WO2022194037A1

WO2022194037A1 - Valley-filling and flicker-free pfc converter

Info

Publication number: WO2022194037A1
Application number: PCT/CN2022/080306
Authority: WO
Inventors: 严宗周
Original assignee: 深圳原能电器有限公司
Priority date: 2021-03-19
Filing date: 2022-03-11
Publication date: 2022-09-22
Also published as: CN112803752A; CN112803752B

Abstract

Provided is a valley-filling and flicker-free PFC converter, comprising: a PFC unit. The PFC unit is provided with an energy storage capacitor and at least one switch tube. The PFC unit is electrically connected in front of a fluctuation circuit or a converter, and is charged by means of a bus input end and/or a winding fly-back. By means of the cooperation of a PFC unit and other circuits and in conjunction with a corresponding control method, peak value energy is stored in the PFC unit at a certain moment, so as to increase a PF value, and the PFC unit performs valley-filling release according to requirements, so as to prevent output fluctuation. Internal switch tubes and/or diodes are used to control the PFC unit to perform energy storage and release, and when a PFC module is added between windings, an energy storage capacitor in the PFC unit can be controlled at a relatively low voltage, so as to reduce the withstand voltage of the PFC capacitor. A stable output with no flicker is realized, and the number of elements used internally is reduced, thereby reducing the overall volume of a converter, and prolonging the service life thereof.

Description

A valley-fill and flicker-free PFC converter

technical field

The invention relates to the field of converter equipment, in particular to a valley-filling and stroboscopic-free PFC converter.

Background technique

In order to provide stable energy output, existing converters usually filter after AC rectification, but when adding capacitors directly, the capacitor voltage drops with the AC input as the load increases, reducing the effect of capacitors; common valley filling circuits, Valley filling requires capacitors to be charged in series and discharged in parallel. The number of capacitors must be at least two or more, and the valley filling time cannot be selected by ordinary valley filling circuits.

Furthermore, in a single-stage PFC circuit, in order to increase the PF value, the current and voltage need to be in the same phase. Therefore, when the sine wave is in the trough of the prior art, the output power of the designed converter is low or even no output, resulting in the output with load. When the current and voltage ripple is large, there is stroboscopic when used on LED lights. In addition, the components in the existing converter have relatively short service life, large overall volume, less choice of capacitors, low limited control of the circuit, low output efficiency and not stable enough.

Therefore, there is an urgent need for a valley-fill and flicker-free PFC converter that can solve one or more of the above problems.

SUMMARY OF THE INVENTION

In order to solve one or more problems existing in the prior art, the present invention provides a valley-filling and stroboscopic-free PFC converter and a control method. The technical scheme that the present invention adopts for solving the above-mentioned problems is: a kind of valley filling and no stroboscopic PFC converter, it is characterized in that, is divided into following unit:

an input unit, the input unit is any one of an input capacitor, an input AC rectified busbar, an AC rectification plus a filter capacitor, and a wave circuit;

a converter, the converter is an inductor or a transformer;

a control unit, the control unit is composed of diodes and/or switch tubes, and the control unit is used to control the connection between the various units;

the input unit and the converter are electrically connected to form a first loop;

PFC unit, the PFC unit is provided with an energy storage capacitor and at least one switch tube, the PFC unit is electrically connected in front of the input unit or the converter, and passes through the input unit and/or the converter. The winding flyback is charged and formed a second loop;

The converter is rectified and filtered to form a third loop, which is an output unit;

The PFC unit is directly electrically connected to the converter, and the PFC unit provides a direct-connected valley-filling power supply to the converter to form a fourth loop, or the PFC unit is connected in series with the input unit to provide a series-connected valley-filling power supply to the converter. A fifth loop .

Further, it also includes: a series-parallel combination of valley filling output, the PFC is directly electrically connected to the converter in the low voltage stage of the fluctuation circuit, or connected in series with the input unit or directly connected or combined in series to provide energy to the converter, and then pass The converter provides energy to the output unit, so that the output is stable and flicker-free.

Further, the PFC unit is connected to the input bus, and the PFC unit is charged after the bridge stack or connected to the fluctuation circuit: in the voltage rise or high voltage stage, the input unit directly charges the PFC unit .

