JPH07271457A - Power unit - Google Patents

Abstract

PURPOSE:To automatically set a protection function corresponding to fitting direction by detecting a fitting direction and selecting one rating out of previously set different plural ratings in accordance with the fitting direction. CONSTITUTION:When ventilating holes 11A and 11B of the power unit are vertically fitted, a resistor RA is parallelly connected to a resistor R7, and a current to be branched to resistors R8 and R9 is reduced. On the other hand, when the ventilating holes 11A and 11B are laterally fitted, the resistor RA is not parallelly connected to the resistor R7, and the current to be branched to the resistors R8 and R9 is increased more than that of the case of vertical fitting. Therefore, a switch SW selects one rating out of the previously set plural different ratings according to the fitting direction. As a result, the fitting state of the power unit is detected and according to a fitting way, the protection function can be automatically set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for supplying power to a control device and other equipment, and more particularly to a power supply device having a protective function.

[0002]

2. Description of the Related Art A power supply device is greatly affected by its capacity, that is, its rating, by the heat generated in an internal circuit, particularly in an output circuit. Therefore, conventionally, various measures have been taken to release the heat generated inside the power supply device. FIG. 6 is an external view of a power supply device that supplies power to the control device. Figure 6
In the above, 11A and 11B are ventilation slits (ventilation holes) provided in the upper and lower portions of the power supply device, and are for releasing heat generated inside. Also, 12A
Reference numerals 12B and 12B are hooks for fixing the power supply device. FIG. 7 is a diagram showing the usage conditions of the maximum output current with respect to the ambient temperature of this power supply device. It is the characteristic in the case where the slits 11A and 11B are parallel to the vertical direction as in the mounting method shown in FIG.
Hot air H is discharged from the upper slit 11A and cold air enters from the lower slit 11B, so that air convection is smoothly performed. In the case of such standard mounting, it can be used within the range of the solid line A in FIG. That is, the maximum usable ambient temperature is Tm and the maximum output current is Im.

However, some users do not always use it in a proper manner, and as shown in FIG.
In some cases, 1A and 11B are attached so that the direction is perpendicular to the vertical direction. In such a case, the use condition is reduced to the range shown by the dotted line B in FIG. 7, the maximum usable ambient temperature is limited to T'm, and the maximum output current is limited to I'm.

On the other hand, some power supply devices are equipped with a protective function so that the device will not be damaged when used in excess of the rating. FIG. 10 is a diagram showing the operation of the protection function when the rating is exceeded. FIG. 10A is a diagram showing an overcurrent protection function. When the output current exceeds a preset rated value, the output voltage is set to zero at the point P1 in the figure, and the protection function is stopped. . Figure 10 (b)
Is a diagram showing an overvoltage protection function, and when the output voltage exceeds a preset rated value at point P2 in the figure, the output is cut off at point P3 in the figure to protect the circuit. Figure 10
(C) is a diagram showing an overheat protection function, and when the temperature exceeds a preset rated value at a point P4 in the figure, a protection function that shuts off the output to suppress the temperature rise works.

Further, as a protection function of the power supply device, there is protection of the output element of the multi-output power supply. FIG. 12 is a circuit diagram showing a configuration of a conventional multi-output power supply device. The operation of this circuit will be described.

The input AC power source is rectified and smoothed by the rectifying diode D1 and the capacitor C6 and is converted into high frequency AC by switching the transistor TR1, and the AC voltage is transmitted to the secondary side through the transformer T1. Then, the diode D51, the capacitors C51 and C52, the diode D61 and the capacitor C61, etc. are rectified and smoothed again to output the V1 output and the V2 output. To stabilize the output, the reference voltage of the IC 51 is compared with the midpoint potential of the resistors R52 and R53, and the error signal is compared with the photocoupler P.
This is done by sending out to the control transistor TR2 through HC1. However, since the V2 output is not controlled, the circuit is configured by the three-terminal regulator of the IC 61 as the voltage stabilizing means for stabilization. In addition, as a protection against misuse or trouble on the user side, the three-terminal regulator IC61 for the V2 output is
At the output, the resistors R7 and R8 detect the current of the transistor TR1 to activate the overcurrent protection and protect the power supply body.

