RU2743509C1 - Method of fine tuning to resonance frequency of inductor of device for magnetic action on living organisms - Google Patents

Abstract

FIELD: medicine.SUBSTANCE: invention relates to medical equipment, to devices for magnetic action on living organisms, in which an inductor is included as a load of active oscillator. Accurate tuning to resonant frequency of inductor is carried out due to that in circuit of positive feedback on current of active oscillator there is a leading differentiating phase compensating circuit, which is made in form of in-series connected capacitor and resistor. At that, accurate adjustment is carried out by changing resistance of resistor, which can be a constant resistor, trimmer, a variable resistor, a set of discrete precision resistors switched by solid-state keys or relays, or a digital potentiometer with control from a microcontroller.EFFECT: method allows effective compensation of phase shift between voltage on inductor and current in inductor and providing accurate tuning to resonant frequency of inductor.5 cl, 5 dwg

Description

The invention relates to a device for magnetic effects on living organisms, in which the inductor is included as a load of an oscillator, which can be used in medicine and veterinary medicine to implement a magnetic physiotherapeutic or magnetostimulating effect on tissues and internal organs of a person or animal in order to eliminate pain syndromes, stimulate processes vital functions and regeneration, accelerating the restoration of human and animal tissues after invasive influences and injuries.

A device for magnetic effect on living organisms is known according to RF patent No. 2714433, containing a power source, an oscillator and an inductor connected to it, which is characterized in that the oscillator operates at the resonant frequency of the inductor, which is made in the form of a flat bifilar coil with open windings, connected to the oscillator as a load in the form of a serial oscillatory circuit, providing a sinusoidal shape of the output current at the resonant frequency of the coil, while the bifilar coil is made in the form of a flat disk, in which the wires of its windings are placed on a dielectric substrate in the form of two concentrically arranged spirals of two adjacent to each other wires of different windings, while the open terminal of one of the windings of the bifilar coil is located on the inner end of the coil in the radial direction of the coil, and the open terminal of the second of the windings of the inductor coil is located on outer in the radial direction of the coil end of the specified winding, and the opposite terminals of both windings of the coil are connected to the corresponding terminals of the oscillator.

The method of operation of this technical solution, as the closest to the declared technical essence and the achieved result, is adopted as its prototype. The known method provides for the formation by the inductor of a directed magnetic effect on the tissues and organs of a person with the formation of an inhomogeneous magnetic field of a conical shape with the provision of a maximum intensity of such an effect, i.e. the maximum of the induction of the magnetic field located at the apex of the specified cone. The design of the device in a compact ergonomic form increases the level of positive emotions of users during its use, promotes patient adherence to treatment, that is, compliance, which leads to higher rates of the effectiveness of the treatment process.

The disadvantage of this method is that the excitation of electrical oscillations that determine the magnetic field of the inductor does not occur exactly at the resonant frequency of the inductor. This is due to the inevitable time delays in the propagation of the signal on the components of the oscillator. In this case, electrical oscillations arise not at the resonant frequency of the inductor, but with a certain frequency shift. As a result, the energy advantages of the resonant method of generating oscillations are not fully exploited and such devices consume useless reactive energy. In addition, due to the appearance of a reverse channel for transferring reactive energy to the power source, the shape of the generated magnetic field changes.

The objective of the claimed invention is to provide accurate tuning to the resonant frequency of the inductor of the device for magnetic effects on living organisms, as well as automatic control of this tuning with a given accuracy.

The essence of the claimed technical solution is expressed in the following set of essential features sufficient to solve the technical problem indicated by the applicant and obtain the technical result provided by the invention.

According to the invention, the method of fine tuning to the resonant frequency of the inductor of a device for magnetic action on living organisms, which includes a power source, an oscillator with a load in the form of an inductor included in the positive feedback circuit of the current of the oscillator is characterized in that the positive feedback circuit In terms of the current of the oscillator, a leading differentiating phase-compensating circuit is included, which is performed in the form of a capacitor and a resistor connected in series, while the exact tuning to the resonant frequency of the inductor is carried out by changing the resistance of the resistor.

In addition, the claimed technical solution is characterized by a number of additional optional features, namely:

- the resistor is made in the form of a resistor of a preselected constant resistance;

- the resistor is made in the form of a manually controlled trimmer or variable resistance resistor;

- the resistor is made in the form of a set of discrete precision resistors switched by electronic keys;

- the resistor is made in the form of a digital potentiometer, the resistance of which is controlled via a digital bus by a microcontroller, to the input of which a phase mismatch signal is supplied from a phase detector, the inputs of which are connected to the outputs of comparators, to the inputs of which signals are supplied, respectively, of the voltage on the inductor and the current in the inductor.

The claimed set of essential features ensures the achievement of the technical result, which consists in the fact that in any embodiment of the resistor it is possible to fine-tune the device for magnetic action on living organisms at the resonant frequency of its inductor with the ability to control this setting with a given accuracy.

