Control method of power conversion circuit and power conversion circuit

Abstract

The application provides a power conversion circuit and a control method thereof, and the control method comprises the following steps: determining a preset load and a preset working frequency of the power conversion circuit; obtaining a current load of the power conversion circuit; if the current load does not exceed the preset load, determining a running number of the power conversion circuit working at the preset working frequency in a working cycle according to the preset working frequency and the current load; and controlling the power conversion circuit to work based on the preset working frequency and the running number in the working cycle, so that the driving loss and the switching loss in the conversion process of the circuit are reduced, the conversion efficiency of the circuit under the light load state is further improved, and no more complex frequency is introduced, which is more conducive to the design of an EMC filter circuit.

Description

Technical Field

[0001] This invention relates to the field of electronic circuits, and more particularly to a control method for power conversion circuits and power conversion circuits. Background Technology

[0002] The core of power electronics technology is to use power conversion circuits to efficiently convert electrical energy. How to improve the conversion efficiency of power conversion circuits and reduce losses during the conversion process has always been the core problem that power electronics technology needs to solve.

[0003] Frequency modulation mode (PFM) is widely used due to its advantages such as extremely high efficiency under light load, ease of soft switching, and strong adaptability to wide input / output range. In practical applications, power conversion circuits using PFM operate at high frequencies under light loads and low frequencies under heavy loads. However, increasing the frequency under light loads leads to greater drive and switching losses in the semiconductor devices within the power conversion circuit, thus affecting the light-load efficiency of the power conversion circuit. Summary of the Invention

[0004] This invention provides a control method and a power conversion circuit for power conversion circuits, in order to solve the technical problems of low circuit efficiency under light load conditions and the introduction of a lot of noise by complex frequencies in the prior art.

[0005] This invention provides a control method for a power conversion circuit, the method comprising:

[0006] Determine the preset load and preset operating frequency of the power conversion circuit;

[0007] Obtain the current load of the power conversion circuit;

[0008] If the current load does not exceed the preset load, the number of times the power conversion circuit operates at the preset operating frequency within one working cycle is determined based on the preset operating frequency and the current load;

[0009] During this working cycle, the power conversion circuit is controlled to operate based on the preset working frequency and the number of runs.

[0010] In one embodiment, the steps of determining the preset load and preset operating frequency of the power conversion circuit include:

[0011] Obtain the operating efficiency of the power conversion circuit under various loads in frequency modulation mode;

[0012] The load corresponding to the optimal work efficiency is determined as the preset load;

[0013] The operating frequency of the power conversion circuit under the preset load is determined as the preset operating frequency.

[0014] In one embodiment, the power conversion circuit is an LLC resonant circuit, and the steps of determining the preset load and preset operating frequency of the power conversion circuit include:

[0015] The resonant frequency of the LLC resonant circuit is determined as the preset operating frequency;

[0016] The load of the LLC resonant circuit at the resonant frequency is determined as the preset load.

[0017] In one embodiment, the step of determining the number of times the power conversion circuit operates at the preset operating frequency within one operating cycle, based on the preset operating frequency and the current load, includes:

[0018] The duty cycle of the power conversion circuit operating at a preset operating frequency within one working cycle is determined based on the preset load and the current load.

[0019] The number of times the power conversion circuit operates within one working cycle is determined based on the duty cycle and the preset operating frequency.

[0020] In one embodiment, the step of controlling the operation of the power conversion circuit based on the preset operating frequency and the number of runs during the operating cycle includes:

[0021] Generate a number of drive signals corresponding to the number of runs, wherein the frequency of the drive signal is the preset operating frequency, and the duty cycle is the duty cycle corresponding to the power conversion circuit operating at the preset operating frequency;

[0022] After the power conversion circuit has completed its number of runs, it stops working at other times within the operating cycle.

[0023] In one embodiment, the method further includes:

[0024] The operating cycle of the power conversion circuit is determined according to the preset operating frequency.

