Ripple voltage calculation device, computer program, ripple voltage calculation method and power supply device

Abstract

To provide a ripple voltage calculation device capable of calculating a ripple voltage highly functionally at low cost, a computer program, a ripple voltage calculation method and a power supply device.SOLUTION: A ripple voltage calculation device comprises: an AD conversion section by which a voltage waveform inputted via an input section is sampled in a predetermined sampling cycle and converted into a digital value; a generation section for generating a histogram indicating a degree of the digital value which is converted by the AD conversion section for a required period; a statistic calculation section for calculating a statistic of variations of a degree of the generated histogram; and a ripple voltage calculation section for calculating a ripple voltage for a required period on the basis of the calculated statistic.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a ripple voltage calculation device, a computer program, a ripple voltage calculation method, and a power supply device. [Background technology]

[0002] Some power supply devices, such as stabilized power supplies, are equipped with electrolytic capacitors on the output side of the power supply device to suppress ripple voltage in the output voltage. If the electrolytic capacitor deteriorates, such power supply devices will no longer be able to output the required voltage, so technology has been developed to detect the ripple voltage and determine the deterioration of the electrolytic capacitor.

[0003] To measure the ripple voltage, for example, a test measurement system using an oscilloscope as disclosed in Patent Document 1 is used. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-7959 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, a measuring instrument such as the oscilloscope disclosed in Patent Document 1 requires a high sampling and high resolution AD converter to realize a high performance sensing circuit, which increases the cost of the measuring instrument.

[0006] The present invention has been made in consideration of the above circumstances, and has an object to provide a ripple voltage calculation device, a computer program, a ripple voltage calculation method, and a power supply device that are highly functional and can calculate a ripple voltage at low cost. [Means for solving the problem]

[0007] The present application includes multiple means for solving the above-mentioned problems. As one example, a ripple voltage calculation device includes an AD conversion unit that samples a voltage waveform input through an input unit at a predetermined sampling period and converts it into a digital value, a generation unit that generates a histogram indicating the frequency of the digital values ​​converted by the AD conversion unit over a required period, a statistics calculation unit that calculates statistics of the fluctuation in the frequency of the generated histogram, and a ripple voltage calculation unit that calculates the ripple voltage for the required period based on the calculated statistics. Effect of the Invention

[0008] According to the present invention, a ripple voltage can be calculated with high functionality and at low cost. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating an example of a configuration of a ripple voltage calculation device according to an embodiment of the present invention. [Diagram 2] FIG. 4 is a diagram illustrating an example of a voltage waveform input to a microcomputer. [Diagram 3] FIG. 13 is a diagram illustrating an example of a histogram. [Figure 4] FIG. 13 is a diagram illustrating an example of a frequency difference between frequencies of a histogram. [Diagram 5] FIG. 13 is a diagram illustrating an example of a moving average of frequency differences. [Figure 6] FIG. 11 is a diagram illustrating an example of a method for calculating a ripple voltage. [Figure 7] FIG. 4 is a diagram showing an example of a procedure of a ripple voltage calculation process performed by the ripple voltage calculation device. [Figure 8] 1 is a diagram illustrating an example of the configuration of a power supply device including a ripple voltage calculation device of an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the present invention will be described with reference to the drawings showing the embodiments. FIG. 1 is a diagram showing an example of the configuration of a ripple voltage calculation device 50 of this embodiment. The ripple voltage calculation device 50 includes an input unit 51, a microcomputer 53, an output unit 59, and a storage unit 60. The input unit 51 includes an AC coupling circuit 52. The microcomputer 53 includes a CPU 54, a ROM 55, a RAM 56, an AD conversion unit 57, and an input / output interface 58. The storage unit 60 can be configured with, for example, a hard disk or a semiconductor memory, and can store a computer program (program product) 61 and required information. The ripple voltage calculation device 50 can be incorporated into a measuring instrument for measuring ripple voltage, or can be incorporated into a power supply device.

[0011] When a voltage waveform is input to the input unit 51, the DC component of the voltage waveform is removed by the AC coupling circuit 52, and only the AC component is extracted. The input unit 51 adds an offset voltage so that negative values ​​in the AC component become positive values. The input unit 51 amplifies the voltage waveform in which the offset voltage is superimposed on the AC component, and outputs it to the microcomputer 53. Here, the offset voltage can be set to an intermediate potential in the voltage range (0V to Vref) that can be measured by the AD conversion unit 57 of the microcomputer 53.

