DE102020204900B4 - Method and circuit arrangement for precharging an input capacitance of a vehicle when forming an electrical contact with an overhead line - Google Patents

Abstract

Method for precharging an input capacitance (CV) of a vehicle (50) when forming an electrical contact with an overhead line (20), wherein a two-pole electrical contact between the overhead line (20) and the vehicle (50) is made pole by pole by means of at least one semiconductor switch (S1 , S2) is produced, and wherein at least one of the semiconductor switches (S1) is controlled in a pulsed manner in such a way that the input capacitance (CV) of the vehicle (50) is precharged to a target voltage (vDes), wherein an electrical contact for one of the poles is closed by closing the at least one semiconductor switch (S2) assigned to the pole is formed after a mechanical contact has been formed between a pantograph (53) and the overhead line (20), and wherein only the at least one semiconductor switch (S1) assigned to the other electrical pole is used for precharging the input capacitance (CV ) is controlled in a pulsed manner.

Description

The invention relates to a method and a circuit arrangement for precharging an input capacitance of a vehicle when forming an electrical contact with an overhead line.

It is known, when a vehicle is coupled to an overhead line, to precharge an input capacitance of the vehicle by means of a precharging circuit. In this case, the input capacitance is charged to such an extent that the remaining voltage difference between the overhead line and the input capacitance is too low to cause currents that are harmful to components.

Furthermore, in addition to the pre-charging circuit, mechanical main contactors and fuses against overcurrent are usually present in a pantograph used for coupling in order to enable safe coupling and decoupling as well as disconnection of the circuits.

Loss of contact between the pantograph or its pantographs (e.g. sliding contacts) and the overhead line can occur while driving on the overhead line. Reconnecting also requires a controlled pre-charging of the input capacitance, since the properties of the overhead line (resistive-inductive) and vehicle (capacitive) form a slightly damped oscillating circuit, which can lead to strong current and voltage oscillations. This effect can lead to temporary overvoltages in the system and, due to the high pre-charging current, premature wear of components, especially mechanical switching contacts.

It is known to carry out the pre-charging via an ohmic pre-charging resistor. The control with mechanical switches and discrete pre-charging resistors is possible when contacting for the first time via a sequence control or a voltage control. However, when contacting the overhead line again, a mechanical switch cannot usually be used due to the extremely short contact breaks (a few milliseconds). This makes the process uncontrollable. Furthermore, precharging via the constant precharging resistor is a purely passive process and therefore comparatively time-consuming, since a relatively large precharging resistor must be selected if the contact currents of the main contactors are to be greatly reduced to reduce contact wear, especially at the beginning of precharging. Another disadvantage of the passive method is that any load current that might be present would mean that the precharging is not completed.

From the DE 10 2016 014 625 A1 a method for pre-charging a power converter is known, with a switchable decoupling component being connected between a feed pole of a switchable DC voltage source for providing a feed DC voltage and an output pole for providing a charging voltage for the power converter such that a reverse current from the output pole to the feed pole is blocked and wherein according to switching on the DC voltage source, the power converter is precharged by a precharging circuit connected in parallel with the decoupling component, before the decoupling component is switched on to provide the charging voltage and to let through a charging current. The method provides for the pre-charging circuit to have a switchable rectifier arrangement for passing a pre-charging current from the feed pole to the output pole and for a switching arrangement of the rectifier arrangement to be switched on in a pulsed manner for pre-charging the power converter. A corresponding device for pre-charging a power converter and a corresponding power converter arrangement are also described.

From the DE 20 2019 101 527 U1 discloses an on-board power converter, in particular for a rail vehicle, with a main module that is designed to convert an input DC voltage into a first output AC voltage, and at least one first auxiliary module that is connected to an intermediate circuit of the main module and is designed to convert an intermediate circuit DC voltage of the intermediate circuit to convert into an output DC voltage, wherein the main module and the first auxiliary module are arranged in a common housing.

From the DE 10 2017 201 657 A1 a vehicle electrical system, a means of locomotion and a circuit arrangement for supplying energy to an intermediate circuit of a high-voltage energy network of a means of locomotion are known. The circuit arrangement comprises an input terminal for connecting an electrochemical energy store for traction energy, an output terminal for connecting the intermediate circuit, an inductance, a diode, a main contactor and a switch, with the inductance being set up when the main contactor is open and a current flowing from the input terminal to the switch when the switch is closed to conduct the output terminal and to maintain the current through the diode to the output terminal when the switch is open.

The invention is based on the object of improving a method and a circuit arrangement for precharging an input capacitance of a vehicle when forming an electrical contact with an overhead line.

The object is achieved according to the invention by a method having the features of patent claim 1 and a circuit arrangement having the features of patent claim 9 . Advantageous configurations of the invention result from the dependent claims.

In particular, a method for precharging an input capacitance of a vehicle when forming an electrical contact with an overhead line is provided, with a two-pole electrical contact between the overhead line and the vehicle being produced pole by pole by means of at least one semiconductor switch, and at least one of the semiconductor switches being pulsed in such a way is controlled that the input capacitance of the vehicle is pre-charged to a target voltage.

