A dual active bridge partial power converter and a control method thereof

Abstract

This invention discloses a dual active bridge partial power converter and its control method. The converter includes an input capacitor, a primary-side full-bridge inverter circuit, a high-frequency transformer, a leakage inductor, a secondary-side full-bridge inverter circuit, an output capacitor, and a bypass switch. One end of the output capacitor is connected to one end of the bypass switch and serves as the positive terminal of the output, connected to the load. The other end of the load is connected to the negative terminal of a battery. The other end of the output capacitor is connected to the other end of the bypass switch and simultaneously connected to the positive terminal of the battery. By detecting the battery voltage and comparing it with a preset threshold, a three-stage mode switching is achieved: high-voltage bypass direct connection, medium-voltage light partial power conversion, and low-voltage heavy partial power conversion. Frequent switching is avoided by setting a hysteresis interval. Furthermore, a joint optimization method for key parameters is proposed, aiming to maximize the energy utilization efficiency throughout the entire life cycle, and jointly searching to determine the optimal combination of the high-voltage threshold, low-voltage threshold, and transformer turns ratio. This invention significantly improves the overall energy efficiency of the converter throughout its entire life cycle.

Description

Technical Field

[0001] This invention relates to the field of power electronic conversion technology, and in particular to a dual active bridge partial power converter and its control method. Background Technology

[0002] With the rapid development of new energy storage technologies, energy storage battery packs are evolving towards higher voltage and wider voltage ranges in pursuit of higher energy density and charge / discharge efficiency. Taking the mainstream lithium iron phosphate (LFP) high-voltage battery pack as an example, its terminal voltage typically covers a fluctuation range of 150V to 500V or even wider throughout its entire life cycle. Under such a wide input voltage condition, traditional full-power DC / DC converters often need to design the transformer turns ratio and switching device ratings according to the worst operating conditions in order to meet the gain requirements at the lowest input voltage. This results in not only high input current stress under normal operating conditions, but also a large amount of reactive circulating current that significantly increases the losses of magnetic components and switching devices, severely restricting the overall operating efficiency of the system.

[0003] To overcome efficiency bottlenecks, Partial Power Processing (PPP) architecture has emerged. This architecture, through series / parallel connections on the input and output sides, processes only a portion of the transmitted power, thereby significantly reducing the power rating and size of the converter. Among them, PPP converters based on dual active bridges (DABs) have become a research hotspot for wide-voltage energy storage interface circuits due to their electrical isolation and ease of implementing zero-switching (ZVS) characteristics.

[0004] However, existing dual active bridge partial power conversion technologies still have insurmountable technical shortcomings when facing wide-voltage energy storage applications, mainly in the following two aspects:

[0005] First, fixed-mode switching strategies cannot match dynamic operating conditions. Existing technologies typically use a single voltage threshold to simply divide the operating range into "boost / buck" or "bypass / conversion" modes. However, over a wide voltage range, battery voltage changes continuously with state of charge (SOC). A single fixed threshold often causes the converter to be in a "hard switching" or "inefficient operation" state in the voltage critical region, making it impossible to achieve optimal smooth transition in efficiency across the entire voltage range.

[0006] Second, the design of hardware parameters and control parameters is disconnected. In traditional design methods, designers typically first select the turns ratio (n) of the high-frequency transformer based on the maximum / minimum voltage range, using experience or the principle of maximizing rated point efficiency. After determining the hardware, they then set the control threshold (V) based on open-loop test results. H V LIn fact, the transformer turns ratio directly determines the partial power ratio and the soft-switching range, while the control threshold determines the operating proportion of each mode. These three parameters (n, V) H V L There is a strong nonlinear coupling relationship in determining the full-cycle efficiency. This decoupled design method of "hardware first, software later" severs the intrinsic connection between parameters, causing the system to often get stuck in local optima and making it difficult to maximize energy utilization during the charging and discharging process of the entire life cycle.

