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WO2016119737A1 - 半桥逆变器单元及逆变器 - Google Patents

半桥逆变器单元及逆变器 Download PDF

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Publication number
WO2016119737A1
WO2016119737A1 PCT/CN2016/072701 CN2016072701W WO2016119737A1 WO 2016119737 A1 WO2016119737 A1 WO 2016119737A1 CN 2016072701 W CN2016072701 W CN 2016072701W WO 2016119737 A1 WO2016119737 A1 WO 2016119737A1
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WIPO (PCT)
Prior art keywords
bidirectional switch
circuit module
diode
terminal
bridge inverter
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Ceased
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PCT/CN2016/072701
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English (en)
French (fr)
Inventor
汪洪亮
刘雁飞
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Individual
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Individual
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Priority to CN201680003955.XA priority Critical patent/CN107534398B/zh
Priority to US15/547,005 priority patent/US10277146B2/en
Publication of WO2016119737A1 publication Critical patent/WO2016119737A1/zh
Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
    • H02M7/66—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output with possibility of reversal
    • H02M7/68—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output with possibility of reversal by static converters
    • H02M7/72—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/79—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/797—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for AC mains or AC distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • 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
    • H02J2101/24—
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0067—Converter structures employing plural converter units, other than for parallel operation of the units on a single load
    • H02M1/007—Plural converter units in cascade
    • 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

Definitions

  • the invention relates to an inverter unit and an inverter in the field of power electronics, in particular a half bridge inverter.
  • Photovoltaic power generation has a good development prospect because of its abundant resources and wide distribution. For photovoltaic power generation systems, how to reduce costs and improve efficiency has become an important issue for photovoltaic power generation.
  • an inverter In a photovoltaic power generation system, an inverter is used to convert direct current output from a photovoltaic array into alternating current.
  • Grid-connected inverters can be divided into two types: isolated grid-connected inverters and non-isolated grid-connected inverters.
  • isolated grid-tied inverters the transformer is electrically isolated to ensure personal safety.
  • the energy loss and bulk of the transformer bring many problems, such as low efficiency, low power density and high cost. Therefore, non-isolated photovoltaic grid-connected inverters have become mainstream.
  • non-isolated photovoltaic grid-connected inverter systems there is a common mode loop due to the lack of electrical isolation of the transformer.
  • Non-isolated PV inverters are required to meet a wide range of input voltages due to the wide range of fluctuations in the output voltage of the PV array.
  • non-isolated inverters in photovoltaic systems have a normal operating minimum input voltage.
  • the output voltage of the PV array may be less than the minimum input voltage of the inverter. Therefore, a boost circuit is typically used in photovoltaic inverter systems.
  • the existing photovoltaic inverter system is a two-stage circuit.
  • the first level is DC-DC Unit, the DC-DC unit is usually implemented by a booster circuit.
  • the second stage is the DC-AC unit.
  • the DC-DC unit When the PV array output voltage is less than the minimum input voltage, the DC-DC unit operates to raise the input voltage to operate the DC-AC unit normally; when the PV array output voltage is greater than the minimum input voltage, the DC-DC unit is bypassed, The DC-AC unit works normally.
  • the two-stage circuits are connected in series, thereby reducing system efficiency and increasing cost.
  • the single-stage full-bridge inverter shown in Fig. 2 is given in the reference "Derivation, Analysis, and Implementation of a Boost-Buck Converter-Based High-Efficiency PV Inverter".
  • this single-stage full-bridge inverter is costly in the case of multiple photovoltaic arrays.
  • the single-stage full-bridge inverter is inefficient when the number of photovoltaic cells in a plurality of photovoltaic arrays is very different. Since the photovoltaic arrays are connected in parallel, the output voltage requirements of each photovoltaic array are equal. To this end, the output voltage of each photovoltaic array is increased to varying degrees. This reduces system efficiency.
  • the present invention provides a half bridge inverter unit and an inverter to solve the above problems in the prior art.
  • each switching transistor is connected in reverse with a diode.
  • the term "bidirectional switch” as used in this application refers to a switch that can flow in both directions but can only withstand unidirectional voltage, such as an IGBT with an anti-parallel diode, or a MOSFET with a parallel diode.
  • the present invention provides a half-bridge inverter unit, including: an inverter control module and a first inductor; and having a first access terminal, a second access terminal, a third access terminal, and a first voltage An output end and a second voltage output end and a plurality of control ends;
  • the inverter control module is connected to the first access terminal, the second access terminal, the third access terminal, the first voltage output terminal, the second voltage output terminal, the first end of the inductor, and the second end of the inductor. a terminal, and connecting the plurality of control ends; for inputting to each according to the first working mode Control signals of the control terminals, for the seven terminals, the connection between the first end of the first inductor and the first access end and the connection between the second end of the first inductor and the first voltage output end And disconnecting other end-to-end connections; according to the control signals input to the respective control terminals in the second working mode, for the seven terminals, between the first end and the second access end of the first inductor are turned on The connection and the connection between the second end of the first inductor and the first voltage output terminal; according to the control signal input to each control terminal in the third working mode, the first inductor is turned on for the seven terminals a connection between one end and the first access end and a connection between the second end of the
  • the present invention provides a single phase half bridge inverter.
  • the single-phase half-bridge inverter includes the half-bridge inverter unit of the first aspect and a controller; wherein the controller is connected to several control ends of the half-bridge inverter unit, The control signals corresponding to the respective working modes are provided for the half bridge inverter unit.
  • the present invention provides a three-phase half-bridge inverter.
  • the three-phase half-bridge inverter includes a controller and three half-bridge inverter units provided by the first aspect, wherein a first access end of each half-bridge inverter unit is connected to each other, and a second The access terminals are connected to each other, and the third access terminals are connected to each other; the first voltage output ends of the respective half bridge inverter units are connected one-to-one to the AC load access terminal of one phase of the three-phase half-bridge inverter;
  • the controller is connected to each control terminal of each half-bridge inverter unit for providing a control signal corresponding to each level mode for the half-bridge inverter unit.
  • the half-bridge inverter unit and the corresponding inverter provided by the invention can operate in a buck mode or a boost mode, thus meeting the requirements of the wide input voltage range of the inverter.
  • the two series connected in parallel with the DC power supply are solved.
  • the inverter adopts a single-stage structure, which has low power consumption, low cost, high efficiency and high stability.
  • the present invention provides a half-bridge inverter unit and an inverter that can be used, but is not limited to, a renewable energy system, such as a single-phase or three-phase grid-connected photovoltaic system.
  • FIG. 1 The feature information and advantages of the present invention will be more clearly understood from the following description of the accompanying drawings.
  • 1 is a circuit block diagram of a conventional two-stage inverter system
  • FIG. 2 is a schematic diagram of a circuit principle of a conventional single-stage full-bridge inverter system
  • 3(a) is a partial block diagram showing the circuit principle of a first single-phase half-bridge inverter according to an embodiment of the present invention
  • 3(b) is a partial block diagram showing the circuit principle of a second single-phase half-bridge inverter according to an embodiment of the present invention
  • FIG. 4(a) is a schematic diagram of a first circuit principle of a first circuit module M1 according to an embodiment of the present invention
  • 4(b) is a schematic diagram showing a second circuit principle of a first circuit module M1 according to an embodiment of the present invention
  • 4(c) is a schematic diagram showing a third circuit principle of the first circuit module M1 according to an embodiment of the present invention.
  • 4(d) is a schematic diagram showing a fourth circuit principle of the first circuit module M1 according to an embodiment of the present invention.
  • FIG. 5(a) is a schematic diagram of a first circuit principle of a second circuit module M2 according to an embodiment of the present invention
  • FIG. 5(b) is a schematic diagram of a second circuit principle of a second circuit module M2 according to an embodiment of the present invention.
  • FIG. 5(c) is a schematic diagram of a third circuit principle of a second circuit module M2 according to an embodiment of the present invention.
  • FIG. 5(d) is a schematic diagram of a fourth circuit principle of a second circuit module M2 according to an embodiment of the present invention.
  • FIG. 6 is a first single-phase half bridge including a first circuit module M1 in FIG. 4(a) and a second circuit module M2 in FIG. 5(a) and a magnetic core shared by L1 and L2 according to an embodiment of the present invention.
  • FIG. 7 is a first single-phase half bridge including a first circuit module M1 in FIG. 4(a) and a second circuit module M2 in FIG. 5(b) and a magnetic core shared by L1 and L2 according to an embodiment of the present invention.
  • FIG. 8 is a second-phase half-bridge including a first circuit module M1 in FIG. 4(a) and a second circuit module M2 in FIG. 5(a) and a magnetic core shared by L1 and L2 according to an embodiment of the present invention.
  • FIG. 9 is a second single-phase half bridge including a first circuit module M1 in FIG. 4(a) and a second circuit module M2 in FIG. 5(b) and a magnetic core shared by L1 and L2 according to an embodiment of the present invention.
  • FIG. 10 is a single-phase half bridge including the first circuit module M1 in FIG. 4(a) and the second circuit module M2 in FIG. 5(a) and L1 and L2 do not share a magnetic core according to an embodiment of the present invention.
  • FIG. 11 is a schematic diagram of a first working mode of a single-phase half-bridge inverter according to an embodiment of the present invention.
  • FIG. 12 is a schematic diagram of a second working mode of a single-phase half-bridge inverter according to an embodiment of the present invention.
  • FIG. 13 is a schematic diagram of a third working mode of a single-phase half-bridge inverter according to an embodiment of the present invention.
  • FIG. 14 is a schematic diagram of a fourth working mode of a single-phase half-bridge inverter according to an embodiment of the present invention.
  • 15 is a schematic diagram of a first modulation strategy of a single-phase half-bridge inverter according to an embodiment of the present invention.
  • 16 is a schematic diagram of a second modulation strategy of a single-phase half-bridge inverter according to an embodiment of the present invention.
  • FIG. 17 is a schematic diagram of a circuit principle of a single-phase half-bridge inverter applied to a photovoltaic system having multiple photovoltaic arrays according to an embodiment of the present invention
  • FIG. 18 is a schematic diagram of a circuit principle of a first-phase half-bridge inverter applied to a photovoltaic system having two photovoltaic arrays according to an embodiment of the present invention
  • FIG. 19 is a schematic diagram of a circuit principle of a second-phase half-bridge inverter applied to a photovoltaic system having two photovoltaic arrays according to an embodiment of the present invention
  • 20(a) is an equivalent block diagram of a first single-phase half-bridge inverter according to an embodiment of the present invention
  • 20(b) is an equivalent block diagram of a second single-phase half-bridge inverter according to an embodiment of the present invention.
  • 21(a) is a block diagram showing the circuit principle of a first three-phase half-bridge inverter according to an embodiment of the present invention
  • 21(b) is a block diagram showing the circuit principle of a second three-phase half-bridge inverter according to an embodiment of the present invention.
  • 21(c) is a block diagram showing the circuit principle of a third three-phase half-bridge inverter according to an embodiment of the present invention.
  • FIG. 21(d) is a block diagram showing the circuit principle of a fourth three-phase half-bridge inverter according to an embodiment of the present invention.
  • the invention provides a half bridge inverter unit and an inverter.
  • the technical solutions in the embodiments of the present invention are clearly and completely described in the accompanying drawings. It is apparent that the described embodiments are only a part of the embodiments of the invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of the present invention.
  • the half bridge inverter unit provided by the invention comprises:
  • An inverter control module and a first inductor and having a first access terminal, a second access terminal, a third access terminal, a first voltage output terminal and a second voltage output terminal, and a plurality of control terminals;
  • the inverter control module is connected to the first access terminal, the second access terminal, the third access terminal, the first voltage output terminal, the second voltage output terminal, the first end of the inductor, and the second end of the inductor.
