LC filter switching power supply and its resonant frequency adaptive adjustment method

Abstract

This invention discloses an LC filter switching power supply, characterized by comprising: a noise sensor, a microcontroller unit, and an LC filter, wherein the LC filter includes a variable inductor and a variable capacitor; the noise sensor is used to monitor at least the noise spectrum of the power supply output and feed the noise spectrum back to the microcontroller unit; the microcontroller unit is used to adjust the variable capacitor and the variable inductor according to the noise spectrum to adjust the resonant frequency of the LC filter; the LC filter operates according to the adjusted resonant frequency. This invention achieves stable noise suppression performance of the switching power supply under various operating environments by setting an LC filter with an adjustable resonant frequency, and ensuring that the adjustment of the LC filter's resonant frequency matches the real-time acquired noise spectrum.

Description

Technical Field

[0001] The invention relates to an LC filter switching power supply and a method for adaptively adjusting the resonance frequency thereof. Background Art

[0002] In the existing switching power supply circuit design process, LC filters are usually used in application scenarios that need to suppress high-frequency noise. LC filters have a good suppression effect on high-frequency noise, but the suppression effect on low-frequency noise is not very ideal. However, with the continuous improvement of people's requirements for the performance of electronic equipment, the market has further requirements for the stability of power supply and noise suppression ability of electronic equipment. Traditional LC filters can no longer meet the requirements of newly manufactured electronic products for as little noise as possible. Therefore, in power supply design, there is an urgent need for an LC filter switching power supply that can adapt to a variety of working scenarios. Summary of the invention

[0003] In view of the above problems, the present invention is an LC filter switching power supply capable of adaptively adjusting the resonant frequency according to different noise conditions.

[0004] In a first aspect, the present invention provides an LC filter switching power supply, comprising: a noise sensor, a micro control unit and an LC filter, wherein the LC filter comprises a variable inductor and a variable capacitor; the noise sensor is used to at least monitor the noise spectrum output by the power supply, and feed back the noise spectrum to the micro control unit; the micro control unit is used to adjust the variable capacitor and the variable inductor according to the noise spectrum to adjust the resonant frequency of the LC filter; the LC filter operates according to the adjusted resonant frequency.

[0005] In some embodiments, the variable inductor is a magnetic saturation capacitor controlled by a control current, and the variable capacitor is a capacitor diode controlled by a reverse bias voltage; the microcontroller unit adjusts the variable capacitor and the variable inductor according to the noise spectrum, including: the microcontroller unit adjusts the control current of the magnetic saturation capacitor and the reverse bias voltage of the capacitor diode according to the noise spectrum.

[0006] In some embodiments, the micro control unit is further used to convert the noise spectrum from a time series signal into a frequency domain signal, and identify noise components from the frequency domain signal.

[0007] In some embodiments, the noise sensor is an analog-to-digital converter ADC, and the analog-to-digital converter ADC samples the output signal of the power supply, and the sampling rate is a multiple of the highest frequency of the noise spectrum signal to be collected.

[0008] In some embodiments, the microcontroller is used to adjust the variable capacitance and the variable inductance according to a noise spectrum, including: selecting at least one target frequency from the noise spectrum as a target resonant frequency; calculating a target variable capacitance and a target variable inductance according to the target resonant frequency; and determining a control current of the magnetic saturation capacitor and a reverse bias voltage of the capacitor diode according to the target variable capacitance and the target variable inductance.

[0009] In some embodiments, the microcontroller is further used to determine the type of noise spectrum. If the noise spectrum is broadband noise, the noise spectrum is divided into multiple sub-bands. There are multiple LC filters, and the multiple LC filters are connected in parallel. The microcontroller calculates the target variable capacitance and target variable inductance corresponding to each sub-band, and determines the LC filter corresponding to each sub-band. The microcontroller controls the LC filter corresponding to each sub-band to achieve the target variable capacitance and target variable inductance of the corresponding sub-band.

[0010] In some embodiments, if the noise spectrum is periodic noise, the selecting at least one target frequency from the noise spectrum as the target resonant frequency is: the microcontroller determines the target resonant frequency corresponding to the periodic noise according to the periodic characteristics of the periodic noise or the historical data.

[0011] In some embodiments, if the noise spectrum is random noise, selecting at least one target frequency from the noise spectrum as the target resonant frequency is: presetting a noise threshold, and when the detected random noise reaches the noise threshold, selecting at least one target frequency from the noise spectrum as the target resonant frequency.

