CN114123839A - Isolated bidirectional AC/DC conversion circuit and device - Google Patents
Isolated bidirectional AC/DC conversion circuit and device Download PDFInfo
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- CN114123839A CN114123839A CN202111237683.9A CN202111237683A CN114123839A CN 114123839 A CN114123839 A CN 114123839A CN 202111237683 A CN202111237683 A CN 202111237683A CN 114123839 A CN114123839 A CN 114123839A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/66—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal
- H02M7/68—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters
- H02M7/72—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/79—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/797—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
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Abstract
The invention provides an isolated bidirectional alternating current-direct current conversion circuit and an isolated bidirectional alternating current-direct current conversion device, which comprise a first switch module, a second switch module and a switching module, wherein the second switch module is electrically connected between the first switch module and the switching module, and when the circuit is in a first conversion mode; when the circuit is in a second conversion mode, the switching module is used for switching the waveform of the alternating current power flow to obtain a power frequency alternating current power flow, the second switch module is used for converting the power frequency alternating current power flow into a high-frequency alternating current power flow, and the first switch module is used for converting the high-frequency alternating current power flow into a direct current power flow. Compared with the traditional isolated bidirectional AC/DC converter, the isolated bidirectional AC/DC converter does not need a bus capacitor, an inverter inductor and a high-frequency chopping switch tube, has simpler whole circuit composition and smaller available capacity, has higher conversion efficiency, and can prolong the service life of equipment in some application scenes.
Description
Technical Field
The invention relates to the technical field of power electronic converters, in particular to an isolated bidirectional alternating current-direct current conversion circuit and device.
Background
At present, with the development of micro-grid technology and energy storage technology, research on bidirectional ac/dc converter technology is receiving wide attention. The bidirectional AC/DC converter can be used for bidirectional conversion of AC voltage and DC voltage and can realize bidirectional flow of power flow at AC/DC side.
The existing isolated bidirectional AC/DC converter mainly comprises a two-stage converter. The two-stage converter structure is generally a one-stage isolation type DCDC conversion and a one-stage DCAC conversion, and in order to be suitable for high-frequency power flow, a high-frequency chopping switch tube is mostly adopted, and a bus capacitor and an inverter inductor are matched, so that the problem of complexity of the whole circuit structure is caused, and the problem of short service life caused by the use of the bus capacitor is solved.
Therefore, the prior art is to be improved.
Disclosure of Invention
The invention mainly aims to provide an isolated bidirectional alternating current-direct current conversion circuit and an isolated bidirectional alternating current-direct current conversion device, so as to at least solve the technical problem that the whole circuit structure of most of the existing two-stage converter structures is complex.
The invention provides an isolated bidirectional alternating current-direct current conversion circuit, which comprises a first switch module, a second switch module and a switching module, wherein the second switch module is electrically connected between the first switch module and the switching module;
when the circuit is in a first conversion mode, the first switch module is used for converting direct current power flow into high-frequency alternating current power flow, the second switch module is used for rectifying the high-frequency alternating current power flow into power frequency direct current power flow, and the switching module is used for switching the waveform of the power frequency direct current power flow to obtain alternating current power flow;
when the circuit is in a second conversion mode, the switching module is used for switching the waveform of the alternating current power flow to obtain a power frequency direct current power flow, the second switch module is used for converting the power frequency direct current power flow into a high-frequency alternating current power flow, and the first switch module is used for converting the high-frequency alternating current power flow into a direct current power flow.
In a second aspect of the present invention, an isolated bidirectional ac/dc converter is provided, which includes the isolated bidirectional ac/dc converter circuit of the first aspect.