  • a terminal connected to the plurality of control terminals; configured to turn on the first end of the first inductor and the first access terminal for the seven terminals according to a control signal input to each control terminal in the first working mode And a connection between the second end of the first inductor and the first voltage output, and disconnecting the other end-to-end connection; according to the control signal input to each control end in the second working mode, Seven terminals, connecting a connection between the first end and the second end of the first inductor and a connection between the second end of the first inductor and the first voltage output; input according to the third working mode a control signal to each of the control terminals, for the seven terminals, between the first end of the first inductor and the first access end and between the second end of the first inductor and the second voltage
  • the half-bridge inverter unit provided by the invention can control the half-bridge inverter including the half-bridge inverter unit to operate in the buck mode or the liter by controlling the inverter control module to apply the corresponding control signal.
  • the voltage mode thus meets the requirements of the wide input voltage range of the inverter.
  • the use of the positive and negative half-cycle symmetry of the grid voltage solves the problem of the midpoint voltage balance of the two series capacitors in parallel with the DC power supply.
  • the inverter adopts a single-stage structure and consumes power. Small, low cost, high efficiency and high stability.
  • the above-mentioned inverter control module can be implemented by various structures.
  • the most direct way may be to set four switch branches, wherein the first switch branch is connected to the first access end and the first Between the first ends of an inductor, the second switch branch is connected between the second access terminal and the first end of the first inductor, and the third switch branch is connected to the second end of the first inductor and the first voltage Between the outputs, the fourth switch branch is connected between the second end of the first inductor and the second voltage output.
  • the term "PV" as used in the present invention denotes a photovoltaic array (that is, a direct current power source), U PV denotes an output voltage of a photovoltaic array, and M1 denotes a first circuit module in a half bridge inverter unit, M2 Representing the second circuit module, C 1 represents the first capacitor (ie, the first DC power source), C 2 represents the second capacitor (ie, the second DC power source), C 3 represents the third capacitor, and G represents the AC grid.
  • the photovoltaic array PV can be replaced by other DC power sources, that is, the DC power source in the present invention is not limited to PV.
  • the AC grid G can be replaced with other AC loads, that is, the AC load in the present invention is not limited to the AC grid.
  • the diode is used to represent a unidirectional conduction element, but the one-directional conduction element in the present invention is not limited to the diode.
  • the anode of the diode refers to the anode and the cathode refers to the cathode.
  • a switching MOSFET is used to represent a controllable (on and off) switching transistor in the present invention.
  • An N-channel MOSFET will be described as an example. The first end of the N-channel MOSFET is the drain, the second end is the source, and the control is the gate.
  • a drive control signal is applied to each of the switch control terminals of the half bridge inverter unit. For the sake of brevity, we will not repeat them later.
  • each of the switching tubes of the present invention is connected in parallel with one diode.
  • the term "bidirectional switch” refers to a switch that can flow in both directions but can only withstand unidirectional voltage, such as with an anti-parallel diode. IGBT, or MOSFET with built-in parallel diode.
  • the switch transistor can also be implemented with other transistors, such as an NPN transistor.
  • the first terminal refers to the collector
  • the second terminal refers to the emitter
  • the control terminal refers to the base.
  • the switching transistor in the present invention is not limited to a MOSFET or an NPN transistor. That is to say, the switch tube of the present invention can also adopt other controllable (on and off) switch tube devices.
  • the photovoltaic array PV is connected in parallel with two capacitors connected in series, that is, a first capacitor C 1 and a second capacitor C 2 .
  • the first capacitor C 1 serves as a first DC power source
  • the second capacitor C 2 serves as a second DC power source.
  • the cathode of the first capacitor C 1 is connected to the anode of the second capacitor C 2
  • the anode of the first capacitor C 1 is connected to the anode of the photovoltaic array PV
  • the cathode of the cathode 2 is connected to the cathode of the PV array PV.
  • the half-bridge inverter circuit unit includes a first module M1, the second circuit module M2 and a first inductor L 1.
  • the first circuit module M1 includes at least an upper input terminal I + , an intermediate input terminal I 0 , a lower input terminal I ⁇ , an output terminal A, a first switch circuit branch and a second switch circuit branch; wherein the upper input terminal I + connected to the first access terminal, the intermediate input terminal I 0 is connected to the third access terminal, the lower input terminal I - is connected to the second access terminal, and the output terminal A and the first inductor L 1
  • the first end (left end) is connected; for convenience, the first access end is also denoted as I + , and the second access end is also denoted as I - , and the third access end is denoted as I 0 .
  • the upper input terminal I + of the first circuit module M1 is connected to the positive pole of the first capacitor C 1 ; the intermediate input terminal I 0 is connected to the common end of the first capacitor C 1 and the second capacitor C 2 ; the lower input terminal I - is connected The cathode of the second capacitor C 2 .
  • the first switching circuit branch of the first circuit module M1 is disposed between the upper input terminal I + and the output terminal A of the first circuit module M1, and the second switching circuit branch of the first circuit module M1 is disposed in the first circuit module M1 is the input terminal I - and between the output terminal a, so that the first input circuit module M1 can be different according to various control signals with the control terminal is connected, at least the following two states: the first is only turned on a connection between the first end of the inductor and the first access end; only the connection between the first end and the second access end of the first inductor is turned on.
  • the first circuit module M1 may further include a third switching circuit branch.
  • the third switching circuit branch of the first circuit module M1 is disposed between the intermediate input terminal I 0 and the output terminal A of the first circuit module M1. This enables the first circuit module M1 to also turn the connection between the intermediate input terminal I 0 and the output terminal A on or off according to the control signal input from the connected control terminal.
  • the second module M2 includes a circuit input terminal B, the first output terminals C, D of the second output terminal, a first branch and a second switch switching branch, a first input terminal B connected to a second end of the inductor L (1 the right end of the first inductor L 1), a first output terminal C of the above-described first voltage output terminal connected to a second output terminal D connected to said second voltage output terminal.
  • the first output terminal C of the second circuit module M2 is connected to the common end of the first capacitor C 1 and the second capacitor C 2 , or the second output terminal D of the second circuit module M2 is connected to the first capacitor C 1 and the second The common end of capacitor C 2 .
  • the first output terminal C and the second output terminal D of the second circuit module M2 are both connected to the AC grid as an AC terminal.
  • the first switching branch of the second circuit module M2 is disposed between the input terminal B of the second circuit module M2 and the first output terminal C; the second switching branch is disposed at the input terminal B and the second of the second circuit module M2
  • the second circuit module M2 can provide at least the following two working states according to the different control signals input to the respective control terminals connected: only the second end of the first inductor and the first voltage are turned on. a connection between the outputs; only the connection between the second end of the first inductor and the second voltage output is turned on.
  • the first inductor L 1 is connected between the output terminal A of the first circuit module M1 and the input terminal B of the second circuit module M2.
  • the first inductor L 1 is used to filter out high frequency harmonics to obtain a load current of almost sinusoidal waveform.
  • FIG. 4(a) is a schematic diagram showing a first circuit principle of the first circuit module M1 according to an embodiment of the present invention.
  • the first circuit module M1 includes a first bidirectional switch T 41a and a second bidirectional switch T 42a .
  • the first end of the first bidirectional switch T 41a is connected to the upper input terminal I + of the first circuit module M1 , and the second end of the first bidirectional switch T 41a is simultaneously connected to the output terminal A and the second bidirectional switch T of the first circuit module M1 .
  • the first end of 42a is connected to the lower input terminal I - of the first circuit module M1.
  • the first switching circuit branch of the first circuit module M1 includes a first bidirectional switch T 41a and the second switching circuit branch includes a second bidirectional switch T 42a .
  • FIG. 4(b) is a schematic diagram showing a second circuit principle of the first circuit module M1 according to an embodiment of the present invention.
  • the first circuit module M1 includes a first bidirectional switch T 41b , a second bidirectional switch T 42b , a third bidirectional switch T 43b , a fourth bidirectional switch T 44b , a first diode D 41b and a second diode D 42b .
  • the first end of the first bidirectional switch T 41b is connected to the upper input terminal I + of the first circuit module M1 ; the second end of the first bidirectional switch T 41b is simultaneously connected to the negative pole of the first diode D 41b and the second bidirectional switch T 42b a first end; a second end of the second bidirectional switch 42b while the T connection T 43b of the third bidirectional switch and a first terminal of a first output terminal of circuit block a M1; T 43b of the third bidirectional switch while the second end connecting a first end of the second diode D 42b and the fourth positive T 44b of the bidirectional switch; T 44b of the fourth bidirectional switch connecting a second terminal of the first circuit module M1 at the input terminals I -; a first diode
  • the anode of D 41b is connected to the cathode of the second diode D 42b ; the common terminal of the first diode D 41b and the second diode D 42b is connected to the intermediate input terminal I 0 of the
  • the first switching circuit branch of the first circuit module M1 includes a first bidirectional switch T 41b and a second bidirectional switch T 42b.
  • the second switching circuit branch includes a third bidirectional switch T 43b and a fourth bidirectional switch T 44b .
  • the third switching circuit branch includes a first diode D 41b and a second bidirectional switch T 42b or a second diode D 42b and a third bidirectional switch T 43b .
  • FIG. 4(c) is a schematic diagram showing a third circuit principle of the first circuit module M1 according to an embodiment of the present invention.
  • the first circuit module M1 includes a first bidirectional switch T 41c , a second bidirectional switch T 42c , a third bidirectional switch T 43c , and a fourth bidirectional switch T 44c .
  • the first end of the first bidirectional switch T 41c is connected to the upper input terminal I + of the first circuit module M1 ; the second end of the first bidirectional switch T 41c is simultaneously connected to the output terminal A and the fourth bidirectional switch T of the first circuit module M1 44c the first end; a second end of the fourth T bidirectional switch circuit 44c is connected to a first input terminal of the module M1 is the I -; a first end of the second bidirectional switch T 42c is connected to the intermediate circuit module M1 is a first input terminal I 0; a second end of the second bidirectional switch T 42c connected to the second terminal of the third bidirectional switch T 43c; a third bidirectional switch T 43c of the first terminal connected to the output terminal of the first circuit block M1 is A.
  • the first switching circuit branch of the first circuit module M1 comprises a first bidirectional switch T 41c .
  • the second switching circuit branch includes a fourth bidirectional switch T 44c .
  • the third switching circuit branch includes a second bidirectional switch T 42c and a third bidirectional switch T 43c .
  • FIG. 4(d) is a schematic diagram showing a fourth circuit principle of the first circuit module M1 according to an embodiment of the present invention.
  • the first circuit module M1 includes a first bidirectional switch T 41d , a second bidirectional switch T 42d , a third bidirectional switch T 43d , a first diode D 41d , a second diode D 42d , and a third diode D 43d , fourth diode D 44d .
  • the first end of the first bidirectional switch T 41d is connected to the upper input terminal I + of the first circuit module M1 ; the second end of the first bidirectional switch T 41d is simultaneously connected to the output terminal A and the third bidirectional switch T of the first circuit module M1 43d is a first end; a second terminal of the third bidirectional switch T circuit 43d is connected to a first input terminal of the module M1 is the I -; D anode of the first diode connected to the second diode 41d, while the anode 42d and D
  • the anode of 42d is simultaneously connected to the anode of the fourth diode D 44d and the second end of the second bidirectional switch T 42d ; the anode of the third diode D 43d is
  • the first switching circuit branch of the first circuit module M1 includes a first bidirectional switch T 41d .
  • the second switching circuit branch includes a third bidirectional switch T 43d .
  • the third switching circuit branch includes a first diode D 41d , a fourth diode D 44d , and a second bidirectional switch T 42d , or includes a second diode D 42d , a third diode D 43d , and a second Bidirectional switch T 42d .
  • FIG. 5(a) is a schematic diagram showing a first circuit principle of the second circuit module M2 according to an embodiment of the present invention.
  • the second circuit module M2 includes a first bidirectional switch T 51a , a second bidirectional switch T 52a , and first to eighth diodes D 51a to 58a .
