Dual-active full-bridge converter based on Brayton Moser power forming and control method of dual-active full-bridge converter

Abstract

The invention provides a dual active bridge converter based on Brayton Moser power forming and a control method thereof. The method comprises the following steps: acquiring a measured value V1 of a primary side direct current side voltage of a primary side full-bridge converter and a measured value V2 of a voltage of an output capacitor; based on the voltage expected value V * of the output capacitor, the measured value V1 of the primary side direct current side voltage, the measured value V2 of the secondary side direct current side voltage, the inductance value L of the input inductor, the capacitance value C2 of the output capacitor, the resistance value R of the load and the working frequency fs, the duty ratio of the primary side full-bridge converter and the duty ratio of the secondary side full-bridge converter are obtained; performing modulation processing based on the duty ratio to obtain a switch control signal; and switching tubes in the primary full-bridge converter and the secondary full-bridge converter are controlled based on the switching control signal. According to the invention, the response speed in the control process of the dual-active full-bridge converter is fast, the overshoot condition does not exist, and the control reliability and robustness of the dual-active full-bridge converter are improved.

Description

Technical Field

[0001] The present disclosure relates to the field of electric power technology, and in particular to a dual active bridge converter based on Brayton Moser power shaping and a control method thereof. Background Art

[0002] With the development of science and technology, energy demand continues to rise, and DC converters are widely used in the fields of electric vehicle charging and DC microgrids. Among them, the advantages of dual active full-bridge DC-DC converters (DAB) include bidirectional energy flow, high transmission efficiency, electrical isolation, and low reactive power demand. They have been widely used in electric vehicles, new energy generation, and energy storage. However, since power electronic converters are strongly coupled nonlinear systems, they are affected by factors such as circuit parameter perturbations, load and input voltage changes, and unmodeled dynamics. The traditional linear control method can no longer meet the requirements for high-performance systems in practical applications. Summary of the invention

[0003] In view of this, the purpose of the present disclosure is to propose a dual active full-bridge converter based on Brayton Moser power shaping and a control method thereof.

[0004] Based on the above purpose, in a first aspect, the present disclosure provides a control method for a dual active full-bridge converter based on Brayton Moser power shaping, wherein the dual active full-bridge converter comprises a primary full-bridge converter, a transformer and a secondary full-bridge converter connected in sequence, the input inductor of the primary full-bridge converter is connected to the primary coil of the transformer, and the output capacitor of the secondary full-bridge converter is connected to a load;

[0005] The method comprises:

[0006] Collecting a measured value V1 of the primary DC side voltage of the primary full-bridge converter and a measured value V2 of the voltage of the output capacitor;

[0007] Based on the expected value of the output capacitor voltage V * , the measured value V1 of the primary DC side voltage, the measured value V2 of the secondary DC side voltage, the inductance value L of the input inductor and the capacitance value C2 of the output capacitor, the resistance value R of the load and the operating frequency fs, to obtain the duty cycle of the primary full-bridge converter and the secondary full-bridge converter;

[0008] Performing modulation processing based on the duty cycle to obtain a switch control signal;

[0009] The switch tubes in the primary full-bridge converter and the secondary full-bridge converter are controlled based on the switch control signal.

[0010] On the other hand, the present disclosure provides a dual active full-bridge converter based on Brayton Moser power shaping, which is controlled by the method according to the first aspect.

[0011] As can be seen from the above, the dual active full-bridge converter and control method thereof provided by the present disclosure can ensure that the system has no overshoot during the adjustment process through the idea of ​​passive control, that is, the output voltage will not exceed the set value, thereby improving the stability and reliability of the system. Based on the Brayton-Moser theory, from the perspective of the instantaneous power of the system, variables such as the voltage and current of the converter can be directly introduced into the model to ensure that the system remains stable under various working conditions. The method has good robustness and can maintain stable operation of the system in the case of complex environment and fluctuation of parameters. Due to the use of passive control and Brayton-Moser theory, the system has a faster response speed and can quickly adapt to load changes and other external disturbances. Compared with many complex nonlinear control algorithms, the algorithm logic structure of this method is simple, easy to program and implement, and reduces the difficulty in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the present disclosure or related technologies, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are only embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0013] Figure 1 It is a schematic main circuit diagram of a dual active full-bridge converter based on Brayton Moser power shaping according to an embodiment of the present disclosure.

