JPH042971A - Electronic watt-hour meter - Google Patents

Abstract

PURPOSE:To obtain a watt-hour meter equipped with a highly precise time counting device by generating one clock signal from a control circuit at the time of transition from the interruption of service of a commercial power supply to the start thereof and by synchronizing the signal with a reference period of a clock signal generated from a frequency divider which divides the frequency of the commercial power supply. CONSTITUTION:When the service of a commercial power supply is started, a frequency divider 3 starts counting from this time point as a starting point. Simultaneously when a microprocessor (MPU) 1 makes an interrupt action on the basis of one clock signal generated from a control circuit 11 immediately after the start, a time counter 8 counts the clock signal. Since a reset signal generated by the interrupt action of the MPU 1 is given at this time, a count value of the frequency divider 3 up to this time is cleared and the counting is restarted, while a switch 7 is changed over to the end on the service side. Accordingly, a clock signal of a one-second period is inputted from the frequency divider 3 to the counter 8 synchronously with the clock signal generated from the control circuit 11, and therefore no deviation occurs in the period of the clock signal even at the time point of changeover from the interruption of the service to the start thereof.

Description

[Detailed Description of the Invention] [Purpose of the Invention (Industrial Application Field) The present invention provides an electronic power consumption system that has a clock device and measures the power consumption for each time period set in the clock device. Regarding the meter.

(Prior art) There are various types of electronic watt-hour meters.
Among them, there is an electronic watt-hour meter that can be set for multiple time periods, which divides the day into multiple time periods and sets electricity rates for each time period. This electronic watt-hour meter has an internal clock device (timer) for setting time zones, and measures the amount of power in each time zone with reference to this timer.

By the way, in such an electronic watt-hour meter that can be set for multiple time periods, the basic clock source used for the timer is a method of obtaining a clock signal by dividing the commercial power frequency (50Hz or 60Hz), and a method of obtaining a clock signal as an oscillation element, for example. There is a method of obtaining a clock signal by using a crystal oscillator and dividing its oscillation frequency. In this case, in terms of accuracy of h1, it is better to obtain a clock signal by dividing the commercial power supply frequency, but there is a problem that the commercial power supply frequency disappears in the event of a power outage. Sometimes, time is measured using a clock signal obtained from the frequency of the commercial power supply, and when the commercial power supply is interrupted, time is measured using a clock signal obtained from a crystal oscillator.

FIG. 6 shows a block diagram of a timing device in a conventional electronic watt-hour meter that can be set in multiple time zones.

In FIG. 4, reference numeral 1 denotes a microprocessor responsible for the control necessary for metering the amount of electricity. 7 is input, and this pulse signal is divided into 1150 or ]/60 to divide the oscillation frequency of the crystal oscillator 4 and the frequency divider 3 divides the clock signal with a period of 1 second. An interrupt processing circuit 6 which interrupts the microprocessor 1 to perform a necessary operation every time a one-second period clock signal obtained by dividing the frequency by the circuit 5 and obtaining it by the circuit 7 is input, and divides the frequency when the commercial power supply is turned on. A change-over switch 7 is connected to the output end (power-on side) of the frequency divider 3, and is switched to the output end (power-out side) of the frequency dividing circuit 5 in the event of a power outage of the commercial power supply, and a clock signal input through the change-over switch 7. When a power outage of the commercial power source is detected by the power outage detection circuit 9 and the power outage detection circuit 9, the power outage processing circuit 10 switches the changeover switch 7 from the energized side to the outage side in response to the detection signal.

Note that the frequency divider circuit 5 is blocked from outputting a clock signal when no power failure detection signal is input from the power failure detection circuit 9, and outputs a clock signal when a power failure detection signal is input from the power failure detection circuit 9. It looks like this.

Here, the interrupt processing circuit 6 in the microprocessor is
This is provided for the following reasons.

In other words, electronic watt-hour meters obtain the power necessary for control operations from batteries when the commercial power supply goes out, so in order to minimize battery consumption, the electronic circuit inside the watt-hour meter should not be operated as much as possible. There is a need to. In particular, a microprocessor, which is the core of a power meter system, consumes a large amount of power during operation.

