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

Abstract

The invention provides a space-type DC/AC converter and a fault-tolerant operation method thereof. The space-type DC/AC converter includes a DC power supply E, a basic switched capacitor module, N switched capacitor sub-modules, a half bridge I and a half-bridge Bridge II; the electrolytic capacitor C _i3 of the i-th switched capacitor sub-module and the electrolytic capacitor C _(i-1)3 of the i-1-th switched capacitor sub-module are cross-connected through the switch S _i6 and the switch S _i7 . Through the driving signal, the above-mentioned spatial DC/AC converter is controlled to work in 2N+5 modes, and output 2N+5 levels: 0, ±E, ±2E, ..., ±(N+2)E; Among them, N represents the number of switched capacitor sub-modules. The present invention can be extended by adding capacitors and switching devices, and by separating the charging loop and the discharging loop, the spatial DC/AC converter can withstand open circuit faults.

Description

A space-type DC/AC converter and its fault-tolerant operation method

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 technique

Multilevel converters have been widely used in renewable energy power generation systems (especially photovoltaic power generation systems), power distribution systems, electric vehicles and other fields. The main advantages of these systems include step voltages for lower total harmonic distortion, low EMI, and lower voltage stress on the switches.

As with traditional multilevel converters, studies on neutral point clamped (NPC), flying capacitor (FC) and cascaded H bridge (CHB) multilevel converters have been well established. However, neutral-point clamp and flying capacitor multilevel converters require a large number of diodes or capacitors, and implementing capacitor voltage self-balancing or additional charging circuits will increase their complexity and cost. CHB multilevel converters use multiple isolated sources to boost output levels. In addition, the low voltage gain (the ratio of the maximum output voltage to the input voltage) and the single expansion method limit the development of traditional multilevel converters. To solve these problems, new multilevel converters based on switched capacitor technology have been proposed and developed rapidly.

The capacitor of a switched capacitor multilevel converter (SCMLI) is charged in parallel with the DC supply and discharged in series for high voltage gain. In addition, compared with traditional multilevel converters, SCMLI outputs the same level with fewer devices, and has the advantages of capacitor voltage self-balancing 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, due to the use of a large number of switches and capacitors, low reliability is one of the main problems of multi-level converters.

Fault-tolerant technology is considered to be an effective way to improve the reliability of converters. In recent years, the fault-tolerant operation of multi-level converters has received extensive attention, mainly including two ways:

(1) It is realized by adding redundant branches in the converter. The purpose of configuring redundant branches is to isolate the faulty branch when a fault occurs, and replace the faulty branch with the redundant branch. This solution maintains the continuity of the output level, but increases the number of components, converter cost and control complexity;

(2) The control solution without additional components is not realized by directly changing the control strategy of the converter. The inherent defect of this solution is that the output level decreases after a fault, which limits its application.

In order to solve the above problems, people have been looking for an ideal technical solution.

SUMMARY OF THE INVENTION

The purpose of the present invention is to aim at the deficiencies of the prior art, so as to provide a space-type DC/AC converter and a fault-tolerant operation method thereof.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A first aspect of the present invention provides a space-type DC/AC converter, which includes a DC power supply E, a basic switched capacitor module, N switched capacitor sub-modules, a half bridge I and a half bridge II, and the basic switched capacitor module includes a switch tube S ₁ , switch tube S ₂ , switch tube S ₄ , switch tube S ₅ , diode D ₁ , diode D ₂ , electrolytic capacitor C ₁ and electrolytic capacitor C ₂ , the half-bridge I includes switch tube S ₈ and switch tube S ₉ , the half-bridge II includes a switch tube S ₁₀ and a switch tube S ₁₁ ;

When N=1, the switched capacitor sub-module includes a switch S ₃ , a switch S ₆ , a switch S ₇ , a diode D ₃ and an electrolytic capacitor C ₃ ;

The input end of the switch tube S1 _of the basic switched capacitor module is respectively connected to the input end of the switch tube S2, the input end of the switch tube S3 _of the switched capacitor sub _- module and the positive pole of the DC power supply E, respectively, _The output end of the switch tube S1 is respectively connected with the input end of the switch tube _S4 and the anode of the electrolytic capacitor _C1 , and the output end of the switch tube S2 is respectively connected with the input end of the switch tube _{S5 .} terminal, the input terminal of the switch tube _S6 of the switched capacitor sub _- module is connected to the anode of the electrolytic capacitor C2 _; the output terminal of the switch tube S4 is respectively connected with the output terminal of the switch tube S7 of the switched capacitor sub _- module , the input end of the diode D ₂ is connected to the cathode of the electrolytic capacitor C ₂ , and the output end of the switch tube S ₅ is respectively connected to the input end of the diode D ₁ and the cathode of the electrolytic capacitor C ₁ ;

The output end of the switch tube S3 _of the switched capacitor sub _- module is respectively connected to the input end of the switch tube S7 and the anode _of the electrolytic capacitor C3, and the output end of the switch tube _S6 is respectively connected to the diode. The input terminal of D ₃ is connected to the cathode of electrolytic capacitor C ₃ ;

The negative pole of the DC power supply E is respectively connected with the output terminal of the diode D1 and the output terminal of the diode D2 _of the basic switched capacitor module, and the output terminal of the diode _D3 of the switched capacitor sub _- module;

The input end of the switch tube _S8 of the half-bridge I is connected to the anode of the electrolytic capacitor _C1 of the basic switched capacitor module, the output end of the switch tube _S8 is connected to the input end of the switch tube _S9 , The output terminal of the switch tube _S9 is connected to the cathode of the electrolytic capacitor _C1 of the basic switched capacitor module; the input terminal of the switch tube _S10 of the half-bridge II is connected to the electrolytic capacitor C3 _of the switched capacitor sub-module. The anode of the switch tube _S10 is connected to the input end of the switch tube _S11 , and the output end of the switch tube _S11 is connected to the cathode of the electrolytic capacitor C3 _of the switched capacitor sub-module;

When N≥2, the ith switched capacitor sub-module includes an electrolytic capacitor C _i3 , a diode D _i3 , a switch S _i3 , a switch S _i6 and a switch S _i7 , 2≤i≤N;

The electrolytic capacitor C _i3 of the i-th switched capacitor sub-module and the electrolytic capacitor C _(i-1)3 of the i-1-th switched capacitor sub-module are cross-connected through the switch tube S _i6 and the switch tube S _i7 ; the i-th switch The anode of the electrolytic capacitor C _i3 of the capacitor sub-module is also connected to the output end of the switch tube S _i3 , and the input end of the switch tube S _i3 is respectively connected to the positive pole of the DC power supply E and the switch tube S ₁ of the basic switched capacitor module. The input end, the input end of the switch tube S ₂ and the input end of the switch tube S _{(i-1) 3} are connected; the cathode of the electrolytic capacitor C _i3 of the i-th switched capacitor sub-module is also connected with the input end of the diode D _i3 , the output end of the diode D _i3 is respectively connected with the cathode of the DC power supply E, the output end of the diode D _{(i-1) 3} , the output end of the diode D ₁ and the output end of the diode D ₂ of the basic switched capacitor module ;

The anode of the electrolytic capacitor C _N3 of the Nth switched capacitor sub-module is connected to the input end of the switch _S10 of the half bridge II, and the cathode of the electrolytic capacitor C _N3 is connected to the output end of the switch _S11 of the half bridge II connect.

A second aspect of the present invention provides a modulation method for a spatial DC/AC converter. The spatial DC/AC converter according to claim 1 or 2 is controlled to work in 2N+5 modes through a driving signal, and outputs 2N +5 levels: 0, ±E, ±2E, ..., ±(N+2)E; where N represents the number of switched capacitor sub-modules.

