Power factor corrector with DC output voltage stabilization

Abstract

A power factor corrector contains a power control switch (3) consisting of anti-series connected field-effect transistors, the control electrodes of which are joined into a common point connected to a control circuit (15), and a power transformer (2), a primary winding (1) of which is connected via the power control switch (3) to a source of AC voltage. Connected in parallel to the power control switch (3) is a winding (4) which is in antiphase to winding (1) and has a capacitor (5). Opposite-phase secondary windings (6) and (7) of the transformer (2) are connected in series via a capacitor (8). The start of winding (6) is connected to the cathode of a diode (9), the anode of which is coupled to the end of winding (7). The start of winding (7) is connected to the anode of a diode (10), the cathode of which is coupled to the end of winding (6). A common connection point of the start of winding (6) and the cathode of diode (9) is connected to a first pole of a step-down controller (11), and a common connection point of the start of winding (7) and the anode of diode (10) is connected to a second pole of the step-down controller (11). The technical result consists in the possibility of generating a continuous current that is in phase with an AC input voltage, and also generating and stabilizing a DC output voltage.

Description

[0001] POWER FACTOR CORRECTOR WITH CONSTANT STABILIZATION

[0002] OUTPUT VOLTAGE

[0003] 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.

[0004] Converters of alternating voltage to direct voltage with connection of the load through rectifier diodes and a smoothing capacitive filter are known [1].

[0005] 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.

[0006] 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].

[0007] 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.

[0008] 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 purpose is achieved by the fact that in a magnetically coupled power factor corrector with stabilization of a constant output voltage, a second magnetically coupled winding is introduced, which is antiphase to the first winding and is connected in parallel to the antiphase controlled keys via a series-connected capacitor, and two antiphase secondary windings are connected in series via a capacitor, and are connected to the input terminals of a voltage regulator with continuous consumption and transmission of energy to the load via diodes connected to them, the control of which is carried out by a feedback circuit implemented as a pulse-width controller.

[0009] Fig. 1 and 2 show the basic electrical circuit diagrams of embodiments of the proposed magnetically coupled power factor corrector with a passive clamping element and stabilization of the constant output voltage. Fig. 1 shows the basic electrical circuit diagram of the magnetically coupled power factor corrector with a passive clamping element and stabilization of the constant output voltage; Fig. 2 shows the basic electrical circuit diagram of the magnetically coupled power factor corrector with a passive clamping element and stabilization of the constant output voltage with the introduction of an additional linear inductance in series with the primary winding of the transformer.

[0010] 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. Parallel to the counter-series switch 3, the second magnetically coupled winding 4 is connected in series with the capacitor 5, antiphase to the first winding. Two secondary windings 6 and 7 of transformer 2, connected in antiphase, are connected in series through capacitor 8 so that the beginning of winding 6 is connected to the cathode of diode 9, the anode of which is connected to the end of winding 7, and the beginning of winding 7 is connected to the anode of diode 10, the cathode of which is connected to the end of winding 6. The common connection point of the beginning of winding 6 and cathode 9 is connected to the first pole of step-down regulator 11, and the common connection point of the beginning of winding 7 and the anode of diode 10 is connected to the second pole of step-down regulator U.A control controller 12 of the pulse-width type is connected to the output terminals of the step-down regulator 11, which controls the control transistor of the step-down regulator 11. 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. A linear inductance 14 is connected in parallel to the additional winding 13 of the transformer 2.

[0011] In Fig. 2, a linear inductance 16 is connected in series with the primary winding 1 of the transformer 2.

[0012] The operating principle of the proposed magnetically coupled power factor corrector with a passive clamping element and stabilization of the constant output voltage will be considered based on the assumption of ideal key elements, steady-state operation, and continuous change in the magnetic flux in the core of transformer 2. We will designate as D the duration of the on state of key 3 relative to the period T.

[0013] Let us assume that at the moment of considering the operation of a magnetically coupled power factor corrector with a passive clamping element and stabilization of the constant output voltage, a positive half-wave of sinusoidal voltage comes from an alternating 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 accumulated in the magnetization inductance of transformer 2 due to the primary windings 1,4.

