Adaptive frequency optimization control system and method based on DC-DC converter

Abstract

The invention provides an adaptive frequency optimization control system and method based on a DC-DC converter, and relates to the technical field of power electronics, and the system comprises a first obtaining module which is connected with the positive output end of an input power supply, and is used for obtaining an input current signal of the converter; the second acquisition module is connected with the positive input end of the output load and is used for acquiring an output voltage value and an output current value of the converter; the first control module is connected with the output end of the first acquisition module and is used for determining a frequency value of the converter when the power loss is minimum according to the input current signal; and the second control module is connected with the output end of the second acquisition module and is used for calculating the duty ratio corresponding to the frequency value according to the output voltage value and the output current value, so that the output power of the converter is kept unchanged when the frequency of the converter changes. According to the invention, the power loss of the DC-DC converter can be reduced, so that the DC-DC converter can operate at the maximum efficiency in different working states.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to an adaptive frequency optimization control system and method based on a DC-DC converter. Background Art

[0002] The optimal design of a DC-DC converter requires the optimization of multiple parameters to achieve the goal of improving efficiency and performance. Some of these parameters are load-related, line-related, component-related, and temperature-related. Designing these parameters for specific loads, inputs and outputs, components, and temperatures may improve the efficiency of a single design point, but it will not produce maximum efficiency under different conditions, and improvements at that design point cannot be guaranteed due to changes in components, temperature, and operating points.

[0003] In the prior art, the maximum efficiency tracking control system of the power converter adopts a fixed-step tracking strategy, which has the problem of insufficient tracking speed and easy misjudgment. Therefore, how to improve the accuracy of tracking precision is a technical problem that needs to be solved. Summary of the invention

[0004] In response to the problems in the prior art, the present application provides an adaptive frequency optimization control system based on a DC-DC converter, which can reduce the power loss of the DC-DC converter and enable it to operate at maximum efficiency under different working conditions.

[0005] In order to solve the above technical problems, this application provides the following technical solutions:

[0006] In a first aspect, the present application provides an adaptive frequency optimization control system based on a DC-DC converter, comprising:

[0007] A first acquisition module is connected to the positive output terminal of the input power supply and is used to acquire an input current signal of the converter;

[0008] A second acquisition module is connected to the positive input terminal of the output load and is used to acquire the output voltage value and the output current value of the converter;

[0009] A first control module, connected to the output end of the first acquisition module, for determining a frequency value of the converter when power loss is minimum according to the input current signal;

[0010] The second control module is connected to the output end of the second acquisition module, and is used to calculate the duty cycle corresponding to the frequency value according to the output voltage value and the output current value, so that the output power of the converter remains unchanged when the frequency of the converter changes.

[0011] Furthermore, the first acquisition module includes a current sampling circuit.

[0012] Furthermore, the second acquisition module includes a current sampling circuit and a voltage sampling circuit.

[0013] Furthermore, the second acquisition module is specifically used to calculate the output power value of the converter according to the output voltage value and the output current value.

[0014] Furthermore, the first control module is specifically used to calculate a first difference between a current value of the input current signal and a previous value of the input current signal, and a second difference between a current frequency and a previous frequency; and to update the operating frequency of the converter according to the first difference and the second difference.

[0015] Further, the first control module is specifically used to calculate the step length according to the current state of the converter;

[0016] Wherein, if the current state is the first state, the operating frequency of the converter is reduced according to the step size to move toward the maximum efficiency point; wherein the first state is that the first difference and the second difference have the same sign;

[0017] If the current state is the second state, the operating frequency of the converter is increased according to the step size to move toward the maximum efficiency point; wherein the first state is that the signs of the first difference and the second difference are different.

[0018] Furthermore, the calculation formula of the step length is: Among them, ξ and μ are parameters that control the convergence speed and accuracy, respectively.

[0019] Furthermore, the second control module is specifically used to compare the output power difference between the output power value of the converter and the preset power value; perform PI control on the output power difference and then input it into the PWM wave generator to correct the duty cycle.