[0014] Figure 2 Schematic diagram of output voltage of a dual active full-bridge converter based on Brayton Moser power shaping during the startup phase according to an embodiment of the present disclosure.

[0015] Figure 3 Schematic diagram of expected output voltage of a dual active full-bridge converter based on Brayton Moser power shaping according to an embodiment of the present disclosure.

[0016] Figure 4 Schematic diagram of bus voltage of a dual active full-bridge converter based on Brayton Moser power shaping according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0017] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0018] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the embodiments of the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0019] With the development of science and technology, energy demand continues to rise, and DC converters are widely used in the fields of electric vehicle charging and DC microgrids. Among them, the dual active full-bridge DC-DC converter (Dual Active Bridge, DAB) has the advantages of bidirectional energy flow, high transmission efficiency, electrical isolation, and low reactive power demand. It has been widely used in the fields of new energy generation, electric vehicles, and energy storage. However, the power electronic converter is a strongly coupled nonlinear system, which will be affected by factors such as circuit parameter perturbations, load and input voltage changes, and unmodeled dynamics. The traditional linear control method can no longer meet the requirements of high-performance systems in practical applications. Therefore, how to improve the control stability and robustness of the dual active full-bridge converter is a technical problem that needs to be solved urgently.

[0020] In view of this, the disclosed embodiment provides a dual active full-bridge converter and a control method thereof. Through the idea of ​​passive control, it can be ensured that the system has no overshoot during the adjustment process, that is, the output voltage will not exceed the set value, thereby improving the stability and reliability of the system. Based on the Brayton-Moser theory, from the perspective of the instantaneous power of the system, variables such as the voltage and current of the converter can be directly introduced into the model to ensure that the system remains stable under various working conditions. The method has good robustness and can maintain stable operation of the system in a complex environment and when parameters fluctuate. Due to the use of passive control and Brayton-Moser theory, the system has a fast response speed and can quickly adapt to load changes and other external disturbances. Compared with many complex nonlinear control algorithms, the algorithm logic structure of this method is simple and easy to program, which reduces the difficulty in practical applications.

[0021] See also Figure 1 , Figure 1A schematic main circuit diagram of a dual active full-bridge converter according to an embodiment of the present disclosure is shown. Figure 1 In the embodiment, the dual-active full-bridge converter 100 may include primary-side full-bridge converters S1-S4, a transformer T, and secondary-side full-bridge converters Q1-Q4 connected in sequence. Specifically, the AC side of the primary-side full-bridge converters S1-S4 is connected to one side of the transformer T, and the AC side of the secondary-side full-bridge converters Q1-Q4 is connected to the other side of the transformer T. The dual-active full-bridge converter 100 can realize DC-AC voltage conversion through the primary-side full-bridge converters S1-S4, and realize AC-DC voltage conversion through the secondary-side full-bridge converters Q1-Q4, and the transformer T can realize voltage matching, electrical isolation, and temporary energy storage functions between the primary and secondary sides.

[0022] In some embodiments, the primary side full-bridge converters S1-S4 may include:

[0023] A primary filter capacitor C1, wherein a first end of the primary filter capacitor C1 and a second end of the primary filter capacitor C1 are respectively connected to a first DC power supply;

[0024] The primary first switch unit, the primary second switch unit, the primary third switch unit and the primary fourth switch unit; wherein the primary first switch unit includes the primary first switch tube S1 and the first diode D1 connected in parallel to the primary first switch tube S1, the primary second switch unit includes the primary second switch tube S2 and the second diode D2 connected in parallel to the primary second switch tube S2, the primary third switch unit includes the primary third switch tube S3 and the third diode D3 connected in parallel to the primary third switch tube S3, and the primary fourth switch unit includes the primary fourth switch tube S4 and the fourth diode D4 connected in parallel to the primary fourth switch tube S4. The primary first switch tube S1 and the primary second switch tube S2 are connected in series at both ends of the filter capacitor C1 to form the primary first bridge arm; the primary third switch tube S3 and the primary fourth switch tube S4 are connected in series at both ends of the filter capacitor C1 to form the primary second bridge arm; the primary first switch tube S1, the primary third switch tube S3, the first end of the filter capacitor C1 and the positive electrode of the first DC power supply are all connected to the first connection point;

