CN111711374B - Modular parallel four-level converter system and method - Google Patents
Modular parallel four-level converter system and method Download PDFInfo
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- CN111711374B CN111711374B CN202010603585.1A CN202010603585A CN111711374B CN 111711374 B CN111711374 B CN 111711374B CN 202010603585 A CN202010603585 A CN 202010603585A CN 111711374 B CN111711374 B CN 111711374B
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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
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
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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
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
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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
- H02M7/4835—Converters with outputs that each can have more than two voltages levels comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage
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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
- H02M7/53875—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 with analogue control of three-phase output
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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
- H02M7/539—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 with automatic control of output wave form or frequency
- H02M7/5395—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 with automatic control of output wave form or frequency by pulse-width modulation
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
- H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
- H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
- H02P27/08—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation
- H02P27/12—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation pulsing by guiding the flux vector, current vector or voltage vector on a circle or a closed curve, e.g. for direct torque control
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Abstract
The present disclosure provides a modular four-level converter system comprising: the system comprises a first sub-module and at least one Nth sub-module connected with the first sub-module in parallel; each submodule comprises a converter and a controller, the converter of the first submodule is connected with the direct current side of the converter of the Nth submodule in parallel, and the alternating current side of the first submodule is connected with a filter and then connected with the filter in parallel through a power grid; the controller controls the circulation among all the converters according to the zero sequence circulation information; the technical effect of realizing the requirement of large capacity of the equipment is achieved; the vector action time is changed under different modulation degrees, so that the circulating current between the converters is reduced; the method is still suitable for the working condition that the current and the circuit parameters of the converter are not equal.
Description
Technical Field
The present disclosure relates to a modular parallel four-level converter system and method.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
With the rapid development of new energy, the grid-connected power quality of the new energy is required to be higher by the power grid. The advent of four-level inverters just solved this problem. Compared with the traditional two-level inverter and the traditional three-level inverter, the four-level inverter has the advantages of good output waveform quality, small filter size and the like. Among the four-level topologies, the NNPC topology is gaining wide attention due to the small number of switches. In addition, due to the influence of current stress of the switching tube, the capacity of a single inverter is limited, and the application in a high-power occasion is difficult to meet. The parallel connection of the inverters becomes an ideal scheme in a high-power photovoltaic grid-connected power generation system and a wind power generation system.
However, for the mismatch of resistance and inductance between modules, and the difference of algorithms between different converters, the circulating current between the converters is increased. The circulating current affects the output current waveform quality of the inverter and burns out the IGBT itself when severe.
Disclosure of Invention
In order to solve the technical problem, the present disclosure provides a modular four-level converter system and a control method, which implement the circulating current suppression of multiple high-power conversion systems and improve the waveform quality of a grid-connected converter.
In a first aspect, the present disclosure provides a modular four-level converter system comprising: the system comprises a first sub-module and at least one Nth sub-module connected with the first sub-module in parallel; each submodule comprises a converter and a controller, the converter of the first submodule is connected with the direct current side of the converter of the Nth submodule in parallel, and the alternating current side of the first submodule is connected with a filter and then connected with the filter in parallel through a power grid; and the controller controls the circulation among the converters according to the zero sequence circulation information.
In a second aspect, the present disclosure also provides a method of using the modular four-level converter system according to the first aspect, the steps including:
modeling the modular four-level converter system;
designing a current controller aiming at d-axis and q-axis currents of each submodule;
designing a zero-sequence circulation controller according to circulation information i of two convertersz1And iz2And obtaining zero-sequence circulating current information by the inductances of the Nth converter and the first converter and the zero-sequence duty ratio.
Furthermore, the circulation between each converter is controlled according to the zero sequence circulation information, circulation suppression is realized by changing a zero vector in a low modulation degree, and circulation suppression is realized by changing a small vector in a high modulation degree.
