CN112803752A

CN112803752A - Valley-filling and stroboflash-free PFC converter and control method

Info

Publication number: CN112803752A
Application number: CN202110293663.7A
Authority: CN
Inventors: 严宗周
Original assignee: Shenzhen Yuanneng Electric Appliance Co ltd
Current assignee: Shenzhen Yuanneng Electric Appliance Co ltd
Priority date: 2021-03-19
Filing date: 2021-03-19
Publication date: 2021-05-14
Anticipated expiration: 2041-03-19
Also published as: CN112803752B; WO2022194037A1

Abstract

The invention discloses a valley filling and stroboflash-free PFC converter and a control method thereof, which are characterized in that a PFC unit is provided with an energy storage capacitor and at least one switching tube, and the PFC unit is electrically connected in front of a ripple circuit or a converter and is charged through flyback of a bus input end and/or a winding; the PFC unit is matched with other circuits and combined with a corresponding control method, peak energy is stored in the PFC unit at a certain moment to improve the PF value, and the PFC unit releases valley filling according to needs to prevent output fluctuation; the PFC unit is controlled to store energy and release energy through an internal light-emitting tube and/or a diode, and when the PFC module is added between windings, an energy storage capacitor in the PFC unit can be controlled to be at a lower voltage, so that the withstand voltage of the PFC capacitor is reduced; realize steady output and do not have the stroboscopic, reduce the components and parts of inside use, and then reduce the whole volume of converter, improve life simultaneously.

Description

Valley-filling and stroboflash-free PFC converter and control method

Technical Field

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

Background

The existing converter generally performs filtering after alternating current rectification in order to provide stable energy output, but when a capacitor is directly added, the voltage of the capacitor is increased along with the load and is reduced along with the alternating current input, so that the effect of the capacitor is reduced; in the common valley filling circuit, the valley filling needs to be realized by serially charging capacitors and parallelly discharging the capacitors, the number of the capacitors is at least two or more, and the common valley filling circuit cannot select the valley filling time.

In the single-stage PFC circuit, in order to improve the PF value, the current and the voltage are required to be in the same phase, so that in the prior art, when the sine wave is in a valley, the output power of the converter designed by the single-stage PFC circuit is low or even no output is generated, the current and voltage ripples are large when the output is loaded, and the LED lamp is stroboscopic when the single-stage PFC circuit is used. And the service life of the components in the existing converter is relatively short, the whole volume is large, the selection margin of the capacitor is less, the limited control on the circuit is lower, and the output efficiency is not high and not stable enough.

Accordingly, there is a need for a valley fill and strobe free PFC converter and control method that addresses one or more of the above problems.

Disclosure of Invention

To address one or more of the problems of the prior art, the present invention provides a valley fill and no-strobe PFC converter and control method. The technical scheme adopted by the invention for solving the problems is as follows: a valley fill and no strobe PFC converter is characterized by being divided into the following units:

the input unit is any one of an input capacitor, an input alternating current rectified bus, an alternating current rectified and filtered capacitor and a fluctuation circuit;

the converter is an inductor or a transformer;

the control unit consists of a diode and/or a switching tube and is used for controlling the connection between each module and each unit;

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

the PFC unit is provided with an energy storage capacitor and at least one switching tube, is electrically connected in front of the input unit or the converter, and is subjected to flyback charging through a winding of the input unit and/or the converter to form a second loop circuit;

the converter forms a third loop through rectification and filtering, and the third loop is an output unit;

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

Further, still include: and the PFC is directly and electrically connected with the converter in the low-voltage stage of the fluctuation circuit, or is connected with the input unit in series or is directly connected or combined in series to provide energy for the converter, and then the converter provides energy for the output unit, so that the output is stable and has no stroboflash.

Further, the PFC unit is connected to an input bus, and the PFC unit is connected after the bridge or in a charging mode of a ripple circuit: and in the voltage rising or high-voltage stage, the input unit directly charges the PFC unit.