Furthermore, in particular a circuit arrangement for a vehicle for precharging an input capacitance of a vehicle when forming an electrical contact with an overhead line is created, comprising at least one semiconductor switch for each pole of an electrical connection between the overhead line and the vehicle, a control device, the control device being designed in this way is to drive at least one of the semiconductor switches in a pulsed manner in such a way that the input capacitance of the vehicle is precharged to a target voltage.

The method and the circuit arrangement enable an input capacitance of the vehicle, which is generally formed by an intermediate circuit capacitance of the high-voltage network of the vehicle, to form an electrical connection between an overhead line and a vehicle, in particular an electrical connection between the overhead line and a high-voltage network of the vehicle is to subpoena in a targeted and controlled manner. As a result, a voltage difference between the overhead line and the high-voltage network of the vehicle can be reduced or completely eliminated. In particular, the method and the circuit arrangement enable a two-pole connection and disconnection of the electrical connection. For this purpose, at least one semiconductor switch is provided for each of the poles of the electrical connection. To precharge the input capacitance, the at least one semiconductor switch is driven in a pulsed manner on at least one of the poles, so that the input capacitance of the vehicle is precharged to a target voltage. With a suitable selection of the pulses with which the semiconductor switch is driven, it can be achieved in particular that a current flowing effectively to the input capacitance can be limited and a voltage at the input capacitance can be adapted to the voltage of the overhead line over a predetermined pre-charging time.

In particular, the method is started automatically when contact with an overhead line is imminent.

A semiconductor switch is in particular a power semiconductor switch. The semiconductor switch can be formed, for example, as a metal-oxide-semiconductor field effect transistor (MOSFET) or as a bipolar transistor with an insulated gate electrode (IGBT).

Provision can be made for the circuit arrangement to have two semiconductor switches for each of the poles, which are each connected to one another in such a way that a bidirectional current flow and power flow is possible. In this way, in addition to a transmission of electrical energy from the overhead line to the vehicle, it is also possible, in particular, to feed it back, ie to transmit electrical energy from the vehicle via the overhead line to a utility network.

In particular, the circuit arrangement includes a semiconductor switch for each of the poles, so that the electrical connection can be made or separated on all poles.

A pole designates in particular a voltage pole (e.g. positive pole and negative pole) of a DC voltage or a polarity of an electrical conductor or conductive path used to form the electrical connection.

The target voltage corresponds in particular to a voltage on the overhead line or a voltage at least close to the voltage on the overhead line. In order to detect the voltage on the overhead line, the circuit arrangement has in particular a voltage sensor, sensor data detected thereby being fed to the control device.

Parts of the control device can be designed individually or combined as a combination of hardware and software, for example as program code that is executed on a microcontroller or microprocessor. However, it can also be provided that parts are designed individually or combined as an application-specific integrated circuit (ASIC).

In the case of the method and the circuit arrangement, it is assumed in particular that an electrical connection is formed between DC voltage networks.

Provision is made for an electrical contact for one of the poles to be made by closing the at least one semiconductor switch assigned to the pole after a mechanical contact has been formed between a pantograph and the overhead line is formed, and wherein only the at least one semiconductor switch assigned to the other electrical pole is driven in a pulsed manner for precharging the input capacitance. As a result, synchronization when switching the semiconductor switches provided for the two poles can be largely dispensed with, since only the at least one semiconductor switch has to be driven in a pulsed manner by one of the two paths. As a result, the control and the circuit arrangement, in particular the control device, can be simplified, so that costs and effort can be saved. If, for example, a semiconductor switch is provided for each of the two poles, both semiconductor switches are open when the overhead line is mechanically contacted via a pantograph. After the mechanical contact has been made, one of the two semiconductor switches is permanently closed, so that a permanent electrical connection is formed for the associated pole, but no current is yet flowing. The other semiconductor switch is then driven in a pulsed manner, so that the input capacitance of the input capacitor is gradually charged to a target voltage.

One embodiment provides that the precharging is carried out by means of a voltage control and pulse width modulation control of gate drivers of the at least one semiconductor switch controlled in a pulsed manner. In this way, a gradual or continuous adjustment of the voltages between the overhead line and the input capacitance can be achieved. In particular, disruptive vibrations can be reduced in an improved manner both with regard to a current amplitude and with regard to a duration. In a simple case, it is provided that a voltage ramp is calculated as a function of a voltage difference present between the overhead line and the input capacitance and a predetermined pre-charging time. Starting from the calculated voltage ramp, a target value for the voltage is converted into a pulse width ratio over time, i.e. for a current point in time during precharging, and fed to the gate driver of the at least one pulsed-controlled semiconductor switch by means of a pulse width modulator.

