An adaptive modulation multi-state inverter system and modulation method thereof

Abstract

The present invention proposes a multi-state inverter system with adaptive modulation, including: a split capacitor; four bridge arms, each bridge arm has a pair of complementary power switch groups; an isolating switch group, including a fuse and a bidirectional thyristor, a fuse is connected in series on the output branches of the first bridge arm, the second bridge arm, and the third bridge arm respectively to output a three-phase voltage, and the three-phase voltage output side shares two auxiliary branches, one auxiliary branch is from the output branch of the fourth bridge arm, a fuse is connected in series on the output branch, and then connected to the output points of the three-phase voltage respectively through three bidirectional thyristors, and the other auxiliary branch is from the DC side feeding branch derived from the midpoint of the split capacitor, and is connected to the output points of the three-phase voltage respectively through three bidirectional thyristors. The present invention also provides a modulation method for a multi-state inverter system. The adaptive modulation technology is used to enable the multi-state inverter to have the functions of overcurrent protection, isolation of faulty bridge arms, and fault tolerance control of any single or double bridge arms.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to an adaptively modulated multi-state inverter system and a modulation method thereof. Background Art

[0002] As the core component of energy conversion, the performance of the inverter is directly related to the efficiency and reliability of energy conversion. However, due to the fragility of the power electronic devices in the inverter, system failures occur frequently, directly causing economic losses in industrial production, and catastrophic accidents in important places of people's livelihood such as aviation, subway, and electric vehicles.

[0003] In traditional fault-tolerant inverters, only single or double power switch failures can be solved at most; this means that the types of faults that fault-tolerant inverters can withstand are limited at this stage, and to a certain extent, the reliability of the inverter system is limited. However, the location and number of faults in the inverter are random, and we urgently need to find an inverter strain system that can adapt to and withstand multiple types of faults. Summary of the invention

[0004] The object of the present invention is to provide an adaptively modulated multi-state inverter system and a modulation method thereof, so as to solve the problem that the current fault-tolerant inverter can withstand a limited number of fault types.

[0005] In order to solve the above technical problems, the technical solution of the present invention is: to provide an adaptively modulated multi-state inverter system, comprising: a split capacitor; four bridge arms, each of which has a pair of complementary power switch groups; an isolating switch group, comprising four fuses and six bidirectional thyristors, and a fuse is connected in series on the output branches of the first bridge arm, the second bridge arm and the third bridge arm to output a three-phase voltage, and the three-phase voltage output side shares two auxiliary branches, one auxiliary branch starts from the output branch of the fourth bridge arm, a fuse is connected in series on the output branch, and then connected to the output points of the three-phase voltage respectively via three bidirectional thyristors, and the other auxiliary branch starts from the DC side feeding branch derived from the midpoint of the split capacitor, and is directly connected to the output points of the three-phase voltage respectively via three bidirectional thyristors.

[0006] The present invention also provides a modulation method for a multi-state inverter system using adaptive modulation, comprising the following steps: real-time monitoring of the working states of the four fuses in the isolating switch group, determining the state factors of the four fuses, and determining a fault bridge arm matrix according to the state factors; locating the fault bridge arm according to the number of fault bridge arms in the fault bridge arm matrix, and outputting a working state factor S; when the number of fault bridge arms in the fault bridge arm matrix is ​​0, S=1, when the number of fault bridge arms in the fault bridge arm matrix is ​​1, S=2, when the number of fault bridge arms in the fault bridge arm matrix is ​​2, S=3, when the working state factor S≤2, a six-switch fault-tolerant modulation algorithm is adopted; when the working state factor S=3, a four-switch fault-tolerant modulation algorithm is adopted.

[0007] Furthermore, when the fuse works normally, its state factor is set to 0, and when the fuse is blown, its state factor is set to 1.

[0008] The adaptive modulation multi-state inverter system provided by the present invention combines a multi-state inverter and utilizes adaptive modulation technology to enable the multi-state inverter to have the functions of overcurrent protection, isolation of faulty bridge arms, and fault tolerance control of any single or double bridge arms; it can withstand a variety of fault types, including not only single switch tube faults and double switch tube faults, but also triple switch tube faults and quad switch tube faults, etc.; after any single bridge arm fault occurs and can be successfully fault-tolerant, the fault-tolerant control function can still be achieved even if a single bridge arm fault occurs again and causes a successive double bridge arm fault.

