CN211830574U - Rear-stage active filter circuit of single-stage PFC converter - Google Patents

Rear-stage active filter circuit of single-stage PFC converter Download PDF

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CN211830574U
CN211830574U CN202020984690.XU CN202020984690U CN211830574U CN 211830574 U CN211830574 U CN 211830574U CN 202020984690 U CN202020984690 U CN 202020984690U CN 211830574 U CN211830574 U CN 211830574U
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张朝辉
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Abstract

The utility model relates to a single-stage PFC converter later stage active filter circuit comprises single-stage PFC converter (1), bidirectional converter (2), bootstrap electric capacity, support electric capacity and output electric capacity. The bidirectional converter (2) is a non-isolated DC bidirectional conversion circuit and can adopt topologies such as synchronous buck or boost and the like. The bidirectional converter (2), the bootstrap capacitor and the support capacitor form a DC side active filter circuit: the support capacitor is connected to the rear end of the bidirectional converter (2), and the bootstrap capacitor is connected in parallel to the output end of the single-stage PFC converter (1) after being connected in series with the front end of the bidirectional converter (2). The advantages are as follows: 1. the working voltage of the bidirectional converter (2) is obviously reduced by utilizing the voltage division of the bootstrap capacitor, and a low-voltage power device can be adopted. 2. The conversion power of the bidirectional converter (2) is far lower than the output power of the whole machine. 3. The efficiency of the whole machine is improved, and the circuit cost is reduced. The utility model relates to a single-stage PFC + DC side active filter's new technical scheme, the topology is succinct ingenious, can extensively be used for the various switching power supply of input high power factor and output no ripple.

Description

Rear-stage active filter circuit of single-stage PFC converter
Technical Field
The utility model relates to a single-stage PFC converter later stage active filter circuit is a switching power supply technique, belongs to power electronic technology field.
Background
At present, an isolated AC-DC converter with high power factor has two technical schemes, namely a single-stage conversion topology and a two-stage conversion topology.
The single-stage conversion topology mainly includes single-stage PFC (power factor correction) converters such as a flyback converter and a bridge converter, and a combined single-stage converter composed of a PFC converter and a DC-DC converter (sharing a set of switching tube and control circuit). The single-stage PFC converter is characterized by high power factor, but the direct current output end contains second harmonic ripple waves. The combined single-stage converter has the characteristics that the ripple of the direct current output end and the power factor of the alternating current input end can be optimized in a compromise mode, the ripple of the direct current output end can be reduced or eliminated, and the power factor of the input end can be reduced.
The scheme of the two-stage conversion topology is that the first stage is power factor correction AC-DC conversion, and the second stage is DC-DC conversion. Which is divided into two technical routes. One is a first-stage AC-DC non-isolation, and generally adopts a Boost topology; and the second stage DC-DC isolation mainly comprises topologies such as phase-shifted full-bridge, LLC conversion, single-end conversion and the like. The other is a first-stage AC-DC isolation, namely a single-stage PFC converter, and mainly comprises topologies such as a flyback topology, a bridge topology and the like; and the second-stage DC-DC is not isolated and mainly has topology such as Buck, Boost, Buck-Boost and the like. The two-stage conversion topology can completely eliminate output ripples.
The main disadvantage of the two-stage conversion topology scheme is that the circuit is complex. Secondly, the efficiency of the whole machine is reduced. And high cost. This is due to the fact that all of the input power needs to go through two stages of power conversion to reach the load.
The above is only for the purpose of assisting understanding of the technical solutions of the present invention, and does not represent an admission that the above is the prior art.
SUMMERY OF THE UTILITY MODEL
The utility model aims at overcoming the not enough of above-mentioned prior art, design a single-stage PFC converter back level active filter circuit. The active filter is a novel technical scheme of single-stage PFC + direct-current side active filter, the working voltage and the conversion power of a converter in an active filter circuit are reduced by using a simple and ingenious circuit topology, the efficiency of the whole machine is improved, and the cost is reduced.
The technical scheme of the utility model as follows.
