Dual-active bridge series resonant converter control method and system, and converter

Abstract

The invention relates to the technical field of converters, in particular to a control method and system for a double-active-bridge series resonant converter and the converter, and the method comprises the steps: if it is determined that the double-active-bridge series resonant converter enters a light-load working condition, according to a load current reference value and a preset target fitting relation, calculating a load current reference value; a target out-shift phase angle corresponding to a load current reference value is obtained, the load current reference value is a current value output by an expected output port, and the load current and the out-shift phase angle in the target fitting relation are in a negative correlation relation under the light load working condition; based on the target out-shift phase angle, completing adjustment of the out-shift phase angle of the dual-active bridge series resonant converter; according to the load current reference value, adjusting an inner phase shift angle and a switching period of the dual-active bridge series resonant converter to complete control of the dual-active bridge series resonant converter; the method can reduce the hard open current of each switching device under the light load condition as much as possible.

Description

Technical Field

[0001] The present invention relates to the technical field of converters, and in particular to a control method, system and converter of a dual active bridge series resonant converter. Background Art

[0002] With the advancement of power electronics technology, the Dual Active Bridge Series Resonant Converter (DBSRC) is playing an increasingly important role in modern power systems due to its superior performance characteristics. Combining the advantages of a resonant converter with a dual active bridge structure, the DBSRC not only achieves high-frequency electrical isolation and bidirectional power transmission, but also exhibits soft switching characteristics. This makes it a promising candidate for medium- and high-power applications such as renewable energy grid integration, electric vehicle fast charging, and data center power supply.

[0003] However, in actual use, the dual active bridge series resonant converter still has some defects. For example, under high voltage and light load output conditions, the dual active bridge series resonant converter has the problem of high temperature rise of the active side (primary side) switching devices / switch tubes, which leads to a large hard-open current of the active side switching devices and large turn-on losses, reducing the conversion efficiency and causing a series of heat dissipation problems, posing certain thermal risks. Summary of the Invention

[0004] The present invention provides a dual-active-bridge series resonant converter control method, system, and converter to solve the problems in the prior art of dual-active-bridge series resonant converters, such as high temperature rise of active-side switching devices and large hard-on current of active-side switching devices under high-voltage and light-load output conditions.

[0005] The present invention provides a dual active bridge series resonant converter control method for controlling a two-port circuit of the dual active bridge series resonant converter, wherein the two-port circuit includes an input port and an output port. The method includes:

[0006] If it is determined that the dual active bridge series resonant converter enters a light load condition, a target external phase shift angle corresponding to the load current reference value is obtained according to a load current reference value and a preset target fitting relationship, wherein the load current reference value is a current value expected to be output by the output port, and in the target fitting relationship, the load current and the external phase shift angle are negatively correlated under the light load condition;

[0007] Based on the target external phase shift angle, adjusting the external phase shift angle of the dual active bridge series resonant converter is completed;

[0008] According to the load current reference value, the internal phase shift angle and the switching period of the dual active bridge series resonant converter are adjusted to complete the control of the dual active bridge series resonant converter.

[0009] In some embodiments of the present invention, determining whether the dual active bridge series resonant converter enters a light load condition includes:

[0010] Acquiring voltage-related information, the voltage-related information including: an actual value of the input voltage of the input port, and an actual value of the output voltage of the output port;

[0011] Obtaining a load boundary value corresponding to the voltage-related information according to a preset boundary fitting relationship and the voltage-related information, wherein the boundary fitting relationship is a fitting relationship between the voltage-related information and the load boundary value, and the load boundary value is a value of a load current output by an output port of the dual active bridge series resonant converter when the dual active bridge series resonant converter enters a light-load operating condition;

[0012] Obtaining an actual value of the load current of the output port;

[0013] When the actual value of the load current drops to the load threshold value, it is determined that the dual active bridge series resonant converter enters a light load condition.

[0014] In some embodiments of the present invention, obtaining the boundary fitting relationship includes:

[0015] Acquire multiple sample point information, the sample point information including: corresponding input voltage sample values, output voltage sample values, and load boundary sample values, the load boundary sample values ​​being sample values ​​of the load current output by the dual active bridge series resonant converter when it enters a light load condition;

[0016] sorting the plurality of sample point information according to the magnitude of the input voltage sample value or the magnitude of the output voltage sample value to obtain a sample point sequence;

[0017] If the input voltage sample values ​​of a plurality of consecutive sample point information in the sample point sequence are the same, the sample point information with the same input voltage sample value is determined as the first sample point information, and the remaining sample point information is determined as the second sample point information;

[0018] Fitting is performed on the first sample point information and the second sample point information respectively to obtain the boundary fitting relationship.

[0019] In some embodiments of the present invention, fitting the first sample point information and the second sample point information respectively to obtain the boundary fitting relationship includes:

[0020] Determine the ratio between the output voltage sample value and the input voltage sample value in the first sample point information as a first independent variable, and determine the load boundary sample value in the first sample point information as a first dependent variable;

[0021] Performing fitting based on the first independent variable and the first dependent variable to obtain a first fitting relationship;

[0022] obtaining a proportional relationship between input voltage sample values ​​and output voltage sample values ​​in a plurality of second sample point information; determining a ratio between the output voltage sample value and the input voltage sample value in the second sample point information as an intermediate independent variable; and based on the proportional relationship, replacing the input voltage sample value in the intermediate independent variable with an expression containing the corresponding output voltage sample value to obtain a second independent variable; and determining the load boundary sample value in the first sample point information as a second dependent variable;

[0023] Performing fitting based on the second independent variable and the second dependent variable to obtain a second fitting relationship;

[0024] The first fitting relationship and the second fitting relationship are determined as the boundary fitting relationship.

