CN113364334A - Double-parallel Buck-Boost inverter and control method thereof - Google Patents
Double-parallel Buck-Boost inverter and control method thereof Download PDFInfo
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- CN113364334A CN113364334A CN202110796745.3A CN202110796745A CN113364334A CN 113364334 A CN113364334 A CN 113364334A CN 202110796745 A CN202110796745 A CN 202110796745A CN 113364334 A CN113364334 A CN 113364334A
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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
- H02M7/81—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 arranged for operation in parallel
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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
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac 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
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac 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
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac 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 with automatic control of output voltage or current, e.g. switching regulators
- H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac 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 with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
- H02M3/1584—Conversion of dc power input into dc power output without intermediate conversion into ac 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 with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load with a plurality of power processing stages connected in parallel
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Abstract
The invention discloses a double-parallel Buck-Boost inverter which comprises a direct current side port, a first staggered chopping unit, a first switch unit, a second staggered chopping unit, a second switch unit and an alternating current side port, wherein the first staggered chopping unit comprises a third switch unit, a fourth switch unit, a first one-way conduction device, a second one-way conduction device, a first energy storage element and a second energy storage element, and the second staggered chopping unit and the first chopping unit are the same in structure; the third switch unit, the reversely connected first one-way conduction device, the reversely connected second one-way conduction device and the fourth switch unit are sequentially connected, the third switch unit and the fourth switch unit are connected with the positive electrode of the direct current side port, and the positive electrodes of the first one-way conduction device and the second one-way conduction device are respectively connected with the negative electrode of the direct current side port through the first switch unit; the first energy storage element and the second energy storage element are respectively and correspondingly connected with the cathodes of the first one-way conduction device and the second one-way conduction device so as to improve the conversion efficiency.
Description
Technical Field
The invention relates to the technical field of inverters, in particular to a double-parallel Buck-Boost inverter and a control method thereof.
Background
An inverter is a converter that converts a voltage or a current input by a direct current into a voltage or a current output by an alternating current, and is widely used in a new energy power generation system, a power drive system, an alternating current uninterruptible power supply, induction heating, an active power filter, a static var compensator, and the like.
A topology of a conventional Voltage-source inverter (VSI) is shown in fig. 1. 4 switch tubes of the bridge arm are connected with diodes in an anti-parallel mode, so that the bridge arm has bidirectional current flowing and unidirectional voltage blocking capabilities. The disadvantages are that: on the one hand, a conventional Voltage Source Inverter (VSI) belongs to a buck converter, and outputs an ac voltage lower than a dc bus voltage. Therefore, for power conversion situations where the input direct-current voltage is low and the output of a high alternating-current voltage is needed, such as a new energy power generation system, an additional DC-DC boost converter needs to be added at the front stage of the inverter bridge to boost the bus voltage to be greater than the amplitude of the alternating-current output voltage so as to output a desired alternating-current voltage. The addition of a single power converter increases the cost of the system and reduces conversion efficiency and reliability. On the other hand, the switching tubes of the same bridge arm of the conventional voltage source inverter cannot be conducted at the same time, otherwise, a through short circuit occurs to damage the switching devices, so that the converter cannot work reliably. In order to prevent bridge arm from direct connection, a method of inserting dead zone is generally adopted, but the dead zone time causes increase of output harmonic voltage and complexity of control.
Disclosure of Invention
In order to solve the technical defects, the invention adopts a technical scheme that a double-parallel Buck-Boost inverter is provided, and the double-parallel Buck-Boost inverter comprises a direct current side port, a first staggered chopping unit, a first switch unit, a second staggered chopping unit, a second switch unit and an alternating current side port, wherein the first staggered chopping unit comprises a third switch unit, a fourth switch unit, a first one-way conduction device, a second one-way conduction device, a first energy storage element and a second energy storage element, and the second staggered chopping unit comprises a fifth switch unit, a sixth switch unit, a third one-way conduction device, a fourth one-way conduction device, a third energy storage element and a fourth energy storage element.
The third switch unit, the reversely connected first one-way conduction device, the reversely connected second one-way conduction device and the fourth switch unit are sequentially connected to form a first loop, the fifth switch unit, the reversely connected third one-way conduction device, the fourth one-way conduction device and the sixth switch unit are sequentially connected to form a second loop, the first end of the third switch unit, the first end of the fourth switch unit, the first end of the fifth switch unit and the first end of the sixth switch unit are respectively and electrically connected with the positive electrode of the DC side port, the positive electrode of the first one-way conduction device and the positive electrode of the second one-way conduction device are respectively and electrically connected with the negative electrode of the DC side port through the first switch unit, the positive electrode of the third one-way conduction device and the positive electrode of the fourth one-way conduction device are respectively and electrically connected with the negative electrode of the DC side port through the second switch unit, the first end of the first switch unit and the first end of the second switch unit are electrically connected with two ends of the alternating current port.
The first end part of the first energy storage element, the first end part of the second energy storage element, the first end part of the third energy storage element and the first end part of the fourth energy storage element are respectively and correspondingly electrically connected with the negative electrode of the first unidirectional conduction device, the negative electrode of the second unidirectional conduction device, the negative electrode of the third unidirectional conduction device and the negative electrode of the fourth unidirectional conduction device, and the second end part of the first energy storage element, the second end part of the second energy storage element, the second end part of the third energy storage element and the second end part of the fourth energy storage element are respectively and electrically connected with the negative electrode of the direct current side port and the joint of the first switch unit.
Further, the first switch unit, the second switch unit, the third switch unit, the fourth switch unit, the fifth switch unit and the sixth switch unit are bidirectional controllable switch elements, or two unidirectional controllable switch elements which are reversely connected in parallel and do not have a body diode, or two unidirectional controllable switch elements which are reversely connected in series and have a body diode.
Further, the first unidirectional conducting device, the second unidirectional conducting device, the third unidirectional conducting device and the fourth unidirectional conducting device are diodes or switching tubes.
Further, the first energy storage element, the second energy storage element, the third energy storage element and the fourth energy storage element are inductors.