A third aspect of the present invention provides a fault-tolerant operation method for a spatial DC/AC converter,

When no open-circuit fault occurs in the space-type DC/AC converter, the space-type DC/AC converter including a switched capacitor sub-module is controlled to work in seven modes through the drive signal, and output seven levels: 0, ± E, ±2E and ±3E;

When the switch tube S1 _of the basic switched capacitor module fails, the spatial DC/AC converter including one switched capacitor sub-module is controlled to work in five modes through the drive signal, and output five levels: 0, ±E and ±2E;

When the switch tube S2 or the switch tube _S4 or the switch tube _S5 of the basic switched capacitor module fails, the spatial DC/AC converter including a switched capacitor sub _- module is controlled to work in three modes through the drive signal, Output three levels: 0 and ±E;

When the switch tube S3 of the switched capacitor sub _- module fails, the spatial DC/AC converter including one switched capacitor sub-module is controlled to work in five modes through the drive signal, and outputs five levels: 0, ±E and ±2E;

When the switch tube _S6 or the switch tube S7 of the switched capacitor sub _- module fails, the spatial DC/AC converter including one switched capacitor sub-module is controlled to work in three modes through the drive signal, and outputs three levels : 0 and ±E;

When the switch tube _S8 or the switch tube _S9 of the half-bridge I fails, the space-type DC/AC converter including a switched capacitor sub-module is controlled to work in five modes through the drive signal, and output five levels: 0, ±E and ±2E;

When the switching tube _S10 or the switching tube _S11 of the half-bridge II fails, the space-type DC/AC converter including a switched capacitor sub-module is controlled to work in five modes through the drive signal, and output five levels: 0, ±E and ±2E.

A fourth aspect of the present invention provides a spatial DC/AC conversion system, including a controller and a converter, wherein the converter is the above-mentioned spatial DC/AC converter.

A fifth aspect of the present invention provides a fault-tolerant system for a space-type DC/AC converter, including a controller and a space-type DC/AC converter, wherein the controller controls the operation of switches in the space-type DC/AC converter When , the steps of the above-mentioned fault-tolerant operation method of the space-type DC/AC converter are performed.

The beneficial effects of the present invention are:

1) The present invention proposes a space-type DC/AC converter. The space-type DC/AC converter including a switched capacitor sub-module uses 1 DC power supply, 3 capacitors and 11 switching devices to achieve 3 times the voltage gain and 7 times the voltage gain. Level AC voltage output; by separating the charging circuit and the discharging circuit, the topology can realize fault-tolerant operation and improve the reliability of the converter;

Use two "half bridges" instead of H bridges to switch the polarity of the output level and reduce the voltage stress _of the switches; among them, the maximum voltage stress _of the switches S1 and S3 is 2E, and the maximum voltage of the other switches The stress is E;

2) The spatial DC/AC converter uses only one DC power supply, and the output level is increased by adding switched capacitor sub-modules, which can simplify the structure of the converter to the greatest extent; each switched capacitor sub-module includes three A switch tube, a diode and an electrolytic capacitor, in the modular expansion structure, each additional switch capacitor sub-module will increase the output level of the spatial DC/AC converter by 2;

3) The space-type DC/AC converter proposed in the present invention has the advantage of low voltage ripple, and at least one capacitor is charged at any level;

4) The capacitor is independently charged by the DC power supply, so the fault capacitor in the space-type DC/AC converter can be isolated by changing the control strategy;

5) When the switch tube S ₁ or diode D ₁ has an open circuit fault, the electrolytic capacitor C ₁ is isolated from its discharge circuit by changing the control strategy, the switch tubes S ₄ and S ₈ and S ₅ and S ₉ are turned on or off at the same time. _S8 and _S9 are turned on alternately. At this time, the space-type DC/AC converter including a switched capacitor sub-module works as a five-level converter;

When the switch S2 or the diode D2 has an open _- circuit fault, the switches S4 and _S7 and the switches _S5 and _{S6 are} turned _on or off at the same time, and the capacitors _C1 and _C3 cannot be discharged in series. At this time, the space-type DC/AC converter including a switched capacitor sub-module operates as a three-level converter;

When the switch tube S3 or the diode _D3 has an open _- circuit fault, the space-type DC/AC converter including a switched capacitor sub-module operates as a five-level converter;

Because the switches S ₄ and S ₅ , S ₆ and S ₇ work in the complementary state, when one of the two switch tubes working in the complementary state has an open-circuit fault, the other switch remains in a conducting state; When any one of the switch tubes S ₄ , S ₅ , S ₆ or S ₇ has an open-circuit fault, the space-type DC/AC converter including a switched capacitor sub-module operates as a three-level converter;

Since the switches _S8 and _S9 , _S10 and _S11 work in the complementary state, when one of the two switches has an open-circuit fault, the other switch remains on; when the switches _S8 , _S9 When any switch tube in _S10 or _S11 has an open-circuit fault, the space-type DC/AC converter including a switched capacitor sub-module operates as a five-level converter;

6) In the operating state before and after the fault, the voltage balance of the capacitor, the boosting ability and the ability to carry an inductive load can be maintained; in the operating state after the fault, the voltage stress of the switching device and the voltage ripple of the capacitor are reduced or maintained. Change;

7) If a fast fuse or circuit breaker is used to isolate the short-circuit switch tube, this space-type DC/AC converter can be used for short-circuit fault tolerance;

8) The fault-tolerant operation method of the present invention is especially suitable for an extended converter with a high output level, and the fault-tolerant operation method reduces at most four output levels, and is especially suitable for an extendable converter.

Description of drawings

Fig. 1 is the topological structure diagram of the space type DC/AC converter of the present invention;

2(a) to 2(g) are circuit schematic diagrams of seven operating modes of the space-type DC/AC converter (in normal operation) including a switched capacitor sub-module of the present invention;

3 is a schematic diagram of a carrier wave and a modulation waveform of a spatial DC/AC converter comprising a switched capacitor sub-module of the present invention;

4 is a schematic diagram of the original PWM pulse waveform of the spatial DC/AC converter comprising a switched capacitor sub-module of the present invention;

5 is a control signal waveform of each switch tube of the spatial DC/AC converter comprising a switched capacitor sub-module of the present invention;

6 is a schematic diagram of a target output waveform of a spatial DC/AC converter comprising a switched capacitor sub-module of the present invention;

7 is a schematic diagram of an output voltage waveform and a schematic diagram of an output current waveform during a band-resistance inductive load of the space-type DC/AC converter comprising a switched capacitor sub-module of the present invention;

8(I) to 8(V) are circuit schematic diagrams of five operating modes when the switch tube S1 _of the spatial DC/AC converter including a switched capacitor sub-module of the present invention fails;

9 is _a schematic diagram of the output waveform of the fault-tolerant operation of the space-type DC/AC converter including a switched capacitor sub-module after the switch tube S1 fails;

Figures 10(i) to 10(v) are circuit schematic diagrams of five operating modes when the switch tube _S8 of the spatial DC/AC converter including a switched capacitor sub-module of the present invention fails;

FIG. 11 is a topological structure diagram of the expanded spatial DC/AC converter of the present invention.

Detailed ways

The technical solutions of the present invention will be further described in detail below through specific embodiments.