[0025] In some embodiments of the present invention, determining the target fitting relationship includes:

[0026] Acquire a plurality of information to be fitted, wherein the information to be fitted includes mutually corresponding load current sample values ​​and external phase shift angle sample values;

[0027] A cubic polynomial fitting is performed on the information to be fitted to obtain the target fitting relationship, where the independent variable in the target fitting relationship is the load current sample value, and the dependent variable in the target fitting relationship is the external shift phase angle sample value.

[0028] In some embodiments of the present invention, obtaining the load current reference value includes:

[0029] Obtaining an actual input current value of the input port and a preset input current limit value;

[0030] Performing a proportional-integral operation based on a difference between the actual input current value and the input current limit value to obtain a first current value;

[0031] Acquire an actual output voltage value and an output voltage command value of the output port, wherein the output voltage command value refers to an output voltage value in a control command received by the dual active bridge series resonant converter;

[0032] Performing a proportional-integral operation based on a difference between the actual output voltage value and the output voltage command value to obtain a second current value;

[0033] Acquire a third current value, where the third current value refers to the output current value in the control instruction;

[0034] A minimum value among the first current value, the second current value, and the third current value is determined as the load current reference value.

[0035] In some embodiments of the present invention, adjusting the internal phase shift angle and switching period of the dual active bridge series resonant converter according to the load current reference value to complete the dual active bridge series resonant converter control includes:

[0036] Obtaining an actual value of the load current of the output port;

[0037] Performing a proportional-integral operation based on a difference between the load current reference value and the load current actual value to obtain a first switching period;

[0038] performing a proportional resonance operation according to the first switching period to obtain a second switching period;

[0039] If the second switching period is within a preset switching period threshold range, the second switching period is determined as a target switching period, and the preset inner phase shift angle value is determined as a target inner phase shift angle;

[0040] If the second switching period is less than a minimum value in the switching period threshold range and the second switching period is greater than 0, the minimum value in the switching period threshold range is determined as a target switching period, and a ratio between the second switching period and twice the target switching period is determined as a target inner phase shift angle;

[0041] According to the target switching period and the target internal phase shift angle, the internal phase shift angle and the switching period of the dual active bridge series resonant converter are adjusted to complete the control of the dual active bridge series resonant converter.

[0042] The present invention also provides a dual active bridge series resonant converter control system for controlling a two-port circuit of a dual active bridge series resonant converter, wherein the two-port circuit includes an input port and an output port. The system includes:

[0043] a target external phase shift angle acquisition module, configured to obtain, if it is determined that the dual active bridge series resonant converter enters a light load condition, a target external phase shift angle corresponding to the load current reference value based on a load current reference value and a preset target fitting relationship, wherein the load current reference value is a current value expected to be output by the output port, and in the target fitting relationship, the load current and the external phase shift angle are negatively correlated under the light load condition;

[0044] A first adjustment module, configured to adjust the external phase shift angle of the dual active bridge series resonant converter based on the target external phase shift angle;

[0045] The second adjustment module is used to adjust the internal phase shift angle and switching period of the dual active bridge series resonant converter according to the load current reference value to complete the control of the dual active bridge series resonant converter.

[0046] The present invention also provides a dual-active-bridge series resonant converter, comprising: an active-side full bridge, a resonant circuit, a passive-side full bridge, and the dual-active-bridge series resonant converter control system as described above, wherein the active-side full bridge includes the input port, and the passive-side full bridge includes the output port;

[0047] The dual active bridge series resonant converter control system is used to control the switching devices in the active side full bridge and the passive side full bridge based on the adjustment signal of the outer phase shift angle, the adjustment signal of the inner phase shift angle, and the adjustment signal of the switching period.

[0048] The present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program is used to enable a computer to execute the dual active bridge series resonant converter control method provided in any one of the above embodiments.

[0049] Beneficial effects of the present invention: The present invention provides a dual-active bridge series resonant converter control method, system and converter. The method obtains a target external phase shift angle corresponding to the load current reference value according to the load current reference value and a preset target fitting relationship when determining that the dual-active bridge series resonant converter enters a light-load condition. The load current reference value is the current value output by the desired output port. In the target fitting relationship, the load current and the external phase shift angle are negatively correlated under the light-load condition. Based on the target external phase shift angle, the external phase shift angle of the dual-active bridge series resonant converter is adjusted. According to the load current reference value, the internal phase shift angle and the switching period of the dual-active bridge series resonant converter are adjusted to complete the control of the dual-active bridge series resonant converter. By adjusting the external phase shift angle, internal phase shift angle, and switching period under light-load conditions, this method can minimize the hard-on current of each switching device under light-load conditions, while widening the ZVS (Zero Voltage Switching) turn-on range and reducing switching losses, thereby avoiding problems such as temperature rise and thermal risks under high-voltage light-load output conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 A schematic flow chart of a control method for a dual active bridge series resonant converter according to an embodiment of the present invention;

[0051] Figure 2An example diagram of the relationship between the external phase shift angle and the load current reference value when the external phase shift angle light load optimization is not performed, provided by an embodiment of the present invention;

[0052] Figure 3 An example diagram of the relationship between the external phase shift angle and the load current reference value under the condition of linear fitting of the external phase shift angle under light load provided by one embodiment of the present invention;

[0053] Figure 4 An example diagram of the relationship between the external phase shift angle obtained by fitting the external phase shift angle light-load cubic polynomial and the load current reference value provided by one embodiment of the present invention;

[0054] Figure 5 A schematic diagram of a specific flow chart of a dual active bridge series resonant converter control method provided in one embodiment of the present invention;

[0055] Figure 6 A schematic structural diagram of a dual active bridge series resonant converter control system provided by one embodiment of the present invention;

[0056] Figure 7 A schematic structural diagram of a dual active bridge series resonant converter provided by one embodiment of the present invention;

[0057] Figure 8 This is an example diagram of the control timing of each switching device of the dual active bridge series resonant converter control system provided by one embodiment of the present invention;

[0058] Figure 9 A schematic structural diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0059] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. The details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other unless they conflict.