[0007]

However, in the conventional power supply device, the effect of heat dissipation is reduced in the case of a non-standard mounting method, which may affect the reliability and life of the device. Therefore, the manufacturer describes in the catalog or instruction manual that the product is used within the range of the dotted line in FIG. 7, but there is a problem because it is difficult for the user side to thoroughly implement.

On the other hand, regarding the protection function of the multi-output power supply device, in the conventional circuit system shown in FIG. 12, energy for V1 output and V2 output is supplied to the secondary side by controlling the V1 output which is the main output. Therefore, if the V2 load is lightened when the load of the V1 output is heavy, the transformer tap voltage of the V2 output rises, and in the worst case, the capacitors C61 and IC61 in FIG. 10 may be damaged. FIG. 13 shows how the transformer tap voltage rises. FIG. 13A shows a transformer T under normal load conditions.
13B is a diagram showing the waveform of the tap voltage of No. 1 and FIG.
It is a figure which shows the waveform of the tap voltage of the transformer T1 when the output load is heavy and the V2 output load is light. FIG. 13 (b)
In the waveform shown in (1), the voltage rises significantly during switching. As a countermeasure against this, a resistor R61, which is a pseudo load, is inserted in the V2 output to allow a small amount of waste current to flow to suppress the rising voltage. FIG. 14 is a waveform of the tap voltage when the voltage rise is suppressed by the resistor R61. The same effect can be obtained by inserting the pseudo load at both ends of the capacitor C61.

As another measure, a current may be supplied to the pseudo load only when necessary. FIG. 15 shows the resistance R of FIG.
FIG. 34 is a circuit diagram of an example in which an additional circuit that replaces 61 is provided. Figure 1
In No. 5, when the tap voltage of the transformer T1 rises, the Zener diode of the additional circuit shown by the dotted line conducts, the base current flows through the transistor through the resistor, the transistor turns on, and the pseudo load resistor connected to the collector is loaded. An electric current flows. In this case, there is an advantage that a useless load current does not always flow.

By the way, some users often use multiple output power supplies connected in series. FIG. 16 is a circuit diagram showing an example in the case where the terminals 22 and 23 are directly connected and two outputs are connected in series. In this case, the output voltage is V
It becomes 1 + V2. However, when used in this way, the following problems arise due to the characteristics of the three-terminal regulator.

FIG. 17 is a diagram showing the relationship between the output current and the output voltage of a general three-terminal regulator, and the overcurrent protection curve of the three-terminal regulator generally shows the characteristics shown in FIG. That is, when the load becomes heavy and the output current exceeds the rating, the output voltage droops in the shape of "F",
Even if the load is lightened, the original output voltage is restored at once (almost directly above) without following the transition curve in reverse. That is, unless the load current is below the rated value, the rated voltage is not restored. Therefore, once the overcurrent protection operates, it is difficult to recover.

FIG. 18 is a diagram showing an overcurrent protection curve of the series connection configuration shown in FIG. When an overcurrent flows to the output, the drooping curve shown by the solid line in FIG. The droop point A in this case is determined by the original overcurrent point of the IC 51 of FIG. After that, when the voltage of V2 becomes close to 0v after transition to the point B, the following operation is performed.

Since the V1 output is not overcurrent protected, it remains at the rated voltage. Similarly, both ends of the capacitor C61 are V2-V _IO when the input / output voltage difference of the IC 51 at the time of design is V _IO . Here, when the output current i ₀ flowing through the line connecting the terminals 22 and 23 decreases, the drop voltage V _{(RL) of the} load resistance R _L also decreases, and the potentials of the terminals 22 and 23 approach −V1. Come on. Then, the input / output potential difference ΔV of the IC 61 is ΔV = V2 + V _IO − (− V1) = V1 + V2 + V _IO , which is (V1 + V2 + V _IO ) / V in comparison with the normal time.
_A voltage as large as _IO times is applied, and the loss of the IC 61 increases, causing heat generation. In this state, heat is generated in the range E of FIG. 18 because the three-terminal regulator is hard to recover. Therefore, in the worst case without recovery, IC61
Will be destroyed by heat.

