A compound control method and system for optimizing dynamic performance of a resonant converter

Abstract

The application provides a composite control method and system for optimizing dynamic performance of a resonant converter, and belongs to the technical field of power electronics. The method comprises the following steps: when a load mutation occurs, an open-loop control is adopted, a corresponding steady-state operating point is matched according to an input voltage and an output current of the resonant converter, and an output frequency of the open-loop control is obtained; an output voltage of the resonant converter is received in real time, and an output frequency of a closed-loop control is obtained based on a reference voltage of the resonant converter; and the output frequency of the open-loop control and the output frequency of the closed-loop control are added to obtain a switching frequency of the resonant converter. The application optimizes the dynamic response of the resonant converter under the working condition of a large-range load mutation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of power electronics, and more particularly relates to a composite control method and system for optimizing the dynamic performance of a resonant converter. BACKGROUND

[0002] With the rapid development of technologies such as cloud computing, big data, and artificial intelligence, the scale of data centers is expanding, and the number of servers is increasing rapidly, leading to an increasing demand for efficient and reliable server power supplies in the market. At the same time, enterprises' demand for data processing capabilities is also increasing, making higher requirements for the power density and stability of power supplies. Server power supplies are particularly important in the digital transformation wave.

[0003] In the field of server power supplies, resonant converters have many advantages, such as maintaining high efficiency over a wide load range, stable operation over a wide input voltage range, adapting to power supplies in different regions and conditions, and lower electromagnetic interference (EMI) and better electromagnetic compatibility. However, there are still many problems to be solved, one of which is the poor dynamic response of resonant converters under large-scale load mutations, which cannot meet the requirements of server power supplies for power quality stability. SUMMARY

[0004] To overcome the defects of the prior art, the present application provides a composite control method and system for optimizing the dynamic performance of a resonant converter, aiming to solve the problem of poor dynamic response of resonant converters under large-scale load mutations, which cannot meet the requirements of server power supplies for power quality stability.

[0005] To achieve the above-mentioned purpose, on the one hand, the present application provides a composite control method for optimizing the dynamic performance of a resonant converter, comprising the following steps:

[0006] When a load mutation occurs, open-loop control is adopted to match the corresponding steady-state operating point according to the current input voltage and output current of the resonant converter, and the output frequency of open-loop control is obtained;

[0007] The output voltage of the resonant converter is received in real time, and the output frequency of closed-loop control is obtained based on the reference voltage of the resonant converter;

[0008] The output frequency of open-loop control and the output frequency of closed-loop control are added to obtain the switching frequency of the resonant converter.

[0009] Further preferably, the open-loop control specifically comprises the following steps:

[0010] The gain of the resonant cavity is obtained by dividing the rated input voltage of the resonant converter by the input voltage of the resonant converter; the output current of the resonant converter is multiplied by the proportional coefficient to convert it into the corresponding quality factor;

[0011] When the gain and quality factor of the resonant cavity exceed a preset range, the corresponding frequency is looked up in the steady-state operating point table to obtain the output frequency of the open-loop control.

[0012] Further preferably, the method for obtaining the steady-state operating point table includes the following steps:

[0013] Based on the rated power of the resonant converter, the capacitance value of the resonant capacitor, the inductance value of the resonant inductor, the inductance value of the excitation inductor, and the resonant frequency, a curve of the gain of the resonant cavity versus the quality factor and the switching frequency of the resonant converter is obtained; wherein the X-axis represents the ratio between the switching frequency and the resonant frequency; and the Y-axis represents the gain of the resonant cavity;

[0014] A straight line parallel to the X-axis is drawn with the preset resonant cavity gain interval. The intersection of the line with the curve is the steady-state operating point for different loads at the input voltage represented by the current line. The different loads are represented by the output current of the resonant converter.

[0015] The gains of different resonant cavities, different quality factors, and the ratio between the switching frequency and the resonant frequency are recorded in a table to obtain a steady-state operating point table.

[0016] Further preferably, the method for obtaining the proportional coefficient is:

[0017] Calculate the load resistance of the resonant converter based on the output voltage and output current of the resonant converter;

[0018] Obtaining the primary side fundamental wave equivalent resistance based on the load resistance of the resonant converter and the turns ratio between the primary side and the secondary side of the resonant converter;

[0019] According to the type of resonant converter, combined with the primary side fundamental wave equivalent resistance, the relationship between the quality factor and the output current of the resonant converter is calculated to obtain the proportional coefficient.

