JPH04130911A - Voltage monitor - Google Patents

Abstract

PURPOSE:To inform a signal for determining the operation of whole system to the system by forecasting a change in the characteristics of a power supply to be used when abnormality occurs in the power supply, and forecasting a period in which the system can be normally driven. CONSTITUTION:The power supply 1 supplies voltage to a digital circuit system including a microcomputer. A voltage measuring instrument 3 detects the power supply voltage and a time forecasting means 4 for forecasting a time to be consumed up to the power supply comes to abnormal by inputting the detection signal forecases the time to be consumed up to the power supply comes to abnormal based upon a current power supply voltage. A degree deciding means 5 for deciding the degree of the power supply up to the power supply comes to abnormal decides the generation speed of abnormality in the power supply based upon the forecasted value and sorts the degree up to the abnormality into several levels and the degree up to the power supply comes to abnormal is informed to the system 2 by a means 6. Thereby, the system 2 can protect the system itself in accordance with several grades corresponding to the sorts of information signals.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a voltage monitoring device having a function of predicting voltage abnormalities of a monitored object.

[Prior Art] FIG. 5 is a block diagram of a conventional voltage monitoring device shown in, for example, 89° Mitsubishi Semiconductor Data Book Analog ASSP/General Purpose Linear IC Edition, pages 7-32 to 7-38.

A power source to be monitored to obtain a DC voltage by connecting an AC power source (
1) The voltage between Vcc and 250
), a power supply voltage monitoring device (15) and a digital circuit system (2) having a microcomputer. The power supply voltage monitoring device (15) includes a level converter (12), an input terminal comparison circuit (40), and a delay generation circuit (50).
) is supplied with the output voltage of the level converter (12). The voltage of the reference power supply (41) is applied to the positive input terminal of the comparator (42). The voltage of this reference power supply (41) is set to a voltage value related to the voltage at which the digital circuit system (2) having a microcomputer operates normally. The output of this comparator (42) is
A constant current source is provided to the base of the switching transistor (52) whose emitter is grounded in the delay generation circuit (50), and whose collector is connected to the positive electrode of the power source (1) on the input side. The output side of (51) is connected.

The collector of the switching transistor (52) is connected to the positive input terminal of the comparator (53) and grounded via a time constant capacitor (60). The voltage of the second reference power supply (54) is applied to the negative input terminal of the comparator (53). Comparator (53
) output is a digital circuit system with a microcontroller (2)
given to.

Next, the operation of the voltage monitoring device will be explained. When the voltage of the power supply (1) drops, the digital circuit system with a microcontroller (2)
) is in a state where there is a risk of malfunction, the output voltage of the level conversion circuit (12) decreases in proportion to the voltage of the power supply (1). Therefore, the output of the comparator (42) becomes "H" level, and the switching transistor (5
2) turns on. Then, the time constant capacitor (
60) is discharged through the switching transistor (52), the output of the comparator (53) becomes "L" level, and the output is notified to the digital chill circuit system (2) that includes the microcomputer. The digital circuit system (2) that has the power supply (1) can know that the voltage of the power supply (1) is abnormal and stop the system operation to prevent malfunctions caused by its own voltage drop.

[Problems to be Solved by the Invention] Conventional power supply monitoring devices determine whether the power supply is abnormal or normal based on one voltage level at a certain time.
It detects abnormalities in the power supply at a voltage slightly higher than the minimum operating voltage of the system, and when used as a power supply monitoring device for a system designed to save important information, it is highly dependent on the characteristics of the power supply used. There was a problem. In other words, when designing a system, it is necessary to estimate the time from when the power supply output begins to decrease until it reaches the minimum operating voltage, and the worst value of the measured data must be used to determine the detected voltage value and the amount of information to be saved. In addition, since it depends on the characteristics of the power source itself, there is a problem that it is not possible to cope with changes in characteristics due to changes in the power source over time.

The present invention was made to solve these problems, and when a power supply abnormality occurs, it is possible to predict changes in the characteristics of the power supply being used. It is an object of the present invention to provide a power supply monitoring device that can notify a system of a signal for determining the operation of the entire system by predicting whether the system will operate or not.