The post-stage active filter circuit of the single-stage PFC converter is composed of the single-stage PFC converter (1), a bidirectional converter (2), a bootstrap capacitor (C1), a support capacitor (C2) and an output capacitor (Co). The single-stage PFC converter (1) adopts a flyback topology or a bridge topology and is provided with one or more direct current outputs; the bidirectional converter (2) is a non-isolated DC-DC bidirectional conversion circuit and adopts a synchronous buck topology, a synchronous boost topology or a synchronous boost-buck topology; the bidirectional converter (2) has a front end and a back end, and four ports of the bidirectional converter are respectively marked as a front end positive P1, a front end negative N1, a back end positive P2 and a back end negative N2; so-called DC-DC bi-directional conversion is performed between the front end and the back end. Wherein:
the positive electrode Vo and the ground end GND of the direct-current output of the single-stage PFC converter (1) are respectively connected with the positive electrode and the negative electrode of an output capacitor (Co); the rear end positive P2 and the rear end negative N2 of the bidirectional converter (2) are respectively connected with the positive pole and the negative pole of the supporting capacitor (C2). The bidirectional converter (2), the bootstrap capacitor (C1) and the support capacitor (C2) form a direct-current side active filter circuit, and the connection modes of the bidirectional converter and the single-stage PFC converter (1) are two: the bidirectional converter (2) and the single-stage PFC converter (1) are connected in common, namely, the positive pole Vo of the single-stage PFC converter (1) is connected with the positive pole of a bootstrap capacitor (C1), the negative pole of the bootstrap capacitor (C1) is connected with the front-end positive P1 of the bidirectional converter (2), and the front-end negative N1 of the bidirectional converter (2) is connected with the ground GND of the single-stage PFC converter (1). The other is that the bidirectional converter (2) is connected with the common anode of the single-stage PFC converter (1), namely the anode Vo of the single-stage PFC converter (1) is connected with the front end anode P1 of the bidirectional converter (2), the front end cathode N1 of the bidirectional converter (2) is connected with the anode of the bootstrap capacitor (C1), and the cathode of the bootstrap capacitor (C1) is connected with the ground GND of the single-stage PFC converter (1).
The term "bidirectional conversion circuit" refers to a circuit in which current/electric energy can flow in both directions, i.e., the current/electric energy can flow from the front end of the converter to the rear end, or from the rear end to the front end.
Compared with the prior art, the utility model has the following advantages.
1) The utility model discloses, utilize bootstrap capacitor (C1) partial pressure for the front end voltage (being the voltage between positive P1 of front end and the negative N1 of front end) of bidirectional converter (2) is showing and is reducing, and then makes the rear end voltage (being the voltage between positive P2 of rear end and the negative N2 of rear end) also show and reduces. Therefore, the bidirectional converter (2) can adopt a low-voltage power device.
2) The utility model discloses, the reactive power that bidirectional converter (2) were handled is far less than single-stage PFC converter (1) output's alternating current component. Therefore, the power loss of the bidirectional converter (2) is further reduced.
3) The utility model discloses, utilize succinct ingenious circuit topology, reduced the operating voltage and the transform power of bidirectional converter (2) among the active filter circuit of back level, improved complete machine efficiency, reduced the circuit cost.
Drawings
Fig. 1 is a schematic diagram of a common ground connection of a post-stage active filter circuit of a single-stage PFC converter.
Fig. 2 is a schematic diagram of the common positive connection of the post-stage active filter circuit of the single-stage PFC converter.
The PFC converter comprises a 1-single-stage PFC converter, a 2-bidirectional converter, a C1-bootstrap capacitor, a C2-supporting capacitor and a Co-output capacitor. u. ofaThe AC input power source, Vo, the anode, GND and the ground terminal.
Fig. 3 is a common-negative synchronous buck topology that can be used by the bidirectional converter (2) of the present invention.
Fig. 4 is a common-anode synchronous buck topology that can be used by the bidirectional converter (2) of the present invention.
Wherein, Q1, Q2-switch tube, Lr-filter inductance.
Detailed Description
The present invention will be described and analyzed in detail with reference to the preferred embodiments thereof, which are illustrated in the accompanying drawings. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of them.
To put it another way, the descriptions of "front end", "back end", etc. of the bidirectional converter (2) referred to in the present invention are for convenience indicative of illustration only, and are not to be construed as indicating specific locations or proper terms thereof.