[0020] Further preferably, when the resonant converter is an LLC resonant converter, the proportional coefficient is:

[0021]

[0022] Where k is the proportional coefficient; C r is the capacitance value of the resonant capacitor; L r is the inductance of the resonant inductor; N is the turns ratio between the primary and secondary sides of the resonant transformer; V o is the output voltage of the resonant converter.

[0023] Further preferably, the closed-loop control specifically includes the following steps:

[0024] Subtracting the output voltage of the resonant converter from the reference voltage of the resonant converter to obtain a voltage error signal;

[0025] The output frequency of closed-loop control is obtained by performing proportional-integral operation on the voltage error signal.

[0026] On the other hand, the present application provides a composite control system for optimizing the dynamic performance of a resonant converter, comprising: an open-loop control module, a closed-loop control module, and an addition module;

[0027] The open-loop control module is used to adopt open-loop control when a sudden load change occurs. It matches the corresponding steady-state operating point according to the current input voltage and output current of the resonant converter and obtains the output frequency of the open-loop control.

[0028] The closed-loop control module is used to receive the output voltage of the resonant converter in real time and obtain the output frequency of the closed-loop control based on the reference voltage of the resonant converter;

[0029] The adding module is used to add the output frequency of the open-loop control and the output frequency of the closed-loop control to obtain the switching frequency of the resonant converter.

[0030] Further preferably, the open-loop control module includes: a first multiplication unit, a second multiplication unit, and a steady-state operating point search unit; the output ends of the first multiplication unit and the second multiplication unit are connected to the search unit;

[0031] The first multiplication unit is used to obtain the gain of the resonant cavity by dividing the rated input voltage of the resonant converter by the input voltage of the resonant converter;

[0032] The second multiplication unit is used to convert the output current of the resonant converter into a corresponding quality factor by multiplying the proportional coefficient;

[0033] The steady-state operating point search unit is used to search for the corresponding frequency in the steady-state operating point table when the gain and quality factor of the resonant cavity exceed a preset range, and obtain the output frequency of the open-loop control.

[0034] Further preferably, the steady-state operating point search unit includes: a curve plotter, a steady-state operating point acquirer and a table generator;

[0035] The curve plotter is used to obtain a curve graph of the gain of the resonant cavity versus the quality factor and the switching frequency of the resonant converter based on the rated power of the resonant converter, the capacitance value of the resonant capacitor, the inductance value of the resonant inductor, the inductance value of the excitation inductor, and the resonant frequency; wherein the X-axis represents the ratio between the switching frequency and the resonant frequency; and the Y-axis represents the gain of the resonant cavity;

[0036] The steady-state operating point acquirer is used to draw a straight line parallel to the X-axis at a preset resonant cavity gain interval. The intersection of the straight line and the curve is the steady-state operating point at different loads under the input voltage represented by the current straight line. The different loads are represented by the output current of the resonant converter.

[0037] The table generator is used to record the gains of different resonant cavities, different quality factors, and the ratio between the switching frequency and the resonant frequency in a table to obtain a steady-state operating point table.

[0038] Further preferably, the open-loop control module also includes: a proportional coefficient acquisition unit, which is used to calculate the load resistance of the resonant converter based on the output voltage and output current of the resonant converter; obtain the primary side fundamental wave equivalent resistance based on the load resistance of the resonant converter and the turns ratio between the primary and secondary sides of the resonant converter; according to the type of the resonant converter, combined with the primary side fundamental wave equivalent resistance, calculate the relationship between the quality factor and the output current of the resonant converter to obtain the proportional coefficient.

[0039] Further preferably, when the resonant converter is an LLC resonant converter, the proportional coefficient in the proportional coefficient acquisition unit is:

[0040]

[0041] Where k is the proportional coefficient; C r is the capacitance value of the resonant capacitor; L r is the inductance of the resonant inductor; N is the turns ratio between the primary and secondary sides of the resonant transformer; V o is the output voltage of the resonant converter.

[0042] Further preferably, the closed-loop control module includes an adder and a voltage controller;

[0043] The adder is used to obtain a voltage error signal by subtracting the output voltage of the resonant converter from the reference voltage of the resonant converter;

[0044] The voltage controller is used to perform proportional-integral operation on the voltage error signal to obtain the output frequency of the closed-loop control.

