for example 200 5000 F / 2.5V supercapacitors connected in series. The total capacity of the block of supercapacitors is then equal, in this example to 25 F. The machine 2 also comprises a set of auxiliaries 12 which comprise in particular a fan of the traction motors 4, an air compressor for operation. brakes of the machine 2, and a battery charger coupled to an electric accumulator supplying energy to a low voltage circuit (72 V) of the machine 2. All sources of electrical energy, that is, that is, the generator set 6, the battery pack 8 and the supercapacitor pack 10, and electric power consumers, i.e., the traction motors 4 and the

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

Preferably, the calculator 18 operates such that: the generator 6 supplies the energy corresponding to the average regime required for the mission, that is to say the DC 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 at low frequencies; and the block of supercapacitors supplies the energy corresponding to the power demands of short durations and whose activation is very rapid, that is to say the energy at high frequencies. In the machine 2, the generator 6 can not 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 thus to control the current produced by the generator set 6. FIG. illustrates the use of the supercapacitor block 10 as a regulation means of the voltage bus 14, according to the invention. This figure only shows the generator 6, the voltage bus 14 and the block of supercapacitors 10. In FIG. 2, Ige denotes the current delivered by the generator set 6, Iscap denotes the current delivered or absorbed by the generator. block of supercapacitors 10 and 1x represents 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 Igef Iscap and lx is zero .

In addition, the computer 18 controls the electrical sources in order to have Ige = - IX. Thus, the average Iscap current 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 500/0 of the maximum load for example, to allow them to absorb the energy of the overvoltages or to restore energy during the drops of voltage. The choice of the bus voltage 14, noted U14, is therefore directly related to the 1 o current that is desired at the output of the generator 6. The generator 6 produces a voltage comparable to that of a three-phase alternating network of the 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 voltage of the bus 14 is regulated by the supercapacitor block 10 to be preferably between 520 V and 590 V and ideally equal to 540 V at the nominal power. In addition, the block of supercapacitors 10 is connected to the bus 14 through a static converter 24 for controlling the charging current 25 and discharging the supercapacitors. This static converter 24 also makes it possible to impose, by its operation as a step-down or step-up chopper, the voltage at the bus 14 according to a voltage setpoint 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 integral proportional corrector. This correction device 30 is illustrated in FIG.

The correction device 30 comprises means 32 for comparing a current setpoint Ions and the current Ige measured at the output of the generator 6, using a current sensor for example. The current setpoint at the output of the Ions generator set is previously defined according to the desired output current of the generator 6 and necessary to meet the needs of the mission to be performed, for traction, auxiliary power supply and battery charging, for example. The comparison means 32 output an error value Er, 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, in particular 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 cutter 36. The result then obtained at the output of the correction device 30 is the set Usons of the bus voltage 14 which must be supplied to the block The voltage of the bus 14 is thus imposed thanks to the block of 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. supercapacitors 10 to ensure that the supercapacitor block 10 can at any time supply or absorb current from the voltage bus 14. FIG. 4 illustrates this control device 40. The control device 40 comprises comparison means 42. a charge level setpoint of the supercapacitor block SOC1 and the charge level of the supercapacitor block SOC2 measured from a second voltage supply across the supercapacitor block 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 / 2CU2

The charge level setpoint of the supercapacitor block SOC1 is previously defined so that the block of supercapacitors 10 can at any time supply or absorb current from the voltage bus 14. This charge level setpoint is for example set at 500/0. of the maximum load provided in the block of supercapacitors 10. The comparison means 42 output an Ersoc error value, which is supplied to a second integral proportional corrector 44. The second integral proportional corrector 44 is chosen very slow in order to let the load or the discharge of the block of supercapacitors 10 drift slowly without reaching the complete charge or the complete discharge and without causing sudden variations in the equilibrium of the voltage bus 14 at the risk of creating undesirable overvoltages. The amount of stored electricity Q in a supercapacitor responds to the physical law described by the relation Q = 1 × t where 1 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 cutter 46. The result then obtained at the output of the control device 40 is an imbalance current Ides. The current Ides is added to the previous equation of the law of the nodes which thus becomes: Ige + lx + 1 scap + Ides = O.

This equation is used by the computer 18 which controls the electrical sources in order to have: Ige = - lx-Ides- It should be noted that the imbalance current Ides is not consumed or produced by any block since it is introduced only in calculations. This small power imbalance causes the 2970442 io to go up or down.

As the bus voltage 14 is regulated by the supercapacitor block 10 as described above, the supercapacitor block 10 supplies or absorbs this imbalance current Ides. Thus, the block of supercapacitors 10 will charge or discharge depending on the sign of the imbalance current Ides. The regulation of the voltage of the bus 14 using the block of supercapacitors 10 and the correction and control devices of FIGS. 3 and 4 makes it possible to restore the energy absorbed during the overvoltages during under-voltages. 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 of 200 supercapacitors 5000F / 2.5 V 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.20.

Claims (8)

REVENDICATIONS1. Railway engine (2) comprising a plurality of on-board electrical power sources (6, 8, 10, 10) connected by a voltage bus (14), said apparatus further comprising bus voltage regulation means (14) , characterized in that the regulating means comprise at least one supercapacitor (10) connected to the voltage bus (14), said supercapacitor (10) being part of the plurality of sources. 2. Machine (2) according to claim 1, wherein the regulating means comprise a device (30) for correcting the voltage of the bus (14). zo 3. Machine (2) according to claim 2, wherein the correction device (30) comprises a first proportional integral corrector (34). 4. Engine (2) according to any one of claims 1 to 4, wherein the regulating means comprise control means (40) of the charge level of the supercapacitor (10). 15 5. Machine (2) according to claim 5, wherein the control means (40) comprise a second proportional integral corrector (44). 6. Engine (2) according to any one of the preceding claims, wherein the plurality of onboard electrical power sources comprises a generator (6). 20 A method of regulating the voltage of a voltage bus (14) connecting a plurality of electric power sources (6, 8, 10) on board a railway vehicle (2), said plurality of sources comprising at least one supercapacitor (10) and a generator (6), characterized in that it comprises the steps of: - defining a current setpoint (Donations) at the output of the generator (6); - measurement of the current (Ige) at the output of the generator (6); - comparison of the current setpoint (I. $) and the measured current (Ige) to obtain a current error value (Enge); - applying a first integral proportional corrector (34) to the current error value (Enge) to obtain a bus voltage setpoint (U. $); and - supplying the voltage setpoint (U. $) to the supercapacitor (10). The method of claim 7, further comprising the steps of: - defining a charge level setpoint (SOC1) of the supercapacitor (10); measurement of the charge level (SOC2) of the supercapacitor (10); s - comparing the charge level setpoint (SOC1) and the measured charge level (SOC2) to obtain a charge level error value (Ersoc) of the supercapacitor (10); applying a second integral proportional corrector (44) to the charge level error value (Ersoc) of the supercapacitor (10) for obtaining an unbalance current (Ides); and charging or discharging the supercapacitor (10) according to the sign of the imbalance current (Ides).