WO2019238039A1 - 检测llc变换器谐振频率的方法、设备和存储介质 - Google Patents

检测llc变换器谐振频率的方法、设备和存储介质 Download PDF

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WO2019238039A1
WO2019238039A1 PCT/CN2019/090694 CN2019090694W WO2019238039A1 WO 2019238039 A1 WO2019238039 A1 WO 2019238039A1 CN 2019090694 W CN2019090694 W CN 2019090694W WO 2019238039 A1 WO2019238039 A1 WO 2019238039A1
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frequency
llc converter
resonance
detecting
llc
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PCT/CN2019/090694
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English (en)
French (fr)
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胡永辉
林钊
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中兴通讯股份有限公司
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Definitions

  • the present disclosure relates to the field of power electronics technology.
  • LLC converter is a commonly used resonant converter.
  • the resonant cavity of LLC converter is composed of resonant inductor, transformer's excitation inductance and resonant capacitor.
  • the output voltage gain is always 1, regardless of the load size, and has the best efficiency.
  • the LLC converter In order to obtain the best efficiency, the LLC converter is designed to work at the resonance frequency. However, in the actual circuit, due to the difference in the parameters of the resonant cavity, the resonance inductance and resonance capacitance will have deviations, which will cause deviations in the resonance frequency. In order for the LLC converter to obtain optimal efficiency, it is necessary to accurately measure the resonant frequency of the LLC converter and set the operating frequency of the LLC converter to the resonant frequency.
  • a device for detecting a resonant frequency of an LLC converter including: a frequency generating unit configured to determine a frequency sweep range according to a tolerance range of a resonant parameter of the LLC converter, and control the The LLC converter sequentially scans frequencies in the frequency range at preset frequency intervals; the voltage acquisition unit is configured to obtain the input voltage Vin and the input voltage of the LLC converter at the currently scanned frequency each time a scan is performed.
  • is obtained; and a resonance frequency determination unit is configured to set the voltage difference value V
  • a device for detecting a resonant frequency of an LLC converter which includes a memory and a processor.
  • a computer program is stored on the memory, and the computer program is The processor performs the steps of the method for detecting a resonant frequency of an LLC converter according to the present disclosure.
  • a computer-readable storage medium on which one or more programs are stored, and when the one or more programs are executed by one or more processors, the one or more programs Processors perform detection LLC according to the present disclosure
  • Figure 1 is a schematic diagram of the main power circuit of an LLC converter.
  • Fig. 2 is a relationship diagram between the output voltage and frequency of an LLC converter.
  • FIG. 3 is a flowchart of a method of detecting a resonant frequency of an LLC converter according to an embodiment of the present disclosure.
  • FIG. 4 is a structural block diagram of an apparatus for detecting a resonant frequency of an LLC converter according to an embodiment of the present disclosure.
  • FIG. 5 is a flowchart of step S120 in the method of detecting a resonant frequency of an LLC converter shown in FIG. 3 according to an embodiment of the present disclosure.
  • FIG. 6 is a sweeping voltage sampling result of the method for detecting a resonant frequency of an LLC converter shown in FIG. 3 according to an embodiment of the present disclosure.
  • FIG. 7 is a structural block diagram of a device for detecting a resonant frequency of an LLC converter according to another embodiment of the present disclosure.
  • Figure 1 shows a schematic diagram of the main power circuit of an LLC converter.
  • the resonant cavity of an LLC converter consists of a resonant inductor Lr, a transformer's excitation inductance Lm, and a resonant capacitor Cr.
  • Lr resonant inductor
  • Lm transformer's excitation inductance
  • Cr resonant capacitor
  • Figure 2 shows the relationship between the output voltage and frequency of the LLC converter.
  • the gain curves of LLC converters with different Q values represent the gain curves of LLC converters with different loads.
  • the LLC converter In order to obtain the best efficiency, the LLC converter is designed to work at the resonance frequency.
  • the resonance inductance has a deviation of +/- 10%
  • the resonance capacitance has a deviation of +/- 5%
  • the resonance frequency will now have a deviation of +/- 7.5%.
  • the nominal resonance frequency is 500KHz
  • the range of the actual resonance frequency is about 460-540KHz. If the switching frequency is only fixed at the nominal resonance frequency, the deviation of the actual resonance frequency point will cause a large deviation in the efficiency of the LLC resonant converter. Therefore, in order to obtain the optimal efficiency of the LLC converter, it is necessary to accurately measure the resonant frequency of the LLC converter and set the operating frequency of the LLC converter to the resonant frequency.