The invention provides an isolated bidirectional AC-DC conversion circuit and device.A main body frame adopts a first switch module, a second switch module and a switching module, and the second switch module is electrically connected between the first switch module and the switching module. When the circuit is in a first conversion mode, the first switch module is used for converting the direct current power flow into high-frequency alternating current power flow, the second switch module is used for rectifying the high-frequency alternating current power flow to form direct current power flow, and the switching module is used for switching the waveform of the direct current power flow; when the circuit is in a second conversion mode, the switching module is used for switching the waveform of the alternating current power flow, the second switching module is used for converting the alternating current power flow into high-frequency alternating current power flow, and the first switching module is used for converting the high-frequency alternating current power flow into direct current power flow. Therefore, the invention is suitable for the bidirectional conversion of alternating current power current and direct current power current and can realize the bidirectional flow of the alternating current-direct current side power current. Compared with the traditional isolated bidirectional AC/DC converter, the isolated bidirectional AC/DC converter does not need a bus capacitor and an inverter inductor, and simultaneously does not need a high-frequency chopping switch tube, so that the whole circuit is simple in composition, the switch tube with smaller capacity can be used, and the cost is lower. Because the DCAC high-frequency chopping switch tube in the traditional isolated bidirectional AC-DC converter is not used, the conversion efficiency is improved on the basis of ensuring the simple composition of the whole circuit, and because the bus capacitor is not used, the service life of the equipment can be longer in some application scenes.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a schematic circuit diagram of a bidirectional AC/DC converter according to the related art;
fig. 2 is a schematic diagram of module connection of an isolated bidirectional ac-dc converter circuit according to a first embodiment of the present invention;
fig. 3 is a schematic diagram of module connection of an isolated bidirectional ac-dc converter circuit according to a second embodiment of the present invention;
fig. 4 is a schematic circuit connection diagram of an isolated bidirectional ac-dc converter circuit according to a third embodiment of the present invention;
FIG. 5 is a schematic circuit diagram of a first switching device according to the present invention;
FIG. 6 is a schematic circuit diagram of a second switching device according to the present invention;
FIG. 7 is a waveform diagram of the working timing sequence of the isolated bidirectional AC/DC converter circuit of the present invention in the first conversion mode;
FIG. 8 is a waveform diagram of the operation timing sequence of the isolated bidirectional AC/DC converter circuit in the second conversion mode according to the present invention;
fig. 9 is a schematic circuit connection diagram of an isolated bidirectional ac-dc converter circuit according to a fourth embodiment of the present invention;
fig. 10 is a schematic circuit connection diagram of an isolated bidirectional ac-dc converter circuit according to a fifth embodiment of the present invention;
FIG. 11 is a schematic circuit diagram of a power factor correction circuit according to the present invention applied to a three-phase AC scenario.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
It is noted that relative terms such as "first," "second," and the like may be used to describe various components, but these terms are not intended to limit the components. These terms are only used to distinguish one component from another component. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present invention. The term "and/or" refers to a combination of any one or more of the associated items and the descriptive items.
The following is an explanation of terms in the present application:
the high-frequency alternating current power flow refers to alternating current power flow with the frequency of more than 1 Khz;
the high-frequency direct current power flow refers to direct current power flow with the frequency of more than 1 Khz;
the power frequency alternating current power flow refers to alternating current power flow with the frequency below 1Khz, and the frequency is smaller than that of the high-frequency alternating current power flow;
the power frequency direct current power flow refers to direct current power flow with the frequency below 1Khz, and the frequency is smaller than that of high-frequency direct current power flow.
In the related art, a topology structure of a more commonly used isolated bidirectional converter is shown in fig. 1, which discloses a two-stage converter, and as can be seen from a topology structure diagram, DCDC conversion of a first stage of the converter mainly functions in isolation and voltage transformation, and the operation principle of the converter is to convert direct current from one side to high-frequency alternating current, transmit the high-frequency alternating current to the other side through a transformer and rectify the high-frequency alternating current into direct current, and the input side and the output side of the converter are both direct currents. The second-stage DCAC conversion mainly functions as AC-DC conversion, and the main working principle is to chop DC into high-frequency pulse and convert the high-frequency pulse into AC through a filter circuit or chop AC into high-frequency pulse and rectify and filter the high-frequency pulse into DC. Therefore, the conversion process is that direct current is converted into direct current and then converted into alternating current or alternating current is converted into direct current and then converted into direct current. The specific circuit configuration of the inverter uses a bus capacitor C _ bus, an inverter inductor L _ inv, and high-frequency chopper switching tubes Q11 and Q12, which causes problems of complicated circuit structure, high cost, and short service life.
In order to solve the above technical problem, the present invention provides an isolated bidirectional ac-dc conversion circuit, as shown in fig. 2, the circuit includes a first switch module 10, a second switch module 30 and a switching module 40, wherein the second switch module 30 is electrically connected between the first switch module 10 and the switching module 40.
The first switch module 10 is configured to convert a dc power stream into a high-frequency ac power stream or convert the high-frequency ac power stream into a dc power stream; the second switch module 30 is used for rectifying the high-frequency ac power flow or converting the ac power flow into a high-frequency ac power flow; the switching module 40 may switch the waveform of the power flow (the waveform of the direct current power flow or the waveform of the alternating current power flow). Specifically, the magnitude of the alternating current power flow is the product of alternating voltage and alternating current, and the alternating current power flow is alternating current electric power; the magnitude of the direct current power is the product of direct voltage and direct current, and the direct current power is direct current power.
The circuit comprises a first conversion mode and a second conversion mode, when the circuit is in the first conversion mode, the first switch module 10 is used for converting direct current power flow into high-frequency alternating current power flow, the second switch module 30 is used for rectifying the high-frequency alternating current power flow into power frequency direct current power flow, and the switching module 40 is used for switching the waveform of the power frequency direct current power flow to obtain alternating current power flow; when the circuit is in the second conversion mode, the switching module 40 is configured to switch a waveform of the ac power flow to obtain a power frequency ac power flow, the second switch module 30 is configured to convert the power frequency ac power flow into a high frequency ac power flow, and the first switch module 10 is configured to convert the high frequency ac power flow into a dc power flow.
