CN110943633B - Three-level single-phase single-stage boost inverter and control method thereof - Google Patents

Three-level single-phase single-stage boost inverter and control method thereof Download PDF

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CN110943633B
CN110943633B CN201811119520.9A CN201811119520A CN110943633B CN 110943633 B CN110943633 B CN 110943633B CN 201811119520 A CN201811119520 A CN 201811119520A CN 110943633 B CN110943633 B CN 110943633B
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bridge arm
switching tube
diode
switching
tube
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CN110943633A (en
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盛万兴
吴鸣
吕志鹏
孙丽敬
宋振浩
赵婷
刘国宇
郑楠
雷达
肖莹
王金浩
樊瑞
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State Grid Electric Power Research Institute Of Sepc
State Grid Corp of China SGCC
China Electric Power Research Institute Co Ltd CEPRI
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State Grid Electric Power Research Institute Of Sepc
State Grid Corp of China SGCC
China Electric Power Research Institute Co Ltd CEPRI
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/483—Converters with outputs that each can have more than two voltages levels
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)

Abstract

The invention provides a three-level single-phase single-stage boost inverter and a control method thereof, a first inductor (L)1) And a power supply (U)in) The bridge comprises a first bridge arm and a second bridge arm; the positive pole of the power supply and the first inductance (L)1) Connected to form a series circuit; the first bridge arm and the second bridge arm are connected to the first inductor (L)1) And a power supply (U)in) A series circuit connection for receiving a voltage control signal; the first bridge arm and the second bridge arm respectively comprise a plurality of switching tubes; the three-level single-phase single-stage boost inverter is enabled to output 5 voltages through one switching period of each bridge arm switching tube, the 5 voltages form one waveform of alternating-current voltage, the three-level single-phase single-stage boost inverter is enabled to output the alternating-current voltage, each bridge arm output voltage can obtain three levels, and compared with a two-level inverter, the harmonic content of the output voltage can be greatly reduced, so that output filter elements can be reduced, and the waveform quality is improved.

Description

Three-level single-phase single-stage boost inverter and control method thereof
Technical Field
The invention relates to the technical field of power electronic converters, in particular to a three-level single-phase single-stage boost inverter and a control method thereof.
Background
Inverters are a core component of photovoltaic power generation systems. In order to adapt to the characteristic of wide output voltage variation range of a photovoltaic array, a two-stage structure of a Boost converter cascaded voltage type full-bridge inverter is generally adopted by a photovoltaic inverter. However, the conversion efficiency of a two-stage system is relatively low. In addition, because the structure does not contain a high-frequency or low-frequency transformer, the high-frequency switching of the power tube can cause the ground capacitance of the photovoltaic cell panel to generate high-frequency common-mode voltage, so that large high-frequency leakage current is formed, and the safety of equipment and personnel is endangered. The single-phase three-level Z-source inverter can well solve the problems. However. The number of power devices and passive devices is large, and the cost is high. Complex control, insufficient boosting capacity and the like.
Disclosure of Invention
In order to solve the above-mentioned deficiency existing in the prior art, the invention provides a three-level single-phase single-stage boost inverter, comprising: first inductance (L)1) And a power supply (U)in) The bridge comprises a first bridge arm and a second bridge arm;
the positive pole of the power supply and the first inductance (L)1) Connected to form a series circuit;
the first mentionedOne bridge arm and a second bridge arm are connected with the first inductor (L)1) And a power supply (U)in) A series circuit connection for receiving a voltage control signal;
the first bridge arm and the second bridge arm respectively comprise a plurality of switching tubes; and enabling the three-level single-phase single-stage boost inverter to output five voltages through one switching period of each bridge arm switching tube, wherein the five voltages form one waveform of alternating-current voltage.
Preferably, the first leg includes: a first diode (D)1) A seventh diode (D)7) The bridge arm comprises a first bridge arm upper bridge arm and a first bridge arm lower bridge arm;
the first upper leg includes: a first switch tube (S)1) And a second switch tube (S)2)；
The first switch tube (S)1) And the second switching tube (S)2) The positive electrode of (1) is connected;
the first leg lower leg includes: third switch tube (S)3) And a fourth switching tube (S)4)；
The third switching tube (S)3) And the fourth switching tube (S)4) The positive electrode of (1) is connected;
the second switch tube (S)2) Negative electrode and the third switching tube (S)3) Connecting the positive electrode;
the first diode (D)1) And the first inductor (L)1) Connected, the first diode (D)1) The cathode of the first bridge arm is connected with the midpoint of the upper bridge arm of the first bridge arm;
the seventh diode (D)7) Is connected with the midpoint of the lower arm of the first arm, and the seventh diode (D)7) Is connected with the negative pole of the power supply.