[0007] In summary, existing partial power conversion technologies still have significant shortcomings in wide-voltage energy storage systems. There is an urgent need for a partial power conversion device and its control method that can adapt to a wider voltage range through multi-segment mode switching and can significantly improve the system's full-cycle energy utilization efficiency through parameter joint optimization strategies. Summary of the Invention

[0008] In view of the above, this invention proposes a dual active bridge partial power converter and its control method. The converter of this invention can adapt to a wider voltage range and can maximize the energy utilization efficiency throughout the entire cycle.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: a dual active bridge partial power converter, comprising an input capacitor C1, a primary-side full-bridge inverter circuit, a high-frequency transformer T, and a leakage inductance L. k Secondary-side full-bridge inverter circuit, output capacitor C2 and bypass switch K a ;

[0010] The input capacitor C1 is connected in parallel between the positive and negative terminals of the energy storage battery and is also connected to the input terminal of the primary-side full-bridge inverter circuit; the output terminal of the primary-side full-bridge inverter circuit is connected to the primary winding of the high-frequency transformer T; the secondary winding of the high-frequency transformer T is connected through the leakage inductance L. k The secondary-side full-bridge inverter circuit is connected to its input terminal; the output terminal of the secondary-side full-bridge inverter circuit is connected in parallel to the output capacitor C2; one end of the output capacitor C2 is connected to the bypass switch K. a One end of the output capacitor C2 is connected to the positive terminal of the converter output and then to the positive terminal of the load. The other end of the load is connected to the negative terminal of the energy storage battery. The other end of the output capacitor C2 is connected to the bypass switch K. a The other end is connected to the positive terminal of the battery.

[0011] The aforementioned dual active bridge power converter includes a lithium iron phosphate battery, a ternary lithium battery, or a sodium-ion battery as its energy storage battery.

[0012] The aforementioned control method for the dual active bridge power converter includes the following steps:

[0013] Detecting the voltage V of the energy storage battery bat and compare it with the preset high voltage threshold V. H and low-pressure threshold V L By comparison, the system is divided into high-voltage bypass mode, medium-voltage light-section power conversion mode, and low-voltage heavy-section power conversion mode; among which:

[0014] High-voltage bypass mode: when V bat ≥V H At that time, drive the bypass switch K a Close and turn off all switching devices;

[0015] Medium-voltage light-power conversion mode: when V L ≤V bat <V H At that time, drive the bypass switch K a Disconnect and drive the partial power converter to operate in light partial power conversion mode;

[0016] Low-voltage heavy-duty power conversion mode: when V bat <V L At that time, control the bypass switch K a Keep it disconnected and drive the partial power converter to operate in heavy partial power conversion mode.

[0017] The aforementioned control method for the dual active bridge power converter, wherein the high-voltage bypass mode, the medium-voltage light-side power conversion mode, and the low-voltage heavy-side power conversion mode are all implemented by setting a voltage hysteresis region; wherein, a high-voltage entry threshold V is set. H,on High voltage exit threshold V H,off Low-pressure entry threshold V L,on and low-voltage exit threshold V L,off And V H,off <V H,on V L,off <V L,on ;

[0018] When V is satisfied bat ≥V H,on At that time, the power conversion mode of the medium-voltage light section is switched to the high-voltage bypass mode;

[0019] When V is satisfied bat ≤V H,off At that time, it switches from high-voltage bypass mode back to medium-voltage light-power conversion mode;

[0020] When V is satisfied bat <V L,onAt that time, the power conversion mode of the medium-voltage light component is switched to the power conversion mode of the low-voltage heavy component;

[0021] When V is satisfied bat ≥V L,off At that time, the power conversion mode is switched from the low-voltage heavy-duty component to the medium-voltage light-duty component.

[0022] In the aforementioned control method for the dual active bridge power converter, the medium-voltage light power conversion mode is achieved through three-phase shift modulation, and the phase shift angle of the three-phase shift modulation is controlled within a preset range.

[0023] The aforementioned control method for the dual active bridge power converter includes a low-voltage heavy-duty power conversion mode achieved by increasing the phase shift angle of the three-phase shift modulation, and includes a current limiting unit to limit the peak current in the low-voltage region.

[0024] The aforementioned control method for the dual active bridge power converter also includes a joint optimization step for key parameters to maximize the battery's full-cycle energy utilization efficiency k. E To achieve this goal, the high-voltage threshold V of the converter is determined by adding threshold voltage constraints, transformer turns ratio constraints, and partial power ratio constraints. H Low-voltage threshold V L And the optimal combination of three key parameters: the turns ratio n of the high-frequency transformer.