FIG. 19 shows a three-terminal regulator (IC61).
This is a circuit to prevent the thermal destruction of. In FIG. 19, a diode D62 is added in parallel with the pseudo load resistor R61. When the operating point changes to the position of point B in FIG. 18, this diode D62 is prevented from conducting to increase the input / output voltage difference ΔV of the three-terminal regulator from increasing. When the diode D62 conducts at point B, the droop curve folds to the right as shown by the dotted line. Point F is a droop point determined by resistors R7 and R8.

However, when the measure for suppressing the rise of the transformer tap voltage and the measure for preventing the thermal destruction of the three-terminal regulator at the time of series connection are carried out at the same time, the number of parts increases and the cost also increases. Further, there arises a problem that the power source becomes larger.

A first aspect of the present invention is to provide an excellent power supply device capable of detecting the mounting state of the power supply device and automatically setting the protection function according to the mounting method. The purpose of.

The second aspect of the present invention is a measure for suppressing the rise of the transformer tap voltage without increasing the number of parts, the cost, and the increase in the size of the power supply. It is a second object of the present invention to provide an excellent power supply device capable of simultaneously performing the measures for preventing the thermal destruction of the three-terminal regulator in the above.

[0018]

In order to achieve the above-mentioned first object, a mounting direction detecting means for detecting a mounting direction and one rating according to the mounting direction are selected from a plurality of different preset ratings. And a rating selecting means for selecting.

In order to achieve the second object, the DC voltage is switched and converted into an AC voltage, which is supplied to the primary side of the transformer, and the AC voltages of a plurality of systems are respectively supplied from the secondary side of the transformer. A voltage stabilizing means for receiving a DC voltage obtained from the secondary side of the transformer on the input side and sending a DC voltage of a constant voltage from the output side to a multi-output power supply device for converting the voltage, and this voltage stabilizing means. A first semiconductor element that conducts when the DC voltage on the input side rises above a predetermined value, and a switching means that has a second semiconductor element that conducts when the voltage on the output side becomes a reverse voltage. .

[0020]

According to the first aspect of the invention, since the rating according to the mounting direction can be freely and automatically set, the power supply device can be mounted without imposing an unnecessary burden on the user.

According to the second aspect of the invention, by using the characteristic but inexpensive switching means, the number of parts and cost are not increased, and the power source is not enlarged. It is possible to simultaneously take measures for suppressing the rise of the transformer tap voltage and measures for preventing thermal destruction of the three-terminal regulator during series connection.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram of a power supply device according to an embodiment of the first invention. The function of this circuit diagram will be described. The AC input is converted into a DC voltage by the rectifier D1 and the smoothing capacitor C5 via the choke L1. This DC voltage is supplied to IC1. A high-frequency pulse signal is generated in IC1, and the field-effect transistor T is output from the output terminal 2 via the resistor R10.
It is supplied to the gate of R1. Therefore, the transistor TR
The drain / source of 1 performs a switching operation in response to this pulse signal, and the transformer T1 connected to the drain
An alternating voltage is supplied to the primary side of the. This AC voltage is converted into a predetermined voltage by the transformer T1, and converted into a DC voltage again by the rectifier D51, the choke L1, and the capacitors C53 and C54, and output.

The resistors R7, R8, R9, RA, the switch SW and the capacitor C10 have an overcurrent protection function, and the voltage drop by the resistor R8 is detected by the IC1, thereby detecting the output current and exceeding the rating. When the current flows, the pulse signal supplied to the gate of the transistor TR1 is stopped, and the output voltage is drooped to suppress the output current.

Zener diode D52, resistor R61,
The photocoupler PHC2, the resistors R14 and R16, and the capacitor C13 form an overvoltage protection circuit that shuts off the output when the output voltage exceeds the rated voltage (the Zener voltage of the Zener diode D52). That is, when the output voltage exceeds the rated voltage, the photocoupler PHC2
A current flows to the input side of the input terminal, the phototransistor on the output side becomes conductive, and the voltage of the input terminal 6 of the IC1 becomes higher than a predetermined value. As a result, the pulse signal supplied to the gate of the transistor TR1 is stopped to cut off the output.

