JPH0836001A - Voltage detecting circuit - Google Patents

Abstract

PURPOSE:To provide a voltage detecting circuit, of which two detecting parts of an over-voltage detecting part and a low-voltage detecting part are formed out of one circuit and which has excellent productivity. CONSTITUTION:This voltage detecting circuit is provided with a power source voltage circuit and a microcomputer 50 connected to the power source voltage circuit and having an A/D port 51. A data table, in which a reference voltage is stored as the data for judgment of over-voltage or low-voltage when the driving condition of a load is detected, and a comparing part for comparing the data of the data table with the power source voltage input to the A/D port 51 are provided in the microcomputer 50.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to voltage detection of electric equipment, and more particularly to a circuit for comparing a reference voltage with a power supply voltage to be supplied to detect an overvoltage or a low voltage.

[0002]

2. Description of the Related Art Currently, as a power source for operating electrical equipment,
A 100-volt commercial power source and a 200-volt industrial power source are widely used. Both commercial power supplies and industrial power supplies are generally introduced in factories, and in recent years, they have begun to spread to general households when home electric appliances such as air conditioners are used.

However, the shapes of the outlets at the ends of the two power sources are almost the same, and in the process of wiring work or the process of use by the consumer, for example, commercial electric power is used for industrial electric equipment. , Or conversely, an electric device that uses a commercial power supply may be connected to an industrial power supply. In the former case, it is often sufficient that the device does not operate because the voltage is insufficient, but in the latter case, the device is often damaged.

Assuming the above-mentioned problem, in order to eliminate this problem in advance, conventionally, the following voltage detection circuit is added to the electric equipment to detect the overvoltage. In FIG. 4, which shows a block diagram of the prior art, there is a voltage rectifying element 15 connected to a commercial power supply 10, and a power supply voltage circuit 20 and a reference voltage circuit 40 connected in parallel to this output section. 20 and reference voltage circuit 40
And a warning circuit 80 connected to the voltage judgment circuit 60, and a warning device 90 is connected to the warning circuit 80. In the above description, the reference voltage circuit 40 and the voltage determination circuit 60 are a voltage detection unit.
In addition, in the above circuit, two voltage detectors are provided in parallel in order to detect an abnormal voltage drop at the same time when the overvoltage is detected.

With the above structure, the comparator in the voltage determination circuit 60 compares the voltage input to the electric device with the reference voltage generated by the reference voltage circuit 40, and the voltage input to the electric device is normal. It is determined whether or not there is an abnormal voltage, and if the voltage is abnormal, the alarm circuit 80 is activated and the alarm device 90 is driven.

[0006]

As is well known, the general ten
Electric equipment using 0 volt is designed to operate within at least 85 to 110 volt in consideration of some variations in supply voltage.
In the above-mentioned conventional circuit, for example, in an electric device that uses a power supply of 100 V, an overvoltage detection unit in the case of being connected to an outlet of 200 V and a low voltage in which a voltage drop due to so-called octopus wiring is assumed. Two voltage detectors, that is, the detector, are required, and the circuit configuration is complicated.

Further, in the conventional circuit, the reference voltage circuit 40
The reference voltage created in 1 is adjusted in the manufacturing process, and this working process is complicated.

The present invention has been made in view of the above problems, and provides a voltage detection circuit having a high productivity, in which two detection units, an overvoltage detection unit and a low voltage detection unit, are formed by one circuit. With the goal.

[0009]

In order to solve the above problems, the present invention comprises a power supply voltage circuit and a microcomputer having an A / D port connected to the power supply voltage circuit, and a load is provided in the microcomputer. A voltage provided with a data table in which a reference voltage for detecting an overvoltage or a low voltage by detecting the driving state of the data table is converted into a data table, and a comparison unit for comparing the data in the data table with the power supply voltage input to the A / D port. Use as a detection circuit.

[0010]

In the conventional voltage detection circuit, the reference voltage is provided with two reference voltage circuits for overvoltage detection and low voltage detection. For example, for a supply voltage of 100 V, the overvoltage is 120 V, Although two reference voltage circuits for overvoltage and low voltage are required to determine the upper and lower reference voltages such as setting the low voltage to 80 volts, the voltage detection circuit of the present invention uses, for example, a supply voltage. Voltage is 10
If it is 0 V, the upper and lower limit voltages are determined with the 100 V as a reference voltage. Since the upper limit and the lower limit of the reference voltage are determined by the microcomputer, the width of the upper limit and the lower limit can be set arbitrarily, and the set value can be easily changed.

Further, since the processing such as the determination of the voltage value and the comparison of the input voltage value can be performed by the microcomputer, the number of constituent elements can be reduced in terms of hardware, and the reference voltage performed at the manufacturing stage can be easily determined.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A block diagram of a voltage detection circuit according to an embodiment of the present invention is shown in FIG. 1 and this circuit diagram is shown in FIG. In FIG.
A commercial power supply 10 is connected to the primary side of a transformer 12, a voltage rectifying element 15 composed of a diode stack or the like is connected to this secondary side, and a power supply voltage circuit 30 is connected to this output part.
Are connected to the arithmetic control unit such as the microcomputer 50.

