Aviation three-level motor predictive starting control method based on cascade coupling structure

Abstract

The invention discloses an aviation three-level motor prediction starting control method based on a cascade coupling structure. The method comprises the following steps: constructing a rotor current observer and a stator current prediction model of an exciter; obtaining rotor end voltage, flux linkage and current information of the exciter at the current moment, and predicting stator current of the exciter at the next moment; obtaining a rotor excitation current value of the main motor at the current moment and a rotor excitation current predicted value of the main motor at the next moment according to an electromagnetic coupling relationship between the main motor and the exciter; obtaining a stator current predicted value of the main motor at the next moment according to the mathematical model of the main motor; by designing an excitation control cost function and a main motor control cost function, predictive control is performed on an exciter and a main motor. Thus, coupling between the main motor and the exciter is considered through observer construction, and the problem that an existing model prediction control method cannot be directly applied is solved.

Description

Technical Field

[0001] The present application relates to the technical field of AC motor control, and in particular to an aviation three-stage motor predictive starting control method based on a cascade coupling structure. Background Art

[0002] As a key technology of More Electric Aircraft (MEA), the core idea of ​​integrated starter / generator technology is to use the reversible principle of the motor. Compared with the traditional starting method, the integrated starter / generator technology eliminates the traditional dedicated starter and allows the onboard generator to run in the motor mode to start the engine. After the start is completed, the onboard generator switches to the power generation mode to power the onboard electrical equipment. The integrated starter / generator technology simplifies the engine's accessory casing and air bleed device, reduces the "dead weight" of the aircraft, and improves the aircraft's reliability, maintainability and energy efficiency.

[0003] The three-stage starting / generating integrated technology is developed on the basis of the three-stage generating technology. The existing three-stage generating system usually consists of a coaxially mounted main motor, an exciter, an auxiliary exciter and a rotating rectifier. Since the auxiliary exciter can only provide excitation current to the exciter when the system is rotating, it does not participate in the starting process. In addition, the exciter of the three-stage motor in the generating mode is a DC excitation mode. When the system is stationary or running at a low speed, even if the stator winding of the exciter is supplied with DC power through an external power supply, the main motor still cannot run electrically. Therefore, the excitation problem of the main motor in the zero low-speed stage is the key to realizing the three-stage starting / generating integrated function.

[0004] The active excitation control scheme with the exciter inverter has the advantages of high excitation regulation efficiency and good flexibility. The adjustment is flexible, and the structure can truly realize the coordinated optimization control of the main motor and the exciter. In recent years, the model predictive control method has received high attention in the field of AC motor control. This method has the advantages of good dynamic characteristics and simple operation. However, due to the special motor cascade coupling structure of the three-stage motor and the inability to directly measure the signal on the rotor side, the traditional model predictive control method cannot be directly used in the starting coordinated control of the three-stage motor. The model predictive control method that simplifies the main motor into a permanent magnet motor cannot consider the coupling between motors, so it cannot truly realize the excitation current control. Summary of the invention

[0005] The embodiment of the present application provides an aviation three-stage motor predictive starting control method based on a cascade coupling structure, which is constructed by an observer to consider the coupling between the main motor and the exciter, thereby solving the problem that the existing model predictive control method cannot be directly applied.

[0006] In order to achieve the above object, the technical solution of the embodiment of the present invention is:

[0007] In the first aspect, an embodiment of the present invention provides an aviation three-stage motor predictive starting control method based on a cascade coupling structure, comprising: respectively obtaining the three-phase currents of the stators of the three-stage main motor and the exciter in a three-phase stationary coordinate system; constructing a rotor current observer of the exciter according to the three-phase current of the stator of the exciter and the mathematical model of the exciter, and obtaining the rotor current observation value of the exciter at the current moment; according to a preset first vector transformation strategy, converting the three-phase current of the stator of the exciter to a two-phase stationary coordinate system, thereby constructing a stator current prediction model of the exciter, and predicting the stator current of the exciter at the next moment after the current moment; according to a preset second vector transformation strategy, converting the predicted value of the stator current of the exciter at the next moment to a three-phase stationary coordinate system, and constructing a rotor excitation current prediction model of the main motor according to the electromagnetic coupling relationship between the main motor and the exciter, and obtaining the rotor excitation current prediction value of the main motor at the next moment; according to a preset third A vector transformation strategy is adopted to convert the three-phase stator current of the main motor into a two-phase rotating coordinate system to obtain the stator current of the main motor in the two-phase rotating coordinate system at the current moment; a stator current prediction model of the main motor is constructed according to the stator current of the main motor in the two-phase rotating coordinate system at the current moment and the mathematical model of the main motor to obtain the stator current prediction value of the main motor at the next moment; an excitation control cost function of the exciter inverter is designed according to the predicted value of the rotor excitation current of the main motor at the next moment; and a main motor control cost function of the main motor inverter is designed according to the predicted value of the stator current of the main motor at the next moment; a first optimal voltage vector of the exciter inverter is predicted according to the excitation control cost function, and the exciter inverter is driven by the first optimal voltage vector to perform predictive control on the exciter; a second optimal voltage vector of the main motor inverter is predicted according to the main motor control cost function, and the main motor inverter is driven by the second optimal voltage vector to perform predictive control on the main motor.