[0020] Further, when the output power difference is greater than zero, the output power value of the converter is greater than the preset power value, and the duty cycle decreases;

[0021] When the output power difference is less than zero, the output power value of the converter is less than the preset power value, and the duty cycle increases;

[0022] When the output power difference is equal to zero, the output power value of the converter is equal to the preset power value, and the duty cycle remains unchanged.

[0023] In a second aspect, the present application provides an adaptive frequency optimization control method based on a DC-DC converter, which is applied to the adaptive frequency optimization control system based on a DC-DC converter, comprising:

[0024] The first acquisition module acquires an input current signal of the converter, and feeds back a current value of the input current signal to the first control module;

[0025] The first control module calculates a first difference between a current value of the input current signal and a previous value of the input current signal, and a second difference between a current frequency and a previous frequency; and updates the operating frequency of the converter according to the first difference and the second difference;

[0026] A second acquisition module acquires an output current value and an output voltage value of the converter, and feeds the output current value and the output voltage value back to a second control module;

[0027] The second control module calculates the output power value according to the output current value and the output voltage value; compares the output power difference between the output power value of the converter and the preset power value; and updates the duty cycle of the converter in the current working state according to the output power difference to ensure that the output power of the converter remains unchanged.

[0028] In response to the problems in the prior art, the adaptive frequency optimization control system and method based on DC-DC converter provided by the present application can be applied to the field of adaptive control of power electronics. It can use the maximum efficiency point tracking adaptive controller to optimize the switching frequency of the DC-DC converter, and at the same time track the minimum input power point of the converter under variable working conditions, so as to find the optimal switching frequency with the minimum total loss and the highest efficiency, thereby solving the problems of insufficient tracking speed and easy misjudgment under the fixed step tracking strategy. Specifically, it obtains the precise value of the step size through an adaptive algorithm, and corrects the operating frequency of the power converter according to the trend of the input current. The method is easy to implement and the step size is accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 A schematic diagram of an adaptive frequency optimization control system based on a DC-DC converter provided by the present invention;

[0031] Figure 2 A schematic flow chart of an adaptive frequency optimization control method based on a DC-DC converter provided by the present invention;

[0032] Figure 3 Schematic diagram of efficiency-fsw and input current-fsw curves. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0034] It should be noted that the adaptive frequency optimization control method and device based on DC-DC converter provided in the present application can be used in the financial field, and can also be used in any field other than the financial field. The application field of the adaptive frequency optimization control method and device based on DC-DC converter provided in the present application is not limited.

[0035] The acquisition, storage, use and processing of data in the technical solution of this application comply with the relevant provisions of laws and regulations.

[0036] In one embodiment, see Figure 1 In order to reduce the power loss of a DC-DC converter and enable it to operate at maximum efficiency under different working conditions, the present application provides an adaptive frequency optimization control system based on a DC-DC converter, comprising:

[0037] A first acquisition module is connected to the positive output terminal of the input power supply and is used to acquire an input current signal of the converter;

[0038] A second acquisition module is connected to the positive input terminal of the output load and is used to acquire the output voltage value and the output current value of the converter;

[0039] A first control module, connected to the output end of the first acquisition module, for determining a frequency value of the converter when power loss is minimum according to the input current signal;

[0040] The second control module is connected to the output end of the second acquisition module, and is used to calculate the duty cycle corresponding to the frequency value according to the output voltage value and the output current value, so that the output power of the converter remains unchanged when the frequency of the converter changes.

[0041] In one embodiment, the first acquisition module includes a current sampling circuit.

[0042] In one embodiment, the second acquisition module includes a current sampling circuit and a voltage sampling circuit.

[0043] In one embodiment, the second acquisition module is specifically configured to calculate the output power value of the converter according to the output voltage value and the output current value.