Further, the PFC unit is electrically connected to the winding of the converter: in the peak period of the input voltage, the input energy is stored in the converter by turning on the first loop, and then the control unit distributes the energy. energy of the converter to the PFC unit or the output unit.

Further, it also includes: superimposed windings, the energy of the energy storage capacitor in the PFC unit is equal to 0.5CV , C is the capacitance of the energy storage capacitor, V is the voltage at both ends of the energy storage capacitor, and is To boost the PFC unit energy, use the following superimposed windings:

On the converter windings, stacking windings is then electrically connected to the PFC unit;

The superimposed winding is arranged at any one of the positive end and the negative end of the input winding, and a high-voltage winding is arranged separately.

Further, each component is set in different positions as required to achieve corresponding functions; the diodes and switch tubes are set as: any one of negative terminal connection, positive terminal connection and different combined connections; the diode is connected by the switch as required. The switch tube is any one or a combination of MOS tube, triode, thyristor, and gallium nitride.

And the above-mentioned control method of a valley-filling and flicker-free PFC converter, the following nodes are divided by 0 to 180 degrees of the positive half-cycle after rectification as a cycle period:

T0, T0 is the low-voltage point with the lowest voltage;

T1, T1 are set in the voltage rising stage, the voltage is greater than T0, which is the low voltage boost point;

T2, T2 are set in the voltage rising stage, the voltage is greater than T1, which is the boost high voltage point;

T3, T3 are high voltage points, the voltage at T3 is greater than that at T2;

T4, T4 are set in the voltage drop stage, the voltage at T4 is less than the voltage at T3, which is the high voltage point of step-down;

T5, T5 are set in the voltage drop stage, the voltage at T5 is less than the voltage at T4, which is the low-voltage step-down point;

When the PFC unit is added to the circuit behind the fluctuation circuit, in the boost or high voltage stage T0-T3, T0-T4, T1-T3, T1-T4, T2-T3, T2-T4 stage, the PFC unit is turned on for a long time or intermittently conducts through charging;

When the PFC unit is added to the circuit between the windings, in the high voltage stage T2-T4 stage, by turning on the first loop, the input energy is stored in the converter, and the control unit distributes the excess energy of the converter. energy to the PFC unit to charge the PFC unit;

In the low pressure stage T4-T2 or T5-T1 stage, the PFC unit performs valley filling release.

Further, when the PFC unit is arranged between the windings, the control method for energy distribution and storage in the input high voltage stage is that, in the T2-T4 stage, the input end of the first loop control bus is turned on to store energy for the inductor or transformer winding. , and then the control unit distributes the energy stored on the inductor or the transformer winding, and the distribution method adopts any one of the following methods:

Method 1: The entire cycle energy is allocated to the output unit or the PFC unit, and the number of cycles is controlled as required;

Method 2: Distribute the energy of a single switching cycle to the PFC unit and the output unit in sequence through control.

Further, in the low-voltage stage, that is, the T4-T2 or T5-T1 stage, the control unit controls the PFC unit to directly connect the converter with valley-filling power or connect it in series with the bus input terminal and then perform valley-filling output for the converter, or The two are combined, and then the converter performs valley filling output; the PFC unit fills the valley and outputs in the low voltage stage, which means that in the low voltage stage, one or more combinations of AC power supply, direct power supply, and series power supply are used to supply power to meet the needs. Input current waveform and output stability;

The direct-connected valley-filling power supply also includes forward power supply and flyback power supply for the converter.

Further, in the stage T2-T4 of the PFC unit at high voltage, in addition to conventionally transforming the peak current to change the current waveform of the input circuit, or using a fixed peak current to adjust the frequency to change the equivalent current;

When the PFC unit is at low voltage, in addition to conventionally transforming the peak current to change the current waveform of the input circuit, or using the conduction frequency to reduce or reduce the conduction time to reduce the equivalent current.

The beneficial effects obtained by the present invention are as follows: the present invention provides a PFC unit and skillfully connects the PFC unit and the existing converter structure, so that the converter can be powered by alternating current during the falling edge of the mains waveform, and when the trough is low The PFC unit is only turned on for valley filling output, which can effectively solve the problem of unstable valley output, and the capacitor used for valley filling can reduce the capacity; The layout and design reduce the number of components used, reduce the overall volume, and at the same time ensure that the PF value is in a high range, the output is stable and there is no stroboscopic; the number of energy conversions is reduced, the output efficiency is improved, and the PFC module is added to the winding. At the same time, it can effectively control the withstand voltage of the circuit and the PFC capacitor, and can choose a low-voltage PFC capacitor to reduce the volume and effectively improve the service life. The above greatly improves the practical value of the present invention.

