CN103812313A - Active EMI (Electro-Magnetic Interference) filter for high-frequency switching power supply - Google Patents
Active EMI (Electro-Magnetic Interference) filter for high-frequency switching power supply Download PDFInfo
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- CN103812313A CN103812313A CN201210440654.7A CN201210440654A CN103812313A CN 103812313 A CN103812313 A CN 103812313A CN 201210440654 A CN201210440654 A CN 201210440654A CN 103812313 A CN103812313 A CN 103812313A
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- power supply
- operational amplifier
- switching power
- filter
- active emi
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Abstract
The invention belongs to the technical field of filters and particularly relates to an active EMI (Electro-Magnetic Interference) filter for a high-frequency switching power supply which is good in filtering effect and small in size. The active EMI filter for the high-frequency switching power supply comprises an operational amplifier. The structural key points of the active EMI filter are that a same-phase end of the operational amplifier is connected with a positive end of a first diode and a negative end of a second diode, a negative end of the first diode is connected with an anti-phase end of the operational amplifier, a positive end of the second diode is connected with an output end of the operational amplifier via a first capacitor, a first resistor, a second resistor and a second capacitor in sequence.
Description
Technical field
the invention belongs to wave filter technology field, relate in particular to a kind of high frequency switch power active EMI filter.
Background technology
switching Power Supply is to utilize modern power electronics technology, and the time ratio that control switch pipe turns on and off maintains a kind of power supply of regulated output voltage, and Switching Power Supply generally controls IC by pulse width modulation (PWM) and MOSFET forms.Along with development and the innovation of power electronic technology, make switch power technology also in constantly innovation.At present, Switching Power Supply, with small-sized, light weight and high efficiency feature nearly all electronic equipment that is widely used, is the indispensable a kind of power mode of current electronics and information industry develop rapidly.
switching Power Supply, due to plurality of advantages such as its high-quality, efficient and various transformation of electrical energy effects, has been widely used in industry and civil area at present.But due to the electromagnetic interference that uses device for power switching and Switching Power Supply itself to produce, cause the electromagnetic environment of Switching Power Supply inside more and more severe, electronic equipment around and the normal work of power supply itself have been caused to threat simultaneously.In addition, Switching Power Supply high frequency is the direction of its development, and high frequency makes Switching Power Supply miniaturization, but, Switching Power Supply but produces more serious electromagnetic interference in high frequency, and due to the problem such as volume, power consumption, existing passive electromagnetic interface filter can not meet the needs of filtering technique.
Summary of the invention
the present invention is exactly for the problems referred to above, and a kind of good wave filtering effect, high frequency switch power active EMI filter that volume is little are provided.
for achieving the above object, the present invention adopts following technical scheme, the present invention includes operational amplifier, the in-phase end of its structural feature operational amplifier is connected with the first diode cathode end, the second diode cathode end respectively, the end of oppisite phase of the first diode cathode end and operational amplifier, the second diode cathode end is connected with the output of operational amplifier by the first electric capacity, the first resistance, the second resistance, the second electric capacity successively.
as a kind of preferred version, the capacitance of the first electric capacity of the present invention is 560pF, and the first resistance value is 10 ohm.
as another kind of preferred version, the second resistance of the present invention is 2 ohm, and the second capacitor's capacity is 560pF.
beneficial effect of the present invention.
the present invention can not only suppress common mode disturbances effectively, has also met the requirement of Switching Power Supply physical characteristic.Experimental results show that on active EMI filter and stablize, filter effect is good.And because components and parts used are fewer, do not occupy very large space, and making compact overall structure, the volume of filter has had significantly and has reduced, and meets the requirement that Switching Power Supply further develops.More and more less at Switching Power Supply volume, under the increasing trend of power density, EMI/EMC problem becomes a key factor of Switching Power Supply stability.EMI Active Power Filter Technology goes out to send to suppress interference from the route of transmission of electromagnetic interference, the conducted interference can filtering many reasons producing, eliminating coupling and radiation between interference source and disturbed equipment, cut off the route of transmission of electromagnetic interference, is a kind of effective measures that spike ten is disturbed that suppress.
Accompanying drawing explanation
in order to make technical problem solved by the invention, technical scheme and beneficial effect clearer, below in conjunction with the drawings and the specific embodiments, the present invention is further elaborated.Should be appreciated that embodiment described herein, only in order to explain the present invention, is not intended to limit the present invention.
fig. 1 is circuit theory diagrams of the present invention.
Embodiment
as shown in the figure, the present invention includes operational amplifier, the in-phase end of operational amplifier is connected with the first diode cathode end, the second diode cathode end respectively, the end of oppisite phase of the first diode cathode end and operational amplifier, the second diode cathode end is connected with the output of operational amplifier by the first electric capacity, the first resistance, the second resistance, the second electric capacity successively.
the capacitance of described the first electric capacity is 560pF, and the first resistance value is 10 ohm.
described the second resistance is 2 ohm, and the second capacitor's capacity is 560pF.
due to " empty short " between amplifier end of oppisite phase and in-phase end, make capacitor C
2
and the series connection of coupling capacitance between transformer primary secondary, therefore can pass through capacitor C
2
sample its mode voltage, and be input to the end of oppisite phase of amplifier, then through amplifier feedback network and capacitor C
4
and resistance R
2
, i.e. an exportable reciprocal dynamic current compensation, thus common mode current is circulated in network internal, thus greatly reduce the common mode current of inflow place, reach the even cancellation common mode current object that decays.
be understandable that, above about specific descriptions of the present invention, only for being described, the present invention is not limited to the described technical scheme of the embodiment of the present invention, those of ordinary skill in the art is to be understood that, still can modify or be equal to replacement the present invention, to reach identical technique effect; Use needs as long as meet, all within protection scope of the present invention.
Claims (3)
1. high frequency switch power active EMI filter, comprise operational amplifier, the in-phase end that it is characterized in that operational amplifier is connected with the first diode cathode end, the second diode cathode end respectively, the end of oppisite phase of the first diode cathode end and operational amplifier, the second diode cathode end is connected with the output of operational amplifier by the first electric capacity, the first resistance, the second resistance, the second electric capacity successively.
2. high frequency switch power active EMI filter according to claim 1, the capacitance that it is characterized in that described the first electric capacity is 560pF, the first resistance value is 10 ohm.
3. high frequency switch power active EMI filter according to claim 1, is characterized in that described the second resistance is 2 ohm, and the second capacitor's capacity is 560pF.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210440654.7A CN103812313A (en) | 2012-11-07 | 2012-11-07 | Active EMI (Electro-Magnetic Interference) filter for high-frequency switching power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210440654.7A CN103812313A (en) | 2012-11-07 | 2012-11-07 | Active EMI (Electro-Magnetic Interference) filter for high-frequency switching power supply |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN103812313A true CN103812313A (en) | 2014-05-21 |
Family
ID=50708646
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201210440654.7A Pending CN103812313A (en) | 2012-11-07 | 2012-11-07 | Active EMI (Electro-Magnetic Interference) filter for high-frequency switching power supply |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN103812313A (en) |
-
2012
- 2012-11-07 CN CN201210440654.7A patent/CN103812313A/en active Pending
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C02 | Deemed withdrawal of patent application after publication (patent law 2001) | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20140521 |