SU866491A1 - Electronic electricity meter - Google Patents

Description

The invention relates to the field of measuring electrical energy in direct and alternating current systems.

Known electronic circuit schetchitskov electricity (ESE), in which a signal proportional to the electrical mosh- ⁵ NOSTA, Prepared by using the latitude and the amplitude modulation with subsequent conversion of the signal in frequency by the voltage-frequency converter (VFC) The output · * ® whose pulses are fed to an electronic or electromechanical counter £ 11

The disadvantage of this device is the presence of multiple conversion of * ⁵ input signals. One factor is converted into duration by a latitudinal modulator (PWM), the other factor is converted into amplitude by an amplitude modulator (AM), the PWM AM signal is averaged, converted to frequency, and converted into a number of pulses using a counter. The indicated signal conversion sequence naturally leads to a complication of the circuit and reduces accuracy.

The closest in technical essence to the proposed one is an electronic electricity meter containing a pulse counter, two sources of multiplier signals, an indicator and a pulse-width modulator, consisting of an integrator, to the input of which the outputs of the source of the first signal — multiplier and reference current (voltage) source with a controlled polarity, the control input of which is connected to the output of a comparator covered by positive feedback ', the input of which is connected to the output of the integrator f2j.

A disadvantage of the known device is the design complexity due to the need for multiple signal conversion.

The purpose of the invention is to simplify the design.

This goal is achieved by the fact that in the electronic electricity meter.

containing a pulse counter, two sources of multiplier signals, an indicator and a pulse-width modulator, consisting of an integrator, to the input of which the outputs of the source of the primary signal-multiplier and the source of the reference current (voltage) with controlled polarity are connected, the control input of which is connected to the output of the positive feedback of the comparator, the input of which is connected to the output of the integrator, a reference frequency generator and a second comparator are introduced, which inverts and non-inverts the inputs of which the sources are connected to the output of the integrator and through bipolar keys to the neutral wire of the circuit, the control inputs of the keys are connected to the output of the first comparator, one of the inputs of which is connected to the output of the source of the second signal-multiplier, the output of the second comparator and the output of the reference frequency generator are connected to the corresponding inputs of the two coincidence elements, the output of the first of which is connected to the summing input of the pulse counter, and the output of the second, through the negation element, to the subtracting input of the pulse counter.

In this counter, the difference in the durations of the output pulses of the pulse-width modulator immediately becomes proportional to the instantaneous energy of the signals and it remains only to convert it to the number of pulses, which is done by counting the pulses of the reference frequency generator in the counter. As a result, the circuit is greatly simplified, since the amplitude modulator, filter, and voltage-frequency converter are eliminated. Reducing the number of signal conversions increases the accuracy of the device, and simplifying the circuit leads to an increase in reliability.

In Fig * 1 is a block diagram of a counter; in FIG. 2 - implementation of this circuit on integrated operational amplifiers; in FIG. 3 - timing diagrams of the circuit.

An electronic electricity meter consists of sources 1 and 2 of input signals, one of which is proportional to the current, and the other to the voltage of the controlled network. Sources 1 and 2 of the input signals are connected to the inputs of a pulse-width modulator 3, consisting of an integrator 4, a first comparator 5 with a positive feedback unit 6, a reference current (voltage) source 7 whose polarity is determined by the polarity of the output signal of the first comparator 5, second comparator 8, two antiphase switches 9 and 10, and two resistors 11 and 12. The source 1 of the input signal 5 and the source 7 of the reference current are connected to the input of the integrator 4. Source 2 of the input signal, feedback node 6 and the output of the integrator 4 by are connected to the input of the comparator 5. The output of the integrator 4 is also connected ¹⁰ through the resistors 11 and 12, respectively, to the inverting and non-inverting inputs of the second comparator 8. The indicated inputs through the keys 9 and 10 operating in antiphase are connected to the 15th bus of the device. The control inputs of the keys 9 and 10 are connected to the output of the first comparator 5. The output of the second comparator 8 is the output of a pulse-width modulator 3, it is connected to the first inputs of coincidence elements 13 and 14, to the second inputs of which the output of the reference frequency generator 15 is connected. The output of the coincidence element 13 is connected to the summing input of the counter 25 ka 16, and the output of the coincidence element 14 through the negation element 17 to the subtracting input of the counter 16. The output of the latter is connected to the input of the indicator 18.