[0012] Fig. 2 is a diagram showing an example of a voltage waveform input to the microcomputer 53. As shown in Fig. 2, the voltage waveform input to the microcomputer 53 has an offset voltage and a ripple voltage (including a ripple noise component) superimposed on an AC component voltage. The AC coupling circuit 52 removes the DC component of the input voltage waveform.

[0013] The voltage waveform input to the microcomputer 53 is input to the AD conversion unit 57 via the input / output interface. The AD conversion unit 57 samples the input voltage waveform (analog value) at a predetermined sampling period and converts it into a digital value. The AD conversion unit 57 realizes the AD conversion function provided as a peripheral function of the microcomputer 53, and is composed of relatively inexpensive parts. Furthermore, by using the AD conversion unit 57, which is a peripheral function of the microcomputer 53, there is no need to configure a separate AD conversion circuit, and it can be realized at low cost.

[0014] The AD conversion unit 57 has, for example, a resolution of 12 bits or less and a sampling rate of 1 Msps or less. For example, an AD converter used in a high-performance sensing circuit such as an oscilloscope has a high resolution of, for example, 14 bits or more and is capable of high-speed sampling at a sampling rate of, for example, 25 Msps. The AD conversion unit 57 of this embodiment has a low resolution and a low sampling rate compared to a high-performance AD ​​converter, but is low cost.

[0015] The voltage waveform input to the AD conversion unit 57 contains AC components from which the DC components have been removed and ripple voltage, so that the resolution can be equivalently reduced by the absence of the DC components. Therefore, even if the resolution of the AD conversion unit 57 is low, it is possible to convert the voltage waveform (analog value) into a digital value.

[0016] The CPU 54 can execute a computer program 61 loaded in the RAM 56. The processing by the CPU 54 is also processing by the computer program 61.

[0017] The CPU 54 executes the function of a generating unit. The CPU 54 generates a histogram showing the frequency of the digital values ​​converted by the AD conversion unit 57 over a required period. The required period can be a period during which the number of samples of the converted digital values ​​is equal to or greater than a predetermined value. The predetermined value can be, for example, 3000, 4000, 5000, etc., but is not limited thereto. The predetermined value may be determined according to the sampling rate of the AD conversion unit 57, and may be a number of digital values ​​that allows statistical calculation. In other words, according to this embodiment, the ripple waveform of the input voltage waveform is roughly sampled, but by collecting digital values ​​over a required time to compensate for the rough sampling, it is possible to obtain a number of samples equivalent to that obtained by high-speed sampling within a short period by a high-performance, high-resolution AD converter used in an oscilloscope, etc.

[0018] Fig. 3 is a diagram showing an example of a histogram. The horizontal axis indicates each range obtained by dividing the range from the minimum value to the maximum value of the digital values ​​converted by the AD conversion unit 57 into required ranges, and the vertical axis indicates the frequency (number) of digital values ​​belonging to each range. Note that the horizontal axis may use another index instead of the digital value. The histogram shown in Fig. 3 shows the distribution of digital values ​​sampled over a required period.

[0019] The CPU 54 executes the function of a statistics calculation unit. The CPU 54 calculates the statistics of the fluctuation of the frequency of the generated histogram. More specifically, the CPU 54 calculates the frequency difference between the frequencies of adjacent digital values ​​in the histogram as the fluctuation, and calculates the moving average of the calculated frequency difference as the statistics.

[0020] Fig. 4 is a diagram showing an example of the frequency difference of the frequencies of the histogram. The frequency difference can be calculated as the difference between the frequency of the digital values ​​of a certain division and the frequency of the digital values ​​of the division immediately to the right of the certain division. Fig. 4 plots the frequency difference calculated for all divisions of the histogram.

[0021] FIG. 5 is a diagram showing an example of the moving average of the frequency difference. The moving average of the frequency difference of each division of the digital value is the average value of the frequency difference of the division in a certain section including the division. The moving average may be any of the following: a median moving average using the average value of the frequency difference between each division and the divisions before and after it, a backward moving average using the average value of each division and the divisions before it, and a forward moving average using the average value of each division and the divisions after it. By using the moving average, the value of the frequency difference can be smoothed.

[0022] The CPU 54 executes the function of a ripple voltage calculation unit. The CPU 54 calculates the ripple voltage for the required period based on the calculated statistics (the moving average of the frequency difference). More specifically, the CPU 54 identifies the minimum digital value and the maximum digital value at which the moving average of the frequency difference exceeds a predetermined threshold value among the digital values ​​of the histogram, and calculates the difference between the identified maximum digital value and minimum digital value as the ripple voltage for the required period.