[0025] In one embodiment, the working cycle is an integer multiple of the cycle corresponding to the preset working frequency.

[0026] In one embodiment, the method further includes:

[0027] If the current load exceeds the preset load, the power conversion circuit is controlled to operate through frequency modulation mode.

[0028] In one embodiment, the power conversion circuit is a non-isolated conversion circuit or an isolated conversion circuit.

[0029] This application also provides a power conversion circuit, the power conversion circuit including a control module, the control module being used to execute the control method of the power conversion circuit as described in any of the above claims, so as to control the operation of the power conversion circuit.

[0030] Compared with the prior art, the technical solution of the embodiments of the present invention has the following beneficial effects:

[0031] The control method and power conversion circuit provided in this embodiment of the invention utilize a working frequency at which the circuit operates at high efficiency. The circuit operates at this fixed frequency (with a certain deviation) a certain number of times within the working cycle according to the load, and can stop operating at other times. This effectively reduces the drive loss and switching loss during the circuit conversion process, thereby further improving the circuit conversion efficiency under light load conditions. Furthermore, since the working frequency is fixed, it does not introduce more complex frequencies, which is more conducive to the design of EMC filter circuits. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention, but not all embodiments. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0033] Figure 1 A flowchart illustrating a control method for a power conversion circuit provided in an embodiment of this application;

[0034] Figure 2 A flowchart illustrating step S110 of a control method for a power conversion circuit provided in an embodiment of this application;

[0035] Figure 3 A flowchart illustrating step S110 in a control method for a power conversion circuit provided in another embodiment of this application;

[0036] Figure 4 A flowchart illustrating step S130 in a control method for a power conversion circuit provided in an embodiment of this application;

[0037] Figure 5 A flowchart illustrating step S140 in a control method for a power conversion circuit provided in an embodiment of this application;

[0038] Figure 6 This is a schematic diagram of the structure of a power conversion circuit provided in one embodiment of this application;

[0039] Figure 7 A schematic diagram of a power conversion circuit provided in an embodiment of this application;

[0040] Figure 8 A schematic diagram of a power conversion circuit provided in another embodiment of this application;

[0041] Figure 9 This is a schematic diagram of a power conversion circuit provided in one embodiment of this application. Detailed Implementation

[0042] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0043] It should be understood that the terms “system,” “device,” “unit,” and / or “module” used herein are one way to distinguish different components, elements, parts, sections, or assemblies at different levels. However, if other terms can achieve the same purpose, they may be replaced by other expressions.

[0044] As illustrated herein, unless the context clearly indicates otherwise, the words “a,” “an,” “an,” and / or “the” do not specifically refer to the singular and may also include the plural. Generally speaking, the terms “comprising” and “including” only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0045] The definitions used herein, such as the terms “having,” “may have,” “comprising,” or “may include,” indicate the presence of the corresponding function, operation, element, etc., and do not limit the presence of one or more other functions, operations, elements, etc. Furthermore, it should be understood that the terms “comprising” or “having” as used herein indicate the presence of the features, figures, steps, operations, elements, components, or combinations thereof described in the specification, without excluding the presence or addition of one or more other features, figures, steps, operations, elements, components, or combinations thereof.

[0046] The definitions of "first" and "second" in this document, and the descriptions of "first" and "second" appearing in this document, are for illustrative purposes and to distinguish the objects being described. They do not indicate any order or limit on the number of devices, and do not constitute any limitation on this document. For example, a first element may be referred to as a second element without departing from the scope of this disclosure, and similarly, a second element may be referred to as a first element.

[0047] The definition of connection in this document will be understood to mean that when an element (e.g., a first element) is “connected to” or “operationally or communicatively coupled to” another element (e.g., a second element), the element may be directly connected or coupled to the other element, and there may be an intermediate element (e.g., a third element) between the element and the other element. Conversely, it will be understood that when an element (e.g., a first element) is “directly connected to” or “directly coupled to” another element (e.g., a second element), there is no intermediate element (e.g., a third element) between the element and the other element.

