JP2019191017A - Power supply quality detector - Google Patents

Abstract

To provide a power supply quality detector with which it is possible to satisfactorily detect power supply quality by a simple configuration.SOLUTION: Provided is a power supply quality detector 20 for detecting the quality of an AC power supply being supplied, comprising: a voltage clip circuit 21 for not passing electricity when the voltage of the AC power supply is lower than a prescribed voltage and passing electricity when higher than or equal to the prescribed voltage; a photocoupler 23, with its input side connected to the voltage clip circuit 21, for sending a signal from the voltage clip circuit 21 side to an output side while being electrically insulated; and a power supply quality detection unit 22 connected to the output side of the photocoupler 23. The power supply quality detection unit 22 detects the quality of the AC power supply on the basis of a signal from the photocoupler 23 side that is outputted when the voltage of the AC power supply is higher than or equal to the prescribed voltage.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a power quality detection device.

  Various precision instruments equipped with a computer (CPU) and the like exhibit their performance by being connected to an AC power source with stable quality. In other words, if the quality of the supplied AC power supply is poor, the precision instrument cannot exhibit some performance or the precision instrument itself cannot operate.

  As a device for detecting the quality of an AC power source including a commercial power source (power source quality detecting device), it is generally considered to use a transformer. In other words, by using a transformer, for example, the voltage of a 100V or 200V AC power supply is dropped, the power supply and the detection circuit are insulated, and the power supply voltage (voltage fluctuation) is detected by a detection circuit or the like connected to the computer unit. It was.

  Note that a transformer in which a transformer is connected to an AC power supply, and a power supply device that includes a voltage detection circuit and a current detection unit at an output unit of the transformer are disclosed in, for example, Patent Document 1.

JP 2017-99085 A

  However, since a transformer is used in the conventional power quality detection device, there is a problem that the weight increases and the cost becomes high.

  The present invention solves the above-described problems, and an object of the present invention is to provide a power supply quality detection device that can detect power supply quality satisfactorily with a simple configuration.

  In order to solve the above-mentioned problems, the present invention is a power quality detection device for detecting the quality of a supplied AC power supply, which is not energized when the voltage of the AC power supply does not reach a predetermined voltage, while not lower than the predetermined voltage. Is connected to the voltage clip circuit that is energized, the photocoupler that has the input side connected to the voltage clip circuit, sends the signal from the voltage clip circuit side to the output side in an electrically insulated state, and the output side of the photocoupler A power quality detecting unit configured to detect the quality of the AC power source based on a signal from the photocoupler output when the voltage of the AC power source is equal to or higher than the predetermined voltage. It is characterized by that.

  According to the above configuration, the period during which the voltage of the power supply is equal to or higher than the predetermined voltage can be detected by the power supply quality detection unit using the voltage clipping circuit and the photocoupler. That is, since the power quality can be detected without using a transformer, the power quality detecting device can be realized at a lower cost and lighter than when a transformer is used.

  In the present invention, the power quality detection unit calculates the frequency of the AC power supply as quality information by detecting a period between adjacent rising edges or falling edges of the output signal from the photocoupler side. Features. With this configuration, it is possible to determine the power quality by detecting the frequency of the power source with a simple configuration.

  Further, the present invention is characterized in that the power quality detection unit estimates an effective voltage of the AC power source as quality information based on a period in which the voltage of the AC power source is equal to or higher than the predetermined voltage. With this configuration, the power supply quality can be determined by detecting the voltage of the power supply with a simple configuration.

  Further, the present invention is characterized in that the power supply quality detection unit detects an instantaneous interruption of the supplied AC power supply as quality information based on a lack of rising or falling of the output signal from the photocoupler side. And With this configuration, it is possible to determine the power quality by detecting an instantaneous power failure or detecting the frequency of the instantaneous power failure.

  The present invention preferably includes a rectifying unit that rectifies the power supplied to the power supply unit. Further, it is more preferable that the rectifying unit is full-wave rectified, and it is possible to quickly detect a voltage, a frequency, or an instantaneous interruption compared to a case where the rectifying unit performs half-wave rectification.

  In addition, the present invention includes a determination warning unit that determines the power quality based on the quality information detected by the power quality detection unit, and warns when it is detected that the quality of the AC power supply is deteriorated. And With this configuration, it is possible to quickly and surely know a decrease in power quality.

  Further, the present invention is characterized in that the data writing process to the storage unit by the CPU of the computer is stopped based on the information on the instantaneous power failure detected by the power quality detection unit. With this configuration, it is possible to prevent the computer from crashing due to the loss of the data to be written without completely writing the data to be written.

