DE102007041247A1 - Device and system for signal processing of a voltage - Google Patents

Abstract

The invention relates to a device (1) for signal processing of an electrical input voltage (30, 50), wherein each value of the input voltage is associated with a value of an electrical output voltage (34, 54) based on a piecewise linear assignment function, wherein the assignment function at least two having contiguous allocation areas (60_1, ..., 60_n) adjustable by a respective threshold voltage (31_1, ..., 31_n, 51_1, ..., 51_n), wherein the allocation function in the one allocation area (60_1) having the lowest Value of a limit voltage (31_1, 51_1) is a degree function defined by a slope and an offset, wherein the assignment function of each further allocation range is determined by the combination of the assignment function of the respectively adjacent assignment range having the next lower value of the limit voltage further degree function results, characterized in that ss at least one limit value module (10_1, ..., 10_n, 13_1, ..., 13_n) is present, which from the input voltage (30, 50) and a respective predetermined limit voltage (31_1, ..., 31_n, 51_1,. .., 51_n) provides a respective limit module output voltage (32_1, ..., 32_n, 52_1, ..., 52_n) which is supplied both to a basic module (11, 14) and to an output module (12, 15) Basic module (11, 14) to the input voltage (30, 50) each one of the respective ...

Description

The The invention relates to a device for signal processing an electrical input voltage, wherein each value of the input voltage by a piecewise linear assignment function is exactly one value of an electrical output voltage is assigned, wherein the assignment function at least two each have contiguous allocation areas, which are separated by a respective limit voltage are adjustable, wherein the assignment function in that allocation area with the lowest value of a limit voltage is a degree function, which by a slope and an offset is defined, with the assignment function of each other Assignment area from the combination of the assignment function of the each adjacent allocation area, the next smaller Value of the limit voltage, with another degree function results.

It is well known that for overload protection of electrical loads, in particular of asynchronous motors, calculation models to emulate the warming be used. Input variables such Calculation models are common Measured values showing the time course of the three phase currents of the asynchronous motor describe. Asynchronous motors can Connected loads of a few kW up to several MW have

The heat generation in an asynchronous motor is dependent on the time, the power, which at its inner ohmic resistors as a thermal entry accrues, and other thermal factors such as heat capacity, thermal conductivity, heat radiation and / or ambient temperature. These factors are in the implementation of a calculation model according to the desired Accuracy of the calculation model.

In particular, for calculating the thermal input of power, it is advantageous to perform this according to the known formula p (t) = i ² (t) · R, where p (t) the instantaneous power, i (t) the instantaneous current and R the equivalent effective resistance within the asynchronous motor is where the thermal power dissipation occurs. These quantities are usually available by measurement.

As a result, is for safe and easy implementation of thermal overload protection in an overload protection device, for example, in an overload relay, a squaring of the measured current signal of at least one of three phase conductors necessary. Usually Such squaring is done by means of a well-known Diode circuit. The disadvantage of this approach, however, is that the ambient temperature significantly influences the diode circuit, the accuracy of the quantities determined thereby being significant sinks.

outgoing From this prior art, it is an object of the invention, a Device and a system for signal processing, in particular the squaring, an electrical variable to specify their transfer function not or only to a very small extent of the ambient temperature dependent is.

These The object is achieved by a device for signal processing of an electrical Voltage with the features specified in claim 1.

Accordingly marked the device for signal processing of an electrical Voltage of the type mentioned in that at least one Limit value module is present, which consists of the input voltage and a respective definable limit voltage a respective Grenzwertmodulausgangsspan voltage which provides both a basic module and an output module supplied is that the basic module to the input voltage one each the respective limit module output voltage resulting voltage added as an offset and this sum voltage as an auxiliary voltage to the Output module supplied is which one of these from the respective limit module output voltages resulting factor corresponding to the respective slope of the grades multiplied and provides as output voltage.

The transfer function is achieved by the device according to the invention thus divided into several allocation areas, within which the assignment of an output value to an input value of the voltage according to a degree function, characterized by respectively an offset and a slope, takes place. The respective upper voltage limit an assignment range is by a predetermined voltage value determined, the lower voltage limit corresponds to the upper limit of the adjoining allocation area. The lowest allocation area is unlimited downwards, which is topmost allocation area unlimited upwards.

The number of assignment regions results from the number of limit value modules increased by the number one, wherein according to the invention at least one limit value module is present, resulting in a minimum of two assignment ranges. By a correspondingly high number of threshold modules can be in an advantageous manner any realize high accuracy of the mapping function to be displayed.

each Grade is characterized by an offset and a slope. The respective offsets are determined by the basic module, the gradients the respective degrees through the output module.

