JP2011106856A - Electric characteristic measuring device and electric characteristic measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely calculate electric characteristics of an AC signal even if noise is superimposed on the AC signal. <P>SOLUTION: An electric characteristic measuring device includes a processing part 5 calculating electric characteristics of an AC signal S1 to be displayed by updating it for each display update period on the basis of a sampling value D1 of the AC signal S1 and a zero-cross detection part 3 detecting a zero-cross point of a predetermined type about the AC signal S1. The processing part 5 calculates the electric characteristics by a calculation system not using a window function on the basis of the sampling value D1 between detection time points when the zero-cross point is detected three times or more by the zero-cross detection part 3 within the display update period and when a comparison value obtained by comparing intervals between consecutive two detection time points with each other is within a predetermined allowable range, and calculates the electric characteristics by a calculation system using the window function on the basis of all the sampling values D1 in a predetermined acquisition duration within the display update period when the zero-cross point is detected three times or more and when the comparison value is outside the allowable range. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electrical characteristic measuring apparatus and an electrical characteristic measuring method for measuring electrical characteristics such as an effective value of an AC signal.

  As this type of electrical characteristic measuring apparatus, an AC signal measuring apparatus disclosed in Patent Document 1 below is known. This AC signal measuring device detects the same type of zero cross point (for example, one of the zero cross point of the rising zero cross point and the zero cross point of the falling zero point) for the AC signal every display update period of a predetermined length. When multiple zero-cross points are detected within the display update cycle, the zero-cross points are used as the start point and end point of the average value calculation period (that is, the start point and end point of the average value calculation period are synchronized with the zero cross point). Calculate the value.

  On the other hand, when a plurality of the same kind of zero cross points are not detected within the display update cycle, the start point and end point of the average value calculation period cannot be synchronized with the zero cross points. The average value of the AC signal is calculated using the end point as the start point and end point of the average value calculation period, that is, the entire display update cycle as the average value calculation period. In addition, since the average value when the start point and end point of the average value calculation period are not synchronized with the zero cross point may not be accurate, the AC signal measuring device outputs a warning signal indicating that fact. Display on the display.

  Therefore, in this AC signal measurement device, the user can know from the display on the display that the average value calculation period is not set appropriately, so the measurement cycle (display update cycle) can be lengthened, or the AC signal It is possible to check whether the waveform is appropriate. Moreover, since it can also be used after understanding that the average value calculation period is not set appropriately, it is possible to perform appropriate measurement in a short time.

JP 2004-233179 A (page 4-5, FIG. 2)

  However, the following problems exist in the electrical characteristic measuring apparatus. That is, in this electrical characteristic measuring apparatus, when a plurality of the same type of zero cross points are not detected within the display update cycle, the average value of the AC signal is calculated using the entire display update cycle as the average value calculation period, and the average value is displayed on the display unit. Since the calculated average value may not be accurate, a warning signal is output and this is indicated on the display. On the other hand, when multiple zero-cross points of the same type are detected within the display update cycle, the calculated average value is displayed on the display without outputting a warning signal, assuming that the average value of the calculated AC signal is accurate. ing. Here, for example, when noise is superimposed on the input signal, many points that are not originally zero-cross points in the input signal on which noise is not superimposed become zero-cross points, and the intervals between the zero-cross points are also extremely random. For this reason, when the average value of this input signal is calculated by synchronizing the start point and end point of the average value calculation period with the zero cross point, the average value is not accurate. Therefore, in this electrical characteristic measuring apparatus, even when the average value is calculated by synchronizing the start point and end point of the average value calculation period with the zero cross point, the average value may not be accurate. Inconvenience that the fact that is not accurate is not displayed.

  The present invention has been made in view of such a problem, and provides an electrical property measuring apparatus and an electrical property measuring method capable of accurately calculating electrical characteristics of an alternating current signal even when noise is superimposed on the alternating current signal. The main purpose is to do.

