CA1226896A - Pulse absorption circuit for power source circuit - Google Patents
Pulse absorption circuit for power source circuitInfo
- Publication number
- CA1226896A CA1226896A CA000471351A CA471351A CA1226896A CA 1226896 A CA1226896 A CA 1226896A CA 000471351 A CA000471351 A CA 000471351A CA 471351 A CA471351 A CA 471351A CA 1226896 A CA1226896 A CA 1226896A
- Authority
- CA
- Canada
- Prior art keywords
- circuit
- capacitor
- transformer
- power source
- pulse
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Abstract
Abstract of the Disclosure A pulse absorbing circuit for a power source circuit for absorbing an abnormal pulse when an input current at a primary winding of an output transformer in a switching power source is cut off, has: a capacitor, one end of which is connected to a primary winding output terminal of a transformer in a phase opposite to a primary winding input terminal thereof; a first rectifying element, an anode of which is connected to the other end of said capacitor and a cathode of which is connected to an output terminal of a rectifying circuit arranged at a secondary winding side of said transformer; a second rectifying element, a cathode of which is connected to a junction between said first rectifying element and said capacitor; and a conductor inserted between a ground terminal and said second rectifying element. The conductor has, for example, a coil for absorbing and effectively reutilizing abnormal pulse energy.
Description
2'Z~;~96 Background of the Invention (1) Field of the Invention The present invention relates to a pulse absorption circuit for absorbing an abnormal pulse generated at a secondary winding when an input current is cut off at a primary winding of an output transformer in a switching power source.
In some conventional pulse absorption circuits, pulse energy is absorbed by a circuit loss, thereby degrading efficiency of the power source.
It is an object of the present invention to provide a pulse absorption circuit for properly absorbing an abnormal pulse and reutilizing absorbed energy, thereby improving efficiency of a power source voltage.
According to the present invention there is provided a pulse absorption circuit for a switching power source circuit for supplying or cutting off an input current at a primary winding of a transformer upon ON/OFF open-anion of a switching element, and for rectifying and smoothing an output of a secondary winding of said transformer by means of a diode and a smoothing capacitor, comprising: a capacitor, one end of which is connected to a primary winding output terminal of the transformer in a phase opposite to a primary winding input terminal thereof; a first rectifying element, an anode of which is connected to the other end of said capacitor and a cathode of which is connected to an output terminal of a rectifying circuit arranged at a secondary winding side of said transformer; a second rectifying element, I I, I
a cathode of which is connected to a junction between said first rectifying element and said capacitor; and a conductor inserted between a ground terminal and said second rectifying element.
Brief Description of the Drawings Figs. 1 to 4 are circuit diagrams showing convent tonal pulse absorption circuits for a power source circuit, respectively;
Fig. 5 is a circuit diagram of a pulse absorption circuit for a power source circuit according to an em-bodiment of the present invention; and Fig. 6 is a circuit diagram of a pulse absorption circuit for a power source circuit according to another embodiment of the present invention.
Description of the Prior Art Conventionally, a pulse absorption circuit is arranged in an output transformer of a switching power source. In typical conventional pulse absorption circuits S shown in Figs. 1 to 4, each circuit S is connected between a ground side terminal To of a primary winding of a trays-former T and a ground terminal El i.e., between the collector and emitter of a switching transistor Q. In the arrangement shown in Fig. 1, a snubber comprises a series circuit of a capacitor C and a resistor R. In the arrangement shown in Fig. I varister B is used to constitute a pulse absorption circuit. In the arrange-mint shown in Fig. 3, a Zoner diode Z is used to absorb a pulse component having a voltage exceeding a predator-mined voltage. In the arrangement shown in Fig. 4, a clamp circuit is arranged wherein a diode D is connected in series wit a capacitor C, and a common junction there-between is connected to a ground terminal E through a resistor R.
In these conventional pulse absorption circuits, pulse energy is absorbed by a circuit loss, thereby degrading efficiency of the power source.
Detailed Description of the Preferred Embodiments A pulse absorption circuit according to an embody-lo mint of the present invention will be described with reference to Fig. 5.
