CN109672356B - Active fault-tolerant control method for open-circuit fault of single switching tube of ANPC three-level inverter - Google Patents
Active fault-tolerant control method for open-circuit fault of single switching tube of ANPC three-level inverter Download PDFInfo
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Abstract
The invention relates to an active fault-tolerant control method for an open-circuit fault of a single switching tube of an ANPC three-level inverter, which comprises the following steps of: 1) establishing an ANPC three-level inverter state space model: 2) acquiring a three-phase fault characteristic signal f after the power switch tube has an open-circuit fault according to the topological structure of the ANPC three-level inverter; 3) designing a sliding mode controller according to a three-phase fault characteristic signal f after the power switch tube has an open-circuit fault; 4) and designing an SVPWM fault-tolerant control module, and carrying out active fault-tolerant control on the open-circuit fault of the single switching tube of the ANPC three-level inverter. Compared with the prior art, the method has the advantages of improving dynamic and steady-state performance and robustness, along with quick and accurate fault-tolerant control, easy implementation, convenient application, strong universality and the like.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to an active fault-tolerant control method for an open-circuit fault of a single switching tube of an ANPC three-level inverter.
Background
With the rapid development of power electronic technology in the fields of new energy power generation, high-speed electrified railways and the like in China, the multi-level inverter is widely applied, wherein the ANPC three-level inverter gradually becomes the mainstream of the multi-level inverter due to the advantages of stable performance, more flexible balance control on loss and the like. However, compared with a two-level inverter, the topology structure and the control mode of the inverter are more complex, and the probability of the failure of an internal device is greatly increased; especially for the power switch tube which is most prone to open circuit fault, if the power switch tube cannot be processed in time after the fault occurs, the overall output performance of the system is affected, even the system is broken down, and in severe cases, personal injuries and deaths may be caused. Therefore, the research on the fault-tolerant technology of the ANPC three-level inverter has important practical significance.
At present, a plurality of scholars research the fault-tolerant control of the three-level inverter: the Qiu Shi Guang and Li Si Guang are relatively difficult to accurately position the device fault of the inverter, and a four-bridge-arm fault-tolerant topology of the three-level NPC inverter is provided; scholars such as Zhou Peng Fei and Chen Right use the T-shaped three-level inverter as an object to analyze the fault-tolerant control strategy after the open-circuit fault occurs; the scholars such as Vietnam and Zhangpeng propose a fault-tolerant control strategy under the condition of power device open circuit according to the characteristics of the topological structure of the ANPC three-level converter. The method is mainly passive fault-tolerant control with a fixed and single structure or hardware redundancy control needing additional redundancy equipment, a good control effect is difficult to achieve on an ANPC three-level inverter system with a complex topological structure, the input of redundancy devices is added, the size and the cost of the inverter are further increased, the complexity of the system is improved, and the reliability is reduced.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide an active fault-tolerant control method for the open-circuit fault of a single switching tube of an ANPC three-level inverter.
The purpose of the invention can be realized by the following technical scheme:
an active fault-tolerant control method for an open-circuit fault of a single switching tube of an ANPC three-level inverter comprises the following steps:
1) establishing an ANPC three-level inverter state space model:
2) acquiring a three-phase fault characteristic signal f after the power switch tube has an open-circuit fault according to the topological structure of the ANPC three-level inverter;
3) designing a sliding mode controller according to a three-phase fault characteristic signal f after the power switch tube has an open-circuit fault;
4) and designing an SVPWM fault-tolerant control module, and carrying out active fault-tolerant control on the open-circuit fault of the single switching tube of the ANPC three-level inverter.
In the step 1), the state space model of the ANPC three-level inverter is as follows:
x＝[iaibic]T
u＝[uanubnucn]T
y＝[iaibic]T
A＝diag(-R/L,-R/L,-R/L)
B＝diag(L,L,L)
C＝diag(1,1,1)
f＝[fafbfc]T
wherein x is a system state variable, y is a system output variable, u is a control input quantity, f is a three-phase fault characteristic signal, and fa、fb、fcFault signature for phases a, b, c, ia、ib、icA load current of a, b, c phase, uan、ubn、ucnA, B, C is a coefficient matrix, R is a three-phase load resistor, and L is a three-phase load inductor.