The essence of the invention is illustrated by drawings, where figure 1 shows a functional diagram of an oscillator with a load in the form of an inductor in the POST circuit, figure 2 is a graph of voltage and current signals in the inductor circuit at zero phase shift, figure 3 is a graph of voltage signals and the current in the inductor circuit at a non-zero phase shift, Fig. 4 is a functional diagram of an oscillator with a phase-compensating circuit, Fig. 5 is a functional diagram of an auto-oscillator with a phase-compensating circuit and automatic tuning to the resonant frequency of the inductor.

In the drawings, positions and letters indicate:

A1 - autogenerator unit;

DA1 - amplifier stage with feedback - OOSN and POST;

+ IN1, -IN1- direct and inverting inputs of the amplifier stage;

OUT - output of the autogenerator unit;

R1, R2 - resistors that determine the transmission coefficient of the oscillator

by voltage in the OOSN circuit;

R3 - resistor (current sensor) of the POST circuit (for Fig. 1);

R3 is a divider resistor in a phase-compensating circuit (for Fig. 4, Fig. 5);

R4 - resistor (current sensor) of the POST circuit;

RFC - phase-compensating circuit resistor;

SFC - phase-compensating circuit capacitor;

RФК1, RФК2 - phase-compensating circuit resistors narrowing the adjustment range;

RK1, RK2 - voltage divider resistors that equalize the slope of voltage and current signals at the comparator inputs;

PD - phase detector;

KOMP1, KOMP2 - comparators that convert voltage and current signals from sinusoidal to rectangular;

MK - microcontroller;

CPU - digital potentiometer;

I2C - digital potentiometer control bus;

L1 - inductor;

1-2, 3-4 - pins L1;

Δ t - time phase shift;

U is the voltage across the inductor;

I is the current in the inductor.

The claimed device operates as follows.

The oscillator A1 (Fig. 1), in the ideal case, automatically operates at the resonant frequency of the inductor L1. In this generalized circuit, resistors R1 and R2 provide negative voltage feedback (NFF) and determine the voltage gain of the oscillator. When power is supplied to the A1 node through the current sensor, resistor R3, it closes and is supported by POST. In this case, the classical conditions for the occurrence of self-oscillations are fulfilled - phase balance and amplitude balance. The voltage across the inductor and the current through it are in phase, i.e. the shift between them is 0 degrees (Fig. 2). As a result, the reactive components of the impedance of the inductor L1 are compensated, the impedance of the inductor L1 contains only the active component, the current through the inductor L1 and, accordingly, the magnetic field induction are maximum. The shape of the magnetic field has a pronounced maximum. The benefits of resonance are fully exploited.

However, in reality, the output voltage signal corresponding to the signal difference: OOSN at the input - IN A1 and DC at the input + IN A1, due to the propagation delay in A1, cannot instantly appear at the OUT A1 output. As a result, the voltage signal on the inductor lags behind the current signal in the inductor (Fig. 3). Those. a phase shift appears between them. This means the appearance of the reactive, in this case, the capacitive component of the inductor impedance L1 and the detuning from the resonant frequency of the inductor. This leads to the appearance of a reactive component of the current, uselessly consuming the energy of the power source and reducing the maximum current amplitude in the inductor L1 and, accordingly, the magnetic field induction.

For fine tuning, it is possible to connect in series with the A1 output of variable or discretely switched capacitors, which will reduce the capacitive component of the inductor L1 impedance.

However, this method of tuning is extremely inconvenient and imprecise, since these capacitors must:

- have a sufficiently large nominal capacity (0.01 ... 0.1 mkF);

- pass significant currents (up to 1A);

- have a minimum capacity error (less than 1%);

- have maximum smoothness or minimum discreteness of capacity change.

Simultaneous implementation of all these requirements is difficult due to the lack of an appropriate element base.

The claimed method of fine tuning control (STUN) consists in compensating the time delay Δt using a special phase-compensating circuit included in the DC circuit. The voltage signal at the output of this circuit leads the voltage signal at the input of this circuit. This circuit (figure 4) includes a series-connected resistor R3 and additional elements - RfK and SFC, i.e. is a differentiating chain.

Resistor R3 determines the input resistance of the POST circuit, and also forms a POST voltage divider with RfK and SFC elements, which determines the POST depth. The time constant of this differentiating circuit τ determines the lead time of the DC output signal.

τ = (R3 + RfK) × SFC.

By changing this time constant, it is possible to change the lead time of the POST output signal and, thus, to compensate for the phase shift, i.e. tune the auto-oscillator exactly to the resonant frequency of the inductor L1, achieving Δt = 0.

Such an adjustment can be made very accurately by changing the resistance of only one element - the resistor RfK, which can be a constant resistor, a trimming resistor, a variable resistor, a set of discrete precision resistors switched by solid-state keys or a relay, or a digital potentiometer controlled by a microcontroller (Fig. 4, Figure 5).

The most promising is the use of a digital potentiometer. In the case of using a set of discrete resistors or a digital potentiometer, it becomes possible to automatically tune the device to the resonant frequency of the inductor.

For this, a phase detector (PD) unit and a microcontroller (MC) are added to the oscillator circuit (Fig. 5).

This scheme works as follows.

