CN114944776B - High-gain DC-AC converter for new energy access - Google Patents
High-gain DC-AC converter for new energy access Download PDFInfo
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- CN114944776B CN114944776B CN202210592079.6A CN202210592079A CN114944776B CN 114944776 B CN114944776 B CN 114944776B CN 202210592079 A CN202210592079 A CN 202210592079A CN 114944776 B CN114944776 B CN 114944776B
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- 239000003990 capacitor Substances 0.000 claims abstract description 101
- 210000004899 c-terminal region Anatomy 0.000 claims description 21
- 238000000034 method Methods 0.000 claims description 16
- 238000006243 chemical reaction Methods 0.000 claims description 9
- 239000000969 carrier Substances 0.000 claims description 3
- 238000007599 discharging Methods 0.000 abstract description 9
- 238000010586 diagram Methods 0.000 description 11
- 210000004027 cell Anatomy 0.000 description 2
- 230000007547 defect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/5387—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 in a bridge configuration
- H02M7/53871—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 in a bridge configuration with automatic control of output voltage or current
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- 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
-
- 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
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
-
- 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
- H02M1/32—Means for protecting converters other than automatic disconnection
-
- 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
- H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/70—Wind energy
- Y02E10/76—Power conversion electric or electronic aspects
Abstract
The invention provides a high-gain DC-AC converter for new energy access, which comprises a left half-bridge circuit, a T-type inverter unit, an n-level M-type boosting unit and a right half-bridge circuit which are sequentially connected in series; the M-type boosting unit has the capability of switching the polarity of the output voltage, so that the converter can adopt two end-side half-bridges to replace a rear-end H-bridge to realize bipolar output voltage, and the maximum voltage stress of a single switching tube is effectively reduced; the capacitor in the M-type boosting unit can participate in discharging at the same time, so that the utilization rate of the capacitor is improved, and the boosting capacity of the inverter is improved; the inverter realizes high output level through a voltage dividing capacitor in the T-shaped inverter, so that the total harmonic distortion rate of the output voltage is reduced; the converter can improve voltage gain and output level on the premise of not increasing a direct current power supply by connecting an additional M-type boosting unit in series, so that the number of power devices in the converter is effectively reduced.
Description
Technical Field
The invention relates to a high-gain DC-AC converter for new energy access, belonging to the fields of power electronic conversion and new energy power generation.
Background
Power converters are an important component for connecting renewable energy systems to the grid or local loads. With the increasing demand for renewable energy systems for power quality, power converters have received widespread attention. Among them, the multi-level inverter has excellent advantages in converting direct current into alternating current due to low du/dt and high quality of output voltage.
Neutral-point clamped, flying capacitors, and cascaded H-bridge inverters are the most common multilevel inverters. These conventional multilevel inverters have been widely studied and applied in different industrial sectors. As the output level increases, the number of active devices of neutral point clamped and flying capacitor type multilevel inverters increases significantly. In addition, they all suffer from voltage balancing problems, requiring auxiliary circuitry and complex control algorithms to maintain the voltage balance of the capacitor. The cascaded H-bridge multilevel inverter increases its output level by expanding the H-bridge cells and can produce more output levels by asymmetrically isolating the dc power supply. However, the need for multiple isolated dc power sources limits its range of applications.