Compared with the prior art, this disclosure possesses following beneficial effect:
1. according to the converter, the first sub-module and the at least one Nth sub-module which is connected with the first sub-module in parallel are arranged through parallel connection of the converters, the converters of the first sub-module are connected with the direct current side of the converters of the Nth sub-module in parallel, the alternating current side of the converters of the Nth sub-module is connected with the filter in parallel through the power grid, the technical problem that due to the influence of current stress of a switch tube, the capacity of a single converter is limited, the application in a high-power occasion is difficult to meet is solved, and the technical effect of large-capacity requirements of equipment is achieved.
2. The method controls the circulation among all converters according to the zero sequence circulation information, realizes circulation suppression by changing a zero vector at a low modulation degree, realizes circulation suppression by changing a small vector at a high modulation degree, solves the technical problems that the mismatching of resistance and inductance among modules can cause the circulation between the converters to be intensified, the circulation can influence the waveform quality of the output current of the converters, and the IGBT can be burnt out when the circulation is serious because of different algorithms among different converters, realizes the change of the vector action time under different modulation degrees, and reduces the circulation among the converters.
3. The present disclosure designs an optimal controller for d-axis and q-axis currents; adding an optimal circulation controller, designing a zero-sequence circulation controller according to circulation information i of the two convertersz1And iz2The inductance and the zero sequence duty ratio of the Nth converter and the first converter acquire zero sequence circulation information, the technical problems that circulation can affect the waveform quality of output current of the converters and the IGBT can be burnt out when serious are solved, and the method is still applicable to working conditions that current and circuit parameters of the converters are unequal.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the application and, together with the description, serve to explain the application and are not intended to limit the application.
Fig. 1 is a structural diagram of a parallel system of four-level converters in embodiment 1 of the present disclosure;
fig. 2 is a control circuit diagram of a parallel four-level converter in embodiment 1 of the present disclosure;
fig. 3 is a block diagram of a control system controller in embodiment 2 of the present disclosure.
The specific implementation mode is as follows:
the present disclosure is further described with reference to the following drawings and examples.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
Example 1
As shown in fig. 1, a modular four-level converter system comprises: the system comprises a first sub-module and at least one Nth sub-module connected with the first sub-module in parallel; each submodule comprises a converter and a controller, the converter of the first submodule is connected with the direct current side of the converter of the Nth submodule in parallel, and the alternating current side of the first submodule is connected with a filter and then connected with the filter in parallel through a power grid; and the controller controls the circulation among the converters according to the zero sequence circulation information.
Furthermore, the converter comprises three bridge arms connected in parallel, each bridge arm comprises a capacitor, a diode and six switching tubes connected in series in sequence, and the switching tubes are clamped through the diodes and the capacitors.
Further, the bridge arm comprises six switching tubes, namely a first switching tube, a second switching tube, a third switching tube, a fourth switching tube, a fifth switching tube and a sixth switching tube; the emitter of the first switching tube is connected with the collector of the second switching tube, the emitter of the second switching tube is connected with the collector of the third switching tube, the emitter of the third switching tube is connected with the collector of the fourth switching tube, the emitter of the fourth switching tube is connected with the collector of the fifth switching tube, and the emitter of the fifth switching tube is connected with the collector of the sixth switching tube; the collectors of the first switching tubes of the three bridge arms are connected in parallel and then connected to the positive electrode of the direct current side, and the emitters of the sixth switching tubes of the three bridge arms are connected in parallel and then connected to the negative electrode of the direct current side;
furthermore, the device also comprises two flying capacitors which are respectively a first capacitor and a second capacitor; the first end of the first capacitor is connected with the common end of the first switch tube and the second switch tube, the second end of the first capacitor is connected with the first end of the second capacitor, and the second end of the second capacitor is connected with the common end of the fifth switch tube and the sixth switch tube.
Furthermore, the LED lamp also comprises two diodes which are respectively a first diode and a second diode; the negative electrode of the first diode is connected with the common ends of the second switching tube and the third switching tube, the positive electrode of the first diode is connected with the negative electrode of the second diode, and the positive electrode of the second diode is connected with the common ends of the fourth switching tube and the fifth switching tube.
