CN111245269A - Modularized multi-level inverter based on micro energy storage unit - Google Patents
Modularized multi-level inverter based on micro energy storage unit Download PDFInfo
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- CN111245269A CN111245269A CN202010135071.8A CN202010135071A CN111245269A CN 111245269 A CN111245269 A CN 111245269A CN 202010135071 A CN202010135071 A CN 202010135071A CN 111245269 A CN111245269 A CN 111245269A
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- energy storage
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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
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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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- Engineering & Computer Science (AREA)
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- Inverter Devices (AREA)
Abstract
The invention discloses a modularized multi-level inverter based on a miniature energy storage unit, which comprises four identical bridge arms and a load; the four bridge arms are divided into two completely identical groups, each group is formed by connecting two bridge arms in series, and the two groups are connected end to end; each bridge arm comprises N energy storage sub-modules; the energy storage submodule comprises a first power switch device, a second power switch device, a first diode, a second diode and a lithium battery. The invention can effectively solve the problems of capacitor voltage sharing, small output level number, high input side equipment voltage and the like of the conventional multi-level inverter.
Description
Technical Field
The invention relates to a modularized multi-level inverter based on a micro energy storage unit, and belongs to the technical field of power electronic converters.
Background
In the world, the multilevel conversion technology is more and more widely applied to become a hot spot of the power electronic technology, which is generated under the condition that the withstand voltage value and the current withstand value of a high-power electronic device cannot meet the application requirements, and the modular multilevel technology has many specific advantages and is paid attention by many people. Although the types of power electronic devices are continuously updated, the manufacturing level is continuously improved, and the withstand voltage value and the current withstand value of products are continuously improved, the traditional two-level topological structure voltage type inverter still has difficulty in meeting the urgent requirements of people on high power, high voltage and high frequency.
In order to solve the above problems, researchers have proposed multilevel inverters having various topologies, such as diode-clamped multilevel inverters, flying capacitor multilevel inverters, and cascade multilevel inverters. However, the research of the existing multi-level inverter still has a series of problems. For example, the problem of capacitor voltage equalization of the inverter needs a series of control strategies and measures to be taken by students to solve, and obviously, the complexity of normal operation of the inverter is increased. For another example, the number of the modules of the modular multilevel inverter is small, the number of the levels output by the inverter is positively correlated with the number of the modules, and the small number of the modules directly results in the small number of the output levels, thereby increasing the low-frequency harmonic wave. In addition, if the inverter is applied to occasions with high power and high voltage, the requirements on the voltage resistance and the current resistance of the power switching device are higher, and the cost of system design is further increased. For example, the input side of the multi-level inverter needs to be connected with a direct current device for outputting high voltage, which obviously increases the volume and cost of the inverter, reduces the convenience of the inverter, and increases the operation risk of the connected high voltage device.
Disclosure of Invention
The technical problem is as follows: the existing multi-level inverter has the problems of capacitance voltage balancing, small output level number, high input side equipment voltage and the like, and the modularized multi-level inverter based on the miniature energy storage unit is provided for solving a series of problems.
The technical scheme is as follows: a modularized multi-level inverter based on a miniature energy storage unit comprises four identical bridge arms and a load; the four bridge arms are divided into two completely identical groups, each group is formed by connecting two bridge arms in series, and the two groups are connected end to end; each bridge arm comprises N energy storage sub-modules; the energy storage submodule comprises a first power switch device, a second power switch device, a first diode, a second diode and a lithium battery; the emitter of the first power switch tube is respectively connected with the collector of the second power switch tube and the anode of the output of the energy storage submodule; the positive electrode of the lithium battery is connected with the collector electrode of the first power switch tube; the emitting electrode of the second power switch tube is respectively connected with the negative electrode of the lithium battery and the negative electrode output by the energy storage submodule; the anode of the first diode is connected with the emitter of the first power switch tube; the cathode of the first diode is connected with the collector electrode of the first power switch tube; the anode of the second diode is connected with the emitter of the second power switch tube; the cathode of the second diode is connected with the collector electrode of the second power switch tube; one end of the load is connected with the middle point of one group of series-connected bridge arms, and the other end of the load is connected with the middle point of the other group of series-connected bridge arms.
As a preferred embodiment of the present invention, the four identical bridge arms are each formed by connecting N identical energy storage sub-modules in series, and the number of output levels of the inverter is large. The direct current at the input side of the inverter module is provided by an energy storage submodule, and the output voltage of the energy storage submodule is provided by the terminal voltage of a lithium battery E with a low voltage level through controlling the on and off of two power switch tubes with anti-parallel diodes.
