Dual-active bridge frequency conversion phase shift control method based on boundary judgment adaptive control

Abstract

The invention provides a dual-active bridge frequency conversion and phase shift control method based on boundary judgment adaptive control, which comprises the following steps of: 1, acquiring operation data of a dual-active bridge converter, and judging a soft switching implementation state of the dual-active bridge converter based on the operation data of the dual-active bridge converter; 2, if the soft switching implementation state of the dual-active bridge converter is soft switching loss, calculating a phase shift ratio boundary value of a zero-voltage switch of the dual-active bridge converter; and step 3, performing boundary judgment based on the phase shift ratio boundary value of the zero voltage switch of the dual active bridge converter, determining the self-adaptive control mode of the dual active bridge converter according to a boundary judgment result, and switching the self-adaptive control mode of the dual active bridge converter by using a PI controller. According to the invention, on the premise of not excessively increasing the control complexity, real-time tracking of the global efficiency optimal point can be realized, and the overall efficiency of the dual-active bridge converter under the wide-range load can be improved.

Description

Technical Field

[0001] This invention relates to the field of electronic power technology, and specifically to a dual active bridge frequency converter phase shift control method based on boundary judgment adaptive control. Background Technology

[0002] With the rapid development of applications such as electric vehicles and DC microgrids, isolated bidirectional DC-DC converters have become crucial for building efficient, high-power-density DC power systems. Among them, dual active bridge converters are widely used due to their advantages such as simple structure, easy control, and fast dynamic response. However, dual active bridge converters are prone to loss of zero-voltage switching soft switching under wide voltage ranges or dynamic load changes, leading to a sharp increase in switching losses and a severe decrease in efficiency.

[0003] Therefore, there is an urgent need for a dual active bridge frequency converter phase shift control method based on boundary judgment adaptive control to address the shortcomings of existing technologies. Summary of the Invention

[0004] The purpose of this invention is to provide a dual active bridge frequency converter phase shift control method based on boundary judgment adaptive control to solve the technical problems mentioned in the background art.

[0005] To achieve the above objectives, the first aspect of this invention proposes a dual active bridge frequency converter phase-shift control method based on boundary judgment adaptive control, comprising: Step 1: Collect the operating data of the dual active bridge converter and determine the soft switching implementation status of the dual active bridge converter based on the operating data; Step 2: If the soft switching implementation state of the dual active bridge converter is soft switching loss, calculate the shift ratio boundary value of the zero-voltage switching of the dual active bridge converter; Step 3: Based on the boundary value of the shift ratio of the zero-voltage switch of the dual active bridge converter, perform boundary judgment, determine the adaptive control mode of the dual active bridge converter according to the boundary judgment result, and use a PI controller to switch the adaptive control mode of the dual active bridge converter.

[0006] Furthermore, the specific method for determining the soft-switching implementation status of the dual active bridge converter based on the operating data of the dual active bridge converter in step 1 is as follows: Calculate the turn-off current of the primary and secondary bridge arm switches based on the operating data of the dual active bridge converter; If the calculated turn-off current of the primary and secondary bridge arm switches is greater than zero, the soft-switching implementation state of the dual active bridge is achieved; otherwise, the soft-switching implementation state of the dual active bridge converter is lost.

[0007] Furthermore, the formula for calculating the turn-off current i1 of the primary side bridge arm switch is as follows: The formula for calculating the turn-off current i2 of the secondary bridge arm switch is: Where i1 is the current at the turn-off moment of the primary-side switch; i2 is the current at the turn-off moment of the secondary-side switch; U ab U is the primary voltage; cd denoted as secondary voltage; n is the turns ratio of the primary and secondary transformers; D is the shift ratio of the primary and secondary switching times; f is the switching frequency of the switching transistor; and L is the inductance value.

[0008] Furthermore, the shift ratio of the zero-voltage switch of the dual active bridge converter in step 2 is a boundary value. The calculation formula is: Among them, U ab U is the voltage on the primary side. cd denoted as the secondary voltage, n as the turns ratio of the primary and secondary transformers, and D as the shift ratio at the switching time of the primary and secondary sides.

[0009] Furthermore, the specific method for determining the adaptive control mode of the dual active bridge converter based on the boundary value of the shift ratio of the zero-voltage switch in step 3 includes: Step 31: Shift ratio boundary value based on zero-voltage switching of dual active bridge converter Calculate a dual active bridge converter with a fixed minimum frequency f. min The critical power that can achieve zero-voltage switching in constant-frequency phase-shift control mode ; Step 32: Set the preset power P of the dual active bridge converter to... ref With critical power For comparison, if the preset power P ref Greater than critical power Select the fixed-frequency phase-shift control mode; If the preset power P ref Less than or equal to critical power Select the fixed-phase-value frequency modulation control mode.