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

Further, still include: the energy of the energy storage capacitor in the PFC unit is equal to 0.5C V, and the following superposed windings are adopted for increasing the energy of the PFC unit:

on the converter winding, a winding is superposed and then electrically connected with the PFC unit;

the superposed winding is arranged at the positive end and the negative end of the input winding, and the high-voltage winding is independently arranged.

Furthermore, each component is arranged at different positions according to requirements, so that corresponding functions are realized; the arrangement of the diode and the switch tube is as follows: any one of a negative terminal connection, a positive terminal connection and a different combination connection; the diode is replaced by a switch tube according to the requirement; the switching tube is: any one or combination of MOS tube, triode, silicon controlled rectifier and gallium nitride.

And a valley filling and no-strobe PFC converter control method, dividing the following nodes by taking 0 to 180 degrees of the rectified positive half cycle as a cycle period: t0, T0 is the lowest valley point of voltage; t1, T1 is set in the voltage rising stage, and the voltage is greater than T0 and is a low voltage rising point; t2, T2 is set in the voltage rising phase, the voltage is greater than T1, and the voltage rising phase is a high voltage boosting point; t3, T3 is the high voltage point, the voltage at T3 is greater than at T2; t4, T4 is set in a voltage drop phase, the voltage at T4 is smaller than the voltage at T3, and the voltage is a high voltage drop point; t5, T5 is set in a voltage drop stage, the voltage at T5 is smaller than the voltage at T4, and is a low-voltage step-down point; when the PFC unit is added in a circuit behind the ripple circuit, the PFC unit is conducted for a long time or intermittently conducted to charge in the stages of boosting or high-voltage stages T0-T3, T0-T4, T1-T3, T1-T4, T2-T3 and T2-T4;

when a PFC unit is added to a circuit among windings, in a high-voltage stage T2-T4, input energy is stored in the converter by conducting a first loop, and then the control unit distributes redundant energy of the converter to the PFC unit to charge the PFC unit; during the valley period T4-T2 or T5-T1, the PFC unit performs valley filling release.

Further, when the PFC unit is disposed between windings, the control method for energy distribution and storage in an input high voltage stage includes, in a stage from T2 to T4, turning on the input terminal of the first loop control bus to store energy for an inductor or a transformer winding, and then the control unit distributes the energy stored in the inductor or the transformer winding by using any one of the following methods:

the method comprises the following steps: the energy of the whole period is distributed to an output unit or the PFC unit, and the number of the periods is controlled according to the requirement;

the second method comprises the following steps: energy is distributed to the PFC unit and the output unit in sequence through control of a single switching period.

Furthermore, in a low-voltage stage, namely T4-T2 or T5-T1, the control unit controls the PFC unit to directly fill the valley with power for the converter or to be connected with the input end of the bus in series and then to be used for filling the valley with output for the converter, or to be combined with the input end of the bus and then to be used for filling the valley with output for the converter; the PFC unit is used for valley filling and outputting in a low-voltage stage, namely one or more combined power supplies are carried out on alternating current power supply, direct connection power supply and series connection power supply in the low-voltage stage so as to meet the requirements of input current waveform and output stability;

the direct-connection valley filling power supply also comprises forward power supply and flyback power supply for the converter.

Further, the PFC unit changes the current waveform of the input circuit in a T2-T4 stage when the voltage is high, except that the conventional peak current is changed, or the fixed peak current is adopted, and the frequency is adjusted so as to change the equivalent current;

when the PFC unit is at low voltage, except for changing the current waveform of an input circuit by conventionally converting peak current, the conduction frequency is adopted to reduce or reduce the conduction time so as to reduce the equivalent current.