Example 1

1 shows a schematic diagram of the topology structure of a space-type DC/AC converter. The space-type DC/AC converter includes a DC power supply E, a basic switched capacitor module, N switched capacitor sub-modules, a half bridge I and Half-bridge II, the basic switched capacitor module includes a switch S ₁ , a switch S ₂ , a switch S ₄ , a switch S ₅ , a diode D ₁ , a diode D ₂ , an electrolytic capacitor C ₁ and an electrolytic capacitor C ₂ , so The half-bridge I includes a switch _S8 and a switch _S9 , and the half-bridge II includes a switch _S10 and a switch _S11 ;

When N=1, the switched capacitor sub-module includes a switch S ₃ , a switch S ₆ , a switch S ₇ , a diode D ₃ and an electrolytic capacitor C ₃ ;

The input end of the switch tube S1 _of the basic switched capacitor module is respectively connected to the input end of the switch tube S2, the input end of the switch tube S3 _of the switched capacitor sub _- module and the positive pole of the DC power supply E, respectively, _The output end of the switch tube S1 is respectively connected with the input end of the switch tube _S4 and the anode of the electrolytic capacitor _C1 , and the output end of the switch tube S2 is respectively connected with the input end of the switch tube _{S5 .} terminal, the input terminal of the switch tube _S6 of the switched capacitor sub _- module is connected to the anode of the electrolytic capacitor C2 _; the output terminal of the switch tube S4 is respectively connected with the output terminal of the switch tube S7 of the switched capacitor sub _- module , the input end of the diode D ₂ is connected to the cathode of the electrolytic capacitor C ₂ , and the output end of the switch tube S ₅ is respectively connected to the input end of the diode D ₁ and the cathode of the electrolytic capacitor C ₁ ;

The output end of the switch tube S3 _of the switched capacitor sub _- module is respectively connected to the input end of the switch tube S7 and the anode _of the electrolytic capacitor C3, and the output end of the switch tube _S6 is respectively connected to the diode. The input terminal of D ₃ is connected to the cathode of electrolytic capacitor C ₃ ;

The negative pole of the DC power supply E is respectively connected with the output terminal of the diode D1 and the output terminal of the diode D2 _of the basic switched capacitor module, and the output terminal of the diode _D3 of the switched capacitor sub _- module;

The input end of the switch tube _S8 of the half-bridge I is connected to the anode of the electrolytic capacitor _C1 of the basic switched capacitor module, the output end of the switch tube _S8 is connected to the input end of the switch tube _S9 , The output terminal of the switch tube _S9 is connected to the cathode of the electrolytic capacitor _C1 of the basic switched capacitor module; the input terminal of the switch tube _S10 of the half-bridge II is connected to the electrolytic capacitor C3 _of the switched capacitor sub-module. The anode of the switch tube _S10 is connected to the input end of the switch tube _S11 , and the output end of the switch tube _S11 is connected to the cathode of the electrolytic capacitor C3 _of the switched capacitor sub-module;

When N≥2, the ith switched capacitor sub-module includes an electrolytic capacitor C _i3 , a diode D _i3 , a switch S _i3 , a switch S _i6 and a switch S _i7 , 2≤i≤N;

The electrolytic capacitor C _i3 of the i-th switched capacitor sub-module and the electrolytic capacitor C _(i-1)3 of the i-1-th switched capacitor sub-module are cross-connected through the switch tube S _i6 and the switch tube S _i7 ; the i-th switch The anode of the electrolytic capacitor C _i3 of the capacitor sub-module is also connected to the output end of the switch tube S _i3 , and the input end of the switch tube S _i3 is respectively connected to the positive pole of the DC power supply E and the switch tube S ₁ of the basic switched capacitor module. The input end, the input end of the switch tube S ₂ and the input end of the switch tube S _{(i-1) 3} are connected; the cathode of the electrolytic capacitor C _i3 of the i-th switched capacitor sub-module is also connected with the input end of the diode D _i3 , the output end of the diode D _i3 is respectively connected with the cathode of the DC power supply E, the output end of the diode D _{(i-1) 3} , the output end of the diode D ₁ and the output end of the diode D ₂ of the basic switched capacitor module ;

The anode of the electrolytic capacitor C _N3 of the Nth switched capacitor sub-module is connected to the input end of the switch _S10 of the half bridge II, and the cathode of the electrolytic capacitor C _N3 is connected to the output end of the switch _S11 of the half bridge II connect.

Among them, the electrolytic capacitor C _i3 of the ith switched capacitor sub-module and the electrolytic capacitor C _(i-1)3 of the i-1st switched capacitor sub-module are cross-connected through the switch S _i6 and the switch S _i7 , referring to Yes: the input end of the switch tube S _i6 is respectively connected with the input end of the switch tube S _{(i-1) 7} , the output end of the switch tube S _{(i-1) 3} and the anode of the electrolytic capacitor C _{(i-1) 3} The output end of switch tube S _i6 is respectively connected with the input end of diode D _i3 and the cathode of electrolytic capacitor C _i3 ; the input end of switch tube S _i7 is respectively connected with the output end of switch tube S _i3 and the anode of electrolytic capacitor C _i3 . Connection; the output end of the switch tube S _i7 is respectively connected with the input end of the diode D _(i-1)3 , the output end of the switch tube S _(i-1)6 and the cathode of the electrolytic capacitor C _(i-1)3 .

It can be understood that the electrolytic capacitor _C2 of the basic switched capacitor module of the spatial DC/AC converter and the electrolytic capacitor C3 of the first switched capacitor sub _- module are cross _- connected through the switch _S6 and the switch S7.

Specifically, the switch transistors S ₄ and S ₅ of the basic switched capacitor module, the switch transistors S _i6 and S i7 of the switched capacitor sub-module, and the switch transistors S ₈ and S _i7 of the half-bridge I and the half-bridge II The switch transistor S ₉ , the switch transistor S ₁₀ , and the switch transistor S ₁₁ are switch transistors including reverse diodes, the switch transistors S ₁ and S ₂ of the basic switched capacitor module and the switch transistor S of the switched capacitor sub-module _i3 is a switch tube that does not contain a reverse diode. It can be understood that the space type DC/AC converter uses MOSFETs or IGBTs with anti-parallel diodes to provide a channel for feeding back reactive energy from the AC output side to the DC input side; therefore, the space type DC/AC The converter is capable of carrying inductive loads.

It should be noted that the space-type DC/AC converter can be expanded by increasing the number of switched capacitor sub-modules. The DC power supply E separately charges all the switched capacitor sub-modules, and each switched capacitor sub-module is discharged in series to increase the output power. flat. In the modular expansion structure, each additional switched capacitor sub-module will increase the output level of the spatial DC/AC converter by 2; this expansion method can not only maintain the advantages of the cascade expansion method, but also only requires a DC power supply.

It can be understood that each switched capacitor sub-module of the spatial DC/AC converter includes three switch tubes, a diode and an electrolytic capacitor. According to the positional relationship between the switched capacitor sub-module and the basic switched capacitor module, the Two adjacent switched capacitor sub-modules are set as a front-stage switched capacitor sub-module and a rear-stage switched capacitor sub-module;

The electrolytic capacitor of the rear-stage switched capacitor sub-module and the electrolytic capacitor of the preceding-stage switched capacitor sub-module are cross-connected through two of the switch tubes of the rear-stage switched capacitor sub-module, and the anode of the electrolytic capacitor of the rear-stage switched capacitor sub-module is also connected to the anode. The output end of another switch tube of the rear-stage switched capacitor sub-module is connected, and the input end of the other switch tube of the rear-stage switched capacitor sub-module is respectively connected to the positive pole of the DC power supply E and the switch tube S of the basic switched capacitor module. _The input end of ₁ , the input end of the switch tube S2 and the input end of one of the switch tubes of the front-stage switched capacitor sub-module are connected; The input end of the diode of the switch capacitor sub-module is connected to the output end of the diode of the subsequent stage switched capacitor sub-module respectively with the negative electrode of the DC power supply E, the output end of the diode of the front-stage switched capacitor sub-module, and the diode D1 _of the basic switched capacitor module. _The output of the diode D2 is connected to the output.

It should be noted that the charging loop and the discharging loop are separated in the space-type DC/AC converter, which has fault tolerance and scalability; two "half bridges" are used instead of the H bridge to convert the polarity of the output level, and Reduce the voltage stress of its switch tube.

Example 2

On the basis of the spatial DC/AC converter in Embodiment 1, this embodiment provides a specific implementation of a modulation method for a spatial DC/AC converter:

Through the driving signal, the spatial DC/AC converter in Example 1 is controlled to work in 2N+5 modes, and output 2N+5 levels: 0, ±E, ±2E, ..., ±(N+2 ) E; among them, N represents the number of switched capacitor sub-modules.

