Title of Invention

DEVICE FOR MEASURING THE CONSUMPTION OF ELECTRICAL ENERGY

Abstract

A device for measuring the consumption of electrical energy is presented, which starting from voltage signals and current signals (u, i) which can be fed to the inputs (2, 3) of the circuit, determines an actual power signal which with the help of a calibrating block (10) is multiplied by a calibration factor. This calibration factor is stored in a non-volatile, programmable fixed value memory (12) which comprises of several irreversible programmable memory cells (13). These are designed in such a way that irreversible re-programming of any random memory cell (12) would effect an increase in the calibration factor. Thus any eventual manipulation of the energy meter by re-programming the calibration factor, e.g. after an official calibration, would always lead to an increase of the measured value which would not be desired by the manipulator.

Full Text

Description Device for Measuring the Consumption of Electrical Energy This invention pertains to a device for measuring the consumption of electrical energy. Measuring devices or energy meters for electrical energy, which in colloquial language is referred to as current meter or kilowatt-hour-meter (KWh-meter), serve the purpose of determining the electrical energy fed into an electrical supply network or the electrical energy drawn from an electrical supply network. For this, the electrical instantaneous power drawn by a consumer from the electrical supply network is integrated over the time. The instantaneous electrical power is thereby obtained from the product of the current and the voltage. Such types of electrical energy meters serve the purpose of electrical power supply companies, EVU, as the calculation basis for billing their clients, the consumers. In the document DE 198 42 241 Al, an electrical meter is given. This comprises of an integrated input module with analogous/digital-converter and a multiplier agent. Besides, there are also inputs for feeding voltage and current. It is further foreseen that during manufacture of the meter, compensation/equalisation information can be stored. In order to reduce the cost of drawing electrical energy, there are attempts on the part of the consumer to manipulate electrical energy meters in such a way, that an electrical energy lower than what is actually drawn is indicated. To safeguard against such undesired, manipulating interventions, the EVU puts seals on the energy meters. These however only have a limited protection effect. Particularly in case of modern, digitally working electrical energy meters produced on semiconductor base, a manipulation of the energy reading can be attempted by re- programming the concerned electronic components. It is the task of this invention to present a device for measuring the consumption of electrical energy, which on the one hand is integrated on a chip, and on the other hand, the protection against undesirable manipulation with the intention of reducing the measured energy quantity against the actually drawn quantity, is improved. This task is fulfilled as per the invention by'means of a device for the consumption of an electrical energy, which has the following: - A first input for feeding a voltage signal; - a second input for feeding a current signal; a multiplier which is coupled with the first and second inputs and which gives an intermediate signal at its output as a function of the voltage signal and current signal; - a calibration block which is coupled with the output of the multiplier and with a non- volatile memory and multiplies the intermediate signal of the multiplier with a calibration factor; - an integrator which is coupled with the calibration block and prepares a calibration energy measuring value at its output; and - the non-volatile memory which comprises of several irreversible programmable memory cells for storing the calibration factor, in such a way that a re-programming of any random memory cell results in an increase of the calibration factor. The measuring device is also referred to below as meter circuit. According to the presented principle, electrical voltage and electrical current is fed at the first and second input, preferably as time-continuous and value-continuous analogous signals of the meter circuit. With the help of the multiplier, the instantaneous drawn electrical power is determined by multiplication of voltage and current. In the subsequently connected calibration block, the determined electrical power is multiplied by a calibration factor and finally, from the thus obtained calibrated instantaneous power value an energy measuring value is formed by means of integration over time or by accumulation of a final number of measured values of power. Calibration of an electrical energy meter is advantageous, as on account of production-related parameter fluctuations which could lead to value tolerances of components. Furthermore, on account of ageing-related drift effect and other reasons for standard variations, measuring errors could occur which would be undesirable. According to the above-mentioned principle, the non-volatile memory which is foreseen for storing the calibration factor, is designedin such a way that the subsequent re-programming of a random memory cell which is not covered by the non-volatile memory, could effect an increase in the calibration factor. The individual programmable memory cells are thereby programmable in an irreversible manner. Such types of irreversible programmable memory cells are known in the form of so-called fuses, as well as in the form of programmable diodes, which one can convert into a short circuit by overloading in the high-resistance