Disclosure of Invention
The invention aims at overcoming the defects of the prior switch capacitor technology, thereby providing a high-gain DC-AC converter for new energy access, which comprises the following specific scheme:
the first aspect of the invention provides a high-gain DC-AC converter for new energy access, which comprises a left half-bridge circuit, a T-type inverter unit, an n-level M-type boosting unit and a right half-bridge circuit which are sequentially connected in series, wherein n is more than or equal to 1;
the T-shaped inverter unit comprises a switching tube T 1 Switch tube T 2 Electrolytic capacitor C with equal capacitance a And C b DC power supply U dc ；
The electrolytic capacitor C a Is connected with the DC power supply U dc The positive electrode of the electrolytic capacitor C is connected with b Cathode of (2) and DC power supply U dc The negative electrode of the electrolytic capacitor C is connected with a Is connected with the electrolytic capacitor C b An anode of (a); the switch tube T 1 E end of (2) and the switch tube T 2 E end of the switch tube T is connected with 2 Is connected to the electrolytic capacitor C a Is connected to the cathode of the electrolytic capacitor C b Is connected with the anode of the switch tube T 1 Is connected to the left half-bridge circuit as the negative output of the high-gain DC-AC converter;
the M-type boosting unit comprises a switching tube S n1 Switch tube S n2 Switch tube S n3 Switch tube S n4 Switch tube S n5 Switch tube S n6 And an electrolytic capacitor C n1 Electrolytic capacitor C n2 ；
The switch tube S n1 C terminal of (C) and said switching tube S n3 The C end of the switch tube S is connected and then used as the positive input end of the M-shaped boosting unit n1 E end of (2) and the switch tube S n2 E end connection of the switch tube S n2 C terminal of (C) and said electrolytic capacitor C n1 Is used as the positive output end of the M-shaped boosting unit after being connected with the anode;
the switch tube S n5 E terminal of (2) and the switching tube S n4 E end of the M-type boosting unit is connected and then used as a negative input end of the M-type boosting unit, and the switching tube S n5 C terminal of (C) and the switch tube S n6 C-terminal connection of the switch tube S n6 E terminal of (C) and the electrolytic capacitor C n2 Is used as the negative output end of the M-type boosting unit after being connected with the cathode of the M-type boosting unit;
the electrolytic capacitor C n1 Is connected to the cathode of the electrolytic capacitor C n2 Is connected with the anode of the battery;
the switch tube S n3 E terminal of (2) and the switching tube S n4 Is connected to the electrolytic capacitor C at the C terminal n1 Is connected to the cathode of the electrolytic capacitor C n2 Is connected to the anode of the battery;
the switch tube S n1 E terminal of (2) and the switching tube S n2 Is connected with the E end of the switch tube S n5 C terminal of (C) and said switching tube S n6 Is connected with the C end connection point of the (C) terminal;
the positive input end of the 1 st stage M-type boosting unit is connected to the direct current power supply U dc The negative input end of the 1 st stage M-type boosting unit is connected to the DC power supply U dc Is a negative electrode of (a);
the positive output end of the upper M-shaped boosting unit is connected with the positive input end of the lower M-shaped boosting unit, and the negative output end of the upper M-shaped boosting unit is connected with the negative input end of the lower M-shaped boosting unit;
the positive output end and the negative output end of the n-th stage M-type boosting unit are connected to the right half-bridge circuit.
The left half-bridge circuit comprises a switching tube S 7 And a switch tube S 8 ；
The switch tube S 7 C terminal of (C) and the electrolytic capacitor C a Is connected with the anode of the switch tube S 7 Is connected to the negative output of the high gain DC-AC converter; the switch tube S 8 E terminal of (C) and the electrolytic capacitor C b Is connected with the cathode of the switch tube S 8 Is connected to the negative output of the high gain DC-AC converter;
the right half-bridge circuit comprises a switching tube S 9 And S is 10 ；
The switch tube S 9 Electrolytic capacitor C of C end and n-th M-stage booster unit n1 Is connected with the anode of the switch tube S 10 Electrolytic capacitor C of E end and n-th M-stage booster unit n2 Is connected with the cathode of the switch tube S 9 E terminal of (2) and the switching tube S 10 And is connected as the positive output of the high gain DC-AC converter.
A second aspect of the present invention provides a modulation method for a high-gain DC-AC converter for new energy access, generating a driving signal, and cascade-charging N-stage M-type boost units in the high-gain DC-AC converter for new energy access by using the driving signal, so that the output level number N of the high-gain DC-AC converter for new energy access is 2 n +3 -3 sum voltage gains G of 2 n+1 -1。
The third aspect of the invention provides a DC/AC conversion system for new energy access, which comprises a controller and a multi-level converter, wherein the multi-level converter adopts the high-gain DC-AC converter for new energy access.
