Three-stage motor high-frequency impedance modeling method based on cascade coupling evaluation

Abstract

The invention discloses a cascade coupling evaluation-based three-stage motor high-frequency impedance modeling method, which comprises the following steps of: respectively defining a main motor and an exciter as a differential-mode two-port network and a common-mode two-port network, and obtaining Z parameter matrixes of the main motor and the exciter according to a mathematical equation of the two-port networks; according to a mutual conversion relation between a Z parameter and a T parameter of a two-port network, an impedance coupling model of a cascade three-stage motor formed by a main motor and an exciter is established by using the T parameter, an equivalent Z parameter matrix of differential mode impedance and common mode impedance of the cascade three-stage motor is obtained, and according to the established impedance coupling model of the cascade three-stage motor, an impedance coupling model of the cascade three-stage motor is obtained. And establishing an impedance coupling evaluation model of the cascaded three-stage motor, and establishing a cascaded coupling evaluation-based three-stage motor high-frequency impedance model structure according to an impedance coupling evaluation result of the system. Therefore, the problem that an existing motor modeling method cannot be directly applied can be solved.

Description

Technical Field

[0001] The present application relates to the technical field of aviation AC motors, and in particular to a three-stage motor high-frequency impedance modeling method based on cascade coupling evaluation. Background Art

[0002] Aviation starter / generator integrated technology has become an important development direction for future more electric aircraft. The starter / generator integrated technology uses the reversible principle of the motor to eliminate the traditional dedicated starter and realize the dual functions of starting and generating electricity. This design simplifies the engine's accessory casing and air bleed device, reduces the "dead weight" of the aircraft, and improves the overall reliability, maintainability and energy efficiency of the aircraft.

[0003] The three-stage brushless synchronous motor has the advantages of mature power generation technology and wide application range. The integrated starting / generating system based on the three-stage motor has become an important development direction of future multi-electric large aircraft technology. The three-stage generator 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 / generating integrated function.

[0004] With the continuous improvement of switching frequency and system integration, the starting controller based on pulse width modulation (PWM) technology has improved the starting control performance, but also caused serious conducted electromagnetic interference (EMI) problems. The EMI problem of the starter / generator system not only affects its own reliable operation, but also seriously affects the normal operation of other onboard electrical equipment as an interference source, thereby affecting the electromagnetic compatibility performance of the entire more-electric aircraft power system. As an important conduction path of EMI, the broadband impedance modeling technology of the three-stage starter / generator is an important basis for conducting related EMI research.

[0005] Due to its special motor cascade structure, the system has the significant characteristics of multi-motor coupling and multi-interference sources, which provides the possibility for EMI conduction coupling between subsystems. However, the traditional motor impedance modeling method usually only considers the stator impedance and is not suitable for EMI coupling analysis between three-stage motors. Summary of the invention

[0006] The embodiment of the present application solves the problem that the existing motor modeling method cannot be directly applied by providing a three-stage motor high-frequency impedance modeling method based on cascade coupling evaluation.

[0007] In order to achieve the above object, the technical solution of the embodiment of the present invention is:

[0008] In a first aspect, an embodiment of the present invention provides a three-stage motor high-frequency impedance modeling method based on cascade coupling evaluation, comprising: defining a main motor and an exciter as a differential-mode two-port network and a common-mode two-port network, respectively, wherein the differential-mode two-port network is used to characterize the differential-mode interference transmission path, and the common-mode two-port network is used to characterize the common-mode interference transmission path; according to the mathematical equation of the two-port network, respectively obtaining the differential-mode impedance Z parameter matrix and the common-mode impedance Z parameter matrix of the main motor and the exciter; according to the conversion relationship between the two-port network Z parameter and the T parameter, respectively converting the differential-mode impedance Z parameter matrix and the common-mode impedance Z parameter matrix of the main motor and the exciter into a T parameter matrix, and based on the cascade equivalent relationship of the T parameter matrix The differential-mode impedance equivalent T parameter matrix and the common-mode impedance equivalent T parameter matrix of the cascaded three-stage motor composed of the main motor and the exciter are obtained, and then the differential-mode impedance equivalent T parameter matrix and the common-mode impedance equivalent T parameter matrix are converted into the differential-mode impedance equivalent Z parameter matrix and the common-mode impedance equivalent Z parameter matrix of the cascaded three-stage motor respectively; based on the obtained differential-mode impedance equivalent Z parameter matrix and the common-mode impedance equivalent Z parameter matrix of the cascaded three-stage motor, the impedance relative error rate caused by ignoring the impedance coupling of the cascaded motor is calculated; according to the comparison result of the relative error rate with the preset reference error rate, the high-frequency impedance model structure of the three-stage motor based on cascade coupling evaluation is established, and the equivalent circuit parameters are solved by the circuit parameterization method.

[0009] In some possible implementations, the mathematical equation of the two-port network based on Z parameters is expressed as:

[0010] ;

[0011] in, Represents the input port of a two-port network and The input port voltage between Represents the output port of a two-port network and The output port voltage between represents the input port current flowing through the input port, represents the output port current flowing through the output port, and the Z parameter matrix describes the relationship between the input / output port voltage and the input / output port current, which is expressed as:

[0012] ;

[0013] in, represents the input impedance of the two-port network, represents the output impedance of the two-port network, and represents the transfer impedance of the two-port network.

[0014] In some possible implementations, the differential mode impedance Z parameter matrix and the common mode impedance Z parameter matrix of the main motor and the exciter are respectively expressed as:

[0015] ;

[0016] in, is the main motor differential mode impedance Z parameter matrix, is the main motor common mode impedance Z parameter matrix, is the exciter differential mode impedance Z parameter matrix, is the exciter common mode impedance Z parameter matrix.