When the circuit is in the first conversion mode, the first switch module 10, the second switch module 30 and the switching module 40 in the circuit are shown to execute work according to a first preset switch rule; when the circuit is in the second conversion mode, it indicates that the first switch module 10, the second switch module 30, and the switching module 40 in the circuit perform operations according to a second preset switch rule (the second preset switch rule is different from the first preset switch rule). Therefore, when the circuit is in the first conversion mode, the direct current power from the DC side is converted into the alternating current power through the first switch module 10, the second switch module 30 and the switch module 40 in sequence and then output from the AC side, and when the circuit is in the second conversion mode, the alternating current power from the AC side is converted into the direct current power through the switch module 40, the second switch module 30 and the first switch module 10 in sequence and then output from the DC side.
Therefore, the invention is suitable for the bidirectional conversion of alternating current power current and direct current power current and can realize the bidirectional flow of the alternating current-direct current side power current. Compared with the traditional isolated bidirectional AC/DC converter, the isolated bidirectional AC/DC converter does not need a bus capacitor and an inverter inductor, and simultaneously does not need a high-frequency chopping switch tube, so that the whole circuit is simple in composition, the switch tube with smaller capacity can be used, and the cost is lower. Because the DCAC high-frequency chopping switch tube in the traditional isolated bidirectional AC-DC converter is not provided, the conversion efficiency of the invention is higher, and because the bus capacitor is not provided, the service life of the equipment can be longer in some application scenes.
Fig. 3 shows a module connection diagram in an isolated bidirectional ac-dc conversion circuit according to a second embodiment of the present invention, the circuit further includes a first isolation module 20, the first isolation module 20 is electrically connected between the first switch module 10 and the second switch module 30, and the first isolation module 20 is used for isolating the first switch module from the second switch module. The first isolation module 20 has an isolation function, so that the output end and the input end are completely isolated in an open circuit manner, thereby ensuring the safety and reliability of the process of converting the alternating current power into the direct current power.
In this embodiment, the circuit further includes a first control module 50 and a second control module 70, the first control module 50 is electrically connected to the first switch module 10, and the second control module 70 is electrically connected to the second switch module 30 and the switching module 40.
When the circuit needs to convert the DC power flow into the ac power flow, the first control module 70 outputs a first control signal to the first switch module 10, the second control module 70 outputs a second control signal to the second switch module 30 and the switching module 40, the first control signal and the second control signal control the first switch module 10, the second switch module 30 and the switching module 40 to execute the operation according to the first preset switch rule, and then the DC power flow at the DC side sequentially passes through the first switch module 10, the second switch module 30 and the switching module 40 to be converted into the ac power flow.
When the circuit needs to convert an AC power stream into a dc power stream, the first control module 50 outputs a third control signal to the first switch module 10, the second control module 70 outputs a fourth control signal to the second switch module 30 and the switch module 40, the third control signal and the fourth control signal control the first switch module 10, the second switch module 30 and the switch module 40 to execute work according to a second preset switch rule, and then the AC power stream on the AC side sequentially passes through the switch module 40, the second switch module 30 and the first switch module 10 to be converted into the dc power stream.
Wherein, a second isolation module 60 can be disposed between the first control module 50 and the second control module 70, and the second isolation module can be one or a combination of an isolation chip and a transformer. The effect of isolating the control signal output by the first control module and the control signal output by the second control module can be achieved, and cross influence is avoided.
Fig. 4 shows a specific circuit connection diagram of an isolated bidirectional ac-dc converter circuit according to a third embodiment of the present invention. The first switching module includes a first switching device Q1, a second switching device Q2, a third switching device Q3, and a fourth switching device Q4. The first terminal of the first switching device Q1 is electrically connected to the first terminal of the second switching device Q2 and the first isolation module 20, the first terminal of the third switching device Q3 is electrically connected to the first terminal of the fourth switching device Q4 and the first isolation module 20, the second terminal of the first switching device Q1 is electrically connected to the second terminal of the third switching device Q3 and the positive DC + of the DC side, and the second terminal of the second switching device Q2 is electrically connected to the second terminal of the fourth switching device Q4 and the negative DC-of the DC side. That is, when the circuit is in the first conversion mode (the dc power stream needs to be converted into the ac power stream), the four switching devices perform work (control on time) according to the first preset switching rule, so that the dc power stream changes according to the sinusoidal rule, and the dc power stream is converted into the high-frequency ac power stream (the converted high-frequency ac power stream is transmitted to the first isolation module 20). And when the circuit is in a second conversion mode (the alternating current power flow needs to be converted into the direct current power flow), the four switching devices execute work (control on time) according to a second preset switching rule, and the high-frequency alternating current power flow is converted into the direct current power flow (the converted direct current power flow is output to a DC side).