Preferably, the second leg includes: second diode (D)2) An eighth diode (D)8) The upper bridge arm and the lower bridge arm of the second bridge arm;
the second upper leg includes: fifth switch tube (S)5) And a sixth switching tube (S)6)；
The fifth switch tube (S)5) And the sixth switching tube (S)6) The positive electrode of (1) is connected;
the second leg lower leg includes: seventh switch tube (S)7) And an eighth switching tube (S)8)；
The seventh switching tube (S)7) And the eighth switching tube (S)8) The positive electrode of (1) is connected;
the sixth switching tube (S)6) Negative electrode and the seventh switching tube (S)7) The positive electrode of (1) is connected;
the first switch tube (S)1) A positive electrode and the fifth switching tube (S)5) Connecting the positive electrode;
the fourth switch tube (S)4) Negative pole and the eighth switching tube (S)8) Connecting the negative electrodes;
the second diode (D)2) And the first inductor (L)1) Connected, the second diode (D)2) The cathode of the second bridge arm is connected with the midpoint of the upper bridge arm of the second bridge arm;
the eighth diode (D)8) The anode of the second bridge arm is connected with the midpoint of the lower bridge arm of the second bridge arm; the eighth diode (D)8) Is connected to the negative pole of the power supply.
Preferably, the inverter further includes: a first capacitor (C)1) A second capacitor (C)2) A third diode (D)3) A fourth diode (D)4) A fifth diode (D)5) And a sixth diode (D)6) And a filter;
the first capacitor (C)1) And said second capacitor (C)2) Is connected to said first capacitor (C)1) And the other end of the first switching tube (S)1) And the fifth switching tube (S)5) Is connected to the second capacitor (C)2) And the other end of the fourth switching tube (S)4) And the eighth switching tube (S)8) The connection point of the negative electrode is connected;
the third diode (D)3) And the fourth diode (D)4) The cathode of (a) is connected; the third diode (D)3) The cathode of the first bridge arm is connected with the midpoint of the upper bridge arm of the first bridge arm; the fourth diode (D)4) The anode of the first bridge arm is connected with the midpoint of the lower bridge arm of the first bridge arm;
the fifth diode (D)5) And the sixth diode (D)6) The cathode of (a) is connected; the fifth diode (D)5) The cathode of the second bridge arm is connected with the midpoint of the upper bridge arm of the second bridge arm; the sixth diode (D)6) The anode of the second bridge arm is connected with the midpoint of the lower bridge arm of the second bridge arm;
one end of the filter is connected with the midpoint of the first bridge arm, and the other end of the filter is connected with the midpoint of the second bridge arm.
Preferably, the filter comprises a second inductor (L)2) An output capacitor (C)0) And a load resistance (R)0)；
The second inductance (L)2) Is connected with the midpoint of the first bridge arm, a second inductance (L)2) And the other end of (C) and the output capacitor (C)0) Is connected to the first terminal of the output capacitor (C)0) Is connected to the midpoint of the second leg, the load resistance (R)0) Same output capacitor (C)0) Are connected in parallel.
Preferably, the first capacitance (C)1) And a second capacitance (C)2) Are equal in size.
A method of controlling a three-level single-phase single-stage boost inverter, the method comprising:
acquiring a control signal of required voltage;
a first bridge arm and a second bridge arm of the three-level single-phase single-stage boost inverter control switching tubes of the first bridge arm and the second bridge arm based on the acquired control signals of the required voltage, so that the three-level single-phase single-stage boost inverter works in one switching period;
and enabling a power supply to charge or discharge the first inductor based on five working modes in the switching period, so that the three-level single-phase single-stage boost inverter outputs alternating-current voltage.
Preferably, the obtaining of the control signal of the required voltage includes:
acquiring two isosceles triangular waves and sine waves which are in the same phase and have the same amplitude based on the voltage;
modulating the isosceles triangle wave and the sine wave to obtain positive and negative groups of SPWM control signals;
and modulating the isosceles triangular wave and the sine wave in a reversed phase manner to obtain the other positive and negative SPWM control signals.