[0010] Furthermore, critical power The calculation formula is: Among them, U ab U is the voltage on the primary side. cd Where is the voltage on the secondary side, n is the turns ratio of the primary and secondary transformers; D is the shift ratio at the switching time on the primary and secondary sides; f min To fix the minimum frequency.

[0011] Furthermore, the specific method for switching the adaptive control mode of the dual active bridge converter using a PI controller in step 3 includes: The PI controller is invoked based on the mode selection signal, and the PI controller generates a shift ratio. and switching frequency The control signal controls the switching transistors of the drive converter to complete the adaptive control mode switching.

[0012] A second aspect of the present invention provides an electronic device comprising: a memory, a processor, and a computer program, the computer program being stored in the memory and configured to be executed by the processor to implement the method described thereon.

[0013] A third aspect of the present invention provides a computer-readable storage medium storing a computer program that is executed by a processor to implement the method.

[0014] The beneficial effects of the technical solution provided by the embodiments of the present invention include: transforming the complex bivariate real-time optimization problem into a mode switching problem based on preset boundaries, thereby achieving real-time tracking of the global efficiency optimum without excessively increasing the control complexity, and improving the overall efficiency of the dual active bridge converter under a wide range of loads. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating an embodiment of the present invention; Figure 2 This is a topology diagram of a dual active bridge converter according to an embodiment of the present invention; Figure 3 This is a key waveform diagram generated by a dual active bridge converter according to an embodiment of the present invention; Figure 4 This is a comparison chart of the efficiency of adaptive control and traditional single-phase-shift control under the condition of 400V input and 1kW load in an embodiment of the present invention. Figure 5 This is a comparison chart of the efficiency of adaptive control and traditional single-phase-shift control under the condition of 400V input and 2kW load in an embodiment of the present invention. Detailed Implementation

[0016] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. 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.

[0017] Example 1 The first aspect of this invention proposes a dual active bridge frequency converter phase-shift control method based on boundary judgment adaptive control, such as... Figure 1 As shown, the method includes: This embodiment uses a 3kW dual active bridge converter applied to a DC microgrid interface as an example to illustrate the implementation process of the present invention in detail. The converter topology diagram of the dual active bridge converter is shown below. Figure 2 As shown, Figure 2 S1-S8 are the eight switches of the dual active bridge converter. The key waveforms generated by the dual active bridge converter are as follows: Figure 3 As shown, Figure 3 The diagram shows the switching signals S1-S8 and the corresponding inductor current waveforms. Key design parameters of this prototype are shown in Table 1. Table 1 Key design parameters of the prototype Step 1: Collect the operating data of the dual active bridge converter and determine the soft switching implementation status of the dual active bridge converter based on the operating data; Specifically, the primary and secondary voltages of the dual active bridge converter are acquired, the voltage sampling signals are preprocessed, and the data are averaged again using an RC low-pass filter and a DSP to obtain the primary voltage. and secondary voltage The real-time control parameters in the DSP are shifted relative to... and switching frequency Accessed from the control output. The turns ratio of the transformer in a dual active bridge converter. and inductance These are fixed parameters that are pre-written into the DSP.

[0018] Specifically, in this embodiment, the primary side voltage , .

[0019] Furthermore, the specific method for determining the soft-switching implementation status of the dual active bridge converter based on the operating data of the dual active bridge converter in step 1 is as follows: Calculate the turn-off current of the primary and secondary bridge arm switches based on the operating data of the dual active bridge converter; If the calculated turn-off current of the primary and secondary bridge arm switches is greater than zero, the soft-switching implementation state of the dual active bridge is achieved; otherwise, the soft-switching implementation state of the dual active bridge converter is lost.

[0020] Furthermore, the formula for calculating the turn-off current i1 of the primary side bridge arm switch is as follows: The formula for calculating the turn-off current i2 of the secondary bridge arm switch is: Where i1 is the current at the turn-off moment of the primary-side switch; i2 is the current at the turn-off moment of the secondary-side switch; U ab U is the primary voltage; cd denoted as secondary voltage; n is the turns ratio of the primary and secondary transformers; D is the shift ratio of the primary and secondary switching times; f is the switching frequency of the switching transistor; and L is the inductance value.

