CN213585563U - Filter circuit and switching power supply - Google Patents
Filter circuit and switching power supply Download PDFInfo
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- CN213585563U CN213585563U CN202022502815.3U CN202022502815U CN213585563U CN 213585563 U CN213585563 U CN 213585563U CN 202022502815 U CN202022502815 U CN 202022502815U CN 213585563 U CN213585563 U CN 213585563U
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Abstract
The utility model discloses a filter circuit and switching power supply, wherein filter circuit includes: the first power input end and the second power input end are respectively used for receiving a first power supply and a second power supply, the current variation amplitude of the first power supply is the same as that of the second power supply, and the phases of the first power supply and the second power supply are opposite. The utility model discloses a compensating circuit loading is the same rather than electric current ripple amplitude of change on inductance filter circuit, and opposite phase's compensating current just so can make the electric current of inductance filter circuit output or the undulant of voltage offset each other, and the ripples is eliminated or is reduced switching power supply's line, simple structure moreover, great the cost that has reduceed. The utility model discloses but wide application in power technical field.
Description
Technical Field
The utility model belongs to the technical field of the power technology and specifically relates to a filter circuit and switching power supply are related to.
Background
In some high-performance power supply products of precision equipment, generally, low-power products often use a high-performance linear dc power supply, while medium-power products need to use a switching power supply to supply power in consideration of efficiency, however, ripples of the switching power supply are one of unavoidable problems to be solved.
The ripple of the switching power supply mainly includes low-frequency fluctuation (ac noise output by the rectifier), high-frequency ripple, common-mode noise, additional noise of the control loop, and the like of the input power supply, and the ripple of the switching power supply affects the stability of the product and the normal operation of the product function. There are a lot of research and development schemes aiming at reducing high-frequency ripples, but some have high cost, limited application range and some are complex and difficult to realize. There is therefore a need for a relatively cost-effective and efficient method for reducing and eliminating the ripple in switching power supplies.
SUMMERY OF THE UTILITY MODEL
The present invention is directed to solving, at least to some extent, one of the problems in the related art. Therefore, an object of the present invention is to provide a filter circuit.
Therefore, the second objective of the present invention is to provide a switching power supply.
The utility model adopts the technical proposal that:
in a first aspect, the present invention provides a filter circuit, including: the power supply comprises a first power supply input end, a second power supply input end, an inductance filter circuit, a compensation circuit and a power supply output end, wherein the first power supply input end and the second power supply input end are respectively used for receiving a first power supply and a second power supply, and the current change amplitudes of the first power supply and the second power supply are the same and the phases of the first power supply and the second power supply are opposite;
the first power supply input end is connected with the power supply output end through the inductive filter circuit, and the first power supply output by the first power supply input end is filtered and transmitted to the power supply output end through the inductive filter circuit;
the second power input end is connected with the compensation circuit, the compensation circuit is connected with the inductance filter circuit, and the second power output by the second power input end is loaded onto the inductance filter circuit through the compensation circuit to eliminate current ripples on the inductance filter circuit.
Further, the inductance filter circuit comprises a first inductance, a first diode and a first electrolytic capacitor, the first power input end comprises a positive end and a negative end, and the power output end comprises a positive end and a negative end;
the positive end of the first power supply input end is connected with the negative electrode of the first diode, and the negative end of the first power supply input end is connected with the positive electrode of the first diode;
the positive end of the power supply output end is connected with the positive electrode of the first electrolytic capacitor, and the negative end of the power supply output end is connected with the negative electrode of the first electrolytic capacitor;
one end of the first inductor is connected with the cathode of the first diode, and the other end of the first inductor is connected with the anode of the first electrolytic capacitor.
Further, the compensation circuit comprises a second inductor, the second power input comprises a positive terminal and a negative terminal, the positive terminal of the second power input is connected to the positive terminal of the first electrolytic capacitor through the second inductor, and the negative terminal of the second power input is connected to the negative terminal of the first electrolytic capacitor.
Further, the inductance values of the first inductor and the second inductor are equal.
On the other hand, the utility model discloses still improved a switching power supply, a serial communication port, include: the transformer comprises a first secondary coil and a second secondary coil, the current variation amplitude of the first secondary coil and the current variation amplitude of the second secondary coil are the same and equal in magnitude,
the output end of the first rectifier bridge is connected with the input end of the transformer, the output end of the PWM driving module is connected with the input end of the transformer, a first secondary coil of the transformer is connected with the first power supply input end, and a second secondary coil of the transformer is connected with the second power supply input end.
