RU2822988C2 - Electronically controlled resistor control device - Google Patents

Abstract

FIELD: electrical engineering; electronics.

SUBSTANCE: control device for an electronically controlled resistor (ECR) comprises an adder, an operational amplifier, a controlled current generator and a voltage divider, and also contains five leads, first and fourth of which are connected to variable resistor, second is designed to receive a feedback signal from the connection point of the measuring resistor and the external active element, the third is intended for connection of the control output of the external active element, and the fifth is connected to the low-potential output of the device.

EFFECT: wider range of technical means realizing their purpose in the form of control devices for an electronically controlled resistor (ECR), due to the possibility of using variable resistance of variable resistors for controlling the ECR.

7 cl, 4 dwg

Description

Technical field

The present invention relates to the field of electrical engineering and electronics, in particular to measuring equipment, power electronics, radio engineering and communications, as well as consumer electronics. The invention is intended to control changes in the resistance of a section of an electrical circuit using electronic means.

Prior Art

The problem of changing the resistance of a section of an electrical circuit over a wide range using electronic means is one of the pressing problems, the solution of which opens up new opportunities for the creation of automated electrical, radio-electronic and other devices of wide application, including for the Internet of Things (IoT).

The electronically controlled resistor (ECR) control device provides the formation of a control voltage that changes the resistance of the active element of the electronically controlled resistor within a wide range, depending on the magnitude of the input influence.

The mentioned ESD generally includes an active element, a measuring resistor and a control device for the ESD. The input effect is a change in the resistance of the control variable resistor, for example, a mechanical potentiometer, photoresistor, thermistor, digital potentiometer, etc., which is not part of the power steering unit.

A number of solutions are known in the art. For example, patents RU2666786, RU2661348, RU2658681, US10447167, I670920 (TW), I674742 (TW) and KR10-2054359 describe a control device for the active element of the EUR, which has the following set of essential features (see Fig. 1 of any of these publications, in which a well-known control device is shown):

- the first output of the control circuit, intended for its connection to the control voltage source;

- the second output of the control circuit, intended for its connection to the low-potential output of the power steering unit;

- the third terminal of the control circuit, which is its output and is intended for its connection to the control terminal of the active element that is part of the electronically controlled resistor.

The known control circuit further comprises an operational amplifier, a reference resistor, a feedback resistor and a constant voltage source, wherein the non-inverting input of the operational amplifier is connected to the first terminal of the reference resistor, the second terminal of which is connected to the first terminal of the control circuit.

In this case, the non-inverting input of the operational amplifier is also connected to the first terminal of the feedback resistor, the second terminal of which is connected to the output of the operational amplifier, which, in turn, is connected to the third terminal of the control circuit, in addition, the inverting input of the operational amplifier is connected to the positive pole of the DC source voltage.

The disadvantages of the known solution are:

- insufficient precision in controlling the resistance of a section of an electrical circuit, especially when exposed to destabilizing factors (for example, ambient temperature);

- the inability to use the changing resistance of variable resistors (photoresistor, thermistor, digital potentiometer, etc.) to control the resistance of a section of an electrical circuit.

As a second analogue, we chose the technical solution disclosed in the description of the invention SU1807554, published on 04/07/93 (see Fig. 2 and 3 of the publication). A known solution for controlling the resistance of a section of an electrical circuit contains:

- the first output of the control circuit, intended for its connection to the high-potential output of the power steering unit;

- the second terminal of the control circuit, which is its output and is intended for its connection to the first input of the measuring resistor included in the EUR;

- the third output of the control circuit, intended for connecting it to a source of control action in the form of a changing analog voltage;

- the fourth output of the control circuit, intended for its connection to the low-potential output of the power steering unit.

The known solution also contains:

- scheme for converting control actions;

- operational amplifier;

- feedback resistor;

- limiting resistor;

- constant voltage source.

In this case, the non-inverting input of the operational amplifier is connected to the first terminal of the limiting resistor, the second terminal of which is connected to the fourth terminal of the control circuit.

The inverting input of the operational amplifier is connected to the output of the control conversion circuit, as well as to the first terminal of the feedback resistor, the second terminal of which is connected to the output of the operational amplifier and to the second terminal of the control circuit.

The first input of the control action conversion circuit is connected to the first output of the control circuit, the second input of the control action conversion circuit is connected to the third output of the control circuit, and the third input of the control action conversion circuit is connected to the positive pole of the constant voltage source.

The output of the operational amplifier is connected to the second pin of the control circuit.

This solution has the following disadvantages:

- lack of control of the active element of the power steering;

- the inability to use for control the changing resistance of variable resistors (photoresistor, thermistor, digital potentiometer, etc.);

- inverse dependence of the EUR resistance on the control action in the form of a changing analog voltage;

- the impossibility of obtaining a sufficiently low resistance value of an electronically controlled resistor, which is often necessary in practice.

The latter is due to the fact that in the known technical solution, the current flowing through the measuring resistor is closed to a common wire through series-connected measuring and limiting resistors. Therefore, in practice, there is a dependence of the resistance value of the EUR on the resistance value of the indicated resistors. And it is possible to neglect this component only under the condition that the resistance of the measuring resistor is many times greater than the total resistance of the indicated resistors, which gives rise to the above disadvantage.

There is also a known solution for controlling the resistance of a section of an electrical circuit, disclosed in the description of the invention in US patent No. 4833472 dated May 23, 1989.

The known technical solution contains (see Fig. 1 of this publication):

- the first output of the control circuit, intended for its connection to the high-potential output of the power steering unit;

- the second terminal of the control circuit, intended for its connection to the first terminal of the measuring resistor, which is part of the EUR;

- the third output (group of outputs) of the control circuit, intended for its connection to the source of control digital codes;

- the fourth output of the control circuit, intended for its connection to the low-potential output of the power steering unit;

- the fifth terminal of the control circuit, which is its output and is intended for its connection to the control terminal of the active element included in the EUR.

The known control circuit also contains an operational amplifier, a multiplier and a digital-to-analog converter.

In this case, the non-inverting input of the operational amplifier is connected to the first output of the control circuit.

