CN114553038A - Space type DC/AC converter and fault-tolerant operation method thereof - Google Patents

Space type DC/AC converter and fault-tolerant operation method thereof Download PDF

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Publication number
CN114553038A
CN114553038A CN202210183909.XA CN202210183909A CN114553038A CN 114553038 A CN114553038 A CN 114553038A CN 202210183909 A CN202210183909 A CN 202210183909A CN 114553038 A CN114553038 A CN 114553038A
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switch
switching tube
tube
converter
capacitor
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CN114553038B (en
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王要强
张亨泰
赖锦木
陈天锦
王克文
梁军
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Zhengzhou University
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Zhengzhou University
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/483—Converters with outputs that each can have more than two voltages levels
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • 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
    • 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
    • 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
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Rectifiers (AREA)

Abstract

The invention provides a space type DC/AC converter and a fault-tolerant operation method thereof, wherein the space type DC/AC converter comprises a direct-current power supply E, a basic switched capacitor module, N switched capacitor sub-modules, a half bridge I and a half bridge II; electrolytic capacitor C of ith switch capacitor submodulei3Electrolytic capacitor C of i-1 th switch capacitor submodule(i‑1)3Through a switching tube Si6And a switching tube Si7And (4) cross-connecting. The space type DC/AC converter is controlled to work in 2N +5 modes through a driving signal, and 2N +5 levels are output: 0. + -E, + -2E, … …, + - (N + 2) E; wherein N represents the number of switched capacitor sub-modules. The invention can be expanded by adding a capacitor and a switching device, and the space type DC/AC converter can bear open circuit caused by separating a charging loop and a discharging loopAnd (4) a barrier.

Description

Space type DC/AC converter and fault-tolerant operation method thereof
Technical Field
The invention relates to a converter, in particular to a space type DC/AC converter and a fault-tolerant operation method thereof.
Background
The multilevel converter is widely applied to the fields of renewable energy power generation systems (particularly photovoltaic power generation systems), power distribution systems, electric vehicles and the like. The main advantages of these systems include step voltages to achieve lower total harmonic distortion, low electromagnetic interference, and switching tubes subject to lower voltage stress.
As with conventional multilevel converters, research into Neutral Point Clamped (NPC), Flying Capacitors (FC), and cascaded H-bridge (CHB) multilevel converters has been well established. However, neutral point clamping and flying capacitor multilevel converters require a large number of diodes or capacitors, and implementing capacitor voltage self-balancing or additional charging circuits increases their complexity and cost. The CHB multilevel converter uses multiple isolated sources to boost the output level. Furthermore, the low voltage gain (maximum output voltage to input voltage ratio) and single expansion limit the development of conventional multilevel converters. To solve these problems, a new type of multilevel converter based on switched capacitor technology has been proposed and developed rapidly.
The capacitance of a switched capacitor multilevel converter (SCMLI) is charged in parallel with a dc power supply and discharged in series to achieve high voltage gain. Furthermore, compared to conventional multi-level converters, the SCMLI outputs the same level with fewer devices and has the advantage of self-balancing of the capacitor voltage and low voltage ripple.
Based on field experience, power devices such as Insulated Gate Bipolar Transistors (IGBTs) and metal-oxide semiconductor field effect transistors (MOSFETs) are prone to failure. Therefore, low reliability is one of the main problems of multilevel converters due to the large number of switching tubes and capacitors used.
Fault tolerant techniques are considered as an effective way to improve the reliability of converters, and in recent years, the fault tolerant operation of multilevel converters has received wide attention, mainly including two ways:
(1) the aim of configuring the redundant branch is to isolate the fault branch when a fault occurs and replace the fault branch with the redundant branch. This solution, while maintaining the continuity of the output level, increases the number of components, the converter cost and the control complexity;
(2) control solutions without additional components are not implemented by directly changing the control strategy of the converter, and such solutions have the inherent drawback of a reduced output level after a fault, limiting its application.
In order to solve the above problems, people are always seeking an ideal technical solution.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, and provides a space type DC/AC converter and a fault-tolerant operation method thereof.
In order to achieve the purpose, the invention adopts the technical scheme that:
the invention provides a space type DC/AC converter in a first aspect, which comprises a direct current power supply E, a basic switched capacitor module, N switched capacitor sub-modules, a half bridge I and a half bridge II, wherein the basic switched capacitor module comprises a switching tube S1Switch tube S2Switch tube S4Switch tube S5Diode D1Diode D2And an electrolytic capacitor C1And an electrolytic capacitor C2The half bridge I comprises a switching tube S8And a switching tube S9The half bridge II comprises a switching tube S10And a switching tube S11；
When N =1, the switched capacitor submodule comprises a switching tube S3Switch tube S6Switch tube S7Diode D3And an electrolytic capacitor C3；
Switch tube S of basic switch capacitor module1Respectively with the switching tube S2Input terminal of the switched capacitor submodule and a switching tube S of the switched capacitor submodule3The input end of the switch tube S is connected with the positive pole of the direct current power supply E1Respectively with said switchClosing pipe S4And the electrolytic capacitor C1Is connected to the anode of the switching tube S2Respectively with the switching tube S5Input terminal of the switched capacitor submodule and a switching tube S of the switched capacitor submodule6Input terminal and electrolytic capacitor C2The anode of (2) is connected; the switch tube S4Respectively with the switching tubes S of the switched capacitor sub-module7Of the diode D2And the electrolytic capacitor C2Is connected to the cathode of the switching tube S5Respectively with said diode D1And the electrolytic capacitor C1The cathode of (a) is connected;
switch tube S of switch capacitor submodule3Respectively with the switching tube S7And the electrolytic capacitor C3Is connected to the anode of the switching tube S6Respectively with said diode D3Input terminal and electrolytic capacitor C3The cathode of (a) is connected;
the negative electrode of the direct current power supply E is respectively connected with the diode D of the basic switch capacitor module1And diode D2And the diode D of the switched capacitor submodule3The output ends of the two-way valve are connected;
switching tube S of half-bridge I8And the electrolytic capacitor C of the basic switch capacitor module1Is connected with the anode of the switch tube S8And the output end of the switch tube S9Is connected with the input end of the switch tube S9And the electrolytic capacitor C of the basic switch capacitor module1The cathode of (a) is connected; switching tube S of half bridge II10And the electrolytic capacitor C of the switch capacitor submodule3Is connected to the anode of the switching tube S10And the output end of the switch tube S11Is connected with the input end of the switch tube S11And the output end of the switch capacitor submodule and the electrolytic capacitor C of the switch capacitor submodule3The cathode of (a) is connected;
when N is more than or equal to 2, the ith switch capacitor submodule comprises an electrolytic capacitor Ci3Two polesPipe Di3And a switch tube Si3Switch tube Si6And a switching tube Si7，2≤i≤N；
Electrolytic capacitor C of ith switch capacitor submodulei3Electrolytic capacitor C of i-1 th switch capacitor submodule(i-1)3Through a switching tube Si6And a switching tube Si7Cross-connecting; electrolytic capacitor C of ith switch capacitor submodulei3The anode of the switch tube Si3Is connected with the output end of the switch tube Si3Respectively connected with the positive electrode of the DC power supply E and the switching tube S of the basic switch capacitor module1Input terminal of, the switching tube S2Input terminal of and switching tube S(i-1)3The input ends of the two-way valve are connected; electrolytic capacitor C of ith switch capacitor submodulei3And a diode Di3Is connected to the input terminal of a diode Di3Respectively connected with the negative pole of the DC power supply E and the diode D(i-1)3Output terminal of the basic switched capacitor module, diode D1And diode D2The output ends of the two-way valve are connected;
electrolytic capacitor C of Nth switch capacitor submoduleN3With the switching tube S of the half-bridge II10Is connected to the input terminal of an electrolytic capacitor CN3And the switching tube S of the half bridge II11Is connected.