Compared with the prior art, the invention has the following advantages:
1. the problem of capacitor voltage sharing does not exist
Each module of the existing modular multilevel inverter contains a capacitor, so that voltage sharing of the capacitor needs to be realized by adopting a corresponding control strategy, each energy storage unit of the inverter does not adopt the capacitor, and a lithium battery is adopted on a direct current side, so that the problem of voltage sharing of the capacitor does not need to be solved;
2. more actual energy storage units
The number of modules of the existing modular multilevel inverter is small, the number of output levels is in positive correlation with the number of modules, the small number of modules directly leads to the small number of output levels, and further leads to the increase of low-frequency harmonic waves. In addition, if the existing modular multilevel inverter is applied to occasions with high power and high voltage, the requirements on the voltage resistance and the current resistance of a power switch device are higher, and the cost of system design is further increased. The inverter energy storage units can reach dozens of hundreds, the number of output levels can also reach dozens of hundreds (if the number of energy storage units of each bridge arm is N, the number of output levels is N +1), so that the output low-frequency harmonic waves are greatly reduced, and the requirements on the voltage resistance and the current resistance of a power switch device cannot be high if the inverter is applied to occasions with high power and high voltage;
3. equipment without high voltage output at input side
The direct current voltage at the input side of the inverter is provided by combining the lithium batteries in each energy storage unit through a corresponding control mode, so that high-voltage direct current equipment at the input side of the traditional multi-level inverter is not needed, the size of the inverter is reduced, the reproducibility of a module is increased, the portability of the inverter in use is improved, and the safety of the operation and the operation of the inverter is also increased;
4. micro energy storage
Each energy storage unit of the inverter is a miniature energy storage unit consisting of a lithium battery with the voltage as small as several volts and a power switch device, and the lithium battery can release energy outwards through discharging and can also store energy through charging the lithium battery;
5. high practicability and wide application prospect
The invention solves various problems of the existing multi-level inverter, has obvious advantages, simple and reliable system and very high practical value and application prospect.
Drawings
FIG. 1 is a block diagram of a modular multilevel inverter of the present invention;
FIG. 2 is a basic control block diagram of the present invention;
FIG. 3 is a simulation waveform of the present invention with 8 energy storage units per arm and a given sinusoidal output current amplitude of 62.2A;
the various reference numbers in the figures are defined as follows:
1.1, 1.2, 1.3 and 1.4 are bridge arms which are formed by connecting N micro energy storage units in series, 1.5 is a load, and 1.6 is a concrete structure of the micro energy storage unit; 2.1 is an output current reference value, 2.2 is an actual output current value, 2.3 is a subtracter, 2.4 is a PR controller, 2.5 is a limiting module, 2.6 is a sine modulation wave signal, 2.7 is a modulation wave signal, 2.8 is a switch driving signal, and 2.9 is a triangular carrier signal.
Detailed Description
As shown in fig. 1, a modular multilevel inverter based on micro energy storage units comprises four identical legs and a load Z; the four bridge arms are divided into two completely identical groups, each group is formed by connecting two bridge arms in series, and the two groups are connected end to end; each bridge arm comprises N energy storage sub-modules; the energy storage submodule comprises two power switching devices T1And T2Two diodes D1And D2A lithium battery E; the power switch tube T1The emitter not only contacts another power switch tube T2The collector is connected with the anode of the output of the submodule; the anode of the lithium battery E and the power switch tube T1The collector electrodes are connected; the power switch tube T2The emitting electrode of the energy storage submodule is connected with the negative electrode of the lithium battery E and the negative electrode output by the energy storage submodule; the diode D1Anode and power switch tube T1The emitting electrodes are connected; the diode D1Negative pole and power switch tube T1The collector points of the two electrodes are connected; the diode D2Anode and power switch tube T2The emitting electrodes are connected; the diode D2Negative pole and power switch tube T2The collector points of the two electrodes are connected; one end of the load Z is connected with the middle point of one group of series-connected bridge arms, and the other end of the load Z is connected with the middle point of the other group of series-connected bridge arms. The input voltage of the multilevel inverter is provided by the lithium battery of each miniature submodule, and the voltage is larger than 311V.
As shown in fig. 2, the given sinusoidal current IresFor a desired load currentSaid output current IoIs the actual measured load current. The given sinusoidal current IresAnd the output current IoDifferencing generates an input signal to the PR controller. By appropriately adjusting the parameters of the PR controller, an appropriate output signal of the PR controller is generated. The output signal of the PR controller passes through the amplitude limiting regulator to generate the carrier wave vmSaid carrier vmThen comparing with the triangular carrier, and generating a trigger signal T corresponding to a power switch tube in each energy storage submodule by utilizing a carrier phase shift modulation strategyN1、TN2。
As shown in FIG. 3, to verify the present invention, a closed loop simulation was performed using the circuit topology of FIG. 1 and the basic control block diagram of FIG. 2, using PSIM. Each bridge arm of the modular multilevel inverter adopts 8 micro energy storage units, and a lithium battery in each micro energy storage unit is 84V; the load is resistance inductance, the resistance parameter is 5 omega, and the inductance parameter is 3 mH; taking the switching frequency in the inverter as 1 kHz; the output frequency is 50 Hz; the output given sinusoidal current amplitude was 62.2A. FIG. 3 shows, in sequence from top to bottom, the resulting output sinusoidal current given IresOutput current IoAnd a load voltage V with 9 levels outputoutThe simulated waveform of (2).
