JP4577837B2 - Switching power supply - Google Patents

Description

  The present invention relates to a switching power supply, and more particularly to a switching power supply that includes a standby power supply circuit and a main power supply circuit, and that saves power by stopping the main power supply circuit by an external on / off control signal during standby.

  In recent years, the operating power of the main load has been turned off in OA equipment such as personal computers, printers, copiers, etc. and household electrical appliances, especially equipment that can be operated with a remote control switch (air conditioner, lighting, telephone, TV, video, etc.) However, most of them have a function to put the device in a standby mode so that the main load can be operated immediately by a command from a remote control switch or the like. These devices usually have some energy-saving measures, but one of them is a dual power supply with a separate switching power supply circuit specialized for standby operation in addition to a switching power supply optimized for the rated load. There is a method. In this standby power supply circuit, circuit constants, components used, and other circuit designs are optimized in accordance with the standby load.

Conventionally, as a dual power supply type switching power supply for saving power during standby, as shown in FIGS. 4 and 5, a standby power supply circuit and a main power supply circuit have independent rectifier circuits, smoothing circuits, and inrush current suppression circuits. As a rush current suppression device that is provided separately, a switching power supply using a power thermistor on the standby power supply circuit side and a parallel connection circuit of a rush current suppression resistor and a thyristor or triac on the main power supply circuit side is known. (For example, refer nonpatent literature 1).
Alternatively, as shown in FIGS. 6 and 7, the standby power supply circuit and the main power supply circuit are provided with a common rectifier circuit and smoothing circuit, and an inrush current suppression circuit, and as the inrush current suppression device, an inrush current suppression resistor and a thyristor or A switching power supply that uses a parallel connection circuit with a triac and supplies a gate voltage for turning on the thyristor or triac from the standby power supply circuit side to the gate terminal of the thyristor or triac is known (for example, non-patent document). 2).

FIG. 4 is a diagram showing a conventional dual power supply type switching power supply circuit. This has a rectifier circuit and a smoothing circuit and an inrush current suppression circuit which are independent from each other in the standby power supply circuit and the main power supply circuit. 4A is an overall circuit diagram, FIG. 4B is a circuit diagram illustrating an example of a standby power supply circuit, and FIG. 4C is a circuit diagram illustrating an example of a main power supply circuit.
The connection from the AC power supply P to the standby power supply circuit 6 will be described with reference to FIG. 4A. First, on the AC power supply P side, the rectifier circuit 12 is provided as an independent rectification and smoothing circuit for supplying power to the standby power supply circuit 6. A full-wave rectifier diode is connected. The rectified output plus side terminal is connected to the plus pole side of the smoothing capacitor serving as the smoothing circuit 17 and the plus terminal of the standby power supply circuit 6 via the power thermistor 14 for suppressing inrush current.
That is, the inrush current suppressing power thermistor 14 is connected between the rectified output plus side terminal of the rectifier circuit 12 and the plus pole of the smoothing circuit 17.
On the other hand, the rectified output minus side terminal of the rectifier circuit 12 and the minus terminal of the standby power supply circuit 6 are connected to the minus pole side of the smoothing circuit 17.
The standby power supply circuit 6 illustrated in FIG. 4B will be described. The standby power supply circuit 6 is an insulating type composed of a primary side circuit and a secondary side circuit connected via a transformer 23. The primary side circuit is provided with a switching main circuit unit 26 for performing output control, and the secondary side circuit is provided with an output rectifying / smoothing circuit 27 for rectifying and smoothing the electric power received from the transformer. In the output control of the standby power supply circuit 6 according to this example, the magnitude of the secondary output output to the standby power supply output terminal 8 is determined via the output detection circuit 24 and the photocoupler 25 for insulating between the primary and secondary circuits. This is performed by feeding back to the switching main circuit section 26 of the primary side circuit.

