JP4670775B2 - measuring device - Google Patents

Description

  The present invention relates to a measuring apparatus that measures current, voltage, and power by a digital sampling method.

  Conventionally, analog, current, and voltage values measured with an input circuit are digitally converted at a specified sampling period, and the current value, voltage value, or calculated power value is output as a measured value. There is a measuring device to measure. For example, Patent Document 1 discloses a digital sampling-type integrated watt-hour meter, and a technique for monitoring integrated power in real time in addition to a function for obtaining integrated power for each interval.

  That is, FIG. 4 is a block diagram schematically showing the configuration of the conventional measuring apparatus 100 described above. The measuring apparatus 100 includes input circuits 111 and 112, A / Ds 121 and 122, peak detection circuits 123 and 124, a DSP 130, a peak latch circuit 140, a CPU 150, and a display unit 160.

  The input circuits 111 and 112 normalize the voltage V and current I input from terminals not shown in particular. The A / Ds 121 and 122 perform analog / digital conversion of outputs of the input circuits 111 and 112 within a predetermined dynamic range (conversion range). In addition, A / D121,122 outputs the upper limit or lower limit value, when the value exceeding the upper limit or lower limit of the conversion range is input. The peak detection circuits 123 and 124 detect a peak over when the output of the input circuits 111 and 112 is outside the conversion range of the A / D 121 and 122, and output a peak over signal to the peak latch circuit 140.

  The DSP 130 (Digital Signal Processor) has a working RAM (Random Access Memory) (not shown) and the like, acquires the outputs of the A / Ds 121 and 122 at a predetermined sampling cycle, that is, acquires voltage values and current values, and instantaneously Power (current value x voltage value) is calculated. The DSP 130 stores data for a predetermined time (for example, data for one cycle) in the work RAM, thereby calculating integrated power, calculating an average current value, and an average voltage value. For example, the DSP 130 performs cycle-by-cycle measurement to obtain voltage, current, and power for each period by setting the predetermined time to one period (one wave).

  Specifically, the DSP 130 performs an operation process as shown in FIG. 5 when measuring current, voltage, and power (cycle-by-cycle measurement). As shown in the figure, first, measurement loop processing (steps S101 to S109) for performing measurement for a predetermined cycle is started. Next, the A / D value (instantaneous voltage) of the voltage V is acquired from the A / D 121 (step S102), and the A / D value (instantaneous current) of the current I is acquired from the A / D 122 (step S103). The instantaneous power is calculated by the product of the instantaneous voltage and the instantaneous current (step S104), and the acquired instantaneous voltage, instantaneous current, and instantaneous power are stored in the working RAM or the like (step S105).

  After step S105, it is determined whether or not a predetermined measurement section, for example, a measurement section for one cycle at the time of cycle-by-cycle measurement, is completed (step S106). If not completed, the process returns to step S102. That is, a series of processing from step S102 to S106 is processing for sampling the instantaneous voltage, the instantaneous current, and the instantaneous power, and is performed at a preset sampling cycle.

  Following step S106, when sampling of one measurement section is completed (step S106: YES), the integrated power is calculated based on the instantaneous voltage, instantaneous current, instantaneous power, etc. stored in the working RAM or the like, the average current value, A measurement value such as an average voltage value is calculated (step S107), and the calculated measurement value is transferred to the CPU 150 (step S108), and the process proceeds to the next loop (step S109). The DSP 130 performs the above-described operation process and outputs a measurement value to the CPU 150.

  The peak latch circuit 140 latches the peak over signal output from the peak detection circuits 123 and 124, and transmits the peak over signal to the CPU 150 through the interrupt handler. A CPU 150 (Central Processing Unit) includes a ROM (Read Only Memory), a RAM, and the like in which a control program and the like are stored, and reads out the control program to the RAM and sequentially executes the control program 100 to control each part of the measurement apparatus 100. The display unit 160 is an LCD (Liquid Crystal Display) or the like, and performs screen display based on an instruction from the CPU 150.