[0014] After switching off switch 3, over the time interval (lD)T, a polarity reversal of the voltages on the transformer windings occurs, diode 9 is switched on, and the accumulated energy in the magnetization inductance is output through the secondary winding 6 of transformer 2 to the series-connected capacitor 8.

[0015] When the polarity of the input voltage source changes, all the processes described above are repeated with the only difference that now, during the time interval (lD)T, diode 10 is turned on and the accumulated energy in the magnetization inductance is output through the secondary winding 7 of transformer 2 into the series-connected capacitor 8.

[0016] The circuit on the secondary side of transformer 2, composed of antiphase secondary windings 6,7 connected in series through capacitor 8 and diodes 9,10, forms a passive clamping element that ensures the fixation of voltages on the windings of transformer 2 during the time interval (lD)T of the off state of regulating switch 3.

[0017] 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 £ Э FF1 = FOR winding 4 by expression ^ЭФФ2 = ^22(1— k 2 ) / (l — kn). In these expressions, Ln = L^i + Lsi is the magnetizing inductance of transformer 2 along winding 1 taking into account the leakage inductance, and L22 = Ц12 +Ls2 is the magnetizing inductance of transformer 2 along winding 1 taking into account the leakage inductance, where j LulLu2 . < - . л k = / - - the coupling coefficient between windings 1 and 4 is always less than or

[0018] *\ / LH / 22

[0019] L22 is equal to one, and n = I is the transformation ratio between the windings.

[0020] Al 1

[0021] 1 and 4. In our case, the value of EFF1 is important, which is equal to infinity at k=n, thereby eliminating the pulsations of the continuous and in-phase current with the input alternating voltage. With an equal number of turns of the windings of 1.4, the desired value of £EFF / is achieved by connecting a small inductance 16 in series with winding 1.

[0022] The introduction of an additional winding 13 of the transformer 2 with a parallel-connected linear inductance 14 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.

[0023] 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.

[0024] Maintaining a constant output voltage in the load is carried out using a step-down regulator 11 [2], the distinctive feature of which is the continuous consumption and transfer of energy to the load, and this property is an analogue of a resistive load. Feedback, implemented in the form of a pulse-width controller 12, affects the regulating transistor of the voltage regulator 11, ensuring the maintenance of a constant output voltage with a given accuracy.

[0025] Thus, the proposed magnetically coupled power factor corrector with a passive clamping element and 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.

[0026] 1. Patent for invention of the Russian Federation No. 2802914 with priority from 02.02.2023

[0027] 2. USSR Author's Certificate No. 1598073 “Pulse DC Voltage Regulator” A.G. Polikarpov, E.F. Sergienko with priority from 05.12.1988

Claims

Invention formula 1. A magnetically coupled power factor corrector with a passive clamping element and stabilization of a constant output voltage, comprising an electromagnetic element having a primary winding connected through an anti-series switch made on MOSFET field-effect transistors to the output terminals of an alternating 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 of the transformer is introduced, antiphase to the first primary winding of the transformer, and with a series-connected capacitor is connected in parallel to the anti-series switch made on MOSFET field-effect transistors, and the passive clamping element is made in the form of two secondary windings of the transformer, connected antiphase and in series through the second capacitor,in which the beginning of the first secondary winding of the transformer is connected to the cathode of a diode, the anode of which is connected to the end of the second secondary winding of the transformer, and the beginning of the second secondary winding of the transformer is connected to the anode of another diode, the cathode of which is connected to the end of the first secondary winding of the transformer, while a step-down regulator is introduced, the input terminals of which are connected to the beginnings of the secondary windings of the transformer, and the output terminals are connected to the terminals of the filter capacitors.

2. A magnetically coupled power factor corrector with a passive clamping element and stabilization of the 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. Magnetically coupled power factor corrector with passive clamping element and constant output stabilization voltage according to paragraph 1, characterized in that the step-down regulator is designed with continuous consumption and transmission of energy to the load and is covered by feedback from the controller with pulse-width regulation.

4. A magnetically coupled power factor corrector with a passive clamping element and stabilization of a constant output voltage according to paragraph 1, characterized in that the counter-sequential keys are controlled by a constant-duration controller.

5. A magnetically coupled power factor corrector with a passive clamping element and stabilization of the constant output voltage according to paragraph 1, characterized in that an additional transformer winding is introduced, in parallel to which a linear inductance is connected.

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