[0008] In some possible implementations, a rotor current observer of the exciter is constructed according to the three-phase stator current of the exciter and the mathematical model of the exciter to obtain the rotor current observation value of the exciter at the current moment, including:

[0009] The rotor current observer of the exciter is constructed according to the stator voltage, stator flux equation and rotor current characteristics of the exciter;

[0010] Among them, the stator voltage of the exciter is expressed as:

[0011]

[0012] The stator flux equation of the exciter is expressed as:

[0013]

[0014] The rotor current characteristics of the exciter include:

[0015] i ra +i rb +i rc =0;

[0016] Among them, u A ,u B and u C is the voltage at the three-phase winding terminals of the exciter stator, i sA ,i sB and i sC is the three-phase current of the exciter stator, i ra ,i rb and i rc is the three-phase current of the exciter rotor, and is the three-phase flux linkage of the exciter stator, R se is the phase resistance of the stator winding of the exciter, L se is the total self-inductance of the stator winding of the exciter, M sr is the mutual inductance amplitude of the stator and rotor windings of the exciter, θ r is the exciter rotor position;

[0017] According to the rotor current observer of the exciter, the exciter rotor current estimation expression in the three-phase stationary coordinate system is determined. The exciter rotor current estimation expression is expressed as:

[0018]

[0019] Among them, A1 is the calculation factor of phase C, and A2 is the calculation factor of phase B;

[0020] According to the exciter rotor current estimation expression, the observed value of the exciter rotor current at the current moment is determined.

[0021] In some possible implementations, a stator current prediction model of the exciter is constructed to predict the stator current of the exciter at the next moment from the current moment, including:

[0022] Based on the mathematical equation of the exciter, the rotor flux and rotor terminal voltage of the exciter at the current moment are observed in a two-phase stationary coordinate system;

[0023] Among them, the rotor flux of the exciter is expressed as:

[0024]

[0025] The rotor terminal voltage of the exciter is expressed as:

[0026]

[0027] in, is the rotor flux of the exciter, L r is the exciter rotor winding self-inductance, i s is the stator current of the exciter, L m is the mutual inductance of the exciter rotor winding, i r is the exciter rotor current; V r is the rotor terminal voltage of the exciter, R r is the phase resistance of the exciter rotor winding, is the differential operator, j is the imaginary unit, w is the rotor electrical angular velocity, and k represents the current moment;

[0028] According to the stator current expression of the exciter and forward Euler discretization, the stator current prediction model of the exciter is constructed, and the current prediction value of the exciter stator at the next moment is obtained through the stator current prediction model of the exciter; wherein, the stator current prediction model of the exciter is expressed as:

[0029]

[0030] Among them, k+1 represents the next moment of the current moment, i s (k+1) is the predicted value of the stator current of the exciter at the next moment from the current moment, T s is the sampling time of the system, k r is the magnetic coupling factor, R σ is the equivalent resistance, σ is the magnetic leakage coefficient, τ r is the rotor time constant, τ σ is the instantaneous time constant, V s is the stator terminal voltage of the exciter.

[0031] In some possible implementations, a rotor excitation current prediction model of the main motor is constructed according to the electromagnetic coupling relationship between the main motor and the exciter to obtain a predicted value of the rotor excitation current of the main motor at the next moment, including:

[0032] The electromagnetic coupling relationship is expressed as:

[0033] |i ra |+|i rb |+|i rc |=2i f ;

[0034] Among them, i f Is the main motor rotor excitation current value;

[0035] According to the electromagnetic coupling relationship and the observation results of the exciter rotor current observer, the rotor excitation current value of the main motor at the current moment is obtained, which is expressed as:

[0036]

[0037] Among them, i f (k) is the rotor excitation current value of the main motor at the current moment, i ra (k), i rb (k), i rc (k) are the three-phase current observation values ​​of the exciter rotor at the current moment;

[0038] According to the exciter rotor current observer and the predicted value of the stator current of the exciter at the next moment, the rotor current of the exciter at the next moment is predicted;

[0039] According to the electromagnetic coupling relationship and the predicted value of the rotor current of the exciter at the next moment, the predicted value of the rotor excitation current of the main motor at the next moment is determined; the predicted value of the rotor excitation current of the main motor at the next moment is expressed as:

[0040]

[0041] Among them, i f (k+1) is the predicted value of the main motor rotor excitation current at the next moment from the current moment, i ra (k+1), i rb (k+1), i rc (k+1) are the predicted three-phase current values ​​of the exciter rotor at the next moment.