The step 2) is specifically as follows:
obtaining the output voltage difference value of each phase bridge arm of the ANPC three-level inverter before and after the fault, performing Fourier series expansion on the difference value in a fundamental frequency period, removing direct current components, selecting three-phase fundamental frequency components as three-phase fault characteristic signals, and taking a geometric mean value as an amplitude.
The step 3) specifically comprises the following steps:
31) selecting a sliding mode control target as a sliding mode surface s, and then:
s＝i-iref
i＝[iaibic]T
iref＝[iarefibreficref]T
where i is the three-phase load current, irefFor load reference current, iaref、ibref、icrefLoad reference currents of a phase, b phase and c phase respectively;
32) selection of the approximation law of sliding mode indexes
And determining the control input u by combining an ANPC three-level inverter state space model as follows:
u＝-εsgn(s)-qs-f
wherein sgn (·) is a sign function, epsilon and q are sliding mode control parameters, and epsilon is more than 0 and q is more than 0;
33) defining Lyapunov functions
According to accessibility requirements for satisfying sliding mode control
The sliding mode surface change rule is obtained as follows:
the sliding mode control parameter epsilon is adjusted as follows:
the step 4) specifically comprises the following steps:
41) for the control input quantity, a corresponding voltage space vector and the action time thereof are obtained by adopting an SVPWM control method;
42) from the off-line generated fault-tolerant decision knowledge base phidD, obtaining a voltage space vector which can not be normally output in the corresponding fault mode, deleting the voltage space vector in the mapping relation between d, and reconstructing and forming a new voltage space vector on the basis of keeping the output voltage and current to be three-phase symmetrical, wherein d is 0, 1, 2 and … … and corresponds to a normal mode, a fault mode 1, a fault mode 2 and … … respectively, and phidThe SVPWM voltage vector set is an SVPWM voltage vector set which cannot be normally output in a corresponding mode;
43) and for the reconstructed generated voltage space vector, on the basis of keeping the original output state of the fault phase unaffected, reconstructing an SVPWM method, adjusting the voltage space vector sending sequence, adjusting the original seven-segment space vector sending sequence into a five-segment vector sending sequence, and generating a PWM control signal.
In the step 43), the corresponding space vector action time calculation and PWM signal distribution mode are the same as those in normal operation, and are not affected by faults.
The control system for realizing the method comprises the following steps:
a multi-fault-tolerant decision unit module: the method is used for monitoring the running state of the system on line on the basis of a fault-tolerant decision knowledge base established in an off-line manner under normal and various fault modes of the system, outputting fault-tolerant control signals under the corresponding fault modes to a sliding-mode fault-tolerant control module and an SVPWM fault-tolerant control module, and realizing active fault-tolerant control under a multi-fault mode;
a sliding-mode fault-tolerant control module: according to fault characteristic signals under different fault modes, a slip-mode control law is reconstructed by combining a faulted inverter state space model, and output control input quantity is changed in real time to an SVPWM fault-tolerant control module by adjusting various control parameters of a controller;
SVPWM fault-tolerant control module: according to the control input quantity output by the sliding-mode fault-tolerant control module, the voltage space vector is reconstructed by combining the space vector which cannot be normally output after the fault, the original SVPWM control method is reconstructed according to different fault types, the voltage space vector sending sequence is adjusted, and the fault-tolerant PWM control signal is generated, so that the ANPC three-level inverter can still safely operate under the condition that the original output performance or performance is slightly reduced after the open-circuit fault occurs in the switching tube, and the active fault-tolerant control of the system is completed.
Compared with the prior art, the invention has the following advantages:
the invention designs a sliding mode controller with a sliding mode switching item to form a closed loop feedback link of an inverter system, so that the input is tracked and output in real time, and the dynamic and stable performance and robustness of the system are greatly improved.
