IT202000026618A1 - SELECTIVE SHORT CIRCUIT SYSTEM - Google Patents

Description

DESCRIPTION OF THE INDUSTRIAL INVENTION ENtitled: ?SHORT CIRCUIT SYSTEM

SELECTIVE?,

INTRODUCTION:

Reference context

The railway track and the rails that are part of it, in addition to having to mechanically support and route the movement of the rolling stock, are the site of the passage of electric currents generated for various purposes such as:

? Currents for the electric traction of trains,

? Communication signals (e.g. coded currents) ground-train,

? Signals for detecting rolling stock,

? Signals for the diagnostics of the rails themselves etc? .

The electrical parameters of the structure in which these currents pass vary greatly as the environmental conditions vary (sun, rain, snow, etc...)

Can the different currents involved vary in intensity? by several orders of magnitude: from several thousand amperes for traction currents in continuous traction to fractions of amperes for rolling stock detection signals in the case of audio frequency CDBs (track circuits).

Signals and currents must be ?separable? by type of signal and by railway section to which they refer.

Given the need? to circulate the rolling stock at speed? more sustained compared to the past, even in sections where the high speed? not ? present, and also due to maintenance problems, is there a further need? to eliminate from the lines the isolated joints which historically separate the different sections (joints which lead to a physical weakening of the line especially as speed increases).

Given the characteristics of the site and the power levels of the currents indicated above, in order to avoid the introduction of particularly complex and/or expensive filters for the spatial (section) separation / control of the different currents, ? today I use to distance them in frequency by placing them in the bands where the filters are more? easily achievable. This solution necessarily involves raising the frequency of the signals (see audio frequency cdb).

The above-described solution of increasing the frequency of the currents, while facilitating the separation of the signals by type and reference sections, brings as a counterbalance both the consistent attenuation of the signals themselves as the distance from the generator increases and further criticalities of implementation caused by phenomena such as ?cross talk? and variation of the frequency response characteristics of the land as a function of meteorological phenomena.

The situations indicated above impose the implementation of specific measures which, in addition to being onerous, entail technical constraints on the entire infrastructure; among these technical devices we mention:

? The placement of a large number of generators along the line,

? The placement of capacitors along the line,

? The positioning of devices capable of varying the transmission frequency on sequential sections with pre-established logics,

? The positioning of ?periodic? short circuits? frequency selective made with filters tuned to the frequencies used.

Solution: 2017 patent and still unsolved problems

In order to overcome the limitations indicated above allowing the operation of the system at low frequencies with consequent overcoming of the contraindications / problems enumerated and with the possibility? to separate the currents in a simple way, yes ? identified in 2013 an innovative solution.

The innovative solution, described in the patent granted by the Chamber of Commerce in 2017 n. 0001427886 (AUTOMATIC BLOCKING SYSTEM WITH CODED CURRENTS WITHOUT THE USE OF INSULATED JOINTS AND COMPATIBLE WITH THE CURRENT ON-BOARD SUB-SYSTEM INSTALLED ON RAILWAY VEHICLES), with a ?forward sliding cdb? to the advancement of the train based on the dynamic opening and closing of delimiting short circuits of cdb, it allows to dynamically move the signal generators in such a way that the currents that carry the information relating to the section in which the train passes are always produced in front to the moving train.

The solution able to operate with all currents at low frequencies, avoiding the elevation in frequency, ? for? characterized by an implementation problem considered ?blocking? for its effective use in the field relating to the fundamental component constituted by the switches which divide the sections when they close, delimiting them with a short circuit between the rails.

Although the solution identified in the 2017 patent functionally needs to operate on the two rails of the track by short-circuiting only the codified current signals (signals of low intensity at low frequencies ranging from 50 to 200 Hz), the patented technical solution envisages conceptually very simple switches which actually operate short-circuits on all frequencies (including continuous).

This feature requires for? to the closed switch of having to support the crossing of currents of great intensity? (such as those due to the rebalancing of the continuous traction currents which can even reach a thousand Ampere) and poses substantial complexities? construction / economics of the switches themselves. OBJECTIVES OF THE PROPOSED INVENTION:

The present patent proposal identifies a solution which allows the problems characterizing the switches discussed above to be overcome thanks to its capacity? to operate as a short circuit only for the selected signals (in the railway case of the BACC (Automatic Block with Codified Currents) the selective block of the only codified currents).

The new discovery ?SELECTIVE SHORT CIRCUIT SYSTEM? ? easily and economically implementable even with high currents and at low frequencies, where, due to the electrical parameters of the rails themselves, the classic filters are difficult to implement.

