CN215910574U - Detection circuit for power adapter - Google Patents
Detection circuit for power adapter Download PDFInfo
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- CN215910574U CN215910574U CN202122248449.8U CN202122248449U CN215910574U CN 215910574 U CN215910574 U CN 215910574U CN 202122248449 U CN202122248449 U CN 202122248449U CN 215910574 U CN215910574 U CN 215910574U
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Abstract
The utility model discloses a detection circuit for a power adapter, which comprises a low-voltage power supply, a first switch circuit, a second switch circuit, a current-limiting circuit and a sampling circuit, wherein the low-voltage power supply is connected with the first switch circuit; the positive end of the low-voltage power supply is connected with a first detection joint, and the first switching circuit and the current limiting circuit are sequentially connected in series to the positive end of the low-voltage power supply; the negative end of the low-voltage power supply is connected with a second detection joint, one end of the second switch circuit is connected with a node between the first switch circuit and the current-limiting circuit, and the other end of the second switch circuit is connected with the negative end of the low-voltage power supply and the second detection joint; the sampling circuit is connected with the current limiting circuit and is used for collecting the current of the current limiting circuit. The detection system and the detection method can effectively detect whether the power adapter is suitable for a direct current power supply system on the premise of ensuring that the power adapter is not damaged.
Description
Technical Field
The utility model relates to a detection circuit for a power adapter.
Background
In order to meet the requirements of the equipment on power supplies, the existing equipment except the induction machine adopts an alternating current power adapter or a self-contained switch power supply to convert 220V alternating current into a direct current power supply required by the equipment. At present, the direct current power supply technology is vigorous, and direct current power distribution is needed in some occasions. However, the power adapters of the existing devices are developed based on an ac 50Hz 220V working environment, and are not necessarily suitable for dc power supply, and a detection method is required to detect whether the existing power adapters can directly use dc power supply.
SUMMERY OF THE UTILITY MODEL
The utility model aims to provide a detection circuit for a power adapter, which is used for solving the problem that no detection technology for detecting whether the power adapter is suitable for a direct-current power distribution system exists at present.
In order to solve the above technical problem, the present invention provides a detection circuit for a power adapter, which includes a low voltage power supply, a first switch circuit, a second switch circuit, a current limiting circuit and a sampling circuit;
the positive end of the low-voltage power supply is connected with a first detection joint, and the first switching circuit and the current limiting circuit are sequentially connected in series to the positive end of the low-voltage power supply; the negative end of the low-voltage power supply is connected with a second detection joint, one end of the second switch circuit is connected with a node between the first switch circuit and the current-limiting circuit, and the other end of the second switch circuit is connected with the negative end of the low-voltage power supply and the second detection joint; the sampling circuit is connected with the current limiting circuit and is used for collecting the current of the current limiting circuit.
Furthermore, the first switch circuit is a first field effect transistor, a source electrode of the first field effect transistor is connected with a positive electrode end of the low-voltage power supply, a drain electrode of the first field effect transistor is respectively connected with the second switch and the current limiting circuit, and a grid electrode of the first field effect transistor is connected with the switch control signal.
Furthermore, the second switch circuit is a second field effect transistor, a source electrode of the second field effect transistor is connected with a positive electrode end of the low-voltage power supply, a drain electrode of the second field effect transistor is respectively connected with the first switch and the current limiting circuit, and a grid electrode of the second field effect transistor is connected with the switch control signal.
Further, the detection circuit further comprises a controller respectively connected with the first switch circuit and the second switch circuit, and the controller is used for sending switch control signals to the first switch circuit and the second switch circuit to control the first switch circuit and the second switch circuit to be switched on and off.
Furthermore, the sampling circuit is connected with the controller, and the controller is used for acquiring current signals acquired by the sampling circuit and automatically judging whether the power adapter is suitable for the direct-current power distribution system according to the current signals.
Further, the system also comprises a human-computer interaction unit connected with the controller.
Further, the system also includes a communication interface coupled to the controller.
Further, the controller is a single chip microcomputer.
Further, the low-voltage power supply is a 12V low-voltage power supply.
Further, the sampling circuit is an AD sampling circuit.