Further, the secondary winding of the transformer is connected with the second power input end through the second rectifier bridge.
The utility model has the advantages that:
the utility model discloses a compensating circuit loading is the same rather than electric current ripple amplitude of change on inductance filter circuit, and opposite phase's compensating current just so can make the electric current of inductance filter circuit output or the undulant of voltage offset each other, and the ripples is eliminated or is reduced switching power supply's line, simple structure moreover, great the cost that has reduceed.
Drawings
Fig. 1 is a schematic circuit diagram of a filter circuit according to an embodiment of the present invention;
fig. 2 is a schematic waveform diagram of a filter circuit according to an embodiment of the present invention.
Detailed Description
The solutions for solving the low ripple in the prior art mainly include three kinds, the first kind: two inductively coupled CUK converters: the ripple of the output of the CUK converter can be reduced by two mutually coupled inductors. However, since the CUK converter is an energy converter, the current and voltage capacities of the MOS transistor and the diode of the circuit are increased, and the device cost is increased; and the second method comprises the following steps: some adopt multistage filter circuits, so the cost of the circuit is increased, and the circuit is only suitable for outputting high-voltage low-power products; and the third is that: the hybrid filter formed by combining the active filter and the passive filter can also realize the reduction of output ripples, but the circuit for realizing the hybrid filter is complex, the circuit structure needs to be detected and controlled, and has phase shift errors, and the parameters of the filter inductance are larger.
Therefore, the utility model provides a simple structure can reduce filter circuit of cost, include: the power supply comprises a first power supply input end, a second power supply input end, an inductance filter circuit, a compensation circuit and a power supply output end, wherein the first power supply input end and the second power supply input end are respectively used for receiving a first power supply and a second power supply, and the current change amplitudes of the first power supply and the second power supply are the same and the phases of the first power supply and the second power supply are opposite; the first power supply input end is connected with the power supply output end through the inductive filter circuit, and the first power supply output by the first power supply input end is filtered and transmitted to the power supply output end through the inductive filter circuit; the second power input end is connected with the compensation circuit, the compensation circuit is connected with the inductance filter circuit, and the second power output by the second power input end is loaded onto the inductance filter circuit through the compensation circuit to eliminate current ripples on the inductance filter circuit.
Example 1
As shown in fig. 1, in the present embodiment, it discloses a circuit schematic of a filter circuit.
Specifically, the inductance filter circuit comprises a first inductor L1, a first diode VD and a first electrolytic capacitor Cout, the first power input end Us1 comprises a positive terminal and a negative terminal, and the power output end Uo comprises a positive terminal and a negative terminal; the positive end of the first power input end Us1 is connected with the negative electrode of the first diode VD, and the negative end of the first power input end Us1 is connected with the positive electrode of the first diode VD; the positive end of the power supply output end UO is connected with the positive electrode of the first electrolytic capacitor Cout, and the negative end of the power supply output end UO is connected with the negative electrode of the first electrolytic capacitor Cout; one end of the first inductor L1 is connected to the cathode of the first diode VD, and the other end is connected to the anode of the first electrolytic capacitor Cout.
The compensation circuit comprises a second inductor L2, the second power input end Us2 comprises a positive terminal and a negative terminal, the positive terminal of the second power input end Us2 is connected with the positive electrode of the first electrolytic capacitor Cout through the second inductor L2, and the negative terminal of the second power input end Us2 is connected with the negative electrode of the first electrolytic capacitor Cout. The inductance values of the first inductor L1 and the second inductor L2 are equal.
As shown in fig. 2, it shows a current waveform diagram of the filter circuit in the above embodiment, where iL1 and iL2 respectively represent current waveforms on the first inductor L1 and the second inductor L2, Us1 and Us2 respectively represent voltages at the first power input terminal and the second power input terminal, and Io represents a current at the power output terminal. As can be seen, it is divided into the following two states:
iL1 rises and iL2 falls, with opposite slopes and equal amplitudes.
Since inductance L1= L2.
The volt-second equilibrium equation for inductance L1 is:
(1)
the volt-second equilibrium equation for inductance L2 is:
(2)
therefore:
s (3)
iL1 goes down and iL2 goes up, with opposite slopes and equal amplitudes.
Since inductance L1= L2.