  In order to achieve the above object, an electrical characteristic measuring apparatus according to claim 1 is provided with a processing unit that calculates an electrical characteristic of an AC signal to be updated and displayed at each display update period based on a sampling value of the AC signal. A characteristic measuring apparatus, comprising: a zero-cross detection unit that detects a predetermined type of zero-cross point for the AC signal; and the processing unit sets the zero-cross point to 3 by the zero-cross detection unit within the display update period. A calculation method that does not use a window function based on the sampling value between the detection points when a comparison value that is detected more than once and compares each interval between two consecutive detection points is within a predetermined allowable range When the zero cross point is detected three times or more and the comparison value is out of the allowable range, the electric characteristic is calculated by the display update cycle. By the calculation method using a window function based on all of the sampled values of the definitive predefined acquisition period to calculate the electrical properties.

  The electrical property measuring apparatus according to claim 2 is the electrical property measuring apparatus according to claim 1, wherein the zero cross point is not detected three or more times by the zero cross detecting unit within the display update period. Then, the electrical characteristics are calculated by a calculation method using the window function based on all the sampling values in the acquisition period.

  The electrical characteristic measurement method according to claim 3 is an electrical characteristic measurement method for calculating an electrical characteristic of an alternating current signal to be updated and displayed at each display update period based on a sampling value of the alternating current signal. A pre-defined type of zero-cross point for a signal is detected, the zero-cross point is detected three or more times within the display update period, and a comparison value comparing each interval between two consecutive detection points is predetermined. If it is within the allowable range, the electrical characteristic is calculated by a calculation method that does not use a window function based on the sampling value between the detection points, the zero cross point is detected three times or more, and the comparison value is the allowable value When out of range, the calculation method using the window function based on all the sampling values of the predetermined acquisition period within the display update period To calculate the electrical characteristics.

  In addition, the electrical property measurement method according to claim 4 is the electrical property measurement method according to claim 3, wherein when the zero cross point is not detected three times or more within the display update period, all of the acquisition periods are detected. The electrical characteristic is calculated by a calculation method using a window function based on the sampling value.

  In the electrical characteristic measuring apparatus according to claim 1 and the electrical characteristic measuring method according to claim 3, the zero-cross point of a predetermined type is detected three times or more, and each interval between two consecutive detection points is compared. When the comparison value is out of the allowable range, the electrical characteristics are calculated based on all sampling values in a predetermined acquisition period within the display update cycle. For this reason, according to this electrical characteristic measuring apparatus and electrical characteristic measuring method, when a number of points that are not originally zero-crossing points become zero-crossing points due to the superimposition of noise on the AC signal, the zero-crossing caused by the noise is caused. It is possible to reliably prevent a situation in which an incorrect electrical characteristic is calculated based on a sampling value between points. In addition, by calculating the electrical characteristics by the calculation method using the window function, even if the sampling values at the beginning and end of the acquisition period are different from each other and discontinuous, for each sampling value of the acquisition period By multiplying by the window function, weighting is performed so that the sampling values at the beginning and the end smoothly converge to the value 0, and thereby the electrical characteristics can be accurately calculated. Therefore, according to this electrical characteristic measuring apparatus and electrical characteristic measuring method, even when noise is superimposed on an AC signal, the electrical characteristics of the AC signal can be accurately calculated. Further, according to the electrical characteristic measuring device and the electrical characteristic measuring method, the electrical characteristics are calculated based on a part of the sampling values in the acquisition period in order to calculate the electrical characteristics based on all the sampling values in the acquisition period. Compared to the configuration and method, the calculation accuracy of the electrical characteristics can be improved by the number of sampling values.

  Further, in this electrical characteristic measuring apparatus and electrical characteristic measuring method, a comparison value is obtained by detecting a predetermined type of zero-cross point three times or more in the display update period and comparing each interval between two consecutive detection points. Is within an allowable range defined in advance, the electrical characteristics are calculated by a calculation method that does not use a window function based on sampling values between detection points. For this reason, according to this electrical property measuring apparatus and electrical property measuring method, when calculating electrical properties of an alternating current signal in which noise is not superimposed and the zero cross point is detected in the same cycle as the fundamental cycle The most accurate calculation of electrical characteristics based on sampling values from the zero crossing point to the zero crossing point where the sampling values at the start and end are equal to each other, that is, the sampling values at the start and end are continuous. Can do. Moreover, according to this electrical property measuring apparatus and electrical property measuring method, electrical properties can be measured at a high speed by the amount not using the window function.

