The resonant power amplifier power frequency - it is a static electromagnetic device designed to enhance the capacity of power frequency of 50 Hz.
Resonance ( from Lat. Resono - heard in response that match), a relatively large (selective) response of the oscillating system (oscillator) on periodicity. effects with a frequency close to the frequency of its Property. oscillations. When R. is a sharp increase in the amplitude of the forced vibration of the oscillator.
Resonance plays a very important role in a variety of events, and in some useful, others harmful.
In 1906 in St. Petersburg struck Egyptian Bridge over the Fontanka River.
The reason - the resonance phenomenon caused by the passage over the bridge cavalry squadron. Step horses trained to march past, was in response to the period of the bridge. Such examples from the history of art are many. Responses in these cases, harmful phenomenon and to remove its special measures (detuning periods, increased attenuation - damping, and others.).
The radio resonance is mainly used as a useful phenomenon.
The phenomenon of electrical resonance allows you to configure transmitters and receivers at a predetermined frequency and to ensure their work without interference. In general, the use of resonance phenomena in electric radio incalculable. However, the conservation laws impose restrictions on the use of resonance to produce free energy, while supporters of getting it established stable stereotypes of parametric resonance amplification. So do not yet use the resonance phenomenon implemented.
Currently, a lot of broken copies when considering the theme "Resonance Melnichenko." There is even a category of people who declare him a charlatan.
Melnichenko hides the secret of their inventions, despite patents. But the secret of Melnichenko - is "an open secret".
Let's try to prove it. Take the well-known book "The elementary physics textbook ed. Acad. GS Lansberg Volume III Oscillations, waves. Optics. The structure of the atom. - M .: 1975. 640 p. with illustrations. "will open its pages 81 and 82 for a description of the experimental setup for the resonance frequency in the current City
In the above examples clearly show how it is possible to get the inductance and capacitance voltage is ten times greater than the supply voltage. If no special measures are taken, the power of resonance can destroy elements of the installation.
In this resonance amplifier power frequency electric resonance phenomenon is used in the series resonant circuit. The effect of the power amplifying AC series resonant circuit is achieved in that the input impedance at series resonance circuit is purely resistive, and the voltage on the reactive elements of the circuit input voltage exceeds an amount equal to Q of the circuit. To maintain continuous wave serial resonant circuit is only required to compensate for the heat loss in the active resistance of the circuit inductance and the internal resistance of the input voltage source.
Fig. 1.The block diagram and the composition of the resonance amplifier
The inductance of the resonant circuit is designed as a series-connected and coordinated primary winding of the power transformer windings and two controlled magnetic reactors. As the capacitance of the resonant circuit to be applied with a non-polar capacitor operating voltage is not less than twice the voltage at resonance. Control winding magnetic reactors include counter to the emf induced in them, were directed toward each other and are mutually compensated. It is important that the magnetic characteristics of the reactors were identical. Magnetic reactors are included in the resonant circuit of the amplifier to compensate for the detuning serial circuit when the load changes.
Vector idling current I0 is represented as a geometric sum of two components Ih, characterizes eddy current loss and Iμ, characterizing hysteresis loss. At idle, the transformer operates as a conventional inductance losses.
Fig. 2 the equivalent circuit of the transformer idling
Fig. 3 the equivalent circuit of the transformer under load
In the analysis of the equivalent circuit of the transformer under load it is seen that in series with the input impedance of the primary winding includes two parallel branches, one of which contains a resistance Z0, while the other two series-connected impedance Z'2 and Z'n.
The equivalent impedance Z'n can be written as
Z'э = Z'1 + Z'0 (Z'2 Z'н +) / (+ Z'0 Z'2 + Z'н).
From the equivalent circuit shows that the linking of complex resistance and Z'2 Z'n, (in the geometric sense) have a negative value, and depending on the nature of the total load impedance can be either capacitive or inductive.
The resonant amplifier power frequency transformer loaded introduces mismatch in the serial oscillating circuit and reduce its quality factor.
In transgenerator, for example, the mismatch due to the load is easily compensated by the change in feed rate. The resonant amplifier this is not possible because mains frequency is set, so it detuning compensation is carried out by introducing feedback via controlled magnetic reactors. The feedback loop is performed analysis and the geometric components of the summation current of the secondary winding and the load, the formation and regulation of the control current.
The structure of the feedback circuit includes: a part of the secondary winding of the power transformer, current transformer, rectifier and resistor setting the operating point of the magnetic reactors.
Fig. 4 the equivalent circuit of the resonant power amplifier power frequency under load
Two magnetic coils combined reactor control - a well-known and widely used magnetic amplifier (magnetic amplifier in this design does not increase, and works as a controlled inductance and introduces additional losses on the heating resistances of its windings). Depending on the operating conditions and the nature of the load it is possible to set various modes of payment by the introduction of additional windings internal feedback and bias.
The gain of the resonance amplifier power frequency is strongly dependent on the load, but a well-designed power efficiency is always significantly greater than unity.
The mathematical apparatus for the design of the resonance frequency of the power amplifier industry has long developed and maintained in the course of electrical engineering, as well as a large number of manuals and guidelines for the design of transformers and magnetic amplifiers. The algorithm for calculating constructed from the analysis of structural scheme and does not cause difficulties, it is only important to properly assess the operation of the nature of the load.
