SU1684698A1 - Voltage root-mean-square value measuring device - Google Patents

Abstract

The invention relates to electrical measuring equipment and can be used to digitally measure the rms value of an alternating voltage. In order to improve the measurement accuracy, a voltage divider 7, memory registers 11 and 12, a digital divider 9 and a quadrant 13, an OR 10 element, a control unit 8 are entered into the device. The device works in two cycles. In the first cycle, the input voltage through the switch 1 and its contact groups 2 and 3 is fed to the input of the linear converter 4 AC voltage to constant, from the output of which is fed to the input of the analog-to-digital converter (ADC) 6 and is monitored in block 5 analog memorizing. The code from the output of the ADC 6 is written to register 11. In the second cycle, switch 1 switches and block 5 is disconnected from the output of converter 4 and through divider 7 is connected to the input of converter 4, ADC 6 is turned on again and in register 12 is recorded a new result. In the quadrant 13 and the divider 9, the signal signals recorded in registers 11 and 12 are processed. 1 з п. Ф-лы. 2 Il. AND

Description

The invention relates to electrical measuring equipment and is intended for the digital measurement of the root mean square value (RMS) of an alternating voltage.

The aim of the invention is to improve the measurement accuracy.

FIG. 1 shows a functional diagram of the device; Fig. 2 shows an example implementation of the control unit.

The device for measuring the rms voltage value includes a switch 1 with two contact groups 2 and 3, a linear converter 4 of alternating current voltage to constant, an analog memory block 5, the input of which is connected through the terminals of the moving and fixed contacts of the second contact group 3 of the switch 1 s the output of the linear inverter 4 AC voltage to constant and the input of analog-digital converter 6, the voltage divider 7, the input of which is connected to the output of the block 5 analog The new memory, the output of the divider 7 is connected to the output of the second fixed contact of the first contact group 2, control unit 8, digital divider 9, the control output of which is connected to the second input of the control unit 8, the element OR 10, whose inputs are connected to the first and second outputs of the unit 8 control, and the output is connected to the control input of the analog-digital converter 6, PeO 00 C O 00

memory hubs 11 and 12, the inputs of which are connected to the output of the analog-digital converter 6, the control inputs of the memory registers 11 and 12 are connected respectively to the third and fourth outputs of the control unit 8, the fifth output of which is connected to the control inputs of the switch 1, digital a quadrant 13 whose inputs are connected to the output of memory register 11, and an output of digital quadr 13 is connected to the first input of a digital divider 9, the second input of which is connected to the output of memory register 12, the seventh output of control unit 8 is connected to control the digital divider 9 input. The device input 14 through the output of the first fixed contact of the first contact group 2 of the switch 1 is connected to the input of the linear voltage converter 4 to constant AC, the first input of the control unit 8 is connected to the input 15 of the device start, the sixth output of the unit 8 control is connected to output 16 The end of the measurement device, the output of the digital divider 9 is connected to the information output 17 of the device

Control unit 8 (Fig. 2) consists of drivers 18-28, which sequentially generate signals and delay them in time. The formers 27, 28, 18, 19, 20, 22, 23, 24, 25 and 26 are connected in series. The input of the former 21 is connected to the output of the former 20. The first input of the former 18 is the first input of the control unit 8, the second input of which is connected to the input of the former 27, the output of which is the sixth output of the control unit 8, the first output of which is connected to the output of the former 18. The outputs formers 23. 20. 25, 21 and 26 are the second, third, fourth, fifth, sixth and seventh outputs of control unit 8.

A device for measuring the mean voltage value of a voltage works as follows.

At the input of the linear inverter 4, the alternating current voltage is gradually established, the measured voltage U fed through the first contact group 2 of the switch 1. The device measures the RMS voltage in two cycles. The first measurement cycle starts with the arrival of the Start signal at the first input of the control unit 8.

During the first cycle, the contacts of the switch 1 are in the position shown in FIG.

The control unit 8 on the first cycle forms zero from its fifth output.

the signal to the control input of the switch 1. On the start signal from the first output of the control unit 8 to the input element OR

10, the signal of the first start of the analog-digital converter 6 is received, and with a delay of the analog-digital converter time from the third output of the control unit 8, a signal is written to write the result code of the first converter to the memory register 11. As a result of the first analog-to-digital converter, the digital equivalent of the NI of the output voltage Ui of the linear conversion 4, proportional to the RMS of the input voltage (Ui KU / v, where K is the conversion coefficient of the linear converter 4), is written to the memory register 11. In this case, having taken the conversion ratio of the analog-to-digital converter 6 per unit, we get

Ni KUv (1)

During the first cycle, the voltage Ui is monitored by the analog memory unit.