The inverting input of the operational amplifier is connected to the output of a digital-to-analog converter, the inputs of which are connected to the outputs of the multiplier, and the output of the operational amplifier is connected to the fifth pin of the control circuit.

The third output (group of outputs) of the control device is connected to the first input (group of inputs) of the multiplier, and the second input of the multiplier is connected to the second output of the control circuit.

The main disadvantage of the known solution is the inability to use the changing resistance of variable resistors (photoresistor, thermistor, digital potentiometer, etc.) for control.

A solution for controlling the resistance of a section of an electrical circuit is also known, disclosed in the description of the invention JPS5111404 dated October 7, 1976.

The known technical solution contains (see Fig. 1 of this publication):

- the first output of the control circuit, intended for its connection to the high-potential output of the power steering unit;

- the second terminal of the control circuit, intended for its connection to the first terminal of the measuring resistor, which is part of the EUR;

- the third output (group of outputs) of the control circuit, intended for its connection to the source of control digital codes;

- the fourth output of the control circuit, intended for its connection to the second output of the source of control digital codes;

- the fifth output of the control circuit, intended for its connection to the low-potential output of the power steering unit;

- the sixth terminal of the control circuit, which is its output and is intended for its connection to the control terminal of the active element included in the EUR.

The known control circuit also contains an output and intermediate operational amplifiers, a repeater, an inverter, a bias resistor, a reference resistor, and a digital-to-analog converter.

In this case, the repeater input is connected to the first output of the control circuit, and its output is connected to the first output of the reference resistor, the second output of which is connected to the inverting input of the intermediate operational amplifier.

The inverting input of the intermediate operational amplifier is also connected through a bias resistor to the output of the digital-to-analog converter, the inputs of which are connected to the third pin (group of pins) of the control circuit.

The non-inverting input of the intermediate operational amplifier is connected to the fifth terminal of the control circuit, and its output is connected through an inverter to the non-inverting input of the output operational amplifier, the inverting input of which is connected to the second terminal of the control circuit.

The disadvantage of the known solution is the inability to use the changing resistance of variable resistors (photoresistor, thermistor, digital potentiometer, etc.) for control.

A solution for controlling the resistance of an electrical circuit section is also known, disclosed in the description of the application for the invention DE 3239309 dated April 26, 1984.

A known solution for controlling the resistance of a section of an electrical circuit contains (see Fig. 2 of this publication):

- the first output of the control circuit, intended for its connection to the high-potential output of the power steering unit;

- the second output of the control circuit, intended for its connection to the first output of the current-voltage converter, which is part of the EUR;

- the third output of the control circuit, intended for its connection to the control voltage source, made in the form of a digital-to-analog converter;

- the fourth terminal of the control circuit, intended for its connection to the second terminal of the control voltage source;

- the fifth output of the control circuit, intended for its connection to the low-potential output of the power steering unit;

- the sixth terminal of the control circuit, which is its output and is intended for its connection to the control terminal of the active element included in the EUR.

The known control circuit also contains an operational amplifier and an analog voltage-to-current divider.

In this case, the inverting input of the operational amplifier is connected to the second output of the control circuit, and the non-inverting input of the operational amplifier is connected to the output of the analog voltage-to-current divider.

The main disadvantage of the known solution is the inability to use the changing resistance of variable resistors (photoresistor, thermistor, digital potentiometer, etc.) for control.

The technical solution disclosed in the description of the European application for the invention EP3182243A1, dated June 21, 2017, was chosen as the closest prototype analogue. The known solution for controlling the resistance of a section of an electrical circuit contains (see Fig. 1 of the specified publication, which is similar to Fig. 1 of this application) :

- the first output of the control circuit, intended for its connection to the high-potential output of the power steering unit;

- the second terminal of the control circuit, intended for its connection to the first terminal of the measuring resistor, which is part of the EUR;

- the third terminal of the control circuit, intended for its connection to the first terminal of the control resistor;

- the fourth terminal of the control circuit, intended for its connection to the second terminal of the variable control resistor;

- the fifth output of the control circuit, intended for its connection to the low-potential output of the power steering unit;

- the sixth output of the control circuit, which is its output and is intended for its connection to the control input of the active element included in the EUR.

The known control circuit also contains an operational amplifier, a reference resistor, a constant voltage source and an uncontrolled current generator.

In this case, the non-inverting input of the operational amplifier is connected to the fourth terminal of the control device and to the first terminal of the reference resistor, the second terminal of which is connected to the fifth terminal of the control circuit.

The inverting input of the operational amplifier is connected to the second pin of the control circuit.

The output of the operational amplifier is connected to the sixth pin of the control circuit.

The first and third terminals of the control device are interconnected and connected to the output of an uncontrolled current generator, the input of which is connected to the positive pole of a constant voltage source.

The disadvantage of the known technical solution is the impossibility of using digital potentiometers with a grounded terminal (for example, ISL90728WIE627Z-TK, TPL0401A-10DCKR, MCP4018T-103E/LT and many others) as a control resistor.

Digital potentiometers have neither active elements nor sense resistors, and are thus not part of the prior art.

Accordingly, in this field of technology there is a need for an EUR control device that allows you to accurately set its resistance and at the same time ensure a linear (proportional) dependence of the EUR resistance on the resistance of the control variable resistor (photoresistor, thermistor, digital potentiometer of any modification, including one with a grounded terminal , and so on.).

Brief description of the invention

The purpose of the present invention is to overcome the disadvantages of known solutions and to create such control devices for electronically controlled resistors that provide accurate setting of the required (including quite small) resistance value of an electrical circuit section within a wide range, while allowing the use of various types of variable control resistors, including digital potentiometers of any modification, for the mentioned setting of the required resistance value while ensuring a linear (proportional) dependence of the EUR resistance on the resistance of the variable control resistor.

The technical result of the present invention lies in the possibility of using digital potentiometers of any modification as a variable control resistor for the electric power steering system, which expands the arsenal of technical means that realize their purpose in the form of electric power steering control devices.

In the following description and formula, if an element is said to be “connected” to another element, then the element may be “directly connected” to the other element or “electrically connected” through a third element.

In addition, unless otherwise specifically provided, the term “comprises” and its derivatives (“comprising,” “contained,” “including,” and other similar terms) are understood to include the specified elements and not to exclude any other elements.