[0017] In some possible implementations, the conversion relationship between the two-port network Z parameter and the T parameter is expressed as:

[0018] .

[0019] In some possible implementations, the T parameter matrix describes the relationship between the voltage / current at the input port and the voltage / current at the output port of the two-port network. The two-port network is represented by a mathematical equation based on the T parameter description:

[0020] ;

[0021] Based on the cascade equivalent relationship of the T parameter matrix, the differential mode impedance equivalent T parameter matrix and the common mode impedance equivalent T parameter matrix of the cascaded three-stage motor composed of the main motor and the exciter are obtained, including:

[0022] According to the T parameter equation of the two-port network, the cascaded two-port network corresponding to the cascaded three-stage motor composed of the main motor and the exciter is obtained; the cascaded two-port network includes a two-port network 1 and a two-port network 2, and the two output ports of the two-port network 1 are respectively connected to the two input ports of the two-port network 2; the cascaded two-port network satisfies the following expression:

[0023] ;

[0024] in, represents the input port voltage of the two-port network, represents the input port current of the two-port network, represents the output port voltage of the two-port network, represents the output port current of the two-port network, represents the input port voltage of the two-port network, represents the input port current of the two-port network, represents the output port voltage of the two-port network, represents the output port current of the two-port network, and is the T parameter matrix of the cascaded two-port network 1 and the two-port network 2;

[0025] Among them, the cascaded two-port network satisfies , ; Therefore, the cascaded two-port network further satisfies the following expression:

[0026] ;

[0027] The cascaded two-port network is equivalent to a new two-port network, and the equivalent T parameter matrix of the cascade system It can be calculated by the following formula:

[0028] ;

[0029] According to the equivalent T parameter matrix equivalent method of the cascade system, the differential mode impedance equivalent T parameter matrix and the common mode impedance equivalent T parameter matrix of the cascaded three-stage motor composed of the main motor and the exciter are obtained, which are expressed as:

[0030] ;

[0031] in, is the differential mode impedance equivalent T parameter matrix of the cascaded three-stage motor, is the common-mode impedance equivalent T parameter matrix of the cascaded three-stage motor, is the main motor differential mode impedance T parameter matrix, is the exciter differential mode impedance T parameter matrix, is the parameter matrix of the main motor common mode impedance T, is the exciter common mode impedance T parameter matrix;

[0032] The conversion of the differential mode impedance equivalent T parameter matrix and the common mode impedance equivalent T parameter matrix into the differential mode impedance equivalent Z parameter matrix and the common mode impedance equivalent Z parameter matrix of the cascaded three-stage motor is achieved through the conversion relationship between the two-port network T parameters and the Z parameters. The conversion relationship between the two-port network T parameters and the Z parameters is expressed as:

[0033] .

[0034] In some possible implementations, based on the obtained differential-mode impedance equivalent Z parameter matrix and common-mode impedance equivalent Z parameter matrix of the cascaded three-stage motor, the impedance relative error rate caused by ignoring the impedance coupling of the cascaded motor is calculated, including:

[0035] According to the differential mode impedance equivalent Z parameter matrix and the common mode impedance equivalent Z parameter matrix, the three-stage motor impedance considering cascade coupling is obtained, which is expressed as:

[0036] ;

[0037] in, To consider the equivalent differential mode impedance of the main motor side when the cascade motor impedance coupling is used, To consider the equivalent differential mode impedance of the exciter side when the cascaded motor impedance coupling is used, To consider the equivalent common mode impedance of the main motor side when the cascade motor impedance coupling is used, To consider the equivalent common mode impedance of the exciter side when the cascaded motor impedance coupling is used, is the differential mode impedance equivalent Z parameter matrix of the cascaded three-stage motor, is the common mode impedance equivalent Z parameter matrix of the cascaded three-stage motor;

[0038] According to the obtained three-stage motor impedance, the impedance relative error rate caused by ignoring the cascade motor impedance coupling is calculated, which is expressed as:

[0039] ;

[0040] in, The relative error rate of the differential mode impedance of the main motor caused by ignoring the impedance coupling of the cascaded motor is: To ignore the relative error rate of the differential mode impedance of the exciter caused by the impedance coupling of the cascaded motor, The relative error rate of the main motor common mode impedance caused by ignoring the impedance coupling of the cascaded motor is: The relative error rate of the common-mode impedance of the exciter caused by ignoring the impedance coupling of the cascaded motor.

[0041] In some possible implementations, according to the comparison result between the relative error rate and the preset reference error rate, a three-stage motor high-frequency impedance model structure based on cascade coupling evaluation is established, including:

[0042] When the relative error rate is lower than the preset reference error rate in the entire frequency band, the impedance coupling between the three-stage motors is ignored, and the main motor and the exciter are regarded as two independent motors for high-frequency impedance modeling analysis. The low-coupling unit part is selected from the constructed three-stage motor high-frequency impedance model structure based on cascade coupling evaluation as its equivalent circuit model structure; at this time, the equivalent circuit model structure only includes the stator winding impedance branches of the main motor and the exciter, respectively, without considering the impedance coupling between the cascaded three-stage motors, that is, the differential mode and / or common mode analysis only considers the stator impedance of the main motor and the stator impedance of the exciter;

[0043] When the relative error rate is higher than the preset reference error rate in the entire frequency band, the high coupling unit part is selected from the constructed three-stage motor high-frequency impedance model structure based on cascade coupling evaluation as its equivalent circuit model structure; at this time, the equivalent circuit model structure adopts a T-type equivalent circuit structure to be equivalent to the established cascade equivalent two-port network differential mode impedance equivalent Z parameter matrix and common mode impedance equivalent Z parameter matrix;

[0044] When the relative error rate is higher than the preset reference error rate in the low frequency band and lower than the preset reference error rate in the high frequency band, a hybrid model structure in which a low coupling unit part and a high coupling unit part are connected in parallel is selected from the constructed three-stage motor high frequency impedance model structure based on cascade coupling evaluation as its equivalent circuit model structure; wherein the high coupling unit part is used to consider the low-frequency impedance coupling characteristics between the three-stage motors with a higher error rate, and a high-pass filter is added to the low coupling unit part to prevent the impedance influence of the high coupling unit; the frequency of the filter is determined by the impedance error evaluation result;

[0045] The equivalent circuit parameters are solved by a circuit parameterization method, including: calculating the impedance of each branch in the equivalent circuit model structure according to the impedance extraction result, and solving the equivalent circuit parameter value by using a vector matching circuit parameterization method.

