A small signal modeling method, device, electronic device and medium for a three-phase LLC resonant converter based on model reduction

Abstract

The present application discloses a small signal modeling method, device, electronic device and medium of a three-phase LLC resonant converter based on model reduction, which belongs to the technical field of DC / DC converters. Applied to a three-phase LLC resonant converter, the method includes: modeling according to the elements and state quantities in the three-phase LLC resonant converter to obtain a high-order small signal model of each resonant cavity; based on the resonant cavity of the three-phase LLC resonant converter, the high-order small signal model is reduced in the frequency domain to obtain a low-order small signal model of the three-phase LLC resonant converter; according to the low-order small signal model, the state space equation of the three-phase LLC resonant converter is determined; according to the transfer function calculated by the state space equation, a Bode diagram is drawn to evaluate the low-order small signal model. The method reduces the complexity and order of the model. Under the premise of selecting the bandwidth of the three-phase LLC resonant converter in the medium and low frequency bands, the obtained low-order small signal model can better match the simulation results in the medium and low frequency bands of the three-phase LLC resonant converter, accurately reflects the actual dynamic characteristics of the three-phase LLC resonant converter, and can guide the parameter design of the closed-loop control system of the three-phase LLC resonant converter.

Description

Technical Field

[0001] The present application belongs to the technical field of DC / DC converters, and in particular relates to a small signal modeling method, device, electronic device and medium for a three-phase LLC resonant converter based on model reduction. Background Art

[0002] In modern power electronics technology, the establishment and analysis of the converter's small signal model is of great significance to the controller parameter design, especially for complex systems such as resonant converters. Traditionally, the method for establishing small signal models mainly relies on the state space averaging method, but the premise of this method is not applicable to resonant converters controlled by variable frequency. The extended description function method can take into account any number of harmonics, but the modeling process for multi-element resonant converters is still very complicated. The equivalent model method reduces the complexity of small signal modeling of resonant converters by simplifying the complex resonant cavity into an equivalent circuit.

[0003] For high-power charging piles, three-phase LLC resonant converters have been widely used in engineering due to their high power density and low output current ripple. However, in the process of modeling three-phase LLC resonant converters, especially systems with three or more resonant elements, the equivalent model method has high complexity and high order, making it difficult to analyze and understand the dynamic characteristics of the converter and the influence of circuit parameters.

[0004] A small signal modeling method is urgently needed to reduce the complexity and order of the model and accurately reflect the actual dynamic characteristics of the three-phase LLC resonant converter. Summary of the invention

[0005] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a small signal modeling method, device, electronic device and medium of a three-phase LLC resonant converter based on model order reduction, which reduces the complexity and order of the model. Under the premise of selecting the bandwidth of the three-phase LLC resonant converter in the medium and low frequency bands, the obtained low-order small signal model can better match the simulation results in the medium and low frequency bands of the three-phase LLC resonant converter, accurately reflects the actual dynamic characteristics of the three-phase LLC resonant converter, and can guide the parameter design of the closed-loop control system of the three-phase LLC resonant converter.

[0006] In a first aspect, the present application provides a small signal modeling method for a three-phase LLC resonant converter based on model order reduction, which is applied to a three-phase LLC resonant converter. The method comprises:

[0007] Modeling is performed based on the components and state quantities in the three-phase LLC resonant converter to obtain a high-order small signal model of each resonant cavity;

[0008] Based on the resonant cavity of the three-phase LLC resonant converter, the high-order small signal model is reduced in frequency domain to obtain a low-order small signal model of the three-phase LLC resonant converter;

[0009] Determining a state space equation of the three-phase LLC resonant converter according to the low-order small signal model;

[0010] Based on the transfer function calculated from the state-space equation, a Bode plot is plotted to evaluate the low-order small signal model.

[0011] According to one embodiment of the present application, based on the resonant cavity of the three-phase LLC resonant converter, the high-order small signal model is reduced to obtain a low-order small signal model of the three-phase LLC resonant converter, including:

[0012] The capacitor parallel branch in the high-order small signal model corresponding to each resonant cavity is equivalent to a series branch;

[0013] The series branches are merged, and the excitation inductance and the resonant inductance branches are merged to obtain the low-order small signal model.

[0014] According to one embodiment of the present application, the following relationship exists in the low-order small signal model:

[0015]

[0016] Among them, R s is the equivalent series impedance of the resonant inductor Lr and the resonant capacitor Cr; ω s is the switching angular frequency; L r is the resonant inductance; C r is the resonant capacitor size; L m is the excitation inductance; σ and L2 are intermediate variables.