[0025] The aforementioned control method for the dual active bridge power converter includes the following steps in the joint optimization of key parameters:

[0026] S1. Obtain the open-circuit voltage-state-of-charge curve of the energy storage battery, and discretize the SOC interval into N calculation points;

[0027] S2. Establish a loss model for the converter. This loss model characterizes the converter loss in relation to the battery voltage V. bat The functional relationship between the turns ratio n and the partial power ratio q of a high-frequency transformer;

[0028] S3, the total cycle energy utilization efficiency k E Defined as the weighted average of the converter's total efficiency across N calculation points;

[0029] S4, to maximize the full-cycle energy utilization efficiency k E Using the objective function, and under the premise of satisfying threshold voltage constraints, transformer turns ratio constraints, and partial power ratio constraints, a joint search strategy is adopted to simultaneously determine the high-voltage threshold V of the converter. H Low-voltage threshold V L And the optimal combination of the turns ratio n of the high-frequency transformer.

[0030] Compared with the prior art, the present invention has the following significant advantages:

[0031] 1. In this invention, the load is directly connected to the negative terminal of the battery, forming a series circuit with the battery, load, and converter itself. This means the converter (DAB) only needs to process and convert the power corresponding to the voltage difference between the load voltage and the battery voltage, rather than the entire input / output power. This directly reduces the power rating of the converter, significantly reducing the size of magnetic components and conduction losses, laying the foundation for high-efficiency system operation. Based on the "partial power" topology, this invention creatively adds a bypass switch, connected in parallel with the output capacitor C2. This is the key hardware foundation for achieving efficient three-stage operation. When the battery voltage is high enough, this switch can directly connect the battery to the load, completely bypassing the converter and achieving near-zero power transfer.

[0032] 2. This invention proposes a method based on a high-voltage threshold V. H and low-pressure threshold V L The three-stage mode switching strategy overcomes the limitations of existing single-threshold switching. By dividing the battery voltage range into three modes—high-voltage bypass, medium-voltage light power, and low-voltage heavy power—the system operates in a higher efficiency range, thereby improving the overall energy utilization efficiency throughout the entire cycle.

[0033] 3. This invention further proposes a joint parameter optimization strategy to maximize the full-cycle energy utilization efficiency k. E Let V be the objective function, and let V be the high-voltage threshold. H Low-voltage threshold V L By performing a multivariate joint search on the three key parameters of turns ratio n, we ensured that all core parameters achieved optimal matching across the entire voltage range, further improving system performance. Attached Figure Description

[0034] Figure 1 This is a topology diagram of the dual active bridge power converter proposed in this invention.

[0035] Figure 2 This is a schematic diagram of the three-stage control mode and switching logic proposed in this invention.

[0036] Figure 3 This is a flowchart of the joint optimization of key parameters proposed in this invention.

[0037] Figure 4 This is an experimental waveform diagram of the converter when it is in the low-voltage heavy-duty power conversion mode.

[0038] Figure 5 The waveform diagram is an experimental waveform diagram of the medium-voltage light-power conversion.

[0039] Figure 6 The efficiency curves are shown for the converter under different modes and loads. Detailed Implementation

[0040] To describe the present invention in more detail, the technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] Example: A dual active bridge partial power converter, such as Figure 1 As shown, it includes input capacitor C1, primary-side full-bridge inverter circuit, high-frequency transformer T, and leakage inductance L. k Secondary-side full-bridge inverter circuit, output capacitor C2, bypass switch K a and control circuits.

[0042] The primary-side full-bridge circuit includes switching devices Q1 to Q4. The drain of switching device Q1 is connected to the drain of switching device Q3, one end of input capacitor C1, and the positive terminal of the energy storage battery (the energy storage battery is a lithium iron phosphate battery, a ternary lithium battery, or a sodium-ion battery). The source of switching device Q1 is connected to one end of the primary winding of high-frequency transformer T and the drain of switching device Q2. The source of switching device Q2 is connected to the source of switching device Q4, the other end of input capacitor C1, and the negative terminal of the energy storage battery. The source of switching device Q3 is connected to the drain of switching device Q4 and the other end of the primary winding of high-frequency transformer T.

[0043] The secondary-side full-bridge circuit includes switching devices Q5~Q8. The drain of switching device Q5 is connected to the drain of switching device Q7, one end of output capacitor C2, and bypass switch K. a One end of the switch Q5 is connected to the output load end; the source of the switch Q5 is connected to the leakage inductance L. k One end of the capacitor is connected to the drain of the switching device Q6; the source of the switching device Q6 is connected to the source of the switching device Q8, the other end of the output capacitor C2, and the bypass switch K. a The other end; the source of switching device Q7 is connected to one end of the secondary coil of the high-frequency transformer and the drain of switching device Q8 respectively; the other end of capacitor C2 is connected to the positive terminal of the battery, and the other end of the load is connected to the negative terminal of the battery; the turns ratio of the high-frequency transformer T is n.