In a second aspect, the present invention provides a modulation method for a spatial DC/AC converter, which controls the spatial DC/AC converter according to claim 1 or 2 to operate in 2N +5 modes by a driving signal, and outputs 2N +5 levels: 0. + -E, + -2E, … …, + - (N + 2) E; wherein N represents the number of switched capacitor sub-modules.
A third aspect of the present invention provides a fault tolerant operation method of a space type DC/AC converter,
when the space type DC/AC converter has no open-circuit fault, the space type DC/AC converter comprising a switched capacitor submodule is controlled to work in seven modes through a driving signal, and seven levels are output: 0. e, + -2E and + -3E;
at the basic switch capacitor moduleSwitch tube S1When the converter fails, the drive signal controls the space type DC/AC converter comprising a switched capacitor submodule to work in five modes and output five levels: 0. e and 2E;
a switching tube S of the basic switch capacitor module2Or a switching tube S4Or a switching tube S5When the circuit is in failure, the space type DC/AC converter comprising a switched capacitor submodule is controlled to work in three modes through a driving signal, and three levels are output: 0 and. + -. E;
a switch tube S in the switch capacitor submodule3When the converter fails, the drive signal controls the space type DC/AC converter comprising a switched capacitor submodule to work in five modes and output five levels: 0. e and 2E;
a switch tube S in the switch capacitor submodule6Or a switching tube S7When the circuit is in failure, the space type DC/AC converter comprising the switched capacitor submodule is controlled to work in three modes through the driving signal, and three levels are output: 0 and. + -. E;
at the switching tube S of the half-bridge I8Or a switching tube S9When the converter fails, the drive signal controls the space type DC/AC converter comprising a switched capacitor submodule to work in five modes and output five levels: 0. e and 2E;
a switching tube S in the half bridge II10Or a switching tube S11When the converter fails, the drive signal controls the space type DC/AC converter comprising a switched capacitor submodule to work in five modes and output five levels: 0. e and 2E.
In a fourth aspect of the present invention, a spatial DC/AC conversion system includes a controller and a converter, where the converter is the spatial DC/AC converter.
In a fifth aspect of the present invention, a fault tolerant system of a space type DC/AC converter is provided, which includes a controller and the space type DC/AC converter, wherein the controller executes the steps of the fault tolerant operation method of the space type DC/AC converter when controlling the operation of the switching tube in the space type DC/AC converter.
The invention has the beneficial effects that:
1) the invention provides a space type DC/AC converter, which comprises a switched capacitor submodule and is characterized in that 1 direct current power supply, 3 capacitors and 11 switching devices are used for realizing 3-time voltage gain and 7-level alternating current voltage output; by separating the charging circuit and the discharging circuit, the topological structure can realize fault-tolerant operation and improve the reliability of the converter;
two half-bridges are used for replacing an H bridge to convert the polarity of an output level and reduce the voltage stress of a switching tube; wherein, the switch tube S1And S3The maximum voltage stress of the switching tube is 2E, and the maximum voltage stress of the other switching tubes is E;
2) the space type DC/AC converter only uses one direct current power supply, and the output level is improved by adding a switched capacitor submodule, so that the structure of the converter can be simplified to the greatest extent; each switched capacitor submodule comprises three switching tubes, a diode and an electrolytic capacitor, and in the modular expansion structure, 2 output levels are added to the space type DC/AC converter by adding one switched capacitor submodule;
3) the space type DC/AC converter has the advantages of low voltage ripple, and at least one capacitor is charged at any level;
4) the capacitor is independently charged by a direct current power supply, so that the fault capacitor in the space type DC/AC converter can be isolated by changing a control strategy;
5) at the switch tube S1Or diode D1When open-circuit fault occurs, the electrolytic capacitor C is connected by changing the control strategy1Isolated from its discharge circuit, switching tube S4And S8And S5And S9Are simultaneously turned on or off, the switching tubes S8And S9And conducting alternately. At this time, the space type DC/AC converter comprising the switched capacitor submodule works as a five-level converter;
in the opening of the pipe switch S2Or diode D2When open-circuit fault occurs, the switch tube S4And S7And a switching tube S5And S6Simultaneously switched on or off, capacitor C1And C3The series discharge cannot be made. At this time, the space type DC/AC converter comprising the switched capacitor submodule operates as a three-level converter;
at the switching tube S3Or diode D3When an open-circuit fault occurs, the space type DC/AC converter comprising the switched capacitor submodule operates as a five-level converter;
due to the switch tube S4And S5、S6And S7When one of the two switching tubes in the complementary state is in open-circuit fault, the other switching tube is kept in a conducting state; at the switch tube S4、S5、S6Or S7When any one of the switching tubes has an open-circuit fault, the space type DC/AC converter comprising the switched capacitor submodule operates as a three-level converter;
due to the switch tube S8And S9、S10And S11When one of the two switch tubes has an open-circuit fault, the other switch tube keeps a conducting state; at the switch tube S8、S9、S10Or S11When any one of the switching tubes has an open-circuit fault, the space type DC/AC converter comprising the switched capacitor submodule operates as a five-level converter;
6) the voltage balance, the boosting capacity and the capacity with inductive load of the capacitor can be kept in the running state before and after the fault; in the post-fault operating state, the voltage stress of the switching device and the voltage ripple of the capacitor are reduced or kept unchanged;
7) if a fast fuse or a breaker is used to isolate the short-circuit switch tube, the space type DC/AC converter can be used for short-circuit fault tolerance;
8) the fault-tolerant operating method is particularly suitable for an extended converter with high output levels, reduces four output levels at most, and is particularly suitable for an extended converter.
Drawings
FIG. 1 is a topological block diagram of a space-type DC/AC converter of the present invention;
fig. 2(a) to 2(g) are schematic circuit diagrams of seven operation modes of the space-type DC/AC converter (in normal operation) including a switched capacitor submodule according to the present invention;
FIG. 3 is a schematic diagram of the carrier and modulation waveforms of the present invention for a space-mode DC/AC converter including a switched capacitor sub-module;
FIG. 4 is a schematic diagram of the original PWM pulse shape of the space-type DC/AC converter of the present invention including a switched capacitor sub-module;
FIG. 5 is a waveform of control signals of each switching tube of the space type DC/AC converter including a switched capacitor submodule according to the present invention;
FIG. 6 is a schematic diagram of the target output waveform of the space-mode DC/AC converter of the present invention including a switched capacitor sub-module;
FIG. 7 is a schematic diagram of an output voltage waveform and an output current waveform of the space-type DC/AC converter with inductive load, which includes a switched capacitor sub-module according to the present invention;
FIGS. 8 (I) to 8 (V) show the switching tube S of the space-type DC/AC converter of the present invention including a switched capacitor sub-module1A circuit schematic diagram of five working modes in fault;
FIG. 9 shows a switching tube S1The output waveform schematic diagram of the fault-tolerant operation of the space type DC/AC converter comprising a switched capacitor submodule after the fault occurs;
FIGS. 10 (i) to 10 (v) show switching tubes S of a space-type DC/AC converter of the present invention comprising a switched capacitor sub-module8A circuit schematic diagram of five working modes in fault;
fig. 11 is a topology structure diagram of the expanded space-type DC/AC converter of the present invention.
Detailed Description
The technical solution of the present invention is further described in detail by the following embodiments.