The comparator 5 is non-inverting 30 PWM, the circuit of its positive feedback is created by the resistor 6, a diode bridge is used as the source 7 of the reference voltage, the zener diode of which includes the stabilization of the output voltage of the comparator. The keys 9 and 10 are made on field-effect transistors with channels p and η type.

The counter works as follows.

_<0 Suppose that at some point in time indicated on the time diagrams (Fig. 3) t _{0, the} voltage U _o at the output of the comparator 5 is positive, and at the output of the integrator 4 it is equal to zero. Integrator 4 integrates the sum of the voltage Uq and the voltage of the source 1 of the input signal Uj in the negative direction. The key 10 is closed, and the key 9 is open and a negative voltage is supplied to the inverting input of the comparator 8 from the output of the integrator ^{50 of the} rotor 4. In this case, the voltage at the output of the comparator 8 will be positive and the pulses of the generator 4 through the open element 13 will pass to the summing input of the counter 16.

When the negative voltage at the output of the integrator 4 at time 1 becomes equal in absolute value to the sum of the operating voltage of the comparator 5 0ts and the source 2 of the input signal C * j, the comparator 5 will change its sign in a jump. The duration of the time interval t ^ + o is defined as

and _{o +} m ₄ (I) but interchange the inputs of the comparator 8 or the inputs of the counter 16.

It is easy to show that the number recorded in the counter 16 for the period of operation of the circuit T _} 5 is proportional to the energy of the input signals during this time. The period of operation of the circuit T consists of four clock cycles and where T _o is the integrator time constant U _K >1L; and ₀ 7 U _n · When changing the polarity of the comparator 5, the integration speed will change in magnitude and sign, the key 10 will open, and the key 9 will be closed, the polarity of the voltage at the output of the comparator 8 will be reversed and the pulses of the generator 15 through element 14 and element 17 will go to the subtracting counter input 16.

At a point in time, the voltage at the output of the integrator 4 will reach zero and the comparator 8 will again change sign, while the pulses of the generator 15 will again arrive at the summing input of the counter 16. The time interval is equal to _{Uk + 0} .

(2)

At a point in time, the positive voltage at the output of the integrator is 4 veins

⁴ Wo (6) where 4T ₀ y

Putting this expression in (5) we get

Η -.-. ΫώΖ_ _ε .2ο_ et _t .

Dg and ₀ and ^ and _{0 will} compensate for the negative voltage (U _K + UJ. Comparators 5 and 8 will again change the sign of the output signal and the pulses of the generator 15 will be fed to the subtracting input of the counter. The time interval 's is equal to% _t "' and _{0 4} (3) where _{т t} is energy during G.

Thus, for any time interval that is a multiple of an integer number of periods of operation of the circuit, the meter readings are proportional to the energy of the input signals, i.e.

in this device, the pulse-width modulator is multiplying.

If in the known device the relativities> the accuracy of the output pulses are 9 = y! ~ = linearly depends on a single input signal, then in the proposed device the relative difference in duration over four clock cycles linearly depends on the product of the input signals „a ^ + ^ + ^ + ^ 4 U ₀ Ug

Finally, at time -14, the positive voltage at the output of the integrator decreasing again reaches zero, comparator 8 again reverses the polarity to positive and the process described above repeats itself. The time interval is defined as <-t ^{4 0} U _o + U4 (4)

Thus, in comparison with the known, the proposed counter eliminates a number of ₄₀ transformations of the input signals - amplitude modulation, filtering and converting voltage to frequency. The amplitude modulator and converter are excluded from the circuit; voltage — frequency, which ₄₅ greatly simplifies the design of the meter and increases accuracy and reliability.

The number of pulses recorded in the counter during the operation of the circuit will be ^{N =} W VVWo '(5) where is the frequency of the generator 15.