As shown in Fig. 2(a) to Fig. 2(g), when the spatial DC/AC converter includes a switched capacitor sub-module, the above-mentioned spatial DC/AC converter is controlled to work in seven kinds of mode, and outputs seven levels: 0, ±E, ±2E and ±3E; the spatial DC/AC converter realizes the series connection of electrolytic capacitors by controlling the _on -off state of the switch S4 to the switch S7 _{. The} control switches S1 to S3 charge the electrolytic capacitors in the _on state, and the switches _S8 and _S9 and _S10 and _S11 are alternately turned on to generate a negative level.

Figures 2(a) to 2(g) show the working principle diagrams of the spatial DC/AC converter including a switched capacitor sub-module in different modes, the symbols "+" and "-" represent the connected load The positive and negative poles of the space-type DC/AC converter are represented by U. In the absence of an open-circuit fault, the space-based DC/AC converter including a switched capacitor sub-module is configured to operate in seven modes, including:

Working state a: switch tube S ₁ , switch tube S ₅ , switch tube S ₇ , switch tube S ₈ and switch tube S ₁₁ are turned on, the rest of the switch tubes are turned off, the diode D ₁ is turned on, and the rest of the diodes are in an idle state , the output voltage U is 3E;

As shown in Figure 2(a), the switching tube S ₁ , the DC power supply E, and the diode D ₁ form a charging loop, the switching tube S ₁ is turned on, and the DC power supply E charges the electrolytic capacitor C ₁ ; the switching tube S ₈ , the electrolytic capacitor C ₁ , switch tube S ₅ , electrolytic capacitor C ₂ , switch tube S ₇ , electrolytic capacitor C ₃ and switch tube S ₁₁ form a discharge loop, switch tubes S ₅ and S ₇ are turned on, capacitors C ₁ , C ₂ and C ₃ series discharge;

Working state b: switch tube S ₁ , switch tube S ₅ , switch tube S ₇ , switch tube S ₈ and switch tube S ₁₀ are turned on, the rest of the switch tubes are turned off, the diode D ₁ is turned on, and the rest of the diodes are in an idle state , the output voltage U is 2E;

As shown in Figure 2(b), the switch tube S ₁ , the DC power supply E, and the diode D ₁ form a charging loop, the switch tube S ₁ is turned on, and the DC power supply E charges the capacitor C ₁ ; the switch tube S ₈ , the electrolytic capacitor C _{1. The} switch tube S5, the electrolytic capacitor _C2 , the switch tube S7 and the switch tube _S10 form a discharge loop, the switch tubes _S5 and _S7 are turned _on , and the capacitors _C1 and _C2 are discharged in series;

Working state c: switch tube S ₂ , switch tube S ₄ , switch tube S ₇ , switch tube S ₈ and switch tube S ₁₁ are turned on, the rest of the switch tubes are turned off, the diode D ₂ is turned on, and the rest of the diodes are in an idle state , the output voltage U is E;

As shown in Figure 2(c), the switching tube S ₂ , the DC power supply E, the diode D ₂ and the electrolytic capacitor C ₂ form a charging loop, the switching tube S ₂ is turned on, and the DC power supply E charges the capacitor C ₂ ; the switching tube S _8. The switch tube S ₄ , the switch tube S ₇ , the electrolytic capacitor C ₃ and the switch tube S ₁₁ form a discharge loop, the switch tubes S ₄ and S ₇ are turned on, and the capacitor C ₃ discharges;

Working state d: switch tube S ₁ , switch tube S ₃ , switch tube S ₅ , switch tube S ₆ , switch tube S ₉ and switch tube S ₁₁ are turned on, the rest of the switch tubes are turned off, and diode D ₁ and diode D ₃ are turned on The other diodes are in the idle state, and the output voltage U is 0;

As shown in Figure 2(d), the electrolytic capacitor C ₁ , the switch tube S ₁ , the DC power supply E, the switch tube S ₃ , the electrolytic capacitor C ₃ , the diode D ₃ and the diode D ₁ form a charging loop, and the switch tube S ₁ and S3 is turned _on , and the DC power supply E charges the capacitors _C1 and C3 _; the switch tube _S9 , the switch tube S5, the switch tube _S6 and the switch _{tube S11} form a discharge loop;

Working state e: switch tube S ₁ , switch tube S ₃ , switch tube S ₅ , switch tube S ₆ , switch tube S ₉ and switch tube S ₁₀ are turned on, the rest of the switch tubes are turned off, and diode D ₁ and diode D ₃ are turned on The other diodes are in idle state, and the output voltage U is -E;

As shown in Figure 2(e), the electrolytic capacitor C ₁ , the switch tube S ₁ , the DC power supply E, the switch tube S ₃ , the diode D ₃ and the diode D ₁ form a charging loop, and the switch tubes S ₁ and S ₃ are turned on, The DC power supply E charges the capacitors C ₁ and C ₃ ; the switch tube S ₉ , the switch tube S ₅ , the switch tube S ₆ , the electrolytic capacitor C ₃ and the switch tube S ₁₀ form a discharge loop, and the switch tubes S ₅ and S ₆ are turned on, Capacitor C3 discharges _;

Working state f: switch tube S ₃ , switch tube S ₄ , switch tube S ₆ , switch tube S ₈ and switch tube S ₁₀ are turned on, the rest of the switch tubes are turned off, the diode D ₃ is turned on, and the rest of the diodes are in an idle state , the output voltage U is -2E;

As shown in Figure 2(f), the switch tube S ₃ , the DC power supply E and the diode D ₃ form a charging loop, the switch tube S ₃ is turned on, and the DC power supply E charges the capacitor C ₃ ; the switch tube S ₈ , the switch tube S _4. The electrolytic capacitor C ₂ , the switch tube S ₆ , the electrolytic capacitor C ₃ and the switch tube S ₁₀ form a discharge loop, the switch tubes S ₄ and S ₆ are turned on, and the capacitors C ₂ and C ₃ are discharged in series;

Working state g: switch tube S ₃ , switch tube S ₄ , switch tube S ₆ , switch tube S ₉ and switch tube S ₁₀ are turned on, the rest of the switch tubes are turned off, the diode D ₃ is turned on, and the rest of the diodes are in an idle state , the output voltage U is -3E;

As shown in Figure 2(g), the switch tube S ₃ , the DC power supply E and the diode D ₃ form a charging loop, the switch tube S ₃ is turned on, and the DC power supply E charges the capacitor C ₃ ; the switch tube S ₉ , the electrolytic capacitor C _1. Switch tube S ₄ , electrolytic capacitor C ₂ , switch tube S ₆ , electrolytic capacitor C ₃ and switch tube S ₁₀ form a discharge loop, switch tubes S ₄ and S ₆ are turned on, capacitor C ₁ , capacitor C ₂ , capacitor C ₃ discharge in series.

It should be noted that, when each switch tube of the spatial DC/AC converter including a switched capacitor sub-module is working normally, a DC power supply can be used to realize a seven-level stepped voltage output (±3E, ±2E, ±E , 0) and ₃ times the voltage gain; the maximum voltage stress of the switches is equal to 2E; the maximum voltage stress _of the switches S1 and S3 is 2E, and the maximum voltage stress of the other switches is E.

Further, when N=1, as shown in FIG. 3, the logic signals u ₁ to u ₆ are obtained by comparing the sinusoidal modulation wave U _ref with the six triangular carrier waves u _a1 to u _a6 , and the logic signals u ₁ to u ₆ After logical combination, the drive signal of each switch tube is output, and the expression of the drive signal of each switch tube is:

When N≥2, the modulation method of the spatial DC/AC converter is the same as when N=1; the logic is obtained by comparing the sinusoidal modulation wave U _ref with N+2 triangular carriers u _a1 to u _{a (N+2)} The signals u ₁ to u _{N +2 are} logically combined to obtain the drive signals of the respective switch tubes.