Next, the connection from the AC power supply P to the main power supply circuit 7 will be described. On the AC power supply P side, full-wave rectification that becomes the rectification circuit 13 as an independent rectification and smoothing circuit that supplies power to the main power supply circuit 7 is described. A diode is connected. The rectified output plus side terminal is connected to the plus pole side of the smoothing capacitor serving as the smoothing circuit 18 and the plus terminal of the main power supply circuit 7 through a rush current suppressing device for the main power supply circuit 7 described below. Yes.
The inrush current suppressing device for the main power supply circuit 7 includes a parallel connection circuit of an inrush current suppressing resistor 16 and a thyristor 15, and is connected in series between the rectified output plus side terminal of the rectifier circuit 13 and the plus pole of the smoothing circuit 18. It is connected. At this time, the anode side of the thyristor 15 is connected to the rectified output plus side terminal of the rectifier circuit 13, and the cathode side is connected to the plus pole of the smoothing circuit 18.
A gate voltage for turning on the thyristor 15 is supplied to the gate terminal of the thyristor 15 from the main power supply circuit 7 side.
On the other hand, the rectified output minus side terminal of the rectifier circuit 13 and the minus terminal of the main power supply circuit 7 are connected to the minus pole side of the smoothing circuit 18.
Further, the main power supply circuit 7 illustrated in FIG. 4C will be described. This is an insulating type composed of a primary side circuit and a secondary side circuit connected via a transformer 23. The primary side circuit is provided with a switching main circuit unit 26 for performing output control, and the secondary side circuit is provided with an output rectifying / smoothing circuit 27 for rectifying and smoothing the electric power received from the transformer. In the output control of the main power supply circuit 7 according to this example, the magnitude of the secondary output output to the main power supply output terminal 9 is determined via the output detection circuit 24 and the photocoupler 25 for insulation between the primary and secondary circuits. This is performed by feeding back to the switching main circuit section 26 of the primary side circuit. The main power supply output on / off control signal input 10 is also input to the switching main circuit unit 26 via the photocoupler 25.
Further, the main power supply circuit 7 illustrated in FIG. 4C is configured to supply a voltage to the gate terminal of the thyristor 15 using an auxiliary winding provided in the transformer 23. That is, after the AC power supply P is turned on, when the main power supply circuit 7 is started through a transient state, a voltage is generated in the transformer 23 and its auxiliary winding. Therefore, this auxiliary winding voltage is supplied to the thyristor via the resistor 29 and the rectifier diode 28. When the main power supply circuit 7 is turned on, the thyristor 15 is maintained in the on state by being input to the gate terminal 15.

  According to the circuit having the configuration as shown in FIG. 4, it is necessary to separately provide the rectification and smoothing circuit and the inrush current suppression circuit in the standby power supply circuit 6 and the main power supply circuit 7, and the number of parts increases. There is a problem that the space efficiency becomes worse.

FIG. 5 is a diagram showing another conventional dual power supply type switching power supply circuit, in which the thyristor 15 of FIG. At this time, the T2 side of the triac 19 is connected to the rectified output plus side terminal of the rectifier circuit 13, and the T1 side is connected to the plus pole of the smoothing circuit 18. Other configurations are the same as those of the circuit shown in FIG.
Similarly to the circuit described with reference to FIG. 4, this circuit also requires the rectification and smoothing circuit and the inrush current suppression circuit to be provided separately for the standby power supply circuit 6 and the main power supply circuit 7, which increases the number of components. In addition, there is a problem that the space efficiency is deteriorated.