The beneficial effects obtained by the invention are as follows: according to the invention, the PFC unit is arranged and is skillfully connected with the existing converter structure, so that the converter is powered by alternating current during the falling edge of the waveform of the mains supply, and the PFC unit is turned on for valley filling output in the valley, the problem of unstable valley output can be effectively solved, and the capacity of a capacitor for valley filling can be reduced; the invention stores energy in a boosting or high-voltage stage and fills the valley in a valley stage, thereby reducing the used components and parts by ingenious layout and design, reducing the whole volume, ensuring the PF value in a higher range, outputting stably and having no stroboflash; the conversion frequency of energy is reduced, the output efficiency is improved, and when the PFC module is added between windings, the withstand voltage of a circuit and a PFC capacitor can be effectively controlled, the low-voltage PFC capacitor can be selected, the size is reduced, and the service life is effectively prolonged. The practical value of the invention is greatly improved.

Drawings

FIG. 1 is a basic circuit diagram of a valley fill and no strobe PFC converter of the present invention;

fig. 2 is a diagram of an independent direct connection circuit for a valley fill and no strobe PFC converter in accordance with the present invention;

FIG. 3 is a circuit diagram of a valley fill and no strobe PFC converter in series and parallel operation in accordance with the present invention;

FIG. 4 is a circuit diagram of a non-isolated output boost, winding energy storage series valley fill circuit of a valley fill and non-strobe PFC converter of the present invention;

FIG. 5 is a circuit diagram of a valley-fill and non-strobe PFC converter with flyback winding energy storage that can be cascaded and valley-filled in parallel in accordance with the present invention;

FIG. 6 is a circuit diagram of a valley-fill and non-strobe PFC converter with flyback winding energy storage that can be series-connected, valley-fill, and secondary-controlled in accordance with the present invention;

FIG. 7 is a circuit diagram of a valley fill and no-strobe PFC converter with negative-pressure stack storage, series-parallel valley fill;

FIG. 8 is a circuit diagram of a valley-fill and non-strobe PFC converter with positive voltage stack and series-parallel valley-fill;

FIG. 9 is a circuit diagram of a valley-fill and non-strobe PFC converter with independent winding storage, series-parallel valley-fill;

fig. 10 is a circuit diagram of a valley-fill and non-strobe PFC converter with forward-stack and forward-pumped valley-fill in accordance with the present invention;

fig. 11 is a schematic waveform diagram of the PFC low-voltage parallel valley fill control method of the present invention;

fig. 12 is a schematic waveform diagram of the PFC low voltage series valley fill control method of the present invention at the input unit;

fig. 13 is a schematic waveform diagram of the PFC low voltage series-parallel combination valley fill control method of the present invention at the input unit;

FIG. 14 is a schematic waveform diagram of the low voltage series valley fill control method of the PFC of the present invention between windings;

FIG. 15 is a schematic waveform diagram of the low voltage series-parallel combination valley fill control method of the PFC of the present invention between windings;

FIG. 16 is a schematic waveform diagram of the control method of the present invention and the prior art implementation of input-output current discrimination;

fig. 17 is a schematic waveform diagram of a circuit for implementing a fixed IPK according to the control method of the present invention.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

The invention discloses a valley filling and stroboflash-free PFC converter, which is characterized by comprising the following units:

the converter is an inductor or a transformer;

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

Fig. 1 is a circuit diagram of the PFC unit disposed on an input bus, with parallel valley filling adopted. As shown in fig. 1, the switch tube KP and the capacitor EC1P form the PFC unit, and the ac input is rectified by the DB1 and then continuously positive half-cycle ac is used as the input bus; the converter is an inductor LP, and the control unit is a switching 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 a switch tube K1; the PFC unit (a capacitor EC1P and a switching tube KP) and the input unit are electrically connected to form a second loop circuit; the converter (inductor LP), a diode D7 and a capacitor EC3 form a third loop, and the third loop is the output unit; the PFC unit and the converter (inductor LP) are electrically connected through a switch tube K1 and a switch tube KP to form a fourth loop (parallel valley filling circuit).

Fig. 11 is a waveform diagram illustrating the exemplary parallel valley fill control method of fig. 1. Transferring the energy of the input unit to the converter by conducting a first loop and then transferring the energy of the input unit to the output unit through the converter; the PFC unit is charged by conducting a second loop circuit in a boosting or high-voltage stage; and in the valley period, the converter is stored with energy by conducting the combination of the fourth loop and the input unit, and the energy is transferred to the output unit through the converter to provide stable energy for the load.