Example 1
FIG. 1 is a schematic diagram showing a topology of a space-type DC/AC converter including a DC power supply E and a basic switched capacitor moduleN switched capacitor sub-modules, half-bridge I and half-bridge II, basic switched capacitor module includes switch tube S1Switch tube S2Switch tube S4Switch tube S5Diode D1Diode D2And an electrolytic capacitor C1And an electrolytic capacitor C2The half bridge I comprises a switching tube S8And a switching tube S9The half bridge II comprises a switching tube S10And a switching tube S11；
When N =1, the switch capacitor submodule comprises a switch tube S3Switch tube S6Switch tube S7Diode D3And an electrolytic capacitor C3；
Switch tube S of basic switch capacitor module1Respectively with the switching tube S2Input terminal of the switched capacitor submodule and a switching tube S of the switched capacitor submodule3The input end of the switch tube S is connected with the positive pole of the direct current power supply E1Respectively with the switching tube S4And the electrolytic capacitor C1Is connected to the anode of the switching tube S2Respectively with the switching tube S5Input terminal of the switched capacitor submodule and a switching tube S of the switched capacitor submodule6Input terminal and electrolytic capacitor C2The anode of (2) is connected; the switch tube S4The output ends of the two capacitors are respectively connected with a switch tube S of the switch capacitor submodule7Of the diode D2And the electrolytic capacitor C2Is connected to the cathode of the switching tube S5Respectively with said diode D1And the electrolytic capacitor C1The cathode of (a) is connected;
switch tube S of switch capacitor submodule3Respectively with the switching tube S7And the electrolytic capacitor C3Is connected to the anode of the switching tube S6Respectively with said diode D3Input terminal and electrolytic capacitor C3The cathode of (a) is connected;
the negative electrode of the direct current power supply E is respectively connected with the diode D of the basic switch capacitor module1And diode D2And the diode D of the switched capacitor submodule3The output ends of the two-way valve are connected;
switching tube S of half-bridge I8And the electrolytic capacitor C of the basic switch capacitor module1Is connected to the anode of the switching tube S8And the output end of the switch tube S9Is connected with the input end of the switch tube S9And the electrolytic capacitor C of the basic switch capacitor module1The cathode of (a) is connected; switching tube S of half bridge II10And the electrolytic capacitor C of the switch capacitor submodule3Is connected to the anode of the switching tube S10And the output end of the switch tube S11Is connected with the input end of the switch tube S11And the output end of the switch capacitor submodule and the electrolytic capacitor C of the switch capacitor submodule3The cathode of (a) is connected;
when N is more than or equal to 2, the ith switch capacitor sub-module comprises an electrolytic capacitor Ci3Diode Di3Switch tube Si3Switch tube Si6And a switching tube Si7，2≤i≤N；
Electrolytic capacitor C of ith switch capacitor submodulei3Electrolytic capacitor C of i-1 th switch capacitor submodule(i-1)3Through a switching tube Si6And a switching tube Si7Cross-connecting; electrolytic capacitor C of ith switch capacitor submodulei3The anode of the switch tube Si3Is connected with the output end of the switch tube Si3Respectively connected with the positive electrode of the DC power supply E and the switching tube S of the basic switch capacitor module1Input terminal of, the switching tube S2Input terminal of and switching tube S(i-1)3The input ends of the two-way valve are connected; electrolytic capacitor C of ith switch capacitor submodulei3And a diode Di3Is connected to the input terminal of a diode Di3Respectively connected with the negative pole of the DC power supply E and the diode D(i-1)3Output terminal of the basic switched capacitor module, diode D1And diode D2The output ends of the two-way valve are connected;
the Nth switchElectrolytic capacitor C of capacitor moduleN3With the switching tube S of the half-bridge II10Is connected to the input terminal of an electrolytic capacitor CN3And the switching tube S of the half bridge II11Is connected with the output end of the power supply.
Wherein, the electrolytic capacitor C of the ith switch capacitor submodulei3Electrolytic capacitor C of i-1 th switch capacitor submodule(i-1)3Through a switching tube Si6And a switching tube Si7Cross-connect, meaning: switch tube Si6Respectively connected with the switch tube S(i-1)7Input terminal of (1), switch tube S(i-1)3Output terminal and electrolytic capacitor C(i-1)3The anode of the anode is connected; switch tube Si6Respectively with a diode Di3Input terminal and electrolytic capacitor Ci3The cathode of the anode is connected; switch tube Si7Respectively connected with the switch tube Si3Output terminal and electrolytic capacitor Ci3The anode of the anode is connected; switch tube Si7Respectively with a diode D(i-1)3Input terminal of (1), switch tube S(i-1)6Output terminal and electrolytic capacitor C(i-1)3Are connected with each other.
It can be understood that the electrolytic capacitor C of the basic switch capacitor module of the space type DC/AC converter2Electrolytic capacitor C of first switch capacitor submodule3Through a switch tube S6And a switching tube S7And (4) cross-connecting.
Specifically, the switch tube S of the basic switch capacitor module4And a switching tube S5A switch tube S of the switch capacitor submodulei6And a switching tube Si7And switching tube S of half-bridge I and half-bridge II8Switch tube S9Switch tube S10Switch tube S11For the switching tube including the backward diode, the switching tube S of the basic switched capacitor module1And a switching tube S2And a switch tube S of the switch capacitor submodulei3Is a switch tube without a reverse diode. It will be appreciated that the space-mode DC/AC converter uses MOSFETs or IGBTs with anti-parallel diodes providing a direct current output from the AC output sideA channel for feeding back reactive energy at the input side; therefore, the space-type DC/AC converter has an ability to carry an inductive load.
It should be noted that the space-mode DC/AC converter can be expanded by increasing the number of the switched capacitor sub-modules, the DC power supply E charges all the switched capacitor sub-modules, and the switched capacitor sub-modules are connected in series to discharge to increase the output level. In the modular expansion structure, every time a switched capacitor submodule is added, the space type DC/AC converter is added with 2 output levels; the expansion mode not only can keep the advantages of the cascade expansion mode, but also only needs one direct-current power supply.
It can be understood that each switched capacitor submodule of the space-type DC/AC converter includes three switching tubes, a diode and an electrolytic capacitor, and two adjacent switched capacitor submodules are set as a preceding-stage switched capacitor submodule and a succeeding-stage switched capacitor submodule according to a positional relationship between the switched capacitor submodules and the basic switched capacitor module;
the electrolytic capacitor of the rear-stage switch capacitor submodule is connected with the electrolytic capacitor of the front-stage switch capacitor submodule in a cross way through two switch tubes of the rear-stage switch capacitor submodule, the anode of the electrolytic capacitor of the rear-stage switch capacitor submodule is also connected with the output end of the other switch tube of the rear-stage switch capacitor submodule, and the input end of the other switch tube of the rear-stage switch capacitor submodule is respectively connected with the anode of the direct-current power supply E and the switch tube S of the basic switch capacitor module1Input terminal of, the switching tube S2The input end of the first-stage switch capacitor submodule is connected with the input end of one of the switch tubes of the preceding-stage switch capacitor submodule; the cathode of the electrolytic capacitor of the rear-stage switch capacitor submodule is also connected with the input end of the diode of the rear-stage switch capacitor submodule, and the output end of the diode of the rear-stage switch capacitor submodule is respectively connected with the cathode of the direct-current power supply E, the output end of the diode of the front-stage switch capacitor submodule and the diode D of the basic switch capacitor module1And diode D2Is connected with the output end of the power supply.
It should be noted that the charging circuit and the discharging circuit in the space-type DC/AC converter are separated, so that the space-type DC/AC converter has fault-tolerant capability and expansibility; two 'half-bridges' are used instead of the H-bridge to switch the polarity of the output level and reduce the voltage stress of its switching tubes.