[0046] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0047] In the embodiment of the present invention, by defining the main motor and the exciter as a differential mode two-port network and a common mode two-port network respectively, according to the mathematical equation of the two-port network, the Z parameter matrix of the main motor and the exciter is obtained, according to the mutual conversion relationship between the two-port network Z parameter and the T parameter, the impedance coupling model of the cascaded three-stage motor composed of the main motor and the exciter is established by using the T parameter, and the differential mode impedance and common mode impedance equivalent Z parameter matrix of the cascaded three-stage motor is obtained. According to the impedance coupling model of the cascaded three-stage motor established, the impedance coupling evaluation model of the cascaded three-stage motor is established, and according to the impedance coupling evaluation result of the system, the high-frequency impedance model structure of the three-stage motor based on the cascade coupling evaluation is established, and the circuit parameterization solution is performed. In this way, the cascade coupling structure of the three-stage motor is fully considered, the stator-rotor coupling and the impedance coupling association between the motors are realized, and the technical difficulty that the traditional motor high-frequency impedance modeling method cannot be directly used for the three-stage motor is made up, and the theoretical basis is provided for the simplification of the high-frequency model of the three-stage motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] 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.

[0049] Figure 1 The following is a typical starting scheme diagram of a three-stage motor based on a three-phase active excitation structure;

[0050] Figure 2 It is a schematic diagram of a three-stage motor multi-terminal network model based on network theory;

[0051] Figure 3 A schematic flow chart of an embodiment of a method for modeling high-frequency impedance of a three-stage motor based on cascade coupling evaluation provided for the implementation of the present invention;

[0052] Figure 4 It is a typical two-port network diagram;

[0053] Figure 5 This is a schematic diagram of the two-port definition of the differential mode impedance of the main motor;

[0054] Figure 6 This is a schematic diagram of the two-port definition of the common-mode impedance of the main motor;

[0055] Figure 7 It is a schematic diagram of the two-port definition of differential mode impedance of the exciter;

[0056] Figure 8 It is a schematic diagram of the two-port definition of the common-mode impedance of the exciter;

[0057] Fig. 9 for Schematic diagram of the extraction process;

[0058] Fig.10 for Schematic diagram of the extraction process;

[0059] Fig.11 For the intermediate amount Schematic diagram of the extraction process;

[0060] Fig.12 Schematic diagram of the equivalent process of a two-port network of a cascaded motor based on T parameters in an embodiment of the present invention;

[0061] Fig.13 is a schematic diagram of a cascade equivalent two-port network in an embodiment of the present invention;

[0062] Fig.14 It is a structural diagram of a three-stage motor high-frequency impedance model based on cascade coupling evaluation in an embodiment of the present invention;

[0063] Fig.15 An equivalent circuit diagram of each branch in the model structure diagram in an embodiment of the present invention;

[0064] Fig.16 A simulation diagram of the relative error rate of the differential mode impedance of the main motor in an embodiment of the present invention;

[0065] Fig.17 Schematic diagram of the comparison results of the equivalent circuit impedance spectrum of the low-coupling unit branch of the main motor differential mode impedance. DETAILED DESCRIPTION

[0066] 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 this application.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] In order to illustrate the technical solution of the present invention, specific embodiments are provided below for illustration.

[0073] Aviation starter / generator integrated technology has become an important development direction for future more electric aircraft. The starter / generator integrated technology uses the reversible principle of the motor to eliminate the traditional dedicated starter and realize the dual functions of starting and generating electricity. This design simplifies the engine's accessory casing and air bleed device, reduces the "dead weight" of the aircraft, and improves the overall reliability, maintainability and energy efficiency of the aircraft.

[0074] The three-stage brushless synchronous motor has the advantages of mature power generation technology and a wide range of applications. The integrated starting / generation system based on the three-stage motor has become an important development direction of future large aircraft technology. The three-stage generator 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. See Figure 1 As shown, Figure 1 The following is a typical structure diagram of a three-stage motor starting scheme based on a three-phase active excitation structure. 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.

[0075] With the continuous improvement of switching frequency and system integration, the starting controller based on pulse width modulation (PWM) technology has improved the starting control performance, but also caused serious conducted electromagnetic interference (EMI) problems. The EMI problem of the starter / generator system not only affects its own reliable operation, but also seriously affects the normal operation of other onboard electrical equipment as an interference source, thereby affecting the electromagnetic compatibility performance of the entire more-electric aircraft power system. As an important conduction path of EMI, the broadband impedance modeling technology of the three-stage starter / generator is an important basis for conducting related EMI research.

[0076] Due to its special motor cascade structure, the system has the significant characteristics of multi-motor coupling and multi-interference sources, which provides the possibility for EMI conduction coupling between subsystems. However, the traditional motor impedance modeling method usually only considers the stator impedance and is not suitable for EMI coupling analysis between three-stage motors.

[0077] Based on this, the embodiment of the present invention solves the problem that the existing motor modeling method cannot be directly applied by providing a three-stage motor high-frequency impedance modeling method based on cascade coupling evaluation.