Among them, MOS transistors are preferable for each of the switching devices (the first switching device Q1, the second switching device Q2, the third switching device Q3, and the fourth switching device Q4) in fig. 4. Of course, it is also possible for the first switching device Q1 to be a bidirectionally controllable power electronic device, such as a bidirectional switch. As shown in fig. 5, the first switching device Q1 includes a first MOS transistor and a second MOS transistor connected in series with the first MOS transistor. The first MOS transistor can be a first N-channel enhancement type MOS transistor N1, the second MOS transistor can be a second N-channel enhancement type MOS transistor N2, and the source electrode of the first N-channel enhancement type MOS transistor is connected with the drain electrode of the second N-channel enhancement type MOS transistor. The bidirectional switch is formed by connecting the double P-channel enhancement type MOS tubes in series, so that the technical effect of bidirectional control is achieved.
Specifically, a twelfth tube is connected between the source electrode of the first N-channel enhancement type MOS transistor and the drain electrode of the first N-channel enhancement type MOS transistor to provide a function of protecting the first N-channel enhancement type MOS transistor. An eleventh diode is connected between the source electrode of the second N-channel enhancement type MOS tube and the drain electrode of the second N-channel enhancement type MOS tube to provide a function of protecting the second N-channel enhancement type MOS tube.
Referring to fig. 4 again, the second switching module includes a fifth switching device Q5, a sixth switching device Q6, a seventh switching device Q7, and an eighth switching device Q8. The first terminal of the fifth switching device Q5 is electrically connected to the first isolation module 20, the second terminal of the fifth switching device Q5 is electrically connected to the first terminal of the sixth switching device Q6 and the switching module 40, the second terminal of the sixth switching device Q6 is electrically connected to the first isolation module 20, the first terminal of the seventh switching device Q7 is electrically connected to the first isolation module 20, the second terminal of the seventh switching device Q7 is electrically connected to the first terminal of the eighth switching device Q8 and the switching module 40, and the second terminal of the eighth switching device Q8 is electrically connected to the first isolation module 20. That is, when the circuit is in the first conversion mode (the dc power stream needs to be converted into the ac power stream), the four switching devices perform operation (on-time control) according to the first preset switching rule, so that the switching devices change according to the sinusoidal rule, and perform synchronous rectification processing on the high-frequency ac power stream (the high-frequency ac power stream is transmitted from the first isolation module 20). When the circuit is in the second conversion mode (the ac power stream needs to be converted into the dc power stream), the four switching devices execute the operation (control on-time) according to the second preset switching rule, and the ac power stream transmitted by the switching module 40 is converted into the high-frequency ac power stream and transmitted to the first isolation module 20.
As shown in fig. 6, the second switching device Q2 may include a first bipolar transistor and a second bipolar transistor connected in series with the first bipolar transistor. The first bipolar transistor may be a first insulated gate bipolar transistor E1, and the second bipolar transistor may be a second insulated gate bipolar transistor E2. The two insulated gate bipolar transistors are connected in series to form a bidirectional switch, so that the technical effect of bidirectional control is achieved. Specifically, a twelfth diode D12 is connected between the source of the first igbt E1 and the drain of the first igbt E1 to provide a function of protecting the first igbt E1. A thirteenth diode D13 is connected between the source of the second insulated gate bipolar transistor E2 and the drain of the second insulated gate bipolar transistor E2 to provide a function of protecting the second insulated gate bipolar transistor E2. Of course, in a preferred mode, the second switching device Q2 is preferably a MOS transistor.