The invention discloses a modularized multi-level inverter based on a micro energy storage unit, wherein the difference between the micro energy storage unit of the modularized multi-level inverter and a module unit of a modularized multi-level converter provided at present is that the modularized energy storage unit adopts a micro idea, each micro energy storage unit is an energy storage device in the topology of the modularized multi-level converter provided at present, which is replaced by a single or a plurality of lithium batteries with standard voltage of only a few volts. Compared with other multi-level converters which use large batteries with the voltage as small as hundreds of volts and as large as thousands of volts to replace capacitors to form module units, on one hand, the converter has more advantages in the number of the module units, so that the more levels are generated, the smaller the harmonic waves are; on the other hand, the volume and the voltage grade of a single module unit are smaller, so that the operation is safer, the operation is more convenient, and the requirements of the required power switching device on voltage resistance and current resistance are lower. The invention creatively provides a multilevel converter based on a miniature energy storage unit by utilizing a infinitesimal idea, and aims to solve the problems of the currently known multilevel converter. The method has high practical value and easy popularization, verifies the feasibility of the method by simulation, can be applied to some key technical fields, and improves the electric energy quality of key loads.
The above description is only a preferred embodiment of the present invention, and the scope of the present invention is not limited to the above embodiment, but equivalent modifications or changes made by those skilled in the art according to the present disclosure should be included in the scope of the present invention as set forth in the appended claims. The modular multilevel inverter can be applied to the related fields of micro-grids, energy storage and the like.
Claims (3)
1. A modularized multi-level inverter based on a micro energy storage unit is characterized in that the modularized multi-level inverter comprises four identical bridge arms and a load; the four bridge arms are divided into two completely identical groups, each group is formed by connecting two bridge arms in series, and the two groups are connected end to end; each bridge arm comprises N energy storage sub-modules; the energy storage submodule comprises a first power switch device, a second power switch device, a first diode, a second diode and a lithium battery; the emitter of the first power switch tube is respectively connected with the collector of the second power switch tube and the anode of the output of the energy storage submodule; the positive electrode of the lithium battery is connected with the collector electrode of the first power switch tube; the emitting electrode of the second power switch tube is respectively connected with the negative electrode of the lithium battery and the negative electrode output by the energy storage submodule; the anode of the first diode is connected with the emitter of the first power switch tube; the cathode of the first diode is connected with the collector electrode of the first power switch tube; the anode of the second diode is connected with the emitter of the second power switch tube; the cathode of the second diode is connected with the collector electrode of the second power switch tube; one end of the load is connected with the middle point of one group of series-connected bridge arms, and the other end of the load is connected with the middle point of the other group of series-connected bridge arms.
2. The modular multilevel inverter based on the micro energy storage unit according to claim 1, wherein the four identical bridge arms are all formed by connecting N identical energy storage sub-modules in series.
3. The modular multilevel inverter based on micro energy storage cells of claim 1, wherein the direct current at the input side of the inverter is provided by an energy storage submodule.
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| CN104917393A (en) * | 2015-06-09 | 2015-09-16 | 合肥科威尔电源系统有限公司 | Photovoltaic and energy-storage integrated DC converter structure based on MMC technology |
| CN105048484A (en) * | 2015-09-08 | 2015-11-11 | 山东大学 | Battery state-of-health optimization control method for modular multilevel battery energy storage system |
| CN107039991A (en) * | 2017-04-24 | 2017-08-11 | 北京交通大学 | A kind of light storage off-network independent power supply device and method based on MMC topologys |
| CN206471841U (en) * | 2016-12-30 | 2017-09-05 | 中国移动通信集团设计院有限公司 | Electric energy router and micro-capacitance sensor structure |
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2020
- 2020-03-02 CN CN202010135071.8A patent/CN111245269A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101795080A (en) * | 2010-03-03 | 2010-08-04 | 中国科学院电工研究所 | Three-phase power electronics transformer for power distribution |
| CN201774263U (en) * | 2010-07-22 | 2011-03-23 | 荣信电力电子股份有限公司 | Non-transformer battery energy storage topological structure based on MMC modular multi-level inverter |
| CN104917393A (en) * | 2015-06-09 | 2015-09-16 | 合肥科威尔电源系统有限公司 | Photovoltaic and energy-storage integrated DC converter structure based on MMC technology |
| CN105048484A (en) * | 2015-09-08 | 2015-11-11 | 山东大学 | Battery state-of-health optimization control method for modular multilevel battery energy storage system |
| CN206471841U (en) * | 2016-12-30 | 2017-09-05 | 中国移动通信集团设计院有限公司 | Electric energy router and micro-capacitance sensor structure |
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