One embodiment provides that the pre-charging is carried out by means of current regulation via continuous regulation and pulse width modulation actuation of gate drivers of the at least one semiconductor switch which is actuated in a pulsed manner. As a result, a maximum current flowing during precharging can be limited in an improved manner. Since a maximum current that flows can be limited in an improved manner, oscillations in the current after the precharging has ended can also be reduced in an improved manner, both with regard to a current amplitude and with regard to a duration. In a simple example, it is provided that a voltage gradient is calculated as a function of a voltage difference between the overhead line and the input capacitance and a predetermined pre-charging time (i.e. a gradient of a particularly linear voltage ramp). Based on the calculated voltage gradient, a target value for the current is calculated as a function of the input capacitance. This calculated setpoint value for the current forms a reference variable for a PI current controller, with the PI current controller providing a setpoint value for the voltage as a manipulated variable for regulation. The voltage is converted into a pulse width ratio and fed to the gate driver of the at least one pulsed-controlled semiconductor switch by means of a pulse width modulator. In other words, the voltage lags the current during pre-charging because the input capacitance works like an integrator.

One embodiment provides that the precharging is carried out by means of a current control via a two-point control with direct control of gate drivers of the at least one semiconductor switch controlled in a pulsed manner. The two-point control allows a particularly simple construction of the circuit arrangement or the control device. Nevertheless, a current during pre-charging can be regulated in a targeted manner and oscillations can be reduced after pre-charging has ended. In particular, the gate driver is only switched on and off around the desired setpoint, which means there are only two states in two-point control. Furthermore, the two-point control is advantageous when electrically connecting the vehicle to an overhead line, because no knowledge of the current control path is required. Since the inductances of the overall system are usually unknown, this allows improved control of the current during pre-charging. In a simple example, it is provided that a voltage gradient is calculated as a function of a voltage difference between the overhead line and the input capacitance and a predetermined pre-charging time (i.e. a gradient of a particularly linear voltage ramp). Based on the calculated voltage gradient, a target value for the current is calculated as a function of the input capacitance. This calculated desired value for the current is controlled using a two-point controller, ie the gate driver is controlled accordingly using the two-point controller. As with continuous regulation, the voltage lags the current because the input capacitance works like an integrator.

In one embodiment it is provided that the pre-charging by means of a cascade control the voltage with subordinate current regulation is carried out via continuous regulation and pulse width modulation actuation of gate drivers of the at least one semiconductor switch which is actuated in a pulsed manner. As a result, vibrations during and after preloading can be almost completely suppressed. A simple example provides that, based on the voltage on the overhead line as a command variable, a voltage regulator provides a setpoint value for the current as a manipulated variable. The target value for the current forms the reference variable for a PI current controller, which provides a voltage as a manipulated variable, which is converted into a pulse width ratio and fed to the gate driver of the at least one pulsed-controlled semiconductor switch by means of a pulse width modulator.

One embodiment provides that the pre-charging is carried out by means of a cascade regulation of the voltage with a subordinate current regulation via a two-point regulation with direct activation of gate drivers of the at least one pulsed-controlled semiconductor switch. As a result, vibrations during and after preloading can be almost entirely suppressed. In addition, an inrush current can be greatly limited compared to continuous regulation. Furthermore, the two-point control allows a particularly simple construction of the circuit arrangement or the control device. A simple example provides that, based on the voltage on the overhead line as a command variable, a voltage regulator provides a setpoint value for the current as a manipulated variable. The setpoint for the current forms the reference variable for the two-position controller. As with continuous regulation, the voltage lags the current because the input capacitance works like an integrator.

One specific embodiment provides that a target value restriction is provided for a variable that is controlled in each case. As a result, the control behavior can be better controlled.

In one embodiment, provision is made for the pre-charging to be carried out even after a loss of contact between a pantograph and the overhead line and contact being made again. As a result, currents can be kept low or regulated even in the event of a brief loss of contact and subsequent reconnection. The control device is designed in particular to detect a loss of contact, for example by detecting a brief voltage drop, and to start the pre-charging method after detection.

In one embodiment it is provided that at least one of the poles after the pre-charging, an additional electrical contact is formed parallel to the at least one semiconductor switch by means of at least one mechanical switch. In this way a hybrid switch can be formed. Mechanical switches connected in parallel can reduce conduction losses in normal operation, ie after precharging has taken place, which can otherwise occur at the semiconductor switches. The mechanical switches connected in parallel are closed after successful pre-charging, so that another, lower-loss electrical connection is formed between the overhead line and the vehicle.

Furthermore, mechanical switches connected in series can also be provided for both poles. These allow galvanic isolation, whereby the series-connected mechanical switches are normally closed and during pre-charging.

In any case, provision is made for the mechanical switches to be switched in a coordinated manner with respect to the semiconductor switches. The control device is designed in such a way that the mechanical switches are closed and opened by appropriate activation in a manner coordinated with the semiconductor switches.