Fig. 2 is a circuit diagram of the PFC unit disposed on the input bus, and independently connected directly to fill the valley. As shown in fig. 2, the rectifier DP and the capacitor EC1P constitute the PFC unit; the input unit: the continuous positive half-cycle alternating current after the alternating current input is rectified by a diode DB1 is filtered by a capacitor EC 1; the converter is a transformer T1, and the control unit is a switch tube K1; after the switching tube K1 is closed, the input unit and the converter transformer T1 are electrically connected to form a first loop through the switching tube K1 and a diode DE; the PFC unit (a capacitor EC1P and a rectifier tube DP) and the input unit are electrically connected to form a second loop circuit; the output winding of the transformer T1, the diode D7 and the capacitor EC3 form a third loop, and the third loop is the output unit; the energy storage capacitor EC1P of the PFC unit and the converter (transformer T1) are electrically connected through a switching tube K1A to form a fourth loop circuit, namely a parallel valley filling circuit.

Fig. 12 is a waveform diagram illustrating an exemplary parallel valley fill control method for the structure of fig. 2. The energy of the input unit is transmitted to the converter by conducting a first loop circuit, then transmitted to the output unit by the converter, and the PFC unit is charged by conducting a second loop circuit in a boosting or high-voltage stage; and in the valley period, the fourth loop and the PFC unit are conducted, the energy is stored in the converter, and the energy is transferred to the output unit through the converter to provide stable energy for the load.

Fig. 3 is a circuit diagram of the PFC unit disposed at the bus position of the input unit, and the valley is filled by adopting a series-parallel combination. As shown in fig. 3, the switch tube KP and the capacitor EC1P constitute the PFC unit; the input unit: after the alternating current input is rectified by a diode DB1, continuous positive half-cycle alternating current is filtered by a capacitor EC 1; the converter is a transformer T1, and the control unit is a switch tube K1; the input unit and the transformer T1 are electrically connected to form a first loop through a switching tube K1 and a diode DP 2; the input unit and the capacitor EC1P of the PFC unit are electrically connected through a switch tube KP, a switch tube K1 and a diode DP2 to form a second loop circuit; the output winding of the transformer T1 is rectified by a diode D7 and filtered by a capacitor EC3 to form a third loop, and the third loop is the output unit; the energy storage capacitor EC1P of the PFC unit and the converter (transformer T1) are electrically connected through a switching tube KP1 to form a fourth loop circuit, namely a parallel valley filling circuit; the energy storage capacitor EC1P of the PFC unit is connected in series with the input unit through a switch tube KP2, and then is electrically connected with the converter (transformer T1) through a switch tube K1 to form a fifth loop circuit, namely a series valley filling circuit.

Fig. 13 is a waveform diagram illustrating an exemplary parallel-series combination valley-fill control method for the structure of fig. 3. The energy of the input unit is transferred to the converter by conducting the first loop circuit, then transferred to the output unit by the converter, and the PFC unit is charged by conducting the second loop circuit at the stage of boosting or high voltage; and in the valley period, the combination of the first loop, the fourth loop and the fifth loop is controlled to be conducted to store energy and transfer energy to the converter, and the energy is transferred to the output unit through the converter, so that stable energy is provided for the load.

Fig. 4 is a circuit diagram of the PFC unit disposed between windings with the valley filled in series. As shown in fig. 4, the switch tube KP and the capacitor EC1P constitute the PFC unit, and 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 an inductor LP, and the control unit is a switching tube K1; the input unit and the converter (inductor LP) are electrically connected to form a first loop through a switching tube K1 and a diode DP 2; a capacitor EC1P of the PFC unit and an inductor LP of the converter are electrically connected through a switching tube KP, a diode DP2 and a diode D7 to form a second loop circuit; the converter (inductor LP) and the input unit and output filter capacitor EC3 are electrically connected through a diode D7 and a diode DP2 to form a third loop, namely the output unit; the PFC unit, the input unit and the converter (inductor LP) form a fifth loop, i.e., a series valley fill circuit, through a switching tube K1 and a switching tube KP 2.

