LU505697B1 - Measuring device for measuring a current intended for energy supply - Google Patents

Abstract

The invention relates to a measuring device for measuring a current provided for energy supply, comprising a measuring circuit with two connection contacts (X3, X4; X5, X6), via which a current (I1) provided for energy supply is conducted through the measuring circuit for its measurement via a current input and current output, wherein the measuring circuit is equipped with a voltage limiter (DX) and comprises a shunt (RX), characterized in that adjacent to the connection contacts (X3, X4; X5, X6) the shunt (RX) is arranged as the first component of the measuring circuit and electrically connects the current input and current output, in particular so that the signal input of the measuring circuit is designed with low resistance. Furthermore, the invention relates to a charging station which has a measuring device according to one of claims 1 to 8 and a control device for controlling a charging process with electrical current.

Description

' LU505697

Measuring device for measuring a current intended for energy supply

Description

The invention relates to a measuring device for measuring a current intended for energy supply and to a charging station with such a measuring device.

Such a measuring device is usually set up to measure the current supplied via an electrical line, whereby the current must usually flow through the measuring device for measurement and recording. If a voltage is also detected in this context, the

The electrical energy supplied via the electrical line can be recorded or measured.

Such a measuring device is therefore often used in a

Electricity metering unit, often referred to as electricity meter or power meter, which records the electrical energy transmitted at a metering point. The metering point can be, for example, between a power grid and a household or

industrial plant, but can also be located between two power grids.

The use of extracted energy is sometimes referred to as energy consumption. In this sense, it is also an energy meter.

As a rule, such measuring instruments are also mounted on a mounting plate (e.g.

domestic installation) or using DIN rail systems. If MID compliant, i.e. in accordance with the EU

If the measurement is carried out in accordance with the Measuring Instruments Directive, i.e., Directive 2014/32/EU (effective April 20, 2016), the measuring instrument must be regularly inspected and replaced. This entails increased effort.

An ever increasing area of application for such measuring devices can be found, for example, in various charging stations, especially in the wake of the growing e-

Mobility, such as the wall boxes or other e-mobility

Charging stations. AC (alternating current) charging stations typically achieve charging capacities of up to 22 kW, whereas DC (direct current) charging stations

2 LU505697 significantly higher charging capacities of up to 500 kW can be achieved.

Short circuits can be particularly problematic for such measuring instruments, if this results in significantly larger

Short-circuit currents occur at the measuring device, but also due to other

Short-term overcurrents

The object of the invention is to create an overload-capable measuring device, in particular to create an overload-capable measuring device suitable for high currents such as those encountered during the charging process using charging stations in the field of e-mobility.

The solution to the problem of creating an overload-capable measuring device is according to the

The invention is represented by a measuring device having the features according to claim 1 and by a charging station having the features according to claim 9.

Appropriate refinements and further developments are the subject of the respective further dependent claims.

The invention proposes a measuring device for measuring a current intended for energy supply, which comprises a measuring circuit with two connection contacts, via which a current intended for energy supply is fed to its

Measurement can be or is carried out via a current input and current output through the measuring circuit, whereby the measuring circuit is connected to a

The measuring device according to the invention is characterized in particular by the fact that the shunt is the first component of the measuring device and is located next to the connection contacts.

measuring circuit and the current input and current output are arranged electrically interconnected, so that the signal input of the

measuring circuit is designed to be low-impedance.

If the shunt is connected in parallel to the rest of the measuring circuit, a significant current component can be diverted or the measuring range of the measuring device can be increased without causing damage. This has the advantage that even high nominal currents, especially high DC nominal charging currents, can be measured, since, depending on the shunt's dimensioning, only a reduced current component is conducted through the rest of the measuring circuit, and at the same time, a potentially higher current, especially short-circuit or short-time current, can be permitted without damage. By means of voltage limitation, the

3 LU505697 the rest of the measuring circuit connected in parallel with the shunt is protected in the event of extreme overcurrent.

A suppressor diode, an active switchable overvoltage limiter, a spark gap or anti-parallel diodes, in particular two anti-parallel diodes, as part of the measuring circuit have proven particularly useful as voltage limiters.