Especially the realization of the device according to the invention by electrical Standard components, such as a resistor, a Capacitor or operational amplifier, enables a robust construction and a high degree of independence the assignment function of the ambient temperature, whereby possible temperature dependencies the standard components compensate each other.

On this way an arbitrarily accurate assignment function can be realized, especially a second-order parselet which is suitable to achieve the squaring of a voltage signal.

In Advantageously, the input voltage supplied to the device according to the invention is proportional to the measured load current of at least one phase of an asynchronous motor.

On that way Especially easy is the thermal power input in one Determine asynchronous motor.

In a further embodiment the device according to the invention is the signal of the input voltage previously rectified, provided the assignment function to be displayed for magnitude equal input voltages the same values of the output voltage. This is for example an origin parabola function of the second order of the case.

On this way is the effort to replicate the assignment function especially low. Only the positive or the respectively negative range of the function is to be approximated by degrees.

In a development of the embodiment are several devices according to the invention for signal processing of an input voltage in parallel arranged.

So Is it possible, the caused by all three phases of an induction motor thermal Entry to determine, especially in the unbalanced load condition.

Especially Cheap it is when the device according to the invention for further processing of an electrical voltage, an evaluation device is downstream.

By This evaluation device is based on the characteristics, for example of the asynchronous motor and based on the current through the supply lines of the asynchronous motor and squared signals Determination of the registered thermal power possible. In a further step is based thereon on the basis of a thermal Model through integration over a period of time the determination of the temperature of the asynchronous motor in dependence the time possible. In this way, a thermal overload protection of the asynchronous motor feasible, which in case of overload initiated a shutdown of the induction motor.

In In another advantageous embodiment, the determined Temperature of the asynchronous motor from the evaluation provided as output.

so the device and / or individual modules have at least one standard electronic component, such as a resistor, a Capacitor, a diode and / or a differential amplifier. By using such standard components, the structure can be and / or the link realize the individual modules in a particularly simple and robust manner.

In a further development of the subject invention are and / or several modules together with continue to use the device meaningful components, such as one or more backups, Switching devices and / or display devices, in a common casing arranged.

On this way is the number of protection and / or monitoring one or more electrical loads, in particular asynchronous motors, necessary overall components reduced and the assembly respectively the maintenance of the device is simplified.

Especially Cheap is the modular design of the device in multiple cases, though for further protection and / or monitoring one or more electrical loads, in particular asynchronous motors, additional functionalities to be realized. These functionalities work together on one Part of the available in the device Voltage signals back. By such a modular structure, the number of required individual modules and / or components are advantageously reduced.

In an advantageous embodiment are additional functionalities in the same housing integrated, as the inventive device. This is special Cheap, if multiple functionalities predominantly be shared, for example, protection against thermal Warming at an asynchronous motor and unbalanced load protection.

So will be cheaper Way further reduces the number of housings used.

In a further embodiment have the housings, in which individual and / or several modules and / or components arranged are, if possible flexible connection options on, for example, at least one screwable and / or clampable Connectivity. Also a common, pluggable connection bus system for information, Current and / or voltage transmission is conceivable.

So let yourself through the modular design, the handling of one or more housing significantly to reduce.

The Task is still solved by a system for calculating the power of a thermal one-day in an asynchronous motor, wherein a measuring signal of the current through at least one of the three supply lines of the asynchronous motor provided in the form of a voltage signal proportional thereto is, characterized in that the voltage signal on the input side a device for signal processing of an electrical voltage according to the claims 1 to 14 available and squares through the device and that squared Voltage signal can be linked by means of an evaluation with other parameters.

Consequently is advantageously from the multiplication of the voltage signal with in particular the equivalent Ohmic resistance of the asynchronous motor an electrical active power determined, which corresponds to the thermal entry.

Further advantageous design options are the other dependent claims refer to.

Based the embodiments illustrated in the drawings are intended to Invention, further embodiments and other advantages closer to be discribed.

It demonstrate:

1 a schematic diagram of the device for signal processing of an electrical input voltage,

2 an example of a mapping function and

3 a circuit example of a device with three allocation areas.

