Capacitive current calculation method under special waveform voltage

Abstract

The invention discloses a capacitance current calculation method under special waveform voltage. The capacitance current calculation method comprises the steps of complex voltage waveform processing and capacitance current accurate calculation. Under the condition that the current source outputs a special waveform, the complex waveform voltage of the output end is processed by introducing high-frequency sampling and frequency domain analysis; according to the high-frequency sampling, a high-speed data acquisition technology is adopted, an output voltage waveform is obtained at a high sampling frequency, and it is ensured that transient change of voltage is captured; through high-frequency sampling and frequency domain analysis, the complex waveform voltage can be effectively processed, so that the capacitance current can be accurately calculated in constant current output control; after the voltage change rate is determined, the capacitance current is calculated through segmentation and differential calculation. Compared with the prior art, the calculation precision of the capacitance current can be effectively improved, the stability of the current source device in a constant current output mode is ensured especially under the condition of complex waveform voltage, and important support is provided for accurate control in power electronic application.

Description

Technical Field

[0001] This invention relates to a current source device, and more particularly to a method for calculating capacitor current under a special waveform voltage. Background Technology

[0002] In the field of power electronics, current source devices are widely used in applications requiring precise current control, such as LED drivers, motor control, and battery charging. In these applications, especially in constant current output mode (CC mode), the device needs to provide a stable output current. However, a capacitor is typically connected in parallel at the output, which can cause current fluctuations when the output voltage fluctuates or when using special waveform voltages, thus affecting load performance and device reliability.

[0003] Figure 1 This is the circuit structure at the output terminal of a current source in constant current output mode, where... The output current is the same as the load current. This is the current flowing through the capacitor at the output terminal. The current sampled at the output terminal during feedback control of the control circuit includes both capacitor current and load current. Accurate calculation of the capacitor current is crucial for achieving constant current control. It is known that the capacitor current is directly proportional to the rate of change of its voltage, specifically:

[0004]

[0005] in:

[0006] This is the capacitor current;

[0007] C is the capacitance value;

[0008] It is the output voltage that changes over time.

[0009] Furthermore, with increasing demands on the performance of current source devices, accurately calculating the current in the output capacitor under complex voltage waveforms has become a pressing issue. Precise calculation of the capacitor current not only helps improve the stability of the constant current output but also enhances the efficiency and reliability of the entire system.

[0010] Existing technology and its limitations:

[0011] Existing technologies mainly rely on simple capacitor current formulas. This method is used to calculate the capacitor current. It works well when the waveform is a simple sine wave or DC, but when faced with complex waveforms (such as pulse waves, sawtooth waves, etc.), the calculation results are often not accurate enough due to the discontinuity or nonlinearity of the voltage change rate.

[0012] In addition, traditional current sampling schemes often fail to consider the high-frequency characteristics of voltage waveforms, resulting in insufficient sampling frequency and an inability to capture the details of transient voltage changes, thus affecting the real-time calculation and feedback control of capacitor current. Furthermore, existing technologies are mostly designed for specific waveforms or applications, lacking versatility and adaptability to different special waveforms, making them ineffective in various complex environments. Most control algorithms rely heavily on the feedback of the total current, failing to separately eliminate capacitor current, which often leads to output current fluctuations in practical applications, thus affecting the normal operation of the equipment and load performance.

[0013] In summary, existing methods for calculating capacitor current under special waveform voltages have many shortcomings, necessitating a new method to accurately calculate capacitor current and improve the stability of constant current output. This provides the theoretical basis and technical support for the proposal of this invention.

[0014] In view of this, the present invention is hereby proposed. Summary of the Invention

[0015] The purpose of this invention is to provide a method for calculating capacitor current under special waveform voltages, so as to solve the above-mentioned technical problems existing in the prior art.

[0016] The objective of this invention is achieved through the following technical solution:

[0017] The present invention provides a method for calculating capacitor current under special waveform voltages, including processing complex voltage waveforms and accurately calculating capacitor current.

[0018] Step 1, the processing of the complex voltage waveform includes:

[0019] When the current source outputs a special waveform, the complex waveform voltage at the output terminal is processed by introducing high-frequency sampling and frequency domain analysis.

