CN109347344B - Three-level combined fault-tolerant inverter circuit - Google Patents

Abstract

A three-level combined fault-tolerant inverter circuit is disclosed, which includes a three-phase bridge arm fault-tolerant module and a transformer fault-tolerant module. The transformer is used to optimize the three-phase output voltage waveform when the inverter circuit is working normally; after the fault, the faulty bridge arm is removed, and the partial structure of the bridge arm can be used to achieve single-arm, double-arm and three-arm fault tolerance; the transformer can be used to The two-phase voltage is synthesized into three phases for output, and the single-phase fault tolerance is realized to ensure the normal operation of the circuit. The fault-tolerant topology of the three-phase level inverter circuit has a good fault-tolerant function, and the control and topology are simple and easy to implement.

Description

A three-level combined fault-tolerant inverter circuit

technical field

The invention relates to a three-phase inverter circuit technology, in particular to a novel inverter circuit fault-tolerant topology structure composed of an inverter circuit power bridge arm and a transformer.

Background technique

In order to realize the fault-tolerant function of the three-phase inverter circuit, it is often necessary to add more power tubes to increase the redundant bridge arms, so as to implement fault-tolerant control when the inverter circuit fails. Compared with the traditional two-level inverter circuit, the multi-level inverter circuit has good fault-tolerant performance. In this kind of circuit, each voltage vector has a redundant vector to ensure the fault-tolerant operation of the circuit. However, there are many power tubes in the multi-level inverter circuit, so the control is more complicated, and it is often necessary to design different control strategies for the circuit before and after the fault, and the practical application is more complicated. The redundant bridge arm is often not very useful when the circuit is working normally. If it is only used to backup the faulty bridge arm, it will not only lead to complicated control strategies, but also increase the economic cost.

SUMMARY OF THE INVENTION

In view of the problems existing in the prior art, the present invention provides a three-level combined fault-tolerant inverter circuit, including a three-phase bridge arm fault-tolerant module for realizing the fault-tolerant function of a single-tube or multi-tube fault of a certain phase or multi-phase bridge arm , and the transformer fault-tolerant module that outputs the three-phase voltage output function by the remaining two-phase circuit after the entire bridge arm of a certain phase fails.

The three-phase bridge arm fault-tolerant module is divided into four bridge arms, the first bridge arm is the mid-point adjustment bridge arm, and the four power tubes S ₁ , S ₂ , S ₃ , S ₄ from top to bottom and their respective It is composed of an anti-parallel diode and a clamping capacitor C; the collector of each power tube is connected to the negative pole of the anti-parallel diode, and the emitter is connected to the positive pole of the anti-parallel diode to form a power tube unit. Therefore, a phase series is formed from top to bottom. There are _four power tube units _: power tube S1 unit, S2 unit, S3 unit and _S4 unit _; wherein, from top to bottom, the collector _of power tube S1 is connected to the positive pole _of the power supply, and the emission of power tube S1 _The pole is connected to the collector of the power tube _S2 , the emitter of the power tube S2 is connected to the collector _of the power tube S3, the emitter _of the power tube _S3 is connected to the collector of the power tube _S4 , and the The emitter is grounded; and, the "+" end of the clamping capacitor C is connected to the emitter _of the power tube S1, and the "-" end of the clamping capacitor C is connected to the emitter _of the power tube S3 _; The connection point between the emitter and the collector _of the power transistor S3, such a connection point is hereinafter referred to as the "midpoint" of the two power transistors, and is defined as point O;

The remaining three bridge arms in the three-phase bridge arm fault-tolerant module are the three-phase output bridge arms, wherein the A-phase bridge arms are composed of power tubes S _a1 , S _a4 , S _A1 , S _A4 and their respective It is composed of anti-parallel diodes, forming four power tube units from top to bottom: power tube S _a1 unit, S _a4 unit, S _A1 unit, S _A4 unit. The connection methods of the bridge arms are exactly the same; the power tube S _a1 unit and the power tube S _a4 unit connected in series are called the upper bridge arm of the A-phase bridge arm, and the power tube unit S _A1 and the power tube S _A4 unit connected in series are called the upper bridge arm of the A-phase bridge arm. is the lower arm of the A-phase bridge arm; point a is the midpoint of the power tubes S _a1 and S _a4 of the upper arm, and point A is the midpoint of the power tubes S _A1 and S _A4 of the lower arm; as the extension of the upper arm , the filter inductor L _a and the filter resistor R _a are connected in series, and a filter capacitor C _a is connected in parallel after the filter resistor R _a ; and the positive end of the filter inductor L _a is connected to point a, and the negative end is connected to the filter resistor _Ra , The other end of the filter resistor R _a is connected to the positive end of the filter capacitor _{C a} , and the negative end of the filter capacitor C _a is defined as point O ₁ ; as an extension of the lower bridge arm, the filter inductor LA and the filter resistor _RA are connected in series, _A filter capacitor CA is connected in parallel behind the filter resistor _RA ; the positive end of the filter inductor LA is connected to point _A , the negative end is connected to the filter resistor _RA , and the other end of the filter resistor _RA is connected to the positive end of the filter capacitor _CA The terminals are connected, and the negative terminal of the filter inductor C _A is defined as the point O ₂ ;