Description of drawings

Fig. 1 is the basic circuit diagram of a kind of valley filling and no stroboscopic PFC converter of the present invention;

Fig. 2 is the independent direct connection circuit diagram of a kind of valley filling and no stroboscopic PFC converter of the present invention;

3 is a series-parallel circuit diagram of a valley-filling and flicker-free PFC converter of the present invention;

4 is a non-isolated output boosting, winding energy storage series valley filling circuit diagram of a valley filling and flicker-free PFC converter of the present invention;

5 is a circuit diagram of a kind of valley filling and stroboscopic-free PFC converter of the present invention in which the energy storage of the flyback winding can be connected in series and the valley can be filled in parallel;

6 is a circuit diagram of the flyback winding energy storage of a valley-filling and stroboscopic-free PFC converter of the present invention, which can be connected in series, can be filled in parallel, and the secondary can be controlled;

Fig. 7 is a kind of circuit diagram of valley-filling and stroboscopic-free PFC converter of the present invention that can fill valleys with negative pressure stacking storage and both series and parallel;

8 is a circuit diagram of a valley-filling and stroboscopic-free PFC converter of the present invention that can fill valleys with both positive-voltage stacking and series-parallel;

FIG. 9 is a circuit diagram of the independent winding storage of a valley-filling and stroboscopic-free PFC converter of the present invention, and both can fill valleys in series and parallel;

10 is a circuit diagram of forward stacking and forward valley filling of a valley-filling and stroboscopic-free PFC converter of the present invention;

11 is a schematic waveform diagram of the present invention PFC in the input unit low-voltage parallel valley filling control method;

12 is a schematic waveform diagram of a PFC in the input unit low-voltage series valley filling control method of the present invention;

13 is a schematic waveform diagram of the present invention PFC in the input unit low-voltage series-parallel combined valley filling control method;

14 is a schematic waveform diagram of a low-voltage series valley filling control method for PFC between windings of the present invention;

15 is a schematic waveform diagram of the present invention PFC between windings, low-voltage series-parallel combined valley filling control method;

16 is a schematic waveform diagram of the control method of the present invention and the prior art to realize the difference between input and output current;

FIG. 17 is a schematic waveform diagram of a fixed IPK circuit implemented by the control method of the present invention.

Detailed ways

In order to make the above objects, features and advantages of the present invention easier to understand, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, the present invention can be implemented in many other ways different from this description, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

The invention discloses a valley-filling and stroboscopic-free PFC converter, which is characterized in that it is divided into the following units:

a converter, the converter is an inductor or a transformer;

The converter is rectified and filtered to form a third loop, and the third loop is an output unit;

The PFC unit is directly connected with the converter to form a fourth loop or the PFC unit is connected in series with the input unit to form a fifth loop.

FIG. 1 is a circuit diagram in which the PFC unit is arranged on the input bus and the valley is filled in parallel. As shown in FIG. 1 , the switch tube KP and the capacitor EC1P form the PFC unit, and the AC input is rectified by DB1 and then continuously positive half-cycle AC power is used as the input bus; the converter is the inductor LP, and the control unit is the switch tube K1; After the switch tube K1 is closed, the input unit and the converter (inductor LP) are electrically connected to form a first loop through the switch tube K1; the PFC unit (capacitor EC1P and switch tube KP) is electrically connected to the input unit A second loop is formed; the converter (inductance LP), diode D7 and capacitor EC3 form a third loop, and the third loop is both the output unit; the PFC unit and the converter (inductance LP) ) is electrically connected through the switch tube K1 and the switch tube KP to form a fourth loop (parallel valley filling circuit).

FIG. 11 is a schematic diagram of waveforms of the parallel valley filling control method exemplified in FIG. 1 . By turning on the first loop, the energy of the input unit is transferred to the converter and then transferred to the output unit through the converter; and in the boost or high voltage stage, the energy of the input unit is transferred to the converter by turning on the second loop The PFC unit is charged; when the fourth loop is turned on and the input unit is combined to store energy for the converter, and the converter transmits it to the output unit to provide stable energy to the load.

