CN112701913A - Boost power conversion circuit and control method and application device thereof - Google Patents
Boost power conversion circuit and control method and application device thereof Download PDFInfo
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- CN112701913A CN112701913A CN201911005659.5A CN201911005659A CN112701913A CN 112701913 A CN112701913 A CN 112701913A CN 201911005659 A CN201911005659 A CN 201911005659A CN 112701913 A CN112701913 A CN 112701913A
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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
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
Abstract
The invention provides a boost power conversion circuit and a control method and an application device thereof, which are applied to the technical field of photovoltaic power generation.A circuit is provided with one or more switches at a specified position, the switches are closed when meeting a preset closing condition, or are opened when not meeting the preset closing condition, if the switches are arranged between a connection point of a first switch tube and an inductor and a connection point of the first switch tube and a flying capacitor, the bus voltage is shared by a first diode and a second diode; if the switch is arranged between the connection point of the second diode and the flying capacitor and the connection point of the second diode and the first voltage-sharing capacitor, the second diode is in an open circuit state and cannot bear bus voltage, so that the problems that the second diode of the boost power conversion circuit in the prior art is difficult to select types and has overvoltage breakdown risk can be solved, and the design cost of the boost power conversion circuit is reduced.
Description
Technical Field
The invention relates to the technical field of photovoltaic power generation, in particular to a boost power conversion circuit, a control method and an application device thereof.
Background
In a common application scenario, the output terminals of the plurality of boost power conversion circuits need to be connected in parallel to the dc bus at the same time, and the output terminals are connected to the post-stage circuit after being converged by the dc bus. In this application scenario, if there is a boost power conversion circuit that is powered on before other boost power conversion circuits connected to the dc bus, there will be a bus voltage established by the boost power conversion circuit that is powered on before on the dc bus, and the bus voltage will affect other boost power conversion circuits that are not powered on the dc bus.
Referring to fig. 1, fig. 1 is a diagram of a three-level flying capacitor boost power conversion circuit commonly used in the prior art, when other boost power conversion circuits connected in parallel to the same dc bus are powered on first, a bus voltage V exists at an output terminal of the unpowered boost power conversion circuitbusAt this time, the flying capacitor C1 of the booster power conversion circuit to which the circuit is not powered on has a capacitor voltage and an input voltage V on its input sideinThe capacitors C2 and C3 have voltage, the switch tube T1 is bidirectionally short-circuited by the diode D2 and the diode D5, so that the input side of the unpowered boost power conversion circuit, the inductor L1, the switch tube T1, the switch tube T2, the diode D2 and the flying capacitor C1 can be approximately seen as equipotential, the negative pole N of the direct current bus is equally connected with the anode of the diode D3, the positive pole P of the direct current bus is connected with the cathode of the diode D3, that is, the diode D3 bears the whole bus voltage V3bus。
In this case, if the voltage-withstanding grade of the diode D3 is selected to be low, the diode D3 may be over-voltage broken, and if the voltage-withstanding grade of the diode D3 is increased, the diode D3 is not only difficult to select, but also the design cost of the circuit is increased.
Disclosure of Invention
The invention provides a boost power conversion circuit, a control method and an application device thereof, which are used for solving the problems that a diode D3 of the boost power conversion circuit is difficult to select and has overvoltage breakdown risk in the prior art and reducing the design cost of the boost power conversion circuit.
In order to achieve the purpose, the technical scheme provided by the application is as follows:
in a first aspect, the present invention provides a boost power conversion circuit, including: an inductor, a first diode, a second diode, a first voltage-sharing capacitor, a second voltage-sharing capacitor, a first switch tube with an anti-parallel diode, a second switch tube with an anti-parallel diode, a flying capacitor and at least one switch,
the inductor, the first diode, the second diode, the first voltage-sharing capacitor and the second voltage-sharing capacitor are sequentially connected in series to form a first series branch;
one end of the first series branch is used as a positive input end of the boost power conversion circuit, and the other end of the first series branch is used as a negative input end of the boost power conversion circuit;
the first switching tube and the second switching tube are connected in series to form a second series branch;
one end of the second series branch is connected with the series connection point of the inductor and the first diode, and the other end of the second series branch is connected with the negative electrode input end;
one end of the flying capacitor is connected with the series connection point of the first diode and the second diode, and the other end of the flying capacitor is connected with the series connection point of the first switch tube and the second switch tube;
the switch is arranged between a connection point of the first switch tube and the inductor and a connection point of the first switch tube and the flying capacitor, and at any one or more positions between a connection point of the second diode and the flying capacitor and a connection point of the second diode and the first voltage-sharing capacitor;
and the control end of the switch receives a control signal so as to be closed when a preset closing condition is met or be opened when the preset closing condition is not met.