  • the cathode of the first diode D 51a is simultaneously connected to the cathode of the third diode D 53a and the first end of the first bidirectional switch T 51a ;
  • the anode of the first diode D 51a is simultaneously connected to the second diode D 52a a negative pole and a first output terminal C of the second circuit module M2;
  • a positive pole of the second diode D 52a is simultaneously connected to the anode of the fourth diode D 54a and the second end of the first bidirectional switch T 51a ;
  • the anode of the pole D 53a is simultaneously connected to the cathode of the fourth diode D 54a and the input terminal B of the second circuit module M2;
  • the cathode of the fifth diode D 55a is simultaneously connected to the cathode of the seventh diode D 57a and the a first end of the two bidirectional switch T 52a ;
  • a positive pole of the fifth diode D 55a is simultaneously connected to
  • the first switching branch of the second circuit module M2 includes a first bidirectional switch T 51a , a second diode D 52a and a third diode D 53a , or includes a first bidirectional switch T 51a , a first diode D 51a and fourth diode D 54a .
  • the second switching branch includes a fifth diode D 55a , an eighth diode D 58a , and a second bidirectional switch T 52a , or includes a sixth diode D 56a , a seventh diode D 57a , and a second bidirectional Switch T 52a .
  • FIG. 5(b) is a schematic diagram showing a second circuit principle of the second circuit module M2 according to an embodiment of the present invention.
  • the second circuit module M2 includes a first bidirectional switch T 51b , a second bidirectional switch T 52b , a third bidirectional switch T 53b , and a fourth bidirectional switch T 54b .
  • the first end of the first bidirectional switch T 51b is connected to the first output terminal C of the second circuit module M2; the second end of the first bidirectional switch T 51b is connected to the second end of the second bidirectional switch T 52b ; the second bidirectional switch T a first end 52b while the third bidirectional switch T 53b connected to an input terminal B of the first end and a second circuit module M2; a third bidirectional switch T 53b connecting the second end of the fourth bidirectional switch T 54b of the second end; The first end of the fourth bidirectional switch T 54b is connected to the second output terminal D of the second circuit module M2.
  • the first switching branch of the second circuit module M2 includes a first bidirectional switch T 51b and a second bidirectional switch T 52b .
  • the second switching branch includes a third bidirectional switch T 53b and a fourth bidirectional switch T 54b .
  • FIG. 5(c) is a schematic diagram showing a third circuit principle of the second circuit module M2 according to an embodiment of the present invention.
  • the second circuit module M2 includes a first bidirectional switch T 51c , a second bidirectional switch T 52c , a third bidirectional switch T 53c , a fourth bidirectional switch T 54c , a first diode D 51c , and a second diode D 52c , a third diode D 53c and a fourth diode D 54c .
  • the first end of the first bidirectional switch T 51c is simultaneously connected to the negative pole of the third diode D 53c and the first output terminal C of the second circuit module M2; the second end of the first bidirectional switch T 51c is connected to the first diode D 51c of the positive electrode; cathode of the first diode D 51c connected to input terminal B, while a second bidirectional switch T 52c of the first and second circuit module M2; a second end connected to the second T 52c of the second bidirectional switch 52c of the anode of the diode D; a second end of the third diode D connected to the positive electrode of the third bidirectional switch 53c 53c of the T; T a first terminal of the third bidirectional switch 53c while the negative electrode 54c connected to the fourth diode D and an input terminal B of the second circuit module M2; a second end 54c of the fourth diode D is connected to the positive electrode of the fourth bidirectional switch T 54c; T 54c of the fourth bidirectional switch connected to a first terminal
  • the first switching branch of the second circuit module M2 includes a first bidirectional switch T 51c and a first diode D 51c or a third bidirectional switch T 53c and a third diode D 53c .
  • the second switching branch includes a second bidirectional switch T 52c and a second diode D 52c or a fourth diode D 54c and a fourth bidirectional switch T 54c .
  • FIG. 5(d) is a schematic diagram showing a fourth circuit principle of the second circuit module M2 according to an embodiment of the present invention.
  • the second circuit module M2 includes a first reverse resistance type IGBT and a second reverse resistance type IGBT.
  • the first reverse resistance type IGBT is connected between the input terminal B of the second circuit module M2 and the first output terminal C; the second reverse resistance type IGBT is connected to the input terminal B and the second output terminal D of the second circuit module M2. between.
  • the first switching branch of the second circuit module M2 comprises a first reverse-resistance type IGBT.
  • the second switching branch includes a second reverse resistance type IGBT.
  • the reverse resistance type IGBT in FIG. 5(d) is used as a switching tube representing a current bidirectional controllable
  • Other current bidirectional controllable switch tubes can be used instead.
  • the half bridge inverter unit further includes a second inductance L 2 .
  • the second inductor L 2 is connected between the second output terminal D and the AC grid G and the first output terminal C of the second circuit module M2 is connected to the common end of the first DC power source and the second DC power source; or, the second inductor L 2 is connected between the first output terminal C of the second circuit module M2 and the AC grid G and the second output terminal D of the second circuit module M2 is connected to the common terminal of the first DC power source and the second DC power source.
  • the second inductance L 2 is used to filter out high frequency harmonics to obtain a load current of almost sinusoidal waveform.
  • the half bridge inverter unit further includes a third capacitor C 3 .
  • the third capacitor C 3 is connected between the first output terminal C and the second output terminal D of the second circuit module M2.
  • the third capacitor C 3 is used to filter out high frequency harmonics to obtain a load current of almost sinusoidal waveform.
  • the unit comprises a half-bridge inverter circuit and any one of FIGS. 4 (a) to 4 (d) 5 in combination (a) any one of the circuit in (d) to FIG. 5 and the first inductance of L 1 .
  • the half bridge inverter unit is typically used in conjunction with the first capacitor C 1 and the second capacitor C 2 .
  • the half bridge inverter unit may further include a second inductance L 2 , and/or a third capacitance C 3 .
  • FIG. 7, FIG. 8 and FIG. 9 respectively show circuit schematic diagrams of four single-phase half-bridge inverters provided by embodiments of the present invention. 6, 7, 8 and 9, the first inductor L 1 and the second inductor L 2 share a core, reducing cost and size.
  • FIG single-phase half-bridge inverter shown in FIG. 6 includes 4 (a) a first circuit block M1, FIG. 5 (a) in a second circuit module M2, a first inductor L 1, a second inductor L 2 and a third capacitor C 3 . 6, the lower terminal of the third capacitor C 3 is connected to a first capacitor and a second capacitor C C. 1 common terminal 2, and the second terminal of inductor L 2 and the AC power grid connected to the third capacitance C 3 is between.
  • FIG. 7 is different from FIG. 6 in that the single-phase half-bridge inverter shown in FIG. 7 includes the second circuit module M2 in FIG. 5(b).
  • 8 is different from FIG. 6 in that the upper terminal of the third capacitor C 3 in FIG. 8 is connected to the common terminal of the first capacitor C 1 and the second capacitor C 2 and the second inductor L 2 is connected to the third capacitor C.
  • the single-phase half-bridge inverter shown in FIG. 9 includes the second circuit module M2 in FIG. 5(b).
  • a single-phase half-bridge inverter provided by an embodiment of the present invention includes one of the half-bridge inverter unit and a controller. Wherein the controller provides a drive control signal for each of the two-way inverter units.
  • the single-phase half-bridge inverter shown in FIG. 10 is taken as an example to illustrate its working principle.
  • FIG. 10 is a schematic diagram showing the circuit principle of a single-phase half-bridge inverter provided by an embodiment of the present invention.
  • the single-phase half-bridge inverter comprising a controller and a (a) circuit
  • FIG. 5 (a) containing a circuit 4 a first half-bridge inductor L 1, the second inductor L 2 and the third capacitance C 3 is Inverter unit.
  • the single-phase half-bridge inverter is used in combination with the first capacitor C 1 and the second capacitor C 2 .
  • the second inductor L 2 is connected between the first output terminal C of the second circuit module M2 and the first end of the AC grid, and the second output terminal D of the second circuit module M2 is simultaneously connected to the second end of the AC grid and the first capacitor C. 1.
  • the common end of the second capacitor C 2 .
  • the DC output voltage of the photovoltaic array (ie, the DC power source) is U pv .
  • the capacitance value of the first capacitor C 1 is equal to the capacitance value of the second capacitor C 2 .
  • the present invention does not limit the magnitude relationship between the capacitance value of the first capacitor C 1 and the capacitance value of the second capacitor C 2 .
  • the first capacitor C 1 voltage and the second capacitor C 2 voltage are both equal to 0.5 U PV .
  • the first inductor L 1 current in the circuit of Figure 11 is defined to flow from left to right as a forward current and vice versa.
  • the term "U m" means the minimum input voltage of a single-phase half-bridge inverter. According to this embodiment, the minimum input voltage U m is equal to the peak-to-peak value of the grid voltage.
  • FIG. 11 is a first operational modal diagram of a single-phase half-bridge inverter provided by an embodiment of the present invention.
  • the forward current path is: X ⁇ C 1 ⁇ P ⁇ T 41a ⁇ L 1 ⁇ D 53a ⁇ T 51a ⁇ D 52a ⁇ L 2 ⁇ G ⁇ X;
  • the negative current path is: X ⁇ G ⁇ L 2 ⁇ D 51a ⁇ T 51a ⁇ D 54a ⁇ L 1 ⁇ T 41a ⁇ C 1 ⁇ X.
  • FIG. 12 is a second operational modal diagram of a single-phase half-bridge inverter provided by an embodiment of the present invention.
  • the forward current path is: X ⁇ C 2 ⁇ N ⁇ T 42a ⁇ L 1 ⁇ D 53a ⁇ T 51a ⁇ D 52a ⁇ L 2 ⁇ G ⁇ X.
  • the negative current path is: X ⁇ G ⁇ L 2 ⁇ D 51a ⁇ T 51a ⁇ D 54a ⁇ L 1 ⁇ T 42a ⁇ C 2 ⁇ X.
  • FIG. 13 is a third operational modal diagram of a single-phase half-bridge inverter provided by an embodiment of the present invention.
  • the forward current path is: X ⁇ C 1 ⁇ P ⁇ T 41a ⁇ L 1 ⁇ D 55a ⁇ T 52a ⁇ D 58a ⁇ X.
  • the negative current path is: X ⁇ D 57a ⁇ T 52a ⁇ D 56a ⁇ L 1 ⁇ T 41a ⁇ P ⁇ C 1 ⁇ X.
  • FIG. 14 is a fourth operational modal diagram of a single-phase half-bridge inverter provided by an embodiment of the present invention.
  • the forward current path is: X ⁇ C 2 ⁇ N ⁇ T 42a ⁇ L 1 ⁇ D 55a ⁇ T 52a ⁇ D 58a ⁇ X.
  • the negative current path is: X ⁇ D 57a ⁇ T 52a ⁇ D 56a ⁇ L 1 ⁇ T 42a ⁇ C 2 ⁇ X.
  • the single-phase half-bridge inverter By controlling the corresponding switch tube to be turned on or off, the single-phase half-bridge inverter is alternately operated in the above four working modes, and finally the required inverter output voltage is obtained.
  • the terms "a”, “b”, “c”, “d” are used to denote the above four operating modes of a single-phase half-bridge inverter, respectively.
  • FIG. 15 is a schematic diagram showing a first modulation strategy of a single-phase half-bridge inverter provided by an embodiment of the present invention. At this time, the DC power supply voltage U pv is smaller than the minimum input voltage U m .
  • the absolute value of the grid voltage is less than 0.5 U pv .
  • the single-phase half-bridge inverter alternately operates in the first operating mode a and the second operating mode b, and operates in a buck mode.
  • the grid voltage is positive for half a week, the grid voltage is greater than 0.5 U pv but less than 0.5 U m , and the single-phase half-bridge inverter alternately operates in the first working mode a and the third working mode c, Run in boost mode.
  • the grid voltage is negative for half a week, the absolute value of the grid voltage is greater than 0.5 U pv but less than 0.5 U m , and the single-phase half-bridge inverter alternately operates in the second working mode b and the fourth working mode. d, running in boost mode.