[0012] In some embodiments, a closed-loop feedback control circuit is further included, and a voltage and current acquisition module is provided at the output end of the LC filter. The closed-loop feedback circuit compares the control current and reverse bias voltage acquired by the voltage and current acquisition module with the control current of the magnetic saturation capacitor and the reverse bias voltage of the capacitor diode determined according to the target variable capacitance and the target variable inductance. If there is a deviation, the control current and the reverse bias voltage are further adjusted.

[0013] In a second aspect, a method for adaptively adjusting the resonant frequency of an LC filter includes: monitoring a noise spectrum output by a power supply; calculating a target value of a variable capacitor and a target value of a variable inductor of the LC filter according to the noise spectrum; determining a target control current of a magnetic saturation capacitor and a target reverse bias voltage of a capacitor diode according to the target value of the variable capacitor and the target value of the variable inductor, wherein the variable inductor is a magnetic saturation capacitor controlled by a control current, and the variable capacitor is a capacitor diode controlled by a reverse bias voltage; controlling the control current of the LC filter to be a target control current, and the reverse bias voltage to be a target reverse bias voltage.

[0014] In the technical solution of the embodiment of the present invention, an LC filter with adjustable resonant frequency is provided, and the adjustment of the resonant frequency of the LC filter can be matched with the noise spectrum acquired in real time, so that the switching power supply can have stable noise suppression performance in various working environments.

[0015] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0017] Figure 1 It is a schematic diagram of the structure of the LC filter switching power supply in some embodiments;

[0018] Figure 2 FIG. 4 is a flow chart of a method for adaptively adjusting the resonant frequency in some embodiments. DETAILED DESCRIPTION

[0019] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which the present invention belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention; the terms "including" and "having" in the specification and claims of the present invention and the above-mentioned drawings and any variations thereof are intended to cover non-exclusive inclusions.

[0021] In the description of the embodiments of the present invention, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present invention, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0022] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive of other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments. In the description of the embodiments of the present invention, the term "multiple" refers to more than two (including two)

[0023] like Figure 1 As shown, the present invention provides an LC filter 30 switching power supply, comprising: a noise sensor 10, a microcontroller 20 and an LC filter 30, wherein the LC filter 30 comprises a variable inductor and a variable capacitor; the noise sensor 10 is arranged at the output end of the switching power supply, and is used to at least monitor the noise spectrum of the power supply output, and feed back the noise spectrum to the microcontroller 20; the microcontroller 20 is used to adjust the variable capacitor and the variable inductor according to the noise spectrum, so as to adjust the resonant frequency of the LC filter 30; the LC filter 30 works according to the adjusted resonant frequency to effectively suppress the noise of the power supply output, thereby enabling the switching power supply to output stably.

[0024] In this embodiment, an adjustable LC filter is provided in the switching power supply, and a noise sensor and a microcontroller unit are provided. The microcontroller unit can adaptively adjust the capacitance and inductance of the LC filter according to the noise signal detected in real time, so that the adjusted LC filter can effectively suppress the current noise. Through the design of this embodiment, no matter how the noise output by the power supply changes, a good noise suppression effect can be achieved.

[0025] It should be noted that if Figure 1 As shown, the switching power supply also includes input and output, PWM modulator, switching elements, etc.

[0026] In some embodiments, continuing as Figure 1 As shown, the variable inductor of the LC filter is a magnetic saturation capacitor controlled by a control current, and the variable capacitor of the LC filter is a capacitor diode controlled by a reverse bias voltage; the microcontroller 20 adjusts the variable capacitor and the variable inductor according to the noise spectrum, including: the microcontroller 20 adjusts the control current of the magnetic saturation capacitor and the reverse bias voltage of the capacitor diode according to the noise spectrum.

[0027] In some embodiments, the microcontroller 20 is further configured to convert the noise spectrum from a time series signal into a frequency domain signal, and identify noise components from the frequency domain signal.

[0028] In some embodiments, the noise sensor 10 is an analog-to-digital converter ADC, which samples the output signal of the power supply, and the sampling rate is a multiple of the highest frequency of the noise spectrum signal to be collected.

[0029] Specifically, in order to achieve the purpose of adaptively adjusting the resonant frequency of the LC filter, the present invention uses a microcontroller with a high-precision analog-to-digital converter (ADC) to detect and analyze the noise spectrum of the power supply output in real time, and converts the time domain signal into a frequency domain signal through a fast Fourier transform algorithm (FFT), so as to identify the main noise components and dynamically adjust the LC filter parameters according to the identified noise components.