[0009] The modulation method of the multi-state inverter system using adaptive modulation provided by the present invention is a space vector modulation technology based on adaptive control, which can flexibly modulate the healthy bridge arm according to the specific working state factor of the multi-state inverter. First, it is necessary to actually monitor the working state of the fuse. When any single or double bridge arm fails, the fuse on the corresponding fault phase will automatically blow to achieve the function of isolating the faulty bridge arm, and thereby determine the faulty bridge arm matrix, thereby determining the working state factor according to the number of faulty bridge arms; finally, the working state factor is used to achieve the function of modulating the healthy bridge arm. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The invention will be further described below in conjunction with the accompanying drawings:

[0011] Figure 1 A circuit diagram of a multi-state inverter system with adaptive modulation provided by an embodiment of the present invention;

[0012] Figure 2 A flow chart of the steps of a modulation method for a multi-state inverter system using adaptive modulation provided by the present invention;

[0013] Figure 3A spatial vector diagram of a multi-state fault-tolerant inverter when S≤2 provided by an embodiment of the present invention;

[0014] Figure 4a A switching sequence diagram of the first sector when there is no fault in the multi-state fault-tolerant inverter when S≤2 provided by an embodiment of the present invention;

[0015] Figure 4b The embodiment of the present invention provides a switching sequence diagram of the second sector when the A phase of the multi-state fault-tolerant inverter fails when S≤2;

[0016] Figure 5 A spatial vector diagram of a multi-state fault-tolerant inverter when S=3 provided in an embodiment of the present invention;

[0017] Figure 6a 1 is a switching sequence diagram of the first sector when the A&B phase of the multi-state fault-tolerant inverter fails when S=3 in an embodiment of the present invention;

[0018] Figure 6b 1 is a switching sequence diagram of the second sector when the A&B phase of the multi-state fault-tolerant inverter fails when S=3 in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The following is a further detailed description of the adaptive modulation multi-state inverter system and modulation method thereof proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer according to the following description and claims. It should be noted that the accompanying drawings are all in a very simplified form and use inaccurate ratios, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0020] The core idea of ​​the present invention is that the adaptive modulation multi-state inverter system provided by the present invention combines the multi-state inverter and uses the adaptive modulation technology to enable the multi-state inverter to have the functions of overcurrent protection, isolation of faulty bridge arms and fault tolerance control of any single or double bridge arms; it can withstand a variety of fault types, including not only single switch tube faults, double switch tube faults, but also three switch tube faults and four switch tube faults; after any single bridge arm fault occurs and can be successfully fault-tolerant, even if a single bridge arm fault occurs again and causes a successive double bridge arm fault, the function of fault-tolerant control can still be realized. The modulation method of the multi-state inverter system using adaptive modulation provided by the present invention is a space vector modulation technology based on adaptive control, which can flexibly modulate the healthy bridge arm according to the specific working state factor of the multi-state inverter. First, it is necessary to actually monitor the working state of the fuse. When any single or double bridge arm fails, the fuse on the corresponding fault phase will automatically blow to realize the function of isolating the faulty bridge arm, and thereby determine the faulty bridge arm matrix, thereby determining the working state factor according to the number of faulty bridge arms; finally, the function of modulating the healthy bridge arm is realized by the working state factor.

[0021] Figure 1 A circuit diagram of a multi-state inverter system with adaptive modulation provided by an embodiment of the present invention. Figure 1 , providing an adaptively modulated multi-state inverter system, comprising: a split capacitor 11; four bridge arms, each of which has a pair of complementary power switch groups; an isolation switch group 13, comprising four fuses and six bidirectional thyristors, and a fuse F is connected in series on the output branches of the first bridge arm 121, the second bridge arm 122 and the third bridge arm 123 respectively. a 、F b 、F c Output three-phase voltage, and the three-phase voltage output side shares two auxiliary branches, one auxiliary branch is from the output branch of the fourth bridge arm 124, and a fuse F is connected in series on the output branch x , and then through three bidirectional thyristors TR a1 ,TR b1 ,TR c1 The other auxiliary branch is a DC side feeding branch derived from the midpoint of the split capacitor, and directly passes through three bidirectional thyristors TR a2 ,TR b2 ,TR c2 Connect to the output points of the three-phase voltage respectively.

[0022] For the convenience of technical explanation, in the embodiment of the present invention, the first bridge arm is the A bridge arm, which has power switch groups IGBT1 and IGBT2, the second bridge arm is the B bridge arm, which has power switch groups IGBT3 and IGBT4, the third bridge arm is the C bridge arm, which has power switch groups IGBT5 and IGBT6, and the fourth bridge arm is the X bridge arm, which has power switch groups IGBT7 and IGBT8.