Therefore, during a power outage, the microprocessor is kept in standby mode as shown in the flowchart shown in Figure 7, and when a clock signal is input to the interrupt processing circuit 6, an interrupt is sent to the microprocessor and the time counter A count operation of 8 is started, and when the operation is completed, the device is put into a standby state so that battery consumption is minimized.

In an electronic watt-hour meter equipped with a timekeeping device configured as described above, when the commercial power supply is energized, the selector switch 7 switches to the frequency divider 3.
connected to the side. Further, a pulse signal corresponding to a commercial power supply frequency of 50H2 or 60 Hz is inputted to the frequency dividing circuit 3 from the waveform shaping circuit 2. Therefore, the time counter 8 counts the 1 second cycle clock signal obtained from the frequency divider 3 to measure time. In this case, the 1 second period clock signal obtained by dividing the oscillation frequency of the crystal oscillator 4 by the frequency dividing circuit 5 is not input to the interrupt processing circuit 6.

In such a state, when the power failure detection circuit 9 detects a power outage in the commercial power supply, the power outage processing circuit 10 switches the selector switch 7 from the energized side to the power outage side, and at the same time, the frequency dividing circuit 5 outputs a 1 second cycle clock. Allow signal output.

Therefore, a clock signal is input from the frequency dividing circuit 5 to the interrupt processing circuit 6, and when the microprocessor is activated, the π1 hour counter 8 counts the clock signal. When the counting operation of the time counter 8 is completed, the time counter 8 enters a standby state until the next clock signal is input. Such an operation is repeatedly executed every time a clock signal is input from the frequency dividing circuit 5 to the interrupt processing circuit 6, and the time counter 8 advances the clock every time a clock signal with a period of one second arrives.

(Problem to be Solved by the Invention) In this way, when the commercial power supply is energized, the clock signal with a period of 1 second obtained by dividing the commercial power supply frequency is sent to the time counter 8.
In the event of a power outage, a clock signal obtained by dividing the oscillation frequency of the crystal oscillator 4 is inputted to the time counter 8 to maintain the function of the timer even in the event of a power outage of the commercial power supply.

However, in an electronic watt-hour meter equipped with such a timing device, when the commercial power supply changes from a power outage state to a power-on state,
When the selector switch 7 is switched from the power outage side to the energization side, the clock signal obtained from the frequency divider 3 that divides the commercial power frequency is again input to the time counter 8, but at this time, the following problem occurs. .

That is, in FIG. 8, when the commercial power supply is currently in a power outage state, a clock signal with a period of 1 second is inputted to the time counter 8 from the frequency dividing circuit 5 of the crystal oscillator 4 as shown in period A. In this state, when the commercial power supply is turned on at time t1, the frequency divider 3 that divides the commercial power frequency divides the clock signal generated every second, starting from time t1, as shown in period B. It is input to the time counter 8. At this time, at time L1, that is, when the changeover switch 7 switches from the power outage side to the energization side, the period of the clock signal input from the frequency dividing circuit 5 of the crystal oscillator 4 to the π1 hour counter 8 and the AC power frequency are divided. Since the period of the clock signal input from the frequency divider 3 to the time counter 8 is not synchronized, there is a possibility that there will be a shift of up to 1 second as shown in period C when switching from a power outage to a power supply. . Therefore, electronic watt-hour meters that have a timing device for setting multiple time zones integrate the measured values separately depending on the time zone, resulting in errors in the measurements for each time zone. There was a point.

The present invention was made in view of the above-mentioned problems.
The purpose is to provide a highly accurate electronic watt-hour meter that does not produce time measurement errors even when the commercial power supply changes from a power outage state to a power supply state and the source of the clock signal used for time measurement switches from the oscillation element to the commercial power supply side. be.

[Structure of the Invention] (Means for Solving the Problem) In order to achieve the above object, the present invention includes a time counter that measures a set time period, and a frequency dividing means that divides the commercial power frequency and uses it as a reference. The first generator generates a periodic blackout signal.
a second clock source that generates a reference period clock signal by dividing the oscillation frequency of the oscillation element by a frequency divider circuit, and a clock generated from the first clock source when the commercial power supply is energized. A timekeeping device comprising a switching means for inputting a signal to the timekeeping counter, and switching means for switching to the second clock source when the commercial power supply is interrupted and inputting a clock signal generated from the second clock source to the timekeeping counter. In the electronic watt-hour meter, the second
A clock signal generated from a clock source is inputted, and when the commercial power source is energized, the output of this clock signal is blocked, and when the commercial power source is out of power, the output of the clock signal is allowed and input to the time counter; a control circuit that generates one clock signal and inputs it to the time counter immediately after the commercial power source changes from a power outage state to a energized state; and reset means for resetting the frequency dividing means of the first clock source in synchronization with one clock signal.