The present found, thanks to its ability? to work as a Selective Short-Circuit System and to its simplicity? therefore constitutes? an innovative alternative to the switch envisaged in the 2017 patent capable of performing similar functions overcoming the implementation problems.

The discovery that arises from necessity? to solve a specific and identified problem? however, it is convenient to use in all contexts where similar problems arise.

DESCRIPTION OF THE DISCOVERY:

generality

The new find? based on the placement of power generators (output of PW power amplifiers in the drawings) controlled by a feedback subsystem able for practical purposes to ?cancel? the voltage differences between two points of the circuit (in the case of the study the rails) only for a selected part of the global signal. The selection can be carried out either according to the frequencies or if the case of different logics.

The solution provides for the dynamic control of the voltage between the points where the selective short-circuit is to be operated with the implementation of a sort of ?tuned? to cancel the crossing of the currents selected and subject to short circuit.

The generator / amplifier supplies therefore? the necessary currents that would be present only for the selected signals in the event of a real short-circuit, effectively realizing a selective short-circuit.

Thanks to this system / invention used in the railway sector in the 2017 patent, instead of switches, it is possible to separate ?spatially? the various CDBs as regards specific currents relating to signalling.

Given the principles set out above, an important element? the subsystem of piloting in feedback that ? made in such a way as to effectively obtain zeroing (hereinafter defined only as zeroing since the residual signal, even if not completely zeroed, can be made small as desired) of the signal components present in the circuit between its points A and B (as indicated in figure 0 described below).

In the railway application for which the discovery ? been conceived, it could be requested, for example, according to needs:

1) Zeroing of the potential difference of the 2 rails (total short circuit),

2) Elimination of frequencies related to BACC systems (generally 50 and 178 Hz) (selective short circuit, useful in replacing the switch in the cited patent),

3) Elimination of one or more? specific signals / codes

Based on the function required, the input signal to the amplifier can be derived or simply from the tension between the rails in the same point (which a sort of selective feedback) or from a processing of more? signals (voltages and currents) taken from various points of the circuit (in the case of study rails) or external to it. Generalized architecture (figure 0)

In its general sense, the invention (conceptually applicable also in sectors other than the railway)? constituted by the blocks indicated in figure 0. In it between the points of the circuit A and B (in the railway case, points of the two rails) ? the voltage difference has been detected which is physically conditioned (block BC-Block Conditioning) and processed / filtered (block B1 not necessarily realized in frequency for example, Look in amplifier, box car integrator, etc..) to report the input to block A only the part of the signal to be short-circuited from the overall signal present on points A and B. Block A ? consisting of a high gain amplifier which minimizes the signal to be ?shorted? on the circuit (in the railway case the rails). Block B2 is used to avoid output voltage transients; in fact, the block operates a suitable filtering which eliminates from the output signal the components not proportional to the signal to be "short-circuited". Through the block, Output adaptation (Au), a signal of suitable power is supplied in a suitable way (power, impedance and possible insulation) at points A and B.

The necessity? of block B2 derives from the fact that since the feedback loop is closed only for the signals selected by filter F1, amplifier A could go into saturation and never come out of it. If saturated, the short-circuit system would remain open also for signals meeting the requirements set by F1.

During the time required for the entire loop to reach full speed, filter F2 selects at the output of OP the only signal components capable of ?passing? in F1 and then close the ring.

Always in order to avoid possible blocks of the feedback loop due to the saturation of A, the amplifier can? also be equipped with an SCT element (Total Feedback System) which, in the event of saturation, brings it back to work in the linear area, enabling the feedback of the entire signal. The element is progressively disengaged when it reaches full speed. It seems more It is easy to implement this system in block A, even if it could conceivably work on filter blocks (B1 and B2).

Since the system must be stable and therefore not oscillate, ? necessary, at the time of the final design to verify its stability? through some commonly used criterion (for example the Nyquist criterion or that of Bode).

Further signals can be used to condition all the blocks of the invention. The signals, denominated D or S according to their digital or analog nature, can come from sources external to the circuit (such as remote control systems, sensors mounted to draw voltages and/or currents in adjacent circuits, temperature/humidity sensors?) or from specific points of the circuit itself. Said signals may require adequate conditioning before being connected to blocks of the invention (input conditioning block to the BC SA invention (Auxiliary Signal Conditioning Block) which in the case may coincide with those used to condition the signals on which the selective short is applied .

For greater clarification of the previous principle schemes, we illustrate some application examples

Example 1 (figure 1)

The example ? relating to the railway context in the context of cdb (track circuit) where the invention referred to in the aforementioned 2017 patent is present.

