A two-way clllc state observation control method based on extended description function modeling

Abstract

The application discloses a bidirectional CLLLc state observation control method based on extended describing function modeling, belongs to the field of power electronic technology application, and is based on solving the wide voltage output of the bidirectional CLLLc converter and the output voltage stability problem under different load working conditions, and through the establishment of a bidirectional CLLLc harmonic equivalent circuit, the establishment of a large signal model by using an extended describing function, the approximate linearization of the model by using partial derivatives and steady-state solutions, the creation of a bidirectional CLLLc converter state observation equation, and the design of a controller, accurate control of the bidirectional CLLLc converter is realized. The state observation matrix of the application is related to the circuit topology and system control parameters, and therefore the bidirectional CLLLc converter state observation control method based on the extended describing function modeling is suitable for DC / DC conversion under various application scenarios, and under different degrees of load working conditions, the effect of stable output voltage is achieved.

Description

Technical Field

[0001] This invention belongs to the field of power electronics technology applications, specifically relating to a bidirectional CLLLC state observation and control method based on extended description function modeling. Background Technology

[0002] With the continuous development of technology, in order to solve the problem of unstable power generation in new energy systems such as photovoltaic and wind power, it is necessary to use energy storage systems to maintain stable power through bidirectional DC / DC converters. At the same time, bidirectional DC / DC converters have wide applications in electric vehicles, DC power distribution networks, aerospace power systems and other fields. There are many types of bidirectional DC / DC converter topologies, among which resonant DC / DC converters have good soft-switching characteristics.

[0003] Improving the efficiency and power density of bidirectional DC / DC converters, achieving a wide voltage regulation range and fast, smooth switching between forward and reverse energy transfer, and ensuring stable output voltage under different load conditions have become pressing issues for bidirectional DC / DC converters in recent years. To address this, a bidirectional CLLLC state observation control method based on extended describing function modeling is proposed. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a bidirectional CLLLC state observation and control method based on extended description function modeling, which solves the technical problem of output voltage variation under different load conditions in existing technologies.

[0005] The objective of this invention can be achieved through the following technical solution: a bidirectional CLLLC state observation control method based on extended description function modeling, comprising the following steps:

[0006] A large-signal model is generated by extending the describing function through a bidirectional CLLLC converter, and then state observation and control are performed based on the generated large-signal model.

[0007] Preferably, the large-signal model generated by the extended description function modeling of the bidirectional CLLLC converter consists of the equivalent circuit of the bidirectional CLLLC converter, the harmonic approximation, and the extended description function equation.

[0008] Preferably, the equivalent circuit of the bidirectional CLLLC converter is a circuit with an amplitude of V. ab The square wave voltage source replaces the full-bridge inverter circuit, and the rectifier circuit is equivalent to a combination of a controlled voltage source and a controlled current source. The equivalent series resistance of the output filter capacitor is r. o The transformer turns ratio is n:1. The nonlinear state equation of the equivalent circuit is as follows:

[0009]

[0010]

[0011]

[0012]

[0013]

[0014]

[0015] Where sgn is the sign function, and the positive or negative value of sgn represents the direction of the current flowing through the primary side of the transformer; L1 is the primary resonant inductance; L2 is the secondary resonant inductance; L... m Here, r1 is the magnetizing inductor, r2 is the equivalent resistance of inductor L2, C1 is the primary capacitance, C2 is the secondary capacitance, and C... o For the output filter capacitor, i1 and i2 are the inductor currents flowing through L1 and L2, respectively. m For flow through L m The inductor current, and The voltages across capacitors C1 and C2 are respectively, V Co V is the voltage across the output filter capacitor. o For the output voltage, R L To output equivalent load.

[0016] Preferably, the harmonics approximately comprise two parts:

[0017] The voltage across the nonlinear element and the current flowing through the nonlinear element are expressed using the fundamental approximation equation:

[0018] i1(t)=i 1s (t)sin(ωt)+i 1c (t)cos(ωt)

[0019] i m (t)=i ms (t)sin(ωt)+i mc (t)cos(ωt)

[0020] i2(t)=i 2s (t)sin(ωt)+i 2c (t)cos(ωt)

[0021]

[0022]

[0023] Where ω is the fundamental frequency, i 1s i1c i ms i mc i 2s i 2c , i1 and i m i2, The amplitudes of the sinusoidal and cosine components;