[0048] This application discloses a control method and a power conversion circuit for power conversion circuits, in order to solve the problems of low circuit efficiency under light load conditions and the introduction of more noise at complex frequencies in the prior art.

[0049] The technical solutions provided by the various embodiments of this application are described in detail below with reference to the accompanying drawings.

[0050] Figure 1 This is a flowchart illustrating a control method for a power conversion circuit provided in an embodiment of this application. The control method involved in this embodiment is applied to a power conversion circuit. The power conversion circuit can be a circuit that adopts a frequency modulation mode, such as a non-isolated conversion circuit, such as a Buck circuit, a Boost circuit, etc., or it can be an isolated circuit, such as an LLC resonant circuit, etc. The switching devices in the power conversion circuit can include MOSFETs, IGBTs, or SiC, etc., and this application does not specifically limit them.

[0051] like Figure 1 As shown, a control method for a power conversion circuit includes:

[0052] Step S110: Determine the preset load and preset operating frequency of the power conversion circuit.

[0053] Specifically, since the frequency modulation circuit operates at a high frequency under light load, resulting in high drive loss and low circuit efficiency, in order to improve the circuit efficiency under light load, it is necessary to change the control method of the circuit under light load. This application determines the load and operating frequency of the power conversion circuit when it is at its highest efficiency (with a certain deviation) as the preset load and preset operating frequency.

[0054] Step S120: Obtain the current load of the power conversion circuit.

[0055] Specifically, since the frequency modulation circuit is only less efficient under light load, but can generally achieve higher efficiency under heavy load, it is necessary to obtain the current load of the power conversion circuit in real time and compare the current load with the preset load to determine the current load state of the power conversion circuit and whether the control method needs to be changed to achieve higher efficiency.

[0056] Step S130: If the current load does not exceed the preset load, determine the number of times the power conversion circuit operates at the preset operating frequency within one working cycle based on the preset operating frequency and the current load.

[0057] Specifically, when it is determined that the current load does not exceed the preset load, that is, the power conversion circuit is in a light load state with low efficiency, it is necessary to change the control mode of the circuit to make it work at the preset operating frequency in order to reduce the drive loss caused by high frequency. However, since the current load is low, the power conversion circuit cannot always work at the preset operating frequency. It is necessary to determine the number of times the power conversion circuit works at the preset operating frequency in one working cycle according to the current load, so as to simultaneously meet the power requirements of the preset operating frequency and the current load.

[0058] Step S140: During this working cycle, the power conversion circuit is controlled to work based on the preset working frequency and the number of runs.

[0059] Specifically, after determining the number of times the power conversion circuit will run within a working cycle, a corresponding number of drive signals can be generated so that the power conversion circuit can operate at a preset operating frequency for that number of times within a working cycle. During the remaining time within that working cycle, it can stop operating, thereby reducing drive losses and improving the efficiency of the power conversion circuit.

[0060] In summary, the power conversion circuit control method provided by the embodiments of the present invention, by adopting the operating frequency when the circuit has high operating efficiency, runs the circuit a certain number of times at this fixed frequency (with a certain deviation) within the working cycle according to the load, and can stop working at other times, can effectively reduce the driving loss and switching loss during the circuit conversion process, thereby further improving the circuit conversion efficiency under light load conditions. Moreover, since the operating frequency is fixed, it will not introduce more complex frequencies, which is more conducive to the design of EMC filter circuits.

[0061] Figure 2 This is a flowchart illustrating step S110 of a control method for a power conversion circuit provided in an embodiment of this application, as shown below. Figure 2 As shown, in one embodiment, step S110 may include:

[0062] Step S111: Obtain the operating efficiency of the power conversion circuit under various loads in frequency modulation mode.