One embodiment provides that an electrical connection between the overhead line and the vehicle is disconnected by means of the at least one semiconductor switch in the event of an overvoltage, an overcurrent and/or a fault current occurring. As a result, a fuse can be implemented by means of the semiconductor switches, which protects the circuit arrangement and the vehicle in an additional and improved manner. A sensor system that is appropriately set up for this purpose is provided for detecting an overvoltage, an overcurrent and/or a fault current.

In one embodiment, it is provided that at least one of the semiconductor switches is protected or is protected by means of a snubber circuit. As a result, when the at least one semiconductor switch is opened, overvoltages that occur due to the inductive nature of the overhead line can be intercepted or reduced.

Further features for the configuration of the circuit arrangement result from the description of configurations of the method. The advantages of the circuit arrangement are in each case the same as in the case of the configurations of the method.

• 1 eine schematische Darstellung einer Ausführungsform der Schaltungsanordnung für ein Fahrzeug zum Vorladen einer Eingangskapazität eines Fahrzeugs beim Ausbilden eines elektrischen Kontaktes mit einer Oberleitung;
• 2 eine schematische Darstellung eines zeitlichen Verlaufs für das Schalten der Halbleiterschalter beim Verbinden und Trennen der elektrischen Verbindung zwischen Oberleitung und Fahrzeug;
• 3a, 3b schematische Darstellungen zur Verdeutlichung von Ausführungsformen der Halbleiterschalter für einen unidirektionalen Betrieb;
• 4a, 4b schematische Darstellungen zur Verdeutlichung von Ausführungsformen der Halbleiterschalter für einen bidirektionalen Betrieb;
• 5 eine schematische Darstellung eines Ausschnitts einer weiteren Ausführungsform der Schaltungsanordnung mit Snubberschaltung;
• 6a, 6b verdeutlichen das Ausbilden einer elektrischen Verbindung zwischen einem Fahrzeug und einer Oberleitung ohne besondere Maßnahmen, das heißt ohne ein Vorladen;
• 7a, 7b verdeutlichen das Ausbilden einer elektrischen Verbindung zwischen einem Fahrzeug und einer Oberleitung, wobei das Vorladen mit Hilfe einer Ausführungsform des Verfahrens durchgeführt wird;
• 8a, 8b verdeutlichen das Ausbilden einer elektrischen Verbindung zwischen einem Fahrzeug und einer Oberleitung, wobei das Vorladen mit Hilfe einer weiteren Ausführungsform des Verfahrens durchgeführt wird;
• 9a, 9b verdeutlichen das Ausbilden einer elektrischen Verbindung zwischen einem Fahrzeug und einer Oberleitung, wobei das Vorladen mit Hilfe einer weiteren Ausführungsform des Verfahrens durchgeführt wird;
• 10a, 10b verdeutlichen das Ausbilden einer elektrischen Verbindung zwischen einem Fahrzeug und einer Oberleitung, wobei das Vorladen mit Hilfe einer weiteren Ausführungsform des Verfahrens durchgeführt wird;
• 11a, 11b verdeutlichen das Ausbilden einer elektrischen Verbindung zwischen einem Fahrzeug und einer Oberleitung, wobei das Vorladen mit Hilfe einer weiteren Ausführungsform des Verfahrens durchgeführt wird;
• 12 eine schematische Darstellung einer weiteren Ausführungsform der Schaltungsanordnung mit zusätzlichem Überspannungs,- Überstrom- und Fehlerstromschutz;
• 13 eine schematische Darstellung zur Verdeutlichung einer Ausführungsform der Halbleiterschalter mit zusätzlichen parallel und/oder in Serie geschalteten mechanischen Schaltern.

The invention is described below using preferred exemplary embodiments with reference taken on the figures explained in more detail. Here show:

• 1 a schematic representation of an embodiment of the circuit arrangement for a vehicle for precharging an input capacitance of a vehicle when forming an electrical contact with an overhead line;
• 2 a schematic representation of a time course for the switching of the semiconductor switches when connecting and disconnecting the electrical connection between the overhead line and the vehicle;
• 3a , 3b schematic representations to illustrate embodiments of the semiconductor switches for unidirectional operation;
• 4a , 4b schematic representations to illustrate embodiments of the semiconductor switches for bidirectional operation;
• 5 a schematic representation of a section of a further embodiment of the circuit arrangement with snubber circuit;
• 6a , 6b illustrate the formation of an electrical connection between a vehicle and an overhead line without special measures, ie without pre-charging;
• 7a , 7b illustrate the formation of an electrical connection between a vehicle and a catenary, wherein the pre-charging is performed using an embodiment of the method;
• 8a , 8b illustrate the formation of an electrical connection between a vehicle and an overhead line, the pre-charging being carried out with the aid of a further embodiment of the method;
• 9a , 9b illustrate the formation of an electrical connection between a vehicle and an overhead line, the pre-charging being carried out with the aid of a further embodiment of the method;
• 10a , 10b illustrate the formation of an electrical connection between a vehicle and an overhead line, the pre-charging being carried out with the aid of a further embodiment of the method;
• 11a , 11b illustrate the formation of an electrical connection between a vehicle and an overhead line, the pre-charging being carried out with the aid of a further embodiment of the method;
• 12 a schematic representation of a further embodiment of the circuit arrangement with additional overvoltage, overcurrent and residual current protection;
• 13 a schematic representation to illustrate an embodiment of the semiconductor switch with additional mechanical switches connected in parallel and/or in series.