[0030] The analog-to-digital converter ADC is configured to sample the output signal of the power supply. During the conversion between analog and digital signals, according to the Nyquist theorem (fs.max>2fmax), the sampling rate will be set between 2.56 and 4 times the highest frequency of the target signal, so that the expected noise frequency band can be fully covered. In order to store the collected data points, a circular buffer will be set up inside the system to store the collected data points.

[0031] In some embodiments, the microcontroller 20 is used to adjust the variable capacitance and the variable inductance according to the noise spectrum, including: selecting at least one target frequency from the noise spectrum as a target resonant frequency; calculating a target variable capacitance and a target variable inductance according to the target resonant frequency; and determining a control current of the magnetic saturation capacitor and a reverse bias voltage of the capacitor diode according to the target variable capacitance and the target variable inductance.

[0032] Specifically, the microcontroller 20 selects one or more frequencies to be suppressed as the target resonant frequency according to the noise spectrum obtained by the above analysis, and calculates the required values ​​of the inductance L and the capacitance C according to the target frequency. Then, the current of the magnetic saturation inductor and the reverse bias voltage of the capacitor diode are set according to the calculated L and C values, so as to achieve the effect of dynamically adjusting the resonant frequency of the LC filter to match the noise scenario of the current circuit, thereby achieving the purpose of automatically adapting the LC filter according to the application scenario.

[0033] In some embodiments, the microcontroller 20 is also used to determine the type of noise spectrum. If the noise spectrum is broadband noise, the noise spectrum is divided into multiple sub-bands. There are multiple LC filters 30, and the multiple LC filters 30 are connected in parallel. The microcontroller 20 calculates the target variable capacitance and target variable inductance corresponding to each sub-band, and determines the LC filter 30 corresponding to each sub-band. The microcontroller 20 controls the LC filter 30 corresponding to each sub-band to achieve the target variable capacitance and target variable inductance of the corresponding sub-band.

[0034] In some embodiments, if the noise spectrum is periodic noise, the selecting at least one target frequency from the noise spectrum as the target resonant frequency is: the microcontroller 20 determines the target resonant frequency corresponding to the periodic noise according to the periodic characteristics of the periodic noise or the historical data.

[0035] In some embodiments, if the noise spectrum is random noise, selecting at least one target frequency from the noise spectrum as the target resonant frequency is: presetting a noise threshold, and when the detected random noise reaches the noise threshold, selecting at least one target frequency from the noise spectrum as the target resonant frequency.

[0036] Specifically, for broadband noise, since it covers a wide frequency range, it will affect almost all parts of the circuit and cause signal distortion or data transmission errors. Therefore, the algorithm design needs to identify multiple major noise peaks. It divides the entire spectrum into several sub-bands, and performs independent known noise processing on each of the divided sub-bands, so that the noise in each frequency band can be accurately controlled. At the hardware level, the circuit will also use multiple LC filters to work in parallel, and push the divided sub-bands to each LC filter at the hardware level. In this way, the dual collaboration of software and hardware can improve the broadband noise suppression effect without increasing the complexity of the system structure.

[0037] For narrowband noise, this kind of noise is generally concentrated on a certain frequency or a narrow frequency band. These noises are usually generated by a certain component in the circuit (such as motor harmonics, carrier leakage of communication system, etc.). Although its spectrum is very narrow, the energy it carries is very huge, or the intensity is very high. If this frequency overlaps with the operating frequency of the system, the system will be seriously disturbed and unable to work. According to the frequency concentration characteristics of narrowband noise, we can locate these frequencies in a targeted manner through algorithms and calculate the resonant frequency more accurately. At the same time, in this algorithm, it is necessary to simplify the response logic and speed up the system's response to this kind of noise that may suddenly disappear or appear so as to quickly adjust to the new resonant frequency. At the hardware level, the circuit will select an LC filter with a higher Q value (quality factor). Since a high Q value means that it will have a higher gain at a specific frequency, its response at other frequencies will also be correspondingly smaller.

[0038] For periodic noise, this kind of noise usually comes from voltage fluctuations in the power grid or mechanical vibrations, etc. It usually appears periodically and repeatedly, and usually appears as discrete peaks in the spectrum. Due to its periodicity and repeatability, it may resonate with the system and cause errors. Based on its repeatability and periodicity, the algorithm design can predict future noise conditions in advance through historical data. Logically, the corresponding resonant frequency will be calculated based on historical data. When it is recognized again, there is no need to repeat the calculation, and the original configuration can be called directly. At the hardware level, the resonant frequency of the LC filter will be synchronized with the operating frequency of the power supply first, so that the optimal suppression effect of periodic noise can be achieved.