[0042] In some possible implementations, a stator current prediction model of the main motor is constructed according to the stator current of the main motor in the two-phase rotating coordinate system at the current moment and the mathematical model of the main motor, and a stator current prediction value of the main motor at the next moment is obtained, including:

[0043] According to the electrically excited synchronous motor model, the voltage and flux equations of the main motor are established;

[0044] Among them, the voltage equation of the main motor is expressed as:

[0045]

[0046] Among them, u d is the stator d-axis voltage of the main motor, u q is the q-axis voltage of the main motor stator, u f is the main motor rotor excitation winding voltage, R sm is the stator resistance of the main motor, R f is the resistance value of the main motor rotor excitation winding, i dis the stator d-axis current of the main motor, i q is the q-axis current of the main motor stator, i f is the main motor rotor excitation current, is the stator d-axis flux of the main motor, is the q-axis magnetic flux of the main motor stator, is the main motor rotor excitation flux, w e is the electrical angular velocity of the main motor;

[0047] The flux equation of the main motor is expressed as:

[0048]

[0049] Among them, L d The equivalent inductance of the stator winding d axis of the main motor, L q is the q-axis equivalent inductance of the main motor stator winding, L md is the mutual inductance between the d-axis equivalent inductance of the stator winding of the main motor and the rotor winding, L f The self-inductance of the main motor excitation winding;

[0050] Apply the forward Euler discretization formula to the voltage equation of the main motor to obtain the predicted value of the stator current of the main motor at the next moment, which is expressed as:

[0051]

[0052] Among them, i d (k+1) is the stator d-axis current of the main motor at time k+1, i q (k+1) is the stator q-axis current of the main motor at time k+1.

[0053] In some possible implementations, the excitation control cost function in the constant excitation control mode is expressed as:

[0054]

[0055] The main motor control cost function is expressed as:

[0056]

[0057] Among them, g e is the excitation control cost function, g m is the main motor control cost function, As the main motor rotor excitation current reference, For the main motor d-axis current reference, It is the reference of the q-axis current of the main motor.

[0058] In some possible implementations, predicting a first optimal voltage vector of an exciter inverter according to an excitation control cost function includes:

[0059] Evaluating multiple switch vector states of the exciter inverter through an excitation control cost function, and determining a first optimal voltage vector from voltage vectors corresponding to the multiple switch vector states;

[0060] According to the main motor control cost function, a second optimal voltage vector of the main motor inverter is predicted, including:

[0061] A plurality of switch vector states of the main motor inverter are evaluated by using a main motor control cost function, and a second optimal voltage vector is determined from voltage vectors corresponding to the plurality of switch vector states.

[0062] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0063] An embodiment of the present invention provides an aviation three-stage motor predictive starting control method based on a cascade coupling structure. The method is constructed through an observer to consider the coupling between the main motor and the exciter, fully considers the cascade coupling structure of the three-stage motor, and realizes the model predictive collaborative starting control of the excitation current and the main motor, thereby making up for the technical problem that the traditional model predictive control method cannot be directly used for the collaborative starting control of the three-stage motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] In order to more clearly illustrate the embodiments of the present invention, the accompanying drawings required for use in the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0065] Figure 1 It is a schematic diagram of the typical three-stage power generation system structure;

[0066] Figure 2 It is a structural diagram of an existing three-stage motor starting control system based on a three-phase active excitation structure;

[0067] Figure 3 A schematic flow chart of an embodiment of a predictive start control method for an aviation three-stage motor based on a cascade coupling structure provided for the implementation of the present invention;

[0068] Figure 4 A schematic diagram of a predictive start control method for an aviation three-stage motor based on a cascade coupling structure provided by an embodiment of the present invention;

[0069] Figure 5 Schematic diagram of the structure of a three-phase two-level excitation inverter in an embodiment of the present invention. DETAILED DESCRIPTION

[0070] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0071] In the relevant description of this embodiment, the terms "including, containing, having" and the like are open terms and are generally understood to include but not be limited to; the term "at least one" is generally understood to mean one or more, where "plurality" refers to two or more; the term "at least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items, for example, "at least one of a, b or c", or "at least one of a, b and c", can all represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple, respectively; the symbol "A / B" is used to describe the selection relationship of associated objects, generally indicating an "or" relationship before and after.

[0072] In the following description of the present embodiment, the terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0073] Those skilled in the art should understand that in the following description of the embodiments of the present application, the order of serial numbers does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0074] Those skilled in the art will appreciate that the numerical ranges in the embodiments of the present application are to be construed as also specifically disclosing each intermediate value between the upper and lower limits of the scope. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the range is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded in the scope.