Preferably, the five working modes in one switching cycle include:
a first mode of operation: a second switching tube (S) for connecting the first bridge arm2) And a third switching tube (S)3) And a sixth switching tube (S) of the second bridge arm6) And a seventh switching tube (S)7) For the first inductance (L)1) Charging is carried out;
a second working mode: a third switching tube (S) for connecting the first bridge arm3) And a fourth switching tube (D)4) A fifth switching tube (D) of the second bridge arm5) And a sixth switching tube (D)6) For the first inductance (L)1) Discharging;
the third working mode is as follows: a third switching tube (S) for connecting the first bridge arm3) And a fourth switching tube (S)4) And a sixth switching tube (S) of the second bridge arm6) And a seventh switching tube (S)7) For the first inductance (L)1) Charging is carried out;
the fourth working mode: a first switching tube (S) for connecting the first bridge arm1) And a second switching tube (S)2) A seventh switching tube (S) of the second bridge arm7) And an eighth switching tube (S)8) For the first inductance (L)1) Discharging;
a fifth working mode: a first switching tube (S) for connecting the first bridge arm1) And a second switching tube (S)2) And a sixth switching tube (S) of the second bridge arm6) And a seventh switching tube (S)7) For the first inductance (L)1) And charging is carried out.
Preferably, the charging or discharging the first inductor based on five working modes in the one switching cycle to enable the three-level single-phase single-stage boost inverter to output the ac voltage includes:
enabling the first inductor of the three-level single-phase single-stage boost inverter to alternately work in a charging state and a discharging state based on five working modes in one switching period;
enabling the three-level single-phase single-stage boost inverter to obtain 5 different levels in sequence based on the fact that the first inductor works in a charging state and a discharging state alternately;
the three-level single-phase single-stage boost inverter outputs an alternating-current voltage based on the 5 different levels.
Compared with the prior art, the invention has the following beneficial effects:
1. three-level single-phase single-stage boost inverter, control method and system thereof, and first inductor (L)1) And a power supply (U)in) The bridge comprises a first bridge arm and a second bridge arm; the positive pole of the power supply and the first inductance (L)1) Connected to form a series circuit; the first bridge arm and the second bridge arm are connected to the first inductor (L)1) And a power supply (U)in) A series circuit connection for receiving a voltage control signal; the first bridge arm and the second bridge arm respectively comprise a plurality of switching tubes; the three-level single-phase single-stage boost inverter is enabled to output five voltages through one switching period of each bridge arm switching tube, the five voltages form one waveform of alternating-current voltage, the three-level single-phase single-stage boost inverter is enabled to output the alternating-current voltage, the output voltage of each bridge arm can obtain three levels, and compared with a two-level inverter, the harmonic content of the output voltage of the three-level single-phase single-stage boost inverter can be greatly reduced, so that output filter elements can be reduced, and the waveform quality is improved.
2. Three-level single-phase single-stage boost inverter and control method and system thereof, wherein four switching tubes S1、S4、S5、S8The voltage stress of the direct current bus is reduced to half of the voltage of the direct current bus; the function originally realized by the two-stage power conversion is realized by the one-stage power conversion, the cost is reduced, and the system integration level is improved.
3. A three-level single-phase single-stage boost inverter and a control method and a system thereof are provided, wherein a two-stage structure needs to simultaneously realize the neutral point voltage clamping and other control of a front stage and a rear stage, the control structure is very complex, the single-phase three-level boost inverter only needs to realize the control of one-stage power conversion, and the control structure is simpler.
Description of the drawings:
FIG. 1 is a schematic diagram of a converter and its TL topology of the present invention;
FIG. 2 is an equivalent circuit diagram of a first mode of operation according to the present invention;
FIG. 3 is an equivalent circuit diagram of a second mode of operation according to the present invention;
FIG. 4 is an equivalent circuit diagram of a third mode of operation according to the present invention;
FIG. 5 is an equivalent circuit diagram of a fourth mode of operation according to the present invention;
FIG. 6 is an equivalent circuit diagram of a fifth mode of operation according to the present invention;
FIG. 7 is a waveform diagram of a carrier wave, modulated by a unipolar SPWM employed in the present invention;
FIG. 8 is a waveform diagram of the output simulation under unipolar SPWM modulation in accordance with the present invention.
The specific implementation mode is as follows:
for a better understanding of the present invention, reference is made to the following description taken in conjunction with the accompanying drawings and examples, in which:
example 1
A three-level single-phase single-stage boost inverter as shown in fig. 1, comprising: first inductance (L)1) And a power supply (U)in) The bridge comprises a first bridge arm and a second bridge arm;
the positive pole of the power supply and the first inductance (L)1) Connected to form a series circuit;
the first bridge arm and the second bridge arm are connected to the first inductor (L)1) And a power supply (U)in) A series circuit connection for receiving a voltage control signal;
the first bridge arm and the second bridge arm respectively comprise a plurality of switching tubes; and enabling the three-level single-phase single-stage boost inverter to output 5 voltages through one switching period of each bridge arm switching tube, wherein the 5 voltages form one waveform of alternating-current voltage.