[0024] Differentiate the fundamental approximation equation:

[0025]

[0026]

[0027]

[0028]

[0029]

[0030] Preferably, the extended describing function equation comprises three parts:

[0031] The nonlinear term V ab ,sgn(i1-i m ),n|i1-i m | Written in fundamental form:

[0032] V ab =f1(d,v in sin(ωt)

[0033] sgn(i1-i m )=f2(i 1s -i ms i 1c -i mc sin(ωt) + f3(i 1s -i ms i 1c -i mc cos(ωt)

[0034] n|i1-i m |=nf4(i 1s -i ms i 1c -i mc )

[0035]

[0036]

[0037]

[0038]

[0039] in, V g For V ab Amplitude, v in V is the input sinusoidal voltage. es This represents the sinusoidal component of the output voltage of the full-bridge inverter circuit.

[0040] Substituting the fundamental form of the nonlinear term into the derivative form of the harmonic approximation equation:

[0041]

[0042]

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050]

[0051] The large-signal model of the bidirectional CLLLC converter is obtained by separating the differential term:

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059]

[0060]

[0061] in, K4 = n 2 L2+L m K5 = L m r1+n 2 L2r1+n 2 L m r2, K6 = n 2 L2, K7 = n 2 L2r1-n 2 L1r2.

[0062] Preferably, the state observation and control consists of a state observer and a state controller.

[0063] Preferably, the design of the state observer includes the following steps:

[0064] With the state observer's state vector and frequency input selected, the large-signal model equations are rewritten as follows:

[0065]

[0066] in, u=ω,d=V es G is the proportionality coefficient;

[0067] Calculate the dynamic matrix A, control matrix B, and measurement matrix C to determine the state equations of the bidirectional CLLC converter:

[0068]

[0069]

[0070]

[0071] Where y = V O , This is the calculated state-stable solution;

[0072] Design a complete Luenberger observer for a bidirectional CLLLC converter:

[0073]

[0074] in, It is an estimate of the actual state variables. For simulators, The observer gain matrix L is the corrected weight, which acts as the trimmer.

[0075] Preferably, the state controller is designed as follows:

[0076]

[0077] Where K is the state feedback gain matrix, v is the reference input, and u is the controller output.

[0078] An apparatus comprising:

[0079] One or more processors;

[0080] Memory, used to store one or more programs;

[0081] When the one or more programs are executed by the one or more processors, the one or more processors implement a bidirectional CLLLC state observation control method based on extended description function modeling as described above.

[0082] A storage medium containing computer-executable instructions, which, when executed by a computer processor, are used to perform a bidirectional CLLLC state observation and control method based on extended description function modeling as described above.

[0083] The beneficial effects of this invention are:

[0084] This invention addresses the challenges of wide-range output voltage and output voltage stability under varying load conditions in bidirectional CLLLC converters. It establishes a harmonic equivalent circuit for the bidirectional CLLLC converter, utilizes an extended description function to build a large-signal model, and approximates the linearization of the model using partial derivatives and steady-state solutions. This creates a state observation equation for the bidirectional CLLLC converter, and a controller is designed to achieve precise control of the converter. Since the state observation matrix is ​​related to both the circuit topology and system control parameters, the state observation control method for bidirectional CLLLC converters based on extended description function modeling is applicable to DC / DC conversion in various application scenarios, achieving stable output voltage under different load conditions. Attached Figure Description

[0085] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0086] Figure 1 This is a schematic diagram of the bidirectional CLLLC converter circuit topology;

[0087] Figure 2 This is the equivalent circuit diagram of a bidirectional CLLLC converter;

[0088] Figure 3 This is a state observation and control block diagram of a bidirectional CLLLC converter;

[0089] Figure 4 This is a simulation waveform diagram built on PLECS. Detailed Implementation

[0090] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0091] like Figure 1-4 As shown, a bidirectional CLLLC state observation and control method based on extended description function modeling includes two parts: bidirectional CLLLC converter extended description function modeling and state observation and control.

[0092] The extended describing function model consists of the equivalent circuit of the bidirectional CLLLC converter, the harmonic approximation, and the extended describing function equation.