[0044] It can be understood that the first acquisition module includes a current sampling circuit, which is electrically connected to the positive output terminal of the input power supply to obtain the input current signal and characterize the input power; the second acquisition module includes a current sampling circuit and a voltage sampling circuit, which are electrically connected to the positive input terminal of the output load to obtain the output voltage value and the output current value of the converter module and calculate the output power; the first control module is electrically connected to the output terminal of the first acquisition module to determine the increase or decrease of the frequency value according to the changing trend of the input current, and determine the step size of the frequency change according to the magnitude of the change of the input current with the frequency, so as to find the frequency value when the power loss of the converter is minimized; the second control module is electrically connected to the output terminal of the second acquisition module to calculate the duty cycle at the frequency according to the output voltage value and the output current value, so as to ensure that the output power of the converter remains unchanged when the frequency changes.

[0045] In one embodiment, the first control module is specifically used to calculate a first difference between a current value of the input current signal and a previous value of the input current signal, and a second difference between a current frequency and a previous frequency; and to update the operating frequency of the converter according to the first difference and the second difference.

[0046] In one embodiment, see Figure 3 , the first control module is specifically used to calculate the step length according to the current state of the converter;

[0047] Wherein, if the current state is the first state, the operating frequency of the converter is reduced according to the step size to move toward the maximum efficiency point; wherein the first state is that the first difference and the second difference have the same sign;

[0048] If the current state is the second state, the operating frequency of the converter is increased according to the step size to move toward the maximum efficiency point; wherein the first state is that the signs of the first difference and the second difference are different.

[0049] In one embodiment, the step length is calculated as follows: Among them, ξ and μ are parameters that control the convergence speed and accuracy, respectively.

[0050] It can be understood that in the embodiment of the present application, the process of determining the increase or decrease of the frequency according to the change trend of the input current is as follows:

[0051] The first control module can determine the increase or decrease of the frequency value according to the change trend of the input current, compare the sign of the frequency change with the sign of the input current change, and decide to increase or decrease the switching frequency. Among them, the first difference and the second difference need to be compared in sign.

[0052] In some embodiments of the present application, the process of correcting the step value according to the change in input current is as follows:

[0053] The first control module can determine the step size of the frequency change according to the magnitude of the input current change, and find the frequency value when the power loss of the converter is minimized.

[0054] Specifically, the first acquisition module acquires the input current of the power converter, and the first control module calculates the difference between the current value and the previous value of the input current (also called the first difference) and the difference between the current frequency and the previous frequency (also called the second difference); the first control module compares the first difference with the preset current error accuracy Ie, and updates fsw if the conditions are met, and the program proceeds to the next step; the first control module calculates the step size according to the current state.

[0055] The so-called satisfying condition means that the first difference is greater than a preset current error accuracy Ie.

[0056] The so-called current state refers to the first difference (△Iin) and the second difference (△fsw) obtained after the conditions are met.

[0057] The first difference is compared with the current error precision Ie, and the subsequent procedures are performed only when the condition that the first difference is greater than the preset current error precision Ie is met.

[0058] The difference between the current value and the previous value of the input current and the difference between the current frequency and the previous frequency have the same sign, and fsw decreases by fsw_step to move toward the maximum efficiency point;

[0059] The difference between the current value and the previous value of the input current and the difference between the current frequency and the previous frequency have different signs, and fsw increases by fsw_step to move toward the maximum efficiency point;

[0060] The calculation formula of step length is:

[0061]

[0062] Among them, ξ and μ are parameters that control the convergence speed and accuracy. “·” indicates a multiplication operation. △Iin refers to the difference between the currents, i.e., the first difference; △fsw refers to the difference between the frequencies, i.e., the second difference.

[0063] In one embodiment, the second control module is specifically used to compare the output power difference between the output power value of the converter and the preset power value; perform PI control on the output power difference and then input it into the PWM wave generator to correct the duty cycle.

[0064] In one embodiment, when the output power difference is greater than zero, the output power value of the converter is greater than the preset power value, and the duty cycle is reduced;

[0065] When the output power difference is less than zero, the output power value of the converter is less than the preset power value, and the duty cycle increases;

[0066] When the output power difference is equal to zero, the output power value of the converter is equal to the preset power value, and the duty cycle remains unchanged.