If not only this voltage limitation is connected in parallel to the shunt, but also in

If at least one resistor is connected in series with the voltage limiter, in particular a resistor is connected in series with the current input or current output between the shunt and the voltage limiter, the

Voltage limitation currents are limited again and thus in particular the dimensioning, e.g. the size, of a respective

Voltage limitation can be reduced.

According to a particularly useful embodiment, the measuring circuit of a

Measuring device according to the invention further comprises two, i.e. in particular several, cascade-connected circuit parts, in which the parallel to the

Shunt and in series with at least one resistor

Voltage limitation forms a first circuit part of these two circuit parts and the second circuit part has a further voltage limitation connected in parallel to the shunt and in series with at least one further resistor.

This allows for a gradual signal attenuation and consequently a gradual

Limitation of the signal values present in the measuring circuit, i.e. in particular current and/or voltage values.

In practical implementation, the measuring device also has a measuring transformer connected downstream of the measuring circuit, which is a

Converts a measurement signal representing current into a low-voltage signal, whereby the

The measuring circuit and the measuring transformer are galvanically isolated in a suitable design.

In order to reduce the risk to the personnel, particularly in the event of a short circuit and/or a possible or expected explosion, due to open live parts,

environment and/or by bridging insulation distances, the damage to the

In order to minimize the impact on the environment and thus also on any user, the encapsulation of the measuring transducer within a

Housing excluding the measuring circuit and/or the encapsulation of the measuring circuit wholly or partially within a housing excluding the measuring transformer.

In addition to or as an alternative to the encapsulation shown above, the measuring circuit can also be encapsulated separately within a housing in a suitable embodiment, whereby the connection contacts are accessible from outside this housing for the purpose of connecting electrical cables.

The invention therefore also proposes a charging station with a measuring device designed according to the above statements, which is more expedient

In this way, it also has a control device for controlling a charging process with electrical current.

Further features and advantages of the invention will become apparent from the following

Description of some preferred embodiments with reference to the accompanying drawing, in which:

Fig. 1 shows a simplified circuit diagram of a possible internal electrical

Circuit structure of a charging station connected to a vehicle according to the invention together with a measuring device with a first

Embodiment of a measuring circuit according to the invention for carrying out a charging process with electric current;

Fig. 2 shows a simplified circuit diagram of a possible internal electrical

Circuit design of a measuring device with a further embodiment of a measuring circuit according to the invention, which is arranged within a

Vehicle-connectable or connected charging column can or is used to carry out a charging process with electrical current.

Fig. 3A shows a further embodiment of a measuring circuit according to the

Invention;

Fig. 3B shows a simplified first embodiment of a measuring circuit according to

Invention with two cascade-connected

circuit parts;

Fig. 3C shows a highly simplified second embodiment of a measuring circuit according to the

Invention with two cascade-connected

circuit parts; and

> LU505697

Fig. 4 shows a simplified representation of several embodiments of different

Encapsulation variants within the measuring device according to the invention.

Below is a detailed description of a measuring device for measuring a

The measuring device comprises a measuring circuit with, for example, two connection contacts X3, X4, via which a current |1 provided for the energy supply is passed through the measuring circuit for its measurement via a current input and current output, is equipped with a voltage limiter DX and comprises a shunt RX, which is arranged adjacent to the connection contacts X3, X4 as the first component of the measuring circuit and electrically connects the current input and current output. A charging station is also described in more detail, which is used within the scope of the

Invention such a measuring device and a control device for controlling a

Charging process with electrical current.

First, reference is made to Fig. 1, which shows a simplified

Circuit diagram of a possible internal electrical wiring structure of a charging column connected to a vehicle according to the invention, including a

Measuring device with a first embodiment of a measuring circuit according to the invention for carrying out a charging process with electric current.

Such a charging station has, as shown in the charging column sketched in Fig. 1 and designated there with control 1, a control device for controlling a

Charging process with electrical current. In particular, since charging stations, such as wall boxes or other e-mobility charging stations, such as the charging station outlined in Fig., are usually part of a larger system, the

The control device of the charging station, as shown in Fig. 1, can be connected to another, higher-level controller, whereby the connection is expediently made via a bus, via which extensive data exchange can then also take place. Such a bus can be configured, for example, as a CAN bus or Profibus, although other suitable buses are certainly known to those skilled in the art. After or by connecting the charging station to a vehicle, the control device of the charging station is also known to exchange data with a control device arranged in the vehicle, designated as controller 2 in Fig. 1.

