CN117914213A - Direct torque control method for single-phase open-circuit fault tolerance of double three-phase motor - Google Patents
Direct torque control method for single-phase open-circuit fault tolerance of double three-phase motor Download PDFInfo
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Abstract
The invention discloses a direct torque control method for fault tolerance of a single-phase open circuit fault of a double three-phase motor, which comprises the following steps: the method comprises the steps of utilizing multistage hysteresis loops, simultaneously considering positive and negative and amplitude values of torque and flux linkage, selecting different voltage vector combinations to carry out voltage modulation of an alpha-beta plane and an x-y harmonic plane in dynamic and steady states, carrying out fault-tolerant operation aiming at single-phase open-circuit faults of a double three-phase permanent magnet synchronous motor, correcting voltage modulation of the x-y harmonic plane and the alpha-beta plane, and realizing direct torque control of the multistage hysteresis loops of the double three-phase permanent magnet synchronous motor. The invention considers the positive and negative and amplitude values of the torque and the flux linkage, respectively selects different voltage vector combinations in dynamic and steady states to perform voltage vector synthesis, further reduces torque pulsation, is applied to single-phase open-circuit fault working conditions of direct torque control, adopts a full-dimensional model after fault to perform fault-tolerant operation, modifies a current reference value after motor fault, does not need to change a controller, and has simple structure and small torque pulsation.
Description
Technical Field
The invention belongs to the field of drive control of double three-phase motors, and particularly relates to a direct torque control method for single-phase open-circuit fault tolerance of a double three-phase motor.
Background
The double three-phase permanent magnet synchronous motor has good fault tolerance capability, and the main current mode of fault processing mostly adopts the mode of converting faults into open-phase faults and performing fault tolerance control to be converted into open-phase operation, so that the fault tolerance control strategy of the double three-phase motor is mainly concentrated on motor open-phase operation research.
Currently, the control of a double three-phase PMSM motor generally utilizes space decoupling transformation, and all variables of the double three-phase motor are mapped to an alpha-beta plane, an x-y plane and an o1-o2 plane through static coordinate transformation (1) according to a vector space decoupling theory. The alpha-beta subplane participates in electromechanical energy conversion, the x-y plane is a harmonic plane, 5 and 7 times harmonic currents are mapped to the plane, the plane is restrained to be 0 in normal control, the o1-o2 subplane is a zero sequence subplane, and variables in the o1-o2 subplane are all zero under the condition that neutral points are mutually isolated.
Thus, the motor control can be performed by controlling the physical quantities of the alpha-beta plane, the x-y plane and the o1-o2 plane, and further controlling the physical quantities of the respective phases. The three sub-planes are decoupled from each other during normal operation.
The defects of the existing direct torque fault-tolerant control strategy of the double three-phase permanent magnet synchronous motor are that:
The fault-tolerant control of direct torque of the double three-phase permanent magnet synchronous motor needs to establish a dimensionality reduction mathematical model after faults, and different motor models are required to be established for different faults, so that the fault-tolerant control is complex. And the controller needs to be switched before and after the fault, so that the control is not simple enough.
Most of the current fault tolerance strategies based on direct torque control are based on virtual voltage vectors, and the direct torque control strategies based on the virtual voltage vectors eliminate the influence of inverter voltage output on an x-y harmonic plane, but cannot restrain harmonic currents caused by counter electromotive force, dead time, external interference and other factors.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a direct torque control method for fault tolerance of a single-phase open circuit fault of a double three-phase motor, which considers the positive and negative values and the amplitude values of torque and flux linkage, respectively selects different voltage vector combinations in dynamic and steady states to perform voltage vector synthesis, further reduces torque pulsation, is applied to the working condition of the single-phase open circuit fault of direct torque control, adopts a full-dimensional model for fault tolerance operation after the fault, modifies a current reference value after the motor fault, does not need to change a controller, and has simple structure and small torque pulsation.