direction, i.e. so-called Zener-zapping. Apart from the already mentioned components, obviously also other programmable cells can be used. Depending on the type of programmable memory cells used, the calibration factor to be derived in the non-volatile memory is coded according to the present principle in such a way, that in case of subsequent re-programming of the memory cells,"irrespective' of which selection of programmable memory cells are re-programmed, one constantly gets the effect of an increase in the calibration factor. Thus it is ensured that in case of unwanted tampering of the meter circuit with the intention of manipulating it in such a way that the meter indication is lower than the actually drawn electrical energy, one always has an increase of the measured quantity energy with respect to the actually supplied energy quantity. An increase in the calibration factor by subsequent re-programming of the memory cells accordingly leads to the situation, that the electrical meter shows more kilowatt hours than actually drawn, in any case not lesser. A calibration factor can, for example, be programmed during or immediately after production, or within the framework of an official calibration of the meter circuit. According to a preferred design of the present invention, the non-volatile memory comprises of the programming input for programming the memory cells. The programming of the memory cells can be done with a parallel or serial programming input of a programmable fixed value memory. As is usual in the case of such types of memory, addressing the individual memory cells can take place with the help of line-coders and split-end coders. The programmable memory cells are thereby arranged in a matrix form, e.g. in a quadratic matrix. According to a further preferred design form of the present invention, the programmable memory cells each comprise of a diode which on loading with an energy impulse goes over irreversibly into a low-resistance condition. Such types of programmable fixed value memories which one can transform by overloading in high-resistance direction from an electrical high-resistance condition into an electrical short circuit, are also known as anti-fuses. By using such programmable memory cells, according to the present principle, initially all programmable memory cells should ideally be in high- resistance condition. According to this principal, the lowest adjustable calibration factor is coded, in that all programmable memory cells are in high-resistance conducting condition, and the highest adjustable calibration factor is coded, in that all programme memory cells are in a low-resistance conducting condition. By means of reprogramming in an irreversible sequence from high-resistance to low-resistance conducting condition, the calibration factor can subsequently only be increased, however cannot be reduced. According to the present principle it is therefore insignificant whether only one, a certain selection or all the programmable memory cells get re-programmed. In an alternative, similarly preferred design form of the present invention, the programmable memory cells each comprise of a fuse, which on applying an energy impulse goes over irreversibly from a low-resistance to a high-resistance conducting condition. These fuses are generally designed with the help of thin metal bridges. On being subjected to energy impulse, e.g. a current impulse or voltage impulse, they go over irreversibly from a very low-resistance conducting condition to a practically unlimited high-resistance conducting condition. Regarding coding of the calibration factor, the following is subsequently true: the lowest adjustable calibration factor is coded, in that all fuses are in low-resistance conducting condition and the highest adjustable calibration factor is coded, in that all fuses or programmable memory cells are in a high-resistance conducting condition. According to the present invention, while coding the calibration factor one should subsequently take into account, that by irreversible transporting of a random memory cell or random selection of memory cells from low-resistance to the high-resistance conducting condition, constantly an increase in the calibration factor is effected. According to a further preferred design form of the present invention, a pulse generator is connected at the output of the integrator, which prepares a coded output signal proportional to the calibrated energy measured value provided at the output of the integrator. Accordingly, the coded output signal of the pulse generator is a measure for the electrical energy measured by the meter circuit, e.g. since a re-setting of the energy measured value in the integrator. According to a further preferred design form of the present invention, an analogous/digital converter is foreseen for each of the first and second inputs with the multiplier. The analogous/digital converter coupled with the first input of the meter circuit converts an analogous fed voltage signal into a digital voltage signal, which is available preferably time- discreet and value-discreet or at least value-discreet. Accordingly, the analogous/digital (A/D) converter coupled with the second input of the meter circuit converts the current signal which can be fed from the input side and which is available with the analogous signal into a digital signal which is present at least as value- discreet and preferably time-discreet and value-discreet. Apart from a quantification error which is unavoidable, the digital current and voltage signals which can be derived from the A/D converters on the output side are proportional to the analogous current and voltage signals fed to the input side. The A/D converters enable