RU1794277C - Phase detector - Google Patents

Abstract

The invention relates to radio engineering. The purpose of the invention is to expand the sensor operating band. The phase sensor contains a feeder line section, a current transformer, a first voltage divider consisting of a capacitor and a resistor, a second voltage divider consisting of an inductor and a resistor, a differential rectifier including two diodes, two resistors, two capacitors , inductor and differential rectifier. The object of the invention is achieved by supplying voltage to a differential rectifier from broadband devices - a current transformer and from the - diagonal of the bridge, which is formed by the first and second voltage dividers. 2 ill. with y

Description

(L

with

The invention relates to radio engineering and can be used in automatic matching devices of radio transmitters.

A known phase sensor, the closest in technical essence to the proposed device and selected as a prototype. The sensor comprises a feeder wire, a phase-shifting current transformer with a middle terminal of the secondary winding, a capacitive voltage divider and a diode differential rectifier,

A disadvantage of the known device is the frequency dependence of the sensitivity of the phase sensor, which limits its working frequency band.

An object of the invention is the extension of the working frequency band of a phase sensor. At the same time, it is possible to obtain small dimensions, mass, power consumption, ease of setup and reliability of the sensor.

This goal is achieved by the fact that in the known phase sensor containing a wire feeder connected to the winding of a current transformer with a middle terminal, the first terminal of which is connected in series through the first diode, connected in the forward direction, the first resistor and the first capacitor connected in parallel, connected in parallel the second resistor and the second capacitor and the second diode, connected in the opposite direction, are connected to the second terminal of the current transformer, the middle terminal of which is connected to a feeder guide, an inductor, the first terminal of which is connected to the connection point of the first and second resistors, a third resistor is inserted between the common bus and the middle terminal of the current transformer, and a fourth resistor is between the common bus and the connection point of the first and second resistors

an amplifier whose output is the output of a phase sensor, direct and inverse inputs of a differential amplifier are connected to the cathodes of the first and second diodes, respectively, with the second terminal of the inductor connected to the wire of the feeder.

The current transformer, in contrast to the prototype, is selected to be non-phase-shifting (for example, at the ends of the secondary winding of the current transformer relative to its average terminal, one is in the other phase in antiphase with the feeder line current, which is achieved by a known method of shunting the secondary winding of the current transformer is quite small compared to the inductive resistance of this winding resistor). The phase shift required by the phase sensor for 90 ° (with a purely active feeder load) between the voltages supplied to the first and second diodes and removed: one from the current transformer, the other from the third and fourth resistors, is ensured by the choice of small values these resistors in comparison with the reactance of the third capacitor and inductance connected to them. The purpose of the inductor and its connection in the date circuit differs significantly from the prototype. chica. If in the prototype it serves as a choke that closes the direct current circuits of the diodes and blocks the passage of high-frequency currents, then in the proposed device, the inductor is an element of a high-frequency voltage divider supplied to the diodes, and the constituent components of the diode currents are closed through the third and fourth resistors. In such designs, it is unacceptable to connect the loads of the diodes (first or second resistors) with a common bus, therefore, the voltage difference across the loads of the diodes is formed using a differential amplifier.

In Fig.1 shows a diagram of an electric phase sensor: in Fig. 2 shows vector diagrams of voltages and currents in a phase sensor.

The phase sensor contains a piece of feeder line 1, a current transformer 2, a first diode 3, a second diode 4, a first resistor 5, a first capacitor 9, a second resistor 6, a second capacitor 10, a third capacitor 11, a third resistor 7, a fourth resistor 8, an inductor 12, differential amplifier 13.

On the vector diagrams of Fig. 2 are indicated: n, UH current and voltage at the feeder load; (p is the phase angle between the current and

voltage at the feeder load; UL is the voltage at the ends of the secondary winding of the current transformer relative to the middle terminal; Us, U4 are the voltages at the third and fourth resistors, respectively;

.Ugi, Ug2 are the voltages on the first and second diodes, respectively.

The phase sensor operates as follows.

An alternating voltage is applied to each of the diodes 3 and 4, which is the geometric sum of half the voltage of the secondary winding of the current transformer 2 and the voltage between the connection point

capacitor 11 and resistor 7 and the connection point of the inductor 12 and resistor 8. The voltages supplied to the diodes 3 and 4 from the current transformer 2 are out of phase, since they are counted relative to

secondary output of its secondary winding. These voltages are always one in phase, the other in antiphase with the current in the feeder line load (the sum of the resistances of the shunt resistors

secondary winding of current transformer 2, much less than the inductive resistance of the secondary winding of the current transformer at the minimum frequency of the operating range).