  • FIG. 3 is a flowchart of a method of detecting a resonant frequency of an LLC converter according to an embodiment of the present disclosure.
  • the method for detecting a resonant frequency of an LLC converter includes steps S110 to S130.
  • the method for detecting a resonant frequency of an LLC converter is mainly performed based on the detection of the resonant frequency of the LLC converter 100 as shown in FIG. 4, and the resonant frequency of the LLC converter 100 includes a voltage obtaining unit. 110, a comparison unit 120, a resonance frequency determination unit 130, and a frequency generation unit 140.
  • the voltage obtaining unit 110 is connected to the input and output ends of the resonant circuit of the LLC converter, and is used to detect the input voltage Vin and the output voltage Vo of the LLC converter at different frequencies in the frequency sweep range.
  • the comparison unit 120 is configured to compare a sampled output voltage and a result of dividing the sampled input voltage by a transformer turns ratio according to a result obtained by the voltage obtaining unit 110.
  • the resonance frequency determining unit 130 is configured to determine a resonance frequency of the LLC converter according to an output result of the comparison unit.
  • the frequency generating unit 140 is configured to generate a switching signal of a corresponding operating frequency according to a frequency sweep range to drive the resonant circuit to work.
  • a frequency sweep range is determined according to a tolerance range of a resonance parameter of the LLC converter.
  • the resonance parameters include the nominal resonance frequency and the resonance frequency deviation.
  • the resonance frequency deviation is determined jointly by the resonance inductance deviation of the LLC converter and the resonance capacitance deviation of the LLC converter.
  • the nominal resonant frequency of the LLC converter is 500KHz
  • the deviation of the resonance inductance is ⁇ 10%
  • the resonance capacitance is ⁇ 5%
  • the tolerance range of the actual resonance frequency is about 460-540KHz.
  • the sweep frequency range is set to be larger than the tolerance range of the resonance frequency, so when the nominal resonance frequency is 500KHz, the sweep frequency range is set to 400-600KHz.
  • step S120 frequencies within the frequency sweep range are sequentially scanned at preset frequency intervals.
  • the relationship between the output voltage gain and frequency of the LLC converter is known.
  • the gain curves of different Q values represent the gain curves of different loads.
  • the output voltage gain at the resonant frequency is always 1 at different loads.
  • the relationship between the output voltage gain and frequency of the LLC converter is used to perform the resonance frequency detection.
  • the voltage gain of the LLC converter is 1
  • the operating frequency is the resonant frequency of the LLC converter.
  • the output voltage gain at the resonance frequency is less than 1, and the larger the load, the smaller the output voltage gain, which affects the accuracy of the resonance frequency detection of the method.
  • Another disadvantage of heavy duty frequency sweeping is that it consumes more energy. Therefore, from the perspective of accuracy of resonance frequency detection and energy consumption, it is necessary to set the load of the LLC converter during the frequency sweep to light load, for example, to make the output current of the LLC converter 1A or 2A.
  • the resonant frequency of the LLC converter is the nominal resonant frequency of 500KHz. If the scan starts from the lowest frequency of 400KHz in the sweep range of the nominal resonant frequency of 500KHz to 400-600KHz, the LLC converter uses synchronous rectification, and the LLC transformer works at resonance At frequencies below the frequency point, there is a problem of output back-flushing. Although scanning starts from a low frequency, and the ON time of the synchronous rectifier is set to the highest frequency to prevent the problem of back-flow, this operation method will bring about the problem of the conduction of the synchronous rectifier body diode and affect the output. The voltage thus affects the accuracy of the resonance frequency detection. Therefore, the embodiments of the present disclosure limit scanning from the highest frequency in the frequency sweep range, and stopping the scanning when the resonance frequency is determined can effectively avoid the output backflow and does not affect the resonance frequency detection accuracy.
  • the preset frequency interval is set according to the determined swept frequency range and the detection accuracy of the resonance frequency.
  • the preset frequency interval is 10 KHz.
  • step S120 specifically includes steps S121 to S122.
  • step S121 the load of the LLC converter is set to a light load.
  • light load means a load that causes the output current of the LLC converter to be less than 20% of the rated output current.