Referring to Fig. 5, reference symbol T denotes a transformer; and Q, a switching transistor for supplying or cutting off a current with respect to a primary winding Lo. Reference symbols Lo and Lo denote secondary windings of the transformer T. An output from the secondary winding Lo is rectified and smoothed through a rectifying diode Do, a choke coil Lo and a smoothing capacitor Of. Refer-once numeral l denotes a pulse absorption circuit. The pulse absorption circuit l comprises: a capacitor C2, one end of which is connected to a primary winding output terminal P of the I-", --Jo ,. /
I..
~.ZZ~j~96 transformer T in a phase opposite to a primary winding input terminal thereof; a diode Do as a first rectifying element, an anode of which is connected to the other end of the capacitor C2 and a cathode of which is connected to an output terminal OUT of a rectifying circuit arranged at a secondary winding side of the transformer T; a diode Do as a second rectifying element, a cathode of which is connected to a junction between the diode Do and the capacitor C2; and a conductor inserted between a ground terminal E and the rectifying element Do. The conductor comprises a coil Lo.
The operation of the pulse absorption circuit will be described hereinafter. When an electromotive force is generated at the secondary winding Lo of the transformer 1' in such a manner that the diode Do is reverse biased, the capacitor C2 is charged by the electromotive force at the winding Lo through the coil Lo and the diode Do. In this case, the coil Lo is operated to reduce pulse noise by slowly charging the capacitor C2. Louvre, the coil Lo may be omitted.
When the coil Lo is omitted, the anode of the diode Do is directly connected to the ground terminal E.
Thereafter, when the polarity of the output voltage at the winding Lo is inverted, the capacitor C2 is discharged through the diode Do since a voltage of the winding Lo causes the output terminal P to be set at a ~26~9~
positive potential. The discharge voltage thus appears at the output terminal OUT. The pulse noise generated at the side of the winding Lo can be absorbed by the capacitor C2. In addition, the pulse noise energy can be effectively utilized to improve efficiency of the power source voltage.
Fig. 6 shows another embodiment of the present invention. Only a winding Lo is provided as a secondary winding of a transformer T. In this embodiment, pulse noise energy is supplied to the secondary winding only when a switching transistor Q is turned off. The arrangement of the pulse absorption circuit 1 is the same as that of the previous embodiment (Fig. 5), except that one end of a capacitor C2 is connected to one end (secondary output terminal P
having a phase opposite to the primary input terminal) of the winding Lo.
When an electromotive force is generated in the winding Lo in such a manner that a diode Do is reverse biased, the capacitor C2 is charged through a coil Lo and a diode Do. Thereafter, when the polarity of the secondary winding output is inverted upon OFF operation of a transistor Q, a smoothing capacitor C1 is charged through the diode Do. In this case, the charge at the capacitor C2 is supplied to the output terminal OUT
through the diode Do. In the same manner as in the first embodiment, the pulse generated at the winding Lo is absorbed by the capacitor C2. In addition, when the transistor Q is on, the energy charged in the capacitor C2 can be effectively utilized.
According to the pulse absorption circuit for a power source circuit of the present invention, the abnormal pulse generated when the input current at the primary winding of the output transformer in the switching power source is cut off can be absorbed at the secondary winding side. In addition, absorbed energy can be effectively utilized to greatly improve the power source voltage.
There has been described a pulse absorbing circuit for a power source circuit for absorbing an abnormal pulse when an input current at a primary winding of an output transformer in a switching power source is cut off, comprising: a capacitor, one end of which is connect-Ed to a primary winding output terminal of the transformer in a phase opposite to a primary winding input terminal thereof; a first rectifying element, an anode of which is connected to the other end of said capacitor and a cathode of which is connected to an output terminal of a rectifying circuit arranged at a secondary winding side of said transformer; a second rectifying element, a cathode of which is connected to a junction between said first rectifying element and said capacitor; and a con-doctor inserted between a ground terminal and said second rectifying element. The conductor comprises, for example, a coil for absorbing the abnormal pulse to effectively reutilize abnormal pulse energy.