Optionally, the preset closing condition includes that the input voltage of the boost power conversion circuit reaches a first preset voltage threshold, or the capacitor voltage of the flying capacitor reaches a second preset voltage threshold.
Optionally, the first preset voltage threshold is equal to the second preset voltage threshold.
Optionally, the switch is a normally open switch.
Optionally, the normally open switch is at least one of a relay, a contactor, and a semiconductor switch without an anti-parallel diode.
Optionally, the boost power conversion circuit provided in the first aspect of the present invention further includes: a third diode, wherein,
the anode of the third diode is connected with the series connection point of the first switch tube and the second switch tube, and the cathode of the third diode is connected with the series connection point of the first voltage-sharing capacitor and the second voltage-sharing capacitor.
Optionally, the boost power conversion circuit provided in the first aspect of the present invention further includes: a fourth diode, wherein,
one end of the fourth diode is connected with the anode input end, and the other end of the fourth diode is connected with the series connection point of the first voltage-sharing capacitor and the second diode.
In a second aspect, the present invention provides a method for controlling a boost power converter circuit, which is applied to the boost power converter circuit according to any one of the first aspect of the present invention, the method including:
acquiring input voltage of the boost power conversion circuit and capacitance voltage of a flying capacitor in the boost power conversion circuit;
judging whether the input voltage and the capacitor voltage meet a preset closing condition or not;
if the preset closing condition is not met, maintaining the switch in the boost power conversion circuit to be switched off;
and if the preset closing condition is met, controlling the switch to be closed.
Optionally, the determining whether the input voltage and the capacitor voltage meet a preset closing condition includes:
if the input voltage reaches a first preset voltage threshold value, or the capacitor voltage reaches a second preset voltage threshold value, judging that the preset closing condition is met;
and if the input voltage does not reach a first preset voltage threshold value and the capacitor voltage does not reach a second preset voltage threshold value, judging that the preset closing condition is not met.
In a third aspect, the present invention provides a boost power conversion apparatus, including: the detection module, the controller and the boost power conversion circuit according to any one of the first aspect of the present invention, wherein,
the detection module is used for detecting and outputting the input voltage of the boost power conversion circuit and the capacitance voltage of a flying capacitor in the boost power conversion circuit to the controller;
the controller is configured to obtain the input voltage and the capacitor voltage, execute the control method of the boost power conversion circuit according to any one of the second aspects of the present invention, and output a control signal to a control terminal of a switch in the boost power conversion circuit.
In a fourth aspect, the present invention provides an inverter comprising an inverter module and at least one boost power conversion circuit according to any one of the first aspect of the present invention, wherein,
each boosting power conversion circuit is used for boosting input voltage and then outputting the boosted input voltage to a direct current bus of the inversion module;
the inversion module is used for inverting the direct current output by the boost power conversion circuit into alternating current.
In a fifth aspect, the present invention provides a photovoltaic power generation apparatus comprising a photovoltaic string and the boost power conversion apparatus according to the third aspect, wherein,
the low-voltage side of the boosting power conversion device is connected with the output end of the photovoltaic string;
and the high-voltage side of the boosting power conversion device is used as the output end of the photovoltaic power generation device.
In a sixth aspect, the present invention provides a photovoltaic power generation system comprising a plurality of sets of photovoltaic power generation apparatuses according to any one of the fifth aspect of the present invention and a dc bus, wherein,
the output end of each photovoltaic power generation device is connected in parallel with the direct current bus.
The boost power conversion circuit provided by the invention is characterized in that switches are arranged at any one or more positions between a connection point of a first switch tube and an inductor and a connection point of the first switch tube and a flying capacitor, between a connection point of a second diode and the flying capacitor and between a connection point of the second diode and a first voltage-sharing capacitor, and control ends of the switches receive control signals so as to be closed when a preset closing condition is met or be opened when the preset closing condition is not met.