6 LU505697 this data exchange can take place via a bus, as is conventional.

Furthermore, as outlined in Fig. 1, part of the charging station is usually a charge controller that is connected to a power source, in particular to an AC or three-phase network, and regulates the charging current via the controller 1, e.g. via the control line marked ST2 in Fig. 1. Such a charge controller can, for example, also be an analog-to-digital converter or digital-to-analog converter.

Converters include, depending on whether the power source is an AC or

DC source is used and whether the charging current is alternating current (AC) or

Direct current (DC) is to be used. If, as shown in Fig. 1, a

AC or three-phase source is used and as charging current, however, a

If direct current is used, which is then fed via a DC network, the charge controller therefore also conveniently includes an analog-to-digital converter, hereinafter also referred to as ADC.

At least a portion of a direct current provided or made available by the charging station, in particular by its charge controller, via the line marked L+ on the charge controller, as shown in Fig. 1, is thus used as a charging current of a

vehicle and thus according to the example outlined for

Used to supply energy to the vehicle.

For measuring a current 11 intended for energy supply, the

Fig. 1 sketched charging station a possible embodiment of a measuring device, in which

Fig. 1 for the sake of clarity referred to as energy meter with a first

Embodiment of a measuring circuit according to the invention. For measuring the

Power supply 11 are at least two connection contacts

X3 and X4 on the measuring device, through which this current intended for energy supply [1 for its measurement via a current input and

Current output can or will be passed through a measuring circuit of the measuring device.

In particular, based on the embodiment of Fig. 1, the

The current 11 intended for the energy supply is thus initially passed through the measuring circuit of the

measuring device before it is completely or partially, according to the embodiment according to

Fig. 1 over section D, as charging current to the vehicle for the battery stored there

The cable marked L- is used to supply the

Circuit according to the embodiment of Fig. 1 is finally closed. By means of the

! LU505697

The measuring circuit of the measuring device can then at least

measuring signal representing the current intended for the energy supply | for

provided, which, however, in particular for monitoring and

Evaluation of the power supply, can be converted into a low-voltage signal by means of a measuring transformer arranged downstream of the measuring circuit (see all Figs. 1 to 4). According to the exemplary embodiments outlined in the figures, in which direct current is used as the charging current, a

Digital-to-digital converters are used.

As also shown in the embodiment sketched in Fig. 1, the

The measuring circuit of the measuring device has a voltage limiter DX and a shunt RX or the measuring circuit is also made up of these components, among others.

In particular, as shown, it is evident that adjacent to the

Connection contacts X3 and X4, first the shunt RX as the first component of the

measuring circuit and the current input and current output are arranged electrically interconnected. As a result, the signal input of the measuring circuit can preferably be designed with low impedance and thus, in particular due to this low impedance of the signal input, the measuring device can be advantageously

It can also be used in the context of or in the field of e-mobility applications as a suitable overload-capable measuring device.

Dimensioning of the shunt, only a reduced current share through the rest of the

measuring circuit, and at the same time a possible higher current, especially

Short-circuit or short-time current can be tolerated without destruction.

Voltage limitation, in turn, the remainder of the

The measuring circuit can be protected from extreme overcurrents. This allows the voltage measurement path, labeled U3, to be protected in particular in the event of an extreme overcurrent. Providing a resistance value for the shunt RX in the mOhm range or lower has proven particularly useful.

If not only this voltage limiter DX is connected in parallel to the shunt RX, but at least one resistor R3 and/or R4 is connected in series with the voltage limiter DX, which also absorbs voltage again in the event of an overload, in particular a resistor is connected in series to the current input or current output between the shunt RX and the voltage limiter DX, the

Voltage limitation DX carried current can be limited again and thus in particular the dimensioning, e.g. the size, of a respective voltage limitation can be reduced.