[0017] According to one embodiment of the present application, the state space equation is:

[0018]

[0019] Among them, x is the state variable, is the derivative of the state variable, u is the input quantity, y is the output quantity, A is the system matrix of the three-phase LLC resonant converter, B is the input matrix, and C is the output matrix.

[0020] According to one embodiment of the present application, drawing a Bode diagram according to the transfer function calculated by the state-space equation to evaluate the low-order small signal model includes:

[0021] According to the state space equation, the transfer function from switching frequency to output voltage after reduction is obtained;

[0022] Solving the transfer function to obtain a frequency response to draw the Bode diagram;

[0023] Based on the Bode diagram, when it is determined that the degree of matching between the frequency response characteristics of the low-order small signal model and the theoretical expectation reaches a preset condition, the accuracy verification of the low-order small signal model is passed.

[0024] According to an embodiment of the present application, the modeling is performed according to the elements and state quantities in the three-phase LLC resonant converter to obtain a high-order small signal model of each resonant cavity, including:

[0025] Determining a fundamental wave vector and an average value of the state quantity based on the input-output characteristics of each resonant cavity of the three-phase LLC resonant converter;

[0026] Based on the fundamental wave vector, a small signal disturbance superposition is performed, and a small signal model of each resonant cavity is obtained according to the corresponding relationship between the steady-state components of the circuit parameters;

[0027] Based on the small signal model of the resonant cavity, determining an inductance small signal model and a capacitance small signal model;

[0028] Based on the inductor small signal model and the capacitor small signal model, the steady-state values ​​of related state quantities are solved to obtain the high-order small signal model.

[0029] According to one embodiment of the present application, the small signal model of each resonant cavity is obtained based on the following steps:

[0030] Expanding the real and imaginary parts of the fundamental wave components in the fundamental wave vector and superimposing a small signal disturbance to obtain a nonlinear vector;

[0031] Performing a first-order Taylor expansion on the nonlinear vector and retaining a first-order linear term;

[0032] Based on the first-order linear term, the steady-state components in the state quantity are eliminated according to the relative relationship between the steady-state components of the circuit parameters, so as to obtain a small signal model of each resonant cavity.

[0033] In a second aspect, the present application provides a small signal modeling device for a three-phase LLC resonant converter based on model order reduction, which is applied to a three-phase LLC resonant converter, and the device includes:

[0034] A first processing module is used to perform modeling according to the components and state quantities in the three-phase LLC resonant converter to obtain a high-order small signal model of each resonant cavity;

[0035] A second processing module is used to perform order reduction processing on the high-order small signal model in the frequency domain based on the resonant cavity of the three-phase LLC resonant converter to obtain a low-order small signal model of the three-phase LLC resonant converter;

[0036] A third processing module, configured to determine a state space equation of the three-phase LLC resonant converter according to the low-order small signal model;

[0037] The fourth processing module is used to draw a Bode diagram according to the transfer function calculated by the state-space equation to evaluate the low-order small signal model.

[0038] In a third aspect, the present application provides an electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the small signal modeling method of the three-phase LLC resonant converter based on model order reduction as described in the first aspect above is implemented.

[0039] In a fourth aspect, the present application provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the small signal modeling method of a three-phase LLC resonant converter based on model reduction as described in the first aspect above.

[0040] In a fifth aspect, the present application provides a chip, comprising a processor and a communication interface, wherein the communication interface is coupled to the processor, and the processor is used to run a program or instruction to implement the small signal modeling method of a three-phase LLC resonant converter based on model reduction as described in the first aspect.

[0041] In a sixth aspect, the present application provides a computer program product, including a computer program, which, when executed by a processor, implements the small signal modeling method of a three-phase LLC resonant converter based on model order reduction as described in the first aspect above.

[0042] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application.

[0043] The present application provides a small signal modeling method, device, electronic device and medium for a three-phase LLC resonant converter based on model reduction, which has the following beneficial effects compared with the prior art:

[0044] (1) By reducing the order of the single-phase resonant cavity in the frequency domain, the complexity and order of the model are reduced while ensuring the accuracy of modeling. This can intuitively reflect the influence of circuit parameters on the dynamic characteristics of the three-phase LLC resonant converter. Under the premise of selecting the bandwidth of the three-phase LLC resonant converter in the medium and low frequency bands, the obtained low-order small signal model can better match the simulation results in the medium and low frequency bands of the three-phase LLC resonant converter, accurately reflecting the actual dynamic characteristics of the three-phase LLC resonant converter, and can guide the parameter design of the closed-loop control system of the three-phase LLC resonant converter.