In order to achieve the above object, the present invention provides the following solutions:
A direct torque control method for single-phase open-circuit fault tolerance of a double three-phase motor comprises the following steps:
the method comprises the steps of utilizing multistage hysteresis loops, simultaneously considering positive and negative and amplitude values of torque and flux linkage, selecting different voltage vector combinations to carry out voltage modulation of an alpha-beta plane and an x-y harmonic plane in dynamic and steady states, carrying out fault-tolerant operation aiming at single-phase open-circuit faults of a double three-phase permanent magnet synchronous motor, correcting voltage modulation of the x-y harmonic plane and the alpha-beta plane, and realizing direct torque control of the multistage hysteresis loops of the double three-phase permanent magnet synchronous motor.
Preferably, the method of voltage modulation of the α - β plane and the x-y harmonic plane comprises:
and modulating the x-y harmonic plane voltage and the alpha-beta plane voltage, performing multistage hysteresis loop control by using a flux linkage observer to observe flux linkage and torque of the motor, calculating errors of the flux linkage and the torque, and selecting a voltage vector according to error values of the flux linkage and the torque.
Preferably, the method for selecting different combinations of voltage vectors includes:
And selecting 3 adjacent voltage vectors as a voltage vector group, wherein the voltage vector group comprises 2 adjacent D4 vectors and 1D 2 vector, and synthesizing an output voltage.
Preferably, a flux linkage observer based on stator flux linkage as a state variable is designed by using a model reference self-adaptive method to identify the flux linkage of the motor for closed-loop control of the flux linkage.
Preferably, the method for designing the flux linkage observer based on the stator flux linkage as a state variable to perform the closed-loop control of the flux linkage by using the model reference adaptive method comprises the following steps:
Constructing a reference model and an adjustable model of flux linkage by using a basic principle of model reference adaptive control to observe the flux linkage of the motor;
defining an error vector, and making a difference between the reference model and the adjustable model;
according to the stability theory, a transfer function of a forward path is obtained;
substituting the difference between the reference model and the adjustable model into the transfer function to obtain an estimated flux linkage;
And obtaining an estimated stator current by using the estimated flux linkage, and forming a closed-loop feedback link by making a difference with the actual value of the motor current, thereby realizing closed-loop control of the flux linkage.
Preferably, the reference model is:
In the method, in the process of the invention, U' q＝uq,Rs represents the stator resistance, ω e is the electrical angular frequency, L d and L q are the d, q axis stator direct axis inductances and quadrature axis inductances ψ d、ψq are the d, q axis stator flux linkages, and u d、uq is the d, q axis stator voltages, respectively;
the adjustable model is as follows:
estimated value of d and q axis stator flux linkage respectively,/> Is an electrical rotational speed estimate.
Preferably, the method for performing fault-tolerant operation on the single-phase open circuit fault of the double three-phase permanent magnet synchronous motor comprises the following steps:
after the double three-phase permanent magnet synchronous motor has single-phase open circuit fault, a full-dimensional model after the double three-phase permanent magnet synchronous motor has fault is utilized, fault-tolerant current in a corresponding minimum copper loss or maximum torque mode is selected according to the position of phase failure, the fault-tolerant current is added to a harmonic plane current reference value, and a PR controller is utilized to track the harmonic current reference value, so that single-phase open circuit fault-tolerant operation is realized.
Preferably, the transfer function of a proportional resonance PR controller in the discrete domain can be expressed as:
Wherein the parameters are as follows:
k pr is the resonant gain; omega c is the cut-off frequency; omega 0 is the resonant frequency; t s is the stator torque.
Compared with the prior art, the invention has the beneficial effects that:
The invention mainly aims at the problems that a controller needs to be replaced before and after a fault exists in fault-tolerant control by adopting a dimension reduction model in the fault-tolerant operation of the double three-phase permanent magnet synchronous motor and the suppression effect on torque pulsation is limited, and provides direct torque control of the double three-phase permanent magnet synchronous motor in the fault-tolerant operation based on a full dimension model.
