WO2024075006A1

WO2024075006A1 - An integrated control for electric traction railway vehicles

Info

Publication number: WO2024075006A1
Application number: PCT/IB2023/059912
Authority: WO
Inventors: Antonio Nitti; Vito LUCARELLI; Paolo Roberto MASSENIO
Original assignee: Tesmec Rail S.R.L.
Priority date: 2022-10-05
Filing date: 2023-10-03
Publication date: 2024-04-11

Abstract

An integrated control for electric traction railway vehicles particularly suitable for a speed, antislip and power limitation control for a railway vehicle comprising at least one traction system provided with an electric motor which can be operated by an electronic drive system that performs a torque or current control, characterised by comprising a control architecture configured to determine: a) based on signals and/or data and/or commands received through a communication protocol, a difference between a limit power transferrable to/receivable from a power source and an electric power requested by/transferred to said power source, processing said difference with a PID (Proportional, Integral, Derivative) control logic to supply a signal comprised within minimum and maximum limits of a torque or current reference that can be supplied to the electronic drive unit of the electric motor of the railway vehicle; b) based on the signals and/or data and/or commands received, a torque or current signal to be implemented in case a slipping/skidding event is detected, with said signal comprised between the minimum and maximum limits of a torque or current reference that can be supplied to the electronic drive unit of the electric motor; c) based on the signals and/or data and/or commands received, a difference between the desired speed of the vehicle and the current speed of the same vehicle, with said difference processed with PID control logic for the generation of a torque or current signal to supply to the electronic drive unit of the electric motor, said torque or current signal limited dynamically in accordance with the torque or current signals determined according to the logics of points a) and b).

Description

AN INTEGRATED CONTROL FOR ELECTRIC TRACTION RAILWAY VEHICLES

DESCRIPTION

The present invention relates to an integrated control for electric traction railway vehicles .

More in particular, the present invention refers to an integrated speed, anti-slip and power limitation control in an electric traction railway vehicle .

As is known, in the railway handling sector and, speci fically, in the traction sector of railway vehicles comprising one or more axles , speed control is implemented by means of one or more electric drives connected to the motorised axles and with the electric energy coming from an overhead contact line ( technically called "catenary" ) that is converted into mechanical driving energy; however, in case of such overhead line being absent , the electric energy is supplied by one or more combustion generators and/or by at least one battery pack .

An example of a conventional architecture of the elements of an electric traction railway vehicle and of the related speed control is schematised in Fig . 1 in the form of a block diagram .

With reference to the aforementioned block diagram, the electric energy for traction and for supplying the auxiliary loads of the railway vehicle is supplied, through a direct current line 10 , by a block 12 defined by a generator set and/or by a battery pack and/or by an overhead line ; in case of supply by alternating current overhead line a conversion stage from alternating current to direct current is used .

Downstream of the block 12 , there are provided an inverter 13 , with the function of converting the voltage from direct to alternating to supply the alternating current loads 13 ' ( such as compressors , operating machines and the like ) , a direct current convertor 14 with the function of supplying direct current loads 14 ' of the 24 Volt/ 72 Volt type, and a chopper device 15 with the function of closing the direct current line on a braking rheostat 16 in order to dissipate the excess energy generated during the electric braking steps of traction motors .

The solutions of conventional type can have configurations that include several inverters , converters and braking rheostats , with the traction taking place by means of "n" motorised axles ; in this regard, per the i-th motorised axle , an i-th torque-controlled inverter 17 is connected to an 1- th traction motor which, in turn, is connected to the i-th axle 19 by means of 1-th transmission members .

Control of the traction inverters takes place by means of a vector control logic 21 that defines the gate signals of the transistors of the inverter based on the current and speed/position feedback of the electric motor and voltage on the direct current line .

In this control the desired torque reference is assumed as input of the vector control , with this assumption contemplating the use both of synchronous and asynchronous motors , providing they are equipped with a suitable control unit commandable with the desired torque value by means of a fieldbus connection; based on the angular velocity measurements of the electric motors (SpdMi with i=l , ..., n) , of the desired speed of the vehicle (SpdRef) and of the current speed of the vehicle (SpdVehicle) , the vehicle control unit (VCU) 22 regulates the torque references for each inverter (TorqueRefi with i=l , ..., n) in order to implement the speed control of the vehicle .

