CN213341996U - Active filter circuit and power supply system - Google Patents
Active filter circuit and power supply system Download PDFInfo
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- CN213341996U CN213341996U CN202021766475.9U CN202021766475U CN213341996U CN 213341996 U CN213341996 U CN 213341996U CN 202021766475 U CN202021766475 U CN 202021766475U CN 213341996 U CN213341996 U CN 213341996U
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Abstract
The utility model discloses an active filter circuit and electrical power generating system, including RC series connection filtering unit, first transistor and second transistor, electric capacity C and resistance R are connected simultaneously to the base of first transistor, electric capacity C's other end ground connection, the other end of resistance R connects the input; the collector of the first transistor is connected with the input end, the emitter of the first transistor is connected with the base of the second transistor, the collector of the second transistor is connected with the input end, and the emitter of the second transistor is connected with the output end. The utility model discloses an active filter circuit and electrical power generating system utilize the electric current amplification effect of transistor, use the filter capacitance of less capacity to reach better filter effect to this reduces volume and weight.
Description
Technical Field
The utility model relates to a power electronic technology field, concretely relates to active filter circuit still relates to an electrical power generating system who uses this active filter circuit.
Background
The 50Hz and 60Hz AC input switching power supply contains power frequency noise, and when the off-line switching power supply is adopted to supply power for information and communication equipment such as a cesium atomic clock, a modulator, a demodulator and the like, power frequency phase noise is generated. When the off-line switching power supply is adopted to supply power to the LED, stroboscopic is generated. To reduce power frequency noise, there are generally two methods: one method is to increase the filter capacitance at the dc output, which usually needs to be increased from hundreds of microfarads to thousands of microfarads, even tens of thousands of microfarads, resulting in an increase in the switching power supply volume by 20% -50% and weight. The other method is that the direct current output end is connected with the three-terminal voltage regulator in series to supply power to the load, and because the output end of the off-line switching power supply is low in voltage and large in current, the power supply conversion efficiency is low, and a radiator needs to be configured for the three-terminal voltage regulator.
Disclosure of Invention
The to-be-solved technical problem of the utility model is to provide an active filter circuit and electrical power generating system uses the filter capacitance of small capacity to reach better filter effect, especially power frequency noise filtering to this volume and the weight that reduce electrical power generating system.
In order to solve the technical problem, the utility model provides an active filter circuit, including RC series filter unit, first transistor and second transistor, electric capacity C and resistance R are connected simultaneously to the base of first transistor, the other end ground connection of electric capacity C, the other end connection input of resistance R; the collector of the first transistor is connected with the input end, the emitter of the first transistor is connected with the base of the second transistor, the collector of the second transistor is connected with the input end, and the emitter of the second transistor is connected with the output end.
Based on the same inventive concept, the utility model also provides an active filter circuit, including two sets of RC series filter unit, first transistor and second transistor, first electric capacity C1 and first resistance R1 are connected simultaneously to the base of first transistor, the other end of first electric capacity C1 is ground connection, the input is connected to the other end of first resistance R1; the collector of the first transistor is simultaneously connected with a second resistor R2 and a second capacitor C2, the other end of the second capacitor C2 is grounded, and the other end of the second resistor R2 is connected with the input end; the emitter of the first transistor is connected with the base of the second transistor, the collector of the second transistor is connected with the input end, and the emitter of the second transistor is connected with the output end.
In a preferred embodiment of the present invention, the base of the first transistor is provided with a base resistor.
In a preferred embodiment of the present invention, the first transistor and the second transistor form a homopolar darlington structure.
Based on the same inventive concept, the utility model discloses still provide a power supply system who uses the active filter circuit.
In a preferred embodiment of the present invention, the power supply further comprises a DC/DC converter, wherein an input terminal of the DC/DC converter is connected to an output terminal of the active filter circuit.
The present invention further comprises at least two sets of DC/DC converters, wherein the two sets of DC/DC converters are connected in parallel and the input end connected in parallel is connected to the active filter circuit.
In a preferred embodiment of the present invention, the apparatus further comprises a PFC circuit, wherein an output terminal of the PFC circuit is connected to an input terminal of the active filter circuit.
The present invention further comprises a rectifier circuit, wherein the input end of the rectifier circuit is connected to the ac input end, and the output end of the rectifier circuit is connected to the PFC circuit.
The utility model has the advantages that:
the utility model discloses an active filter circuit and electrical power generating system utilize the electric current amplification effect of transistor, use the filter capacitance of less capacity to reach better filter effect, especially power frequency noise filtering to this volume and the weight that reduces electrical power generating system.