And secondly, when the inverter has a single switching tube open circuit fault, the control law and the control parameters of the system are adjusted on line, the fault-tolerant control is rapid and accurate, and the operation reliability of the inverter system is improved.
The power devices are limited in quantity and cost increase, high in cost performance, easy to implement, convenient to apply and have certain practical application value.
And fourthly, considering that each power switch tube in the inverter system is likely to have an open-circuit fault, the invention has universality and strong flexibility for the open-circuit fault of each bridge arm single tube.
Drawings
Fig. 1 is a structural diagram of an active fault-tolerant control system of an ANPC three-level inverter.
Fig. 2 is a diagram of a main circuit of the ANPC three-level inverter.
FIG. 3 is Sa1Schematic diagram of current flow paths before and after open circuit fault.
FIG. 4 is Sa1Voltage control signal space vector distribution diagram before and after fault.
FIG. 5 is Sa1And (4) distributing the fault space vector.
FIG. 6 is Sa1And (3) carrying out open-circuit fault-tolerant control on a three-phase load current simulation waveform.
FIG. 7 is Sa1And (3) carrying out open-circuit fault-tolerant control on a three-phase load voltage simulation waveform.
FIG. 8 is Sa1And controlling an input quantity simulation waveform by the open-circuit fault-tolerant control.
FIG. 9 is Sa1And (3) controlling a quadrature axis current output response curve by open-circuit fault tolerance.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments.
Examples
The invention provides an active fault-tolerant control system for an open-circuit fault of a single switching tube of an ANPC three-level inverter based on sliding mode control, the system structure diagram is shown in figure 1, and the system mainly comprises a multi-fault-tolerant decision unit module, a sliding mode fault-tolerant control module and an SVPWM fault-tolerant control module.
The multi-fault-tolerant decision-making unit module monitors the running state of the system on line on the basis of establishing a fault-tolerant decision-making knowledge base under normal and various fault modes of the system in an off-line manner, ensures that the system performs fault-tolerant switching control during fault, outputs a control signal under the corresponding fault mode to act on a unit needing fault-tolerant reconstruction, and realizes an active fault-tolerant control function under the multi-fault mode.
And the sliding mode fault-tolerant control module reconstructs a sliding mode control law according to fault characteristic signals under different fault modes and combines an inverter state space model after the fault, changes output control input quantity in real time by adjusting each control parameter of the controller, and provides a given reference voltage for the adjustment of the SVPWM fault-tolerant control strategy.
The SVPWM fault-tolerant control module reconstructs a voltage space vector by combining a space vector which cannot be normally output after a fault according to the control input quantity output by the sliding-mode fault-tolerant control module, reconstructs an original SVPWM control algorithm aiming at different fault types based on the reconstructed space vector, adjusts the sending sequence of the voltage space vector, generates a fault-tolerant PWM control signal, ensures that the ANPC three-level inverter can still safely run under the condition that the original output performance or the performance is slightly reduced after an open-circuit fault occurs in a switching tube, and completes the active fault-tolerant control of the system.
The control method according to the active fault-tolerant control system comprises the following steps:
(1) establishing an ANPC three-level inverter state space model:
an ANPC three-level inverter system with inductive load is shown in fig. 2, in which each phase bridge arm includes six power switching tubes Sx1～Sx6Six diodes VD connected in anti-parallel with itx1～VDx6(x ═ a, b, c), load resistance, and inductance.
The three-phase output equation can be obtained as follows:
in the formula uxn(x ═ a, b, c) represents load voltage of each phase, ix(x ═ a, b, c) represents the load current of each phase.