[0075] Unless otherwise specified, the technical / scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which this application belongs. Although this application only describes preferred methods and materials, any methods and materials similar or equivalent to these may also be used in the implementation or testing of this application. All documents mentioned in this specification are incorporated by reference to disclose and describe methods and / or materials related to the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0076] In order to illustrate the technical solution of the present invention, specific embodiments are provided below for illustration.

[0077] As a key technology of More Electric Aircraft (MEA), the core idea of ​​integrated starter / generator technology is to use the reversible principle of the motor. Compared with the traditional starting method, the integrated starter / generator technology eliminates the traditional dedicated starter and allows the onboard generator to run in the motor mode to start the engine. After the start is completed, the onboard generator switches to the power generation mode to power the onboard electrical equipment. The integrated starter / generator technology simplifies the engine's accessory casing and air bleed device, reduces the "dead weight" of the aircraft, and improves the aircraft's reliability, maintainability and energy efficiency.

[0078] The three-stage starter / generator integrated technology is developed on the basis of the three-stage generator technology. Figure 1 The figure is a typical schematic diagram of the structure of a three-stage power generation system, which consists of a coaxially mounted main motor, an exciter, an auxiliary exciter, and a rotating rectifier. Since the auxiliary exciter can only provide excitation current to the exciter when the system is rotating, it does not participate in the starting process. In addition, the exciter of the three-stage motor in the power generation mode is a DC excitation mode. When the system is stationary or running at a low speed, even if the stator winding of the exciter is supplied with DC power through an external power supply, the main motor still cannot run electrically. Therefore, the excitation problem of the main motor in the zero low-speed stage is the key to realizing the three-stage starting / generation integration function.

[0079] The active excitation control scheme with the exciter inverter has the advantages of high excitation regulation efficiency and good flexibility. The structure can truly realize the coordinated optimization control of the main motor and the exciter. Figure 2 As shown, Figure 2 It is a structural diagram of an existing three-stage motor starting control system based on a three-phase active excitation structure.

[0080] In recent years, the model predictive control method has received much attention in the field of AC motor control. This method has the advantages of good dynamic characteristics and simple operation. However, due to the special motor cascade coupling structure of the three-stage motor and the inability to directly measure the signal on the rotor side, the traditional model predictive control method cannot be directly used in the starting cooperative control of the three-stage motor. The model predictive control method that simplifies the main motor into a permanent magnet motor cannot consider the coupling between motors, so it cannot truly realize the excitation current control.

[0081] Based on this, an embodiment of the present invention provides an aviation three-stage motor predictive starting control method based on a cascade coupling structure, which is constructed through an observer to consider the coupling between the main motor and the exciter, thereby solving the problem that the existing model predictive control method cannot be directly applied.

[0082] Figure 3 A schematic diagram of an embodiment of a three-stage aviation motor predictive starting control method based on a cascade coupling structure provided for the implementation of the present invention is shown in FIG. Figure 3 As shown, the above method may include:

[0083] S301, respectively obtaining three-phase currents of the stators of the three-stage main motor and the exciter in a three-phase stationary coordinate system;

[0084] The three-phase current in the three-phase stationary coordinate system (ie, the abc coordinate system) can be measured by any existing sensor or monitoring equipment.

[0085] S302, constructing a rotor current observer of the exciter according to the three-phase stator current of the exciter and the mathematical model of the exciter, and obtaining the rotor current observation value of the exciter at the current moment;

[0086] In some embodiments, the above step S302 may include:

[0087] The rotor current observer of the exciter is constructed according to the stator voltage, stator flux equation and rotor current characteristics of the exciter;

[0088] In the embodiment of the present invention, the stator voltage of the exciter can be expressed as:

[0089]

[0090] The stator flux equation of the exciter can be expressed as:

[0091]

[0092] The rotor current characteristic of the exciter can be expressed as:

[0093] i ra +i rb +irc =0;

[0094] Among them, u A ,u B and u C is the voltage at the three-phase winding terminals of the exciter stator, i sA ,i sB and i sC is the three-phase current of the exciter stator, i ra ,i rb and i rc is the three-phase current of the exciter rotor, and is the three-phase flux linkage of the exciter stator, R se is the phase resistance of the stator winding of the exciter, L se is the total self-inductance of the stator winding of the exciter, M sr is the mutual inductance amplitude of the stator and rotor windings of the exciter, θ r is the exciter rotor position;

[0095] Based on the rotor current observer constructed in the above steps, the rotor current estimation expression of the exciter in the three-phase stationary coordinate system is further determined;

[0096] For example, the exciter rotor current estimation expression can be expressed as:

[0097]

[0098] Among them, A1 is the calculation factor of phase C, and A2 is the calculation factor of phase B;

[0099] After the exciter's rotor current estimation expression is determined, the exciter's rotor current value can be calculated based on the expression, thereby determining the exciter's rotor current observation value at the current moment.