Under the control of the CPU 150, the measurement apparatus 100 displays the measurement / calculation result in the DSP 130, peak-over information based on the peak-over signal through the interrupt handler, and the like on the screen of the display unit 160. Specifically, as shown in FIG. 6, when the input current is digitally converted at a predetermined sampling period and cycle-by-cycle measurement is performed in the measurement sections K1, K2, K3..., The DSP 130 measures the measurement sections K1, K2,. Subsequent to the sampling at K3, calculation and output are sequentially performed, and the CPU 150 receives the output and performs display control of the measured value. Further, the peak over display outside the A / D conversion range between time t1 and t2 or between time t3 and t4 is immediately controlled by the CPU 150 based on the detection by the peak detection circuit 124. .
JP-A-7-922209

  As described above, the detection and display of peak over in the conventional measurement apparatus 100 is not synchronized with the measurement value for each measurement section. This is because the peak over detection / display is intended to protect the input circuit and prevent danger.

  In addition, when an excessive input occurs instantaneously in the sampling process and exceeds the A / D conversion range, the current / voltage calculated with the digital value (measurement value) changed by mistake. -Even if the calculation result is within the allowable range, an event that the measurement value is not normal occurs. However, when the measurement interval is set to be long over a plurality of periods, the number of samplings increases, so that the influence is not so great.

  However, in recent years, in the evaluation of wind power generation and small motors, there has been an increasing demand for cycle-by-cycle measurement for obtaining voltage, current, and power for each cycle (one wave). In this cycle-by-cycle measurement, the number of samples is smaller than the conventional sampling over multiple periods, and the validity of the measured value at the time of peak over detection is ignored because of the strict demand for the measured value for each period. become unable. However, in the conventional measuring apparatus 100, since the synchronization between the detection of the peak over and the measurement value is not established, the correctness of the measurement value cannot be evaluated.

  The present invention has been made in view of such problems, and the object of the present invention is to determine the validity of the measurement value when measuring current, voltage, and power with a plurality of sampling data for each predetermined section. An object of the present invention is to provide a measuring apparatus capable of evaluating the sex.

In order to solve the above-described problem, the invention according to claim 1 is an arithmetic means for calculating a measurement value for each measurement section based on sampling data obtained by A / D converting input data at a predetermined sampling period. Detecting means for detecting whether input data when acquiring sampling data by performing A / D conversion in any one of the measurement sections is a value based on the A / D conversion range A flag memory for storing the detection result for any one of the measurement sections, a measurement value calculated by the calculation means for the any measurement section, and a detection result stored in the flag memory. comprising a data output means for outputting, and a display control means for displaying on the display unit the outputted measured value and the detected result by said data output means, said detecting means In addition, it is determined whether the A / D converted sampling data is a value greater than or equal to a preset upper limit threshold value or a lower limit threshold value within the A / D conversion range. In the measurement interval, the A / D-converted sampling data is detected to be in a peak over state exceeding the upper limit when the value is equal to or greater than the upper limit threshold, and in any one of the measurement intervals, the A / D When the converted sampling data is equal to or less than the lower limit threshold value, it is detected that the peak over state is below the lower limit, and the data output means detects that the peak output state exceeds the upper limit by the detection means. If it is out, the respect one of the measurement interval, and outputs a detection result and a peak over condition exceeding the upper limit calculated measured values by the arithmetic means If it is the peak over condition is below the lower limit is detect by the detector, wherein for any of the measurement interval, the detection result and the peak over condition below the lower limit and the measured value calculated by the arithmetic means When the measurement value calculated by the calculation means and the detection result in the peak over state exceeding the upper limit are output by the data output means, the display control means outputs a peak exceeding the upper limit. Information indicating the over-state is displayed at a position corresponding to the measurement section where the peak-over state exceeding the upper limit is detected, and the measured value calculated by the computing means and the peak-over state below the lower limit When a certain detection result is output, information indicating the peak over state exceeding the lower limit is detected, and the peak over state exceeding the lower limit is detected. It is characterized by being displayed at a position corresponding to the measured section .

According to a second aspect of the present invention, in the first aspect of the present invention, the preset upper limit threshold in the detection means is an upper limit value of the A / D conversion range.

According to a third aspect of the present invention, in the first aspect of the present invention, the preset lower limit threshold value in the detecting means is a lower limit value of the A / D conversion range.