Compared with the prior art, the invention has outstanding substantive characteristics and remarkable progress, and concretely comprises the following steps:
the invention provides a high-gain DC-AC converter for new energy access, wherein an M-type boosting unit has polarity conversion capability, so that the converter can adopt two end-side half-bridges to replace a rear-end H-bridge to realize bipolar output voltage, and the maximum voltage stress of a single switching tube is effectively reduced; the capacitor in the M-type boosting unit can participate in discharging at the same time, so that the utilization rate of the capacitor is improved, and the boosting capacity of the inverter is improved; the high-level output can be realized through the serial-parallel conversion of the T-type inverter unit and the M-type boosting unit; the working mode that the back-stage capacitor in the expansion module is charged in series by the front-stage capacitor can further improve the output voltage gain and the output level by modularly expanding the M-type boosting unit to the right; the voltage balance of the capacitor is realized by using the parallel charging and series discharging working modes of the capacitor and the direct current power supply, and any auxiliary circuit or additional control method is not needed.
Drawings
Fig. 1 is a block diagram of a high-gain DC-AC converter in embodiment 1 of the present invention.
Fig. 2 is a diagram showing a current flow path of a first output level of the inverter according to embodiment 2 of the present invention.
Fig. 3 is a diagram showing a current flow path of the second output level of the inverter according to embodiment 2 of the present invention.
Fig. 4 is a diagram showing a current flow path of a third output level of the inverter according to embodiment 2 of the present invention.
Fig. 5 is a diagram showing a current flow path of a fourth output level of the inverter according to embodiment 2 of the present invention.
Fig. 6 is a diagram showing a current flow path of a fifth output level of the inverter according to embodiment 2 of the present invention.
Fig. 7 is a diagram showing a current flow path of a sixth output level of the inverter according to embodiment 2 of the present invention.
Fig. 8 is a diagram showing a current flow path of a seventh output level of the inverter according to embodiment 2 of the present invention.
Fig. 9 is a PWM modulation schematic of the inverter described in embodiment 2 of the present invention.
Fig. 10 is a waveform diagram of output voltage and current of the converter in embodiment 2 of the present invention under a resistive load.
Fig. 11 is a waveform diagram of output voltage and current of the converter in embodiment 2 of the present invention under resistive-inductive load.
FIG. 12 shows an electrolytic capacitor C of the inverter according to embodiment 2 of the present invention 1 And C 2 Is a voltage waveform diagram of (a).
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more clear, the following description of the technical solutions in the embodiments of the present invention will be given in detail, but the present invention is not limited to these embodiments:
example 1
As shown in fig. 1, the embodiment provides a high-gain DC-AC converter for new energy access, which comprises a left half-bridge circuit, a T-type inverter unit, an n-stage M-type boost unit and a right half-bridge circuit which are sequentially connected in series, wherein n is greater than or equal to 1;
the T-shaped inverter unit comprises a switching tube T 1 Switch tube T 2 Electrolytic capacitor C with equal capacitance a And C b DC power supply U dc ；
The electrolytic capacitor C a Is connected with the DC power supply U dc The positive electrode of the electrolytic capacitor C is connected with b Cathode of (2) and DC power supply U dc The negative electrode of the electrolytic capacitor C is connected with a Is connected with the electrolytic capacitor C b An anode of (a); the switch tube T 1 E end of (2) and the switch tube T 2 E end of the switch tube T is connected with 2 Is connected to the electrolytic capacitor C a Is connected to the cathode of the electrolytic capacitor C b Is connected with the anode of the switch tube T 1 Is connected to the left half-bridge circuit as the negative output of the high-gain DC-AC converter;
the M-type boosting unit comprises a switching tube S n1 Switch tube S n2 Switch tube S n3 Switch tube S n4 Switch tube S n5 Switch tube S n6 And an electrolytic capacitor C n1 Electrolytic capacitor C n2 ；
The switch tube S n1 C terminal of (C) and said switching tube S n3 The C end of the switch tube S is connected and then used as the positive input end of the M-shaped boosting unit n1 E end of (2) and the switch tube S n2 E end connection of the switch tube S n2 C terminal of (C) and said electrolytic capacitor C n1 Is used as the positive output end of the M-shaped boosting unit after being connected with the anode;
the switch tube S n5 E terminal of (2) and the switching tube S n4 E end of the M-type boosting unit is connected and then used as a negative input end of the M-type boosting unit, and the switching tube S n5 C terminal of (C) and the switch tube S n6 C-terminal connection of the switch tube S n6 E terminal of (C) and the electrolytic capacitor C n2 Is used as the negative output end of the M-type boosting unit after being connected with the cathode of the M-type boosting unit;
the electrolytic capacitor C n1 Is connected to the cathode of the electrolytic capacitor C n2 Is connected with the anode of the battery;
the switch tube S n3 E terminal of (2) and the switching tube S n4 Is connected to the electrolytic capacitor C at the C terminal n1 Is connected to the cathode of the electrolytic capacitor C n2 Is connected to the anode of the battery;
the switch tube S n1 E terminal of (2) and the switching tube S n2 Is connected with the E end of the switch tube S n5 C terminal of (C) and said switching tube S n6 Is connected with the C end connection point of the (C) terminal;
the positive input end of the 1 st stage M-type boosting unit is connected to the direct current power supply U dc The negative input end of the 1 st stage M-type boosting unit is connected to the DC power supply U dc Is a negative electrode of (a);
the positive output end of the upper M-shaped boosting unit is connected with the positive input end of the lower M-shaped boosting unit, and the negative output end of the upper M-shaped boosting unit is connected with the negative input end of the lower M-shaped boosting unit;
the positive output end and the negative output end of the n-th stage M-type boosting unit are connected to the right half-bridge circuit.