[0063] Step S112: Determine the load corresponding to the optimal working efficiency as the preset load.

[0064] Step S113: Determine the operating frequency of the power conversion circuit under the preset load as the preset operating frequency.

[0065] Specifically, when power conversion circuits such as Buck circuits operate in frequency modulation mode, an increase in load represents an increase in transmitted energy. The frequency is higher with a lighter load and lower with a heavier load. As the load increases, the circuit's conversion efficiency gradually increases to its maximum. After reaching this maximum efficiency, further increases in load will cause the efficiency to slowly decrease due to increased conduction losses, turn-off losses, and copper losses in the circuit components. Therefore, to maintain maximum efficiency, the efficiency of the power conversion circuit under various loads can be obtained. The load at which the circuit achieves maximum efficiency can be defined as the preset load, and the operating frequency under that load can also be defined as the preset operating frequency. By operating the power conversion circuit at this preset operating frequency, the circuit's maximum efficiency can be maintained.

[0066] Understandably, the specific values ​​of the preset load and preset operating frequency can be calculated based on the circuit structure of the power conversion circuit or determined through testing. For example, in a specific implementation, the maximum efficiency of a Buck circuit is achieved at 60% load, and the operating frequency of the Buck circuit is 65kHz. Therefore, the preset load is 60% and the preset operating frequency is 65kHz.

[0067] Figure 3 A flowchart illustrating step S110 in a control method for a power conversion circuit according to another embodiment of this application is shown below. Figure 3 As shown, in one embodiment, the power conversion circuit is an LLC resonant circuit, and step S110 above may include:

[0068] Step S114: Determine the resonant frequency of the LLC resonant circuit as the preset operating frequency.

[0069] Step S115: Determine the load of the LLC resonant circuit at the resonant frequency as the preset load.

[0070] Specifically, a typical circuit that uses frequency modulation is the LLC resonant circuit. When the power conversion circuit is an LLC resonant circuit, the LLC resonant circuit is most efficient when it operates at the resonant frequency. Therefore, the resonant frequency of the LLC resonant circuit can be directly determined as the preset operating frequency, and the load at which the LLC resonant circuit operates at the resonant frequency can be determined as the preset load.

[0071] Figure 4This is a flowchart illustrating step S130 of a control method for a power conversion circuit according to an embodiment of this application, as shown below. Figure 4 As shown, in one embodiment, step S130 may include:

[0072] Step S131: Determine the duty cycle of the power conversion circuit operating at the preset operating frequency within one working cycle based on the preset load and the current load.

[0073] Step S132: Determine the number of times the power conversion circuit operates within one working cycle based on the duty cycle and the preset operating frequency.

[0074] Specifically, the preset load is the load that runs at a preset operating frequency in frequency modulation mode. Therefore, based on the ratio of the preset load to the current load, the duty cycle of the power conversion circuit at the preset operating frequency to satisfy the current load can be determined. Thus, based on the duty cycle, the preset operating frequency, and the duration of the operating cycle, the number of times the power conversion circuit runs in one operating cycle can be calculated.

[0075] Figure 5 This is a flowchart illustrating step S140 of a control method for a power conversion circuit according to an embodiment of this application, as shown below. Figure 5 As shown, in one embodiment, step S140 may include:

[0076] Step S141: Generate a number of drive signals corresponding to the number of runs, wherein the frequency of the drive signal is the operating frequency, and the duty cycle is the duty cycle corresponding to the power conversion circuit operating at the preset operating frequency.

[0077] Step S142: After the power conversion circuit has completed its number of runs, it stops working at other times during the operating cycle.

[0078] Specifically, a corresponding number of drive signals can be generated based on the number of times the power conversion circuit runs within a working cycle. After receiving the drive signals, the power conversion circuit operates at a preset operating frequency. After the power conversion circuit completes the required number of runs, it can stop operating for the rest of the working cycle, thereby reducing drive losses and improving the efficiency of the power conversion circuit.