Further, a direct-current power supply is arranged on the direct-current port, an alternating-current side filtering unit and an alternating-current side load are arranged on the alternating-current side port in parallel, two ends of the alternating-current side filtering unit are electrically connected with the first end portion of the first switch unit and the first end portion of the second switch unit respectively, and at the moment, the double-parallel Buck-Boost inverter works in an inversion mode.
Further, the dc side port is provided with a dc side filtering unit and a dc side load which are arranged in parallel, the ac side port is provided with an ac power source and ac side filtering units connected in parallel at two ends of the ac power source, a first end of the dc side filtering unit is electrically connected with the third switching unit, the fourth switching unit, the fifth switching unit and the sixth switching unit, a second end of the dc side filtering unit is electrically connected with a second end of the first inductor, two ends of the ac side filtering unit are electrically connected with a first end of the first switching unit and a first end of the second switching unit, respectively, and at this time, the double parallel Buck-Boost inverter operates in a rectification mode.
Further, the ac-side filter unit and the dc-side filter unit are filter capacitors, LC circuits, or LCL circuits.
The invention also provides a control method of the double parallel Buck-Boost inverter, which is suitable for controlling the double parallel Buck-Boost inverter and comprises the following steps:
applying driving signals with a phase difference of 180 degrees to a third switching unit and a fourth switching unit in the first interleaved chopping unit, and applying driving signals with a phase difference of 180 degrees to a fifth switching unit and a sixth switching unit in the second interleaved chopping unit;
in a power frequency period, the first interleaved chopping unit and the second interleaved chopping unit are enabled to alternately work in respective half periods;
the conduction duty ratios of the third switching unit, the fourth switching unit, the fifth switching unit and the sixth switching unit are controlled to change the conduction states of the first switching unit and the second switching unit, and the direct current side or the alternating current side is charged, so that the output alternating current voltage is higher than or lower than the direct current bus voltage.
Further, the double-parallel Buck-Boost inverter comprises the following 8 working modes in one power frequency cycle:
1) inversion mode a: in the positive half period of the alternating current side, the second staggered chopping unit works, and the third switching unit, the fourth switching unit, the second switching unit, the first one-way conducting device, the second one-way conducting device, the third one-way conducting device and the fourth one-way conducting device are disconnected; the fifth switch unit and the sixth switch unit are sequentially conducted, and the time interval is a 180-degree phase angle; the first switch unit is switched on or switched off, the direct current side charges and stores energy to the third energy storage element and the fourth energy storage element through the fifth switch unit and the sixth switch unit, and the alternating current side load is supplied with power by the alternating current side filtering unit;
2) inversion mode b: in the positive half period of the alternating current side, the second staggered chopping unit works, and the third switching unit, the fourth switching unit, the fifth switching unit, the sixth switching unit, the second switching unit, the first one-way conducting device and the second one-way conducting device are disconnected; the first switch unit, the third one-way conduction device and the fourth one-way conduction device are conducted; energy in the third energy storage element and the fourth energy storage element supplies follow current to the alternating current side through the first switch unit, the third one-way conduction device and the fourth one-way conduction device;
3) inversion mode c: in the negative half period of the alternating current side, the first staggered chopping unit works, and the fifth switching unit, the sixth switching unit, the first one-way conducting device, the second one-way conducting device, the third one-way conducting device and the fourth one-way conducting device are disconnected; the third switch unit and the fourth switch unit are sequentially conducted, and the time interval is 180-degree phase angle; the second switch unit is switched on or switched off, the direct current side charges and stores energy to the first energy storage element and the second energy storage element through the third switch unit and the fourth switch unit, and the alternating current side load is supplied with power by the alternating current side filtering unit;
4) inversion mode d: in the negative half period of the alternating current side, the first staggered chopping unit works, and the third switching unit, the fourth switching unit, the fifth switching unit, the sixth switching unit, the first switching unit, the third unidirectional conducting device and the fourth unidirectional conducting device are disconnected; the second switch unit, the first one-way conduction device and the second one-way conduction device are conducted; energy in the first energy storage element and the second energy storage element supplies follow current to the alternating current side through the second switch unit and the first one-way conduction device and the second one-way conduction device;
5) rectification mode a: in the positive half period of the alternating current side, the first staggered chopping unit works, and the third switching unit, the fourth switching unit, the fifth switching unit, the sixth switching unit, the first switching unit, the third unidirectional conducting device and the fourth unidirectional conducting device are disconnected; the second switch unit, the first one-way conduction device and the second one-way conduction device are conducted; the alternating current side charges and stores energy to the first energy storage element and the second energy storage element through the second switch unit, the first unidirectional conduction device and the second unidirectional conduction device, and the direct current side load is supplied with power by the direct current side filtering unit;
6) rectification mode b: in the positive half period of the alternating current side, the first staggered chopping unit works, and the fifth switch unit, the sixth switch unit, the first switch unit, the second switch unit, the first one-way conduction device, the second one-way conduction device, the third one-way conduction device and the fourth one-way conduction device are disconnected; the third switch unit and the fourth switch unit are sequentially conducted, and the time interval is 180-degree phase angle; the energy in the first energy storage element and the second energy storage element is supplied to the direct current side load through the third switching unit and the fourth switching unit, and meanwhile, the direct current side filtering unit is charged for energy storage;
7) rectification mode c: in the negative half period of the alternating current side, the second staggered chopping unit works, and the third switching unit, the fourth switching unit, the fifth switching unit, the sixth switching unit, the second switching unit, the first one-way conducting device and the second one-way conducting device are disconnected; the first switch unit, the third one-way conduction device and the fourth one-way conduction device are conducted; the alternating current side charges and stores energy to the third energy storage element and the fourth energy storage element through the first switch unit, the third unidirectional conduction device and the fourth unidirectional conduction device, and the direct current side load is supplied with power by the direct current side filtering unit;
8) rectification mode d: in the negative half period of the alternating current side, the second staggered chopping unit works, and the third switching unit, the fourth switching unit, the first switching unit, the second switching unit, the first one-way conduction device, the second one-way conduction device, the third one-way conduction device and the fourth one-way conduction device are disconnected; the fifth switch unit and the sixth switch unit are sequentially conducted, and the time interval is a 180-degree phase angle; the energy in the third energy storage element and the fourth energy storage element is supplied to the direct current side load through the fifth switching unit and the sixth switching unit, and meanwhile, the direct current side filtering unit is charged to store energy.