FIG. 6 is a diagram showing still another dual power supply type switching power supply circuit that has been conventionally used. This has a common rectifier circuit, smoothing circuit, and inrush current suppression circuit in the standby power supply circuit and the main power supply circuit. 6A is an overall circuit diagram, FIG. 6B is a circuit diagram illustrating an example of a standby power supply circuit, and FIG. 6C is a circuit diagram illustrating an example of a main power supply circuit.
The connection from the AC power supply to each power supply circuit will be described based on FIG. 6A. First, a rectifier circuit as a common rectification and smoothing circuit that supplies power to the standby power supply circuit 6 and the main power supply circuit 7 on the AC power supply P side. A full-wave rectifier diode 2 is connected. The rectified output plus side terminal is connected to the plus pole side of the smoothing capacitor to be the smoothing circuit 5 through a rush current suppressing device to the standby power source circuit 6 and the main power source circuit 7 described below. Further, the plus pole side of the smoothing circuit 5 is connected to the plus terminal of the standby power circuit 6 and the plus terminal of the main power circuit 7.
The inrush current suppression device for the standby power supply circuit 6 and the main power supply circuit 7 includes a parallel connection circuit of an inrush current suppression resistor 21 and a thyristor 20, and a rectified output plus side terminal of the rectifier circuit 2 and a plus pole of the smoothing circuit 5. Are connected in series. At this time, the anode side of the thyristor 20 is connected to the rectified output plus side terminal of the rectifier circuit 2, and the cathode side is connected to the plus pole of the smoothing circuit 5. The gate voltage for turning on the thyristor 20 is supplied to the gate terminal of the thyristor 20 from the standby power supply circuit 6 side.
On the other hand, the rectified output minus side terminal of the rectifier circuit 2 is connected to the minus pole side of the smoothing circuit 5, and the minus pole side of the smoothing circuit 5 is connected to the minus terminal of the standby power source circuit 6 and the main power source circuit 7. Is connected to the negative terminal.

Next, the standby power supply circuit 6 and the main power supply circuit 7 illustrated in FIGS. 6B and 6C will be described. The standby power supply circuit 6 and the main power supply circuit 7 are insulated by a primary circuit and a secondary circuit connected via a transformer 23. It is of shape. The primary side circuit is provided with a switching main circuit unit 26 for performing output control, and the secondary side circuit is provided with an output rectifying / smoothing circuit 27 for rectifying and smoothing the electric power received from the transformer. In the output control of the standby power supply circuit 6 and the main power supply circuit 7 according to this example, the magnitude of the secondary output output to the standby power supply output terminal 8 or the main power supply output terminal 9 is determined based on the output detection circuits 24 and 1-2. This is performed by feeding back to the switching main circuit portion 26 of the primary side circuit via the photocoupler 25 for insulation between the secondary circuits.
Here, the main power supply output on / off control signal input 10 is also input to the switching main circuit portion 26 of the main power supply circuit 7 illustrated in FIG.
Further, the standby power supply circuit 6 illustrated in FIG. 6B is configured to supply a voltage to the gate terminal of the thyristor 20 using an auxiliary winding provided in the transformer 23. That is, when the standby power supply circuit 6 is started through a transient state after the AC power supply P is turned on, a voltage is generated in the transformer 23 and its auxiliary winding, and this auxiliary winding voltage is supplied to the thyristor via the resistor 29 and the rectifier diode 28. When the standby power supply circuit 6 is turned on, the thyristor 20 is maintained in the on state by being input to the gate terminal 20.

According to the circuit having the configuration as shown in FIG. 6, the number of parts can be reduced as compared with the circuits shown in FIGS. 4 and 5 by sharing the rectifying and smoothing circuit and the inrush current suppressing circuit.
However, in this circuit configuration, since the thyristor 20 is turned on except when the AC power is turned on, the gate drive power supplied from the standby power supply circuit 6 to the gate of the thyristor 20 is not only during the main power supply operation but also during standby. Is always necessary. Therefore, there is a problem that power consumption during standby is increased and power saving during standby is prevented.

In the circuit shown in FIG. 6, a method of replacing the parallel connection circuit of the thyristor 20 and the inrush current suppressing resistor 21 with a power thermistor is also conceivable.
However, if the main power supply outputs a large amount of power, a large current flows through the power thermistor when the main power supply circuit 7 is turned on and the main power supply output 9 is output. It is not practical because a power thermistor needs to be selected.

Further, in the circuit shown in FIG. 6, a method of supplying the gate voltage for turning on the thyristor 20 from the main power supply circuit 7 side to the gate terminal instead of from the standby power supply circuit 6 side is also conceivable.
However, in such a configuration, when the main power supply circuit 7 is turned off during standby, the thyristor 20 is also turned off as the voltage supply from the main power supply circuit 7 to the gate of the thyristor 20 is stopped. For this reason, the current consumption of the standby power supply circuit 6 always flows into the inrush current suppression resistor 21 during standby, resulting in an increase in useless power consumption and further causing abnormal heat generation of the inrush current suppression resistor 21. Therefore, it is still not useful.