[0045] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the existing technologies:

[0046] The present application provides a composite control method for optimizing the dynamic performance of a resonant converter. On the basis of the traditional control method, only an open-loop control part is added. When a sudden load change occurs, open-loop control is adopted. According to the input voltage and output current of the current resonant converter, the corresponding steady-state operating point is matched to obtain the output frequency of the open-loop control. There is no complex calculation and no additional computing power pressure is brought to the MCU (microcontroller).

[0047] The present application provides a composite control method for optimizing the dynamic performance of a resonant converter. The two sampling input voltages V in And the output current I o It is usually required for control and protection of the original circuit, and is easy to implement and deploy without adding any additional circuits or sampling circuits.

[0048] The present application provides a composite control method for optimizing the dynamic performance of a resonant converter, which has a significant dynamic performance optimization effect. Since the open-loop control part can make the frequency jump over a large range within a control cycle during the dynamic process, compared with the traditional control method that relies on the continuous and slow adjustment of the PI controller, its dynamic performance is significantly optimized. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a control block diagram of a composite control method for optimizing the dynamic performance of a resonant converter provided in an embodiment of the present application;

[0050] Figure 2 is a topology diagram of a resonant converter provided in an embodiment of the present application;

[0051] Figure 3 The resonant cavity gain G provided by the embodiment of the present application varies with and the cluster of curves of Q variation;

[0052] Figure 4(a) is a diagram of the embodiment of the present application. Figure 3 The first region is enlarged, showing the diagram of the steady-state operating point selection under some input voltages;

[0053] Figure 4(b) is a diagram of the embodiment of the present application. Figure 3 The second area in the figure is enlarged to show the diagram of the steady-state operating point selection under some input voltages;

[0054] Figure 5 is a steady-state operating point table provided in the embodiment of the present application;

[0055] Figure 6 This is the no-load to full-load dynamic response provided by the embodiment of the present application without using compound control;

[0056] Figure 7 This is the no-load to full-load dynamic response using compound control provided in an embodiment of the present application. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0058] The term "and / or" as used herein describes an association between related objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. The symbol " / " as used herein indicates that the related objects are in an "or" relationship, for example, A / B means either A or B.

[0059] The terms "first" and "second" and the like in the description and claims herein are used to distinguish different objects rather than to describe a specific order of the objects.

[0060] In the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0061] In the description of the embodiments of the present application, unless otherwise specified, “plurality” means two or more.

[0062] The technical solutions provided in the embodiments of this application are introduced.

[0063] The present application provides a composite control method for optimizing the dynamic performance of a resonant converter. The composite control method includes an open-loop control part and a closed-loop control part. Whether it is the composite control method or the open-loop control part and the closed-loop control part contained therein, the control quantity is the switching frequency f s The output of the compound controller is the sum of the output of the open-loop control part and the closed-loop control part.

[0064] Example 1

[0065] like Figure 1 As shown, the embodiment of the present application provides a composite control method for optimizing the dynamic performance of a resonant converter. The circuit state parameter required to be sampled by the composite control method is the input voltage V in , output voltage V o And the output current I o , the output is the switching frequency f of the resonant converter s , the specific resonant converter topology is as follows Figure 2 As shown;

[0066] The output frequency f of the open-loop control so It is a constant value when there is no large-scale load mutation; when a large-scale load mutation occurs, its output frequency changes according to the current circuit state (input voltage V in And the output current Io ), matching the corresponding steady-state operating point, so that the output frequency jumps to the corresponding output frequency f of the next state so ;

[0067] The feedback quantity of closed-loop control is the output voltage V o , its output frequency f sc It changes slightly in each control cycle to stabilize the output voltage in steady state;

[0068] The output of the composite control method is the switching frequency f of the resonant converter. s , whose value is the output frequency f of the open-loop control so The output frequency f of the closed-loop control sc Addition;

[0069] A composite control method for optimizing the dynamic performance of a resonant converter, wherein a method for selecting a steady-state operating point comprises the following steps:

[0070] (1) Setting the circuit parameters of the resonant converter;

[0071] (2) Using the obtained circuit parameters to calculate, simulate or test the actual machine to obtain the gain G of the resonant cavity with the quality factor Q and the switching frequency f s The X-axis represents the switching frequency f s and the resonant frequency f n The Y axis represents the gain G of the resonant cavity; the resonant converter includes a resonant cavity;

[0072] (3) Draw a straight line parallel to the X-axis (representing the same input voltage) with an appropriate resonant cavity gain interval. The intersection of the straight line and the curve is the steady-state operating point at different loads under the input voltage represented by the current straight line; among them, the output current I o representation;

[0073] To more clearly illustrate the process of selecting the steady-state operating point, a design example and diagrams are provided below. This example is a 3200W 12V LLC resonant converter design. The specific design parameters are shown in the following table.