[0078] The typical starting scheme of the three-stage motor based on the three-phase active excitation structure in the embodiment of the present invention is shown in the above Figure 1 As shown. The system is mainly composed of the motor body composed of the coaxially mounted main motor, exciter, and rotating rectifier, and the starter part composed of the main motor inverter and exciter inverter. The rotating rectifier, main motor inverter, and exciter inverter constitute the interference source of the system, and the main motor and exciter are the key paths for EMI transmission of the system. According to the electrical network theory, it can be obtained as follows Figure 2 The schematic diagram of the three-stage motor multi-terminal network model is shown. Figure 1 to Figure 2 middle, , , They are the three ports of the main motor inverter. , , They are the three ports of the exciter inverter. , They are the two ports of the main motor, , , They are the three ports of the exciter, Figure 2 middle This is the grounding port.

[0079] Figure 3 A schematic diagram of an embodiment of a three-stage motor high-frequency impedance modeling method based on cascade coupling evaluation provided for the implementation of the present invention, see Figure 3 As shown, the three-stage motor high-frequency impedance modeling method based on cascade coupling evaluation may include:

[0080] S301, defining the main motor and the exciter as a differential mode two-port network and a common mode two-port network respectively, wherein the differential mode two-port network is used to characterize the differential mode interference transmission path, and the common mode two-port network is used to characterize the common mode interference transmission path;

[0081] It should be noted that a two-port network is a circuit model with two ports (input and output) that is used to describe how signals or energy are transmitted in a system. Each port has two connection points that can input or output current and voltage. Differential mode interference is the voltage difference generated when a signal is transmitted between two wires and is part of the normal signal. Common mode interference is usually the same interference signal (such as noise) that is received by two wires at the same time, usually due to external electromagnetic interference or grounding problems. See Figure 4 As shown, Figure 4 This is a typical two-port network diagram.

[0082] Differential mode impedance is the equivalent impedance of the main motor and exciter under differential mode signals, reflecting its ability to transmit normal signals. Common mode impedance is the equivalent impedance of the main motor and exciter under common mode interference, reflecting its ability to transmit common mode noise.

[0083] The impedance two-port network definition is to abstract the differential mode impedance and common mode impedance characteristics of the main motor and the exciter into a two-port network model. Among them, the input port represents the access point of the interference source (such as noise or signal source). The output port represents the transmission result of the interference or signal in the motor and the exciter. The network parameters describe how the interference signal is transmitted and attenuated in the system through the differential mode impedance and the common mode impedance.

[0084] In the embodiment of the present invention, the Figure 4 The two-port network shown is used to equate the differential mode impedance and common mode impedance of the main motor and the exciter, thereby obtaining the impedance two-port network definition of the main motor and the exciter.

[0085] For example, see Figure 5 As shown, Figures 5 to 8 Schematic diagram of the impedance two-port network definition of the main motor and the exciter in the embodiment of the present invention. Figure 5 This is a schematic diagram of the two-port definition of the differential mode impedance of the main motor. Figure 6 This is a schematic diagram of the two-port definition of the common-mode impedance of the main motor. Figure 7 This is a schematic diagram of the two-port definition of the differential mode impedance of the exciter. Figure 8 Schematic diagram of the two-port definition of the common-mode impedance of the exciter.

[0086] S302, according to the mathematical equation of the two-port network, respectively obtain the differential mode impedance Z parameter matrix and the common mode impedance Z parameter matrix of the main motor and the exciter;

[0087] In some embodiments, the two-port network based on the Z parameter satisfies the following relationship:

[0088] ;

[0089] in, Represents the input port of a two-port network and The input port voltage between Represents the output port of a two-port network and The output port voltage between represents the input port current flowing through the input port, represents the output port current flowing through the output port, and the Z parameter matrix describes the relationship between the input / output port voltage and the input / output port current, which is expressed as:

[0090] ;

[0091] in, represents the input impedance of the two-port network, represents the output impedance of the two-port network, and represents the transfer impedance of the two-port network.

[0092] It should be noted that in the above formula, the numbers in the subscripts 11 to 22 refer to the number of rows and columns in the matrix, corresponding to the two input ports and two output ports in the two-port network (for example Figure 4 The superscripts of the parameters in the subsequent formulas have similar representations as here and will not be described in detail later.

[0093] In some embodiments, the above step S302 specifically includes:

[0094] According to the mathematical equation satisfied by the above two-port network, the calculation method of Z parameter is obtained, which is expressed as:

[0095] ;

[0096] in, and It can be directly measured using an impedance tester. For the measurement method, see Figures 9 to 11 As shown, Figures 9 to 11 Schematic diagram of the Z parameter extraction process of a two-port network in an embodiment of the present invention. Fig. 9 for Schematic diagram of the extraction process. Fig.10 for Schematic diagram of the extraction process. Fig.11 For the intermediate amount Schematic diagram of the extraction process.

[0097] According to the Z parameter characteristics of passive devices ( ), in Fig.11 The output port R1 and R2 short circuit test method shown is calculated by the following expression;

[0098] ;

[0099] in, Fig.11 middle Indicates output port and Short circuit input port and Impedance. On this basis, the complete two-port network Z parameter matrix can be obtained.

[0100] Afterwards, according to the measurement and calculation method of the two-port network Z parameter matrix, we can obtain Figures 5 to 8 The impedance two-port network matrix of the three-stage main motor and exciter is shown in FIG. The differential mode impedance Z parameter matrix and common mode impedance Z parameter matrix of the main motor and exciter can be expressed as:

[0101] ;

[0102] in, is the main motor differential mode impedance Z parameter matrix, is the main motor common mode impedance Z parameter matrix, is the exciter differential mode impedance Z parameter matrix, is the exciter common mode impedance Z parameter matrix.