The left half-bridge circuit comprises a switching tube S 7 And a switch tube S 8 ；
The switch tube S 7 C terminal of (C) and the electrolytic capacitor C a Is connected with the anode of the switch tube S 7 Is connected to the negative output of the high gain DC-AC converter; the switch tube S 8 E terminal of (C) and the electrolytic capacitor C b Is connected with the cathode of the switch tube S 8 Is connected to the negative output of the high gain DC-AC converter;
the right half-bridge circuit comprises a switching tube S 9 And S is 10 ；
The switch tube S 9 Electrolytic capacitor C of C end and n-th M-stage booster unit n1 Is connected with the anode of the switch tube S 10 Electrolytic capacitor C of E end and n-th M-stage booster unit n2 Is connected with the cathode of the switch tube S 9 E terminal of (2) and the switching tube S 10 And is connected as the positive output of the high gain DC-AC converter.
In this embodiment, the structure of the M-type boosting unit is vertically symmetrical, and the vertically symmetrical capacitor is connected with the input DC power supply U in one period dc The parallel charging and the series discharging are equal, thereby achieving the purposes of self-balancing the capacitor voltage and improving the gain of the output voltage. And the serial-parallel conversion of the T-shaped converter and the M-shaped boosting unit with boosting capability at the later stage enables the output level number of the high-gain DC-AC converter to be higher. The left half-bridge circuit and the right half-bridge circuit are respectively positioned at two sides of the T-type inverter unit and the M-type boost unit and can be used for completing the conversion of the output polarity of the multi-level converter.
In the present embodiment, when the switch tube S i3 When conducting (i=1, 2,3 … n), electrolytic capacitor C i1 Discharging, the voltage of the output end is U dc The method comprises the steps of carrying out a first treatment on the surface of the When the switch tube S i1 And S is i6 Electrolytic capacitor C when conducting i1 And C i2 Serial discharge, output voltage of 2U dc The method comprises the steps of carrying out a first treatment on the surface of the When the switch tube S i4 Electrolytic capacitor C when conducting i2 Discharging, the output terminal voltage is-U dc The method comprises the steps of carrying out a first treatment on the surface of the When the switch tube S i2 And S is i5 Electrolytic capacitor C when conducting i1 And C i2 Discharging in series with an output voltage of-2U dc The method comprises the steps of carrying out a first treatment on the surface of the Electrolytic capacitor C with completed charging i1 And C i2 The + -U can be output to two ends by switching the state of the switch tube dc And + -2U dc The M-type boosting unit has the capability of switching the polarity of the output voltage, so that the inverter can adopt two end side half-bridges to replace a rear end H bridge to realize bipolar output voltage, the maximum voltage stress of a single switching tube is effectively reduced, and the electrolytic capacitor C in the M-type boosting unit i1 And C i2 Meanwhile, the capacitor takes part in discharging, and the utilization rate and the boosting capacity of the capacitor are improved.