[0045] (2) The premise of system reduction is that the disturbance frequency is much smaller than the switching frequency. Therefore, from the Bode plot analysis, the simplified model in the low frequency band and the system Bode plot obtained by simulation can be well matched. For traditional PWM converters, the bandwidth of the control system is usually 1 / 5 to 1 / 10 of the switching frequency. For LLC resonant converters working at high frequencies, the available bandwidth range is relatively wider. This simplified model can guide the parameter design of the three-phase LLC resonant converter to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0047] Figure 1 This is one of the flow charts of a small signal modeling method of a three-phase LLC resonant converter based on model order reduction provided in an embodiment of the present application;

[0048] Figure 2 It is a topological structure diagram of a three-phase LLC resonant converter with a resonant cavity YY connection provided in an embodiment of the present application;

[0049] Figure 3 : is a single-phase topological structure diagram equivalent to the three-phase LLC resonant converter provided in the embodiment of the present application;

[0050] Figure 4 It is a structural schematic diagram of an equivalent small signal model of an inductor and capacitor element obtained by the equivalent circuit method provided in an embodiment of the present application;

[0051] Figure 5 It is a structural schematic diagram of an inductor equivalent small signal model in the real number domain provided in an embodiment of the present application;

[0052] Figure 6 is a structural schematic diagram of a capacitor equivalent small signal model in the real number domain provided in an embodiment of the present application;

[0053] Figure 7 It is a structural schematic diagram of a capacitor equivalent series small signal model provided in an embodiment of the present application;

[0054] Figure 8 It is a structural schematic diagram of a low-order small signal equivalent model of a system in the real number domain provided by an embodiment of the present application;

[0055] Fig. 9 It is one of the Bode diagrams of the system under different working conditions obtained through examples provided in the embodiments of the present application;

[0056] Fig.10 This is the second Bode diagram of the system under different working conditions obtained through examples provided in the embodiment of the present application;

[0057] Fig.11 This is the third Bode diagram of the system under different working conditions obtained through examples provided in the embodiment of the present application;

[0058] Fig.12 It is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0059] The following will be combined with the drawings in the embodiments of the present application to clearly describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments in the present application belong to the scope of protection of this application.

[0060] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0061] In combination with the accompanying drawings, a small signal modeling method of a three-phase LLC resonant converter based on model order reduction, a small signal modeling device of a three-phase LLC resonant converter based on model order reduction, an electronic device and a readable storage medium provided in an embodiment of the present application are described in detail through specific embodiments and their application scenarios.

[0062] Among them, the small signal modeling method of the three-phase LLC resonant converter based on model reduction can be applied to the terminal, and can be specifically executed by hardware or software in the terminal.

[0063] The terminal includes, but is not limited to, a portable communication device such as a mobile phone or tablet computer with a touch-sensitive surface (e.g., a touch screen display and / or a touch pad). It should also be understood that in some embodiments, the terminal may not be a portable communication device, but a desktop computer with a touch-sensitive surface (e.g., a touch screen display and / or a touch pad).

[0064] In the following various embodiments, a terminal including a display and a touch-sensitive surface is described. However, it should be understood that the terminal may include one or more other physical user interface devices such as a physical keyboard, a mouse and a joystick.

[0065] An embodiment of the present application provides a small-signal modeling method for a three-phase LLC resonant converter based on model order reduction. The executor of the small-signal modeling method for a three-phase LLC resonant converter based on model order reduction may be an electronic device or a functional module or functional entity in the electronic device that can implement the small-signal modeling method for a three-phase LLC resonant converter based on model order reduction. The electronic devices mentioned in the embodiment of the present application include but are not limited to mobile phones, tablet computers, computers, cameras, and wearable devices. The small-signal modeling method for a three-phase LLC resonant converter based on model order reduction provided in the embodiment of the present application is described below using an electronic device as an example of the executor.

[0066] The method is applied to a three-phase LLC resonant converter.

[0067] like Figure 1 As shown, the small signal modeling method of the three-phase LLC resonant converter based on model order reduction includes:

[0068] Step 110: Modeling is performed according to the components and state quantities in the three-phase LLC resonant converter to obtain a high-order small signal model of each resonant cavity;

[0069] Step 120: Based on the resonant cavity of the three-phase LLC resonant converter, the high-order small signal model is reduced in frequency domain to obtain a low-order small signal model of the three-phase LLC resonant converter;

[0070] Step 130: Determine the state space equation of the three-phase LLC resonant converter according to the low-order small signal model;

[0071] Step 140: Draw a Bode diagram based on the transfer function calculated by the state-space equation to evaluate the low-order small signal model.