In the boost power conversion circuit provided by the invention, under the condition that the switch is arranged between the connection point of the first switch tube and the inductor and the connection point of the first switch tube and the flying capacitor, if bus voltage exists, the switch is switched off when a preset closing condition is not met, the bus voltage is jointly borne by the first diode and the second diode, and the second diode only needs to bear half of the voltage drop of the bus voltage; and under the condition that the switch is arranged between the connection point of the second diode and the flying capacitor and the connection point of the second diode and the first voltage-sharing capacitor, if bus voltage exists, the switch is switched off when a preset closing condition is not met, the second diode is in an open circuit state and cannot bear the bus voltage, and the type selection can be performed according to half of the bus voltage.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings 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 of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a conventional three-level flying capacitor boost power conversion circuit in the prior art;
fig. 2 is a circuit topology diagram of a boost power conversion circuit according to an embodiment of the present invention;
fig. 3 is a circuit topology diagram of another boost power conversion circuit provided by the embodiment of the invention;
fig. 4 is a circuit topology diagram of a further boost power conversion circuit according to an embodiment of the present invention;
fig. 5 is a flowchart of a control method of a boost power conversion circuit according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Optionally, referring to fig. 2, fig. 2 is a circuit topology diagram of a boost power conversion circuit according to an embodiment of the present invention, where the boost power conversion circuit according to the embodiment of the present invention may include: an inductor L, a first diode D1, a second diode D2, a first equalizing capacitor C1, a second equalizing capacitor C2, a first switch tube T1 with an anti-parallel diode (i.e. the diode D5 shown in FIG. 2), a second switch tube T2 with an anti-parallel diode (i.e. the diode D6 shown in FIG. 2), and a flying capacitor C2fAnd at least one switch (not shown), wherein,
the inductor L, the first diode D1, the second diode D2, the first equalizing capacitor C1 and the second equalizing capacitor C2 are sequentially connected in series to form a first series branch, one end of the first series branch is used as an anode input end of the boost power conversion circuit, and the other end of the first series branch is used as a cathode input end of the boost power conversion circuit. Specifically, in the embodiment of the present invention, one end of the inductor L is used as an anode input end of the boost power conversion circuit, and an output end of the second voltage-sharing capacitor C2 is used as a cathode input end of the boost power conversion circuit, when the anode input end of the boost power conversion circuit is connected to an anode of the dc power supply and the cathode input end is connected to a cathode of the dc power supply, the dc power supply and the first serial branch will form a complete closed loop.
Further, an input end of the first equalizing capacitor C1 is used as an anode output end of the boost power conversion circuit, an output end of the second equalizing capacitor C2 is also used as a cathode output end of the boost power conversion circuit, and a load or a post-stage circuit (shown by R in fig. 2) is connected with the anode output end and the cathode output end of the boost power conversion circuit to receive the direct-current electric energy output by the boost power conversion circuit after being boosted.
The first switch tube T1 and the second switch tube T2 are connected in series to form a second series branch, one end of the second series branch is connected to the series connection point of the inductor L and the first diode D1, and the other end of the second series branch is connected to the negative input end of the boost power conversion circuit. Similarly, when the boost power converter circuit is connected to the dc power source, the inductor L and the second series branch form another closed loop.
Flying capacitor CfIs connected to the series connection of a first diode D1 and a second diode D2, and a flying capacitor CfAnd the other end thereof is connected to the series connection point of the first switching tube D1 and the second switching tube D2.
Optionally, the boost power conversion circuit provided in the embodiment of the present invention further includes a third diode D3 and a fourth diode D4. Specifically, the anode of the third diode D3 is connected to the series connection point of the first switch transistor T1 and the second switch transistor T2 (and is also the flying capacitor C)fAnd the connection point of the second switching tube T2), and the cathode of the third diode D3 is connected to the series connection point of the first equalizing capacitor C1 and the second equalizing capacitor C2.
One end of the fourth diode D4 is connected to the positive input end of the boost power conversion circuit, and the other end of the fourth diode D4 is connected to the series connection point of the first equalizing capacitor C1 and the second diode D2 (which is also the positive output end of the boost power conversion circuit).
