Magnetically-coupled power factor corrector with DC output voltage stabilization

Abstract

The claimed device relates to electrical engineering. A magnetically-coupled corrector contains a power control switch in the form of anti-series connected field-effect transistors, the control electrodes of which are connected to a control circuit, and a power transformer, a primary winding of which is connected via the control switch to a source of AC voltage. Connected in parallel to the control switch is a magnetically-coupled winding which is in antiphase to the primary winding and has a series-connected capacitor. Connected in parallel to said magnetically-coupled winding is a clamping element comprising a series-connected capacitor and anti-series connected field-effect transistors, the control electrodes of which are connected to a control circuit. Two secondary windings of the transformer are joined into a common point by the start of one winding and the end of the other. The respective end and start of the windings are connected to diode cathodes and the diode anodes are joined. The common point of the windings is connected to a first pole of an L-type LC filter, and the common point of the anodes is connected to a second pole of the L-type LC filter. The technical result is the generation of a continuous current that is in phase with an AC input voltage, and also the generation and stabilization of a DC output voltage.

Description

[0001] Magnetically coupled power factor corrector with constant output voltage stabilization

[0002] The invention relates to electrical engineering, in particular to converters of alternating voltage into direct voltage, and can be used in secondary power supply systems for power factor correction, conversion, regulation and stabilization of direct output voltage.

[0003] Converters of alternating voltage to direct voltage with connection of the load through rectifier diodes and a smoothing capacitive filter are known [1].

[0004] The disadvantage of known AC to DC converters is the lack of formation of continuous and in-phase current consumed from the input sinusoidal voltage, as well as stabilization of the constant output voltage.

[0005] The closest in technical essence to the proposed device is a converter of alternating sinusoidal voltage into direct output voltage, containing a primary winding of a transformer connected through counter-series controlled keys to the terminals of a source of alternating sinusoidal voltage, a secondary winding of a transformer connected through rectifier diodes to a capacitive filter and a load [1].

[0006] The disadvantages of this voltage converter are that it lacks power factor correction, continuous and in-phase current generation for the AC input voltage, and DC output voltage stabilization.

[0007] The purpose of the invention is to form a continuous and in-phase current to an alternating input voltage, to form a constant output voltage and to stabilize it.The stated objective is achieved by the fact that in a magnetically coupled power factor corrector with stabilization of constant output voltage, a second magnetically coupled winding is introduced, which is antiphase to the first winding, which is connected in parallel to the counter-series controlled keys via a series-connected capacitor, and a clamping element, composed of counter-series controlled keys and a capacitor, is connected in parallel to the second winding, two secondary windings are introduced, which are connected to an L-shaped LC filter via rectifier diodes, with which a step-down voltage regulator with continuous consumption and transmission of energy to the load is connected in series, the control of which is carried out by a feedback circuit implemented in the form of a pulse-width controller.

[0008] Fig. 1, 2 and 3 show the basic electrical circuit diagrams of embodiments of the proposed magnetically coupled power factor corrector with stabilization of constant output voltage. Fig. 1 shows the basic electrical circuit diagram of the magnetically coupled power factor corrector with stabilization of constant output voltage; Fig. 2 shows the basic electrical circuit diagram of the magnetically coupled power factor corrector with stabilization of constant output voltage with the introduction of an additional linear inductance in series with the primary winding of the transformer; Fig. 3 shows the basic electrical circuit diagram of the magnetically coupled power factor corrector with stabilization of constant output voltage with the connection of a damping element composed of counter-series controlled keys with a capacitor connected in series to the auxiliary winding of the transformer. In it (Fig.1) the beginning of the primary winding 1 of the transformer 2 is connected to the first pole of the input source of alternating voltage, and the end of the primary winding 1 is connected to the second pole of the input source of alternating voltage through a controlled counter-series switch 3. A second magnetically coupled winding 4, antiphase to the first winding, is connected in parallel with the counter-series switch 3. A counter-series controlled switch 7 with a series-connected capacitor 6 is connected in parallel to the second antiphase winding 4. Two secondary windings 8 and 9 of the transformer 2 are united into a common connection point by the beginning of winding 8 and the end of winding 9, the end of winding 8 is connected to the cathode of diode 10, and the beginning of winding 9 is connected to the cathode of diode 11, the anodes of which are united into a common connection point.The common connection point of windings 8,9 is connected to the first pole of the L-shaped LC filter 12, and the common connection point of anodes 10,11 is connected to the second pole of the L-shaped LC filter. A step-down regulator 13 is connected in parallel to the output terminals of the L-shaped LC filter 12, the output terminals of which are connected to a pulse-width type control controller 14, which controls the regulating transistor of the step-down regulator 13. The control electrodes of the counter-series switch 3 are combined into a common connection point and connected to the controller 15, the second terminal of which is connected to the common connection point of the counter-series switches of the transistors of switch 3. The control electrodes of the counter-series transistors of the clamping element 7 are combined into a common connection point and connected to the controller 16, the second terminal of which is connected to the common connection point of the counter-series transistors of the dumping switch 7.A linear inductance 18 is connected in parallel to the additional winding 17 of the transformer 2.

[0009] In Fig. 2, a linear inductance 19 is connected in series with the primary winding 1 of the transformer 2. We will consider the operating principle of the proposed magnetically coupled power factor corrector with stabilization of the constant output voltage based on the assumption of ideal key elements, steady-state operation, and continuous change of magnetic flux in the core of the transformer 2. We will designate as D the duration of the on state of the switch 3 relative to the period T.