FIG. 7 is a diagram showing still another dual power supply type switching power supply circuit that has been conventionally used, in which the thyristor 20 of FIG. At this time, the T2 side of the triac 22 is connected to the rectified output plus side terminal of the rectifier circuit 2, and the T1 side is connected to the plus pole of the smoothing circuit 5. Other configurations are the same as those of the circuit shown in FIG.
Similar to the circuit described with reference to FIG. 6, this circuit can reduce the number of parts, but the triac 22 is turned on except when the AC power is turned on, so that the standby power circuit 6 is connected to the gate of the triac 22. The supplied gate drive power is always required during standby as well as during main power operation. Therefore, there is a problem that power consumption during standby is increased and power saving during standby is prevented.
Also, a method of replacing the parallel connection circuit of the triac 22 and the inrush current suppression resistor 21 with a power thermistor, or a gate voltage for turning on the triac 22 from the main power supply circuit 7 side to the gate terminal instead of from the standby power supply circuit 6 side. The delivery method is still not useful for the reasons described above.

In short, in any of the above-described prior arts, a switching power supply device capable of reducing standby power consumption more than ever while reducing the number of parts constituting the rectifying and smoothing circuit and the inrush current suppressing circuit is realized. It was not done.
"Practical power circuit design handbook", Jiro Togawa, CQ Publishing Co., Ltd., published 15th February 1990, 4th edition (pages 25-27, Fig. 1-20, Fig. 1-23) "Switching power supply handbook 2nd edition", supervised by Kosuke Harada, Nikkan Kogyo Shimbun, January 25, 2000, 2nd edition, 1st edition (page 117-119, Fig. 2.74)

  Accordingly, the present invention provides a switching power supply apparatus according to a dual power supply system that solves the above-described problems, can reduce the number of components required for the rectifying and smoothing circuit and the inrush current suppressing circuit, and can reduce power consumption during standby. Is an issue.

The present invention is a switching power supply device capable of solving the above-described problems,
A standby power supply circuit that supplies a standby power supply output and a main power supply circuit that supplies a main power supply output, and supplies power to the standby power supply circuit and the main power supply circuit before the standby power supply circuit and the main power supply circuit. A switching power supply device including a common rectifier circuit and a smoothing circuit,
At any position between the rectified output plus side terminal of the rectifier circuit and the plus pole of the smoothing circuit, or between the rectified output minus side terminal of the rectifier circuit and the minus pole of the smoothing circuit,
The thermistor,
Inrush comprising a parallel connection circuit with a power control device that can switch the operation / operation stop of the main power supply circuit by an external on / off signal and can control the conduction / non-conduction state in accordance with the operation / operation stop of the main power supply circuit A current suppression device is connected in series ,
In the main power supply operation mode in which the main power supply circuit operates, the power control device is turned on to short-circuit both ends of the thermistor, while in the standby mode, the operation of the main power supply circuit is stopped to It is characterized by being in a non-conductive state .

  The power control device includes a thyristor or a triac that can be controlled by inputting the external on / off signal to a gate terminal, and the external on / off signal is transmitted from the main power supply circuit to the thyristor or triac. It is preferably supplied to the gate terminal.

The “thermistor” in the present invention refers to a semiconductor device that utilizes the fact that the resistance value changes with temperature.
Although the temperature characteristic of the resistance varies depending on the property of the element, generally, the resistance value decreases as the temperature increases, and the resistance value increases as the temperature decreases.
The “triac” in the present invention refers to a bidirectional three-terminal thyristor, and refers to a thyristor capable of conducting a current in either direction by a signal applied to a gate terminal.
The term “thyristor” is used in a broad sense, and refers to various thyristors of GTO and other commutation turn-off types and self-turn-off types in addition to reverse blocking three-terminal thyristors. The trigger energy of the thyristor is not particularly limited as long as it is normal electric energy, light, heat, etc., unless otherwise specified.

  According to the present invention, the number of components required for the rectifying and smoothing circuit and the inrush current suppressing circuit is reduced in a switching power supply that includes a standby power supply circuit and a main power supply circuit and stops the main power supply circuit by an external on / off control signal during standby. In addition, the power consumption during standby can be reduced, and the cost generated during manufacturing and subsequent use can be suppressed more than ever.