  In addition, the power quality detection device is preferably provided in the weighing device, and further preferably provided in a track scale.

  According to the present invention, a voltage clip circuit that is energized when the voltage of the supplied AC power supply is equal to or higher than a predetermined voltage, and an input side connected to the voltage clip circuit to electrically insulate a signal from the voltage clip circuit side A photocoupler that is sent to the output side in a state in which the power supply is connected, and a power quality detection unit connected to the output side of the photocoupler. The power quality detection unit is output when the voltage of the AC power source is equal to or higher than the predetermined voltage. By detecting the quality of the AC power source based on the signal from the photocoupler side, the power source quality can be detected without using a transformer, and the power source quality detecting device can be realized at low cost and light weight.

  In addition, the power quality detector detects the frequency of the power supply with a simple configuration by detecting the period between adjacent rising or falling edges of the output signal from the photocoupler, and determines the power quality by detecting the frequency of the power supply. It becomes possible.

  Further, the power quality detection unit detects the voltage of the power supply with a simple configuration by estimating the effective voltage of the AC power supply as quality information based on a period in which the voltage of the AC power supply is equal to or higher than the predetermined voltage. It is possible to determine the power quality.

  In addition, the power supply quality detection unit detects the instantaneous interruption of the supplied AC power supply as quality information based on the lack of rise or fall of the output signal from the photocoupler side. The power quality can be determined by detecting a momentary power failure or detecting the frequency of the momentary power failure.

  Moreover, the power quality is deteriorated by having a determination warning unit for judging the power quality based on the quality information detected by the power quality detecting unit and warning that the quality of the AC power source is deteriorated. Can know quickly and reliably.

  In addition, by stopping the data writing process to the storage unit by the CPU of the computer based on the instantaneous power failure information detected by the power quality detection unit, it is possible to prevent the occurrence of a computer system crash and improve the reliability. To do.

It is a figure which shows simply the weighing | measuring apparatus provided with the power supply quality detection apparatus which concerns on embodiment of this invention. It is a figure which shows simply the indicator storage part, the indicator, etc. of the measuring device. It is a figure which shows the power supply quality detection apparatus which concerns on embodiment of this invention. It is a figure which shows the voltage of AC power supply. It is a figure which shows the voltage after the rectification (full wave rectification) of AC power supply. It is a figure which shows the output signal of the photocoupler of the power supply quality detection apparatus. It is a figure which shows the input signal to the power supply quality detection part of the power supply quality detection apparatus. It is a figure which shows the difference of the signal of the light emission part of a photocoupler by the voltage, and the input signal to a power supply quality detection part.

  Hereinafter, a power quality detection apparatus according to an embodiment of the present invention will be described. First, a weighing apparatus provided with a power quality detection apparatus according to an embodiment of the present invention will be described with reference to the drawings. Here, FIG. 1 is a diagram simply showing a track scale which is an example of a weighing device, and FIG. 2 is a diagram simply showing an indicator storage part, an indicator, and the like of the weighing device.

  As shown in FIGS. 1 and 2, the track scale as an example of the weighing device 1 includes a platform 2 as a load loading unit on which a load is loaded (a loaded truck is loaded), and the platform. The load (weight) is calculated based on a plurality of (four in this embodiment) digital load cells 3 (3A to 3D) that support 2 and output data corresponding to the load, and output signals from the digital load cell 3. An indicator 4, a connection wiring 5 for connecting the digital load cell 3 and the indicator 4, a power supply unit 6 connected to a commercial power supply, and the like. The power quality detection device 20 is connected. In this embodiment, as shown in FIGS. 1 and 2, the indicator 4, the power supply unit 6, the power supply quality detection device 20, and the like are connected to an indicator storage unit (indicator storage box (storage housing)) 10. Although the case where it is accommodated is shown, it is not restricted to this.

  In this embodiment, a plurality (for example, four) of digital load cells 3 (3A to 3D) are connected to a load cell unit connecting portion (so-called junction box) 7 and connected to the digital load cell 3 through the connection wiring 5. While power is supplied, a signal from each digital load cell 3 (3A to 3D) is sent to the indicator 4 side through the connection wiring 5. 2, 11 is an overall power switch for turning on (connecting) and turning off (disconnecting) the entire power of the weighing device 1 including the indicator storage unit 10, and 12 is a power plug (power supply) connected to a commercial power source. Part) and 13 are terminal blocks to which the connection wiring 5 is connected.