  • step S122 starting from the highest frequency in the frequency sweep range, decreasing downwards at the preset frequency interval, and sequentially scanning frequencies in the frequency sweep range.
  • the input voltage of the LLC converter is set to a rated voltage of 48V
  • the load is set so that the output current of the LLC converter is 1A
  • the preset frequency interval is 10KHz. Then, starting from the highest frequency in the frequency sweep range, decreasing downwards at the preset frequency interval, and sequentially scanning the frequencies in the frequency sweep range.
  • the frequencies in the frequency sweep range are sequentially scanned
  • the current operating frequency of the LLC converter is set to the current frequency being scanned, and the input voltage Vin and corresponding to the LLC converter at the current operating frequency are collected and recorded.
  • Output voltage Vo is the input voltage Vin and corresponding to the LLC converter at the current operating frequency are collected and recorded.
  • the frequency generating unit 140 first set the scanning frequency to 600KHz, set the operating frequency of the LLC converter to 600KHz, and the frequency generating unit 140 generates a switching signal of the corresponding operating frequency to drive the resonant circuit to work.
  • the input voltage is a known amount It is not necessary to detect the input voltage Vin, and it is only required to detect the output voltage Vo of the LLC converter, and the voltage acquisition unit 110 records the output voltage Vo and the input voltage Vin corresponding to the frequency.
  • the scanning frequency is sequentially set to 590KHz, 580KHz, 570KHz, etc., and so on, the frequencies in the scanning frequency range are sequentially scanned, and the voltage obtaining unit 110 records the output voltage Vo and input voltage Vin corresponding to each scanning frequency.
  • the voltage difference V
  • FIG. 6 is a sweep frequency voltage sampling result of a method for detecting a resonant frequency of an LLC converter according to an embodiment of the present disclosure.
  • the horizontal axis is the operating frequency of the LLC converter
  • the vertical axis is the output voltage of the LLC converter
  • the load is set so that the output current of the LLC converter is 1A.
  • the resonance frequency determination unit 130 can determine the resonance frequency fr of the LLC converter. 520KHz, and stop sweeping. Therefore, the technical solution of the present disclosure may not actually need to sweep the entire frequency sweep range, which is beneficial to improving the efficiency of detecting the resonance frequency.
  • FIG. 7 is a structural block diagram of a device for detecting a resonant frequency of an LLC converter according to another embodiment of the present disclosure.
  • the device 20 for detecting the resonant frequency of an LLC converter includes a memory 21 and a processor 22.
  • a computer program operable on the processor 22 is stored in the memory 21, and the processor 21 and the memory 22 are connected and communicated through a data bus 23.
  • detection LLC according to various embodiments of the present disclosure is implemented.
  • the method of the converter resonant frequency is, for example, the method of detecting the resonant frequency of an LLC converter described in conjunction with FIG. 3 to FIG. 5.
  • An embodiment of the present disclosure further provides a computer-readable storage medium on which one or more programs are stored, and the one or more programs can be executed by one or more processors to implement the embodiments according to the present disclosure.
  • the method for detecting the resonance frequency of an LLC converter for example, the method for detecting the resonance frequency of an LLC converter described in conjunction with FIG. 3 to FIG. 5.
  • the resonant frequency of the LLC converter can be accurately measured without measuring the specific parameters of the resonant element, so as to set the operating frequency of the LLC converter to the resonant frequency. To make the LLC converter get the best efficiency.
  • the division between functional modules / units mentioned in the above description does not necessarily correspond to the division of physical components.
  • one physical component may have multiple functions, or one function or step may be performed in cooperation by several physical components.
  • Some or all physical components can be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit .
  • Such software may be distributed on computer-readable media, which may include computer storage media (or non-transitory media) and communication media (or transitory media).
  • Computer storage medium includes both volatile and nonvolatile implementations in any method or technology used to store information such as computer-readable instructions, data structures, program modules or other data.
  • Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disk (DVD) or other optical disk storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or may Any other medium used to store desired information and which can be accessed by a computer.
  • a communication medium typically contains computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transmission mechanism, and may include any information delivery medium .