a quick, trouble-free and reliable working digital signal processing of the current and voltage signals, particularly their multiplication to an instantaneous power value, as well as with multiplication and calibration factor and finally the accumulation of the determined, calibrated power values in the integrator. According to a further preferred design form of the present invention, for coupling of the A/D converters and the multiplier a digital filter is provided, which is connected on the input side to the output of the respective analogous/digital converter and on the output side with one of the inputs of the multiplier. The advantage of the digital filters is that they allow a suppression of higher harmonics of the signals occurring during quantification in the A/D converters, which could lead to falsification in the measured result in the subsequently connected multipliers. According to a further preferred design form of the present invention, the non-volatile memory is designed for storing the calibration factor in binary coded manner. As the memory cells of programmable fixed value memories in relationship to their conducting conditions can generally assume only two logical conditions, either high- resistance or low-resistance, the binary coding is particularly suitable for coding the calibration factor by means of fixed value memories. According to a further preferred design form of the present invention, the meter circuit is designed as integrated and electronic circuit. According to a further preferred extension of the meter circuit, the non- volatile memory is designed in such a way that the calibration value which can be derived on the non-volatile memory can only assume positive values. The calibration value is stored in the non-volatile memory without any sign. The calibration values can thereby assume values from a range, e.g. between 0.5 and 2, which would then be multiplied by the measured instantaneous power values. Further details and advantageous extensions of the invention are part of the sub claims. The invention is explained below on the basis of a design example and the drawings. The following are shown: Fig. 1 A simplified block circuit diagram of a first, model design form of the meter circuit as per the invention on the basis of selected circuit blocks; and Fig. 2 the model coding of the calibration factor in the non-volatile memory in a meter circuit as shown in fig. 1 on the basis of selected calibration values. Fig. 1 shows a block circuit diagram of a meter circuit for electrical energy mounted as integrated circuit on a chip 1. This has a first input 2 for feeding a voltage signal u, a second input 3 for feeding a current signal i as well as an output 4 from which a calibrated measured value can be derived, which is a measure for an electrical energy quantity dependent on a current signal i and voltage signal u and integrated over a definite time. In details, the meter circuit comprises of two analogous/digital converters 5, 6 with an input each for feeding an analogous signal, which is connected to the first or second input 2, 3 of the meter circuit. On the output side of the analogous/digital converters 5, 6 respectively a digital filter 7, 8 is connected. The outputs of the digital filters 7, 8 are connected to an input of the digitally operating multiplier 9. The multiplier 9 prepares at its output an intermediate signal formed by multiplication of the current signal and voltage signal i, u, which is a measure for instantaneous electrical power, however not calibrated. The output of the mixer 9 is connected to a calibrating block 10. The calibrating block 10 has a further multiplier 11 with two inputs, out of which a first input is connected to the output of the multiplier 9 and a second input is connected to a non-volatile memory 12. The non-volatile memory 12 comprises of several irreversible programmable memory cells 13. Furthermore, the non- volatile memory 12 comprises of a programming input 14 for programming the irreversible programmable memory cells 13. The output of the additional multiplier 11 in the calibrating block 10, on which a calibrated signal is readied, which represents instantaneous electrical power P, is connected to the input of an integrator 15 which integrates the instantaneous electrical power P over time and provides an energy meter value W at its output. The output of the integrator 15 is connected to the input of a pulse generator 16 which provides the actual energy measured value at its output 4. With the help of the electrical energy meter integrated on a chip, as shown in fig. 1, the actual electric power is constantly determined, which is obtained by the product of voltage signal u and current signal i. The voltage u is thereby generally the rated voltage of an electrical supply network, e.g. 230 volts AC. The actual electrical power derived from the voltage signal and current signal is provided at the output of the multiplier 9. With the calibrating block 10 the electrical power which is provided at the output of the multiplier 9 is multiplied with a calibration factor. This calibration factor helps to correct standard fluctuations internally on the chip bearing the meter circuit 1, as well as also externally, e.g. caused by line impedance. The calibration factor is determined after completion of the meter circuit during calibration of the electrical energy meter. Now the calibration factor is constantly multiplied by the actual electrical power in such a way, that at the output of the calibrating block 10 one obtains an electrical instantaneous power P corrected by the calibration factor. This corrected electrical instantaneous power P is continuously accumulated in the integrator 