[0079] In one embodiment, the above method further includes:

[0080] The operating cycle of the power conversion circuit is determined based on the preset operating frequency.

[0081] Specifically, the power conversion circuit needs to operate at a preset operating frequency for a complete cycle, meaning the number of cycles must be an integer. This can lead to discontinuities in the duty cycle, causing load discontinuities and resulting in limit cycle oscillations during load adjustments. This issue can be avoided by adjusting the operating cycle of the power conversion circuit using the preset operating frequency.

[0082] Furthermore, in one embodiment, the working cycle is an integer multiple of the cycle corresponding to the preset working frequency.

[0083] By setting the duty cycle to an integer multiple of the single operating cycle corresponding to the preset operating frequency, the continuity of the duty cycle can be guaranteed, thereby avoiding limit cycle oscillations during load adjustment. The multiple of the duty cycle relative to the single operating cycle can be determined according to the duty cycle adjustment accuracy of the circuit. For example, in a specific embodiment, the duty cycle can be set to 100 times the single operating cycle, thereby achieving a duty cycle adjustment accuracy of 1%.

[0084] In a specific embodiment, when the current load Io of the power conversion circuit does not exceed the preset load Iomax, i.e., the power conversion circuit is in a light load state, the preset operating frequency 1 / ts of the power conversion circuit at its optimal efficiency in frequency modulation mode is first determined, and the operating period Ts of the power conversion circuit is set to an integer multiple of the single operating period ts corresponding to the preset operating frequency. Then, the duty cycle D of the power conversion circuit operating at the preset operating frequency within one operating cycle is determined. The duty cycle D is specifically the ratio of the current load to the preset load, i.e. At the same time, because the duty cycle is also equal to the ratio of the duration of a single running cycle ts (n times) to the working cycle duration Ts, that is... Therefore, based on The number of times the power conversion circuit runs, n, within one working cycle Ts is calculated, thereby controlling the power conversion circuit to run n times at a preset working frequency 1 / ts within one working cycle Ts, so as to efficiently meet the current load Io.

[0085] In one embodiment, after step S120, the above method further includes:

[0086] If the current load exceeds the preset load, the power conversion circuit is controlled to operate through frequency modulation mode.

[0087] Specifically, since the efficiency of the frequency modulation circuit does not change significantly after exceeding the load corresponding to its maximum efficiency, meaning it can maintain high efficiency under heavy load conditions, there is no need to change the operating state of the power conversion circuit. The power conversion circuit can still be controlled using frequency modulation mode; that is, by adjusting the operating frequency of the power conversion circuit, a lower frequency results in a larger output current for the same output voltage, thus meeting the demands of high loads. The type of frequency modulation mode can be determined based on the actual situation of the power conversion circuit; for example, a critical control mode can be selected to control the power conversion circuit.

[0088] In one embodiment, this application also provides a power conversion circuit. The power conversion circuit includes a control module, which is used to execute the control method of the power conversion circuit as described in any of the above embodiments to control the operation of the power conversion circuit.

[0089] Specifically, the power conversion circuit can be a non-isolated conversion circuit, such as a Buck circuit or a Boost circuit, or it can be an isolated circuit, such as an LLC resonant circuit. The switching devices in the power conversion circuit can include MOSFETs, IGBTs, or SiC, etc. This embodiment does not make specific limitations on this.

[0090] To enable those skilled in the art to fully understand and implement this invention, the following examples, using two specific application scenarios, further supplement the specific implementation principles of this invention.

[0091] Figure 6 This is a schematic diagram of a power conversion circuit according to an embodiment of this application. Figure 7 A schematic diagram of a power conversion circuit provided in one embodiment of this application is shown below. Figure 6 and Figure 7 As shown, in this embodiment, the power conversion circuit is a Buck circuit. The Buck circuit includes a switch Q1, a switch Q2, an input capacitor Cin, an output capacitor Co, an inductor Lf, and a resistor Rload. The input voltage of the Buck circuit is Vin, the output voltage is Vo, the inductor voltage is VLf, and the inductor current is ILf.