[0074]

[0075] Where P is the rated output power of the resonant converter; C r is the capacitance value of the resonant capacitor; L r is the inductance value of the resonant inductor; L m is the inductance of the excitation inductor; N is the turns ratio of the primary and secondary sides of the transformer; f n C r and L rThe series resonant frequency of

[0076] The LLC circuit parameters are used to simulate the LLC resonant converter. LLC refers to a resonant cavity composed of two inductors (L) and a capacitor (C). The gain G of the resonant cavity varies with the quality factor Q and the switching frequency f. s The changing curve, such as Figure 3 As shown, due to the difference between Q and I o is proportional, so Figure 3 Directly use Q with I o Instead, it is more intuitive to convert the load size into output current I o size.

[0077] Draw straight lines parallel to the X-axis (representing the same input voltage) at appropriate intervals. The intersection of the straight line and the curve is the steady-state operating point at different loads under the input voltage represented by the current straight line. The corresponding horizontal axis is the normalized switching frequency at the current steady-state operating point. Further multiply by the resonant frequency f n The switching frequency at the current steady-state operating point can be obtained. The specific selection of the steady-state operating point is shown in Figure 4(a) and Figure 4(b). It should be noted that Figure 4(a) and Figure 4(b) only show the straight lines represented by part of the input voltage to illustrate the method of selecting the steady-state operating point.

[0078] (4) Finally, the obtained data is organized into a table, and the table is looked up in each control cycle to determine the output frequency of the open-loop controller. The steady-state operating point table obtained according to the above embodiment is as follows: Figure 5 As shown; the table records the gain of different resonant cavities, different quality factors (characterizing the load) and switching frequency f s and the resonant frequency f n The ratio between.

[0079] Further preferably, after determining the appropriate steady-state operating point, the open-loop control specifically includes the following steps:

[0080] (1) Collect the input voltage V of the resonant converter in and the output current I of the resonant converter o ;

[0081] (2) Using the rated input voltage V of the resonant converter N Divide by the collected current input voltage V in , get the gain G of the current resonant cavity;

[0082] (3) Using output current I o Multiply by the proportional coefficient to convert to the corresponding quality factor Q. The conversion method is given in formulas (5) and (6). In this example, k = 0.00138 can be calculated;

[0083] More specifically, I o The conversion between I and Q is a simple proportional relationship. Taking the LLC resonant converter as an example, the conversion between I o The relationship between Q is deduced as follows:

[0084] According to the definition of quality factor Q:

[0085]

[0086] Among them, R ac is the primary side fundamental wave equivalent resistance;

[0087] The primary side fundamental wave equivalent resistance R ac With the load resistor R L There are the following relationships:

[0088]

[0089] Where N is the transformer primary to secondary turns ratio;

[0090] And because the load resistance R L With the output voltage V o and output current I o There are the following relationships:

[0091]

[0092] Combining formulas (1) to (3), we can obtain:

[0093]

[0094] Output voltage V o In this control mode, it can be regarded as a fixed value, and the other parameters are constants that have been determined in the parameter design stage. Therefore, taking the LLC resonant converter as an example, the output current I o The relationship with the quality factor Q can be expressed as:

[0095] Q=k·I o (5)

[0096] The expression of the constant k is:

[0097]

[0098] It should be understood that some of the above formulas for calculating the k value may vary slightly in different resonant converters, but the calculation ideas and the rule that k is a constant are applicable to resonant converters with any frequency control;

[0099] (4) If the change of G and Q does not exceed the specified range, the output of the open-loop controller remains unchanged; if the value of G and Q changes beyond the specified range, the value of G and Q is approximated, and the corresponding frequency in the steady-state operating point table is found using the corresponding G and Q, which is the output frequency f of the open-loop controller. so .