On the one hand, to achieve the specified technical result, the EUR control device (one of the implementations of which is shown in Fig. 2) may contain: a current generator that generates an output current; an amplifier that receives an input voltage proportional to the output current and supplies the amplified input voltage to the first input of the adder; a voltage divider containing a bias resistor and a reference resistor connected in series between the high-potential and low-potential terminals of the power steering unit; a buffer cascade that receives the output signal of the measuring resistor included in the power steering unit, and the output voltage of the buffer cascade is supplied to the current generator and to the second input of the adder, at the output of which the total voltage is formed. In addition, the EUR control device may contain an operational amplifier, the first input of which receives voltage from the midpoint of the divider, the second input of which receives the total voltage, and the output generates a control voltage supplied to the active element of the EUR.

In addition to the above, the variable control resistor with one of its terminals is connected to the low-potential terminal of the EUR, and with its second terminal it is connected to the current output of the control device, while the input voltage of the control device is the voltage across the variable resistor. In addition to the above, the active element of the EUR can be a field-effect transistor. In addition to the above, the current generator is a controlled current generator. In addition to the above, the active element and the measuring resistor included in the EUR can be connected in series.

In addition to the above, a controlled current generator (one implementation of which is shown in Fig. 3) may contain a second operational amplifier that receives the output voltage of the buffer stage and a voltage proportional to the resistance of the first resistor of the controlled current generator; a first transistor receiving an output voltage of the second operational amplifier and outputting a driving current to the first resistor; a second resistor connected in series between the voltage source and the first transistor, wherein the connection point of the second resistor and the first transistor is connected to the first input of the third operational amplifier; a third resistor connected in series between the voltage source and the second transistor, wherein the connection point of the third resistor and the second transistor is connected to the second input of the third operational amplifier; a second transistor that receives the output voltage of the third operational amplifier and supplies a controlled current to the output of the controlled current generator.

On the other hand, the EUR containing the above-described control device may contain: a current generator generating an output current; an amplifier that receives an input voltage proportional to the output current and the resistance value of the variable control resistor, and supplies the amplified input voltage to the first input of the adder; a voltage divider containing a bias resistor and a reference resistor connected in series between the high-potential and low-potential terminals of the power steering unit; an active element and a measuring resistor connected in series between the high-potential and low-potential terminals of the power steering unit; a buffer cascade that receives the output signal of the measuring resistor included in the power steering unit, and the output voltage of the buffer cascade is supplied to the current generator and to the second input of the adder, at the output of which the total voltage is formed. In addition, the EUR control device may contain an operational amplifier, the first input of which receives voltage from the midpoint of the divider, the second input of which receives the total voltage, and the output generates a control voltage supplied to the active element of the EUR.

In addition to the above, the variable control resistor with one of its terminals is connected to the low-potential terminal of the EUR, and with its second terminal it is connected to the current output of the control device, while the input voltage of the control device is the voltage across the variable resistor. In addition to the above, the active element of the EUR can be a field-effect transistor. In addition to the above, the current generator is a controlled current generator.

In addition to the above, the controlled current generator may comprise a second operational amplifier that receives the output voltage of the buffer stage and a voltage proportional to the resistance of the first resistor of the controlled current generator; a first transistor receiving an output voltage of the second operational amplifier and outputting a driving current to the first resistor; a second resistor connected in series between the voltage source and the first transistor, wherein the connection point of the second resistor and the first transistor is connected to the first input of the third operational amplifier; a third resistor connected in series between the voltage source and the second transistor, wherein the connection point of the third resistor and the second transistor is connected to the second input of the third operational amplifier; a second transistor that receives the output voltage of the third operational amplifier and supplies a controlled current to the output of the controlled current generator.

Additional features and advantages of the present invention will be set forth in the description that follows, will be apparent in part from the description, or may be learned by practice of the invention. The advantages of the invention will be realized and achieved by the structure specifically indicated in the description and claims, as well as in the accompanying drawings.

It is to be understood that both the foregoing general description and the following detailed description are illustrative and explanatory and are intended to further explain the claimed invention.

Brief description of the attached drawings

The accompanying drawings, which are presented to further the understanding of the claimed invention, are included in this specification and constitute a part thereof, illustrate embodiments of the invention and, together with the description, serve to explain the principles of operation of the claimed invention.

On the drawings:

Figure 1 shows a diagram of the prototype device (Prior art).

Figure 2 shows one of the possible options for implementing a control device for the active element of the EUR under control action in the form of changing resistance of a variable resistor (for example, a mechanical potentiometer, photoresistor, thermistor, digital potentiometer, etc.).

Figure 3 shows one of the possible implementation options for a controlled current generator included in the control device.

Figure 4 shows the experimental results of device prototyping.

Detailed Description of the Invention

Next, the features of the implementation of the claimed invention will be discussed in detail, illustrated by the attached drawings.

In order to achieve the above technical result, the proposed device includes (see Fig. 2, which illustrates an exemplary embodiment of the control device 220 for an electronically controlled resistor 222) the following elements and their connections:

- the first terminal 1 of the control device 220, intended for its connection to the first terminal of the variable control resistor Rc;

- the second terminal 2 of the control device 220, intended for its connection to the first terminal of the measuring resistor Rsense, which is part of the EUR 222;

- the third terminal 3 of the control device 220, intended for its connection to the control terminal of the active element 224, which is part of the EUR 222;

- the fourth terminal 4 of the control device 220, intended for its connection to the second terminal of the variable control resistor Rc;

- the fifth terminal 5 of the control device 220, intended for its connection to the low-potential terminal 12 of the EUR 222;

- the sixth terminal 6 of the control device 220, intended for its connection to the high-potential terminal 10 of the EUR 222

- operational amplifier 208;

- reference resistor R _ref ; and

- a constant voltage source 214 (for example, a battery), with the non-inverting input of the operational amplifier 208 connected to the first terminal of the reference resistor R _ref , the second terminal of which is connected to the fifth terminal 5 of the control device 220, and the output of the operational amplifier 208 is connected to the third terminal 3 of the control device 220.