The minus sign in front of (5) indicates that with the accepted polarity of the input signals, the counter readings are negative. To change the counting voltage, sufficient

Claims (1)

(54) ELECTRONIC ELECTRIC COUNTER METHOD The invention relates to the field of measuring electrical energy in DC and AC systems. Circuits of electronic electricity meters (ESE) are known, in which a signal proportional to an electrical distance is obtained by using a latitude and amplitude module, followed by converting this signal into a frequency using a voltage-frequency converter (LFR) and Schloss pulses. which are fed to an electronic or electromechanical counter-w. . The disadvantage of this device is the ampli fi cation of multiple conversion of input signals. One factor is converted to duration by a latitude modulator (PWM), the other factor is amplitude by an amplitude modulator (AM), the PWM AM signal is averaged, converted to frequency and, using a counter, to a pulse. This sequence of signal conversion naturally leads to a complication of the circuit and reduces accuracy. The closest in technical essence to the present invention is an electronic electricity meter containing a pulse counter, two sources of signal multipliers, an indicator of a pulse-width modulator consisting of an integrator, to the Input of which the outputs of the source of the first signal-multiplier and the reference current source are connected (eg with controlled polarity, the control input of which is connected to the output of the comparator covered by the positive feedback, the input of which is connected to the output of the CsJ generator. A disadvantage of the known device is the complexity of the design, due to the need for multiple signal conversion. The purpose of the invention is to simplify the design. This goal is achieved by the fact that in an electronic meter of electric power,. containing a pulse counter, two sources of signals of factors, an indicator and a pulse width modulator connected from the integrator to the input of which are connected the outputs of the source of the primary signal-multiplier and the source of the reference current (voltage) with controlled polarity connected to the output of a comparator covered by positive feedback, whose input is connected to the integrator's output, a reference frequency generator and a second comparator, inverting and non-inverting inputs KOTopoix, are entered through a resistor They are connected to the integrator's output and via opposite keys to the zero wire of the circuit, the control inputs of the keys are connected to the output of the first comparator, one of the inputs of which is connected to the output of the second signal of the multiplier factor, the output of the second comparator and the output of the reference frequency generator are connected to the corresponding the inputs of two coincidence elements, the first of which is connected to the summing input of the pulse counter, and the output of the second through the negative element to the subtracting input of the pulse counter. In this counter, the difference in the durations of the output pulses of the pulse width modulator immediately turns out to be proportional to the instantaneous energy of the signals and it remains only to convert it into a number of pulses, which is done by counting the pulses of the oscillator frequency in the counter. As a result, the circuit is greatly simplified, since the amplitude modulator, filter, and voltage-frequency converter are eliminated. Reducing the number of signal conversions increases the accuracy of the device, and simplifying the circuit leads to increased reliability. FIG. 1 is a block diagram of a meter; on . 2 - re-implementation of this circuit on integrated operational amplifiers; on 4ng. 3 - timing diagram of the scheme. The electronic electricity meter consists of sources 1 and 2 of the input signals, one of which is proportional to the current, and the other to the co-monitored network. Sources 1 and 2 of the input signals are connected to the inputs of the pulse-width modulator 3, consisting of integrator 4, first comparator 5 with node 6 positive feedback, source 7 of the reference current (voltage) polarity 8 14 by the output signal of the first comparator 5, the second comparator 8, two antiphase switches 9 and 10, and two resistors 11 and 12. The input signal source 1 and the reference current source 7 are connected to the integrator input 4. Input source 2, reverse node 6 connection and the output of the integrator 4 under lyucheny to the input of the comparator 5. The output of the integrator 4 is also connected through resistors 11 and 12 respectively and to the inverting input of the second comparator nennvertiruyushemu 8. These inputs via the keys 9 and 1O, rabottayuschie in antiphase, are connected to the zero schine device. The control inputs of the keys 9 and 10 are connected to the output of the first comparator 5. The output of the second comparator 8 is the output of the micron-pulse modulator 3, it is connected to the first inputs of the matching elements 13 and 14, to the second inputs of which is connected to the output of the 15th frequency generator. The output of matching element 13 is connected to the summing input of counter 16, and the output of matching element 14 via negative element 17 to the subtracting input of counter 16. The output of the latter is connected to the input of indicator 18. Comparator 5 is non-inverting and its positive feedback is generated by a resistor 6 , a diode bridge is used as the source 