The three-phase output bridge arm structure is the same;

Since the structure of the three-phase bridge arms is the same, there are filter inductors L _b , L _c , filter resistors R _b , R _c , and filter capacitors C _b , C _c in the upper bridge arms of the B and C phases, respectively. All filter capacitors The "-" terminals of C _a , C _b , and C _c are all connected to point O ₁ ; in the lower arms of the two phases B and C, there are filter inductors L _B , L _C , filter resistors R _B , R _C , and Filter capacitors C _B , C _C , the "-" ends of the filter capacitors C _A , C _B , and C _C of the three-phase lower bridge arm are all connected to point O ₂ ; the A-phase upper bridge arm filter resistance R _a is connected to the transformer module and A-phase load LoadA is connected in series with the lower bridge arm _RA to form a loop;

In the three-phase bridge arm fault-tolerant module, it is defined that U is the output voltage between point a and point O of the upper bridge arm of phase A, U _Ag is the output voltage between point A and ground point g of the lower bridge arm of phase A, and S _a1 -S _a6 , S _A1 -S _A6 are the 6 power switch tubes of the upper and lower bridge arms respectively; the three-phase output voltage is superimposed by the upper and lower working circuits respectively; R _X , L _X , C _X , X=a, b, c, A, B, C are the filter resistance, filter inductance and filter capacitor of each phase bridge arm; for simplicity of description, the upper bridge of the three-phase output bridge arm in the three-phase bridge arm fault-tolerant module is now The arms are collectively referred to as the upper three bridge arms of the circuit, and the respective lower bridge arms of the three-phase output bridge arms are collectively referred to as the lower three bridge arms of the circuit;

The transformer fault-tolerant module is two sets of three-phase transformers, which specifically include three-phase transformers a, b and c on the upper bridge arm and three-phase transformers A, B, and C on the lower bridge arm;

C相绕组的原副边变比

In the transformer fault-tolerant module, the transformation ratio of the primary and secondary sides of the A-phase winding is T _1a : T _2a1 : T _2a2 = 1: 1: 0.5, and the transformation ratio of the primary and secondary sides of the B-phase winding

Primary and secondary side transformation ratio of C-phase winding

c相的原边线圈与副边四个线圈的线圈匝数比分别为

The turns ratio of the primary side coil and the two secondary side coils of phase a of the upper-arm transformer is T _1a : T _2a1 : T _2a2 = 1: 1: 0.5; the primary side coil and the three secondary side coils of phase b The turns ratio of the coils are

The coil turns ratios of the primary coil of phase c and the four secondary coils are respectively:

The two transformers of the transformer fault-tolerant module have the same structure. For the transformer connected to the upper bridge arm, the primary winding of the three-phase transformer consists of three windings: T _1a , T _1b and T _1c . The "-" terminals are respectively connected with the filter resistor output terminals of the upper arms a, b, and c, and the "-" terminals of the three windings are connected together with the O ₁ point; there are many secondary windings of the transformer, which will be explained in turn. The secondary winding of phase a is composed of two sets of coils with three taps. The first one of the three taps is "+" and the last one is "-"; the secondary winding of phase b is composed of three sets of coils with four taps. Among the four taps, the first one is "+" and the last one is "-"; the secondary winding of phase C consists of four sets of coils with five taps, the first one of the five taps is "+", and the last one is "-". It is "-"; the difference from the upper bridge arm transformer is that the positive and negative directions of the secondary side taps of the lower bridge arm transformer are opposite, the first one is "-" and the last one is "+", and the rest of the composition is the same, Specifically: the secondary winding of phase A of the lower arm transformer consists of three taps and two sets of coils, the first of which is "-" and the last one is "+"; the secondary winding of phase B consists of four It consists of three sets of coils with five taps, the first one of the four taps is "-" and the last one is "+"; the secondary winding of phase C consists of four sets of coils with five taps, and the first one of the five taps is "+"; is "-", the last one is "+"; the secondary side of the upper and lower bridge arm transformers are connected through the load of this phase to form a loop.

C相绕组的原副边变比

In a specific embodiment of the present invention, in the transformer fault-tolerant module, the transformation ratio of the primary and secondary sides of the A-phase windings is T _1a : T _2a1 : T _2a2 =1:1:0.5, and the transformation ratio of the primary and secondary sides of the B-phase windings is 1:1:0.5.