It can be understood that this embodiment proposes a modulation strategy on the basis of the spatial DC/AC converter including a switched capacitor sub-module, and the modulation principle is shown in FIGS. 3 to 6 . This strategy adopts the carrier stacking pulse width modulation technology, uses 6 channels of triangular carriers with the same amplitude and the same frequency to stack in turn, compares them with the 1 channel amplitude sine modulated wave, and then logically combines the obtained 6 channels of original pulse waveforms to get The gate pulse signal used to drive the switch on and off. The number of triangular carrier signals is determined based on the number of output levels (other than 0), and the state of the switch tube is predetermined according to the operating state of the spatial DC/AC converter, wherein redundant switch combinations are considered; The on-off state of the tube in one cycle and compare with the pulse shown in Figure 4.

It should be noted that the working states of the switch tube _S4 and the switch tube _S5 are complementary, the switch tube _S6 and the switch tube _S7 work in the complementary state, the switch tube _S8 and the switch tube _S9 work in the complementary state, and the switch tube _S10 and the switch tube _S11 work in a complementary state, thus reducing the control complexity of the space-type DC/AC converter.

This embodiment verifies the spatial DC/AC converter including a switched capacitor sub-module through experiments according to the above modulation method. Figure 7 shows the output voltage V _o and load current I _o of the converter with a resistive inductive load waveform diagram. According to the waveform diagram, under the condition of resistive-inductive load (RL), the space-type DC/AC converter can output a standard 7-level stepped voltage waveform during stable operation, and the output voltage reaches a boost gain of 3 times; Its load current waveform exhibits a smooth sinusoidal curve and lags the output voltage waveform. Practice has proved that the space-type DC/AC converter has the capability of providing inductive load and the self-balancing capability of capacitor voltage.

It can be understood that when N≥2, the first switched capacitor sub-module includes a switch tube S ₃ , a switch tube S ₆ , a switch tube S ₇ , a diode D ₃ and an electrolytic capacitor C ₃ , and the i-th switched capacitor sub-module includes an electrolytic capacitor Capacitor C _i3 , diode D _i3 , switch S _i3 , switch S _i6 and switch S _i7 .

In a specific embodiment, the spatial DC/AC converter includes two switched capacitor sub-modules to form a nine-level spatial converter. The topology is shown in FIG. 11, and nine output levels are: 0, ±E, ±2E, ±3E and ±4E; the first-stage switched capacitor sub-module includes switch S ₃ , switch S ₆ , switch S ₇ , diode D ₃ and electrolytic capacitor C ₃ ; the added switched capacitor sub-module is a second-stage switched capacitor sub-module, which includes a switch tube S ₂₃ , a switch tube S ₂₆ , a switch tube S ₂₇ , a diode D ₂₃ and an electrolytic capacitor C ₂₃ ;

It can be understood that the working principle of the nine-level spatial converter is similar to the above-mentioned seven-level converter (a spatial DC/AC converter including _a switched capacitor sub _- module); Charges at levels E and 2E, capacitors _C2 and _C23 charge at output levels 0 and -E.

On the basis of the spatial DC/AC converter in Embodiment 1, this embodiment also provides a spatial DC/AC conversion system, which includes a controller and a converter, and the converter is the above-mentioned spatial DC/AC converter. When the controller controls the operation of the switches in the spatial DC/AC converter, the steps of the modulation method for the spatial DC/AC converter described above are executed.

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 sub-module; The probability of failure is small, and the fault-tolerant operation method of the spatial DC/AC converter of the present invention is a modulation method after a single switch tube or a single diode has an open-circuit fault.

Specifically, when there is no open-circuit fault in the space-type DC/AC converter, the space-type DC/AC converter including a switched capacitor sub-module is controlled to work in seven modes through the drive signal, and output seven levels: 0, ±E, ±2E and ±3E;

When the switch tube S1 _of the basic switched capacitor module fails, the spatial DC/AC converter including one switched capacitor sub-module is controlled to work in five modes through the drive signal, and output five levels: 0, ±E and ±2E;

When the switch tube S2 or the switch tube _S4 or the switch tube _S5 of the basic switched capacitor module fails, the spatial DC/AC converter including a switched capacitor sub _- module is controlled to work in three modes through the drive signal, Output three levels: 0 and ±E;

When the switch tube S3 of the switched capacitor sub _- module fails, the spatial DC/AC converter including one switched capacitor sub-module is controlled to work in five modes through the drive signal, and outputs five levels: 0, ±E and ±2E;

When the switch tube _S6 or the switch tube S7 of the switched capacitor sub _- module fails, the spatial DC/AC converter including one switched capacitor sub-module is controlled to work in three modes through the drive signal, and outputs three levels : 0 and ±E;

When the switch tube _S8 or the switch tube _S9 of the half-bridge I fails, the space-type DC/AC converter including a switched capacitor sub-module is controlled to work in five modes through the drive signal, and output five levels: 0, ±E and ±2E;

When the switching tube _S10 or the switching tube _S11 of the half-bridge II fails, the space-type DC/AC converter including a switched capacitor sub-module is controlled to work in five modes through the drive signal, and output five levels: 0, ±E and ±2E.

Further, when the diode D1 _of the basic switched capacitor module fails, the spatial DC/AC converter including a switched capacitor sub-module is configured in five modes and outputs five levels: 0, ±E and ±2E;

When the diode D2 of the basic switched capacitor module fails, the spatial DC/AC converter including a switched capacitor sub _- module is configured in three modes and outputs three levels: 0 and ±E;

When the diode _D3 of the switched capacitor sub-module fails, the space-type DC/AC converter including one switched capacitor sub-module is configured in five modes and outputs five levels: 0, ±E and ±2E.

It should be noted that, if an open circuit fault occurs in the switch tubes S ₁ , S ₂ or S ₃ and the diodes D ₁ , D ₂ or D ₃ , the corresponding electrolytic capacitors cannot be charged.

Specifically, when the switch S1 or the diode D1 has _an open _- circuit fault, the electrolytic capacitor _C1 is isolated from its discharge circuit by changing the control strategy, the switches S4 and _S8 , and _S5 and _S9 are turned _on or off at the same time. Tubes _S8 and _S9 are turned on alternately. At this time, the spatial DC/AC converter works as a five-level converter;

When the switch S2 or the diode D2 has an open _- circuit fault, the switches S4 and _S7 and the switches _S5 and _{S6 are} turned _on or off at the same time, and the capacitors _C1 and _C3 cannot be discharged in series. At this time, the spatial DC/AC converter operates as a three-level converter;

When the switch tube S3 or the diode _D3 has an open _- circuit fault, the space-type DC/AC converter operates as a five-level converter;

Since the switches S ₄ and S ₅ , S ₆ and S ₇ work in the complementary state, when any one of the two switches in the complementary state has an open-circuit fault, the other switch remains in a conducting state; When any one of the switch tubes S ₄ , S ₅ , S ₆ or S ₇ has an open-circuit fault, the space-type DC/AC converter operates as a three-level converter;

Since the switches S ₈ and S ₉ , S ₁₀ and S ₁₁ work in the complementary state, when any one of the two switches in the complementary state has an open-circuit fault, the other switch remains in a conducting state; When any one of the switch tubes S ₈ , S ₉ , S ₁₀ or S ₁₁ has an open-circuit fault, the space-type DC/AC converter operates as a five-level converter.

On the basis of the above-mentioned fault-tolerant operation method of a space-type DC/AC converter, this embodiment provides a specific implementation of a fault-tolerant system for a space-type DC/AC converter. The fault-tolerant system includes a controller and a space-type DC/AC converter. When the controller controls the operation of the switches in the spatial DC/AC converter, the steps of the above-mentioned fault-tolerant operation method of the spatial DC/AC converter are performed.

