RU194944U1 - KEY TWO-STAGE HARMONIC OSCILLATION GENERATOR - Google Patents

Abstract

The device relates to converting electronic equipment and can be used in various fields of science and technology to obtain harmonic oscillations. The push-pull key generator contains as a load a series resonant circuit consisting of two capacitors and one inductor (LCC circuit). The technical effect of the new utility model is to reduce the power consumption of the power source, expanding the frequency range of the generator without complicating the design of the installation.

Description

The device relates to converting electronic equipment and can be used in various fields of science and technology.

In physical studies, to obtain harmonic oscillations in an inductor, a linear single-cycle generator with external excitation is known that contains generator devices made on vacuum tubes and a parallel resonant circuit as a load (Installation for studying phase transitions. Stabilization systems. Preprint of the Institute of Physics and Technology named after A.F. Ioffe, N 398, Leningrad, 1972) [1]. A parallel resonant circuit consists of an inductor and a variable capacitor for tuning the resonant circuit to the frequency of the master oscillator. A parallel resonant circuit is connected on the one hand to the minus of the power source, and on the other hand to the generator device through a blocking capacitor and has a high quality factor. A power supply with an output voltage of 600 V is connected to the generator through a blocking inductor. For tuning the circuit to the frequency of the external master oscillator, a variable capacitor is used. A linear generator with a high-quality oscillatory circuit allows one to obtain harmonic oscillations in a wide frequency range, which is a necessary requirement for solving a number of physical problems.

A disadvantage of the known device is the inability to obtain the average rectified value of the output voltage, a larger voltage source. Therefore, in order to obtain a large amplitude of alternating current in a parallel resonant circuit, a powerful high-voltage power source and electron tubes are used. Such a generator circuit is unreliable and rather cumbersome, and high voltage creates additional problems from a safety point of view.

Known is a key push-pull generator for power sources of electrotechnological induction heating plants, containing generator devices to which a series resonant circuit consisting of a capacitor and an inductor is connected. The inductor is a small-coil coil with a low inductance and a low inductance. A disadvantage of the known device is the need to use a matching device between the inverter and the series resonant circuit, usually a transformer (Matching transistor frequency converters with induction heaters. S.V. Dzliev, A.A. Zavorotkin, Yu.Yu. Perevalov, K.E. Pishchalev // Journal - Induction Heating - 2012. - No. 3 (21) - pp. 33-40. ISSN: 2076-3840) [2].

The closest to the destination (prototype) is a key push-pull generator, which allows to obtain harmonic oscillations with a serial resonant circuit (Transistor harmonic oscillators in a key mode, edited by IA Popov, M., Radio and communication, 1985) [3] .

The key push-pull generator prototype includes a master oscillator, generator devices in the form of transistors (hereinafter referred to as generator devices) with a control circuit, a serial resonant LC circuit (hereinafter LC circuit). The input of the control circuit of the generating devices receives rectangular pulses from the master oscillator. The control circuit provides the formation of rectangular voltage pulses with a duty cycle of 2 at the output of the generating devices. Rectangular voltage pulses arrive at the input of the LC circuit with high quality factor (Q> 10) and are converted into

oscillatory circuit into harmonic oscillations. Such generators make it possible to obtain oscillations close to harmonic in the load in a wide frequency range without additional filters (Designing of radio transmitters. Edited by VV Shakhgildyan. M, Radio and communication, 2000) [4]. Unlike generators with a parallel resonant circuit, a generator with a serial resonant circuit uses a low-voltage power source.

The disadvantage of a key push-pull generator with a serial resonant circuit - the prototype is that all the resonant circuit current flows through the generator devices. Due to the finite resistance of the generating devices in the open state, part of the power supply power is dissipated. This leads to a limitation of vibrational power and a decrease in efficiency, limits the frequency range.

The technical effect of the new utility model is to reduce the power consumption of the power source, expanding the frequency range of the generator without complicating the design of the installation.

The technical result is achieved in that in a key push-pull generator of harmonic oscillations, containing a driving generator of rectangular pulses, generator devices in the form of transistors connected in a push-pull circuit with a control circuit, and the control circuit is configured to alternately turn on and off the generating instruments, which receives the input signal from the rectangular pulse generator, the resonant circuit, new is that the specified resonant circuit is sequential box from capacitor C1, inductors L connected in series, capacitor C2 connected in parallel to coil L, moreover, C1 is connected on one side to one output of the generator devices, and on the other hand to coil L and capacitor C2, and coil L and capacitor C2 on the other hand

connected to another output of the generating devices, and the resonant frequency

где C_res=С1+С2.determined by the formula

where C _res = C1 + C2.

In FIG. 1 shows a diagram of a device where:

1 - a rectangular pulse generator;

2 - generating devices, including a control circuit (not shown in Fig.);

3 - serial resonant LCC circuit (hereinafter - LCC circuit), consisting of an inductor L, capacitor C1, capacitor C2.

The key push-pull generator circuit (Fig. 1) works as follows. The control circuit of the generating devices 2 with a certain frequency receives the input signals from the generator of rectangular pulses 1. The control circuit provides alternately turning on and off the generating devices for half the period. Powerful rectangular voltage pulses are generated at the output of the generating devices. The resonant circuit filters out all harmonics except the frequency to which it is tuned. The number and magnitude of harmonics depends on the quality factor of the circuit.

Coil L, capacitors C1 and C2 form a series resonant LCC circuit.

The resonant frequency of the circuit is determined by the formula

где С_рез=С1+С2.

where C _rez = C1 + C2.