Drawings
Fig. 1 is a schematic circuit diagram of an active filter circuit according to a first embodiment of the present invention;
fig. 2 is a schematic circuit diagram of an active filter circuit according to a second embodiment of the present invention;
fig. 3 is a block diagram of a power supply system according to a preferred embodiment of the present invention;
fig. 4 is a block diagram showing the structure of the DC/DC converter in the power supply system shown in fig. 3.
The reference numbers in the figures illustrate:
10-a rectifier circuit;
20-a PFC circuit;
30-an active filter circuit;
40-DC/DC converter.
Detailed Description
The present invention is further described with reference to the following drawings and specific embodiments so that those skilled in the art can better understand the present invention and can implement the present invention, but the embodiments are not to be construed as limiting the present invention.
Examples
The embodiment of the utility model discloses active filter circuit, it is shown with reference to fig. 1, including RC series filter unit, first transistor Q1 and second transistor Q2, among the technical scheme of this embodiment, first transistor Q1 and second transistor Q2 constitute homopolar darlington structure, wherein, electric capacity C and resistance R are connected simultaneously to first transistor Q1's base, electric capacity C's other end ground connection, input Vin is connected to resistance R's the other end; the collector of the first transistor Q1 is connected to the input terminal Vin, the emitter thereof is connected to the base of the second transistor Q2, the collector of the second transistor Q2 is connected to the input terminal Vin, and the emitter thereof is connected to the output terminal Vout.
Based on the same inventive concept, in another embodiment of the present disclosure, as shown in fig. 2, the active filter circuit includes two sets of RC series filter units, a first transistor Q1 and a second transistor Q2, the first transistor Q1 and the second transistor Q2 form a homopolar darlington structure, wherein a base of the first transistor Q1 is connected to a first capacitor C1 and a first resistor R1, the other end of the first capacitor C1 is grounded, and the other end of the first resistor R1 is connected to an input terminal Vin-SR(ii) a The collector of the first transistor Q1 is connected to a second resistor R2 and a second capacitor C2, the other end of the second capacitor C2 is grounded, and the other end of the second resistor R2 is connected to the input end Vin-SR(ii) a The emitter of the first transistor Q1 is connected with the base of the second transistor Q2, and the collector of the second transistor Q2 is connected with the input end Vin-SRThe emitter of which is connected with the output end VO-SR。
The utility model discloses an in two kinds of above embodiments, all utilize the electric current amplification effect of transistor, use the filter capacitance of less capacity to reach better filter effect to this volume and the weight that reduce filter circuit, the following theory of operation to the second kind of embodiment carries out detailed description:
the active filter circuit utilizes the current amplification effect of the transistor, and the power frequency large-capacity filter capacitor at the emitter output end is converted into the small capacity of the base electrode to carry out power frequency filtering, so that the small capacity is used to achieve a better filtering effect. Suppose that a filter capacitor C with large capacitance is originally needed at the output of the active filter circuitO-SRThe AC component of the output current of the active filter circuit is iO-SRThe corresponding ripple is:
the base of the first transistor Q1 is connected to the first capacitor C1, and its base ripple voltage is:
ib1is an AC component of the base current of the first transistor Q1, C1Is the capacitance value of the first capacitor; w is the angular frequency of the ripple (w ═ 2 π f);
due to iO-SR＝(1+β1)(1+β2)ib1β 1 is the amplification factor of the first transistor, and β 2 is the amplification factor of the second transistor. If the filtering effect of the large-capacitance filtering circuit is the same as that of the active filtering circuit, namely VO-SR＝vb1Then, then
And (3) calculating:
and (3) calculating:
that is, after the active filter circuit of the present invention is used, the base of the first transistor is connected to
The capacitor achieves the filtering effect and the capacitance is CO-SRThe filtering effect of the capacitors is consistent. Usually, beta 1 and beta 2 are 40-300, and the capacitance C is calculated according to the minimum value of 40O-SRThe filtering effect of the capacitor, use the utility model discloses an active filter circuit only needs to use
The capacitor can be used for greatly reducing the volume and the weight of the filter capacitor on the premise of achieving the same filtering effect, and further reducing the volume and the weight of the active filter circuit.
Further, the base electrode of the first transistor is provided with a base electrode resistor RbThrough the base resistance R in case of long wiringbAnd suppressing noise caused by parasitic oscillation of the lead.
Based on the same inventive concept, the embodiment of the utility model also discloses a power supply system using the active filter circuit, which has all the technical effects of the active filter circuit described above.