  According to the present invention, in a measurement apparatus that calculates a measurement value for each measurement section based on sampling data acquired by A / D converting input data at a predetermined sampling period, A / D Since it is a configuration for outputting a detection result obtained by detecting whether or not input data when converting and obtaining sampling data is a value based on the A / D conversion range, and the calculated measurement value, When current, voltage, power, etc. are measured with a plurality of sampling data for each predetermined section, the validity of the measured value can be evaluated.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3, but the present invention is not limited to the following embodiments. Further, the embodiment of the present invention shows the most preferable embodiment of the invention, and the uses and terms of the invention are not limited to this. FIG. 1 is a block diagram schematically showing a functional configuration of a measuring apparatus 1 according to the present invention. FIG. 2 is a flowchart illustrating the operation of the measurement apparatus 1 during measurement. FIG. 3 is a conceptual diagram illustrating a measurement result displayed on the display unit 50 of the measurement apparatus 1.

  As shown in FIG. 1, the measuring apparatus 1 includes input circuits 11 and 12, A / D 21 and 22, a DSP 30, a CPU 40, and a display unit 50. The input circuits 11 and 12 normalize the voltage V and the current I input from terminals not shown in particular. The A / Ds 21 and 22 convert the outputs of the input circuits 11 and 12 from analog to digital.

  The DSP 30 has memories 31, 32, calculation means 33, detection means 34, flag memory 35, and data output means 36, and acquires the outputs of A / Ds 21, 22 at a predetermined sampling period, that is, voltage values and current values. Is obtained, and instantaneous power (current value × voltage value) is calculated. It should be noted that the functions of the above-described units in the DSP 30 may be realized by developing a control program stored in a ROM in the DSP 30 (not shown) in a work area of a RAM (not shown) and sequentially executing the program.

  The memories 31 and 32 are digital data (voltage V and current I) converted by the A / Ds 21 and 22 and sequentially store sampling data acquired at a predetermined sampling period. The calculation means 33 performs a calculation based on the sampling data stored in the memory 31 and the memory 32 and calculates a measurement value. The calculation in the calculation means 33 includes calculation of measurement values calculated for each sampling data, such as calculation of instantaneous power based on voltage values and current values acquired simultaneously by the A / Ds 21 and 22, and sampling data within the measurement section. The measurement value calculated for each measurement section is calculated, such as calculating the average value (average voltage, average current, average voltage,...). Note that the measurement section is, for example, a period (one wave) in cycle-by-cycle measurement, and a predetermined time is set in advance by an operation unit such as a switch (not shown).

  In the detection means 34, the maximum value / minimum value of the conversion ranges of the A / Ds 21 and 22 are set in advance. By sequentially reading and comparing the sampling data stored in the memories 31 and 32, the maximum value is obtained. It is detected that the peak is over on the positive side, and that the peak is over on the negative side when the minimum value is reached. For example, when the A / D 21 and 22 perform 16-bit A / D conversion and output a value of FFFF to 0000, the detection unit 34 reads the sampling data and determines whether the input is correctly converted or not. When the maximum value (FFFF) or the minimum value (0000) is unknown, the peak over state is detected. The flag memory 35 is a memory that stores the result detected by the detecting means 34 in association with the sampling data stored in the memories 31 and 32.

  Note that the detection means 34 is not limited to a configuration in which the maximum value / minimum value of the conversion ranges of the A / Ds 21 and 22 are set in advance, and the upper limit or the lower limit with a slight margin with respect to the maximum value / minimum value. May be configured so that the peak over state is detected when the threshold value is set in advance and is equal to or higher than the upper threshold value or lower than the lower threshold value. For example, when the A / D 21 and 22 perform 16-bit A / D conversion and output a value of FFFF to 0000, the upper limit threshold is set to FFF0, and the lower limit threshold is set to 000F, the detection unit 34 performs sampling. Data is read out, and a peak over state is detected when the value is from FFFF to FFF0 or from 0000 to 000F.

  The data output means 36 is a functional unit that outputs a result detected by the detection means 34 and a measurement value calculated by the calculation means 33 to the CPU 40 for any measurement section. When the measurement value calculated in this way is output, the detection result of the detection means 34 relating to the sampling data in the measurement section is read from the flag memory 35 and output.

  Here, an operation performed by the DSP 30 when measuring current, voltage, and power (for example, cycle-by-cycle measurement) will be described. As shown in FIG. 2, first, measurement loop processing (steps S11 to S31) for performing measurement for a predetermined cycle is started.