[0100] S303, according to the preset first vector transformation strategy, the three-phase stator current of the exciter is converted into a two-phase stationary coordinate system, so as to construct a stator current prediction model, and predict the stator current of the exciter at the next moment after the current moment;

[0101] In some embodiments, the vector transformation strategy may be a specific mathematical formula or algorithm such as Clarke transformation. Taking Clarke transformation as an example, the three-phase current can be directly transformed from the abc coordinate system to a two-phase stationary coordinate system (or a two-phase rotating coordinate system) through Clarke transformation. The specific methods of the above-mentioned first vector transformation strategy and the subsequent second vector transformation measurement and the third vector transformation strategy can be selected according to actual needs. It is only necessary to complete the transformation of the coordinate system. The embodiment of the present invention does not impose specific restrictions on this. By performing coordinate transformation, the stator current can be represented and analyzed in a simpler way, which is convenient for further control and processing.

[0102] Specifically, the above step S303 may include:

[0103] Based on the mathematical equation of the exciter, the rotor flux and the rotor terminal voltage of the exciter at the current moment are observed in a two-phase stationary coordinate system;

[0104] In some embodiments, the rotor flux of the exciter can be expressed as:

[0105]

[0106] The rotor terminal voltage of the exciter can be expressed as:

[0107]

[0108] in, is the rotor flux of the exciter, L r is the exciter rotor winding self-inductance, i s is the stator current of the exciter, L m is the mutual inductance of the exciter rotor winding, i r is the exciter rotor current; V r is the rotor terminal voltage of the exciter, R r is the phase resistance of the exciter rotor winding, is the differential operator, j is the imaginary unit, w is the rotor electrical angular velocity, and k represents the current moment;

[0109] Furthermore, according to the stator current expression of the exciter and the forward Euler discretization method, a stator current prediction model of the exciter can be further constructed.

[0110] By predicting the stator current value of the exciter through the constructed exciter stator current prediction model, the current prediction value of the exciter stator at the next moment of the current moment can be obtained;

[0111] In some embodiments, the exciter stator current prediction model can be expressed as:

[0112]

[0113] Among them, k+1 represents the next moment of the current moment, i s (k+1) is the predicted value of the stator current of the exciter at the next moment from the current moment, T s is the sampling time of the system, k r is the magnetic coupling factor, R σ is the equivalent resistance, σ is the magnetic leakage coefficient, τ r is the rotor time constant, τ σ is the instantaneous time constant, V s is the stator terminal voltage of the exciter.

[0114] S304, according to the preset second vector transformation strategy, the predicted value of the stator current of the exciter at the next moment is converted to the three-phase stationary coordinate system, and according to the electromagnetic coupling relationship between the main motor and the exciter, a rotor excitation current prediction model of the main motor is constructed to obtain the predicted value of the rotor excitation current of the main motor at the next moment;

[0115] In some embodiments, the electromagnetic coupling relationship between the main motor and the exciter can be expressed as:

[0116] |i ra |+|i rb |+|i rc |=2i f ;

[0117] Among them, i f It is the main motor rotor excitation current value.

[0118] Based on the same concept, the exciter rotor current value at the current moment obtained by the exciter rotor current observer can be used to obtain the rotor excitation current value of the main motor at the current moment, which can be expressed by the following formula:

[0119]

[0120] Among them, i f (k) is the rotor excitation current value of the main motor at the current moment, i ra (k), i rb (k), i rc (k) are the three-phase current observation values ​​of the exciter rotor at the current moment;

[0121] According to the exciter rotor current observer and the predicted value of the stator current of the exciter at the next moment, the rotor current of the exciter at the next moment is predicted;

[0122] Determine the predicted value of the rotor excitation current of the main motor at the next moment according to the electromagnetic coupling relationship and the predicted value of the rotor current of the exciter at the next moment;

[0123] Exemplarily, the predicted value of the rotor excitation current of the main motor rotor at the next moment can be expressed as:

[0124]

[0125] Among them, i f (k+1) is the predicted value of the main motor rotor excitation current at the next moment from the current moment, i ra (k+1), i rb (k+1), i rc (k+1) are the predicted three-phase current values ​​of the exciter rotor at the next moment.

[0126] S305, according to a preset third vector transformation strategy, convert the stator three-phase current of the main motor into a two-phase rotating coordinate system to obtain the stator current of the main motor in the two-phase rotating coordinate system at the current moment;

[0127] S306, constructing a stator current prediction model of the main motor according to the stator current of the main motor in the two-phase rotating coordinate system at the current moment and the mathematical model of the main motor, and obtaining a stator current prediction value of the main motor at the next moment;

[0128] The mathematical model of the main motor usually includes voltage equations, flux equations, torque equations, and mechanical motion equations. For stator current prediction, the voltage equation and flux equation are the main focus because they are the basis of current changes. Therefore, in an embodiment of the present invention, the stator current prediction model of the main motor may include the voltage and flux equations of the main motor.