[0023] The adaptively modulated multi-state inverter system can withstand any single or double bridge arm faults. Table 1 is a list of fault types that the adaptively modulated multi-state inverter system can withstand. Referring to Table 1, the embodiment of the present invention mainly includes 36 types of switch tube faults, including not only 6 single switch tube faults and 15 double switch tube faults, but also 12 triple switch tube faults and 3 quadruple switch tube faults.

[0024] Table 1

[0025]

[0026]

[0027] Figure 2 The present invention provides a flow chart of the steps of the modulation method of the multi-state inverter system using adaptive modulation. Figure 2 The present invention also provides a modulation method of a multi-state inverter system using adaptive modulation, comprising the following steps:

[0028] S21, monitoring the working status of the four fuses in the isolating switch group in real time, determining the status factors of the four fuses, and determining the fault bridge arm matrix according to the status factors;

[0029] S22, locating the faulty bridge arm according to the number of faulty bridge arms in the faulty bridge arm matrix, and outputting a working state factor S;

[0030] S23. When the number of faulty bridge arms in the faulty bridge arm matrix is ​​0, S=1; when the number of faulty bridge arms in the faulty bridge arm matrix is ​​1, S=2; when the number of faulty bridge arms in the faulty bridge arm matrix is ​​2, S=3; when the working state factor S≤2, a six-switch fault-tolerant modulation algorithm is adopted; when the working state factor S=3, a four-switch fault-tolerant modulation algorithm is adopted.

[0031] Real-time monitoring of the four fuses F in the disconnector group a 、F b 、F c and F x The working state of the four fuses is determined by the state factor f a 、f b 、f c and f x , and determine the fault bridge arm matrix F = [f a f b f c f x Specifically, when the fuse works normally, its state factor is set to 0, and when the fuse is blown due to overcurrent caused by the faulty bridge arm, its state factor is set to 1.

[0032] No matter which bridge arm in the inverter fails, an overcurrent will be generated, causing the corresponding fuse (F a 、F b 、F c or F x ) will automatically fuse due to the heat generated by itself. This will automatically isolate the faulty bridge arm and protect the entire system from further damage caused by the faulty bridge arm.

[0033] Based on the number of faulty bridge arms in the faulty bridge arm matrix F, the faulty bridge arm can be located, thereby determining the corresponding optimal working state and outputting the working state factor S.

[0034] Table 2 is a fault-tolerant working state classification table. Referring to Table 2, when the number of faulty bridge arms in the faulty bridge arm matrix F is 0, S=1, when the number of faulty bridge arms in the faulty bridge arm matrix F is 1, S=2, and when the number of faulty bridge arms in the faulty bridge arm matrix F is 2, S=3.

[0035] Table 2

[0036] Fault bridge arm matrix F Fault bridge arm Working status factor S [0 0 0 0] none 1 [1 0 0 0] A bridge arm 2 [0 1 0 0] Bridge arm B 2 [0 0 1 0] C bridge arm 2 [1 1 0 0] A&B bridge arm 3 [0 1 1 0] B&C Bridge Arm 3 [1 0 1 0] C&A bridge arm 3 [1 0 0 1] A&X bridge arm 3 [0 1 0 1] B&X Bridge Arm 3 [0 0 1 1] C&X Bridge Arm 3

[0037] When the working state factor S≤2, a six-switch fault-tolerant modulation algorithm is adopted.

[0038] In the space vector modulation algorithm based on sector conversion, no matter the multi-state fault-tolerant inverter is in S=1 or S=1, the six-switch fault-tolerant modulation algorithm can be used. Figure 3 A spatial vector diagram of a multi-state fault-tolerant inverter when S≤2 provided by an embodiment of the present invention. Figure 3 , in the α-β stationary coordinate system, the target voltage that the inverter should output is:

[0039] U ref ∠θ=U α +jU β (1)

[0040] Among them, U α , U β are the components of the target voltage on the α and β axes respectively.

[0041] In the α-β stationary coordinate system, according to the target voltage U ref The phase angle θ of ∠θ can determine the sector N in the three-phase six-switch operation space vector diagram. In addition, by performing a remainder calculation on θ, the target voltage can be converted to the first sector and the following is obtained: Figure 3 The angle θ1 of the first sector is shown.