The control device 220 is additionally equipped with:

- bias resistor R _bias ;

- amplifier 204;

- adder 206;

- buffer cascade 210; and

- controlled current generator 212,

wherein

- the first pin of the bias resistor R _bias is connected to the sixth pin 6 of device 220, and the second pin of the bias resistor R _bias is connected to the non-inverting input of the operational amplifier 208,

- the input of the amplifier 204 is connected to the first pin 1 of the device, and the output of the amplifier 204 is connected to the first input of the adder 206, the output of which is connected to the inverting input of the operational amplifier 208,

- the second output 2 of the device is connected to the input of the buffer stage 210, the output of which is connected to both the second input of the adder 206 and the control input 24 of the controlled current generator 212,

- power input 22 of said controlled current generator 212 is connected to the positive terminal of the DC power supply 214, the negative terminal of which is connected to the common wire,

and

- output 26 of the mentioned controlled current generator 212 is connected to the mentioned first terminal 1 of the device, designed to supply through it a control action in the form of a changing resistance of the variable control resistor R _c .

The introduction of a bias resistor R _bias , an amplifier 204, an adder 206, a buffer stage 210 and a controlled current generator 212 with corresponding connections, according to the proposed technical solution, allows, in the process of converting the voltage U ₁ coming from the high-potential pin 10 of the EUR 222, to create at the non-inverting input operational amplifier 208 potential:

U ₁ ' = U ₁ * R _ref /( R _ref + R _bias ), (1)

where Rbias is the resistance value of the mentioned bias resistor,

Rref - value of the resistance of the reference resistor.

At the same time, the inverting input of the operational amplifier 208 receives the sum signal S, the terms of which are formed as follows:

The first term, S ₁ , is supplied to the first input of the adder 206 from the first output 1 of the inventive device 220 through an amplifier 204 with a gain K' and represents an amplified voltage drop across the variable control resistor R _c created by the current Icg of the controlled current generator 212, i.e. e.

S ₁ = K' * Icg* R _s . (2)

The second term, S ₂ , is supplied to the second input of the adder 206 from the second output 2 of the proposed device through a buffer stage 210 with a unity transfer coefficient and represents the voltage U ₂ from the measuring resistor R _sense , which is part of the EUR 222, controlled by the proposed device 220.

This voltage is determined by the formula:

U ₂ = I ₀ * R _sense , (3)

where R _sense is the value of the measuring resistor, which can be chosen as small as possible from the point of view of technical implementation,

I ₀ is the magnitude of the current that flows through the electronically controlled resistor 222 and is set by the active element 224, which is part of the power steering unit 222.

Hence,

S ₂ = U ₂ = I ₀ * R _sense . (4)

And the value of the total signal S at the inverting input of the operational amplifier 208 is equal to:

S=S₁+ S₂= K’ * Icg* R_With +I₀ *R_sense. (5)

Let us now take into account that the current Icg of the controlled current generator 212 depends on the voltage U ₂ supplied to the control input 24 of the controlled current generator from the output of the buffer stage 210, i.e.

Icg=U₂*Gcg =I₀ *R_sense * Gcg, (6)

where Gcg is the conversion coefficient of the control voltage U ₂ into a current having the dimension of conductivity.

Therefore, based on formulas (5) and (6), we obtain that:

S=K' *I₀ *R_sense *Gcg*R_With +I₀ *R_sense =I₀*R_sense *(1+ K' *R_With *Gcg). (7)

The difference between U ₁ ' and S from the output of the operational amplifier 208 is supplied in the form of a control signal U _contr (U _contr = U ₁ ' - S) to the third pin 3 of the control circuit 220, intended for its connection to the control pin of the active element 224 included in composition of EUR 222, i.e. to the output of the proposed device. Due to the large gain in the feedback circuit (operational amplifier 208 - active element 224 EUR - measuring resistor Rsense - buffer stage 210 - adder 206 - operational amplifier 208), the relation U ₁ '≈ S is satisfied with sufficient accuracy for practice.

Therefore, see (1) and (7):

U₁*R_ref /( R_ref + R_bias) = I₀ *R_sense *(1+ K' *R_With *Gcg) . (8)

It immediately follows that R ₀ - the resistance of the electric power steering between the high-potential terminal 10 and the low-potential terminal 12 - is equal to:

R₀ = U₁ / I₀ = R_sense *(1+ K' *R_With * Gcg) /(1+ R_bias /R_ref). (9)

From formula (9) it is clear that the resistance of the power steering according to the proposed technical solution is directly proportional to the resistance value of the measuring resistor Rsense, as well as proportional to the value of the control action, which corresponds to the resistance of the variable control resistor Rc (for example, a digital potentiometer).

From formula (9) it also follows that it is possible to obtain small and ultra-small values of R _O at small values of R _sense , while simultaneously fulfilling the following relations:

R _c * (K' * Gcg) << 1 and R _bias ≈ R _ref . (10)

As a variable control resistor R _c , just like in the prototype, a mechanical potentiometer, photoresistor or thermistor can be used.

Unlike the prototype, it is possible to use digital potentiometers of any modification, including those with a grounded terminal, as a variable control resistor of the power steering unit, which makes it possible to achieve the above technical result.

The proposed control device for an electronically controlled resistor according to Fig. 2 operates as follows.

When the control action changes, corresponding to a change in the resistance value of the variable control resistor R _c (for example, a digital potentiometer), the voltage U _Rc is transmitted from this resistor through the amplifier 204, which has a transmission coefficient K', and is supplied to the first input of the adder 206 in the form of the first term S ₁ = K'*U _Rc . The second input of the adder 206 through the buffer stage 210 receives the second term S ₂ in the form of voltage U ₂ from the measuring resistor R _sense , which is part of the EUR 222. The specified voltage is determined by formula (3), that is, U ₂ = I ₀ * Rsense, therefore and S ₂ = I ₀ * Rsense (see formula (4)),

where Rsense is the value of the measuring resistor, which can be chosen as small as possible from the point of view of technical implementation.

