SU1742996A1 - Shaft rotation angle-to-code converter - Google Patents

Abstract

The invention relates to automation and computer technology and can be used, for example, in satellite antenna control systems and in other systems that are subject to strict requirements for the temperature mode of operation of an angle sensor that is remote for a considerable distance. The invention provides an increase in temperature stability and noise immunity of the converter. The converter contains a phase shifter 1, a generator of 2 pulses, comparators 3-6, RS-flip-flops 7 and 8, summators-subtractors 9 and 10, a generator of 11 sine and a generator of cosine 12, Elements And 14 and 13. current counters 15 and 16, current sensors 17-20, temperature compensating elements 21 and 22, differential amplifiers 23 and 24, adder 25 and output bus 26. Use as supports

Description

The invention relates to automation and computer technology and can be used, for example, in satellite antenna control systems and in other systems that have strict requirements for the temperature mode of operation of an angle sensor that is remote for a considerable distance.

The aim of the invention is to increase the temperature stability and noise immunity of the converter.

Fig 1 is a diagram of the converter of the angle of rotation of the shaft into a code; FIG. 2 shows an equivalent circuit for replacing a phase shifter.

The converter of the shaft rotation angle into the code contains a phase shifter 1, a generator of 2 pulses, the first 3, the second 4, the third 5 and the fourth 6 comparators, the first 7 and the second 8 RS triggers, the first 9 and the second 10 totalizers-subtractors, the generator 11 para-phase sine signals, generator 12 paraphase cosine signals, the first 13 and second 14 elements are And the first 15 and second 16 counters, the first 17, second 18, third 19, fourth fourth current sensors, first 21 and second 22 thermal compensating elements, first 23 and second 24 differential amplifiers, the adder 25 and the output bus 26.

Converter angle of rotation of the shaft in the code works as follows.

The pulses of the generator 2 clock pulses are supplied to the inputs of the generators of the sine 11 and cosine 12 signals. The generated signals from their outputs through sensors 17-20 of the current are respectively fed through a symmetrical line to one and other inputs of the input windings of the phase shifter 1. From the sensors 17 and 18 of the current, a signal proportional to the current of one winding is fed to the inputs of the first subtractor 9 and the signal from the current sensors 19 and 20, proportional to the current of the other winding, is fed to the inputs of the second subtractor 10. From the outputs of the adders 9 and 10, the signals of one and the other channels, which are reference, are fed to zero comparators 3 and 4 respectively venno. Zero comparators 3 and 4 generate pulses when the reference signals go through zero and feed them to the S inputs of RS flip-flops 7 and 8, respectively. The signals of the other two windings of the phase shifter, which are output, are also transmitted via a symmetric line to the differential amplifiers 23 and 24 of the one and the other channels, respectively. With the help of comparators 5 and 6, when passing through zero output signals from the outputs of differential amplifiers 23 and 24, pulses are generated that are addressed to the R inputs of the RS flip-flops 7 and 8 of one and the other channels. As a result, the outputs of the RS-flip-flops 7 and 8 are formed

signals whose duration is proportional to the angle of rotation of the shaft of the phase shifter 1. Using the elements And 13 and 14 and counters 15 and 16, the duration of these pulses is converted into digital.

code. The digital codes of each of the channels (one and the other) from the outputs of the counters 15 and 16 are summed up in the adder 25, the output 26 of which forms a digital code equal to half the sum of the input codes of the one and the other

channels and proportional to the angle of rotation of the shaft of the phase shifter 1, and the use of two channels (one and the other) eliminates the converter errors associated with the inequality of amplitudes and the non-orthogonality of the phases of the voltages supplying the phase shifter 1.

In order to eliminate the temperature drift of the output code of the converter caused by phase drift between the input

the voltage of the phase shifter and the current in the excitation windings, the reference signals used are not the excitation voltages, but currents flowing in the excitation windings of the phase shifter. For any

arbitrary angle of rotation of the shaft of the phase shifter between the excitation voltage and

current in the field windings there is a phase shift due to the presence of inductance and active resistance of the winding, and this phase shift changes as the active resistance of the field winding changes. Since the emf induced on the advantageous windings of the phase shifter is a consequence of the excitation current, there is a temperature drift between the excitation voltage and the emf. When using signals proportional to the excitation current, it is possible to partially eliminate the temperature drift of the converter code caused by a change in the active resistance of the windings, the excitation of the phase shifter,

To almost completely eliminate the temperature drift of the converter code, thermal compensating elements — capacitors 21 and 22 — are introduced into its circuit.

five

evidence of this will consider the equivalent of a phase shifter along one of the channels (figure 2). The equivalent circuit of another channel is similar.