  • the second inductor L 2 described above is not necessarily a structure, and in practical applications, the capacitor C 3 is not The structure that must be set.
  • the first capacitor C 1 and the second capacitor C 2 are only for providing a DC source. In a specific application, it is not necessary to provide a structure. For example, in some alternative embodiments, other DC sources may be provided to be connected to the above.
  • the first access terminal, the second access terminal, and the third access terminal are used instead of the first capacitor C 1 and the second capacitor C 2 .
  • FIG. 16 is a schematic diagram showing a second modulation strategy of a single-phase half-bridge inverter provided by an embodiment of the present invention.
  • the DC power supply voltage U pv is greater than the minimum input voltage U m .
  • the single-phase half-bridge inverter alternately operates in the first working mode a and the second working mode b throughout the duty cycle, and operates in a buck mode.
  • the single-phase half-bridge inverter unit can operate in a buck mode or a boost mode according to a specific modulation mode, which satisfies the requirements of the wide input voltage range of the inverter. Therefore, a single-phase half-bridge inverter can be used in the case where multiple photovoltaic arrays are connected in series.
  • the plurality of photovoltaic arrays are connected to the half bridge inverter unit by a bidirectional DC-DC converter.
  • the half-bridge inverter unit is connected in parallel with two capacitors connected in series. The number of photovoltaic cells of each of the plurality of photovoltaic arrays may or may not be equal. Therefore, the system efficiency is improved and the cost is reduced.
  • the bidirectional DC-DC converter is used to implement the function of each PV array MPPT.
  • the bidirectional DC-DC converter includes N capacitors (ie, C N1 , . . . , C NN ), N bidirectional switches (ie, T N1 , . . . , T NN ), and (N ⁇ 1) inductors ( That is, L (N-1)1 , ..., L (N-1) (N-1) ).
  • One capacitor is connected in parallel to each PV array.
  • the first end of the first bidirectional switch T N1 is simultaneously connected to the anode of the first photovoltaic array and the anode of the first capacitor C 1 .
  • the second end of the first bidirectional switch T N1 is connected to the common end of the first photovoltaic array and the second photovoltaic array through the first inductance L (N-1)1 .
  • the second end of the first bidirectional switch T N1 is connected to the first end of the second bidirectional switch T N2 .
  • the second end of the second bidirectional switch T N2 is connected to the common end of the second photovoltaic array and the third photovoltaic array through the second inductance L (N-1) 2 while also connecting the first end of the third bidirectional switch T N3 .
  • the interconnection between the other bidirectional switches other than the Nth bidirectional switch T NN and other devices is the same as that described above.
  • the first end of the Nth bidirectional switch T NN is connected to the second end of the (N-1)th bidirectional switch T N(N-1) , and also passes through the (N-1)th inductor L (N-1) (N-1) connecting the common ends of the (N-1)th photovoltaic array and the Nth photovoltaic array.
  • the second end of the Nth bidirectional switch T NN is simultaneously connected to the negative pole of the Nth photovoltaic array and the negative pole of the second capacitor C 2 .
  • FIG. 18 is a schematic diagram showing the circuit principle of a first-phase half-bridge inverter applied to a photovoltaic system having two photovoltaic arrays according to an embodiment of the present invention.
  • the bidirectional DC-DC converter includes two capacitors (i.e., C 21 , C 22 ), an inductor L 11 , a first bidirectional switch T 21 , and a second bidirectional switch T 22 .
  • One capacitor is connected in parallel to each PV array.
  • the first end of the first bidirectional switch T 21 is simultaneously connected to the anode of the first photovoltaic array and the upper input terminal I + of the first circuit module M1.
  • the second end of the first bidirectional switch T 21 is connected to the common end of the first photovoltaic array and the second photovoltaic array through the first inductance L 11 .
  • the second end of the first bidirectional switch T 21 is connected to the first end of the second bidirectional switch T 22 .
  • the second end of the second bidirectional switch T 22 is simultaneously connected to the negative pole of the second photovoltaic array and the lower input terminal I - of the first circuit module M1.
  • the first output terminal C of the second circuit module M2 is connected to the AC grid through the second inductor L 2 , and the second output terminal D is simultaneously connected to the AC grid and the common ends of the first capacitor C 1 and the second capacitor C 2 .
  • FIG. 19 is a schematic diagram showing the circuit principle of a second-phase half-bridge inverter applied to a photovoltaic system having two photovoltaic arrays according to an embodiment of the present invention.
  • the bidirectional DC-DC converter in FIG. 19 and the bidirectional DC-DC converter circuit in FIG. 18 have the same composition and connection manner, and are not described again for brevity.
  • 19 is different from FIG. 18 in that the first output terminal C of the second circuit module M2 in FIG. 19 is connected to the common terminal of the first capacitor C 1 and the second capacitor C 2 , and the second output terminal D passes the The second inductor L 2 is connected to the AC grid.
  • one terminal of the AC power grid is connected to the midpoint of the DC power source, so that the parasitic capacitance voltage is constant, thereby completely eliminating leakage current.
  • Figure 20 (a) is an equivalent block diagram of a single-phase half-bridge inverter when the second output terminal D of the second circuit module M2 is connected to the common terminal of the first capacitor C 1 and the second capacitor C 2 .