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Abstract

本公开提供一种检测LLC变换器谐振频率的方法、设备和存储介质。该方法包括：根据LLC变换器的谐振参数的容差范围确定扫频范围；按预设的频率间隔依次扫描扫频范围内的频率；在每次进行扫描时，获取当前被扫描的频率下所述LLC变换器的输入电压Vin和输出电压Vo，如果电压差值V＝|Vin/N-Vo|小于或等于预设阀值时，则判定当前被扫描的频率为LLC变换器的谐振频率，并不再继续对扫频范围内的频率进行扫描，其中，N为LLC变换器的变压器匝比。

Description

检测LLC变换器谐振频率的方法、设备和存储介质 技术领域
本公开涉及电力电子技术领域。
背景技术
LLC变换器是一种常用的谐振变换器，LLC变换器的谐振腔由谐振电感、变压器的励磁电感和谐振电容组成。LLC变换器工作在谐振频率时，输出电压增益始终为1，与负载大小无关，具有最优效率。
为了获得最优效率，LLC变换器被设计为工作在谐振频率点。但是，在实际电路中，由于谐振腔参数的差异，谐振电感和谐振电容会有偏差，使得谐振频率此出现偏差。为了使LLC变换器获得最优效率，必须准确测量LLC变换器的谐振频率并将LLC变换器的工作频率设定为谐振频率。
发明内容
根据本公开的实施例，提供一种检测LLC变换器谐振频率的方法，包括：根据LLC变换器的谐振参数的容差范围确定扫频范围；按预设的频率间隔依次扫描所述扫频范围内的频率；以及在每次进行扫描时，获取当前被扫描的频率下所述LLC变换器的输入电压Vin和输出电压Vo，如果电压差值V＝|Vin/N-Vo|小于或等于预设阀值时，则判定当前被扫描的频率为所述LLC变换器的谐振频率，并不再继续对所述扫频范围内的频率进行扫描，其中，N为所述LLC变换器的变压器匝比。
根据本公开的实施例，还提供了一种检测LLC变换器谐振频率的设备，包括：频率生成单元，被配置为根据LLC变换器的谐振参数的容差范围确定扫频范围，并控制所述LLC变换器按预设的频率间隔依次扫描所述频率范围内的频率；电压获取单元，被配置为在每次进行扫描时，获取当前被扫描的频率下所述LLC变换器的输入电压Vin和输出电压Vo；比较单元，被配置为在每次进行扫描时通过将所述 电压获取单元获取的所述LLC变换器的输入电压Vin和所述LLC变换器的变压器匝比N的比值与所述电压获取单元获取的所述LLC变换器的输出电压进行比较，并获取电压差值V＝|Vin/N-Vo|；以及谐振频率确定单元，被配置为当所述电压差值V＝|Vin/N-Vo|大于或等于预设阈值时，判定当前被扫描的频率为所述LLC变换器的谐振频率，并控制所述LLC变换器不再继续对所述扫频范围内的频率进行扫描。
根据本公开的实施例，还提出了一种检测LLC变换器谐振频率的设备，包括存储器和处理器，在所述存储器上存储有计算机程序，所述计算机程序被所述处理器执行时，所述处理器执行根据本公开的检测LLC变换器谐振频率的方法的步骤。
根据本公开的实施例，还提供了一种计算机可读存储介质，其上存储有一个或者多个程序，所述一个或者多个程序被一个或者多个处理器执行时，所述一个或者多个处理器执行根据本公开的检测LLC
变换器谐振频率的方法。
附图说明
图1是LLC变换器的主功率电路示意图。
图2是LLC变换器的输出电压和频率的关系图。
图3是根据本公开的实施例的检测LLC变换器谐振频率的方法的流程图。
图4是根据本公开的实施例的检测LLC变换器谐振频率的装置的结构框图。
图5是根据本公开的实施例的图3所示的检测LLC变换器谐振频率的方法中的步骤S120的流程图。
图6是根据本公开的实施例的图3所示的检测LLC变换器谐振频率的方法的扫频电压采样结果。
图7是根据本公开的另一实施例的检测LLC变换器谐振频率的设备的结构框图。
将结合实施例并参照附图对本公开目的的实现、功能特点及优点做进一步说明。
具体实施方式
应当理解，此处所描述的具体实施例仅仅用以解释本公开，并不用于限定本公开。