Compared with the prior art, the technical scheme of the invention has the beneficial effects that:
according to the double-parallel Buck-Boost inverter and the control method thereof, the two groups of Buck-Boost circuits which are connected in parallel in a staggered mode are arranged to form the staggered chopping unit, so that the voltage boosting or voltage reducing conversion of the inverter is realized, and any two switch units on the staggered chopping unit do not have the direct connection possibility through the reverse blocking effect of the one-way conduction device, so that the inverter can be conducted at the same time, and after an inductor is buffered in the charging and discharging processes, the direct connection danger of a bridge arm is avoided, the problems of output harmonic voltage increase and complex control caused by insertion of dead time are solved, and the bidirectional flow of energy is realized; the two staggered chopping units work alternately in a power frequency period, so that the switching frequency and the conversion efficiency are improved; under the same output inductive current ripple, only smaller inductance is needed, and the current stress and loss of the high-frequency switching tube can be reduced; an extra DC-DC boost converter is not needed to be added at the front stage of the inverter bridge, so that the cost of the system is reduced, the complexity of a circuit is reduced, and the conversion reliability is improved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a circuit schematic of a conventional bridge inverter;
fig. 2(a) is a schematic circuit diagram of a double parallel Buck-Boost inverter according to an embodiment of the present invention;
fig. 2(b) is a schematic circuit diagram of a double-parallel Buck-Boost inverter in an inversion mode according to an embodiment of the present invention;
fig. 2(c) is a schematic circuit diagram of a double-parallel Buck-Boost inverter in a rectification mode according to an embodiment of the present invention;
FIG. 3 is embodiment 1 of each switch unit provided by an embodiment of the present invention;
FIG. 4 is embodiment 2 of each switch unit provided by an embodiment of the present invention;
FIG. 5 is embodiment 3 of each switch unit provided by an embodiment of the present invention;
fig. 6 to 9 are schematic circuit diagrams of 4 operating modes of a double-parallel Buck-Boost inverter in an inversion mode according to an embodiment of the present invention;
fig. 10-13 are schematic circuit diagrams of 4 operating modes of a double-parallel Buck-Boost inverter in a rectification mode according to an embodiment of the present invention;
fig. 14(a) is a timing diagram of an inversion mode in a control method of a double parallel Buck-Boost inverter according to an embodiment of the present invention;
fig. 14(b) is a timing diagram of each switching period in the inversion mode in the control method of the double parallel Buck-Boost inverter according to the embodiment of the present invention;
fig. 14(c) is a table of correspondence between conduction states of the switching units and corresponding modes in the inversion mode in the control method of the double-parallel Buck-Boost inverter according to the embodiment of the present invention;
fig. 15(a) is a timing diagram of each switching period in the rectification mode in the control method of the double parallel Buck-Boost inverter according to the embodiment of the present invention;
fig. 15(b) is a table of correspondence between conduction states of the switching units and corresponding modes in the rectification mode in the control method of the double-parallel Buck-Boost inverter according to the embodiment of the present invention.
Detailed Description
The invention is further described with reference to the following figures and specific examples.
Example 1
Referring to fig. 2a, the double parallel Buck-Boost inverter provided by the present invention includes a dc side port a, a first interleaved chopper unit, and a first switch unit S1A second interleaved chopping unit, a second switching unit S2And an AC side port B, the first interleaved chopping unit including a third switching unit SaAnd a fourth switching unit SbThe first unidirectional conducting device, the second unidirectional conducting device, the first energy storage element and the second energy storage element are arranged on the first staggered chopping unit, and the second staggered chopping unit comprises a fifth switching unit ScThe sixth switching unit SdThe power supply comprises a first unidirectional conduction device, a second unidirectional conduction device, a third energy storage element and a fourth energy storage element.
Third switching unit SaA first one-way conducting device, a second one-way conducting device and a fourth switch unit S which are reversely connectedbSequentially connected to form a first loop, and a fifth switch unit ScA third one-way conducting device, a fourth one-way conducting device and a sixth switch unit S which are reversely connecteddSequentially connected to form a second loop and a third switch unit SaFirst end portion, fourth switching unit SbFirst end portion, fifth switch unit ScFirst end portion of (1), sixth switching unit SdIs respectively electrically connected with the positive electrode of the DC side port A, the positive electrode of the first unidirectional conducting device and the positive electrode of the second unidirectional conducting device are respectively connected with the positive electrode of the DC side port A through the first switch unit S1The anode of the third one-way conduction device and the anode of the fourth one-way conduction device are respectively connected with the cathode of the DC side port A through a second switch unit S2A first switch unit S electrically connected to the negative pole of the DC port A1First end portion, second switch unit S2Is electrically connected to both ends of the ac side port B.
A first end of the first energy storage element, a first end of the second energy storage element, a first end of the third energy storage element and a first end of the fourth energy storage elementOne end part is respectively and electrically connected with the cathode of the first unidirectional conduction device, the cathode of the second unidirectional conduction device, the cathode of the third unidirectional conduction device and the cathode of the fourth unidirectional conduction device in a one-to-one correspondence manner, and the second end part of the first energy storage element, the second end part of the second energy storage element, the second end part of the third energy storage element and the second end part of the fourth energy storage element are respectively and electrically connected with the cathode of the DC side port A and the first switch unit S1Are electrically connected.
Preferably, the first switching unit S1A second switch unit S2And a third switch unit SaAnd a fourth switching unit SbThe fifth switch unit ScAnd a sixth switching unit SdIs a bidirectional controllable switching element, or two unidirectional controllable switching elements which are connected in reverse parallel and are not provided with body diodes, or two unidirectional controllable switching elements which are connected in reverse series and are provided with body diodes.
The controllable switch element specifically uses a self-controlled forward-conducting device, such as an Insulated Gate Bipolar Transistor (IGBT), a Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET), and the like.