  As shown in FIG. 2, the indicator 4 is assembled in an indicator storage unit (indicator storage box) 10 in a detachable state, for example, and includes an indicator power switch 4a and various values including measurement values. A display unit 4b for displaying information, an input unit 4c used for making various settings, and instructing the digital load cell 3 to send a signal such as a weight value and inputting signals from all the digital load cells 3. And an indicator CPU (indicator control unit) 4d for calculating a measurement value and performing various controls relating to the weighing operation, a storage unit 4e for storing various information relating to the measurement, and the like.

  In addition, the indicator storage unit 10 that detachably stores the indicator 4, the sub-board 15 having the power supply unit 6 and the sub CPU 16, and the built-in CPU (upper computer CPU) 17 that controls the entire weighing device 10. And a storage unit 18 for storing and saving various types of information. The sub-board 15 is also provided with a storage unit 16a having an area for temporarily storing output data from the digital load cell 3 and the like. In the weighing device 1, power is supplied to the sub-board 15 and the digital load cell 3 even when the power switch 4 a of the indicator 4 is not turned on.

  As shown in FIGS. 2 and 3, the indicator storage unit 10 (in this embodiment, the sub-board 15 of the indicator storage unit 10) detects the quality of the AC power supplied. A power quality detection device 20 according to the embodiment is provided. In the power quality detection device 20, the voltage of an AC power supply (100 V commercial AC power supply in this embodiment) is a predetermined voltage (a maximum instantaneous voltage value defined by the AC power supply (about 141 V (100 × √ in this embodiment)). 2)) When the voltage is lower than, for example, 100 V), it is not energized (turned off). On the other hand, when it is equal to or higher than the predetermined voltage, the voltage clip circuit 21 that is energized (turned on) A photocoupler 23 that is connected and sends a signal from the voltage clip circuit 21 side to the output side in an electrically insulated state, a power quality detector 22 connected to the output side of the photocoupler, and the like.

  The power quality detector 22 of the power quality detector 20 uses the voltage clip circuit 21 and the photocoupler 23 to output a photocoupler that is output when the voltage of the AC power supply is equal to or higher than the predetermined voltage (threshold voltage). The quality of the AC power supply is detected based on the signal from the 23 side. In this embodiment, as shown in FIG. 3, the voltage clip circuit 21 is formed of a Zener diode. However, any circuit other than the Zener diode may be used as long as it is a circuit that is energized (ON) when the voltage is higher than a predetermined voltage. The configuration can be used.

  In this embodiment, as shown in FIG. 3, the power quality detection device 20 includes a rectifier 24 that rectifies the supplied AC power and a DC connected to one of the outputs of the photocoupler 23. Based on the quality information detected by the power supply unit (power supply unit that pulls up to a predetermined voltage when the output unit of the photocoupler 23 is in the OFF state) 25 and the power quality detection unit 22, the quality of the AC power supply is determined. A determination warning unit 26 that issues a warning such as an error output when a decrease is detected is also provided. In this embodiment, the rectifying unit 24 is configured to connect four diodes by a bridge circuit, and is configured to full-wave rectify the supplied AC power supply as shown in FIGS. 4 and 5. Yes.

  Therefore, the photocoupler 23 is loaded with a full-wave rectified voltage, and when this voltage is equal to or higher than the predetermined voltage (100 V), the photocoupler 23 emits and receives light, and as shown in FIG. When the voltage is equal to or higher than the predetermined voltage (100 V), the light emitting portion of the photocoupler 23 becomes H (high voltage). Further, in this embodiment, the voltage is lowered to L (low voltage) by grounding only when the photocoupler 23 is energized (the LH signal is reversed) (see FIG. 7).

The power supply quality detection unit 22 detects a period A (see FIG. 7) between adjacent falling edges (or rising edges) of the output signal from the photocoupler 23 side, and based on this period A, the frequency of the AC power supply Is calculated. For example, when this period is 10 msec, it is 50 Hz. Specifically, for example, the frequency is calculated from the following calculation formula (Formula 1). Here, when the count reference frequency for detection is 4 MHz (resolution: 250 ns), for example, the falling (falling edge) and the rising (rising edge) are measured, and the input pulse interval (period A) is measured. Here, Pfreq is a power supply frequency (Hz), Cfreq is a reference frequency (Hz) = 4 MHz, and Cfn (n is time-series data) is a power supply cycle count value. The count value is added using the long type, and the frequency calculation is performed using the float type. In Equation 1 described below, the average of the latest four times is calculated by taking Σ (sum) of n = 1 to 4.