[0025] An input inductor L, a first end of the input inductor L is connected to a connection point between a primary first switch tube S1 and a primary second switch tube S2, a second end of the input inductor L is connected to a first end of a primary side coil of a transformer T, and a second end of the primary side coil of the transformer T is connected to a connection point between a primary third switch tube S3 and a primary fourth switch tube S4.

[0026] In some embodiments, the transformer T may be a high-frequency transformer (HFT), wherein the transformer coil turns ratio may be n:1. For example, the AC side of the primary-side full-bridge converter S1-S4 may be connected to the primary-side coil, and the secondary-side full-bridge converter Q1-Q4 may be connected to the secondary-side coil of the transformer.

[0027] In some embodiments, the secondary side full-bridge converters Q1-Q4 may include:

[0028] A first switch unit on the secondary side, a second switch unit on the secondary side, a third switch unit on the secondary side and a fourth switch unit on the secondary side; wherein the first switch unit on the secondary side includes a first switch tube Q1 on the secondary side and a fifth diode D5 connected in parallel to the first switch tube Q1 on the secondary side, the second switch unit on the secondary side includes a second switch tube Q2 on the secondary side and a sixth diode D6 connected in parallel to the second switch tube Q2 on the secondary side, the third switch unit on the secondary side includes a third switch tube Q3 on the secondary side and a seventh diode D7 connected in parallel to the third switch tube Q3 on the secondary side, and the fourth switch unit on the secondary side includes a fourth switch tube Q4 on the secondary side and an eighth diode D8 connected in parallel to the fourth switch tube Q4 on the secondary side. The first switch tube Q1 on the secondary side is connected in series with the second switch tube Q2 on the secondary side to form a first bridge arm on the secondary side; the third switch tube Q3 on the secondary side is connected in series with the fourth switch tube Q4 on the secondary side to form a second bridge arm on the secondary side; the connection point between the first switch tube Q1 on the secondary side and the second switch tube Q2 on the secondary side is connected to the first end of the secondary coil of the transformer 120, and the connection point between the third switch tube Q3 on the secondary side and the fourth switch tube Q4 on the secondary side is connected to the second end of the secondary coil of the transformer 120;

[0029] The output capacitor C2, the first end of the output capacitor C2 and the second end of the output capacitor C2 are respectively connected to the two ends of the first bridge arm and the second bridge arm of the secondary side; the first switch tube Q1 of the secondary side, the third switch tube Q3 of the secondary side and the first end of the output capacitor C2 are all connected to the second connection point.

[0030] Specifically, if Figure 1 As shown, the DC side of the secondary side full-bridge converter Q1-Q4 can also be connected to the load R. Single-phase-shift (SPS) modulation can be used, and the primary side first switch tube S1 and the primary side fourth switch tube S4 of the primary side full-bridge converter 110 are turned on at the same time, and the primary side second switch tube S2 and the primary side third switch tube S3 are turned on at the same time. Similarly, the secondary side first switch tube Q1 and the secondary side fourth switch tube Q4 of the secondary side full-bridge converter 130 are turned on at the same time, and the secondary side second switch tube Q2 and the secondary side third switch tube Q3 are turned on at the same time, and the primary side and secondary side of the transformer T generate a square wave voltage V H1 and V H2 There is a 50% duty cycle. U1 can be the input voltage and U2 is the output voltage. Lis the average value of the input inductor current, and N is the transformer ratio. Due to the similarity of the working mechanisms of the primary and secondary sides, the switches in the primary side full-bridge converter S1-S4 and the secondary side full-bridge converter Q1-Q4 can use MOSFETs.