[0103] S303, according to the conversion relationship between the two-port network Z parameters and T parameters, the differential mode impedance Z parameter matrix and the common mode impedance Z parameter matrix of the main motor and the exciter are converted into T parameter matrices respectively, and based on the cascade equivalent relationship of the T parameter matrix, the differential mode impedance equivalent T parameter matrix and the common mode impedance equivalent T parameter matrix of the cascaded three-stage motor composed of the main motor and the exciter are obtained, and then the differential mode impedance equivalent T parameter matrix and the common mode impedance equivalent T parameter matrix are converted into the differential mode impedance equivalent Z parameter matrix and the common mode impedance equivalent Z parameter matrix of the cascaded three-stage motor respectively;

[0104] Among them, the obtained Z parameter matrix of the main motor and the exciter is converted into a T parameter matrix to solve the problem that the Z parameter cannot be directly used for the calculation of the cascade system.

[0105] In some embodiments, the conversion relationship between the two-port network Z parameter and the T parameter is expressed as:

[0106] ;

[0107] The T parameter matrix describes the relationship between the voltage / current at the input port and the voltage / current at the output port of a two-port network. The two-port network is represented by a mathematical equation based on the T parameter description:

[0108] ;

[0109] Based on the T parameter description of the two-port network, in some embodiments, based on the cascade equivalent relationship of the T parameter matrix, obtaining the differential mode impedance equivalent T parameter matrix and the common mode impedance equivalent T parameter matrix of the cascaded three-stage motor composed of the main motor and the exciter can specifically include:

[0110] According to the T parameter equation of the two-port network, a cascaded two-port network corresponding to the cascaded three-stage motor composed of the main motor and the exciter is obtained; the cascaded two-port network includes a two-port network 1 and a two-port network 2, and the two output ports of the two-port network 1 are respectively connected to the two input ports of the two-port network 2;

[0111] For example, Fig.12: is a schematic diagram of the equivalent process of a two-port network of a cascaded motor based on T parameters in an embodiment of the present invention, wherein: Fig.12 The cascaded two-port network shown satisfies the following expression:

[0112] ;

[0113] in, represents the input port voltage of the two-port network, represents the input port current of the two-port network, represents the output port voltage of the two-port network, represents the output port current of the two-port network, Represents the input port voltage of port 2, represents the input port current of the two-port network, represents the output port voltage of the two-port network, represents the output port current of the two-port network, and is the T parameter matrix of the cascaded two-port network 1 and the two-port network 2; Fig.12 middle, , is the input port of the two-port network 1, , is the input port of the two-port network 1, , is the input port of two-port two, , is the output port of two-port network 2.

[0114] Among them, the cascaded two-port network satisfies , ; Therefore, the cascaded two-port network further satisfies the following expression:

[0115] ;

[0116] The cascaded two-port network is equivalent to a new two-port network, see Fig.13 As shown, Fig.13 Schematic diagram of a cascaded equivalent two-port network in an embodiment of the present invention. Fig.13 The equivalent T parameter matrix of the cascaded equivalent two-port network shown in It can be calculated by the following formula:

[0117] ;

[0118] Will Fig.12 The two-port network 1 and the two-port network 2 are cascaded to obtain Fig.13 The cascaded equivalent two-port network shown, Fig.13 In , is the input port of the cascaded equivalent two-port network, , is the output port of the cascaded equivalent two-port network.

[0119] Afterwards, according to the equivalent T parameter matrix of the cascade system The equivalent method is used to obtain the differential mode impedance equivalent T parameter matrix and the common mode impedance equivalent T parameter matrix of the cascaded three-stage motor composed of the main motor and the exciter, which can be specifically expressed as:

[0120] ;

[0121] in, is the differential mode impedance equivalent T parameter matrix of the cascaded three-stage motor, is the common-mode impedance equivalent T parameter matrix of the cascaded three-stage motor, is the main motor differential mode impedance T parameter matrix, is the exciter differential mode impedance T parameter matrix, is the parameter matrix of the main motor common mode impedance T, is the parameter matrix of the common mode impedance T of the exciter.

[0122] Afterwards, the obtained differential-mode impedance equivalent T parameter matrix and common-mode impedance equivalent T parameter matrix can be converted into the differential-mode impedance equivalent Z parameter matrix and common-mode impedance equivalent Z parameter matrix of the cascaded three-stage motor, respectively.

[0123] In some embodiments, the differential mode impedance equivalent T parameter matrix and the common mode impedance equivalent T parameter matrix are converted into the differential mode impedance equivalent Z parameter matrix and the common mode impedance equivalent Z parameter matrix of the cascaded three-stage motor, which is achieved through the conversion relationship between the two-port network T parameters and the Z parameters. Specifically, the conversion relationship between the two-port network T parameters and the Z parameters can be expressed as:

[0124] .

[0125] It should be noted that in two-port network modeling, the Z parameter directly represents the impedance characteristics of the network through the voltage-current relationship of the input / output port (such as the input impedance , output impedance Transfer impedance / ), so it can be directly used for impedance modeling and analysis of the two-port network, but it cannot be directly used in the modeling and calculation of the cascade system (such as the multi-motor series structure of a three-stage motor).

[0126] To solve this problem, in the above step S303, the two-port network Z parameter is converted into a T parameter suitable for cascade operation. The T parameter that characterizes the voltage-current transfer relationship of the input / output port can directly describe the cascade characteristics of the two-port network. The cascade T parameter equivalent method obtained thereby can simplify the modeling process of the cascade two-port network. After the cascade equivalence is completed, the T parameter is converted back to the Z parameter to retain the physical meaning of the impedance, which is convenient for the subsequent correlation analysis between the impedance model and the circuit parameters. This method not only utilizes the intuitive characterization ability of the Z parameter for the impedance characteristics, but also avoids the calculation bottleneck of the cascade system through the T parameter, and can realize the efficient modeling of complex coupled systems.