Referring to fig. 4 again, the first isolation module 20 may be a resonance isolation module, which includes a first inductor Lm1, a second inductor Lm2, a third inductor Lr, a first capacitor Cr, and a transformer T. One end of the first inductance coil Lm1 is electrically connected to the first end of the first switching device Q1, the first end of the second switching device Q2, and one end of the first capacitor Cr, the other end of the first inductance coil Lm1 is electrically connected to the first end of the third switching device Q3, the first end of the fourth switching device Q4, and one end of the third inductance coil Lr, the other end of the first capacitor Cr is electrically connected to one end of the second inductance coil Lm2 and the same-name end of the first primary winding N1 in the transformer T, the other end of the second inductance coil N1 is electrically connected to the other end of the third inductance coil Lr and the different-name end of the first primary winding N1, the same-name end of the first winding N2 in the first secondary winding of the transformer T is electrically connected to the first end of the fifth switching device Q5, the different-name end of the second winding N3 in the first secondary winding N3 is electrically connected to the second end of the sixth switching device Q6, and the same-name end of the second secondary winding N4 in the transformer T is electrically connected to the second secondary winding Q7 And the synonym end of the fourth winding N5 in the second secondary winding is electrically connected with the second end of the eighth switching device Q8, and the common end of the first secondary winding is simultaneously electrically connected with the common end of the second secondary winding, the alternating current side N pole and the alternating current side L pole. The common end of the first secondary winding represents a junction (an end point formed by connection) formed by the different-name end of the first winding N2 and the same-name end of the second winding N3, and the common end of the second secondary winding represents a junction (an end point formed by connection) formed by the different-name end of the third winding N4 and the same-name end of the fourth winding N5. Namely, a resonant network is formed by the first inductance coil Lm1, the second inductance coil Lm2, the third inductance coil Lr and the first capacitance Cr, the resonant network is matched with an isolation function provided by the transformer T to realize isolation between a DC side and an AC side, and on the basis of a function of voltage transformation, the first switching device Q1, the second switching device Q2, the third switching device Q3, the fourth switching device Q4 on the DC side, the fifth switching device Q5, the sixth switching device Q6, the seventh switching device Q7 and the eighth switching device Q8 on the AC side are enabled to realize a soft switching function. And the resonant network can realize the soft switching of the first switch module and the second switch module simultaneously, and can effectively reduce the loss and the stress of the switch tube.
Referring again to fig. 4, the switching module 40 includes a ninth switching device Q9 and a tenth switching device Q10. A first terminal of the ninth switching device Q9 is electrically connected to the second terminal of the fifth switching device Q5, a second terminal of the ninth switching device Q9 is electrically connected to the first terminal of the tenth switching device Q10, the ac side N pole and the ac side L pole, and a second terminal of the tenth switching device Q10 is electrically connected to the second terminal of the seventh switching device Q7 and the first terminal of the eighth switching device Q8. That is, the switching module 40 switches the waveform of the dc power flow or the waveform of the ac power flow by matching the on/off states of the ninth switching device Q9 and the tenth switching device Q10.
It should be noted that, in the present application, each switching device may be connected in parallel with a corresponding protection device, for example, the protection device may be a diode, such as the first diode D1, the second diode D2 … …, and the ninth diode D9 in fig. 4.
When the circuit is in the first conversion mode, the working timing waveform of the circuit is as shown in fig. 7, and the working timing waveform comprises 6 stages in total, specifically as follows:
in the t0-t1 phase of the first conversion mode, the ninth switching device Q9 maintains the on state and the tenth switching device Q10 maintains the off state; the seventh switching device Q7 and the eighth switching device Q8 maintain an off state; namely, the corresponding working frequency fo when the Q1-Q4 work in the PWM mode in the t0-t1 stage of the first conversion mode; the first switching device Q1 and the fourth switching device Q4 are turned on and off at the same time, the second switching device Q2 and the third switching device Q3 are turned on and off at the same time, the second switching device Q2 is turned on after dead time Td passes after the first switching device Q1 is turned off, the duty ratios of the first switching device Q1 and the second switching device Q2 are kept consistent, the duty ratios are adjusted by closed loops, and the fifth switching device Q5 and the sixth switching device Q6 work in a synchronous rectification mode; at this stage, the energy on the DC side is transmitted to the AC side through the resonance isolation modules (Lm1, Lm2, Cr, Lr, T), and the soft switching function of the switching device is realized.
In the t1-t2 phase of the first conversion mode, the ninth switching device Q9 maintains the on state and the tenth switching device Q10 maintains the off state; the seventh switching device Q7 and the eighth switching device Q8 maintain an off state; Q1-Q4 operate in PFM mode with a duty cycle of
(Td denotes a dead time, and fs denotes an operating frequency corresponding to the operation of Q1-Q4 in the PFM mode at the t1-t2 stages of the first conversion mode); the first switching device Q1 and the fourth switching device Q4 are turned on and off simultaneously, the second switching device Q2 and the third switching device Q3 are turned on and off simultaneously, the second switching device Q2 is turned on after dead time Td passes after the first switching device Q1 is turned off, and the duty ratios of the first switching device Q1 and the second switching device Q2 are ensuredKeep consistent, the magnitude of its switching frequency is generated by closed-loop regulation, it is necessary to say fs<fo (different working frequencies in different stages), the fifth switching tube Q5 and the sixth switching device Q6 work in a synchronous rectification mode; at this stage, the energy on the DC side is transmitted to the AC side through the resonance isolation modules (Lm1, Lm2, Cr, Lr, T), and the soft switching function of the switching device is realized.