[0031] The dynamic model of the DAB converter based on the Brayton-Moser power model is:

[0032]

[0033] Introduce duty cycle D, where Y = [i L ,U2] T =[y1,y2] T Substitute into the above model. We can get:

[0034]

[0035] The compact form of the power model of the nonlinear system is expressed as:

[0036]

[0037] We can multiply both sides of equation (3) by We can get:

[0038]

[0039] In the formula so Since A is not a negative definite matrix, the power balance inequality is not satisfied Therefore, in order to ensure the stability of the DAB converter, a new BM model needs to be established to determine the new and For a given (A, P), choose any λ and symmetric matrix F:

[0040]

[0041] Thus, the power model is transformed into: In the formula

[0042]

[0043] Therefore, only when The matrix satisfies the negative definite condition: Sometimes, there is At this time, the system power balance inequality is satisfied Where u T (Γ) is the input, is the output of the BM model.

[0044] but If satisfied is a negative definite matrix. According to the criterion for negative definite matrices, the odd-order principal minor must be less than 0, and the even-order principal minor must be greater than 0. Then therefore, Right now Get the new BM model:

[0045]

[0046] In order to improve the dynamic regulation capability of DC microgrid DAB converter and regulate voltage, a new potential function P needs to be constructed. c (y), thus obtaining a new closed-loop system The new potential function P c (y) Equilibrium point x at expected value * Requirements: where y * =[y1 * , y2 * ] T =[i L * , U2 * ] T . Let the new potential function P c (y)=P(y)+P a (y). We can get:

[0047]

[0048] make P c (y) The equilibrium point y at the expected value * The second condition is satisfied, so it can be expressed as:

[0049]

[0050]

[0051] Since the closed-loop system satisfies the condition at the desired equilibrium point Then there is

[0052]

[0053] Finally, the duty cycle is obtained as:

[0054]

[0055] According to an embodiment of the present disclosure, a control method of a dual active full-bridge converter may include:

[0056] Step S1: collecting a measured value V1 of the primary DC side voltage of the primary full-bridge converter and a measured value V2 of the voltage of the output capacitor;

[0057] Step S2: Based on the expected voltage value V of the output capacitor * , the measured value V1 of the primary DC side voltage, the measured value V2 of the secondary DC side voltage, the inductance value L of the input inductor and the capacitance value C2 of the output capacitor, the resistance value R of the load and the operating frequency fs, to obtain the duty cycle of the primary full-bridge converter and the secondary full-bridge converter;

[0058] Step S3: performing modulation processing based on the duty cycle to obtain a switch control signal;

[0059] Step S4: Control the switch tubes in the primary full-bridge converter and the secondary full-bridge converter based on the switch control signal.

[0060] In some embodiments, based on the expected voltage value V of the output capacitor * , the measured value V1 of the primary DC side voltage, the measured value V2 of the secondary DC side voltage, the inductance value L of the input inductor and the capacitance value C2 of the output capacitor, the resistance value R of the load and the operating frequency fs, and obtaining the duty ratio of the primary full-bridge converter and the secondary full-bridge converter, including:

[0061] Wherein, fs is the operating frequency of the dual active full-bridge converter, L is the inductance of the input inductor, N is the coil turns ratio of the transformer, C2 is the capacitance of the output capacitor, R is the resistance of the load, y2 is the measured value of the secondary DC side voltage, y2* is the expected value of the secondary DC side voltage, and λ is an arbitrary number. It should be understood that the duty cycle of the primary full-bridge converter and the secondary full-bridge converter can both be d1 or d2.

[0062] In some embodiments, based on the expected voltage value V of the output capacitor * , the measured value V1 of the primary DC side voltage, the measured value V2 of the secondary DC side voltage, the inductance value L of the input inductor and the capacitance value C2 of the output capacitor, the resistance value R of the load and the operating frequency fs, and obtaining the duty ratio of the primary full-bridge converter and the secondary full-bridge converter, including:

[0063] Converting an initial power model of the dual active full-bridge converter into a first power model;

[0064] converting the first power model into a second power model based on an arbitrary number and a symmetric matrix;

[0065] converting the second power model into a third power model based on a stable condition of the dual active full-bridge converter;

[0066] The duty cycle is determined based on a target potential function, a condition satisfied by the power model at a desired value, and the third power model.