7 of the reference voltage, the diagonal of which includes a zener diode, which stabilizes the output voltage of the comparator. The keys 9 and 1O are made on field-effect transistors with channels of the p and n type. The counter works as follows. Let at some point in time, denoted by the time diagrams (Fig. 3) t (j, the voltage OQ at the output of the comparator 5 is positive, and at the output of the integrator 4 is zero. The integrator 4 integrates the sum of the voltage OQ and the voltage of the source 1 of the input signal The key 10 is closed, and the key 9 is open and the inverting input of the comparator 8 is supplied with a negative voltage from the output of the integrator 4. The voltage at the output of the comparator 8 will be positive and the generator 4 pulses through the open element 13 will pass with umiruyuschy input of the counter 16. When the negative voltage at the output of the integrator 4 at time t becomes equal in magnitude to the sum of the operation voltage of the comparator 5 Oz and the source 2 of the input signal U j, the comparator 5 abruptly changes sign. Duration of the time interval f: - t - tg is defined as where TQ is the constant of the time of the integration of the torus-; Up 7 Un When the polarity of the comparator 5 changes, the magnitude and sign of the integration rate changes, the key 10 is opened, and the key 9 is closed, the polarity of the voltage at the comparator output 8 changes to counter The positive and pulses of the generator 15 through the element 14 and the element 17 arrive at the subtractive input of the counter 16, At time i, the voltage at the output of the integrator 4 reaches zero and the comparator 8 again changes sign, and the pulses of the generator 15 are again fed to the summing input counter 16, the time interval Q t2-fc VT "and, - and At time t, a positive voltage at the output of the integrator 4 compensates for the negative voltage (. Comparators 5 and 8 again change the sign of the output signal and the pulses of the generator 15 are fed to the subtracting input of the counter. The time interval is 3. VuT Finally at time point -fc. positive voltage at the output of the integrator will decrease again to zero, comparator 8 will again change the polarity to positive and the process described above will repeat. The time interval T.r t-1l is defined as Jtc-t i О Uo4U The number of pulses recorded in the meter for the period of operation of the circuit will be equal to (VVS-V -fo oJ |: (5) where d is the frequency of the generator 15. Sign the minus in front of (5) shows that, for the polarity of the input CHrw, the meter readings are negative.To change the counting voltage, it is enough to swap the inputs of the comparator 8 or the inputs of the counter 16. It is easy to show that the number recorded in the counter 16 for the period of operation of the circuit T. is proportional to the energy of the input signals during this time. The period of operation of the circuit T consists of the three cycles and is equal to rt.ft ... t ... and 3 from 4-To 4 By putting this expression in (5) we get N-.MiI .., where Et- is the energy during T. Thus, for any the time interval is a multiple of the integer number of periods of the circuit operation, the meter readings are proportional to the energy of the input signals, i.e. in this device the pulse-width modulator turns out to be multiplying. If, in a known device, relativity is output: the 9 rt pulse linearly depends on one input signal, then in the proposed device the relative difference of durations over four ta that linearly depends on the product of the input signals t:, - «- Ci-i- J + 4- Taknm manner compared with known proposed counter eliminates a number of input signals reobrazovany - ampliudnuyu modulation, filtering, and preobraovani voltage to frequency. The circuit modulates the amplitude modulator on the converter, the single voltage | voltage-frequency switch, which greatly simplifies, the device is countable and contributes to an increase in the accuracy and reliability. Formula Shadow Electronic Meter with Pulse Counter, two sources of multipliers, an indicator and an Irot Amplifier Modulator, which is an integrator with input / output outputs of the source of the first signal multiplier and voltage reference current source controlled polarity. the control input of which is connected to the output of a comparator covered by positive feedback, the input of which is connected to the output of an integrator, characterized in that, for the purpose of simplification, an onop-i frequency generator and a second comparator are entered, the inverting and non-inverting input of which is through resistors connected to the integrator's output and via a neutral-pole to the zero wire of the circuit; the control inputs of the keys are connected to the output of the first comparator, one of the inputs of which is connected to the output of the second signal source, Residents output of the second comparator and an output reference frequency reaepiaTopa connected to respective inputs of the coincidence of two elements, the first output of which is connected to summiruk present input pulse counter and the output of the second turn negation element - to a subtracting input of the pulse counter. Sources of information taken into account in the examination i.Fiereit Horet.ECefclrorrtselier KWfi-ZdMer run down Maase 0,5.- 5iemen5 ZeiiSC rift, 4.T, N4, p 2ВО-2вЗ. i. Neg1e1p, Reinc rotrol, Woieter keli.EbvIgotes + tvg PrOfzafieef .- Siemens -iSHetlirtf-t fg73.47, N -fi P.963-8fe6. MyitsL ;, aw5