Wherein the first switch unit S1A second switch unit S2And a third switch unit SaAnd a fourth switching unit SbThe fifth switch unit ScAnd a sixth switching unit SdThe types of the two-way controllable switch can be the same or different, as long as the two-way controllable function can be realized.
The one-way controllable switching elements shown in fig. 3 are two anti-parallel controllable switching elements with unidirectional flow of power after conduction.
The one-way controllable switching elements shown in fig. 4 and 5 are two oppositely connected controllable switching elements with body diodes in series and with unidirectional flow of power after conduction.
Preferably, the first unidirectional conducting device, the second unidirectional conducting device, the third unidirectional conducting device and the fourth unidirectional conducting device are diodes or switching tubes. In particular diodes, which are in turn set as first diodes D for the convenience of description with reference to the figureaThe first stepTwo diodes DbA third diode DcA fourth diode Dd。
Preferably, the first energy storage element, the second energy storage element, the third energy storage element and the fourth energy storage element are inductors. For convenience of description, the first inductor L is specifically setaA second inductor LbA third inductor LcA fourth inductor Ld。
As shown in FIG. 2b, the DC port A is provided with a DC power supply VbusThe AC side port B is provided with an AC side filter unit and an AC side load which are connected in parallel, and two ends of the AC side filter unit are respectively connected with the first switch unit S1First end portion, second switch unit S2The first end of the double parallel Buck-Boost inverter is electrically connected, and the double parallel Buck-Boost inverter works in an inversion mode at the moment.
As shown in fig. 2c, the dc port a is provided with a dc filter unit and a dc load connected in parallel, and the ac port B is provided with an ac power supply VgAnd connected in parallel to an AC power supply VgAn AC side filter unit at both ends, a first end of the DC side filter unit and a third switch unit SaAnd a fourth switching unit SbThe fifth switch unit ScThe sixth switching unit SdElectrically connected to the second end of the DC-side filter unit and the first inductor LaThe second end of the AC side filter unit is electrically connected with the first switch unit S1First end portion, second switch unit S2The first end of the double parallel Buck-Boost inverter is electrically connected, and the double parallel Buck-Boost inverter works in a rectification mode at the moment.
Preferably, the ac-side filter unit and the dc-side filter unit are filter capacitors or LC circuits or LCL circuits. In particular, the filter capacitor is sequentially set as an AC side filter capacitor C for convenience of description of the corresponding diagramfDC side filter capacitor Cbus. DC power supply VbusThe power grid or alternating current motor input can be obtained through rectification and filtration, and can also be obtained through a photovoltaic cell, a fuel cell or a storage battery. The load on the AC side and the load on the DC side are load resistors, and are sequentially set as a load R for convenience of description of the corresponding diagramL1、RL2。
The chopper part consists of 4 identical Buck-Boost chopper circuits: third switching unit SaA first diode DaA first inductor LaForming a Buck-Boost 1; fourth switching unit SbA second diode DbA second inductor LbForming a Buck-Boost 2; fifth switching unit ScA third diode DcA third inductor LcForming a Buck-Boost 3; sixth switching unit SdA fourth diode DdA fourth inductor LdTo form Buck-Boost 4. Wherein, the third switching units S of Buck-Boost1 and Buck-Boost2aAnd a fourth switching unit SbThe difference of the trigger signals is 180 degrees, and a first staggered chopping unit is formed; fifth switching units S of Buck-Boost3 and Buck-Boost4cAnd a sixth switching unit SdBy 180 deg., constituting a second interleaved chopping unit. In a power frequency period, the first interleaving chopping unit and the second interleaving chopping unit alternately work in respective half periods.
First switch unit S1A second switch unit S2Forming a directional part, depending on the direction of the voltage measured by the alternating current, by adjusting the third switching unit SaAnd a fourth switching unit SbThe fifth switch unit ScThe sixth switching unit SdBy changing the first switching unit S1A second switch unit S2The on-state of the inverter realizes the voltage boosting inversion and the voltage reducing inversion, so that the output alternating voltage is higher than or lower than the direct current bus voltage.
Wherein the first switching unit S is shown in FIGS. 2, 6-131A second switch unit S2And a third switch unit SaAnd a fourth switching unit SbThe fifth switch unit ScAnd a sixth switching unit SdOnly illustrated as an ideal switch.
The invention provides a control method of a double-parallel Buck-Boost inverter, which is suitable for controlling the double-parallel Buck-Boost inverter and comprises the following steps:
for the third switch in the first interleaved chopping unitUnit SaAnd a fourth switching unit SbApplying drive signals with phase difference of 180 degrees to the fifth switching unit S in the second interleaved chopping unitcThe sixth switching unit SdDrive signals 180 degrees out of phase are applied.
In a power frequency period, the first interleaved chopping unit and the second interleaved chopping unit alternately work in respective half periods;
by controlling the third switching unit SaAnd a fourth switching unit SbThe fifth switch unit ScThe sixth switching unit SdBy changing the first switching unit S1A second switch unit S2The on state of (2) charges the dc side or the ac side to make the output ac voltage higher or lower than the dc bus voltage.
When charging the DC side, the AC power supply V is usedgWhen the AC side is charged, the DC power supply V supplies powerbusSupply power to change the first switching unit S1A second switch unit S2The direction of the current passing through.
Preferably, the double-parallel Buck-Boost inverter comprises the following 8 working modes in one power frequency cycle:
1) inversion mode a: in the positive half period of the AC side, the second interleaved chopper unit is operated, and the third switching unit SaAnd a fourth switching unit SbA second switch unit S2The first unidirectional conducting device, the second unidirectional conducting device, the third unidirectional conducting device and the fourth unidirectional conducting device are disconnected; fifth switching unit ScThe sixth switching unit SdConducting successively and the time interval is 180 degrees phase angle; first switch unit S1On or off, the DC side passes through the fifth switch unit ScThe sixth switching unit SdAnd the third energy storage element and the fourth energy storage element are charged to store energy, and the alternating current side load is supplied with power by the alternating current side filtering unit. To reduce losses, the first switching unit S is here designed1And conducting.