On the basis of the circuit topology, the boost power conversion circuit provided by the embodiment of the invention further comprises at least one switch. Optionally, in order to simplify the control logic of the circuit and avoid applying an additional control signal to control the state of the switch before the circuit normally operates, the switch may be a normally open switch, specifically, such as a relay, a contactor, and a semiconductor switch without an anti-parallel diode, and of course, when specifically selecting, at least one of them may be selected. It should be noted that, on the premise of not exceeding the scope of the core idea of the present invention, other electronic components or circuit structures that can implement the corresponding functions of the switch in the embodiments of the present invention are optional, and also belong to the protection scope of the present invention.
Referring to fig. 2, the optional positions of the switches are shown as a, b, C and d in fig. 2, namely, the connection point of the first switch tube T1 and the inductor L and the connection point of the first switch tube T1 and the flying capacitor CfAnd a second diode D2 and a flying capacitor CfAnd the connection point of the second diode D2 and the first grading capacitor C1. It should be noted that, in the boost power conversion circuit provided in the embodiment of the present invention, only one switch may be provided, or a plurality of switches may be provided, and the number of the switches may be specifically selected according to needs, but the setting position of the switch must be one or more of the above-mentioned limited positions.
And the control end of each switch receives a control signal so as to be closed when a preset closing condition is met or be opened when the preset closing condition is not met. Specifically, before the positive input end and the negative input end of the boost power conversion circuit are connected to the input voltage, each switch is in an off state. Boosting the input voltage of the power conversion circuit and the flying capacitor C after the input voltage is switched onfThe capacitor voltage of the flying capacitor C is gradually increased, but the input voltage of the boost power conversion circuit does not reach the first preset voltage threshold value, and the flying capacitor CfUnder the condition that the capacitor voltage does not reach the second preset voltage threshold value, namely when the preset closing condition is met, all the switches are still in an off state. Conversely, when the input voltage of the boost power conversion circuit reaches the first preset voltage threshold value, or the flying capacitor CfWhen the capacitor voltage reaches a second preset voltage threshold, that is, when a preset closing condition is met, each switch is connected according to the voltageThe received control signal is closed and maintains the closed state.
It should be noted that, the first preset voltage threshold and the second preset voltage threshold may be selected from the same voltage value, or may be selected from different voltage values, so that the selection may be performed flexibly.
It should be noted that, based on the above-mentioned operation processes of the switches, it can be known that each switch should be in an off state when the preset on condition is not met, and therefore, if each switch selects a normally open switch, it is not necessary to apply a separate control signal to control the switch to be turned off when the preset on condition is not met, and the control process can be simplified to a certain extent, and only when the preset on condition is met, it is necessary to control each switch to be turned on.
In summary, the boost power conversion circuit provided in the embodiments of the present invention has a switch disposed at a specific position, specifically, when the switch is disposed at the connection point between the first switch tube and the inductor, and the first switch tube T1 and the flying capacitor CfIn the case of the connection point (i.e., the position of point a and point b shown in fig. 2), if the boost power conversion circuit has bus voltage, and the preset closing condition is not met, the switch is turned off, the bus voltage is shared by the first diode and the second diode, and the second diode only needs to bear half of the voltage drop of the bus voltage; and when the switch is arranged between the connection point of the second diode and the flying capacitor and the connection point of the second diode and the first voltage-sharing capacitor (namely, the positions of the point c and the point d shown in fig. 2), if the bus voltage exists, the switch is switched off when the preset closing condition is not met, the second diode is in an open circuit state and cannot bear the bus voltage, and the type selection can be performed according to half of the bus voltage.
It is conceivable that, in the case of setting the switches at the points c and d, although the second diode may be made to be in the off state without having to bear any bus voltage, when the boost power conversion circuit enters the normal operation state, that is, when the switches are closed while satisfying the preset closing condition, the second diode still needs to bear half of the bus voltage, and therefore, the model selection of the second diode still needs to use half of the bus voltage as the reference voltage.
The boost power conversion circuit provided by the embodiment of the invention is described below with reference to a specific application scenario.
Optionally, referring to fig. 3, fig. 3 is a circuit topology diagram of another boost power conversion circuit according to an embodiment of the present invention, as shown in fig. 3, the switch S1 is a normally open switch and is set at a point b shown in fig. 2, and other circuit configurations and connection relationships may refer to the embodiment shown in fig. 2, and are not repeated here.