Example 2
On the basis of the spatial DC/AC converter in embodiment 1, this embodiment provides a specific implementation of a modulation method of the spatial DC/AC converter:
the spatial DC/AC converter in embodiment 1 is controlled to operate in 2N +5 modes by the driving signal, and outputs 2N +5 levels: 0. + -E, + -2E, … …, + - (N + 2) E; wherein N represents the number of switched capacitor sub-modules.
As shown in fig. 2(a) to 2(g), when the spatial DC/AC converter includes a switched capacitor submodule, the spatial DC/AC converter is controlled by the driving signal to operate in seven modes, and outputs seven levels: 0. e, 2E and 3E; the space type DC/AC converter controls the switch tube S4To a switching tube S7The on-off state of the electrolytic capacitor realizes the series connection of the electrolytic capacitors, and the switching tube S is controlled1To a switching tube S3Charging the electrolytic capacitor in the on state, switching tube S8And S9And S10And S11Alternately conducting to produce a negative level.
Fig. 2(a) to 2(g) show operation schematic diagrams of a spatial DC/AC converter including a switched capacitor submodule in different modes, where "+" and "-" represent positive and negative electrodes connected to a load, and an output voltage of the spatial DC/AC converter is denoted by U. When no open circuit fault occurs, the space type DC/AC converter comprising a switched capacitor submodule is configured to work in seven modes, including:
the working state a: switch tube S1Switch tube S5Switch tube S7Switch tube S8And a switching tube S11Conducting, turning off the other switch tubes and diode D1Conducting, keeping the rest diodes in an idle state, and outputting a voltage U of 3E;
as shown in FIG. 2(a), the switch tube S1DC power supply E, IIPolar tube D1Forming a charging circuit, a switch tube S1Conducting, the DC power supply E is an electrolytic capacitor C1Charging; switch tube S8And an electrolytic capacitor C1Switch tube S5And an electrolytic capacitor C2Switch tube S7And an electrolytic capacitor C3And a switching tube S11Forming a discharge circuit, a switching tube S5And S7On, the capacitance C1、C2And C3Discharging in series;
and (b) working state: switch tube S1Switch tube S5Switch tube S7Switch tube S8And a switching tube S10Conducting, turning off the other switch tubes and diode D1Conducting, keeping the rest diodes in an idle state, and outputting a voltage U of 2E;
as shown in FIG. 2(b), a switching tube S1DC power supply E and diode D1Form a charging circuit, a switch tube S1On, the DC power supply E is a capacitor C1Charging; switch tube S8And an electrolytic capacitor C1Switch tube S5And an electrolytic capacitor C2Switch tube S7And a switching tube S10Forming a discharge circuit, a switching tube S5And S7On, the capacitance C1、C2Discharging in series;
and (c) working state: switch tube S2Switch tube S4Switch tube S7Switch tube S8And a switching tube S11Conducting, turning off the other switch tubes and diode D2Conducting, keeping the rest diodes in an idle state, and outputting a voltage U of E;
as shown in FIG. 2(c), the switch tube S2DC power supply E and diode D2And an electrolytic capacitor C2Form a charging circuit, a switch tube S2On, the DC power supply E is a capacitor C2Charging; switch tube S8Switch tube S4And a switch tube S7And an electrolytic capacitor C3And a switching tube S11Forming a discharge circuit, a switching tube S4And S7On, the capacitance C3Discharging;
and (3) working state d: switch tube S1Switch tube S3Switch tube S5Switch tube S6Switch tube S9And a switching tube S11Conducting, turning off the other switch tubes and diode D1And a diode D3Conducting, keeping the rest diodes in an idle state, and keeping the output voltage U at 0;
as shown in FIG. 2(d), an electrolytic capacitor C1And a switch tube S1DC power supply E and switch tube S3And an electrolytic capacitor C3Diode D3And a diode D1Form a charging circuit, a switch tube S1And S3On, the DC power supply E is a capacitor C1、C3Charging; switch tube S9Switch tube S5Switch tube S6And a switching tube S11Forming a discharge loop;
and (e) working state: switch tube S1Switch tube S3Switch tube S5Switch tube S6Switch tube S9And a switching tube S10Conducting, turning off the other switch tubes and turning off the diode D1And a diode D3Conducting, keeping the rest diodes in an idle state, and outputting a voltage U of-E;
as shown in FIG. 2(e), an electrolytic capacitor C1Switch tube S1DC power supply E and switch tube S3Diode D3And a diode D1Form a charging circuit, a switch tube S1And S3On, the DC power supply E is a capacitor C1、C3Charging; switch tube S9Switch tube S5Switch tube S6And an electrolytic capacitor C3And a switching tube S10Forming a discharge circuit, a switching tube S5And S6On, the capacitor C3Discharging;
and (3) working state f: switch tube S3Switch tube S4Switch tube S6Switch tube S8And a switching tube S10Conducting, turning off the other switch tubes and turning off the diode D3Conducting, keeping the rest diodes in an idle state, and outputting a voltage U of-2E;
as shown in FIG. 2(f), the switch tube S3DC power supply E and diode D3Form a charging circuit, a switch tube S3On, the DC power supply E is a capacitor C3Charging; switch tube S8Switch tube S4And an electrolytic capacitor C2Switch tube S6And an electrolytic capacitor C3And a switching tube S10Forming a discharge circuit, a switching tube S4And S6On, the capacitance C2、C3Discharging in series;
and (3) working state g: switch tube S3Switch tube S4Switch tube S6Switch tube S9And a switching tube S10Conducting, turning off the other switch tubes and turning off the diode D3Conducting, keeping the rest diodes in an idle state, and outputting a voltage U of-3E;
as shown in FIG. 2(g), the switching tube S3DC power supply E and diode D3Form a charging circuit, a switch tube S3On, the DC power supply E is a capacitor C3Charging; switch tube S9Electrolytic capacitor C1Switch tube S4And an electrolytic capacitor C2Switch tube S6And an electrolytic capacitor C3And a switching tube S10Forming a discharge circuit, a switching tube S4And S6On, the capacitor C1Capacitor C2Capacitor C3And discharging in series.
It should be noted that when each switching tube of the space-type DC/AC converter including one switched capacitor submodule normally operates, a DC power supply can be used to realize seven-level step voltage output (± 3E, ± 2E, ± E, 0) and 3-time voltage gain; the maximum voltage stress of the switching tube is equal to 2E; wherein the switch tube S1And S3The maximum voltage stress of the switching tube is 2E, and the maximum voltage stress of the other switching tubes is E.
Further, when N =1, as shown in fig. 3, by comparing the sine-modulated wave UrefAnd six triangular carriers ua1To ua6Obtaining a logic signal u1To u6Logic signal u1To u6After logical combination, the driving signals of all the switching tubes are obtained through output, and the expression of the driving signals of all the switching tubes is as follows:
Figure 289639DEST_PATH_IMAGE001
when N is larger than or equal to 2, the modulation method of the space type DC/AC converter is the same as the principle when N = 1; by comparing sine-modulated waves UrefAnd N +2 triangular carriers ua1To ua（N+2）Obtaining a logic signal u1To uN+2Logic signal u1To u N+2And after logical combination, outputting to obtain the driving signals of each switching tube.
It can be understood that the present embodiment proposes a modulation strategy based on the space type DC/AC converter including a switched capacitor sub-module, and the modulation principle is as shown in fig. 3 to 6. The strategy adopts a carrier lamination pulse width modulation technology, 6 paths of triangular carriers with the same amplitude and the same frequency are sequentially laminated and are compared with 1 path of amplitude sinusoidal modulation waves, and then the obtained 6 paths of original pulse waveforms are logically combined to obtain a gate pole pulse signal for driving a switching tube to be switched on and switched off. The number of triangular carrier signals is determined based on the number of output levels (except 0), and the state of a switch tube is predetermined according to the operation state of the space type DC/AC converter, wherein the redundant switch combination is considered; the on-off state of the switching tube during one cycle is analyzed and compared with the pulse shown in fig. 4.