Example 4

After an open circuit fault occurs in a single switch tube or a single diode in a space-type DC/AC converter including a switched capacitor sub-module, this embodiment provides a specific implementation of a fault-tolerant operation method for a space-type DC/AC converter ;

Specifically, when a single switch tube or a single diode in different positions has an open-circuit fault, the switch tubes in the same state, the switch tubes that remain on, and the number of corresponding output levels are shown in the following table:

。

.

In this embodiment, a fault-tolerant operation method of a space-type DC/AC converter including a switched capacitor sub-module is described by taking the open-circuit fault of the switch S1 or the switch _S8 as _an example.

In a specific implementation manner, after the switch tube S1 _of the basic switched capacitor module has an open-circuit fault, each device of the spatial DC/AC converter including one switched capacitor sub-module at each output level status, as shown in the following table:

For the switches in the same or complementary relationship described above, only the state of one of the switches is given, "1" and "0" represent the on and off states of the switch respectively; "C", "D" and "─" Represent the charging, discharging and idle states of the capacitor, respectively.

As shown in Figures 8(I) to 8(V), when the switch tube S1 _of the basic switched capacitor module fails, the five modes of the spatial DC/AC converter including a switched capacitor sub-module are as follows: :

Working mode I: switch tube S ₅ , switch tube S ₇ , switch tube S ₉ and switch tube S ₁₁ are turned on, the rest of the switch tubes are turned off, the diode D ₂ is turned on, the rest of the diodes are in an idle state, and the output voltage U is 2E;

Working mode II: switch tube S ₂ , switch tube S ₄ , switch tube S ₇ , switch tube S ₈ and switch tube S ₁₁ are turned on, the rest of the switch tubes are turned off, the diode D ₂ is turned on, and the rest of the diodes are idle state, the output voltage U is E;

Working mode III: switch tube S ₃ , switch tube S ₅ , switch tube S ₆ , switch tube S ₉ and switch tube S ₁₁ are turned on, the rest of the switch tubes are turned off, the diode D ₃ is turned on, and the rest of the diodes are idle state, the output voltage U is 0;

Working mode IV: switch tube S ₃ , switch tube S ₅ , switch tube S ₆ , switch tube S ₉ and switch tube S ₁₀ are turned on, the rest of the switch tubes are turned off, the diode D ₃ is turned on, and the rest of the diodes are idle state, the output voltage U is -E;

Working mode V: switch tube S ₃ , switch tube S ₄ , switch tube S ₆ , switch tube S ₈ and switch tube S ₁₀ are turned on, the rest of the switch tubes are turned off, the diode D ₃ is turned on, and the rest of the diodes are idle state, the output voltage U is -2E.

Fig. 9 shows the waveform diagrams of the output voltage V _o and the load current I _o of the fault-tolerant operation of the space-type DC/AC converter including a switched capacitor sub-module after the switch tube S ₁ fails. _The state changes after the fault, the capacitor _C1 is in an idle state, and the switches S4 and _S8 and S5 and _S9 are turned _on or off at the same time. It can be seen from FIG. 9 that the spatial DC/AC converter quickly stabilizes in a five-level working state. Therefore, the open-circuit fault-tolerant operation capability of the space-type DC/AC converter is proved.

It should be noted that when the diode D ₁ of the basic switched capacitor module fails, the switch tube S ₁ is in an idle state, and the space-type DC/AC converter including a switched capacitor sub-module is configured in five modes, and the output Five levels; at this time, the state of each device of the spatial DC/AC converter at each output level is the same as when the switch S1 _of the basic switched capacitor module fails, so this embodiment will not be repeated.

In another specific embodiment, when the switch tube S2 of the basic switched capacitor module fails, the space _- type DC/AC converter including one switched capacitor sub-module is configured in three modes and outputs three electrical The state of each device of the spatial DC/AC converter at each output level is shown in the following table:

It can be understood that since the switch _S5 and the switch _S6 are in the same state at each output level, the state of the switch S5 can be _deduced according to the state of the switch _S6 in the above table _{; The} switch S4 is in the same state at each output level, so the state of the switch S7 can be deduced according to the state of the switch _S4 in the table above _; since the switch _S9 and the switch _S8 are at each output level Therefore, the state of the switch _S9 can be deduced from the state of the switch _S8 in the above table; since the switch _S11 and the switch _S10 are in a complementary state at each output level, according to the above table The state of the switch tube _S10 can be deduced from the state of the switch tube _S11 .

In another specific embodiment, when the diode D ₂ of the basic switched capacitor module fails, the switch tube S ₂ is in an idle state, and the space-type DC/AC converter including one switched capacitor sub-module is configured with three types of mode, and outputs _three levels; at this time, the states of each device of the spatial DC/AC converter at each output level are the same as when the switch tube S2 of the basic switched capacitor module fails, so this embodiment No longer.

In another specific embodiment, when the switch tube S3 of the switched capacitor sub _- module fails, the space-type DC/AC converter including one switched capacitor sub-module is configured in five modes, and outputs five electrical modes. At this time, the state of each device of the spatial DC/AC converter at each output level is shown in the following table:

It can be understood that since the switch _S5 and the switch S4 are in complementary states at each output level, the state of the switch S5 can be _deduced according to the state of the switch _S4 in the above _{table ; The} switch _S10 is in the same state at each output level, so the state of the switch S7 can be deduced according to the state of the switch _S10 in the table above; since the switch _S9 and the switch _S8 are at each output level Therefore, the state of the switch _S9 can be deduced from the state of the switch _S8 in the above table; since the switch _S11 and the switch _S6 are in the same state at each output level, according to the above table The state of the switch tube _S6 can be derived from the state of the switch tube _S11 .

In another specific embodiment, when the diode D ₃ of the switched capacitor sub-module fails, the switch tube S ₃ is in an idle state, and the space-type DC/AC converter including one switched capacitor sub-module is configured with five types of mode, and outputs five levels; at this time, the state of each device of the spatial DC/AC converter at each output level is the same as when the switch tube S3 _of the basic switched capacitor module fails, so this embodiment No longer.

_In another specific embodiment, when the switch tube S4 of the basic switched capacitor module fails, the spatial DC/AC converter including one switched capacitor sub-module is configured in three modes, and outputs three electrical At this time, the state of each device of the spatial DC/AC converter at each output level is shown in the following table:

It can be understood that the switch S5 maintains a conducting state at each output level _; since the switch _S7 and the switch _S6 are in a complementary state at each output level, the state of the switch _S6 in the above table can _The state of the switch tube S7 is deduced; since the switch tube _S9 and the switch tube _S8 are in a complementary state at each output level, the state of the switch tube _S9 can be deduced according to the state of the switch tube _S8 in the above table; Since the switch _S11 and the switch _S10 are in complementary states at each output level, the state of the switch _S11 can be deduced according to the state of the switch _S10 in the above table.

In another specific embodiment, when the switch tube S5 of the basic switched capacitor module fails, the space _- type DC/AC converter including one switched capacitor sub-module is configured in three modes and outputs three electrical At this time, the state of each device of the spatial DC/AC converter at each output level is shown in the following table:

It can be understood that the switch S4 is in a conducting state at each output level _; since the switch _S7 and the switch _S6 are in a complementary state at each output level, the state of the switch _S6 in the above table can _The state of the switch tube S7 is deduced; since the switch tube _S9 and the switch tube _S8 are in a complementary state at each output level, the state of the switch tube _S9 can be deduced according to the state of the switch tube _S8 in the above table; Since the switch _S11 and the switch _S10 are in complementary states at each output level, the state of the switch _S11 can be deduced according to the state of the switch _S10 in the above table.