Fig. 5 is a circuit diagram of PFC cells arranged between windings with valley fill in series-parallel. As shown in fig. 5, the switch tube KP and the capacitor EC1P form the PFC unit, and 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 a transformer T1, and the control unit is a 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 switching tube KP and a switching tube KP2 and a diode DP2 to form a second loop circuit; the output winding of the transformer T1 and the output filter capacitor EC3 are electrically connected through a diode D7 to form a third loop, and the third loop is the output unit; the PFC unit and a primary winding of a transformer T1 form a fourth loop circuit, namely a parallel valley filling circuit, through a switching tube K1, a switching tube KP1 and a diode DP 1; the PFC unit, the input unit and the transformer T1 form a fifth loop circuit, namely a series valley filling circuit, through a switch tube K1 and a switch tube KP 2.

Further according to an energy formula of the energy storage capacitor, the energy stored by the capacitor E =0.5 × C × V, and in order to boost the energy stored by the PFC unit, the following superposed windings are used: wherein, fig. 6-9 are the stack or boost energy storage based on fig. 5, specifically:

as shown in fig. 6, based on fig. 5, the secondary rectifier D7 is changed to a bidirectional cut-off plus switch tube, and the energy stored in the energy storage capacitor EC1P is equal to the number of primary winding turns NP × output VOUT/output winding turns NS by controlling K7, so as to increase the energy stored in the PFC capacitor.

As shown in fig. 7, based on fig. 5, a winding is added to the negative end of the input winding, and a superimposed voltage is formed with the input winding, so that the stored energy of the capacitor EC1P in the PFC unit is boosted when the second loop is turned on.

As shown in fig. 8, based on fig. 5, a winding is added to the positive end of the input winding, and a superimposed voltage is formed with the input winding, so that the stored energy of the capacitor EC1P of the PFC unit is boosted when the second loop is turned on.

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

As shown in fig. 10, fig. 10 is a circuit diagram of the PFC unit disposed between the windings and the positive valley filling is adopted for the valley. As shown in fig. 10, the switch tube KP and the capacitor EC1P form the PFC unit, and after the ac input is rectified by the DB1, continuous positive half-cycle ac power is used as the input unit; the converter is a transformer T1, and the control unit is a switch tube K1; the input unit and the primary winding NP of the transformer T1 are electrically connected into a first loop through a switching tube K1; a capacitor EC1P of the PFC unit and a transformer T1 laminated winding (NP string ND) are electrically connected through a switch tube KP to form a second loop circuit; the output winding NS of the transformer T1 and the output filter capacitor EC3 are electrically connected through a diode D7, a diode D7A and an inductor LS to form a third loop, and the third loop is the output unit; the PFC unit and a winding NP of a transformer T1 are electrically connected through a switching tube K1 and a switching tube KP1 to form a fourth loop circuit, namely a forward valley filling circuit;

the PFC capacitor energy storage control method of fig. 10 is the same as the control method of fig. 5-9; there are differences in the way the valley filling outputs are at the low valleys T4-T2 or T5-T1: during demagnetization after the first loop is closed, or after the first loop is demagnetized, opening a fourth loop, and supplying power to a transformer T1 by the PFC unit directly in a forward direction, wherein according to the Faraday electromagnetic induction principle, the voltage of an output winding NS is higher than that of an output capacitor EC3, the output winding NS of the converter forms a third loop through a diode D7, an inductor LS and a capacitor EC3, and the voltage of the NS winding 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 becomes back voltage from large to small, and at this time, the diode D7A conducts the follow current to supply power to the output capacitor or the load, so that the energy is stably output during the valley period.