  • Fig. 20 (b) is an equivalent block diagram of the single-phase half-bridge inverter when the first output terminal C of the second circuit module M2 is connected to the common terminal of the first capacitor C 1 and the second capacitor C 2 .
  • the half bridge inverter unit is equivalent to the circuit module M.
  • the upper input terminal I + of the first circuit module M1, the intermediate input terminal I 0 and the lower input terminal I - respectively serve as an upper input terminal, an intermediate input terminal and a lower input terminal of the circuit module M.
  • the first output terminal C and the second output terminal D of the second circuit module M2 serve as a first output terminal and a second output terminal of the circuit module M, respectively.
  • the present invention also provides a three-phase half-bridge inverter as shown in Figures 21(a), 21(b), 21(c) and 21(d).
  • the three-phase half-bridge inverter includes three circuit modules M and one controller.
  • the three circuit modules M share the first capacitor C 1 and the second capacitor C 2 .
  • the controller provides a drive control signal for each of the three circuit modules M.
  • the input circuit all the three modules M are connected to the positive terminal of the first capacitor C 1; and all three of the intermediate circuit module M are connected to an input terminal of a first capacitor C 1 and the second a common end of the capacitor C 2 ; all the lower input terminals of the three circuit modules M are connected to the negative pole of the second capacitor C 2 ;
  • the three first output terminals of the three circuit modules M respectively pass the second inductor L 2 Connecting the three phases of the AC grid and the three second output terminals of the three circuit modules M are connected to the common ends of the first capacitor C 1 and the second capacitor C 2 (FIG.
  • the three second output terminals of the three circuit modules M are respectively connected to the three phases of the AC power grid through the second inductor L 2 and the three first output terminals of the three circuit modules M are connected to the first capacitor C 1 and the common terminal of the second capacitor C 2 (Fig. 21 (b) or 21 (d)).
  • the neutral end of the AC power grid is connected to the common terminal of the first capacitor C 1 and the second capacitor C 2 to constitute a three-phase four-wire system.
  • the neutral end of the AC power grid is not connected to the common terminal of the first capacitor C 1 and the second capacitor C 2 to constitute a three-phase three-wire system.
  • the absolute value of the grid voltage is positive and negative half-cycle symmetrical, so the midpoint voltages of the two series capacitors in parallel with the DC power supply are automatically balanced.
  • the inverter adopts a single-stage structure, which has low power consumption, low cost, high efficiency and high stability.
  • the present invention provides a half-bridge inverter unit and an inverter that can be used, but is not limited to, a renewable energy system, such as a single-phase or three-phase grid-connected photovoltaic system.
  • the above is only a specific embodiment of the present invention, and it should be noted that those skilled in the art can make some improvements and refinements without departing from the principles of the present invention, for example, according to the present embodiment.
  • the topological circuit in the example utilizes the topology obtained by the symmetry characteristic, and these improvements and retouchings should also be regarded as the protection scope of the present invention.

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Abstract

一种半桥逆变器单元及逆变器。半桥逆变器单元包括逆变控制模块和电感(L1)，逆变控制模块能够响应于不同的工作模态提供不同的连接状态，从而使得相应的半桥逆变器单元可以运行在降压模式或者升压模式，满足了宽输入电压范围的要求。利用电网电压正负半周对称的特性，解决了与直流电源并联的两串联电容中点电压平衡的问题。该半桥逆变器单元采用单级结构，功耗小，成本低，效率高，稳定性高。

Description

半桥逆变器单元及逆变器
本申请要求2015年1月29日提交的美国临时专利申请US62/109,431的优先权，其公开内容整体并入于此作为参考。
技术领域
本发明涉及电力电子领域中的逆变器单元及逆变器，特别是半桥逆变器。
背景技术
随着全球能源和环境问题加剧，可再生能源发展迅速。光伏发电因其资源丰富，分布广泛，具有很好的发展前景。对于光伏发电系统来说，如何降低成本，提高效率成为光伏发电的重要课题。
在光伏发电系统中，逆变器用于将光伏阵列输出的直流电转化成交流电。并网逆变器可以分为隔离型并网逆变器和非隔离型并网逆变器两类。在隔离型并网逆变器中，变压器实现了电气隔离，确保了人身安全。但是，变压器的能量损耗和体积大，带来很多问题，比如效率低，功率密度低和成本高等。所以，非隔离型光伏并网逆变器成为主流。但在非隔离型光伏并网逆变器系统中，由于缺少了变压器的电气隔离而存在共模回路。该共模回路产生漏电流，从而危及设备和人身安全。因此，非隔离型并网逆变器中，漏电流是一个需要解决的重要问题。同时，高效率成为光伏产业的另一个目标。
由于光伏阵列的输出电压存在很大范围的波动，因此非隔离型光伏逆变器要满足宽范围输入电压的要求。然而，光伏系统中非隔离型逆变器存在正常工作最小输入电压。光伏阵列的输出电压可能小于逆变器的最小输入电压。因此，光伏逆变器系统中通常使用一个升压电路。
如图1所示，现有的光伏逆变器系统是两级电路。第一级是DC-DC 单元，该DC-DC单元通常采用一个升压电路来实现。第二级是DC-AC单元。当光伏阵列输出电压小于最小输入电压时，DC-DC单元工作以升高输入电压从而使DC-AC单元正常工作；当光伏阵列输出电压大于最小输入电压时，则DC-DC单元被旁路，DC-AC单元正常工作。所述两级电路串联连接，因此，降低了系统效率，增加了成本。
参考文献“Derivation,Analysis,and Implementation of a Boost–Buck Converter-Based High-Efficiency PV Inverter”中给出了图2所示的单级全桥逆变器。然而，该单级全桥逆变器在多光伏阵列的情况下成本高。另外，当多个光伏阵列中的光伏电池数目差异很大的时候，该单级全桥逆变器效率低。由于光伏阵列之间是并联连接，所以每个光伏阵列的输出电压要求相等。为此，每个光伏阵列的输出电压被不同程度地升高。这样降低了系统效率。本领域的技术人员都知道，全桥逆变器由于自身寄生因数的缘故很难完全消除高频漏电流。而且，全桥逆变器需要两个滤波电感且他们的磁芯不共用，因此成本高。
发明内容
本发明提供了一种半桥逆变器单元及逆变器，以解决现有技术中的上述问题。
为了让电流双向流动，每个开关管反向并联一个二极管。为了叙述方便，本申请中的术语“双向开关”指电流可以双向流动但只能承受单向电压的开关，比如带有反向并联二极管的IGBT，或内置并联二极管的MOSFET。
第一方面，本发明提供一种半桥逆变器单元，包括：逆变控制模块和第一电感；并具有第一接入端、第二接入端、第三接入端、第一电压输出端和第二电压输出端以及若干控制端；
所述逆变控制模块连接第一接入端、第二接入端、第三接入端、第一电压输出端、第二电压输出端、电感的第一端和电感的第二端七个端子，并连接所述若干控制端；用于根据第一工作模态下输入到各 个控制端的控制信号，针对所述七个端子，导通第一电感的第一端与第一接入端之间的连接以及第一电感的第二端与第一电压输出端之间的连接，并断开其他的端到端连接；根据第二工作模态下输入到各个控制端的控制信号，针对所述七个端子，导通第一电感的第一端与第二接入端之间的连接以及第一电感的第二端与第一电压输出端之间的连接；根据第三工作模态下输入到各个控制端的控制信号，针对所述七个端子，导通第一电感的第一端与第一接入端之间的连接以及第一电感的第二端与第二电压输出端之间的连接；根据第四工作模态下输入到各个控制端的控制信号，针对所述七个端子，导通第一电感的第一端与第二接入端之间的连接以及第一电感的第二端与第二电压输出端之间的连接。
第二方面，本发明提供一种单相半桥逆变器。
所述单相半桥逆变器包括第一方面所述的半桥逆变器单元和一个控制器；其中，所述控制器与所述半桥逆变器单元的若干个控制端相连，用于为所述半桥逆变器单元提供各个工作模态对应的控制信号。
第三方面，本发明提供一种三相半桥逆变器。
所述三相半桥逆变器，包括一个控制器和三个第一方面提供的半桥逆变器单元其中，其中，各个半桥逆变器单元的第一接入端相互连接，第二接入端相互连接，第三接入端相互连接；各个半桥逆变器单元的第一电压输出端一对一连接所述三相半桥逆变器的一个相位的交流负载接入端；
所述控制器与每一个半桥逆变器单元中的各个控制端相连，用于为该半桥逆变器单元提供各个电平模式对应的控制信号。
本发明提供的半桥逆变器单元以及相应的逆变器，可以运行在降压模式或者升压模式，因此满足了逆变器宽输入电压范围的要求。利用电网电压正负半周对称的特性，解决了与直流电源并联的两串联电 容中点电压平衡的问题。该逆变器采用单级结构，功耗小，成本低，效率高，稳定性高。
本发明提供了一种半桥逆变器单元及逆变器，可以用于，但不限于，可再生能源系统，比如单相或三相并网光伏系统。
附图说明
通过参考附图会更加清楚的理解本发明的特征信息和优点，附图是示意性的而不应理解为对本发明进行任何限制，在附图中：
为了更全面地理解本发明的技术方案，对后面的实施例或现有技术描述中所需要使用的附图进行介绍如下。
