SU420114A1 - ANALOG-DIGITAL CONVERTER OF ACTIVE POWER - Google Patents

Description

one

The invention relates to a technique for converting analog values to digital codes.

Active-to-frequency analog-to-digital converters are known, with intermediate conversion to frequency, containing series-connected phase inverter, switch, adder, integrator, comparator, reversible counter with input matching circuit, reference voltage driver, connected by a control input to the output of the comparator, and a selector period period selector, the output of which is connected to the control inputs of the switch and the reversible counter.

The drawbacks of such converters are that their quadrating devices are low, accurate, and have significant inertia, and they also use highly sensitive measuring amplifiers of low-current drift current.

In order to increase accuracy and speed in the proposed converter, the output of the reference voltage driver is connected to one of the inputs of the comparison device, adder, and assembly scheme.

The Converter operates as follows.

The input voltage U, which is normalized to the voltage of the circuit under study, is fed to period selector 1 and phase inverter 2. From the direct and inverse outputs of the phase inverter, voltage is applied to an electronic switch 3 controlled by a period selector. From the switch output, the signal arrives at the input of the inverting adder 4, an input voltage is applied to its second input (Jz proportional to the current in the circuit under study, and a rectangular raznonol pf o | I from the output

The voltage of the driver 5 is the reference voltage. The output direction of the adder is fed to the integrator 6.

Suppose that in one of the periods the input from the switch output is shifted in phase by 180 ° relative to Ui. Then the voltage at the output of the adder is

,

where Uii, Uzi are the instantaneous values of the stresses Ll and Uz at some instant of time. In this case, the voltage at the output of the integrator changes according to the law

"I-- x (u ,, 1 + U (, where Ki is the constant of the integrator. For the moment of equality of the output voltage of the integrator with the voltage, we obtain

K (, i + U, t ,,,

from where

2t / o

t, .-.

K ,, + U,

The impulse from the output of the comparator device 7 is fed to the control input of the reference voltage driver 5, the output of which is the voltage -t / o. From this point on, the voltage at the integrator output decreases from + f / o to -t / o over a period of time fe, the duration of which is determined from

K (U, i-U, i-U,) t, -, i.e.

L:.

and f / o + t /, (- f / a

At time 4, the output impulse of the control device through the coincidence circuit 8, which opens when the negative voltages coincide, passes to the reversible counter 9, which operates in this clock period. The mode of operation of the counter is determined by the period selector. The sum of the intervals ii + 4 is the period of the instantaneous frequency / g equal to

ul- (U i-Ui {f

4f / o

And containing information about the power in time. The number of Ni pulses arriving at the reversible counter during the voltage period is equal to

  / Cu2 / i2x

 + 2V, Uii-U t

X

wl

where n is the number of comparisons over the period of the output voltage of the integrator with -C / o.

In the next period, the voltage goes from the switch output to the adder, and the reversible counter switches to the subtraction mode; otherwise, processes 5 proceed similarly. The number of pulses entering the counter for the second period is equal to

,

X

ul

After two periods in the counter accumulates pulses.

lv, - CU,

N N.-N.,

2 ° where / С -%, and

t /

,

and (/ 2 is proportional to the current in the circuit under study.

Subject invention

An analog-to-digital active power converter containing a series-connected phase inverter, a switch, an adder, an integrator, a comparison device, a reversible counter with a matching circuit

an input, as well as a voltage driver, connected by a control input with an output of a coping device, and a selector period period selector, the output of which is connected to the control inputs of a switch and a reversible counter, in order to improve accuracy and speed, the output of the reference voltage driver is connected to one of the inputs of the comparison device, the adder and the coincidence circuit.

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