8 LU505697

As outlined in Fig. 1, the voltage limit DX has been shown to be

Suppressor diode is shown as a component of the measuring circuit. Alternatively, however, the use of two anti-parallel diodes, an active, switchable overvoltage limiter or spark gap is also possible. The activation of such an active, switchable voltage limiter DX can, for example, be carried out by means of a further circuit accommodated by the charging station or the measuring device, e.g. in the form of a processor, in the embodiment sketched in Fig. 1, for example, by the microprocessor up sketched there. Accordingly, in the embodiment according to

Fig. 2 outlined embodiment of another possible internal electrical

Circuit design of a measuring device, which is installed within a

Vehicle connectable or connected charging column for carrying out a

charging process with electrical current, the

Voltage limitation DX is shown in dashed lines as a box. Also, as can be seen in particular in Fig. 2, the energy measuring device according to the invention does not have to comprise only one measuring circuit, but can also have one or more further measuring circuits, each with two connection contacts X5 and X6, via which a further current [2 intended for energy supply is then passed through the further measuring circuit. Also expediently in addition to

Measurement of a current intended for energy supply, a current applied

Voltage U1, as further sketched in the embodiments according to Figures 1 and 2, is determined. A measuring circuit provided for this purpose is then preferably again a

A measuring transformer is arranged downstream, which in this case then converts a measuring signal U representing the voltage U1 present in a

low voltage signal.

This voltage increase at RX caused by extreme overcurrent, especially large short-circuit current, can only be prevented by a suitable

Since the power cut-off can be very slow in terms of time, additional components such as the one outlined in Fig. 1, a

A switch K2 arranged in the vehicle to protect the energy storage device, in particular a so-called pyroswitch and/or a fuse S1 installed upstream in the charging station, may be necessary.

These components usually have a response time of approximately 100us to approximately 5ms. In addition or alternatively, if a

Current monitoring takes place by means of a monitoring module IDC1 arranged in the charging station, as outlined in the embodiment according to Fig. 1, also the

9 LU505697 the corresponding shutdown of a switch K1 in the charging station, which is suitably arranged for "power shutdown", can be initiated. This can result in reaction times between 10 - 30 ms. If a charge controller is used, as shown in Fig. 1, the shutdown time can usually be further reduced to a shutdown time in the us range, because then the charge controller has internal

Power electronics can be deactivated.

In order to further increase the measuring range of the measuring instrument, especially the

In order to optimally cover the requirements of the measuring transformer included in the low-voltage conversion version, the shunt RX and, if present, the resistor R3 and/or R4 connected in series with the voltage limiter DX are preferably designed so that a nominal current plus an overcurrent factor, e.g., a factor of 10 or greater, can be measured. The overcurrent factor can also be based, for example, on a protective fuse arranged in the charging station for current limitation or shutdown, such as the one shown in Fig. 1.

Fuse S1.

For example, if the measuring device according to the invention is to be used to measure nominal charging currents of, for example, 500A, i.e. the (nominal) current 11 intended for the energy supply is 500A, and at the same time a possible short-circuit current of 70kA, i.e. the (short-circuit) current 11 intended for the energy supply is 70kA, without

Destruction can be permitted, there would be a possible suitable

Dimensioning, in particular based on an embodiment according to Fig. 1, 2 or 3, for example, involves using a voltage limiter that responds at approximately 1V and providing a resistance value of approximately 0.1 mOhm for the shunt RX. In this case, with the (nominal) current I1 of 500A present, the voltage U2 dropped across the shunt RX would be approximately 50mV. Correspondingly, approximately 50mV would drop across the rest of the measuring circuit connected in parallel to the shunt. In this case, the voltage limiter would not yet respond, and approximately 50mV could also be present or dropped at the voltage measuring path U3. However, if a short-circuit current of 70kA is present, the

Shunt RX dropping voltage U2 is therefore about 7V. Thus Uber would be the parallel to the

However, the shunt-connected rest of the measuring circuit also drops by about 7V. In this case, the voltage limiter would therefore respond at about 1V.