2) Inversion mode b: in the positive half period of the AC side, the second interleaved chopper unit is operated, and the third switching unit SaAnd a fourth switching unit SbThe fifth switch unit ScThe sixth switching unit SdA second switch unit S2The first unidirectional conducting device and the second unidirectional conducting device are disconnected; first switch unit S1The third one-way conduction device and the fourth one-way conduction device are conducted; the energy in the third energy storage element and the fourth energy storage element passes through the first switch unit S1And the third unidirectional conducting device and the fourth unidirectional conducting device supply follow current to the alternating current side.
3) Inversion mode c: in the negative half period of the AC side, the first interleaved chopping unit is operated, and the fifth switching unit ScThe sixth switching unit SdA first switch unit S1The first unidirectional conducting device, the second unidirectional conducting device, the third unidirectional conducting device and the fourth unidirectional conducting device are disconnected; third switching unit SaAnd a fourth switching unit SbConducting successively and the time interval is 180 degrees phase angle; second switch unit S2On or off, the DC side is through the third switch unit SaAnd a fourth switching unit SbAnd the first energy storage element and the second energy storage element are charged to store energy, and the alternating current side load is supplied with power by the alternating current side filtering unit. To reduce losses, the second switching unit S is here designed2And conducting.
4) Inversion mode d: in the negative half period of the AC side, the first interleaved chopping unit is operated, and the third switching unit SaAnd a fourth switching unit SbThe fifth switch unit ScThe sixth switching unit SdA first switch unit S1The third unidirectional conducting device and the fourth unidirectional conducting device are disconnected; second switch unit S2The first one-way conduction device and the second one-way conduction device are conducted; the energy in the first energy storage element and the second energy storage element passes through the second switch unit S2The first unidirectional conducting device and the second unidirectional conducting device supply follow current to the alternating current side;
5) rectification mode a: in the positive half period of the AC side, the first interleaved chopping unit is operated, and the third switching unit SaAnd a fourth switching unit SbThe fifth switch unit ScThe sixth switching unit SdA first switch unit S1The third unidirectional conducting device and the fourth unidirectional conducting device are disconnected; second switch unit S2The first one-way conduction device and the second one-way conduction device are conducted; the AC side passes through the second switch unit S2The first one-way conduction device and the second one-way conduction device charge and store energy to the first energy storage element and the second energy storage element, and the direct current side load is supplied with power by the direct current side filtering unit.
6) Rectification mode b: in the positive half period of the AC side, the first interleaved chopping unit is operated, and the fifth switching unit ScThe sixth switching unit SdA first switch unit S1A second switch unit S2The first unidirectional conducting device, the second unidirectional conducting device, the third unidirectional conducting device and the fourth unidirectional conducting device are disconnected; third switching unit SaAnd a fourth switching unit SbConducting successively and the time interval is 180 degrees phase angle; the energy in the first energy storage element and the second energy storage element passes through the third switch unit SaAnd a fourth switching unit SbAnd supplying power to a direct current side load, and simultaneously charging and storing energy to a direct current side filtering unit.
7) Rectification mode c: in the negative half period of the AC side, the second interleaved chopping unit is operated, and the third switching unit SaAnd a fourth switching unit SbThe fifth switch unit ScThe sixth switching unit SdA second switch unit S2The first unidirectional conducting device and the second unidirectional conducting device are disconnected; first switch unit S1The third one-way conduction device and the fourth one-way conduction device are conducted; the AC side passes through the first switch unit S1The third unidirectional conduction device and the fourth unidirectional conduction device charge and store energy for the third energy storage element and the fourth energy storage element, and the direct current side load is supplied with power by the direct current side filtering unit.
8) Rectification mode d: in the negative half period of the AC side, the second interleaved chopping unit is operated, and the third switching unit SaAnd a fourth switching unit SbA first switch unit S1A second switch unit S2A first one-way conduction device, a second one-way conduction device, a third one-way conduction device and a fourth one-way conduction deviceTurning off to the conducting device; fifth switching unit ScThe sixth switching unit SdConducting successively and the time interval is 180 degrees phase angle; the energy in the third energy storage element and the fourth energy storage element passes through a fifth switch unit ScThe sixth switching unit SdAnd supplying power to a direct current side load, and simultaneously charging and storing energy to a direct current side filtering unit.
As can be seen from the above, in the inverter mode, the circuit mode can be divided into 4 modes according to the operation conditions of the first interleaved chopper unit and the second interleaved chopper unit, and fig. 6 to 9 are equivalent circuits of the 4 modes in the inverter mode. The corresponding relationship between the conducting state of each switch unit and the corresponding mode is shown in fig. 14 c.
In FIG. 14c, Sa、Sb、Sc、Sd、S1、S2Representing that the corresponding switch is in a conducting state,
representing that the corresponding switch is in an off state, the modality labeled "\" and the unlisted modality both represent that the modality is an invalid modality.
When the circuit works in an inversion mode, the alternating current side can output voltages with different polarities (positive and negative) by controlling the conducting states of the first switch unit S1 and the second switch unit S2. The second switching unit S2 is not operated during the ac side positive half period, and the first switching unit S1 is not operated during the ac side negative half period.
As can be seen from the above, in the rectification mode, the circuit mode can be divided into 4 modes according to the operation conditions of the first interleaved chopping unit and the second interleaved chopping unit, and fig. 10 to 13 are equivalent circuits of the 4 modes in the rectification mode. The corresponding relationship between the conduction state of each switch unit and the corresponding mode is shown in fig. 15 b.
In FIG. 15b, Sa、Sb、Sc、Sd、S1、S2Representing that the corresponding switch is in a conducting state,
representing that the corresponding switch is in an off state, the modality labeled "\" and the unlisted modality both represent that the modality is an invalid modality.
When the circuit operates in the rectification mode, the on states of the first switch unit S1 and the second switch unit S2 are determined according to the polarities (positive and negative) of the ac side voltage. The first switching unit S1 is not operated during the ac side positive half period, and the second switching unit S2 is not operated during the ac side negative half period.