  In this measurement loop process, steps S12 and S13 related to voltage acquisition are processes performed in the memory 31. Further, steps S14 to S18 in which the determination of the voltage A / D value and the peak over information as a result thereof are stored in the flag memory 35 are processes performed by the detection means 34. Steps S19 and S20 related to current acquisition are processes performed in the memory 32. Further, steps S21 to S25 in which the determination of the current A / D value and the peak over information as a result thereof are stored in the flag memory 35 are processing performed by the detection means 34. Further, steps S26 to S29 relating to the measurement section end determination and measurement value calculation from the calculation of the instantaneous voltage are processes performed by the calculation means 33. Steps S30 and S31 relating to measurement value output and measurement loop end determination are processes performed by the data output means 36.

  Next, an A / D value (instantaneous voltage) of the voltage V is acquired from the A / D 21 (step S12), and the acquired voltage V is stored in the memory 31 (step S13).

  Next, it is determined whether or not the A / D value of the voltage V is the maximum value in the conversion range (step S14). If not, the A / D value of the voltage V is the minimum value in the conversion range. Is determined (step S15). If the voltage is the maximum value in step S14, it is stored in the flag memory 35 in association with the voltage V stored in the memory 31 (steps S16 and S18). If the voltage is the minimum value in step S15, it is stored in the flag memory 35 in association with the voltage V stored in the memory 31 (step S17, S18).

  Next, the A / D value (instantaneous current) of the current I is acquired from the A / D 22 (step S19), and the acquired current I is stored in the memory 32 (step S20).

  Next, it is determined whether or not the A / D value of the current I is the maximum value in the conversion range (step S21). If not, the A / D value of the current I is the minimum value in the conversion range. Is determined (step S22). If the current value is the maximum value in step S21, it is stored in the flag memory 35 in association with the current I stored in the memory 32 (steps S23 and S25). If the current value is the minimum value in step S22, it is stored in the flag memory 35 in association with the current I stored in the memory 32 (steps S24 and S25).

  Next, the instantaneous power by the product of the instantaneous voltage and the instantaneous current is calculated (step S26), stored in a memory such as the memory 31, 32 (step S27), and for a predetermined measurement section, for example, one cycle at the time of cycle-by-cycle measurement. It is determined whether or not the measurement interval has been completed (step S28). If the measurement interval has not been completed, the process returns to step S12 to perform processing related to the next sampling data. That is, a series of processes from Steps S12 to S28 is a process for acquiring an instantaneous voltage, an instantaneous current, and an instantaneous power, and is performed at a preset sampling cycle.

  After step S28, when sampling of one measurement section is completed (step S28: YES), calculation of integrated power, average current value based on instantaneous voltage, instantaneous current, instantaneous power, etc. stored in memories 31, 32 Calculation of the measurement value in the measurement interval such as calculation of the average voltage value and the like is performed (step S29).

  Next, information (voltage / current) relating to the peak over of sampling data related to the calculation of the measurement value of the measurement section stored in the flag memory 35 is output to the CPU 40 together with the calculated measurement value (step S30). The process proceeds to the next loop (step S31).

  In the DSP 30, by performing the above-described operation, when the measurement value (voltage, current, power) for each measurement interval is output, the sampling data related to the measurement interval is the dynamic range (conversion range) of the A / D 21, 22 The peak over information that is the result of detecting whether or not the value is within the range is output.

  The above description of the operation of the DSP 30 is configured to detect the case where the sampling data is the maximum value (upper limit value) or the minimum value (lower limit value) of the conversion range. It goes without saying that the configuration for detecting cases is the same.

  The CPU 40 includes a ROM, a RAM, and the like in which a control program and the like are stored. The CPU 40 reads out the control program to the RAM and sequentially executes the control program 1 so as to comprehensively control each unit of the measurement apparatus 1. The display unit 50 is an LCD, a CRT (Cathode Ray Tube), or the like, and performs screen display based on an instruction from the CPU 40.

With the above-described configuration, the measuring apparatus 1 can display the measurement result based on the output from the DSP 30 as shown in FIG. That is, the display unit 50 includes
Measurement results such as “frequency”, “measurement voltage”, “measurement current”, “measurement power” for each “No.” that is a measurement section are displayed.