It should be noted that in the implementation, the electrolytic capacitor C in the T-type inverter unit a 、C b The charging voltages of (a) are all 0.5U of the direct current input voltage dc Electrolytic capacitor C in M-type booster cell n1 And C n2 Is 2 n U dc 。
The modulation method of the high-gain DC-AC converter of the embodiment comprises the following steps: generating a driving signal, and performing cascade charging on N-level M-type boosting units in the high-gain DC-AC converter for new energy access by using the driving signal to enable the output level number N of the high-gain DC-AC converter for new energy access to be 2 n+3 -3 sum voltage gains G of 2 n+1 -1。
The capacitor pairs of the front-stage M-type boosting unit are connected in series, the electrolytic capacitor of the rear stage is charged through the conducted switching tube, and the working mode of cascade charging can further improve the output voltage gain and the output level number. The M-type boosting unit expands rightwards, and when the M-type boosting unit expands to n stages, the electrolytic capacitor C n1 (C n2 ) Is charged to a rated voltage of 2 n U dc The high gain DC-AC converter can output 2 n+1 Voltage gain of-1 times and 2 n+3 -3 output levels.
Specifically, an in-phase carrier laminated PWM method is selected to modulate the high-gain DC-AC converter:
with 2 n+3 -4 triangular carriersAnd sine modulated wave V ref Comparing, and logically combining the generated pulses according to the states of the switching tubes under each output level to obtain logic signals for controlling the on-off states of the switching tubes;
in the modulation method, triangular carrierWith the same amplitude A c And frequency f c The amplitude of the sine wave is A ref The modulation ratio M and the voltage gain G are defined as:
M=A ref /（2 n+2 -2）A c
G=V out /（V dc ）
wherein V is out To output the voltage amplitude, V dc Is the input voltage; the value range of the modulation ratio M is more than 0 and less than or equal to 1;
when (when)When j is E [1, 2, …,2 n+2 -2]The converter outputs 2j+1 level.
Example 2
In this embodiment, an M-type boost unit (n=1) is taken as an example, and the converter can output 13 levels and realize 3 times of voltage gain in one period; during the positive half cycle of the converter operation, 7 step output levels are shown in fig. 2-8. The specific working principle is analyzed as follows:
output level 1: as shown in fig. 2, through the switching tube S in the on state 11 、S 16 、S 8 And S is 9 Electrolytic capacitor C 11 And C 12 Discharge in series with DC power supply in output path, output voltage U out Is 3U dc ；
Output level 2: as shown in fig. 3, a switch S is turned on by a conduction state 11 、S 16 、S 9 、T 1 And T 2 Electrolytic capacitor C 11 And C 12 And electrolytic capacitor C in output path a Series-connected amplifierElectric, output voltage U out Is 2.5U dc ；
Output level 3: as shown in fig. 4, by turning on the switching tube S 13 、S 15 、S 16 Electrolytic capacitor C 12 Charging in parallel with input DC power supply, electrolytic capacitor C 1 Through the switching tube S in the on state 13 、S 8 、S 9 Discharging in series with the DC power supply in the output path, outputting a voltage U out Is 2U dc ；。
Output level 4: as shown in fig. 5, by turning on the switching tube S 13 、S 15 、S 16 Electrolytic capacitor C 12 Charging in parallel with DC power supply, electrolytic capacitor C 11 Switch S through on state 13 、S 9 、T 1 、T 2 In the output path with capacitor C a Serial discharge, output voltage U out 1.5U dc ；。
Output level 5: as shown in fig. 6, by turning on the switching tube S 11 、S 12 、S 14 Electrolytic capacitor C 11 Charging in parallel with a DC power supply, the DC power supply is connected with a switch S 11 、S 12 、S 8 、S 9 Independently discharge in output path, output voltage U out Is U (U) dc ；。
Output level 6: as shown in fig. 7, by turning on the switching tube S 11 、S 12 、S 14 Electrolytic capacitor C 11 Charging in parallel with DC power supply, electrolytic capacitor C a Through the switching tube S in the on state 11 、S 12 、S 9 、T 1 、T 2 Discharge in output path, output voltage U out 0.5U dc ；
Output level 7: as shown in fig. 8, a switching tube S 11 、S 12 、S 14 、S 7 And S is 9 In an on state, other switches in an off state, an electrolytic capacitor C 1 Charging in parallel with DC power supply, outputting voltage U out Is 0; .