In another specific embodiment, when the switch tube _S6 of the switched capacitor sub-module fails, the spatial DC/AC converter including one switched capacitor sub-module is configured in three modes, and outputs three electrical At this time, the state of each device of the spatial DC/AC converter at each output level is shown in the following table:

It can be understood that since the switch _S5 and the switch S4 are in complementary states at each output level, the state of the switch S5 can be _deduced according to the state of the switch _S4 in the above table _; the switch _S7 is in each The conduction state is maintained at the output level; since the switch tube _S9 and the switch tube _S8 are in a complementary state at each output level, the state of the switch tube _S9 can be deduced according to the state of the switch tube _S8 in the above table; Since the switch _S11 and the switch _S10 are in complementary states at each output level, the state of the switch _S11 can be deduced according to the state of the switch _S10 in the above table.

In another specific embodiment, when the switch tube S7 of the switched capacitor sub _- module fails, the spatial DC/AC converter including one switched capacitor sub-module is configured in three modes and outputs three electrical At this time, the state of each device of the spatial DC/AC converter at each output level is shown in the following table:

It can be understood that since the switch _S5 and the switch S4 are in complementary states at each output level, the state of the switch S5 can be _deduced according to the state of the switch _S4 in the above table _; the switch _S6 is in each The conduction state is maintained at the output level; since the switch tube _S9 and the switch tube _S8 are in a complementary state at each output level, the state of the switch tube _S9 can be deduced according to the state of the switch tube _S8 in the above table; Since the switch _S11 and the switch _S10 are in complementary states at each output level, the state of the switch _S11 can be deduced according to the state of the switch _S10 in the above table.

In another specific embodiment, when the switch _S8 of the half-bridge I has an open-circuit fault, the switch _S9 is kept on, and the three electrolytic capacitors are charged normally. During the maximum output level, at most two electrolytic capacitors are discharged in series; at this time, the space-type DC/AC converter including a switched capacitor sub-module is configured in five modes and outputs five levels; each device of the space-type DC/AC converter is in each The state at the output level, as shown in the following table:

As shown in Fig. 10(i) to Fig. 10(v), when the switch _S8 of the half-bridge I fails, the five modes of the space-type DC/AC converter including a switched capacitor sub-module are:

Working mode ⅰ: switch tube S ₁ , switch tube S ₅ , switch tube S ₇ , switch tube S ₉ and switch tube S ₁₁ are turned on, the rest of the switch tubes are turned off, the diode D ₁ is turned on, and the rest of the diodes are idle state, the output voltage U is 2E;

Working mode ii: switch tube S ₁ , switch tube S ₅ , switch tube S ₇ , switch tube S ₉ and switch tube S ₁₀ are turned on, the rest of the switch tubes are turned off, the diode D ₁ is turned on, and the rest of the diodes are idle state, the output voltage U is E;

Working mode iii: switch tube S ₂ , switch tube S ₄ , switch tube S ₇ , switch tube S ₉ and switch tube S ₁₁ are turned on, the rest of the switch tubes are turned off, the diode D ₂ is turned on, and the rest of the diodes are idle state, the output voltage U is 0;

Working mode iv: switch tube S ₃ , switch tube S ₅ , switch tube S ₆ , switch tube S ₉ and switch tube S ₁₀ are turned on, the rest of the switch tubes are turned off, the diode D ₃ is turned on, and the rest of the diodes are idle state, the output voltage U is -E;

Working mode ⅴ: switch S ₃ , switch S ₄ , switch S ₆ , switch S ₉ and switch S ₁₁ are turned on, the rest of the switches are turned off, the diode D ₃ is turned on, and the rest of the diodes are idle state, the output voltage U is -2E.

In another specific embodiment, when the switch tube _S9 of the half-bridge I fails, the space-type DC/AC converter including a switched capacitor sub-module is configured in five modes and outputs five levels ; At this time, the state of each device of the spatial DC/AC converter at each output level is shown in the following table:

It can be understood that since the switch _S5 and the switch S4 are in complementary states at each output level, the state of the switch S5 can be _deduced according to the state of the switch _S4 in the above _{table ;} The switch _S6 is in a complementary state at each output level, so the state of the switch S7 can be deduced according to the state of the switch _S6 in the table above; the switch _S8 remains _on at each output level; Since the switch _S11 and the switch _S10 are in complementary states at each output level, the state of the switch _S11 can be deduced according to the state of the switch _S10 in the above table.

In another specific embodiment, when the switch _S10 of the half-bridge II fails, the space-type DC/AC converter including a switched capacitor sub-module is configured in five modes and outputs five levels ; At this time, the state of each device of the spatial DC/AC converter at each output level is shown in the following table:

。

.

It can be understood that since the switch _S5 and the switch S4 are in complementary states at each output level, the state of the switch S5 can be _deduced according to the state of the switch _S4 in the above _{table ; The} switch _S6 is in a complementary state at each output level, so the state of the switch S7 can be deduced according to the state of the switch _S6 in the above table; since the switch _S9 and the switch _S8 are at each output level Therefore, the state of the switch tube _S9 can be deduced from the state of the switch tube _S8 ; the switch tube _S11 maintains a conducting state at each output level.

In another specific embodiment, when the switch tube _S11 of the half-bridge II fails, the space-type DC/AC converter including a switched capacitor sub-module is configured in five modes and outputs five levels ; At this time, the state of each device of the spatial DC/AC converter at each output level is shown in the following table:

It can be understood that since the switch _S5 and the switch S4 are in complementary states at each output level, the state of the switch S5 can be _deduced according to the state of the switch _S4 in the above _{table ; The} switch _S6 is in a complementary state at each output level, so the state of the switch S7 can be deduced according to the state of the switch _S6 in the above table; since the switch _S9 and the switch _S8 are at each output level Therefore, the state of the switch tube _S9 can be deduced according to the state of the switch tube _S8 ; the switch tube _S10 maintains the conduction state at each output level.

Example 5

It should be noted that, when N≥2, the open-circuit fault tolerance strategy of the spatial DC/AC converter is similar to that described in Embodiments 3 and 4, and its characteristics are described below.

When the switch tube in the charging circuit has an open-circuit fault, the corresponding electrolytic capacitor will no longer work. When configuring the redundant state, it is necessary to ensure that the switch tube connected to the positive electrode of the electrolytic capacitor in the charging state is turned off. When the switch tube S1 connected to the switch tube _S8 of the load-side half-bridge _I has an open-circuit fault, the states of the switch tubes _S8 and S4 ₍ switch tubes _S9 and S5 ₎ keep the same; When the switch S _i3 connected to the switch S ₁₀ has an open-circuit fault, the states of the switches S ₁₀ and S _i7 (the switches S ₁₁ and S _i6 ) remain the same; in these two cases, the space-type DC/AC converter The number of output levels is 2N+3.

In addition, when the switch tube S1 has _an open-circuit fault, no capacitor is charged when the output level is 2N+3. When the switch tube in the charging circuit not connected to the load-side switch tube has an open-circuit fault, the two switch tubes connected to the positive electrode (negative electrode) of the corresponding electrolytic capacitor are in the same state, and the output level of the spatial DC/AC converter The number is 2N+1.

When an open-circuit fault occurs in the switch tube in the discharge circuit, the switch tube in the complementary state with the switch tube in the normal working state is kept on. When the load-side switch tube has an open-circuit fault, the output level number of the space-type DC/AC converter is 2N+3; when the non-load-side switch tube has an open-circuit fault, the output level of the space-type DC/AC converter is 2N+3. The flat number is 2N+1.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand: The specific embodiments of the invention are modified or some technical features are equivalently replaced; without departing from the spirit of the technical solutions of the present invention, all of them should be included in the scope of the technical solutions claimed in the present invention.