[0060] It should be noted that the illustrations provided in the following embodiments are merely schematic illustrations of the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0061] In the following description, numerous details are discussed to provide a more thorough explanation of the embodiments of the present invention. However, it will be apparent to those skilled in the art that the embodiments of the present invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring the embodiments of the present invention.

[0062] To facilitate understanding of the dual active bridge series resonant converter control method, system, and converter provided by the present invention, some technical terms involved in the present invention are explained below.

[0063] Dual active bridge series resonant converter: A power electronic converter based on a dual active bridge topology combined with series resonance. It has significant advantages in efficient power conversion, low switching losses, and high power density, and is widely used in fields requiring efficient energy transmission and conversion.

[0064] Light load condition: The output power of the dual active bridge series resonant converter is much lower than its rated power. In this case, soft switching (such as ZVS) may fail, increasing switching losses and reducing efficiency.

[0065] High-voltage, light-load output operating condition: This is the operating state of the dual-active-bridge series resonant converter operating at high output voltage and low output power. In this case, the hard-on current of the active-side switching device increases, resulting in large turn-on losses, which affects efficiency and heat dissipation, posing a certain thermal risk.

[0066] Switching cycle: The time it takes for a complete switching action in a dual active bridge series resonant converter (such as the alternating conduction of the upper and lower tubes of the full bridge (H bridge)).

[0067] External phase shift angle: the phase difference between the active side full bridge (input side or primary side full bridge) and the passive side full bridge (output side or secondary side full bridge).

[0068] Internal phase shift angle: The phase difference between different switching devices (such as MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) and IGBT (Insulated Gate Bipolar Transistor)) within a single full-bridge.

[0069] Zero Voltage Switching (ZVS): A soft switching technology that significantly reduces switching losses and electromagnetic interference (EMI) by triggering the switching action when the voltage across the switching device is zero.

[0070] Hard-on current: The current flowing when a switching device is turned on or off under non-zero voltage (hard switching) conditions. This current causes significant switching losses and may cause voltage / current stress, as well as electromagnetic interference and other problems.

[0071] Please refer to Figure 1 , Figure 1 A flow chart of a dual active bridge series resonant converter control method according to an embodiment of the present invention is provided. The method is used to control a two-port circuit of a dual active bridge series resonant converter, wherein the two-port circuit includes an input port and an output port. Figure 1 As shown, the method includes:

[0072] S110: If it is determined that the dual active bridge series resonant converter enters a light load condition, a target external phase shift angle corresponding to the load current reference value is obtained based on the load current reference value and a preset target fitting relationship. The load current reference value is the current value expected to be output by the output port. In the target fitting relationship, the load current and the external phase shift angle are negatively correlated under the light load condition.

[0073] It should be noted that by obtaining the target external phase shift angle based on the preset target fitting relationship, it is easy to adjust the external phase shift angle, thereby helping to reduce the hard-on current under light load conditions.

[0074] S120: Based on the target external phase shift angle, complete adjustment of the external phase shift angle of the dual active bridge series resonant converter.

[0075] In some examples of this embodiment, the external phase shift angle of the dual active bridge series resonant converter may be directly adjusted to the target external phase shift angle.

[0076] S130: Adjusting the internal phase shift angle and the switching period of the dual active bridge series resonant converter according to the load current reference value to complete the control of the dual active bridge series resonant converter.

[0077] In some examples of this embodiment, a preset mapping relationship and a neural network model can be used to obtain the target internal phase shift angle and target switching period of the dual active bridge series resonant converter, so that the internal phase shift angle of the dual active bridge series resonant converter is adjusted based on the target internal phase shift angle, and the switching period of the dual active bridge series resonant converter is adjusted based on the target switching period. For example, a mapping relationship between a load current reference value and a mapping value (including an internal phase shift angle and a switching period) is preset, and based on the mapping relationship, the corresponding target internal phase shift angle and target switching period are obtained. Alternatively, the load current reference value is input into a pre-trained neural network model to perform target internal phase shift angle prediction and target switching period prediction, and obtain the target internal phase shift angle and target switching period output by the neural network model.

[0078] It should be noted that the internal phase shift angle in this embodiment is the internal phase shift angle of the switching devices in the active side full bridge. Adjusting the internal phase shift angle refers to adjusting the internal phase shift angle of the switching devices in the active side full bridge.

[0079] It can be understood that the dual-active-bridge series resonant converter control method in the above embodiment can effectively reduce the hard-on current by adjusting the external phase shift angle between the bridges, the internal phase shift angle of the active-side full bridge, and the switching period of the dual-active-bridge series resonant converter. Moreover, it can, to a certain extent, widen the ZVS turn-on range and reduce switching losses, thereby avoiding problems such as temperature rise and thermal risks under high-voltage and light-load output conditions. Widening the ZVS turn-on range means that by optimizing the control strategy and other means, the switching devices in the dual-active-bridge series resonant converter can achieve zero voltage turn-on under wider load conditions, input voltage ranges, or parameter changes, thereby reducing switching losses and improving efficiency.

[0080] In some embodiments, determining that the dual active bridge series resonant converter enters a light load condition includes:

[0081] 1. Obtain voltage-related information, where the voltage-related information includes: an actual value of the input voltage of the input port and an actual value of the output voltage of the output port.

[0082] 2. According to the preset boundary fitting relationship and the voltage association information, a load boundary value corresponding to the voltage association information is obtained, wherein the boundary fitting relationship is a fitting relationship between the voltage association information and the load boundary value, and the load boundary value is the value of the load current output by the output port of the dual active bridge series resonant converter when it enters a light load condition.

[0083] 3. Obtain the actual value of the load current of the output port.

[0084] 4. When the actual value of the load current drops to the load threshold value, it is determined that the dual active bridge series resonant converter enters a light load condition.

[0085] It should be noted that, through the above steps, it is possible to monitor whether the dual active bridge series resonant converter is operating in a light load condition.