Firstly, the controller needs to be changed before and after the fault of the dimension reduction algorithm, and the proposed algorithm can realize single-phase open-circuit fault tolerant operation only by changing the current reference value after the fault;
Secondly, fault tolerance of the dimension reduction model is based on virtual voltage vectors, the virtual voltage vectors are of equal amplitude, the reduction ratio of torque pulsation is limited, voltage vector correction is carried out on the basis, fault tolerance is carried out, and the suppression effect on harmonic waves is limited; the algorithm is based on multistage hysteresis control, and voltage vector groups are selected based on dynamic state and steady state respectively, so that voltage vectors with required amplitude values can be synthesized more finely, voltage can be synthesized more finely according to positive and negative magnetic linkage torque and amplitude values to control, and harmonic suppression effect is better.
And thirdly, a flux linkage observer based on a model reference self-adaption method is adopted to realize accurate identification of the flux linkage of the motor, and closed-loop control of the flux linkage of the motor is carried out.
Drawings
In order to more clearly illustrate the technical solutions of the present invention, the drawings that are needed in the embodiments are briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic diagram of the topology of a stator winding and a current transformer of the present invention;
FIG. 2 is a space voltage vector diagram of a dual three-phase two-level voltage source converter in an embodiment of the invention; wherein (a) is an alpha-beta plane double three-phase two-level voltage source type converter space voltage vector diagram; (b) The space voltage vector diagram of the voltage source type converter with two three phases and two levels in the x-y plane is shown;
FIG. 3 is a block diagram of a direct torque control fault tolerant operation control based on a multi-stage hysteresis in an embodiment of the present invention;
FIG. 4 is a schematic diagram illustrating selection of a set of voltage vectors according to the present invention; wherein (a) is a schematic drawing of selection of an alpha-beta plane voltage vector group; (b) selecting a schematic diagram for the x-y plane voltage vector group;
FIG. 5 is a schematic flow chart of a method for synthesizing reference voltage vectors in the x-y plane in an embodiment of the invention;
FIG. 6 is a schematic view of a synthetic x-y plane zero vector in an embodiment of the invention; wherein (a) is an alpha-beta plane zero vector schematic; (b) is an x-y plane zero vector schematic;
FIG. 7 is a schematic diagram of selection and time of action calculation of v 0 vector sets in an embodiment of the present invention;
FIG. 8 is a flow chart of a multi-level hysteresis based ST-DTC fault tolerant operation in an embodiment of the invention;
FIG. 9 is a forward block diagram of a MARS-based observer system in accordance with an embodiment of the present invention;
FIG. 10 is a block diagram of a flux linkage observer in an embodiment of the invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
Example 1
As shown in fig. 1, the object of the present invention is a double neutral point phase shifted 30 ° double three phase permanent magnet synchronous motor (DT-PMSM), the stator windings are powered by two store voltage source type inverters, and the two sets of neutral points are isolated from each other. The invention mainly carries out fault-tolerant control when one-phase open circuit fault occurs when direct torque control is adopted for double three-phase PMSM.
The invention provides a fault-tolerant control strategy based on normal decoupling transformation, which keeps a decoupling transformation matrix of a system unchanged, voltage equations, flux linkage equations and torque equations not affected, only needs to modify harmonic subspace reference currents, analyzes calculation of voltage vectors synthesized into different plane reference values after single-phase open-circuit faults of a double-three-phase motor, considers the influence of harmonic plane voltage modulation on alpha-beta voltage modulation after faults, and corrects voltage modulation during faults to adapt to fault-tolerant working conditions. The direct torque control based on the multistage hysteresis takes the positive and negative values and the amplitude values of the torque flux linkage into consideration, so that the degree of the system needing to increase and decrease the torque or flux linkage can be described in more detail, and a more proper voltage vector combination is selected for direct torque control, so that the torque pulsation can be further reduced.
The motor spatial decoupling matrix can be expressed as:
The voltage of a double three-phase permanent magnet synchronous motor can be expressed as:
Wherein R s represents the stator resistance; stator voltage u s＝uα+juβ,uz＝ux+juy; stator current i s＝iα+jiβ,iz＝ix+jiy; stator flux linkage ψ s＝ψα+jψβ,ψz＝ψx+jψy.
