JPS5929974B2 - Condition monitoring device for analog-to-digital converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an analog-to-digital conversion system, and is intended to promptly detect circuit abnormalities and failures and provide a highly reliable device.

Analog information is transferred to computers and microprocessors.
When processing data using a computer, an A/D converter is indispensable.

In the case of systems that protect and control power systems using computers, which have recently been used for protection, monitoring and control of large power systems, A-D converters play a large role, unlike in other fields, and their reliability is important. It is no exaggeration to say that the reliability of the entire system is affected by this.

The reason for this is not so much the protection function that detects faults in the power system, but also the high-speed sampling, wide range of A-D conversion from small inputs at normal times to large inputs in the event of an accident, and the ability to detect errors in sampling. This is because it is considered necessary.

FIG. 1 shows a typical block diagram of this type of A-D converter.

In the figure, 1 is an analog sensor, and the analog information detected by this analog sensor 1 is filtered through filter circuits 2o to 2n to remove aliasing errors caused by sampling, and the output of this filter is sent to the next stage sampling hold circuit 3. ~3n, and is sampled and held at a certain sampling frequency.

4 is a multiplexer circuit that switches a plurality of analog inputs, which uses the A-D converter circuit 5 in time division to convert into digital quantities, and inputs this digital output to the data processing circuit 6. Generally, predetermined data processing is performed using the following steps.

The problem with this A-D converter is that the input from the analog sensor 1 is filtered through the filter circuit 2 → sampling hold circuit 3 → multiplexer circuit 4 → A-D.
In the process of digital conversion through the conversion circuit 5, it is detected whether each circuit in the middle is operating normally.

That is, when a system fault occurs, the sensor side responds transiently, and this effect makes it impossible to detect using conventional methods.

As a means to solve this problem of transient response, a configuration as shown in FIG. 2, for example, can be considered.

That is, two A-D converters having the same configuration as shown in FIG.
A comparison circuit 1 shown in the figure compares and judges the outputs of these A/D converters A and B to detect errors in each circuit.

In Fig. 2, the same parts as in Fig. 1 are given the same reference numerals, and parts with the same functions as in Fig. 1 are given the same numbers.
/ II is attached.

In this way, by preparing two sets of A-D converters with the same configuration and comparing the Ryokawa power, the conventional problems can be solved, and errors in each circuit in response to sampling can be detected. .

However, even if configured as shown in the figure, for example, A, 8
It can be pointed out that it is impossible to detect errors due to common factors in both blocks.

That is, it is impossible to detect abnormalities caused by common factors such as power supply, surge, noise, temperature change, etc., which can cause errors in both blocks A and B in the same way.

The present invention was invented in view of the above points, and will be described in detail below based on the embodiments shown in FIGS. 3 and 4.

FIG. 3 shows an embodiment according to the present invention, and the same parts as in FIGS. 1 and 2 are given the same reference numerals.

In the figure, 8° to 8n are polarity inverting circuits, which have the function of simply reversing the polarity without changing the value of the input analog signal. , filter circuit 2゜, 2n', sampling hold circuit 3゜, 3n', multiplexer circuit 4゜'4n')
A l) Conversion circuit 5', 5', polarity inversion circuit 8°, g
n'(7) Except for errors in each circuit, they match in terms of time and absolute values, and the polarities are simply reversed.

Therefore, data errors can be detected by comparing the two blades.

T is a comparator circuit that takes into account the error and compares each A-D converter A.
, B are calculated and compared for each sampling, and it is determined whether the values are within a set value.

Reference numeral 6 denotes a data processing circuit, which performs processing operations on the A-D converted data 10, 10' based on the comparison result 9 of the γ comparison circuit, and this processing circuit includes, for example, a CPU,
A computer such as a microprocessor can be considered.

Note that the polarity inversion circuit 8 only needs to have the function of simply inverting the polarity without changing the value of the input analog signal, so it can also be configured with a phase inversion circuit using, for example, an operational amplifier. When dealing with analog quantities such as voltage and current in a power system, the frequency range is limited, so there is no need to provide a polarity reversal circuit. It can be easily configured using a transformer as shown in the figure.

That is, the embodiment shown in Fig. 5 has two windings on the secondary side of the transformer, and the output has opposite polarity and is applied to both blocks A and 8, whereas the embodiment shown in Fig. 6 is a transformer with the same characteristics. A by using two devices and connecting the primary side with opposite polarity.

The voltage is applied to eight blocks.

With this configuration, not only the circuit configuration can be simplified, but also a defect in the transformer inserted into a part of the analog sensor can be detected.

Although the embodiments shown in Figures 5 and 6 are explained using a voltage transformer, the same concept can be applied even when a current transformer is used, with the only difference being the connections. Needless to say, there is nothing to gain from it.

As described above, the present invention implements two sets of A-reconverting elements with the same configuration and the same function, applies a regular analog input to one, and
The idea is to apply an input of opposite polarity to the other side and monitor the output signal with comparator circuit 1 to detect data errors and abnormalities in the constituent circuits, but simply applying the analog input with opposite polarity in this way This provides various effects as described later.