Short-circuit current of 70kA can still be permitted without causing destruction, therefore in a practical design approx. 6V further over the

Resistors R3, R4 can be used to compensate for this. In the case of the exemplary

The requirement would therefore be to provide a total resistance value of approximately 1000hm for the resistors R3, R4.

In principle, the voltage applied or dropped on the voltage measuring path of the measuring device can also be further reduced by setting the measuring device according to

Invention, circuit parts connected in series in a cascade manner are provided, as is sketched, for example, in the embodiments according to Figs. 3B, 3C and 4.

This means that the shunt RX can be connected in parallel and in series with at least one

Resistor-connected voltage limiter DX forms a first circuit part of two circuit parts connected in series in a cascade manner, and the second circuit part is a further voltage limiter connected in parallel to the shunt RX and in series with at least one further resistor R3', R4'

DX2. Such embodiments can be seen, for example, in Figs. 3B and 3C. The voltage ultimately present or dropped across the voltage measurement path of the measuring device is labeled U3' in Figs. 3B and 3C.

In detail, Fig. 3B shows, for example, an embodiment in which the first circuit part Y1' outlined therein comprises the shunt RX and, in parallel thereto, the voltage limiter DX connected in series with at least one resistor R3, R4, and a second circuit part Y2 comprises a further voltage limiter connected in parallel to the shunt DX and in series with at least one further resistor R3', R4'

DX2. As an alternative to the embodiment according to Fig. 3B, Fig. 3C shows a

Embodiment is outlined in which the voltage limiter DX connected in parallel with the shunt RX in series with the at least one resistor R3, R4 forms a first circuit part Y1 of these two circuit parts and the second

Circuit part Y2 has a further voltage limiter DX2 connected in parallel to the shunt RX in series with at least one further resistor R3', R3'.

The first one connected to the shunt RX or formed together with it

Circuit part Y1 or Y1' thus limits the voltage U3 to a first level in the event of an overload. By means of the second circuit part Y2, the voltage U3 present at the input is then further reduced by a further amount in a further stage, whereby a further current limitation is achieved by the resistors R3' and R4', and the voltage U3' thus has a lower second level than the voltage U3. Since the voltage U3' at the voltage limiter DX2 is thus further reduced, its dimensioning can be influenced by the

Cascade structure can also be designed smaller compared to the voltage limitation DX.

With reference to an embodiment as outlined in Fig. 1, a causal

Short-circuit fault for an overcurrent acting on the measuring device, i.e. for a very large current value 11 and consequently for a large value U3/DX below the

Assuming that switch K1 is switched on, essentially in each of the

Sections A, B, C, D, E and F occur.

If the causal fault is in section A or B, the energy of the

Energy storage device via the shunt RX. If the causal error is in the section

C, the grid or the energy storage is short-circuited via the shunt RX. If the causal fault is in section D, E, or F, the energy storage will be discharged at the short-circuit point, with additional current being drawn from the charging station.

Current is supplied to this point via the shunt RX. However, if switch K1 is off, the current flow can only be maintained by the vehicle's energy storage system, with sections B and C then being supplied with current via the shunt RX and becoming particularly critical.

In order to minimize the risk to the environment in the event of a short circuit, the resulting destruction, or even an explosion that may be expected,

environment and thus protect any user/person/operator from

To protect against these dangers, various measures are integrated into the measuring device according to the invention in a practical development. Since the dangers can be quite diverse, e.g. dangers from flying parts, dangers from open live parts and/or dangers, also of an indirect nature, from

For parts that bridge internal insulation gaps to 24V, complementary but also alternative measures are preferred. Hazards and their

Risk assessment is defined in the standard IEC 61010 or the corresponding EN 61010, in particular IEC 61010-1:2010 or the

EN 61010-1:2010, whereby the invention is of course based on the standard applicable at the time of application.

Furthermore, printed circuit boards have often been used to fulfill wiring tasks for current measurement inputs. However, this also causes significant disadvantages with regard to short-circuit loading. Because a short-circuit load on a

Printed circuit board can in particular cause delamination of the layers, a complete

Separation of the layers into individual layers, so that overpressure conditions from the

interior, to the surface, a complete melting of conductive layers, especially copper layers, the formation of a plasma cloud, an uncontrolled arc formation and/or extreme overpressure in the involved

circuit area, to name just a few possible effects.