15. With the help of the calibration factor, subsequently especially production-related standard fluctuations from the component values of the integrated meter circuit 1 are compensated. In this way, the result of the energy meter reading, namely the accumulated energy measured value available at the output of the integrator 15 is significantly improved with respect to precision. The calibration factor is thereby stored in the non-volatile memory 12 in such a way that a subsequent changing of bits, i.e. a re-programming of individual programmable memory cells, irrespective of the selection of the re-programmed memory cells, always leads to an increase in the calibration factor and hence also to an increase in the electrical instantaneous power, so that any manipulation of the energy meter would not be of any advantage to a manipulator. The non-volatile memory 12 comprises of several irreversible programmable memory cells arranged in a matrix. Each of the programmable memory cells can assume one of two possible conditions, zero or one. It is a property of a non-volatile memory that the programmed conditions of the programmable memory cells can be retained even when a supply voltage of the meter circuit is switched off. The programmable memory cells are irreversible programmable, i.e. their memory condition which generally is present in the form of an electrical conducting condition, can only be programmed in one direction, for example from high-resistance to low-resistance or from low-resistance to high-resistance. Such types of non-volatile and irreversible programmable memory cells, depending on the design, are known as fuses or anti-fuses. The programmable memory cells 13 are realised in the present design example as diodes, which by overloading in high-resistance direction can be converted into a short circuit. Alternatively, one can however also use other programmable memory cells, e.g. floating-gate-mosfets, which is similarly suitable as PROM, Programmable Read Only Memory. In case of programmable floating-gate-mosfets of such types, the insulated floating gate is charged during programming, so that the threshold voltage of the mosfet shifts continuously. Fig. 2 shows on the basis of a design example the coding of the calibration factor in the non- volatile memory 12 which in this case comprises of 16 programmable memory cells. The starting condition of the programmable memory cells is a logical zero, which in the case of the application of diodes foreseen here represents a high-resistance conducting condition. In the table as shown in fig. 2, in the first column the calibration factor decimal is shown, in the second column the hexadecimal, in the third column the binary coded value, respectively for four example values, namely for the calibration factor 0.5; 1.0-1 LSB; 1.0 and 2.0-1 LSB. LSB denotes thereby the least value bit, the so-called Least Significant Bit. The available table accordingly shows a calibration factor which can be adjusted in a range from 0.5 to 2.0. This calibration factor, as already explained on the basis of the description of fig. 1, is continuously multiplied with the actual determined instantaneous power value. Of course, in practical realisations, several further calibration factors can be coded. Fig. 2 merely shows a selection of calibration factors on the basis of the table. The binary coding without any sign bit allows a simple multiplication. In the present example, in which the greatest adjustable calibration factor is 2.0 - 1 LSB, the decimal point of the binary coding is foreseen between both the maximum value bits. For example, the binary coded number 1100 could denote a decimal number 1.5 and a binary coded number 1010 could denote a decimal number 1.25 etc. In the binary representation as shown in fig. 2, a logical zero corresponds to the starting condition of the irreversible programmable memory cell, whereas a logical one gives that condition which the memory cell has after carrying out an irreversible condition change, i.e. after a re-programming. One can identify that in the binary coding according to the table shown in fig. 2, a random re-programming of one or several memory cells, i.e. in the present case, condition transition from a zero to a one, always leads to an increase of the calibration factor. The principle in question is supposed to be made further clear on the basis of an additional coding example with four-bit-binary representation. One can assume that the original condition of the non-volatile memory for storing the calibration factor is 0000. As again between both the left bits, i.e. between both the maximum value bits, the comma-position is supposed to represent a decimal number, the bit sequence 1000 represents the decimal number 1.0, so that the 1 has to be programmed. If any other random bit is changed, say within the framework of a manipulation attempt, e.g. the second bit, then the new binary represented calibration factor isl0l0 which denotes the decimal factor 1.25. One can identify that the calibration factor has increased. Alternative to the already presented, binary coding of the calibration factor, one could assume that the original condition of the non-volatile memory is represented by the binary, four-bit- word 1111 and a programming of the calibration factor is supposed to take place by changing the logical condition from one to zero. Accordingly, the logical one, on application of a diode as programmable element, would represent its high-resistance conducting condition. If in this case, for a calibration of an energy meter a decimal value of 1.375 is supposed to be set as calibration factor, then a bit sequence 1011 should be programmed. However, here one could for