[0086] In some embodiments, obtaining the boundary fitting relationship includes:

[0087] 1. Acquire multiple sample point information, wherein the sample point information includes: corresponding input voltage sample values, output voltage sample values, and load boundary sample values, wherein the load boundary sample values ​​are sample values ​​of the load current output by the dual active bridge series resonant converter when it enters a light load condition.

[0088] It is understandable that the input voltage sample value and the output voltage sample value can be obtained through instrument detection, and the load boundary sample value can be obtained through experimental testing or manually set.

[0089] 2. Sort the plurality of sample point information according to the magnitude of the input voltage sample value or the magnitude of the output voltage sample value to obtain a sample point sequence.

[0090] 3. If the input voltage sample values ​​of a plurality of consecutive sample point information in the sample point sequence are the same, the sample point information with the same input voltage sample value is determined as the first sample point information, and the remaining sample point information is determined as the second sample point information.

[0091] 4. Fitting the first sample point information and the second sample point information respectively to obtain the boundary fitting relationship.

[0092] It should be noted that by fitting the first sample point information and the second sample point information separately, it is possible to obtain fitting relationships for both the cases where the input voltage sample values ​​are the same and the cases where the input voltage sample values ​​are different, thereby reducing the difficulty of fitting and improving the credibility and accuracy of the resulting boundary fitting relationship. It is understandable that, compared to fitting all sample point information, the above-mentioned segmented fitting method not only reduces the amount of data and the difficulty of fitting for a single fit, but also helps to improve the accuracy of the subsequently obtained boundary fitting relationship and improve the efficiency of subsequent reading or calling of the boundary fitting relationship.

[0093] In some embodiments, fitting the first sample point information and the second sample point information respectively to obtain the boundary fitting relationship includes:

[0094] 1. Determine the ratio between the output voltage sample value and the input voltage sample value in the first sample point information as a first independent variable, and determine the load boundary sample value in the first sample point information as a first dependent variable;

[0095] 2. performing fitting based on the first independent variable and the first dependent variable to obtain a first fitting relationship;

[0096] 3. Obtaining a proportional relationship between input voltage sample values ​​and output voltage sample values ​​in a plurality of second sample point information; determining a ratio between the output voltage sample value and the input voltage sample value in the second sample point information as an intermediate independent variable; and based on the proportional relationship, replacing the input voltage sample value in the intermediate independent variable with an expression containing the corresponding output voltage sample value to obtain a second independent variable; and determining the load boundary sample value in the first sample point information as a second dependent variable;

[0097] 4. performing fitting based on the second independent variable and the second dependent variable to obtain a second fitting relationship;

[0098] 5. Determine the first fitting relationship and the second fitting relationship as the boundary fitting relationship.

[0099] The following further explains how to obtain the above boundary fitting relationship by taking an exemplary dual active bridge series resonant converter as an example.

[0100] First, the operating range and component parameters of the exemplary dual active bridge series resonant converter can be referred to in Table 1 below:

[0101] Table 1 Operating range and component parameters of an exemplary dual active bridge series resonant converter

[0102]

[0103] Based on the parameters shown in Table 1, multiple experiments were conducted to obtain the following Table 2:

[0104] Table 2 Different voltage gains Load cutoff point below

[0105]

[0106] Among them, I TnetDiff Represents the load boundary (sample) value, that is, the load current value at the load boundary point, Indicates the corresponding outward shift phase angle at the load boundary point.

[0107] When V B =750V~880V(V A =800V), the mathematical expression of the first fitting relationship is:

[0108]

[0109] When V B =550V~750V(V A =700V~800V), we get V A and V B The proportional relationship between them:

[0110]

[0111] Simplifying, we get:

[0112] Then, the mathematical expression of the second fitting relationship is obtained as follows:

[0113]

[0114] It can be understood that the above method of obtaining the first fitting relationship and the second fitting relationship is simple to operate, low in cost, and low in computational difficulty.

[0115] In some embodiments, determining the target fitting relationship includes:

[0116] 1. Acquire multiple pieces of information to be fitted, where the information to be fitted includes corresponding load current sample values ​​and external shift phase angle sample values.

[0117] 2. Performing cubic polynomial fitting on the information to be fitted to obtain the target fitting relationship, wherein the independent variable in the target fitting relationship is the load current sample value, and the dependent variable in the target fitting relationship is the external shift phase angle sample value.

[0118] The following Table 3 exemplifies the information to be fitted in the above embodiment. Please refer to Table 3:

[0119] Table 3 Examples of information to be fitted

[0120]

[0121] Among them, I Tnet represents the actual value of the load current of the dual active bridge series resonant converter, f s is the preset switching frequency, Denotes the outward phase angle, D A represents the internal phase shift angle of the active side full bridge, x is the independent variable in the cubic polynomial fitting, y is the dependent variable in the cubic polynomial fitting, and " / " represents the relationship of "or". Performing cubic polynomial fitting on x and y in Table 3 yields:

[0122] y=3.3643x 3 -6.2553x2 +3.9196x-0.0286

[0123] The above mathematical expression is the target fitting relationship obtained by performing cubic polynomial fitting based on Table 3.

[0124] Figure 2 For an example diagram of the relationship between the external phase shift angle and the load current reference value when the external phase shift angle light load optimization is not performed according to an embodiment of the present invention, please refer to Figure 2 , Figure 2 The horizontal axis is the load current reference information i TnetRefConv , the load current reference information i TnetRefConv The value of is the load current reference value i TnetRef , the vertical axis is the outward shift phase angle Figure 2 Take I TnetDiff Draw an auxiliary line perpendicular to the horizontal axis. The auxiliary line to the left is the light load range, and the auxiliary line to the right is the medium and heavy load range. When light load optimization is not performed, as the load current changes, the corresponding external shift phase angle remains unchanged, that is, it remains

[0125] Figure 3 For an example diagram of the relationship between the external phase shift angle and the load current reference value under the condition of linear fitting of the external phase shift angle under light load provided by an embodiment of the present invention, please refer to Figure 3 , Figure 3 In the light load range, a linear fitting method is adopted, so that the load current reference value and the corresponding external shift phase angle in the light load range show a linear downward trend.