Typically, the control logic o f the VCU 22 is implemented considering the same number of control loops as the number of the motorised axles . The logic of the typical control loop of the i-th axle is schematised in Fig . 2 .

With reference to this figure , based on an error between a reference speed ( SpdRef ) measured in metres per second and the speed of the i-th axle ( SpdWi ) , also measured in metres per second, a PID ( Proportional , Integral , Derivative ) control logic 23 and with said control logic equipped with an antiwindup action, regulates the torque value to bring the error to zero providing an output torque signal ( TorqueCri ) , with the value of the speed of the axle SpdWi that is calculated with the formula :

wherein r± is the radius of the wheels of the axle and n± is the transmission ratio .

With reference to Fig . 2 , saturation of the PID controller 23 occurs when the value calculated thereby exceeds a limit value calculated by the torque-speed map of the motor 24 that is interrogated with the absolute value of the angular velocity of the electric motor ( \ SpdMi \ ) to obtain the corresponding maximum torque value that can be delivered by the motor ( Tmaxi) .

Based on the maximum power that can be delivered by the motor ( Pmeci ) the torque signal ( TorqueCr±) is corrected by means of the saturation block 25 the limits of which are obtained through the minimum value between Plimi/ | SpdM± | and Tmax, with Plimi=PmeCi .

The output of the saturation block 25 ( TorqueCri' ) can be manipulated by an anti-slip and/or anti-skid control logic 26 that performs a regulation of the torque , for example , based on the speed of the vehicle ( SpdVehicle ) and on the speed of the axle ( SpdWi ) .

However, the conventional control methods of the type illustrated above have some important drawbacks linked to the fact that when the power supply source is represented by a generator set and/or by a battery pack, the power is dimensioned based on the nominal power values required by the alternating current and direct current loads and by the nominal power required by the traction motors and, with regard to the alternating current and direct current loads , the use factor and contemporaneity factor can be di f ficult to calculate exactly and precisely, tending to consider a contemporary use of all the loads at their nominal power and this , in the useful li fe of the railway vehicle occurs somewhat sporadically .

This over-dimensioning of the power of the source results in further drawbacks represented by an increase in the weights , in the overall dimensions and in the costs of the devices and, accordingly, also results in a reduction of ef ficiency and an increase in emissions .

In fact , for example , in the case of a source defined by a generator set that operates for most of the time at an operating point that di f fers from its nominal value , its ef ficiency decreases with a resulting increase in fuel consumption, in lubricant consumption and in the energy dissipated on its alternator .

Also , in the case of a source cons isting of a battery pack, over-dimensioning of the source of the power results in a considerable increase in the weights and, accordingly, in the energy used by traction, dynamic performance being equal .

In order to solve the aforesaid drawbacks , by means of the control logic described above with reference to Fig . 2 , considering a limit power value Plimi that adapts based on the power available instant by instant and, therefore , considering n traction motors with the same nominal characteristics , in each instant the value Plimi is calculated as :

wherein Ps is the nominal power delivered by the source , Nca is the number of alternating current inverter/ load lines connected to the direct current line , Ncc is the number of direct current converter/ load lines connected to the direct current line , Peak (with k=l , ..., Nca ) is the power absorbed by each alternating current load line , Peck (with k=l , ..., Ncc ) is the power absorbed by each direct current load line and g is the performance of the inverter-motor system .

However, this logic also has some important drawbacks linked to the fact that it requires the use of devices to measure the instantaneous power absorbed installed on each direct current and alternating current load line , suitably redundant to be able to ensure a high reliability of the traction function, with an increase in the overall dimensions , in the costs and in the construction and functional complexity .

The obj ect of the present invention is to overcome the drawbacks indicated above .

More in particular, the obj ect of the present invention is to provide an integrated control for electric traction railway vehicles suitable to ensure optimised flexibility in the choice and in the dimensioning of the energy source when it consists of a generator set and/or of a battery pack . Even more in particular, the obj ect of the present invention is to provide an integrated control for electric traction railway vehicles for vehicles in which the direct current and alternating current loads are characterised by powers variable in a wide range and for which it is di f ficult to precisely establish a contemporaneity and use factor .