[0023] FIG. 6 is a diagram showing an example of a method for calculating ripple voltage. The horizontal axis indicates digital values ​​(digital values ​​of each division), and the vertical axis indicates the moving average of frequency differences. As shown in FIG. 6, thresholds (positive and negative thresholds) for the moving average are set, and the digital value at which the moving average of frequency differences first exceeds the threshold (range of positive and negative thresholds) from the smaller digital value is identified as the minimum digital value, and the moving average is further searched for toward the larger digital value, and the digital value at which it finally exceeds the threshold (range of positive and negative thresholds) is identified as the maximum digital value. The ripple voltage for the required period can be calculated by subtracting the minimum digital value from the maximum digital value.

[0024] The output unit 59 outputs the calculated ripple voltage to the outside.

[0025] 7 is a diagram showing an example of the procedure of the ripple voltage calculation process by the ripple voltage calculation device 50. For convenience, the following description will be given assuming that the main processing is the CPU 54. The CPU 54 samples the input voltage waveform at a predetermined sampling period and converts it into a digital value (S11), and determines whether or not the conversion has been performed for a required period (S12). If the conversion has not been performed for the predetermined period (NO in S12), the CPU 54 performs the processes from step S11 onwards.

[0026] If the conversion has been performed over a predetermined period (YES in S12), the CPU 54 generates a histogram showing the frequency of the converted digital values ​​(S13), and calculates the frequency difference between the frequencies of adjacent digital values ​​in the generated histogram (S14). The CPU 54 calculates a moving average of the frequency difference (S15).

[0027] The CPU 54 identifies the minimum and maximum digital values ​​at which the moving average exceeds a predetermined threshold (S16), and calculates the ripple voltage for the required period based on the maximum and minimum digital values ​​(S17). The CPU 54 determines whether or not to end the process (S18), and if not (NO in S18), performs the process from step S11 onwards, and if to end the process (YES in S18), ends the process.

[0028] According to the ripple voltage calculation device 50 of this embodiment, it is possible to measure the ripple voltage with the same accuracy as a high-resolution AD converter.

[0029] As described above, according to this embodiment, by accumulating digital values ​​converted by the relatively low-cost, low-resolution AD conversion unit 57 for a required period of time that allows statistical processing, it is possible to calculate the ripple voltage with the same accuracy as a high-resolution AD converter, and also to calculate the ripple voltage with high functionality and at low cost.

[0030] FIG. 8 is a diagram showing an example of the configuration of a power supply device 100 including a ripple voltage calculation device 50 of this embodiment. The power supply device 100 includes, for example, a rectifier circuit 10, a DC / DC converter 20, a filter unit 30 having an electrolytic capacitor and a filter circuit, a control unit 40, and a ripple voltage calculation device 50. The ripple voltage calculation device 50 acquires a voltage waveform at an output end of the power supply device 100 to calculate a ripple voltage, and outputs the calculated ripple voltage to the control unit 40. The control unit 40 determines a deterioration state of the filter unit 30 (electrolytic capacitor) according to the ripple voltage input from the ripple voltage calculation device 50. The control unit 40 may output a warning or stop the operation of the power supply device 100 according to the deterioration state. Note that the configuration of the power supply device 100 is an example, and is not limited to the configuration of FIG. 8. In addition, when the electrolytic capacitor is used in a place other than the filter unit 30, the ripple voltage calculation device 50 may acquire a voltage waveform of the place where the electrolytic capacitor is used according to the place where the electrolytic capacitor is used.

[0031] (Supplementary Note 1) The ripple voltage calculation device includes an AD conversion unit that samples a voltage waveform input through an input unit at a predetermined sampling period and converts it into a digital value, a generation unit that generates a histogram indicating the frequency of the digital values ​​converted by the AD conversion unit over a required period, a statistics calculation unit that calculates statistics of the fluctuation in the frequency of the generated histogram, and a ripple voltage calculation unit that calculates the ripple voltage for the required period based on the calculated statistics.

[0032] (Supplementary Note 2) In the ripple voltage calculation device according to Supplementary Note 1, the statistics calculation unit calculates a frequency difference between frequencies of adjacent digital values ​​in the histogram as the fluctuation, and calculates a moving average of the calculated frequency difference as the statistics.