Further, the resistance value of the thermistor TH1 changes according to the ambient temperature, and when the ambient temperature exceeds the preset rated temperature by the voltage divided by the resistor R14 and the thermistors TH1 and R16, the IC1 Since the voltage of the input terminal 6 becomes higher than the predetermined value, the pulse signal supplied to the gate of the transistor TR1 is stopped to stop the IC.
1 forms a thermal protection circuit that shuts off the output.

FIG. 2 is a diagram showing a structure for operating the switch SW. In FIG. 2, reference numeral 1 denotes a ball that moves in a cavity extending in a predetermined direction inside the power supply device, and has a certain weight such as a pachinko ball. Ball 1
Moves in the cavity according to the mounting direction of the power supply device. When the ball 1 is in the position shown by the solid line in the figure, that is, when the ventilation holes 11A and 11B of the power supply device are mounted in the vertical direction (the vertical direction), the contact point of the switch SW is turned on, and the ball 1 is shown in the dotted line When in the position
That is, the contact of the switch SW is turned off when the ventilation holes 11A and 11B of the power supply device are attached in the lateral direction (the direction perpendicular to the vertical direction). Therefore, the ball 1 constitutes mounting direction detecting means for detecting the mounting direction.

FIG. 3 (a) is a diagram showing a portion of the overcurrent protection circuit in FIG. 1, and shows ventilation holes 11A and 1A of the power supply device.
When 1B is mounted in the vertical direction as shown in FIG. 8, the resistor RA is connected in parallel with the resistor R7, so that the current shunted to the resistors R8 and R9 is small. On the other hand, when the ventilation holes 11A and 11B of the power supply device are laterally mounted as shown in FIG. 9, the resistor RA is not connected in parallel to the resistor R7, so that the current shunted to the resistors R8 and R9 is mounted in the vertical direction. More than in. As a result, the voltage drop of the resistor R8 becomes larger than that in the case of vertical mounting. FIG. 3 (b) is a diagram comparing the rated values due to the differences in these mounting directions. In the case of lateral mounting (when the contact of the switch SW is closed), in the case of vertical mounting (the contact of the switch SW is In case of open), the rated value is lower than that in the case of open, and the output voltage is drooped by a smaller output current. Therefore, the switch SW constitutes a rating selection unit that selects one rating from a plurality of preset different ratings according to the mounting direction.

FIG. 4 is a diagram showing an example of changing the thermal protection rating according to the mounting direction of the power supply device. FIG. 4A is an example of a circuit in which a thermistor THA of another rating is connected in parallel to the thermistor TH1 via a switch in the circuit of FIG. This switch is turned off when the ventilation holes 11A and 11B of the power supply device are mounted vertically, and is turned on when the ventilation holes 11A and 11B of the power supply device are mounted laterally. FIG. 4B is a diagram showing how the output is cut off according to the temperature.

When the ventilation holes 11A and 11B of the power supply device are mounted in the vertical direction, the output is shut off at a high temperature because only the thermistor TH1 is connected, but the ventilation holes 11A and 11B are mounted in the vertical direction. In the case of the direction, since the thermistor THA is also connected, the output is cut off at a low temperature. Needless to say, the switch in this case can have a structure similar to that of FIG.

FIG. 5 is a view showing a switch structure of another embodiment different from the switch structure of FIG. In FIG. 5, reference numeral 2 denotes a weight provided inside the power supply device, which swings around the shaft 2a according to the direction of gravity. Reference numeral 3 denotes a photo interrupter, which is arranged at a position sandwiching the weight 2. When the mounting direction of the ventilation holes 11A and 11B of the power supply device is the vertical direction, the weight 2 is located at the position shown by the solid line in the figure.
When the mounting directions of A and 11B are vertical, the weight 2 is at the position shown by the dotted line in the figure. That is, since the position of the weight 2 changes according to the mounting direction of the power supply device, the mounting direction can be detected by the photo interrupter 3. When the photo interrupter 3 is turned on or off, the switch SW, which is the rating selecting means, is driven.