  Further, in the electrical characteristic measuring apparatus according to claim 2 and the electrical characteristic measuring method according to claim 4, when the zero-cross point is not detected three times or more within the display update period, it is based on all sampling values in the acquisition period. The electrical characteristics are calculated by a calculation method using a window function. Therefore, according to this electrical characteristic measuring apparatus and electrical characteristic measuring method, the zero cross point cannot be detected three times or more within the display update period (the detection time interval does not exist twice or more), and the AC signal has noise. Even when it is not possible to determine whether or not they are superimposed, the electrical characteristics can be accurately measured by a calculation method using a window function based on all sampling values in the acquisition period.

1 is a configuration diagram showing a configuration of an electrical characteristic measuring apparatus 1. FIG. 3 is a timing chart for explaining an outline of operation of the electrical characteristic measuring apparatus 1. 5 is a flowchart of an electrical characteristic calculation process 50. 3 is a first timing chart illustrating details of the operation of the electrical characteristic measuring apparatus 1. 6 is a second timing chart for explaining details of the operation of the electrical characteristic measuring apparatus 1.

  Hereinafter, embodiments of an electrical property measuring apparatus 1 and an electrical property measuring method will be described with reference to the accompanying drawings.

  Initially, the structure of the electrical property measuring apparatus 1 is demonstrated with reference to drawings.

  As shown in FIG. 1, the electrical characteristic measuring apparatus 1 includes an A / D conversion unit 2, a zero cross detection unit 3, a measurement unit 4, a processing unit 5, a storage unit 6, and a display unit 7, and the electrical characteristics of the AC signal S1. (In this example, as an example, effective value Vrms) can be measured.

  The A / D converter 2 inputs the AC signal S1 and samples the AC signal S1 with a sampling clock having a predetermined cycle (a cycle sufficiently short with respect to the cycle of the AC signal S1). The amplitude of S1 is converted into digital data (hereinafter also referred to as “sampling value”) D1 and output to the processing unit 5.

  As an example, the zero-cross detection unit 3 includes a comparator whose threshold is defined as zero volts, and is one of the predetermined types of zero-crossing points of the rising zero-crossing point and the falling zero-crossing point of the AC signal S1. A point (in this example, a rising zero cross point as an example) is detected, and a detection signal S2, which is a pulse signal, is output to the processing unit 5 as an example in synchronization with the detection timing of the zero cross point.

  The measuring unit 4 is composed of a timer IC or the like, repeatedly executes measurement of a predetermined display update cycle T1, and outputs an update signal S3 that is a pulse signal to the processing unit 5 as an example for each display update cycle T1. To do.

  The processing unit 5 is composed of a CPU or the like, inputs the detection signal S2 and the update signal S3 as interrupt signals, operates according to an operation program stored in the storage unit 6, and performs the above-described electric signal for the AC signal S1. The electric characteristic calculation process 50 (refer FIG. 3) which calculates a characteristic based on the sampling value D1 is performed.

  The storage unit 6 includes a semiconductor memory such as a ROM and a RAM. The storage unit 6 stores in advance an operation program that defines the operation of the processing unit 5 as described above. Further, the storage unit 6 functions as a work memory of the processing unit 5, and the zero cross point is detected by the sampling value D <b> 1 acquired by the processing unit 5 from the A / D conversion unit 2 and the zero cross detection unit 3 (detection signal S <b> 2). (For example, time data D2) and the effective value Vrms as the electrical characteristic calculated by the processing unit 5 in the electrical characteristic calculation process 50 are stored. The display unit 7 includes a display device such as an LCD (Liquid Crystal Display), and displays the effective value Vrms calculated by the processing unit 5.

  Next, a method for measuring the electrical characteristics of the AC signal S1 by the electrical characteristics measuring apparatus 1 and an electrical characteristics measuring method will be described with reference to the drawings.

  First, in the electrical characteristic measuring apparatus 1, in the operating state, the A / D converter 2 performs sampling on the AC signal S1, the zero cross detector 3 detects the zero cross point of the AC signal S1, and the measuring unit 4 The display update cycle T1 is measured. Therefore, the sampling value D1 is output from the A / D conversion unit 2 at the sampling clock cycle, the detection signal S2 is intermittently output from the zero cross detection unit 3, and the update signal S3 is output from the measurement unit 4 to the processing unit 5. It is output at the display update cycle T1.