[0126] Figure 4 For an example diagram of the relationship between the external phase shift angle obtained by fitting the external phase shift angle light load cubic polynomial provided in one embodiment of the present invention and the load current reference value, please refer to Figure 4 By fitting the external phase shift angle and the load current reference value in the light load range with a cubic polynomial, the external phase shift angle can be smoothly decreased in the light load range. Figure 2 The light-load optimization method of the external phase angle is not performed in the embodiment. The light-load cubic polynomial fitting method of the external phase angle in this embodiment can adjust the external phase angle under light-load conditions. Figure 3 In the linear fitting method, the light load cubic polynomial fitting method of the external phase shift angle in this embodiment can avoid the load boundary point (with I TnetDiff Draw an auxiliary line perpendicular to the horizontal axis. Figure 2 、 3 , 4) the outward phase angle drops sharply, thus avoiding the impact on the efficiency of the converter. Figure 4As shown in the figure, in addition to the light load range, there is also a continuous curve in the medium and heavy load range, namely the dark blue line parallel to the horizontal axis in the medium and heavy load range. It can be understood that through this method, a natural and smooth transition between light load and medium and heavy load can be achieved, which facilitates the overall efficiency optimization and improvement across the entire operating range.

[0127] In some embodiments, obtaining the load current reference value includes:

[0128] 1. Obtain the actual value of the input current of the input port and the preset input current limit value.

[0129] 2. Perform a proportional integral operation based on the difference between the actual input current value and the input current limit value to obtain a first current value.

[0130] 3. Obtaining an actual output voltage value and an output voltage command value of the output port, wherein the output voltage command value refers to an output voltage value in a control command received by the dual active bridge series resonant converter.

[0131] 4. Perform a proportional integral operation based on the difference between the actual output voltage value and the output voltage command value to obtain a second current value.

[0132] 5. Obtain a third current value, where the third current value refers to the output current value in the control instruction.

[0133] 6. Determine the minimum value among the first current value, the second current value, and the third current value as the load current reference value.

[0134] It can be understood that through the above steps, a load current reference value with higher accuracy can be obtained, which helps to improve subsequent control accuracy.

[0135] In some embodiments, adjusting the internal phase shift angle and switching period of the dual active bridge series resonant converter according to the load current reference value to complete the dual active bridge series resonant converter control includes:

[0136] 1. Obtain the actual value of the load current of the output port.

[0137] 2. Perform a proportional-integral operation based on the difference between the load current reference value and the load current actual value to obtain a first switching period.

[0138] 3. Perform proportional resonance operation according to the first switching period to obtain a second switching period.

[0139] 4. If the second switching period is within a preset switching period threshold range, the second switching period is determined as a target switching period, and the preset inner phase shift angle value is determined as a target inner phase shift angle.

[0140] 5. If the second switching period is less than the minimum value in the switching period threshold range and the second switching period is greater than 0, the minimum value in the switching period threshold range is determined as the target switching period, and the ratio of the second switching period to twice the target switching period is determined as the target inner phase shift angle.

[0141] 6. According to the target switching period and the target internal phase shift angle, the internal phase shift angle and the switching period of the dual active bridge series resonant converter are adjusted to complete the control of the dual active bridge series resonant converter.

[0142] It can be understood that through the above steps, the internal phase shift angle and switching period of the dual active bridge series resonant converter can be adjusted in real time under light load conditions, avoiding the problem of the internal phase shift angle dropping too fast under high voltage and light load conditions, resulting in increased hard-opening current and increased temperature rise.

[0143] In some experiments, the dual active bridge series resonant converter is controlled to run in the forward direction and its parameters are set to V A =800V, V B =880V, f s =190kHz. When the dual-active bridge series resonant converter enters the light-load range (light-load operating condition), experimental data collection shows that as the dual-active bridge series resonant converter gradually approaches light load, its active-side inner phase shift angle shows a downward trend. This leads to an increase in the hard-on current of the active-side switching device and an increase in turn-on loss, while also affecting the converter's operating efficiency and heat dissipation, posing a certain thermal risk. The dual-active bridge series resonant converter control method in the above embodiment can effectively avoid the occurrence of the above situation by adjusting its multiple modulation variables, namely, the outer phase shift angle, the inner phase shift angle, and the switching period, when the dual-active bridge series resonant converter enters the light-load range. This method has low cost and strong real-time performance.

[0144] The control method of the dual active bridge series resonant converter in the above embodiment is explained below with reference to a specific embodiment.

[0145] Please refer to Figure 5 For ease of explanation, Figure 5 The entire process is divided into three branches, namely the first branch (used to obtain the load current reference value i TnetRef ), a second branch (for obtaining a target outer phase shift angle), and a third branch (for obtaining a target switching period and a target inner phase shift angle), wherein the first branch includes:

[0146] 1. Obtain the actual value of the input current I at the input port of the dual active bridge series resonant converter AC_Rms , and the preset input current limit value I AC_Lim .

[0147] 2. Input current limit value I AC_Lim The actual value of input current I AC_Rms Perform difference calculation to get I ACErr .

[0148] 3. Based on I ACErr A proportional-integral (PI) operation is performed to obtain a first current value.

[0149] 4. Obtain the actual output voltage value U of the output port of the dual active bridge series resonant converter Tnet_Notch And the output voltage command value U TnetCmd .

[0150] 5. Output voltage command value U TnetCmd And the actual value of output voltage U Tnet_Notch Perform difference calculation to get U TnetErr .

[0151] 6. U TnetErr A proportional-integral (PI) operation is performed to obtain a second current value.

[0152] 7. Obtaining the third current value I TnetCmd .