When the power switch tube IGBT of a certain phase bridge arm in the ANPC three-level inverter has open-circuit fault, the working state of the system is directly changed, thereby influencing the influenceThree-phase load voltage u of inverterxn(x ═ a, b, c), and if a three-phase fault characteristic signal f (t) ═ f is introduced in a certain fault modeafbfc]TDefining the state variable x as a vector formed by three-phase load current, the control input u as a vector formed by three-phase load voltage, and R ═ Ra＝Rb＝Rc，L＝La＝Lb＝LcThe state space model under the fault of the ANPC three-level inverter can be obtained as follows:
wherein x ═ iaibic]T，u＝[uanubnucn]TThe system output variable y ═ iaibic]TThe coefficient matrix A, B, C may be expressed as a ═ diag (-R/L ), B ═ diag (L, L), and C ═ diag (1,1,1), respectively.
(2) And extracting a three-phase fault characteristic signal f (t) after the power switch tube of the ANPC has an open-circuit fault according to the topological structure of the ANPC three-level inverter.
When the power switching tube of the single-phase bridge arm of the ANPC three-level inverter has an open-circuit fault, the actual value of the output voltage of the fault phase is different from the expected value:
Δuxo＝u′xo-uxo(x＝a,b,c) (3)
in the formula uxo(x ═ a, b, c) denotes the output voltage of each phase arm of the pre-fault inverter, u'xoAnd (x ═ a, b and c) represents the output voltage of each phase arm of the inverter after the fault.
And the output voltage difference of the non-fault phase before and after the fault is 0.
According to the obtained three-phase bridge arm output voltage difference, the difference between the three-phase load voltage after the fault and the three-phase load voltage before the fault is further obtained as follows:
within a fundamental frequency period, the difference signal delta u before and after the load voltage faultxnAll the periodic functions are subjected to Fourier series expansion, direct-current components are removed according to parity of the periodic functions, three-phase fundamental frequency components are selected as three-phase fault characteristic signals, geometric mean values are used as amplitudes of the three-phase fault characteristic signals, and three-phase fault characteristic signal expressions f are obtaineda(t)、fb(t)、fc(t)。
(3) In order to enable the ANPC three-level inverter system to be stably switched to a new stable state operation as soon as possible after a fault occurs and avoid the system being in an out-of-control state, based on the three-phase fault characteristic signal f (t) obtained in the step (2), a fault-tolerant reconstruction design needs to be performed on the sliding mode controller, and the fault-tolerant reconstruction method specifically comprises the following substeps:
(301) selecting a sliding mode control target as a sliding mode surface according to a design principle of a sliding mode controller:
s＝i-iref(5)
wherein i ═ iaibic]TIs a three-phase load current iref＝[iarefibreficref]TIs a three-phase load reference current.
(302) Selection of approximation law of sliding mode index
In the formula, sgn (-) is a sign function, sliding mode control parameters epsilon > 0 and q > 0 are combined with an ANPC three-level inverter state space model, so that a sliding mode control signal (control law) is determined as follows:
u＝-εsgn(s)-qs-f (6)
(303) defining Lyapunov functions
According to accessibility requirements for satisfying sliding mode control
The obtained sliding mode surface change law is as follows:
thus, the sliding-mode control parameters ε and q may be adjusted to:
(4) according to the control input quantity u obtained in the step (3), further designing an SVPWM fault-tolerant control module, and specifically comprising the following substeps:
(401) and aiming at the control input quantity output by the sliding mode fault-tolerant controller, a basic SVPWM control algorithm is adopted to determine a corresponding voltage space vector and the acting time thereof.
(402) Analyzing phi in an offline generated fault-tolerant decision knowledge basedD, determining a voltage space vector which cannot be normally output in the fault mode, and deleting the voltage space vector in the space vector generated in the step 1; and reconstructing and forming a new voltage space vector on the basis of keeping the three-phase symmetry of the output voltage and current.
(403) And aiming at the reconstructed generated voltage space vector, on the basis of keeping the original output state of the fault phase unaffected, reconstructing the original SVPWM algorithm, adjusting the voltage space vector sending sequence, adjusting the original seven-segment space vector sending sequence into a five-segment vector sending sequence, and generating a PWM control signal. The corresponding space vector action time calculation and PWM signal distribution mode are the same as those in normal work and are not affected by faults.
