SU1793393A1 - Device for testing capacitor capacitance during winding process - Google Patents

Description

The invention relates to a control technique Й concerns the improvement of capacitance monitoring devices, coil capacitors during winding. ·. '· -;

A device is known for monitoring capacitance during the winding process, comprising a converter of the capacitance of a wound .. 'capacitor section into an' impulse ', a circuit for comparing the converter pulse with a voltage corresponding to a given capacitance, a controlled voltage source of a given capacitance and an executive circuit. . '·

The main disadvantage of this device is that the capacitance of the wound capacitors or their sections is monitored using dc current, while the finished capacitors are monitored by alternating current at frequencies of 50 or 1000 Hz, depending on their type and nominal. . '·.

A device for monitoring capacitance in the process of winding sections of capacitors, containing a measuring bridge, a comparison element and a stop electromagnet, in which a quasi-balanced resistor bridge is connected to the comparison element through series-connected cathode repeaters, rectifiers and smoothing LC filters.

A significant drawback of this device is the inaccuracy of the capacitance control caused by disproportionality.

the amplitude of the sinusoidal voltage in the diagonal of the bridge and the rectified voltage of the diagonal of the bridge at the input of the comparison element. This is due to a stepwise (stepwise) change in the capacitance of the wound capacitor (winding unevenness) and short-term short circuits in it due to the presence on the film hop filled with metal and anomalies during refueling, which causes a transition process in the diagonal of the bridge and an exponential component of the voltage, the value of which depends on the instantaneous values of the voltage of the diagonal at the time of the jump in capacitance and the time constant of the transient from parallel connected reference wound capacitors and the input impedance of the cathode follower connected in the bridge diagonal. Due to the fact that the input resistance of the cathode follower in the diagonal of the bridge should be 2-3 orders of magnitude higher than the output resistance of the bridge for independent monitoring of capacitance and high sensitivity, the time constant of the transition process, causing a disproportionality of the voltage at the input of the comparison element and the amplitude of the sinusoidal voltage of the diagonal at significant capacitance * of the rewound capacitor, can be several seconds. Another drawback is the dependence of the capacitance monitoring results on significant parasitic capacities5 .6 of the tape drive rollers and the tape lock mechanism relative to the body of the winding machine, simulating the resistive shoulders of the bridge, setting the voltages on the winding and reference 5 capacitors,

The closest in technical essence to the proposed device is a direct compensation bridge with direct balancing, containing a 10-frequency generator connected to a capacitance-to-voltage converter executed on an operational amplifier, whose negative feedback circuit is connected to a reference resistor, and to an inverting one input - wound '(controlled) capacitor, 90 ° phase shifter and two analog-to-digital converters. In this device, the measuring frequency generator is connected directly to a winding (controlled) capacitor, a 90 ° phase shifter and an amplitude detector, and the output of the capacitance pre-converter to the voltage is connected to the pen inputs of the first and second synchronous

N 'n ector, to the second inputs of which are connected the outputs of the generator of the frequency meter, and the phase shifter 90 °. This makes it possible to isolate constant voltages at the outputs of synchronous detectors, proportional to the amplitudes of the synchronous and quadrature (relative to the generator voltage) components of the output voltage of the converter, which in the prototype is expressed by the formula

Ubwx ~ Uoj Щ C _x Ro (1 + jtg Οχ) ,, е (Jo is the voltage of the generator;

Cx, tg oh - the parameters of the wound (controlled) capacitor;

Ro - 'resistance of the reference rizier in the negative feedback circuit '35

DG | Art.

on a e op but

In addition, in the prototype, the output of the first synchronous detector is connected to the measuring input of the first logametric 'analog-to-digital converter (ADC), the output of the amplitude detector to the er input of a similar second ADC, the output of the second synchronous detector to the er input of the first ADC and measuring the input of the second ADC .