[Means for Solving Eight Problems] The power supply monitoring device according to the present invention includes a voltage measuring device that measures the power supply voltage to be monitored, a voltage measuring device that calculates the drop rate of the power supply voltage from the measured data, and uses this value. The system is equipped with means for predicting the time until the power supply voltage becomes abnormal based on the predicted time, and means for determining the extent to which the power supply becomes abnormal based on the predicted time and notifying the system.

[Operations] In this invention, the power supply voltage to be monitored is acquired at certain time intervals, the change in the power supply voltage is calculated based on this value, the time until a power supply abnormality is predicted, and the predicted time is calculated. Based on this, the system is notified of the degree of power failure.

In this way, the characteristics of the power supply are monitored in real time, so there is no need to estimate the worst characteristics of the power supply at the time of design, and changes over time can be accommodated.

Embodiment FIG. 1 is an overall configuration diagram of an embodiment of a voltage monitoring device according to the present invention. In this embodiment, as is clear from FIG. 1, a power supply (1) supplies voltage to a digital circuit system (2) having a microcomputer. This power supply voltage is detected by a voltage measuring device (3), and the time until power supply abnormality prediction means (4) which receives this detection signal as input predicts the time until power supply abnormality occurs from the current power supply voltage. Based on this predicted value, the degree judgment method (5
) to determine how quickly the power supply will become abnormal, classify the level into several levels, and notify the degree to which the power supply malfunctions (6), using a digital circuit system with a microcomputer (2) ). As a result, the digital circuit system (2) having a microcomputer can protect itself in several grades depending on the type of notification signal.

FIG. 2 is a circuit diagram showing the electrical connections of the embodiment of FIG. 1. In the figure (14) is a microcomputer in the power supply voltage monitoring device (15), which includes an input circuit (7) and a memory (
8) , (:Pl] (9) , has an output circuit (10). Also, (3) is a voltage measuring device, which measures the voltage f.
It consists of a level converter (12) that converts the voltage of i (1) to an appropriate range and an A/D converter (11) that converts the output into digital.

Next, the operation of the above embodiment will be explained with reference to FIGS. 3 and 4. Figure 3 shows a microcomputer (14)
FIG. 4 is a flowchart showing the power supply voltage abnormality detection program stored in the memory (8) of the power supply (1), and is an explanatory diagram of the operation of predicting and detecting the voltage abnormality of the power supply (1).

When the digital circuit system (2) with a microcomputer starts normal operation, the power supply voltage monitoring device (15) starts operating and the power supply voltage V is started. is sampled and stored in the memory (8) (step 2 [) in Fig. 3]. Next, for a certain period of time (
δt) Wait without doing anything (Step 22) Sample the next power supply voltage v1 and store it in the memory (8) (Step 23) Here, the power supply voltage values at different sampled times stored in the memory (8) Using v0 and Vl, it is determined whether vl has become smaller than the predicted start voltage Vstart, and (1) has become smaller than vo (stub 24). If either of the two conditions is not met, it can be determined that the power supply is not moving in the downward direction, and there is no need to predict the time until the power supply malfunctions, so the power supply voltage value v1 in the memory (8) is newly considered as vo,
(2) is stored in the location where vo was stored in the memory (8). Step 25) is performed again in order from step (22) to sample vl anew and continue monitoring the power supply. If both conditions are satisfied, it is necessary to predict the time until the voltage abnormality occurs, and in step (26), the time T until the power supply abnormality occurs is predicted.

The prediction method in step (26) is as shown in Fig. 4, where the horizontal axis is time and the vertical axis is power supply voltage. Using the point A of the power supply voltage value v0 of It can be seen from FIG. 4 that the lowest operating voltage VEMG is reached after one hour. Further, the time T until the lowest operating voltage VEMG is the current power supply voltage value v1, the time interval δt,
Power supply voltage V δ7 hours before the present. , minimum operating voltage value V
It can be obtained from EMG as shown below.