[0021] Step 2: If the soft switching implementation state of the dual active bridge converter is soft switching loss, calculate the shift ratio boundary value of the zero-voltage switching of the dual active bridge converter; Furthermore, the shift ratio boundary of the zero-voltage switch in step 2. The calculation formula is: Among them, U ab U is the voltage on the primary side. cd denoted as the secondary voltage, n as the turns ratio of the primary and secondary transformers, and D as the shift ratio at the switching time of the primary and secondary sides.

[0022] Step 3: Based on the boundary value of the shift ratio of the zero-voltage switch, perform boundary judgment, determine the adaptive control mode of the dual active bridge converter according to the boundary judgment result, and use a PI controller to switch the adaptive control mode of the dual active bridge converter.

[0023] Furthermore, the specific method for determining the adaptive control mode of the dual active bridge converter in step 3, based on the boundary value of the shift ratio of the zero-voltage switch, includes: Step 31: Shift ratio boundary value based on zero-voltage switch Calculate a dual active bridge converter with a fixed minimum frequency f. min The critical power that can achieve zero-voltage switching in constant-frequency phase-shift control mode ; Step 32: Set the preset power P of the dual active bridge converter to... ref With critical power For comparison, if the preset power P ref Greater than critical power Select the fixed-frequency phase-shift control mode; If the preset power P ref Less than or equal to critical power Select the fixed-phase-value frequency modulation control mode.

[0024] Furthermore, critical power The calculation formula is: Among them, U abU is the voltage on the primary side. cd Where is the voltage on the secondary side, n is the turns ratio of the primary and secondary transformers; D is the shift ratio at the switching time on the primary and secondary sides; f min To fix the minimum frequency.

[0025] Furthermore, the specific method for switching the adaptive control mode of the dual active bridge converter using a PI controller in step 3 includes: The PI controller is invoked based on the mode selection signal, and the PI controller generates a shift ratio. and switching frequency The control signal controls the switching transistors of the drive converter to complete the adaptive control mode switching.

[0026] Specifically, When the preset frequency is 40kHz and the preset power is 1kW, the input is a mode selection signal output by comparing the critical power calculated based on actual operation with 1kW. The input of the PI controller is the error between the current reference value and the actual current value. The current reference value is calculated from the preset power value and the actual voltage value. The PI controller selects one set of PI parameters for control based on the control selection signal output by the zero-voltage switching boundary calculation module. The parameters of the two sets of PI control have been tested separately, and the frequency and phase shift ratio output of the two sets of PI control are each set of fixed values, realizing the decoupling of the two control quantities. Finally, the PI controller outputs the control quantities D and f, which are the specific values ​​obtained from the adaptive control calculation. In this embodiment, the fixed frequency phase shift control mode uses a fixed 40kHz, and the phase shift ratio is greater than the boundary phase shift ratio. Range control. In the fixed-phase-value frequency modulation control mode, the fixed phase shift value is the boundary phase shift value. The frequency is controlled within the range of 40kHz to 150kHz. Finally, the specific control quantity is sent to the PWM generation module to generate a PWM wave that acts on the switching transistors of the dual active bridge to complete the control.

[0027] This embodiment effectively extends the zero-voltage switching range under different voltage ratios and load conditions. DC microgrids typically use a 400V bus voltage, while downstream electrical equipment commonly uses 48V. 36V and 60V are typical values ​​when the voltage deviates significantly. Under typical boundary conditions such as 400V to 36V and 400V to 60V, traditional single-phase-shift control results in the loss of soft switching on either the primary or secondary side. However, by adopting adaptive boundary control, the system re-achieves zero-voltage switching through automatic frequency adjustment.

[0028] Figure 4 This example demonstrates an efficiency comparison between adaptive control and traditional single-phase-shift control for a 400V input and a 1kW load. Figure 5This example demonstrates a comparison of the efficiency of adaptive control and traditional single-phase-shift control when the input is 400V and the load is 2kW. The curves represent the theoretical efficiency curves, while the points represent the measured efficiency points.

[0029] The adaptive control effectively prevented the sharp drop in efficiency caused by the loss of soft switching. Efficiency test results further confirmed that the proposed strategy is significantly effective under light load conditions: at 1kW, 400V to 30V, the peak efficiency was improved by 5.7%; in the non-zero voltage switching operating range, the system efficiency was generally improved by more than 1%. Overall, within a wide output voltage range of 28V to 60V, the average efficiency at 1kW and 2kW was improved by 1.95% and 1.2%, respectively, verifying the effectiveness and engineering practical value of the proposed control strategy.

[0030] Example 2 A second aspect of the present invention provides an electronic device comprising: a memory, a processor, and a computer program, the computer program being stored in the memory and configured to be executed by the processor to implement the method described in Embodiment 1.