Further, referring to fig. 3, the Power supply system includes a rectifier circuit 10, a PFC circuit 20 and a DC/DC converter 40, wherein an input terminal of the rectifier circuit 10 is connected to an ac input terminal, and an output terminal of the rectifier circuit 10 is connected to the PFC circuit 20, it can be understood that, in order to ensure the EMC performance of the Power supply system, an input protection circuit and an EMI filter are sequentially connected in series between the rectifier circuit 10 and the ac input terminal, the ac input passes through the input protection circuit and the EMI filter in sequence and then is connected to the rectifier circuit 10, and an output terminal of the rectifier circuit 10 is connected to a PFC (Power Factor Correction) Power Factor Correction (PFC) circuitThe circuit 20 and the PFC circuit 20 may adopt a circuit structure for implementing power factor correction in a known example. Referring to fig. 3, intermediate bus voltage X1 converted by PFC circuit 20 has power frequency noise. The output end of the PFC circuit is connected with an active filter circuit 30, the intermediate bus voltage X1 is converted into X2 through the active filter circuit 30, the X2 does not contain power frequency noise any more, the output end of the active filter circuit 30 is connected with a DC/DC converter 40, and an output V formed after the DC/DC converter is convertedOAnd no power frequency noise is contained.
The active filter circuit 30 is arranged between the PFC circuit 20 and the DC/DC converter 40, and the voltage and the current after the PFC circuit 20 are high and small, so that the power loss of the active filter circuit 30 is small, and the conversion efficiency of the whole power supply system can be improved.
On the other hand, use the utility model discloses active filter circuit 30 of innovative design filters at DC/DC converter 40's input, when DC/DC converter 40 has multiunit (at least two sets of), multiunit DC/DC converter 40 parallel connection, and the input after parallelly connected connects active filter circuit 30, active filter circuit 30 carries out power frequency filtering on the input public route of DC/DC converter group, make the signal of telecommunication on getting into all DC/DC converter 40 links all not have power frequency noise, compare in the electrical power generating system mode that all disposes power frequency filter circuit corresponding to every way DC/DC converter 40, can further reduce electrical power generating system's volume and weight.
The above-mentioned embodiments are merely preferred embodiments for fully illustrating the present invention, and the scope of the present invention is not limited thereto. Equivalent substitutes or changes made by the technical personnel in the technical field on the basis of the utility model are all within the protection scope of the utility model. The protection scope of the present invention is subject to the claims.
Claims (9)
1. An active filter circuit, comprising: the filter circuit comprises an RC series filtering unit, a first transistor and a second transistor, wherein the base electrode of the first transistor is simultaneously connected with a capacitor C and a resistor R, the other end of the capacitor C is grounded, and the other end of the resistor R is connected with an input end; the collector of the first transistor is connected with the input end, the emitter of the first transistor is connected with the base of the second transistor, the collector of the second transistor is connected with the input end, and the emitter of the second transistor is connected with the output end.
2. An active filter circuit, comprising: the filter comprises two groups of RC series filtering units, a first transistor and a second transistor, wherein the base of the first transistor is simultaneously connected with a first capacitor C1 and a first resistor R1, the other end of the first capacitor C1 is grounded, and the other end of the first resistor R1 is connected with an input end; the collector of the first transistor is simultaneously connected with a second resistor R2 and a second capacitor C2, the other end of the second capacitor C2 is grounded, and the other end of the second resistor R2 is connected with the input end; the emitter of the first transistor is connected with the base of the second transistor, the collector of the second transistor is connected with the input end, and the emitter of the second transistor is connected with the output end.
3. The active filter circuit of claim 1 or 2, wherein: and the base electrode of the first transistor is provided with a base electrode resistor.
4. The active filter circuit of claim 1 or 2, wherein: the first transistor and the second transistor constitute a homopolar darlington structure.
5. A power supply system using the active filter circuit as claimed in any one of claims 1 to 4.
6. The power supply system of claim 5, wherein: the active filter circuit comprises a DC/DC converter, wherein the input end of the DC/DC converter is connected with the output end of the active filter circuit.
7. The power supply system of claim 6, wherein: the active filter circuit comprises at least two groups of DC/DC converters, wherein the two groups of DC/DC converters are connected in parallel, and the input ends of the two groups of DC/DC converters after being connected in parallel are connected with the active filter circuit.
8. The power supply system of claim 6, wherein: the output end of the PFC circuit is connected with the input end of the active filter circuit.
9. The power supply system of claim 8, wherein: the input end of the rectification circuit is connected with the alternating current input end, and the output end of the rectification circuit is connected with the PFC circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021766475.9U CN213341996U (en) | 2020-08-21 | 2020-08-21 | Active filter circuit and power supply system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021766475.9U CN213341996U (en) | 2020-08-21 | 2020-08-21 | Active filter circuit and power supply system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN213341996U true CN213341996U (en) | 2021-06-01 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202021766475.9U Active CN213341996U (en) | 2020-08-21 | 2020-08-21 | Active filter circuit and power supply system |
Country Status (1)
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|---|---|
| CN (1) | CN213341996U (en) |
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