[0039] For random noise, there is no obvious pattern in its appearance, and there is no clear origin for its appearance. Common phenomena are natural phenomena such as thermal noise and shot noise. Its existence will cause the signal-to-noise ratio (SNR) of the system to decrease, cause baseline drift in analog circuits, and increase the bit error rate in digital circuits. For this kind of noise without rules and characteristics, we design an algorithm based on statistical analysis to determine the main characteristics of the noise. It mainly sets an adaptive noise threshold in advance, and only when noise exceeding this threshold is detected will the adjustment of the LC filter be triggered to avoid excessive response to small and harmless noise changes. In order to better suppress it, the system will also use machine learning to learn the distribution pattern of noise from long-term data, and gradually optimize the adjustment strategy of the LC filter for the resonant frequency in daily use.

[0040] For transient noise, this is short and intense noise, usually lasting for a short time. It is somewhat similar to the narrowband noise mentioned above, but its performance in the frequency domain is more acute. Its generation may be caused by transient operations such as ESD and switching. If no intervention is made, it may cause hardware damage. For this reason, the algorithm structure of narrowband noise and periodic noise should be combined in the algorithm for this type of noise. First, the algorithm logic should be optimized to speed up the system response. Second, a certain resonant frequency value should be preset and called directly at the moment of detection. However, at the physical level, sometimes overshoot may occur due to excessive adjustment. Therefore, the preset parameters need to be combined with the actual hardware conditions to set safety limits to avoid being adjusted badly by the system without being damaged by noise. Generally speaking, the parameters called instantly will cause the system to deviate from the optimal working point, so it is also necessary to add recovery logic at the end of the algorithm. Once the transient noise disappears, the system should be adjusted back to normal working state.

[0041] In some embodiments, a closed-loop feedback control circuit is also included. A voltage and current acquisition module is provided at the output end of the LC filter 30. The closed-loop feedback circuit compares the control current and reverse bias voltage acquired by the voltage and current acquisition module with the control current of the magnetic saturation capacitor and the reverse bias voltage of the capacitor diode determined according to the target variable capacitance and the target variable inductance. If there is a deviation, the control current and the reverse bias voltage are further adjusted.

[0042] Specifically, the LC filter switching power supply also includes a closed-loop feedback control circuit. The purpose of this is to be able to compare the actual resonant frequency with the theoretical value. Here, a voltage and current probe will be installed at the output end of the LC filter to collect the output signal in real time. The error signal is output according to the comparison result to further adjust the control current and reverse bias voltage to ensure that the actual resonant frequency matches the frequency calculated by the algorithm or the error is small enough.

[0043] In some embodiments, Figure 1 As shown, the LC filter switching power supply also includes an environmental sensor, which timely detects the temperature, humidity and other parameters of the working environment of the power supply circuit through the integrated environmental sensor, so that the system can automatically adjust the values ​​of the resonant L and C according to the working state of the power supply to change the resonant frequency, optimize the system performance and suppress the noise effect.

[0044] In other embodiments, when controlling the LC filter, the microcontroller can also use machine learning technology to learn past operations, further automatically optimize parameter settings, and update the algorithm logic in a timely manner according to the evaluation results and learned knowledge to improve the efficiency of the algorithm.

[0045] In some embodiments, Figure 2As shown, a method for adaptively adjusting the resonant frequency of the LC filter 30 is also provided, comprising the following steps:

[0046] Step 100: Monitor the noise spectrum of the power supply output.

[0047] Step 200: Calculate a target value of the variable capacitance and a target value of the variable inductance of the LC filter 30 according to the noise spectrum.

[0048] Step 300: Determine a target control current of a magnetic saturation capacitor and a target reverse bias voltage of a capacitor diode according to a target value of a variable capacitor and a target value of a variable inductor, wherein the variable inductor is a magnetic saturation capacitor controlled by a control current, and the variable capacitor is a capacitor diode controlled by a reverse bias voltage.

[0049] Step 400: Control the control current of the LC filter 30 to be the target control current, and the reverse bias voltage to be the target reverse bias voltage.

[0050] In the technical solution of the embodiment of the present invention, an LC filter 30 with an adjustable resonant frequency is provided, and the adjustment of the resonant frequency of the LC filter 30 can be matched with the noise spectrum acquired in real time, so that the switching power supply can have stable noise suppression performance in various working environments.

[0051] The above steps are consistent with the processing capabilities of the microcontroller of the above-mentioned LC filter switching power supply, and will not be repeated here.