  In this state, as shown in FIG. 2, the processing unit 5 performs the electrical operation shown in FIG. 3 when a predetermined time (tens of tenths of the display update period T1) has elapsed since the update signal S3 was input. The characteristic calculation process 50 is started.

  Specifically, the operation of the processing unit 5 in each electrical characteristic calculation process 50 will be described in detail with reference to FIGS.

  When the electrical characteristic calculation process 50 is started, the processing unit 5 starts the acquisition process of the sampling value D1 output from the A / D conversion unit 2 (step 51). Thereby, the acquisition period T2 (refer FIG. 4) which acquires the sampling value D1 is started. The processing unit 5 also starts storing the acquired sampling value D1 in the storage unit 6 together.

  After that, the processing unit 5 performs whether the detection signal S2 has been input (step 52) and whether the update signal S3 has been input (step 53) while performing the acquisition process and the storage process of the sampling value D1. Repeat detection. At this time, each time the detection signal S2 is input, the processing unit 5 inputs the detection signal S2 until the input of the update signal S3 (the end of the current display update cycle T1) (that is, the zero cross detection unit 3). And the time data D2 that can specify the time point when the zero cross point is detected (detection signal S2 is input) is stored in the storage unit 6 (step 54).

  Next, when the next update signal S3 is input during the execution of steps 52 to 54 (that is, when the display update cycle T1 has elapsed), the processing unit 5 ends the execution of steps 52 to 54. To do. Thereby, the acquisition period T2 for acquiring the sampling value D1 ends. Subsequently, the processing unit 5 determines the number of detections of the detection signal S2 within the acquisition period T2 (within the display update period T1 including the acquisition period T2) for the sampling value D1 up to this point (step 55).

  As a result of the determination, when the detection signal S2 is detected three times or more, the processing unit 5 reads the time data D2 stored in the storage unit 6, and the zero cross point is detected based on the time data D2. The detected time Pt is specified. Subsequently, the processing unit 5 detects the interval I between the two detection times Pt (most recent) (the interval I1 between the detection times Pt1 and Pt2, the interval I2 between the detection times Pt2 and Pt3, and the detection time Pt3 shown in FIG. 4). , Pt4 interval I3 and detection times Pt4, Pt5 interval I4) are calculated (step 56).

  Next, the processing unit 5 selects two of the calculated intervals I1 to I4, and calculates the ratio of the other interval I to the one interval I (an example of a comparison value comparing the intervals I) R. The ratio R is calculated for all combinations that select two of the intervals I1 to I4. Next, it is determined whether or not these ratios R are within a predetermined allowable range Rs (as an example, a range of 99% to 101%) (step 57). In this case, when the noise is not superimposed on the AC signal S1 (or the superimposed noise is slight) and the frequency does not fluctuate (or the frequency fluctuates slightly), it is shown in FIG. Thus, the cycle (basic cycle) of the AC signal S1 and the intervals I1 to I6 are substantially equal. For this reason, when the AC signal S1 is in such a state, each ratio R described above is within the allowable range Rs. At this time, the processing unit 5 determines that all of the ratios R are within the allowable range Rs, and subsequently, between the first detection time Pt1 and the last detection time Pt5 of the detection signal S2. All sampling values D1 are read (step 58).

  Next, the processing unit 5 determines the effective of the AC signal S1 based on the read sampling value D1 by, for example, a root mean square calculation method that does not use a window function (hereinafter also referred to as “normal calculation method that does not use a window function”). A value Vrms is calculated (step 59). Subsequently, the processing unit 5 displays the calculated electrical characteristics on the display unit 7 (step 60).

  For example, when the electric characteristic B is calculated as in the second electric characteristic calculation process 50 in FIG. 2, the display content (electric characteristic A in this example) displayed in the previous display update cycle T1 is used. The electrical characteristic B is displayed on the display unit 7. Thereby, the electrical characteristic calculation process 50 is completed. Next, after completion of the electrical characteristic calculation process 50, the processing unit 5 newly starts the electrical characteristic calculation process 50 when a predetermined time has elapsed since the next update signal S3 was input.