[0127] S304, calculating the impedance relative error rate caused by ignoring the impedance coupling of the cascaded motor based on the obtained differential mode impedance equivalent Z parameter matrix and common mode impedance equivalent Z parameter matrix of the cascaded three-stage motor;

[0128] In some embodiments, the above step S304 specifically includes:

[0129] S3041, according to the differential mode impedance equivalent Z parameter matrix and the common mode impedance equivalent Z parameter matrix, obtain the three-stage motor impedance considering the cascade coupling, which is implemented by the following formula:

[0130] ;

[0131] in, To consider the equivalent differential mode impedance of the main motor side when the cascade motor impedance coupling is used, To consider the equivalent differential mode impedance of the exciter side when the cascaded motor impedance coupling is used, To consider the equivalent common mode impedance of the main motor side when the cascade motor impedance coupling is used, To consider the equivalent common mode impedance of the exciter side when the cascaded motor impedance coupling is used, is the differential mode impedance equivalent Z parameter matrix of the cascaded three-stage motor, is the common mode impedance equivalent Z parameter matrix of the cascaded three-stage motor;

[0132] S3042, based on the obtained three-stage motor impedance, calculate the impedance relative error rate caused by ignoring the cascade motor impedance coupling, expressed as:

[0133] ;

[0134] in, The relative error rate of the differential mode impedance of the main motor caused by ignoring the impedance coupling of the cascaded motor is: To ignore the relative error rate of the differential mode impedance of the exciter caused by the impedance coupling of the cascaded motor, The relative error rate of the main motor common mode impedance caused by ignoring the impedance coupling of the cascaded motor is: The relative error rate of the common-mode impedance of the exciter caused by ignoring the impedance coupling of the cascaded motor.

[0135] S305, according to the comparison result of the relative error rate and the preset reference error rate, a three-stage motor high-frequency impedance model structure based on cascade coupling evaluation is established, and the equivalent circuit parameters are solved by a circuit parameterization method.

[0136] For example, Fig.14 It is a structural diagram of a high-frequency impedance model of a three-stage motor based on cascade coupling evaluation in an embodiment of the present invention.

[0137] In some embodiments, the above step S305 may specifically include:

[0138] S3051, when the relative error rate is lower than the preset reference error rate in the whole frequency band, the impedance coupling between the three-stage motors is ignored, and the main motor and the exciter are regarded as two independent motors for high-frequency impedance modeling analysis. Fig.14 The low coupling unit shown in is used as its equivalent circuit model structure; at this time, the equivalent circuit model structure only includes the stator winding impedance branches of the main motor and the exciter, and does not consider the impedance coupling between the cascaded three-stage motors, that is, the differential mode and / or common mode analysis only considers the stator impedance of the main motor ( ) and exciter stator impedance ( ).

[0139] S3052, when the relative error rate is higher than the preset reference error rate in all frequency bands, select Fig.14 The high coupling unit part shown in is used as its equivalent circuit model structure; at this time, the equivalent circuit model structure adopts a T-type equivalent circuit structure to be equivalent to the established cascade equivalent two-port network differential mode impedance equivalent Z parameter matrix and common mode impedance equivalent Z parameter matrix;

[0140] in, Fig.14 In the differential mode impedance model and common mode impedance model, the three branches , , Public branch roads in Used to achieve high-frequency impedance coupling between the main motor and the exciter.

[0141] S3053, when the relative error rate in the low frequency band is higher than the preset reference error rate and the high frequency band is lower than the preset reference error rate, the high frequency coupling of the cascaded three-stage motor can be ignored, but the low frequency coupling cannot be ignored. At this time, you can choose Fig.14The hybrid model structure in which the low-coupling unit part and the high-coupling unit part are connected in parallel is used as its equivalent circuit model structure; among them, the T-type equivalent circuit of the high-coupling unit is used to consider the low-frequency impedance coupling characteristics between the three-stage motors with a high error rate, and a high-pass filter is added to the low-coupling unit part to prevent the influence of low-frequency impedance; the frequency of the filter is determined by the impedance error evaluation result.

[0142] In some embodiments, solving the equivalent circuit parameters by circuit parameterization method includes: calculating the impedance spectrum of each branch in the equivalent circuit model structure according to the impedance extraction result, and solving the equivalent circuit parameter value by vector matching circuit parameterization method. Specifically including:

[0143] Using the vector matching strategy, the impedance of each branch in the above impedance structure can be expressed in the form of residues and poles as follows:

[0144] ;

[0145] in, Indicates the impedance branch that needs to be parameterized. and represents constant terms and linear terms, represents the total order of vector matching fitting, represents the number of vector matching fitting items, and Indicates For residues and extreme point values.

[0146] According to the circuit principle, the above formula can be Fig.15 The equivalent circuit shown is shown in Figure 2. Among them, the equivalent circuit corresponding to the constant term and the first-order term is as follows: Fig.15 The first dotted box from left to right in the figure shows the circuit composed of resistors. and inductance Series composition, , The value of satisfies the following relationship:

[0147] ;

[0148] When the residues and poles of the fit are real numbers, the resistor and capacitor The RC circuit connected in parallel is used for equivalence, and the corresponding equivalent circuit is as follows Fig.15 The second dotted box from left to right in the figure, , The values ​​are:

[0149] ;

[0150] represents the real residues and the number of pole pairs, represents the number of terms of real residues and pole pairs, and Indicates Residues and extreme values ​​for real numbers.

[0151] When the residues and poles of the fit are conjugate complex pairs, this term can be expressed as a resistor. and ,capacitance ,inductance The corresponding equivalent circuit is as follows: Fig.15 The third dotted box from left to right in the figure, , , and The values ​​are:

[0152] ;

[0153] in, represents the conjugate complex residue and the number of pole pairs, represents the number of terms of conjugate complex residues and pole pairs, , , and Indicates For conjugate complex residues and pole pairs, represents the conjugate complex pair of poles and coefficients, represents the conjugate complex dot product coefficient, represents the product and coefficient of the conjugate complex pair.