[0031] Example 3 A third aspect of the present invention provides a computer program product, a computer-readable storage medium storing a computer program that is executed by a processor to implement the method described in Embodiment 1.

[0032] The contents not described in detail in this specification are prior art known to those skilled in the art. Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0033] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1A device that provides the functions specified in one or more boxes.

[0034] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0035] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit its scope of protection. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading the present invention, they can still make various changes, modifications or equivalent substitutions to the specific implementation of the invention, but these changes, modifications or equivalent substitutions are all within the scope of protection of the pending claims of the invention.

Claims

1. A dual active bridge frequency converter phase-shift control method based on boundary judgment adaptive control, characterized in that, include: Step 1: Collect the operating data of the dual active bridge converter and determine the soft switching implementation status of the dual active bridge converter based on the operating data; Step 2: If the soft switching implementation state of the dual active bridge converter is soft switching loss, calculate the shift ratio boundary value of the zero-voltage switching of the dual active bridge converter; Step 3: Based on the boundary value of the shift ratio of the zero-voltage switch of the dual active bridge converter, perform boundary judgment, determine the adaptive control mode of the dual active bridge converter according to the boundary judgment result, and use a PI controller to switch the adaptive control mode of the dual active bridge converter.

2. The dual active bridge frequency converter phase-shift control method based on boundary judgment adaptive control according to claim 1, characterized in that, The specific method for determining the soft-switching implementation status of the dual active bridge converter based on the operating data of the dual active bridge converter in step 1 is as follows: Calculate the turn-off current of the primary and secondary bridge arm switches based on the operating data of the dual active bridge converter; If the calculated turn-off current of the primary and secondary bridge arm switches is greater than zero, the dual active bridge soft switching is implemented as soft switching. Otherwise, the soft-switching implementation state of the dual active bridge converter is soft-switching lost.

3. The dual active bridge frequency converter phase-shift control method based on boundary judgment adaptive control according to claim 2, characterized in that, The formula for calculating the turn-off current i1 of the primary side bridge arm switch is: The formula for calculating the turn-off current i2 of the secondary bridge arm switch is: Where i1 is the current at the turn-off moment of the primary-side switch; i2 is the current at the turn-off moment of the secondary-side switch; U ab U is the primary voltage; cd denoted as secondary voltage; n is the turns ratio of the primary and secondary transformers; D is the shift ratio of the primary and secondary switching times; f is the switching frequency of the switching transistor; and L is the inductance value.

4. The dual active bridge frequency converter phase-shift control method based on boundary judgment adaptive control according to claim 1, characterized in that, The shift ratio boundary value of the zero-voltage switch in the dual active bridge converter in step 2 The calculation formula is: Among them, U ab U is the voltage on the primary side. cd denoted as the secondary voltage, n as the turns ratio of the primary and secondary transformers, and D as the shift ratio at the switching time of the primary and secondary sides.

5. The dual active bridge frequency converter phase-shift control method based on boundary judgment adaptive control according to claim 1, characterized in that, Step 3, which involves boundary judgment based on the zero-voltage switching boundary value of the dual active bridge converter, to determine the adaptive control mode of the dual active bridge converter, includes the following specific methods: Step 31: Shift ratio boundary value based on zero-voltage switching of dual active bridge converter Calculate a dual active bridge converter with a fixed minimum frequency f. min The critical power that can achieve zero-voltage switching in constant-frequency phase-shift control mode ; Step 32: Set the preset power P of the dual active bridge converter to... ref With critical power For comparison, if the preset power P ref Greater than critical power Select the fixed-frequency phase-shift control mode; If the preset power P ref Less than or equal to critical power Select the fixed-phase-value frequency modulation control mode.

6. The dual active bridge frequency converter phase-shift control method based on boundary judgment adaptive control according to claim 5, characterized in that, Critical power The calculation formula is: Among them, U ab U is the voltage on the primary side. cd Where is the voltage on the secondary side, n is the turns ratio of the primary and secondary transformers; D is the shift ratio at the switching time on the primary and secondary sides; f min To fix the minimum frequency.

7. The dual active bridge frequency converter phase-shift control method based on boundary judgment adaptive control according to claim 1, characterized in that, The specific method for switching the adaptive control mode of the dual active bridge converter using a PI controller in step 3 includes: The PI controller is invoked based on the mode selection signal, and the PI controller generates a shift ratio. and switching frequency The control signal controls the switching transistors of the drive converter to complete the adaptive control mode switching.

8. An electronic device, comprising: A memory, a processor, and a computer program, characterized in that: the computer program is stored in the memory and configured to be executed by the processor to implement the method of claims 1-7.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program that is executed by a processor to implement the method of claims 1-7.

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