[First Embodiment]
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
In the following description, the same components as those shown in FIGS. 4 to 7 described above are denoted by the same reference numerals.
A switching power supply circuit according to a first embodiment of the present invention is shown in FIG. 1A is an overall circuit diagram, FIG. 1B is a circuit diagram illustrating an example of a standby power supply circuit, and FIG. 1C is a circuit diagram illustrating an example of a main power supply circuit.

[Constitution]
The switching power supply circuit 1 according to the present embodiment has a rectifier circuit 2 and a smoothing circuit 5 that are common to the standby power supply circuit 6 and the main power supply circuit 7, and an inrush current suppressing device 30.
The connection from the AC power supply to each power supply circuit will be described with reference to FIG. 1A. First, a rectifier circuit as a common rectification and smoothing circuit that supplies power to the standby power supply circuit 6 and the main power supply circuit 7 on the AC power supply P side. A full-wave rectifier diode 2 is connected. The rectified output plus side terminal is connected to the plus pole side of the smoothing capacitor to be the smoothing circuit 5 via the inrush current suppressing device 30 to the standby power source circuit 6 and the main power source circuit 7 described below. Further, the plus pole side of the smoothing circuit 5 is connected to the plus terminal of the standby power circuit 6 and the plus terminal of the main power circuit 7.
On the other hand, the rectified output minus side terminal of the rectifier circuit 2 is connected to the minus pole side of the smoothing circuit 5, and the minus pole side of the smoothing circuit 5 is connected to the minus terminal of the standby power source circuit 6 and the main power source circuit 7. Is connected to the negative terminal.

The inrush current suppression device 30 to the standby power supply circuit 6 and the main power supply circuit 7 includes a parallel connection circuit of a power control device that can be controlled by an external on / off signal and a thermistor 31, and a rectification output plus side terminal of the rectification circuit 2 And the positive electrode of the smoothing circuit 5 are connected in series. Here, the thermistor 31 plays a role of suppressing an inrush current when the AC power is turned on, and a path of flowing a standby current from the rectifier circuit 2 side to the standby power supply circuit 6 in the standby mode after becoming a steady state. . On the other hand, the power control device operates so as to short-circuit both ends of the thermistor 31 during the main power supply operation after the steady state, and the current flowing into the main power supply circuit 7 in the main power supply operation mode is supplied from the rectifier circuit 2 side to the main power supply. It plays the role of bypassing the circuit 7 without resistance.
In the present embodiment, a thyristor 32 is selected as the power control device, and the anode side of the thyristor 32 is connected to the rectified output plus side terminal of the rectifier circuit 2 and the cathode side is connected to the plus pole of the smoothing circuit 5.
In this embodiment, the gate voltage for turning on the thyristor 32 is supplied from the main power supply circuit 7 side to the gate terminal of the thyristor 32 instead of the standby power supply circuit 6 side. Therefore, when the main power supply circuit 7 is turned on by the main power supply on / off control signal input 10, the drive voltage can be supplied from the main power supply circuit 7 side to the gate terminal of the thyristor 32, and the thyristor 32 is turned on. On the other hand, when the main power supply circuit 7 is stopped by the main power supply output on / off control signal input 10, the voltage supply to the gate terminal of the thyristor 32 is not performed, and the thyristor 32 is not turned on.

Here, the standby power supply circuit 6 and the main power supply circuit 7 illustrated in FIGS. 1B and 1C will be described. These are the insulation composed of the primary circuit and the secondary circuit connected via the transformer 23. It is of shape. The primary side circuit is provided with a switching main circuit unit 26 for performing output control, and the secondary side circuit is provided with an output rectifying / smoothing circuit 27 for rectifying and smoothing the electric power received from the transformer. In the output control of the standby power supply circuit 6 and the main power supply circuit 7 according to this example, the magnitude of the secondary output output to the standby power supply output terminal 8 or the main power supply output terminal 9 is determined based on the output detection circuits 24 and 1-2. This is performed by feeding back to the switching main circuit portion 26 of the primary side circuit via the photocoupler 25 for insulation between the secondary circuits. The main power supply output on / off control signal input 10 is also input to the switching main circuit portion 26 of the main power supply circuit 7 shown in FIG.
Further, the main power supply circuit 7 illustrated in FIG. 1C is configured to supply a voltage to the gate terminal of the thyristor 32 using an auxiliary winding provided in the transformer 23. That is, after the AC power supply P is turned on, when the main power supply circuit 7 is started through a transient state, a voltage is generated in the transformer 23 and its auxiliary winding. Therefore, this auxiliary winding voltage is supplied to the thyristor via the resistor 29 and the rectifier diode 28. When the main power supply circuit 7 is turned on, the thyristor 32 is maintained in the on state by inputting to the gate terminal 32.