Primary and secondary side transformation ratio of C-phase winding

c相的副边绕组的原边线圈与副边四个线圈的线圈匝数比分别为

The turns ratio of the primary coil and the two secondary coils of the secondary winding of phase a of the upper bridge arm transformer is respectively T _1a : T _2a1 : T _2a2 = 1: 1: 0.5; The coil turns ratios of the side coil and the three secondary coils are respectively

The coil turns ratio of the primary coil and the four secondary coils of the secondary winding of phase c are:

In an embodiment of the present invention, the sizes and types of power tubes, transformers, diodes, capacitors, inductors, and resistors are all determined by the output power of the inverter circuit.

In a specific embodiment of the present invention, the DC voltage source is 270V, the power tube is selected from IGBT, the filter inductor L _a =2mH, the filter capacitor C _a =40μF, and the filter resistance R _a =25mΩ.

The working method of the above three-level combined fault-tolerant inverter circuit is that LoadA, LoadB, and LoadC are three-phase loads respectively. In each phase output, the load of the circuit is connected through the transformers of the upper and lower bridge arms; when the circuit is working normally, each The control signals of the upper and lower arms of one phase are different, and the appropriate control signal needs to be selected according to different control methods; when the upper arm or the lower arm of a phase arm fails, the circuit will cut off the faulty arm, and at the same time the normal bridge arm of the phase will be cut off. The output of the arm is added to the transformer side of the faulty bridge arm, so that the faulty bridge arm becomes the output of the two-level inverter circuit;

Table 1 shows the relationship between the A-phase switching state and the output voltage of the A bridge arm; as shown in Table 1, the relationship between the A-phase switching state and the A bridge arm output voltage can meet the three-level output requirements, and 0 in Table 1 indicates that the switch is in the open state , 1 means the switch is off;

Table 1 The relationship between the switching state of phase A and the output voltage of the bridge arm of A

When the three-level combined fault-tolerant inverter circuit works normally, the output voltage of each phase is the superposition of the output voltage of the upper and lower bridge arms, and the three-phase sine wave is output through the filter capacitor and the filter inductor;

When the A-phase upper half bridge arm fails, the A-phase upper bridge arm is cut off from the circuit, and the A-phase upper bridge arm load is connected to the A-phase lower arm output terminal. At this time, the A-phase bridge arm is used as a two-level inverter. Change the circuit output; when the bridge arm on one side of the other phase fails, the processing method is similar;

When the upper half bridge arm of phase A and B fails, remove the upper bridge arm of phase A and B from the circuit, connect the load of the upper arm of phase A to the output terminal of the lower arm of phase A, and connect the load of the upper arm of phase B to the output terminal of the lower arm of phase A. The output terminal of the lower arm of phase B; when the other two-phase arm fails, the processing method is similar;

When A, B, C-phase upper half bridge arm fails, cut A, B, C-phase upper bridge arm from the circuit, connect A, B, C three-phase upper bridge arm load to A, B, C three-phase The output terminal of the lower bridge arm;

When the phase A of the circuit fails, the entire circuit of the A phase is cut off, and the voltage reference signals of the B and C phases are adjusted to a voltage signal with a phase difference of 90°, that is, the B phase leads the C phase by 90°;

When the B-phase of the circuit fails, the entire circuit of the B-phase is cut off, and the voltage reference signals of the A and C phases are adjusted to a voltage signal with a phase difference of 90°, that is, the A-phase leads the C-phase by 90°;

When the C-phase of the circuit fails, the entire circuit of the C-phase is cut off, and the voltage reference signals of the A and B phases are adjusted to a voltage signal with a phase difference of 90°, that is, the A-phase leads the B-phase by 90°.

When the inverter circuit is working normally, the invention uses the transformer to optimize the three-phase output voltage waveform; after the fault, the faulty bridge arm is cut off, and the transformer is used to synthesize the two-phase voltage into three-phase output to ensure the normal operation of the circuit. The fault-tolerant topology of the three-phase three-level inverter circuit has a good fault-tolerant function for single-arm faults, and the control and topology are simple and easy to implement.