[0100] It is worth noting that since G and Q in the steady-state operating point table are limited to a few discrete values, not all calculated G and Q can find corresponding operating points in the table, so it is necessary to approximate the calculated G and Q to correspond to the points in the table. There are many methods to choose from for data approximation. It should be noted that the purpose of data approximation is to find the corresponding values ​​of all calculated G and Q in the table, and then determine the output frequency. Therefore, the method and logic of data approximation will not be elaborated in detail here. It should be pointed out here that the number of steady-state operating points selected, that is, the number of elements in the steady-state operating point table, is related to the number of different quality factors Q selected and the number of different input voltages V in If m steady-state operating points with different quality factors under n different input voltages are selected, the number of elements in the steady-state operating point table is m*n.

[0101] Closed-loop control is as follows Figure 1 The closed-loop controller shown in the figure includes the following steps:

[0102] S1: Collect output voltage V o ;

[0103] S2: Output voltage V o With reference voltage V ref The voltage error signal V e ;

[0104] S3: Perform proportional integral (PI) operation on the error signal to obtain the closed-loop controller output frequency f sc Finally, the output frequency of the open-loop controller is added to the output frequency of the closed-loop controller to obtain the output frequency of the composite controller, which is the switching frequency f of the resonant converter. s .

[0105] In summary, taking a 3200W 12V LLC resonant converter as an example, the composite control method for optimizing the dynamic performance of the LLC resonant converter is explained in detail, and the implementation steps of the control method proposed in this application are explained. The optimization effect of the composite control provided in this application on the dynamic performance of the LLC resonant converter is as follows: Figure 6 and Figure 7 , the composite control method will input voltage V in =450V, the voltage drop when switching from no-load to full-load is reduced from 3.9V to 0.5V, which effectively optimizes the dynamic performance of the LLC resonant converter.

[0106] Example 2

[0107] The present application provides a composite control system for optimizing the dynamic performance of a resonant converter, comprising: an open-loop control module, a closed-loop control module, and an addition module;

[0108] The open-loop control module is used to adopt open-loop control when a sudden load change occurs. It matches the corresponding steady-state operating point according to the current input voltage and output current of the resonant converter and obtains the output frequency of the open-loop control.

[0109] The closed-loop control module is used to receive the output voltage of the resonant converter in real time and obtain the output frequency of the closed-loop control based on the reference voltage of the resonant converter;

[0110] The adding module is used to add the output frequency of the open-loop control and the output frequency of the closed-loop control to obtain the switching frequency of the resonant converter.

[0111] Further preferably, the open-loop control module includes: a first multiplication unit, a second multiplication unit, and a steady-state operating point search unit; the output ends of the first multiplication unit and the second multiplication unit are connected to the search unit;

[0112] The first multiplication unit is used to obtain the gain of the resonant cavity by dividing the rated input voltage of the resonant converter by the input voltage of the resonant converter;

[0113] The second multiplication unit is used to convert the output current of the resonant converter into a corresponding quality factor by multiplying the proportional coefficient;

[0114] The steady-state operating point search unit is used to search for the corresponding frequency in the steady-state operating point table when the gain and quality factor of the resonant cavity exceed a preset range, and obtain the output frequency of the open-loop control.

[0115] Further preferably, the steady-state operating point search unit includes: a curve plotter, a steady-state operating point acquirer and a table generator;

[0116] The curve plotter is used to obtain a curve graph of the gain of the resonant cavity versus the quality factor and the switching frequency of the resonant converter based on the rated power of the resonant converter, the capacitance value of the resonant capacitor, the inductance value of the resonant inductor, the inductance value of the excitation inductor, and the resonant frequency; wherein the X-axis represents the ratio between the switching frequency and the resonant frequency; and the Y-axis represents the gain of the resonant cavity;

[0117] The steady-state operating point acquirer is used to draw a straight line parallel to the X-axis at a preset resonant cavity gain interval. The intersection of the straight line and the curve is the steady-state operating point at different loads under the input voltage represented by the current straight line. The different loads are represented by the output current of the resonant converter.

[0118] The table generator is used to record the gains of different resonant cavities, different quality factors, and the ratio between the switching frequency and the resonant frequency in a table to obtain a steady-state operating point table.