In addition, the switch tube S4And a switching tube S5Complementary working states, switching tube S6And a switching tube S7Operating in complementary states, switching tubes S8And a switching tube S9Operating in complementary states, switching tubes S10And a switching tube S11The space type DC/AC converter works in a complementary state, so that the control complexity of the space type DC/AC converter is reduced.
In this embodiment, the spatial DC/AC converter including a switched capacitor sub-module is verified through experiments according to the modulation method, and fig. 7 shows an output voltage V of the converter with an inductive loadoAnd a load current IoA waveform diagram of (a). From the waveform diagram, it can be seen that under the condition of resistive-inductive load (R-L)When the space type DC/AC converter operates stably, a standard 7-level step voltage waveform can be output, and the output voltage reaches 3 times of boost gain; the load current waveform appears as a smooth sinusoid and lags the output voltage waveform. Practice proves that the space type DC/AC converter has the capacity of providing inductive load and the self-balancing capacity of capacitance voltage.
It can be understood that when N is larger than or equal to 2, the first switched capacitor submodule comprises a switching tube S3Switch tube S6Switch tube S7Diode D3And an electrolytic capacitor C3The ith switched capacitor submodule comprises an electrolytic capacitor Ci3Diode Di3Switch tube Si3Switch tube Si6And a switching tube Si7。
In one embodiment, the space-type DC/AC converter includes two switched capacitor sub-modules to form a nine-level space-type converter, and the topology structure is as shown in fig. 11, and outputs nine levels: 0. e, ± 2E, ± 3E and ± 4E; the first-stage switch capacitor submodule comprises a switch tube S3Switch tube S6And a switch tube S7Diode D3And an electrolytic capacitor C3(ii) a The added switch capacitor submodule is a second-stage switch capacitor submodule which comprises a switch tube S23Switch tube S26Switch tube S27Diode D23And an electrolytic capacitor C23；
It will be appreciated that the nine-level space-mode converter operates in a similar manner to the seven-level converter described above (a space-mode DC/AC converter including a switched capacitor sub-module); capacitor C1And C3Charged by a DC power supply at output levels E and 2E, a capacitor C2And C23Charging at output levels 0 and-E.
In addition to the spatial DC/AC converter in embodiment 1, this embodiment further provides a spatial DC/AC conversion system, which includes a controller and a converter, where the converter is the spatial DC/AC converter, and the controller executes the steps of the modulation method for the spatial DC/AC converter when controlling the operation of the switching tubes in the spatial DC/AC converter.
Example 3
On the basis of embodiment 1, this embodiment provides a specific implementation of a fault-tolerant operation method for a spatial DC/AC converter including a switched capacitor submodule; it should be noted that, because the probability of the simultaneous failure of the plurality of switching tubes is small, the fault-tolerant operation method of the space-type DC/AC converter of the present invention is a modulation method after the open-circuit failure of a single switching tube or a single diode occurs.
Specifically, when the space-type DC/AC converter has no open-circuit fault, the space-type DC/AC converter including a switched capacitor submodule is controlled by a driving signal to operate in seven modes, and seven levels are output: 0. e, + -2E and + -3E;
a switching tube S of the basic switch capacitor module1When the converter fails, the drive signal controls the space type DC/AC converter comprising a switched capacitor submodule to work in five modes and output five levels: 0. e and 2E;
a switching tube S of the basic switch capacitor module2Or a switching tube S4Or a switching tube S5When the circuit is in failure, the space type DC/AC converter comprising a switched capacitor submodule is controlled to work in three modes through a driving signal, and three levels are output: 0 and. + -. E;
a switch tube S in the switch capacitor submodule3When the converter fails, the space type DC/AC converter comprising a switched capacitor submodule is controlled to work in five modes through a driving signal, and five levels are output: 0. e and 2E;
a switch tube S in the switch capacitor submodule6Or a switching tube S7When the circuit is in failure, the space type DC/AC converter comprising a switched capacitor submodule is controlled to work in three modes through a driving signal, and three levels are output: 0 and. + -. E;
at the switching tube S of the half-bridge I8Or a switching tube S9When the converter fails, the drive signal controls the space type DC/AC converter comprising a switched capacitor submodule to work in five modes and output five levels: 0. e and 2E;
a switching tube S in the half bridge II10Or a switching tube S11When the converter fails, the drive signal controls the space type DC/AC converter comprising a switched capacitor submodule to work in five modes and output five levels: 0. e and 2E.
Further, a diode D is arranged on the basic switch capacitor module1In the case of failure, the space-type DC/AC converter comprising a switched capacitor submodule is configured into five modes and outputs five levels: 0. e and 2E;
diode D in the basic switch capacitor module2In the case of a fault, the space type DC/AC converter comprising a switched capacitor submodule is configured into three modes and outputs three levels: 0 and. + -. E;
diode D in the switched capacitor submodule3In the case of failure, the space-type DC/AC converter comprising a switched capacitor submodule is configured into five modes and outputs five levels: 0. e and 2E.
It should be noted that, if the switch tube S is opened or closed1、S2Or S3And a diode D1、D2Or D3When open-circuit fault occurs, the corresponding electrolytic capacitor can not be charged.
In particular, in the switching tube S1Or diode D1When an open-circuit fault occurs, the electrolytic capacitor C is connected by changing the control strategy1Isolated from its discharge circuit, switching tube S4And S8And S5And S9Are simultaneously turned on or off, the switching tubes S8And S9And conducting alternately. At this time, the space type DC/AC converter operates as a five-level converter;
in the opening of the pipe switch S2Or diode D2When open-circuit fault occurs, the switch tube S4And S7And a switching tube S5And S6Simultaneously switched on or off, capacitor C1And C3Series discharge is not possible. At this time, the space type DC/AC converter operates as a three-level converter;
at the switch tube S3Or diode D3When open-circuit fault occurs, the space typeThe DC/AC converter operates as a five-level converter;
due to the switch tube S4And S5、S6And S7When any one of the two switching tubes in the complementary state is in open-circuit fault, the other switching tube is kept in a conducting state; at the switch tube S4、S5、S6Or S7When any one of the switching tubes has an open-circuit fault, the space type DC/AC converter operates as a three-level converter;
due to the switch tube S8And S9、S10And S11When any one of the two switching tubes in the complementary state is in open-circuit fault, the other switching tube is kept in a conducting state; at the switch tube S8、S9、S10Or S11When any one of the switching tubes has an open-circuit fault, the space type DC/AC converter operates as a five-level converter.
Based on the above fault-tolerant operation method of the spatial DC/AC converter, this embodiment provides a specific implementation of a fault-tolerant system of the spatial DC/AC converter, where the fault-tolerant system includes a controller and the spatial DC/AC converter, and the controller executes the steps of the fault-tolerant operation method of the spatial DC/AC converter when controlling the operation of the switching tube in the spatial DC/AC converter.
Example 4
After an open-circuit fault occurs to a single switching tube or a single diode in a space-type DC/AC converter including a switched capacitor submodule, the present embodiment provides a specific implementation of a fault-tolerant operation method of the space-type DC/AC converter;
specifically, when an open-circuit fault occurs in a single switching tube or a single diode at different positions, the switching tubes in the same state, the switching tubes kept in conduction, and the corresponding output level number in the switching tubes are as shown in the following table:
Figure DEST_PATH_IMAGE002
。
the present embodiment uses a switch tube S1Or a switching tube S8The fault tolerant operation method of the space type DC/AC converter including a switched capacitor submodule is explained as an example of the open circuit fault.
