JPH0218703Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to a switching power supply device that can receive DC and AC power as input.

[Technical background of the invention and its problems]

FIG. 1 shows a known switching power supply. In the DC input section, the positive pole of the DC power supply 11 is connected to one end of the primary winding 13 ₁ of the converter transformer 13 via the switch 12 . At the other end of this primary winding ₁₃₁ is a transistor 14.
The collector of this transistor 14 is connected, and the emitter of this transistor 14 is connected to the negative electrode of the DC power supply 11. A series circuit consisting of a reset coil 13 ₂ and a diode 15 and a capacitor 16 are connected in parallel between one end of the primary winding 13 ₁ of the transformer 13 and the emitter of the transistor 14 .
Further, the secondary winding 1 of the converter transformer 13
One end of the secondary winding 13 ₃ is connected to one output end 19 via a diode 17 and a chi-yoke coil 18, and the other end of the secondary winding 13 ₃ is connected to a connection point between the diode 19 and the chi-yoke coil 18 via a diode 20. and is connected to the other output terminal 21. A capacitor 22 is connected between these output ends 20 and 22. The output voltage of this capacitor 22 is supplied to a voltage control circuit 23. This voltage control circuit 23 generates pulse signals with different duties depending on the output voltage, and this output pulse signal is supplied between the base and emitter of the transistor 14.

On the other hand, in the AC input section, one end of the AC power supply 24 is connected to the other end of the AC power supply 24 via the switch 25 and the primary winding 26 ₁ of the power transformer 26 . The secondary winding 26 ₂ of the transformer 26 is connected to the input end of a bridge rectifier circuit 27 , and the output end of this rectifier circuit 27 is connected to both ends of the capacitor 16 . This rectified output voltage is the DC power supply 11
The output voltage is said to be the same as that of

In the above configuration, when the DC power supply 11 is used as an input, only the switch 12 is turned on, and when the AC power supply 24 is used as an input, only the switch 25 is turned on. is generated.

However, in the above configuration, the power transformer 26 is used in the AC input section. This power transformer 26 has an input voltage of, for example, 100 [V] or 50 [V].
If you try to obtain 200 [W] of power at [Hz] and an output voltage of 10 [V], the size will be large and the weight will be very heavy, about 7 [Kg].

Furthermore, since the bridge rectifier circuit 27 is also a low-voltage, large-current rectifier circuit, if rectifier diodes with the same forward voltage (V _F ) are used, the loss of the rectifier diodes will be greater than when rectifying alternating current directly. , which has the problem of reduced efficiency.

[Purpose of invention]

This idea was made based on the above circumstances, and its purpose is to create a small, lightweight, and highly efficient switching power supply device by not using a power transformer or a low-voltage, high-current rectifier diode in the AC input section. This is what we are trying to provide.

[Summary of the idea]

The switching power supply device according to this invention has first and second windings of the same polarity for one secondary winding.
Using a converter transformer formed by coupling primary windings, the output of the AC power source is directly rectified by a first rectifying means, and the rectified output is intermittently supplied to the first primary winding by a first switching means. On the other hand, the output of the DC power source is switched on and off by the second switching means and supplied to the second primary winding.
At this time, the selection means selectively connects the AC power supply or the DC power supply, the AC current output from the secondary winding of the converter transformer is rectified by the second rectification means, and the output of the second rectification means is A coil and a capacitor provide a smoothed output, and a control means controls the first and second switching means based on this smoothed output to stabilize the smoothed output. Here, when the AC power source is selectively connected by the selection means, the output of the AC power source is taken out and rectified by the third rectifying means, and this rectified output is sent to the second primary winding via the second switching means. energization of the second winding in conjunction with energization of the first winding to prevent reverse voltage from being applied to the second switching means. On the other hand, when the AC power supply is selectively connected by the selection means, the rectified output of the third rectification means is used as a driving power source for the control means. When the DC power source is selectively connected, the output of the power source is used as a driving source for the control means.

[Example of idea]

An embodiment of this invention will be described below with reference to the drawings.

In FIG. 2, one end of an AC power source 31 constituting an AC input section is connected to one input end of a bridge rectifier circuit 33 via a switch 32, and the other input end of this rectifier circuit 33 is connected to the other input end of the AC power source 31. Connected to the end. A smoothing capacitor 34 is connected between the output terminals of the rectifier circuit 33, and one output terminal of the rectifier circuit 33 is connected to an AC primary winding 36 1 of a converter transformer 36 via a diode ₃₅ .
connected to one end of the The other end of this primary winding 36 ₁ is connected to the drain of a field effect transistor FET 37 , and the source of this FET 37 is connected to the other output end of the rectifier circuit 33 . A reset coil 36 ₂ of the AC primary winding 36 1 is connected between one end of the primary winding 36 ₁ and the source of the FET 37 _.
A series circuit consisting of a diode 38 and a capacitor 39 are connected in parallel. Further, the secondary winding 36 in the converter transformer 36
One end of ₃ is a diode 40 and a chiyoke coil 41
is connected to one output end 42 via the secondary winding 3
The other end of the diode 6 ₃ is connected to the connection point between the diode 40 and the chiyoke coil 41 via a diode 43 , and is also connected to the other output end 44 . A smoothing capacitor 45 is connected between these output ends 42 and 44. This capacitor 45
The output voltage of is supplied to the voltage control circuit 46. This voltage control circuit 46 generates pulse signals with different duties depending on the output voltage, and one of the output pulse signals is sent to the FET 37.
is supplied to the gate.

