SU789761A1 - Method of measuring electric and non-electric parameters - Google Patents

Description

one

The invention relates to electrical measuring equipment and is intended for use in the implementation of various switching methods of transformation, as well as in circulating control systems and multichannel measuring devices with time division multiplexing.

There is a method of measuring electrical and non-electrical parameters, which involves performing measuring operations on the input signal with an open and closed feedback circuit of the conversion unit, as well as with a modified feedback coefficient followed by processing the measurement results G.

However, in the known method, no test signals are used, and therefore the measurement accuracy is low.

The closest technical solution to the present invention is a method for measuring electrical and non-electrical parameters, based on converting and measuring the input and test signals with subsequent joint processing of measurement results I.

A disadvantage of the known method is associated with large dynamic measurement errors caused by transients when switching the input and test signals on the heels of the inertial conversion channel.

The purpose of the invention is to improve the measurement accuracy while maintaining a short implementation time of the measuring cycle.

To achieve this goal, in the method of measuring electrical and non-electrical parameters based on

15 on the conversion and measurement of the input and test signals, followed by joint processing of the measurement results, the input and test signals are measured again with a time delay determined by the type of conversion, and the measurement results of like signals are summed with weighting factors corresponding to the transfer function of the measurement channels.

FIG. 1, the device that implements the proposed method for measuring electrical and non-electric parameters is an oval diagram of an alternating voltage voltmeter with correction of errors; in fig. 2 diagrams are given, which explain his work.

Voltmeter contains switches

1 and 2, the outputs of which, respectively, through converters 3 and 4 of the alternating voltage to constant,

) and also the voltage divider 5 is connected to the inputs of the adder F. The output of the adder 6 through the computing unit 7 is connected to the input of the indicator 8. The control unit 9 with its outputs is connected to the control inputs of the computing unit 7 and the switches 1 and 2, the latter being connected through the time delay unit 10.

The inputs of switches 1 and 2 are pairwise connected to the source of the measured voltage X and the source of the test voltage X.

An alternating voltage voltmeter that implements the proposed measurement method operates in two cycles.

In the first cycle, the switch 1 becomes in position I and the input voltage X jumps to the input of the converter 3.

After the delay time t ,, the time delay formed by the block 10, the switch 2 becomes in position I and the input voltage X comes to the input of the converter 4.

Transients are generated in converters 3 and 4. If the inertial properties of transducers 3 and 4 are characterized by one constant time t, then transients, as shown in FIG. 2, where Y and Yn, are the output voltages of the converters 3 and 4, respectively, Y is the output voltage of the adder b. The input value is counted after the time to expires on the interval t.

In the second cycle at the command of the control unit 9, the switch 1 and with the time delay tj switch

2 (similar to the first stroke) becomes position II. At the same time, at the inputs of converters 3 and 4, a voltage step is generated. Transient processes similar to those in the first cycle appear.

The result of measuring an unknown quantity X is obtained in this device by the formula

p. Cl)

Nn

- digital samples of the results N, N, tats of X and XQ conversion to the first and second cycles, respectively;

NO - initial preset code.

Show

that in this device using the proposed measurement method, it is not only the static error that is reduced (additive

and multiplicative) -, but also a dynamic error caused by non-revenue up to the established value. In the first cycle, the values of 3i and 7 can be expressed as

Y CC (Xj. Kj; (21 Yft -X., (1st), (3) where Kj.K.I are the conversion factors of the blocks according to their numbers;. &Amp; X, LH - additive errors

blocks 3 and 4, respectively; B (-. Time constants of blocks 3 and 4, respectively.

We assume that we have chosen Kg e / and the substitution in (3) for the moments of time .t 7 / t. we get that

  1M

 Then the result of the conversion in the first cycle, taking into account, (2) and (4)

; N, X (lij, - "4e) tAX3k3 4 4

+ (k, -i; i)

(five).

Thus, if in expression (5) KK, i.e. the conversion factors of blocks 3, 4 are equal, then the count in the first clock cycle does not contain dynamic error.

To determine the value of the quantities iq, Y in the second cycle, one can use the well-known formula for first-order links, which takes into account the initial nonzero conditions when applying the voltage step. .

Y (t) YCO - DoD - Х, еЧ (6) where I, YO - is established and the initial value of the values.

Then, taking into account (b), by analogy with the first conversion cycle, the count in the second cycle will be equal to

 (v: -kjVX i-e- it) -e-t ((7

Thus, with the equality Kj K; Ng readout does not contain dynamic errors.

The result of the measurement to be indicated in block 8 will be determined according to expression (1) and taking into account (5) and (7), while supposing that Kj is Kc., Where j, are multiplicative errors of blocks 3, 4. In addition, the computational block 7, we introduce the offset NO X (1) Then, ..

 -N4 -No-X (1st (X-Ho)

(x-Xo) -) (x-ho) -.-x () .tt. (J.; y) (81

In the future, the operation of the device is repeated.

Claims (2)

From analysis (8) it follows that the conversion result does not include the adaptation error of blocks 3, 4, the multiplicative errors k, are weakened, and most importantly, the dynamic errors of blocks 3, 4 (the last two terms) are significantly reduced, since multiplied by small quantities. The device is designed so that L. In addition, it is easy to carry out XQ iS.X by adjusting the value of Hz according to the first reading of the value of X. Then in expression (8) only the first ideal term will remain. For a slight attenuation of the output signal Y, the attenuation coefficient K.Q e is chosen to be about 0.1-0.2. FIG. Figure 2 shows the plots of high voltage at the output of blocks 3 (curve Yy), at the output of block 5 (curve UL) and at the output of cyivwaropa 6 (curve Y is the thick line with horizontal sections of the farm). The curve is obtained by subtracting from the ordinates of the curve Y and the ordinates of the curve Yj. Characteristic of the Y curve is the presence of plots in areas nt. Converters 3, 4 can also be made on the basis of oscillatory links. It is easy to show that in this case, the proposed method allows one to obtain compensation for oscillatory features and significantly reduce the total time for establishing an accurate reading. A method for measuring electrical and non-electrical parameters, based on transforming and measuring input and test signals, followed by joint processing of measurement results, characterized in that, in order to improve accuracy, the input and test signals are measured repeatedly with a time delay determined by the type of conversion, and the results of measurements of the same signals are summed with the weights and coefficients corresponding to the transfer functions of the measurement channels. Sources of information taken into account in the examination 1. The author's certificate of the USSR 257631, cl. G 01 R 31/00, 1968. 2. USSR author's certificate 331321, cl. G 01 ft 19/00, 1970. X,