SU995004A1 - Method and device converting active power to digital code - Google Patents

Description

pulse shaper of stable duration 2. The disadvantages of this method are low speed and accuracy caused by the following reasons: the need to integrate the frequency of the second frequency-pulse sequence over two periods of the electrical network, which leads to a large conversion time and the occurrence of additional error with inequality the first T. and the second T periods of the conversion cycle, the absolute value of which is; Ho, by the need to use for the purpose of inverting the input signals of operational amplifiers operating in the inversion mode, which introduce additional error from the bounce; . the need to use for switching input signals (their direct and inverse values) to voltage transformers — the frequency of analog switches, which limits the frequency of input signals or the need to increase the conversion time to a number of periods greater than two but multiple two at high input frequencies. The aim of the invention is to increase speed and accuracy. The goal is achieved by the fact that, according to the method involving the conversion of input voltages and currents into proportional voltages, the transformation of the received voltages into. the frequency of the pulse sequences, the formation of pulses in the first of the sequences with a stable duration and the integration of the second pulse sequence with a change in the direction of integration, the integration is carried out during one period of the input voltage, and the change in the direction of integration is carried out at the moments of a change in the amplitude of the pulses of a stable duration of the first sequence In an apparatus for carrying out the method comprising an input unit whose inputs are connected to an input 4 W Inam, the first and second voltage converters to a pulse frequency zero-body, whose input is connected to the first output of the input unit, an inverter, a reversible counter, a shaper of stable duration, the first and second elements And, the delay line, the recorder are entered, and the inputs of the first and the second voltage transducer ui pulse frequency is connected to the outputs of the input unit, the output of the first voltage to frequency converter is transmitted through a pulse shaper of stable duration The second element And through the inverter - with the input of the second element And, the second inputs of the first and second elements And are connected to the output of the second voltage converter into the frequency of the pulses, and their outputs - to the inputs of the reversible counter, the installation input of which is a delay line connected to the output null-organ and the first input of the recorder, the second input is connected to the output of the reversible counter. An outline of an apparatus for implementing a method for converting active power to a digital code is presented. The device contains an input unit 1, voltage converters 2 and 3 into the following frequency, null-organ 4, shaper 5 pulses stable. duration, inverter 6, elements And 7 and 8, the reversible counter 9, the recorder 10 and the delay line 11. The inputs of the input unit 1 are connected to the input signal buses, and the outputs, respectively, with the input of the voltage-to-frequency converter 2, the input of the null-organ 4, and the input of the voltage converter 3 into the frequency. Input unit 1 may consist of a calibrated resistor for converting input current i (t) to voltage and (t), proportional to it, input measuring transformers and voltage for matching input, circuits with the instrument circuit and operational amplifiers for normalized and input signals. Multivibrators with controlled discharge of capacitors can be used as converters 2 and 3 voltages to frequency, Schmidt trigger 4, organ 4, generator of 5 pulses of stable duration counter with recalculation factor of St 0 pulse duration of stable duration, f reference frequency. The conversion of active power into a digital code according to the proposed method in the proposed device is performed continuously during each period of the monitored network with a period of current i (t). At the beginning of each period, the zero-body, 4 generates a signal allowing the transfer of the number from the reversible counter 9 to the result recorder 10 and the reset of the reversible counter 9 to zero. Input voltages U (t) and current i (t) are fed to the input of input unit 1, where i (t) is converted to voltage

U. (t) is proportional to it, and U (t), U (t) is normalized,

0. (t) U

where K. is the proportionality coefficient.

Next, the voltages C (t) and U (t) are fed to the inputs of the voltage converters 2 and 3, respectively, to the frequency of the pulser, where they are converted into pulse sequences with pulse frequency equal to

),

, de and - the frequency of the following pulses at the outputs of the converter 2 and 3 voltage to pulse frequency at zero input signals) Si, Su sensitivity, respectively, of the converters 2 and 3. With the appearance of each pulse at the output of the voltage converter 2 into the pulse frequency, at the output a generator of 5 pulses of stable duration; a pulse of stable duration T is formed; during which the pulses from the output of the converter 3 voltage to the pulse frequency through the element 7 pass to the input of the reversible counter 9.. In the intervals between pulses of stable duration (“a out; invert6p 6 - a single potential) pulses from the output of the voltage converter 3 into the pulse frequency are received through the element 8 on the subtracting the reversing counter 9. At the same time TX current oscillations i (t) in the last Hc1 accumulate the number of pulses: “6b,.) V uttbf, tt)“ € op%% and taking into account (3) after some transformations we get LYx -1 ° 2.1% UWU tt) V 2, 00) io.so.at4f and t „za {) -. -SuUWJa -Ml For a periodic variable signal, the integral of this signal over its period is zero, i.e. -Tc; - J2B, UWT € o dt - 0 15 UiWTc-Tioo: - o 4i, V) U) dt - o

   ° oG "

Taking into account (2), t5) and (6), expression (4) is converted to

inc) - f iSi5oTcTVt; iUU) ut) ilt

Then, setting the sensitivity S,

, given or Sy in accordance with the expressions J according to. )

“AM

will get

5 Wj, 4t) - v-lHt.mt) at - KP,

 It l

Claims (2)

1.0 where 2, l --aK Si uTc-rV p is the active power. The proposed method of converting active power into a digital code has improved speed and accuracy due to the fact that the conversion of power is important for one oscillation period of the input signals, and not two, as a well-known method, as a result of which the conversion time is reduced to two times. In addition, the error of the DM disappears (see, expression (1) 1 is called; inequality of the first and second periods. Conversion cycle when converting power by a known method. In the device for implementing the proposed method, there are no operational amplifiers-inverters, as a result of conversion. by means of this device, it is reduced by the magnitude of the chattering error of the operadion amplifiers in comparison with the known active-power digital-to-digital power converter. Vision of analog switches in the proposed device leads to an increase in its speed in comparison with the known converter. Phos. Invention. 1. Method of converting active power into a digital code, including converting input voltages and currents into proportional voltages, converting received voltages the frequency of the pulse sequences, the formation of pulses in the first of the sequences with a stable duration and the integration of the second pulse sequence with a change in Integration Directions, which are based on the fact that, in order to increase speed and accuracy, the integration is carried out during one period of the input voltage, and the direction of integration is changed at the moments of a change in the amplitude of the pulses of a stable duration of the first sequence. 2. A device for carrying out the implementation of claim 1, comprising an input the block which is connected to the input buses, the first and second voltage converters to the pulse frequency, the zero-organ whose input is connected to the first output of the input block, an inverter, a reversible counter, a shaper of stable duration, characterized in that the first and the second elements And, the delay line, the recorder, the inputs of the first and second voltage to frequency converters are connected to the outputs of the input unit, the output of the first voltage to frequency converter through the forms A stable pulse generator is connected to the input of the first element I and through the inverter to the input of the second element I, the second inputs of the first and second elements I are connected to the output of the second voltage converter into the frequency of the pulses, and the outputs of the elements I to the inputs of the 5 opposite counter, the setting the input of which through the delay line is connected to the output of the zero-organ and the first input of the recorder, the second input of which is connected to the output of the reversible counter. sources of information taken into account in the examination 1. USSR Authorship No 34790f, KL. H 03 K 13/02, 1971, 2. Authors certificate of the USSR 530452, cl. H 03 K 13/20, 1975.