[0119] Further preferably, the open-loop control module also includes: a proportional coefficient acquisition unit, which is used to calculate the load resistance of the resonant converter based on the output voltage and output current of the resonant converter; obtain the primary side fundamental wave equivalent resistance based on the load resistance of the resonant converter and the turns ratio between the primary and secondary sides of the resonant converter; according to the type of the resonant converter, combined with the primary side fundamental wave equivalent resistance, calculate the relationship between the quality factor and the output current of the resonant converter to obtain the proportional coefficient.

[0120] Further preferably, when the resonant converter is an LLC resonant converter, the proportional coefficient in the proportional coefficient acquisition unit is:

[0121]

[0122] Where k is the proportional coefficient; C r is the capacitance value of the resonant capacitor; L r is the inductance of the resonant inductor; N is the turns ratio between the primary and secondary sides of the resonant transformer; V o is the output voltage of the resonant converter.

[0123] Further preferably, the closed-loop control module includes an adder and a voltage controller;

[0124] The adder is used to obtain a voltage error signal by subtracting the output voltage of the resonant converter from the reference voltage of the resonant converter;

[0125] The voltage controller is used to perform proportional-integral operation on the voltage error signal to obtain the output frequency of the closed-loop control.

[0126] In summary, this application has the following advantages:

[0127] The present application provides a composite control method for optimizing the dynamic performance of a resonant converter. On the basis of the traditional control method, only an open-loop control part is added. When a sudden load change occurs, open-loop control is adopted. According to the input voltage and output current of the current resonant converter, the corresponding steady-state operating point is matched to obtain the output frequency of the open-loop control. There is no complex calculation and no additional computing power pressure is brought to the MCU.

[0128] The present application provides a composite control method for optimizing the dynamic performance of a resonant converter. The two sampling input voltages V in And the output current I o It is usually required for control and protection of the original circuit, and is easy to implement and deploy without adding any additional circuits or sampling circuits.

[0129] The present application provides a composite control method for optimizing the dynamic performance of a resonant converter, which has a significant dynamic performance optimization effect. Since the open-loop control part can make the frequency jump over a large range within a control cycle during the dynamic process, compared with the traditional control method that relies on the continuous and slow adjustment of the PI controller, its dynamic performance is significantly optimized.

[0130] It should be understood that the above-mentioned system is used to execute the method in the above-mentioned embodiment. The implementation principle and technical effect of the corresponding program module in the system are similar to those described in the above-mentioned method. The working process of the system can refer to the corresponding process in the above-mentioned method and will not be repeated here.

[0131] It will be understood that the various numerical numbers involved in the embodiments of the present application are merely distinctions for the convenience of description and are not intended to limit the scope of the embodiments of the present application.

[0132] It is easy for those skilled in the art to understand that the above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A composite control method for optimizing the dynamic performance of a resonant converter, characterized in that: The following steps are involved: When a sudden load change occurs, open-loop control is used to match the corresponding steady-state operating point according to the current input voltage and output current of the resonant converter to obtain the output frequency of the open-loop control; receiving the output voltage of the resonant converter in real time, and obtaining the output frequency of the closed-loop control based on the reference voltage of the resonant converter; The output frequency of the open-loop control is added to the output frequency of the closed-loop control to obtain the switching frequency of the resonant converter; Open-loop control specifically includes the following steps: The gain of the resonant cavity is obtained by dividing the rated input voltage of the resonant converter by the input voltage of the resonant converter. Multiply the output current of the resonant converter by the proportional coefficient to convert it into the corresponding quality factor; When the gain and quality factor of the resonant cavity exceed the preset range, the corresponding frequency is found in the steady-state operating point table to obtain the output frequency of the open-loop control; The method for obtaining the steady-state operating point table includes the following steps: Based on the rated power of the resonant converter, the capacitance value of the resonant capacitor, the inductance value of the resonant inductor, the inductance value of the excitation inductor, and the resonant frequency, a curve of the gain of the resonant cavity versus the quality factor and the switching frequency of the resonant converter is obtained; wherein the X-axis represents the ratio between the switching frequency and the resonant frequency; and the Y-axis represents the gain of the resonant cavity; Draw a straight line parallel to the X-axis with respect to the gain interval of the preset resonant cavity. The intersection of the straight line with the curve is the steady-state operating point at different loads under the input voltage represented by the current straight line. The different loads are represented by the output current of the resonant converter. The gains of different resonant cavities, different quality factors, and the ratio between the switching frequency and the resonant frequency are recorded in a table to obtain a steady-state operating point table.