On the other hand, in the DC input section, the positive electrode of the DC power supply 47 is connected to the converter transformer 3 through a switch 48.
6 is connected to one end of the DC primary winding ₃₆₄ . A collector of a transistor 49 is connected to the other end of the primary winding 36 ₄ , and an emitter of the transistor 49 is connected to the negative electrode of the DC power supply 47 . A reset coil 365 of the DC primary winding ₃₆₄ and a diode ₅₀ are connected between one end of the primary winding ₃₆₄ and the emitter of the transistor 49.
A series circuit consisting of a capacitor 51 and a capacitor 51 are each connected in parallel. Further, a switch 52 is provided which is interlocked with the switch 48. The movable contact piece of this switch 52 is connected to the switch 32 of the AC input section.
It is connected to a fixed contact of a switch 53 that operates in conjunction with the switch 53. The movable contact piece of this switch 53 is connected to the movable contact piece of the switch 48 at the DC input section. Further, the fixed contact of the switch 52 and the DC power supply 47
A trip coil TC54 for turning off the switches 48 and 52 is provided between the negative electrodes of the switch. moreover,
This DC input section is provided with a circuit that supplies a power supply voltage to the voltage control circuit 46 when the AC input section is operated. That is, the auxiliary transformer 5 is connected to both input ends of the bridge rectifier circuit 33 in the AC input section.
5 primary winding 55 ₁ is connected, and this transformer 5
The secondary winding 55 ₂ of No. 5 is connected to both input ends of the bridge rectifier circuit 56 . One output end of this rectifier circuit 56 is connected to the negative pole of the DC power supply 47, and the other output end is connected to the power supply connection end of the voltage control circuit 46, and the switch 48 is connected via a diode 57 and a resistor 58. Connected to a movable contact piece.

The secondary output voltage of the auxiliary transformer 55 is applied to the DC primary winding ₃ by operating the AC input section and by the voltage E1 output from the bridge rectifier circuit 33.
The voltage induced at ₆₄ is set so that the voltage between the collector and emitter of the transistor 49 does not become reverse biased.

Further, the voltage control circuit 46 is operated by power supplied from the DC power supply 47 when the DC input section is operated.

Additionally, a diode 35 and a capacitor 39
This is to prevent the large capacity capacitor 34 from being charged by the voltage induced in the AC primary winding 36 ₁ and the reset coil 36 ₂ when the DC input section is operated.

The operation in the above configuration will be explained. switch 3
2 is turned on, the voltage control circuit 46 is operated by the output voltage of the rectifier circuit 56, and the pulse signal output from this voltage control circuit 46 operates the voltage control circuit 46.
FET37 is driven. Therefore, output end 4
A DC stabilized output using an AC power supply 31 is obtained between the 2 and 44.

Further, when only the switch 48 is turned on, the voltage control circuit 46 is operated by the DC power supply 47,
A transistor 49 is driven by a pulse signal output from the voltage control circuit 46. Therefore, the DC power supply 4 is connected between the output ends 42 and 44.
DC stabilized output using 7 can be obtained.

Further, when the switch 48 is turned on while the switch 32 is turned on, the trip coil 54
is energized, and the switches 48 and 52 are returned to the off state. Therefore, the AC input section is operated with priority, and a DC stabilized output using the AC power supply 47 is obtained.

According to the above embodiment, in the AC input section, the output current of the AC power source 31 is directly rectified by the rectifier circuit 33, and this rectified output is supplied to the primary winding ₃₆₁ of the converter transformer 36, and is switched by the FET 37. . Therefore, since a conventional power transformer is not required, the circuit can be made smaller and lighter. Note that since the auxiliary transformer 55 is used to supply power to the voltage control circuit 46, it has a small power capacity and is much smaller and lighter than the power transformer.

Further, since the rectifier circuit 33 directly rectifies the alternating current, the loss of the diodes that constitute the rectifier circuit 33 is small, and high efficiency can be achieved.

In the above embodiment, a case has been described in which the present invention is applied to a switching power supply device having a single configuration using one switching element, but it is also possible to apply this invention to a switching power supply device having a push-pull configuration.

Of course, various other modifications can be made without changing the gist of the invention.

[Effect of idea]

As described in detail above, according to this invention, a power transformer and a low-voltage, large-current rectifier diode are not used in the AC input section, so that a small, lightweight, and highly efficient switching power supply device can be provided.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an example of a conventional switching power supply device, and FIG. 2 is a circuit diagram showing an embodiment of the switching power supply device according to the invention. 31... AC power supply, 32... switch, 33...
... Bridge rectifier circuit, 36 ... Converter transformer, 37 ... FET, 40, 43 ... Diode,
41...Chiyoke coil, 45...Capacitor,
46... Voltage control circuit, 47... DC power supply, 49
...Transistor.

Claims (1)

[Scope of utility model registration request] a converter transformer formed by coupling first and second primary windings of the same polarity to one secondary winding; a first rectifier for directly rectifying alternating current supplied from an alternating current power supply; a first switching means that intermittents the rectified output of the first rectifying means and supplies it to the first primary winding; 2 switching means, and selection means for selectively connecting the AC power source or the DC power source;
a second rectifying means provided in the secondary winding of the converter transformer, a coil connected in series to the output end of the second rectifying means, a capacitor for smoothing the output of this coil, and a capacitor of this capacitor. A control means for controlling the first and second switching means based on the smoothed output; and a third rectifying means for extracting the output of the AC power source and outputting the rectified output when the AC power source is selectively connected by the selection means. and a first auxiliary power supply means for supplying the rectified output of the third rectification means to the second primary winding via the second switching means, and an AC power supply selectively connected by the selection means. and a second auxiliary power supply means for supplying the rectified output of the third rectifying means when the DC power source is connected to the DC power supply as a driving power source for the control means. Features a switching power supply device.