The voltage value U ₂ , as indicated above, is equal to the voltage drop across the measuring resistor R _sense created by the current I ₀ flowing through the EUR 222. In fact, the current I ₀ flows through the circuit: high-potential pin 10 of the EUR 222 - active element 224 - connected in series with it measuring resistor R _sense - low-potential terminal 12 of the EUR 222 (due to the presence of a potential difference U ₁ between the high-potential 10 and low-potential 12 terminals of the EUR 222).

Thus, as a result of summing the voltages K'*U _Rc and U ₂ , i.e.

K'*U_Rc= S₁ and U_{2 =}S₂= I₀ * Rense,

An intermediate signal is generated at the output of adder 206:

S = S₁+S₂ = K'*U_Rc+I₀ *R_sense, (eleven)

which is supplied to the inverting input of operational amplifier 208.

At the same time, from the sixth pin 6 of device 220, through a divider formed by the bias resistor R _bias and the reference resistor R _ref , a potential U ₁ ' equal to (see formula (1)) is supplied to the non-inverting input of the operational amplifier 208, equal to (see formula (1)): U ₁ ' = U ₁ /( 1+ R _bias / R _ref ).

From the output of the operational amplifier 208 to the third pin 3 of the inventive device 220, intended for its connection to the control terminal of the active element 224, which is part of the electronically controlled resistor 222, i.e. the output of the inventive device receives the difference between the values of S and U ₁ ' in the form of control voltage U _contr (U _contr = U ₁ ' - S). From the third pin 3 of the inventive device 220, the control voltage U _contr is supplied to the control pin of the active element 224.

Moreover, if the value of the intermediate signal S at the inverting input of the operational amplifier 208 is greater than the voltage value U₁', then the voltage U_contrat the control terminal of the active element 224 closes the active element 224, current I₀ decreases through it, resulting in a decrease in voltage U₂, which through the buffer stage 210 is supplied to the second input of the adder 206 in the form of the second term. S2 = I₀* Rsense, see formula (4). In addition, voltage U₂ arrives at the control input 24 of the controlled current generator 212 and reduces its current Icg in accordance with formula (6): Icg= U₂*Gcg = I₀ *Rsense*Gcg,

where Gcg is the conversion coefficient of control voltage U ₂ into current, which has the dimension of conductivity.

Decrease current Icg controlled current generator 212 leads to a decrease in the voltage drop across the variable control resistor Rc (for example, on a digital potentiometer), as a result, after amplification by K' times in the amplifier 204, the first term S also decreases₁at the first input of the adder 206, which has the form (based on formulas (2) and (6)):

S ₁ = K' * Icg* _Rc = I ₀ * Rsense * Gcg* K' * Rc. (12)

As a result of summing the terms S₁and S₂in adder 206, an intermediate signal is generated at its output (see formula (7)): S = I₀*R_sense *(1+ K' *R_With * Gcg), which decreases due to the previously described decrease in current I₀.

And due to the large gain of the operational amplifier 208, this process will occur until the intermediate signal S at the inverting input of the operational amplifier 208 will not be equal to the value of U₁' at the non-inverting input of op-amp 208.

On the other hand, if the magnitude of the intermediate signal S at the output of the adder 206 is less than the magnitude of the voltage U₁', then the voltage U_contrat the control terminal of the active element 224 slightly opens the active element 224, current I₀ increases through it, resulting in an increase in voltage U₂, which through the buffer stage 210 is supplied to the second input of the adder 206 in the form of the second term S₂= I₀ *R_sense, see formula (4). In addition, voltage U₂ is supplied to the control input 24 of the controlled current generator 212 and increases its current Icg in accordance with formula (6):

Icg= U ₂ *Gcg = I ₀ * Rsense * Gcg,

In this case, the first term also increases: S ₁ = I ₀ * Rsense * Gcg* К' * Rс (according to formula (12)) _.

As a result of the summation of two increasing terms S ₁ and S ₂ in the adder 206, an intermediate signal S is formed at its output, described by formula (7), which increases due to the previously described increase in current I ₀ .

And due to the large gain of amplifier 208, this process will occur until the intermediate signal S at the inverting input of the operational amplifier 208 will not again become equal to the value of U₁' at the non-inverting input of the operational amplifier 208, i.e. S=U₁'.

Thus, due to the presence of deep feedback covering the operational amplifier 208 - active element 224 EUR 222 - measuring resistor R _sense - buffer stage 210 - adder 206 - operational amplifier 208 in the proposed technical solution, the relation S = will always be satisfied with sufficient accuracy for practice U ₁ '.

Or, substituting the corresponding values from (1) and (11), we again obtain formula (8):

U ₁ * Rref /( Rref + Rbias) = I ₀ * Rsense *(1+ K' * Rс * Gcg)

Relation (8) is stably satisfied under the influence of various destabilizing factors, including temperature changes over a wide range, which is ensured by the depth of the mentioned feedback.

Let us now take into account that the value of resistance R ₀ between the high-potential terminal 10 of the EUR 222 and its low-potential terminal 12 is equal to the quotient of voltage U ₁ divided by the current I ₀ flowing through the circuit: high-potential terminal 10 of the EUR 222 - active element 224 - connected in series with it is the measuring resistor R _sense - low-potential terminal 12 EUR 222 i.e.

R ₀ = U ₁ / I ₀ . (13)

From relations (8) and (13) we obtain the resistance value between the high-potential output of the EUR 222 and its low-potential output:

R₀ =U₁ /I₀ = R_sense *(1+ K' *R_With * Gcg) /(1+ R_bias/R_ref),

which corresponds to formula (9).

Thus, it has been proven that by generating an intermediate signal at the output of the adder 206 in the form (7): S= I₀*R_sense *(1+ K' *R_With *Gcg),

further supplying this signal to the second (inverting) input of the operational amplifier 208, applying to the first (non-inverting) input of the operational amplifier a potential (see formula 1) equal to U₁' = U₁/(1+ R_bias/R_ref), and ensuring equality S = U₁' due to the deep feedback described above, the value of R₀resistance of EUR 222 in the proposed technical solution is directly proportional to the resistance value of the measuring resistor R_sense, and is also proportional to the value control action, which corresponds to the resistance value of the variable control resistor R_c (eg digital potentiometer).