1. Preferred embodiments of the present invention
As shown in fig. 1 and 2, the post-stage active filter circuit of the single-stage PFC converter is composed of the single-stage PFC converter (1), the bidirectional converter (2), a bootstrap capacitor (C1), a support capacitor (C2), and an output capacitor (Co). The single-stage PFC converter (1) adopts a flyback topology or a bridge topology and is provided with one or more direct current outputs; the bidirectional converter (2) is a non-isolated DC-DC bidirectional conversion circuit and adopts a synchronous buck topology, a synchronous boost topology or a synchronous boost-buck topology; the bidirectional converter (2) has a front end and a back end, and four ports of the bidirectional converter are respectively marked as a front end positive P1, a front end negative N1, a back end positive P2 and a back end negative N2; so-called DC-DC bi-directional conversion is performed between the front end and the back end. Wherein:
the positive electrode Vo and the ground end GND of the direct-current output of the single-stage PFC converter (1) are respectively connected with the positive electrode and the negative electrode of an output capacitor (Co); the rear end positive P2 and the rear end negative N2 of the bidirectional converter (2) are respectively connected with the positive pole and the negative pole of the supporting capacitor (C2). The bidirectional converter (2), the bootstrap capacitor (C1) and the support capacitor (C2) form a direct-current side active filter circuit, and the connection mode of the direct-current side active filter circuit and the single-stage PFC converter (1) is two. One is that the bidirectional converter (2) is connected in common with the single-stage PFC converter (1), as shown in fig. 1; namely, the positive electrode Vo of the single-stage PFC converter (1) is connected with the positive electrode of a bootstrap capacitor (C1), the negative electrode of the bootstrap capacitor (C1) is connected with the front end positive P1 of the bidirectional converter (2), and the front end negative N1 of the bidirectional converter (2) is connected with the ground end GND of the single-stage PFC converter (1). The other is that the bidirectional converter (2) is connected with the common anode of the single-stage PFC converter (1), as shown in figure 2; namely, the positive pole Vo of the single-stage PFC converter (1) is connected with the front end positive P1 of the bidirectional converter (2), the front end negative N1 of the bidirectional converter (2) is connected with the positive pole of the bootstrap capacitor (C1), and the negative pole of the bootstrap capacitor (C1) is connected with the ground end GND of the single-stage PFC converter (1).
The load is connected by the positive pole Vo and the ground terminal GND.
The term "bidirectional conversion circuit" refers to a circuit in which current/electric energy can flow in both directions, i.e., the current/electric energy can flow from the front end of the converter to the rear end, or from the rear end to the front end. For the bidirectional converter (2), a synchronous buck topology, a synchronous boost topology or a synchronous buck-boost topology can be adopted, and bidirectional current/power flow can be realized.
As shown in fig. 3, the common-negative synchronous buck topology adopted by the bidirectional converter (2) is composed of two switching tubes (Q1, Q2) and a filter inductor (Lr). The front negative N1 and the rear negative N2 are connected together; the source electrode of the switching tube (Q2) is connected with the front end negative N1 and the rear end negative N2; the drain electrode of the switching tube (Q2) is connected with the source electrode of the switching tube (Q1) and one end of the filter inductor (Lr), and the other end of the filter inductor (Lr) is connected with the front positive P1; the drain of the switching tube (Q1) is connected with the rear positive P2.
As shown in fig. 4, the common-positive-electrode synchronous buck topology adopted by the bidirectional converter (2) is composed of two switching tubes (Q1, Q2) and a filter inductor (Lr). The front end positive P1 and the rear end positive P2 are connected together; the drain electrode of the switching tube (Q1) is connected with the front positive P1 and the rear positive P2; the source electrode of the switching tube (Q1) is connected with the drain electrode of the switching tube (Q2) and one end of the filter inductor (Lr), and the other end of the filter inductor (Lr) is connected with the front negative N1; the source electrode of the switching tube (Q2) is connected with the rear end negative N2.
2. The working principle of the utility model
The working principle of the post-stage active filter circuit of the single-stage PFC converter is analyzed in detail from the following four aspects. These four aspects can be summarized as: the output voltage of the single-stage PFC converter; a voltage transfer function of the bidirectional converter (2); reactive power distribution and overall efficiency analysis; the working voltage and the capacitance of the bidirectional converter (2) are selected.
2.1 output Voltage of Single-stage PFC converter (1)
The single-stage pfc (power Factor correction) converter is a power conversion circuit that outputs a dc voltage by single-stage power conversion and corrects a power Factor. The output of which is a DC voltage VOAnd a direct current IOThe input quantity is an AC voltage uaAnd an alternating current ia. The control strategy of the converter is to stabilize the required direct current output quantity and simultaneously realize the power factor correction of the input end.