example make the second bit from the right to zero and thereby retain the number 1001, which could correspond to the decimal number 1.125. This calibration factor would however be lower, so that a manipulation attempt as desired by the manipulator would lead to a reduction of the indicated energy quantity. Thus a manipulation would work to the advantage of the manipulator. In case of an alternative use of a non-volatile memory which has irreversible programmable memory cell, in which however the initial condition of the programmable memory cells are indicated by logical ones, then on applying the present principle, this should be considered as inverted binary number, according to which the binary depicted calibration factor 0111 would represent the decimal number 1.0. If in this case any one bit is reprogrammed to zero, then accordingly the calibration factor will get similarly increased. Within the scope of the present invention, as an analogy to the already presented single phase meter, the meter circuit can be designed instead of the shown single-phase A.C. meter circuit also as three-phase meter circuit. Furthermore, the described principle can conversely also be extended for a measuring device for the feeding of electrical energy into a supply network, e.g. by the operator of a wind energy plant or a solar energy plant, in which case an intervention for manipulation would refer not to the reduction but to the increase of the calibration factor. WE CLAIM 1. Device for measuring the consumption of electrical energy, which has the following: - a first input (2) for feeding a voltage signal (u); - a second input (3) for feeding a current signal (i); - a multiplier (9) which is coupled with the first and second input (2, 3) and as a factor of the voltage signal and current signal (u, i) gives an intermediate signal at its output; - a calibrating block (10) which is coupled with the output of the multiplier (9) and has a non-volatile memory (12) and the intermediate signal of the multiplier (9) is multiplied by a calibration factor; - an integrator (15) is coupled with the calibrating block (10) and which readies a calibrated energy measuring value (w) at its output; - whereby the non-volatile memory (12) for storing the calibration factor comprises of several irreversible programmable memory cells (13) and is designed in such a way that a re-programming of a random memory cell (13) effects an increase in the calibration factor. 2. Device as per claim 1, in which the non-volatile memory (12) comprises of a programming input (14) for programming of programmable memory cells (12). 3. Device as per claim 1 or 2, in which the programmable memory cells (12) each comprise of a diode, which on being loaded with an energy impulse, irreversibly moves over from a high-resistance into low- resistance conducting condition. 4. Device as per claim 1 or 2, in which the programmable memory cells (12) each comprise of a fuse, which on being loaded with an energy impulse moves over irreversibly from a low-resistance into a high- resistance conducting condition. Device as per one of the claims 1 to 4, in which at the output of the integrator (15) a pulse generator (16) is connected, which provides a coded output signal proportional to the calibrated energy measured valued (W). Device as per one of the claims 1 to 5, in which for the coupling of the first and second input (2, 3) with the multiplier (9), an analogous/digital converter (5, 6) each is provided. Device as per claim 6, in which for coupling the analogous/digital converter (5, 6) with the multiplier (9) a digital filter (7, 8) each is provided, which is connected on the input side with an output of the analogous/digital converter (5, 6) and on the output side respectively with an input of a multiplier (9). Device as per one of the claim 1 to 7, in which the non-volatile memory (12) is designed to store the calibration factor in binary coded form. Device as per the one of the claim 1 to 8, in which the device is designed as integrated circuit. Device as per one of the claim 1 to 9, in which the non-volatile memory (12) is designed in such a way that the calibration factor derivable from the non-volatile memory (12) can assume only positive values. A device for measuring the consumption of electrical energy is presented, which starting from voltage signals and current signals (u, i) which can be fed to the inputs (2, 3) of the circuit, determines an actual power signal which with the help of a calibrating block (10) is multiplied by a calibration factor. This calibration factor is stored in a non-volatile, programmable fixed value memory (12) which comprises of several irreversible programmable memory cells (13). These are designed in such a way that irreversible re-programming of any random memory cell (12) would effect an increase in the calibration factor. Thus any eventual manipulation of the energy meter by re-programming the calibration factor, e.g. after an official calibration, would always lead to an increase of the measured value which would not be desired by the manipulator.

Documents:

836-kolnp-2004-granted-abstract.pdf

836-kolnp-2004-granted-claims.pdf

836-kolnp-2004-granted-correspondence.pdf

836-kolnp-2004-granted-description (complete).pdf

836-kolnp-2004-granted-drawings.pdf

836-kolnp-2004-granted-examination report.pdf

836-kolnp-2004-granted-form 1.pdf

836-kolnp-2004-granted-form 18.pdf

836-kolnp-2004-granted-form 2.pdf

836-kolnp-2004-granted-form 26.pdf

836-kolnp-2004-granted-form 3.pdf

836-kolnp-2004-granted-form 5.pdf

836-kolnp-2004-granted-reply to examination report.pdf

836-kolnp-2004-granted-specification.pdf

836-kolnp-2004-granted-translated copy of priority document.pdf