[0042]

[0043] Figure 4a The switching sequence diagram of the first sector of the multi-state fault-tolerant inverter when S≤2 provided by the embodiment of the present invention is shown in FIG. Figure 4a , assuming that when S=1, the working state of the power switch tube in the I sector is S I =[S AI S BI S CI S XI The specific switch sequence is as follows: Figure 4a Take the seven-segment type shown as an example. When S≤2, the working state S of the power switch tube in the Nth sector N It can be obtained by the following formula:

[0044]

[0045] in,

[0046] Λ a is defined as the fault signal matrix of the six-switch fault-tolerant modulation algorithm under no fault S = 1 or single-arm fault S = 2, and Λ a The element a in ij It depends on the working state of the inverter. When the inverter has no fault S=1, the fault signal a ii =1, a i4 =0, when a single bridge arm fault occurs in the inverter S=2, assuming that when the g-th bridge arm fails, the h-th, k-th and fourth bridge arms are redundant and fault-free bridge arms; the fault signal a gg =a h4 =a k4 =0,a g4 =a hh =a kk =1.

[0047] Calculate the voltage vector action time of the four bridge arms: Assume that when S=1, the conduction time T of the power switch tube in the I sector SI =[T1 T2 T0], where the first vector action time T1, the second vector action time T2, and the zero vector action time T0 are determined by the following formula:

[0048]

[0049] In the case of no fault or single bridge arm fault, the conduction time of the power switch tube in the Nth sector is determined by the following factors:

[0050]

[0051] in,

[0052] The proposed fault-tolerant control algorithm adopts a scheme of directly outputting PWM pulse signals. From the seven-segment switching sequence of the ABCX phase in the I sector of S=1, the seven-segment switching sequence of different sectors under normal and single-arm fault working conditions can be obtained, thus indirectly determining the action order of each voltage vector. Figure 4b The embodiment of the present invention provides a switching sequence diagram of the second sector when the A phase of the multi-state fault-tolerant inverter fails when S≤2. Assume that when a single bridge arm failure occurs in the A phase of the inverter, the working state factor is S=2. Then when the second sector N=II, the switching sequence of the four-bridge arm voltage vector can be calculated by formula (3), as follows: Figure 4b shown.

[0053] When the working state factor S = 3, a four-switch fault-tolerant modulation algorithm is used

[0054] Figure 5 The spatial vector diagram of the multi-state fault-tolerant inverter when S=3 provided by the embodiment of the present invention. Figure 5 , when S = 3, it is necessary to switch to the four-switch fault-tolerant modulation algorithm, regardless of the target voltage U ref ∠θ is located in any sector and can be obtained by Figure 3 S=1 Three-phase six-switch operation space vector diagram Sector I I The relevant parameters are recombined and determined.

[0055] Target voltage U ref The position of ∠θ in the four-switch operation space vector sector:

[0056]

[0057] Definition Figure 5 θ2 is the target voltage U ref The acute angle between ∠θ and the α axis is determined by the following formula:

[0058]

[0059] Calculate the switching sequence of the four bridge arms:

[0060] As above, it is known that S=1 and the working states of the power switch tubes in the Ith sector are S I =[S AI S BI S CI S XI ], and the working state S of the power switch tube of the nth sector when S=3 can be calculated by the following formula n .

[0061]

[0062] in,

[0063] And Λ b As a healthy signal matrix of the four-switch fault-tolerant modulation algorithm, the element b ij and a ij It also depends on the working state of the inverter. When a double bridge arm fault S=3 occurs in the inverter, assuming that only the lth and mth bridge arms are fault-free bridge arms, and m>l, there is a healthy signal b 3l =1,b 4m =1; other elements b ij Then all are 0.

[0064] Calculate the voltage vector action time of the four bridge arms

[0065] Assume that the duration of each switching time of the four bridge arms can be expressed as t sn =[t1 t2 t0], where the first vector action time t1, the second vector action time t2, and the zero vector action time t0 can also be determined by the following formula:

[0066]

[0067] The proposed fault-tolerant control algorithm adopts a scheme of directly outputting PWM pulse signals, which is composed of a seven-segment switching sequence of phases A, B, C, and X in the first sector of S=1 (e.g. Figure 4a As shown in FIG. 1 , the seven-segment switching sequence of different sectors in different working states of the double bridge arm fault S=3 can be obtained, thus indirectly determining the action order of each voltage vector. Figure 6a 1 is a switching sequence diagram of the first sector when the A&B phase of the multi-state fault-tolerant inverter fails when S=3 in an embodiment of the present invention; Figure 6b FIG. 1 is a switching sequence diagram of the second sector when the A&B phase of the multi-state fault-tolerant inverter fails when S=3 in the embodiment of the present invention. Figure 6a And 6b, when the inverter has an A&B double bridge arm fault and is in the S=3 state, the switching sequence of the first sector and the second sector can be obtained according to the above formula.