The volt-second equilibrium equation for inductance L1 is:
(5)
the volt-second equilibrium equation for inductance L2 is:
(6)
therefore: -
(7)
From (9): after the filter inductor is connected with the compensation inductor in parallel, no high-frequency ripple exists. Output voltage: uo = D Us1 (11)
The output voltage value can be adjusted by changing the duty ratio D. The following results are obtained through relevant demonstration: as long as iL1 and iL2 are continuous, the duty ratio D is between 0 and 1, and the output voltage has no high-frequency ripple. The filter inductor and the compensation inductor respectively bear half of the output current, and a small and proper filter capacitor can be connected in parallel at the output end due to the difference between the theory and the practice of components or other uncertain factors.
On the other hand, the utility model discloses still improved a switching power supply, a serial communication port, include: the transformer comprises a first secondary coil and a second secondary coil, the current variation amplitude of the first secondary coil and the current variation amplitude of the second secondary coil are the same and equal, the output end of the first rectifier bridge is connected with the input end of the transformer, the output end of the PWM driving module is connected with the input end of the transformer, the first secondary coil of the transformer is connected with the first power supply input end, and the second secondary coil of the transformer is connected with the second power supply input end.
Preferably, the secondary winding of the transformer is connected to the second power input terminal through a second rectifier bridge.
While the preferred embodiments of the present invention have been described, the present invention is not limited to the above embodiments, and those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and such equivalent modifications or substitutions are intended to be included within the scope of the present invention as defined by the appended claims.
Claims (6)
1. A filter circuit, comprising: the power supply comprises a first power supply input end, a second power supply input end, an inductance filter circuit, a compensation circuit and a power supply output end, wherein the first power supply input end and the second power supply input end are respectively used for receiving a first power supply and a second power supply, and the current change amplitudes of the first power supply and the second power supply are the same and the phases of the first power supply and the second power supply are opposite;
the first power supply input end is connected with the power supply output end through the inductive filter circuit, and the first power supply output by the first power supply input end is filtered and transmitted to the power supply output end through the inductive filter circuit;
the second power input end is connected with the compensation circuit, the compensation circuit is connected with the inductance filter circuit, and the second power output by the second power input end is loaded onto the inductance filter circuit through the compensation circuit to eliminate current ripples on the inductance filter circuit.
2. The filter circuit of claim 1, wherein the inductive filter circuit comprises a first inductor, a first diode, and a first electrolytic capacitor, wherein the first power input comprises a positive terminal and a negative terminal, and wherein the power output comprises a positive terminal and a negative terminal;
the positive end of the first power supply input end is connected with the negative electrode of the first diode, and the negative end of the first power supply input end is connected with the positive electrode of the first diode;
the positive end of the power supply output end is connected with the positive electrode of the first electrolytic capacitor, and the negative end of the power supply output end is connected with the negative electrode of the first electrolytic capacitor;
one end of the first inductor is connected with the cathode of the first diode, and the other end of the first inductor is connected with the anode of the first electrolytic capacitor.
3. The filter circuit of claim 2, wherein the compensation circuit comprises a second inductor, wherein the second power input comprises a positive terminal and a negative terminal, wherein the positive terminal of the second power input is coupled to the positive terminal of the first electrolytic capacitor via the second inductor, and wherein the negative terminal of the second power input is coupled to the negative terminal of the first electrolytic capacitor.
4. The filter circuit of claim 3, wherein the inductance values of the first inductor and the second inductor are equal.
5. A switching power supply, comprising: a first rectifier bridge, a transformer, a PWM driving module and the filter circuit of any one of claims 1 to 4, wherein the transformer comprises a first secondary coil and a second secondary coil, the current variation amplitude on the first secondary coil and the second secondary coil is the same and equal,
the output end of the first rectifier bridge is connected with the input end of the transformer, the output end of the PWM driving module is connected with the input end of the transformer, a first secondary coil of the transformer is connected with the first power supply input end, and a second secondary coil of the transformer is connected with the second power supply input end.
6. The switching power supply according to claim 5, further comprising a second rectifier bridge, wherein the second secondary winding of the transformer is connected to the second power supply input terminal through the second rectifier bridge.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022502815.3U CN213585563U (en) | 2020-11-03 | 2020-11-03 | Filter circuit and switching power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022502815.3U CN213585563U (en) | 2020-11-03 | 2020-11-03 | Filter circuit and switching power supply |
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| Publication Number | Publication Date |
|---|---|
| CN213585563U true CN213585563U (en) | 2021-06-29 |
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| CN202022502815.3U Active CN213585563U (en) | 2020-11-03 | 2020-11-03 | Filter circuit and switching power supply |
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| CN (1) | CN213585563U (en) |
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