Note that the logametric ADC provides a digital readout of the voltage at the measuring input relative to its voltage at the reference input, and the multi-sided analog-to-digital ADCs usually provide a digital readout of the voltage at the measurement, whereas the standard input voltage is relative to the highly stable DC voltage sources built into them; In the prototype, a digital independent readout of the capacitance at the output of the lagometric ADC is possible only when the quadrature component of the converter voltage does not depend on the capacitor tan σ, as is the case in the above formula. But as will be shown below, this formula is valid only for tan 1.

The advantage of the prototype is the lack of standards for capacity. We also note that in the prototype the time constant of the transient process that occurs when a stepwise change in the wound capacitance of the capacitor and short-term short circuits in it (the reason for which is indicated above) can, under certain ratios Ro and Cx, be less than the period of the measuring frequency and have little effect on the accuracy of winding. The advantage of the prototype is the lack of influence of the above parasitic capacitance on the result of capacity monitoring, because they only shunt the output voltage of the measuring frequency generator and the input of the operational amplifier of the converter. Indeed, in the prototype, the result of monitoring the capacitance does not depend on the voltage of the measuring frequency generator, and the voltage at the input of the operational amplifier with the gain of the latter tending to infinity tends to zero.

The disadvantages of the prototype are the dependence of the results of capacity monitoring on the frequency of measurements (its instability).

There is a delay in fixing the moment the capacitance of the wound capacitor reaches its nominal value due to the need to rectify ne voltage voltages with synchronous and amplitude detectors, which requires a time equal to several periods of the measurement frequency. This reduces the accuracy of the winding of the capacitor especially at low measurement frequency and high winding speed, this also takes place * in [2]. The error will be caused by 50 non-linearity of detectors, especially (phase) synchronous, and their instability, but the main disadvantage of the prototype is the dependence of the accuracy of monitoring the capacitance of the capacitor on its tg σ, especially if 55 is taken into account that when winding, the value of tg σ can reach 1 or more, which may cause more inaccuracy in capacity monitoring.

The purpose of the invention is to improve the accuracy of winding capacitors in a given nominal capacity of ’Ί

bones (eliminating the disadvantages of the prototype) is achieved by the fact that in the device for controlling the role of capacitors in the winding process, comprising a measuring frequency generator connected to a capacitance-voltage converter, made on an operational amplifier, in the negative feedback circuit of which a reference resistor is connected, and to the inverting input there is a wound capacitor, a 90 ° phase shifter and two analog-to-digital converters, an additional code-controlled voltage amplifier, introduced in operation, is introduced an amplifier whose inverting input is connected through a resistor to the output of the operational amplifier of the capacitance-to-voltage converter, and to the negative feedback circuit, a digital-to-analog converter controlled by a binary reversible counter equipped with means for recording the code of the rated value of the capacitance of the wound capacitor in it; a limiter made on an operational amplifier with an 'open negative feedback circuit, the output of which is connected. to the trigger inputs of both analog-digital converters; a resistor connected to the measuring frequency generator and the first input of the limiter amplifier with one tap, and the other to its second input and the measuring input of the first analog-to-digital converter, and also through the winding capacitor to the inverting input of the operational amplifier of the mentioned capacitor-converter; a digital comparator, the inputs of the digits of numbers B and A of which are connected respectively to the information code outputs of the first and second analog-to-digital converters, and its outputs A> B and A = B through the circuit or to the winding stop solenoid, and the phase shifter is 90 ° on an operational amplifier with a capacitor in the negative feedback circuit and a variable resistor connected by one tap to the inverting input of this amplifier, and the other to the output of a code-controlled voltage amplifier, and the output of the operational amplifier of Tell ° phase shifter 90 is connected to a measuring input of the second analog-to-digital converter.

The introduction of a code-controlled voltage amplifier into the device according to the described scheme allows ^: a high degree of accuracy to enter data on the value of the nominal value of the capacitance of the wound capacitor by both the operator and the computer, reduce the dimensions of the device and, ultimately, increase the accuracy of control.