[0092] In this Buck circuit, when the circuit efficiency is highest, the preset load is Iomax, and the preset operating frequency is 1 / ts, where ts is a single operating cycle and Ts is the duty cycle. When the current load Io of the Buck circuit does not exceed Iomax, i.e., it is in a light load state, the Buck circuit can operate at the preset operating frequency (1 / ts) within a complete duty cycle Ts, and then pause for a certain period of time until Ts ends. The number of ts cycles can be adjusted according to the current load Io. This allows the circuit to operate at an optimal efficiency ts. The duty cycle D is then adjusted based on the current load Io. , where n is the number of times the circuit operates at a preset operating frequency (1 / ts) within the working cycle Ts. Since the ts operating state is the point of optimal efficiency, there is no circuit loss when the circuit stops operating within Ts, so the overall efficiency can reach the optimal level.

[0093] When the current load Io of the Buck circuit exceeds Iomax, i.e., it is under heavy load, the Buck circuit can be switched back to frequency modulation mode. By simultaneously adjusting the conduction times of switches Q1 and Q2, it is ensured that the inductor current is negative when switch Q2 is on, combined with the dead time of the drives of switches Q1 and Q2. When switch Q2 is off, the inductor current discharges in reverse to switch Q1. After switching Q1 is turned on again, switch Q1 turns on at zero voltage (Vds=0), eliminating turn-on losses and ensuring overall efficiency under high load.

[0094] Figure 8 This is a schematic diagram of a power conversion circuit according to another embodiment of this application. Figure 9 This is a schematic diagram of a power conversion circuit according to another embodiment of this application. In this embodiment, as shown... Figure 8 and Figure 9 As shown, the power conversion circuit is an LLC resonant circuit. The LLC resonant circuit includes a switching transistor S1, a switching transistor S2, a resonant inductor Lr, a magnetizing inductor Lm, a resonant capacitor Cr, a filter capacitor Cf, a resonant transformer T1, a rectifier diode D1, and a rectifier diode D2. The input voltage of the LLC resonant circuit is Vin, the output voltage is Vo, the primary resonant current is IL, and the secondary rectified current is Irec.

[0095] The LLC resonant circuit exhibits high output voltage due to high load impedance under light load conditions, requiring a slight increase in frequency to reduce gain. Conversely, under heavy or full load conditions, the output voltage is low due to low load impedance, necessitating a decrease in frequency to improve gain and stabilize the output voltage. Therefore, the resonant frequency can be selected as the preset operating frequency 1 / ts. The load at the resonant point of the LLC resonant circuit is Io. Similarly, if the current load Io does not exceed Iomax (i.e., under light load), the LLC can operate for n resonant cycles ts within a complete operating cycle Ts, followed by a pause until Ts ends. The number of n can be adjusted according to the current load Io. The resonant point is the most efficient operating state; during the pause within Ts, there is no circuit loss, resulting in optimal overall efficiency and further improving the conversion efficiency of the LLC resonant circuit. Conversely, when the current load Io exceeds Iomax (i.e., under heavy load), the LLC resonant circuit can be switched back to frequency modulation mode. The power conversion circuit described above uses a high operating frequency when the circuit operates. It operates at this fixed frequency a certain number of times according to the load within the working cycle, and can stop working at other times. This can effectively reduce the drive loss and switching loss during the circuit conversion process, thereby further improving the circuit conversion efficiency under light load conditions. Moreover, since the operating frequency is fixed, it does not introduce more complex frequencies, which is more conducive to the design of EMC filter circuits.

[0096] It is understood that the control module of the power conversion circuit described above can also be used to implement the control method of the power conversion circuit in any of the above embodiments, and has corresponding functional modules.