In some conventional pulse absorption circuits, pulse energy is absorbed by a circuit loss, thereby degrading efficiency of the power source.
It is an object of the present invention to provide a pulse absorption circuit for properly absorbing an abnormal pulse and reutilizing absorbed energy, thereby improving efficiency of a power source voltage.
According to the present invention there is provided a pulse absorption circuit for a switching power source circuit for supplying or cutting off an input current at a primary winding of a transformer upon ON/OFF open-anion of a switching element, and for rectifying and smoothing an output of a secondary winding of said transformer by means of a diode and a smoothing capacitor, comprising: a capacitor, one end of which is connected to a primary winding output terminal of the transformer in a phase opposite to a primary winding input terminal thereof; a first rectifying element, an anode of which is connected to the other end of said capacitor and a cathode of which is connected to an output terminal of a rectifying circuit arranged at a secondary winding side of said transformer; a second rectifying element, I I, I
a cathode of which is connected to a junction between said first rectifying element and said capacitor; and a conductor inserted between a ground terminal and said second rectifying element.
Brief Description of the Drawings Figs. 1 to 4 are circuit diagrams showing convent tonal pulse absorption circuits for a power source circuit, respectively;
Fig. 5 is a circuit diagram of a pulse absorption circuit for a power source circuit according to an em-bodiment of the present invention; and Fig. 6 is a circuit diagram of a pulse absorption circuit for a power source circuit according to another embodiment of the present invention.
Description of the Prior Art Conventionally, a pulse absorption circuit is arranged in an output transformer of a switching power source. In typical conventional pulse absorption circuits S shown in Figs. 1 to 4, each circuit S is connected between a ground side terminal To of a primary winding of a trays-former T and a ground terminal El i.e., between the collector and emitter of a switching transistor Q. In the arrangement shown in Fig. 1, a snubber comprises a series circuit of a capacitor C and a resistor R. In the arrangement shown in Fig. I varister B is used to constitute a pulse absorption circuit. In the arrange-mint shown in Fig. 3, a Zoner diode Z is used to absorb a pulse component having a voltage exceeding a predator-mined voltage. In the arrangement shown in Fig. 4, a clamp circuit is arranged wherein a diode D is connected in series wit a capacitor C, and a common junction there-between is connected to a ground terminal E through a resistor R.
In these conventional pulse absorption circuits, pulse energy is absorbed by a circuit loss, thereby degrading efficiency of the power source.
Detailed Description of the Preferred Embodiments A pulse absorption circuit according to an embody-lo mint of the present invention will be described with reference to Fig. 5.
Referring to Fig. 5, reference symbol T denotes a transformer; and Q, a switching transistor for supplying or cutting off a current with respect to a primary winding Lo. Reference symbols Lo and Lo denote secondary windings of the transformer T. An output from the secondary winding Lo is rectified and smoothed through a rectifying diode Do, a choke coil Lo and a smoothing capacitor Of. Refer-once numeral l denotes a pulse absorption circuit. The pulse absorption circuit l comprises: a capacitor C2, one end of which is connected to a primary winding output terminal P of the I-", --Jo ,. /
I..
~.ZZ~j~96 transformer T in a phase opposite to a primary winding input terminal thereof; a diode Do as a first rectifying element, an anode of which is connected to the other end of the capacitor C2 and a cathode of which is connected to an output terminal OUT of a rectifying circuit arranged at a secondary winding side of the transformer T; a diode Do as a second rectifying element, a cathode of which is connected to a junction between the diode Do and the capacitor C2; and a conductor inserted between a ground terminal E and the rectifying element Do. The conductor comprises a coil Lo.
The operation of the pulse absorption circuit will be described hereinafter. When an electromotive force is generated at the secondary winding Lo of the transformer 1' in such a manner that the diode Do is reverse biased, the capacitor C2 is charged by the electromotive force at the winding Lo through the coil Lo and the diode Do. In this case, the coil Lo is operated to reduce pulse noise by slowly charging the capacitor C2. Louvre, the coil Lo may be omitted.