1 FIG. 3 shows a block diagram of an exemplary embodiment of the device according to the invention 1 is with which a piecewise linear function is realized with multiple allocation areas. An input voltage 30 will be several limit modules 10_1 , ... 10_n supplied as the first limit module input, only three are shown, but in principle any number of these limit modules 10_1 . 10_2 ... 10_n installed / can be connected in parallel and thus allow any arbitrary approximation of the assignment function. Each limit module 10_1 , ... 10_n is the individually definable limit voltage as each second threshold module input 31_1 , ... 31_n fed. Is the value of the input voltage 30 greater than the respective predefinable limit voltage 31_1 , ... 31_n , so gives the relevant limit module 10_1 , ... 10_n as limit module output 32_1 , ... 32_n in each case a first voltage value, otherwise in each case a second voltage value, which is preferably 0 V. As an alternative to the real voltages, voltage information is also conceivable, for example digitized numerical values.

The Minimum number of limit modules is logically one, so that this results in a minimum of two allocation areas, namely a first for all Values of the input voltage which are less than or equal to the predefinable Limit voltage, and a second for those values of input voltage, which are larger than are the limit voltage.

The input voltage 30 will continue to be a basic module 11 fed. Further input variables for the basic module 11 are the threshold module outputs 32_1 , ... 32_n , In the basic module 11 be the input voltage 30 predefinable offsets added, namely exactly one offset per Grenzmodmodulausgangsgröße 32_1 , ... 32_n , The amount of each offset for each threshold module output 32_1 , ... 32_n as well as a base offset can be defined in the basic module or stored as values. Thus, by linking the different offsets in the different allocation areas for each allocation area a separate offset can be realized. The output size of the basic module 11 is an auxiliary voltage 33 , which is an output module 12 is supplied.

Further input variables for the output module 12 are the threshold module outputs 32_1 , ... 32_n every limit module 10_1 , ... 10_n , The output size of the output module 12 is an output voltage 34 , which results from the connection of the auxiliary voltage 33 with a predeterminable in the output module basis multiplication factor. Another multiplication factor, by which the ratio of the output voltage 34 to the auxiliary voltage 33 can be influenced results from the output module 12 supplied limit module output variables 32_1 , ... 32_n , Each of the aforementioned input quantities is a separate one in the output module 12 specifiable, multiplication factor assigned. Thus, by combining the different multiplication factors in the different assignment regions, a separate multiplication factor can be realized for each assignment region, which corresponds to the slope of the straight line of the assignment function.

In this way, a predeterminable assignment function between input voltage 30 and the output voltage 34 realized. The voltage values for such a device according to the invention are usually between 0 V and 10 V.

2 schematically shows a diagram of an assignment function of an exemplary output voltage 44 to an exemplary input voltage 40 with three-dimensional limit tension 41_1 . 41_2 . 41_3 and the resulting four allocation ranges 60_1 . 60_2 . 60_3 . 60_4 , The respective allocation regions and the respective assignment functions are selected such that an approximation of a second-order pararelax is used, as used for squaring a signal. The negative branch of the parabola is not shown in this example, because the imaginary input signal is assumed to be rectified in this case, and thus only values of the exemplary input voltage 40 greater than or equal to zero can occur.

3 illustrates a concrete circuit example of a device according to the invention for signal processing of another input voltage 50 where two more limit modules 13_1 . 13_2 are shown.

The other limit modules 13_1 . 13_2 are realized in this example by a commercial operational amplifier in each case, in the example shown, a first N3 for the other first threshold module 13_1 and a second N4 for the further second threshold module 13_2 , The power supply of the operational amplifier is effected by a marked connection VCC. The specification of another first limit voltage 51_1 and another second limit voltage 51_2 is done by a separate voltage source, which is not shown in more detail.

Another basic module 14 also has an operational amplifier, in this case N1. The gain of the operational amplifier fixed by the resistors R7 and R8 is compensated by the resistor divider R1 and R2 so that the amplification factor of the further basic module 14 one is. By a suitable choice of the resistors R1, R2, R7 and R8, however, this factor can be changed as desired. The offsets are taken into account via the resistors R3 to R6, where R5 and R6 are the base offset of the further basic module 14 take into account and R3 or R4 the offset by the other modules 13_1 respectively 13_2 is determined. The further basic module 14 represents another output module 15 another auxiliary voltage 53 to disposal.

Also the further output module 15 in this example has an operational amplifier, namely N2. The basic gain factor of the other output module 15 is determined by the resistors R11 and R12. This factor can still be changed by a parallel connection of the resistors R9 and / or R10 to R11. In series connection with R9 and R10 are in each case the transistors V1 and V2, whose conduction values of the further output module 15 supplied wide ren limit module output voltages 52_1 . 52_2 depending on whether they are conductive or non-conductive.