As shown in FIG. 2, the power supply voltage circuit 30 is connected to an electric field capacitor 31 and a variable resistor 32 which are connected in parallel to the output part of the voltage rectifying element 15, and the variable resistor 3
The other end of 2 is connected to an A / D (analog-digital) port 51 of a microcomputer 50 through resistors 34 and 36 connected in series. The connecting portion between the variable resistor 32 and the resistor 34 is connected to the cathode of the Zener diode 33, the anode thereof is grounded, and the connecting portion between the resistors 34 and 36 is connected to one end of the resistor 35 and the other end thereof. Is grounded, one end of a capacitor 37 is connected between the resistor 36 and the A / D port 61, and the other end is grounded.

The operation of the voltage detection circuit having the above configuration will be described. In FIG. 2, the commercial power supply 10 is transformed by the transformer 12 and supplied to the secondary side of the transformer 12. This supply voltage is adjusted by the variable resistor 32 to form a reference voltage, and the A /
It is input to the D port 51. In the conventional voltage detection circuit,
The reference voltage is provided with two reference voltage circuits for overvoltage detection and low voltage detection. For example, for a supply voltage of 100 V, the overvoltage is 120 V and the low voltage is 8 V.
Although the upper and lower reference voltages are determined such as 0 volt, in the above configuration of the present invention, for example, if the supply voltage is 100 volts, the upper and lower reference voltages are set on the basis of 100 volt. The value is determined.

The Zener diode 33 in the above is A /
For protection of the D port 51, the resistors 34 and 35 are provided as an example for voltage division, and the resistor 36 and the capacitor 37 are provided as an example for noise suppression. Generally, the A / D port 5 is used.
The voltage value input to 1 is about several volts.

The voltage input to the A / D port 51 is processed according to the flowchart shown in FIG.

In the first stage, the voltage input to the A / D port 51 is subjected to analog-digital conversion (A / D conversion).

In the second step and the third step, the usage state of the electric equipment is detected. This is because the voltage input to the A / D port 51 fluctuates when a load such as a relay or motor in the device is driven, as compared with the case where these are not driven. Is provided,
In particular, data is provided assuming an overvoltage with respect to the reference voltage, and the reference voltage value at the time of overvoltage is determined.
In the microcomputer 50, there is provided a data table in which some data is stored according to the usage status of the load.

In the fourth step, the data obtained in the first step and the data obtained in the third step are compared with the reference voltage at the time of overvoltage to judge whether or not the reference voltage is exceeded. In the case where the voltage exceeds the reference value, the process proceeds to an alarm process, and although not shown in FIGS. 1 and 2, a process of driving an alarm device or stopping the operation of an electric device may be performed. If the voltage value is normal at this stage, the process shifts to voltage detection at low voltage as the fifth and sixth stages.

The fifth and sixth steps are the same as the second step and the third step except that the overvoltage reference voltage is replaced by the low voltage detection, and therefore the description thereof is omitted. The results from the 5th and 6th steps and the data from the 1st step are the 7th
It may be compared in stages, and when the voltage is lower than the reference value compared with the low voltage reference value, the alarm processing may be performed, and processing such as driving the alarm device or stopping the operation of the electric device may be performed as in the fourth step. . If the voltage value is normal at this stage, normal operation of the electric device is performed.

[0021]

According to the above structure, when an overvoltage such as an industrial power source is supplied to the commercial power source 10 connected to the outlet, or conversely, a low voltage which cannot operate the main body of the electric equipment is supplied, an abnormality occurs. It is possible to detect that a voltage is being supplied, and conventionally, the overvoltage detection circuit and the low voltage detection circuit were configured as separate voltage detection units, but it is possible to combine both detection circuits as one detection circuit. Since the number of constituent elements can be reduced, the circuit can be simplified and the degree of freedom in circuit design can be increased.

Further, in the past, there are two for overvoltage and for low voltage.
Although it was necessary (three times) to adjust the reference voltage in the manufacturing process, it was necessary. However, according to the present invention, this adjustment work is performed only once for determining the reference voltage. The complexity is eliminated.

[Brief description of drawings]

FIG. 1 is a block diagram of a voltage detection circuit according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of FIG.

FIG. 3 is a flowchart of the microcomputer of the present invention.

FIG. 4 is a block diagram of a conventional voltage detection circuit.

[Explanation of symbols]

 In the drawings, the same reference numerals indicate the same or corresponding parts. 10 Commercial Power Supply 15 Voltage Rectifier 20 Power Supply Voltage Circuit 30 Power Supply Voltage Circuit 40 Reference Voltage Circuit 50 Microcomputer 51 A / D Port 60 Voltage Judgment Circuit 80 Alarm Circuit 90 Alarm Device

Claims (1)

[Claims] 1. A standard comprising a power supply voltage circuit and a microcomputer having an A / D port connected to the power supply voltage circuit, wherein the microcomputer detects a driving state of a load and judges an overvoltage or a low voltage. A voltage detection circuit provided with a data table in which the voltage is converted into data, and a comparison unit for comparing the data in the data table with the power supply voltage input to the A / D port.