[0129] In some embodiments, the voltage equation of the main motor can be expressed as:

[0130]

[0131] Among them, u d is the stator d-axis voltage of the main motor, u q is the q-axis voltage of the main motor stator, u f is the main motor rotor excitation winding voltage, R sm is the stator resistance of the main motor, R f is the resistance value of the main motor rotor excitation winding, i d is the stator d-axis current of the main motor, i q is the q-axis current of the main motor stator, i f is the main motor rotor excitation current, is the stator d-axis flux of the main motor, is the q-axis magnetic flux of the main motor stator, is the main motor rotor excitation flux, w e The electrical angular velocity of the main motor;

[0132] The flux equation of the main motor can be expressed as:

[0133]

[0134] Among them, L d The equivalent inductance of the stator winding d axis of the main motor, L q is the q-axis equivalent inductance of the main motor stator winding, L md is the mutual inductance between the d-axis equivalent inductance of the stator winding of the main motor and the rotor winding, L f The self-inductance of the main motor excitation winding;

[0135] After that, the forward Euler discretization formula can be applied to the voltage equation of the main motor to obtain the predicted value of the stator current of the main motor at the next moment, which can be expressed as:

[0136]

[0137] Among them, i d (k+1) is the stator d-axis current of the main motor at time k+1, i q (k+1) is the stator q-axis current of the main motor at time k+1.

[0138] S307, designing an excitation control cost function of the exciter inverter according to the predicted value of the rotor current of the main motor at the next moment; and designing a main motor control cost function of the main motor inverter according to the predicted value of the stator current of the main motor at the next moment;

[0139] In some embodiments, the excitation control cost function in the constant excitation control mode can be expressed as:

[0140]

[0141] Among them, the constant excitation control mode refers to a control method that keeps the magnitude and direction of the excitation current unchanged for a period of time to maintain stable operation of the equipment. In the constant excitation control mode, the excitation control system will automatically adjust the magnitude of the excitation current according to the operating status of the equipment and the preset control target to keep the equipment running stably under rated conditions. Specifically, when the equipment load changes, the excitation control system will detect and respond to these changes, and adjust the excitation current to keep the equipment's output voltage, current or power factor and other parameters stable.

[0142] The main motor control cost function can be expressed as:

[0143]

[0144] Among them, ge is the excitation control cost function, g m is the main motor control cost function, As the main motor rotor excitation current reference, For the main motor d-axis current reference, It is the reference of the q-axis current of the main motor.

[0145] S308, predicting the first optimal voltage vector of the exciter inverter according to the excitation control cost function, and driving the exciter inverter by the first optimal voltage vector to perform predictive control of the exciter; predicting the second optimal voltage vector of the main motor inverter according to the main motor control cost function, and driving the main motor inverter by the second optimal voltage vector to perform predictive control of the main motor.

[0146] The first optimal voltage vector of the exciter inverter is predicted according to the excitation control cost function, including:

[0147] Evaluating multiple switch vector states of the exciter inverter through an excitation control cost function, and determining a first optimal voltage vector from voltage vectors corresponding to the multiple switch vector states;

[0148] According to the main motor control cost function, a second optimal voltage vector of the main motor inverter is predicted, including:

[0149] A plurality of switch vector states of the main motor inverter are evaluated by using a main motor control cost function, and a second optimal voltage vector is determined from voltage vectors corresponding to the plurality of switch vector states.

[0150] A predictive starting control method for an aviation three-stage motor based on a cascade coupling structure provided by an embodiment of the present invention fully considers the cascade coupling structure of the three-stage motor, realizes model predictive collaborative starting control of the excitation current and the main motor, and makes up for the technical problem that the traditional model predictive control method cannot be directly used for the collaborative starting control of the three-stage motor.

[0151] The method provided by the embodiment of the present invention is described below with a specific embodiment.

[0152] Figure 4 The schematic diagram of a three-stage aviation motor predictive starting control method based on a cascade coupling structure provided by an embodiment of the present invention. Figure 4As shown, by collecting the stator current information of the exciter and the stator current of the main motor respectively, the three-phase current in the corresponding three-phase stationary coordinate system is obtained; the three-phase current of the stator of the exciter is converted to the two-phase stationary coordinate system by coordinate transformation, and the stator current of the exciter in the two-phase stationary coordinate system is obtained, and the rotor flux and the rotor open-circuit end voltage are calculated respectively by the constructed rotor current observer of the exciter, and then the stator current at the next moment is predicted by the stator current prediction model based on the rotor flux and the rotor open-circuit end voltage. After that, the stator current at the next moment is converted to the three-phase stationary coordinate system by coordinate transformation again, and then the rotor current value of the main motor at the next moment is predicted based on the electromagnetic coupling relationship between the main motor and the exciter, according to the rotor current value of the exciter at the current moment and the predicted value of the rotor current at the next moment. After that, the three-phase stator current of the main motor is further converted to a two-phase rotating coordinate system. According to the mathematical model of the main motor and the rotor current prediction value of the main motor at the current moment, the stator current prediction value of the main motor at the next moment is determined, thereby constructing the excitation control cost function and the main motor control cost function respectively. Finally, the switching vector state of the inverter is selected according to the cost function, and the optimal switching vector output is selected to drive the corresponding inverter, thereby realizing the control of the main motor and the exciter.