In the embodiment of fig. 3, switch S1 is off before the boost power converter circuit is switched on to the input voltage, and flying capacitor C is connected if the bus voltage is established at the output of the boost power converter circuitfThe first switch tube T1 is not bidirectionally shorted by its own anti-parallel diode D5 and first diode D1 because S1 is turned off, and the bus voltage will be shared by the first diode D1 and the second diode D2.
Therefore, even if the withstand voltage value of the second diode D2 is selected to be half of the target voltage, there is no risk of overvoltage breakdown. The input end of the power conversion circuit to be boosted is connected with a direct-current power supply, the voltage of the input end is gradually increased, and meanwhile, the flying capacitor CfThe capacitor voltage will also gradually rise, when it is detected that the input voltage reaches the first preset voltage threshold, or the capacitor voltage reaches the second preset voltage threshold, a control signal can be sent to control the switch S1 to close, and the closed state is maintained all the time in the normal working process of the boost power conversion circuit.
Optionally, referring to fig. 4, fig. 4 is a circuit topology diagram of another boost power conversion circuit according to an embodiment of the present invention, as shown in fig. 4, the switch S2 is a normally open switch and is set at a point c shown in fig. 2, and other circuit configurations and connection relationships may refer to the embodiment shown in fig. 2, and are not repeated here.
In the embodiment shown in fig. 4, the switch S2 is in the off state before the boost power conversion circuit is connected to the input voltage, and since the branch of the second diode D2 is disconnected due to the disconnection of S2, even though the bus voltage is already established on the output side of the boost power conversion circuit at this time, the second diode D2 will not bear the bus voltage, and there is no risk of overvoltage breakdown.
After the boost power conversion circuit is connected with the input voltage, if the input voltage of the boost power conversion circuit is detected to reach a first preset voltage threshold value or the capacitor voltage of the flying capacitor reaches a second preset voltage threshold value, a control signal can be sent to control the switch S2 to be closed, and the closed state is always maintained in the normal working process of the boost power conversion circuit.
Optionally, based on the boost power conversion circuit provided in any of the embodiments, an embodiment of the present invention provides a control method for a boost power conversion circuit. The control method may be applied to the boost power conversion circuit provided in any of the above embodiments, referring to fig. 5, fig. 5 is a flowchart of a control method of the boost power conversion circuit provided in an embodiment of the present invention, where the flowchart may include:
s100, acquiring an input voltage of the boost power conversion circuit and a capacitance voltage of a flying capacitor in the boost power conversion circuit.
As described above, the condition that the second diode in the boost power conversion circuit has the risk of overvoltage breakdown occurs when the bus voltage is established on the output side of the boost power conversion circuit, and the boost power conversion circuit is not connected to the input voltage, so that the control method of the boost power conversion circuit according to the embodiment of the present invention needs to monitor the input voltage of the boost power conversion circuit.
Furthermore, after the input voltage is connected to the input end of the boost power conversion circuit, the capacitance voltage of the flying capacitor and the input voltage of the boost power conversion circuit are changed almost synchronously, so that the capacitance voltage of the flying capacitor can be monitored synchronously.
Optionally, the obtaining of the input voltage and the capacitor voltage may be implemented by a detection circuit in the prior art, and the input voltage and the capacitor voltage are fed back to the controller after corresponding analog-to-digital conversion.
S110, judging whether the input voltage and the capacitor voltage meet a preset closing condition, if not, executing S120, and if so, executing S130.
After the input voltage of the boost power conversion circuit and the capacitor voltage of the flying capacitor are obtained, whether a preset closing condition is met or not is further judged. If the preset closing condition is not met, executing S120, and keeping a switch in the boost power conversion circuit to be switched off; if the preset closing condition is met, S130 is executed, and the control switch is closed.
Specifically, if the input voltage reaches a first preset voltage threshold, or the capacitor voltage reaches a second preset voltage threshold, it is determined that the preset closing condition is satisfied, and only one of the preset closing condition and the preset closing condition needs to be satisfied. And if the input voltage does not reach the first preset voltage threshold value and the capacitor voltage does not reach the second preset voltage threshold value, judging that the preset closing condition is not met.
And S120, keeping the switch in the boost power conversion circuit to be switched off.
And under the condition that the preset closing condition is not met, maintaining the switch in the boosting power conversion circuit to be opened. It is conceivable that, if the switch is a normally open switch, the actual execution process of this step is actually realized without outputting a corresponding control signal.