1

contraption for processing an input voltage

10_1

first limit module

10_2

second limit module

10_n

nth limit module

11

basic module

12

output module

13_1

additional first limit module

13_2

additional second limit module

14

additional basic module

15

additional output module

30

input voltage

31_1

first limit voltage

31_2

second limit voltage

31_n

nth limit voltage

32_1

output voltage of the first threshold module

32_2

output voltage of the second limit module

32_n

output voltage of the nth limit module

33

auxiliary voltage

34

output voltage

40

exemplary input voltage

41_1

exemplary first limit voltage

41_2

exemplary second limit voltage

41_3

exemplary third limit voltage

44

exemplary output voltage

50

Further input voltage

51_1

Further first limit voltage

51_2

Further second limit voltage

52_1

Further Output voltage of the first limit module

52_2

Further Output voltage of the second limit module

53

Further auxiliary voltage

54

Further output voltage

60_1

first allocation area

60_2

second allocation area

60_3

second allocation area

60_4

fourth allocation area

60_n

nth allocation area

Claims (15)

Contraption ( 1 ) for signal processing of an electrical input voltage ( 30 . 50 ), wherein each value of the input voltage is determined by means of a piecewise linear assignment function exactly one value of an electrical output voltage ( 34 . 54 ), wherein the assignment function has at least two respectively adjacent assignment regions ( 60_1 , ..., 60_n ), which by a respective limit voltage ( 31_1 , ..., 31_n . 51_1 , ..., 51_n ) are adjustable, wherein the assignment function in that allocation area ( 60_1 ) with the lowest value of a limit voltage ( 31_1 . 51_1 ) is a degree function, which is defined by a slope and an offset, wherein the assignment function of each further assignment range results from the combination of the assignment function of the respectively adjacent assignment range, which has the next lower value of the limit voltage, with a further degree function, characterized that at least one limit value module ( 10_1 , ... 10_n . 13_1 , ... 13_n ), which consists of the input voltage ( 30 . 50 ) and a respective definable limit voltage ( 31_1 , ... 31_n . 51_1 , ..., 51_n ) a respective threshold module output voltage ( 32_1 , ... 32_n . 52_1 , ... 52_n ), which both a basic module ( 11 . 14 ) as well as an output module ( 12 . 15 ), that the basic module ( 11 . 14 ) to the input voltage ( 30 . 50 ) one each from the respective limit module output voltage ( 32_1 , ... 32_n . 52_1 , ... 52_n ) added as an offset voltage and this sum voltage as auxiliary voltage ( 33 . 53 ) the output module ( 12 . 15 ) which is supplied with one of the respective limit module output voltages ( 32_1 , ... 32_n . 52_1 , ... 52_n ) multiplied by the respective slope of the grades and multiplied as output voltage ( 34 . 54 ). Contraption ( 1 ) according to claim 1, characterized in that the input voltage ( 30 . 50 ) is proportional to a measured current. Contraption ( 1 ) according to claim 1 or 2, characterized in that the input voltage ( 30 . 50 ) is rectilinear. Contraption ( 1 ) according to one of the preceding claims, characterized in that a plurality of assignment functions can be represented by a plurality of individual devices arranged in parallel. Contraption ( 1 ) according to one of the preceding claims, characterized in that at least one output voltage ( 34 . 54 ) is supplied to an evaluation module. Contraption ( 1 ) according to claim 5, characterized in that a size proportional to an electrical power can be determined by the evaluation module. Contraption ( 1 ) according to claim 6, characterized in that the determinable by the evaluation module of the electric power proportional size over a certain period of time is integrally processed further. Contraption ( 1 ) according to claim 7, characterized in that at least one output of the Auswertemoduls represents the thermal heating of an electrical load. Contraption ( 1 ) according to one of the preceding claims, characterized in that at least one module has at least one electronic component. Contraption ( 1 ) according to one of the preceding claims, characterized in that a plurality of modules are arranged in a single common module. Contraption ( 1 ) according to one of the preceding claims, characterized in that the modules and / or components used are arranged in a common housing. Contraption ( 1 ) according to claim 8 to 11, characterized in that the modules used and / or further components are arranged in at least two different housings. Contraption ( 1 ) according to one of the preceding claims, characterized in that further modules and / or components for further functionalities are integrated in at least one housing and / or integrated. Contraption ( 1 ) according to claim 11 to 13, characterized in that a housing has at least one klemmbare plug connection option and / or a screw connection option for connecting lines. System for calculating the performance of a thermal One-day in an asynchronous motor, being a measuring signal of the current by at least one of the three supply lines of the asynchronous motor in Is provided in the form of a voltage signal proportional thereto, characterized in that the voltage signal on the input side a device for signal processing of an electrical Tension according to the claims 1 to 14 available and squares through the device and that squared Voltage signal by means of an evaluation device with other parameters linkable is.