[0044] Furthermore, this embodiment provides a control method for a dual active bridge power converter. Figure 2 As shown. The control circuit of this invention is based on the energy storage battery voltage V. bat With the preset high voltage threshold V H and low-pressure threshold V LThe comparison results divide the converter's operation into high-voltage bypass mode, medium-voltage light-part power conversion mode, and low-voltage heavy-part power conversion mode. Furthermore, to improve system stability at mode switching points, a voltage hysteresis region is set, employing four specific voltage thresholds (high-voltage entry threshold V). H,on High voltage exit threshold V H,off Low-pressure entry threshold V L,on and low-voltage exit threshold V L,off To avoid frequent switching, the control method is implemented by the control circuit, which includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the following control logic: detecting the battery voltage V. bat And based on its relationship with the preset high voltage threshold V H and low-pressure threshold V L The comparison results enable the bypass switch K to be used. a And the switching control of the three-stage mode of the power converter.

[0045] The three-stage control mode and switching logic are as follows:

[0046] 1) High-voltage bypass mode: When V bat >V H,on Switch to this mode when needed. In this mode, the controller drives the bypass switch K. a The PWM signal of the switching device is closed and then disconnected, the converter stops working, and the battery directly supplies power to the load, achieving zero conversion loss. This only occurs when the battery voltage drops to the high-voltage shutdown threshold, i.e., V... bat <V H,off Only when the system exits bypass mode will it enter medium-voltage light power conversion mode.

[0047] 2) Medium-voltage light-duty power handling mode: When V L,on ≤V bat <V H,off When switching to this mode, bypass switch K a When disconnected, some power converters operate with a smaller phase shift angle, primarily used for slight power boosting or bucking.

[0048] 3) Low-voltage heavy-duty power handling mode: When V bat <V L,on When switching to this mode, bypass switch K a Maintaining the open circuit, a significant voltage boost is achieved by increasing the three-phase shift modulation (TPS) phase shift angle. The control circuit includes a current limiting unit to limit the peak leakage inductance current, thereby reducing current stress and temperature rise in the switching devices. When V bat >V L,offWhen this happens, the system exits this mode and enters the medium-voltage light power conversion mode.

[0049] Furthermore, in partial power converters, some power is transmitted in a direct pass-through manner, with only a portion of the power being transmitted to the output side via a dual active bridge (DAB) converter. Therefore, the actual power that the converter needs to handle is determined by the voltage difference between the battery and the load.

[0050] Define the partial power ratio q to measure the proportion of power actually processed by the DAB converter to the total output power:

[0051] ;

[0052] Ideally, the power flow efficiency of the through section is approximately 100%, therefore the loss P in part of the power converter is... loss,DAB The main source of power comes from the actual power processed by DAB, primarily including switching losses P. sw Conduction loss P cond and magnetic loss P tr :

[0053] ;

[0054] All three types of losses are related to the battery voltage V. bat The transformer turns ratio n and partial power ratio q are related.

[0055] Therefore, the efficiency η of DAB DAB It can be represented as:

[0056] ;

[0057] Overall system efficiency η sys It is mainly determined by the ratio of the actual processed power to the total power, and in high-voltage bypass mode, η sys It is approximately 100%. Therefore, the overall system efficiency is expressed as:

[0058] ;

[0059] Full-cycle energy utilization efficiency k E It is a key indicator for evaluating system performance, and it is defined as the overall system efficiency η. sys Integral or weighted average over the battery's full discharge process at SOC:

[0060] .

[0061] The joint optimization problem is transformed into one that maximizes the battery's full-cycle energy efficiency k. E The objective function for the objective is:

[0062] ;

[0063] The optimization problem needs to satisfy the following constraints to ensure the safety and effectiveness of the system in actual operation:

[0064] (1) Threshold voltage constraint

[0065] ;

[0066] In the formula, V min,use V is the voltage corresponding to the minimum allowable SOC of the battery. max This is the voltage corresponding to the battery's maximum SOC.

[0067] (2) Transformer turns ratio constraint:

[0068] ;

[0069] In the formula, n min and n max The actual physical range of the transformation ratio n is limited.

[0070] (3) Partial power ratio constraint:

[0071] ;

[0072] In the formula, q max The maximum power ratio is given by the value q. max =0.5, meaning that the actual power processed by the converter is not allowed to exceed 50% of the total power.