FIG. 4 shows another embodiment according to the present invention, and the same parts as in FIGS. 1, 2, and 3 are given the same reference numerals. By newly inserting a check signal generation circuit 11 into the one shown in the figure, it is also possible to check the comparison circuit 7.

That is, A from the inspection signal generation circuit 11 as shown in the figure.

When a predetermined signal is input to the multiplexer circuits 4 and 4' of the B block, since both blocks A and 8 always operate with opposite polarity, the comparator circuit γ's own signal changes in accordance with the switching cycle of the multiplexer circuit 4°4'. As the inspection signal generating circuit 11, a relatively simple one can be applied as long as it can detect a non-operational failure and simply generate a predetermined signal.

As described above, in the present invention, two sets of A-D converters having the same configuration and the same function are prepared, and the analog signals input to these devices are simply applied with opposite polarities. Since it is designed to constantly monitor itself, it has various effects as shown below.

■ If any of the filter circuits, sampling hold circuits, multiplexer circuits, and A-D conversion circuits break down or make errors, this can be detected by sampling or bit processing, greatly increasing the reliability of the data and the device itself. can be improved.

■ By making the input signals have opposite polarities and always operating the two sets of component circuits in opposite directions, it is possible to detect errors caused by disturbances acting in the same direction, such as noise, surges, and ground potential fluctuations.

(2) For the same reason as (2), it is also possible to detect errors due to common factors in the device, such as fluctuations and abnormalities in the control power supply that drives the circuit, and temperature changes.

■ The comparison circuit 1 in FIG. 3 is the A-D conversion circuit 5.
, 5' simply perform a sum operation based on the positive and negative polarity of the digital outputs, and check whether the result is zero.
Unlike conventional devices, there is no need to perform complicated difference calculations or comparison calculations, and the circuit configuration is simplified, which is advantageous in terms of cost.

[Brief explanation of drawings]

FIG. 1 is a typical block configuration diagram of an A-D conversion device, FIG. 2 is a specific block configuration diagram when status monitoring is performed using a conventional method, and FIGS. 3 and 4 are one implementation according to the present invention. FIGS. 5 and 6 are block diagrams illustrating specific examples in which a polarity inverting circuit according to the present invention is inserted into a part of an analog sensor. 1 is an analog sensor, 28 to 2n, 25 to 2n' are filter circuits, 3o to 3n, 3. )' to 3n' are sampling and hold circuits, 4 and 4' are multiplexer circuits, 5 and 5' are A-D conversion circuits, 6 is a data processing circuit, T is a comparison circuit, 8o to 8n are polarity inversion circuits, and 11 is a Inspection signal generation circuit, A and B are A-D converters.

Claims (1)

[Claims] In a system that constantly monitors the state of an analog-to-digital conversion device that converts 11 or more analog input quantities into digital quantities at a certain sampling frequency, an analog quantity is detected. Some analog sensors and
Analog circuits with the same configuration and functions, consisting of a filter circuit, a sampling hold circuit that holds the analog input amount, a multiplexer circuit that switches the analog input at a predetermined cycle, and an A-D conversion circuit that converts the analog input into a digital signal. - 2 digital conversion devices
A circuit for converting an analog input signal to the opposite polarity is provided on the input side of one analog-to-digital converter, and a regular analog signal is input to one analog-to-digital converter, while the other An analog device characterized in that a signal having a polarity opposite to that of a regular analog signal is input to the analog-to-digital converter, and the digital outputs of each analog-to-digital converter are compared to monitor the status of each part. - Condition monitoring devices for digital converters. 21 or a plurality of analog input quantities into digital quantities at a certain sampling frequency. ,
Analog circuits with the same configuration and functions, consisting of a filter circuit, a sampling hold circuit that holds the analog input amount, a multiplexer circuit that switches the analog input at a predetermined cycle, and an A-D conversion circuit that converts the analog input into a digital signal. - 2 digital conversion devices
A circuit for converting an analog input signal to the opposite polarity is provided on the input side of one analog-to-digital converter, and a regular analog signal is input to one analog-to-digital converter, while the other A signal of opposite polarity to the regular analog signal is input to the analog-to-digital converter, and a check signal from the check signal generation circuit is input to each multiplexer circuit to convert the digital output of each analog-to-digital converter. A condition monitoring device for an analog-to-digital converter, characterized in that the condition of each part is monitored by comparison. 3 As a circuit that converts an analog input signal to reverse polarity,
A patent claim in which two sets of current transformers or voltage transformers with the same characteristics and reversely connected secondary sides are applied, and the transformers are integrated with a part of the analog sensor. A condition monitoring device for an analog-to-digital converter according to item 1 or 2. 4 As a circuit that converts an analog input signal to reverse polarity,
Claims that apply two sets of current transformers or voltage transformers with the same characteristics and reversely connected primary sides, and the transformers are integrated with a part of the analog sensor. A state monitoring device for an analog-to-digital converter according to item 1 or item 2.