[0033] (Supplementary Note 3) In the ripple voltage calculation device according to Supplementary Note 1 or Supplementary Note 2, the ripple voltage calculation unit identifies a minimum digital value and a maximum digital value among the digital values ​​of the histogram at which the statistical amount exceeds a predetermined threshold, and calculates a difference between the identified maximum digital value and minimum digital value as the ripple voltage.

[0034] (Supplementary Note 4) In the ripple voltage calculation device according to any one of Supplementary Note 1 to Supplementary Note 3, the input section has an AC coupling circuit that removes DC components.

[0035] (Supplementary Note 5) In the ripple voltage calculation device according to any one of Supplementary Note 1 to Supplementary Note 4, the AD conversion unit has a resolution of 12 bits or less and a sampling rate of 1 Msps or less.

[0036] (Supplementary Note 6) The computer program causes a computer to execute the following processes: generate a histogram indicating the frequency of digital values ​​obtained by sampling and converting a voltage waveform input through an input unit at a predetermined sampling period over a required period; calculate statistics of the fluctuation in the frequency of the generated histogram; and calculate a ripple voltage for the required period based on the calculated statistics.

[0037] (Supplementary Note 7) A ripple voltage calculation method samples a voltage waveform input through an input unit at a predetermined sampling period and converts it into digital values, generates a histogram showing the frequency of the converted digital values ​​over a required period, calculates statistics of the fluctuation in frequency of the generated histogram, and calculates the ripple voltage for the required period based on the calculated statistics.

[0038] (Additional Note 8) The power supply device includes the above-mentioned ripple voltage calculation device, and the ripple voltage can be measured by the ripple voltage calculation device.

[0039] The matters described in each embodiment can be combined with each other. In addition, the independent claims and dependent claims described in the claims can be combined with each other in any and all combinations regardless of the citation format. Furthermore, the claims use a format in which a claim cites two or more other claims (multiple claim format), but this is not limited to this. A multiple claim (multi-multi claim) that cites at least one multiple claim may also be used. [Explanation of symbols]

[0040] 50 Ripple voltage calculation device 51 Input section 52 AC coupling circuit 53 Microcomputer 54 CPU 55 ROM 56 RAM 57 AD conversion section 58 Input / Output Interface 59 Output section 60 Storage section 61 Computer Programs

Claims

1. an AD conversion unit that samples the voltage waveform input through the input unit at a predetermined sampling period and converts it into a digital value; a generation unit that generates a histogram indicating a frequency of the digital values ​​converted by the AD conversion unit over a required period of time; a statistics calculation unit for calculating statistics of the fluctuation of the frequency of the generated histogram; a ripple voltage calculation unit that calculates a ripple voltage for the required period based on the calculated statistics; Equipped with Ripple voltage calculation device.

2. The statistics calculation unit calculating a difference in frequency between adjacent digital values ​​in the histogram as the variation; Calculating a moving average of the calculated frequency differences as the statistic. The ripple voltage calculation device according to claim 1 .

3. The ripple voltage calculation unit identifying a minimum digital value and a maximum digital value among the digital values ​​of the histogram where the statistical quantity exceeds a predetermined threshold; A difference between the identified maximum digital value and the identified minimum digital value is calculated as the ripple voltage. The ripple voltage calculation device according to claim 1 or 2.

4. The input unit includes: An AC coupling circuit is provided to remove DC components. The ripple voltage calculation device according to claim 1 or 2.

5. The AD conversion unit includes: The resolution is 12 bits or less and the sampling rate is 1 Msps or less. The ripple voltage calculation device according to claim 1 or 2.

6. A histogram is generated showing the frequency of digital values ​​obtained by sampling and converting the voltage waveform input through the input unit at a predetermined sampling period over a required period of time; Calculate the statistics of the frequency fluctuation of the generated histogram, calculating a ripple voltage for the required period based on the calculated statistics; A computer program that causes a computer to carry out processing.

7. A voltage waveform input through an input unit is sampled at a predetermined sampling period and converted into a digital value, generating a histogram showing the frequency of the converted digital values ​​over a required period of time; Calculate the statistics of the frequency fluctuation of the generated histogram, calculating a ripple voltage for the required period based on the calculated statistics; How to calculate ripple voltage.

8. 3. A power supply device comprising the ripple voltage calculation device according to claim 1, wherein a ripple voltage can be measured by the ripple voltage calculation device.

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