JPH09269841A - Power source controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent power voltage from being supplied to a main power transformer and to protect an electric equipment from a fault and burning when applied voltage shows a value except for a power voltage value by which the transformer normally operates by comparing the output voltage of a rectifier/ smoothing circuit with a threshold. SOLUTION: A voltage judgment circuit 4 being a comparison means compares the output voltage of the control rectifier/smoothing circuit 2 with the previously set threshold between the voltage value of an upper limit and the voltage value of a lower limit, by which the electric equipment can operate. When the DC voltage of the control rectifier/smoothing circuit 2 is within the threshold, the compared result is signal-outputted. When the output signal is inputted to a relay driving circuit 5 being a control means, the relay driving circuit 5 becomes an operation state and a relay 7 being a main power switch can be driven. The relay circuit 5 is provided with a control terminal 10 for opening/closing the relay 7. Only when the signal from the voltage judgment circuit 4 is outputted, control can be realized with the control signal of a control microcomputer that the electric equipment has, which is transmitted to the control terminal 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply control device for electric equipment using alternating current as a power supply.

[0002]

2. Description of the Related Art In an electric device using a commercial AC power source, a part of constituent parts of a power supply circuit has a standard sufficiently high with respect to a predetermined voltage, for example, even an electric device using a power supply voltage of AC100V has a part rated at AC250V. Use,
Widening the range of allowable power supply voltage. However, in the case of power equipment, etc., where the power supply voltage directly affects its output, it is not only uneconomical and dangerous to use parts with specifications that are sufficiently high for a given voltage, so fuses and breakers are required. This is handled by using a protection circuit such as.

[0003]

However, when different voltages are applied to the preset rated power supply voltage of the electric equipment, not only the performance of the electric equipment is not exhibited but there is a risk of abnormal operation. is there. Further, when a voltage higher than a predetermined voltage value is applied, there is a risk of causing heat generation, causing a failure, smoking, and burning. A protection circuit such as a fuse or breaker can protect when an overvoltage of 2 times or more is applied, but when an overvoltage of 2 times or less is applied,
It is not always possible to protect.

In particular, the AC20 which has become popular in homes in recent years
In the case of 0V single-phase three-wire type power distribution, the neutral wire is shared and the load of electric equipment is connected to each wire, but the amount of the load applied to the neutral wire and each wire is balanced. Almost never. If the impedance of the neutral wire becomes high for some reason, such as the contact resistance increasing at the relay connection terminals of the single-phase 3-wire power distribution, the line voltage of the heavier load will drop and the line voltage of the heavier load will decrease. The line voltage has a voltage value higher than 100 V obtained by subtracting the line voltage of the heavier load from 200 V.

When such a voltage is applied to an electric device, the protective circuit such as a fuse or a breaker does not operate and the electric device becomes an abnormal state, and there is a risk of malfunction, smoking or burning. There is. In addition, since distribution to countries with different power supply voltages is becoming more and more open, there is an increased possibility of accidentally connecting electrical equipment with different power supply voltages to a power supply exceeding the allowable range and causing the above-mentioned accident. There is.

It is an object of the present invention to supply a power supply voltage to a main power transformer when the voltage applied to the electric equipment is other than a power supply voltage value for normal operation, and to protect the electric equipment from a failure or a burnout. It is to provide a control device.

[0007]

According to the power control device of the present invention, the main power transformer and the connection between the main power transformer and the AC power source are turned on in the electric equipment operated by the AC power source. , Main power switching means to turn off, small power transformer for control connected to AC power supply, rectifying and smoothing circuit connected to small power transformer for control, and comparing the output voltage of the rectifying and smoothing circuit with multiple thresholds And a control means for controlling the connection of the main power supply switching means with the AC power supply by the output signal of the comparison means.

According to a second aspect of the present invention, there is provided the power source control device according to the first aspect,
The comparing means sends a control signal from the voltage determining means to the control means when the output voltage of the rectifying / smoothing circuit is between the threshold values with the upper limit voltage value and the lower limit voltage value at which the electric device can operate as threshold values. However, it is characterized in that the main power supply opening / closing means is brought into a controllable state.

According to a third aspect of the present invention, there is provided a power source control device according to the second aspect.
The control means has a control terminal, and is characterized by controlling the main power supply opening / closing means by a control signal from the control terminal.

Therefore, when the value of the power supply voltage is other than the value at which the electric equipment normally operates, the power supply voltage is not supplied to the main power supply transformer, thus preventing the electric equipment from breaking down, smoking or burning.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a power supply control device according to the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing an embodiment of a power supply control device of the present invention. In the figure, a power supply voltage is applied to terminals 9a and 9b from an AC power supply (not shown), which is transformed into a predetermined AC voltage by a small power transformer 1 for control, and then supplied to a rectifying / smoothing circuit 2 for control. The voltage is output, and the voltage stabilizing circuit 3 converts the voltage into a DC voltage with little voltage fluctuation and supplies the DC voltage to the voltage determining circuit 4. In addition,
The small control power supply transformer 1, the control rectifying / smoothing circuit 2, and the stabilizing power supply circuit 3 are configured to sufficiently withstand the maximum value of the supplied power supply voltage.

The voltage determination circuit 4 as a comparison means compares the output voltage of the control rectifying / smoothing circuit 2 with preset threshold values of the upper limit voltage value and the lower limit voltage value at which the electric equipment can operate. When the DC voltage of the control rectifying / smoothing circuit 2 is within the threshold value, the comparison result is output as a signal. When this output signal is input to the relay drive circuit 5 which is the control means, the relay drive circuit 5 becomes operable. When the relay drive circuit 5 becomes operable, the relay 7, which is the main power switch, can be driven.