  In this case, the time required for the processing from step 55 to step 60 (the data processing time T3 shown in FIG. 4) is extremely short (for example, the display update cycle) compared to the display update cycle T1 (for example, about 120 ms). Since the processing unit 5 repeatedly executes the above processing, the electrical characteristics of the AC signal S1 calculated by the processing unit 5 are displayed on the display update cycle. It is displayed while being updated at T1.

  On the other hand, for example, as shown in FIG. 5, when noise is superimposed on the AC signal S1, the zero cross point may be detected at a time point that does not originally become the zero cross point (the zero cross point is detected at random). . In such a state, the interval I calculated in the above-described step 56 (interval I5 of detection times Pt6 and Pt7, interval I6 of detection times Pt7 and Pt8, interval I7 of detection times Pt8 and Pt9 shown in FIG. Since the interval I8 between Pt9 and Pt10, the interval I9 between the detection times Pt10 and Pt11, and the interval I10 between the detection times Pt11 and Pt12) fluctuate greatly, the ratio R may be outside the allowable range Rs. At this time, the processing unit 5 determines in step 57 described above that any or all of the ratios R are outside the allowable range Rs.

  Here, as shown in FIG. 5, the zero cross point is detected eight times by noise superposition on the AC signal S1, and the window function is based on the sampling value D1 from the first detection time Pt1 to the last detection time Pt12 at this time. Assuming that the electrical characteristics are calculated by a normal calculation method that does not use, even though only the sampling values D1 for about four periods are acquired from the detection time Pt6 to the detection time Pt12, 7 As a result of calculation assuming that the sampling values D1 for the period have been acquired, the calculated electrical characteristics become inaccurate. For this reason, in this electrical characteristic measuring apparatus 1, when the processing unit 5 determines in step 57 that any or all of the ratios R are not within the allowable range Rs, the last detection from the first detection time Pt1. Instead of reading the sampling value D1 until time Pt12, all the sampling values D1 within the acquisition period T2 are read (step 61), and the electrical characteristics are calculated.

  In this case, since it is extremely rare that the start and end of the acquisition period T2 coincide with the zero cross point (the sampling value D1 at the start and end becomes 0), in general, at the start and end of the acquisition period T2. The sampling values D1 are different from each other (a so-called phenomenon occurs in which the first and last sampling values D1 cut out in the acquisition period T2 are discontinuous). And the value of the electrical characteristic calculated by the calculation method that does not use the window function based on the sampling value D1 that is discontinuous due to the cutting is generally an inaccurate value. For this reason, when calculating the electrical characteristics based on all the sampling values D1 within the acquisition period T2, the processing unit 5 changes to a calculation method that does not use a window function, for example, a window derived from a Parseval relational expression. Calculation is performed by a calculation method using a function (step 62), and the calculated electrical characteristics are displayed on the display unit 7 (step 60).

  In this calculation method using the window function, each sampling value D1 in the acquisition period T2 is multiplied by the window function to perform weighting so that the sampling value D1 at the beginning and the end smoothly converges to the value 0. Thus, the electrical characteristics can be accurately calculated. As window functions used in this calculation method, various window functions such as Gaussian window, Hanning window (Han window), Hamming window, Blackman window, Kaiser window, Bartlett window, etc. can be used. As an example, the electrical characteristics are calculated by a calculation method using a Hanning window.

  For example, when the zero cross point is not detected three times or more, the processing unit 5 determines in step 55 that the number of detections of the detection signal S3 is less than three times, and then within the acquisition period T2. All sampling values D1 are read (step 61), and the electrical characteristics are calculated. In this case, as described above, the beginning and end of the sampling value D1 cut out in the acquisition period T2 are discontinuous, and the value of the electrical characteristic calculated by the calculation method that does not use the window function based on the sampling value D1. Is generally an inaccurate value. Therefore, even when the processing unit 5 determines that the number of detection times of the detection signal S3 is less than 3, the processing unit 5 accurately calculates the electrical characteristics by the calculation method using the window function described above (step 62), The calculated electrical characteristics are displayed on the display unit 7 (step 60).