[0072] Among them, the resonant cavity is a resonant circuit composed of components such as L and C.

[0073] like Figure 2As shown, the three-phase YY-connected three-phase LLC resonant converter includes components such as a power switch, an LLC resonant circuit, a transformer, an output filter, an auxiliary power supply and a control circuit. For the three-phase YY-connected three-phase LLC resonant converter with completely consistent three-phase parameters, when performing small signal modeling of the three-phase LLC resonant converter, only the input and output characteristics of a single resonant cavity need to be considered.

[0074] State quantities are physical quantities used to describe the state of a circuit when analyzing a circuit, including voltage, current, power, and frequency.

[0075] Components are used to complete power conversion, control and filtering, and state quantities are used to describe the dynamic behavior of the circuit. Components and state quantities together determine the operating performance, efficiency and control strategy of the converter.

[0076] In some embodiments, the modeling is performed according to the elements and state quantities in the three-phase LLC resonant converter to obtain a high-order small signal model of each resonant cavity, including:

[0077] Determining a fundamental wave vector and an average value of the state quantity based on the input-output characteristics of each resonant cavity of the three-phase LLC resonant converter;

[0078] Based on the fundamental wave vector, a small signal disturbance superposition is performed, and a small signal model of each resonant cavity is obtained according to the corresponding relationship between the steady-state components of the circuit parameters;

[0079] Based on the small signal model of the resonant cavity, determining an inductance small signal model and a capacitance small signal model;

[0080] Based on the inductor small signal model and the capacitor small signal model, the steady-state values ​​of related state quantities are solved to obtain the high-order small signal model.

[0081] like Figure 3 As shown, v AB As the reference phase, the fundamental phasor and average value expressions of each component and state quantity are obtained as follows:

[0082]

[0083]

[0084] Among them, combined Figure 3 , Represents the resonant cavity input voltage, i.e. the bridge arm voltage v AB The fundamental component of Represents the fundamental component of the resonant current i1, I in Indicates the input current i in The average value of It represents the fundamental component of i2 after the secondary current is equivalent to the primary current. Represents the transformer primary voltage v P The fundamental component, I o Indicates the output current i o The average value of the variable, the subscript r represents the real part of the variable, i represents the imaginary part of the variable, and m represents the amplitude of the variable. In addition, V in Indicates input voltage, V o represents the output voltage, n represents the transformer ratio, I o Represents the output current, express Hysteresis The phase angle, express Hysteresis The phase angle, express Hysteresis The phase angle.

[0085] In some embodiments, the small signal model of each resonant cavity is obtained based on the following steps:

[0086] Expanding the real and imaginary parts of the fundamental wave components in the fundamental wave vector and superimposing a small signal disturbance to obtain a nonlinear vector;

[0087] Performing a first-order Taylor expansion on the nonlinear vector and retaining a first-order linear term;

[0088] Based on the first-order linear term, the steady-state components in the state quantity are eliminated according to the relative relationship between the steady-state components of the circuit parameters, so as to obtain a small signal model of each resonant cavity.

[0089] Superimpose a small signal disturbance on the above state variables, for example: Represents a small signal disturbance on the input voltage.

[0090] In actual implementation, the fundamental component of the transformer primary voltage is Expand the real and imaginary parts to get v P1r 、v P1i , after superimposing a small signal disturbance v P1r 、v P1i ,I o The first-order Taylor expansion of equal nonlinear quantities is performed to obtain the first-order linear terms, and the nonlinear three-phase LLC resonant converter is approximated as a linear system to simplify the analysis of steady-state response and reduce the influence of complex high-order harmonics, thereby extracting the fundamental response of the multi-resonance element.

[0091] like Figure 4 As shown, after extracting the fundamental response of the multi-resonance element according to the first-order linear term, according to the relative relationship between the steady-state components of the circuit parameters, the steady-state components in the state quantity are eliminated to obtain the small signal model of each resonant cavity as follows:

[0092]

[0093] in, It is V in The amount of superimposed disturbance, Yes The amount of superimposed disturbance, to I in The amount of superimposed disturbance, Yes The amount of superimposed disturbance, Yes The disturbance amount superimposed after real part expansion is: Respectively The disturbances that are superimposed after the real and imaginary parts are expanded are: It is V o The amount of superimposed disturbance, Respectively The disturbances that are superimposed after the real and imaginary parts are expanded are: Yes o The amount of superimposed disturbance.