As the lack of considered design mentioned the increase of size and weight. Some of the advantages include the possible lack of active elements in the circuit, significantly increases the reliability of the design.
To work at constant load can be applied simplified diagrams of resonance amplifiers. The block diagram of a simplified resonant power amplifier power frequency is shown in Fig. 5.
Fig. 5 the block diagram of a simplified resonant power amplifier power frequency
The simplest resonance amplifier consists of only four elements.
Assigning the same elements as in the previously considered amplifier. The only difference is that in the simplest resonant amplifier manual adjustment is made in response to a particular load.
Calculate the simplest amplifier can be simplified to the following algorithm:
1. Turn on the power transformer in the network, and measure at a given load current consumed by them.
2. Measure the resistance of the primary winding of the power transformer.
3. Calculate the impedance transformer under load.
4. Calculate the inductive reactance of the transformer under load.
5. Select the value of the controlled magnetic inductive reactance reactor equal to about 20% of the inductive reactance of the power transformer.
6. Produce an adjustable magnetic reactor with branches starting from the middle to the end of the winding (the most objections are made, the more accurate will be the setting in resonance).
7. According to the condition of equality of the inductive and capacitive reactance at resonance to calculate the capacitance value to be included in series with the transformer and adjustable magnetic reactor for a series resonant circuit.
8. From the resonance condition, multiply the measured consumed current transformer loaded to the amount of the active resistance of the primary winding and the reactor and to obtain the approximate value of the voltage, which must be submitted to the serial circuit.
9. Take the transformer for output, according to claim 8 found the measured voltage and current consumption of claim 1 (the period setting of the amplifier is more convenient to use LATR [laboratory autotransformer]).
10. Is powered from the network via a transformer according to claim 9 input resonant circuit - (series connected capacitor, the primary winding of the loaded power transformers and reactors).
11. By changing the inductance of the reactor by switching the taps to set up the primary circuit to resonate at a reduced input voltage (for fine-tuning is possible in small change within the capacity of the capacitor connected in parallel with the main capacitors of small capacity).
12. By changing the input voltage to set the voltage on the primary winding of the power transformer 220 V.
13. Turn off and turn on the stationary LATR down transformer with the same strain.
Widespread use of resonance amplifiers power frequency can significantly reduce the load on the distribution networks and reduce the capital cost of the introduction of new electrical capacity.
Application of resonance amplifiers power frequency - stationary and marine electrical systems. For mobile facilities transgenerator advisable to use at high frequencies, followed by converting AC to DC.
When the coincidence of the frequency amplitude becomes largest is obtained an electrical resonance: the current in the circuit and voltage its capacitor can greatly exceed those obtained by detuning, t. E. Away from the resonance. Resonance phenomena pronounced the stronger and sharper than the lower resistance path, which thus here plays the same role as friction in the mechanical system.
All these phenomena are easy to observe, was used to produce a harmonic e. d. s. Urban AC and constructing an oscillating circuit whose natural frequency can be changed in both sides of the current frequency (50 Hz). To avoid in this high resonance voltage in the circuit, which (at a voltage in the urban network in the 110 or 220 V) can achieve more kilovolts, we will use step-down transformer.
Fig. 53 shows the location of devices and circuitry of experience (refer to the figure on the same scheme). Here, T - down transformer, C - a capacitor, L 1 and L 2 - chokes (self-induction coil with an iron core) which are necessary to obtain the desired high inductance. Inductance is composed of two separate coils for ease of circuit configuration. The adjustment is made so that one of the throttles (U) the core has an air gap, the width of which can be continuously changed in the range of 2-4 mm, thereby changing the magnitude of the total inductance. The wider the gap, the smaller the inductance. In the caption to Fig. 53 provides an example of the values of all variables. The voltage on the capacitor is measured by a voltmeter AC V, and AC ammeter Andallows you to monitor the current in the circuit.
Experience shows the following: for low inductance circuit voltage across the capacitor is a little more than e induced in the circuit emf, t. e. several volt. Increasing the inductance, we can see that the voltage increases; this growth is becoming more and more dramatic as it approaches the resonant inductor value. In the numerical data, which are indicated by Fig. 53, the voltage rises above 60 in. With a further increase in inductance voltage falls again. The current in the circuit varies in proportion to the voltage across the capacitor at the resonance and can reach up to 20 mA.
Fig. 53. Getting the electric resonance frequency of the City current.
T - a step-down transformer, for example from 6 to 120 In, C - capacitor with a capacitance of 1.2 microfarads; L 1 - Choke inductance 7,5 H (coil resistance of about 80 ohms): L 2 - the same reactor, but with variable air gap in the core. The total inductance of the circuit with a certain average width of the gap (2-3 mm) should be 8.3 H, and the change of the gap should be changed induktivnost 15-20% on either side of the said (resonance) meaning: V - voltmeter (120 V) and A - an ammeter (30 mA) AC.
This experience corresponds to the mechanical experience with load on the spring, which was described in § 12. There we were more convenient to change the frequency of the applied force, but here we are passing through the resonance setting, changing the natural frequency of the oscillating system - our circuit. The essence of the resonance phenomenon does not change.