So-called Power Factor Correction (PFC), i.e. an alternating current iaTracking an ac voltage uaSo that their waveforms are identical in phase, thereby achieving a high power factor. Theoretically, power factorThe number PF is less than or equal to 1. When PF is 1, there are:
Figure BDA0002520130610000041
in the formula (E-1), VaIs an alternating voltage uaEffective value of (I)aIs an alternating current iaω is the angular frequency of the sinusoidal alternating current. Setting the efficiency of the single-stage PFC converter as eta, the AC input power P of the single-stage PFC converteraAnd DC output power PoRespectively as follows:
Figure BDA0002520130610000042
will output power PoInto a direct current component
Figure BDA0002520130610000043
Plus an alternating component
Figure BDA0002520130610000044
In the form of:
Figure BDA0002520130610000045
similarly, the DC output voltage VOCan be decomposed into DC components
Figure BDA0002520130610000046
Plus an alternating component
Figure BDA0002520130610000047
In the form of:
Figure BDA0002520130610000048
the AC component of the DC output voltage is analyzed by taking the resistive load as an example
Figure BDA0002520130610000049
Because the load containing reactance component (inductive reactance or capacitive reactance) is connected in parallel with the filter capacitor, the parallel model of the capacitor and the resistor can be equivalent.
According to the law of conservation of energy, the linear superposition theorem and the circuit theory, the following differential equation is obtained:
Figure BDA0002520130610000051
wherein C is a filter capacitor, RoIs a load resistor. In view of the fact
Figure BDA0002520130610000052
The formula (E-5) is simplified as:
Figure BDA0002520130610000053
the differential equation of the formula (E-6) is solved to obtain the AC component
Figure BDA0002520130610000054
The expression of (a) is as follows:
Figure BDA0002520130610000055
as can be seen from the equation (E-7), the AC component of the output voltage of the single-stage PFC converter
Figure BDA0002520130610000056
Is 2 times the angular frequency of the input ac voltage and is therefore referred to as the second harmonic. Increasing the filter capacitance C can reduce the second harmonic but cannot completely eliminate it. If the second harmonic is to be eliminated completely, another technical means is required.
2.2 Voltage transfer function of bidirectional converter (2)
The non-isolated DC-DC bidirectional conversion circuit has six basic topologies, namely synchronous Buck, Boost, Buck-Boost, Sepic, Cuk and Zeta. Wherein Buck is Buck conversion, Boost is Boost conversion, and Buck-Boost and Sepic, Cuk and Zeta are Boost-Buck conversion. When the non-isolated DC-DC bidirectional conversion circuit works in a current continuous mode, the voltage transfer function is as follows:
Figure BDA0002520130610000057
in the formula (E-8), D is the conduction duty ratio of the switching tube, namely the duty ratio of PWM control; v1And V2The voltage of the front end and the voltage of the rear end of the non-isolated DC-DC bidirectional conversion circuit are respectively.
The bidirectional converter (2) of the utility model can adopt one of the six basic topologies. Without loss of generality, detailed analysis is made below with reference to fig. 1 and 3, taking as an example that the bidirectional converter (2) employs a common-negative synchronous buck topology and is connected in common with the single-stage PFC converter (1).
Setting the voltage V of the bootstrap capacitor (C1)C1And a voltage V of the supporting capacitor (C2)C2Respectively as follows:
Figure BDA0002520130610000058
in the formula (E-9),
Figure BDA0002520130610000061
and
Figure BDA0002520130610000062
a direct current component and an alternating current component of the bootstrap capacitor (C1) voltage, respectively;
Figure BDA0002520130610000063
and
Figure BDA0002520130610000064
the dc component and the ac component of the support capacitor (C2) voltage, respectively.
As shown in fig. 1 and 3, the front end voltage V of the bidirectional converter (2)1And a back end voltage V2Respectively as follows:
Figure BDA0002520130610000065
according to equation (E-8), if the bidirectional converter (2) is operating in current continuous mode, its voltage transfer function is:
Figure BDA0002520130610000066
in the formula (E-11), DtIs the on duty cycle of the switching tube Q1, which varies with time. Neglecting the dead time, the conduction duty ratio of the switching tube Q2 is (1-D)t). If so that
Figure BDA0002520130610000067
Then the output voltage
Figure BDA0002520130610000068
And VC1、VC2The relationship of (1) is:
Figure BDA0002520130610000069
it can be seen that, in order to completely eliminate the second harmonic in Vo, it is only necessary to feedback-control Dt to satisfy the formula (E-12). At this time, since the AC component (i.e., reactive power) of the output power of the single-stage PFC converter (1) is absorbed by the bootstrap capacitor (C1) and the support capacitor (C2), the AC component is absorbed by the bootstrap capacitor (C1) and the support capacitor (C2) in total
Figure BDA00025201306100000617
And
Figure BDA00025201306100000618
in the form of a second harmonic similar to equation (E-7).