The voltage between the connection point of the capacitor 11 and the resistor 7 and the connection point of the inductor 12 and the resistor 8 is shifted 90 °

voltage at the feeder load if the reactance of the inductor 12 and capacitor 11 at the minimum frequency of the operating range is much greater than the resistance of resistor 7 and resistor 8, respectively. This can be seen from the consideration of the transmission coefficient K (s) of the circuit, consisting of elements 11, 7, 8.12:

KI

Kyu

Rn

R10 + IRl1 + jft) ll2

Jfr, R1oCe + L)

(t)

where RIO.RII - resistances of resistors 7 and 8 ;.

Ce is the capacitance of the capacitor 11;

1.12 - the inductance of the coil 12 and where the conditions

 1 / toC9 Rio

With a purely active load of the feeder line, when the current 1H and voltages UH coincide in phase (Fig. 2a), the geometric sums of the voltages supplied to diodes 3 and 4, respectively Ugi and Ug2, are equal, equal and

the rectified voltages across resistors b and 7 (if the resistance values of these resistors and the capacitance values of capacitors 9 and 10 are respectively equal), and the output voltage of differential amplifier 13 is zero. When a phase shift occurs between the current and the voltage in the feeder line, the voltages on diodes 3 and 4 become unequal (Fig. 2 bc), and the output voltage of the differential amplifier 13 becomes greater or less than zero depending on the direction of the phase shear between current and voltage in the feeder line.

The purpose of the invention, i.e. the operation of the phase sensor in a wider frequency band is ensured by the weaker frequency dependence of the voltage between the connection point of the capacitor 11 and the resistor 7 and the connection point of the inductor 12 and the resistor 7. compared to the output voltage of the phase-shifting current transformer in the prototype. The first voltage depends on the frequency in accordance with formula (1), the second is linear.

It can be shown that the sensitivity of the phase sensor in the proposed device is determined by the formula:

S

2 R (UC (1 + ug / ffl).

v 1 (1 + 2 a phase sensor in the prototype formula:

Snp

2 M ns V1 + (M 1 „of

(3)

where R is the magnitude of the resistance shunting the secondary winding of the current transformer; (Oo I / Ci2 Ce; M is the mutual inductance of the windings.

Comparing expressions (2) and (3) with each other, it can be seen that with "Q) the frequency characteristics (2) and (3) coincide / However, if you select o) 0 equal to the average frequency of the operating range, i.e. ratio 0) o / a) of order I, then the dependence of sensitivity on frequency according to expression (2) can be significantly reduced.

The adjustment of the phase sensor is carried out as follows. SUMMARY OF THE INVENTION SUMMARY OF THE INVENTION A phase sensor comprising a feeder wire inductively coupled to a current transformer with a midpoint, a first terminal

fifty

5 0 5

0

5

0

5

the activity of the coil 12 and the% capacitance Cd of the capacitor 11, select the outcome from the expression Yaz I / L-12 Ce. where% Ј "mine,

Shmin, (Imax is the minimum and maximum frequencies of the operating range. At a frequency ub and at a feeder load equal to the wave impedance of the feeder, the voltage across resistor 7 (resistor 8) is measured. The voltages at the ends of the current transformer winding are measured average output and regulate each of these voltages to a value approximately two times larger than the voltage on resistor 10 (in this case, the voltages supplied to diodes 3 and 4 from current transformer 2 and from the voltage divider formed elements 9-12 will be approx This adjustment is carried out by alternately changing the value of the resistors shunting the current transformer 2, while the voltages at the ends of the windings of the current transformer 2 must be set equal and the total value of the resistance of the shunting resistors must be significantly less than the reactance of the inductance of the secondary winding of the current transformer 2 at the minimum operating frequency.

The sensor is implemented as shown in FIG. 1, while the resistors shunting the secondary winding of current transformer 2 must be variable. In the frequency range of short waves, the parameters of the component parts of the phase sensor can be selected as follows:

- current transformer 2 can be performed on a ferrite ring 1000NN K7-4-2; secondary winding of 25 turns, primary - a feeder passing inside the ring, shunt resistors - not more than several hundred, Ohm; the resistance value of the resistors 7 and 11 is several tens of Ohms with the coil inductance 12 of several tens of microgenry and the capacitance of the capacitor 11 is several tens of picofarads, diodes 3 and 4 can be of type 2D522, resistors 5 and 7 can have a value of several tens of ohms, differential amplifier 13 can be performed on a chip type 140 UD 12.

which through a series-connected first diode, connected in the forward direction, parallel-connected first resistors and capacitors, parallel-connected second resistors and a capacitor, and a second diode, connected in the opposite direction, is connected to the second terminal of the current transformer, the middle terminal of which through the third capacitor - is connected to the feeder wire, an inductance coil, the first output of which is connected to the connection point of the first and second resistors, with the exception of the fact that, in order to expand the range of the other frequencies, a third resistor is inserted between the common bus and the middle terminal of the current transformer, a fourth resistor is between the common bus and the connection point of the first and second resistors, a differential amplifier whose output is the output of the phase sensor, the direct and inverse inputs of the differential amplifier are connected to the cathodes of the first and the second diodes, respectively, the second terminal of the inductor is connected to the wire of the feeder.

Output