As described above, according to the first embodiment of the present invention, by providing the mounting direction detecting means which operates in accordance with the mounting direction of the power supply device to detect the mounting direction,
Since the rating can be freely and automatically set by the rating selecting means, the user can mount the rating without imposing an unnecessary burden on the user.

In the embodiment of the first invention,
The rating for sending the alarm output to the user is also changed according to the mounting direction. With this configuration, the user can use the power supply device with peace of mind when there is no alarm output regardless of the mounting direction.

FIG. 11A is a circuit diagram of the power supply device according to the second embodiment of the invention. In FIG. 11A, a switching means indicated by a dotted line is added to the 3-terminal regulator IC 61. As shown in the figure, this switching means is composed of a voltage dividing resistor for detecting the input voltage of the IC 61 and the field effect transistor 100. The other circuit configurations are the same as those in FIG. 12 (except R61), and are therefore denoted by the same reference numerals and the description thereof will be omitted. The voltage dividing resistor has a constant such that the transistor 100 becomes conductive in the portion where the voltage waveform shown in FIG. 13B rises.

FIG. 11B shows an internal circuit of the transistor 100. As shown in FIG. 11B, the inside of the transistor element 101 is the first semiconductor element.
And a diode element 102 which is a second semiconductor element.

Next, the operation of this circuit will be described.
When the transformer tap voltage supplied to the input side of the three-terminal regulator becomes a high voltage as shown in FIG. 13B, the transistor element 101 becomes conductive, so that the load current is output to the output of the three-terminal regulator. Flowing. Therefore, when two outputs are connected in series as shown in FIG.
Even when the three-terminal regulator has a light load, the transistor element 101 becomes a pseudo load, so that it is possible to prevent thermal destruction of the three-terminal regulator.

On the other hand, since the diode element 102 is built in between the drain and source of the transistor element 101, when the operating point changes to the position of point B in FIG. It is possible to prevent the difference ΔV, which is the input / output voltage difference, from increasing.

Therefore, according to the second embodiment of the present invention, the increase in the transformer tap voltage can be suppressed without increasing the number of parts, increasing the cost, and increasing the size of the power supply. It is possible to simultaneously take the measure and the measure for preventing the thermal destruction of the three-terminal regulator during the series connection.

[0039]

As is apparent from the above embodiments, according to the first aspect of the present invention, the mounting direction detecting means that operates in accordance with the mounting direction of the power supply device is provided to detect the mounting direction, and thereby the rating is determined. Since it can be freely and automatically set by the rating selection means, it can be installed without imposing an unnecessary burden on the user.

Further, according to the second aspect of the present invention, the number of parts does not increase, the cost does not increase, and the measure for suppressing the rise of the transformer tap voltage without increasing the size of the power supply is provided. It is possible to simultaneously take measures to prevent thermal destruction of the three-terminal regulator during connection.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a power supply device according to an embodiment of the first invention.

FIG. 2 is a diagram showing a structure for operating a switch SW in FIG.

FIG. 3A is a diagram showing a portion of an overcurrent protection circuit in FIG. 1. (B) is a figure which compared the rated value by the difference in an attachment direction.

FIG. 4 is a diagram showing an example in which a thermal protection rating is changed according to a mounting direction of a power supply device.

5 is a diagram showing a switch structure of another embodiment different from the switch structure of FIG.

FIG. 6 is a diagram illustrating an appearance of a power supply device that supplies power to a control device.

FIG. 7 is a diagram showing a usage condition of a maximum output current with respect to an ambient temperature of a power supply device.

FIG. 8 is a view showing the attachment in which the ventilation holes are in the vertical direction.

FIG. 9 is a view showing the attachment in which the ventilation holes are perpendicular to the vertical direction.

FIG. 10 is a diagram showing the operation of the protection function when the rating is exceeded.

FIG. 11A is a circuit diagram of a power supply device according to an embodiment of the second invention. (B) is a diagram showing an internal circuit of the transistor 100.