Description of drawings

Fig. 1 is the topological structure diagram of inverter circuit of the present invention;

Fig. 2 is the fault-tolerant circuit of the single-arm fault of the inverter circuit;

Fig. 3 is the fault-tolerant circuit of the double-arm fault of the inverter circuit;

Figure 4 is a fault-tolerant circuit for the three-arm fault of the inverter circuit;

Figure 5 is the A-phase fault, topology fault tolerance scheme and the wiring diagram of the transformer module after the A-phase is removed, in which Figure 5(a) shows the A-phase fault topology reconstruction scheme, and Figure 5(b) shows the A-phase fault transformer side wiring Program;

Figure 6 is the B-phase fault, topology fault-tolerant scheme and the wiring diagram of the transformer module after the B-phase is removed. Figure 6(a) shows the circuit reconstruction topology after the B-phase is removed, and Figure 6(b) shows the B-phase fault transformer side. wiring scheme;

Figure 7 is the C-phase fault, topology fault tolerance scheme and the wiring diagram of the transformer module after the C-phase is removed, in which Figure 7(a) shows the circuit reconstruction topology after the C-phase is removed, and Figure 7(b) shows the C-phase fault transformer side wiring scheme.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

As shown in Figure 1, the main circuit topology of the three-level combined fault-tolerant inverter circuit of the present invention is divided into two modules, the left part is the three-phase bridge arm fault-tolerant module, and the right part is the transformer fault-tolerant module, respectively represented by two dashed boxes . The fault-tolerant functions of the two modules are different, which can meet the fault-tolerant work of the inverter circuit when the circuit fails in various complex situations.

In the three-phase bridge arm fault-tolerant module, it is divided into four bridge arms, the first bridge arm is the neutral point adjustment bridge arm, and the top-down four power tubes S ₁ , S ₂ , S ₃ , S ₄ and their It is composed of its respective anti-parallel diode and clamping capacitor C; the collector of each power tube is connected to the negative pole of the anti-parallel diode, and the emitter is connected to the positive pole of the anti-parallel diode to form a power tube unit. Therefore, from top to bottom _A total of _four power tube units connected in series are formed: power tube S1 unit, S2 unit, S3 unit and _S4 unit _; wherein, from top to bottom, the collector _of power tube S1 is connected to the positive pole of the power supply, and the power tube _The emitter of S1 is connected with the collector of power tube _S2 , the emitter of power tube _S2 is connected with the collector _of power tube S3, the emitter _of power tube _S3 is connected with the collector of power tube S4, the power _The emitter of the tube S4 is grounded; and the "+" end of the clamping capacitor C is connected to the emitter _of the power tube S1 ₍ that is, the collector of the power tube S2), and the "-" end of the clamping capacitor C is connected to _The emitter of the power tube S3 (that is, the collector of S4 ₎ is connected; the connection point between the emitter of the power tube S2 and the collector _of the power tube S3 (hereinafter such connection points are referred to as _two The "midpoint") of the power tube is defined as point O.

The remaining three bridge arms in the three-phase bridge arm fault-tolerant module are respectively three-phase output bridge arms, and the three bridge arms have the same structure. The A-phase bridge arm is taken as an example for illustration. The A-phase bridge arm is composed of power tubes S _a1 , S _a4 , S _A1 , S _A4 and their respective anti-parallel diodes from top to bottom, forming four power tube units from top to bottom: the power tube S _a1 unit, The connection method of the S _a4 unit, the S _A1 unit, and the S _A4 unit, and the four power tube units are exactly the same as the connection method of the above-mentioned neutral point adjustment bridge arm, and will not be repeated. Among them, the power tube S _a1 unit and the power tube S _a4 unit connected in series are called the upper bridge arm of the A-phase bridge arm, and the power tube unit S _A1 and the power tube S _A4 unit connected in series are called the upper arm of the A-phase bridge arm. Lower bridge arm. Point a is the midpoint of the power tubes S _a1 and S _a4 of the upper bridge arm, and point A is the midpoint of the power tubes S _A1 and S _A4 of the lower bridge arm. As an extension of the upper bridge arm, the filter inductor La and the filter resistor _Ra are connected in series, and _a filter capacitor C _a is connected in parallel after the filter resistor _Ra ; the positive end of the filter inductor _La is connected to point a, and the negative end is connected to the filter The resistor _Ra is connected, and the other end of the filter resistor _Ra is connected to the positive end of the filter capacitor C _a , and the negative end of the filter capacitor C _a is defined as a point O ₁ . As an extension of the lower bridge arm, the filter inductor LA and the filter resistor _RA are connected in series, and a filter capacitor _{C A} is connected in parallel after the filter resistor _RA ; the positive end of the filter inductor LA is connected to point _A , and the negative end is connected to the filter The resistor _RA is connected, the other end of the filter resistor _RA is connected with the positive end of the filter capacitor _CA , and the negative end of the filter inductor _CA is defined as point O ₂ .

Since the structure of the three-phase bridge arms is the same, there are filter inductors L _b , L _c , filter resistors R _b , R _c , and filter capacitors C _b , C _c in the upper bridge arms of the B and C phases, respectively. All filter capacitors The "-" terminals of C _a , C _b , and C _c are all connected to one point, that is, point O ₁ . In the lower arms of the two phases B and C, there are respectively filter inductors LB and LC, filter resistors _RB and RC, as well as filter capacitors C _B and _{C C} , and filter capacitors C _A and _C of the three-phase lower arms _. The "-" ends of _B and _C are connected to the O ₂ point. A-phase upper bridge arm filter resistance R _a is connected in series with the _A -phase load LoadA and the lower bridge arm RA to form a loop.