[0097] The various embodiments in this application are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the device and medium embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the description of the method embodiments.

[0098] The foregoing has described specific embodiments of this application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired results. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0099] The power conversion circuit and control method provided in this application are one-to-one correspondences. Therefore, the circuit also has similar beneficial technical effects as its corresponding method. Since the beneficial technical effects of the method have been described in detail above, the beneficial technical effects of the circuit will not be repeated here.

[0100] Those skilled in the art will understand that this application may take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. This application is described with reference to flowchart illustrations and / or block diagrams of methods and apparatus (circuits) according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by instructions. These instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0101] These instructions may also be stored in a memory that can direct a computer or other programmable data processing device to operate in a particular manner, such that the instructions stored in the memory produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0102] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0103] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0104] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A control method for a power conversion circuit, characterized in that, The method includes: Determine the preset load and corresponding preset operating frequency of the power conversion circuit; Obtain the current load of the power conversion circuit; If the current load does not exceed the preset load, the number of times the power conversion circuit operates at the preset operating frequency within one working cycle is determined based on the preset operating frequency and the current load; During this working cycle, the power conversion circuit is controlled to work based on the preset working frequency and the number of runs, and the power conversion circuit is controlled to stop working at other times.

2. The control method for a power conversion circuit according to claim 1, characterized in that, The steps for determining the preset load and preset operating frequency of the power conversion circuit include: Obtain the operating efficiency of the power conversion circuit under various loads in frequency modulation mode; The load corresponding to the optimal work efficiency is determined as the preset load; The operating frequency of the power conversion circuit under the preset load is determined as the preset operating frequency.

3. The control method for a power conversion circuit according to claim 1, characterized in that, The power conversion circuit is an LLC resonant circuit. The steps for determining the preset load and preset operating frequency of the power conversion circuit include: The resonant frequency of the LLC resonant circuit is determined as the preset operating frequency; The load of the LLC resonant circuit at the resonant frequency is determined as the preset load.

4. The control method for a power conversion circuit according to claim 1, characterized in that, The step of determining the number of times the power conversion circuit operates at the preset operating frequency within one operating cycle based on the preset operating frequency and the current load includes: The duty cycle of the power conversion circuit operating at a preset operating frequency within one working cycle is determined based on the preset load and the current load. The number of times the power conversion circuit operates within one working cycle is determined based on the duty cycle and the preset operating frequency. The duty cycle is the proportion of time during which the power conversion circuit operates at a preset operating frequency within one working cycle.

5. The control method for a power conversion circuit according to claim 1, characterized in that, During this working cycle, the steps of controlling the operation of the power conversion circuit based on the preset operating frequency and the number of runs include: Generate a number of drive signals corresponding to the number of runs, wherein the frequency of the drive signal is the preset operating frequency, and the duty cycle is the duty cycle corresponding to the power conversion circuit operating at the preset operating frequency; After the power conversion circuit has completed its number of runs, it stops working at other times within the operating cycle.

6. The control method for a power conversion circuit according to claim 1, characterized in that, The method further includes: The operating cycle of the power conversion circuit is determined according to the preset operating frequency.

7. The control method for a power conversion circuit according to claim 6, characterized in that, The working cycle is an integer multiple of the cycle corresponding to the preset working frequency.

8. The control method for a power conversion circuit according to claim 1, characterized in that, The method further includes: If the current load exceeds the preset load, the power conversion circuit is controlled to operate through frequency modulation mode.

9. The method according to any one of claims 1 to 8, characterized in that, The power conversion circuit is either a non-isolated conversion circuit or an isolated conversion circuit.

10. A power conversion circuit, characterized in that, The power conversion circuit includes a control module, which is used to execute the control method of the power conversion circuit as described in any one of claims 1 to 8 to control the operation of the power conversion circuit.

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