[0153] In the embodiment of the present invention, the main motor inverter and the exciter inverter may be three-phase two-level excitation inverters, for example, Figure 5 The schematic diagram of the structure of the three-phase two-level excitation inverter in the embodiment of the present invention includes three switch states A, B, and C, which can form a total of 8 switch vector states, and each switch state has a corresponding output voltage vector. Specifically, it can be shown in the following Table 1:

[0154] Table 1:

[0155]

[0156] Among them, S a , S b , S c They represent the conduction state of the upper bridge arm of each phase, "1" represents on, "0" represents off, and V0 to V7 represent the output voltage vector corresponding to each switching state.

[0157] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other. Each embodiment focuses on the differences from other embodiments.

[0158] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present application.

Claims

1. A predictive starting control method for an aviation three-stage motor based on a cascade coupling structure, characterized in that: include: The three-phase currents of the stators of the three-stage main motor and the exciter are respectively obtained in a three-phase stationary coordinate system; According to the three-phase current of the stator of the exciter and the mathematical model of the exciter, a rotor current observer of the exciter is constructed to obtain the rotor current observation value of the exciter at the current moment; According to the preset first vector transformation strategy, the three-phase stator current of the exciter is converted into a two-phase stationary coordinate system, so as to construct a stator current prediction model of the exciter, and predict the stator current of the exciter at the next moment of the current moment; According to the preset second vector transformation strategy, the predicted value of the stator current of the exciter at the next moment is converted to a three-phase stationary coordinate system, and according to the electromagnetic coupling relationship between the main motor and the exciter, a rotor excitation current prediction model of the main motor is constructed to obtain the predicted value of the rotor excitation current of the main motor at the next moment; According to a preset third vector transformation strategy, the three-phase stator current of the main motor is converted into a two-phase rotating coordinate system to obtain the stator current of the main motor in the two-phase rotating coordinate system at the current moment; According to the stator current of the main motor in the two-phase rotating coordinate system at the current moment and the mathematical model of the main motor, a stator current prediction model of the main motor is constructed to obtain a stator current prediction value of the main motor at the next moment; According to the predicted value of the rotor excitation current of the main motor at the next moment, design an excitation control cost function of the exciter inverter; and according to the predicted value of the stator current of the main motor at the next moment, design a main motor control cost function of the main motor inverter; According to the excitation control cost function, the first optimal voltage vector of the exciter inverter is predicted, and the exciter inverter is driven by the first optimal voltage vector to perform predictive control on the exciter; according to the main motor control cost function, the second optimal voltage vector of the main motor inverter is predicted, and the main motor inverter is driven by the second optimal voltage vector to perform predictive control on the main motor.

2. The method according to claim 1, characterized in that The method of constructing a rotor current observer of the exciter according to the three-phase current of the stator of the exciter and the mathematical model of the exciter to obtain the rotor current observation value of the exciter at the current moment includes: Constructing a rotor current observer of the exciter according to the stator voltage, stator flux equation and rotor current characteristics of the exciter; Wherein, the stator voltage of the exciter is expressed as: The stator flux equation of the exciter is expressed as: The rotor current characteristic of the exciter is expressed as: i ra +i rb +i rc =0; Among them, u A ,u B and u C is the voltage at the three-phase winding terminals of the exciter stator, i sA ,i sB and i sC is the three-phase current of the exciter stator, i ra ,i rb and i rc is the three-phase current of the exciter rotor, and is the three-phase flux linkage of the exciter stator, R se is the phase resistance of the stator winding of the exciter, L se is the total self-inductance of the stator winding of the exciter, M sr is the mutual inductance amplitude of the stator and rotor windings of the exciter, θ r is the exciter rotor position; According to the rotor current observer of the exciter, an exciter rotor current estimation expression in a three-phase stationary coordinate system is determined; the exciter rotor current estimation expression is expressed as: Among them, A1 is the calculation factor of phase C, and A2 is the calculation factor of phase B; According to the exciter rotor current estimation expression, the rotor current observation value of the exciter at the current moment is determined.