The first leg includes: a first diode (D)1) A seventh diode (D)7) The bridge arm comprises a first bridge arm upper bridge arm and a first bridge arm lower bridge arm;
the first upper leg includes: a first switch tube (S)1) And a second switch tube (S)2)；
The first switch tube (S)1) And the second switching tube (S)2) The positive electrode of (1) is connected;
the first leg lower leg includes: third switch tube (S)3) And a fourth switching tube (S)4)；
The third switching tube (S)3) And the fourth switching tube (S)4) The positive electrode of (1) is connected;
the second switch tube (S)2) Negative electrode and the third switching tube (S)3) Connecting the positive electrode;
the first diode (D)1) And the first inductor (L)1) Connected, the first diode (D)1) The cathode of the first bridge arm is connected with the midpoint of the upper bridge arm of the first bridge arm;
the seventh diode (D)7) Is connected with the midpoint of the lower arm of the first arm, and the seventh diode (D)7) Is connected with the negative pole of the power supply.
The second leg includes: second diode (D)2) An eighth diode (D)8) The upper bridge arm and the lower bridge arm of the second bridge arm;
the second upper leg includes: fifth switch tube (S)5) And a sixth switching tube (S)6)；
The fifth switch tube (S)5) And the sixth switching tube (S)6) The positive electrode of (1) is connected;
the second leg lower leg includes: seventh switch tube (S)7) And an eighth switching tube (S)8)；
The seventh switching tube (S)7) Negative electrode of (1) and the eighth switchPipe closing (S)8) The positive electrode of (1) is connected;
the sixth switching tube (S)6) Negative electrode and the seventh switching tube (S)7) The positive electrode of (1) is connected;
the first switch tube (S)1) A positive electrode and the fifth switching tube (S)5) Connecting the positive electrode;
the fourth switch tube (S)4) Negative pole and the eighth switching tube (S)8) Connecting the negative electrodes;
the second diode (D)2) And the first inductor (L)1) Connected, the second diode (D)2) The cathode of the second bridge arm is connected with the midpoint of the upper bridge arm of the second bridge arm;
the eighth diode (D)8) The anode of the second bridge arm is connected with the midpoint of the lower bridge arm of the second bridge arm; the eighth diode (D)8) Is connected to the negative pole of the power supply.
The inverter further includes: a first capacitor (C)1) A second capacitor (C)2) A third diode (D)3) A fourth diode (D)4) A fifth diode (D)5) And a sixth diode (D)6) And a filter;
the first capacitor (C)1) And said second capacitor (C)2) Is connected to said first capacitor (C)1) And the other end of the first switching tube (S)1) And the fifth switching tube (S)5) Is connected to the second capacitor (C)2) And the other end of the fourth switching tube (S)4) And the eighth switching tube (S)8) The connection point of the negative electrode is connected;
the third diode (D)3) And the fourth diode (D)4) The cathode of (a) is connected; the third diode (D)3) The cathode of the first bridge arm is connected with the midpoint of the upper bridge arm of the first bridge arm; the fourth diode (D)4) The anode of the first bridge arm is connected with the midpoint of the lower bridge arm of the first bridge arm;
the fifth diode (D)5) And the sixth diode (D)6) The cathode of (a) is connected; the fifth diode (D)5) The cathode of the second bridge arm is connected with the midpoint of the upper bridge arm of the second bridge arm; the sixth diode (D)6) The anode of the second bridge arm is connected with the midpoint of the lower bridge arm of the second bridge arm;
one end of the filter is connected with the midpoint of the first bridge arm, and the other end of the filter is connected with the midpoint of the second bridge arm.
The filter comprises a second inductor (L)2) An output capacitor (C)0) And a load resistance (R)0)；
The second inductance (L)2) Is connected with the midpoint of the first bridge arm, a second inductance (L)2) And the other end of (C) and the output capacitor (C)0) Is connected to the first terminal of the output capacitor (C)0) Is connected to the midpoint of the second leg, the load resistance (R)0) Same output capacitor (C)0) Are connected in parallel.
The first capacitor (C)1) And a second capacitance (C)2) Are equal in size.