In resonance mode, there are two current circuits, serial and parallel.

Serial circuit: one output of the generating devices - capacitor C1 - inductor L - another output of the generating devices. Parallel circuit: capacitor C2 - inductor L.

Через катушку протекает суммарный ток конденсаторов, т.е.

Ток через катушку L в

раза больше, чем через генераторные приборы и конденсатор С1.The ratio of currents through capacitors C1 and C2 is proportional to capacitances, i.e.

The total current of the capacitors flows through the coil, i.e.

Current through coil L in

times more than through generating devices and capacitor C1.

In FIG. Figure 2 shows a graph of the dependence of the power consumption of a key push-pull generator with an LC circuit and an LCC circuit for various capacitor ratios C2 / C1, obtained from the simulation results. Simulation parameters: current in the coil I _Lm = 6A, coil inductance L = 6 μH, resonant capacitance of the capacitor C = C1 + C2 = 144 nF, simulation frequency P = 100 kHz.

In FIG. Figure 3 shows the experimental data on the cost of power supply to obtain the same current and field strengths in the coil in a key push-pull generator with an LCC circuit at different ratios of capacitors C2 / C1 without changing the value of the resonant capacitance C = C1 + C2. The power consumption of a generator power supply with an LC circuit was determined at C2 / C1 = 0.

The field was determined using a test coil and an oscilloscope. Inductance of the LCC coil circuit L = 6 μH. The resonant frequency is about 170 kHz. Using the switches, 12 capacitors of 11 nF each were switched to obtain different C2 / C1 ratios, the total capacitance C = C2 + C1 ≈ 140 nF. Coil current Im = 2.66A, field strength Hm = 15 Oersted.

Thus, both modeling and experimental research show the following:

1. At the same current in the coil, the power consumption of the power source in the generator with the LCC circuit is much less than in the generator with the LC circuit.

2. There is an optimal range of the C2 / C1 ratio, in which the power consumption of the power source is minimal. With a ratio of C2 / C1 in the range from 1.5 to 4, it takes half the cost of the power supply in a generator with an LCC circuit compared to an LC circuit.

3. The quality factor of the LCC circuit in the optimal range is 2-3 higher than the LC circuit.

Через катушку протекает суммарный ток последовательного С1 и параллельного С2 конденсаторов, т.е.

Ток через катушку L в

раза больше, чем ток через генераторные приборы и конденсатор С1. Таким образом, уменьшаются потери мощности источника питания на транзисторах.4. The ratio of currents through capacitors C1 and C2 is proportional to capacitances, ie

The total current of the series C1 and parallel C2 capacitors flows through the coil, i.e.

Current through coil L in

times more than the current through the generating devices and capacitor C1. Thus, the power loss of the power source on the transistors is reduced.

5. The input impedance of the LCC circuit grows with increasing ratio C2 / C1. By changing the ratio C2 / C1, it is possible to achieve optimal matching of the resonant circuit with generator devices and to expand the range of generator devices without using a matching transformer.

These properties allow you to expand the frequency range and reduce the cost of power supply without complicating the circuit of the generator.

The utility model, a key push-pull generator of harmonic oscillations, was directly created for installing the spin-echo of small-angle neutron scattering (SEMURN), in which the IXDD614CI chip was used as generator equipment. This so-called lower-shoulder driver, made in the TO-220-5 package, contains a push-pull output stage operating in key mode. The above properties of the serial resonant circuit and limiting driver parameters (supply voltage 35 V, continuous current 4 A, maximum current amplitude 14 A) allow us to obtain the necessary amplitude of the radio frequency current in the inductor for installing the SEMURN in a wide range from 30 kHz to 3 MHz without using matching transformer, additional filters and replaceable coils with switching only resonant circuit capacitors.

In FIG. 4 and FIG. Figure 5 shows the data on the cost of power supply and Q factor for a generator with LC and LCC circuit (coil with an inductance of 6 μH, the amplitude of the current in the coil is 2.7A). On such a large range with decreasing frequency, the wave resistance and quality factor of the LC circuit drops to units, and it is almost impossible to obtain harmonic oscillation without complicating the circuit or increasing the coil inductance. But in a generator with an LCC circuit at a frequency of 38 kHz, the Q factor is Q = 10, and the power supply costs in the lower part of the range are 2-3 times less.

In FIG. 6 and FIG. Figure 7 shows the oscillograms of the radio frequency magnetic field and the input voltage in the LCC and LC circuits taken with a test coil located in the center of the inductor L. The oscillograms clearly illustrate the improved filtering properties of the LCC circuit compared to the LC circuit, especially at low frequencies .

Thus, a simple, reliable, economical generator was created, which allows creating harmonic oscillations in an extended frequency range.

Claims (2)

A key push-pull generator of harmonic oscillations, containing a driving generator of rectangular pulses, generator devices in the form of transistors connected in a push-pull circuit with a control circuit, and the control circuit is configured to alternately turn on and off transistors, which receives an input signal from a square-wave generator, resonant circuit, characterized in that the resonant circuit is sequential and consists of a capacitor C1, an inductor L, connected series, capacitor C2 connected in parallel to the coil L, and capacitor C1 on the one hand connected to one output of the generator devices in the form of transistors, and on the other hand, to the coil L and capacitor C2, and the coil L and capacitor C2 on the other hand are connected to another output of the generating devices in the form of transistors, and the resonant frequency is determined by the formula

where C _res = C1 + C2.

Images