In 1 1 is a schematic representation of an embodiment of the circuit arrangement 1 for a vehicle 50 for precharging an input capacitance CV of the vehicle 50 when forming an electrical contact with an overhead line 20 . The input capacitance CV is part of a high-voltage network 60 of the vehicle 50.

The circuit arrangement 1 is arranged in a pantograph 51 of the vehicle 50 . Circuit arrangement 1 includes a semiconductor switch S1, S2 for each pole or polarity of the electrical connection between overhead line 20 and vehicle 50. Circuit arrangement 1 also includes a control device 2. Control device 2 itself is controlled, for example, by means of a pantograph control 52; for example, after a pantograph 53 has been mechanically connected to the overhead line 20, the method described in this disclosure can be started by means of the pantograph controller 52 by a start signal.

The control device 2 controls at least one of the semiconductor switches S1, S2 in a pulsed manner, so that the input capacitance CV of the vehicle 50 is precharged before an electrical connection is formed between the overhead line 20 and the vehicle 50. In particular, a voltage UV at the input capacitance CV is adjusted to a voltage UF of the overhead line 20 by precharging the input capacitance CV by means of a precharging current IV.

The circuit arrangement 1 also includes a fuse FP and a voltage sensor (not shown) for detecting the voltage UF on the overhead line 20 and the voltage UV on the vehicle after the mechanical connection. Furthermore, a loss of contact and reconnection can also be recorded and/or detected by means of the voltage sensors. The circuit arrangement 1 also includes a current sensor 54 for detecting the current IV. The detected voltages UF and UV and the detected current IV are fed to the control device 2 .

Provision can be made for the pre-charging to be carried out even after a loss of contact between a pantograph 53 and the overhead line 20 and contact being made again. That The procedure here is in principle analogous to the pre-charging after an initial contacting of the overhead line 20.

Provision can also be made for the arrangement to have an electrical overvoltage protection device 3 (lightning protection).

In the 2 is a schematic representation of a time profile for the switching of the semiconductor switches when electrically connecting and disconnecting the electrical connection between the overhead line and the vehicle. After the formation of the mechanical contact between the pantograph 53 and the overhead line 20, the semiconductor switch S2 is permanently closed (time t1). Then, starting at time t2, the semiconductor switch S1 is driven in a pulsed manner by the control device 2, so that the input capacitance CV is precharged by means of a constant current IV.

If the input capacitance CV is sufficiently precharged, ie if a voltage UV at the input capacitance is equalized to a voltage UF of the overhead line, then the semiconductor switch S1 is permanently closed (time t3). In normal operation, electrical power can now be transported from the overhead line to the vehicle and used there, for example, to operate an electrical drive and/or to charge a battery.

If the semiconductor switches S1, S2 are designed to be bidirectional, electrical power can also be fed back in a controlled manner from the vehicle via the overhead line into a utility network by way of feedback.

Before the mechanical connection between the pantograph and the overhead line is separated at the end of an overhead line journey, after the transmitted electrical power or the current IV has been reduced to zero, first the semiconductor switch S1 (time t4) and then the semiconductor switch S2 (time t5) are opened in order to disconnect the electrical connection. The mechanical connection between the pantograph and the overhead line can then be separated.

the 3a and 3b show schematic representations to clarify embodiments of the semiconductor switches S1, S2 for unidirectional operation (ie IV> 0, cf. 1 ), i.e. the semiconductor switches S1, S2 only allow the flow of current and thus the flow of power from the overhead line to the vehicle to be controlled. 3a shows a normally blocking n-channel IGBT and 3b a self-locking n-channel MOSFET with anti-parallel connected diodes.

the 4a and 4b show schematic representations to clarify embodiments of the semiconductor switches S1, S2 for a bidirectional operation (ie IV < 0 < IV, cf. 1 ), i.e. the semiconductor switches S1, S2 allow both a control of the current flow and thus the power flow from the overhead line to the vehicle and a control of the current flow and thus the power flow from the vehicle to the overhead line. 4a shows two normally blocking n-channel IGBTs connected in series and opposite each other 3b two normally-off n-channel MOSFETs connected in opposite series, each with anti-parallel connected diodes.