T=v, bi-parked −δ1 −−−−−−−−−−−
■VO-V.

Next, the time T to the lowest operating voltage calculated here and the constant value T used to determine whether the degree of voltage drop is fast or slow.
If T is smaller than Tα (Step 27) in Figure 3 compared to α, it is assumed that the time T required to reach the minimum operating voltage is short (Step 28), leading to an abnormality in the digital circuit system (2) with a microcomputer. It is notified that the time until the end is short (step 29). Furthermore, if T is larger than Tα, it is determined that the time T required to reach the minimum operating voltage is long (step 30), and the digital circuit system (2) including the microcomputer is notified that it takes a long time to reach the abnormality. (Step 31). In a digital chill circuit system (2) that has a microcomputer, by looking at this notification, you can know the degree to which the power supply will fail, and you can decide whether more work can be done to protect the system and take appropriate action. . After this, in order to continue monitoring the power supply, the memory (8
) New power supply voltage value V, ■. Thinking about this, the memory (
8) V in. In step 32), vl is stored in the location where it was stored, and steps are executed again in order from step (22). From then on, the above is repeated.

In addition, in the above embodiment, the time T until the lowest operating voltage is reached
By comparing Tα with a constant value Tα, the digital circuit system (2) with a microcomputer is notified of the time to abnormality in two states: long and short. However, by using multiple types of constant values, By having multiple notification processes based on comparisons and judgments such as those in steps (27) to (31), it is possible to notify the digital circuit system (2) having a multi-state microcomputer of the degree of power failure. Allows for more detailed system protection. In addition, the formula (■) is used to calculate the time T until the minimum operating voltage is reached, but the calculation of the time T can be done not only by a linear approximation method such as the formula (■), but also by using the power supply voltage values at several points in the past. Needless to say, there are methods of weighted averaging and curve approximation. Further, although this embodiment describes a digital circuit system having a microcomputer, it is clear that similar effects can be obtained in general systems using a DC power supply as the power supply voltage. Furthermore, in the above embodiment, the DC voltage on the secondary side of the power supply (1) is monitored, but if we consider the monitoring of the AC voltage on the - secondary side of the power supply (1), step (3) in FIG. When sampling the power supply voltage in steps 21) to (23), δt is the cycle of the AC power supply, and the −th sample is the peak voltage value.

, vl contains the peak voltage value in each cycle, and the minimum operating voltage in this example is the minimum operating voltage on the primary side of the power supply (the minimum operating voltage on the secondary side cannot be normally supplied as a power supply). It can also be seen that the same effect as in the embodiment can be obtained by considering the voltage value on the primary side to be obtained.

[Effects of the Invention] As described above, according to the present invention, the power supply voltage to be monitored is acquired at certain time intervals, the change in the power supply voltage is calculated based on this value, and the time until a power supply abnormality occurs is calculated. predict,
Since the system is configured to notify the extent to which the power supply will become abnormal based on the predicted time, the characteristics of the power supply side can be monitored in real time, and the degree to which the power supply will become abnormal can be appropriately notified according to changes in the power supply side. can.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of a voltage monitoring device according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing electrical connections of the embodiment of FIG. 1, and FIG. 3 is a flowchart showing its operation. 4
The figure is a diagram for explaining its operation, and FIG. 5 is a block diagram of a conventional power supply monitoring device. In the figure, (1) is a power supply, (2) is a digital circuit system with a microcomputer, (3) is a voltage measuring device, (4) is a means for predicting the time until voltage abnormality, and (5) is the time taken until voltage abnormality occurs. degree determination means, (6) means for notifying the degree to which voltage abnormality occurs, (14) a microcomputer, (15)
) is a power supply voltage monitoring device. In addition, the same symbols in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] In a voltage monitoring device that detects voltage abnormalities in the monitored target and prevents malfunctions in digital circuit systems that include microcontrollers, it is possible to predict the time it will take for the system to malfunction based on periodically detected changes in the monitored voltage. A voltage monitoring device characterized in that it notifies the system of a signal that allows the operation of the entire system to be determined according to a predicted value.