The introduction into the device of an amplifier-limiter, additionally a resistor in this connection with a measuring frequency generator, a capacitance to voltage converter, and also a 90 ° phase shifter and both analog-to-digital converters made it possible to form, at the inputs of the latter, such two voltage of the measuring frequency and measure their instantaneous values at that point in time when the measurement results depend only on the degree of proximity of the capacitance of the wound capacitor to the nominal value and do not depend on its t angle of loss.

The introduction of a digital comparator into the device makes it possible to determine the instant of equality of the instantaneous values of the compared voltages (with a high degree of accuracy) corresponding to the moment of equality of the capacitance of the wound capacitor to its nominal value and stop winding with a delay of no more than one period of the measuring frequency.

The constructive implementation of the phase shifter by 90 °, in addition, allows not only to form one of the compared voltages, but also to exclude the dependence of the monitoring results on the measurement frequency or, more importantly, on its instability.

All taken together, the features provide the ability to set the moment of winding the capacitor in a given nominal capacity, regardless of its loss tangent, regardless of the instability of the generator frequency, no later than for one period of the measuring frequency, to exclude the influence on the result of transient monitoring during a step change in the wound capacitor capacitance and short-term short circuits in it. Comparative analysis with the prototype shows that the claimed device is distinguished by the presence of new elements: a code-controlled amplifier, an additional resistor, an amplifier-limiter, a digital comparator, a specific feature of 90 ° phase shifter and their connections with other elements of the device.

Thus, the device meets the criteria of the invention of Novelty.

Comparison of this solution with other technical solutions shows that code-controlled voltage amplifiers, gels-limiters, digital comparators, a 90 ° phase shifter (it is made with an integrator device) are well known. However, when they are introduced into the specified device in connection with the remaining elements of the circuit for monitoring the capacitance of capacitors during the winding process, they exhibit new properties that contribute to improving the accuracy of winding the capacitors at a given capacity rating. This allows us to conclude that the technical solution meets the criterion of Significant differences. "

The drawing shows the structural diagram of the device.

The device comprises a measuring frequency generator 1, a converter executed on a perration amplifier 30, into a negative-castie circuit to a voltage of 2, o

whose feedback is connected and

to

The common input of which is through a resistor 8 (Ri) (3to

P m

p en reference resistor 4 (R _o ), and to its borehole input - a wound endcap 5 (C _x , g _x ); - code-controlled voltage amplifier 6, made on the operational amplifier 7, invert

Ρ С Η the resistor is usually included in the microchip of the digital-to-analog converter) is connected to the output of the operational amplifier 3 of the converter 2, and the digital-to-analog circuit (the converter 9, controlled by a binary reversible counter 10, equipped with an input 11 for writing a code with a nominal value of capacity : amplifier-limiter, made on the operational amplifier 12 with an open circuit negative feedback, the output of which is connected to the input inputs of the analog-to-digital converters 13 and 14. In addition

Πι

Ρ 'τψ. the device contains a resistor 15 (R2), oh,

Η.

Ρ '• (with a tap connected to the generator and the first input of the amplifier-limiter 12, and the other to its second input, the measuring input of the transducer 13, and through the rewind capacitor 5 to the inverting input of the amplifier 3; digital comtator 16, discharge inputs the numbers B and A. of the mountain are connected respectively to the inrmation code outputs of the converters 13 and 14, and the outputs of the comparator A> * B and A = B through the OR circuit 17 to the winding stop magnet 18; phase shifter 90 ° 19, made on the operational amplifier 20 with capacitors 21 (SF) in the circuit from negative feedback and a variable resistor 22 (Lf) connected by one tap to the inverting input of the amplifier 20, and the other to the output of the operational amplifier 7. The output of the amplifier 20 is connected to the measuring input of the transducer 14, the means 11 for writing the code to the binary counter counter 9 can be performed differently: from the host computer, the code can be fed directly to the installation inputs 5 of the triggers of the counter 10, and when the code is set by the operator, for example, as it is shown in FIG. 1. The recording means 11 includes a rectangular pulse generator 23 with an adjustable repetition rate (1 - 40) 10 Hz. three sequentially connected binary decimal counter 2426, the outputs of the triggers of each of which are connected to the liquid crystal 15 digital indicators 30-32 through the decoders of the seven-segment code 27-29, and each of the inputs of the counters 25 and 26 (for addition and subtraction) is connected to the corresponding outputs the transfer 'of the previous counter 24, the transfer outputs of counter 20 of the counter 25 through the circuit or 33 are connected to the input of the zero setting of the counter 10. The generator 23 through the contacts of the push-button switches (without latching) 34 and 35 is connected respectively but to the inputs of addition and vychi25 Thaniah counters 10 and 24.