In the t2-t3 phase of the first conversion mode, the ninth switching device Q9 maintains the on state and the tenth switching device Q10 maintains the off state; the seventh switching device Q7 and the eighth switching device Q8 maintain an off state; Q1-Q4 operate in PWM mode at fo; the first switching device Q1 and the fourth switching device Q4 are turned on and off at the same time, the second switching device Q2 and the third switching device Q3 are turned on and off at the same time, the second switching device Q2 is turned on after dead time Td passes after the first switching device Q1 is turned off, the duty ratios of the first switching device Q1 and the second switching device Q2 are kept consistent, the duty ratios are adjusted by closed loops, and the fifth switching device Q5 and the sixth switching device Q6 work in a synchronous rectification mode; at this stage, the energy on the DC side is transmitted to the AC side through the resonance isolation modules (Lm1, Lm2, Cr, Lr, T), and the soft switching function of the switching device is realized.
In the t3-t4 phase of the first conversion mode, the ninth switching device Q9 maintains the off state and the tenth switching device Q10 maintains the on state; the fifth switching device Q5 and the sixth switching device Q6 maintain an off state; Q1-Q4 operate in PWM mode at fo; the first switching device Q1 and the fourth switching device Q4 are turned on and off at the same time, the second switching device Q2 and the third switching device Q3 are turned on and off at the same time, the second switching device Q2 is turned on after dead time Td passes after the first switching device Q1 is turned off, the duty ratios of the first switching device Q1 and the second switching device Q2 are kept consistent, the duty ratios are adjusted by closed loops, and the seventh switching device Q7 and the eighth switching device Q8 work in a synchronous rectification mode; at this stage, the energy on the DC side is transmitted to the AC side through the resonance isolation modules (Lm1, Lm2, Cr, Lr, T), and the soft switching function of the switching device is realized.
In the t4-t5 phase of the first conversion mode, the ninth switching device Q9 maintains the off state and the tenth switching device Q10 maintains the on state; the fifth switching device Q5 and the sixth switching device Q6 maintain an off state; Q1-Q4 are operated in PFM mode with duty cycle of; the first switching device Q1 and the fourth switching device Q4 are turned on and off at the same time, the second switching device Q2 and the third switching device Q3 are turned on and off at the same time, the second switching device Q2 is turned on after a dead time Td elapses after the first switching device Q1 is turned off, the duty ratios of the first switching device Q1 and the second switching device Q2 are kept consistent, the switching frequency is generated by closed-loop regulation, it is required to be noted that fs < fo, and the seventh switching device Q7 and the eighth switching device Q8 operate in a synchronous rectification mode; the DC side energy at this stage is transferred to the AC side through the first isolation module 20(Lm1, Lm2, Cr, Lr, T) and soft switching function of the switching device is realized.
In the t5-t6 phase of the first conversion mode, the ninth switching device Q9 maintains the off state and the tenth switching device Q10 maintains the on state; the fifth switching device Q5 and the sixth switching device Q6 maintain an off state; Q1-Q4 operate in PWM mode at fo; the first switching device Q1 and the fourth switching device Q4 are turned on and off at the same time, the second switching device Q2 and the third switching device Q3 are turned on and off at the same time, the second switching device Q2 is turned on after dead time Td passes after the first switching device Q1 is turned off, the duty ratios of the first switching device Q1 and the second switching device Q2 are kept consistent, the duty ratios are adjusted by closed loops, and the seventh switching device Q7 and the eighth switching device Q8 work in a synchronous rectification mode; the DC side energy at this stage is transmitted to the AC side through the resonance isolation modules (Lm1, Lm2, Cr, Lr, T), and the soft switching function of the switching tube is realized.
Wherein the driving pulse of the first switching device Q1 is identical in timing to the driving pulse of the fourth switching device Q4, the driving pulse of the second switching device Q2 is identical in timing to the driving pulse of the third switching device Q3, and the phase difference between the driving pulse of the first switching device Q1 and the driving pulse of the second switching device Q2 is 180 degrees. More specifically, the first switching device Q1 and the second switching device Q2 are complementarily conductive, the third switching device Q3 and the fourth switching device Q4 are complementarily conductive, and the first switching device Q1 and the third switching device Q3 are identically switched, so that the present circuit stably implements the first switching mode and the second switching mode in the process of controlling the first switching device Q1 and the second switching device Q2.