[0093] The equivalent circuit of a bidirectional CLLLC converter is a circuit with an amplitude of V. ab The square wave voltage source replaces the full-bridge inverter circuit, and the rectifier circuit is equivalent to a combination of a controlled voltage source and a controlled current source. The equivalent series resistance of the output filter capacitor is r. o The transformer turns ratio is n:1, such as Figure 2 The nonlinear state equations of the equivalent circuit are as follows:

[0094]

[0095]

[0096]

[0097]

[0098]

[0099]

[0100] Where sgn is the sign function, and its positive or negative value represents the direction of the current flowing through the primary side of the transformer; L1 is the primary resonant inductance; L2 is the secondary resonant inductance; L... m Here, r1 is the magnetizing inductor, r2 is the equivalent resistance of inductor L2, C1 is the primary capacitance, C2 is the secondary capacitance, and C... oFor the output filter capacitor, i1 and i2 are the inductor currents flowing through L1 and L2, respectively. m For flow through L m The inductor current, and The voltages across capacitors C1 and C2 are respectively, V Co V is the voltage across the output filter capacitor. o For the output voltage, R L To output equivalent load.

[0101] The harmonic approximation involves two steps:

[0102] Step 1: Approximate the voltage across the nonlinear element and the current flowing through the nonlinear element using the fundamental frequency:

[0103] i1(t)=i 1s (t)sin(ωt)+i 1c (t)cos(ωt)

[0104] i m (t)=i ms (t)sin(ωt)+i mc (t)cos(ωt)

[0105] i2(t)=i 2s (t)sin(ωt)+i 2c (t)cos(ωt)

[0106]

[0107]

[0108] Where ω is the fundamental frequency, i 1s i 1c i ms i mc i 2s i 2c , i1 and i m i2, The amplitudes of the sinusoidal and cosine components;

[0109] Step 2, differentiate the fundamental approximation equation:

[0110]

[0111]

[0112]

[0113]

[0114]

[0115] The expansion function describes the equation in three steps:

[0116] Step 1, convert the nonlinear term V ab ,sgn(i1-i m ),n|i1-i m | Written in fundamental form:

[0117] V ab =f1(d,v in sin(ωt)

[0118] sgn(i1-i m )=f2(i 1s -i ms i 1c -i mc sin(ωt) + f3(i 1s -i ms i 1c -i mc cos(ωt)

[0119] n|i1-i m |=nf4(i 1s -i ms i 1c -i mc )

[0120]

[0121]

[0122]

[0123]

[0124] in, V g For V ab Amplitude, v in V is the input sinusoidal voltage. es This represents the sinusoidal component of the output voltage of the full-bridge inverter circuit.

[0125] Step 2: Substitute the fundamental form of the nonlinear term into the derivative form of the harmonic approximation equation:

[0126]

[0127]

[0128]

[0129]

[0130]

[0131]

[0132]

[0133]

[0134]

[0135]

[0136] Step 3: Separate the differential terms to obtain the large-signal model of the bidirectional CLLLC converter:

[0137]

[0138]

[0139]

[0140]

[0141]

[0142]

[0143]

[0144]

[0145]

[0146] in, K4 = n 2 L2+L m K5 = L m r1+n 2 L2r1+n 2 L m r2, K6 = n 2 L2, K7 = n 2 L2r1-n 2 L1r2.

[0147] State observation and control, such as Figure 3 It consists of a state observer and a controller.

[0148] The design of a state observer involves three steps:

[0149] Step 1: Select the state observer's state vector and frequency input, and rewrite the large-signal model equations:

[0150]

[0151] in, u=ω,d=V es G is the proportionality coefficient.

[0152] Step 2: Calculate the dynamic matrix A, control matrix B, and measurement matrix C to determine the state equations of the bidirectional CLLC converter.

[0153]

[0154]

[0155]

[0156] Where y = V O , This is the calculated state-stable solution;

[0157] Step 3, Design a complete Luenberger observer for the bidirectional CLLLC converter:

[0158]

[0159] in, It is an estimate of the actual state variables. For simulators, The observer gain matrix L is the corrected weight, acting as a trimmer.

[0160] The state controller is designed as follows:

[0161]

[0162] Where K is the state feedback gain matrix, v is the reference input, and u is the controller output.