Based on the analysis of the output level, the embodiment also provides a specific implementation mode of the driving signals of each switching tube in the carrier laminated pulse width modulation mode;
as shown in fig. 9, 12 triangular carriers are usedV t1 -V t12 And sine modulated wave V ref Comparing, and logically combining the generated pulses according to the states of the switching tubes under each output level to obtain logic signals for controlling the on-off states of the switching tubes;
in the modulation method, triangular carrierV t1 -V t12 With the same amplitude A c And frequency f c The amplitude of the sine wave is A ref The modulation ratio M of the converter is determined by the amplitude A of the modulation wave S And amplitude A of carrier wave C Common decisions, namely:
M=A ref /6A c
the value range of the modulation ratio M is 0< M is less than or equal to 1: when M is more than 0 and less than or equal to 1/6, the converter outputs 3 level, and the voltage gain G is 0.5; when M is more than 1/6 and less than or equal to 1/3, the converter outputs 5 level, and the voltage gain G is 1; when 1/3<M is less than or equal to 1/2, the converter outputs 7 level, and the voltage gain G is 1.5; when 1/2<M is less than or equal to 2/3, the converter outputs 9 level, and the voltage gain G is 2; when 2/3<M is less than or equal to 5/6, the converter outputs 11 level, and the voltage gain G is 2.5; when 5/6<M is less than or equal to 1, the converter outputs 13 level, and the voltage gain G is 3.
According to the modulation mode, the embodiment utilizes MATLAB/SIMULINK software to simulate the thirteen-level converter. FIGS. 10 and 11 are output voltage and current waveforms under resistive and resistive-inductive loads, respectively, it being observed that the output voltage waveforms contain 13 levels; when the input voltage is 20V, the peak output voltage reaches 60V, verifying the 13 level output and 3 boost capability of the proposed topology. The output current waveform comprises 13 levels under resistive load, with a peak output current of about 0.99A; the output current waveform is closer to a sine wave under a resistive load and lags the output voltage by a certain angle, and the peak output current is about 0.92A. FIG. 12 shows a waveform of capacitor voltage, electrolytic capacitor C 1 And C 2 Fluctuating between 18.8V and 20.0V. The result shows that the capacitor voltage is in the period of the converter operationFluctuations within acceptable limits, without any external balancing circuits or complex control algorithms.
Example 3
The embodiment provides a DC/AC conversion system for new energy access, which comprises a controller and a multi-level converter, wherein the multi-level converter adopts the high-gain DC-AC converter for new energy access in embodiment 1. And when the controller controls the switching tube in the high-gain DC-AC converter for new energy access to act, executing the modulation method of the high-gain DC-AC converter for new energy access described in the embodiment 1.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same; while the invention has been described in detail with reference to the preferred embodiments, those skilled in the art will appreciate that: modifications may be made to the specific embodiments of the present invention or equivalents may be substituted for part of the technical features thereof; without departing from the spirit of the invention, it is intended to cover the scope of the invention as claimed.
Claims (5)
1. The utility model provides a high gain DC-AC converter for new forms of energy inserts which characterized in that:
the power supply comprises a left half-bridge circuit, a T-type inverter unit, an n-level M-type boosting unit and a right half-bridge circuit which are sequentially connected in series, wherein n is more than or equal to 1;
the T-shaped inverter unit comprises a switching tube T 1 Switch tube T 2 Electrolytic capacitor C with equal capacitance a And C b DC power supply U dc ；
The electrolytic capacitor C a Is connected with the DC power supply U dc The positive electrode of the electrolytic capacitor C is connected with b Cathode of (2) and DC power supply U dc The negative electrode of the electrolytic capacitor C is connected with a Is connected with the electrolytic capacitor C b An anode of (a); the switch tube T 1 E end of (2) and the switch tube T 2 E end of the switch tube T is connected with 2 Is connected to the electrolytic capacitor C a Is connected to the cathode of the electrolytic capacitor C b Is connected with the anode of the switch tube T 1 Is connected to the left half-bridge circuit as the negative output of the high-gain DC-AC converter;
the M-type boosting unit comprises a switching tube S n1 Switch tube S n2 Switch tube S n3 Switch tube S n4 Switch tube S n5 Switch tube S n6 And an electrolytic capacitor C n1 Electrolytic capacitor C n2 ；