From relation (9) it follows that it is possible to obtain small and ultra-small values of R _O with a sufficiently large current I ₀ , which is provided by the active element 224. Thus, to control the resistance of a section of the electrical circuit, a control action corresponding to the value of the changing resistance Rc is used (for example, a digital potentiometer ), and the resistance of the EUR 222 is proportional to the magnitude of the control action, which corresponds to the resistance value of the variable control resistor R _c (for example, a digital potentiometer).

In Fig. 3 indicates the following elements of the controlled current generator 212:

- 302 - second operational amplifier;

- 303 - third operational amplifier;

- 311 - first MOSFET;

- 312 - second field-effect transistor;

- Rcg1 is the first resistor of the controlled current generator 212;

- Rcg2 - second resistor of the controlled current generator 212;

- Rcg3 - third resistor of the controlled current generator 212;

Controlled current generator 212 according to Fig. 3 works as follows.

The signal S ₂ , which is the control signal for the controlled current generator 212, is supplied to its control input 24 and then to the non-inverting input (+) of the second operational amplifier 302, the output of which is connected to the gate of the first MOSFET 311. The source of the first MOSFET is - transistor 311 is connected to the inverting input (-) of the second operational amplifier 302 and to the first terminal of the first resistor Rcg1 of the controlled current generator 212, the second terminal 28 of the first resistor Rcg1 is connected to the low-potential terminal 12 of the EUR 222 (see also Fig. 2). A current Icg1 flows through the drain-source circuit of the first MOSFET 311, which creates a voltage drop across the first resistor Rcg1 of the controlled current generator 212:

U cg1 = Icg1* Rcg1. (14)

Due to the deep feedback between the second operational amplifier 302 and the first MOSFET 311, the signal S ₂ at the non-inverting input (+) of the second operational amplifier and the voltage Ucg1 at its inverting input (-) are equal to each other with sufficient accuracy for practice, those.

S ₂ = U cg1. (15)

Hence, the current flowing through the first MOSFET 311 is

Icg1 = S ₂ / Rcg1, (16)

and this current creates a voltage drop on the second resistor Rcg2 of the controlled current generator 212:

U cg2 = Icg1 * Rcg2. (17)

Since the first terminal of the second resistor Rcg2 is connected to terminal 22 of the controlled current generator 212, which is supplied with supply voltage E, and the second terminal of the second resistor Rcg2 is connected to the non-inverting input (+) of the third operational amplifier 303, a voltage appears at the specified input

U ₊₃₀₃ = E ̶ U cg2. (18)

The output of the third operational amplifier 303 is connected to the gate of the second MOSFET 312, the drain of which is connected to the inverting input (-) of the third operational amplifier 303 and to the first terminal of the third resistor Rcg3, the second terminal of which is connected to terminal 22 of the controlled current generator 212, to which supply voltage E is supplied.

The drain-source circuit of the second MOSFET 312 carries the output current Icg of the controlled current generator 212, which is supplied to terminal 26 of the controlled current generator 212. The output current Icg creates a voltage drop across the third resistor Rcg3 of the controlled current generator 212

U cg3 = Icg* Rcg3. (19)

As a result, the following voltage is supplied to the inverting input (-) of the third operational amplifier 303 from the first terminal of the third resistor Rcg3:

U _-303 = E ̶ U cg3. (20)

Due to the deep feedback between the third operational amplifier 303 and the second MOSFET 312, the voltage values at the non-inverting input (+) and at the inverting input (-) of the third operational amplifier 303 are equal to each other with sufficient accuracy for practice, i.e. .

U ₊₃₀₃ = U _-303 . (21)

From where it immediately follows, see (18) and (20):

Ucg2 = Ucg3. (22)

And, taking into account (17) and (19)

Icg1 * Rcg2 = Icg* Rcg3. (23)

Therefore, the output current Icg of the controlled current generator 212

Icg = Icg 1 * Rcg2 / Rcg3. (24)

And since Icg1 depends on the control signal S2 (see 16), we get:

Icg = S ₂ * Rcg2 / (Rcg1 * Rcg3). (25)

Or, taking into account the fact that the signal S ₂ is identically equal to the voltage U ₂ coming from the measuring resistor R _sense , which is part of the EUR 222, we finally get

Icg = U ₂ * Rcg2 / (Rcg1 * Rcg3). (26)

And this current does not depend on the resistance of the variable control resistor Rc, external to the controlled current generator 212, but is determined only by the internal resistances of the controlled current generator 212 and the control voltage U ₂ coming from the measuring resistor Rsense.

Magnitude

Gcg = Rcg2 / (Rcg1* Rcg3) (27)

characterizes the conversion coefficient of control voltage U ₂ into current, has the dimension of conductivity and is used to determine the resistance value of the EUR 222 in the proposed technical solution. Thus, a controlled current generator 212, made, for example, according to Fig. 3, ensures the operation of the claimed device and obtains the stated technical result.

The controlled current generator 212 can be implemented in other ways, for example, according to the diagram given in the source "LT 1789. Technical description and product information", LINEAR TECHNOLOGY CORPORATION 2002, drawing "0.5A to 4A Voltage Controlled Current Source" (see. also on the Internet https://www.analog.com/ru/products/lt1789.html#product-overview).

Also, the controlled current generator 212 can be made, for example, according to the diagram given in the Electrical Engineering Stack Exchange, article “How should I design variable current source of 4-20mA with 24Vdc input?” (See online https://electronics.stackexchange.com/questions/72192/how-should-i-design-variable-currentsource-of-4-20ma-with-24vdc-input?rq=1).

It is also possible to implement a controlled current generator 212 based on the LT 6552 chip, as shown in the article “Voltage controlled current source—ground referred input and output”, Jim Williams, in Analog Circuit Design, 2013 (https://www.sciencedirect.com /topics/engineering/controlled-current-source), and many other ways.

The voltage divider can be a resistive divider, or can be made in the form of a divider consisting of two transistors connected in series, or in any other way that ensures that part of the voltage from the high-potential output 10 of the EUR 222 is supplied to the non-inverting input of the operational amplifier 208.

The voltage divider can also be external to the control device 220 and can be connected to it through a separate output, which makes it possible not to supply voltage to the control device 220 from the high-potential pin 10 of the EUR 222.