The flux linkage of a double three-phase permanent magnet synchronous motor can be expressed as:
Wherein: l s＝3Lm+Lz;Lm and L z are stator winding self inductance and leakage inductance respectively; phi f is the magnitude of the rotor flux linkage; θ e is the electrical angle of the rotor position;
The electromagnetic torque of the motor can be expressed as:
Te＝3np(is×ψs) (4)
n p is the pole pair number of the motor.
Mapping the voltage vector to two orthogonal sub-planes of alpha-beta and x-y by using a formula (5), setting a switching function of the six-phase inverter as S= [ S A SB SC SD SE SF ], taking the phase A as an example, and if S A = 1, indicating that a switch on a bridge arm of the phase A of the inverter is conducted; s A =0 indicates that the phase a bridge arm lower switch is on. The six-bit switch corresponds to 64 voltage vectors, wherein the six-bit switch comprises 60 effective vectors and 4 zero vectors, the six-bit switch can be divided into four groups according to the voltage vector amplitude, and the four groups are respectively a large vector D 4, a medium vector D 3, a medium vector D 2 and a small vector D 1, and the amplitudes are respectively />The mapping relation between the alpha-beta plane and the x-y plane is shown in fig. 2 (a) and (b), and the amplitude corresponding relation is shown in the amplitude of the voltage vector of the double three-phase permanent magnet synchronous motor in table 1.
TABLE 1
The invention selects voltage vector combination to perform multistage hysteresis control, simultaneously considers positive and negative and amplitude values of flux linkage and torque, selects an optimal voltage vector group to perform voltage modulation, performs direct torque control of multistage hysteresis, performs fault-tolerant operation aiming at single-phase open faults of the double three-phase permanent magnet synchronous motor, and corrects the voltage modulation of an x-y harmonic plane and an alpha-beta plane.
The control strategy block diagram proposed by the present invention is shown in fig. 3, and the subscript "ref" represents the reference value.
W e is the motor electrical speed, T e is the electromagnetic torque, e represents the error, T A-TF is the vector on-time duty cycle, i A-iF is the stator current, i s is the stator current, and i z is the harmonic current. v c and v o are the active vector set and the zero vector set, respectively.
Where ε ψ＝ψs,ref-ψs,εT＝Te,ref-Te+ωeψs, deltaT is the hysteresis width of the torque control. And reasonably selecting the hysteresis width delta T according to working conditions such as rotating speed, torque and the like to perform hysteresis control.
The harmonic plane adopts a Proportional Resonance (PR) controller to control the harmonic plane current to realize the static-difference-free adjustment of the harmonic current iz. During normal operation, harmonic plane current should be suppressed to 0, and during faults, 5 and 7 times harmonic current is suppressed, and given fault tolerant operation reference current is tracked.
The transfer function of the PR controller in the discrete domain can be expressed as:
Wherein the parameters are as follows:
k pr is the resonant gain; omega c is the cut-off frequency; omega 0 is the resonant frequency. Increasing k pr can increase the controller amplitude-frequency gain, and increasing ω c can increase the controller bandwidth.
PR controllers with resonant frequency omega e(ωe as electric angular frequency), 5 omega e and 7 omega e are connected in parallel to be used as x-y plane current controllers, and closed loop control is adopted to restrain 5 th and 7 th current harmonics and track fundamental frequency current reference values.
To achieve planar linear voltage modulation, adjacent 3 voltage vectors are selected as a voltage vector group, comprising 2 adjacent D4 vectors and 1D 2 vector, to synthesize the output voltage, as shown by (a), (b) black (bolded) vectors in fig. 4. Vector combinations are denoted by v c, and a total of 12 such vector combinations, vector combinations and their positions in the x-y plane are shown in table 2v c1 vector sets and positions.
TABLE 2
After the double three-phase PMSM has single-phase open-circuit fault, the current reference value of the harmonic plane is modified according to the principle of maximum torque or minimum copper loss to carry out fault tolerance. As shown in table 3 for open-phase fault locations and corresponding current constraints.
