CN212572380U - Switching power supply circuit and electric energy meter with same - Google Patents
Switching power supply circuit and electric energy meter with same Download PDFInfo
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- CN212572380U CN212572380U CN202020714918.3U CN202020714918U CN212572380U CN 212572380 U CN212572380 U CN 212572380U CN 202020714918 U CN202020714918 U CN 202020714918U CN 212572380 U CN212572380 U CN 212572380U
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Abstract
A switching power supply circuit includes a transformer including a primary coil and a secondary coil; the output end of the main circuit is connected with a primary coil of the transformer, the main circuit comprises a control circuit, a switch chip with an MOS (metal oxide semiconductor) tube arranged in the control circuit is arranged in the control circuit, the source electrode of the MOS tube is connected with a current sampling circuit, and the other end of the current sampling circuit is grounded; a power output circuit connected to a secondary coil of the transformer; the method is characterized in that: the control circuit also comprises a filter circuit, the filter circuit comprises a fifth capacitor, and the fifth capacitor is connected with the current sampling circuit in parallel. An electric energy meter with the switching power supply circuit is also disclosed. The filter circuit connected in parallel with the current sampling circuit is arranged in the control circuit, so that the interference of a high-frequency electromagnetic field on a signal acquired by the current sampling circuit is avoided.
Description
Technical Field
The utility model relates to a power supply circuit, in particular to switching power supply circuit and have this switching power supply circuit's electric energy meter.
Background
The switching power supply is a power supply which utilizes modern power electronic technology to control the on-off time ratio of a switching tube and maintain stable output voltage, and generally consists of a Pulse Width Modulation (PWM) control IC and a MOSFET. With the development and innovation of power electronic technology, the technology of the switching power supply is continuously innovated. The switching power supply is widely applied to almost all electronic devices due to the characteristics of small size, light weight and high efficiency, and is an indispensable power supply mode for the rapid development of the electronic information industry at present. The primary current of a transformer needs to be sampled in a current feedback type switching power supply, one of the existing primary current sampling modes is to sample through an MOS tube source electrode series resistor in a switching chip with an internal MOS tube, but signals acquired by a current sampling resistor are small and are easily interfered by an external high-frequency electromagnetic field, so that the signals acquired by a current sampling circuit are deviated, and the switching power supply is abnormal in work.
In order to filter high-frequency interference signals in the switching power supply, a chinese patent with application number CN201810333152.1 (application publication number CN108336917A) discloses a switching power supply circuit, which comprises a protection circuit, an input filter circuit, a rectification filter circuit, a main power switch tube circuit, an isolation voltage-reducing circuit and an output rectification filter circuit, which are connected in sequence; the output end of the output rectifying filter circuit forms a voltage negative feedback loop through an isolation negative feedback circuit, a control circuit, a main power switch tube circuit and an isolation voltage reduction circuit which are connected in sequence. The output end of the output rectifying and filtering circuit in the circuit forms a voltage negative feedback loop through an isolation negative feedback circuit, a control circuit, a main power switch tube circuit and an isolation voltage reduction circuit which are sequentially connected, so that not only can high-frequency interference signals in an input power supply be filtered, but also the voltage of direct current can be stably output through the voltage negative feedback loop. However, the circuit has a complex structure, a complete loop is needed to filter out the high-frequency interference signals, and the high-frequency interference signals in the input power supply cannot be filtered out when any circuit is not connected. Further improvements are therefore desirable.
SUMMERY OF THE UTILITY MODEL
The utility model aims to solve the first technical problem to provide a simple structure, with low costs and can effective filtering high frequency interference signal's switching power supply circuit to prior art's current situation.
The utility model discloses the second technical problem that will solve is to prior art's current situation, provides an electric energy meter with above-mentioned switching power supply circuit.