Example 2
Comprises a power supply UinFirst inductance L1A first diode D1The seventh diode D7A first switch tube S1A second switch tube S2A third switch tube S3And a fourth switching tube S4A third diode D3A fourth diode D4A first capacitor C1A second capacitor C2A fifth diode D5A sixth diode D6The fifth switch tube S5The sixth switching tube S6Seventh switching tube S7The eighth switching tube S8A second diode D2The eighth polar tube D8A second inductor L1An output capacitor C0Load resistance R0。
The power supply UinPositive pole and first inductance L1Is connected to the first terminal of the first inductor L1Second terminal and first diode D1Is connected to the anode of the second diode D2Is connected with the anode of the first switching tube S1A second switch tube S2And the thirdSwitch tube S3And a fourth switching tube S4A first bridge arm and a first diode D connected in series1Cathode of (2), third diode D3The cathode of (1) and the midpoint of the upper arm of the first bridge arm (first switching tube S)1And a second switching tube S2Of the seventh diode D), the seventh diode D7Anode of (2), fourth diode D4And the middle point of the lower bridge arm of the first bridge arm (third switching tube S)3And a fourth switching tube S4Of the seventh diode D), the seventh diode D7Is connected to the negative pole of the input voltage source.
The first capacitor C1And a second capacitor C2Is a voltage-dividing capacitor with large capacitance value for stabilizing the voltage at two ends of the bridge arm, and a first capacitor C1And a second capacitor C2Connected in series, the first capacitor C being in normal operation1And a second capacitor C2Both ends are equalized and connected in series C1、C2Is connected in parallel with the first leg. The third diode D3Anode of (2), fourth diode D4Cathode of (1), fifth diode D5Anode of (2), sixth diode D6The cathode and the first capacitor C1And a second capacitor C2The midpoints of the series are connected.
The fifth switch tube S5The sixth switching tube S6Seventh switching tube S7The eighth switching tube S8A fifth diode D connected in series to form a second bridge arm5Cathode of (2), second diode D2The cathode of the first bridge arm and the midpoint of the upper bridge arm of the second bridge arm (the fifth switching tube S)5And a sixth switching tube S6The connection point of) and the sixth diode D6Anode of (2), eighth diode D8Anode of (1) and midpoint of lower arm of second arm (seventh switching tube S)7And an eighth switching tube S8The connection point of) and the eighth diode D8Is connected to the negative pole of the input voltage source.
The second inductor L2And output capacitor C0Forming an LC filter, a second inductor L2Is connected to the midpoint of the first bridge arm (second switch tube S)2And a third switchPipe S3The connection point of) on the second inductor L2Is connected to the output capacitor C0First terminal of (1), output capacitor C0Is connected to the midpoint of the second bridge arm (sixth switching tube S)6And a seventh switching tube S7The connection point of) on the load resistor R, the load resistor R0Same output capacitor C0Are connected in parallel with an output capacitor C0The two ends of the three-level boost inverter are the alternating current output ends of the three-level boost inverter.
Further, the switch tube S1And S3、S2And S4、S5And S7、S6And S8Are complementary to each other.
Example 3
The working principle and characteristics of the three-level single-phase single-stage boost inverter are analyzed in detail below. To simplify the analysis process, the following basic assumptions are made: all power tubes and filter elements are ideal devices; ② voltage-sharing capacitor C1、C2Large enough to ignore its ripple, so there is Uc1＝Uc2(ii) a Third switch tube S4A second capacitor C2And an eighth switching tube S8The potential of the junction point O of (2) is 0.
The method comprises the following steps: acquiring a control signal of required voltage;
step two: a first bridge arm and a second bridge arm of the three-level single-phase single-stage boost inverter control switching tubes of the first bridge arm and the second bridge arm based on the acquired control signals of the required voltage, so that the three-level single-phase single-stage boost inverter works in one switching period;
step three: and enabling a power supply to charge or discharge the first inductor based on five working modes in the switching period, so that the three-level single-phase single-stage boost inverter outputs alternating-current voltage.
Based on the above assumptions, the operation process of the converter in one switching period in the steady state is divided into 5 modes, and each mode corresponds to an equivalent circuit.
The method comprises the following steps: acquiring a control signal of required voltage;
the switch tube S1～S8A Sinusoidal Pulse Width Modulation (SPWM) control strategy is adopted, and specifically, two isosceles triangular waves with the same phase and the same amplitude are used as carrier waves, and positive and negative phase waveforms of a sinusoidal wave obtained by a controller are used as modulation waves. The normal phase modulation wave and the carrier wave are intersected to obtain one group of SPWM control signals, and the other group of SPWM control signals are obtained after inversion; and similarly, the inverse modulation wave and the carrier wave are intersected to obtain the other two groups of SPWM control signals.