[0153] 8. For the first current value, the second current value, and the third current value I TnetCmd Perform minimum operation (Min) to obtain the load current reference value i TnetRef .

[0154] The second branch includes:

[0155] 1. Obtaining the load threshold value I TnetDiff Specifically, voltage-related information is obtained, and the voltage-related information includes: the actual value of the input voltage of the input port and the actual value of the output voltage of the output port; according to the preset boundary fitting relationship and the voltage-related information, the load boundary value corresponding to the voltage-related information is obtained.

[0156] 2. Obtain the load threshold value I TnetDiff The corresponding outward phase angle

[0157] 3. Set the load current reference value i TnetRef Determine as i TnetRefConv (The horizontal axis of the target fitting relationship is Figure 5The value of the fitting relationship corresponding to the green curve in the figure.

[0158] 4. According to the load current reference value i TnetRef The relationship between the target and the target is fitted to obtain the corresponding target outward shift phase angle target.

[0159] 5. Determine whether the target external phase shift angle is within the preset external phase shift angle threshold range Within (the mathematical expression of this operation is Limit: Limit indicates a limit), if so, it is determined that the target outward shift phase angle is valid.

[0160] 6. Perform ramp signal processing (Ramp) on the effective target external phase shift angle to obtain the final external phase shift angle modulation. Based on the external phase shift angle modulation, the external phase shift angle of the dual active bridge series resonant converter is adjusted. Make adjustments.

[0161] The third branch includes:

[0162] 1. Reference value of load current i TnetRef Perform ramp signal processing (Ramp) to obtain the load current modulation amount i TnetRefTmp .

[0163] 2. Load current modulation i TnetRefTmp The actual value of the load current i Tnet Perform difference operation to get I TnetErr .

[0164] 3. According to the difference I TnetErr Perform proportional-integral operation to obtain the first switching period.

[0165] 4. Determine whether the first switching cycle is within the preset threshold range [0, T s_max ] (The mathematical expression of this operation is Limit: [0, T s_max ]), if so, it is determined that the first switching cycle is valid, if not, a new first switching cycle is re-determined.

[0166] 5. When the first switching cycle is determined to be valid, a proportional resonance (PR) operation is performed on the first switching cycle to obtain the second switching cycle T Loopout .

[0167] 6. If the second switching period T Loopout Is it within the preset switching cycle threshold range [T s_min , T s_max ] (The mathematical expression of this operation is If in range:[T s_min , T s_max]), if so, the second switching period is determined as the target switching period (T s =T Loopout ). The second switching cycle is subjected to ramp signal processing to obtain a switching cycle modulation amount. Based on the switching cycle modulation amount, the switching cycle T of the dual active bridge series resonant converter is modulated. s Adjust the preset value of the inner phase shift angle, such as 0.5, as the target inner phase shift angle.

[0168] 7. If the second switching period is less than the minimum value in the switching period threshold range, and the second switching period is greater than 0 (the mathematical expression of the judgment condition is If in range: [0, T s_min ]), then the minimum value T in the switching cycle threshold range is s_min The ratio between the second switching period and twice the target switching period is determined as the target internal phase shift angle, which is mathematically expressed as: The target internal phase shift angle is processed by ramp signal to adjust the internal phase shift angle D of the dual active bridge series resonant converter. A Make adjustments.

[0169] The dual active bridge series resonant converter control system provided by the present invention is described below. The dual active bridge series resonant converter control system described below and the dual active bridge series resonant converter control method described above can refer to each other.

[0170] Please refer to Figure 6 The system is used to control a two-port circuit of a dual active bridge series resonant converter, wherein the two-port circuit includes an input port and an output port. The system includes:

[0171] a target external phase shift angle acquisition module 610 for obtaining, if it is determined that the dual active bridge series resonant converter has entered a light load condition, a target external phase shift angle corresponding to the load current reference value based on a load current reference value and a preset target fitting relationship, wherein the load current reference value is a current value expected to be output by the output port, and in the target fitting relationship, the load current and the external phase shift angle are negatively correlated under the light load condition;

[0172] A first adjustment module 620 is configured to adjust the external phase shift angle of the dual active bridge series resonant converter based on the target external phase shift angle;

[0173] The second adjustment module 630 is configured to adjust the internal phase shift angle and switching period of the dual active bridge series resonant converter based on the load current reference value to complete dual active bridge series resonant converter control. The target external phase shift angle acquisition module 610, the first adjustment module 620, and the second adjustment module 630 can achieve the technical effects achieved by the dual active bridge series resonant converter control method in the above-described embodiment and are not further described here.

[0174] It should be noted that the dual-active-bridge series resonant converter control method provided in the above embodiment and the dual-active-bridge series resonant converter control system are based on the same concept, wherein the specific manner in which each module performs operations has been described in detail in the method embodiment and will not be repeated here. In actual applications, the dual-active-bridge series resonant converter control system provided in the above embodiment can allocate the above functions to different functional modules as needed, that is, divide the internal structure of the system into different functional modules to complete all or part of the functions described above, and this is not limited here.

[0175] The dual active bridge series resonant converter control system may be an MCU (Microcontroller Unit) or the like.

[0176] This embodiment also provides a dual active bridge series resonant converter, please refer to Figure 7 The dual active bridge series resonant converter comprises: an active side full bridge, a resonant circuit, a passive side full bridge, and the dual active bridge series resonant converter control system as described above ( Figure 7 The dual active bridge series resonant converter control system is hidden in the figure), the active side full bridge includes the input port, and the passive side full bridge includes the output port;

[0177] The dual active bridge series resonant converter control system is used to control the switching devices in the active side full bridge and the passive side full bridge based on the adjustment signal of the outer phase shift angle, the adjustment signal of the inner phase shift angle, and the adjustment signal of the switching period.