[Operation]
Next, a schematic operation of the switching power supply circuit 1 of the present embodiment having the above-described configuration will be described. Hereinafter, the operation of the switching power supply circuit 1 when the AC power supply is turned on from the initial state and the main power supply operation mode or the standby mode is shifted will be described. In the initial state, it is assumed that the thyristor 32 is off and is in a standby mode.

  First, when the AC power supply P is turned on, the AC voltage is rectified by the rectifier circuit 2 and smoothed by the smoothing capacitor 5. At this time, the inrush current flowing toward the respective power supply circuits through the full-wave rectifier diode is suppressed by the power thermistor 31. After this transient state, standby power supply circuit 6 or main power supply circuit 7 is activated.

When the main power supply circuit 7 is turned on by the main power supply on / off control signal input 10 and enters the main power supply operation mode, the drive voltage is supplied from the main power supply circuit 7 side to the gate terminal of the thyristor 32 and the thyristor 32 is turned on. Thus, both ends of the power thermistor 31 are short-circuited.
Thereby, in the switching power supply circuit 1 according to the present embodiment, even when a large amount of power is extracted from the main power supply output 9 side, a large current does not flow to the power thermistor 3 but flows to the thyristor 32 in the on state. The power thermistor 31 does not generate heat abnormally, and wasteful power consumption does not occur in this portion.

On the other hand, when the standby mode is entered, the main power supply circuit 7 is stopped by the main power supply output on / off control signal input 10 so that the voltage supply to the gate terminal of the thyristor 32 is not performed. Thus, in the standby mode, the drive power of the thyristor 32 is not consumed and power saving is realized. In this standby mode, the thyristor 32 is turned off and a current flows through the power thermistor 31.
However, in the standby mode, the output is only the standby power output 8 having a very small power, and therefore, although the power thermistor 31 is slightly self-heated, considering that the resistance value of the thermistor decreases due to the self-heating, the power thermistor in the standby mode. No abnormal heat is generated in the portion 31 and no wasteful power consumption occurs in this portion.
Therefore, the power thermistor 31 can be selected from small power thermistors that match the standby power output 8 of minute power.

  As described above, according to the switching power supply circuit of the present embodiment, it is possible to reduce power consumption during standby more than before, and the number of components constituting the rectifying and smoothing circuit and the inrush current preventing circuit can be reduced. A small number of switching power supply devices can be realized.

[Second Embodiment]
FIG. 2 shows a switching power supply circuit according to the second embodiment of the present invention. The circuit shown in FIG. 2 is obtained by replacing the thyristor 32 with a triac 33 as an alternative circuit to the inrush current suppressing circuit of FIG. The T2 side of the triac 33 is connected to the rectified output plus side terminal of the rectifier circuit 2, and the T1 side is connected to the plus pole of the smoothing circuit 5. The configurations of the standby power supply circuit 6 and the main power supply circuit 7 illustrated are the same as those described in the section of the first embodiment.
Therefore, the operation of the switching power supply circuit according to the present embodiment is substantially the same as the operation of the switching power supply circuit according to the first embodiment in both the main power supply operation mode and the standby mode.
Thus, even with the switching power supply circuit of the second embodiment, it is possible to reduce power consumption during standby more than before, and the number of parts constituting the rectifying and smoothing circuit and the inrush current preventing circuit can be reduced. A small number of switching power supply devices can be realized.