[0020] The high-frequency sampling employs high-speed data acquisition technology to acquire the output voltage waveform at a higher sampling frequency, ensuring that transient changes in voltage are captured. The sampling frequency is at least twice that of the highest frequency component of the signal.

[0021] Step two, the precise calculation of the capacitor current includes:

[0022] By using high-frequency sampling and frequency domain analysis, complex waveform voltages can be effectively processed, thereby accurately calculating the capacitor current in constant current output control; after determining the voltage change rate, the capacitor current is calculated by piecewise and differential calculations.

[0023] Compared with existing technologies, the capacitor current calculation method under special waveform voltage provided by this invention can effectively improve the calculation accuracy of capacitor current. Especially when facing complex waveform voltage, it ensures the stability of the current source device in constant current output mode, and provides important support for precise control in power electronics applications. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the circuit structure at the output terminal of a current source in constant current output mode.

[0025] Figure 2 This is a schematic diagram of the method for calculating capacitor current under special waveform voltage provided in an embodiment of the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them, and do not constitute a limitation on the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0027] First, the following explanations are provided for the terms that may be used in this article:

[0028] The term "and / or" means that either or both can be achieved simultaneously. For example, X and / or Y means that it includes both "X" or "Y" as well as the three cases of "X and Y".

[0029] The terms "comprising," "including," "containing," "having," or other similar semantic descriptions should be interpreted as non-exclusive inclusion. For example, including a technical feature element (such as raw material, component, ingredient, carrier, dosage form, material, size, part, component, mechanism, device, step, process, method, reaction conditions, processing conditions, parameter, algorithm, signal, data, product or article of manufacture, etc.) should be interpreted as including not only the expressly listed technical feature element, but also other technical feature elements that are not expressly listed and are well-known in the art.

[0030] The contents not described in detail in the embodiments of this invention are prior art known to those skilled in the art. Where specific conditions are not specified in the embodiments of this invention, they shall be performed according to conventional conditions in the art or conditions recommended by the manufacturer. Where the manufacturers of the reagents or instruments used in the embodiments of this invention are not specified, they are all conventional products that can be purchased commercially.

[0031] The present invention provides a method for calculating capacitor current under special waveform voltages, including processing complex voltage waveforms and accurately calculating capacitor current.

[0032] Step 1, the processing of the complex voltage waveform includes:

[0033] When the current source outputs a special waveform, the complex waveform voltage at the output terminal is processed by introducing high-frequency sampling and frequency domain analysis.

[0034] The high-frequency sampling employs high-speed data acquisition technology to acquire the output voltage waveform at a higher sampling frequency, ensuring that transient changes in voltage are captured. The sampling frequency is at least twice that of the highest frequency component of the signal.

[0035] Step two, the precise calculation of the capacitor current includes:

[0036] By using high-frequency sampling and frequency domain analysis, complex waveform voltages can be effectively processed, thereby accurately calculating the capacitor current in constant current output control; after determining the voltage change rate, the capacitor current is calculated by piecewise and differential calculations.

[0037] In step one:

[0038] The actual sampling frequency is set to ten times the highest frequency of the signal. for:

[0039]

[0040] in It is the highest frequency of the signal;

[0041] After determining the sampling frequency, a high-performance analog-to-digital converter is used to sample the output voltage signal in real time.

[0042] The frequency domain analysis utilizes wavelet transform and / or Fourier transform to decompose complex time-domain voltage signals into various frequency components, extracting high-frequency and low-frequency components to separate noise and interference in the voltage signal and enhance the accuracy of capacitor current calculation.

[0043] The frequency domain analysis includes:

[0044] Wavelet transform is used to process non-stationary signals to obtain a time-frequency representation of the signal, thereby extracting transient features. The wavelet transform formula is as follows:

[0045]

[0046] in, It is the result of wavelet transform;

[0047] This is the signal to be analyzed;

[0048] It is the mother wavelet;

[0049] a is the scale parameter representing frequency, and b is the translation parameter representing time position;

[0050] After wavelet transform, Fourier transform is then performed to convert the time-domain signal into a frequency-domain representation, which helps to identify the frequency components of the signal.