FIG. 12 is a circuit diagram showing a configuration of a conventional multiple output power supply device.

FIG. 13 is a diagram showing how the transformer tap voltage rises.

FIG. 14 is a waveform of a tap voltage when the voltage rise is suppressed by a resistor R61.

15 is a circuit diagram in which an additional circuit that replaces the resistor R61 of FIG. 12 is provided.

16 is a circuit diagram showing a case in which two terminals are directly connected to each other and two outputs are connected in series in FIG.

FIG. 17 is a diagram showing a relationship between an output current and an output voltage of a general three-terminal regulator.

FIG. 18 is a diagram showing an overcurrent protection curve of the configuration of series connection shown in FIG. 16;

FIG. 19 is a circuit for preventing thermal destruction of a three-terminal regulator.

[Explanation of symbols]

 1 Ball (Mounting Direction Detection Means) 2 Weight (Mounting Direction Detection Means) 3 Photointerrupter (Rating Selection Means) SW Switch (Rating Selection Means) 10 Power Supply Device 11A, 11B Slits (Ventilation Holes) 100 Field Effect Transistor (Switching Element) 101 transistor element (first semiconductor element) 102 diode element (second semiconductor element)

Claims (11)

[Claims] 1. A power supply device comprising: mounting direction detecting means for detecting a mounting direction; and rating selecting means for selecting one rating according to the mounting direction from a plurality of preset different ratings. 2. The mounting direction detecting device according to claim 1, wherein the two facing surfaces have ventilation holes for heat dissipation, and the mounting direction detecting means is a mounting direction in which the two facing surfaces are in a vertical direction or a vertical direction. And a means for determining whether the mounting direction is a right angle direction, the rating selecting means selects a standard rating when the mounting direction is the vertical direction, and the mounting direction is a direction perpendicular to the vertical direction. Is a power supply device characterized by selecting a rating lower than the standard. 3. The power supply device according to claim 1, wherein the rating is a rating for sending an alarm output. 4. The power supply device according to claim 1, wherein the rating is a rating for limiting an output current. 5. The power supply device according to claim 1, wherein the rating is a rating of ambient temperature for limiting output. 6. The mounting direction detecting means according to claim 1, wherein the mounting direction detecting means includes a cavity extending in a predetermined direction of the apparatus.
It has a ball that freely moves in the cavity according to the mounting direction of the device, and a switch that operates when the ball moves to a predetermined position, and the mounting direction of the device can be changed by turning the switch on or off. A power supply device, characterized in that the one rating is selected and selected. 7. The weight according to claim 1 or 2, wherein the mounting direction detecting means includes a weight swinging around an axis according to the direction of gravity, and a photo interrupter type switch that shields light when the weight is within a predetermined range. A power supply device, comprising: and one of the ratings, which is determined by turning the switch on or off to determine the mounting direction of the device. 8. The power supply device according to claim 6, wherein the constant of the output current limiting circuit is changed by turning on or off the switch. 9. The power supply device according to claim 6, wherein a constant of a temperature setting circuit that cuts off the output is changed by turning on or off the switch. 10. A multi-output power supply device for switching a DC voltage to convert it into an AC voltage, supplying the AC primary voltage to a primary side of the transformer, and converting AC voltages of a plurality of systems from the secondary side of the transformer into DC voltages. There is provided a voltage stabilizing means for receiving a DC voltage obtained from the secondary side of the transformer on the input side and sending out a constant DC voltage from the output side, and a DC voltage on the input side of the voltage stabilizing means is a predetermined value. A power supply device comprising: a first semiconductor element that conducts when the voltage rises above a value and a switching unit that has a second semiconductor element that conducts when the output-side voltage becomes a reverse voltage. 11. The switching means according to claim 10, wherein the voltage dividing resistor for dividing the DC voltage on the input side of the voltage stabilizing means and the divided voltage supplied to the gate exceed a predetermined value. And a field effect transistor having a flywheel diode incorporated therein, which conducts when a reverse voltage is applied between the drain and the source.