[0178] In some examples of this embodiment, the dual active bridge series resonant converter control system converts the target external phase shift angle, target internal phase shift angle, and target switching period in the above embodiments into drive signals for each switching device of the active side full bridge and the passive side full bridge, and uses the drive signals to control each switching device of the active side full bridge and the passive side full bridge, thereby completing the control of the dual active bridge series resonant converter.

[0179] In some embodiments, the active side full bridge includes a first switch device Q1, a second switch device Q2, a third switch device Q3, and a fourth switch device Q4. The passive side full bridge includes a fifth switch device Q5, a sixth switch device Q6, a seventh switch device Q7, and an eighth switch device Q8. The input side power supply V A The positive electrode, the first switching device Q1, the second switching device Q2, are connected to the input side power supply V A The negative pole of the input power supply V A The positive electrode, the third switch device Q3, and the fourth switch device Q4 are connected to the input side power supply V A The negative pole of the input power supply V A There is an input capacitor C in parallel A The series resonant circuit includes the first resonant capacitor C r1 , the second resonant capacitor C r2 , and the resonant inductor L r . Output side power supply V B The positive electrode, the fifth switch device Q5, and the sixth switch device Q6 are connected to the output side power supply V B The negative pole of the output power supply V B The positive electrode, the seventh switching device Q7, and the eighth switching device Q8 are connected to the output side power supply V B The negative pole of the output power supply V B There is an output capacitor C in parallel B .

[0180] Figure 8 For an example diagram of the control timing of each switching device of the dual active bridge series resonant converter control system provided by an embodiment of the present invention, please refer to Figure 8 , the target switching period, target outer phase shift angle, and target inner phase shift angle can be converted into drive signals G1 to G8 of the first switching device Q1, the second switching device Q2, the third switching device Q3, the fourth switching device Q4, the fifth switching device Q5, the sixth switching device Q6, the seventh switching device Q7, and the eighth switching device Q8, thereby realizing dynamic control of the dual active bridge series resonant converter. B Indicates the on-duty cycle of each switching device.

[0181] In some embodiments, the output power P of the dual active bridge series resonant converter is o The mathematical expression is:

[0182]

[0183] in, V A Indicates the input voltage, V B Indicates the output voltage, f r Represents the resonant frequency, fs represents the switching frequency, Z0 represents the characteristic impedance, which is obtained based on the resonant inductor and the resonant capacitor, π represents pi, and “·” represents dot product.

[0184] In some embodiments, an electronic device is also provided. The electronic device may be a server, and its internal structure is shown in FIG. Figure 9 As shown. The electronic device includes a processor, a memory, a network interface and a database connected via a system bus. The processor of the electronic device is used to provide computing and control capabilities. The memory of the electronic device includes a non-volatile and / or volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and computer program in the non-volatile storage medium. The network interface of the electronic device is used to communicate with an external client via a network connection. When the computer program is executed by the processor, the functions or steps on the server side of the above method are implemented.

[0185] In some embodiments, an electronic device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the following steps are implemented: if it is determined that the dual-active bridge series resonant converter enters a light-load operating condition, a target external phase shift angle corresponding to the load current reference value is obtained based on a load current reference value and a preset target fitting relationship, wherein the load current reference value is a current value output from a desired output port, and in the target fitting relationship, the load current and the external phase shift angle are negatively correlated under the light-load operating condition; based on the target external phase shift angle, the external phase shift angle of the dual-active bridge series resonant converter is adjusted; and according to the load current reference value, the internal phase shift angle and the switching period of the dual-active bridge series resonant converter are adjusted to complete control of the dual-active bridge series resonant converter.

[0186] In some embodiments, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented: if it is determined that the dual-active bridge series resonant converter enters a light-load condition, then based on the load current reference value and a preset target fitting relationship, a target external phase shift angle corresponding to the load current reference value is obtained, the load current reference value is the current value output by the desired output port, and in the target fitting relationship, the load current and the external phase shift angle are negatively correlated under the light-load condition; based on the target external phase shift angle, the external phase shift angle of the dual-active bridge series resonant converter is adjusted; according to the load current reference value, the internal phase shift angle and switching period of the dual-active bridge series resonant converter are adjusted to complete the control of the dual-active bridge series resonant converter.

[0187] It should be noted that the above functions or steps that can be implemented by the computer-readable storage medium or electronic device can be referred to the relevant descriptions on the server side and the client side in the aforementioned method embodiment. To avoid repetition, they will not be described one by one here.

[0188] The flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architecture, functions and operations of the methods and computer program products according to various embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram can represent a module, program segment, or a part of code, and the module, program segment, or a part of code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order than that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of the boxes in the block diagram and / or flowchart, can be implemented by a dedicated hardware-based system that performs the specified function or operation, or can be implemented by a combination of dedicated hardware and computer instructions.

[0189] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A dual active bridge series resonant converter control method, characterized in that: The method is used to control a two-port circuit of a dual active bridge series resonant converter, wherein the two-port circuit includes an input port and an output port, and comprises: If it is determined that the dual active bridge series resonant converter enters a light load condition, a target external phase shift angle corresponding to the load current reference value is obtained according to a load current reference value and a preset target fitting relationship, wherein the load current reference value is a current value expected to be output by the output port, and in the target fitting relationship, the load current and the external phase shift angle are negatively correlated under the light load condition; Based on the target external phase shift angle, adjusting the external phase shift angle of the dual active bridge series resonant converter is completed; According to the load current reference value, the internal phase shift angle and the switching period of the dual active bridge series resonant converter are adjusted to complete the control of the dual active bridge series resonant converter.

2. The dual active bridge series resonant converter control method according to claim 1, wherein: Determine whether the dual active bridge series resonant converter enters the light load condition, including: Acquiring voltage-related information, the voltage-related information including: an actual value of the input voltage of the input port, and an actual value of the output voltage of the output port; Obtaining a load boundary value corresponding to the voltage-related information according to a preset boundary fitting relationship and the voltage-related information, wherein the boundary fitting relationship is a fitting relationship between the voltage-related information and the load boundary value, and the load boundary value is a value of a load current output by an output port of the dual active bridge series resonant converter when the dual active bridge series resonant converter enters a light-load operating condition; Obtaining an actual value of the load current of the output port; When the actual value of the load current drops to the load threshold value, it is determined that the dual active bridge series resonant converter enters a light load condition.