Figure 2 is a circuit diagram of the PFC unit set on the input bus, and the independent direct connection to fill the valley. As shown in Figure 2, the rectifier DP and the capacitor EC1P form the PFC unit; the input unit: the AC input is rectified by the diode DB1 and the continuous positive half-cycle AC is filtered by the capacitor EC1; the converter is a transformer T1, and the The control unit is a switch tube K1; after the switch tube K1 is closed, the input unit and the converter transformer T1 are electrically connected to form a first loop through the switch tube K1 and the diode DE; the PFC unit (capacitor EC1P and rectifier tube DP) ) and the input unit are electrically connected to form a second loop; the output winding of the transformer T1, the diode D7 and the capacitor EC3 form a third loop, and the third loop is both the output unit; the energy storage capacitor of the PFC unit The EC1P and the converter (transformer T1) are electrically connected through the switch tube K1A to form a fourth loop, that is, a parallel valley filling circuit.

FIG. 12 is a schematic diagram of waveforms of a parallel valley filling control method exemplified by the structure of FIG. 2 . The energy of the input unit is transferred to the converter by turning on the first loop, and then transferred to the output unit through the converter, and is transferred to the output unit by turning on the second loop in the boosting or high-voltage stage. The PFC unit is charged; when the fourth loop is turned on, the PFC unit is turned on to store energy for the converter, and is transmitted to the output unit through the converter to provide stable energy to the load.

FIG. 3 is a circuit diagram in which the PFC unit is arranged at the position of the bus bar of the input unit, and the valley is filled with a series-parallel combination. As shown in Figure 3, the switch tube KP and the capacitor EC1P constitute the PFC unit; the input unit: after the AC input is rectified by the diode DB1, the continuous positive half-cycle AC is filtered by the capacitor EC1; the converter is the transformer T1, so The control unit is the switch tube K1; the input unit and the transformer T1 are electrically connected to form a first loop through the switch tube K1 and the diode DP2; the capacitor EC1P of the input unit and the PFC unit is connected to the switch tube KP and the switch The tube K1 and the diode DP2 are electrically connected to form a second loop; the output winding of the transformer T1 is rectified by the diode D7 and then filtered by the capacitor EC3 to form a third loop, and the third loop is the output unit; the PFC unit The energy storage capacitor EC1P and the converter (transformer T1) are electrically connected through the switch tube KP1 to form a fourth loop, that is, a parallel valley filling circuit; the energy storage capacitor EC1P of the PFC unit is connected in series with the input unit through the switch tube KP2 Then, it is electrically connected with the converter (transformer T1) through the switch tube K1 to form a fifth loop, that is, a series valley filling circuit.

FIG. 13 is a schematic diagram of waveforms of a parallel-series combination valley filling control method exemplified by the structure of FIG. 3 . The energy of the input unit is transferred to the converter by turning on the first loop, and then transferred to the output unit through the converter, and the PFC unit is charged by turning on the second loop in the boost or high voltage stage ; Control the combination of the first loop, the fourth loop, and the fifth loop to conduct energy storage and transfer energy to the converter at the time of the valley, and transfer the energy to the output unit through the converter, thereby providing stability to the load. energy of.

FIG. 4 is a circuit diagram in which the PFC unit is arranged between the windings and the valley is filled in series. As shown in Figure 4, the switch tube KP and the capacitor EC1P form the PFC unit. After the AC input is rectified by the diode DB1, the continuous positive half-cycle AC is used as the input unit; the converter is the inductor LP, and the control unit is the switch tube K1; the input unit and the converter (inductance LP) are electrically connected to form a first loop through the switch tube K1 and the diode DP2; the capacitor EC1P of the PFC unit and the inductance LP of the converter are electrically connected through the switch tube KP is electrically connected to diode DP2 and diode D7 to form a second loop; the converter (inductor LP), the input unit and output filter capacitor EC3 are electrically connected to form a third loop through diode D7 and diode DP2. The third loop is the output unit; the PFC unit, the input unit and the converter (inductor LP) form a fifth loop through the switch tube K1 and the switch tube KP2, that is, a series valley filling circuit.