The utility model provides a technical scheme that above-mentioned first technical problem adopted does: a switching power supply circuit comprises
A transformer including a primary coil and a secondary coil;
the output end of the main circuit is connected with a primary coil of the transformer, the main circuit comprises a control circuit, a switch chip with an MOS tube arranged inside is arranged in the control circuit, the source electrode of the MOS tube is connected with a current sampling circuit, and the other end of the current sampling circuit is grounded;
a power output circuit connected to a secondary coil of the transformer;
the method is characterized in that: the control circuit also comprises a filter circuit used for filtering interference signals of the high-frequency electromagnetic field, wherein the filter circuit comprises a fifth capacitor, and the fifth capacitor is connected with the current sampling circuit in parallel.
Preferably, the fifth capacitor is a decoupling capacitor.
Specifically, the capacitance value range of the fifth capacitor is as follows: 22pf to 300 pf.
In this scheme, the current sampling circuit comprises an eleventh resistor and a twelfth resistor which are connected in parallel.
Furthermore, the main circuit further comprises a protection circuit, a rectification filter circuit and an absorption circuit which are sequentially connected, wherein the input end of the protection circuit is connected with a mains supply, and the absorption circuit is connected with the drain electrode of the MOS tube arranged in the switch chip.
Preferably, the absorption circuit is an RCD absorption circuit.
The transformer comprises two groups of primary coils, wherein one group of primary coils is connected with the output end of the absorption circuit, and the other group of primary coils is connected with the control circuit.
The transformer comprises two groups of secondary coils, the power output circuits are in two paths, one group of secondary coils is connected with one path of power output circuit, and the other group of secondary coils is connected with the other path of power output circuit.
The model of the switch chip is ALTAIR 04-900.
The utility model provides a technical scheme that above-mentioned second technical problem adopted does: an electric energy meter, characterized by: including a switching power supply circuit as described above.
Compared with the prior art, the utility model has the advantages of: the filter circuit is arranged in the control circuit and connected with the current sampling circuit in parallel, and the high-frequency electromagnetic field interference signal received in the control circuit is led into a reference ground through the capacitor, so that the interference of the high-frequency electromagnetic field on the signal acquired by the current sampling circuit is avoided, the sampling precision of the current sampling circuit is improved, the work of the switching power supply is further ensured, and the circuit is simple in structure and low in cost.
Drawings
Fig. 1 is a circuit diagram of a switching power supply according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the following embodiments.
As shown in FIG. 1, a switching power supply circuit comprises
A transformer T1 including a primary coil and a secondary coil;
the output end of the main circuit is connected with a primary coil of the transformer T1, the main circuit comprises a control circuit 4, wherein a switch chip N1 with a built-in MOS (metal oxide semiconductor) tube is arranged in the control circuit 4, the source electrode of the MOS tube is connected with a current sampling circuit 41, and the other end of the current sampling circuit 41 is grounded;
a power output circuit 5 connected to the secondary winding of the transformer T1;
and the filter circuit 42 is arranged in the control circuit 4 and is used for filtering the high-frequency electromagnetic field interference signals, wherein the filter circuit 42 comprises a fifth capacitor C5, and the fifth capacitor C5 is connected in parallel with the current sampling circuit 42.
In this embodiment, the fifth capacitor C5 is a decoupling capacitor, and has a capacitance value range of: 22pf to 300 pf. The switch chip N1 is of type ALTAIR 04-900.
The current sampling circuit 41 provided in the switching power supply includes an eleventh resistor R11 and a twelfth resistor R12 connected in parallel.
The main circuit further comprises a protection circuit 1, a rectification filter circuit 2 and an absorption circuit 3 which are connected in sequence, wherein the input end of the protection circuit 1 is connected with a mains supply, and the absorption circuit 3 is connected with a drain electrode of a built-in MOS (metal oxide semiconductor) tube of the switch chip N1. In the present embodiment, the snubber circuit 3 is an RCD snubber circuit, but may be an RC snubber circuit.