2.3 reactive power distribution and overall efficiency analysis
The bidirectional converter (2), the bootstrap capacitor (C1) and the support capacitor (C2) form a DC side active filter circuit, and when the DC side active filter circuit completely filters out the DC output voltage VoAt the second harmonic of (3), only the DC component of the output voltage
Figure BDA00025201306100000610
According to the formula (E-3), the AC component of the output current of the single-stage PFC converter (1)
Figure BDA00025201306100000611
Comprises the following steps:
Figure BDA00025201306100000612
because of the fact that
Figure BDA00025201306100000613
The alternating current component of the voltage of the bootstrap capacitor C1
Figure BDA00025201306100000614
Comprises the following steps:
Figure BDA00025201306100000615
without loss of generality, for ease of description, the following parameters may be set:
Figure BDA00025201306100000616
in the formula (E-15), λ is called bootstrap coefficient and is called ripple coefficient; in general, λ is 0.7 to 0.9.
According to the equations (E-9), (E-13) and (E-15), the bootstrap capacitor C1 absorbs the reactive power
Figure BDA0002520130610000071
Comprises the following steps:
Figure BDA0002520130610000072
according to the equations (E-16) and (E-3), the reactive power absorbed by the supporting capacitor C2
Figure BDA0002520130610000073
Comprises the following steps:
Figure BDA0002520130610000074
according to the formula (E-17) and the formula (E-7), the alternating current component of the voltage of the supporting capacitor C2 is obtained
Figure BDA0002520130610000075
Comprises the following steps:
Figure BDA0002520130610000076
as can be seen from the formulas (E-16) and (E-17), the AC reactive power
Figure BDA0002520130610000077
And
Figure BDA0002520130610000078
contains not only the second harmonic but also the higher harmonic, which is caused by the active filtering performed by the bidirectional converter (2).
The alternating current power processed by the bidirectional converter (2) is
Figure BDA0002520130610000079
Theoretically
Figure BDA00025201306100000710
Is reactive power. However, the flow of ac power into and out of the supporting capacitor C2 through the bidirectional converter (2) is lossy, and this loss is supplemented by real power to maintain VC1And VC2The stability of (2). The loss is recorded as Δ P2，ΔP2Including the losses of the switching tubes (Q1, Q2), the filter inductance Lr and the support capacitance C2. The average value of the loss can be obtained by integration according to the formula (E-17)
Figure BDA00025201306100000711
Comprises the following steps:
Figure BDA00025201306100000712
in the formula eta2The conversion efficiency of the bidirectional converter (2). As can be seen from the formula (E-19), the AC power output by the single-stage PFC converter (1)
Figure BDA00025201306100000713
Therein is only
Figure BDA00025201306100000714
That is, a few parts generate filtering loss, and the efficiency of the whole machine is greatly improved. The loss is smaller as λ is larger, and therefore, the DC voltage component of the bootstrap capacitor C1 should be increased as much as possible
Figure BDA00025201306100000715
2.4 operating Voltage and capacitance selection for a bidirectional converter (2)
According to the equations (E-14) and (E-18), the modes of the alternating voltage components of the bootstrap capacitor C1 and the support capacitor C2 are as follows:
Figure BDA0002520130610000081
according to the formula (E-11), since 0. ltoreq. D t1, so one of the requirements for the normal operation of the bidirectional converter (2) is:
Figure BDA0002520130610000082
substituting formula (E-9) and formula (E-15) for formula (E-21) gives:
Figure BDA0002520130610000083
without loss of generality, the following can be selected:
Figure BDA0002520130610000084
from the formulas (E-20) and (E-15), it is deduced:
Figure BDA0002520130610000085
one initial state to consider is: when the single-stage PFC converter (1) is operated and the bidirectional converter (2) is not operated, the body diode of the switching tube Q1 is conducted, and the bootstrap capacitor C1 and the support capacitor C2 output voltage VoPartial pressure. In order to ensure that the voltage at C2 is not higher than its steady operation voltage, and the voltage at C1 is not lower than its steady operation voltage, the support capacitor C2 is selected as follows:
Figure BDA0002520130610000086
it should be noted that, since the bootstrap capacitor C1 and the supporting capacitor C2 completely absorb the second harmonic wave output by the single-stage PFC converter (1), the capacity of the output capacitor Co may be much smaller than that of the bootstrap capacitor C1 and the supporting capacitor C2. This is also why it is called "output capacitance" and not called "filter capacitance".