  As described above, in this electrical property measuring apparatus 1 and electrical property measuring method, each interval I between two consecutive detection times Pt is detected three times or more of the zero cross point of a predetermined type within the display update period T1. When the ratio R between the two is outside the allowable range Rs, the electrical characteristics are calculated based on all the sampling values D1 in the acquisition period T2 within the display update cycle T1. For this reason, according to the electrical characteristic measuring apparatus 1 and the electrical characteristic measuring method, when many points that are not originally zero cross points due to the superimposition of noise on the AC signal S1 are zero cross points, they are caused by the noise. It is possible to reliably prevent a situation in which inaccurate electrical characteristics are calculated based on the sampling value D1 during the detection time Pt between the zero-cross points. Further, by calculating the electrical characteristics by the calculation method using the window function, each sampling value of the acquisition period T2 is different even when the sampling values D1 at the beginning and end of the acquisition period T2 are different from each other and discontinuous. By multiplying D1 by the window function, weighting is performed so that the sampling value D1 at the beginning and end smoothly converges to the value 0, and thereby the electrical characteristics can be accurately calculated. Therefore, according to this electrical property measuring apparatus 1 and electrical property measuring method, even when noise is superimposed on the alternating current signal S1, the electrical properties of the alternating current signal S1 can be accurately calculated. Further, according to the electrical characteristic measuring apparatus 1 and the electrical characteristic measuring method, since the electrical characteristics are calculated based on all the sampling values D1 in the acquisition period T2, based on a part of the sampling values D1 in the acquisition period T2. Compared with the configuration and method for calculating the electrical characteristics, the accuracy of calculating the electrical characteristics can be improved as the number of sampling values D1 is larger.

  Further, in this electrical property measuring apparatus 1 and electrical property measuring method, a zero-cross point of a predetermined type is detected three or more times within the display update period T1, and the intervals I between the two consecutive detection times Pt are detected. When the ratio R is within the allowable range Rs, the electrical characteristics are calculated by a normal calculation method that does not use a window function based on the sampling value D1 during the detection time Pt. For this reason, according to the electrical characteristic measuring apparatus 1 and the electrical characteristic measuring method, the electrical characteristic of the AC signal S1 is calculated such that noise is not superimposed and the zero cross point is detected in the same period as the basic period. In some cases, the sampling value D1 at the start and the end is equal to 0 (that is, the sampling value D1 at the start and the end is continuous), and the electrical characteristics are most determined based on the sampling value D1 from the zero cross point to the zero cross point. It can be calculated accurately. Further, according to the electrical property measuring apparatus 1 and the electrical property measuring method, electrical properties can be measured at a high speed by the amount not using the window function.

  Further, in the electrical characteristic measuring apparatus 1 and the electrical characteristic measuring method, when the zero cross point is not detected three times or more within the display update period T1, the window function is used based on all the sampling values D1 in the acquisition period T2. The electrical characteristics are calculated by the calculation method used. For this reason, according to the electrical characteristic measuring apparatus 1 and the electrical characteristic measuring method, the zero cross point cannot be detected three or more times within the display update period T1 (the interval I of the detection time Pt does not exist twice or more). Even when it is not possible to determine whether or not noise is superimposed on the signal S1, the electrical characteristics can be calculated by the calculation method using the window function based on all the sampling values D1 in the acquisition period T2. Electrical characteristics can be calculated accurately.

  Note that, as an example of a comparison value obtained by comparing the intervals I of two consecutive detection times Pt, a ratio R of the other interval I to the one interval I is calculated, and the ratio R is within the allowable range Rs. Although the configuration and method for determining whether or not are described above, a difference value between one interval I and the other interval I is calculated as the comparison value, and the difference value is within a predetermined allowable range. It is also possible to adopt a configuration and a method for determining whether or not, or calculate the ratio of the difference value with respect to one interval I or the other interval I, and whether or not this ratio is within a predetermined allowable range. It is also possible to employ a configuration and method for determining whether or not.