[0067] In some embodiments, converting the initial power model of the dual active full-bridge converter into a first power model includes:

[0068] Based on the initial power model and the duty cycle D of the dual active full-bridge converter, the first intermediate power model is obtained Where Y = [i L , U2] T =[y1,y2] T ;

[0069] Converting the first intermediate power model into the second intermediate power model Where A = diag{-L, C2}, Y = [y1, y2] T ,

[0070] Multiply both sides of the second intermediate power model Get the first power model In the formula,

[0071] In some embodiments, converting the first power model into a second power model based on an arbitrary number and a symmetric matrix includes:

[0072] Select any λ and symmetric matrix F, and we can get

[0073] Converting the first power model into a second power model

[0074] In some embodiments, converting the second power model to a third power model based on a stable condition of the dual active full-bridge converter includes:

[0075] Select but

[0076] Obtaining the third power model based on the stable condition includes:

[0077]

[0078] The stability conditions include The matrix satisfies hour, Among them, u T (Γ) is the input value, is the output value; i L is the current value of the input inductor, and D is the duty cycle of the dual active full-bridge converter.

[0079] In some embodiments, determining the duty cycle based on a target potential function, a condition satisfied by the power model at a desired value, and the third power model comprises:

[0080] An updated system model is obtained based on the third power model and the target potential function

[0081] Based on the updated system model and the target potential function P c (y)=P(y)+P a (y) Equilibrium point x at expected value * Requirements: where y * =[y1 * , y2 * ] T =[i L * , U2 * ] T , we can get:

[0082]

[0083] make P c (y) The equilibrium point y at the expected value * Available at:

[0084]

[0085] The updated power model satisfies the condition at the expected value Then the matrix form of the updated power model is obtained

[0086] The duty cycle is determined based on a matrix form of the updated power model.

[0087] For example, based on the passive control of the BM model based on the control method of the embodiment of the present disclosure, a parallel injection damping simulation verification can be performed on the dual active full-bridge converter, and the simulation parameters are shown in Table 1.

[0088] parameter Numeric <![CDATA[Input voltage V 1 / V]]> 400 <![CDATA[Output voltage set value V 2 / V]]> 750 Inductance L / mH 60 Switching frequency f / kHz 50 <![CDATA[Primary side full-bridge capacitor C 1 / mF]]> 0.7 <![CDATA[Full-bridge capacitor on the secondary side C 2 / mF]]> 0.35 <![CDATA[Transformer turns ratio n > 1:1

[0089] Table 1

[0090] See also Figure 2 , Figure 2 A schematic diagram of the secondary-side output voltage of a dual-active full-bridge converter during a startup phase according to an embodiment of the present disclosure is shown. Figure 2 In the control method according to the embodiment of the present disclosure, the output voltage is 750V, and the coefficients of the new BM controller parameters are set to 400, which is 5.11. The proportional coefficient of the PI controller, which is also the integral coefficient, is respectively. The simulation results show that the static effects of the three control strategies are finally stabilized at 750V, but the speed and overshoot are different. Using BM control, the voltage reaches the desired value within 0.109s and gradually stabilizes at 750V. In contrast, when using EL control, the voltage reaches a steady state at 0.111s, and when using PI control, the voltage reaches the desired value at 0.13s and there is a steady state. The yellow solid line represents the PI control, as shown in Figure 4 As shown, the PI control has a significant overshoot of 20.6% compared with the EL and BM controls. Comparing the three control strategies, the system response speed under BM control and passive control is faster according to the control method based on the BM model of the embodiment of the present disclosure, and there is no overshoot under BM control. Compared with the EL control, the response speed of BM control is better, which proves that BM control can more effectively solve the contradiction between speed and overshoot in PI control than traditional passive control.