The amplifier 204, buffer stage 210 and adder 206 may have different circuit designs that ensure the functionality of the inventive control device.

The control device 220 may be implemented on standard electronic components, such as operational amplifiers, transistors, and resistors, or on integrated circuits, including custom integrated circuits. For example, amplifier 204, buffer stage 210, controlled current generator 212 can be implemented on operational amplifier chips OPA189, TLV9002IDR, MCP6002-E/SN and many others. Main parameters of the microcircuits: OPEN-LOOP GAIN (load = 10 kΩ) no less than 100 dB; Gain-bandwidth product at least 1 MHz; Rail-to-rail entry and exit. The same microcircuits can be used as an operational amplifier 208. Transistors NTNUS3171PZ, NX3020NAK and the like can be used as transistors of the controlled current generator 212. Main parameters: RDS (on) no more than 5.5 Ohm, drain current I ₀ no less than 100 mA.

The remaining elements of the EUR control device (adder 206, constant voltage source 214) are trivial and can be made in any known way.

The resistor values can be selected as follows:

Rbias within 100... 200 kOhm;

Rref within 50… 100 kOhm.

The resistor values of the controlled current generator Rcg1, Rcg2, Rcg3 are selected within the range of 200 Ohm...1 kOhm.

The value of the measuring resistor R _sense , depending on what value the EUR 222 needs to be obtained, can be selected from 10 milliOhms or more (for example, up to 100 Ohms). Various transistors can be used as an active element, including MOSFETs, for example, the STT6N3LLH6 transistor or its analogues, if its RDS(on) is an order of magnitude less than the nominal value of the EUR 222.

The claimed control device 220 for the EUR 222 can be made, for example, in the form of a microcircuit, microassembly or microboard. The EUR 222 itself can also be manufactured, for example, in the form of a microcircuit, microassembly or microboard.

It is preferable to implement the control device 220 EUR 222 in the form of an integrated circuit, which makes it possible to significantly reduce the dimensions of the device and reduce production costs. For relatively low-power ESD (the total power dissipation on the active element and the measuring resistor does not exceed 1-2 W), it is advisable to implement the control device, the active element and the measuring resistor as a single integrated circuit. In both cases, the voltage divider can either be part of the integrated circuit or be external to it.

Experimental results

In order to confirm the achievability of the stated technical result, prototyping of the control device 220 was carried out, corresponding to Fig. 2, Fig. 3.

Layout results:

Supply voltage: 5V±5%

Minimum resistance of the variable control resistor R _c (for example, digital potentiometer): 100 Ohm.

Maximum resistance of variable control resistor R _c (for example, digital potentiometer): 10000 Ohms.

Minimum resistance of the electric power steering R _0min : 383.5 Ohms.

Maximum resistance of the electric power steering R _0max : 26225.9 Ohms.

EUR resistance adjustment range: 68.4 times.

The nonlinearity of the dependence of the resistance of the EUR 222 on the resistance of the variable control resistor R _c (for example, a digital potentiometer) is no more than 1.4%.

The dependence of the resistance of the EUR 222 R ₀ on the resistance of the variable control resistor R _c is shown in Fig. 4 and represents a straight line, while the measured resistance values are at a glance indistinguishable from the calculated ones.

From the given data it follows that the claimed technical solution actually provides the above technical result.

However, the claimed invention is not limited to the above.

The claimed invention is described on the basis of what is currently considered to be practically possible implementation of various embodiments of the device. However, it should be borne in mind that the claimed invention is not limited to the above embodiments, but, on the contrary, is intended for use in various modifications and equivalent embodiments that correspond to the ideas and spirit of the formula below.

Accordingly, the drawings and description of operation are illustrative and do not limit the ability to implement the invention.

The claimed technical solution is defined by the following claims.

Claims (7)