Figure 5 is a circuit diagram in which the PFC unit is arranged between the windings, and the valley is filled in series and parallel. As shown in Figure 5, the switch tube KP and the capacitor EC1P form the PFC unit. After the AC input is rectified by the diode DB1, the continuous positive half-cycle AC power is used as the input unit; the converter is the transformer T1, and the control unit is the switch tube K1; the input unit and the converter (transformer T1) are electrically connected through a switch tube K1 and a diode DP2 to form a first loop; the capacitor EC1P of the PFC unit and the converter (transformer T1) are electrically connected through a switch tube KP, switch tube KP2 and diode DP and diode DP2 are electrically connected to form a second loop; the output winding of transformer T1 and output filter capacitor EC3 are electrically connected through diode D7 to form a third loop, and the third loop is both the output unit ; The PFC unit and the primary winding of the transformer T1 form a fourth loop through the switch tube K1, the switch tube KP1 and the diode DP1, that is, a parallel valley filling circuit; the PFC unit, the input unit, and the transformer T1 pass through the switch tube K1 and The switch tube KP2 forms a fifth loop, that is, a valley-filling circuit in series.

Further according to the energy formula of the energy storage capacitor, the energy stored by the capacitor E=0.5CV 2 , C is the capacitance of the energy storage capacitor, V is the voltage at both ends of the energy storage capacitor, to improve the energy stored in the PFC unit. , using the following superimposed windings: Figures 6-9 are superimposed or boosted energy storage on the basis of Figure 5, specifically:

As shown in Figure 6, on the basis of Figure 5, the secondary rectifier tube D7 is changed to a bidirectional cut-off and a switch tube, and by controlling K7, the energy stored by the energy storage capacitor EC1P is equal to the number of turns of the primary winding NP* output VOUT/output The number of winding turns is NS, thereby improving the energy stored in the PFC capacitor.

As shown in Figure 7, on the basis of Figure 5, a winding is added to the negative end of the input winding to form a superimposed voltage with the input winding, thereby increasing the energy storage of the capacitor EC1P in the PFC unit when the second loop is turned on. energy.

As shown in Figure 8, on the basis of Figure 5, a winding is added to the positive end of the input winding to form a superimposed voltage with the input winding, thereby increasing the energy storage energy of the capacitor EC1P of the PFC unit when the second loop is turned on. .

As shown in Figure 9, on the basis of Figure 5, a winding is added, and the number of winding turns is increased, and then the PFC unit is added to the winding with the increased number of turns, so as to improve the overall performance when the second loop is turned on. The stored energy of the capacitor EC1P of the PFC unit.

As shown in Figure 10, Figure 10 is a circuit diagram in which the PFC unit is arranged between the windings, and the valley is filled with forward excitation. As shown in Figure 10, the switch tube KP and the capacitor EC1P form the PFC unit. After the AC input is rectified by DB1, the continuous positive half-cycle AC power is used as the input unit; the converter is the transformer T1, and the control unit is the switch tube K1 ; The input unit and the primary winding NP of the transformer T1 are electrically connected to form a first loop through the switch tube K1; the capacitor EC1P of the PFC unit and the stacked winding (NP string ND) of the transformer T1 are electrically connected to form the first loop through the switch tube KP. The second loop; the output winding NS of the transformer T1 and the output filter capacitor EC3 are electrically connected through the diode D7, the diode D7A and the inductor LS to form a third loop, and the third loop is the output unit; the PFC unit, the transformer T1 The winding NP is electrically connected through the switch tubes K1 and KP1 to form the fourth loop, that is, the forward excitation valley filling circuit;

The PFC capacitor energy storage control method described in Fig. 10 is the same as the control method in Fig. 5-Fig. 9; there is a difference in the way of filling the valley at T4-T2 or T5-T1: after the first loop is closed, during demagnetization, Or after the energy demagnetization of the first loop is completed, the fourth loop is opened, and the PFC unit directly supplies forward power to the transformer T1. According to the Faraday electromagnetic induction principle, the output winding NS voltage is higher than the output capacitor EC3, and the converter output The winding passes through the diode D7, the inductor LS and the capacitor EC3 to form a third loop. The NS winding voltage is higher than the voltage difference required by the output capacitor EC3, and then stored in the inductor LS; when the fourth loop is closed, the energy of the winding NS is cut off, The current of the inductor LS changes from large to small to form a back pressure. At this time, the diode D7A conducts freewheeling to supply power to the output capacitor or load, so that the energy can be output stably during the valley.