2. The composite control method for optimizing the dynamic performance of a resonant converter according to claim 1, characterized in that: The method to obtain the proportional coefficient is: Calculate the load resistance of the resonant converter based on the output voltage and output current of the resonant converter; Obtaining the primary side fundamental wave equivalent resistance based on the load resistance of the resonant converter and the turns ratio between the primary side and the secondary side of the resonant converter; According to the type of resonant converter, combined with the primary side fundamental wave equivalent resistance, the relationship between the quality factor and the output current of the resonant converter is calculated to obtain the proportional coefficient.

3. The composite control method for optimizing the dynamic performance of a resonant converter according to claim 2, characterized in that: When the resonant converter is an LLC resonant converter, the proportional coefficient is: in, is the proportionality coefficient; C r is the capacitance value of the resonant capacitor; L r is the inductance value of the resonant inductor; N is the turns ratio between the primary and secondary sides of the resonant transformer; V o is the output voltage of the resonant converter.

4. The composite control method for optimizing the dynamic performance of a resonant converter according to claim 1, wherein: Closed-loop control specifically includes the following steps: Subtracting the output voltage of the resonant converter from the reference voltage of the resonant converter to obtain a voltage error signal; The output frequency of closed-loop control is obtained by performing proportional-integral operation on the voltage error signal.

5. A composite control system for optimizing the dynamic performance of a resonant converter based on the composite control method for optimizing the dynamic performance of a resonant converter according to any one of claims 1 to 4, characterized in that: include: Open-loop control module, closed-loop control module and addition module; The open-loop control module is used to adopt open-loop control when a sudden load change occurs. It matches the corresponding steady-state operating point according to the current input voltage and output current of the resonant converter and obtains the output frequency of the open-loop control. The closed-loop control module is used to receive the output voltage of the resonant converter in real time and obtain the output frequency of the closed-loop control based on the reference voltage of the resonant converter; The adding module is used to add the output frequency of the open-loop control and the output frequency of the closed-loop control to obtain the switching frequency of the resonant converter.

6. The composite control system for optimizing the dynamic performance of a resonant converter according to claim 5, characterized in that: The open-loop control module includes: a first multiplication unit, a second multiplication unit, and a steady-state operating point search unit; the output ends of the first multiplication unit and the second multiplication unit are connected to the search unit; The first multiplication unit is used to obtain the gain of the resonant cavity by dividing the rated input voltage of the resonant converter by the input voltage of the resonant converter; The second multiplication unit is used to convert the output current of the resonant converter into a corresponding quality factor by multiplying the proportional coefficient; The steady-state operating point search unit is used to search for the corresponding frequency in the steady-state operating point table when the gain and quality factor of the resonant cavity exceed a preset range, and obtain the output frequency of the open-loop control.

7. The composite control system for optimizing the dynamic performance of a resonant converter according to claim 6, characterized in that: The steady-state operating point search unit includes: a curve plotter, a steady-state operating point acquirer and a table generator; The curve plotter is used to obtain a curve graph of the gain of the resonant cavity versus the quality factor and the switching frequency of the resonant converter based on the rated power of the resonant converter, the capacitance value of the resonant capacitor, the inductance value of the resonant inductor, the inductance value of the excitation inductor, and the resonant frequency; wherein the X-axis represents the ratio between the switching frequency and the resonant frequency; and the Y-axis represents the gain of the resonant cavity; The steady-state operating point acquirer is used to draw a straight line parallel to the X-axis at a preset resonant cavity gain interval. The intersection of the straight line and the curve is the steady-state operating point at different loads under the input voltage represented by the current straight line. The different loads are represented by the output current of the resonant converter. The table generator is used to record the gains of different resonant cavities, different quality factors, and the ratio between the switching frequency and the resonant frequency in a table to obtain a steady-state operating point table.

8. The composite control system for optimizing the dynamic performance of a resonant converter according to claim 5, characterized in that: The closed-loop control module includes an adder and a voltage controller; The adder is used to obtain a voltage error signal by subtracting the output voltage of the resonant converter from the reference voltage of the resonant converter; The voltage controller is used to perform proportional-integral operation on the voltage error signal to obtain the output frequency of the closed-loop control.

Images