In one embodiment, the switch tube S of the basic switched capacitor module1After an open-circuit fault occurs, the states of the devices of the spatial DC/AC converter including one switched capacitor submodule at each output level are shown in the following table:
Figure 800254DEST_PATH_IMAGE003
for switches described in the foregoing in the same or complementary relationship, the state of only one of the switches is given, "1" and "0" indicating the on and off states of the switch, respectively; "C", "D" and "—" represent the charge, discharge and idle states of the capacitor, respectively.
As shown in fig. 8 (i) to 8 (v), the switching tube S of the basic switched capacitor module1In the case of a fault, five modes of the space type DC/AC converter comprising a switched capacitor submodule are as follows:
working mode I: switch tube S5Switch tube S7Switch tube S9And a switching tube S11Conducting, turning off the other switch tubes and diode D2Conducting, keeping the rest diodes in an idle state, and outputting a voltage U of 2E;
and working mode II: switch tube S2Switch tube S4Switch tube S7Switch tube S8And a switching tube S11Conducting, turning off the other switch tubes and diode D2Conducting, keeping the rest diodes in an idle state, and outputting a voltage U of E;
and working mode III: switch tube S3Switch tube S5Switch tube S6Switch tube S9And a switching tube S11Conducting, turning off the other switch tubes and turning off the diode D3Conducting, leaving the rest of the diodes in an idle state, and outputting a voltageU is 0;
and working mode IV: switch tube S3Switch tube S5Switch tube S6Switch tube S9And a switching tube S10Conducting, turning off the other switch tubes and diode D3Conducting, keeping the rest diodes in an idle state, and outputting a voltage U of-E;
and (3) working mode V: switch tube S3Switch tube S4Switch tube S6Switch tube S8And a switching tube S10Conducting, turning off the other switch tubes and diode D3And (4) conducting, keeping the rest diodes in an idle state, and outputting a voltage U of-2E.
FIG. 9 shows a switching tube S1The output voltage V of the space type DC/AC converter containing a switched capacitor submodule during fault-tolerant operation after a fault occursoAnd a load current IoThe capacitor C, as the pre-fault state changes to the post-fault state1In an idle state, the switch tube S4And S8And S5And S9While being switched on or off. As can be seen from fig. 9, the space type DC/AC converter rapidly stabilizes in a five-level operation state. Therefore, the open-circuit fault-tolerant operation capability of the space type DC/AC converter is proved.
In the basic switched capacitor module, a diode D is provided1In case of failure, the switch tube S1In an idle state, a space type DC/AC converter comprising a switched capacitor submodule is configured into five modes and outputs five levels; at this time, the state of each device of the space type DC/AC converter under each output level and the switch tube S of the basic switch capacitor module1The failure is the same, so the present embodiment is not described again.
In another embodiment, the switch tube S of the basic switched capacitor module2When the space type DC/AC converter fails, the space type DC/AC converter comprising the switched capacitor submodule is configured into three modes and outputs three levels; the states of the devices of the space type DC/AC converter at the respective output levels are shown in the following table:
Figure DEST_PATH_IMAGE004
it will be appreciated that the switch tube S is a switch tube5And a switching tube S6At each output level, is in the same state, so the switching tube S is according to the table above6Can deduce the state of the switching tube S5The state of (1); due to the switch tube S7And a switching tube S4At each output level, is in the same state, so the switching tube S is according to the table above4Can deduce the state of the switching tube S7The state of (1); due to the switch tube S9And a switching tube S8In complementary states at respective output levels, and hence switching transistor S according to the table above8Can deduce the state of the switching tube S9The state of (1); due to the switch tube S11And a switching tube S10In complementary states at respective output levels, and hence switching transistor S according to the table above10Can deduce the state of the switching tube S11The state of (1).
In another embodiment, the diode D of the basic switched-capacitor module2In case of failure, the switch tube S2In an idle state, a space type DC/AC converter comprising a switched capacitor submodule is configured into three modes and outputs three levels; at this time, the state of each device of the space type DC/AC converter under each output level and the switch tube S of the basic switch capacitor module2The failure is the same, so the present embodiment is not described again.
In another embodiment, the switch tube S of the switched capacitor submodule3In the case of a fault, the space type DC/AC converter comprising a switched capacitor submodule is configured into five modes and outputs five levels; at this time, the states of the devices of the space type DC/AC converter at the respective output levels are shown in the following table:
Figure 173467DEST_PATH_IMAGE005
it can be understood that the switch tube S5And a switching tube S4In complementary states at respective output levels, and hence switching transistor S according to the table above4Can deduce the state of the switching tube S5The state of (1); due to the switch tube S7And a switching tube S10At each output level, is in the same state, so the switching tube S is according to the table above10Can deduce the state of the switching tube S7The state of (1); due to the switch tube S9And a switching tube S8In complementary states at respective output levels, and hence switching transistor S according to the table above8Can deduce the state of the switching tube S9The state of (1); due to the switch tube S11And a switching tube S6At each output level, is in the same state, so the switching tube S is according to the table above6Can deduce the state of the switching tube S11The state of (1).
In another embodiment, the diode D of the switched capacitor submodule3In case of failure, the switch tube S3In an idle state, a space type DC/AC converter comprising a switched capacitor submodule is configured into five modes and outputs five levels; at this time, the state of each device of the space type DC/AC converter under each output level and the switch tube S of the basic switch capacitor module3The failure is the same, so the present embodiment is not described again.
In another embodiment, the switch tube S of the basic switched capacitor module4When the space type DC/AC converter fails, the space type DC/AC converter comprising the switched capacitor submodule is configured into three modes and outputs three levels; the state of each device of the spatial DC/AC converter at each output level at this time is shown in the following table:
Figure DEST_PATH_IMAGE006
it can be understood that the switch tube S5Keeping the conducting state under each output level; due to the switch tube S7And a switching tube S6In complementary states at respective output levels, and hence switching transistor S according to the table above6Can deduce the state of the switching tube S7Shape ofState; due to the switch tube S9And a switching tube S8In complementary states at respective output levels, and hence switching transistor S according to the table above8Can deduce the state of the switching tube S9The state of (1); due to the switch tube S11And a switching tube S10In complementary states at respective output levels, and hence switching transistor S according to the table above10Can deduce the state of the switching tube S11The state of (1).
In another embodiment, the switch tube S of the basic switched capacitor module5When the space type DC/AC converter fails, the space type DC/AC converter comprising the switched capacitor submodule is configured into three modes and outputs three levels; at this time, the states of the devices of the space type DC/AC converter at the respective output levels are shown in the following table:
Figure 663616DEST_PATH_IMAGE007
it can be understood that the switch tube S4Keeping the conducting state under each output level; due to the switch tube S7And a switching tube S6In complementary states at respective output levels, and hence switching transistor S according to the table above6Can deduce the state of the switching tube S7The state of (1); due to the switch tube S9And a switching tube S8In complementary states at respective output levels, and hence switching transistor S according to the table above8Can deduce the state of the switching tube S9The state of (1); due to the switch tube S11And a switching tube S10In complementary states at respective output levels, and hence switching transistor S according to the table above10Can deduce the state of the switching tube S11The state of (1).