[0073] like Figure 3 The diagram shown is a flowchart of the joint optimization of key parameters proposed in this invention, used to simultaneously determine the high-voltage threshold V. H Low-voltage threshold V L The transformer turns ratio n makes the total life cycle energy utilization efficiency k E Maximum. The optimization process includes the following steps:

[0074] S1, Battery model and operating point discretization;

[0075] (1) Obtain or measure the open-circuit voltage-state-of-charge (OCV)–SOC curve of the energy storage battery to obtain V bat =f OCV (s) functional relationship.

[0076] (2) Divide the SOC interval [SOC min SOC max Discretize into N points s, either uniformly or non-uniformly. i For each discrete point s i Calculate the corresponding battery voltage .

[0077] (3) Set the target output voltage V o Therefore, the partial power ratio q(V) can be calculated at each voltage point. bat ).

[0078] S2. Loss Model and Efficiency Calculation;

[0079] (1) According to the DAB converter loss model (conduction loss P) cond Switching loss P sw Transformer loss P tr ), express the DAB converter loss explicitly as a function of V bat A function of n and q.

[0080] (2) For a given combination of design variables (V) H V L ,n), at each discrete battery voltage point V bat,i Above, determine the current operating mode: if it is in bypass mode, then let η sys,i =1; If it is in the medium-voltage light-part power conversion mode or the low-voltage heavy-part power converter mode, then η is first obtained from the loss model. DAB,i This leads to the system efficiency: .

[0081] S3, Total Cycle Energy Utilization Efficiency k E calculate;

[0082] (1) Weighted average of the entire discharge process in the SOC dimension to obtain the value corresponding to the current (V H V L Energy utilization efficiency of combination (n):

[0083] ;

[0084] The denominator represents the output energy of the ideal battery during the entire discharge process (normalization coefficient), and the numerator represents the effective output energy after considering the losses of the DAB bridge converter.

[0085] S4. Multivariate joint search and optimal selection;

[0086] Based on the established objective function, in order to find the optimal (V) H V L A combination of (V, n) is used to perform a global scan of the design space using a multidimensional discrete grid search algorithm. First, the discrete step size of the variation ratio n is fixed, and then, within the constraints (V... H V L The process involves finding local optima on a plane and then determining the globally optimal parameter combination by comparing the results across all planes. The specific steps are as follows:

[0087] (1) Outer layer scan voltage threshold: within a pre-defined interval, the voltage threshold for V is... H and V L Perform a grid search: where:

[0088] ;

[0089] (2) Inner layer scan ratio n;

[0090] For each group (V) H V L ), within the allowable range [n min ,n max Perform a one-dimensional scan on n and calculate the corresponding k. E (V H V L The optimal ratio under this piecewise combination is obtained by considering n).

[0091] ;

[0092] (3) In each candidate group (V) H V L The maximum power ratio of the component q is checked on n). max Constraints. If not satisfied, the solution is discarded.

[0093] S5, Global Optimal Search;

[0094] Among all combinations that satisfy the constraints, choose the one that makes k... E The largest group:

[0095] ;

[0096] Based on the above scheme, this embodiment is used for verification. Figure 4 , Figure 5 The waveforms shown are experimental waveforms when the converter is in the low-voltage heavy power conversion and medium-voltage light power conversion modes, respectively. From top to bottom, they are the switching transistor drive waveform and the drain-source voltage V. ds And leakage current. It can be observed that soft switching is achieved in both modes. In high-voltage bypass mode, power is directly transferred from the input to the output side, and the main power circuit does not operate, therefore there is no switching waveform.

[0097] Figure 6 The figures show the efficiency curves of the converter under different modes and loads. In the high-voltage direct-through mode, there is no power converter, so the efficiency is approximately 100%. In the other two modes, the converter also has high efficiency, verifying the effectiveness of the technical solution of this invention.

[0098] The above description of the embodiments is provided to enable those skilled in the art to understand and apply the present invention. Those skilled in the art can readily make various modifications to the above embodiments and apply the general principles described herein to other embodiments without creative effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made to the present invention by those skilled in the art based on the disclosure thereof should be within the scope of protection of the present invention.