And the two capacitors are connected in parallel with the bridge arm circuit, one end of the two capacitors is connected to the positive electrode of the direct current side after being connected in series, and the other end of the two capacitors is connected to the negative electrode of the direct current side.
Further, the switching tube may be an IGBT tube or an MOS tube, and as a preferred scheme, the switching tube is an IGBT tube.
The controller is also connected with the protection circuit, and the driving circuit outputs a PWM signal to drive the IGBT tube in the bridge arm to be switched on and switched off.
Further, the protection circuit realizes overvoltage and overcurrent protection of the converter system; the conditioning circuit conditions the relevant signals measured by the Hall sensor to obtain analog signals which can be received by the sampling circuit; the sampling circuit converts the conditioned analog signal into digital quantity and transmits the digital quantity to the controller; the controller is used for generating a driving signal for controlling the normal operation of the system.
Further, the controller comprises a current controller and a zero sequence circulating current controller, and the current controller adjusts an optimal current value according to d-axis and q-axis currents of each submodule; the current controller is connected with a driving circuit, and the driving circuit outputs a PWM signal to drive the on and off of an IGBT tube in a bridge arm;
further, the zero sequence circulation controller is used for controlling the circulation of the two converters according to the circulation information i of the first modulez1And iz2Acquiring zero-sequence circulating current information by the inductances and the zero-sequence duty ratios of the Nth converter and the first converter; controlling the circulation between the converters according to the zero-sequence circulation information, wherein a zero-sequence circulation controller is connected with a driving circuit, and the driving circuit outputs a PWM signal to drive the on and off of the IGBT tubes in the bridge arms;
furthermore, circulation suppression is realized by changing a zero vector at a low modulation degree (less than 1/3), and circulation suppression is realized by changing a small vector at a high modulation degree (more than 1/3). The vectors include a large vector, a medium vector, a small vector, and a zero vector.
Further, the obtaining of the zero-sequence circulating current information specifically includes: and calculating the acquired data as zero-sequence circulating current information by subtracting the product of the inductance of the first filter and the zero-sequence circulating current of the first converter from the product of the inductance of the nth filter and the zero-sequence circulating current of the nth converter, then adding the product of the input voltage and the time to obtain a ratio, adding the difference value between the duty ratio of the nth converter which is one sixth of the product of the inductance of the first filter and the zero-sequence circulating current of the first converter and the duty ratio of the first converter, and further adding the difference value between the nth converter and the first converter which select different values according to the sector.
Specifically, fig. 3 shows a control circuit diagram of the four-level converter. The control circuit comprises a protection circuit, a driving circuit, a sampling circuit and a conditioning circuit, the conditioning circuit is connected with the sampling circuit, the sampling circuit is connected with a DSP module, the DSP module is in two-way communication with the protection circuit, the DSP module is connected with the driving circuit, and the driving circuit outputs PWM signals to drive the IGBT tubes in the bridge arms to be switched on and off. The converter may be an inverter.
The conditioning circuit collects the capacitance voltage of each phase and the three-phase current i output by the filtera、ib、ic。
The signal conditioning circuit and the control voltage have over/under voltage protection and over current protection; the conditioning circuit conditions the relevant signals measured by the Hall sensor to obtain analog signals which can be received by the sampling circuit. The sampling and conversion of the AD converter are controlled by the DSP, and the conditioned analog signals are converted into digital quantity. The digital signal processing, SPWM control and PWM generation are realized by a DSP, and finally generated PWM signals are sent to a driving circuit to control the on-off of the IGBT tube.
The IGBT tube is an Insulated Gate Bipolar Transistor (IGBT).
And controlling the circulation current between the converters by using an optimal circulation current controller, wherein the optimal controller inputs parameters such as zero sequence voltage, inductance, current, resistance, circulation current and the like of the first inverter and the i inverters. And the circulation suppression is realized by changing a zero vector at a low modulation degree (less than 1/3) and by changing a small vector at a high modulation degree (more than 1/3).