[0094]

[0095] like Figure 5 As shown, similarly, based on the fundamental wave approximation and the introduction of small signal disturbance, the small signal model of the inductor is as follows:

[0096]

[0097] Among them, ω s is the switching angular frequency.

[0098] like Figure 6 As shown, the small signal model of the capacitor is as follows:

[0099]

[0100] The steady-state values ​​of other related state quantities are solved through the single-phase topological structure, and the expressions are as follows:

[0101]

[0102] The solution methods for other steady-state currents are similar, where R e ' q is the load equivalent to the primary side of the rectifier network, and its expression is:

[0103]

[0104] Where n is the transformer ratio, V o is the output voltage, Po is the output power.

[0105] The high-order small signal equivalent model of the three-phase LLC resonant converter in the real domain still contains 7 energy storage elements such as inductors and capacitors. The order of the three-phase LLC resonant converter reaches 7, which is not conducive to analysis and controller parameter design.

[0106] In this embodiment, model reduction is performed based on the extended describing function method or the equivalent model method, and only the fundamental component is considered. Therefore, the analysis of the working condition at the resonance point is the most accurate. There are certain errors in the working conditions at other frequency points, but they are within an acceptable range.

[0107] In some embodiments, based on the resonant cavity of the three-phase LLC resonant converter, the high-order small signal model is reduced to obtain a low-order small signal model of the three-phase LLC resonant converter, including:

[0108] The capacitor parallel branch in the high-order small signal model corresponding to each resonant cavity is equivalent to a series branch;

[0109] The series branches are merged, and the excitation inductance and the resonant inductance branches are merged to obtain the low-order small signal model.

[0110] In some embodiments, the low-order small signal model has the following relationship:

[0111]

[0112] Among them, R s is the equivalent series impedance of the resonant inductor Lr and the resonant capacitor Cr; ω s is the switching angular frequency; L r is the resonant inductance; C r is the resonant capacitor size; L m is the excitation inductance; σ and L2 are intermediate variables.

[0113] like Figure 7 As shown, assuming that the disturbance frequency is much smaller than the switching frequency, the capacitor parallel branch is equivalent to the series branch by using the equivalent transformation of the Norton branch and the Thevenin branch. The impedance of the Norton branch can be equivalent to:

[0114]

[0115] Among them, ω m is the disturbance frequency.

[0116] After merging the series branches, the excitation inductance and the resonant inductance branches are still merged by using the equivalent transformation of the Norton branch and the Thevenin branch to obtain the low-order small signal model of the three-phase LLC resonant converter in the real domain, as shown in Figure 8As shown, the following relationship exists:

[0117]

[0118] In some embodiments, the state space equation is:

[0119]

[0120] Among them, x is the state variable, is the derivative of the state variable, u is the input quantity, y is the output quantity, A is the system matrix of the three-phase LLC resonant converter, B is the input matrix, and C is the output matrix.

[0121] The state space expression of the three-phase LLC resonant converter is obtained based on the low-order small signal model and satisfies the following relationship:

[0122]

[0123] C=

[001]

[0124] In some embodiments, based on the state-space equation, analyzing and verifying the low-order small signal model to determine the system bandwidth of the three-phase LLC resonant converter includes:

[0125] According to the state space equation, the transfer function from switching frequency to output voltage after reduction is obtained;

[0126] Solving the transfer function to obtain a frequency response to draw the Bode diagram;

[0127] Based on the Bode diagram, when it is determined that the degree of matching between the frequency response characteristics of the low-order small signal model and the theoretical expectation reaches a preset condition, the accuracy verification of the low-order small signal model is passed.

[0128] In actual implementation, the state space equation is transformed to obtain the transfer function formula from switching frequency to output voltage after reduction as follows:

[0129]

[0130] This is used to analyze the characteristics of the three-phase LLC resonant converter.

[0131] By solving the transfer function, the frequency response of the three-phase LLC resonant converter can be obtained. By drawing the Bode plot, the frequency response characteristics of the low-order small signal model can be analyzed to verify the accuracy of the low-order small signal model within a specific frequency range.

[0132] When it is determined that the matching degree between the frequency response characteristics of the low-order small signal model and the theoretical expectation reaches a preset condition, the accuracy verification of the low-order small signal model is passed.