1. A control device (220) for an electronically controlled resistor (ECR) (222), containing: a first operational amplifier (208), a reference resistor (Rref), a constant voltage source (214), a first terminal (1) of the device (220) , designed to connect the first terminal of the external control variable resistor (Rc), the second terminal (2) of the device (220), designed to receive a feedback signal from the point of connection of the external measuring resistor (Rsense) with the external active element, the third terminal (3) of the device (220), intended for connecting the control terminal of the external active element (224), the fourth terminal (4) of the device (220), intended for connecting the second terminal of the external control variable resistor (Rc), the fifth terminal (5) of the device (220), intended for its connection to the low-potential terminal (12) of the EUR (222), the sixth terminal (6) of the device (220), intended for its connection to the high-potential terminal (10) of the EUR (222), and: the output of the first operational amplifier (208) is connected to the third (3) terminal of the device (220), the first terminal of the reference resistor (Rref) is connected to the non-inverting input of the first operational amplifier (208), and the second terminal of the reference resistor (Rref) is connected to the fifth (5) terminal of the device (220), characterized in that that the device (220) is equipped with a bias resistor (Rbias), the first terminal of which is connected to the sixth (6) terminal of the device (220), and the second terminal is connected to the non-inverting input of the first operational amplifier (208), an adder (206), the first input of which is designed to be connected to the first terminal (1) of the device (220), the second input of the adder 206 is intended to be connected to the second terminal (2) of the device (220), and the output of the adder 206 is connected to the inverting input of the first operational amplifier (208), and also controlled by a current generator (212) containing a second operational amplifier (302), a third operational amplifier (303), a first transistor (311), a second transistor (312), a first resistor (Rcg1), a second resistor (Rcg2) and a third resistor ( Rcg3), and the control input (24) of the controlled current generator (212) is connected to the second (2) output of the device (220) and to the non-inverting input of the second operational amplifier (302), the inverting input of which is connected to the connection point of the first transistor (311) and the first resistor (Rcg1) connected in series with it, and the output of the second operational amplifier (302) is connected to the gate of the first transistor (311), the output (26) of the controlled current generator (212) is intended for connection to the first (1) terminal of the device (220) , to the inverting input of the first operational amplifier (208) and to the second transistor (312), the gate of which is connected to the output of the third operational amplifier (303), the non-inverting input of the third operational amplifier (303) is connected to the connection point of the first transistor (311) and in series a second resistor (Rcg2) connected thereto, and the inverting input of said third operational amplifier (303) is connected to a junction point of said second transistor (312) and a third resistor (Rcg3) connected in series therewith, wherein the common point of the second resistor (Rcg2) and the third resistor (Rcg3) is connected to the terminal (22) of the controlled current generator (212), intended for its connection to the DC power source (214), and the fourth (4) and fifth (5) terminals of the device (220) are connected to each other. 2. Device (220) according to claim 1, additionally containing a buffer stage (210) connected between the second (2) output of the device (220) and the input (24) of the controlled current generator (212), in addition, the output of the buffer stage (210 ) is also connected to the first input of the adder 206. 3. The device (220) according to claim 1, further comprising an amplifier (204) between the first (1) output of the device (220) and the first input of the adder (206). 4. Electronically controlled resistor (ECR) (222) for use with a variable control resistor (Rc), containing a series-connected high-potential terminal (10), an active element (224), a measuring resistor (Rsense) and a low-potential terminal (12), different in that the EUR (222) additionally contains a control device (220) according to claim 1, and the high-potential terminal (10) of the EUR (222) is connected to the sixth terminal (6) of the control device (220), the low-potential terminal (12) of the EUR (222 ) is connected to the fifth terminal (5) of the control device (220), the control terminal of the active element (224) is connected to the third terminal (3) of the control device (220), the connection point of the active element (224) and the measuring resistor (Rsense) is connected to the second terminal (2) of the control device (220), the first terminal (1) of the control device (220) is intended to be connected to the first terminal of the variable control resistor (Rc), and the fourth terminal (4) of the control device (220) is intended to be connected to the second terminal variable control resistor (Rc). 5. EUR (222) according to claim 4, in which the active element (224) is a transistor. 6. Integrated circuit (IC) of the control device (220) for the power steering unit (222), containing the first operational amplifier (208), a reference resistor (Rref), a bias resistor (Rbias), the first pin (1) of the IC, designed to connect the first pin external control variable resistor (Rc), second pin (2) of the IC, intended for receiving a feedback signal from the point of connection of the external measuring resistor (Rsense) with the external active element (224), third pin (3) of the IC, intended for connecting the control pin external active element (224), fourth (4) terminal of the IC, intended for connecting the second terminal of the external control variable resistor (Rc), fifth (5) terminal of the IC, intended for connecting it to the low-potential terminal (12) of the EUR (222), sixth (6) an IC pin intended for its connection to the high-potential pin (10) of the EUR (222), a controlled current generator (212), which contains a second operational amplifier (302), a third operational amplifier (303), a first transistor (311), the second transistor (312), the first resistor (Rcg1), the second resistor (Rcg2) and the third resistor (Rcg3), the control input (24) of the controlled current generator (212) is intended for connecting it to the second (2) output of the IC and to the non-inverting input a second operational amplifier (302), the inverting input of which is connected to the connection point of the first transistor (311) and a first resistor (Rcg1) connected in series with it, and the output of the second operational amplifier (302) is connected to the gate of the first transistor (311), output (26 ) of the controlled current generator (212) is designed to connect it to the first (1) pin of the IC, to the inverting input of the first operational amplifier (208) and to the second transistor (312), the gate of which is connected to the output of the third operational amplifier (303), non-inverting input said third operational amplifier (303) is connected to the connection point of the first transistor (311) and the second resistor (Rcg2) connected in series therewith, and the inverting input of the said third operational amplifier (303) is connected to the connection point of the said second transistor (312) and the series-connected with it a third resistor (Rcg3), and: the output of the first operational amplifier (208) is connected to the third (3) terminal of the IC, the first terminal of the reference resistor (Rref) is connected to the non-inverting input of the first operational amplifier (208), and the second terminal of the reference resistor ( Rref) is connected to the fifth (5) pin of the IC, the first pin of the bias resistor (Rbias) is connected to the sixth (6) pin of the IC, and the second pin is connected to the non-inverting input of the first operational amplifier (208), with the fourth (4) and fifth ( 5) the IC pins are connected to each other. 7. Integrated circuit of the EUR control device, containing the first terminal (1) of the IC, intended for connecting the first terminal of the external control variable resistor (Rc), the second terminal (2) of the IC, intended for receiving a feedback signal from the connection point of the external measuring resistor (Rsense ) with an external active element (224), the third pin (3) of the IC, intended for connecting the control pin of the external active element (224), the fourth pin (4) of the IC, intended for connecting the second pin of the external control variable resistor (Rc), fifth pin (5) IC intended for its connection to the low-potential terminal (12) of the ESD (222), the sixth terminal (6) of the IC intended for connection to the high-potential terminal (10) of the ESD (222), additional terminal of the IC intended for connecting an external a voltage divider consisting of a bias resistor (Rbias) and a reference resistor (Rref) connected in series, connected between the high-potential (10) and low-potential (12) terminals of the power steering unit (222), as well as the first operational amplifier (208) and a controlled current generator (212 ) containing a second operational amplifier (302), a third operational amplifier (303), a first transistor (311), a second transistor (312), a first resistor (Rcg1), a second resistor (Rcg2) and a third resistor (Rcg3), a control input ( 24) of the controlled current generator (212) is designed to connect it to the second (2) output of the IC and to the non-inverting input of the second operational amplifier (302), the inverting input of which is connected to the connection point of the first transistor (311) and the first resistor ( Rcg1), and the output of the second operational amplifier (302) is connected to the gate of the first transistor (311), the output (26) of the controlled current generator (212) is intended for connection to the first (1) pin of the IC, to the inverting input of the first operational amplifier (208 ) and to a second transistor (312), the gate of which is connected to the output of the third operational amplifier (303), the non-inverting input of the said third operational amplifier (303) is connected to the connection point of the first transistor (311) and a second resistor (Rcg2) connected in series with it, and the inverting input of the said third operational amplifier (303) is connected to the connection point of the said second transistor (312) and a third resistor (Rcg3) connected in series with it, the non-inverting input of the first operational amplifier (208) being intended for its connection to an additional pin of the IC, output the first operational amplifier (208) is connected to the third terminal (3) of the IC, while the fourth (4) and fifth (5) terminals of the IC are interconnected inside the IC.