A further obj ect of the present invention is to provide an integrated control applicable to any electric traction railway vehicle and, in particular, applicable to railway vehicles whose direct current and alternating current loads are characterised by powers variable in a time range as a function of the operating conditions ( for example , railway vehicles that comprise diagnostic systems and/or operating machines such as cranes or li fting platforms or ice breaking pantographs or similar, used in infrastructure maintenance operations ) .

A further obj ect of the present invention is to provide an integrated control applicable both with synchronous motors and with asynchronous motors .

A further obj ect of the present invention is to provide users with an integrated control for electric traction railway vehicles suitable to ensure a long useful li fe and high reliability over time and, moreover, such that can be implemented easily and inexpensively .

These and other ob ects are achieved by the apparatus of the invention having the features of claim 1 .

According to the invention, there is provided an integrated control for electric traction railway vehicles particularly suitable for a speed, antislip and power limitation control for a railway vehicle comprising at least one traction system provided with an electric motor which can be operated by an electronic drive system that performs a torque or current control , characterised by comprising a control architecture configured to determine : a ) based on signals and/or data and/or commands received through a communication protocol , a di f ference between a limit power trans ferrable to/receivable from an energy source and an electric power requested by/trans f erred to said energy source , processing said di f ference with a PID ( Proportional , Integral , Derivative ) control logic to supply a signal comprised within minimum and maximum limits of a torque or current reference that can be supplied to the electronic drive unit of the electric motor of the railway vehicle , b ) based on the signals and/or data and/or commands received, a torque or current signal to be implemented in case a slipping/ skidding event is detected, with said signal comprised between the minimum and maximum limits of the torque or current reference that can be supplied to the electronic drive unit of the electric motor, c ) based on the signals and/or data and/or commands received, a di f ference between the desired speed of the vehicle and the current speed of the same vehicle , with said di f ference processed with PID control logic for the generation of a torque or current signal to supply to the electronic drive unit of the electric motor, with said torque or current signal limited dynamically in accordance with the torque or current signals determined according to the logics of points a ) and b ) .

Advantageous embodiments of the invention are described in the dependent claims .

The construction and functional features of the integrated control for electric traction railway vehicles of the present invention can be better understood from the detailed description below in which reference will be made to the accompanying drawings/diagrams , which illustrate an embodiment thereof provided purely by way of non-limiting example and wherein :

Fig . 1 illustrates , in the form of block diagram, the typical architecture of the elements of an electric traction railway vehicle and the related speed control , highlighting the main electrical and mechanical connections and those relating to the exchange of information via fieldbus ;

Fig . 2 schematically represents a speed control of type known in the state of the art of an electric traction railway vehicle ;

Fig . 3 schematically illustrates the integrated control logic for electric traction railway vehicles of the present invention .

The integrated control for electric traction railway vehicles of the present invention provides an electronic unit functional to the control of an electric traction system of a railway vehicle comprising an electric motor which can be operated by an electronic drive system that performs a torque or current control and which is configured to receive , by means of any communication protocol , a torque or current reference to be implemented . The electronic control unit is configured to receive signals and/or data and/or commands useful for the determination of the operating conditions of the railway vehicle , and, in particular, of the electric power requested by/trans f erred to the energy source , of an electric power limit trans ferrable to/receivable from the source , of the speed of the vehicle , of the speed of the wheels connected to the traction system, and of the desired speed of the vehicle .

The electronic control unit is configured to determine , based on signals and/or data and/or commands received, the di f ference between the limit power trans ferrable to/receivable from the energy source and the electric power requested by/trans f erred to the energy source , and to process this di f ference with a PID ( Proportional , Integral , Derivative ) control logic in order to supply a signal comprised within the minimum and maximum limits of the torque or current reference that can be supplied to the electronic drive unit of the electric motor . Moreover, the electronic control unit is configured to determine , based on the signals and/or data and/or commands received, a torque or current signal to be implemented in case a slipping/ skidding event is detected, with this signal comprised between the minimum and maximum limits of the torque or current reference that can be supplied to the electronic drive unit of the electric motor .

