SU1168868A1 - Method and device for obtaining squared root-mean-square value of a.s.voltage - Google Patents

Abstract

1. The method of obtaining the square of the rms ac voltage, consisting in linear detection of the monitored signal, quadratic transformation of the predicted voltage and integrating the conversion result, which is characterized by the fact that, in order to increase the accuracy, the integrand function is composed of the total voltage of two stepwise varying voltages, the amplitude of the first of which is set proportional to the amplitude of the detected voltage, and the amplitude of volts Step voltage is less than one step of the amplitude of the first step voltage. 2. A device for obtaining the square of the rms value of the alternating voltage, containing an exponent connected to the input of the device, a first digital-to-analog converter and a series-connected and output integrator connected in series to the device that, in order to increase accuracy, a second digital-to-analog converter, additional integrator, pulse generator, cycle generator, comparison circuit, delay circuit, and logical coincidence circuit, with output An additional integrator is connected to the first signal input of the comparison circuit, to the second (L signal input of which the output of the first digital-to-analog converter is connected, which is also connected to the first input of the adder, to the second input of which the output of the second digital-analog converter is connected, the signal input of which is connected) is connected through the circuit delays from the output of the 00 matching logic circuit, to which the O5 signal is also connected to the first digital-to-analog converter, the control inputs are digital analog converters are connected to the output of the comparison circuit, to which the first input of the matching logic circuit is also connected, to the second input of which a pulse generator is connected, and the third input of the matching logic circuit is connected to the output of the cycle generator and to the control input of the comparison circuit.

Description

1 The invention relates to electrical measuring equipment and can be used in voltmeters of the rms value of alternating voltage. The aim of the invention is to improve the accuracy. FIG. 1 and 2 are time diagrams explaining the essence of the proposed method; in FIG. 3 is a functional diagram of the device that implements the proposed method} in FIG. 4 shows timing charts for devices that work. The device contains rectifier additional integrator 2, circuit 3 comparing generator 4 cycles, pulse generator 5, logic circuit 6 coincidence, circuit7 delay the first 8 and second 9 digital-to-analog converters, adder 10, main integrator 11. Device input 12 is connected to the output of the generator the output of which is connected to the input of the additional integrator 2, the output of the latter is connected to the first signal input of the comparison circuit 3, and in the course of the pulse generator 5 is connected to the second input of the matching circuit 6, to the third input to The generator is connected to the output of a 4-cylinder generator, also connected to the control input of the comparison circuit 3. The output of the comparison circuit 3 is connected to the control inputs of the digital-to-analog converters 8. and 9 and to the first input of the coincidence circuit 6, the output connected to the signal input of the first digital-to-analog converter 8 and through the delay circuit 7 to the signal gy input of the second digital-analog converter 9. Output the latter is connected to the second input of the accumulator 10, to the second input of which the output of the first digits of the analog converter 8 is connected, also connected to the second signal input of the comparison circuit 3, the output of the adder 10 is connected to Foot ode Ba integrator 11 whose output 13 is vkodom device process is carried out as follows. The monitored signal U (t) (Fig. 1a) is subjected to linear detection, which can be either half-wave or half-wave (Fig. 1b). To simplify the formation of a stepped, voltage (Fig. 1g) with an amplitude proportional to the detected controlled voltage, this detected voltage may be subjected to integration (Fig. 1c). The amplitude of the first of the stepwise varying voltages (Fig. 1g) is set proportional to the pre-detected controlled voltage or, if integrated, to the resulting constant voltage (Fig. 1c) The amplitude of the second stepwise varying voltage (Fig. 1 e) one step less than the amplitude of the first step voltage. These two stepwise varying voltages are summed (Fig. 1e), and then the total voltage is integrated (Fig. 1g). When the monitored signal changes by K times the voltsecond area of the first margined step voltage, and consequently, obtained after integrating this stepwise voltage, the DC voltage changes by K times. Let, for example, the voltage U (t) be monitored, the amplitude of which is shown in fig. 2 and a flat line. This voltage is converted to a pulsation, the voltage U2 (t) (Fig. 2 b), and then a constant voltage Uj (t) (Fig. 2 c). In terms of the constant voltage and (1), a step voltage U4 (t) (Fig. 2g) is formed, the amplitude of which is equal to or in the general case proportional to this constant voltage, as well as the second stepwise voltage U5 ( t) (fig. 2 d), the number of steps in which or the amplitude of which is one step less than the amplitude of the first of the stepped varying voltages. If, for example, the first stepwise varying voltage U (t) has four steps, then the second VgM has three steps (Fig. 2 g and 2 d). Then, these two stepwise varying voltages are summed, thus obtaining the total voltage Ug (t) (Fig. 2e), which is then subjected to integration, converting this stepwise sum voltage into a constant voltage (Fig. 2) ). If the amplitude of the monitored voltage U (t) changes, for example, halves, i.e. is 4-U (t) (indicated by the dashed line in Fig. 2a), the magnitude of the pulsating voltage is) and the constant voltage value is (t) (Fig. 2b and 2c). The magnitude of the step voltage 1) 4 (1) is also halved, i.e. instead of four steps, only two steps are formed (shaded in Fig. 2g) and the step voltage Uj- (t) consists of only one step (Fig. 2e). As a result of the summation of these two step voltages of reduced amplitudes, a total step voltage is formed (shaded in Fig. 2 e), the volt-second area of which is equal to the initially generated step voltage U (t). Consequently, the value of the constant voltage and (t) is reduced four times with a decrease in the amplitude of the input controlled voltage by two times. This quadratic ratio between the input variable and voltage is maintained at any change in the controlled alternating voltage. For example, if the alternating voltage is from the initial voltage (Fig. 1a), then the voltages U, j (t) and U3 (t) (Fig. 16 and 1c) change in the same proportions, the first of step voltages has three steps (fig. 1 g) and the second — two steps (fig. 1 e). The volt-second area of the total step voltage (fig. 1 e) is (t), and the integrated constant voltage (FIG. 1 g) is reduced to a value (t). Thus, in this case, the voltage U (t) integrated after the quadratic transformation also varies in proportion to the square of the change in the controlled alternating voltage. The device (FIG. 3) operates as follows. The input controlled voltage Id (Fig. A) is converted into a pulsating and linear rectifier 1 (Fig. 4), and then into a constant voltage Uj proportional to it (Fig. 4) by an additional integrator 2. This constant voltage U, proportional to the input controlled alternating voltage, is fed to the first signal input of the comparison circuit 3. The generator 4 cycles generates a pulse voltage U (Fig. 4), whose frequency is much less than the frequency of the pulse voltage U5- generated by the generator 5 - (Fig. 4). In the initial state, the voltage Ug at the output of the comparison circuit 3 is equal to the logical unit (Fig. 4), therefore, the pulse voltage from the output of the pulse generator 5 passes to the output of the matching circuit 6 and is fed to the signal input of the first digital-to-analog converter 8, starting it. For each pulse received at the signal input of the D / A converter 8, a voltage step is generated by the converter. This step voltage Ug (Fig. 4) goes to the second signal input of the comparison circuit 3, with which the amplitude of the stepped voltage Ug is compared with the value of the constant voltage 02. At the moment of equality of these voltages, the comparison circuit 3 also operates its output appears logical zero signal, which is fed to the control input of the digital-to-analog converter 8, resetting the voltage at its output to zero. At the same time, the output voltage of the digital-analog converter 9, The pulses to the input of which come from the output of the coincidence circuit 6 through the delay circuit 7, as a result of which the voltage at its output increases with a delay of one pulse relative to the input of the digital-to-analog converter 8, therefore the step voltage UQ has one step less than the step voltage Ug. The voltage of the logical zero from the output of the comparison circuit 3, which also arrives after its operation at the first input of the coincidence circuit 6, prohibits the further passage of pulses from the pulse. generator 5 to the output of the coincidence circuit in this cycle of operation of the device. IIosTONfy, during this cycle of operation of the voltage device U "and U, the outputs of the digital-to-analog converters B and 9 remain equal to zero.