[0052] In the technical solution of the embodiment of the present invention, an LC filter with adjustable resonant frequency is provided, and the adjustment of the resonant frequency of the LC filter can be matched with the noise spectrum acquired in real time, so that the switching power supply can have stable noise suppression performance in various working environments.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. An LC filter switching power supply, characterized in that: include: A noise sensor, a micro control unit and an LC filter, wherein the LC filter includes a variable inductor and a variable capacitor; The noise sensor is used to at least monitor the noise spectrum output by the power supply and feed back the noise spectrum to the micro control unit; The micro control unit is used to adjust the variable capacitor and the variable inductor according to the noise spectrum to adjust the resonant frequency of the LC filter; The LC filter operates according to the adjusted resonant frequency.

2. The LC filter switching power supply according to claim 1, characterized in that: The variable inductor is a magnetic saturation capacitor controlled by a control current, and the variable capacitor is a capacitance diode controlled by a reverse bias voltage; The micro control unit adjusts the variable capacitor and the variable inductor according to the noise spectrum, including: The micro control unit adjusts the control current of the magnetic saturation capacitor and the reverse bias voltage of the capacitor diode according to the noise spectrum.

3. The LC filter switching power supply according to claim 2, characterized in that: The micro control unit is also used to convert the noise spectrum from a time series signal into a frequency domain signal, and identify noise components from the frequency domain signal.

4. The LC filter switching power supply according to claim 2, characterized in that: The noise sensor is an analog-to-digital converter ADC, and the analog-to-digital converter ADC samples the output signal of the power supply. The sampling rate is a multiple of the highest frequency of the noise spectrum signal to be collected.

5. The LC filter switching power supply according to claim 2, characterized in that: The microcontroller is used to adjust the variable capacitor and the variable inductor according to the noise spectrum, including: selecting at least one target frequency from the noise spectrum as a target resonant frequency; calculating a target variable capacitance and a target variable inductance according to the target resonant frequency; The control current of the magnetic saturation capacitor and the reverse bias voltage of the capacitance diode are determined according to the target variable capacitance and the target variable inductance.

6. The LC filter switching power supply according to claim 5, characterized in that: The microcontroller is further used to determine the type of the noise spectrum, and if the noise spectrum is broadband noise, divide the noise spectrum into a plurality of sub-frequency bands; There are multiple LC filters, and the multiple LC filters are connected in parallel. The microcontroller calculates the target variable capacitance and target variable inductance corresponding to each sub-frequency band, and determines the LC filter corresponding to each sub-frequency band. The microcontroller controls the LC filter corresponding to each sub-frequency band to achieve the target variable capacitance and target variable inductance of the corresponding sub-frequency band.

7. The LC filter switching power supply according to claim 5, characterized in that: If the noise spectrum is periodic noise, the selecting at least one target frequency from the noise spectrum as the target resonant frequency is: the microcontroller determines the target resonant frequency corresponding to the periodic noise according to the periodic characteristics of the periodic noise or the historical data.

8. The LC filter switching power supply according to claim 5, characterized in that: If the noise spectrum is random noise, selecting at least one target frequency from the noise spectrum as the target resonant frequency is: A noise threshold is preset, and when the detected random noise reaches the noise threshold, at least one target frequency is selected from the noise spectrum as a target resonant frequency.

9. The LC filter switching power supply according to claim 5, characterized in that: It also includes a closed-loop feedback control circuit, and a voltage and current acquisition module is arranged at the output end of the LC filter. The closed-loop feedback circuit compares the control current and reverse bias voltage acquired by the voltage and current acquisition module with the control current of the magnetic saturation capacitor and the reverse bias voltage of the capacitor diode determined according to the target variable capacitance and the target variable inductance. If there is a deviation, the control current and the reverse bias voltage are further adjusted.

10. A method for adaptively adjusting the resonant frequency of an LC filter, characterized in that: include: Monitor the noise spectrum of the power supply output; Calculate a target value of a variable capacitor and a target value of a variable inductor of an LC filter based on the noise spectrum; Determining a target control current of a magnetic saturation capacitor and a target reverse bias voltage of a capacitance diode according to a target value of a variable capacitance and a target value of a variable inductance, wherein the variable inductance is a magnetic saturation capacitor controlled by a control current, and the variable capacitance is a capacitance diode controlled by a reverse bias voltage; The control current of the LC filter is controlled to be a target control current, and the reverse bias voltage is controlled to be a target reverse bias voltage.

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