In order to simplify the difficulty of analyzing the working mode of the double Buck-Boost inverter, the following assumptions are provided: all devices in the circuit are ideal models, namely: the switch unit and the diode can be switched on or off instantly, and have no conducting voltage drop (the resistance is 0 when the switch unit and the diode are switched on) and no leakage current when the switch unit and the diode are switched off; the inductor works in a linear region without saturation, and the parasitic resistance is zero; the equivalent series resistance of the capacitor is zero; filter capacitor CfAnd a filter capacitor CbusIs sufficiently large to flow through the filter capacitor CfAnd a filter capacitor CbusIs approximately 0; and thirdly, the circuits are all in a stable state of operation.
The drive signal is analyzed with a square wave as an example, that is: the driving signal of each switch unit is a square wave sequence with fixed pulse width. When the driving signal of each of the switching units Sa, Sb, Sc, Sd is a PWM wave, the driving principle is basically the same as the square wave driving principle, and thus the driving signal is not limited to a square wave but may be a PWM wave.
In the inverter mode, the operating mode of the circuit can be divided into a Continuous Conduction Mode (CCM) and a Discontinuous Conduction Mode (DCM) according to whether the current flowing through the inductors La, Lb, Lc, and Ld is reduced to zero or not. The two work processes are generally similar, in the DCM mode, the current of each inductor La, Lb, Lc, Ld can be reduced to zero, but the CCM mode does not have such a condition, and the CCM mode is taken as an example in the subsequent analysis.
In the inversion mode, when the duty ratio of each switching unit is greater than 50%, the switching units Sa, Sb, Sc, and Sd may be simultaneously turned on, and when the duty ratio of each switching unit is less than 50%, this does not happen, and since the duty ratio of the driving signal greater than 50% affects the analysis process, the duty ratio of each switching unit less than 50% is taken as an example for explanation.
Waveform analysis in inversion mode
As shown in fig. 14a, Tg is the ac side voltage period and Ts is the switching period. In the inverter mode, to realize grid connection, the working cycles of the first switch unit S1 and the second switch unit S2 are consistent with the cycle of the alternating-current side voltage. In the positive half period of the alternating current side, the first switch unit S1 is turned on, and the fifth switch unit Sc and the sixth switch unit Sd are conducted in a staggered mode; in the negative half period on the ac side, the second switching unit S2 is turned on, and the third switching unit Sa and the fourth switching unit Sb are turned on alternately.
Further analysis is made on a certain switching period of the positive half period of the ac side in fig. 14a, the timing chart and the related waveforms are as shown in fig. 14b, and in a switching period, the duty ratios of the fifth switching unit Sc and the sixth switching unit Sd are the same and the phase difference is 180 °.
From FIG. 14b, it can be seen that: in a switching period, the circuit can be divided into four conditions, and in a half period of the alternating current side, the four conditions of the circuit appear in sequence and are circulated. Of the four cases, cases 1 and 3 belong to modality a, and cases 2 and 4 belong to modality b. Four cases will now be described in detail:
(1) stage 1 (t 0-t 1): the fifth switch unit Sc is triggered to be conducted, the terminal voltage of the fifth switch unit Sc is reduced to 0, and the current iSc flowing through the fifth switch unit Sc is the same as the current iLc of the third inductor Lc; the sixth switching element Sd is turned off, its terminal voltage is Vbus + V0, and the current flowing through the sixth switching element Sd is 0. The direct-current power supply Vbus charges and stores energy to the third inductor Lc, the inductor voltage vLc is constant Vbus, and the inductor current iLc rises; fourth inductance Ld to load RL1When power is supplied, the inductor voltage vLd is constant at-V0, and the inductor current iLd is reduced. The third diode Dc is turned off by a reverse voltage of Vbus + V0, and its current iDc is 0; the fourth diode Dd conducts a freewheeling current with a terminal voltage vDd of 0 and a current iDd equal to the inductor current iLd.
(2) Stage 2 (t 1-t 2): the fifth switching unit Sc and the sixth switching unit Sd are both turned off, the terminal voltages thereof are Vbus + V0, and the currents flowing through the switching units are both 0. The third inductor Lc and the fourth inductor Ld simultaneously supply power to the load RL1When power is supplied, the voltage of the two inductors is constant to be-V0, and the current of the inductors is reduced. The third diode Dc and the fourth diode Dd conduct freewheeling, the terminal voltages of which are both 0, and the current is the same as the corresponding inductor current.
(3) Stage 3 (t 2-t 3): triggering and conducting the sixth switching unit Sd, wherein the terminal voltage of the sixth switching unit Sd is reduced to 0, and the current iSd flowing through the sixth switching unit Sd is the same as the current iLd of the fourth inductor Ld; the fifth switching unit Sc is turned off, its terminal voltage is Vbus + V0, and the current flowing through the fifth switching unit Sc is 0. The direct-current power supply Vbus charges and stores energy to the fourth inductor Ld, the inductor voltage vLd is constant Vbus, and the inductor current iLd rises; third inductance Lc to load RL1When power is supplied, the inductor voltage vLc is constant at-V0, and the inductor current iLc drops. The fourth diode Dd is turned off by a reverse voltage of Vbus + V0, and its current iDd is 0; the third diode Dc conducts a freewheeling current with a terminal voltage vDc of 0 and a current iDc equal to inductor current iLc.
(4) Stage 4 (t 3-t 4): the fifth switching unit Sc and the sixth switching unit Sd are both turned off, the terminal voltages thereof are Vbus + V0, and the currents flowing through the switching units are both 0. The third inductor Lc and the fourth inductor Ld simultaneously supply power to the load RL1When power is supplied, the voltage of the two inductors is constant to be-V0, and the current of the inductors is reduced. The third diode Dc and the fourth diode Dd conduct freewheeling, the terminal voltages of which are both 0, and the current is the same as the corresponding inductor current.
As can be seen from the above analysis, the ripple amount of the total current obtained by superimposing the currents iclc and iLd in the two sets of interleaved chopping units, i.e., the ripple amount of the load current in fig. 14b, is lower than the ripple amount of the current of any one set of branches, i.e., the ripple amount of the current iLc or iLd. This will help to reduce the inductance requirement of the circuit, reduce the circuit volume, and improve the power density.