在后续的描述中，使用用于表示元件的诸如“模块”、“部件”或“单元”的后缀仅为了有利于本公开的说明，其本身没有特有的意义。因此，“模块”、“部件”或“单元”可以混合地使用。
图1示出了LLC变换器的主功率电路示意图。
如图1所示，LLC变换器的谐振腔由谐振电感Lr、变压器的励磁电感Lm、谐振电容Cr组成。通常，当LLC变换器工作在谐振频率
Figure PCTCN2019090694-appb-000001
时，LLC变换器的输出电压增益始终为1，与负载大小无关，电路具有最佳的效率。
图2示出了LLC变换器的输出电压和频率的关系图。
如图2所示，不同Q值的LLC变换器的增益曲线代表不同负载的LLC变换器的增益曲线，LLC变换器的Q值越大，负载越大，并且不同Q值的LLC变换器的增益曲线在谐振频率点(fs/fr＝1)的输出电压增益始终为1。
为了获得最优的效率，LLC变换器会被设计为工作在谐振频率点。但是，在实际电路中，由于谐振腔参数的差异，谐振电感有+/-10％的偏差，谐振电容有+/-5％的偏差，谐振频率此时会出现+/-7.5％的偏差。当标称谐振频率为500KHz时，实际谐振频率的范围约为460-540KHz。如果开关频率只固定在标称的谐振频率，则实际谐振频率点的偏差将会导致LLC谐振变换器的效率出现较大偏差。因此，为了使LLC变换器获得最优的效率，必须准确的测量LLC变换器的谐振频率并将LLC变换器的工作频率设定为谐振频率。
图3是根据本公开的实施例的检测LLC变换器谐振频率的方法的流程图。
如图3所示，根据本实施例的检测LLC变换器谐振频率的方法包括步骤S110至S130。
具体地，根据本公开实施例的检测LLC变换器谐振频率的方法 主要基于如图4所示的检测LLC变换器谐振频率检测装置100来进行，该LLC变换器谐振频率检测装置100包括电压获取单元110、比较单元120、谐振频率确定单元130以及频率生成单元140。
电压获取单元110和LLC变换器的谐振电路的输入和输出端相连，用于检测LLC变换器在扫频范围内的不同频率下的输入电压Vin和输出电压Vo。比较单元120用于根据电压获取单元110获取的结果，对采样的输出电压和采样的输入电压除以变压器匝比的结果相比较。谐振频率确定单元130用于根据比较单元的输出结果确定LLC变换器的谐振频率。频率生成单元140用于根据扫频范围生成相应的工作频率的开关信号来驱动谐振电路工作。
返回参照图3，在步骤S110，根据LLC变换器的谐振参数的容差范围确定扫频范围。
谐振参数包括标称谐振频率及谐振频率偏差。谐振频率偏差通过LLC变换器的谐振电感偏差及LLC变换器的谐振电容偏差来共同决定。例如，当该LLC变换器的标称谐振频率为500KHz时，在实际电路中，由于谐振腔参数的差异，谐振电感有±10％的偏差，谐振电容有±5％的偏差，谐振频率此时会出现±7.5％的偏差，即谐振参数偏差为±7.5％，实际谐振频率的容差范围约为460-540KHz。通常设置的扫频范围要大于谐振频率的容差范围，因此当标称谐振频率为500KHz时，设置的扫频范围为400-600KHz。
在步骤S120，按预设的频率间隔依次扫描该扫频范围内的频率。
具体地，从图2可知LLC变换器的输出电压增益和频率的关系，不同Q值的增益曲线代表不同负载的增益曲线，理论上不同负载时在谐振频率点输出电压增益始终为1。本公开实施例即是利用LLC变换器的输出电压增益和频率的关系来进行谐振频率检测。理论上说，当LLC变换器的电压增益为1时的工作频率即为LLC变换器的谐振频率。但是，由于LLC变换器内阻的关系，当重载的时候，在谐振频率点输出电压增益小于1，负载越大，输出电压增益越小，影响本方法的谐振频率检测的精度。重载进行扫频的另一个缺点是消耗能源较多。因此，从谐振频率检测的精度以及能源消耗的角度考虑，需要将LLC 变换器扫频时的负载设为轻载，比如使LLC变换器的输出电流为1A或者2A。