14 is a control method of a valley-filling and stroboscopic-free PFC converter according to the present invention. When the PFC unit is between windings and the input unit is at a valley, the PFC unit directly provides valley-filling to the converter. energy control methods;

15 is a control method in which the PFC unit directly provides energy to the converter for valley filling and the input unit is connected in series to provide valley filling energy to the converter when the input unit is in a valley.

And the control method of the above-mentioned one kind of valley filling and no stroboscopic PFC converter, as shown in Fig. 14-Fig. 15 in combination with Fig. 1 and the structure shown in Fig. 4-9, the specific method is as follows

Divide the following nodes with 0 to 180 degrees of the rectified positive half-cycle as a cycle:

T0, T0 is the low-voltage point with the lowest voltage;

T1, T1 are set in the voltage rising stage, the voltage is greater than T0, it is the low voltage boost point; T2, T2 is set in the voltage rising stage, the voltage is greater than T1, it is the boost high voltage point; T3, T3 are high voltage points, The voltage at T3 is greater than that at T2;

When the PFC unit is added after the wave circuit, in the boost or high voltage stage T0-T3, T0-T4, T1-T3, T1-T4, T2-T3, T2-T4 stage, the PFC unit is turned on for a long time or intermittently. to charge;

It should be noted that, with reference to FIG. 1 and FIG. 10-FIG. 14, when the PFC unit is arranged between the windings, the control method for energy distribution and storage in the input high voltage stage is: in the T2-T4 stage, the first loop is turned on. The input terminal of the control bus is used to store energy for the inductor or transformer winding, and then the control unit distributes the energy stored on the inductor or transformer winding, and the distribution method adopts any one of the following methods:

Specifically, as shown in FIGS. 1-9 in combination with FIGS. 10-14 , in the low-voltage stage, that is, the T4-T2 or T5-T1 stage, the control unit controls the PFC unit and the bus input terminal to be connected in series, in parallel, or a combination of both. , perform valley filling output; the PFC unit fills valley output in the low voltage stage, which means that in the low voltage stage, one or more combinations of AC power supply, parallel power supply, and series power supply are used to supply power to meet the needs of input current waveform and output stability.

Specifically, as shown in Fig. 10-Fig. 14, in the stage T2-T4 when the PFC unit is at high voltage, in addition to conventionally transforming the peak current to change the current waveform of the input circuit, a fixed peak current is also used to adjust the frequency to change the equivalent current ;

When the PFC unit is at low voltage, in addition to conventionally transforming the peak current to realize the sine wave of the input electric current, frequency reduction or conduction time reduction is also used to reduce the equivalent current.

Fig. 16 is the difference between the control method of a kind of valley-filling and stroboscopic-free PFC converter of the present invention and the prior art: wherein the upper part of Fig. 16 is for the comparison of the output current, the prior art single-stage PFC outputs the fluctuation of 2 times of alternating current, This technology realizes constant output;

The lower part of Fig. 16 shows the input current waveform that can be realized by this technology. The current waveform with spikes is the current waveform of adding the PFC unit to the bus of the input unit. It can also be a steamed bread wave as needed; for the PFC unit set between the windings, its The input waveform can realize sine wave, steamed bread wave and square wave through the combination of direct connection and series valley filling power supply.

FIG. 17 is a schematic waveform diagram of realizing a fixed IPK circuit by a control method of a valley-filling and stroboscopic-free PFC converter of the present invention. The technology also provides a fixed IPK current method to realize that the input current is a sine wave. Specifically, it is realized by the following methods: increasing the effective current by increasing the frequency in the high-voltage phase; reducing the switching frequency during the low valley, or reducing the conduction by filling the valley in series. Time to reduce the input effective current, so as to achieve a fixed IPK peak current, and the input current can also be a sine wave, steamed bread wave or square wave.

It should be pointed out that the above embodiments are only targeted examples, and each component is set in different positions as required to achieve corresponding functions; the settings of the diode and the switch tube are: negative terminal connection, positive terminal connection and different combined connections Any one of the diodes; the diode is replaced by a switch tube as needed; the switch tube is any one or a combination of MOS tube, triode, thyristor, and gallium nitride.