When the coil Lo is omitted, the anode of the diode Do is directly connected to the ground terminal E.
Thereafter, when the polarity of the output voltage at the winding Lo is inverted, the capacitor C2 is discharged through the diode Do since a voltage of the winding Lo causes the output terminal P to be set at a ~26~9~
positive potential. The discharge voltage thus appears at the output terminal OUT. The pulse noise generated at the side of the winding Lo can be absorbed by the capacitor C2. In addition, the pulse noise energy can be effectively utilized to improve efficiency of the power source voltage.
Fig. 6 shows another embodiment of the present invention. Only a winding Lo is provided as a secondary winding of a transformer T. In this embodiment, pulse noise energy is supplied to the secondary winding only when a switching transistor Q is turned off. The arrangement of the pulse absorption circuit 1 is the same as that of the previous embodiment (Fig. 5), except that one end of a capacitor C2 is connected to one end (secondary output terminal P
having a phase opposite to the primary input terminal) of the winding Lo.
When an electromotive force is generated in the winding Lo in such a manner that a diode Do is reverse biased, the capacitor C2 is charged through a coil Lo and a diode Do. Thereafter, when the polarity of the secondary winding output is inverted upon OFF operation of a transistor Q, a smoothing capacitor C1 is charged through the diode Do. In this case, the charge at the capacitor C2 is supplied to the output terminal OUT
through the diode Do. In the same manner as in the first embodiment, the pulse generated at the winding Lo is absorbed by the capacitor C2. In addition, when the transistor Q is on, the energy charged in the capacitor C2 can be effectively utilized.
According to the pulse absorption circuit for a power source circuit of the present invention, the abnormal pulse generated when the input current at the primary winding of the output transformer in the switching power source is cut off can be absorbed at the secondary winding side. In addition, absorbed energy can be effectively utilized to greatly improve the power source voltage.
There has been described a pulse absorbing circuit for a power source circuit for absorbing an abnormal pulse when an input current at a primary winding of an output transformer in a switching power source is cut off, comprising: a capacitor, one end of which is connect-Ed to a primary winding output terminal of the transformer in a phase opposite to a primary winding input terminal thereof; a first rectifying element, an anode of which is connected to the other end of said capacitor and a cathode of which is connected to an output terminal of a rectifying circuit arranged at a secondary winding side of said transformer; a second rectifying element, a cathode of which is connected to a junction between said first rectifying element and said capacitor; and a con-doctor inserted between a ground terminal and said second rectifying element. The conductor comprises, for example, a coil for absorbing the abnormal pulse to effectively reutilize abnormal pulse energy.
Claims (2)
1. A pulse absorption circuit for a switching power source circuit for supplying or cutting off an input current at a primary winding of a transformer upon ON/OFF operation of a switching element, and for rectifying and smoothing an output of a secondary winding of said transformer by means of a diode and a smoothing capacitor, comprising: a capacitor, one end of which is connected to a primary winding output terminal of the transformer in a phase opposite to a primary winding input terminal thereof; a first rectifying element, an anode of which is connected to the other end of said capacitor and a cathode of which is connected to an output terminal of a rectifying circuit arranged at a secondary winding side of said transformer; a second rectifying element, a cathode of which is connected to a junction between said first rectifying element and said capacitor; and a conductor inserted between a ground terminal and said second rectifying element.
2. A pulse absorption circuit according to claim 1, wherein said conductor comprises a coil.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000471351A CA1226896A (en) | 1985-01-02 | 1985-01-02 | Pulse absorption circuit for power source circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000471351A CA1226896A (en) | 1985-01-02 | 1985-01-02 | Pulse absorption circuit for power source circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1226896A true CA1226896A (en) | 1987-09-15 |
Family
ID=4129498
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000471351A Expired CA1226896A (en) | 1985-01-02 | 1985-01-02 | Pulse absorption circuit for power source circuit |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1226896A (en) |
-
1985
- 1985-01-02 CA CA000471351A patent/CA1226896A/en not_active Expired
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| MKEX | Expiry |