For the negative half period of the AC side, the analysis method is similar to that described above and is not described in detail.
Waveform analysis in rectification mode
As shown in fig. 15a, Ts is the switching period. In the rectification mode, the third switching unit Sa, the fourth switching unit Sb, and the second switching unit S2 operate in the ac-side positive half cycle, and the fifth switching unit Sc, the sixth switching unit Sd, and the first switching unit S1 operate in the ac-side negative half cycle. Fig. 15a only takes a certain switching period during the positive half period of the ac side as an example for analysis, and the analysis method is similar for the negative half period of the ac side and is not repeated.
As can be seen from fig. 15a, the circuit can be divided into two cases in one switching period, and the two cases of the circuit occur in sequence in half the period of the ac side, and cycle back and forth. Two cases will now be described in detail:
(1) stage 1 (t 0-t 1): the second switch unit S2 iS triggered to turn on, the terminal voltage thereof drops to 0, and the current iS2 flowing through the second switch unit S2 iS the sum of the current iLa of the first inductor La and the current iLb of the second inductor Lb; the third switching unit Sa and the fourth switching unit Sb are turned off, the terminal voltages thereof are Vbus + Vg, and the currents flowing through the third switching unit Sa and the fourth switching unit Sb are 0. The alternating current power supply Vg charges the first inductor La and the second inductor Lb for energy storage, the inductor voltages vLa and vLb are the same as the alternating current power supply voltage Vg, and the inductor currents iLa and iLb rise. The first diode Da and the second diode Db conduct and freewheel, the terminal voltages vDa and vDb are 0, and the currents iDa and iDb are the same as the inductor currents iLa and iLb.
(2) Stage 2 (t 1-t 2): the second switch unit S2 is turned off, and its terminal voltage is- (Vbus + V0), and the current flowing through the second switch unit S2 is 0; the third switching unit Sa and the fourth switching unit Sb are triggered to be turned on, the terminal voltages thereof are both 0, and the current flowing through the third switching unit Sa and the fourth switching unit Sb is the same as the inductive currents iLa and iLb. The first inductor La and the second inductor Lb simultaneously supply power to the load RL2When power is supplied, the voltage of the two inductors is constant to be-Vbus, and the current of the inductor is reduced. The first diode Da and the second diode Db are turned off due to no current loop, and both the terminal voltages are 0 and the currents are 0.
The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may occur to those skilled in the art without departing from the principle of the invention, and are considered to be within the scope of the invention.
Claims (9)
1. A double parallel Buck-Boost inverter is characterized in that: the energy-saving device comprises a direct-current side port, a first staggered chopping unit, a first switch unit, a second staggered chopping unit, a second switch unit and an alternating-current side port, wherein the first staggered chopping unit comprises a third switch unit, a fourth switch unit, a first one-way conduction device, a second one-way conduction device, a first energy storage element and a second energy storage element;
the third switch unit, the reversely connected first one-way conduction device, the reversely connected second one-way conduction device and the fourth switch unit are sequentially connected to form a first loop, the fifth switch unit, the reversely connected third one-way conduction device, the fourth one-way conduction device and the sixth switch unit are sequentially connected to form a second loop, the first end of the third switch unit, the first end of the fourth switch unit, the first end of the fifth switch unit and the first end of the sixth switch unit are respectively and electrically connected with the positive electrode of the DC side port, the positive electrode of the first one-way conduction device and the positive electrode of the second one-way conduction device are respectively and electrically connected with the negative electrode of the DC side port through the first switch unit, the positive electrode of the third one-way conduction device and the positive electrode of the fourth one-way conduction device are respectively and electrically connected with the negative electrode of the DC side port through the second switch unit, the first end part of the first switch unit and the first end part of the second switch unit are electrically connected with two ends of the alternating current side port;
the first end part of the first energy storage element, the first end part of the second energy storage element, the first end part of the third energy storage element and the first end part of the fourth energy storage element are respectively and correspondingly electrically connected with the negative electrode of the first unidirectional conduction device, the negative electrode of the second unidirectional conduction device, the negative electrode of the third unidirectional conduction device and the negative electrode of the fourth unidirectional conduction device, and the second end part of the first energy storage element, the second end part of the second energy storage element, the second end part of the third energy storage element and the second end part of the fourth energy storage element are respectively and electrically connected with the negative electrode of the direct current side port and the joint of the first switch unit.
2. The double parallel Buck-Boost inverter of claim 1, wherein: the first switch unit, the second switch unit, the third switch unit, the fourth switch unit, the fifth switch unit and the sixth switch unit are bidirectional controllable switch elements, or two unidirectional controllable switch elements which are reversely connected in parallel and are not provided with body diodes, or two unidirectional controllable switch elements which are reversely connected in series and are provided with body diodes.
3. The double parallel Buck-Boost inverter of claim 1 or 2, wherein: the first one-way conduction device, the second one-way conduction device, the third one-way conduction device and the fourth one-way conduction device are diodes or switching tubes.
4. The double parallel Buck-Boost inverter of claim 1 or 2, wherein: the first energy storage element, the second energy storage element, the third energy storage element and the fourth energy storage element are inductors.
5. The double parallel Buck-Boost inverter of claim 1 or 2, wherein: the direct current side port is provided with a direct current power supply, the alternating current side port is provided with an alternating current side filtering unit and an alternating current side load which are connected in parallel, two ends of the alternating current side filtering unit are respectively and electrically connected with the first end part of the first switch unit and the first end part of the second switch unit, and at the moment, the double parallel Buck-Boost inverter works in an inversion mode.
6. The double parallel Buck-Boost inverter of claim 5, wherein: the direct current side port is provided with a direct current side filtering unit and a direct current side load which are connected in parallel, the alternating current side port is provided with an alternating current power supply and alternating current side filtering units which are connected at two ends of the alternating current power supply in parallel, a first end portion of the direct current side filtering unit is electrically connected with a third switch unit, a fourth switch unit, a fifth switch unit and a sixth switch unit, a second end portion of the direct current side filtering unit is electrically connected with a second end portion of a first inductor, two ends of the alternating current side filtering unit are respectively electrically connected with a first end portion of the first switch unit and a first end portion of the second switch unit, and at the moment, the double parallel Buck-Boost inverter works in a rectification mode.