TABLE 3 Table 3
And selecting a fault-tolerant current in a corresponding minimum copper loss or maximum torque mode according to the phase failure position, adding the fault-tolerant current to a harmonic plane current reference value, and tracking the harmonic current reference value by using a PR controller. Taking F phase as an example, the x-y harmonic plane current reference value when the minimum copper loss mode is adopted is as follows:
ix,ref＝0,iy,ref＝-iβ (9)
when the maximum torque mode is adopted, the current reference value is as follows:
ix,ref＝-iα,iy,ref＝-iβ (10)
And modulating harmonic plane voltage and alpha-beta plane voltage, performing multistage hysteresis loop control by using a flux linkage observer to observe flux linkage and torque of the motor, selecting a current observer for the flux linkage observer, calculating errors of the flux linkage and the torque, and selecting a voltage vector according to the two error values.
According to formulas (6) and (7), setting the current hysteresis width delta T, selecting the most suitable voltage vector according to the flux linkage error and the torque error, wherein v c and v o are an active vector group and a zero vector group respectively, lambda epsilon [0,1] is an adjusting coefficient, and a vector selection switching table is shown in a table 4ST-DTC switching table.
TABLE 4 Table 4
When e T is not equal to 0, v c vector sets are selected, 2 adjacent D 4 vectors and 1D 2 vector are selected to synthesize output voltage, as shown in fig. 4, corresponding voltage vector sets are selected according to flux linkage and torque error, as shown in table 3, and then 3 selected voltage vectors are used to synthesize a required voltage vector.
The reference value of the harmonic voltage before the fault is 0, namely u z,ref =0, after the single-phase open circuit fault occurs, the reference value of the harmonic current after the fault is modified, the corresponding harmonic reference voltage u z,ref is generated through the PR controller, and u z,ref is synthesized by two adjacent vectors at the position of the harmonic voltage in the selected three voltages, as shown in fig. 5.
When the motor operates normally, u z,ref =0, and only the alpha-beta plane reference voltage vector needs to be synthesized. And synthesizing an x-y plane harmonic voltage reference value u z,ref when the motor has a single-phase open circuit fault, as shown in a formula (11).
vc1Tc1,1+vc2Tc2,1+vc3Tc3,1＝uz,ref (11)
According to the correspondence of the voltage vectors shown in fig. 4, the voltage vectors generated by the synthesized x-y plane harmonic voltage vectors in the α - β plane are:
vc1Tc1,1+vc2Tc2,1+vc3Tc3,1＝uαβ,1 (12)
The harmonic voltage after the fault is relatively large, the influence of the synthesized x-y plane harmonic voltage on the alpha-beta plane is needed to be considered when the alpha-beta plane voltage reference value is synthesized, and the voltage vector needed to be synthesized is corrected:
u′αβ,ref＝uαB,ref-uαβ,1 (13)
Then, according to the mapping relation of the voltage vectors, the corrected alpha-beta plane reference voltage u' αβ,ref is synthesized by using the residual time, and the voltage vectors of the synthesized voltage mapped on the x-y plane are zero, as shown in (a) and (b) in fig. 6, which can be expressed as:
vc1Tc1,2+vc2Tc2,2+vc3Tc3,2＝u′αβ,ref (14)
this gives a total time of action of 3 vectors in one cycle, which can be expressed as:
choosing a smaller lambda can reduce the torque ripple without affecting the voltage modulation of the harmonic plane, but lambda cannot be reduced indefinitely.
When e T =0, since the conventional zero vector v 0 cannot modulate the x-y harmonic plane voltage, cannot modulate the harmonic plane voltage after the fault well, and cannot effectively suppress the harmonic current, the present invention provides a new vector selection scheme to replace the conventional zero vector as shown in fig. 7.