From the formulae (E-25) and (E-20), σ is given as:
Figure BDA0002520130610000091
substituting equation (E-26) for the first equation of equation (E-23) yields:
Figure BDA0002520130610000092
according to the formula (E-10), the front end voltage V of the bidirectional converter (2)1And a back end voltage V2The peak values of (a) are:
Figure BDA0002520130610000093
in the formula, V1_PAnd V2_PAre each V1And V2Peak value of (a). As can be seen from the equation (E-28), as the bootstrap coefficient λ increases, the peak value V of the front-end voltage and the back-end voltage of the bidirectional converter (2)1_PAnd V2_PAre all reduced and are far awayLess than the output DC voltage
Figure BDA0002520130610000094
I.e. the operating voltage of the bidirectional converter (2) is significantly reduced. Therefore, the bidirectional converter (2) can select a low-voltage power device with low on-resistance, so that the efficiency is further improved, and the cost is reduced.
The bidirectional converter (2) adopts a common-negative electrode synchronous buck topology and is connected with the single-stage PFC converter (1) in a common ground mode to form an exemplary embodiment, and the working principle of the bidirectional converter is analyzed in detail. When the bidirectional converter (2) adopts a non-isolated DC-DC bidirectional conversion circuit outside a synchronous buck topology and is connected with the output voltage common anode of the single-stage PFC converter (1), the analysis process can be carried out according to a similar principle, and the details are not described herein.
The above only is the preferred embodiment of the present invention, not limiting the scope of the present invention, all the equivalent structure changes made by the contents of the specification and the drawings under the inventive concept of the present invention, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims (1)

1. The post-stage active filter circuit of the single-stage PFC converter is composed of a single-stage PFC converter (1), a bidirectional converter (2), a bootstrap capacitor (C1), a support capacitor (C2) and an output capacitor (Co); the single-stage PFC converter (1) adopts a flyback topology or a bridge topology and is provided with one or more direct current outputs; the bidirectional converter (2) is a non-isolated DC-DC bidirectional conversion circuit and adopts a synchronous buck topology, a synchronous boost topology or a synchronous boost-buck topology; the bidirectional converter (2) has a front end and a back end, and four ports of the bidirectional converter are respectively marked as a front end positive P1, a front end negative N1, a back end positive P2 and a back end negative N2; so-called DC-DC bi-directional conversion is performed between the front end and the back end; the method is characterized in that:
the positive electrode Vo and the ground end GND of the direct-current output of the single-stage PFC converter (1) are respectively connected with the positive electrode and the negative electrode of an output capacitor (Co), and the rear-end positive electrode P2 and the rear-end negative electrode N2 of the bidirectional converter (2) are respectively connected with the positive electrode and the negative electrode of a supporting capacitor (C2); the bidirectional converter (2), the bootstrap capacitor (C1) and the support capacitor (C2) form a direct-current side active filter circuit, and the connection modes of the bidirectional converter and the single-stage PFC converter (1) are two: one is that the bidirectional converter (2) is connected with the single-stage PFC converter (1) in common, namely the positive pole Vo of the single-stage PFC converter (1) is connected with the positive pole of a bootstrap capacitor (C1), the negative pole of the bootstrap capacitor (C1) is connected with the front end positive P1 of the bidirectional converter (2), the front end negative N1 of the bidirectional converter (2) is connected with the ground GND of the single-stage PFC converter (1); the other is that the bidirectional converter (2) is connected with the common anode of the single-stage PFC converter (1), namely the anode Vo of the single-stage PFC converter (1) is connected with the front end anode P1 of the bidirectional converter (2), the front end cathode N1 of the bidirectional converter (2) is connected with the anode of the bootstrap capacitor (C1), and the cathode of the bootstrap capacitor (C1) is connected with the ground GND of the single-stage PFC converter (1).
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