Referring to the above example, according to the specific setting position of the switch, the second diode and the first diode in the boost power conversion circuit can share the bus voltage, or the second diode is completely in the open circuit state and does not bear any bus voltage, and the specific implementation principle is not repeated here.
And S130, controlling the switch to be closed.
After the preset closing condition is met, the control signal can be output to control the switch arranged in the boost power conversion circuit to be closed, and the closed state is maintained in the normal working process of the boost power conversion circuit.
In summary, according to the control method of the boost power conversion circuit provided by the embodiment of the present invention, when the preset closing condition is not satisfied, the switch in the boost power conversion circuit is kept off, and when the switch is disposed between the connection point of the first switching tube and the inductor and the connection point of the first switching tube and the flying capacitor, if the bus voltage exists, the bus voltage is shared by the first diode and the second diode, and the second diode only needs to share half of the voltage drop of the bus voltage; and under the condition that the switch is arranged between the connection point of the second diode and the flying capacitor and the connection point of the second diode and the first voltage-sharing capacitor, if the bus voltage exists, the second diode is in an open circuit state and cannot bear the bus voltage, and the type selection can be carried out according to half of the bus voltage.
Therefore, the control method of the boost power conversion circuit provided by the invention is based on the boost power conversion circuit provided by any embodiment, can solve the problems that the second diode of the boost power conversion circuit is difficult to select and has overvoltage breakdown risk in the prior art, and reduces the design cost of the boost power conversion circuit.
Optionally, an embodiment of the present invention further provides a boost power conversion apparatus, including: the detection module, the controller and the boost power conversion circuit provided by any of the above embodiments, wherein,
the detection module is used for detecting and outputting the input voltage of the boost power conversion circuit and the capacitance voltage of a flying capacitor in the boost power conversion circuit to the controller;
the controller is configured to obtain the input voltage and the capacitor voltage, execute the control method of the boost power conversion circuit according to the above embodiment of the present invention, and output a control signal to a control terminal of a switch in the boost power conversion circuit.
Optionally, an embodiment of the present invention further provides an inverter, which includes an inverter module and at least one boost power conversion circuit provided in any one of the above embodiments, wherein,
each boosting power conversion circuit is used for boosting input voltage and then outputting the boosted input voltage to a direct current bus of the inversion module;
the inversion module is used for inverting the direct current output by the boost power conversion circuit into alternating current.
Optionally, an embodiment of the present invention further provides a photovoltaic power generation apparatus, which is characterized by including a photovoltaic string and the boost power conversion apparatus provided in any of the above embodiments, wherein,
the low-voltage side of the boosting power conversion device is connected with the output end of the photovoltaic string;
and the high-voltage side of the boosting power conversion device is used as the output end of the photovoltaic power generation device.
Optionally, an embodiment of the present invention further provides a photovoltaic power generation system, which is characterized by comprising a plurality of sets of photovoltaic power generation apparatuses and a dc bus provided in the above embodiment, wherein,
the output end of each photovoltaic power generation device is connected in parallel with the direct current bus.
The embodiments of the invention are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments can be referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.
The foregoing is merely a preferred embodiment of the invention and is not intended to limit the invention in any manner. Although the present invention has been described with reference to the preferred embodiments, it is not intended to be limited thereto. Those skilled in the art can make numerous possible variations and modifications to the present teachings, or modify equivalent embodiments to equivalent variations, without departing from the scope of the present teachings, using the methods and techniques disclosed above. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention are still within the scope of the protection of the technical solution of the present invention, unless the contents of the technical solution of the present invention are departed.
Claims (13)
1. A boost power conversion circuit, comprising: an inductor, a first diode, a second diode, a first voltage-sharing capacitor, a second voltage-sharing capacitor, a first switch tube with an anti-parallel diode, a second switch tube with an anti-parallel diode, a flying capacitor and at least one switch,
the inductor, the first diode, the second diode, the first voltage-sharing capacitor and the second voltage-sharing capacitor are sequentially connected in series to form a first series branch;
one end of the first series branch is used as a positive input end of the boost power conversion circuit, and the other end of the first series branch is used as a negative input end of the boost power conversion circuit;
the first switching tube and the second switching tube are connected in series to form a second series branch;
one end of the second series branch is connected with the series connection point of the inductor and the first diode, and the other end of the second series branch is connected with the negative electrode input end;
one end of the flying capacitor is connected with the series connection point of the first diode and the second diode, and the other end of the flying capacitor is connected with the series connection point of the first switch tube and the second switch tube;
the switch is arranged between a connection point of the first switch tube and the inductor and a connection point of the first switch tube and the flying capacitor, and at any one or more positions between a connection point of the second diode and the flying capacitor and a connection point of the second diode and the first voltage-sharing capacitor;
and the control end of the switch receives a control signal so as to be closed when a preset closing condition is met or be opened when the preset closing condition is not met.