[0067] It can be understood that, in some embodiments of the present application, the specific implementation process of ensuring that the output power remains unchanged when the operating frequency changes is as follows:

[0068] The second control module can calculate the duty cycle at the frequency based on the output voltage value and the output current value to ensure that the output power remains unchanged when the frequency changes. The output power value (also called the preset power value) is preset and compared with the output power value calculated by the second acquisition module based on the output voltage value and the output current value to obtain the current output power difference dP. The output power difference (also called the power error value) dP is input into the PI controller for control, and then input into the PWM wave (pulse width modulation wave) generator to correct the duty cycle D.

[0069] When the power error value dP>0, the current output power value is greater than the set output power value, and the duty cycle D is corrected, and D should be reduced;

[0070] When the power error value dP is less than 0, the current output power value is less than the set output power value, and the duty cycle D is corrected, and D should be increased;

[0071] When the power error value dP=0, the current output power value is equal to the set output power value, and the duty cycle D remains unchanged.

[0072] Among them, the parameters of the PI controller are set according to the actual circuit.

[0073] In one embodiment, see Figure 2 The present application provides an adaptive frequency optimization control method based on a DC-DC converter, which is applied to the adaptive frequency optimization control system based on a DC-DC converter, comprising:

[0074] The first acquisition module acquires an input current signal of the converter, and feeds back a current value of the input current signal to the first control module;

[0075] The first control module calculates a first difference between a current value of the input current signal and a previous value of the input current signal, and a second difference between a current frequency and a previous frequency; and updates the operating frequency of the converter according to the first difference and the second difference;

[0076] A second acquisition module acquires an output current value and an output voltage value of the converter, and feeds the output current value and the output voltage value back to a second control module;

[0077] The second control module calculates the output power value according to the output current value and the output voltage value; compares the output power difference between the output power value of the converter and the preset power value; and updates the duty cycle of the converter in the current working state according to the output power difference to ensure that the output power of the converter remains unchanged.

[0078] Understandably, see Figure 2 The adaptive frequency optimization control method based on DC-DC converter provided in the present application can be performed according to the following steps:

[0079] Step S201: The first acquisition module acquires the input current signal of the power converter through the current sampling circuit, and feeds back the current input current value corresponding to the input current signal (also called the current value of the input current signal or the current value of the input current) to the first control module; the first control module calculates the difference between the current value and the previous value of the input current (also called the first difference), and the difference between the current frequency and the previous frequency (also called the second difference); wherein the previous value of the frequency refers to: the previous operating frequency value; the previous value of the current refers to: the input current value sampled at the previous operating frequency.

[0080] Step S202: The first control module compares the difference between the current value and the previous value of the input current with the selected current error accuracy Ie (calculated and selected according to the power specification of the applicable topology); when the difference between the current value and the previous value of the input current is greater than the current error accuracy, fsw (the operating frequency of the converter) can be updated and the next step can be performed; otherwise, the loop is jumped out to maintain the current stable working state;

[0081] Step S203: the first control module updates the step size to be increased or decreased according to the gradient of the current input current (the difference between the current value and the previous value of the input current obtained in step S201, and the ratio of the difference between the current frequency and the previous frequency) and the product of the selected ξ and μ; the specific calculation method is as mentioned above;

[0082] Step S204: The first control module determines the increase or decrease of the frequency change; if the "difference between the current value and the previous value of the input current" and the "difference between the current frequency and the previous frequency" have the same sign, the current frequency fsw should be reduced by the step size fsw_step to move toward the maximum efficiency point, otherwise, fsw should be increased by fsw_step;

[0083] Step S205: After the frequency is updated, the second acquisition module obtains the output current value and output voltage value of the power converter through the voltage sampling circuit and the current sampling circuit, and feeds back the current output voltage value and output current value to the second control module; the second control module calculates the output power, and obtains the output power error by comparing it with the rated output power (also called the preset power value), and inputs it to the PI controller to update the duty cycle under the current circuit working state to ensure that the output power of the converter remains unchanged.

[0084] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0085] The above is a description of a specific embodiment of the specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0086] Each embodiment in this specification is described in a progressive manner, and the same and similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In the description of this specification, the description of reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of this specification. In this specification, the schematic representation of the above terms does not necessarily target the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples without contradiction.