Step two: a first bridge arm and a second bridge arm of the three-level single-phase single-stage boost inverter control switching tubes of the first bridge arm and the second bridge arm based on the acquired control signals of the required voltage, so that the three-level single-phase single-stage boost inverter works in one switching period;
the working mode 1, the equivalent circuit is shown in fig. 2: the second switch tube, the third switch tube, the sixth switch tube and the seventh switch tube are all turned on, and the first switch tube, the fourth switch tube, the fifth switch tube and the eighth switch tube are all turned off. At this time, the inductance L1Terminal voltage of Uin-UD1-UD7> 0 (or U)in-UD2-UD8> 0), DC voltage source through D1，D7And D2，D8Charging the inductor L on the DC side1The current in (1) rises linearly, at this time Ua＝Ub＝UC1。
The working mode 2, the equivalent circuit is shown in fig. 3: the third switching tube, the fourth switching tube, the fifth switching tube and the sixth switching tube are switched on, and the first switching tube, the second switching tube, the seventh switching tube and the eighth switching tube are switched off. At this time, the voltage dividing capacitor C2，C1Voltages at both ends are applied to the diode D in reverse directions4，D5Cutting off the two ends of the tube; inductor L1Terminal voltage of Uin-2UC1< 0, inductance L1The current in the power supply is linearly reduced, and the power supply and the inductor are connected in series and simultaneously supply power to the load; voltage dividing capacitor C1，C2Discharging in series to supply energy to the load side; u shapea＝0，Ub＝2UC1。
The working mode 3, the equivalent circuit is shown in fig. 4: the third switching tube, the fourth switching tube, the sixth switching tube and the seventh switching tube are switched on, and the first switching tube, the second switching tube, the fifth switching tube and the eighth switching tube are switched off. At this time, the inductance L1Terminal voltage of Uin-UD2-UD8> 0, DC power supply through D2，D8Charging the inductor L on the DC side1The current in (1) rises linearly; voltage dividing capacitor C2Discharging to supply energy to the load side; u shapea＝0，Ub＝UC2＝UC1。
The working mode 4, the equivalent circuit is shown in fig. 5: the first switching tube, the second switching tube, the seventh switching tube and the eighth switching tube are switched on, and the third switching tube, the fourth switching tube, the fifth switching tube and the sixth switching tube are switched off. At this time, the inductance L1Terminal voltage of Uin-2UC1< 0, inductance L1The current in the power supply is linearly reduced, and the power supply and the inductor are connected in series to supply power to the load at the same time; voltage dividing capacitor C1，C2Discharging in series to supply energy to the load side; u shapea＝2UC1，Ub＝0。
The working mode 5, the equivalent circuit is shown in fig. 6: the first switching tube, the second switching tube, the sixth switching tube and the seventh switching tube are switched on, and the third switching tube, the fourth switching tube, the fifth switching tube and the eighth switching tube are switched off. At this time, the inductance L1Terminal voltage of Uin-UD2-UD8> 0, DC power supply through D2，D8Charging the inductor L on the DC side1The current in (1) rises linearly; voltage dividing capacitor C1Discharging to supply energy to the load side; u shapea＝2UC1，Ub＝UC2＝UC1。
Step three: and enabling a power supply to charge or discharge the first inductor based on five working modes in the switching period, so that the three-level single-phase single-stage boost inverter outputs alternating-current voltage.
Through the analysis of the above switching modes, it can be seen that the three-level single-phase single-stage boost inversion is performed in one switching periodBoth the a point and the b point of the transformer can obtain 0, UC1，2UC1Three levels. Inductor L at DC source side1Alternately operating in a charging state and a discharging state by means of a first inductor L1The voltage is increased by the charging and discharging.
In order to verify the correctness of theoretical analysis, saber simulation software is used for simulation verification, and the design indexes are as follows: switching frequency of 10kHz, and DC input voltage Uin48V, and the output AC voltage amplitude Uo.peak146V, filter inductance L1＝8mH，L21mH, voltage-dividing capacitor C1＝C24000 muF, filter capacitance Co＝5μF，S1～S8Using IRFP460, D1～D8S30L60 was used.
As can be seen from analyzing the simulation waveform diagram 7, only the voltage stress of the first switching tube and the fourth switching tube on the first bridge arm of the three-level single-phase single-stage boost inverter is reduced to half of the voltage stress of the direct-current bus, which is half of the voltage stress of the conventional two-level inverter. However, the voltage stress of the second switching tube and the third switching tube is still equal to the voltage of the direct current bus, which is also a defect of the invention. In addition, U can also be seenabat-UC1、-2UC1、0、UC1And 2UC1The five levels are periodically changed, and the boost multiple of the converter can be more than doubled. The experimental results are completely consistent with theoretical analysis, so that the correctness of the theoretical analysis of the three-level single-phase single-stage boost inverter is proved.