The step voltages Ug and Ug are summed in the device adder 10, and the total step voltage from the output of the adder 10 is then averaged using the main integrator 11. The output constant voltage U of the device from the output of the integrator 11 (Fig. 4) is proportional to the square

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Claims (2)

METHOD FOR PRODUCING SQUARE OF RMS VALUE VARIABLE VARIABLE VALUE AND DEVICE FOR ITS IMPLEMENTATION. (57) 1. The method of obtaining the squared 'rms value of the alternating voltage, which consists in linear detection of the controlled signal, quadratic conversion of the detected voltage and integration of the conversion result, characterized in that, in order to improve accuracy, the integrand is made up of the total voltage of two stepwise varying voltages, the amplitude of the first of which is set proportional to the amplitude of the detected voltage, and the amplitude of the second step voltage is less than one step the first step voltage amplitude. 2. A device for producing a squared rms value of an alternating voltage, comprising a rectifier connected to the input of the device, a first digital-to-analog converter, and an adder and integrator connected in series to the output of the device, characterized in that, in order to increase accuracy, a second digital-to-analog converter is introduced into it , an additional integrator, a pulse generator, a cycle generator, a comparison circuit, a delay circuit and a logical coincidence circuit, while the output of the rectifier Through an additional integrator, _ is connected to the first signal input of the comparison circuit, to the second signal input of which the output of the first digital-to-analog converter is connected, also connected to the first input of the adder, to the second input of which the output of the second digital-to-analog converter is connected, the signal input of which is connected through a delay circuit with the output of a matching logic circuit, to which is also connected the signal input of the first digital-to-analog converter, the control inputs of the digital-to-analog converters zovateley connected to the output of the comparison circuit to which is also connected a first input coincidence logic circuit, a second input is connected to a pulse generator and a third input coincidence logic circuit connected to the output cycle of the generator and the control input of the comparison circuit.