The second cycle begins with the fact that from the trailing edge of the write pulse to the register

The 11 control unit of the control unit 8 forms a signal unit, which from the fifth output of the control unit 8 is fed to the control input of the switch 1. At the same time, the input of the analog storage unit 5 is turned off by the second contact group 3

switch 1 is from the output of the linear converter 4, and block 5 memorizes the voltage Ui; the input of the linear converter 4 is switched by the first contact group 2 of the switch 1 from the measured voltage U / v to the output voltage of the analog storage unit 5, which is supplied to it through the voltage divider 7 with the transfer coefficient equal to

E, where KN is the nominal conversion ratio of the linear converter 4.

Control unit 8 generates a delay for establishing a transient in the linear converter 4, after

0 from the second output of the control unit 8 to the other input of the element OR 10 receives the start signal of the analog-digital converter 6. On the second cycle, the analog-digital converter 6 gives the digital equivalent N2 of the output voltage U2 of the linear converter 4. proportional to the RMS, voltage output divider 7

U2 Ui K-, 1 N1

The code of the number N2 at the end of the conversion time of the analog-to-digital converter 6 is written to the 12-second register by the signal from the fourth output of the control unit 8. In this case, taking into account (1)

N2 - К -1- К VlV V, (2)

ГЧН1 Н

This ends the second cycle and the device proceeds to digitally process the conversion results.

The digital quadrant 13 multiplies the codes of the factors at its inputs NI and generates the output code N 1. which goes to the input of the digital divider 9 as a dividend. At the other entrance of the digital divider 9 comes the code N2 as a divider

From the trailing edge of the code write pulse to the memory register 12, in the equalization block 8, a dividing strobe signal is generated, which from the seventh output of control unit 8 is fed to the control input of the digital divider 9.

(NX - t -), as a result of which at the output of the digital divider 9, taking into account (1) and (2), a code is formed

-K2V, 2

Kn

 - KN

V-.

The dividing end signal from the output of the digital divider 9 is fed to the second input of the control unit 8. On the trailing edge of this signal, a signal is formed, a signal is formed. The end of measurement, which from the sixth output of block 8, goes to the device output, accompanies the transmission of the Nx measurement result code to external devices (for example, to a display device).

At the fifth output of the control signal conditioning unit 8, the Unit is terminated before the signal arrives. The end of the division and the switch 1 to the signal. The end of the measurement returns to the initial state shown in FIG. On the trailing edge of the pulse. The end of measurement, the control unit 8 generates a delay during which the input of the Start signal is blocked. This delay is necessary for setting the voltage at the output of the converter 4 after switching its input to the measured voltage. After the delay time has elapsed, the device can again receive the Start signal

Claims (2)

Invention Formula 1 A device for measuring the average-mean voltage value, containing a switch, is a linear AC-to-DC converter whose input through the terminals of the moving and first fixed contacts of the first contact group of the switch is connected to the input of the device, the analog storage unit of which connected through the terminals of the movable and fixed contacts of the second contact group of the switch with the output of an alternating AC voltage to constant voltage converter and with the input One analog-to-digital converter, characterized in that, in order to improve the measurement accuracy, it additionally 0, a voltage divider, a control element, an PI, two memory registers, a quad, and a divider are entered, the input of the voltage divider is connected to the analog memory output, and 5 the output of the voltage divider is connected to the output of the third stationary contact of the first contact of the first group of the switch, the first input of the block / control is connected to the input of the device Pugk1 second output of the control unit 1, d, i control output and P, BNxo.fi which is connected to the information terminal of the first device I. - Loroi outputs bpoke control goedig, p | l sp input element 5 OR, a link with the control input of the primary digital converter, the output of which is connected to the input of the first and second memory registers, the control inputs of which are connected respectively to the third and fourth outputs of the control unit, the fifth output of which is connected The sixth output of the control unit is connected to the output of the device. The end of the measurement, the output of the first memory register is connected to the inputs of the digital quadrator, the output of which is connected to the first input of the digital divider, Ora input coupled to an output of the second memory register 0 minute, the seventh output control unit coupled to the control input of the digital divider. 2. The device pop1, otlivayuschey- the fact that the control unit contains 5 eleven drivers, and the first input of the control unit is connected to the first input of the first driver, the first output of which is the first output of the control unit, the second output of the first driver through the second, third, fourth, fifth, sixth, seventh and eighth drivers are successively connected to the seventh output of the control unit, the sixth output of which is connected to the output of the ninth and the input of the tenth one, the output of the latter is connected to the second input of the first driver, the input of the ninth form ovatel is a second the input of the control unit, the second output of which is connected to the output of the fifth former, the output of the seventh former is the fourth output of the control unit, the third output of which is connected to the output of the third former and the input of the eleventh former, the output of the control unit. ten 77 figure 1 J