  Further, when the zero cross point is detected three times or more in the display update cycle T1 and the ratio R is within the allowable range Rs, all samplings from the first detection time Pt to the last detection time Pt of the detection signal S2 are performed. The example of calculating the electrical characteristics based on the value D1 has been described above (step 58 of the electrical characteristics calculation process 50), but it is not always necessary to use the sampling value D1 from the first detection time Pt to the last detection time Pt. In addition, the electrical characteristics can be calculated by a normal calculation method that does not use a window function based on the sampling value D1 between the arbitrarily selected detection times Pt. As an example, in FIG. 4, the sampling value D1 from the detection time Pt1 to the detection time Pt2, the sampling value D1 from the detection time Pt2 to the detection time Pt3, and the sampling from the detection time Pt1 to the detection time Pt3. A value D1 or the like can be used. Further, in FIG. 4, both the sampling value D1 between the detection time Pt1 and the detection time Pt2 and the sampling value D1 between the detection time Pt3 and the detection time Pt4 (that is, at two intervals I that are not continuous). A sampling value D1) can also be used. Further, the electrical characteristics are calculated by a normal calculation method that does not use a window function based on the sampling value D1 between the detection time Pt1 and the detection time Pt2 in FIG. 4, and between the detection time Pt3 and the detection time Pt4. It is also possible to employ a configuration and method in which the electrical characteristics are calculated by a normal calculation method that does not use a window function based on the sampling value D1 and the calculated values are averaged.

  In addition, the above-described electrical property measuring apparatus 1 employs a configuration including the A / D converter 2, but the electrical property measuring apparatus does not include the A / D converter, and the A outside the electrical property measuring apparatus. It is also possible to employ a configuration in which the / D conversion unit is arranged. In this configuration, the processing unit 5 directly inputs the sampling value D1 of the AC signal S1 from the outside. In this case, the zero-cross detection unit 3 is configured by, for example, a logic circuit, and the zero-cross detection unit 3 By determining the polarity while inputting the sampling value D1, it is configured to detect the zero cross point for the AC signal S1, or the processing unit 5 determines the polarity while inputting the sampling value D1. Thus, it is possible to adopt a configuration in which the zero-cross point for the AC signal S1 is directly detected, that is, a configuration that also functions as the zero-cross detection unit 3.

  Further, the example of calculating the effective value Vrms of the AC signal S1 as the electrical characteristics has been described above, but the present invention can also be applied when calculating other electrical characteristics (for example, an average value) of the AC signal S1.

DESCRIPTION OF SYMBOLS 1 Electrical property measuring device 3 Zero cross detection part 4 Measurement part 5 Processing part D1 Sampling value I Interval Pt Detection time R Ratio Rs Permissible range S1 AC signal S2 Detection signal S3 Update signal T1 Display update period T2 Acquisition period

Claims (4)

An electrical characteristic measuring apparatus including a processing unit that calculates an electrical characteristic of an AC signal to be updated and displayed at each display update cycle based on a sampling value of the AC signal,
A zero-cross detection unit for detecting a predetermined type of zero-cross point for the AC signal;
In the display update cycle, the processing unit detects the zero cross point three times or more by the zero cross detection unit, and a comparison value obtained by comparing each interval between two consecutive detection points is within a predetermined allowable range. In the case of calculating the electrical characteristics by a calculation method that does not use a window function based on the sampling value between the detection time points, when the zero cross point is detected three times or more and the comparison value is out of the allowable range, An electrical characteristic measuring apparatus that calculates the electrical characteristic by a calculation method using a window function based on all the sampling values in a predetermined acquisition period within the display update period.   The processing unit uses the window function based on all the sampling values of the acquisition period when the zero cross point is not detected three or more times by the zero cross detection unit within the display update period. The electrical property measuring apparatus according to claim 1, wherein the electrical property is calculated by: An electrical characteristic measurement method for calculating an electrical characteristic of an AC signal to be updated and displayed at each display update cycle based on a sampling value of the AC signal,
Detecting a zero-cross point of a predefined type for the AC signal;
When the comparison value obtained by detecting the zero cross point three times or more in the display update period and comparing each interval of two consecutive detection time points is within a predetermined allowable range, the sampling between the detection time points is performed. The electrical characteristic is calculated by a calculation method that does not use a window function based on the value, the zero-cross point is detected three times or more, and the comparison value is out of the allowable range, it is defined in advance within the display update period. An electrical property measurement method for calculating the electrical property by a calculation method using a window function based on all the sampling values in an acquisition period.   The electrical characteristic is calculated by a calculation method using a window function based on all the sampling values in the acquisition period when the zero cross point is not detected three times or more within the display update period. Electrical property measurement method.

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