In another embodiment, the switch tube S of the switched capacitor submodule6When the space type DC/AC converter fails, the space type DC/AC converter comprising the switched capacitor submodule is configured into three modes and outputs three levels; the state of each device of the spatial DC/AC converter at each output level at this time is shown in the following table:
Figure DEST_PATH_IMAGE008
it can be understood that the switch tube S5And a switching tube S4In complementary states at respective output levels, and hence switching transistor S according to the table above4Can deduce the state of the switching tube S5The state of (1); switch tube S7Keeping the conducting state under each output level; due to the switch tube S9And a switching tube S8In complementary states at respective output levels, and hence switching transistor S according to the table above8Can deduce the state of the switching tube S9The state of (1); due to the switching tube S11And a switching tube S10In complementary states at respective output levels, and hence switching transistor S according to the table above10Can deduce the state of the switching tube S11The state of (1).
In another embodiment, the switch tube S of the switched capacitor submodule7When the space type DC/AC converter fails, the space type DC/AC converter comprising the switched capacitor submodule is configured into three modes and outputs three levels; at this time, the states of the devices of the space type DC/AC converter at the respective output levels are shown in the following table:
Figure 71464DEST_PATH_IMAGE009
it can be understood that the switch tube S5And a switching tube S4In complementary states at respective output levels, and hence switching transistor S according to the table above4Can deduce the state of the switching tube S5The state of (1); switch tube S6Keeping the conducting state under each output level; due to the switch tube S9And a switching tube S8In complementary states at respective output levels, and hence switching transistor S according to the table above8Can deduce the state of the switching tube S9The state of (1); due to the switch tube S11And a switching tube S10In complementary states at respective output levels, and hence switching transistor S according to the table above10Can deduce the state of the switching tube S11Shape ofState.
In another embodiment, the switching tube S of the half-bridge I8When open-circuit fault occurs, the switch tube S9Keeping the conducting state, normally charging three electrolytic capacitors, and discharging at most two electrolytic capacitors in series during the period of the maximum output level; at the moment, the space type DC/AC converter comprising the switched capacitor submodule is configured into five modes and outputs five levels; the states of the devices of the space type DC/AC converter at the respective output levels are shown in the following table:
Figure DEST_PATH_IMAGE010
as shown in FIGS. 10 (i) to 10 (v), the switching tube S of the half bridge I8In the case of a fault, five modes of the space type DC/AC converter comprising a switched capacitor submodule are as follows:
working mode i: switch tube S1Switch tube S5Switch tube S7Switch tube S9And a switching tube S11Conducting, turning off the other switch tubes and diode D1Conducting, keeping the rest diodes in an idle state, and outputting a voltage U of 2E;
working mode ii: switch tube S1Switch tube S5Switch tube S7Switch tube S9And a switching tube S10Conducting, turning off the other switch tubes and diode D1Conducting, keeping the rest diodes in an idle state, and outputting a voltage U of E;
working mode iii: switch tube S2Switch tube S4Switch tube S7Switch tube S9And a switching tube S11Conducting, turning off the other switch tubes and diode D2Conducting, keeping the rest diodes in an idle state, and keeping the output voltage U at 0;
working mode iv: switch tube S3And a switch tube S5Switch tube S6And a switch tube S9And a switching tube S10Conducting, turning off the other switch tubes and turning off the diode D3Conducting, leaving the rest of the diodes in idle state, and outputtingThe voltage U is-E;
working mode v: switch tube S3Switch tube S4Switch tube S6Switch tube S9And a switching tube S11Conducting, turning off the other switch tubes and diode D3And (4) conducting, keeping the rest diodes in an idle state, and outputting a voltage U of-2E.
In another embodiment, the switching tube S of the half-bridge I9In the case of a fault, the space type DC/AC converter comprising a switched capacitor submodule is configured into five modes and outputs five levels; at this time, the states of the devices of the space type DC/AC converter at the respective output levels are shown in the following table:
Figure 988867DEST_PATH_IMAGE011
it can be understood that the switch tube S5And a switching tube S4In complementary states at respective output levels, and hence switching transistor S according to the table above4Can deduce the state of the switching tube S5The state of (1); due to the switch tube S7And a switching tube S6In complementary states at respective output levels, and hence switching transistor S according to the table above6Can deduce the state of the switching tube S7The state of (1); switch tube S8Keeping the conducting state under each output level; due to the switch tube S11And a switching tube S10In complementary states at respective output levels, and hence switching transistor S according to the table above10Can deduce the state of the switching tube S11The state of (1).
In another embodiment, the switching tube S of the half bridge ii10In the case of a fault, the space type DC/AC converter comprising a switched capacitor submodule is configured into five modes and outputs five levels; at this time, the states of the devices of the space type DC/AC converter at the respective output levels are shown in the following table:
Figure DEST_PATH_IMAGE012
。
it will be appreciated that the switch tube S is a switch tube5And a switching tube S4In complementary states at respective output levels, and hence switching transistor S according to the table above4Can deduce the state of the switching tube S5The state of (1); due to the switch tube S7And a switching tube S6In complementary states at respective output levels, and hence switching transistor S according to the table above6Can deduce the state of the switching tube S7The state of (1); due to the switch tube S9And a switching tube S8In complementary states at respective output levels, and hence according to the switching tube S8Can deduce the state of the switching tube S9The state of (1); switch tube S11The on state is maintained at each output level.
In another embodiment, the switching tube S of the half bridge ii11In the case of a fault, the space type DC/AC converter comprising a switched capacitor submodule is configured into five modes and outputs five levels; the state of each device of the spatial DC/AC converter at each output level at this time is shown in the following table:
Figure 583796DEST_PATH_IMAGE013
it can be understood that the switch tube S5And a switching tube S4In complementary states at respective output levels, and hence switching transistor S according to the table above4Can deduce the state of the switching tube S5The state of (1); due to the switch tube S7And a switching tube S6In complementary states at respective output levels, and hence switching transistor S according to the table above6Can deduce the state of the switching tube S7The state of (1); due to the switch tube S9And a switching tube S8In complementary states at respective output levels, and hence according to the switching tube S8Can deduce the state of the switching tube S9The state of (1); switch tube S10The on state is maintained at each output level.
Example 5
It should be noted that, at N ≧ 2, the open-circuit fault-tolerant strategy of the space-type DC/AC converter is similar to that described in embodiments 3 and 4, and its characteristics are explained below.
When the open-circuit fault occurs to the switch tube in the charging loop, the corresponding electrolytic capacitor does not work any more, and when the redundant state is configured, the switch tube connected with the anode of the electrolytic capacitor in the charging state needs to be ensured to be in the off state. Switching tube S connected with load side half bridge I8Connected switching tube S1When open-circuit fault occurs, the switch tube S8And S4(switching tube S9And S5) The states of the two are kept consistent; switching tube S connected to load side half bridge II10Connected switching tube Si3When open-circuit fault occurs, the switch tube S10And Si7(switching tube S11And Si6) The states of the two are kept consistent; in both cases, the number of output levels of the spatial DC/AC converter is 2N + 3.
In addition, in the switch tube S1When an open circuit fault occurs, no capacitor is charged in the state of an output level of 2N + 3. When the open circuit fault occurs to the switching tube in the charging circuit which is not connected with the load side switching tube, the two switching tubes connected with the anode (cathode) of the corresponding electrolytic capacitor are in the same state, and the output level number of the space type DC/AC converter is 2N + 1.
When the switch tube in the discharge loop has an open-circuit fault, the switch tube in the complementary state is kept conducted under the normal working state. When the load side switching tube has an open-circuit fault, the number of output levels of the space type DC/AC converter is 2N + 3; and when the non-load side switch tube has an open-circuit fault, the number of output levels of the space type DC/AC converter is 2N + 1.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention and not to limit it; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art will understand that: modifications to the specific embodiments of the invention or equivalent substitutions for parts of the technical features may be made; without departing from the spirit of the present invention, it is intended to cover all aspects of the invention as defined by the appended claims.