  In addition, if the minimum frequency for determination and the maximum frequency for determination are set in advance and the measured frequency falls below the minimum frequency for determination or exceeds the maximum frequency for determination, the quality of the AC power supply ( It is determined by the determination warning unit 26 that the frequency is lower, and error information is output (displayed or stored (printed or displayed)), assuming that the power supply frequency is abnormal.

Further, the power quality detection unit 22 estimates the effective voltage of the AC power source as quality information based on the period B in which the voltage of the AC power source is equal to or higher than the predetermined voltage (100 V). That is, it is assumed that the supplied AC power is a sine wave, and the period B that is equal to or higher than the predetermined voltage (100 V) becomes longer as the voltage becomes higher. Therefore, the effective voltage of the AC power is estimated from this period B. For example, the voltage is estimated (calculated) from the following calculation formula (Formula 2). Here, the voltage is (calculated) assuming that the count reference frequency for detection is 4 MHz (resolution: 250 ns), for example. Here, Vest is an estimated voltage value (V), Vdct is a waveform detection voltage (here, for example, about 105.5 V), Cpn (n is time-series data) is a voltage detection count value, and Cerr is a voltage detection correction value. (For example, about −100), Cfn (n is time-series data) is a power cycle count value. The count value is added using the long type, and the frequency calculation is performed using the float type. Since the waveform detection voltage Vdct and the voltage detection correction value Cerr are values that can be corrected, it is desirable to adjust them by actually measuring with the measuring device. The voltage detection correction value Cerr is a difference between the fall time and the rise time of the signal, and is set to −100 at 25 μs, for example. In Equation 2 described below, the average of the latest four times is calculated by taking Σ (sum) of n = 1 to 4.

  For example, in FIG. 8, the left side shows the signal of the light emitting unit of the photocoupler 23 and the input signal to the power quality detection unit 22 and the period B1 when the effective voltage of the AC power source is 100V, and the center shows the effective AC power source. The signal of the light emitting unit of the photocoupler 23 when the voltage is lower than 100 V, the input signal to the power quality detection unit 22 and the period B2 are shown, and the right side shows the light emission of the photocoupler 23 when the effective voltage of the AC power supply is lower. Signal and the input signal to the power quality detector 22 and its period B3. That is, when the effective voltage of the AC power source is lower than 100V, the period B2 that is equal to or higher than the predetermined voltage (100V) is the predetermined time when the effective voltage of the AC power source is 100V (maximum instantaneous voltage value is about 141V). If the effective voltage of the AC power supply becomes lower and the maximum (maximum) instantaneous voltage value becomes lower than 100V, the period B3 becomes 0. . Thus, the voltage of the AC power supply is estimated using the characteristic that the time for exceeding the predetermined voltage is shortened as the voltage is lowered.

  In addition, if the minimum voltage for determination and the maximum voltage for determination are set in advance and the measured voltage falls below the minimum voltage for determination or exceeds the maximum voltage for determination, the quality of the AC power supply (voltage The determination warning unit 26 determines that the number is low, and outputs error information (displays or stores (prints or displays)) indicating that the power supply voltage is abnormal.

  Further, the power quality detection unit 22 lacks rising or falling of the signal of the light emitting unit of the photocoupler 23, and the input signal to the power quality detection unit 22 remains H (high voltage) (or the photocoupler 23). The period during which the signal of the light emitting unit is L (low voltage) is measured, and if it is equal to or longer than a predetermined period (for example, 10 ms), it is determined that there is an instantaneous stop, and the instantaneous stop time and the number of instantaneous stop are detected. For example, when the count reference frequency is 125 kHz (resolution: 250 μs) and the count value is 1250 or more, that is, the H (high voltage) period is 10 ms or more, the instantaneous power interruption number counter is incremented by 1 and the count value is 2500 When the H (high voltage) period is 20 ms or more, the instantaneous power failure counter is counted up by 2 and the count value is 5000 or more, that is, the H (high voltage) period is 40 ms or more. If the instantaneous power failure number counter is incremented by 3 and the count value is 10000 or more, that is, the H (high voltage) period is 80 ms or more, the instantaneous power failure number counter may be incremented by 4 or the like. This is not a limitation. Further, the count number is confirmed, and if the count value is 1000 or more, an error output (for example, a voltage drop warning) may be output (displayed or stored).