Then, different EMC components and safety components can be added as needed, and diodes, transistors, resistors, capacitors, optocouplers and other components can be added as needed; and switch tubes, VCC startup circuits, voltage divider detection circuits, current limit detection circuits, etc. It can be external or integrated into the chip. The conventional potential energy conversion unit includes isolated, non-isolated, forward excitation, flyback and other converters, or other methods are used for series or parallel discharge according to the above ideas. The exemplary circuits in the above description and in the accompanying drawings can add components to make them have the functions of parallel valley filling and series valley filling at the same time. Similarly, the circuit with parallel valley filling and series valley filling can also remove corresponding components to reduce valley filling. The way.

With the control method of the present invention, it can be concluded that the PFC unit added in the converter can store energy in the boost stage and fill the valley in the trough stage, and ensure that the PF value is higher on the premise of reducing components. Within the range of the converter, the overall volume of the converter can be reduced, and a stable current wave can be output to achieve no stroboscopic; in addition, half of the energy can be directly transferred to the output, which reduces the conversion of energy and improves the output efficiency; The control unit controls the circuit and effectively controls the withstand voltage value of the capacitor. Low-voltage capacitors can be selected, which not only reduces the volume but also effectively improves the service life of the converter.

To sum up, in the present invention, by setting up a PFC unit and skillfully connecting the PFC unit, the control unit and the existing booster circuit, transformer, stacking circuit, etc., the converter realizes the operation of the mains waveform. During the falling edge, AC power is used for power supply, and the PFC unit is turned on to perform valley filling output during the valley, which can effectively solve the problem of unstable valley output, and the capacitance used for valley filling can reduce the capacity; the present invention stores energy in the boosting stage, The valley is filled in the valley stage. The clever layout and design reduce the components used and the overall volume. At the same time, it can ensure that the PF value is in a high range, the output is stable and there is no stroboscopic; it reduces the number of energy conversions and improves the output. It can effectively control the withstand voltage of the circuit and the PFC capacitor, and can choose a low-voltage PFC capacitor to reduce the volume and effectively improve the service life. The above greatly improves the practical value of the present invention.

The above-mentioned embodiments only represent one or more embodiments of the present invention, and the descriptions thereof are specific and detailed, but should not be construed as limitations on the invention patent. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, which all belong to the protection scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

A valley-filling and stroboscopic-free PFC converter is characterized in that, it is divided into the following units:

an input unit, the input unit is any one of an input capacitor, an input AC rectified busbar, an AC rectification plus a filter capacitor, and a wave circuit;

a converter, the converter is an inductor or a transformer;

a control unit, the control unit is composed of diodes and/or switch tubes, and the control unit is used to control the connection between the various units;

the input unit and the converter are electrically connected to form a first loop;

PFC unit, the PFC unit is provided with an energy storage capacitor and at least one switch tube, the PFC unit is electrically connected in front of the input unit or the converter, and passes through the input unit and/or the converter. The winding flyback is charged and formed a second loop;

The converter is rectified and filtered to form a third loop, which is an output unit;

The PFC unit is directly electrically connected to the converter to provide energy directly to the converter and form a fourth loop; or the PFC unit is connected in series with the input unit to provide energy to the converter to form a fifth loop;

Divide the following nodes with 0 to 180 degrees of the rectified positive half-cycle as a cycle:

T0, T0 is the low-voltage point with the lowest voltage;

T1, T1 are set in the voltage rising stage, the voltage is greater than T0, which is the low voltage boost point;

T2, T2 are set in the voltage rising stage, the voltage is greater than T1, which is the boost high voltage point;

T3, T3 are high voltage points, the voltage at T3 is greater than that at T2;

T4 and T4 are set in the voltage drop stage, and the voltage is lower than the voltage at T3, which is the high voltage point of step-down;

T5, T5 are set in the voltage drop stage, the voltage at T5 is less than the voltage at T4, which is the low-voltage step-down point;

When the PFC unit is added to the circuit behind the wave circuit, in one of the boost or high voltage stages T0-T3, T0-T4, T1-T3, T1-T4, T2-T3, T2-T4, the PFC unit will be long-term Conduction or intermittent conduction for charging;