BC block? achieved through the IA isolation amplifier preceded by the inserted capacitor C to avoid possible saturation of the amplifier input stage. saturation? in fact, it is possible in the presence of continuous potential differences due to traction current imbalances (it is hypothesized in continuous traction at 3000 Volts).

The B1 block? implemented by the frequency filter F1, in this application example yes ? opted for a bandpass filter from 25 to 200 Hz which allows both to block continuous components possibly reintroduced by AI (remember the presence of C) and, considering the carriers used in Italy in BACC systems of 50 and 178 Hz, to eliminate any lower frequencies ? high as insignificant.

Block A? constituted by an operational amplifier OP (completed by a control element SCT, whose function is described in the general example) in an inverting configuration whose feedback loop ? consisting of blocks F2, PW, T, C, IA, F1.

The PW power amplifier? necessary to supply the rails (for that part of the signal selected by F1) with the same currents that would flow in the event of a normal short circuit. Even if the railway standard provides for a maximum level of 20 Ampere for the codified currents, and since our system could be seen as a short path from the currents of the 2 generators belonging to the 2 adjacent cdb, it must be able to support the sum of the same therefore 40 Ampere . The power supplied by the amplifier? very limited as its output voltage ? almost nothing thanks to the presence of the feedback (this aspect favors the implementability of the invention in the field).

The Bu Block? composed of the aforementioned amplifier PW and the matching transformer T.

Is also represented the coil of rebalancing L, gi? generally present in the railway sector to rebalance the continuous traction currents in the two rails, it ? irrelevant for our application due to the presence of the capacitor C in the block AU, specifically used to prevent the possible presence of voltage unbalances of different modes from saturating the isolation amplifier IA (the use of IA capable of to withstand common mode voltages greater than 1000 Volts).

Obviously, always because of the delays of the filters, spurious signals may occur in the presence of variations of the signal to be controlled, but these transients in the railway application are completely negligible (remember, for example, that variations of less than 3 seconds are even ignored in the case of signal repetition via coded currents).

It should be noted that obviously the commons of the elements IA, F1, OP, F2, PW and primary of T can be connected to a mass G, while the part referring to the rails must be left floating. The obvious modifications to be made in the case of particular CDBs such as those in which one of the two rails is connected to ground are not considered here.

In order to make the system compliant with the fundamental safety requirements (SIL4) in the railway environment? the simple introduction of a programmable card that allows to verify if the signals present, currents and voltages, are congruent with the instantaneous state of the neighboring CDBs is sufficient. This makes it possible to immediately detect both problems related to the codes and related to any changes in the physical parameters of the system (attributable to any breakage of the rails). It seems superfluous to point out that ? it is advisable that the programmable card is previously certified SIL4.

Example 2 (figure 2)

In figure 2 ? specified a block configuration of the invention applicable in the railway environment also in replacement of the switches in the solution indicated in the 2017 patent.

The different solution aims not already? to the exclusion from the short-circuit of the direct component, but?, in a more? selective to the ?admissibility? short? of the components in frequency around the component where ? the signal of interest is present.

Objective ? why? that of blocking with a selective short only the signals in the typical band of the Italian BACC standard (with 2 carriers, one at 50 Hz and one at 178 Hz).

Said example ? substantially the same as that illustrated in the previous fig.1 where block B1 is composed of the parallel of two bandpass filters with adequate bandwidth (F3 at 50 Hz and F4 at 178 Hz followed by an adder A), and block B2 which, except small possible variations for possible compensations, it could be completely the same as block B1 with F5 equivalent to F3 and F6 equivalent to F4.

In this way, when the amplifier output is activated, all the codes created with signals on one or both of the two aforementioned frequencies are reset, such as the standard ones of the ?Automatic Blocking with Codified Currents? systems.

In the figure L has the same value as example 1.

Example 3 (figure 3)

In figure 3 ? a block configuration of the invention applicable in the railway sector has been specified. In the figure the functions performed by B1, B2, OP are assigned to a digital processing system indicated in the figure with the abbreviation ED (in this application case there are conditioning signals both type D (digital) and S (analog), the digital signals come from external systems while the analog signals come from the same circuit under control and undergo input conditioning operated by the same block BC used for the currents on which the selective short-circuit is applied.

It is possible to identify in the diagram in figure 3, at the output of the sensors ?S?, 2 input signals according to the invention. Are the signals coming from the same stretch of circuit which ? selective short circuit applied. The data is captured by the rails via voltage sensor and current sensor. The current and voltage signal pick-up circuits need to be insulated by means of an insulation system consisting of Isolation Amplifiers similar to those of the conditioning block BC of the invention and therefore represented therein. To feed the system there are further Digital conditioning signals (D) which, like the analog signals, are used to condition the block ED. These signals are made up of inputs from external systems and sensors (the sensors are ballast temperature and humidity, etc.). The analog and digital signals condition the blocks of the invention in order to optimize and speed up the response of the system in the circuit.