Voltage and current signals are fed to the corresponding comparators KOMP1, KOMP2, which convert the sinusoidal signal into a rectangular one. A chain of resistors Rk1, Rk2 equalizes the slope of the voltage and current signals at the inputs of the comparators to maintain the accuracy of the PD operation.

The signal at the output of the PD is proportional to the phase difference of the voltage and current signals. This difference signal is fed to the MC, which, depending on the magnitude of the difference signal, forms a control code for a digital potentiometer (CPU) on the I2C bus (or other digital bus). The CPU permutes, changing the time constant of the DC circuit, until the phase shift becomes equal to zero, i.e. Δt = 0.

Thus, a closed automatic control loop is formed, which provides accurate tuning to the resonant frequency of the inductor. Resistor RFC1 is used to preset the expected phase-compensating delay.

Resistor Rfk2 narrows the adjustment range of Rfk1. Together RFC1 and RFC2 narrow the CPU adjustment range.

To test the possibility of implementing the invention in an auto-generator circuit according to patent No. 2714433, two prototypes of devices implementing the claimed STUN were made, based on a variable resistor and based on a CPU.

The inductor had the following parameters: inner diameter of the winding - 25 mm; outer diameter of the winding 126 mm; diameter of the winding wire 0.5 mm; number of double turns - 51; inductance of one winding (conclusions 1-

2 (3-4) L1, fig. 4, fig. 5) - 100 μH; the capacitance of the circuit (conclusions 1-4 L1, Fig. 4, Fig. 5) - 2300 pF.

With the used parameters of the inductor to ensure accurate adjustment, the elements of the phase-compensating and other circuits had the following values:

For the functional diagram of the oscillator with a phase-compensating circuit (figure 4): R3 - 10 Ohm -1% -0.1W; R4 - 1 Ohm -1% -0.25W; Sfk - 0.022mkF -5% - 16V; RFK -100 Ohm - 1% -0.25W (a phase shift of 0 degrees was provided at RFK = 24 Ohm).

For the functional diagram of the oscillator with a phase-compensating circuit and automatic tuning to the resonant frequency of the inductor (figure 5): R3 - 10 Ohm -1% -0.1W; R4 - 1 Ohm -1% -0.25W; Sfk - 0.022mkF -5% - 16V; RFC1 -100 Ohm - 1% -0.25W (a phase shift of 0 degrees was provided at RFC1 = 24 Ohm); Rfk2 - 33 Ohm-1% -0.1W; CPU - (AD8400ARZ1) - 1 kOhm; RK1 -12 kOhm - 1% -0.1W; RK2 -1 kOhm - 1% -0.1W.

The resonant frequency of the inductor, as a series oscillatory circuit, was determined by the well-known formula:

f = 1 / 2π √L × C, where

L - winding inductance between terminals 1-2 (3-4) L1,

C is the capacitance of the loop between terminals 1-4 L1.

Hence,

f = 1 / 2π √L × C = 1/2 × 3.14√100 × 10-6 × 2300 × 10-12 = 332 × 103Hz = 332kHz

The phase shift provided by the differentiating circuit was determined by the well-known formula:

Δϕ = π2-arctag2πƒτ

Δϕ (rad) = 3.142-arctan2 × 3.14 × 332 × 103 × (10 + 24) × 0.022 × 10-6 = 0.57 rad.

Accordingly, the initial (without STUN) phase shift in degrees was:

Δϕ (deg) = 3602π × Δϕ (rad) = 3602 × 3.14 × 0.57 = 330

Such a phase shift, compensated by the STUN, indicates the presence of a significant initial time shift between the voltage across the inductor and the current in the inductor and, as a consequence, the lack of precise tuning to the resonant frequency of the inductor without the STUN.

Thus, the claimed set of essential features ensures the achievement of the technical result, which consists in the fact that the proposed STUN in the POST of the oscillator can effectively compensate for the phase shift between the voltage on the inductor and the current in the inductor and provide accurate tuning to the resonant frequency of the inductor.

Claims (5)

1. A method of fine tuning to the resonant frequency of an inductor of a device for magnetic action on living organisms, which includes a power source, an oscillator with a load in the form of an inductor included in the positive feedback circuit of the current of the oscillator, characterized in that the positive feedback circuit In terms of the current of the oscillator, a leading differentiating phase-compensating circuit is included, which is performed in the form of a capacitor and a resistor connected in series, while the exact tuning to the resonant frequency of the inductor is carried out by changing the resistance of the resistor. 2. The method according to claim 1, characterized in that the resistor is in the form of a resistor of a predetermined constant resistance. 3. The method according to claim 1, characterized in that the resistor is made in the form of a manually controlled trimming or variable resistance resistor. 4. The method according to claim 1, characterized in that the resistor is made in the form of a set of discrete precision resistors switched by electronic keys. 5. The method according to claim 1, characterized in that the resistor is made in the form of a digital potentiometer, the resistance of which is controlled via a digital bus by a microcontroller, to the input of which a phase mismatch signal is supplied from a phase detector, the inputs of which are connected to the outputs of the comparators, to the inputs of which signals are supplied respectively, the voltage across the inductor and the current in the inductor.

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