图1为一种现有的两级逆变器系统的电路原理方框图；
图2为一种现有的单级全桥逆变器系统的电路原理示意图；
图3(a)为本发明实施例提供的第一种单相半桥逆变器的电路原理部分方框图；
图3(b)为本发明实施例提供的第二种单相半桥逆变器的电路原理部分方框图；
图4(a)为本发明实施例提供的第一电路模块M1的第一种电路原理示意图；
图4(b)为本发明实施例提供的第一电路模块M1的第二种电路原理示意图；
图4(c)为本发明实施例提供的第一电路模块M1的第三种电路原理示意图；
图4(d)为本发明实施例提供的第一电路模块M1的第四种电路原理示意图；
图5(a)为本发明实施例提供的第二电路模块M2的第一种电路原理示意图；
图5(b)为本发明实施例提供的第二电路模块M2的第二种电路原理示意图；
图5(c)为本发明实施例提供的第二电路模块M2的第三种电路原理示意图；
图5(d)为本发明实施例提供的第二电路模块M2的第四种电路原理示意图；
图6为本发明实施例提供的第一种含有图4(a)中的第一电路模块M1和图5(a)中的第二电路模块M2且L1与L2共用磁芯的单相半桥逆变器电路原理示意图；
图7为本发明实施例提供的第一种含有图4(a)中的第一电路模块M1和图5(b)中的第二电路模块M2且L1与L2共用磁芯的单相半桥逆变器电路原理示意图；
图8为本发明实施例提供的第二种含有图4(a)中的第一电路模块M1和图5(a)中的第二电路模块M2且L1与L2共用磁芯的单相半桥逆变器电路原理示意图；
图9为本发明实施例提供的第二种含有图4(a)中的第一电路模块M1和图5(b)中的第二电路模块M2且L1与L2共用磁芯的单相半桥逆变器电路原理示意图；
图10为本发明实施例提供的一种含有图4(a)中的第一电路模块M1和图5(a)中的第二电路模块M2且L1与L2不共用磁芯的单相半桥逆变器电路原理示意图；
图11为本发明实施例提供的一种单相半桥逆变器的第一种工作模态示意图；
图12为本发明实施例提供的一种单相半桥逆变器的第二种工作模态示意图；
图13为本发明实施例提供的一种单相半桥逆变器的第三种工作模态示意图；
图14为本发明实施例提供的一种单相半桥逆变器的第四种工作模态示意图；
图15为本发明实施例提供的一种单相半桥逆变器的第一种调制策略示意图；
图16为本发明实施例提供的一种单相半桥逆变器的第二种调制策略示意图；
图17为本发明实施例提供的一种应用于具有多光伏阵列的光伏系统的单相半桥逆变器的电路原理示意图；
图18为本发明实施例提供的第一种应用于具有两个光伏阵列的光伏系统的单相半桥逆变器的电路原理示意图；
图19为本发明实施例提供的第二种应用于具有两个光伏阵列的光伏系统的单相半桥逆变器的电路原理示意图；
图20(a)为本发明实施例提供的第一种单相半桥逆变器的等效方框图；
图20(b)为本发明实施例提供的第二种单相半桥逆变器的等效方框图；
图21(a)为本发明实施例提供的第一种三相半桥逆变器的电路原理方框图；
图21(b)为本发明实施例提供的第二种三相半桥逆变器的电路原理方框图；
图21(c)为本发明实施例提供的第三种三相半桥逆变器的电路原理方框图；
图21(d)为本发明实施例提供的第四种三相半桥逆变器的电路原理方框图。
为了叙述方便，在各个附图中同一元器件采用相同的参考标号。同一附图中相同的符号，比如
Figure PCTCN2016072701-appb-000001
表示相互连接在一起。
具体实施方式
本发明提供了一种半桥逆变器单元及逆变器。为了使本技术领域的人员更好地理解本发明中的技术方案及其如何实现，下面将结合本 发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述。显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都应当属于本发明保护的范围。
本发明提供的半桥逆变器单元，包括：
逆变控制模块和第一电感；并具有第一接入端、第二接入端、第三接入端、第一电压输出端和第二电压输出端以及若干控制端；
所述逆变控制模块连接第一接入端、第二接入端、第三接入端、第一电压输出端、第二电压输出端、电感的第一端和电感的第二端七个端子，并连接所述若干控制端；用于根据第一工作模态下输入到各个控制端的控制信号，针对所述七个端子，导通第一电感的第一端与第一接入端之间的连接以及第一电感的第二端与第一电压输出端之间的连接，并断开其他的端到端连接；根据第二工作模态下输入到各个控制端的控制信号，针对所述七个端子，导通第一电感的第一端与第二接入端之间的连接以及第一电感的第二端与第一电压输出端之间的连接；根据第三工作模态下输入到各个控制端的控制信号，针对所述七个端子，导通第一电感的第一端与第一接入端之间的连接以及第一电感的第二端与第二电压输出端之间的连接；根据第四工作模态下输入到各个控制端的控制信号，针对所述七个端子，导通第一电感的第一端与第二接入端之间的连接以及第一电感的第二端与第二电压输出端之间的连接。
本发明提供的半桥逆变器单元，通过对其中的逆变控制模块施加对应的控制信号进行控制，可以使得包含该半桥逆变器单元的半桥逆变器运行在降压模式或者升压模式，因此满足了逆变器宽输入电压范围的要求。利用电网电压正负半周对称的特性，解决了与直流电源并联的两串联电容中点电压平衡的问题。该逆变器采用单级结构，功耗 小，成本低，效率高，稳定性高。
在具体实施时，上述的逆变控制模块可以通过多种结构实施，比如一种最为直接的方式可以是，设置四个开关支路，其中第一开关支路连接在第一接入端与第一电感的第一端之间，第二开关支路连接在第二接入端与第一电感的第一端之间，第三开关支路连接在第一电感的第二端与第一电压输出端之间，第四开关支路连接在第一电感的第二端与第二电压输出端之间。下面主要结合附图对上述的逆变控制模块的一些可能的实施方式进行说明。同时为了方便说明，部分附图中还示出了除半桥逆变器单元之外的其他结构，比如用于构造直流源的电容、DC-DC变压器、光伏阵列等。
如图3所示，本发明中使用的术语“PV”表示光伏阵列(也就是直流电源)，UPV表示光伏阵列的输出电压，M1表示半桥逆变器单元中的第一电路模块，M2表示第二电路模块，C1表示第一电容(也就是第一直流电源)，C2表示第二电容(也就是第二直流电源)，C3表示第三电容，G表示交流电网。
显然，光伏阵列PV可以采用其它直流电源代替，也就是说，本发明中的直流电源不限定于PV。类似地，交流电网G可以采用其它交流负载代替，即本发明中的交流负载不限定于交流电网。
注意，二极管被用作代表单方向导通元件，但本发明中的单方向导通元件不限定于二极管。二极管的正极指阳极，负极指阴极。
开关MOSFET被用作代表本发明中的可控型(导通和关断)开关管。以N沟道MOSFET为例进行说明。N沟道MOSFET的第一端指漏极，第二端指源极，控制端指栅极。所述半桥逆变器单元中的每个开关管控制端施加一个驱动控制信号。简洁起见，后面不再赘述。
为了保证每个开关管中的电流双向流动，本发明中的每个开关管反向并联一个二极管。简洁起见，术语“双向开关”指电流可以双向流动但只能承受单向电压的开关，比如带有反向并联二极管的 IGBT，或内置并联二极管的MOSFET。
所述开关管也可以采用其他晶体管实现，比如，NPN型晶体管。对于NPN型晶体管，第一端指集电极，第二端指发射极，控制端指基极。显然，本发明中的开关管不限定于MOSFET或NPN型晶体管。也就是说，本发明中的开关管也可以采用其他可控型(导通和关断)开关管器件。
如图3所示，光伏阵列PV并联连接两个串联连接的电容，即第一电容C1、第二电容C2。其中，第一电容C1作为第一直流电源，第二电容C2作为第二直流电源。第一电容C1的负极连接第二电容C2的正极，第一电容C1的正极连接光伏阵列PV的正极，C2的负极连接光伏阵列PV的负极。所述半桥逆变器单元包括第一电路模块M1，第二电路模块M2和第一电感L1。
所述第一电路模块M1至少包括上输入端子I+、中间输入端子I0、下输入端子I-、输出端子A，第一开关电路支路和第二开关电路支路；其中上输入端子I+与上述的第一接入端相连，中间输入端子I0与上述的第三接入端相连、下输入端子I-与上述的第二接入端相连，输出端子A与第一电感L1的第一端(左端)相连；为了方便说明以下第一接入端也均表示为I+，同样的，第二接入端也均表示为I-，第三接入端均表示为I0。其中，第一电路模块M1的上输入端子I+连接第一电容C1的正极；中间输入端子I0连接第一电容C1与第二电容C2的公共端；下输入端子I-连接第二电容C2的负极。第一电路模块M1的第一开关电路支路设置在第一电路模块M1的上输入端子I+和输出端子A之间，第一电路模块M1的第二开关电路支路设置在第一电路模块M1的下输入端子I-和输出端子A之间，这样使得第一电路模块M1能够根据所连接的各个控制端输入接入的不同控制信号，提供至少以下两种工作状态：仅导通第一电感的第一端与第一接入端之间的连接；仅导通第一电感的第一端与第二接入端之间的连接。
在一些实施例中，所述第一电路模块M1还可以进一步包括第三开关电路支路。第一电路模块M1的第三开关电路支路设置在第一电路模块M1的中间输入端子I0和输出端子A之间。这样能够使得第一电路模块M1还能够根据所接入的控制端输入的控制信号将中间输入端子I0和输出端子A之间的连接导通或者关断。
所述第二电路模块M2包括输入端子B，第一输出端子C，第二输出端子D，第一开关支路和第二开关支路，输入端子B连接第一电感L1的第二端(第一电感L1的右端)，第一输出端子C与上述的第一电压输出端相连，第二输出端子D与上述的第二电压输出端相连。其中，第二电路模块M2的第一输出端子C连接第一电容C1与第二电容C2的公共端，或者第二电路模块M2的第二输出端子D连接第一电容C1与第二电容C2的公共端。第二电路模块M2的第一输出端子C和第二输出端子D均作为交流端子连接交流电网。第二电路模块M2的第一开关支路设置在第二电路模块M2的输入端子B和第一输出端子C之间；第二开关支路设置在第二电路模块M2的输入端子B和第二输出端子D之间，这样第二电路模块M2能够根据所连接的各个控制端输入接入的不同控制信号，提供至少以下两种工作状态：仅导通第一电感的第二端与第一电压输出端之间的连接；仅导通第一电感的第二端与第二电压输出端之间的连接。
第一电感L1连接在第一电路模块M1的输出端子A和第二电路模块M2的输入端子B之间。第一电感L1用于滤除高频谐波而得到几乎正弦波形的负载电流。
图4(a)示出了本发明实施例提供的所述第一电路模块M1的第一种电路原理示意图。所述第一电路模块M1包括第一双向开关T41a和第二双向开关T42a。
第一双向开关T41a的第一端连接第一电路模块M1的上输入端子I+，第一双向开关T41a的第二端同时连接第一电路模块M1的输出端子 A和第二双向开关T42a的第一端。第二双向开关T42a的第二端连接第一电路模块M1的下输入端子I-。
第一电路模块M1的第一开关电路支路包括第一双向开关T41a，第二开关电路支路包括第二双向开关T42a。
图4(b)示出了本发明实施例提供的所述第一电路模块M1的第二种电路原理示意图。所述第一电路模块M1包括第一双向开关T41b、第二双向开关T42b、第三双向开关T43b、第四双向开关T44b、第一二极管D41b和第二二极管D42b。
第一双向开关T41b的第一端连接第一电路模块M1的上输入端子I+；第一双向开关T41b的第二端同时连接第一二极管D41b的负极和第二双向开关T42b的第一端；第二双向开关T42b的第二端同时连接第三双向开关T43b的第一端和第一电路模块M1的输出端子A；第三双向开关T43b的第二端同时连接第二二极管D42b的正极和第四双向开关T44b的第一端；第四双向开关T44b的第二端连接第一电路模块M1的下输入端子I-；第一二极管D41b的正极连接第二二极管D42b的负极；第一二极管D41b和第二二极管D42b的公共端连接第一电路模块M1的中间输入端子I0。
第一电路模块M1的第一开关电路支路包括第一双向开关T41b和第二双向开关T42b。第二开关电路支路包括第三双向开关T43b和第四双向开关T44b。第三开关电路支路包括第一二极管D41b和第二双向开关T42b，或者包括第二二极管D42b和第三双向开关T43b。
图4(c)示出了本发明实施例提供的所述第一电路模块M1的第三种电路原理示意图。所述第一电路模块M1包括第一双向开关T41c、第二双向开关T42c、第三双向开关T43c和第四双向开关T44c。
第一双向开关T41c的第一端连接第一电路模块M1的上输入端子I+；第一双向开关T41c的第二端同时连接第一电路模块M1的输出端子A和第四双向开关T44c的第一端；第四双向开关T44c的第二端连接第一 电路模块M1的下输入端子I-；第二双向开关T42c的第一端连接第一电路模块M1的中间输入端子I0；第二双向开关T42c的第二端连接第三双向开关T43c的第二端；第三双向开关T43c的第一端连接第一电路模块M1的输出端子A。
第一电路模块M1的第一开关电路支路包括第一双向开关T41c。第二开关电路支路包括第四双向开关T44c。第三开关电路支路包括第二双向开关T42c和第三双向开关T43c。
图4(d)示出了本发明实施例提供的所述第一电路模块M1的第四种电路原理示意图。所述第一电路模块M1包括第一双向开关T41d、第二双向开关T42d、第三双向开关T43d、第一二极管D41d、第二二极管D42d、第三二极管D43d、第四二极管D44d。
第一双向开关T41d的第一端连接第一电路模块M1的上输入端子I+；第一双向开关T41d的第二端同时连接第一电路模块M1的输出端子A和第三双向开关T43d的第一端；第三双向开关T43d的第二端连接第一电路模块M1的下输入端子I-；第一二极管D41d的正极同时连接第二二极管D42d的负极和第一电路模块M1的中间输入端子I0；第一二极管D41d的负极同时连接第三二极管D43d的负极和第二双向开关T42d的第一端；第二二极管D42d的正极同时连接第四二极管D44d的正极和第二双向开关T42d的第二端；第三二极管D43d的正极同时连接第四二极管D44d的负极和第一电路模块M1的输出端子A。
第一电路模块M1的第一开关电路支路包括第一双向开关T41d。第二开关电路支路包括第三双向开关T43d。第三开关电路支路包括第一二极管D41d、第四二极管D44d和第二双向开关T42d，或者包括第二二极管D42d、第三二极管D43d和第二双向开关T42d。
图5(a)示出了本发明实施例提供的所述第二电路模块M2的第一种电路原理示意图。所述第二电路模块M2包括第一双向开关T51a、第二双向开关T52a、第一二极管D51a至第八二极管D58a。