[0133] The preset condition may be that the low-order small signal model satisfies the gain amplitude consistency, phase response consistency, frequency response characteristic consistency, amplitude and phase amplitude characteristics consistency with theoretical expectations, and the error is within a preset error range.

[0134] The low-order small signal model that has passed the accuracy verification can be used to guide the parameter design of the closed-loop control system of the three-phase LLC resonant converter. Since the reduced-order model has a good fit in the low and medium frequency bands, the low-order small signal model has a certain reference value in the design of some parameters such as system bandwidth in the subsequent design.

[0135] Based on the above analysis, the Bode diagram of the transfer function from switching frequency to output voltage and even the transfer function of the rest of the system is obtained to guide the controller parameter design.

[0136] In the actual implementation, a 30kW three-phase LLC resonant converter applied to a charging pile is used as the background, and a specific example is given to verify the accuracy of the simplified small signal model. The specific parameters are as follows: L r =9.537μH,C r =118.05nF, L m =42.914μH, f r =150kHz, n=1.3.

[0137] like Figure 9-11 As shown in the figure, the system Bode diagrams obtained by simulation and simplified model at the resonance point, over-resonance and under-resonance when the load is 20Ω, respectively. Fig. 9 In the case of fs=fr=150kHz, Vin=430V, Fig.10 In the case of fs=120kHz, Vin=430V, Fig.11 In the example, fs=180kHz, Vin=430V.

[0138] In this embodiment, the theoretical analysis of the system under the resonance point condition shows that the resonance peak amplitude is relatively large, but in actual work, the resonance peak is suppressed to a certain extent due to the constraints of circuit parasitic parameters and the equivalent ESR of the output capacitor.

[0139] The premise of system reduction is that the disturbance frequency is much smaller than the switching frequency. Therefore, from the Bode plot analysis, the simplified model in the low frequency band and the system Bode plot obtained by simulation can be well matched. For traditional PWM converters, the bandwidth of the control system is usually 1 / 5 to 1 / 10 of the switching frequency. For LLC resonant converters working at high frequencies, the available bandwidth range is relatively wider. This simplified model can guide the parameter design of the three-phase LLC resonant converter to a certain extent.

[0140] According to the small signal modeling method of the three-phase LLC resonant converter based on model order reduction provided in the embodiment of the present application, by reducing the order of the single-phase resonant cavity in the frequency domain, the complexity and order of the model are reduced while ensuring the accuracy of modeling, and the influence of circuit parameters on the dynamic characteristics of the three-phase LLC resonant converter can be intuitively reflected. A reasonable system bandwidth is selected through the state-space equation. On the premise of selecting the bandwidth of the three-phase LLC resonant converter in the medium and low frequency bands, the obtained low-order small signal model can better match the simulation results in the medium and low frequency bands of the three-phase LLC resonant converter, accurately reflects the actual dynamic characteristics of the three-phase LLC resonant converter, and can guide the parameter design of the closed-loop control system of the three-phase LLC resonant converter.

[0141] The small signal modeling method of the three-phase LLC resonant converter based on model order reduction provided in the embodiment of the present application can be executed by a small signal modeling device of the three-phase LLC resonant converter based on model order reduction. In the embodiment of the present application, the small signal modeling method of the three-phase LLC resonant converter based on model order reduction is executed by the small signal modeling device of the three-phase LLC resonant converter based on model order reduction as an example to illustrate the small signal modeling device of the three-phase LLC resonant converter based on model order reduction provided in the embodiment of the present application.

[0142] The embodiment of the present application also provides a small signal modeling device for a three-phase LLC resonant converter based on model order reduction, the device comprising:

[0143] A first processing module is used to perform modeling according to the components and state quantities in the three-phase LLC resonant converter to obtain a high-order small signal model of each resonant cavity;

[0144] A second processing module is used to perform order reduction processing on the high-order small signal model in the frequency domain based on the resonant cavity of the three-phase LLC resonant converter to obtain a low-order small signal model of the three-phase LLC resonant converter;

[0145] A third processing module, configured to determine a state space equation of the three-phase LLC resonant converter according to the low-order small signal model;

[0146] The fourth processing module is used to draw a Bode diagram according to the transfer function calculated by the state-space equation to evaluate the low-order small signal model.