In particular, it must be ensured that no insulation gaps are affected by a short circuit. Consequently, no components, especially components subject to increased mechanical and electrical stress, may be blown off and subsequently create a bridge to the

Low voltage range, in particular according to Figs. 1 and 2 the section

G. In the event of a short circuit, the

measuring device or measuring device area no live parts for the

User/human/operator must be freely accessible.

According to a first preferred further training, at least the

The measuring circuit and the measuring transformer are galvanically isolated from each other, as is the case in all

Fign. and is designated by the reference symbol GT in Fig. 1.

The areas enclosed by dashed lines in Figures 2, 3B, 3C and 4, cf. in particular those marked Y1, Y1'Y2, Y3, Y4, Y5, Y6, represent various suitable possibilities for mechanical encapsulation. For example, if the

If the measuring transformer is encapsulated within a housing that excludes the measuring circuit and/or the measuring circuit is encapsulated entirely or partially within a housing that excludes the measuring transformer, this can also be prevented by live parts reaching the 24V area and bridging section G. In addition or alternatively, a further preferred embodiment provides for the measuring circuit to be encapsulated separately within at least one housing, with the connection contacts being accessible from outside this housing to the

are accessible for the purpose of connecting electrical cables.

Claims (9)

Patent claims 1. Measuring device for measuring a current intended for energy supply, comprising a measuring circuit with two connection contacts (X3, X4; X5, X6), via which a current intended for energy supply (11) is guided through the measuring circuit for its measurement via a current input and current output, wherein the measuring circuit is equipped with a voltage limiter (DX) and comprises a shunt (RX), characterized in that adjacent to the connection contacts (X3, X4; X5, X6) the shunt (RX) is arranged as the first component of the measuring circuit and electrically connects the current input and current output to one another, in particular so that the signal input of the measuring circuit is designed to be low-impedance. 2. Measuring device according to claim 1, wherein a suppressor diode, two antiparallel diodes, an active switchable overvoltage limiter or a spark gap is part of the measuring circuit for voltage limitation (DX). 3. Measuring device according to claim 1 or 2, wherein the voltage limiter (DX) is connected in series with at least one resistor (R3, R4) in parallel to the shunt (RX), in particular a resistor (R3, R4) is connected between the shunt and the voltage limiter in series with the current input or current output. 4. Measuring device according to claim 3, wherein the measuring circuit comprises two circuit parts (Y1, Y2; Y1, Y2) connected in series in a cascade manner, in which the voltage limiter (DX) connected in parallel with the shunt (RX) together with the resistors (R3, R4) connected between the shunt (RX) and the voltage limiter (DX) forms a first circuit part (Y1') of these two circuit parts, and the second circuit part (Y2) comprises a further voltage limiter (DX2) connected in parallel with the shunt (RX) and two further resistors (R3', R4') connected between the two voltage limiters (DX, DX2). one of which is connected in series to the current input and one in series to the current output, or in which the voltage limiter (DX) connected in series with the at least one resistor (R3, R4) in parallel with the shunt (RX) forms a first circuit part (Y1) of these two circuit parts and the second circuit part (Y2) has a further voltage limiter (DX2) connected in series with at least one further resistor (R3', R4") in parallel with the shunt (RX). 5. Measuring device according to one of claims 1 to 4, wherein the measuring circuit is followed by a measuring transformer which converts a measuring signal (I) representing the current provided for the energy supply into a low-voltage signal. 6. Measuring device according to claim 5, wherein the measuring circuit and the measuring transducer are galvanically isolated. 7. Measuring device according to one of claims 5 or 6, wherein the measuring transducer is encapsulated within a housing excluding the measuring circuit and/or the measuring circuit is wholly or partially encapsulated within a housing excluding the measuring transducer. 8. Measuring device according to one of the preceding claims, wherein the measuring circuit is separately encapsulated within a housing and the connection contacts are accessible from outside this housing for the purpose of connecting electrical lines. 9. Charging station comprising a measuring device according to one of claims 1 to 8 and a control device for controlling a charging process with electrical current.