Further, the relay drive circuit 5 has a control terminal 10 for opening and closing the relay 7 which is the main power switch, and this control terminal is provided only when the signal from the voltage determination circuit 4 is output. It can be controlled by a control signal sent to the electronic device 10 such as a control microcomputer (not shown).

The main power supply transformer 6 uses a main load circuit 8 as a load and a terminal 9a via a relay 7 which is a main power supply switch.
9b, and terminals 9a and 9b are connected to an AC power source.

As shown in the circuit diagram of FIG. 2, the voltage determination circuit 4 includes two voltage comparison circuits, a voltage comparison circuit 12a and a voltage comparison circuit 12b, and a transistor 15 forming a logical configuration.
And three voltage dividing resistors 13a, 13b, 13 for dividing the output voltage of the voltage stabilizing circuit 3 applied between the power supply terminal 4a and the common reference terminal 4b to obtain respective threshold values.
c. Then, a DC voltage corresponding to the power supply voltage output from the control rectifying / smoothing circuit 2 is input from the input terminal 4c of the voltage determining circuit 4 via the voltage stabilizing circuit 3 and divided by the voltage dividing resistors 11a and 11b. The comparison determination voltage is input to the negative input terminals of the voltage comparison circuits 12a and 12b.

The voltage dividing resistors divided to obtain the above-mentioned threshold voltage and the two threshold voltages given by 13a, 13b and 13c are the positive input of the voltage comparison circuits 12a and 12b. Input to the terminal. And the voltage dividing resistor 1
The voltage for comparison and determination divided by 1a and 11b is applied to the positive input terminals of the voltage comparison circuits 12a and 12b by a voltage dividing resistor, 13a,
The transistor 15 is turned on only when it is between the two threshold values given by 13b and 13c, that is, when one threshold value is exceeded and the other threshold value is not exceeded, the voltage is applied to the output terminal 4d. Output.

In the above case, the output of the voltage comparison circuit 12b becomes low because the input exceeds the threshold value, the output of the voltage comparison circuit 12a becomes high because the input does not exceed the threshold value, and the transistor 15 becomes A current flows in the forward direction through the resistor 14 and is turned on. The resistor 14 is for limiting the base bias current. Reference numeral 17 is a load resistor, 16 is an output voltage limiting resistor, and a required voltage value at the output terminal 4d, for example, 5
It is for outputting v.

When the input voltage is thus between the two preset threshold values, a signal is output to the relay drive circuit 5, and when the user of the electric device operates to turn on the electric device, control is performed. The control signal from the terminal 10 makes the relay 7 conductive.

When the power supply voltage is lower than the rated voltage range of the electric equipment and the input voltage to the voltage judging circuit 4 is lower than any of the preset threshold values, the voltage comparing circuits 12a and 12a.
Both outputs of b become high, the transistor 15 does not conduct, the output voltage is not generated at the output terminal 4d, and the relay driving circuit 5 does not operate. Therefore, the relay 7 can be rendered conductive regardless of the operation of the user. Can not.

When the power supply voltage is higher than the rated voltage range of the electric equipment and the input voltage of the voltage comparison circuits 12a and 12b is higher than any of the preset threshold values, the outputs of the voltage comparison circuits 12a and 12b are both output. Since the transistor 15 becomes low and the output voltage is not generated at the output terminal 4d and the relay drive circuit 5 does not operate, the relay 7 cannot be turned on regardless of the user's operation.

[0021]

According to the present invention, the electric equipment can be protected from accidents such as failure or burning because the electric equipment can recognize and control the permissible range of the power supply voltage in which the electric equipment can normally operate.

[Brief description of drawings]

FIG. 1 is a block diagram of a power supply control device showing an embodiment of the present invention.

2 is a circuit diagram showing an embodiment of a voltage determination circuit used in the power supply control device of FIG.

[Explanation of symbols]

1 small power transformer for control 2 rectifying / smoothing circuit for control 3 voltage stabilizing circuit 4 voltage determination circuit 4a power supply terminal 4b common reference terminal 4c input terminal 4d output terminal 5 relay drive circuit 6 main power transformer 7 relay 8 main load circuit 9a , 9b terminal 10 control terminal 11a, 11b voltage dividing resistor 11c
Input protection diode 12a, 12b Voltage comparison circuit 13a, 13b, 13c Voltage dividing resistor 14
Bias limiting resistor 15 Transistor 16
Output limiting resistance 17 Output load resistance

Claims (3)

[Claims] 1. A power supply control device for an electric device which is operated by an AC power supply, a main power supply transformer, a main power supply opening / closing means for turning on / off the connection between the main power supply transformer and the AC power supply, and a connection to the AC power supply. Small power transformer for control, rectifying / smoothing circuit connected to the small power transformer for control, comparing means for comparing output voltage of the rectifying / smoothing circuit with a plurality of threshold values, and output signal of the comparing means 2. A power supply control device comprising: a control means for controlling connection of the main power supply opening / closing means with the AC power supply. 2. The power supply control device according to claim 1,
When the output voltage of the rectifying / smoothing circuit is between the threshold values with the upper limit voltage value and the lower limit voltage value at which the electric device is operable as threshold values, the comparing means controls the voltage determining means. A power supply control device which sends a control signal to the means to bring the main power supply opening / closing means into a controllable state. 3. The power supply control device according to claim 2,
The power supply control device, wherein the control means has a control terminal, and controls the main power supply opening / closing means by a control signal from the control terminal.