Example 2
A method for using a modular four-level converter system realizes the circulation suppression of a plurality of high-power inverter systems and improves the waveform quality of a grid-connected inverter. The method comprises the following steps:
firstly, modeling a modular four-level converter system to form a first sub-module and at least one Nth sub-module connected with the first sub-module in parallel;
designing a current controller according to d-axis and q-axis currents of each submodule, wherein the current controller is matched with a magnetic pole axis in a converter to be called a longitudinal axis (also called a direct axis and a d axis), and the current controller is perpendicular to the magnetic pole axis to be called a transverse axis (also called a quadrature axis and a q axis); the current controller adjusts the optimal current value according to the d-axis current and the q-axis current of each submodule; the current controller is connected with a driving circuit, and the driving circuit outputs a PWM signal to drive the on and off of an IGBT tube in a bridge arm;
then designing a zero sequence circulating current controller, wherein controller information of the zero sequence circulating current controller comprises zero sequence voltage, resistance, inductance and circulating current of the first inverter and the Nth inverter; the zero sequence circulation controller is used for controlling the circulation of the two converters according to circulation information i of the first modulez1And iz2N stage and first stage transformationsObtaining zero-sequence circulating current information by the inductance and the zero-sequence duty ratio of the device; controlling the circulation between the converters according to the zero-sequence circulation information, wherein a zero-sequence circulation controller is connected with a driving circuit, and the driving circuit outputs a PWM signal to drive the on and off of the IGBT tubes in the bridge arms; and the circulating current suppression is realized by changing a zero vector at a low modulation degree (less than 1/3) and by changing a small vector at a high modulation degree (more than 1/3).
In which the optimal controller requires two transducers circulation information i of the module 1z1And iz2The inductance and the zero sequence duty ratio of the ith station and the first station, and the obtaining of the zero sequence circulating current information specifically comprise: the method comprises the steps of subtracting the product of the inductance of the filter 1 and the zero-sequence circulating current of the inverter 1 from the product of the inductance of the filter n and the zero-sequence circulating current of the inverter n, carrying out a ratio on the product of input voltage and time, adding a difference value of one sixth of the duty ratio of the inverter n and the duty ratio of the inverter 1, further adding a difference value of different values selected by the inverter n and the inverter 1 according to sectors, and calculating the obtained data to be zero-sequence circulating current information.
The specific form is as follows:
wherein:
The method is still applicable to the condition that the parameters and the working conditions of the converter are inconsistent; the method is simple to implement, strong in expansibility on a parallel system, simple to apply and strong in practicability; the method has wide prospect in the field of renewable energy sources such as photovoltaic power generation systems, wind power generation systems and the like.
Although the present disclosure has been described with reference to specific embodiments, it should be understood that the scope of the present disclosure is not limited thereto, and those skilled in the art will appreciate that various modifications and changes can be made without departing from the spirit and scope of the present disclosure.
Claims (7)
1. A modular four-level converter system, comprising: the system comprises a first sub-module and at least one Nth sub-module connected with the first sub-module in parallel; each submodule comprises a converter and a controller, the converter of the first submodule is connected with the direct current side of the converter of the Nth submodule in parallel, and the alternating current side of the first submodule is connected with a filter and then connected with the filter in parallel through a power grid; the controller controls the circulation among all the converters according to the zero sequence circulation information;
the controller comprises a current controller and a zero sequence circulation controller, and the zero sequence circulation controller is used for circulating current information i of the two converters of the first modulez1And iz2Acquiring zero-sequence circulating current information by the inductances and the zero-sequence duty ratios of the Nth converter and the first converter; controlling the circulation between the converters according to the zero sequence circulation information;
the method for acquiring the zero-sequence circulation information specifically comprises the following steps: subtracting the product of the inductance of the first filter and the zero-sequence circulating current of the first converter from the product of the inductance of the nth filter and the zero-sequence circulating current of the nth converter, then carrying out a ratio on the product of the input voltage and the time, adding a difference value of one sixth of the duty ratio of the nth converter and the duty ratio of the first converter, further adding a difference value of different values selected by the nth converter and the first converter according to the sector, and calculating the obtained data as zero-sequence circulating current information; the specific formula is as follows:
wherein:
dxnis the duty cycle of inverter n，VdcIs the input voltage, hznDifferent values are selected according to the sector, L is the filter inductance, izIs the zero sequence circulating current of the inverter.