When the circuit is in the second conversion mode, the working timing waveform of the circuit is as shown in fig. 8, and the working timing waveform comprises 2 stages in total, specifically as follows:
in the t0-t1 phase of the second conversion mode, the ninth switching device Q9 maintains the on state and the tenth switching device Q10 maintains the off state; the seventh switching device Q7 and the eighth switching device Q8 maintain an off state; the fifth switching device Q5 and the sixth switching device Q6 work in PFM mode with duty ratio of
After the dead time Td passes after the fifth switching device Q5 is turned off, the sixth switching device Q6 is turned on, the duty ratios of the fifth switching device Q5 and the sixth switching device Q6 are kept consistent, the switching frequency is adjusted in a closed loop mode, and Q1-Q4 work in a synchronous rectification mode; at this stage, the energy on the AC side is transmitted to the DC side through the resonance isolation modules (Lm1, Lm2, Cr, Lr, T), and the soft switching function of the switching device is realized.
In the t1-t2 phase of the second conversion mode, the ninth switching device Q9 maintains the off state and the tenth switching device Q10 maintains the on state; the fifth switching device Q5 and the sixth switching device Q6 maintain an off state; the seventh switching device Q7 and the eighth switching device Q8 are operated in PFM mode with duty ratio of
After dead time Td passes after the seventh switching device Q7 is turned off, the eighth switching device Q8 is turned on, the duty ratios of the seventh switching device Q7 and the eighth switching device Q8 are kept consistent, the switching frequency is adjusted in a closed loop mode, and Q1-Q4 work in a synchronous rectification mode; at this stage, the energy on the AC side is transmitted to the DC side through the resonance isolation modules (Lm1, Lm2, Cr, Lr, T), and the soft switching function of the switching device is realized.
Referring to fig. 4, the circuit further includes an ac filtering module electrically connected between the DC-side positive electrode DC +, the DC-side negative electrode DC-and the first switch module 10, and the ac filtering module is configured to filter the high-frequency ac power stream into a power-frequency ac power stream. The alternating current filtering module may be a second electrode C _ DC, one end of the second electrode C _ DC is electrically connected to the DC side positive electrode DC +, the second end of the first switching device Q1, and the second end of the third switching device Q3, and the other end of the second electrode C _ DC is electrically connected to the DC side negative electrode DC-, the second end of the second switching device Q2, and the second end of the fourth switching device Q4.
Referring to fig. 4, the circuit further includes a dc filtering module electrically connected between the ac side N pole, the ac side L pole, the switching module 40, and the first isolation module 20, and the dc filtering module is configured to filter the high-frequency dc power into dc power. . Specifically, the dc filtering module may be a third capacitor C _ inv, one end of the third capacitor C _ inv is electrically connected to the ac side N pole, the common end of the first secondary winding, and the common end of the second secondary winding at the same time, and the other end of the third capacitor C _ inv is electrically connected to the ac side L pole, the ninth switching device Q9, and the tenth switching device Q10 at the same time.
It should be noted that in one embodiment, the circuit may include both the ac filtering module and the dc filtering module.
Fig. 9 is a schematic circuit connection diagram of an isolated bidirectional ac-dc converter circuit according to a fourth embodiment of the present invention, where the second switch module may be a full-bridge switch network composed of eight switch devices and a resonant isolation module, and is capable of transmitting a larger power flow.
Fig. 10 shows a circuit connection diagram of an isolated bidirectional ac-dc conversion circuit according to a fifth embodiment of the present invention, where the first isolation module 20 includes a second inductor Lm2, a third inductor Lr, and a transformer T, and forms a phase-shifting soft switching network.
Referring to fig. 11, the number of the circuits is three, and each circuit is a single-phase novel isolated bidirectional ac/dc converter, so that the three circuits can form a three-phase novel isolated bidirectional ac/dc converter. When the three circuits are in the first conversion mode, the direct current power flows through each circuit and is converted into three alternating current power flows, and when the three circuits are in the second conversion mode, the three alternating current power flows through each circuit and is converted into the direct current power flows. The three single-phase isolated bidirectional AC-DC conversion circuits form a three-phase isolated bidirectional AC-DC conversion circuit to be applied to a three-phase power scene.
The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (10)
1. An isolated bidirectional alternating current-direct current conversion circuit is characterized by comprising a first switch module, a second switch module and a switching module, wherein the second switch module is electrically connected between the first switch module and the switching module;
when the circuit is in a first conversion mode, the first switch module is used for converting direct current power flow into high-frequency alternating current power flow, the second switch module is used for rectifying the high-frequency alternating current power flow into power frequency direct current power flow, and the switching module is used for switching the waveform of the power frequency direct current power flow to obtain alternating current power flow;
when the circuit is in a second conversion mode, the switching module is used for switching the waveform of the alternating current power flow to obtain a power frequency alternating current power flow, the second switch module is used for converting the power frequency alternating current power flow into a high-frequency alternating current power flow, and the first switch module is used for converting the high-frequency alternating current power flow into a direct current power flow.
2. The isolated bidirectional AC-DC converter circuit of claim 1, further comprising a first isolation module electrically connected between said first switch module and said second switch module;
the first isolation module is used for isolating the first switch module from the second switch module.