[0154] Conduct impedance testing on a three-stage motor prototype and build an impedance coupling evaluation model for a cascaded three-stage motor. Fig.16 is the relative error rate of the differential mode impedance of the main motor in the embodiment of the present invention In this embodiment, the preset reference error rate can be set to 0.2. Fig.16 It can be seen from the simulation results that, except for the resonance point of the impedance curve itself, the impedance relative error rate caused by cascade coupling is higher than the preset reference error rate in the low frequency band and lower than the preset reference error rate in the high frequency band, and the frequency cutoff point is about 40kHz. Therefore, from the constructed three-stage motor high-frequency impedance model structure based on cascade coupling evaluation, a hybrid model structure in which the low-coupling unit part and the high-coupling unit part are connected in parallel is selected as its equivalent circuit model structure. At the same time, according to the relative error rate evaluation results, the frequency of the high-pass filter 1 on the main motor side in the low-coupling unit is set to 40kHz.

[0155] Fig.17The following is a schematic diagram of the impedance spectrum comparison results of the equivalent circuit of the low-coupling unit branch of the differential mode impedance of the main motor. The 10th-order vector matching parameter values ​​corresponding to the equivalent circuit are shown in Table 1. The simulation comparison results show that within the frequency range of 100Hz~30MHz, the impedance model established has good consistency with the test results in amplitude and phase.

[0156] Table 1:

[0157] In the embodiment of the present invention, by defining the main motor and the exciter as a differential mode two-port network and a common mode two-port network respectively, according to the mathematical equation of the two-port network, the Z parameter matrix of the main motor and the exciter is obtained, according to the mutual conversion relationship between the two-port network Z parameter and the T parameter, the impedance coupling model of the cascaded three-stage motor composed of the main motor and the exciter is established by using the T parameter, and the differential mode impedance and common mode impedance equivalent Z parameter matrix of the cascaded three-stage motor is obtained. According to the impedance coupling model of the cascaded three-stage motor established, the impedance coupling evaluation model of the cascaded three-stage motor is established, and according to the impedance coupling evaluation result of the system, the high-frequency impedance model structure of the three-stage motor based on the cascade coupling evaluation is established, and the circuit parameterization solution is performed. In this way, the cascade coupling structure of the three-stage motor is fully considered, the stator-rotor coupling and the impedance coupling association between the motors are realized, and the technical difficulty that the traditional motor high-frequency impedance modeling method cannot be directly used for the three-stage motor is made up, and the theoretical basis is provided for the simplification of the high-frequency model of the three-stage motor.

[0158] 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.

[0159] 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 three-stage motor high-frequency impedance modeling method based on cascade coupling evaluation, characterized in that: include: The main motor and the exciter are defined as a differential mode two-port network and a common mode two-port network respectively, wherein the differential mode two-port network is used to characterize the differential mode interference transmission path, and the common mode two-port network is used to characterize the common mode interference transmission path; According to the mathematical equation of the two-port network, the differential mode impedance Z parameter matrix and the common mode impedance Z parameter matrix of the main motor and the exciter are obtained respectively; According to the conversion relationship between the two-port network Z parameters and T parameters, the differential mode impedance Z parameter matrix and the common mode impedance Z parameter matrix of the main motor and the exciter are respectively converted into T parameter matrices, and based on the cascade equivalent relationship of the T parameter matrix, the differential mode impedance equivalent T parameter matrix and the common mode impedance equivalent T parameter matrix of the cascaded three-stage motor composed of the main motor and the exciter are obtained, and then the differential mode impedance equivalent T parameter matrix and the common mode impedance equivalent T parameter matrix are respectively converted into the differential mode impedance equivalent Z parameter matrix and the common mode impedance equivalent Z parameter matrix of the cascaded three-stage motor; Based on the obtained differential mode impedance equivalent Z parameter matrix and common mode impedance equivalent Z parameter matrix of the cascaded three-stage motor, calculate the impedance relative error rate caused by ignoring the impedance coupling of the cascaded motor; According to the comparison result of the relative error rate and the preset reference error rate, a three-stage motor high-frequency impedance model structure based on cascade coupling evaluation is established, and the equivalent circuit parameters are solved by a circuit parameterization method.

2. The method according to claim 1, characterized in that The mathematical equation of the two-port network based on the Z parameter is expressed as: ； in, Represents the input port of a two-port network and The input port voltage between Represents the output port of a two-port network and The output port voltage between represents the input port current flowing through the input port, represents the output port current flowing through the output port, and the Z parameter matrix describes the relationship between the input / output port voltage and the input / output port current, which is expressed as: ； in, represents the input impedance of the two-port network, represents the output impedance of the two-port network, and represents the transfer impedance of the two-port network.

3. The method according to claim 2, characterized in that The differential mode impedance Z parameter matrix and the common mode impedance Z parameter matrix of the main motor and the exciter are respectively expressed as: ； in, is the main motor differential mode impedance Z parameter matrix, is the main motor common mode impedance Z parameter matrix, is the exciter differential mode impedance Z parameter matrix, is the exciter common mode impedance Z parameter matrix.