Further, said electronic control unit is configured to determine , based on the signals and/or data and/or commands received, the di f ference between the desired speed of the vehicle and the current speed of the vehicle and to process said di f ference with a PID control logic in order to supply a torque or current signal to the electronic drive unit of the electric motor, with this torque or current signal comprised between the a maximum value corresponding to the minimum value between the signals calculated according to the logics described above and a minimum value equal to the aforesaid maximum value multiplied by "- 1" .

With reference to the aforesaid figures , the integrated control for electric traction railway vehicles of the present invention is integrated in an architecture of the type illustrated in Fig . 1 and is defined by the block 22 ( indicated with VCU - Vehicle Control Unit ) and illustrated in the detail in Fig. 3.

Said integrated control comprises a control architecture comprising a PID (Proportional, Integral, Derivative) power controller 50, a PID speed controller 52, an anti-slip/anti-skid control 54 coacting with one another as described in more detail below.

The control of the invention provides for integration of the speed control, of the power control and of the anti-slip control in a single functional unit.

For each motorised axle of the railway vehicle (Axlei with i= l,...,n as in Fig. 1) , the control provides a PID speed controller that directly supplies a reference torque signal TorqueRefi based on the error measured between SpdRef and SpdWi.

The power and anti-slip control logics are both positioned upstream of the PID speed controller 52, as schematised in Fig. 3.

The PID power controller 50 is integrated with an anti-wind-up logic and supplies a saturated signal between a value 0 and a value Tmaxi based on a difference between a limit power 51 of the source (indicated as PowerLimit in Fig. 3) and an absolute value of the overall power 51' (indicated with PowerAct) which is requested both by the alternating current loads and by the direct current loads and also by the traction motors (reference is made to the absolute value of the overall power in order to implement a power limitation also during electric braking, in which the value of the overall power ( PowerAct) could be negative (for example, when the power during regeneration of the motors exceeds the power absorbed by the alternating current and direct current loads) .

The output of the PID power controller 50 is a torque signal TorquePwi (indicated with 53 in Fig. 3) which increases up to a limit value Tmaxi until the absolute value of the overall power (PowerAct) is below the value of the limit power of the source ( PowerLimi t) ; conversely, in the situation in which the absolute value of the overall power (PowerAct) were to become greater than the value of the limit power 51 ( PowerLimi t) , the PID power controller 50 will decrease the output TorquePwi until reaching a condition of balance, i.e., until reaching an equality between the absolute value of the overall power 51' (PowerAct) and the value of the limit power 51 ( PowerLimi t) .

The overall power signal 51' (PowerAct) is easily obtainable by interrogating, via fieldbus (not depicted as already known) , the control unit of the generator set and/or the control unit of the battery pack (not depicted) .

Moreover, if the operating conditions of the vehicle require this, the value of the limit power of the source 51 ( PowerLimi t) can be modified in real time (for example, when the source consists of a battery pack, the value of the limit power of the source 51 ( PowerLimi t) changes both based on its state of charge and based on its state of delivery/ regeneration) .

An anti-slip/anti-skid control procedure, indicated by the block 54 in Fig. 3, supplies a torque signal in case a slipping/skidding event is detected on the wheels of the i-th axle.

Fig. 3 illustrates, by way of example, a control strategy functional to a correction of the reference torque supplied by the FID speed controller 52 (the torque TorqueRefi 55) , based on the speed of the wheels of the axle (SpdWi 56) and on the current speed of the vehicle ( SpdVehicle 57) .

If the anti-slip/anti-skid controller also provides a negative output torque, the absolute value thereof is calculated, supplying the signal TorqueAsi (as indicated by the reference number 58 in Fig . 3 ) .

The PID speed controller 52 provided with anti windup logic regulates the reference torque TorqueRefi ( indicated with the reference number 55 ) sent to the control electronics of the electric motor via fieldbus ( as schematised by the dashed lines in Fig . 1 ) based on the error between the speed desired and defined by the operator SpdRef ( indicated by the reference number 60 ) and the current speed of the wheels of the axle , SpdWi ( indicated with the reference number 56 ) .

The saturation limits of the PID speed controller 52 are modi fied dynamically as a function of the minimum torque value between TorqueAsi 58 and TorquePwi 53 and, in particular, the upper limit of the saturation of the PID ( of the speed controller 52 ) coincides with this minimum, while the lower limit coincides with the upper limit multiplied by "- 1" .