In the three-phase bridge arm fault-tolerant module, it is defined that U is the output voltage between point a and point O of the upper bridge arm of phase A, U _Ag is the output voltage between point A and ground point g of the lower bridge arm of phase A, and S _a1 -S _a6 , S _A1 -S _A6 are the 6 power switch tubes of the upper and lower bridge arms, respectively. The three-phase output voltage is superimposed by the upper and lower working circuits respectively. R _X , L _X , and C _X (X=a, b, c, A, B, C) are respectively the filter resistance, filter inductance and filter capacitor of each phase bridge arm. For the sake of simplicity of description, the upper arms of the three-phase output bridge arms in the three-phase bridge arm fault-tolerant module are collectively referred to as the upper three bridge arms of the circuit, and the respective lower arms of the three-phase output bridge arms are collectively referred to as the lower three bridge arms of the circuit .

C相绕组有四组抽头，原副边变比

The transformer fault-tolerant module is composed of two sets of three-phase transformers, specifically including the three-phase transformer on the upper bridge arm and the three-phase transformer on the lower bridge arm. There are two sets of taps on the secondary side of the A-phase winding, and the transformation ratio of the primary and secondary sides is T _1a : T _2a1 : T _2a2 = 1:1:0.5, the B-phase winding has three sets of taps, and the transformation ratio of the primary and secondary sides

The C-phase winding has four sets of taps, the primary and secondary side transformation ratio

c相的副边绕组由五个抽头四组线圈组成，在五个抽头中第一个为“+”，最后一个为“-”，原边线圈与副边四个线圈的线圈匝数比分别为

与上桥臂变压器不同的是下桥臂变压器副边抽头的正负极方向与之相反，均是第一个为“-”最后一个为“+”，其余构成均相同，具体为：下桥臂变压器A相的副边绕组由三个抽头两组线圈组成，在三个抽头中第一个为“-”，最后一个为“+”；B相的副边绕组由四个抽头三组线圈组成，在四个抽头中第一个为“-”，最后一个为“+”；C相的副边绕组由五个抽头四组线圈组成，在五个抽头中第一个为“-”，最后一个为“+”。上下桥臂变压器副边通过该相的负载连接起来构成回路。The two transformers of the transformer fault-tolerant module have the same structure. The following describes the structure of the transformer connected to the upper bridge arm as an example. The primary winding of the three-phase transformer is composed of three windings, T _1a , T _1b and T _1c . The positive terminal) is connected, and the "-" terminals of the three windings are connected together with the O ₁ point. There are many secondary windings of the transformer, which will be described in detail in turn. The secondary winding of phase A of the upper-arm transformer consists of three taps and two sets of coils. Among the three taps, the first one is "+" and the last one is "-". The coil turns ratio of the primary coil and the two secondary coils is T _1a : T _2a1 : T _2a2 = 1: 1: 0.5; the secondary winding of phase b is composed of three sets of coils with four taps. The first one is "+", the last one is "-", the coil turns ratio of the primary coil and the three secondary coils are respectively

The secondary winding of phase c is composed of five taps and four sets of coils. The first one of the five taps is "+" and the last one is "-". The coil turns ratio of the primary coil and the four secondary coils are respectively for

The difference from the upper bridge arm transformer is that the positive and negative directions of the secondary side taps of the lower bridge arm transformer are opposite. The first one is "-" and the last one is "+". The secondary winding of phase A of the arm transformer consists of three taps and two sets of coils. The first one of the three taps is "-" and the last one is "+"; the secondary winding of phase B consists of four taps and three sets of coils. In the four taps, the first one is "-" and the last one is "+"; the secondary winding of phase C consists of four sets of coils with five taps, the first one in the five taps is "-", The last one is "+". The secondary side of the upper and lower bridge arm transformers is connected through the load of the phase to form a loop.

The present invention is an invention of the inverter circuit structure, wherein the size and model of the power tube, transformer, diode, capacitor, inductor and resistor are determined by the output power of the inverter circuit, so it is not limited. In one embodiment of the present invention, the DC voltage source is 270V, the power tube is selected from IGBT, the filter inductor L _a =2mH, the filter capacitor C _a =40μF, and the filter resistance R _a =25mΩ)

LoadA, LoadB, and LoadC are three-phase loads respectively. In each phase output, the loads are connected through the upper and lower bridge arm transformers. When the circuit is working normally, the control signals of the upper and lower bridge arms of each phase are different, and appropriate control signals need to be selected according to different control methods. When the upper arm or lower arm of a certain phase arm fails, the circuit will cut off the faulty arm, and at the same time add the output of the normal arm of the phase to the transformer side of the fail arm, so that the fail arm becomes two arms. Level inverter circuit output.