2. A boost power conversion circuit according to claim 1, wherein the predetermined closed condition comprises the input voltage to the boost power conversion circuit reaching a first predetermined voltage threshold, or the capacitance voltage of the flying capacitor reaching a second predetermined voltage threshold.
3. A boost power conversion circuit according to claim 2, wherein the first predetermined voltage threshold is equal to the second predetermined voltage threshold.
4. A boost power conversion circuit according to claim 1, wherein said switch is a normally open switch.
5. A boost power conversion circuit according to claim 4, wherein said normally open switch is at least one of a relay, a contactor, and a semiconductor switch without an anti-parallel diode.
6. A boost power conversion circuit according to any one of claims 1-5, further comprising a third diode, wherein,
the anode of the third diode is connected with the series connection point of the first switch tube and the second switch tube, and the cathode of the third diode is connected with the series connection point of the first voltage-sharing capacitor and the second voltage-sharing capacitor.
7. A boost power conversion circuit according to any one of claims 1-5, further comprising: a fourth diode, wherein,
one end of the fourth diode is connected with the anode input end, and the other end of the fourth diode is connected with the series connection point of the first voltage-sharing capacitor and the second diode.
8. A method for controlling a boost power converter circuit, applied to the boost power converter circuit according to any one of claims 1 to 7, the method comprising:
acquiring input voltage of the boost power conversion circuit and capacitance voltage of a flying capacitor in the boost power conversion circuit;
judging whether the input voltage and the capacitor voltage meet a preset closing condition or not;
if the preset closing condition is not met, maintaining the switch in the boost power conversion circuit to be switched off;
and if the preset closing condition is met, controlling the switch to be closed.
9. The method of claim 8, wherein the determining whether the input voltage and the capacitor voltage satisfy a predetermined closing condition comprises:
if the input voltage reaches a first preset voltage threshold value, or the capacitor voltage reaches a second preset voltage threshold value, judging that the preset closing condition is met;
and if the input voltage does not reach a first preset voltage threshold value and the capacitor voltage does not reach a second preset voltage threshold value, judging that the preset closing condition is not met.
10. A boost power conversion apparatus, comprising: the detection module, the controller and the boost power conversion circuit of any one of claims 1-7, wherein,
the detection module is used for detecting and outputting the input voltage of the boost power conversion circuit and the capacitance voltage of a flying capacitor in the boost power conversion circuit to the controller;
the controller is configured to obtain the input voltage and the capacitor voltage, perform the control method of the boost power conversion circuit according to claim 8 or claim 9, and output a control signal to a control terminal of a switch in the boost power conversion circuit.
11. An inverter comprising an inverter module and at least one boost power conversion circuit according to any one of claims 1 to 7,
each boosting power conversion circuit is used for boosting input voltage and then outputting the boosted input voltage to a direct current bus of the inversion module;
the inversion module is used for inverting the direct current output by the boost power conversion circuit into alternating current.
12. A photovoltaic power generation apparatus comprising a photovoltaic string and the boost power conversion apparatus according to claim 10, wherein,
the low-voltage side of the boosting power conversion device is connected with the output end of the photovoltaic string;
and the high-voltage side of the boosting power conversion device is used as the output end of the photovoltaic power generation device.
13. A photovoltaic power generation system comprising a plurality of sets of photovoltaic power generation apparatuses according to claim 12 and a DC bus, wherein,
the output end of each photovoltaic power generation device is connected in parallel with the direct current bus.
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| CN201911005659.5A CN112701913A (en) | 2019-10-22 | 2019-10-22 | Boost power conversion circuit and control method and application device thereof |
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| CN201911005659.5A CN112701913A (en) | 2019-10-22 | 2019-10-22 | Boost power conversion circuit and control method and application device thereof |
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