假设LLC变换器的谐振频率为标称谐振频率500KHz，如果从标称谐振频率500KHz的扫频范围400-600KHz中的最低频率400KHz开始扫描，对于LLC变换器采用同步整流，LLC变化器工作于谐振频率点以下的频率时会存在输出倒灌的问题。虽然从低频开始扫描，将同步整流管的驱动开通时间设为最高频率时的导通时间可以防止倒灌的问题，但是，这种操作方式会带来同步整流管体二极管导通的问题，影响输出电压从而影响谐振频率检测的精度。因此，本公开的实施例限定从扫频范围的最高频率开始扫描，当确定谐振频率时即停止扫描可以有效避免输出倒灌并且不影响谐振频率检测精度。
根据上述确定好的扫频范围及谐振频率的检测精度来设置预设的频率间隔。在此实施例中，预设的频率间隔为10KHz，如图5所示，该步骤S120具体包括步骤S121至S122。
在步骤S121，将该LLC变换器的负载设为轻载。在本公开的上下文中，“轻载”表示使得LLC变换器的输出电流在额定输出电流的20％以下的负载。
在步骤S122，从该扫频范围内的最高频率开始，按该预设的频率间隔向下递减，依次扫描该扫频范围内的频率。
例如，根据上述步骤确定扫频范围为400-600KHz后，设置LLC变换器的输入电压为额定电压48V，设置负载为使LLC变换器的输出电流为1A，预设的频率间隔为10KHz。然后，从该扫频范围内的最高频率开始，按该预设的频率间隔向下递减，依次扫描该扫频范围内的频率。在依次扫描该扫频范围内的频率时，将该LLC变换器的当前工作频率设定为被扫描的当前频率，并采集记录该LLC变换器在该当前工作频率下所对应的输入电压Vin和输出电压Vo。即首先将扫描频率设置为600KHz，设置LLC变换器的工作频率为扫频频率600KHz，频率生成单元140生成相应的工作频率的开关信号来驱动谐振电路工作，此时，由于输入电压为已知量，可以不对输入电压Vin进行检测，只需检测LLC变换器的输出电压Vo即可，电压获取单元110记 录该频率所对应的输出电压Vo和输入电压Vin。接着，依次将扫描频率设置为590KHz、580KHz、570KHz……以此类推，依次扫描该扫频范围内的频率，电压获取单元110记录每一扫描频率下所对应的输出电压Vo和输入电压Vin。
返回参照图3，在步骤S130，在每次进行扫描时，获取当前的扫描频率下LLC变压器的输入电压Vin和输出电压Vo，如果电压差值V＝|Vin/N-Vo|小于或等于预设阀值时，则判定当前的扫描频率为该LLC变换器的谐振频率，并不再继续对该扫频范围内的频率进行扫描，N为LLC变换器的变压器匝比。
具体地，在依次扫描该扫频范围内的频率的过程中，每获得一次输出电压Vo和输入电压Vin，均通过比较单元120将该电压差值V＝|Vin/N-Vo|与预设阀值进行比较，其中，N为该LLC变换器的变压器匝比，该预设阀值可根据该谐振频率的检测精度来设置。若某一扫描频率下，该电压差值V＝|Vin/N-Vo|小于或等于预设阀值时，则判定当前扫描频率为该LLC变换器的谐振频率，并结束对该扫频范围内的频率进行扫描。例如，设置该预设阀值为0.05V，变压器匝比为4,则Vin/N＝12；如果|12-Vo|≤0.05V，即Vo在11.95V-12.05V范围以内，则判定当前频率为该LLC变换器的谐振频率，并结束对该扫频范围内的频率进行扫描，如果Vo在11.95V-12.05V范围以外，则将工作频率按照扫频的频率间隔为10KHz往下递减，继续扫描该扫频范围内的下一频率。
图6是本公开实施例的检测LLC变换器谐振频率的方法的扫频电压采样结果。
参照图6，横轴坐标为LLC变换器的工作频率，纵轴坐标为LLC变换器的输出电压，负载被设置为使LLC变换器的输出电流为1A。频率由600KHz至400KHz扫频时，通过输出电压的采样结果可知，当工作频率为520KHz时，输出电压为11.974V，此时，谐振频率确定单元130便可将该LLC变换器的谐振频率fr确定为520KHz，并停止扫频。因此，本公开的技术方案实际上可能不需要对整个扫频范围进行扫频，有利于提升谐振频率检测的效率。
图7是根据本公开的另一实施例的检测LLC变换器谐振频率的设备的结构框图。