The invention provides a novel three-level single-phase single-stage boost inverter. The working principle and the characteristics of the device are analyzed in detail, and Saber software is used for simulation verification. As shown in fig. 8, the research result shows that the three-level single-phase single-stage boost inverter has the first switching tube S compared with the common two-level inverter under the same condition1And a fourth switching tube S4The fifth switch tube S5The eighth switching tube S8The voltage stress of the second switch tube S is reduced to half of the voltage of the direct current bus side2A third switch tube S3The sixth switching tube S6Seventh switching tube S7The voltage stress of the voltage is the voltage of a direct current bus; the output voltage of each bridge arm can obtain 0, UC1，2UC1Three levels; the boost multiple of the converter can reach more than two times. The above conclusions confirm the correctness of the three-level single-phase single-stage boost inverter topology.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and block diagrams of methods, systems, and computer program products according to embodiments of the application. It will be understood that each flow and block of the flow diagrams and block diagrams, and combinations of flows and blocks in the flow diagrams and block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and block diagram block or blocks.
The present invention is not limited to the above embodiments, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are included in the scope of the claims of the present invention which are filed as the application.

Claims (8)

1. A three-level single-phase single-stage boost inverter, comprising: first inductance (L)1) And a power supply (U)in) The bridge comprises a first bridge arm and a second bridge arm;
the positive pole of the power supply and the first inductance (L)1) Connected to form a series circuit;
the first bridge arm and the second bridge arm are connected to the first inductor (L)1) And a power supply (U)in) A series circuit connection for receiving a voltage control signal;
the first bridge arm and the second bridge arm respectively comprise a plurality of switching tubes; enabling the three-level single-phase single-stage boost inverter to output five voltages through one switching period of each bridge arm switching tube, wherein the five voltages form a waveform of alternating-current voltage;
the first leg includes: a first diode (D)1) A seventh diode (D)7) The bridge arm comprises a first bridge arm upper bridge arm and a first bridge arm lower bridge arm;
the first upper leg includes: a first switch tube (S)1) And a second switch tube (S)2)；
The first switch tube (S)1) And the second switching tube (S)2) The positive electrode of (1) is connected;
the first leg lower leg includes: third switch tube (S)3) And a fourth switching tube (S)4)；
The third switching tube (S)3) And the fourth switching tube (S)4) The positive electrode of (1) is connected;
the second switch tube (S)2) Negative electrode and the third switching tube (S)3) Connecting the positive electrode;
the first diode (D)1) And the first inductor (L)1) Connected, the first diode (D)1) The cathode of the first bridge arm is connected with the midpoint of the upper bridge arm of the first bridge arm;
the seventh diode (D)7) Is connected with the midpoint of the lower arm of the first arm, and the seventh diode (D)7) Is connected with the negative pole of the power supply.
2. A three-level single-phase single-stage boost inverter as recited in claim 1, wherein said second leg comprises: second diode (D)2) An eighth diode (D)8) The upper bridge arm and the lower bridge arm of the second bridge arm;
the second upper leg includes: fifth switch tube (S)5) And a sixth switching tube (S)6)；
The fifth switch tube (S)5) And the sixth switching tube (S)6) The positive electrode of (1) is connected;
the second leg lower leg includes: seventh switch tube (S)7) And an eighth switching tube (S)8)；
The seventh switching tube (S)7) And the eighth switching tube (S)8) The positive electrode of (1) is connected;
the sixth switching tube (S)6) Negative electrode and the seventh switching tube (S)7) The positive electrode of (1) is connected;
the first switch tube (S)1) A positive electrode and the fifth switching tube (S)5) Connecting the positive electrode;
the fourth switch tube (S)4) Negative pole and the eighth switching tube (S)8) Connecting the negative electrodes;
the second diode (D)2) And the first inductor (L)1) Connected, the second diode (D)2) The cathode of the second bridge arm is connected with the midpoint of the upper bridge arm of the second bridge arm;
the eighth diode (D)8) The anode of the second bridge arm is connected with the midpoint of the lower bridge arm of the second bridge arm; the eighth diode (D)8) Is connected to the negative pole of the power supply.