(5) A-phase bridge arm outer pipe S of ANPC three-level invertera1The open circuit fault is analyzed for an actual case, and the effectiveness of the method is explained.
(501) Setting the resistance-inductance load R to be 15 omega and the L to be 33mH, and establishing a state space model of the ANPC three-level inverter under the fault condition:
wherein, A is diag (-15/0.033, -15/0.033, -15/0.033), B is diag (0.033,0.033,0.033), and C is diag (1,1, 1).
(502) Extraction of Sa1And (c) generating a three-phase fault characteristic signal f (t) after the open fault occurs.
When S is shown in FIG. 3a1When an open-circuit fault occurs, a current path from the inverter to the load shown by a dotted line in the figure is cut off; due to S at this timea6In the on state, the current forces the freewheeling diode VDa3And the current path shown by a solid line in the figure is formed by conduction, so that the output end is at zero level, namely the switching state of the a-phase bridge arm is changed from P to O after the fault. Therefore, the inverter fault phase a-phase bridge arm output voltage u'aoAnd before fault uaoThe difference of (d) is:
Δuao＝u′ao-uao＝-Ud/2 (9)
and the difference value of the output voltages of the non-fault phases (b and c) before and after the fault is as follows:
the difference between the three-phase load voltage after the fault and before the fault is:
within one fundamental frequency period, Δ uxn(x ═ a, b, c) is a periodic function, and can be expressed approximately as:
wherein n is a non-negative integer and T is a fundamental frequency period.
For the difference signal delta u before and after the a-phase load voltage faultanPerforming Fourier series expansion, and obtaining the following result after neglecting direct current components according to the parity of the Fourier series expansion:
b. the phase c calculation process is similar. Selecting three phasesThe fundamental frequency component being the three-phase fault signature and the geometric mean being the amplitude thereof, i.e.
Three-phase fault characteristic signal fa(t)、fb(t)、fc(t) is expressed as:
(503) and designing fault-tolerant reconstruction of the sliding mode controller based on the fault characteristic signal. In order to simplify the design of the sliding mode controller, all parameters of the sliding mode controller are calculated by transforming an abc three-phase coordinate system into a dq coordinate system.
(5031) Constructing a slip form surface:
(5032) and (3) control law reconstruction:
selecting a sliding mode index approach law, and determining a sliding mode control signal (control law) as follows:
(5033) according to a defined Lyapunov function
Meeting accessibility requirement of sliding mode control
On the premise of obtaining the sliding mode surface change law as follows:
the sliding mode control parameters epsilon and q can thus be adjusted to:
(504) based on the voltage control signal ud、uqAnd further designing the SVPWM fault-tolerant control module.
And (3) carrying out coordinate transformation on the three-phase fault characteristic signals, and obtaining the fault characteristic signals under the dq coordinate system as follows:
therefore, three-phase output voltage control signals of the sliding mode controller after the fault are respectively as follows:
the above equation is the voltage control signal output to the SVPWM fault-tolerant controller. After the signal is converted from dq coordinate system to abc three-phase coordinate system, the amplitude of the three-phase input reference voltage of the SVPWM fault-tolerant controller is reduced after the fault
Therefore, when the SVPWM controller performs modulation based on this, S shown in fig. 4 can be obtaineda1The voltage control signal space vector distribution diagram before and after the fault, wherein the excircle of the dotted line is the track of the control input quantity before the fault in the vector space, and the inner circle of the solid line is the track of the control input quantity after the fault in the vector space; on the other hand, Sa1After an open circuit fault occurs, the fault-tolerant decision knowledge base is analyzed, so that 9 vectors including zero vector PPP, small vector PPO, POO, POP, medium vector PON, PNO and large vector PPN, PNN and PNP cannot be normally output, and the distribution change of the space vectors at the moment is shown in fig. 5. In order to ensure that the fundamental wave of the output voltage is still a sinusoidal signal after fault-tolerant control, the following can be obtained according to a vector reconstruction control strategy: after reconstruction, the voltage space vector can only be distributed in a small hexagonal area, namely the inverter needs derating operation, and the better output performance can be ensured.