Claims (9)

1. A space-type DC/AC converter is characterized in that: comprising a DC power supply E, a basic switched capacitor module, N switched capacitor sub-modules, a half bridge I and a half bridge II, and the basic switched capacitor module comprises a switch tube S ₁ , switch S ₂ , switch S ₄ , switch S ₅ , diode D ₁ , diode D ₂ , electrolytic capacitor C ₁ and electrolytic capacitor C ₂ , the half-bridge I includes switch S ₈ and switch S _9. The half-bridge II includes a switch tube _S10 and a switch tube _S11 ; When N=1, the switched capacitor sub-module includes a switch S ₃ , a switch S ₆ , a switch S ₇ , a diode D ₃ and an electrolytic capacitor C ₃ ; The input end of the switch tube S1 _of the basic switched capacitor module is respectively connected to the input end of the switch tube S2, the input end of the switch tube S3 _of the switched capacitor sub _- module and the positive pole of the DC power supply E, respectively, _The output end of the switch tube S1 is respectively connected with the input end of the switch tube _S4 and the anode of the electrolytic capacitor _C1 , and the output end of the switch tube S2 is respectively connected with the input end of the switch tube _{S5 .} terminal, the input terminal of the switch tube _S6 of the switched capacitor sub _- module is connected to the anode of the electrolytic capacitor C2 _; the output terminal of the switch tube S4 is respectively connected with the output terminal of the switch tube S7 of the switched capacitor sub _- module , the input end of the diode D ₂ is connected to the cathode of the electrolytic capacitor C ₂ , and the output end of the switch tube S ₅ is respectively connected to the input end of the diode D ₁ and the cathode of the electrolytic capacitor C ₁ ; The output end of the switch tube S3 _of the switched capacitor sub _- module is respectively connected to the input end of the switch tube S7 and the anode _of the electrolytic capacitor C3, and the output end of the switch tube _S6 is respectively connected to the diode. The input terminal of D ₃ is connected to the cathode of electrolytic capacitor C ₃ ; The negative pole of the DC power supply E is respectively connected with the output terminal of the diode D1 and the output terminal of the diode D2 _of the basic switched capacitor module, and the output terminal of the diode _D3 of the switched capacitor sub _- module; The input end of the switch tube _S8 of the half-bridge I is connected to the anode of the electrolytic capacitor _C1 of the basic switched capacitor module, the output end of the switch tube _S8 is connected to the input end of the switch tube _S9 , The output terminal of the switch tube _S9 is connected to the cathode of the electrolytic capacitor _C1 of the basic switched capacitor module; the input terminal of the switch tube _S10 of the half-bridge II is connected to the electrolytic capacitor C3 _of the switched capacitor sub-module. The anode of the switch tube _S10 is connected to the input end of the switch tube _S11 , and the output end of the switch tube _S11 is connected to the cathode of the electrolytic capacitor C3 _of the switched capacitor sub-module; When N≥2, the i-th switched capacitor sub-module includes an electrolytic capacitor C _i3 , a diode D _i3 , a switch S _i3 , a switch S _i6 and a switch S _i7 , 2≤i≤N; The electrolytic capacitor C _i3 of the i-th switched capacitor sub-module and the electrolytic capacitor C _(i-1)3 of the i-1-th switched capacitor sub-module are cross-connected through the switch tube S _i6 and the switch tube S _i7 ; the i-th switch The anode of the electrolytic capacitor C _i3 of the capacitor sub-module is also connected to the output end of the switch tube S _i3 , and the input end of the switch tube S _i3 is respectively connected to the positive pole of the DC power supply E and the switch tube S ₁ of the basic switched capacitor module. The input end, the input end of the switch tube S ₂ and the input end of the switch tube S _{(i-1) 3} are connected; the cathode of the electrolytic capacitor C _i3 of the i-th switched capacitor sub-module is also connected with the input end of the diode D _i3 , the output end of the diode D _i3 is respectively connected with the cathode of the DC power supply E, the output end of the diode D _{(i-1) 3} , the output end of the diode D ₁ and the output end of the diode D ₂ of the basic switched capacitor module ; The anode of the electrolytic capacitor C _N3 of the Nth switched capacitor sub-module is connected to the input end of the switch _S10 of the half bridge II, and the cathode of the electrolytic capacitor C _N3 is connected to the output end of the switch _S11 of the half bridge II connect. 2 . The space-type DC/AC converter according to claim 1 , wherein the switching transistors S ₄ and S 5 of the basic switched capacitor module, and the switching transistors S _i6 and S ₅ of the switched capacitor sub-module. 3 . The switch S _i7 and the switch S ₈ , the switch S ₉ , the switch S ₁₀ , and the switch S ₁₁ of the half-bridge I and the half-bridge II are switch tubes including reverse diodes, and the switch tubes of the basic switched capacitor module S ₁ , the switch tube S ₂ and the switch tube S _i3 of the switched capacitor sub-module are switch tubes that do not include reverse diodes. 3. A modulation method of a spatial DC/AC converter, characterized in that: Through the driving signal, the spatial DC/AC converter according to claim 1 or 2 is controlled to work in 2N+5 modes, and output 2N+5 levels: 0, ±E, ±2E, ..., ±( N+2) E; wherein, N represents the number of switched capacitor sub-modules. 4. the modulation method of space type DC/AC converter according to claim 3 is characterized in that: when N=1, obtain logic signal by comparing sinusoidal modulation wave U _ref and six triangular carrier waves u _a1 to u _a6 u ₁ to u ₆ , after the logic signals u ₁ to u ₆ are logically combined, the drive signals of each switch tube are output, and the drive signal expression of each switch tube is:

. 5. a fault-tolerant operation method of the described space type DC/AC converter of claim 1 or 2, is characterized in that: When the switch tube S1 _of the basic switched capacitor module fails, the space-type DC/AC converter including one switched capacitor sub-module is controlled to work in five modes through the drive signal, and output five levels: 0, ±E and ±2E; When the switch tube S2 or the switch tube _S4 or the switch tube _S5 of the basic switched capacitor module fails, the spatial DC/AC converter including a switched capacitor sub _- module is controlled to work in three modes through the drive signal, Output three levels: 0 and ±E; When the switch tube S3 of the switched capacitor sub _- module fails, the spatial DC/AC converter including one switched capacitor sub-module is controlled to work in five modes through the drive signal, and outputs five levels: 0, ±E and ±2E; When the switch tube _S6 or the switch tube S7 of the switched capacitor sub _- module fails, the spatial DC/AC converter including one switched capacitor sub-module is controlled to work in three modes through the drive signal, and outputs three levels : 0 and ±E; When the switch tube _S8 or the switch tube _S9 of the half-bridge I fails, the space-type DC/AC converter including a switched capacitor sub-module is controlled to work in five modes through the drive signal, and output five levels: 0, ±E and ±2E; When the switching tube _S10 or the switching tube _S11 of the half-bridge II fails, the space-type DC/AC converter including a switched capacitor sub-module is controlled to work in five modes through the drive signal, and output five levels: 0, ±E and ±2E. 6 . The fault-tolerant operation method of a space-type DC/AC converter according to claim 5 , wherein when the diode D1 _of the basic switched capacitor module fails, the space-type DC/AC/AC converter including a switched capacitor sub-module fails. 7 . The AC converter is configured in five modes and outputs five levels: 0, ±E and ±2E; When the diode D2 of the basic switched capacitor module fails, the spatial DC/AC converter including a switched capacitor sub _- module is configured in three modes and outputs three levels: 0 and ±E; When the diode _D3 of the switched capacitor sub-module fails, the space-type DC/AC converter including one switched capacitor sub-module is configured in five modes and outputs five levels: 0, ±E and ±2E. 7. A spatial DC/AC conversion system, comprising a controller and a converter, wherein the converter is the spatial DC/AC converter according to claim 1 or 2. 8 . The spatial DC/AC conversion system according to claim 7 , wherein: when the controller controls the operation of the switches in the spatial DC/AC converter, the system of claim 3 or 4 is executed. 9 . The steps of the modulation method of the spatial DC/AC converter. 9. A fault-tolerant system for a space-type DC/AC converter, comprising a controller and a space-type DC/AC converter, wherein the controller controls the actions of switches in the space-type DC/AC converter At the time, the steps of the fault-tolerant operation method of the spatial DC/AC converter according to claim 5 or 6 are performed.

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