The voltage at the output of the operational amplifier at a gain of K, tending to infinity, is equal to:

and _{В out} = -and _В x | £, where _{В В} is the voltage through the complex resistance Zi connected to the inverting input of the amplifier;

Z2 is the complex resistance in the negative feedback circuit 35.

The voltage at the output of the operational amplifier 3 (and _V oohs) of the capacitance to voltage converter 2, because the input voltage for it is the output voltage E of the measuring frequency generator I:

and _{in the} university

E ro

R2 + Γχ -

E Ro (about with _x J

J tg WE + 1

SCh

Ep Rp ω Cx (1 - j tg wE + tg ² WE where C _x and Zx are the capacitance and resistance of the winded capacitor;

tg w. = (R2 + Γχ) ω Cx is the loss tangent of this capacitor, taking into account the additional resistor R2 introduced into the device.

In the absence of R ₂ , as in the prototype, instead of 55, tgc ^ would appear in the formula tg σ = (ύ С _x 2х. In any case, this formula shows that in the general case the quadrature component of the output voltage of converter 1 depends not only on Cx, but also on tan σ _χ . Only for tan w _x <^ 1 (naturally

I, in the absence of R2, introduced into the proposed device), the output voltage of the converter 1 is expressed by the formula and _B ooh2 = - Е ω j C _x Ro (1 - tg σχ), where the quadrature component does not depend on 0Ttg a _x .

It should be noted that when using the amended output voltage formula introduced above, independent control of tg σ _χ in the prototype is possible using lagometric ADCs. However, control of the capacity independent of the loss tangent is not possible in the prototype, because when winding tan σ _{x of the} capacitor reaches 1 or more. In the proposed device, the problem of the operational amplifier 7, independent of tga control® 15, is solved at K - * co, ~ ~ tends to ”0. Here K is the gain of the operational amplifier without feedback, Л Е Е (—J ¹ Ua = ----—: R2 + r _x - j

E (1 - jtgoE).

capacities. If you choose R _o in such a way that Ro a> C _X max ss1, where Schmax is the maximum controlled capacity, then R _O C _X , where T is the period of the measuring frequency. With an abrupt (stepwise) change in the capacitance of the wound capacitor and short-term short circuits in it, causing, as noted above, a transient process, its time constant will be equal to m = 3C _XM axc (Ro + R2 + 2x) and even when tan σ _χ = 1 , it is less than the period of the measuring frequency and will have only a small effect on the result of control. The output voltage of the operational amplifier 7 (0U7 and _OUT) of the amplifier 6 kodoupravlyaemogo considering that at its input - output voltage operatsionnogo- amplifier 7. (see Fig. 1), expressed by the formula

1093 and _B oyOU7 = -Vyi OOUZ ~.

! '1,023' Smake = -and _{in the} output of the OUZ— ^: - “g—> Sn · where N is the number expressing the nominal value of the capacitance Sn of the wound capacitor:

Smake ^{- the} maximum value of the capacitance controlled on a given sub-range, for example, 9.99 microfarads, and 1023 the maximum number that can be written to the binary counter 10 (in this case, ten-digit), or taking into account the values of Tsvyh OUZ and _V oyOU7 = _ Smake 1,023 Е Io si C _x J (1 J tg оЕ).