(Function) In the electronic watt-hour meter having such a configuration, immediately after the commercial power supply changes from a power outage state to a energized state, one clock signal generated from the control circuit is input to the time counter, and a clock signal is input to the time counter. Since the frequency dividing means of the clock source No. 1 is cleared, this frequency dividing means inputs the clock signal of the reference period to the time counter starting from that point in time. Therefore, the commercial power supply changes from a power outage state to a energized state and the second
Even if the clock source is switched from the first clock source to the first clock source, it is possible to input a clock signal synchronized with the reference period of both clock sources to the time counter, and it is possible to prevent a time measurement error in the time counter.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an example of the circuit configuration of an electronic watt-hour meter according to the present invention. Parts that are the same as those in FIG. 6 are given the same symbols, and the explanation thereof will be omitted, and only the different points will be described here. In this embodiment, as shown in FIG. 1, when a clock signal with a reference period obtained from a frequency dividing circuit 5 of a crystal oscillator 4 is input, and a power outage of the commercial power supply is detected by a power outage detection circuit 9, the reference period is changed. The control circuit 1 provides a clock signal to the interrupt processing circuit 6 in the microprocessor 1 and the power outage side terminal of the changeover switch 7. This control circuit 1] includes D flip-flops 12-1. ．． 12-2 and A
The output of the frequency divider circuit 5 is applied to the input terminal (Ck) of the D flip-flop 12-1 in the previous stage, and the output from the microprocessor 11 is applied to the reset terminal (R). A reset signal is input. The input terminal (C
The output of the output terminal of the D flip-flop 12-1 at the previous stage is applied to k), and the output (PD) of the power failure detection circuit 9 is applied to the reset terminal (R). Furthermore, AND
The output of the output terminal of the D flip-flop 12-1 in the preceding stage and the output of the inverted output terminal of the D flip-flop 2-2 in the succeeding stage are applied to the gate 13, and when the AND condition of both forces is satisfied, a clock signal is generated. Output. Therefore, as is clear from the time chart shown in Figure 3,
When a power outage of the commercial power supply is detected by the power outage detection circuit 9, a clock signal of the reference period inputted from the frequency dividing circuit 5 is given to the interrupt processing circuit 6 in the microprocessor 1 to cause the microprocessor 1 to perform an interrupt operation. , This interrupt operation generates a reset signal and is reset. Immediately after the commercial power supply is turned on, the control circuit 11 generates a clock signal P having one reference period.

On the other hand, a reset signal is input from the control circuit 1 to the frequency divider 3 that divides the commercial power frequency in synchronization with one clock signal generated immediately after the commercial power supply changes from a power outage state to a energized state. That's how it is. In this case, the reset signal is generated by an interrupt operation of the microprocessor 1.

Next, the timing operation of the electronic watt-hour meter constructed as described above will be described with reference to the time chart shown in FIG.

When the commercial power source is energized, the changeover switch 7 is connected to the energized side end, so the time counter 8 measures a one-second cycle clock signal generated by the frequency divider 3 that divides the frequency of the commercial power source.

When a power outage occurs in the commercial power supply in such a state, the changeover switch 7 is switched from the energized side end to the power outage side end by the output of the power outage detection circuit 9, and at the same time, the control circuit 11 switches the frequency dividing circuit 5 of the crystal oscillator 4. A clock signal with a period of 1 second inputted from the interrupt processing circuit 6 is applied to the interrupt processing circuit 6. Every time a clock signal is input to the interrupt processing circuit 6, the microprocessor 1 performs an interrupt operation, and the time counter 8 measures the clock signal output from the control circuit 1.