[0091] See also Figure 3 , Figure 3 A schematic diagram of the secondary-side output voltage of a dual active full-bridge converter when the load suddenly changes according to an embodiment of the present disclosure is shown. Figure 3 In Figure 1, the simulated waveforms of the current and voltage of the DAB converter when the desired voltage changes. First, we compared the three control strategies that stabilize at a rate of 650V when the desired voltage changes. The desired output voltage changes from 750V to 650V in 0.2s, and when the system is controlled by the BM control strategy, it returns to steady state in 0.2232s without obvious fluctuations. When EL control is used, the system returns to steady state at 0.2402s, and when PI control is used, the system reaches steady state at 0.266s with a slight overshoot of about 1.62%. Comparing the waveforms of the three control strategies, compared with PI control, BM control and EL control have a certain degree of speed after the disturbance without obvious fluctuations. From the simulation results, it can be seen that the BM controller has better robustness and anti-interference, as well as the fastest stabilization rate when the desired voltage changes suddenly.

[0092] See also Figure 4 , Figure 4 A schematic diagram of the secondary-side output voltage of a dual active full-bridge converter when a sudden voltage change is expected according to an embodiment of the present disclosure is shown. Figure 4In the figure, when the system adopts BM control, the input voltage changes from 500V to 400V within 0.2s. After the disturbance is added, the steady state is restored in 0.218s, and the voltage is stabilized at 750V without obvious fluctuations. The system recovers to a stable state within 0.222s under passive control and within 0.282s under PI control. Comparing the waveforms of the three control methods, compared with PI control, BM control and passive control have more obvious speed and smaller fluctuations after disturbance. At the same time, BM control has better robustness than traditional passive control and reaches a steady state faster.

[0093] It can be seen that according to the embodiment of the present disclosure, the nonlinear control strategy based on the passive concept has no overshoot, high stability, and good robustness, and is very suitable for industrial control fields with complex environments and fluctuating parameters. The essence of passive controller design is to control the distribution of the system's energy. First, the "reactive term" of the system can be separated from the system, because the "reactive term" has no effect on the energy of the system and will not destroy the stability of the system, so it can be configured arbitrarily; then, the "reactive term" of the system is properly configured by injecting damping into the system, so that the total energy function of the system can follow the given energy function, so that the closed-loop system has passivity, thereby ensuring that the system is stable. The Brayton-Moser (BM) control method based on the passive concept can directly introduce variables such as converter voltage and current into the model from the perspective of system instantaneous power, and has the advantages of no overshoot, high stability, fast response speed, strong robustness, etc. At the same time, compared with many nonlinear control algorithms, the algorithm logic structure of passive control is simple and easy to program. For the first time, a dual active full-bridge DC-DC converter control strategy based on the power shaping form of Brayton-Moser theory is proposed, and a more detailed discussion, model and formula are given. Through the proposed method, various dynamic circuit responses of the dual active full-bridge DC-DC converter based on the Brayton-Moser theory control method are realized. Compared with the traditional PI control strategy and passive control strategy, the BM control strategy has been effectively improved under various working conditions.

[0094] The disclosed embodiment also provides a dual active full-bridge converter based on Brayton Moser power shaping, which is controlled by the method described in the disclosed embodiment.

[0095] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present disclosure (including the claims) is limited to these examples. Based on the concept of the present disclosure, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present disclosure as described above, which are not provided in detail for the sake of simplicity.

[0096] In addition, to simplify the description and discussion, and in order not to make the embodiments of the present disclosure difficult to understand, the known power / ground connections to the integrated circuit (IC) chips and other components may or may not be shown in the provided figures. In addition, the device can be shown in the form of a block diagram to avoid making the embodiments of the present disclosure difficult to understand, and this also takes into account the fact that the details of the implementation of these block diagram devices are highly dependent on the platform on which the embodiments of the present disclosure will be implemented (that is, these details should be fully within the scope of understanding of those skilled in the art). Where specific details (e.g., circuits) are set forth to describe exemplary embodiments of the present disclosure, it is apparent to those skilled in the art that the embodiments of the present disclosure can be implemented without these specific details or with changes in these specific details. Therefore, these descriptions should be considered illustrative rather than restrictive.

[0097] The embodiments of the present disclosure are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present disclosure should be included in the scope of protection of the present disclosure.