第一二极管D51a的负极同时连接第三二极管D53a的负极和第一双向开关T51a的第一端；第一二极管D51a的正极同时连接第二二极管D52a的负极和第二电路模块M2的第一输出端子C；第二二极管D52a的正极同时连接第四二极管D54a的正极和第一双向开关T51a的第二端；第三二极管D53a的正极同时连接第四二极管D54a的负极和第二电路模块M2的输入端子B；第五二极管D55a的负极同时连接第七二极管D57a的负极和第二双向开关T52a的第一端；第五二极管D55a的正极同时连接第六二极管D56a的负极和第二电路模块M2的输入端子B；第六二极管D56a的正极同时连接第八二极管D58a的正极和第二双向开关T52a的第二端；第七二极管D57a的正极同时连接第八二极管D58a的负极和第二电路模块M2的第二输出端子D。
第二电路模块M2的第一开关支路包括第一双向开关T51a、第二二极管D52a和第三二极管D53a，或者包括第一双向开关T51a、第一二极管D51a和第四二极管D54a。第二开关支路包括第五二极管D55a、第八二极管D58a和第二双向开关T52a，或者包括第六二极管D56a、第七二极管D57a和第二双向开关T52a。
图5(b)示出了本发明实施例提供的所述第二电路模块M2的第二种电路原理示意图。所述第二电路模块M2包括第一双向开关T51b、第二双向开关T52b、第三双向开关T53b和第四双向开关T54b。
第一双向开关T51b的第一端连接第二电路模块M2的第一输出端子C；第一双向开关T51b的第二端连接第二双向开关T52b的第二端；第二双向开关T52b的第一端同时连接第三双向开关T53b的第一端和第二电路模块M2的输入端子B；第三双向开关T53b的第二端连接第四双向开关T54b的第二端；第四双向开关T54b的第一端连接第二电路模块M2的第二输出端子D。
第二电路模块M2的第一开关支路包括第一双向开关T51b和第二双向开关T52b。第二开关支路包括第三双向开关T53b和第四双向开关 T54b。
图5(c)示出了本发明实施例提供的所述第二电路模块M2的第三种电路原理示意图。所述第二电路模块M2包括第一双向开关T51c，第二双向开关T52c，第三双向开关T53c、第四双向开关T54c、第一二极管D51c、第二二极管D52c、第三二极管D53c和第四二极管D54c。
第一双向开关T51c的第一端同时连接第三二极管D53c的负极和第二电路模块M2的第一输出端子C；第一双向开关T51c的第二端连接第一二极管D51c的正极；第一二极管D51c的负极同时连接第二双向开关T52c的第一端和第二电路模块M2的输入端子B；第二双向开关T52c的第二端连接第二二极管D52c的正极；第三二极管D53c的正极连接第三双向开关T53c的第二端；第三双向开关T53c的第一端同时连接第四二极管D54c的负极和第二电路模块M2的输入端子B；第四二极管D54c的正极连接第四双向开关T54c的第二端；第四双向开关T54c的第一端同时连接第二二极管D52c的负极和第二电路模块M2的第二输出端子D。
第二电路模块M2的第一开关支路包括第一双向开关T51c和第一二极管D51c，或者包括第三双向开关T53c和第三二极管D53c。第二开关支路包括第二双向开关T52c和第二二极管D52c，或者包括第四二极管D54c和第四双向开关T54c。
图5(d)示出了本发明实施例提供的所述第二电路模块M2的第四种电路原理示意图。所述第二电路模块M2包括第一逆阻型IGBT和第二逆阻型IGBT。
第一逆阻型IGBT连接在第二电路模块M2的输入端子B和第一输出端子C之间；第二逆阻型IGBT连接在第二电路模块M2的输入端子B和第二输出端子D之间。
第二电路模块M2的第一开关支路包括第一逆阻型IGBT。第二开关支路包括第二逆阻型IGBT。
图5(d)中的逆阻型IGBT被用作代表电流双向可控的开关管，因此 可采用其它的电流双向可控的开关管代替。
所述半桥逆变器单元进一步包括第二电感L2。第二电感L2连接在第二输出端子D和交流电网G之间且第二电路模块M2的第一输出端子C连接第一直流电源和第二直流电源的公共端；或者，第二电感L2连接在第二电路模块M2的第一输出端子C和交流电网G之间且第二电路模块M2的第二输出端子D连接第一直流电源和第二直流电源的公共端。第二电感L2用于滤除高频谐波而得到几乎正弦波形的负载电流。
所述半桥逆变器单元进一步包括第三电容C3。第三电容C3连接在第二电路模块M2的第一输出端子C和第二输出端子D之间。第三电容C3用于滤除高频谐波而得到几乎正弦波形的负载电流。
所述半桥逆变器单元包括图4(a)至图4(d)中的任一个电路和图5(a)至图5(d)中的任一个电路以及第一电感L1的组合。所述半桥逆变器单元通常和所述第一电容C1、第二电容C2共同使用。所述半桥逆变器单元可以进一步包括第二电感L2，和/或第三电容C3。
图6，图7，图8和图9分别示出了本发明实施例提供的四种单相半桥逆变器的电路原理图。如图6，图7，图8和图9所示，第一电感L1和第二电感L2共用一个磁芯，减小了成本和体积。其中，图6所示的单相半桥逆变器包括图4(a)中的第一电路模块M1、图5(a)中的第二电路模块M2、第一电感L1、第二电感L2和第三电容C3。如图6所示，第三电容C3的下端子连接第一电容C1和第二电容C2的公共端，且第二电感L2连接在第三电容C3的上端子和交流电网之间。图7与图6的不同之处在于，图7所示的单相半桥逆变器包括图5(b)中的第二电路模块M2。图8与图6的不同之处在于，图8中的第三电容C3的上端子连接第一电容C1和第二电容C2的公共端且第二电感L2连接在第三电容C3的下端子和交流电网之间。图9与图8的不同之处在于，图9所示的单相半桥逆变器包括图5(b)中的第二电路模块M2。
本发明实施例提供的单相半桥逆变器，包括一个所述半桥逆变器单元和一个控制器。其中，所述控制器为所述半桥逆变器单元中的每一个双向开关提供驱动控制信号。以图10所示的单相半桥逆变器为例说明它的工作原理。
图10示出了本发明实施例提供的单相半桥逆变器的电路原理示意图。其中，单相半桥逆变器包括一个控制器和一个含有图4(a)电路、图5(a)电路、第一电感L1、第二电感L2和第三电容C3的半桥逆变器单元。该单相半桥逆变器和所述第一电容C1、第二电容C2共同使用。第二电感L2连接在第二电路模块M2的第一输出端子C和交流电网第一端之间且第二电路模块M2的第二输出端子D同时连接交流电网第二端和第一电容C1、第二电容C2的公共端。
根据本实施例，假设光伏阵列(即直流电源)的直流输出电压为Upv。假定第一电容C1的电容值等于第二电容C2的电容值。显然，本发明并不限定第一电容C1的电容值与第二电容C2的电容值之间的大小关系。根据本实施例的假定，第一电容C1电压和第二电容C2电压都等于0.5UPV。定义图11电路至图14电路中的第一电感L1电流从左向右流动为正向电流，反之为负向电流。简洁起见，术语“Um”表示单相半桥逆变器的最小输入电压。根据本实施例，最小输入电压Um等于电网电压的峰峰值。
图11给出了本发明实施例提供的单相半桥逆变器的第一工作模态图。如图11所示，正向电流路径为：X→C1→P→T41a→L1→D53a→T51a→D52a→L2→G→X；负向电流路径为：X→G→L2→D51a→T51a→D54a→L1→T41a→C1→X。
图12给出了本发明实施例提供的单相半桥逆变器的第二工作模态图。如图12所示，正向电流路径为：X→C2→N→T42a→L1→D53a→T51a→D52a→L2→G→X。负向电流路径为：X→G→L2→D51a→T51a→D54a→L1→T42a→C2→X。
图13给出了本发明实施例提供的单相半桥逆变器的第三工作模态图。如图13所示，正向电流路径为：X→C1→P→T41a→L1→D55a→T52a→D58a→X。负向电流路径为：X→D57a→T52a→D56a→L1→T41a→P→C1→X。
图14给出了本发明实施例提供的单相半桥逆变器的第四工作模态图。如图14所示，正向电流路径为：X→C2→N→T42a→L1→D55a→T52a→D58a→X。负向电流路径为：X→D57a→T52a→D56a→L1→T42a→C2→X。
通过控制相应的开关管导通或关断，使单相半桥逆变器在上述的四种工作模态下交替工作，最终获得需要的逆变输出电压。简洁起见，术语“a”、“b”、“c”、“d”分别被用来表示单相半桥逆变器的上述四个工作模态。
图15给出了本发明实施例提供的单相半桥逆变器的第一种调制策略示意图。此时，直流电源电压Upv小于最小输入电压Um。
如图15所示，to-t1、t2-t4、t5-t6时间段内，电网电压绝对值小于0.5Upv。单相半桥逆变器交替工作在第一工作模态a和第二工作模态b，运行在降压模式(Buck mode)。
t1-t2时间段内，电网电压正半周，电网电压大于0.5Upv但小于0.5Um，单相半桥逆变器交替工作在第一工作模态a和第三工作模态c，运行在升压模式(Boost mode)。
t4-t5时间段内，电网电压负半周，电网电压绝对值大于0.5Upv但小于0.5Um，单相半桥逆变器交替工作在第二工作模态b和第四工作模态d，运行在升压模式(Boost mode)。
通过对上述的各个工作模态下的工作流程的分析可以看出，在具体实施时，上述的第二电感L2并不是必须设置的结构，且在实际应用中，这里的电容C3也不是必须设置的结构。第一电容C1和第二电容C2仅是为了提供直流源，在具体应用时，也不是必须设置的结构，比如 在一些可替代的实施例中，可以提供其他直流源接入到上述的第一接入端、第二接入端和第三接入端的基础上以代替第一电容C1和第二电容C2。
图16给出了本发明实施例提供的单相半桥逆变器的第二种调制策略示意图。此时，直流电源电压Upv大于最小输入电压Um。单相半桥逆变器整个工作周期交替工作在第一工作模态a和第二工作模态b，运行在降压模式(Buck mode)。
从上述两种调制策略可以发现，根据具体的调制模式，所述单相半桥逆变器单元可以运行在降压模式或者升压模式，满足了逆变器宽输入电压范围的要求。因此，单相半桥逆变器可以用于多个光伏阵列串联连接的场合。所述多个光伏阵列通过一个双向DC-DC变换器连接所述半桥逆变器单元。其中，所述半桥逆变器单元并联连接两个串联连接的电容。所述多个光伏阵列中每个光伏阵列的光伏电池数目可以相等也可以不相等。因此，提高了系统效率，减小了成本。
所述双向DC-DC变换器用于实现每个光伏阵列MPPT的功能。
假定光伏阵列的数目为N。如图17所示，双向DC-DC变换器包括N个电容(即CN1，…，CNN)、N个双向开关(即TN1，…，TNN)和(N-1)个电感(即L(N-1)1，…，L(N-1)(N-1))。每个光伏阵列并联连接一个电容。第一双向开关TN1的第一端同时连接第一光伏阵列的正极和第一电容C1的正极。第一双向开关TN1第二端通过第一电感L(N-1)1连接第一光伏阵列和第二光伏阵列的公共端。同时，第一双向开关TN1的第二端连接第二双向开关TN2的第一端。第二双向开关TN2的第二端通过第二电感L(N-1)2连接第二光伏阵列和第三光伏阵列的公共端，同时还连接第三双向开关TN3的第一端。除第N个双向开关TNN之外的其它双向开关与其它器件之间的相互连接方式与上述连接方式相同。第N个双向开关TNN的第一端连接第(N-1)个双向开关TN(N-1)的第二端，同时还通过第(N-1)个电感L(N-1)(N-1)连接第(N-1)个光伏阵列和第 N个光伏阵列的公共端。第N个双向开关TNN的第二端同时连接第N个光伏阵列的负极和第二电容C2的负极。
图18给出了本发明实施例提供的第一种应用于具有两个光伏阵列的光伏系统的单相半桥逆变器的电路原理示意图。
如图18所示，双向DC-DC变换器包括两个电容(即C21，C22)、一个电感L11、第一双向开关T21和第二双向开关T22。每个光伏阵列并联连接一个电容。第一双向开关T21的第一端同时连接第一光伏阵列的正极和第一电路模块M1的上输入端子I+。第一双向开关T21的第二端通过第一电感L11连接第一光伏阵列和第二光伏阵列的公共端。同时，第一双向开关T21的第二端连接第二双向开关T22的第一端。第二双向开关T22的第二端同时连接第二光伏阵列的负极和第一电路模块M1的下输入端子I-。第二电路模块M2的第一输出端子C通过第二电感L2连接交流电网，且第二输出端子D同时连接交流电网和第一电容C1与第二电容C2的公共端。
图19给出了本发明实施例提供的第二种应用于具有两个光伏阵列的光伏系统的单相半桥逆变器的电路原理示意图。其中，图19中的双向DC-DC变换器与图18中的双向DC-DC变换器电路组成和连接方式完全相同，简洁起见，不再赘述。图19与图18的不同之处在于，图19中的第二电路模块M2的第一输出端子C连接第一电容C1与第二电容C2的公共端，且第二输出端子D通过第二电感L2连接交流电网。
由本发明实施例提供的附图和上述描述可知，交流电网的一个端子和直流电源的中点连接，使得寄生电容电压为常数，从而完全消除了漏电流。
图20(a)是当第二电路模块M2的第二输出端子D连接第一电容C1和第二电容C2公共端时的单相半桥逆变器的等效方框图。图20(b)是当第二电路模块M2的第一输出端子C连接第一电容C1和第二电容C2公共端时的单相半桥逆变器的等效方框图。所述半桥逆变器单元等效为 电路模块M。第一电路模块M1的上输入端子I+，中间输入端子I0和下输入端子I-分别作为电路模块M的上输入端子，中间输入端子和下输入端子。第二电路模块M2的第一输出端子C和第二输出端子D分别作为电路模块M的第一输出端子和第二输出端子。
本发明还提供了三相半桥逆变器，如图21(a)、图21(b)、21(c)和21(d)所示。
所述三相半桥逆变器包括三个电路模块M和一个控制器。其中，三个电路模块M共用第一电容C1和第二电容C2。所述控制器为所述三个电路模块M中的每一个双向开关提供驱动控制信号。如图21所示，所述三个电路模块M的所有上输入端子均连接第一电容C1的正极；所述三个电路模块M的所有中间输入端子均连接第一电容C1和第二电容C2的公共端；所述三个电路模块M的所有下输入端子均连接第二电容C2的负极；所述三个电路模块M的三个第一输出端子分别通过第二电感L2连接交流电网的三相且所述三个电路模块M的三个第二输出端子均连接第一电容C1和第二电容C2的公共端(图21(a)或21(c))；或者，所述三个电路模块M的三个第二输出端子分别通过第二电感L2连接交流电网的三相且所述三个电路模块M的三个第一输出端子均连接第一电容C1和第二电容C2的公共端(图21(b)或21(d))。