2. The modular four-level converter system according to claim 1, wherein the converter comprises three legs connected in parallel, each leg comprising a capacitor, a diode and six switching tubes connected in series in sequence, the switching tubes being clamped by the diode and the capacitor.
3. The modular four-level converter system according to claim 2, further comprising a control circuit, wherein the control circuit is a conditioning circuit, a sampling circuit, a controller and a driving circuit which are connected in sequence, and the driving circuit outputs a PWM signal to drive the switching tubes in the bridge arms to be turned on and off.
4. The modular four-level converter system according to claim 1, wherein the current controller adjusts the current value of the converter for d-axis and q-axis currents of each sub-module.
5. The modular four-level converter system according to claim 1, wherein said zero sequence circulating current controller implements zero sequence circulating current suppression with changing zero vector at low modulation and implements zero sequence circulating current suppression with changing small vector at high modulation.
6. A method of using a modular four-level converter system according to any of claims 1-5, the steps comprising:
firstly, modeling a modular four-level converter system;
designing a current controller aiming at d-axis and q-axis currents of each submodule;
designing a zero-sequence circulating current controller, wherein the zero-sequence circulating current controller acquires zero-sequence circulating current information according to circulating current information iz1 and iz2 of the two converters, inductance of the Nth converter and the first converter and a zero-sequence duty ratio;
the method comprises the following specific steps of obtaining zero-sequence circulation information: subtracting the product of the inductance of the first filter and the zero-sequence circulating current of the first converter from the product of the inductance of the nth filter and the zero-sequence circulating current of the nth converter, then carrying out a ratio on the product of the input voltage and the time, adding a difference value of one sixth of the duty ratio of the nth converter and the duty ratio of the first converter, further adding a difference value of different values selected by the nth converter and the first converter according to the sector, and calculating the obtained data as zero-sequence circulating current information; the specific formula is as follows:
wherein:
dxnis the duty cycle of inverter n, VdcIs the input voltage, hznDifferent values are selected according to the sector, L is the filter inductance, izIs the zero sequence circulating current of the inverter.
7. Use of the method according to claim 6, characterized in that the control of the converter-to-converter circulating currents is based on zero sequence circulating current information, circulating current suppression is achieved with changing zero vectors at low modulation and circulating current suppression is achieved with changing small vectors at high modulation.
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|---|---|---|---|---|
| CN102570883A (en) * | 2011-06-03 | 2012-07-11 | 深圳市英威腾电气股份有限公司 | Three-level inverter narrow-pulse elimination and midpoint voltage control method and device |
| CN207638580U (en) * | 2017-11-07 | 2018-07-20 | 江苏固德威电源科技股份有限公司 | Four level three-phase grid-connected inverters and electricity generation system |
| CN109802587A (en) * | 2019-02-28 | 2019-05-24 | 山东大学 | Three level NPC converter system of modularization and control method based on coupling inductance |
-
2020
- 2020-06-29 CN CN202010603585.1A patent/CN111711374B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102570883A (en) * | 2011-06-03 | 2012-07-11 | 深圳市英威腾电气股份有限公司 | Three-level inverter narrow-pulse elimination and midpoint voltage control method and device |
| CN207638580U (en) * | 2017-11-07 | 2018-07-20 | 江苏固德威电源科技股份有限公司 | Four level three-phase grid-connected inverters and electricity generation system |
| CN109802587A (en) * | 2019-02-28 | 2019-05-24 | 山东大学 | Three level NPC converter system of modularization and control method based on coupling inductance |
Non-Patent Citations (1)
| Title |
|---|
| 基于改进型零序环流抑制方法的T 型三电平并联并网系统;邢相洋等;《中国电机工程学报》;20170720;第37卷(第14期);第3.2节 * |
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