如图7所示，根据本实施例的检测LLC变换器谐振频率的设备20包括存储器21和处理器22。在存储器21存储有可在处理器22上运行的计算机程序，并且处理器21和存储器22通过数据总线23连接通信，该程序被处理器21执行时，实现根据本公开的各实施例的检测LLC变换器谐振频率的方法，例如，结合图3至图5所描述的检测LLC变换器谐振频率的方法。
本公开实施例还提供一种计算机可读存储介质，其上存储有一个或者多个程序，所述一个或者多个程序可被一个或者多个处理器执行，以实现根据本公开的各实施例的检测LLC变换器谐振频率的方法，例如，结合图3至图5所描述的检测LLC变换器谐振频率的方法。
本公开实施例提出的检测LLC变换器谐振频率的方法、设备和存储介质，通过根据LLC变换器的谐振参数的容差范围确定扫频范围，再按预设的频率间隔依次扫描该扫频范围内的频率，最后，若某一扫描频率下，电压差值V＝|Vin/N-Vo|小于或等于预设阀值时，则判定当前扫描频率为该LLC变换器的谐振频率，并结束对所述扫频范围内的频率进行扫描。可见，本技术方案，其通过利用LLC变换器的增益特性，无需实测谐振元件的具体参数，便可准确地测量LLC变换器的谐振频率，以将LLC变换器的工作频率设定为该谐振频率，来使得该LLC变换器能获得最优的效率。
本领域普通技术人员可以理解，上文中所公开方法中的全部或某些步骤、系统、设备中的功能模块/单元可以被实施为软件、固件、硬件及其适当的组合。
在硬件实施方式中，在以上描述中提及的功能模块/单元之间的划分不一定对应于物理组件的划分。例如，一个物理组件可以具有多个功能，或者一个功能或步骤可以由若干物理组件合作执行。某些物理组件或所有物理组件可以被实施为由处理器，如中央处理器、数字信号处理器或微处理器执行的软件，或者被实施为硬件，或者被实施为集成电路，如专用集成电路。这样的软件可以分布在计算机可读介 质上，计算机可读介质可以包括计算机存储介质(或非暂时性介质)和通信介质(或暂时性介质)。如本领域普通技术人员公知的，术语计算机存储介质包括在用于存储信息(诸如计算机可读指令、数据结构、程序模块或其他数据)的任何方法或技术中实施的易失性和非易失性、可移除和不可移除介质。计算机存储介质包括但不限于RAM、ROM、EEPROM、闪存或其他存储器技术、CD-ROM、数字多功能盘(DVD)或其他光盘存储、磁盒、磁带、磁盘存储或其他磁存储装置、或者可以用于存储期望的信息并且可以被计算机访问的任何其他的介质。此外，本领域普通技术人员公知的是，通信介质通常包含计算机可读指令、数据结构、程序模块或者诸如载波或其他传输机制之类的调制数据信号中的其他数据，并且可包括任何信息递送介质。
以上参照附图说明了本公开的优选实施例，并非因此局限本公开的权利范围。本领域技术人员不脱离本公开的范围和实质内所作的任何修改、等同替换和改进，均应在本公开的权利范围之内。

Claims (18)

  1. 一种检测LLC变换器谐振频率的方法，包括：
    根据LLC变换器的谐振参数的容差范围确定扫频范围；
    按预设的频率间隔依次扫描所述扫频范围内的频率；以及
    在每次进行扫描时，获取当前被扫描的频率下所述LLC变换器的输入电压Vin和输出电压Vo，如果电压差值V＝|Vin/N-Vo|小于或等于预设阀值时，则判定当前被扫描的频率为所述LLC变换器的谐振频率，并不再继续对所述扫频范围内的频率进行扫描，其中，N为所述LLC变换器的变压器匝比。
  2. 根据权利要求1所述的检测LLC变换器谐振频率的方法，其中，所述谐振参数包括标称谐振频率及谐振频率偏差。
  3. 根据权利要求2所述的检测LLC变换器谐振频率的方法，其中，所述谐振频率偏差通过所述LLC变换器的谐振电感偏差及所述LLC变换器的谐振电容偏差来共同决定。
  4. 根据权利要求1所述的检测LLC变换器谐振频率的方法，其中，根据所述扫频范围及所述谐振频率的检测精度来设置所述预设的频率间隔。
  5. 根据权利要求1所述的检测LLC变换器谐振频率的方法，其中，根据所述谐振频率的检测精度来设置所述预设阀值。
  6. 根据权利要求1所述的检测LLC变换器谐振频率的方法，其中，所述按预设的频率间隔依次扫描所述扫频范围内的频率的步骤包括：