Snow (1 + tg ² 0E)

The voltage at the output of the phase shifter at 90 ° 19 is the output of the operational amplifier 20 (and _V oOh2o), taking into account that the voltage of the operational amplifier 7 (and _B oOhO7) acts on its input according to the general formula for the operational amplifier is:.

and _in yyOU2o ^- '. Rf o) sf rf

Smake '1,023 Е Ro ω Lx (1 - j tg (TE) _ j and _you хУУ7

Cn (ύ Cph If (1 + tan ² s / E) for Cx = Cu (when winding in the nominal) and _b1X oy ₂₀ ^ -LL ^C MaKC ¹ .023 R (1 - tan J JE).

Ρψ Сф (1 + tg ² σΕ) '

The voltage at point a between C _x and R _x (see FIG. 1), taking into account the series capacitor equivalent circuit and the fact that the voltage at the inverting input

ά) C _x ) _. E _ ~ 1 + j tg oE “

Φ C _x

1,023 'Smake' Ro _ .j + tg ² oE

Provided that ---- _: ~ —5—

Cf Kf, the voltage at the output of the phase shifter by 90 ° 19, respectively, of amplifier 20 (and _B ых О У 2 2 о 2) and voltages U _a have at the moment C _x = Sn equal in absolute value quadrature and in-phase components, but also opposite in sign, i.e. in this case they are • equal in amplitude and out of phase, but. their 35 instantaneous values are equal in absolute value. On the other hand, point a is potentially aligned with the connection point of the analog-to-digital converter 13 (see Fig. 1) only at the time when the voltage value at R2 is equal to 4Q. This corresponds to the amplitude value of the voltage at C _x , the absence of voltage at g _x and its amplitude value at the output of the phase shifter 19. Therefore, at the time of the winding of the capacitor to the nominal value, in the presence of zero voltage at R2, the voltage at the inputs of the analog-to-digital converters 13 and 14 are equal modulo regardless of the values of tan σ _χ and tan (¾. It is known that analog-to-digital converters convert bipolar voltages at the measuring inputs into a proportional code (only a logical zero or a unit in the sign digit changes ). Note that the existing analog-to-digital microcircuit converters operate in less than 1 μs, which is quite enough to control the capacitance in the winding device; it often measures not more than 1 kHz, but in principle, in the case of π

Γ in

The formation of microcircuit devices for voltage alignment and storage in front of analogue □ -digital converters, switched off at the time of measurement, the frequency of measurements in capacitance monitoring devices 5 during winding can be significantly increased.

If in the device is made variable to accurately comply with the ratio 1,023 'Smake' Ro _d g, _g

---------- = 1, and Ro can be used

111

From _£ βψ Use This Criterion for organizing decimal oddiapazonov. So, if Smake increased ten times, ten times need to be reduced

about.

. ’The device works as follows.

Initially, a binary reversible counter 10 is recorded for the code of the immune value of the winding capacitance of the · 20th capacitor. The code can be submitted directly to the installation inputs in

Η e

Η trigger counter 10 from the control

E oh

P

VM When the operator sets the code, this is done using the 11 code fill tool. In this case, by pressing the push-button switches 34 and 35. (more or less) and setting the pulse frequency of the generator 23 near 40 Hz, keep the switches 34 and 35 pressed until they achieve zeroing of the counters 24-26, xing this by the appearance of three zeros three digital indicators 30-32, at least for a short time. At the moment of resetting the counters 24-26, the transfer pulses of the counter 26 through the OR circuit 33 will reset the counter .. 10. After that, by adjusting the frequency of the generator pulses 23 by turning it on and the switches 34 and 35, the desired nominal value will be read out on the indicators 30-32 capacities. Accordingly, that. the same number of pulses will be recorded in a binary reversible counter 10. Note that during the first setup of the device, instead of a winding capacitor, a capacitance store is connected and the same capacitance is typed on it, which is recorded on the indicators, and an electromagnet is triggered by a variable resistor Bf at these conditions. The device is ready for operation, I