It was established experimentally that with an increase in temperature, the inductive parameters change slightly, while the resistance of the windings RI and R2 increases, and the resistance of the no-load loss RO decreases.

Writing in accordance with the Kirchhoff laws in a complex form, the distribution of currents and EMF, we obtain the ratio of the output voltage and the input current in the phase shifter. By putting the variable values Ro in it. RI and R2, which are linearly dependent on temperature, and equate to the derivative of this ratio with respect to temperature to zero, we obtain equality to determine the required reactance of the element shunting the excitation winding

y (g RQ -% R2) (Rg + Xg) ± Y (d R2 Qb Ro) 2 (Ro + Xj) - 4 og Rg X0 (R2 + Ro) 2 Y

AHn o vAO

2 in RCJ AO

X0 where Xn is the calculated value of the required reactance;

 Ro, Ri, R2, Ho, Xi, X2 are the active and reactive resistances of the idling and phase coil windings;

it and a.2 are the moduli of temperature coefficients of variation of the idling resistance and the excitation winding.

In practice, the value of Hn is always negative, which indicates the need for a capacitive load.

The capacitance of a capacitor is determined by the formula

Ck -

one

wcn where is the frequency of the excitation current.

Therefore, in order to provide thermal stabilization, capacitors 21 and 22 are introduced into the circuit of the proposed converter.

The use of phase shifter excitation currents as reference signals, generated using current sensors 17-20, as well as the introduction of a capacitor converter 21 and 22 connected parallel to the output windings of the phase shifter, make it possible in total to achieve a temperature error of almost zero. In turn, the presence of symmetrical outputs of paraphase sinus 11 generators and paraphase cosine 12 signals Qb Ro) 2 (Ro + Xj) - 4 og R§ X0 (R2 + Ro) 2 Y

n о vАО

2 in RCJ AO

X0X2

Fishing in combination with symmetrical lines on both the excitation side and the output side of the phase shifter using differential amplifiers 23 and 24 makes it possible to significantly increase the noise immunity of the converter.

Thus, the proposed circuit solution for converting the angle of rotation of the shaft into a code allows one to significantly increase its temperature stability and noise immunity. For example, when using a BT-5 type sensor as a phase shifter, the temperature error in the ± 50 ° C temperature range is zero for a 16-bit output code, and the noise immunity for a communication line with a sensor of 12 m is that the resolution of the converter is half the low-order bit of the 16-bit output code without averaging.

Claims (1)

Invention Formula A shaft rotation angle converter into a code containing a phase shifter, a pulse generator, two para-phase sinusoidal voltage generators, the inputs of which are connected to the output of the pulse generator, the first and second zero comparators, the output of the first zero comparator is connected to the S-input of the first RS- the trigger, the third and fourth null comparators, the outputs of which are connected to the R-inputs of the first and second triggers respectively, the outputs of which are connected to one input of the first and second element And, respectively, the other inputs of which are connected The outputs are connected to the output of the pulse generator, and the outputs are connected to the counting inputs of the first and second counters, respectively, whose outputs are connected to the inputs of an adder, whose output is the output of the converter, the zeroing inputs of the first and second counters are connected to the output of the first zero comparator, This is so that, in order to increase the temperature stability and noise immunity of the converter, four current sensors, two subtractors, subtractors, two thermal compensating elements, and outputs of syn generators are introduced into it via the first and second current sensors, respectively, are connected to one input of the corresponding input windings of the phase shifter, and the other outputs of the sinusoidal voltage generators are connected to the other inputs of the corresponding input windings of the phase shifter, respectively, the first current sensor connectors are connected to one input t 1 0first and second groups of inputs of the first adder-subtractor, the findings of the second current sensor are connected to other inputs of the first and second groups of inputs of the first adder-subtractor, the output of which is connected to the input of the first zero comparator, the conclusions of the third current sensor are connected to one input of the first and second groups the inputs of the second adder-subtractor, the conclusions of the fourth current sensor connected to other inputs of the first and second groups of inputs of the second adder-subtractor, the output of which is connected to the input of the second zero comparator, the outputs of the first The output winding of the phase shifter is connected to the terminals of the first temperature compensating element and the inputs of the first differential amplifier, the output of which is connected to the input of the third null comparator, the outputs of the second output winding of the phase shifter are connected to the terminals of the second temperature compensating element and the inputs of the second differential amplifier, the output of which is connected to the input of the fourth zero - comparator. Z2 P (T 4 -J 1