The three-phase bridge arm fault-tolerant module mainly realizes the fault-tolerant function of single-tube or multi-tube faults of a certain phase or multi-phase bridge arm, while the transformer fault-tolerant module mainly realizes the failure of a certain phase and the whole bridge arm by the remaining two-phase circuits. Output function to output three-phase voltage.

Table 1 is the relationship between the A-phase switching state and the output voltage of the A bridge arm. As shown in Table 1, the relationship between the A-phase switching state and the output voltage of the A bridge arm can meet the three-level output requirements. In Table 1, 0 indicates that the switch is on, and 1 indicates that the switch is off.

Table 1 The relationship between the switching state of phase A and the output voltage of the bridge arm of A

When the circuit shown in Figure 1 works normally, the output voltage of each phase is the superposition of the output voltages of the upper and lower bridge arms, and the three-phase sine wave is output through the filter capacitor and the filter inductor.

When the single-phase bridge arm of the circuit fails, such as the failure of the A-phase upper half bridge arm, the topology reconstruction scheme is shown in Figure 2. The A-phase upper arm is removed from the circuit, and the A-phase upper arm load is connected. The output end of the lower bridge arm of phase A, the connection line is represented by the dotted line in the figure. At this time, the A-phase bridge arm is output as a two-level inverter circuit. When the bridge arm on one side of the other phase fails, the processing method is the same, and the dotted line represents the circuit reconstruction part.

When the two-phase bridge arm of the circuit fails, such as the failure of the upper half bridge arm of the A and B phases, the topology reconstruction scheme is shown in Figure 3. The arm load is connected to the output end of the lower arm of phase A, the dotted line in the figure represents the connection line, and the load of the upper arm of phase B is connected to the output end of the lower arm of phase B.

When the three-phase bridge arm of the circuit fails, such as the failure of the upper half bridge arm of the A, B, and C phases, the topology reconstruction scheme is shown in Figure 4. The upper bridge arm of the A, B, and C phases is removed from the circuit, and the A, B, C three-phase upper bridge arm loads are connected to A, B, C three-phase lower bridge arm outputs, and the dotted line in the figure represents the connection line.

When the A-phase of the circuit fails, the entire circuit of the A-phase is cut off, and the voltage reference signals of the B and C phases are adjusted to a voltage signal with a phase difference of 90°, that is, the B-phase leads the C-phase by 90°. The topology fault-tolerant scheme and the connection of the transformer module after removing the A-phase are shown in Figure 5, and the connection line is represented by a dotted line in the figure.

When the B-phase of the circuit fails, the entire circuit of the B-phase is cut off, and the voltage reference signals of the A and C phases are adjusted to a voltage signal with a phase difference of 90°, that is, the A-phase leads the C-phase by 90°, and the topology is fault-tolerant scheme. And the connection of the transformer module after removing the B phase is shown in Figure 6, and the connection line is represented by a dotted line in the figure.

When the C-phase of the circuit fails, the entire circuit of the C-phase is cut off, and the voltage reference signals of the A and B phases are adjusted to a voltage signal with a phase difference of 90°, that is, the A-phase leads the B-phase by 90°, and the topology is fault-tolerant scheme. And the connection of the transformer module after removing the C phase is shown in Figure 7, and the connection line is represented by a dotted line in the figure.

Claims (4)