Fig. 14 is a control method of a valley-fill and strobe-free PFC converter according to the present invention, which is a control method for directly providing valley-fill energy to the PFC unit when the PFC unit is in a valley between windings and the input unit;

fig. 15 is a control method in which the PFC unit directly supplies the valley fill energy to the converter and the input unit is connected in series to supply the valley fill energy to the converter during the valley fill of the input unit.

And a method for controlling a valley fill and non-strobe PFC converter, as shown in FIGS. 14-15 in conjunction with the structure shown in FIG. 1 in conjunction with FIGS. 4-9, in the following manner

Dividing the following nodes by taking 0 to 180 degrees of the rectified positive half cycle as a cycle period: t0, T0 is the lowest valley point of voltage; t1, T1 is set in the voltage rising stage, and the voltage is greater than T0 and is a low voltage rising point; t2, T2 is set in the voltage rising phase, the voltage is greater than T1, and the voltage rising phase is a high voltage boosting point; t3, T3 is the high voltage point, the voltage at T3 is greater than at T2; t4, T4 is set in a voltage drop phase, the voltage at T4 is smaller than the voltage at T3, and the voltage is a high voltage drop point; t5, T5 is set in a voltage drop stage, the voltage at T5 is smaller than the voltage at T4, and is a low-voltage step-down point; when the PFC unit is added behind the fluctuation circuit, the PFC unit is conducted for a long time or intermittently conducted to charge in the stages of boosting or high-voltage stages T0-T3, T0-T4, T1-T3, T1-T4, T2-T3 and T2-T4;

It should be noted that, with reference to fig. 1 and fig. 10 to fig. 14, when the PFC unit is disposed between the windings, the control method for performing energy distribution and storage in the input high-voltage phase includes: and in the stage from T2 to T4, the input end of the first loop control bus is conducted to store energy for the inductor or the transformer winding, and then the control unit distributes the energy stored on the inductor or the transformer winding by adopting any one of the following methods:

the method comprises the following steps: the energy of the whole period is distributed into the output unit or the PFC unit, and the number of the periods is controlled according to the requirement;

Specifically, as shown in fig. 1-9 in combination with fig. 10-14, in a low-voltage stage, i.e., a stage T4-T2 or a stage T5-T1, the control unit controls the PFC unit to be connected in series, in parallel or in combination with a bus input terminal for valley filling output; the PFC unit is used for valley filling and outputting in a low-voltage stage, namely one or more combined power supplies are carried out on alternating current power supply, parallel power supply and serial power supply in the low-voltage stage so as to meet the requirements of input current waveform and output stability.

Specifically, as shown in fig. 10-14, the PFC unit changes the input circuit current waveform at the time of high voltage T2-T4, except that the input circuit current waveform is changed by conventionally converting the peak current, or the equivalent current is changed by adjusting the frequency by using the fixed peak current;

when the PFC unit is at low voltage, besides the input current sine wave is realized by conventionally converting peak current, the frequency is reduced or the conduction time is reduced so as to reduce equivalent current.

Fig. 16 shows the difference between the control method of a valley fill and no-strobe PFC converter of the present invention and the prior art: wherein the upper part of fig. 16 is directed to comparison of output current, the single-stage PFC of the prior art outputs 2 times fluctuation of ac, and the present technique achieves constant output;

the lower half of fig. 16 shows the input current waveform achieved by the present technology, wherein the current waveform with the peak is the current waveform of the PFC unit added to the bus of the input unit, and can be also the bread wave as required; aiming at the PFC unit arranged among the windings, the input waveform of the PFC unit can realize sine waves, steamed bread waves and square waves through the combination of direct connection and series valley filling power supply.

Fig. 17 is a schematic waveform diagram of a fixed IPK circuit implemented by a control method of a valley fill and no-strobe PFC converter according to the present invention. The technology also provides a fixed IPK current mode to realize that the input current is sine wave: the method is realized by the following steps: the effective current is increased in a high-voltage stage in a frequency increasing mode; in the low-ebb period, the input effective current is reduced by reducing the switching frequency or reducing the conduction time by serially connecting and filling the valley, so that the fixed IPK peak current is realized, and the input current can be sine wave, steamed bread wave or square wave.