[0147] According to the small signal modeling device of the three-phase LLC resonant converter based on model order reduction provided in the embodiment of the present application, by reducing the order of the single-phase resonant cavity in the frequency domain, the complexity and order of the model are reduced while ensuring the accuracy of modeling, and the influence of circuit parameters on the dynamic characteristics of the three-phase LLC resonant converter can be intuitively reflected. On the premise of selecting the bandwidth of the three-phase LLC resonant converter in the medium and low frequency bands, the obtained low-order small signal model can better match the simulation results in the medium and low frequency bands of the three-phase LLC resonant converter, accurately reflects the actual dynamic characteristics of the three-phase LLC resonant converter, and can guide the parameter design of the closed-loop control system of the three-phase LLC resonant converter.

[0148] The small signal modeling device of the three-phase LLC resonant converter based on model reduction in the embodiment of the present application can be an electronic device, or a component in the electronic device, such as an integrated circuit or a chip. The electronic device can be a terminal, or other devices other than a terminal. Exemplarily, the electronic device can be a mobile phone, a tablet computer, a laptop computer, a PDA, a vehicle-mounted electronic device, a mobile Internet device (Mobile Internet Device, MID), an ultra-mobile personal computer (Ultra-Mobile Personal Computer, UMPC), etc., which is not specifically limited in the embodiment of the present application.

[0149] The small signal modeling device of the three-phase LLC resonant converter based on model reduction in the embodiment of the present application can be a device with an operating system. The operating system can be a Linux operating system, a Windows operating system, or other possible operating systems, which are not specifically limited in the embodiment of the present application.

[0150] The small signal modeling device of the three-phase LLC resonant converter based on model order reduction provided in the embodiment of the present application can realize the various processes implemented in the small signal modeling method embodiment of the three-phase LLC resonant converter based on model order reduction as in the above-mentioned embodiment. To avoid repetition, they will not be repeated here.

[0151] In some embodiments, Fig.12 As shown, an embodiment of the present application also provides an electronic device 1200, including a processor 1201, a memory 1202, and a computer program stored in the memory 1202 and executable on the processor 1201. When the program is executed by the processor 1201, each process of the embodiment of the small signal modeling method of the three-phase LLC resonant converter based on model reduction is implemented, and the same technical effect can be achieved. To avoid repetition, it will not be repeated here.

[0152] It should be noted that the electronic devices in the embodiments of the present application include the mobile electronic devices and non-mobile electronic devices mentioned above.

[0153] An embodiment of the present application also provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the various processes of the above-mentioned small signal modeling method embodiment of the three-phase LLC resonant converter based on model reduction are implemented, and the same technical effect can be achieved. To avoid repetition, it will not be repeated here.

[0154] The processor is the processor in the electronic device in the above embodiment. The readable storage medium includes a computer readable storage medium, such as a computer read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0155] An embodiment of the present application also provides a computer program product, including a computer program, which, when executed by a processor, implements the above-mentioned small signal modeling method of the three-phase LLC resonant converter based on model order reduction.

[0156] The processor is the processor in the electronic device in the above embodiment. The readable storage medium includes a computer readable storage medium, such as a computer read-only memory ROM, a random access memory RAM, a magnetic disk or an optical disk.

[0157] An embodiment of the present application further provides a chip, which includes a processor and a communication interface, which are coupled to the processor, and the processor is used to run programs or instructions to implement the various processes of the above-mentioned small signal modeling method embodiment of the three-phase LLC resonant converter based on model reduction, and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

[0158] It should be understood that the chip mentioned in the embodiments of the present application can also be called a system-level chip, a system chip, a chip system or a system-on-chip chip, etc.

[0159] It should be noted that, in this article, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises one..." does not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be noted that the scope of the method and device in the embodiment of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0160] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment method can be implemented by means of software plus a necessary general hardware platform, and of course it can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a computer software product, which is stored in a storage medium (such as ROM / RAM, disk, CD), including a number of instructions for a terminal (which can be a mobile phone, computer, server, or network device, etc.) to execute the small signal modeling method of the three-phase LLC resonant converter based on model reduction described in each embodiment of the present application.

[0161] In the description of this application, "first feature" or "second feature" may include one or more of the features.

[0162] In the description of the present application, “plurality” means two or more.

[0163] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

[0164] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0165] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A small signal modeling method for a three-phase LLC resonant converter based on model order reduction, characterized in that: Applied to a three-phase LLC resonant converter, the method comprises: Modeling is performed based on the components and state quantities in the three-phase LLC resonant converter to obtain a high-order small signal model of each resonant cavity; Based on the resonant cavity of the three-phase LLC resonant converter, the high-order small signal model is reduced in frequency domain to obtain a low-order small signal model of the three-phase LLC resonant converter; Determining a state space equation of the three-phase LLC resonant converter according to the low-order small signal model; Based on the transfer function calculated from the state-space equation, a Bode plot is plotted to evaluate the low-order small signal model.