7. The double parallel Buck-Boost inverter of claim 6, wherein: the alternating current side filter unit and the direct current side filter unit are filter capacitors or LC circuits or LCL circuits.
8. A method for controlling a double-parallel Buck-Boost inverter, which is suitable for controlling the double-parallel Buck-Boost inverter according to any one of claims 1 to 7, and is characterized by comprising the following steps:
applying driving signals with a phase difference of 180 degrees to a third switching unit and a fourth switching unit in the first interleaved chopping unit, and applying driving signals with a phase difference of 180 degrees to a fifth switching unit and a sixth switching unit in the second interleaved chopping unit;
in a power frequency period, the first interleaved chopping unit and the second interleaved chopping unit are enabled to alternately work in respective half periods;
the conduction duty ratios of the third switching unit, the fourth switching unit, the fifth switching unit and the sixth switching unit are controlled to change the conduction states of the first switching unit and the second switching unit, and the direct current side or the alternating current side is charged, so that the output alternating current voltage is higher than or lower than the direct current bus voltage.
9. The method for controlling the double-parallel Buck-Boost inverter according to claim 8, wherein the double-parallel Buck-Boost inverter comprises the following 8 working modes in one power frequency cycle:
1) inversion mode a: in the positive half period of the alternating current side, the second staggered chopping unit works, and the third switching unit, the fourth switching unit, the second switching unit, the first one-way conducting device, the second one-way conducting device, the third one-way conducting device and the fourth one-way conducting device are disconnected; the fifth switch unit and the sixth switch unit are sequentially conducted, and the time interval is a 180-degree phase angle; the first switch unit is switched on or switched off, the direct current side charges and stores energy to the third energy storage element and the fourth energy storage element through the fifth switch unit and the sixth switch unit, and the alternating current side load is supplied with power by the alternating current side filtering unit;
2) inversion mode b: in the positive half period of the alternating current side, the second staggered chopping unit works, and the third switching unit, the fourth switching unit, the fifth switching unit, the sixth switching unit, the second switching unit, the first one-way conducting device and the second one-way conducting device are disconnected; the first switch unit, the third one-way conduction device and the fourth one-way conduction device are conducted; energy in the third energy storage element and the fourth energy storage element supplies follow current to the alternating current side through the first switch unit, the third one-way conduction device and the fourth one-way conduction device;
3) inversion mode c: in the negative half period of the alternating current side, the first staggered chopping unit works, and the fifth switching unit, the sixth switching unit, the first one-way conducting device, the second one-way conducting device, the third one-way conducting device and the fourth one-way conducting device are disconnected; the third switch unit and the fourth switch unit are sequentially conducted, and the time interval is 180-degree phase angle; the second switch unit is switched on or switched off, the direct current side charges and stores energy to the first energy storage element and the second energy storage element through the third switch unit and the fourth switch unit, and the alternating current side load is supplied with power by the alternating current side filtering unit;
4) inversion mode d: in the negative half period of the alternating current side, the first staggered chopping unit works, and the third switching unit, the fourth switching unit, the fifth switching unit, the sixth switching unit, the first switching unit, the third unidirectional conducting device and the fourth unidirectional conducting device are disconnected; the second switch unit, the first one-way conduction device and the second one-way conduction device are conducted; energy in the first energy storage element and the second energy storage element supplies follow current to the alternating current side through the second switch unit and the first one-way conduction device and the second one-way conduction device;
5) rectification mode a: in the positive half period of the alternating current side, the first staggered chopping unit works, and the third switching unit, the fourth switching unit, the fifth switching unit, the sixth switching unit, the first switching unit, the third unidirectional conducting device and the fourth unidirectional conducting device are disconnected; the second switch unit, the first one-way conduction device and the second one-way conduction device are conducted; the alternating current side charges and stores energy to the first energy storage element and the second energy storage element through the second switch unit, the first unidirectional conduction device and the second unidirectional conduction device, and the direct current side load is supplied with power by the direct current side filtering unit;
6) rectification mode b: in the positive half period of the alternating current side, the first staggered chopping unit works, and the fifth switch unit, the sixth switch unit, the first switch unit, the second switch unit, the first one-way conduction device, the second one-way conduction device, the third one-way conduction device and the fourth one-way conduction device are disconnected; the third switch unit and the fourth switch unit are sequentially conducted, and the time interval is 180-degree phase angle; the energy in the first energy storage element and the second energy storage element is supplied to the direct current side load through the third switching unit and the fourth switching unit, and meanwhile, the direct current side filtering unit is charged for energy storage;
7) rectification mode c: in the negative half period of the alternating current side, the second staggered chopping unit works, and the third switching unit, the fourth switching unit, the fifth switching unit, the sixth switching unit, the second switching unit, the first one-way conducting device and the second one-way conducting device are disconnected; the first switch unit, the third one-way conduction device and the fourth one-way conduction device are conducted; the alternating current side charges and stores energy to the third energy storage element and the fourth energy storage element through the first switch unit, the third unidirectional conduction device and the fourth unidirectional conduction device, and the direct current side load is supplied with power by the direct current side filtering unit;
8) rectification mode d: in the negative half period of the alternating current side, the second staggered chopping unit works, and the third switching unit, the fourth switching unit, the first switching unit, the second switching unit, the first one-way conduction device, the second one-way conduction device, the third one-way conduction device and the fourth one-way conduction device are disconnected; the fifth switch unit and the sixth switch unit are sequentially conducted, and the time interval is a 180-degree phase angle; the energy in the third energy storage element and the fourth energy storage element is supplied to the direct current side load through the fifth switching unit and the sixth switching unit, and meanwhile, the direct current side filtering unit is charged to store energy.
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|---|---|---|---|---|
| WO2024078318A1 (en) * | 2022-10-14 | 2024-04-18 | 华为数字能源技术有限公司 | Direct-current conversion circuit and photovoltaic inverter |
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| CN113364334B (en) | 2024-06-18 |
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