[0087] The above is only an example of the embodiment of the present specification and is not intended to limit the embodiment of the present specification. For those skilled in the art, the embodiment of the present specification may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the embodiment of the present specification shall be included in the scope of the claims of the embodiment of the present specification.

Claims

1. An adaptive frequency optimization control system based on a DC-DC converter, characterized in that: include: A first acquisition module is connected to the positive output terminal of the input power supply and is used to acquire an input current signal of the converter; A second acquisition module is connected to the positive input terminal of the output load and is used to acquire the output voltage value and the output current value of the converter; A first control module, connected to the output end of the first acquisition module, for determining a frequency value of the converter when power loss is minimum according to the input current signal; The second control module is connected to the output end of the second acquisition module, and is used to calculate the duty cycle corresponding to the frequency value according to the output voltage value and the output current value, so that the output power of the converter remains unchanged when the frequency of the converter changes.

2. The adaptive frequency optimization control system based on DC-DC converter according to claim 1 is characterized in that: The first acquisition module includes a current sampling circuit.

3. The adaptive frequency optimization control system based on DC-DC converter according to claim 1 is characterized in that: The second acquisition module includes a current sampling circuit and a voltage sampling circuit.

4. The adaptive frequency optimization control system based on DC-DC converter according to claim 1 is characterized in that: The second acquisition module is specifically used to calculate the output power value of the converter according to the output voltage value and the output current value.

5. The adaptive frequency optimization control system based on DC-DC converter according to claim 1 is characterized in that: The first control module is specifically used to calculate a first difference between a current value of the input current signal and a previous value of the input current signal, and a second difference between a current frequency and a previous frequency; and to update the operating frequency of the converter according to the first difference and the second difference.

6. The DC-DC converter-based adaptive frequency optimization control system according to claim 5, characterized in that: The first control module is specifically used to calculate the step length according to the current state of the converter; Wherein, if the current state is the first state, the operating frequency of the converter is reduced according to the step size to move toward the maximum efficiency point; wherein the first state is that the first difference and the second difference have the same sign; If the current state is the second state, the operating frequency of the converter is increased according to the step size to move toward the maximum efficiency point; wherein the first state is that the signs of the first difference and the second difference are different.

7. The DC-DC converter-based adaptive frequency optimization control system according to claim 6, characterized in that: The calculation formula of the step length is: Among them, ξ and μ are parameters that control the convergence speed and accuracy, respectively.

8. The DC-DC converter-based adaptive frequency optimization control system according to claim 4, characterized in that: The second control module is specifically used to compare the output power difference between the output power value of the converter and the preset power value; perform PI control on the output power difference and then input it into the PWM wave generator to correct the duty cycle.

9. The DC-DC converter-based adaptive frequency optimization control system according to claim 8, characterized in that: When the output power difference is greater than zero, the output power value of the converter is greater than the preset power value, and the duty cycle decreases; When the output power difference is less than zero, the output power value of the converter is less than the preset power value, and the duty cycle increases; When the output power difference is equal to zero, the output power value of the converter is equal to the preset power value, and the duty cycle remains unchanged.

10. An adaptive frequency optimization control method based on a DC-DC converter, applied to the adaptive frequency optimization control system based on a DC-DC converter according to any one of claims 1 to 9, characterized in that: include: The first acquisition module acquires an input current signal of the converter, and feeds back a current value of the input current signal to the first control module; The first control module calculates a first difference between a current value of the input current signal and a previous value of the input current signal, and a second difference between a current frequency and a previous frequency; and updating the operating frequency of the converter according to the first difference and the second difference; A second acquisition module acquires an output current value and an output voltage value of the converter, and feeds the output current value and the output voltage value back to a second control module; The second control module calculates the output power value according to the output current value and the output voltage value; compares the output power difference between the output power value of the converter and the preset power value; The duty cycle of the converter in the current working state is updated according to the output power difference to ensure that the output power of the converter remains unchanged.

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