After the voltage space vector is reconstructed based on the two parts, the sending sequence of the voltage space vector is adjusted, the SVPWM control algorithm is reconstructed, and the reconstructed sending sequence is shown in table 1.
TABLE 1Sa1Open-circuit fault-tolerant operation vector sending sequence table
Fig. 6-8 are output waveform diagrams of active fault-tolerant control of open-circuit fault of an a-phase outer bridge arm power switch tube of an ANPC three-level inverter system built under MATLAB/Simulink environment. As can be seen from FIGS. 6-8, when S occurs in the systema1After an open circuit fault occurs, the output waveform is distorted, and the system gradually enters a new stable state after the adjustment of less than half of a fundamental frequency period under the action of a sliding mode fault-tolerant controller and an SVPWM fault-tolerant controller; it can be further seen that, when the system switches from normal operation to fault-tolerant operation, the amplitudes of the output voltage and current signals of the system are both reduced to 1/2, and the phase is kept unchanged. The inverter is subjected to derating operation under the action of an active fault-tolerant control strategy, so that three-phase symmetry of output signals is kept, the fault-tolerant control purpose is achieved, and the result is consistent with the theoretical analysis. Fig. 9 is a quadrature axis current output response curve after fault-tolerant control is performed on the system, and the corresponding calculation results of the dynamic and steady-state response indexes are shown in table 2.
TABLE 2Sa1Fault-tolerant control dynamic and steady state response index under open circuit fault
| Type of failure | Output signal | Rise time(s) | Regulating time(s) | Steady state error |
| Sa1Open circuit fault | Quadrature axis load current | 0.0016 | 0.0029 | 2.8％ |
As can be seen from fig. 9 and table 2, after the system reconstructs the sliding-mode control law and adjusts the controller parameters, the system output current can be quickly switched to the new steady-state current, and the error between the steady-state response and the expected response of the system during the steady-state operation stage is kept within a small range, so that the system has better stability. The active fault-tolerant control strategy provided by the invention has a simple principle, does not depend on other hardware, can well meet the high-performance requirement, and has good practicability.
Through the adjustment of the sliding mode control law, the control parameters and the SVPWM vector sending sequence, the S-level control method and the S-level control system are ensureda1The output characteristic under the fault well realizes the active fault-tolerant control function.
The active fault-tolerant control of the invention processes the fault by changing the parameters of the controller or adjusting the structure of the controller on the basis of not increasing redundant hardware, has stronger fault-tolerant capability and fault-tolerant control capability on unknown faults, and ensures the stability of the system after the fault occurs, thereby having good practicability.
Claims (5)
1. An active fault-tolerant control method for an open-circuit fault of a single switching tube of an ANPC three-level inverter is characterized by comprising the following steps:
1) establishing an ANPC three-level inverter state space model:
2) according to the topological structure of the ANPC three-level inverter, acquiring a three-phase fault characteristic signal f after an open-circuit fault occurs to a power switch tube, specifically:
acquiring output voltage difference values of bridge arms of each phase of the ANPC three-level inverter before and after a fault, performing Fourier series expansion on the difference values in a fundamental frequency period, removing direct-current components, selecting three-phase fundamental frequency components as three-phase fault characteristic signals, and taking a geometric mean value as an amplitude;
3) the sliding mode controller is designed according to a three-phase fault characteristic signal f after the power switch tube has an open-circuit fault, and specifically comprises the following steps:
31) selecting a sliding mode control target as a sliding mode surface s, and then:
s＝i-iref
i＝[iaibic]T
iref＝[iarefibreficref]T
where i is the three-phase load current, ia、ib、icA load current of a, b, c phase, irefFor load reference current, iaref、ibref、icrefLoad reference currents of a phase, b phase and c phase respectively;
32) selection of the approximation law of sliding mode indexes
And determining the control input u by combining an ANPC three-level inverter state space model as follows:
u＝-εsgn(s)-qs-f
wherein sgn (·) is a sign function, epsilon and q are sliding mode control parameters, and epsilon is more than 0 and q is more than 0;
33) defining Lyapunov functions
According to accessibility requirements for satisfying sliding mode control
The sliding mode surface change rule is obtained as follows:
the sliding mode control parameter epsilon is adjusted as follows:
wherein, R is a three-phase load resistor, and L is a three-phase load inductor;
4) and designing an SVPWM fault-tolerant control module, and carrying out active fault-tolerant control on the open-circuit fault of the single switching tube of the ANPC three-level inverter.