Η ¹ φ

Claims (1)

• The claims j A device for monitoring the capacitance of capacitors during the winding process, comprising a measuring frequency generator, a capacitance to voltage converter, a wound capacitor can be connected. As the capacitor 5 is winding, the voltage begins to drop at the point of connection, the analog-to-digital conversion. 13 and increase the voltage at the connection point of the analog-to-digital converter 14, the Start-up of the converters 13 and 14 is carried out simultaneously, once, when the voltage goes to R ₂ through zero, because this voltage is converted by the amplifier-limiter into rectangular pulses, the edges of which coincide in time with the moment the voltage across R ₂ passes through zero and with a positive edge, the pulses trigger the converters 13 and 14. Information code outputs of analog-to-digital converters 13 and 14 are connected respectively to the inputs of numbers B and.A of the digital comparator 15, which at the moment of equality of codes B and A, corresponding to the equality in absolute value of the instantaneous voltage values supplied to the measuring inputs of the transducers 13 and 14, gives a pulse from output A 25 = B and through the OR 17 circuit it gives a signal to the winding stop electromagnet 18, which, having some inertia, is finally turned on by the logic unit signal at the output A> B through the OR 17 circuit a little later. As shown above, transients in a wound capacitor in the proposed device can last no more than one period of the measuring frequency. Thus, the moment of winding the capacitor to the nominal value Cx = Cn in the proposed device is determined independently of the loss tangent of the wound capacitor, the voltage of the generator 1 of the measuring frequency, and the instability of this generator in frequency. As indicated above, the range of control of capacitors can be expanded by changing the value of Ro, connecting, for example, through re-! le, other Ro, are ten times more or less, which can significantly improve the accuracy of monitoring the capacitance of wound capacitors in a wide range of nominal capacitance values. made on an operational amplifier, in the negative feedback circuit of which a reference resistor is connected, and a winding capacitor, a 90 ° phase shifter and two analog-to-digital converters are connected to the inverting input, characterized in that, in order to increase the accuracy of winding the capacitor, they are additionally introduced : code-controlled voltage amplifier made on an operational amplifier, the inverting input of which is connected through a resistor to the output of the operational amplifier of the capacitor-to-voltage converter, and to the circuit negative feedback - a digital-to-analog converter, the inputs of which are connected to the outputs of a binary reversible counter, the inputs of which are connected to the outputs of the unit for recording the code of the nominal value of the capacitance of the wound capacitor, an amplifier-limiter implemented on an op-amp with an open negative feedback circuit, the output of which is connected to the start inputs of both analog-to-digital converters ^ resistor, with one output connected to the measuring frequency generator and the first input limiter, and to the other to its second input and the measuring input of the first analog-to-digital converter, as well as through a winding capacitor, to the inverting input of the operational amplifier of the capacitance-to-voltage converter, a digital comparator, the inputs of which bit digits are connected respectively to the information code outputs of the first and the second analog-to-digital converters, and its outputs through the OR element - to the Executive element stop the winding of the capacitor, and the phase shifter 90 ° is made on an operational amplifier with a capacitor in the negative feedback circuit and a variable resistor connected by one output to the inverting input of this amplifier and the other to the output of a code-controlled voltage amplifier, and the output of the operational amplifier of the phase shifter 90 ° is connected to the measuring input of the second analog-to-digital converter. Compiled by S. Chernomordnik Editor S. Kulakova Tehred M. Morgenthal Corrector M. Demchik Order 503 Circulation · Subscription • VNIIIPI of the State Committee for Inventions and Discoveries under the State Committee for Science and Technology of the USSR 113035, Moscow, Zh-35, Raushskaya nab., 4/5 Production and Publishing Plant Patent, Uzhgorod, Gagarin St. 101