2. The small signal modeling method of a three-phase LLC resonant converter based on model order reduction according to claim 1, characterized in that: Based on the resonant cavity of the three-phase LLC resonant converter, the high-order small signal model is reduced to obtain a low-order small signal model of the three-phase LLC resonant converter, including: The capacitor parallel branch in the high-order small signal model corresponding to each resonant cavity is equivalent to a series branch; The series branches are merged, and the excitation inductance and the resonant inductance branches are merged to obtain the low-order small signal model.

3. The small signal modeling method of a three-phase LLC resonant converter based on model order reduction according to claim 2, characterized in that: The following relationship exists in the low-order small signal model: Among them, R s is the equivalent series impedance of the resonant inductor Lr and the resonant capacitor Cr; ω s is the switching angular frequency; L r is the resonant inductance; C r is the resonant capacitor size; L m is the excitation inductance; σ and L2 are intermediate variables.

4. The small signal modeling method of a three-phase LLC resonant converter based on model order reduction according to claim 1, characterized in that: The state space equation is: Among them, x is the state variable, is the derivative of the state variable, u is the input quantity, y is the output quantity, A is the system matrix of the three-phase LLC resonant converter, B is the input matrix, and C is the output matrix.

5. The small signal modeling method of a three-phase LLC resonant converter based on model order reduction according to claim 1, characterized in that: Based on the transfer function calculated by the state-space equation, a Bode plot is plotted to evaluate the low-order small signal model, including: According to the state space equation, the transfer function from switching frequency to output voltage after reduction is obtained; Solving the transfer function to obtain a frequency response to draw the Bode diagram; Based on the Bode diagram, when it is determined that the degree of matching between the frequency response characteristics of the low-order small signal model and the theoretical expectation reaches a preset condition, the accuracy verification of the low-order small signal model is passed.

6. The small signal modeling method of a three-phase LLC resonant converter based on model order reduction according to claim 1, characterized in that: The modeling is performed based on the components and state quantities in the three-phase LLC resonant converter to obtain a high-order small signal model of each resonant cavity, including: Determining a fundamental wave vector and an average value of the state quantity based on the input-output characteristics of each resonant cavity of the three-phase LLC resonant converter; Based on the fundamental wave vector, a small signal disturbance superposition is performed, and a small signal model of each resonant cavity is obtained according to the corresponding relationship between the steady-state components of the circuit parameters; Based on the small signal model of the resonant cavity, determining an inductance small signal model and a capacitance small signal model; Based on the inductor small signal model and the capacitor small signal model, the steady-state values ​​of related state quantities are solved to obtain the high-order small signal model.

7. The small signal modeling method of a three-phase LLC resonant converter based on model order reduction according to claim 6, characterized in that: The small signal model of each resonant cavity is obtained based on the following steps: Expanding the real and imaginary parts of the fundamental wave components in the fundamental wave vector and superimposing a small signal disturbance to obtain a nonlinear vector; Performing a first-order Taylor expansion on the nonlinear vector and retaining a first-order linear term; Based on the first-order linear term, the steady-state components in the state quantity are eliminated according to the relative relationship between the steady-state components of the circuit parameters, so as to obtain a small signal model of each resonant cavity.

8. A small signal modeling device for a three-phase LLC resonant converter based on model order reduction, characterized in that: Applied to a three-phase LLC resonant converter, the device comprises: A first processing module is used to perform modeling according to the components and state quantities in the three-phase LLC resonant converter to obtain a high-order small signal model of each resonant cavity; A second processing module is used to perform order reduction processing on the high-order small signal model in the frequency domain based on the resonant cavity of the three-phase LLC resonant converter to obtain a low-order small signal model of the three-phase LLC resonant converter; A third processing module, configured to determine a state space equation of the three-phase LLC resonant converter according to the low-order small signal model; The fourth processing module is used to draw a Bode diagram according to the transfer function calculated by the state-space equation to evaluate the low-order small signal model.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the small signal modeling method of the three-phase LLC resonant converter based on model order reduction as described in any one of claims 1 to 7 is implemented.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the small signal modeling method of the three-phase LLC resonant converter based on model order reduction as described in any one of claims 1 to 7 is implemented.

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