[0051] When processing voltage waveforms, the Fast Fourier Transform (FFT) algorithm is used, and the formula is as follows:

[0052]

[0053] Where N is the signal length and k is the frequency index;

[0054] After the signal undergoes FFT processing, its spectrum is obtained. The spectrum contains the amplitude and phase information of each frequency component. The formula for calculating the power spectrum is:

[0055]

[0056] Identifying the main frequency components from the power spectrum and extracting the frequency components that may affect the capacitor current facilitates the accuracy of subsequent segmented calculations.

[0057] Step two includes:

[0058] First, segmentation is performed. By segmenting the complex waveform and calculating the capacitive current in each time period, the response capability to rapidly changing voltage waveforms can be improved.

[0059] Specifically, the entire voltage signal Divided into N time periods , ,..., Then, by differentiating each segment and calculating the voltage signal of each segment, the capacitive current of each segment can be obtained:

[0060]

[0061] in This represents the voltage signal within the j-th segment;

[0062] Next, at the characteristic points of the voltage signal, the instantaneous rate of change of the voltage is calculated by differentiation, and then the capacitor current is obtained. Smoothing filtering is then used to improve the stability of the calculation results.

[0063] After establishing the relationship between the capacitor current IC and the rate of change of the voltage V(t) across the capacitor, a numerical differentiation method is used for calculation. Considering that the voltage signal is discrete in practical applications, a numerical differentiation method is used to calculate the rate of change of voltage, employing the central difference method formula:

[0064]

[0065] in It's the sampling interval; choose an appropriate one. It helps improve the accuracy of calculations;

[0066] Finally, the capacitive currents of all segments are combined to obtain an approximate value of the overall capacitive current.

[0067] In summary, the capacitor current calculation method under special waveform voltages in this invention can adapt to various complex waveform voltages, including pulse waves, sine waves, and triangular waves, thus expanding the application range of the current source device. Furthermore, by calculating the capacitor current in real time and eliminating interference, it achieves accurate sampling and control of the load current, effectively improving the stability of the constant current output. Because the influence of the capacitor current is eliminated, the output fluctuation of the current source device in constant current mode is also significantly reduced, improving the reliability of the device.

[0068] To more clearly demonstrate the technical solution and its effects provided by the present invention, the embodiments of the present invention will be described in detail below with reference to specific examples.

[0069] The principle of this invention is to accurately extract the capacitor current under specific waveform voltage conditions by real-time sampling and processing of the output voltage waveform and utilizing a capacitor current calculation model, thereby achieving precise control of the constant current output. Its core principle can be summarized in two aspects: processing complex voltage waveforms and accurately calculating the capacitor current.

[0070] 1) Processing complex voltage waveforms:

[0071] When a current source outputs a special waveform (such as a pulse or triangular wave), the output voltage change is no longer a smooth linear change, which poses a challenge to traditional capacitor current calculations. In this invention, the processing of complex waveform voltages is solved by introducing high-frequency sampling and frequency domain analysis.

[0072] High-frequency sampling employs high-speed data acquisition technology to obtain the output voltage waveform at a higher sampling frequency, ensuring the capture of transient voltage changes. According to the Nyquist theorem, to prevent aliasing, the sampling frequency must be at least twice the highest frequency component of the signal. Therefore, the actual sampling frequency should be set to ten times the highest frequency of the signal to ensure accurate capture of rapidly changing signal characteristics. Setting the sampling frequency... for:

[0073]

[0074] in This is the highest frequency of the signal. After determining the sampling frequency, a high-performance analog-to-digital converter (ADC) is used to sample the output voltage signal in real time. The data acquisition module should have fast response and high accuracy to ensure that the sampled waveform is as realistic as possible.

[0075] Frequency domain analysis utilizes methods such as wavelet transform or Fourier transform to decompose complex time-domain voltage signals into individual frequency components, extracting high-frequency and low-frequency components. This process effectively separates noise and interference from the voltage signal, enhancing the accuracy of capacitor current calculation. First, wavelet transform is used to process the non-stationary signal, obtaining a representation of the signal's time and frequency, thereby extracting transient features. The wavelet transform formula is:

[0076]

[0077] in, It is the result of wavelet transform;

[0078] This is the signal to be analyzed;

[0079] It is the mother wavelet;

[0080] 'a' is the scale parameter (representing frequency).