3. The dual active bridge series resonant converter control method according to claim 2, wherein: The acquisition of the boundary fitting relationship includes: Acquire multiple sample point information, the sample point information including: corresponding input voltage sample values, output voltage sample values, and load boundary sample values, the load boundary sample values ​​being sample values ​​of the load current output by the dual active bridge series resonant converter when it enters a light load condition; sorting the plurality of sample point information according to the magnitude of the input voltage sample value or the magnitude of the output voltage sample value to obtain a sample point sequence; If the input voltage sample values ​​of a plurality of consecutive sample point information in the sample point sequence are the same, the sample point information with the same input voltage sample value is determined as the first sample point information, and the remaining sample point information is determined as the second sample point information; Fitting is performed on the first sample point information and the second sample point information respectively to obtain the boundary fitting relationship.

4. The dual active bridge series resonant converter control method according to claim 3, wherein: Fitting the first sample point information and the second sample point information respectively to obtain the boundary fitting relationship includes: Determine the ratio between the output voltage sample value and the input voltage sample value in the first sample point information as a first independent variable, and determine the load boundary sample value in the first sample point information as a first dependent variable; Performing fitting based on the first independent variable and the first dependent variable to obtain a first fitting relationship; obtaining a proportional relationship between input voltage sample values ​​and output voltage sample values ​​in a plurality of second sample point information; determining a ratio between the output voltage sample value and the input voltage sample value in the second sample point information as an intermediate independent variable; and based on the proportional relationship, replacing the input voltage sample value in the intermediate independent variable with an expression containing the corresponding output voltage sample value to obtain a second independent variable; and determining the load boundary sample value in the first sample point information as a second dependent variable; Performing fitting based on the second independent variable and the second dependent variable to obtain a second fitting relationship; The first fitting relationship and the second fitting relationship are determined as the boundary fitting relationship.

5. The dual active bridge series resonant converter control method according to claim 1, wherein: Determination of the target fitting relationship includes: Acquire a plurality of information to be fitted, wherein the information to be fitted includes mutually corresponding load current sample values ​​and external phase shift angle sample values; A cubic polynomial fitting is performed on the information to be fitted to obtain the target fitting relationship, where the independent variable in the target fitting relationship is the load current sample value, and the dependent variable in the target fitting relationship is the external shift phase angle sample value.

6. The dual active bridge series resonant converter control method according to claim 1, wherein: The acquisition of the load current reference value includes: Obtaining an actual input current value of the input port and a preset input current limit value; Performing a proportional-integral operation based on a difference between the actual input current value and the input current limit value to obtain a first current value; Acquire an actual output voltage value and an output voltage command value of the output port, wherein the output voltage command value refers to an output voltage value in a control command received by the dual active bridge series resonant converter; Performing a proportional-integral operation based on a difference between the actual output voltage value and the output voltage command value to obtain a second current value; Acquire a third current value, where the third current value refers to the output current value in the control instruction; A minimum value among the first current value, the second current value, and the third current value is determined as the load current reference value.

7. The dual active bridge series resonant converter control method according to any one of claims 1 to 6, characterized in that: According to the load current reference value, the internal phase shift angle and the switching period of the dual active bridge series resonant converter are adjusted to complete the dual active bridge series resonant converter control, including: Obtaining an actual value of the load current of the output port; Performing a proportional-integral operation based on a difference between the load current reference value and the load current actual value to obtain a first switching period; performing a proportional resonance operation according to the first switching period to obtain a second switching period; If the second switching period is within a preset switching period threshold range, the second switching period is determined as a target switching period, and the preset inner phase shift angle value is determined as a target inner phase shift angle; If the second switching period is less than a minimum value in the switching period threshold range and the second switching period is greater than 0, the minimum value in the switching period threshold range is determined as a target switching period, and a ratio between the second switching period and twice the target switching period is determined as a target inner phase shift angle; According to the target switching period and the target internal phase shift angle, the internal phase shift angle and the switching period of the dual active bridge series resonant converter are adjusted to complete the control of the dual active bridge series resonant converter.

8. A dual active bridge series resonant converter control system, characterized in that: The system is used to control a two-port circuit of a dual active bridge series resonant converter, wherein the two-port circuit includes an input port and an output port, and comprises: a target external phase shift angle acquisition module, configured to obtain, if it is determined that the dual active bridge series resonant converter enters a light load condition, a target external phase shift angle corresponding to the load current reference value based on a load current reference value and a preset target fitting relationship, wherein the load current reference value is a current value expected to be output by the output port, and in the target fitting relationship, the load current and the external phase shift angle are negatively correlated under the light load condition; A first adjustment module, configured to adjust the external phase shift angle of the dual active bridge series resonant converter based on the target external phase shift angle; The second adjustment module is used to adjust the internal phase shift angle and switching period of the dual active bridge series resonant converter according to the load current reference value to complete the control of the dual active bridge series resonant converter.

9. A dual active bridge series resonant converter, characterized in that: include: An active-side full bridge, a resonant circuit, a passive-side full bridge, and a dual-active-bridge series resonant converter control system according to claim 8, wherein the active-side full bridge includes the input port, and the passive-side full bridge includes the output port; The dual active bridge series resonant converter control system is used to control the switching devices in the active side full bridge and the passive side full bridge based on the adjustment signal of the outer phase shift angle, the adjustment signal of the inner phase shift angle, and the adjustment signal of the switching period.

10. A computer-readable storage medium, characterized in that A computer program is stored thereon, and the computer program is used to enable a computer to execute the dual active bridge series resonant converter control method according to any one of claims 1 to 7.

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