  According to the above configuration, the power quality can be determined with a simple configuration by detecting the frequency, voltage, and instantaneous interruption of the AC power supply. And it is possible to detect the power supply quality (frequency, voltage, presence / absence and frequency of instantaneous power interruption) without using a transformer, and the power supply quality detection device 20 can be realized at low cost and light weight. In other words, when instantaneous power failure occurs regularly, suddenly large current is generated due to whether the supplied AC power supply is unstable or a power system device is connected to the AC power supply. It is considered that this is a state where the voltage of the AC power supply is lowered. In either case, the circuit of the power supply unit 6 of the weighing device 1 that is a precision instrument may be stressed to shorten the product life, and various CPUs (computers) may be caused by the instability of the AC power supply. 4d, 16, and 17 may become unstable. Therefore, if a decrease in power quality (frequency, voltage, presence / absence and frequency of instantaneous power interruption) (such as the above error information or warning) is detected, the AC power supply can be confirmed to be unstable. Various measures can be taken by adding a stabilized power source.

  When a momentary power failure is detected, a signal (instantaneous power failure detection signal) is output to the built-in CPU 17. When this momentary power failure detection signal is input, the built-in CPU (high-order computer CPU) 17 writes data to the storage unit 18. May be configured to stop. In other words, the built-in CPU 17 completes the writing process of the contents stored in the storage unit 18 such as the RAM and stops the new writing start process when notified of the instantaneous power failure. Thereby, it is possible to prevent a system crash from occurring in the built-in CPU 17. In other words, if the power is turned off while data is being written to the storage unit 18, the data to be written is lost without completely writing the data to be written. Although the system crash of the CPU 17 may occur, according to the above configuration, the system crash of the built-in CPU 17 (higher computer) can be prevented and the reliability is improved.

  In the above configuration, the power quality information is preferably operated and displayed by a specific person such as a person who performs maintenance of the weighing device, but is not limited thereto. It may be configured so that it can be displayed and output even to a person using the device.

  Moreover, in the said embodiment, since the rectification | straightening part 24 carries out full wave rectification of AC power supply, compared with the case where AC power supply is half-wave rectified, it becomes possible to detect a voltage, a frequency, or a momentary power failure quickly. However, the configuration is not limited to this, and the rectifying unit 24 may be configured to perform half-wave rectification of the AC power supply.

  In the above embodiment, the case where the power quality detection device 20 is provided in the weighing device 1 (track scale) is described. However, the present invention is not limited to this. It goes without saying that this power quality detection device 20 may also be provided in a precision instrument or the like.

1 Weighing device (track scale)
2 Platform 3, 3A-3D Digital load cell 4 Indicator 10 Indicator storage unit 15 Sub board 16 Sub CPU
17 Built-in CPU (upper CPU)
DESCRIPTION OF SYMBOLS 18 Memory | storage part 20 Power supply quality detection apparatus 21 Voltage clip circuit 22 Power supply quality detection part 23 Photocoupler 24 Rectification part 25 DC power supply part 26 Determination warning part

Claims (10)

A power quality detection device for detecting the quality of supplied AC power,
A voltage clip circuit that is not energized when the voltage of the AC power supply does not reach the predetermined voltage, while energized when the voltage is equal to or higher than the predetermined voltage;
A photocoupler whose input side is connected to the voltage clip circuit and which sends the signal from the voltage clip circuit side to the output side in an electrically insulated state;
A power quality detector connected to the output side of the photocoupler;
With
The power quality detector is configured to detect the quality of the AC power based on a signal from the photocoupler output when the voltage of the AC power is equal to or higher than the predetermined voltage.   The power supply quality detection unit calculates a frequency of an AC power supply as quality information by detecting a period between adjacent rising edges or falling edges of an output signal from the photocoupler side. The power quality detection device described in 1.   The power supply quality detection device according to claim 1, wherein the power supply quality detection unit estimates an effective voltage of the AC power supply as quality information based on a period in which the voltage of the AC power supply is equal to or higher than the predetermined voltage.   The power supply quality detection unit detects an instantaneous interruption of the supplied AC power supply as quality information based on lack of rising or falling of the output signal from the photocoupler side. The power quality detection device described.   The power quality detection device according to claim 1, further comprising a rectification unit that rectifies the supplied AC power.   6. The power quality detection apparatus according to claim 5, wherein the rectification unit performs full-wave rectification of the AC power supply.   The power supply quality detection unit determines a power supply quality based on the quality information, and has a determination warning unit that warns when it is detected that the quality of the AC power supply is deteriorated. 7. The power supply quality detection device according to any one of items 6.   8. The power quality according to claim 1, wherein the processing of writing information to the storage unit by the CPU of the computer is stopped based on information on the instantaneous power failure detected by the power quality detection unit. Detection device.   The power supply quality detection device according to any one of claims 1 to 8, wherein the power supply quality detection device is provided in a weighing device.   The power supply quality detection apparatus according to claim 9, wherein the power supply quality detection apparatus is provided on a track scale.

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