3. The isolated bidirectional AC-DC converter circuit of claim 2, wherein said first switching module includes a first switching device, a second switching device, a third switching device, and a fourth switching device;
the first end of the first switch device is simultaneously electrically connected with the first end of the second switch device and the first isolation module, the first end of the third switch device is simultaneously electrically connected with the first end of the fourth switch device and the first isolation module, the second end of the first switch device is simultaneously electrically connected with the second end of the third switch device and the anode of the direct current side, and the second end of the second switch device is simultaneously electrically connected with the second end of the fourth switch device and the cathode of the direct current side.
4. The isolated bi-directional AC-DC conversion circuit of claim 3, wherein said second switching module comprises a fifth switching device, a sixth switching device, a seventh switching device, and an eighth switching device;
the first end of the fifth switching device is electrically connected with the first isolation module, the second end of the fifth switching device is simultaneously electrically connected with the first end of the sixth switching device and the switching module, the second end of the sixth switching device is electrically connected with the first isolation module, the first end of the seventh switching device is electrically connected with the first isolation module, the second end of the seventh switching device is simultaneously electrically connected with the first end of the eighth switching device and the switching module, and the second end of the eighth switching device is electrically connected with the first isolation module.
5. An isolated bidirectional AC-DC converter circuit according to claim 4, wherein said first isolation module is a resonance isolation module including a first inductor, a second inductor, a third inductor, a first capacitor and a transformer;
one end of the first inductance coil is electrically connected with the first end of the first switch device, the first end of the second switch device and one end of the first capacitor at the same time, the other end of the first inductance coil is electrically connected with the first end of the third switch device, the first end of the fourth switch device and one end of the third inductance coil at the same time, the other end of the first capacitor is electrically connected with one end of the second inductance coil and the dotted end of the first primary winding in the transformer, the other end of the second inductance coil is electrically connected with the other end of the third inductance coil and the dotted end of the first winding at the same time, the dotted end of the first winding in the first secondary winding of the transformer is electrically connected with the first end of the fifth switch device, and the dotted end of the second winding in the first secondary winding is electrically connected with the second end of the sixth switch device, the dotted terminal of the third winding in the second secondary winding of the transformer is electrically connected with the first terminal of the seventh switching device, the dotted terminal of the fourth winding in the second secondary winding is electrically connected with the second terminal of the eighth switching device, and the common terminal of the first secondary winding is electrically connected with the common terminal of the second secondary winding, the N pole of the alternating current side and the L pole of the alternating current side simultaneously.
6. The isolated bidirectional AC-DC converter circuit of claim 5, wherein said switching module includes a ninth switching device and a tenth switching device;
the first end of the ninth switching device is electrically connected with the second end of the fifth switching device, the second end of the ninth switching device is electrically connected with the first end of the tenth switching device, the alternating-current side N pole and the alternating-current side L pole, and the second end of the tenth switching device is electrically connected with the second end of the seventh switching device and the first end of the eighth switching device.
7. The isolated bidirectional ac-dc converter circuit of claim 2, further comprising a first control module electrically connected to said first switch module and a second control module electrically connected to said second switch module and said switching module.
8. An isolated bidirectional AC-DC converter circuit according to claim 1, further comprising an AC filter module and/or a DC filter module;
the alternating current filtering module is used for filtering high-frequency alternating current power flow into power frequency alternating current power flow;
the direct current filtering module is used for filtering the high-frequency direct current power into direct current power.
9. An isolated bidirectional AC-DC converter circuit as claimed in any one of claims 1 to 8, wherein the number of said circuits is three;
when the three circuits are all in the first conversion mode, the direct current power flows through each circuit and is converted into three alternating current power flows;
when the three circuits are all in the second conversion mode, the three alternating current powers are converted into direct current power after flowing through each circuit.
10. An isolated bidirectional ac-dc converter arrangement, comprising a circuit according to any of claims 1-9.
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| CN202111237683.9A CN114123839A (en) | 2021-10-22 | 2021-10-22 | Isolated bidirectional AC/DC conversion circuit and device |
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| CN111884535A (en) * | 2020-06-30 | 2020-11-03 | 西北工业大学 | High-frequency pulse alternating-current link inverter hybrid modulation strategy |
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| CN1489272A (en) * | 2002-10-08 | 2004-04-14 | 中国科学院电工研究所 | Phase-shift full-bridge high-frequency inverter based on DSP |
| CN109560711A (en) * | 2019-01-22 | 2019-04-02 | 山东大学 | A kind of isolation type bidirectional DC-DC converter and its modulator approach |
| CN111884535A (en) * | 2020-06-30 | 2020-11-03 | 西北工业大学 | High-frequency pulse alternating-current link inverter hybrid modulation strategy |
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