[Third Embodiment]
FIG. 3 shows a switching power supply circuit according to the third embodiment of the present invention. 3, the parallel connection circuit of the power thermistor 31 and the triac 33 in FIG. 2 is connected between the rectified output plus side terminal of the rectifier circuit 2 and the plus pole of the smoothing circuit 5, and the rectified output minus side terminal of the rectifier circuit 2. And between the negative poles of the smoothing circuit 5. The configurations of the standby power supply circuit 6 and the main power supply circuit 7 illustrated are the same as those described in the section of the first embodiment.
Signal supply to the gate of the triac 33 is performed from the main power supply circuit 7 side as in the first embodiment. The T2 side of the triac 33 is connected to the rectified output minus side terminal of the rectifier circuit 2, and the T1 side is connected to the minus pole of the smoothing circuit 5.
As described above, in the present embodiment, the inrush current suppression circuit including the parallel connection circuit of the power thermistor 31 and the triac 33 is connected to the negative side of the standby power supply circuit 6 and the main power supply circuit 7. Therefore, in the present embodiment, the configuration of the gate drive circuit provided between the gate of the triac 33 and the main power supply circuit 7 is slightly different from the above examples. That is, in this embodiment, unlike the first embodiment, the rectifier diode 28 is connected in the reverse direction, and the gate trigger auxiliary winding is connected to the negative side of the main power supply circuit 7.
The operation of the switching power supply circuit according to the present embodiment is substantially the same as the operation of the switching power supply circuit according to the first embodiment and the second embodiment in both the main power supply operation mode and the standby mode.
As described above, the switching power supply circuit according to the third embodiment can reduce the power consumption during standby as compared with the first embodiment and the rectification and smoothing circuit, as in the first embodiment and the second embodiment. In addition, it is possible to realize a switching power supply device with a small number of parts constituting the inrush current prevention circuit.

  Using the switching power supply circuit according to the present embodiment configured as described above and the switching power supply circuit according to the conventional example, as a result of comparing the number of parts of both and the input power consumption during standby, the switching power supply according to the present embodiment In the circuit, a better result was obtained than in the conventional example. An example of the comparison results is shown in the table below. Note that the comparison was performed under the same conditions using circuits having the same specifications.

  As is clear from Table 1, the switching power supply circuit according to this embodiment has a smaller number of parts and lower input power consumption than the conventional example.

[Modification]
As mentioned above, although this invention was demonstrated in detail based on one Embodiment, this invention is not limited to the structure as described in the said embodiment, A various design change is possible.
For example, the standby power supply circuit 6 and the main power supply circuit 7 of the above embodiment are not limited to the configurations exemplified in the above embodiments, and various types of switching power supply circuits can be used. Examples of the circuit format of the switching power supply circuit include chopper circuits such as a step-up type, a step-down type, and a step-up / step-down type, as well as insulating converters having various bridge configurations, but are not particularly limited. It is not particularly limited whether or not the soft switching technology is applied to these switching power supply circuits.
In addition, a power factor correction circuit may be connected in front of the standby power supply circuit or the main power supply circuit.
Further, the control method of the standby power supply circuit or the main power supply circuit is not particularly limited, and various methods such as frequency control, duty control, and phase control can be used.

Further, the specific application target of the switching power supply circuit of the present invention is not particularly limited as long as it is a target that requires two operation modes of the main power supply operation mode and the standby mode in one device. Therefore, the switching power supply circuit according to the present invention can be used for office automation equipment such as personal computers, printers, copiers, and fax machines, and household electrical appliances, particularly equipment that can be operated with a remote control switch (air conditioner, lighting, telephone, television, video, and other AV equipment ) And the like.
The power capacities of the standby power supply circuit and the main power supply circuit are not particularly limited, and the present invention can be applied regardless of the power capacity of the main power supply circuit.