It should be noted that the above embodiments are only examples, and each component is disposed at different positions as required to implement a corresponding function; the arrangement of the diode and the switch tube is as follows: any one of a negative terminal connection, a positive terminal connection and a different combination connection; the diode is replaced by a switch tube according to the requirement; the switching tube is: any one or combination of MOS tube, triode, silicon controlled rectifier and gallium nitride.

Different EMC components and safety components can be added according to the requirements, and components such as diodes, triodes, resistors, capacitors, optocouplers and the like are added according to the requirements; and the switch tube, the VCC starting circuit, the voltage division detection circuit, the current-limiting detection circuit and the like can be externally arranged and can also be integrated into the chip. The conventional potential energy conversion unit comprises an isolation converter, a non-isolation converter, a forward converter, a flyback converter and the like, or performs series or parallel discharge by adopting other methods according to the above thought. The exemplary circuits described above and shown in the drawings can add elements to make them have the functions of parallel valley filling and series valley filling at the same time, and the circuits having parallel valley filling and series valley filling at the same time can also remove corresponding elements to reduce the way of valley filling.

By matching with the control method, the PFC unit added in the converter can be obtained, energy can be stored in a boosting stage, valley filling is carried out in a valley stage, the PF value is ensured to be in a higher range on the premise of reducing components, the overall size of the converter is further reduced, a stable current wave is output, and no stroboflash is realized; half of the energy can be directly transmitted to the output, so that the energy conversion is reduced, and the output efficiency is improved; the control unit controls the circuit, so that the withstand voltage value of the capacitor is effectively controlled, the low-voltage capacitor can be selected, the size is reduced, and the service life of the converter is effectively prolonged.

In summary, the invention skillfully connects the PFC unit and the control unit with the existing boost circuit, transformer, and stack circuit, etc. by setting one PFC unit, the converter supplies power with alternating current during the falling edge of the mains waveform, and the PFC unit is turned on for valley filling output in the valley, so that the problem of unstable valley output can be effectively solved, and the capacitor for valley filling can reduce the capacity; according to the invention, energy storage is carried out in the step-up stage, and valley filling is carried out in the valley stage, so that components used are reduced due to ingenious layout and design, the whole volume is reduced, the PF value can be ensured to be in a higher range, stable output is realized, and no stroboflash exists; the conversion frequency of energy is reduced, the output efficiency is improved, the withstand voltage of the circuit and the PFC capacitor can be effectively controlled, the low-voltage PFC capacitor can be selected, the size is reduced, and the service life is effectively prolonged. The practical value of the invention is greatly improved.

The above-described examples merely represent one or more embodiments of the present invention, which are described in greater detail and detail, but are not to be construed as limiting the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the spirit of the invention, which falls within the scope of the invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. A valley fill and no strobe PFC converter is characterized by being divided into the following units:

the converter is an inductor or a transformer;

the PFC unit is directly and electrically connected with the converter, directly supplies energy to the converter and forms a fourth loop; or the PFC unit is connected with the input unit in series to provide energy for the converter to form a fifth loop.

2. The valley-fill and strobe-less PFC converter of claim 1, further comprising: charging the PFC unit through the control unit at the stage of the fluctuation voltage rise or high voltage of the input unit; in the low-voltage stage of input fluctuating voltage, the control unit carries out valley filling discharge on the energy stored in the high-voltage stage of the PFC unit, so that the output is stable;

there are two methods for valley fill discharge: one method is to turn on the fourth loop, called direct connection power supply or direct connection valley filling or parallel valley filling; another method is to turn on the fifth loop, called series power supply or series valley fill, and to implement valley fill discharge by using one or a combination of the above two methods.

3. The valley-fill and strobe-free PFC converter according to claim 1, wherein the PFC unit is connected to an input bus, the PFC unit being charged after a bridge or connected in a ripple circuit: and in the voltage rising or high-voltage stage, the input unit directly charges the PFC unit.