3. The three-level single-phase single-stage boost inverter of claim 2, wherein said inverter further comprises: a first capacitor (C)1) A second capacitor (C)2) A third diode (D)3) A fourth diode (D)4) A fifth diode (D)5) And a sixth diode (D)6) And a filter;
the first capacitor (C)1) And said second capacitor (C)2) Is connected to said first capacitor (C)1) And the other end of the first switching tube (S)1) And the fifth switching tube (S)5) Is connected to the second capacitor (C)2) And the other end of the fourth switching tube (S)4) And the eighth switching tube (S)8) The connection point of the negative electrode is connected;
the third diode (D)3) And the fourth diode (D)4) The cathode of (a) is connected; the third diode (D)3) The cathode of the first bridge arm is connected with the midpoint of the upper bridge arm of the first bridge arm; the fourth diode (D)4) The anode of the first bridge arm is connected with the midpoint of the lower bridge arm of the first bridge arm;
the fifth diode (D)5) And the sixth diode (D)6) The cathode of (a) is connected; the fifth diode (D)5) The cathode of the second bridge arm is connected with the midpoint of the upper bridge arm of the second bridge arm; the sixth diode (D)6) The anode of the second bridge arm is connected with the midpoint of the lower bridge arm of the second bridge arm;
one end of the filter is connected with the midpoint of the first bridge arm, and the other end of the filter is connected with the midpoint of the second bridge arm.
4. A three-level single-phase single-stage boost inverter according to claim 3, characterized in that said filter comprises a second inductor (L)2)、Output capacitance (C)0) And a load resistance (R)0)；
The second inductance (L)2) Is connected with the midpoint of the first bridge arm, a second inductance (L)2) And the other end of (C) and the output capacitor (C)0) Is connected to the first terminal of the output capacitor (C)0) Is connected to the midpoint of the second leg, the load resistance (R)0) Same output capacitor (C)0) Are connected in parallel.
5. A three-level single-phase single-stage boost inverter according to claim 3, characterized in that said first capacitor (C)1) And a second capacitance (C)2) Are equal in size.
6. A method of controlling a three-level single-phase single-stage boost inverter, the method comprising:
acquiring a control signal of required voltage;
a first bridge arm and a second bridge arm of the three-level single-phase single-stage boost inverter control switching tubes of the first bridge arm and the second bridge arm based on the acquired control signals of the required voltage, so that the three-level single-phase single-stage boost inverter works in one switching period;
enabling a power supply to charge or discharge a first inductor based on five working modes in one switching period, and enabling the three-level single-phase single-stage boost inverter to output alternating-current voltage;
five working modes in the switching period comprise:
a first mode of operation: a second switching tube (S) for connecting the first bridge arm2) And a third switching tube (S)3) And a sixth switching tube (S) of the second bridge arm6) And a seventh switching tube (S)7) For the first inductance (L)1) Charging is carried out;
a second working mode: a third switching tube (S) for connecting the first bridge arm3) And a fourth switching tube (D)4) A fifth switching tube (D) of the second bridge arm5) And a sixth switching tube (D)6) For the first inductance (L)1) Discharging;
the third working mode is as follows: a third switching tube (S) for connecting the first bridge arm3) And a fourth switching tube (S)4) And a sixth switching tube (S) of the second bridge arm6) And a seventh switching tube (S)7) For the first inductance (L)1) Charging is carried out;
the fourth working mode: a first switching tube (S) for connecting the first bridge arm1) And a second switching tube (S)2) A seventh switching tube (S) of the second bridge arm7) And an eighth switching tube (S)8) For the first inductance (L)1) Discharging;
a fifth working mode: a first switching tube (S) for connecting the first bridge arm1) And a second switching tube (S)2) And a sixth switching tube (S) of the second bridge arm6) And a seventh switching tube (S)7) For the first inductance (L)1) And charging is carried out.
7. The method of claim 6, wherein said deriving the control signal for the desired voltage comprises:
acquiring two isosceles triangular waves and sine waves which are in the same phase and have the same amplitude based on the voltage;
modulating the isosceles triangle wave and the sine wave to obtain positive and negative groups of SPWM control signals;
and modulating the isosceles triangular wave and the sine wave in a reversed phase manner to obtain the other positive and negative SPWM control signals.
8. The method of claim 6, wherein the causing the power supply to charge or discharge the first inductor based on five operating modes within the switching cycle causes the three-level single-phase single-stage boost inverter to output the AC voltage comprises:
enabling the first inductor of the three-level single-phase single-stage boost inverter to alternately work in a charging state and a discharging state based on five working modes in one switching period;
enabling the three-level single-phase single-stage boost inverter to sequentially obtain five different levels based on the fact that the first inductor alternately works in a charging state and a discharging state;
the three-level single-phase single-stage boost inverter outputs an alternating current voltage based on the five different levels.
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