In addition, in this embodiment, the transformer T1 is a high-frequency transformer, and the transformer T1 includes two sets of primary coils and two sets of secondary coils, wherein one set of primary coils is connected to the output end of the absorption circuit 3, and the other set of primary coils is connected to the control circuit 4; the switching power supply is a switching power supply with two paths of output, wherein one group of secondary coils is connected with one path of power supply output circuit, and the other group of secondary coils is connected with the other path of power supply output circuit.
An electric energy meter comprises the switching power supply circuit.
This switching power supply circuit is at the during operation, the current sampling circuit is easily disturbed by the high frequency electromagnetic field of transformer, through increase filter circuit in control circuit, and only need in this embodiment can be with leading-in the reference ground to the switch chip of interference signal through a decoupling capacitor, thereby consume the interference signal, consequently this switching power supply circuit simple structure, and is with low costs, thereby the accuracy of current sampling circuit sampling has been guaranteed to the high frequency electromagnetic field interference signal of filter circuit filtering, and then control switching power supply circuit maintains stable output voltage, can protect high frequency interference.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of improvements and decorations can be made without departing from the technical principle of the present invention, and these improvements and decorations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A switching power supply circuit comprises
A transformer including a primary coil and a secondary coil;
the output end of the main circuit is connected with a primary coil of the transformer, the main circuit comprises a control circuit, a switch chip with an MOS tube arranged inside is arranged in the control circuit, the source electrode of the MOS tube is connected with a current sampling circuit, and the other end of the current sampling circuit is grounded;
a power output circuit connected to a secondary coil of the transformer;
the method is characterized in that: the control circuit also comprises a filter circuit used for filtering interference signals of the high-frequency electromagnetic field, wherein the filter circuit comprises a fifth capacitor, and the fifth capacitor is connected with the current sampling circuit in parallel.
2. The switching power supply circuit according to claim 1, wherein: the fifth capacitor is a decoupling capacitor.
3. The switching power supply circuit according to claim 2, wherein: the capacitance value range of the fifth capacitor is as follows: 22pf to 300 pf.
4. The switching power supply circuit according to claim 1, wherein: the current sampling circuit comprises an eleventh resistor and a twelfth resistor which are connected in parallel.
5. The switching power supply circuit according to claim 1, wherein: the main circuit further comprises a protection circuit, a rectification filter circuit and an absorption circuit which are sequentially connected, wherein the input end of the protection circuit is connected with a mains supply, and the absorption circuit is connected with the drain electrode of the MOS tube built in the switch chip.
6. The switching power supply circuit according to claim 5, wherein: the absorption circuit is an RCD absorption circuit.
7. The switching power supply circuit according to claim 1, wherein: the transformer comprises two groups of primary coils, wherein one group of primary coils is connected with the output end of the absorption circuit, and the other group of primary coils is connected with the control circuit.
8. The switching power supply circuit according to claim 1, wherein: the transformer comprises two groups of secondary coils, the power output circuits are in two paths, one group of secondary coils is connected with one path of power output circuit, and the other group of secondary coils is connected with the other path of power output circuit.
9. The switching power supply circuit according to claim 1, wherein: the model of the switch chip is ALTAIR 04-900.
10. An electric energy meter, characterized by: comprising a switching power supply circuit according to any one of claims 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020714918.3U CN212572380U (en) | 2020-04-30 | 2020-04-30 | Switching power supply circuit and electric energy meter with same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020714918.3U CN212572380U (en) | 2020-04-30 | 2020-04-30 | Switching power supply circuit and electric energy meter with same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN212572380U true CN212572380U (en) | 2021-02-19 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202020714918.3U Active CN212572380U (en) | 2020-04-30 | 2020-04-30 | Switching power supply circuit and electric energy meter with same |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN212572380U (en) |
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2020
- 2020-04-30 CN CN202020714918.3U patent/CN212572380U/en active Active
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