In the figure L has the same value as example 1.

CONCLUSIONS:

In this description ? illustrated an innovative found, which, although more? wide employability?, ? was conceived to implement the invention referred to in the patent ?AUTOMATIC BLOCKING SYSTEM WITH CODED CURRENT WITHOUT THE USE OF INSULATED JOINTS AND COMPATIBLE WITH THE CURRENT ON-BOARD SUBSYSTEM INSTALLED ON RAILWAY VEHICLES?.

In fact, the invention allows the switches present in the 2017 patent to be replaced with a different system capable of guaranteeing selective shorts agreed on the signal frequencies, avoiding the unacceptable overload of currents on the proposed switches. How already? indicated, the hypothesis of decreasing the current by means of the introduction of the filter in series with the switch ? technically unfeasible.

Some technical features such as:

? The feedback effected exclusively on a selected part of the signal (Block B1), ? Control of the system output, through block B2, introduced to eliminate the presence of unwanted reactions mainly attributable to the times due to block B1 (remember that the feedback loop is closed only for that part of the signal selected by block B1) ,

? Enabling the feedback of all the elements of the signal in a temporary way to accelerate the exit from any states of saturation of the same attributable to the above reasons (thanks to the presence of the SCT element),

? The modulation of the intervention of the various blocks of the ring according to the local and/or remote parameters, such as for example temperature, humidity? of the ballast etc.. (input signals S and D),

? The inclusion of a PW amplifier of fairly limited power even in the presence of large currents, as the voltage it imposes? very low (Short Circuit),

? The very architecture of the invention which, by allowing easy reading of the outputs and inputs of the various voltage and current blocks, makes it simple, with a processing operated by a previously SIL4 certified programmable card, the continuous and safe detection of the state of the invention so as to be able to to meet the safety requirements SIL4 that allow the real usability? in the railway context.

It should be noted that a solution of this kind, in addition to being easy to implement and highly reliable, is completely dynamically variable in a trivial way, and also allows a verification of the variations of the system parameters which can also be used for diagnostic reasons.

In relation to the problem to solve which the invention? was conceived the invention itself pu? be compared to a bandpass filter with active elements (a filter which, if based on classic capacitors, impedances and other passive elements, would not be feasible in the specific implementation context) characterized by simple and reliable implementability.

In its most significant sense extensive, the found pu? be characterized by filters that are not necessarily in frequency, by input and output adapters which may have different characteristics from those typical of the railway environment and by filtering logic adaptable to needs established by external logics which vary over time.

Claims (6)

CLAIMS OF THE INDUSTRIAL INVENTION ENtitled: ?SELECTIVE SHORT-CIRCUIT SYSTEM?, 1. Electronic system composed of the following blocks: PW power amplifier block whose output ? applied, via an impedance matching circuit to the two rails of a track; conditioning block BC of the signal which picks up the signal present on the track at the same point where ? PW amplifier output applied; block B1 applied at the output to the conditioning block BC, which allows the passage of only selected components of the signal, therefore composed of a filter; block A consisting of a high-gain inverting amplifier which amplifies the output signal to block B1; block B2 constituted in a similar way to block B1 which eliminates from the output signal from the previous block A components different from those selected by block B1, which could be generated at the output of the inverting amplifier, whose output ? applied to the PW power amplifier input; said system how ? conceived ? capable of canceling at the point of its application between the 2 rails only some selected components of the signal present there, behaving like a short circuit but only for selected components without altering the others. 2. System according to claim 1 in which the blocks B1 and B2 and A are equipped with inputs and analog or digital logic, able to vary the operating parameters, according to control and driving signals external to the system. 3. System according to claim 1 equipped with an analog or digital block which, in case the high-gain amplifier A goes into saturation, reduces the gain of the amplifier A itself until? it does not return to work in the linear area. 4. System according to claim 1 equipped with an analogue or digital block which, in case the high gain amplifier A goes into saturation, electrically eliminates the two blocks B1 and B2 restoring them when the amplifier A goes out of the saturated state. 5. System according to claim 1 architecturally equipped with outputs for reading voltages and currents at the output/input of the various blocks to be supplied to external analysis boards for various purposes such as safety and diagnosis. 6. System according to claim 1 in which the inversion of the signal is performed in any block or which is present more? times.