In 5 1 is a schematic representation of a section of a further embodiment of the circuit arrangement, in which the semiconductor switch S1 is protected by a snubber circuit 4 connected in parallel therewith against overvoltages occurring when opening due to inductances of the overhead line. The capacitance C and the resistance R of the snubber circuit 4 are to be dimensioned appropriately depending on the application.

the 6a and 6b illustrate the formation of an electrical connection between a vehicle and an overhead line without special measures, ie without pre-charging. the 6a 1 shows a block diagram in this respect, in which, however, the electrical connection is made by simply switching the semiconductor switches without any special measures, in that a gate driver 5 simply switches the semiconductor switch to conduction. In this case, the target voltage vDes corresponds to the voltage UF of the overhead line.

the 6b shows the course of the voltage UV (cf. 1 ) and the current IV (cf. 1 ) at the input capacitance and the switching behavior of the gate driver 5, each over time t for an exemplary simulated scenario. In the exemplary simulated scenario, the following parameters were used: an inductance of the catenary of 1 mH, a resistance of the catenary of 0.2 ohms and an input capacitance CV of the vehicle of 2 mF. It can be clearly seen that after the semiconductor switch has closed at time t1 at 0.005 seconds, both the voltage UV and the current IV show strong oscillations, which can lead to rapid wear of electrical components.

the 7a and 7b illustrate the formation of an electrical connection between a vehicle and an overhead line, with the Pre-charging is carried out using an embodiment of the method, that is to say the input capacitance is pre-charged according to the method.

In the embodiment, it is provided that the pre-charging is carried out by means of a voltage control and pulse width modulation control of a gate driver 5 of the pulsed controlled semiconductor switch S1 (cf. 1 and 2 ) is carried out.

the 7a shows a corresponding block diagram. In a first measure 100, a voltage ramp with a gradient dU/dt is calculated as a function of the voltage difference between the voltage UF of the overhead line and the voltage UV at the input capacitance and a predefined pre-charging time tPrecharge.

In measure 101, the voltage ramp for voltage control is run through by specifying a setpoint voltage vDes as a manipulated variable as a function of time.

In measure 102, depending on the voltage UF of the overhead line and the current target voltage vDes, a pulse width ratio PWM Ratio is calculated and transferred to a pulse width modulator 6, which sends a correspondingly modulated signal to the gate driver 5 of the semiconductor switch S1 ( 1 ) supplies.

the 7b shows the course of the voltage UV (cf. 1 ) and the current IV (cf. 1 ) at the input capacitance and the switching behavior of the gate driver 5, each over time t for an exemplary simulated scenario. It can be clearly seen that the voltage UV is constantly and evenly adapted to the voltage UF of the catenary and that during precharging, in contrast to that in FIG 6b only a limited current IV flows. An amplitude and a duration of the oscillations can also be reduced by means of the embodiment of the method shown.

the 8a and 8b illustrate the formation of an electrical connection between a vehicle and an overhead line, with the pre-charging being carried out with the aid of an embodiment of the method, ie the input capacitance is pre-charged according to the method.

In the embodiment, it is provided that the precharging is carried out by means of a current control via a continuous control and pulse width modulation control of the gate driver 5 of the pulsed controlled semiconductor switch S1 (cf. 1 ) is carried out.

the 8a shows a corresponding block diagram. In a first measure 100, a voltage ramp with a gradient dU/dt is calculated as a function of the voltage difference between the voltage UF of the overhead line and the voltage UV at the input capacitance and a predefined pre-charging time tPrecharge.

In measure 101, a desired current value iDes is calculated on the basis of the known input capacitance CV and the calculated gradient dU/dt.

A PI current controller 7 regulates the current based on the calculated setpoint current iDes and a measured actual current iAct and calculates a setpoint voltage vDes as a manipulated variable for this purpose.

In measure 102, a pulse width ratio PWM Ratio is calculated as a function of the voltage UF of the overhead line, the calculated current target voltage vDes' and a current actual voltage uvAct and transferred to a pulse width modulator 6, which sends a correspondingly modulated signal to the gate driver 5 of the semiconductor switch S1 ( 1 ) supplies.

the 8b shows the curves of the voltage UV (cf. 1 ) and the current IV (cf. 1 ) at the input capacitance and the switching behavior of the gate driver 5, each over time t for an exemplary simulated scenario. It can be clearly seen that the voltage UV is evenly adjusted to the voltage UF of the catenary and that during precharging, in contrast to that in FIG 6b only a limited current IV flows. An amplitude and a duration of the oscillations can also be reduced by means of the embodiment of the method shown. Furthermore, a maximum value of the current IV can be further reduced by this embodiment of the method (cf. 7b and 8b at time t = 0.02 s).

the 9a and 9b illustrate the formation of an electrical connection between a vehicle and an overhead line, with the pre-charging being carried out with the aid of an embodiment of the method, ie the input capacitance is pre-charged according to the method.

In the embodiment it is provided that the pre-charging is carried out by means of a cascade control of the voltage with a subordinate current control via a continuous control and pulse width modulation control of the gate driver 5 of the pulsed controlled semiconductor switch S1 (cf. 1 ) is carried out.

the 9a shows a corresponding block diagram. In a first measure 100, a target voltage vDes is calculated based on the voltage UF of the overhead line, which is used as a reference variable for a voltage regulator 9. Based on this and a current actual voltage uvAct, the voltage regulator 9 regulates the voltage and provides a setpoint current iDes as a manipulated variable for this purpose.