When the PFC unit is added to the circuit between the windings, in the high voltage stage T2-T4 stage, by turning on the first loop, the input energy is stored in the converter, and then the control unit distributes the the excess energy of the converter to the PFC unit to charge the PFC unit;

In the low pressure stage T4-T2 or T5-T1 stage, the PFC unit performs valley filling release;

In the low voltage stage, that is, the T4-T2 or T5-T1 stage, the control unit controls the PFC unit to supply power to the converter directly connected to the valley, or the PFC unit is connected to the bus input terminal in series and then supplies the converter to the converter Fill valley output;

The PFC unit fills the valley and outputs in the low-voltage stage, which means that in the low-voltage stage, one or more combinations of AC power supply, direct power supply, and series power supply are used to supply power to meet the needs of input current waveform and output stability;

The directly connected valley filling means that in the low voltage stage of the input unit, the PFC unit is directly connected to supply power to the converter. A flyback direct-connected valley filling that transfers energy to the output unit by boosting the voltage; or a forward direct-connecting valley filling that is directly transferred to the output unit during the period of supplying energy to the converter.
The valley-filling and flicker-free PFC converter according to claim 1, further comprising: charging the PFC unit through the control unit during the rising or high voltage stage of the input unit fluctuating voltage; In the low-voltage stage, the energy stored in the PFC unit in the high-voltage stage is filled and discharged by the control unit, so that the output is stable;

There are two methods of valley filling discharge: one method is to turn on the fourth loop, which is called direct power supply or direct connection valley filling or parallel valley filling; the other method is to turn on the fifth loop, which is called series connection For power supply or series valley filling, one or both of the above methods are used to realize valley filling discharge.
A valley-filling and stroboscopic-free PFC converter according to claim 1, wherein the PFC unit is connected to the input bus, and the PFC unit is connected to the charging mode behind the bridge stack or the fluctuation circuit: In the voltage rise or high voltage stage, the PFC unit is directly charged by the input unit.
The valley-filling and stroboscopic-free PFC converter according to claim 1, wherein the PFC unit is electrically connected to the winding of the converter: during the peak period of the input voltage, the first loop is turned on by turning on the PFC unit. , the input energy is stored in the converter, and the control unit distributes the energy of the converter to the PFC unit or the output unit.
The valley-filling and stroboscopic-free PFC converter according to claim 4, further comprising: superimposed windings, the energy of the energy storage capacitor in the PFC unit is equal to 0.5CV, and C is the The capacitance of the energy storage capacitor, V is the voltage at both ends of the energy storage capacitor, in order to improve the energy of the PFC unit, the following superimposed windings are used:

The converter is a transformer, and on the converter windings, superimposed windings are arranged and then electrically connected to the PFC unit;

The superimposed winding is arranged at any one of the positive end and the negative end of the input winding of the converter, and a high-voltage winding is arranged separately.
The valley-filling and stroboscopic-free PFC converter according to any one of claims 1-5, wherein each component is arranged in different positions as required to realize corresponding functions; Set as: any one of negative terminal connection, positive terminal connection and different combination connections; diodes are replaced by switch tubes as needed; switch tubes are: any one of MOS tube, triode, thyristor, and gallium nitride species or combination.
The valley-filling and stroboscopic-free PFC converter according to claim 1, wherein, when the PFC unit is arranged between the windings, the control method for energy distribution and storage in the input high voltage stage is that in the T2-T4 stage , turn on the input end of the first loop control bus to store energy for the inductor or transformer winding, and then the control unit distributes the energy stored on the inductor or transformer winding, and the distribution method adopts any one of the following methods:

Method 1: The entire cycle energy is allocated to the output unit or the PFC unit, and the number of cycles is controlled as required;

Method 2: Distribute the energy of a single switching cycle to the PFC unit and the output unit in sequence through control.
A valley-filling and flicker-free PFC converter according to claim 1, characterized in that, in the T2-T4 stage when the PFC unit is at high voltage, in addition to conventionally transforming the peak current to change the current waveform of the input circuit, it also adopts Fix the peak current, adjust the frequency to change the equivalent current;

When the PFC unit is at low voltage, in addition to conventionally transforming the peak current to realize the input sine wave current, it also reduces the frequency or the on-time to reduce the equivalent current.