The control logic described above by way of example provides a PID power control 50 and an anti- slip/anti-skid control 54 which are arranged upstream of the PID speed control 52 with the operating limits modi fied dynamically in accordance with a minimum value between the outputs of the PID power control and of the anti-slip/anti-skid control .

The control according to the invention is independent of the particular anti wind-up technique and the anti-slip/anti-skid technique used, due to the fact that , i f present and functioning correctly, they do not influence what has been described with reference to the control logic .

In addition to this , the control logic described is independent of the techniques and/or methods chosen for the purposes of calculating the speed of the wheels of the axle ( SpdWi) , the speed of the vehicle ( SpdVehi cl e) and the speed error input to the controller 52 .

Fig . 3 , which illustrates the control logic according to the invention also illustrates an example of error obtained considering the di f ference between the speed desired for the vehicle and the speed of the wheels of the axle considered ( alternatively, it is also possible to consider an error calculated as di f ference between the desired speed of the vehicle and the current speed of the vehicle that is estimated or calculated using appropriate known methods ) .

The control described above is , as indicated previously, applied to a railway vehicle such as a train that comprises a plurality of traction vehicles , at least one of which i s provided with an electric motor which can be operated by an electronic drive system that performs a torque or current control and which is configured to be able to receive the torque or current reference to be implemented ( through any communication protocol , not described) , with said control comprising the described control unit configured to command at least one traction system .

Moreover, the electronic drive system for traction vehicles performs a torque or current control configured to receive , through a known communication protocol , the torque or current reference to be implemented .

As can be understood from the above , the advantages that the integrated control for electric traction railway vehicles of the invention achieves are evident .

The integrated control for electric traction railway vehicles of the present invention advantageously allows optimised flexibility to be guaranteed in the choice and in the dimensioning of the energy source when it consists of a generator set and/or of a battery pack and, in particular, when the direct current and alternating current loads are characterised by variable powers in a wide range ; as an advantageous consequence , this allows optimisation of the ef ficiency and of the overall performance of the railway vehicle without penalising reliability and with a reduction in costs , overall dimensions and emissions .

Also advantageous is the fact that the control of the invention can be applied to any railway vehicle of the type with electric traction and, in particular, it can be applied to railway vehicles whose direct current and alternating current loads have powers variable in a time range as a function of the speci fic operating conditions .

A further advantage is represented by the fact that the control of the invention makes it possible not to use power measuring devices on each line , as it uses only the information relating to the power that is delivered from the source instant by instant interrogating, by means of the fieldbus , the control unit of the generator set and the control unit for managing the battery with a consequent reduction in the costs .

A further advantage of the control of the invention is represented by the fact that there is no modi fication to the dynamics of the PID speed controller, but only a limitation of the work area when the overall power requested from the source exceeds a predetermined limit represented, for example , by the nominal power value .

A further advantage of the control of the invention is represented by the fact that , in case of slipping/ skidding, the signal TorqueRefi is not brusquely corrected by the anti-slip/anti-skid controller, but is corrected by the PID speed controller based on the limit updated by the anti- slip/anti-skid control and, in this way, sudden variations of torque are avoided, resulting in an improved travelling comfort ; this last advantage is also achieved i f the dimensioning of the source takes place considering the maximum contemporaneity and use factor, still making the proposed approach more advantageous with respect to the approach known in the state of the art and schematised in Fig . 2 .

Also advantageous is the fact that , i f the traction inverter were commandable in terms of percentage of torque deliverable with respect to the maximum value , it would not be necessary to know the torquespeed map of the motor, but it would suf fice to set a limh of the PID power controller equal to 100 and this gives a greater flexibility and ease of implementation with respect to conventional control methods .

Also advantageous is the fact that the integrated control of the present invention is applicable both with synchronous motors and with asynchronous motors .

Although the invention has been described above with particular reference to an embodiment thereof provided purely by way of non-limiting example , numerous modi fications and variations will be apparent to the person skilled in the art in the light of the above description . Therefore, the present invention includes all modi fications and variations that fall within the scope of the appended claims .