2. The active fault-tolerant control method for the open-circuit fault of the single switching tube of the ANPC three-level inverter as claimed in claim 1, wherein in the step 1), the state space model of the ANPC three-level inverter is as follows:
x＝[iaibic]T
u＝[uanubnucn]T
y＝[iaibic]T
A＝diag(-R/L,-R/L,-R/L)
B＝diag(L,L,L)
C＝diag(1,1,1)
f＝[fafbfc]T
wherein x is a system state variable, y is a system output variable, u is a control input quantity, f is a three-phase fault characteristic signal, and fa、fb、fcIs a fault signature of a, b, c phases, uan、ubn、ucnA, B, C is a coefficient matrix for the load voltages of the phases a, b, and c.
3. The active fault-tolerant control method for the open-circuit fault of the single switching tube of the ANPC three-level inverter according to claim 1, wherein the step 4) specifically comprises the following steps:
41) for the control input quantity, a corresponding voltage space vector and the action time thereof are obtained by adopting an SVPWM control method;
42) according to the working mode d in the fault-tolerant decision knowledge base generated off-line and the SVPWM voltage vector set phi which can not be normally output under the corresponding modedThe mapping relation between the voltage space vectors is obtained, the voltage space vectors which cannot be normally output under the corresponding fault mode are deleted in the voltage space vectors, and the new voltage space vectors are reconstructed and formed on the basis that the output voltage and current are still three-phase symmetrical;
43) and for the reconstructed generated voltage space vector, on the basis of keeping the original output state of the fault phase unaffected, reconstructing an SVPWM method, adjusting the voltage space vector sending sequence, adjusting the original seven-segment space vector sending sequence into a five-segment vector sending sequence, and generating a PWM control signal.
4. The active fault-tolerant control method for the open-circuit fault of the single switching tube of the ANPC three-level inverter as claimed in claim 3, wherein in the step 43), the calculation of the corresponding space vector action time and the distribution mode of the PWM signal are the same as those in normal operation and are not affected by the fault.
5. The active fault-tolerant control method for the open-circuit fault of the single switching tube of the ANPC three-level inverter according to any one of claims 1 to 4, wherein a control system for realizing the method comprises:
a multi-fault-tolerant decision unit module: the method is used for monitoring the running state of the system on line on the basis of a fault-tolerant decision knowledge base established in an off-line manner under normal and various fault modes of the system, outputting fault-tolerant control signals under the corresponding fault modes to a sliding-mode fault-tolerant control module and an SVPWM fault-tolerant control module, and realizing active fault-tolerant control under a multi-fault mode;
a sliding-mode fault-tolerant control module: according to fault characteristic signals under different fault modes, a slip-mode control law is reconstructed by combining a faulted inverter state space model, and output control input quantity is changed in real time to an SVPWM fault-tolerant control module by adjusting various control parameters of a controller;
SVPWM fault-tolerant control module: according to the control input quantity output by the sliding-mode fault-tolerant control module, the voltage space vector is reconstructed by combining the space vector which cannot be normally output after the fault, the original SVPWM control method is reconstructed according to different fault types, the voltage space vector sending sequence is adjusted, and the fault-tolerant PWM control signal is generated, so that the ANPC three-level inverter can still safely operate under the condition that the original output performance or performance is slightly reduced after the open-circuit fault occurs in the switching tube, and the active fault-tolerant control of the system is completed.
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