The D1 vectors have the smallest amplitude in the α - β plane and the largest amplitude in the x-y plane, and the adjacent 2D 1 vectors in the x-y plane differ by 150 ° in the x-y plane, and these two vectors have similar effects on the harmonic plane, but have smaller effects on the α - β plane, and the selection of such two vectors as the vector group is denoted as v o,v0 and there are 12 groups as shown in fig. 7. The selection and synthesis of the voltage vectors are the same as above, and the synthesis of the x-y harmonic plane reference voltage is also performed to realize motor control in steady state, as shown in formula (16).
vo1To1+vo2To2＝uz,ref (16)
The six-dimensional switch column vector is denoted v k＝[SA SB SC SD SE SF]T, such that the vector on time is:
T6P＝Tc1vc1+Tc2vc2+Tc3vc3 (17)
Or:
T6P＝To1vo1+To2vo2 (18)
Wherein T 6P＝[TA TB TC TD TE TF]T.
The switching signals of the VSC six-phase bridge arm can be obtained by comparing T 6P with the triangular carrier through a Pulse Width Modulation (PWM) module, as shown in fig. 8.
And observing the flux linkage of the motor by using a flux linkage observer of a model reference adaptive Method (MARS) to carry out closed-loop control of the flux linkage.
According to the voltage equation (3), the voltage equation is converted into an equation under a d-q coordinate system and written into a matrix form to be expressed as:
Wherein the subscript letters represent the parameters of the variables in their corresponding planes.
Similarly, it is rewritten as follows according to flux linkage equation (4):
Wherein, L d and L q are d, q axis stator direct axis inductance and quadrature axis inductance respectively, L aal is leakage self-inductance of each phase stator winding, and is permanent magnet flux linkage amplitude.
And constructing a reference model and an adjustable model of the flux linkage by using a basic principle of model reference adaptive control to observe the flux linkage of the motor. Therefore, the stator flux linkage in the d-q coordinate system is selected as a state variable, and the reference model can be expressed as follows:
In the method, in the process of the invention, U' q＝uq,ψd、ψq is the d and q axis stator flux linkage, and u d、uq is the d and q axis stator voltages, respectively.
The flux linkage and the rotating speed in the formula (22) are replaced by estimated values, and an adjustable model of the MARS is obtained, which can be expressed as follows:
In the method, in the process of the invention, Estimated value of d and q axis stator flux linkage respectively,/>Is an electrical rotational speed estimate.
Defining error vectorsThe reference model and the adjustable model are subjected to difference to obtain:
The above is abbreviated as:
In the method, in the process of the invention,
According to the stability theory, the system stability is fully conditioned by the fact that the forward path is a strictly positive real transfer function matrix. The system architecture is shown in fig. 9, and the transfer function of the forward path can be expressed as:
H(s)＝(sI-A)-1I (25)
the result of the input calculation is:
The characteristic equation is as follows:
Solving the poles of the method can obtain:
from equation (10), the poles of H(s) are all located on the left half plane of s, the system is stable, and H (jω) +H * (jω) > 0 can be demonstrated. From the stability theory, it is known that the system H(s) is strictly positive, i.e., the system is stable and converged.
The estimated flux linkage is used to obtain the estimated stator current, and the estimated stator current and the actual value of the motor current are differenced to form a closed loop feedback link, and the structure diagram of the flux linkage observer is shown in fig. 10.
G is the feedback matrix, which corresponds to observer open loop when g=0. Reasonable value of G ensures stability, and the value of general feedback gain can be:
G＝Rs (29)
According to the stability theory, when the current estimated value converges to the current actual value, the adjustable model tends to the reference model, and the estimated flux linkage can be considered to be equal to the actual motor flux linkage, so that the observed flux linkage can be obtained for fault-tolerant operation of direct torque control.
The above embodiments are merely illustrative of the preferred embodiments of the present invention, and the scope of the present invention is not limited thereto, but various modifications and improvements made by those skilled in the art to which the present invention pertains are made without departing from the spirit of the present invention, and all modifications and improvements fall within the scope of the present invention as defined in the appended claims.