Claims

1 . An integrated control for electric traction railway vehicles particularly suitable for a speed, anti-slip and power limitation control for a railway vehicle comprising at least one traction system provided with an electric motor which can be operated by an electronic drive system that performs a torque or current control , characterised by comprising a control architecture that comprises , in a single functional unit , a PID power controller ( 50 ) , a PID speed controller ( 52 ) , an anti-slip/anti-skid control ( 54 ) with said PID power controller ( 50 ) and said anti-slip/anti-skid control ( 54 ) positioned upstream of said PID speed controller ( 52 ) , coacting with one another to receive signals and/or data and/or commands functional to a determination of operating conditions of the railway vehicle and with said signals and/or data and/or commands consisting of electric power requested by/ transferred to an energy source , of an electric power limit trans ferrable to/receivable from the power supply source , of the speed of the vehicle , of the speed o f the wheels connected to a traction system and of a desired speed of the vehicle , said control architecture configured to determine : a ) based on signals and/or data and/or commands received through a communication protocol , a di f ference between a limit power trans ferrable to/receivable from an energy source and an electric power requested by/trans f erred to said energy source , processing said di f ference with a PID ( Proportional , Integral , Derivative ) control logic to supply a signal comprised within minimum and maximum limits of a torque or current reference that can be supplied to the electronic drive unit of the electric motor of the railway vehicle ; b ) based on the signals and/or data and/or commands received, a torque or current signal to be implemented in case a slipping/ skidding event is detected, with said signal comprised between the minimum and maximum limits of a torque or current reference that can be supplied to the electronic drive unit of the electric motor ; c ) based on the signals and/or data and/or commands received, a di f ference between the desired speed of the vehicle and the current speed of the same vehicle , with said di f ference processed with PID control logic for the generation of a torque or current signal to supply to the electronic drive unit of the electric motor, said torque or current signal limited dynamically in accordance with the torque or current signals determined according to the logics of points a) and b) .

2. The integrated control according to claim 1, characterised by comprising, for each motorised axle of the railway vehicle, the PID speed controller (52) which directly supplies a torque reference signal ( Torque Refi) based on an error measured between a speed desired and defined by an operator (SpdRef) (60) and a current speed of the wheels of the axle (SpdWi'j (56) .

3. The control according to claim 1 or 2, characterised in that the PID power controller (50) is integrated with an anti-windup logic and supplies a saturated signal between a value 0 and a value Tmaxi based on a difference between a limit power (51) of the source ( PowerLimit) and an absolute value of the overall power (51' ) (PowerAct) which is requested both by the alternating current loads and by the direct current loads and also by traction motors, said overall power (51' ) (PowerAct) obtainable interrogating a control unit of a generator set and/or a control unit for managing a battery pack by means of a fieldbus, the output of the PID power controller (50) being a torque signal TorquePwi (53) which increases up to a limit value Tmaxi until the absolute value of the overall power ( PowerAct) is below the value of the limit power (51) of the source ( PowerLimi t ) , the PID power controller (50) which decreases the output TorquePwi until reaching a condition of balance with an equality between the absolute value of the overall power (51' ) (PowerAct) and the value of the limit power (51) ( PowerLimi t) when the absolute value of said overall power ( PowerAct) is greater than the value of said limit power ( PowerLimi t) .

4. The control according to the preceding claims, characterised in that the PID speed controller (52) comprises an anti-windup logic suitable to regulate a reference torque TorqueRefi (59) sent to the control electronics of the electric motor via fieldbus based on an error calculated between a speed desired and defined by the operator SpdRef (60) and a current speed of the wheels of the axle SpdWi (56) .

5. The control according to the preceding claims, characterised in that the anti-slip/anti-skid control supplies a torque signal in case a slipping/skidding on the wheels of an i-th axle of the railway vehicle is detected.

6. The control according to the preceding claims, characterised in that the saturation limits of the speed control (52) are modified dynamically as a function of a minimum torque value between an absolute torque value TorqueAsi (58) output to the anti-slip/anti-skid control and a torque signal TorquePwi (53) output from the PID power controller (50) , with the upper limit of the saturation of the PID speed controller (52) coinciding with this minimum torque value and with the lower limit coinciding with the upper limit multiplied by "-1".