[0081] b is the translation parameter (representing the time position).

[0082] After wavelet transform, a Fourier transform is performed to convert the time-domain signal into a frequency-domain representation, which helps identify the frequency components of the signal. When processing voltage waveforms, the Fast Fourier Transform (FFT) algorithm can be used to improve computational efficiency. The Fourier transform formula is:

[0083]

[0084] The formula used for efficiently calculating the Discrete Fourier Transform is:

[0085]

[0086] Where N is the signal length and k is the frequency index. After the signal undergoes FFT processing, the signal's spectrum is obtained. The spectrum contains the amplitude and phase information of each frequency component. The formula for calculating the power spectrum is:

[0087]

[0088] Identifying the main frequency components from the power spectrum and extracting the frequency components that may affect the capacitor current facilitates the accuracy of subsequent segmented calculations.

[0089] 2) Precise calculation of capacitor current

[0090] High-frequency sampling and frequency domain analysis can effectively handle complex waveform voltages, thus enabling accurate calculation of capacitor current in constant current output control. Once the voltage change rate is determined, the capacitor current can be calculated using piecewise and differential calculations.

[0091] First, segmentation is performed. By segmenting the complex waveform and calculating the capacitive current in each time period, the response capability to rapidly changing voltage waveforms can be improved. This is because, in the case of complex waveforms, voltage changes may exhibit different characteristics in different time periods. To improve calculation accuracy, the entire voltage signal can be segmented... Divided into N time periods , ,..., Then, by differentiating each segment and calculating the voltage signal of each segment, the capacitive current of each segment can be obtained:

[0092]

[0093] in This represents the voltage signal within the j-th segment.

[0094] Next, at characteristic points of the voltage signal (such as the rising or falling edge of a pulse), the instantaneous rate of change of the voltage is calculated through differentiation, thereby deriving the capacitor current. To avoid the instability of numerical differentiation, a smoothing filter is used to improve the stability of the calculation results. After establishing the relationship between the rate of change of the capacitor current IC and the voltage V(t) across the capacitor, a numerical differentiation method is used for calculation. Considering that voltage signals are discrete in practical applications, the numerical differentiation method is usually used to calculate the rate of change of voltage. The central difference method formula can be used for calculation:

[0095]

[0096] in It is the sampling interval. Choose an appropriate one. This helps improve the accuracy of the calculation. Finally, the capacitive currents of all segments are combined to obtain an approximate value of the overall capacitive current.

[0097] Example 1

[0098] The specific process is as follows: Figure 2 As shown:

[0099] The implementation steps mainly include four parts: voltage acquisition, waveform processing, capacitor current calculation, and feedback control.

[0100] First, power on the device to enter constant current output mode, then start the voltage sampling module and data processing module. The next step is complex waveform processing. This step requires setting an appropriate sampling frequency based on the maximum waveform frequency at the output to ensure that detailed changes in the voltage signal are captured; and then processing the output voltage... Real-time sampling is performed to obtain discrete time series. The denoised voltage signal is then subjected to wavelet transform and fast Fourier transform (FFT) to obtain a spectrum. The main frequency components are identified from the spectrum, and frequency components that may affect the capacitor current are extracted to improve the accuracy of subsequent segmented calculations.

[0101] Next, we proceed to the precise calculation of the capacitor current. First, based on the results of the spectrum analysis and waveform characteristics, the voltage signal is divided into multiple time periods (such as rising edge, falling edge, and flat portion). For each time period, an appropriate window length is set. This allows for independent differential calculations within each segment. Numerical differential methods (such as the central difference method) are used to calculate the voltage change rate for each segment. Within each time period, the capacitor current is calculated based on the voltage change rate. Finally, the capacitor current time series for the entire sampling period is obtained by processing the data. .

[0102] The output current is obtained through a current sensor. This value includes the capacitor current. and load current The sum of the calculated capacitive currents. Remove from the total current to obtain the actual load current. Finally, the actual load current... With the acquired output current The system compares the current and processes the error through the controller, outputting a control signal to adjust the output current of the current source, ensuring that the load current is maintained at the set value.