3. The method according to claim 2, characterized in that The stator current prediction model of the exciter is constructed to predict the stator current of the exciter at the next moment after the current moment, including: Based on the mathematical equation of the exciter, observing the rotor flux and the rotor terminal voltage of the exciter at the current moment in the two-phase stationary coordinate system; Among them, the rotor flux of the exciter is expressed as: The rotor terminal voltage of the exciter is expressed as: in, is the rotor flux of the exciter, L r is the exciter rotor winding self-inductance, i s is the stator current of the exciter, L m is the mutual inductance of the exciter rotor winding, i r is the exciter rotor current; V r is the rotor terminal voltage of the exciter, R r is the phase resistance of the exciter rotor winding, is the differential operator, j is the imaginary unit, w is the rotor electrical angular velocity, and k represents the current moment; According to the stator current expression of the exciter and forward Euler discretization, a stator current prediction model of the exciter is constructed, and the current prediction value of the exciter stator at the next moment is obtained through the stator current prediction model of the exciter; wherein the stator current prediction model of the exciter is expressed as: Among them, k+1 represents the next moment of the current moment, i s (k+1) is the predicted value of the stator current of the exciter at the next moment from the current moment, T s is the sampling time of the system, k r is the magnetic coupling factor, Rσ is the equivalent resistance, σ is the magnetic leakage coefficient, τ r is the rotor time constant, τ σ is the instantaneous time constant, V s is the stator terminal voltage of the exciter.

4. The method according to claim 3, characterized in that The method of constructing a rotor excitation current prediction model of the main motor according to the electromagnetic coupling relationship between the main motor and the exciter to obtain a predicted value of the rotor excitation current of the main motor at the next moment includes: The electromagnetic coupling relationship is expressed as: |and ra |+|and rb |+|and rc |=2i f ; Among them, i f Is the main motor rotor excitation current value; According to the electromagnetic coupling relationship and the observation result of the exciter rotor current observer, the rotor excitation current value of the main motor at the current moment is obtained, which is expressed as: Among them, i f (k) is the rotor excitation current value of the main motor at the current moment, i ra (k), i rb (k), i rc (k) are the three-phase current observation values ​​of the exciter rotor at the current moment; Predicting the rotor current of the exciter at the next moment according to the exciter rotor current observer and the predicted value of the stator current of the exciter at the next moment; According to the electromagnetic coupling relationship and the predicted value of the rotor current of the exciter at the next moment, the predicted value of the rotor excitation current of the main motor at the next moment is determined; the predicted value of the rotor excitation current of the main motor at the next moment is expressed as: Among them, i f (k+1) is the predicted value of the main motor rotor excitation current at the next moment from the current moment, i ra (k+1), i rb (k+1), i rc (k+1) are the predicted three-phase current values ​​of the exciter rotor at the next moment.

5. The method according to claim 4, characterized in that The stator current prediction model of the main motor is constructed according to the stator current of the main motor in the two-phase rotating coordinate system at the current moment and the mathematical model of the main motor, and the stator current prediction value of the main motor at the next moment is obtained, including: According to the electrically excited synchronous motor model, the voltage and flux equations of the main motor are established; Among them, the voltage equation of the main motor is expressed as: Among them, u d is the stator d-axis voltage of the main motor, u q is the q-axis voltage of the main motor stator, u f is the main motor rotor excitation winding voltage, R sm is the stator resistance of the main motor, R f is the resistance value of the main motor rotor excitation winding, i d is the stator d-axis current of the main motor, i q is the q-axis current of the main motor stator, i f is the main motor rotor excitation current, is the stator d-axis flux of the main motor, is the q-axis magnetic flux of the main motor stator, is the main motor rotor excitation flux, w e The electrical angular velocity of the main motor; The flux equation of the main motor is expressed as: Among them, L d The equivalent inductance of the stator winding d axis of the main motor, L q is the q-axis equivalent inductance of the main motor stator winding, L md is the mutual inductance between the d-axis equivalent inductance of the stator winding of the main motor and the rotor winding, L f The self-inductance of the main motor excitation winding; Apply the forward Euler discretization formula to the voltage equation of the main motor to obtain the predicted value of the stator current of the main motor at the next moment, which is expressed as: Among them, i d (k+1) is the stator d-axis current of the main motor at time k+1, i q (k+1) is the stator q-axis current of the main motor at time k+1.

6. The method according to claim 5, characterized in that The excitation control cost function in the constant excitation control mode is expressed as: The main motor control cost function is expressed as: Among them, g e is the excitation control cost function, g m is the main motor control cost function, As the main motor rotor excitation current reference, For the main motor d-axis current reference, It is the reference of the q-axis current of the main motor.

7. The method according to claim 6, characterized in that The predicting, according to the excitation control cost function, a first optimal voltage vector of the exciter inverter comprises: Evaluating a plurality of switch vector states of the exciter inverter by using the excitation control cost function, and determining the first optimal voltage vector from voltage vectors corresponding to the plurality of switch vector states; The predicting, according to the main motor control cost function, a second optimal voltage vector of the main motor inverter comprises: The plurality of switch vector states of the main motor inverter are evaluated by using the main motor control cost function, and the second optimal voltage vector is determined from the voltage vectors corresponding to the plurality of switch vector states.

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