Frequency doubler

FIELD: electric engineering, in particular, engineering of frequency transformers, in particular, engineering of transformer type multipliers, for example, doublers, possible use for powering high speed drives of wood-processing industry, reducer-less centrifuges, for induction heating of large metallic blocks and the like.

SUBSTANCE: frequency doubler contains transformer, on each rod of which four primary windings are positioned, combined in two pairs. Each pair of primary windings is closed on pair of synchronously enabled transistors, working in such a wag, that starting portion of powering voltage sinusoid is utilized. Common connection points of transistors of first and second pairs and windings of second pair are connected in accordance to direct series of phases alternation to input phase clamps. Common connection point of windings of first pair is connected to zero input clamp.

EFFECT: improved power coefficient due to use of starting portion of sinusoid of powering voltage in process of generation of EMF of doubled frequency in windings of transformer.

2 dwg

 

The invention relates to frequency converters, in particular to the multipliers transformer type, such as doublers, and can be used to power high-speed drives woodworking industry, gearless centrifuges, for induction heating of large metal blanks, etc.

Known frequency multiplier containing a three-phase transformer and controlled bridge rectifiers [1], however, this Converter has a large weight of active materials and low energy indicators.

Known three-phase frequency multiplier [2]in which to improve energy performance is used, the initial portion of the sine wave of the supply voltage, however, this device has a large weight and dimensions, contains advanced in its design the rectifier unit, thereby reducing the overall efficiency of the device as a whole.

The prototype of the proposed device is a three-phase frequency multiplier [3], which contains the transformer, thyristor and the phase-shifting unit, in which at each terminal of the transformer are four of the primary winding, incorporated in two pairs, each of which is closed by a pair according enabled thyristors.

The disadvantage of this device is the following.

The final part of the sine wave is tausaga voltage for forming the resultant EMF in the windings of the transformer affects the power factor of the device as a whole, because the focus of the current curve is shifted to decline relative to the center of gravity of the curve of the supply voltage and, as a result, have a low power factor of the frequency multiplier [4].

The purpose of this invention is to improve the power factor of the frequency doubler.

This goal is achieved by the fact that the core of the transformer 1 (Fig 1) are four of the primary winding 2-5, incorporated in two pairs, each of which is closed by a pair according to the enabled transistors 7-10, and the common connection point of the transistors of the first and second pairs of windings and the second pair is connected in accordance with a direct sequence of phases to the input phase terminals, and a common point of connection of the windings of the first pair is connected to the zero input terminal.

Comparative analysis of the prototype shows that the inventive device is characterized by the presence of new elements: power transistors operating in key mode.

Thus, the proposed device complies with the criteria of the invention of "novelty."

The comparison of the proposed solutions with other technical solutions shows that you know the use of power transistors as key elements [5].

However, the use of the power transistor in the key mode, connected in series with the primary winding and the transformer, allows the output winding of the transformer EMF double frequency, using the initial part of the sine wave of the supply voltage, causing the center of gravity of the curve of the current of the primary windings is shifted to advance towards the center of gravity of the curve of the supply voltage and as a result have a capacitive character cosϕ and the overall power factor of the device as a whole is increased [4]. This allows to conclude that the technical solutions according to the criterion of "significant differences".

Figure 1 shows a schematic diagram of one phase of the frequency multiplier. Figure 2. shows time diagrams of the voltage for a single phase transformer.

Frequency doubler (figure 1) consists of a core of the transformer 1 with a wound on his rod windings 2-5, the secondary winding 6, transistors 6-10 managed from the control system (not shown).

The principle of operation of the frequency multiplier explains chart the curves given in figure 2.

Consider the operation of the frequency doubler. The primary winding of the transformer (figure 1) are phase UANlinear and UBCvoltage shifted relative to each other at an angle π/2. The curves of changes of these stresses over time is shown in figure 2. At time t1turns on the transistor 7 and the coil 2 starts protect the current. At time t2the transistor 7 is turned off, and turns on the transistor 9, and the winding 4 starts to leak current. Since the polarity of the connection to the power source voltage winding 4 of opposite polarity connection to the power source voltage winding 2, the current and, accordingly, the induced voltage generated at the output winding 6 have opposite sign with respect to the current flowing through the coil 2. Accordingly, at time tCturns on the transistor 8 and the winding 3 starts to leak current, but since the polarity of this winding to the power source of the opposite polarity connection of the winding 2, in this case, the voltage induced in the output winding 6 has the opposite sign with respect to the supply voltage UANand at time t4transistor 8 turns off and turns on transistor 10. In the future, the process is repeated. As a result of this sequence of operation of the transistors in the output winding of the transformer is formed EMF double frequency compared to the frequency of the supply voltage.

Since the formation of the EMF in the windings of the transformer is used, the initial portion of the sine wave of the supply voltage, the center of gravity of the current curve is shifted to advance towards the center of gravity kryvospytska voltage and as a result, have a high power factor of the device as a whole [4].

Frequency doubler with three-phase output consists of three doublers with single-phase output, with the output winding of the doubler with three-phase output can be connected either in star or in Delta.

Experimental studies of the proposed frequency doubler showed that, compared with the device for a similar purpose (prototype) this device has the best performance power factor.

Sources of information

1. As the USSR №1104624, CL H 02 M 5/16, 1984.

2. As the USSR №1513587, CL H 02 M 5/16, 1989.

3. As the USSR №549868, CL H 02 M 5/16, 1977.

4. Supronowicz, Improving the power factor of the Converter units. TRANS. with Polish. - M.: Energoatomizdat, 1985. - P.60-71,

5. Patent RU NO. 2240595, N 02 N 5/27, 2004.

Frequency doubler that contains the transistors and the transformer, the terminals of which there are four primary and secondary winding, characterized in that at each terminal of the transformer are four of the primary winding, incorporated in two pairs, each of which is closed by a pair according to the enabled transistors operating in such a way that in use the initial part of the sine wave of the supply voltage, and a common connection point of the transistors of the first and second pairs of windings and the second pair is connected in the accordance with a direct sequence of phases to the input phase terminals, as a common point of connection of the windings of the first pair is connected to the zero input terminal.



 

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