Thereafter, when the commercial power supply is turned on at time ti, the frequency divider 3 starts counting from that time, or immediately after that, one clock signal P generated from the control circuit 11 causes the microprocessor to perform an interrupt operation, and the clock is simultaneously counted. Counter 8 measures the clock signal. At this time, a reset signal generated by the interrupt operation of the microprocessor 1 is applied to the frequency divider 3, so the count value of the frequency divider 3 up to that point is cleared, and counting is restarted from this point, and the power failure processing circuit Selector switch 7 by 10
is switched to the current-carrying end.

Therefore, a clock signal with a period of 1 second is inputted to the time counter 8 from the frequency divider 3 in synchronization with one clock signal P generated from the control circuit 11, so that at the time of switching from commercial power outage to energization, Also, there is no deviation in the period of the clock signal, and highly accurate time measurement can be performed.

FIG. 5 shows a flowchart of the timekeeping operation within the microprocessor when the commercial power supply is turned on and when the power is switched on from a power outage.

In this way, according to the present embodiment, when the commercial power supply changes from power outage to power on, the control circuit 11 generates one clock signal No. 8, and the clock signal generated by the frequency divider 3 that divides the commercial power frequency. Since the timing counter 8 is synchronized with the reference period of Even if it ffi values are integrated separately depending on the time zone, errors will not occur in measurements for each time zone.

In the above embodiment, the frequency divider 3 in the microprocessor 1 may be realized by software.

In addition, the reference period of the clock signal was set to 1 second, but 0.5
It may also be a reference period such as seconds. Furthermore, the oscillation frequency of the crystal oscillator 4 is divided by the frequency dividing circuit 5 to be obtained as a clock source during a power outage. However, if there is an alternative to the crystal oscillator 4, other oscillation elements may be used Needless to say, it's a good thing. In addition, the present invention can be implemented with various modifications without changing the gist thereof.

[Effects of the Invention] As described above, according to the present invention, even if the commercial power source changes from a power outage state to a power-on state and the source of the clock signal used for timekeeping switches from the oscillation element to the commercial power source side, a timing error does not occur. It is possible to provide an electronic watt-hour meter equipped with a highly accurate timing device.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing an embodiment of an electronic watt-hour meter equipped with an old-fashioned device according to the present invention, FIG. 2 is a detailed diagram of a control circuit in the same embodiment, and FIG. FIG. 4 is a diagram showing a time chart for explaining the timekeeping function of the same embodiment. FIG. Figure 6 is a block circuit diagram showing an electronic watt-hour meter equipped with a conventional timekeeping device; Figure 7 is a flowchart of the microprocessor's timekeeping operation during a power outage in the same device. FIG. 8 is a diagram showing a time chart for explaining the timekeeping action. ]...Microprocessor, 2...Waveform shaping circuit,
3... Frequency divider, 4... Crystal oscillator, 5... Frequency dividing circuit, 6... Interrupt processing circuit, 7... Selector switch, 8
...Time counter, 9...Power failure detection circuit, 10...
- Power outage processing circuit, 1]...control circuit. Applicant's agent Patent attorney Takehiko Suzue] 7

Claims (1)

[Claims] A clock counter that clocks a set time period, a first clock source that generates a reference period clock signal by dividing the commercial power frequency by a frequency dividing means, and a frequency dividing circuit that divides the oscillation frequency of the oscillation element. A second clock source that cycles and generates a clock signal having a reference period, and a clock signal generated from the first clock source when the commercial power source is energized are input to the time counter, and when the commercial power source is turned on, the clock signal generated by the first clock source is input to the time counter. In an electronic watt-hour meter, the electronic watt-hour meter is equipped with a timekeeping device comprising switching means for switching to a second clock source and inputting a clock signal generated from the second clock source to the time counter. A generated clock signal is input, and when the commercial power source is energized, the output of this clock signal is blocked, and when the commercial power source is out of power, the clock signal is allowed to be output and input to the time counter, and when the commercial power source is out of power, the clock signal is input to the time counter. a control circuit that generates one clock signal and inputs it to the time counter immediately after the state changes from a power-on state to an energized state; and one clock that is generated by the control circuit immediately after the commercial power source changes from a power outage state to an energized state. An electronic watt-hour meter comprising: reset means for resetting the frequency dividing means of the first clock source in synchronization with a signal.