4. The valley-fill and strobe-free PFC converter of claim 1 wherein the PFC unit is electrically connected to windings of the converter: and in the input voltage peak stage, the input energy is stored in the converter by turning on the first loop, and the energy of the converter is distributed to the PFC unit or the output unit by the control unit.

5. The valley-fill and strobe-less PFC converter of claim 4, further comprising: the energy of the energy storage capacitor in the PFC unit is equal to 0.5C V, and the following superposed windings are adopted for increasing the energy of the PFC unit:

the converter is a transformer, and a winding is superposed on a winding of the converter and then is electrically connected with the PFC unit;

the superposed winding is arranged at the positive end and the negative end of the input winding of the converter, and a high-voltage winding is independently arranged.

6. The valley-fill and strobe-less PFC converter according to any one of claims 1-5,

each component is arranged at different positions according to requirements to realize corresponding functions; the arrangement of the diode and the switch tube is as follows: any one of a negative terminal connection, a positive terminal connection and a different combination connection; the diode is replaced by a switch tube according to the requirement; the switching tube is: any one or combination of MOS tube, triode, silicon controlled rectifier and gallium nitride.

7. A control method of a valley-fill and non-strobe PFC converter is characterized in that the following nodes are divided by taking 0 to 180 degrees of a rectified positive half cycle as a cycle period: t0, T0 is the lowest valley point of voltage; t1, T1 is set in the voltage rising stage, and the voltage is greater than T0 and is a low voltage rising point; t2, T2 is set in the voltage rising phase, the voltage is greater than T1, and the voltage rising phase is a high voltage boosting point; t3, T3 is the high voltage point, the voltage at T3 is greater than at T2; t4, T4 is set in the voltage drop stage, the voltage is less than the voltage at T3, and the voltage is a high voltage drop point; t5, T5 is set in a voltage drop stage, the voltage at T5 is smaller than the voltage at T4, and is a low-voltage step-down point; when the PFC unit is added in a circuit behind the ripple circuit, the PFC unit is conducted for a long time or intermittently conducted to charge in one of the boosting or high-voltage stages T0-T3, T0-T4, T1-T3, T1-T4, T2-T3 and T2-T4; when a PFC unit is added to a circuit among windings, in a high-voltage stage T2-T4, input energy is stored in the converter by conducting a first loop, and then the control unit distributes redundant energy of the converter to the PFC unit to charge the PFC unit; during the valley period T4-T2 or T5-T1, the PFC unit performs valley filling release.

8. The method of claim 7, wherein when the PFC unit is disposed between windings, the input high voltage stage is controlled by turning on the input terminal of the first loop control bus to store energy in the inductor or transformer winding during the T2-T4 period, and then the control unit distributes the energy stored in the inductor or transformer winding by any one of the following methods:

9. The method as claimed in claim 7, wherein the control unit controls the PFC unit to directly fill the valley with power or the PFC unit is connected in series with the input terminal of the bus bar to perform valley filling output to the converter during the low voltage stage, i.e. T4-T2 or T5-T1;

the PFC unit is used for valley filling and outputting in a low-voltage stage, namely one or more combined power supplies are carried out on alternating current power supply, direct connection power supply and series connection power supply in the low-voltage stage so as to meet the requirements of input current waveform and output stability;

the direct connection valley filling means that in the low-voltage stage of the input unit, the PFC unit directly supplies power to the converter, and the direct connection valley filling also comprises flyback direct connection valley filling for transferring energy to the output unit by flyback boosting after the energy is provided for the converter; or directly transferred to the output unit during energizing the converter.

10. The method of claim 7, wherein the PFC unit is operated at high voltage T2-T4, except that the input circuit current waveform is changed by conventional peak current conversion, or the equivalent current is changed by adjusting the frequency by using fixed peak current;

when the PFC unit is at low voltage, besides the input sine wave current is realized by converting peak current conventionally, the equivalent current is reduced by reducing the frequency or reducing the conduction time.