[0010] Let us assume that at the moment of considering the operation of the AC-to-DC converter, a positive half-wave of sinusoidal voltage comes from the AC voltage source. In this case, at the stage of the closed state of DT switch 3, the field-effect transistor (MOSFET) of switch 3 operates in the normal key mode (in this case, the upper one), and the second (lower one) in the synchronous rectifier mode. During this time interval, energy is transferred to the load through the forward-biased rectifier diode 10 and the secondary winding 8.

[0011] After the switch 3 is turned off, the counter-series controlled switch of the clamping element 7 is turned on over the time interval (lD)T with the capacitor 6 turned on in series, which leads to a reversal of the voltages on the windings of the transformer 2, turning off the diode 10 and turning on the diode 11, and transferring energy to the load through the winding 9 and the diode 11. The voltage on the capacitor 6 changes according to the law VD / (1-D), and the energy enters the secondary circuit from the magnetizing inductance of the transformer 2.

[0012] When the polarity of the input voltage source changes, all the processes described above are repeated with the only difference that now, in the time interval DT, energy is transferred to the secondary circuit through winding 9 and forward-biased diode 11, and in the interval (1-D)T through winding 8 and diode 10.

[0013] The use of a magnetically coupled circuit, caused by windings 1, 4, allows to significantly increase the differential inductance of the windings (for current pulsations), which is described for winding 1 by the expression and for winding 4 by expression In these expressions magnetizing inductance of transformer 2 along winding 1 taking into account leakage inductance, a L - magnetization inductance of transformer 2 along winding 1 taking into account leakage inductance, where

[0014] - the coupling coefficient between windings 1 and 4 is always less than or is equal to one, and is the transformation ratio between the windings

[0015] 1 and 4. In our case, the important value is which for k=n is equal to infinity and thus eliminates the pulsations of the continuous and in-phase current with the input alternating voltage. With the equality of the number of turns of the windings 1.4, the desired value is achieved by including a small inductance 19 in series with winding 1.

[0016] The introduction of an additional winding 17 of the transformer 2 with a parallel-connected linear inductance 18 makes it possible to weaken the rigid connection between the value of the magnetization inductance of the transformer 2 and the number of turns of the primary winding 1, the geometric size of the magnetic circuit and the transformer gap, which expands the range of changes in the input voltage.

[0017] The values ​​of the time intervals DT and (lD)T are set fixed and do not change during the operation of the magnetically coupled power factor corrector with stabilization of the constant output voltage, thereby fixing the maximum power transmitted to the load.

[0018] Maintaining a constant output voltage in the load is carried out using a step-down regulator 13 [2], the distinctive feature of which is the continuous consumption and transfer of energy to the load, and by this property it is an analogue of a resistive load. Feedback, implemented in the form of a pulse-width controller 14, acts on the regulating transistor of the regulator 13, ensuring the maintenance of a constant output voltage with a given accuracy.

[0019] The clamping element, composed of the counter-series connection of field-effect transistors (MOSFET) of switch 7 and the series-connected capacitor 6, can be connected in parallel to any transformer winding, including the additionally introduced winding of transformer 2, for example, winding 17. In this case, low-voltage transistors of switches 7 can be used, and their control can be carried out relative to the common bus, input or output circuit.

[0020] Thus, the proposed magnetically coupled power factor corrector with stabilization of constant output voltage allows, in comparison with the known device, to implement the formation of a continuous, practically smooth current in phase with the alternating input voltage, the formation of a constant output voltage and its stabilization.

[0021] 1. Patent for invention of the Russian Federation No. 2802914 with priority from 02.02.2023

[0022] 2. USSR Author's Certificate No. 1598073 “Pulse DC voltage regulator” Polikarpov, E.F. Sergienko with priority from 05.12.1988

Claims

Invention formula 1. A magnetically coupled power factor corrector with DC output voltage stabilization, comprising an electromagnetic element having a primary winding connected via an anti-series switch made on MOSFET field-effect transistors to the output terminals of an AC voltage source, first and second rectifier diodes connected to the output terminals of the filter capacitors, and a control controller, characterized in that the electromagnetic element is made in the form of a transformer, in which a second primary winding is introduced, antiphase to the first primary winding, and with a series-connected capacitor is connected in parallel to the anti-series switch made on MOSFET field-effect transistors, two secondary windings of the transformer with anti-phase connection are combined into a common connection point, the opposite terminals of which are connected in series to the diodes, the anodes of which are connected into a second common connection point,and the common connection points are connected to the input terminals of the L-shaped LC filter, while a clamping element is introduced, connected in parallel to one of the transformer windings and composed of a second capacitor and a second counter-series switch connected in series, made on MOSFET field-effect transistors.

2. A magnetically coupled power factor corrector with stabilization of a constant output voltage according to paragraph 1, characterized in that a linear inductance is connected in series with the first primary winding of the transformer.

3. A magnetically coupled power factor corrector with stabilization of the constant output voltage according to item 1, characterized in that a step-down voltage regulator with continuous consumption and transfer of energy to the load.

4. A magnetically coupled power factor corrector with stabilization of a constant output voltage according to paragraph 3, characterized in that the step-down voltage regulator with continuous consumption and transfer of energy to the load is covered by feedback from a controller with pulse-width regulation.

5. A magnetically coupled power factor corrector with stabilization of a constant output voltage according to claim 1, characterized in that the counter-sequential keys of the damping element and the power regulating key are controlled by a constant-duration controller.

6. A magnetically coupled power factor corrector with stabilization of a constant output voltage according to paragraph 1, characterized in that a linear inductance is connected in parallel to the additional winding of the transformer.

7. A magnetically coupled power factor corrector with stabilization of a constant output voltage according to claim 6, characterized in that the clamping element, composed of a series-connected capacitor and an anti-series switch made on MOSFET field-effect transistors, is connected to an additional winding of the transformer, and the switches are controlled relative to the common bus of the input or output circuit.

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