Claims (9)

1. A space-mode DC/AC converter, characterized by: the circuit comprises a direct-current power supply E, a basic switched capacitor module, N switched capacitor sub-modules, a half bridge I and a half bridge II, wherein the basic switched capacitor module comprises a switching tube S1Switch tube S2Switch tube S4Switch tube S5Diode D1Diode D2And an electrolytic capacitor C1And an electrolytic capacitor C2The half bridge I comprises a switching tube S8And a switching tube S9The half bridge II comprises a switching tube S10And a switching tube S11；
When N =1, the switched capacitor submodule comprises a switching tube S3Switch tube S6And a switch tube S7Diode D3And an electrolytic capacitor C3；
Switch tube S of basic switch capacitor module1Respectively with the switching tube S2Input terminal of the switched capacitor submodule and a switching tube S of the switched capacitor submodule3The input end of the switch tube S is connected with the positive pole of the direct current power supply E1Respectively with the switching tube S4And the electrolytic capacitor C1Is connected to the anode of the switching tube S2Respectively with the switching tube S5Input terminal of the switched capacitor submodule and a switching tube S of the switched capacitor submodule6Input terminal and electrolytic capacitor C2The anode of (2) is connected; the switch tube S4The output ends of the two capacitors are respectively connected with a switch tube S of the switch capacitor submodule7Of the diode D2And the electrolytic capacitor C2Is connected to the cathode of the switching tube S5Respectively with said diode D1And the electrolytic capacitor C1The cathode of (a) is connected;
switch tube S of switch capacitor submodule3Respectively with the switching tube S7And the electrolytic capacitor C3Is connected to the anode of the switching tube S6Respectively with said diode D3Input terminal ofAnd an electrolytic capacitor C3The cathode of (a) is connected;
the negative electrode of the direct current power supply E is respectively connected with the diode D of the basic switch capacitor module1And diode D2And the diode D of the switched capacitor submodule3The output ends of the two-way valve are connected;
switching tube S of half-bridge I8And the electrolytic capacitor C of the basic switch capacitor module1Is connected to the anode of the switching tube S8And the output end of the switch tube S9Is connected with the input end of the switch tube S9And the electrolytic capacitor C of the basic switch capacitor module1The cathode of (a) is connected; switching tube S of half bridge II10And the electrolytic capacitor C of the switch capacitor submodule3Is connected to the anode of the switching tube S10And the output end of the switch tube S11Is connected with the input end of the switch tube S11And the output end of the switch capacitor submodule and the electrolytic capacitor C of the switch capacitor submodule3The cathode of (a) is connected;
when N is more than or equal to 2, the ith switch capacitor submodule comprises an electrolytic capacitor Ci3Diode Di3Switch tube Si3Switch tube Si6And a switching tube Si7，2≤i≤N；
Electrolytic capacitor C of ith switch capacitor submodulei3Electrolytic capacitor C of i-1 th switch capacitor submodule(i-1)3Through a switching tube Si6And a switching tube Si7Cross-connecting; electrolytic capacitor C of ith switch capacitor submodulei3The anode of (2) and a switch tube Si3Is connected with the output end of the switch tube Si3Respectively connected with the positive electrode of the DC power supply E and the switching tube S of the basic switch capacitor module1Input terminal of, the switching tube S2Input terminal of and switching tube S(i-1)3The input ends of the two-way valve are connected; electrolytic capacitor C of ith switch capacitor submodulei3And a diode Di3Is connected to the input terminal of a diode Di3Respectively connected with the negative pole of the DC power supply E and the diode D(i-1)3Output terminal of the basic switched capacitor module, diode D1And diode D2The output ends of the two-way valve are connected;
electrolytic capacitor C of Nth switch capacitor submoduleN3With the switching tube S of the half-bridge II10Is connected to the input terminal of an electrolytic capacitor CN3And the switching tube S of the half bridge II11Is connected with the output end of the power supply.
2. The spatial type DC/AC converter according to claim 1, wherein: switch tube S of basic switch capacitor module4And a switching tube S5A switch tube S of the switch capacitor submodulei6And a switching tube Si7And switching tube S of half-bridge I and half-bridge II8Switch tube S9Switch tube S10Switch tube S11For the switching tube including the backward diode, the switching tube S of the basic switched capacitor module1And a switching tube S2And a switch tube S of the switch capacitor submodulei3Is a switch tube without a reverse diode.
3. A modulation method of a space type DC/AC converter is characterized in that:
controlling the spatial DC/AC converter of claim 1 or 2 to operate in 2N +5 modes by the driving signal, and outputting 2N +5 levels: 0. + -E, + -2E, … …, + - (N + 2) E; wherein N represents the number of switched capacitor sub-modules.
4. The modulation method of the spatial type DC/AC converter according to claim 3, wherein: at N =1, by comparing the sine-modulated wave UrefAnd six triangular carriers ua1To ua6Obtaining a logic signal u1To u6Logic signal u1To u6After logical combination, the driving signals of all the switching tubes are obtained through output, and the expression of the driving signals of all the switching tubes is as follows:
Figure 692501DEST_PATH_IMAGE001
。
5. a method of fault tolerant operation of a space based DC/AC converter according to claim 1 or 2, characterized in that:
a switching tube S of the basic switch capacitor module1When the converter fails, the drive signal controls the space type DC/AC converter comprising a switched capacitor submodule to work in five modes and output five levels: 0. e and 2E;
a switching tube S of the basic switch capacitor module2Or a switching tube S4Or a switching tube S5When the circuit is in failure, the space type DC/AC converter comprising a switched capacitor submodule is controlled to work in three modes through a driving signal, and three levels are output: 0 and. + -. E;
a switch tube S in the switch capacitor submodule3When the converter fails, the drive signal controls the space type DC/AC converter comprising a switched capacitor submodule to work in five modes and output five levels: 0. e and 2E;
a switch tube S in the switch capacitor submodule6Or a switching tube S7When the circuit is in failure, the space type DC/AC converter comprising a switched capacitor submodule is controlled to work in three modes through a driving signal, and three levels are output: 0 and. + -. E;
at the switching tube S of the half-bridge I8Or a switching tube S9When the converter fails, the drive signal controls the space type DC/AC converter comprising a switched capacitor submodule to work in five modes and output five levels: 0. e and 2E;
a switching tube S in the half bridge II10Or a switching tube S11When the converter fails, the drive signal controls the space type DC/AC converter comprising a switched capacitor submodule to work in five modes and output five levels: 0. e and 2E.
6. The method of claim 5, wherein the method further comprises: on the basis ofDiode D of switch capacitor module1In the case of failure, the space-type DC/AC converter comprising a switched capacitor submodule is configured into five modes and outputs five levels: 0. e and 2E;
diode D in the basic switch capacitor module2In the case of a fault, the space type DC/AC converter comprising a switched capacitor submodule is configured into three modes and outputs three levels: 0 and. + -. E;
diode D in the switched capacitor submodule3In the case of failure, the space-type DC/AC converter comprising a switched capacitor submodule is configured into five modes and outputs five levels: 0. e and 2E.
7. A space-based DC/AC conversion system comprising a controller and a converter, characterized in that: the converter is a space type DC/AC converter as claimed in claim 1 or 2.
8. The spatial type DC/AC conversion system according to claim 7, wherein: the method of claim 3 or 4, when the controller controls the switching tube of the space-type DC/AC converter to operate.
9. A fault tolerant system of a space type DC/AC converter includes a controller and the space type DC/AC converter, and is characterized in that: the method of claim 5 or 6, when the controller controls the switching tube of the space-type DC/AC converter to operate, for fault-tolerant operation of the space-type DC/AC converter.
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