如图21(a)和图21(b)所示，交流电网的中性端连接第一电容C1和第二电容C2的公共端，从而构成三相四线系统。如图21(c)和图21(d)所示，交流电网的中性端不连接第一电容C1和第二电容C2的公共端，从而构成三相三线系统。
电网电压绝对值正负半周对称，因此，与直流电源并联的两个串联电容中点电压自动平衡。该逆变器采用单级结构，功耗小，成本低，效率高，稳定性高。
本发明提供了一种半桥逆变器单元及逆变器，可以用于，但不限于，可再生能源系统，比如单相或三相并网光伏系统。
本说明书中的各个实施例均采用递进的方式描述，各个实施例之间相同或相似的部分互相参见即可，每个实施例重点说明的都是与其他实施例的不同之处。
需要说明的是，在本文中，诸如“第一”和“第二”，“上”和“下”等之类的关系术语仅仅用来将一个实体或者操作与另一个实体或操作区分开来，而不一定要求或者暗示这些实体或操作之间存在任何这种实际的关系或者顺序。而且，术语“包括”、“包含”或者任何其他变体意在涵盖非排他性的包含，从而使得一系列要素的过程、方法、物品或者设备不仅包括那些要素，而且还包括没有明确列出的其他要素，或者是还包括为这种过程、方法、物品或者设备所固有的要素。在没有更多限制的情况下，由语句“包括一个……”限定的要素，并不排除在包括所述要素的过程、方法、物品或者设备同时还存在另外的其它要素。
以上所述仅是本发明的具体实施方式，应当指出，对于本技术领域的普通技术人员来说，在不脱离本发明原理的前提下，还可以做出若干改进和润饰，比如，根据本实施例中的拓扑电路利用对称特性得到的拓扑，这些改进和润饰也应视为本发明的保护范围。

Claims (25)

  1. 一种半桥逆变器单元，其特征在于，包括：逆变控制模块和第一电感；并具有第一接入端、第二接入端、第三接入端、第一电压输出端和第二电压输出端以及若干控制端；
    所述逆变控制模块连接第一接入端、第二接入端、第三接入端、第一电压输出端、第二电压输出端、电感的第一端和电感的第二端七个端子，并连接所述若干控制端；用于根据第一工作模态下输入到各个控制端的控制信号，针对所述七个端子，导通第一电感的第一端与第一接入端之间的连接以及第一电感的第二端与第一电压输出端之间的连接，并断开其他的端到端连接；根据第二工作模态下输入到各个控制端的控制信号，针对所述七个端子，导通第一电感的第一端与第二接入端之间的连接以及第一电感的第二端与第一电压输出端之间的连接；根据第三工作模态下输入到各个控制端的控制信号，针对所述七个端子，导通第一电感的第一端与第一接入端之间的连接以及第一电感的第二端与第二电压输出端之间的连接；根据第四工作模态下输入到各个控制端的控制信号，针对所述七个端子，导通第一电感的第一端与第二接入端之间的连接以及第一电感的第二端与第二电压输出端之间的连接。
  2. 如权利要求1所述的半桥逆变器单元，其特征在于，所述第一电压输出端和所述第二电压输出端中的一个与所述第三接入端相连。
  3. 如权利要求1或2所述的半桥逆变器单元，其特征在于，所述逆变控制模块包括第一电路模块和第二电路模块；
    所述第一电路模块连接第一接入端、第二接入端、第三接入端和第一电感的第一端，并连接所述若干控制端中的一部分控制端，用于根据所连接的各个控制端输入的不同控制信号，提供至少以下两种工作状态：仅导通第一电感的第一端与第一接入端之间的连接；仅导通第一电感的第一端与第二接入端之间的连接；
    所述第二电路模块连接第一电压输出端、第二电压输出端和第一电感的第二端；并连接所述若干控制端中的一部分控制端，用于根据所连接的各个控制端输入的不同控制信号，提供至少以下两种工作状态：仅导通第一电感的第二端与第一电压输出端之间的连接；仅导通第一电感的第二端与第二电压输出端之间的连接。
  4. 如权利要求3所述的半桥逆变器单元，其特征在于，
    第一电路模块至少包括一个上输入端子、一个中间输入端子、一个下输入端子、一个输出端子、第一开关电路支路和第二开关电路支路；其中上输入端子连接第一接入端，中间输入端子连接第三接入端，下输入端子连接第二接入端，输出端子连接第一电感的第一端；
    第二电路模块至少包括一个输入端子、第一输出端子、第二输出端子、第一开关支路和第二开关支路；其中，输入端子连接第一电感的第二端，第一输出端子连接第一电压输出端，第二输出端子连接第二电压输出端；
    第一电感连接在第一电路模块的输出端子和第二电路模块的输入端子之间；
    第二电路模块的第一输出端子连接第三接入端，或者第二电路模块的第二输出端子连接第三接入端；
    第一电路模块的第一开关电路支路连接在第一电路模块的上输入端子和输出端子之间；
    第一电路模块的第二开关电路支路连接在第一电路模块的下输入端子和输出端子之间；
    第二电路模块的第一开关支路连接在第二电路模块的输入端子和第一输出端子之间；
    第二电路模块的第二开关支路连接在第二电路模块的输入端子和第二输出端子之间。
  5. 根据权利要求4所述的半桥逆变器单元，其特征在于，进一步 包括第三电容，其中，
    第三电容连接在第二电路模块的第一输出端子和第二输出端子之间。
  6. 根据权利要求4所述的半桥逆变器单元，其特征在于，所述第一电路模块进一步包括第三开关电路支路，其中，所述第三开关电路支路连接在第一电路模块的中间输入端子和输出端子之间。
  7. 根据权利要求4所述的半桥逆变器单元，其特征在于，所述第一电路模块包括第一双向开关和第二双向开关；
    第一双向开关的第一端连接第一电路模块的上输入端子；
    第一双向开关的第二端同时连接第一电路模块的输出端子和第二双向开关的第一端；
    第二双向开关的第二端连接第一电路模块的下输入端子。
  8. 根据权利要求6所述的半桥逆变器单元，其特征在于，所述第一电路模块包括第一双向开关、第二双向开关、第三双向开关、第四双向开关、第一二极管和第二二极管；
    第一双向开关的第一端连接第一电路模块的上输入端子；
    第一双向开关的第二端同时连接第一二极管的负极和第二双向开关的第一端；
    第二双向开关的第二端同时连接第三双向开关的第一端和第一电路模块的输出端子；
    第三双向开关的第二端同时连接第二二极管的正极和第四双向开关的第一端；
    第四双向开关的第二端连接第一电路模块的下输入端子；
    第一二极管的正极连接第二二极管的负极；
    第一二极管和第二二极管的公共端连接第一电路模块的中间输入端子。
  9. 根据权利要求6所述的半桥逆变器单元，其特征在于，所述第 一电路模块包括第一双向开关、第二双向开关、第三双向开关和第四双向开关；
    第一双向开关的第一端连接第一电路模块的上输入端子；
    第一双向开关的第二端同时连接第一电路模块的输出端子和第四双向开关的第一端；
    第四双向开关的第二端连接第一电路模块的下输入端子；
    第二双向开关的第一端连接第一电路模块的中间输入端子；
    第二双向开关的第二端连接第三双向开关的第二端；
    第三双向开关的第一端连接第一电路模块的输出端子。
  10. 根据权利要求6所述的半桥逆变器单元，其特征在于，所述第一电路模块包括第一双向开关、第二双向开关、第三双向开关、第一二极管、第二二极管、第三二极管和第四二极管；
    第一双向开关的第一端连接第一电路模块的上输入端子；
    第一双向开关的第二端同时连接第一电路模块的输出端子和第三双向开关的第一端；
    第三双向开关的第二端连接第一电路模块的下输入端子；
    第一二极管的正极同时连接第二二极管的负极和第一电路模块的中间输入端子；
    第一二极管的负极同时连接第三二极管的负极和第二双向开关的第一端；
    第二二极管的正极同时连接第四二极管的正极和第二双向开关的第二端；
    第三二极管的正极同时连接第四二极管的负极和第一电路模块的输出端子。
  11. 根据权利要求4或6所述的半桥逆变器单元，其特征在于，所述第二电路模块包括第一双向开关、第二双向开关、第一二极管、第二二极管、第三二极管、第四二极管、第五二极管、第六二极管、第 七二极管和第八二极管；
    第一二极管的负极同时连接第三二极管的负极和第一双向开关的第一端；
    第一二极管的正极同时连接第二二极管的负极和第二电路模块的第一输出端子；
    第二二极管的正极同时连接第四二极管的正极和第一双向开关的第二端；
    第三二极管的正极同时连接第四二极管的负极和第二电路模块的输入端子；
    第五二极管的负极同时连接第七二极管的负极和第二双向开关的第一端；
    第五二极管的正极同时连接第六二极管的负极和第二电路模块的输入端子；
    第六二极管的正极同时连接第八二极管的正极和第二双向开关的第二端；
    第七二极管的正极同时连接第八二极管的负极和第二电路模块的第二输出端子。
  12. 根据权利要求4或6所述的半桥逆变器单元，其特征在于，所述第二电路模块包括第一双向开关、第二双向开关、第三双向开关和第四双向开关；
    第一双向开关的第一端连接第二电路模块的第一输出端子；
    第一双向开关的第二端连接第二双向开关的第二端；
    第二双向开关的第一端同时连接第三双向开关的第一端和第二电路模块的输入端子；
    第三双向开关的第二端连接第四双向开关的第二端；
    第四双向开关的第一端连接第二电路模块的第二输出端子。
  13. 根据权利要求4或6所述的半桥逆变器单元，其特征在于，所 述第二电路模块包括第一双向开关、第二双向开关、第三双向开关、第四双向开关、第一二极管、第二二极管、第三二极管和第四二极管；
    第一双向开关的第一端同时连接第三二极管的负极和第二电路模块的第一输出端子；
    第一双向开关的第二端连接第一二极管的正极；
    第一二极管的负极同时连接第二双向开关的第一端和第二电路模块的输入端子；
    第二双向开关的第二端连接第二二极管的正极；
    第三二极管的正极连接第三双向开关的第二端；
    第三双向开关的第一端同时连接第四二极管的负极和第二电路模块的输入端子；
    第四二极管的正极连接第四双向开关的第二端；
    第四双向开关的第一端同时连接第二二极管的负极和第二电路模块的第二输出端子。
  14. 根据权利要求4或6所述的半桥逆变器单元，其特征在于，所述第二电路模块包括第一逆阻型IGBT和第二逆阻型IGBT；
    第一逆阻型IGBT连接在第二电路模块的输入端子和第一输出端子之间；
    第二逆阻型IGBT连接在第二电路模块的输入端子和第二输出端子之间。
  15. 一种单相半桥逆变器，其特征在于，包括一个权利要求1至14中的任一项所述的半桥逆变器单元和一个控制器，其中，所述控制器与所述半桥逆变器单元的若干个控制端相连，用于为所述半桥逆变器单元提供各个工作模态对应的控制信号。
  16. 根据权利要求15所述的单相半桥逆变器，其特征在于，还包括第一电容和第二电容；
    所述半桥逆变器单元的第一接入端连接第一电容的第一端，第二 接入端连接第二电容的第二端；所述第一电容的第二端和所述第二电容的第一端连接所述第三接入端。
  17. 根据权利要求15所述的单相半桥逆变器，其特征在于，还包括第二电感；并具有第一交流负载接入端和第二交流负载接入端；
    第二电感连接在所述半桥逆变器单元的第二电压输出端和所述单相半桥逆变器的第一交流负载接入端之间且所述半桥逆变器单元的第一电压输出端和第三接入端连接第二交流负载接入端；或者
    第二电感连接在所述半桥逆变器单元的第一电压输出端和所述单相半桥逆变器的第二交流负载接入端之间且所述半桥逆变器单元的第二电压输出端和第三接入端连接第一交流负载接入端。
  18. 如权利要求17所述的单相半桥逆变器，其特征在于，所述第二电感与所述半桥逆变器单元中的第一电感共用磁芯。
  19. 根据权利要求15-18任一项所述的单相半桥逆变器，其特征在于，还包括：双向DC-DC变换器，所述双向DC-DC变换器与连接所述半桥逆变器单元的第一接入端、第二接入端和第三接入端相连，用于对接收到的直流电压进行变换后输出到所述半桥逆变器单元的第一接入端、第二接入端和第三接入端中。
  20. 根据权利要求19所述的单相半桥逆变器，其特征在于，所述双向DC-DC变换器包括N个电容、N-1个电感和N个双向开关；其中，所述N个电容串联连接在第一接入端和第二接入端之间，所述N个双向开关串联后连接在第一接入端和第二接入端之间；且所述N个双向开关串联得到的电路与所述N个电容串联得到的电路并联；所述N-1个电感中的第i个电感的一端连接在第i个电容与第i+1个电容之间，另一端连接在第i个双向开关与第i+1个双向开关之间；其中N大于等于2。
  21. 一种三相半桥逆变器，其特征在于，包括：
    一个控制器和三个权利要求1至14中的任一项所述的半桥逆变器 单元；
    其中，各个半桥逆变器单元的第一接入端相互连接，第二接入端相互连接，第三接入端相互连接；各个半桥逆变器单元的第一电压输出端一对一连接所述三相半桥逆变器的一个相位的交流负载接入端；
    所述控制器与每一个半桥逆变器单元中的各个控制端相连，用于为该半桥逆变器单元提供各个电平模式对应的控制信号。
  22. 根据权利要求21所述的三相半桥逆变器，其特征在于，还具有交流负载中性端；各个半桥逆变器单元的第三接入端连接所述三相半桥逆变器的交流负载中性端。
  23. 根据权利要求21所述的三相半桥逆变器，其特征在于，还包括第一电容和第二电容；
    各个半桥逆变器单元的第一接入端连接第一电容的第一端，第二接入端连接第二电容的第二端；所述第一电容的第二端和所述第二电容的第一端连接所述第三接入端。
  24. 根据权利要求21所述的三相半桥逆变器，其特征在于，还包括三个相位的交流负载接入端和三个第二电感；三个第二电感与三个半桥逆变器单元一一对应，并与三个相位的交流负载接入端一一对应；
    其中，每一个第二电感连接在对应的半桥逆变器单元的第二电压输出端和对应的相位的交流负载接入端之间且对应的半桥逆变器单元的第一电压输出端和第三接入端连接所述三相半桥逆变器单元的交流负载中性端；或者，
    每一个第二电感连接在对应的半桥逆变器单元的第一电压输出端和对应的相位的交流负载接入端之间且对应的半桥逆变器单元的第二电压输出端和第三接入端连接所述三相半桥逆变器单元的交流负载中性端。
  25. 如权利要求24所述的三相半桥逆变器，其特征在于，每一个 半桥逆变器单元中的第一电感与其对应的第二电感共用一个磁芯。
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