Claims

1. A control method for a dual active bridge converter based on Brayton Moser power shaping, characterized in that: The dual active full-bridge converter comprises a primary full-bridge converter, a transformer and a secondary full-bridge converter connected in sequence, the input inductor of the primary full-bridge converter is connected to the primary coil of the transformer, and the output capacitor of the secondary full-bridge converter is connected to the load; The method comprises: Collecting a measured value V1 of the primary DC side voltage of the primary full-bridge converter and a measured value V2 of the voltage of the output capacitor; Based on the expected value of the output capacitor voltage V * , the measured value V1 of the primary DC side voltage, the measured value V2 of the secondary DC side voltage, the inductance value L of the input inductor and the capacitance value C2 of the output capacitor, the resistance value R of the load and the operating frequency fs, to obtain the duty cycle of the primary full-bridge converter and the secondary full-bridge converter; Performing modulation processing based on the duty cycle to obtain a switch control signal; The switch tubes in the primary full-bridge converter and the secondary full-bridge converter are controlled based on the switch control signal.

2. The method according to claim 1, characterized in that Based on the expected value of the output capacitor voltage V * , the measured value V1 of the primary DC side voltage, the measured value V2 of the secondary DC side voltage, the inductance value L of the input inductor and the capacitance value C2 of the output capacitor, the resistance value R of the load and the operating frequency fs, and obtaining the duty ratio of the primary full-bridge converter and the secondary full-bridge converter, including: Among them, fs is the operating frequency of the dual active full-bridge converter, L is the inductance of the input inductor, N is the turns ratio of the transformer, C2 is the capacitance of the output capacitor, R is the resistance of the load, y2 is the measured value of the secondary DC side voltage, y2* is the expected value of the secondary DC side voltage, λ is an arbitrary number within the required value range, the duty cycle of the primary full-bridge converter and the secondary full-bridge converter is d1 or d2, and t2 is an arbitrary coefficient.

3. The method according to claim 1, characterized in that Based on the expected value of the output capacitor voltage V * , the measured value V1 of the primary DC side voltage, the measured value V2 of the secondary DC side voltage, the inductance value L of the input inductor and the capacitance value C2 of the output capacitor, the resistance value R of the load and the operating frequency fs, and obtaining the duty ratio of the primary full-bridge converter and the secondary full-bridge converter, including: Converting an initial power model of the dual active full-bridge converter into a first power model; converting the first power model into a second power model based on an arbitrary number and a symmetric matrix; converting the second power model into a third power model based on a stable condition of the dual active full-bridge converter; The duty cycle is determined based on a target potential function, a condition satisfied by the power model at a desired value, and the third power model.

4. The method according to claim 3, characterized in that The method converts the initial power model of the dual active full-bridge converter into a first power model, comprising: Based on the initial power model and the duty cycle D of the dual active full-bridge converter, the first intermediate power model is obtained Where Y = [i L , U2] T =[y1,y2] T ; Converting the first intermediate power model into the second intermediate power model Where A = diag{-L, C2}, Y = [y1, y2] T , Multiply both sides of the second intermediate power model Get the first power model In the formula, 5. The method according to claim 4, characterized in that Converting the first power model into a second power model based on an arbitrary number and a symmetric matrix includes: Select any λ and symmetric matrix F, and we can get Converting the first power model into a second power model 6. The method according to claim 5, characterized in that Converting the second power model into a third power model based on a stable condition of the dual active full-bridge converter comprises: Select but Obtaining the third power model based on the stable condition includes: The stability conditions include The matrix satisfies hour, Among them, u T (Γ) is the input value, is the output value; i L is the current value of the input inductor, and D is the duty cycle of the dual active full-bridge converter.

7. The method according to claim 6, characterized in that Determining the duty cycle based on a target potential function, a condition satisfied by the power model at a desired value, and the third power model includes: An updated system model is obtained based on the third power model and the target potential function Based on the updated system model and the target potential function P c (y)=P(y)+P a (y) Equilibrium point x at expected value * Requirements: where y * =[y1 * , y2 * ] T =[i L * , U2 * ] T , we can get: make P c (y) Equilibrium point y at expected value * Available at: The updated power model satisfies the condition at the expected value Then the matrix form of the updated power model is obtained The duty cycle is determined based on a matrix form of the updated power model.

8. A dual active full-bridge converter based on Brayton Moser power shaping, characterized in that: The control is performed using the method according to any one of claims 1 to 7.

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