Claims

1. A dual active bridge partial power converter, comprising an input capacitor C1, a primary-side full-bridge inverter circuit, a high-frequency transformer T, and a leakage inductance L. k Secondary-side full-bridge inverter circuit, output capacitor C2 and bypass switch K a Its characteristics are: The input capacitor C1 is connected in parallel between the positive and negative terminals of the energy storage battery and is also connected to the input terminal of the primary-side full-bridge inverter circuit; the output terminal of the primary-side full-bridge inverter circuit is connected to the primary winding of the high-frequency transformer T; the secondary winding of the high-frequency transformer T is connected through the leakage inductance L. k The secondary-side full-bridge inverter circuit is connected to its input terminal; the output terminal of the secondary-side full-bridge inverter circuit is connected in parallel to the output capacitor C2; one end of the output capacitor C2 is connected to the bypass switch K. a One end of the output capacitor C2 is connected to the positive terminal of the converter output and then to the positive terminal of the load. The other end of the load is connected to the negative terminal of the energy storage battery. The other end of the output capacitor C2 is connected to the bypass switch K. a The other end is connected to the positive terminal of the battery.

2. The dual active bridge power converter according to claim 1, characterized in that: The energy storage battery includes lithium iron phosphate batteries, ternary lithium batteries, or sodium-ion batteries.

3. The control method for the dual active bridge power converter according to claim 1 or 2, characterized in that, Includes the following steps: Detecting the voltage V of the energy storage battery bat and compare it with the preset high voltage threshold V. H and low-pressure threshold V L By comparison, the system is divided into high-voltage bypass mode, medium-voltage light-section power conversion mode, and low-voltage heavy-section power conversion mode; among which: High-voltage bypass mode: when V bat ≥V H At that time, drive the bypass switch K a Close and turn off all switching devices; Medium-voltage light-power conversion mode: when V L ≤V bat <V H At that time, drive the bypass switch K a Disconnect and drive the partial power converter to operate in light partial power conversion mode; Low-voltage heavy-duty power conversion mode: when V bat <V L At that time, control the bypass switch K a Keep it disconnected and drive the partial power converter to operate in heavy partial power conversion mode.

4. The control method for the dual active bridge power converter according to claim 3, characterized in that, The high-voltage bypass mode, medium-voltage light-part power conversion mode, and low-voltage heavy-part power conversion mode are all implemented by setting a voltage hysteresis region; wherein, a high-voltage entry threshold V is set. H,on High voltage exit threshold V H,off Low-pressure entry threshold V L,on and low-voltage exit threshold V L,off And V H,off <V H,on V L,off <V L,on ; When V is satisfied bat ≥V H,on At that time, the power conversion mode of the medium-voltage light section is switched to the high-voltage bypass mode; When V is satisfied bat ≤V H,off At that time, it switches from high-voltage bypass mode back to medium-voltage light-power conversion mode; When V is satisfied bat <V L,on At that time, the power conversion mode of the medium-voltage light component is switched to the power conversion mode of the low-voltage heavy component; When V is satisfied bat ≥V L,off At that time, the power conversion mode is switched from the low-voltage heavy-duty component to the medium-voltage light-duty component.

5. The control method for the dual active bridge power converter according to claim 3, characterized in that, The medium-voltage light power conversion mode is achieved through three-phase shift modulation, and the phase shift angle of the three-phase shift modulation is controlled within a preset range.

6. The control method for the dual active bridge power converter according to claim 3, characterized in that, The low-voltage heavy-duty power conversion mode is achieved by increasing the phase shift angle control of the three-phase shift modulation, and includes a current limiting unit to limit the peak current in the low-voltage region.

7. The control method for the dual active bridge power converter according to claim 3, characterized in that, It also includes a joint optimization step for key parameters to maximize the battery's full-cycle energy efficiency k. E To achieve this goal, the high-voltage threshold V of the converter is determined by adding threshold voltage constraints, transformer turns ratio constraints, and partial power ratio constraints. H Low-voltage threshold V L And the optimal combination of three key parameters: the turns ratio n of the high-frequency transformer.

8. The control method for the dual active bridge power converter according to claim 6, characterized in that, The joint optimization step for the key parameters includes the following steps: S1. Obtain the open-circuit voltage-state-of-charge curve of the energy storage battery, and discretize the SOC interval into N calculation points; S2. Establish a loss model for the converter. This loss model characterizes the converter loss in relation to the battery voltage V. bat The functional relationship between the turns ratio n and the partial power ratio q of a high-frequency transformer; S3, the total cycle energy utilization efficiency k E Defined as the weighted average of the converter's total efficiency across N calculation points; S4, to maximize the full-cycle energy utilization efficiency k E Using the objective function, and under the premise of satisfying threshold voltage constraints, transformer turns ratio constraints, and partial power ratio constraints, a joint search strategy is adopted to simultaneously determine the high-voltage threshold V of the converter. H Low-voltage threshold V L And the optimal combination of the turns ratio n of the high-frequency transformer.

Images