[0163] A simulation model was built using PLECS simulation software, and the simulation waveforms were obtained as follows: Figure 4As shown. Under initial conditions, the converter operates at its rated state and reaches steady-state operation after a certain period. Switching the load to an unloaded condition causes the current to abruptly drop to 0, while the voltage remains stable. Switching the converter to a load exceeding the rated load by 20% causes the current to abruptly increase to 1.2 times the rated current, while the voltage remains stable. Switching the load back to the rated load causes the converter current to return to its rated current. Throughout this process, the converter's output voltage fluctuation remains below 0.3V, i.e., the voltage fluctuation is less than 0.1%, and the output voltage remains essentially stable.

[0164] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0165] The above formulas are all numerical calculations after removing dimensions. The formulas are obtained by software simulation based on a large amount of data and are closest to the real situation. The preset parameters and preset thresholds in the formulas are set by those skilled in the art according to the actual situation or obtained by simulation based on a large amount of data.

[0166] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A bidirectional CLLLC state observation control method based on extended description function modeling, characterized in that, Includes the following steps: A large-signal model is generated by extending the description function through a bidirectional CLLLC converter, and then state observation and control is performed based on the generated large-signal model. The large-signal model generated by the extended description function modeling of the bidirectional CLLLC converter consists of the equivalent circuit of the bidirectional CLLLC converter, harmonic approximation, and extended description function equations. The state observation and control system consists of a state observer and a state controller. The design of the state observer includes the following steps: With the state observer's state vector and frequency input selected, the large-signal model equations are rewritten as follows: in, , , , G is the proportionality coefficient; Calculate the dynamic matrix A, control matrix B, and measurement matrix C to determine the state equations of the bidirectional CLLC converter: in, , , , This is the calculated state-stable solution; Design a complete Luenberger observer for a bidirectional CLLLC converter: in, It is an estimate of the actual state variables. For simulators, The observer gain matrix L is the correction weight for the trimmer. The state controller is designed as follows: Where K is the state feedback gain matrix, v is the reference input, and u is the controller output.

2. The bidirectional CLLLC state observation and control method based on extended description function modeling according to claim 1, characterized in that, The equivalent circuit of the bidirectional CLLLC converter is to replace the full-bridge inverter circuit with a square wave voltage source with an amplitude of Vab. The rectifier circuit is equivalent to a combination of a controlled voltage source and a controlled current source. The equivalent series resistance of the output filter capacitor is ro, and the transformer ratio is n:

1. The nonlinear state equation of the equivalent circuit is as follows: Where sgn is the sign function, and the positive or negative value of sgn represents the direction of the current flowing through the primary side of the transformer; L1 is the primary resonant inductance; L2 is the secondary resonant inductance; Lm is the magnetizing inductance; r1 is the equivalent resistance of inductor L1; r2 is the equivalent resistance of inductor L2; C1 is the primary capacitance; C2 is the secondary capacitance; Co is the output filter capacitor; i1 and i2 are the inductor currents flowing through L1 and L2, respectively; and im is the inductor current flowing through Lm. and VCo represents the voltage across capacitors C1 and C2, respectively; VCo represents the voltage across the output filter capacitor; Vo represents the output voltage; and RL represents the output equivalent load.

3. The bidirectional CLLLC state observation and control method based on extended description function modeling according to claim 1, characterized in that, The harmonic approximation consists of two parts: The voltage across the nonlinear element and the current flowing through the nonlinear element are expressed using the fundamental approximation equation: Where ω is the fundamental frequency. , , , , , , , , , They are respectively , , , , The amplitudes of the sinusoidal and cosine components; Differentiate the fundamental approximation equation: 。 4. The bidirectional CLLLC state observation and control method based on extended description function modeling according to claim 1, characterized in that, The extended description function equation consists of three parts: nonlinear terms , , Written in fundamental form: in, Vg is the amplitude of Vab, vin is the input sinusoidal voltage, and Ves is the sinusoidal component of the output voltage of the full-bridge inverter circuit; Substituting the fundamental form of the nonlinear term into the derivative form of the harmonic approximation equation: ； The large-signal model of the bidirectional CLLLC converter is obtained by separating the differential term: in, , , , , , , .

5. A device, characterized in that, include: One or more processors; Memory, used to store one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement a bidirectional CLLLC state observation control method based on extended description function modeling as described in any one of claims 1-4.

6. A storage medium containing computer-executable instructions, characterized in that, The computer-executable instructions, when executed by a computer processor, are used to perform a bidirectional CLLLC state observation and control method based on extended description function modeling as described in any one of claims 1-4.

Images