[0068] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A modulation method for an adaptively modulated multi-state inverter system, characterized in that: A multi-state inverter system for adaptive modulation, the system comprising: Split capacitor (11); Four bridge arms, each of which has a pair of complementary power switch groups, the four bridge arms comprising: a first bridge arm (121), a second bridge arm (122), a third bridge arm (123), and a fourth bridge arm (124); An isolating switch group (13) comprises four fuses and six bidirectional thyristors, wherein the four fuses comprise: a fuse Fa, a fuse Fb, a fuse Fc and a fuse Fx, and the six bidirectional thyristors comprise: a bidirectional thyristor TRa1, a bidirectional thyristor TRb1, a bidirectional thyristor TRc1, a bidirectional thyristor TRa2, a bidirectional thyristor TRb2 and a bidirectional thyristor TRc2; A fuse Fa, a fuse Fb, and a fuse Fc are respectively connected in series on the output branches of the first bridge arm (121), the second bridge arm (122), and the third bridge arm (123) to output a three-phase voltage, and the three-phase voltage output side shares two auxiliary branches, one auxiliary branch is started from the output branch of the fourth bridge arm (124), a fuse Fx is connected in series on the output branch, and then connected to the output point of the three-phase voltage via three bidirectional thyristors TRa1, bidirectional thyristor TRb1, and bidirectional thyristor TRc1 respectively, and the other auxiliary branch is started from the DC side feeding branch derived from the midpoint of the split capacitor (11), and is directly connected to the output point of the three-phase voltage via three bidirectional thyristors TRa2, bidirectional thyristor TRb2, and bidirectional thyristor TRc2 respectively. The method comprises the following steps: Real-time monitoring of the working status of the four fuses in the isolating switch group, determining the status factors of the four fuses, and determining the fault bridge arm matrix according to the status factors; According to the number of faulty bridge arms in the faulty bridge arm matrix, the faulty bridge arm is located and a working state factor S is output; When the number of faulty bridge arms in the faulty bridge arm matrix is ​​0, S=1; when the number of faulty bridge arms in the faulty bridge arm matrix is ​​1, S=2; when the number of faulty bridge arms in the faulty bridge arm matrix is ​​2, S=3; when the working state factor S≤2, a six-switch fault-tolerant modulation algorithm is adopted; when the working state factor S=3, a four-switch fault-tolerant modulation algorithm is adopted; In the α-β stationary coordinate system, the target voltage that the inverter should output is: U ref ∠θ=U α +jU β (1) In the α-β stationary coordinate system, according to the target voltage U ref The amplitude angle θ of ∠θ can determine the sector N in the three-phase six-switch operation space vector diagram. In addition, the remainder calculation of θ is performed, U α、 U β are the components of the target voltage on the α and β axes respectively. The target voltage can be converted to the first sector and θ1 is obtained. θ1 is the angle between the target voltage and the α axis. Calculate the voltage vector action time of the four bridge arms: Assume that when S=1, the conduction time T of the power switch tube in the I sector SI =[T1T2T0], where the first vector action time T1, the second vector action time T2, and the zero vector action time T0 are determined by the following formula: When S=3, it is necessary to switch to the four-switch fault-tolerant modulation algorithm regardless of the target voltage U ref ∠θ is located in any sector, and can be operated by S=1 three-phase six-switch space vector diagram Sector I I The relevant parameters are recombined and determined; The position of the target voltage Uref∠θ in the four-switch operation space vector sector: Define θ2 as the target voltage U ref The acute angle between ∠θ and the α axis is determined by the following formula: Assume that the duration of each switching time of the four bridge arms can be expressed as t sn =[t1 t2 t0], where the first vector action time t1, the second vector action time t2, and the zero vector action time t0 can also be determined by the following formula: The proposed fault-tolerant control algorithm adopts a scheme of directly outputting PWM pulse signals. From the seven-segment switching sequence of phases A, B, C and X in the I sector S=1, the seven-segment switching sequence of different sectors under different working conditions of the double bridge arm fault S=3 can be obtained, thus indirectly determining the action order of each voltage vector.

2. The modulation method of the adaptive modulation multi-state inverter system according to claim 1, characterized in that: When the fuse is working normally, its state factor is set to 0, and when the fuse is blown, its state factor is set to 1.

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