4. The method according to claim 3, characterized in that The conversion relationship between the two-port network Z parameter and T parameter is expressed as: 。 5. The method according to claim 4, characterized in that The T parameter matrix describes the relationship between the voltage / current at the input port and the voltage / current at the output port of a two-port network. The two-port network is represented by a mathematical equation based on the T parameter description: ； The cascade equivalent relationship based on the T parameter matrix is ​​used to obtain the differential mode impedance equivalent T parameter matrix and the common mode impedance equivalent T parameter matrix of the cascaded three-stage motor composed of the main motor and the exciter, including: According to the T parameter equation of the two-port network, a cascaded two-port network corresponding to the cascaded three-stage motor composed of the main motor and the exciter is obtained; the cascaded two-port network includes a two-port network 1 and a two-port network 2, and the two output ports of the two-port network 1 are respectively connected to the two input ports of the two-port network 2; the cascaded two-port network satisfies the following expression: ； in, represents the input port voltage of the two-port network, represents the input port current of the two-port network, represents the output port voltage of the two-port network, represents the output port current of the two-port network, represents the input port voltage of the two-port network, represents the input port current of the two-port network, represents the output port voltage of the two-port network, represents the output port current of the two-port network, and is the T parameter matrix of the cascaded two-port network 1 and the two-port network 2; Wherein, the cascaded two-port network satisfies , ; Therefore, the cascaded two-port network further satisfies the following expression: ； The cascaded two-port network is equivalent to a new two-port network, and the equivalent T parameter matrix of the cascaded system Calculated by the following formula: ； According to the equivalent T parameter matrix equivalent method of the cascade system, the differential mode impedance equivalent T parameter matrix and the common mode impedance equivalent T parameter matrix of the cascaded three-stage motor composed of the main motor and the exciter are obtained, which are expressed as: ； in, is the differential mode impedance equivalent T parameter matrix of the cascaded three-stage motor, is the common-mode impedance equivalent T parameter matrix of the cascaded three-stage motor, is the main motor differential mode impedance T parameter matrix, is the exciter differential mode impedance T parameter matrix, is the parameter matrix of the main motor common mode impedance T, is the exciter common mode impedance T parameter matrix; Through the conversion relationship between the two-port network T parameters and Z parameters, the differential mode impedance equivalent T parameter matrix and the common mode impedance equivalent T parameter matrix of the cascaded three-stage motor are converted into the differential mode impedance equivalent Z parameter matrix and the common mode impedance equivalent Z parameter matrix. The conversion relationship between the two-port network T parameters and Z parameters is expressed as: 。 6. The method according to claim 5, characterized in that The step of calculating the impedance relative error rate caused by ignoring the impedance coupling of the cascaded motor based on the obtained differential mode impedance equivalent Z parameter matrix and common mode impedance equivalent Z parameter matrix of the cascaded three-stage motor comprises: According to the differential mode impedance equivalent Z parameter matrix and the common mode impedance equivalent Z parameter matrix, the three-stage motor impedance considering cascade coupling is obtained, which is expressed as: ； in, To consider the equivalent differential mode impedance of the main motor side when the cascade motor impedance coupling is used, To consider the equivalent differential mode impedance of the exciter side when the cascaded motor impedance coupling is used, To consider the equivalent common mode impedance of the main motor side when the cascade motor impedance coupling is used, To consider the equivalent common mode impedance of the exciter side when the cascaded motor impedance coupling is used, is the differential mode impedance equivalent Z parameter matrix of the cascaded three-stage motor, is the common mode impedance equivalent Z parameter matrix of the cascaded three-stage motor; According to the obtained three-stage motor impedance, the impedance relative error rate caused by ignoring the cascade motor impedance coupling is calculated, which is expressed as: ； in, The relative error rate of the differential mode impedance of the main motor caused by ignoring the impedance coupling of the cascaded motor is: To ignore the relative error rate of the differential mode impedance of the exciter caused by the impedance coupling of the cascaded motor, The relative error rate of the main motor common mode impedance caused by ignoring the impedance coupling of the cascaded motor is: The relative error rate of the common-mode impedance of the exciter caused by ignoring the impedance coupling of the cascaded motor.

7. The method according to claim 6, characterized in that According to the comparison result between the relative error rate and the preset reference error rate, a three-stage motor high-frequency impedance model structure based on cascade coupling evaluation is established, including: When the relative error rate is lower than the preset reference error rate in the entire frequency band, the impedance coupling between the three-stage motors is ignored, the main motor and the exciter are regarded as two independent motors for high-frequency impedance modeling analysis, and a low-coupling unit part is selected from the constructed three-stage motor high-frequency impedance model structure based on cascade coupling evaluation as its equivalent circuit model structure; at this time, the equivalent circuit model structure only includes the stator winding impedance branches of the main motor and the exciter, and does not consider the impedance coupling between the cascaded three-stage motors. The differential mode and / or common mode analysis only considers the stator impedance of the main motor and the stator impedance of the exciter; When the relative error rate is higher than the preset reference error rate in the entire frequency band, a high coupling unit part is selected from the constructed three-stage motor high-frequency impedance model structure based on cascade coupling evaluation as its equivalent circuit model structure; at this time, the equivalent circuit model structure adopts a T-type equivalent circuit structure to be equivalent to the established cascade equivalent two-port network differential mode impedance equivalent Z parameter matrix and common mode impedance equivalent Z parameter matrix; When the relative error rate is higher than the preset reference error rate in the low frequency band and lower than the preset reference error rate in the high frequency band, a hybrid model structure in which a low coupling unit part and a high coupling unit part are connected in parallel is selected from the constructed three-stage motor high-frequency impedance model structure based on cascade coupling evaluation as its equivalent circuit model structure; wherein the high coupling unit part is used to consider the low-frequency impedance coupling characteristics between the three-stage motors with a higher error rate, and a high-pass filter is added to the low coupling unit part to prevent the impedance influence of the high coupling unit; the frequency of the filter is determined by the impedance error evaluation result; The method of solving the equivalent circuit parameters by circuit parameterization includes: calculating the impedance of each branch in the equivalent circuit model structure according to the impedance extraction result, and solving the equivalent circuit parameter value by using the vector matching circuit parameterization method.

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