Claims (8)
1. The direct torque control method for single-phase open-circuit fault tolerance of the double three-phase motor is characterized by comprising the following steps of:
the method comprises the steps of utilizing multistage hysteresis loops, simultaneously considering positive and negative and amplitude values of torque and flux linkage, selecting different voltage vector combinations to carry out voltage modulation of an alpha-beta plane and an x-y harmonic plane in dynamic and steady states, carrying out fault-tolerant operation aiming at single-phase open-circuit faults of a double three-phase permanent magnet synchronous motor, correcting voltage modulation of the x-y harmonic plane and the alpha-beta plane, and realizing direct torque control of the multistage hysteresis loops of the double three-phase permanent magnet synchronous motor.
2. The direct torque control method for single phase open circuit fault tolerance of a double three phase motor according to claim 1, wherein the method for voltage modulation of the α - β plane and the x-y harmonic plane comprises:
and modulating the x-y harmonic plane voltage and the alpha-beta plane voltage, performing multistage hysteresis loop control by using a flux linkage observer to observe flux linkage and torque of the motor, calculating errors of the flux linkage and the torque, and selecting a voltage vector according to error values of the flux linkage and the torque.
3. The direct torque control method for fault tolerance of a single phase open circuit fault of a double three phase motor according to claim 2, wherein the method for selecting different combinations of voltage vectors comprises:
And selecting 3 adjacent voltage vectors as a voltage vector group, wherein the voltage vector group comprises 2 adjacent D4 vectors and 1D 2 vector, and synthesizing an output voltage.
4. The direct torque control method for single-phase open-circuit fault tolerance of a double three-phase motor according to claim 2, wherein a flux linkage observer based on stator flux linkage as a state variable is designed by using a model reference adaptive method to perform closed-loop control of flux linkage of the motor.
5. The direct torque control method for single-phase open-circuit fault tolerance of a double three-phase motor according to claim 4, wherein the method for closed-loop control of flux linkage of a motor by using a model reference adaptive method to design flux linkage observer identification motor based on stator flux linkage as a state variable comprises:
Constructing a reference model and an adjustable model of flux linkage by using a basic principle of model reference adaptive control to observe the flux linkage of the motor;
defining an error vector, and making a difference between the reference model and the adjustable model;
according to the stability theory, a transfer function of a forward path is obtained;
substituting the difference between the reference model and the adjustable model into the transfer function to obtain an estimated flux linkage;
And obtaining an estimated stator current by using the estimated flux linkage, and forming a closed-loop feedback link by making a difference with the actual value of the motor current, thereby realizing closed-loop control of the flux linkage.
6. The method for direct torque control for single phase open circuit fault tolerance of a dual three phase motor of claim 5,
The reference model is as follows:
In the method, in the process of the invention, U' q＝uq,Rs represents the stator resistance, ω e is the electrical angular frequency, and L d and L q are the d-axis and q-axis stator direct-axis inductances and quadrature-axis inductances, respectively; psi d、ψq is the d and q axis stator flux linkage, u d、uq is the d and q axis stator voltage, respectively;
the adjustable model is as follows:
estimated value of d and q axis stator flux linkage respectively,/> Is an electrical rotational speed estimate.
7. The direct torque control method for single-phase open-circuit fault tolerance of a double three-phase motor according to claim 1, wherein the method for fault-tolerant operation of single-phase open-circuit faults of a double three-phase permanent magnet synchronous motor comprises:
after the double three-phase permanent magnet synchronous motor has single-phase open circuit fault, a full-dimensional model after the double three-phase permanent magnet synchronous motor has fault is utilized, fault-tolerant current in a corresponding minimum copper loss or maximum torque mode is selected according to the position of phase failure, the fault-tolerant current is added to a harmonic plane current reference value, and a PR controller is utilized to track the harmonic current reference value, so that single-phase open circuit fault-tolerant operation is realized.
8. The direct torque control method for fault tolerance of a single phase open circuit fault of a double three phase motor according to claim 7, wherein the transfer function of a proportional resonance PR controller in a discrete domain can be expressed as:
Wherein the parameters are as follows:
k pr is the resonant gain; omega c is the cut-off frequency; omega 0 is the resonant frequency; t s is the stator torque.
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