The switch tube S n1 C terminal of (C) and said switching tube S n3 The C end of the switch tube S is connected and then used as the positive input end of the M-shaped boosting unit n1 E end of (2) and the switch tube S n2 E end connection of the switch tube S n2 C terminal of (C) and said electrolytic capacitor C n1 Is used as the positive output end of the M-shaped boosting unit after being connected with the anode;
the switch tube S n5 E terminal of (2) and the switching tube S n4 E end of the M-type boosting unit is connected and then used as a negative input end of the M-type boosting unit, and the switching tube S n5 C terminal of (C) and the switch tube S n6 C-terminal connection of the switch tube S n6 E terminal of (C) and the electrolytic capacitor C n2 Is used as the negative output end of the M-type boosting unit after being connected with the cathode of the M-type boosting unit;
the electrolytic capacitor C n1 Is connected to the cathode of the electrolytic capacitor C n2 Is connected with the anode of the battery;
the switch tube S n3 E terminal of (2) and the switching tube S n4 Is connected to the electrolytic capacitor C at the C terminal n1 Is connected to the cathode of the electrolytic capacitor C n2 Is connected to the anode of the battery;
the switch tube S n1 E terminal of (2) and the switching tube S n2 Is connected with the E end of the switch tube S n5 C terminal of (C) and said switching tube S n6 Is connected with the C end connection point of the (C) terminal;
the positive input end of the 1 st stage M-type boosting unit is connected to the direct current power supply U dc The negative input end of the 1 st stage M-type boosting unit is connected to the DC power supply U dc Is a negative electrode of (a);
the positive output end of the upper M-shaped boosting unit is connected with the positive input end of the lower M-shaped boosting unit, and the negative output end of the upper M-shaped boosting unit is connected with the negative input end of the lower M-shaped boosting unit;
the positive output end and the negative output end of the n-th stage M-type boosting unit are connected to the right half-bridge circuit;
the left half-bridge circuit comprises a switching tube S 7 And a switch tube S 8 ；
The switch tube S 7 C terminal of (C) and the electrolytic capacitor C a Is connected with the anode of the switch tube S 7 Is connected to the negative output of the high gain DC-AC converter; the switch tube S 8 E terminal of (C) and the electrolytic capacitor C b Is connected with the cathode of the switch tube S 8 Is connected to the negative output of the high gain DC-AC converter;
the right half-bridge circuit comprises a switching tube S 9 And S is 10 ；
The switch tube S 9 Electrolytic capacitor C of C end and n-th M-stage booster unit n1 Is connected with the anode of the switch tube S 10 Electrolytic capacitor C of E end and n-th M-stage booster unit n2 Is connected with the cathode of the switch tube S 9 E terminal of (2) and the switching tube S 10 And is connected as the positive output of the high gain DC-AC converter.
2. A modulation method of a high-gain DC-AC converter for new energy access is characterized in that: generating a driving signal by which the N-stage M-type boosting unit in the high-gain DC-AC converter for new energy access according to claim 1 is cascade-charged so that the number of output levels N of the high-gain DC-AC converter for new energy access is 2 n+3 -3 sum voltage gains G of 2 n+1 -1。
3. The modulation method of a high-gain DC-AC converter for new energy access according to claim 2, wherein the high-gain DC-AC converter is modulated by selecting an in-phase carrier stacked PWM method:
with 2 n+3 -4 triangular carriersAnd sine modulated wave V ref Comparing, and logically combining the generated pulses according to the states of the switching tubes under each output level to obtain logic signals for controlling the on-off states of the switching tubes;
in the modulation method, triangular carrierWith the same amplitude A c And frequency f c The amplitude of the sine wave is A ref The modulation ratio M and the voltage gain G are defined as:
M=A ref /（2 n+2 -2）A c
G=V out /（V dc ）
wherein V is out To output the voltage amplitude, V dc Is the input voltage; the value range of the modulation ratio M is more than 0 and less than or equal to 1;
when (when)When j is E [1, 2, …,2 n+2 -2]The converter outputs 2j+1 level.
4. The DC/AC conversion system for new energy access comprises a controller and a multi-level converter, and is characterized in that: the multi-level converter adopts the high-gain DC-AC converter for new energy access as claimed in claim 1.
5. The DC/AC conversion system for new energy access according to claim 4, wherein: the controller performs the steps of the modulation method of the high-gain DC-AC converter for new energy access according to any one of claims 2 to 3 when controlling the switching tube in the high-gain DC-AC converter for new energy access to operate.
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