As for the power control device, the thyristor or the triac is used in the above embodiment, but the invention is not limited thereto. For example, a self-turn-off type switching element such as IGBT or MOSFET is used alone, or a plurality of switching elements are used. May be used in appropriate combinations. Even in this case, the standby mode and the main power supply operation mode can be appropriately switched and controlled.
The trigger energy input to the gate terminal is also based on normal electrical energy (voltage) in the above embodiment, but is not limited to this, and various things such as light and heat may be used.
Regarding the form of the rectifier circuit, in the above embodiment, the diode bridge is used as the full-wave rectifier diode. However, the form of the rectifier circuit such as a single-phase half-wave rectifier circuit using one simplest rectifier diode is used. Not limited to. Furthermore, it is possible to replace all or part of the diodes constituting the rectifier circuit with a switching element such as a thyristor so as to perform control rectification.

  As described above, it is apparent that the present invention can provide a highly efficient switching power supply circuit that has a smaller number of parts and consumes less standby power than before.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the switching power supply circuit by the Example of this invention, (a) is the whole circuit diagram, (b) is a circuit diagram which shows an example of a standby power supply circuit, (c) is a circuit which shows an example of a main power supply circuit FIG. It is a figure which shows the switching power supply circuit by other Example of this invention, (a) is the whole circuit diagram, (b) is a circuit diagram which shows an example of a standby power supply circuit, (c) is an example of a main power supply circuit FIG. It is a figure which shows the switching power supply circuit by other Example of this invention, (a) is the whole circuit diagram, (b) is a circuit diagram which shows an example of a standby power supply circuit, (c) is an example of a main power supply circuit FIG. It is a figure which shows the switching power supply circuit by a prior art example, (a) is the whole circuit diagram, (b) is a circuit diagram which shows an example of a standby power supply circuit, (c) is a circuit diagram which shows an example of a main power supply circuit. . It is a figure which shows the switching power supply circuit by another prior art example, (a) is the whole circuit diagram, (b) is a circuit diagram which shows an example of a standby power supply circuit, (c) is a circuit diagram which shows an example of a main power supply circuit It is. It is a figure which shows the switching power supply circuit by another prior art example, (a) is the whole circuit diagram, (b) is a circuit diagram which shows an example of a standby power supply circuit, (c) is a circuit diagram which shows an example of a main power supply circuit It is. It is a figure which shows the switching power supply circuit by another prior art example, (a) is the whole circuit diagram, (b) is a circuit diagram which shows an example of a standby power supply circuit, (c) is a circuit diagram which shows an example of a main power supply circuit It is.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Switching power supply circuit 2, 12, 13 Rectifier circuit 3, 14 Thermistor 4, 15, 20 Thyristor 5, 17, 18 Smoothing circuit 6 Standby power circuit 7 Main power circuit 8 Standby power output 9 Main power output 10 Main power output ON / OFF control signal input 11, 19, 22 Triac 14 Power thermistor 16, 21 Inrush current suppression resistor 23 Transformer 24 Output detection circuit 25 Photocoupler 26 Switching main circuit section 27 Output rectification / smoothing circuit 28 Diode 29 Resistance 30 Inrush current suppression device 31 Thermistor 32 Thyristor 33 Triac

Claims (3)

A standby power supply circuit that supplies a standby power supply output and a main power supply circuit that supplies a main power supply output, and supplies power to the standby power supply circuit and the main power supply circuit before the standby power supply circuit and the main power supply circuit. A switching power supply device including a common rectifier circuit and a smoothing circuit,
At any position between the rectified output plus side terminal of the rectifier circuit and the plus pole of the smoothing circuit, or between the rectified output minus side terminal of the rectifier circuit and the minus pole of the smoothing circuit,
The thermistor,
Inrush comprising a parallel connection circuit with a power control device that can switch the operation / operation stop of the main power supply circuit by an external on / off signal and can control the conduction / non-conduction state in accordance with the operation / operation stop of the main power supply circuit A current suppression device is connected in series ,
In the main power supply operation mode in which the main power supply circuit operates, the power control device is turned on to short-circuit both ends of the thermistor, while in the standby mode, the operation of the main power supply circuit is stopped to A switching power supply device characterized by being in a non-conductive state .   2. The switching power supply device according to claim 1, wherein the power control device includes a thyristor, and the external on / off signal is supplied from the main power supply circuit to a gate terminal of the thyristor.   2. The switching power supply device according to claim 1, wherein the power control device includes a triac, and the external on / off signal is supplied from the main power supply circuit to a gate terminal of the triac.

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