[0103] The method of combining segmented calculation and differential calculation in this invention can effectively improve the calculation accuracy of capacitor current, especially when dealing with complex waveform voltages. This method ensures the stability of the current source device in constant current output mode, providing important support for precise control in power electronics applications.

[0104] Comparing the output current with the calculated capacitor current to accurately extract the actual load current is crucial for ensuring control precision. Simultaneously, by adjusting the current source output in real time, the load current is maintained at the set value.

[0105] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims. The information disclosed in the background section is intended only to enhance the understanding of the overall background technology of the present invention and should not be construed as an admission or implication in any way that such information constitutes prior art known to those skilled in the art.

Claims

1. A method for calculating capacitor current under a special waveform voltage, characterized in that, This includes processing complex voltage waveforms and accurately calculating capacitor current; Step 1, the processing of the complex voltage waveform includes: When the current source outputs a special waveform, the complex waveform voltage at the output terminal is processed by introducing high-frequency sampling and frequency domain analysis. The high-frequency sampling employs high-speed data acquisition technology to acquire the output voltage waveform at a higher sampling frequency, ensuring that transient changes in voltage are captured. The sampling frequency is at least twice that of the highest frequency component of the signal. Step two, the precise calculation of the capacitor current includes: By using high-frequency sampling and frequency domain analysis, complex waveform voltages can be effectively processed, thereby accurately calculating the capacitor current in constant current output control; after determining the voltage change rate, the capacitor current is calculated by piecewise and differential calculations.

2. The method for calculating capacitor current under special waveform voltage according to claim 1, characterized in that, In step one: The actual sampling frequency is set to ten times the highest frequency of the signal. for: in It is the highest frequency of the signal; After determining the sampling frequency, a high-performance analog-to-digital converter is used to sample the output voltage signal in real time. The frequency domain analysis utilizes wavelet transform and / or Fourier transform to decompose the complex time-domain voltage signal into various frequency components, extracting high-frequency and low-frequency components to separate noise and interference in the voltage signal and enhance the accuracy of capacitor current calculation.

3. The method for calculating capacitor current under special waveform voltage according to claim 2, characterized in that, The frequency domain analysis includes: Wavelet transform is used to process non-stationary signals to obtain a time-frequency representation of the signal, thereby extracting transient features. The wavelet transform formula is as follows: in, It is the result of wavelet transform; This is the signal to be analyzed; It is a mother wavelet; a is the scale parameter representing frequency, and b is the translation parameter representing time position; After wavelet transform, Fourier transform is then performed to convert the time-domain signal into a frequency-domain representation, which helps to identify the frequency components of the signal.

4. The method for calculating capacitor current under special waveform voltage according to claim 3, characterized in that, When processing voltage waveforms, the Fast Fourier Transform (FFT) algorithm is used, and the formula is as follows: Where N is the signal length and k is the frequency index; After the signal undergoes FFT processing, its spectrum is obtained. The spectrum contains the amplitude and phase information of each frequency component. The formula for calculating the power spectrum is: Identifying the main frequency components from the power spectrum and extracting the frequency components that may affect the capacitor current facilitates the accuracy of subsequent segmented calculations.

5. The method for calculating capacitive current under special waveform voltage according to any one of claims 1 to 4, characterized in that, Step two includes: First, segmentation is performed. By segmenting the complex waveform and calculating the capacitive current in each time period, the response capability to rapidly changing voltage waveforms can be improved. Specifically, the entire voltage signal Divided into N time periods , ,..., Then, by differentiating each segment and calculating the voltage signal of each segment, the capacitive current of each segment can be obtained: in This represents the voltage signal within the j-th segment; Next, at the characteristic points of the voltage signal, the instantaneous rate of change of the voltage is calculated by differentiation, and then the capacitor current is obtained. Smoothing filtering is then used to improve the stability of the calculation results. After establishing the relationship between the capacitor current IC and the rate of change of the voltage V(t) across the capacitor, a numerical differentiation method is used for calculation. Considering that the voltage signal is discrete in practical applications, a numerical differentiation method is used to calculate the rate of change of voltage, employing the central difference method formula: in It's the sampling interval; choose an appropriate one. It helps improve the accuracy of calculations; Finally, the capacitive currents of all segments are combined to obtain an approximate value of the overall capacitive current.

Images