The calculated setpoint current iDes is used as a reference variable for a PI current controller 7. A PI current controller 7 regulates the current based on the calculated current setpoint iDes and an actual current value iAct and calculates a setpoint voltage vDes' as a manipulated variable.

In measure 101, a pulse width ratio PWM Ratio is calculated as a function of the voltage UF of the overhead line, the calculated target voltage vDes' and a current actual voltage uvAct and transferred to a pulse width modulator 6, which sends a correspondingly modulated signal to the gate driver 5 of the semiconductor switch S1 ( 1 ) supplies.

the 9b shows the curves of the voltage UV (cf. 1 ) and the current IV (cf. 1 ) at the input capacitance and the switching behavior of the gate driver 5, each over time t for an exemplary simulated scenario. It can be clearly seen that the voltage UV is adapted asymptotically to the voltage UF of the catenary and that during precharging, in contrast to that in FIG 6b a lower current IV flows. Oscillations no longer occur and the current only flows in one direction.

the 10a and 10b illustrate the formation of an electrical connection between a vehicle and an overhead line, with the pre-charging being carried out with the aid of an embodiment of the method, ie the input capacitance is pre-charged according to the method.

In the embodiment it is provided that the pre-charging is carried out by means of a current control via a two-point control with direct control of the gate driver 5 (cf. 1 ) of the at least one pulsed-controlled semiconductor switch S1 (cf. 1 ) is carried out.

the 10a shows a corresponding block diagram. In a first measure 100, a voltage ramp with a slope dU/dt is calculated as a function of the voltage difference between the voltage UF of the overhead line and the voltage UV of the input capacitance and a predefined pre-charging time tPrecharge.

In measure 101, a desired current value iDes is calculated on the basis of the known input capacitance CV and the calculated gradient dU/dt.

A two-point current controller 10 regulates the current based on the calculated current setpoint iDes and an actual current value iAct and controls the gate driver 5 for this purpose.

the 10b shows the curves of the voltage UV (cf. 1 ) and the current IV (cf. 1 ) at the input capacitance and the switching behavior of the gate driver 5, each over time t for an exemplary simulated scenario. It can be clearly seen that the voltage UV is evenly adjusted to the voltage UF of the catenary and that during precharging, in contrast to that in FIG 6b only a limited current IV flows. An amplitude and a duration of the oscillations can also be reduced by means of the embodiment of the method shown.

the 11a and 11b illustrate the formation of an electrical connection between a vehicle and an overhead line, with the pre-charging being carried out with the aid of an embodiment of the method, ie the input capacitance is pre-charged according to the method.

In the embodiment it is provided that the pre-charging is carried out by means of a cascade control of the voltage with a subordinate current control via a two-point control with direct control of the gate driver 5 of the semiconductor switch S1 controlled in a pulsed manner (cf. 1 ) is carried out.

the 11a shows a corresponding block diagram. In a first measure 100, a target voltage vDes is calculated based on the voltage UF of the overhead line, which is used as a reference variable for a voltage regulator 9. Based on this and a current actual voltage uvAct, the voltage regulator 9 calculates a target current iDes.

A two-point current controller 10 regulates the current based on the calculated current setpoint iDes and an actual current value iAct and controls the gate driver 5 for this purpose.

the 11b shows the curves of the voltage UV (cf. 1 ) and the current IV (cf. 1 ) at the input capacitance and the switching behavior of the gate driver 5, each over time t for an exemplary simulated scenario. It can be clearly seen that the voltage UV is adapted asymptotically to the voltage UF of the catenary and that during precharging, in contrast to that in FIG 6b course shown a lower current IV flows. Oscillations no longer occur and a larger current only flows in one direction. Furthermore, an initial current compared to that in the 9b be reduced in the course of the current IV shown (cf. time t=0.005 s).

In all of the embodiments, it can be provided that a target value limitation is provided for a respectively controlled variable.

In 12 a schematic representation of a further embodiment of the circuit arrangement 1 is shown. The embodiment is basically like that in FIG 1 embodiment shown formed. The same reference symbols designate the same features and terms.

In addition, this embodiment provides that an electrical connection between the overhead line 20 and a high-voltage network 60 of the vehicle 50 is disconnected by means of the semiconductor switches S1, S2 in the event of an overvoltage, an overcurrent and/or a fault current occurring. For this purpose, vehicle 50 has a sensor system, for example, which is formed from a current sensor 54 , a residual current sensor 55 and a safety controller 56 . The current sensor 54 is arranged outside the circuit arrangement 1, but is also used by the circuit arrangement 1. Based on an overcurrent and/or fault current signal 57, which is provided by safety controller 56 when there is an overcurrent or fault current, control device 2 opens semiconductor switches S1, S2 and thereby interrupts the electrical connection between high-voltage network 60 of vehicle 50 and the Overhead line 20. An overvoltage can be detected by means of the voltage sensors, not shown, for the voltages UF and UV, so that the semiconductor switches S1, S2 can also be opened by means of the control device 2 in the event of an overvoltage.