1. A three-level combined fault-tolerant inverter circuit, comprising a three-phase bridge arm fault-tolerant module for realizing the fault-tolerant function of a single-tube or multi-tube fault of a certain phase or multi-phase bridge arm, and a whole bridge arm in a certain phase. After a fault occurs, the transformer fault-tolerant module with the output function of outputting three-phase voltage is realized by the remaining two-phase circuit, wherein The three-phase bridge arm fault-tolerant module is divided into four bridge arms, the first bridge arm is the mid-point adjustment bridge arm, and the four power tubes S ₁ , S ₂ , S ₃ , S ₄ from top to bottom and their respective It is composed of an anti-parallel diode and a clamping capacitor C; the collector of each power tube is connected to the negative pole of the anti-parallel diode, and the emitter is connected to the positive pole of the anti-parallel diode to form a power tube unit. Therefore, a phase series is formed from top to bottom. There are _four power tube units _: power tube S1 unit, S2 unit, S3 unit and _S4 unit _; wherein, from top to bottom, the collector _of power tube S1 is connected to the positive pole _of the power supply, and the emission of power tube S1 _The pole is connected to the collector of the power tube _S2 , the emitter of the power tube S2 is connected to the collector _of the power tube S3, the emitter _of the power tube _S3 is connected to the collector of the power tube _S4 , and the The emitter is grounded; and, the "+" end of the clamping capacitor C is connected to the emitter _of the power tube S1, and the "-" end of the clamping capacitor C is connected to the emitter _of the power tube S3 _; The connection point between the emitter and the collector _of the power transistor S3, such a connection point is hereinafter referred to as the "midpoint" of the two power transistors, and is defined as point O; The remaining three bridge arms in the three-phase bridge arm fault-tolerant module are the three-phase output bridge arms, wherein the A-phase bridge arms are composed of power tubes S _a1 , S _a4 , S _A1 , S _A4 and their respective It is composed of anti-parallel diodes, forming four power tube units from top to bottom: power tube S _a1 unit, S _a4 unit, S _A1 unit, S _A4 unit. The connection methods of the bridge arms are exactly the same; the power tube S _a1 unit and the power tube S _a4 unit connected in series are called the upper bridge arm of the A-phase bridge arm, and the power tube unit S _A1 and the power tube S _A4 unit connected in series are called the upper bridge arm of the A-phase bridge arm. is the lower arm of the A-phase bridge arm; point a is the midpoint of the power tubes S _a1 and S _a4 of the upper arm, and point A is the midpoint of the power tubes S _A1 and S _A4 of the lower arm; as the extension of the upper arm , the filter inductor L _a and the filter resistor R _a are connected in series, and a filter capacitor C _a is connected in parallel after the filter resistor R _a ; and the positive end of the filter inductor L _a is connected to point a, and the negative end is connected to the filter resistor _Ra , The other end of the filter resistor R _a is connected to the positive end of the filter capacitor _{C a} , and the negative end of the filter capacitor C _a is defined as point O ₁ ; as an extension of the lower bridge arm, the filter inductor LA and the filter resistor _RA are connected in series, _A filter capacitor CA is connected in parallel behind the filter resistor _RA ; the positive end of the filter inductor LA is connected to point _A , the negative end is connected to the filter resistor _RA , and the other end of the filter resistor _RA is connected to the positive end of the filter capacitor _CA The terminals are connected, and the negative terminal of the filter inductor C _A is defined as the point O ₂ ; The three-phase output bridge arm structure is the same; Since the structure of the three-phase bridge arms is the same, there are filter inductors L _b , L _c , filter resistors R _b , R _c , and filter capacitors C _b , C _c in the upper bridge arms of the B and C phases, respectively. All filter capacitors The "-" terminals of C _a , C _b , and C _c are all connected to point O ₁ ; in the lower arms of the two phases B and C, there are filter inductors L _B , L _C , filter resistors R _B , R _C , and Filter capacitors C _B , C _C , the "-" ends of the filter capacitors C _A , C _B , and C _C of the three-phase lower bridge arm are all connected to point O ₂ ; the A-phase upper bridge arm filter resistance R _a is connected to the transformer module and A-phase load LoadA is connected in series with the lower bridge arm _RA to form a loop; In the three-phase bridge arm fault-tolerant module, it is defined that U is the output voltage between point a and point O of the upper bridge arm of phase A, U _Ag is the output voltage between point A and ground point g of the lower bridge arm of phase A, and S _a1 -S _a6 , S _A1 -S _A6 are the 6 power switch tubes of the upper and lower bridge arms respectively; the three-phase output voltage is superimposed by the upper and lower working circuits respectively; R _X , L _X , C _X , X=a, b, c, A, B, C are the filter resistance, filter inductance and filter capacitor of each phase bridge arm respectively; the respective upper bridge arms of the three-phase output bridge arms in the three-phase bridge arm fault-tolerant module are collectively referred to as the upper three arms of the circuit The bridge arms and the lower arms of the three-phase output bridge arms are collectively referred to as the lower three bridge arms of the circuit; The transformer fault-tolerant module is two sets of three-phase transformers, which specifically include three-phase transformers a, b and c on the upper bridge arm and three-phase transformers A, B, and C on the lower bridge arm; In the transformer fault-tolerant module, the transformation ratio of the primary and secondary sides of the A-phase winding is T _1a : T _2a1 : T _2a2 = 1: 1: 0.5, and the transformation ratio of the primary and secondary sides of the B-phase winding

Primary and secondary side transformation ratio of C-phase winding

The turns ratio of the primary side coil and the two secondary side coils of phase a of the upper-arm transformer is T _1a : T _2a1 : T _2a2 = 1: 1: 0.5; the primary side coil and the three secondary side coils of phase b The turns ratio of the coils are

The coil turns ratios of the primary coil of phase c and the four secondary coils are respectively:

The two transformers of the transformer fault-tolerant module have the same structure. For the transformer connected to the upper bridge arm, the primary winding of the three-phase transformer consists of three windings: T _1a , T _1b and T _1c . The "-" terminals are respectively connected with the filter resistor output terminals of the upper arms a, b, and c, and the "-" terminals of the three windings are connected together with the O ₁ point; there are many secondary windings of the transformer, which will be explained in turn. The secondary winding of phase a is composed of two sets of coils with three taps. The first one of the three taps is "+" and the last one is "-"; the secondary winding of phase b is composed of three sets of coils with four taps. Among the four taps, the first one is "+" and the last one is "-"; the secondary winding of phase C consists of four sets of coils with five taps, the first one of the five taps is "+", and the last one is "-". It is "-"; the difference from the upper bridge arm transformer is that the positive and negative directions of the secondary side taps of the lower bridge arm transformer are opposite, the first one is "-" and the last one is "+", and the rest of the composition is the same, Specifically: the secondary winding of phase A of the lower arm transformer consists of three taps and two sets of coils, the first of which is "-" and the last one is "+"; the secondary winding of phase B consists of four It consists of three sets of coils with five taps, the first one of the four taps is "-" and the last one is "+"; the secondary winding of phase C consists of four sets of coils with five taps, and the first one of the five taps is "+"; is "-", the last one is "+"; the secondary side of the upper and lower bridge arm transformers are connected through the load of this phase to form a loop. 2. The three-level combined fault-tolerant inverter circuit according to claim 1, wherein the size and model of the power tube, transformer, diode, capacitor, inductor and resistor are all determined by the output power of the inverter circuit. 3. The three-level combined fault-tolerant inverter circuit as claimed in claim 2, wherein the DC voltage source is 270V, the power tube is selected from IGBT, the filter inductance L _a =2mH, the filter capacitor C _a =40μF, and the filter resistance R _a = 25mΩ. 4. A three-level combined fault-tolerant inverter circuit working method based on the three-level combined fault-tolerant inverter circuit of claim 1, specifically, LoadA, LoadB, LoadC are three-phase loads respectively, and each phase outputs In the circuit, the load of the circuit is connected through the transformers of the upper and lower bridge arms; when the circuit is working normally, the control signals of the upper and lower bridge arms of each phase are different, and the appropriate control signal needs to be selected according to different control methods; When the lower bridge arm fails, the circuit will cut off the faulty bridge arm, and at the same time add the output of the normal bridge arm of the phase to the transformer side of the faulty bridge arm, so that the faulty bridge arm becomes the output of the two-level inverter circuit; Table 1 shows the relationship between the A-phase switching state and the output voltage of the A bridge arm; as shown in Table 1, the relationship between the A-phase switching state and the A bridge arm output voltage can meet the three-level output requirements, and 0 in Table 1 indicates that the switch is in the open state , 1 means the switch is off; Table 1 The relationship between the switching state of phase A and the output voltage of the bridge arm of A

When the three-level combined fault-tolerant inverter circuit works normally, the output voltage of each phase is the superposition of the output voltage of the upper and lower bridge arms, and the three-phase sine wave is output through the filter capacitor and the filter inductor; When the A-phase upper half bridge arm fails, the A-phase upper bridge arm is cut off from the circuit, and the A-phase upper bridge arm load is connected to the A-phase lower arm output terminal. At this time, the A-phase bridge arm is used as a two-level inverter. Change the circuit output; when the bridge arm on one side of the other phase fails, the processing method is similar; When the upper half bridge arm of phase A and B fails, remove the upper bridge arm of phase A and B from the circuit, connect the load of the upper arm of phase A to the output terminal of the lower arm of phase A, and connect the load of the upper arm of phase B to the output terminal of the lower arm of phase A. The output terminal of the lower arm of phase B; when the other two-phase arm fails, the processing method is similar; When A, B, C-phase upper half bridge arm fails, cut A, B, C-phase upper bridge arm from the circuit, connect A, B, C three-phase upper bridge arm load to A, B, C three-phase The output terminal of the lower bridge arm; When the phase A of the circuit fails, the entire circuit of the A phase is cut off, and the voltage reference signals of the B and C phases are adjusted to a voltage signal with a phase difference of 90°, that is, the B phase leads the C phase by 90°; When the B-phase of the circuit fails, the entire circuit of the B-phase is cut off, and the voltage reference signals of the A and C phases are adjusted to a voltage signal with a phase difference of 90°, that is, the A-phase leads the C-phase by 90°; When the C-phase of the circuit fails, the entire circuit of the C-phase is cut off, and the voltage reference signals of the A and B phases are adjusted to a voltage signal with a phase difference of 90°, that is, the A-phase leads the B-phase by 90°.

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