    将所述LLC变换器的负载设为使得所述LLC变换器的输出电流在额定输出电流的20％以下的负载。
  7. 根据权利要求6所述的检测LLC变换器谐振频率的方法，其中，在所述将所述LLC变换器的负载设为使得所述LLC变换器的输出电流在额定输出电流的20％以下的负载的步骤之后，所述按预设的频率间隔依次扫描所述扫频范围内的频率的步骤还包括：
    从所述扫频范围内的最高频率开始，按所述预设的频率间隔向下递减，依次扫描所述扫频范围内的频率。
  8. 根据权利要求7所述的检测LLC变换器谐振频率的方法，其中，扫描所述扫频范围内的频率的步骤包括：
    将所述LLC变换器的当前工作频率设定为当前被扫描的频率，并且
    其中，获取当前被扫描的频率下所述LLC变换器的输入电压Vin和输出电压Vo的步骤包括：
    采集所述LLC变换器在所述当前工作频率下所对应的输入电压Vin和输出电压Vo。
  9. 一种检测LLC变换器谐振频率的设备，包括：
    频率生成单元，被配置为根据LLC变换器的谐振参数的容差范围确定扫频范围，并控制所述LLC变换器按预设的频率间隔依次扫描所述频率范围内的频率；
    电压获取单元，被配置为在每次进行扫描时，获取当前被扫描的频率下所述LLC变换器的输入电压Vin和输出电压Vo；
    比较单元，被配置为在每次进行扫描时通过将所述电压获取单元获取的所述LLC变换器的输入电压Vin和所述LLC变换器的变压器匝比N的比值与所述电压获取单元获取的所述LLC变换器的输出电压进行比较，并获取电压差值V＝|Vin/N-Vo|；以及
    谐振频率确定单元，被配置为当所述电压差值V＝|Vin/N-Vo|大于或等于预设阈值时，判定当前被扫描的频率为所述LLC变换器的谐振频率，并控制所述LLC变换器不再继续对所述扫频范围内的频率进 行扫描。
  10. 根据权利要求9所述的检测LLC变换器谐振频率的设备，其中，所述谐振参数包括标称谐振频率及谐振频率偏差。
  11. 根据权利要求10所述的检测LLC变换器谐振频率的设备，其中，所述频率生成单元通过所述LLC变换器的谐振电感偏差及所述LLC变换器的谐振电容偏差共同决定所述谐振频率偏差。
  12. 根据权利要求9所述的检测LLC变换器谐振频率的设备，其中，所述频率生成单元根据所述扫频范围及所述谐振频率的检测精度来设置所述预设的频率间隔。
  13. 根据权利要求9所述的检测LLC变换器谐振频率的设备，其中，所述谐振频率确定单元根据所述谐振频率的检测精度来设置所述预设阀值。
  14. 根据权利要求9所述的检测LLC变换器谐振频率的设备，所述频率生成单元还被配置为将所述LLC变换器的负载设为使得所述LLC变换器的输出电流在额定输出电流的20％以下的负载。
  15. 根据权利要求14所述的检测LLC变换器谐振频率的设备，所述频率生成单元还被配置为从所述扫频范围内的最高频率开始，按所述预设的频率间隔向下递减，依次扫描所述扫频范围内的频率。
  16. 根据权利要求15所述的检测LLC变换器谐振频率的设备，所述频率生成单元还被配置为将所述LLC变换器的当前工作频率设定为当前被扫描的频率，以及
    所述电压获取单元还被配置为通过采集记录所述LLC变换器在所述当前工作频率下所对应的输入电压Vin和输出电压Vo来获取当 前被扫描的频率下所述LLC变换器的输入电压Vin和输出电压Vo。
  17. 一种检测LLC变换器谐振频率的设备，包括存储器和处理器，在所述存储器上存储有计算机程序，所述计算机程序被所述处理器执行时，所述处理器执行根据权利要求1至8中任一项所述的检测LLC变换器谐振频率的方法。
  18. 一种计算机可读存储介质，其上存储有一个或者多个程序，所述一个或者多个程序被一个或者多个处理器执行时，所述一个或者多个处理器执行根据权利要求1至8中任一项所述的检测LLC变换器谐振频率的方法。
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