In the 13 a schematic representation of a section of a further embodiment of the circuit arrangement is shown. In this embodiment, it is provided that for each of the poles or each polarity, after precharging, an additional electrical contact is formed in parallel with the respective semiconductor switch S1, S2 by means of a respective mechanical switch M1, M2. As a result, hybrid switches can be formed which make it possible to reduce conduction losses of the semiconductor switches S1, S2 in normal operation and still be able to precharge an input capacitance in a controlled manner.

Furthermore, further mechanical switches M3, M4 connected in series can be provided, with which all-pole galvanic isolation can be established if necessary. The series-connected mechanical switches M3, M4 are normally closed and also during precharging.

In any case, provision is made for the mechanical switches M1, M2, M3, M4 to be switched in a manner coordinated with the semiconductor switches S1, S2. The mechanical switches M1, M2, M3, M4 are also controlled by the control device 2 of the circuit arrangement 1 (cf. 1 ) controlled.

Reference List

1

circuit arrangement

2

control device

3

electrical overvoltage protection device (lightning protection)

4

snubber circuit

5

gate driver

6

pulse width modulator

20

catenary

50

vehicle

51

pantograph

52

pantograph control

53

pantograph

54

current sensor

55

residual current sensor

56

safety control

57

Overcurrent and/or residual current signal

S1, S2

semiconductor switch

C

capacity

CV

input capacitance

du/dt

slope (voltage)

FP

fuse

iAct

actual current

iDes

target current

Mx

mechanical switches

PWM Ratio

pulse width ratio

R

Resistance

t

time

tPrecharge

preload time

tx

time

IV

Current (pre-charge current input capacitance)

UF

voltage (catenary)

UV

Voltage (Input Capacitance)

u

detected voltage

vDes

target voltage

vDes'

target voltage

uvAct

actual voltage

100-103

measures

Claims (9)

Method for precharging an input capacitance (CV) of a vehicle (50) when forming an electrical contact with an overhead line (20), wherein a two-pole electrical contact between the overhead line (20) and the vehicle (50) is produced pole by pole by means of at least one semiconductor switch (S1, S2), and wherein at least one of the semiconductor switches (S1) is controlled in a pulsed manner in such a way that the input capacitance (CV) of the vehicle (50) is precharged to a target voltage (vDes), wherein an electrical contact for one of the poles is formed by closing the at least one semiconductor switch (S2) assigned to the pole after a mechanical contact has been formed between a pantograph (53) and the overhead line (20), and wherein only the at least a semiconductor switch (S1) for precharging the input capacitance (CV) is driven in a pulsed manner. procedure after claim 1 , characterized in that the pre-charging is carried out by means of a voltage control and pulse width modulation control of gate drivers (5) of the at least one semiconductor switch (S1) controlled in a pulsed manner. procedure after claim 1 , characterized in that the pre-charging is carried out by means of a current control via a continuous control and pulse width modulation control of gate drivers (5) of the at least one semiconductor switch (S1) controlled in a pulsed manner. procedure after claim 1 , characterized in that the pre-charging is carried out by means of a current control via a two-point control with direct control of gate drivers (5) of the at least one semiconductor switch (S1) controlled in a pulsed manner. procedure after claim 1 , characterized in that the pre-charging is carried out by means of a cascade control of the voltage with subordinate current control via a continuous control and pulse width modulation control of gate drivers (5) of the at least one pulsed controlled semiconductor switch (S1). procedure after claim 1 , characterized in that the pre-charging is carried out by means of a cascade control of the voltage (UV) with subordinate current control via a two-point control with direct control of gate drivers (5) of the at least one pulsed-controlled semiconductor switch (S1). Method according to one of the preceding claims, characterized in that the pre-charging is also carried out after a loss of contact between a pantograph (53) and the overhead line (20) and a reconnection. Method according to one of the preceding claims, characterized in that at least for one of the poles after the pre-charging, an additional electrical contact is formed in parallel with the at least one semiconductor switch (S1, S2) by means of at least one mechanical switch (M1, M2, M3). Circuit arrangement (1) for a vehicle (50) for precharging an input capacitance (CV) of a vehicle (50) when forming an electrical contact with an overhead line (20), comprising: at least one semiconductor switch (S1, S2) for each pole of an electrical connection between the overhead line (20) and the vehicle (50), a control device (2), wherein the control device (2) is designed to drive at least one of the semiconductor switches (S1) in a pulsed manner in such a way that the input capacitance (CV) of the vehicle (50) is precharged to a setpoint voltage (vDes), and the semiconductor switch switches (S1, S2) in such a way that an electrical contact for one of the poles is formed by closing the at least one semiconductor switch (S2) assigned to the pole after a mechanical contact has been formed between a pantograph (53) and the overhead line (20), and that only the at least one semiconductor switch (S1) assigned to the other electrical pole is driven in a pulsed manner for precharging the input capacitance (CV).

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