  Further, since the display unit 50 is based on the output from the DSP 30, when the sampling data related to any one of the measurement sections is a peak over that falls below the lower limit of the conversion range, “P- "Is displayed at a position corresponding to the measurement section. Similarly, on the display unit 50, when the sampling data related to any measurement section is a peak over that exceeds the upper limit of the conversion range based on the output from the DSP 30, "P +" indicating that is displayed. It is displayed at the position corresponding to the measurement section. For this reason, the user can visually recognize the legitimacy of the measurement values in the measurement section.

  As described above, the measuring apparatus 1 calculates the measurement value for each measurement section by the calculation means 33 based on the sampling data acquired by A / D converting the input data at a predetermined sampling period, and A / D conversion Then, the detection means 34 detects whether or not the input data when acquiring the sampling data is a value that falls within the A / D conversion range, and the result of detection by the detection means 34 for any one of the measurement sections The data output means 36 for outputting the measurement value calculated by the calculating means 33 is provided. For this reason, the measuring apparatus 1 can evaluate the validity of the measured value when measuring current, voltage, power, and the like with a plurality of sampling data for each predetermined section.

  Note that the description in the present embodiment shows an example of the present invention, and the present invention is not limited to this. The configuration and operation in the present embodiment can be changed as appropriate without departing from the spirit of the present invention.

It is a block diagram which shows typically the functional structure of the measuring apparatus 1 which is this invention. 4 is a flowchart illustrating an operation of the DSP 30 during measurement by the measurement apparatus 1. FIG. 4 is a conceptual diagram illustrating a measurement result displayed on a display unit 50 of the measurement apparatus 1. It is a block diagram which shows typically the functional structure of the conventional measuring apparatus 100. FIG. 5 is a flowchart illustrating an operation at the time of measurement of the measurement apparatus 100. 6 is a timing chart illustrating the operation timing of each part of the measurement apparatus 100 during measurement.

Explanation of symbols

1 Measuring device 11, 12 Input circuit 21, 22 A / D
30 DSP
31, 32 Memory 33 Calculation means 34 Detection means 35 Flag memory 36 Data output means 40 CPU
50 Display V Voltage I Current

Claims (3)

In a measurement apparatus having a calculation means for calculating a measurement value for each measurement section based on sampling data obtained by A / D converting input data at a predetermined sampling period,
Detecting means for detecting whether or not input data when acquiring sampling data by performing A / D conversion in any one of the measurement sections is a value based on the A / D conversion range;
A flag memory for storing the detection result relating to any one of the measurement sections;
Data output means for outputting the measurement value calculated by the calculation means and the detection result stored in the flag memory for any one of the measurement sections;
Display control means for displaying the measurement value and the detection result output by the data output means on a display unit ,
The detection means determines whether the A / D converted sampling data is a value greater than or equal to a preset upper limit threshold value or less than a lower limit threshold value within the A / D conversion range. In any one of the measurement sections, the A / D converted sampling data is detected to be in a peak over state exceeding the upper limit when the sampling data is a value equal to or higher than the upper limit threshold. When the A / D converted sampling data is a value equal to or lower than the lower limit threshold, it is detected that the peak over state is below the lower limit,
It said data output means, when it is the peak over condition exceeding the upper limit is detect by the detector, wherein for any of the measured section, exceeds the upper limit and the measured value calculated by the arithmetic means outputs the detection result and a peak over condition, if it is the peak over condition is below the lower limit is detect by the detector, wherein for any of the measurement period, the measurement value calculated by the arithmetic means Output a detection result that is a peak over state below the lower limit ,
The display control means includes
When the data output means outputs the measurement value calculated by the computing means and the detection result in the peak over state exceeding the upper limit, information indicating the peak over state exceeding the upper limit, When the peak over state exceeding the upper limit is displayed at a position corresponding to the detected measurement section, and the measurement value calculated by the calculation means and the detection result of the peak over state below the lower limit are output, Information indicating that a peak over state exceeding the lower limit is displayed at a position corresponding to a measurement section in which a peak over state exceeding the lower limit is detected .   The measuring apparatus according to claim 1, wherein the preset upper limit threshold value in the detecting means is an upper limit value of the A / D conversion range.   The measuring apparatus according to claim 1, wherein the preset lower limit threshold value in the detecting means is a lower limit value of the A / D conversion range.

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