The utility model has the beneficial effects that: the method comprises the steps that low-voltage direct current is applied to a power adapter, and whether the power adapter is suitable for a direct current power supply system or not is judged according to various waveforms of output current; the method can effectively detect whether the power adapter is suitable for a direct current power supply system on the premise of ensuring that the power adapter is not damaged.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:
FIG. 1 is a detection circuit diagram of one embodiment of the present invention;
FIG. 2 is a block diagram of a detection circuit according to another embodiment of the present invention;
FIG. 3 is a typical schematic diagram of an AC side voltage transformation and DC side linear power supply;
FIG. 4 is a schematic diagram of a switching power supply type power adapter;
FIG. 5 is a power adapter with an isolation transformer;
FIG. 6 is a schematic diagram of a power adapter employing resistance-capacitance voltage reduction;
FIG. 7 is a schematic diagram of the detection of a power adapter with a transformer on the input side;
FIG. 8 is an equivalent circuit diagram of K in FIG. 7 at position 1;
FIG. 9 is an equivalent circuit diagram of K in FIG. 7 at position 2;
FIG. 10 is a graph of the current waveform at R0 for position K in FIG. 7;
FIG. 11 is a graph of the current waveform at position R0 for K in FIG. 7 at position 2;
FIG. 12 is a schematic diagram of a detection of a power adapter with a RC voltage step-down input side;
FIG. 13 is the equivalent circuit of FIG. 12 with K at position 1;
FIG. 14 is a graph of the current waveform at R0 for position 1 for K in FIG. 12;
FIG. 15 is a schematic diagram of the detection of a power adapter employing a switching power supply;
FIG. 16 is the equivalent circuit of FIG. 15 with K in position 1;
fig. 17 is a graph of the current waveform at R0 for position 1 for K in fig. 15.
Detailed Description
The detection circuit for the power adapter shown in fig. 1 comprises a low-voltage power supply, a first switch circuit, a second switch circuit, a current limiting circuit and a sampling circuit; the positive end of the low-voltage power supply is connected with a first detection connector, and the first switching circuit and the current limiting circuit are sequentially connected in series to the positive end of the low-voltage power supply; the negative end of the low-voltage power supply is connected with a second detection joint, one end of the second switch circuit is connected with a node between the first switch circuit and the current-limiting circuit, and the other end of the second switch circuit is connected with the negative end of the low-voltage power supply and the second detection joint; the sampling circuit is connected with the current limiting circuit and is used for collecting the current of the current limiting circuit.
In the detection process, the first detection joint and the second detection joint are respectively connected with the positive input end and the negative input end of the power adapter, then the sampling circuit detects the current value flowing through the current limiting circuit (resistor R0) when the first switch circuit and the second switch circuit are respectively switched on and off, and then whether the power adapter is suitable for a direct current power distribution system is judged according to the current value; the detection system and the detection method are nondestructive detection, and can effectively detect whether the power adapter is suitable for a direct current power supply system on the premise of ensuring that the power adapter is not damaged.
According to an embodiment of the present application, the first switch circuit is a first field effect transistor, a source of the first field effect transistor is connected to a positive terminal of the low voltage power supply, a drain of the first field effect transistor is connected to the second switch and the current limiting circuit, respectively, and a gate of the first field effect transistor is connected to the switch control signal. Wherein, the first field effect transistor is an NMOS (N-type metal oxide semiconductor) transistor.
According to an embodiment of the present application, the second switch circuit is a second field effect transistor, a source of the second field effect transistor is connected to a positive terminal of the low voltage power supply, a drain of the second field effect transistor is connected to the first switch and the current limiting circuit, respectively, and a gate of the second field effect transistor is connected to the switch control signal. Wherein, the second field effect transistor is an NMOS (N-type metal oxide semiconductor) transistor.
According to an embodiment of the present application, as shown in fig. 2, the detection circuit further includes a controller connected to the first switch circuit and the second switch circuit, respectively, and the controller is configured to send a switch control signal to the first switch circuit and the second switch circuit to control the first switch circuit and the second switch circuit to be turned on and off. The controller can adopt a 32-chip microcomputer, the sampling period of the controller is not higher than 1us, sampling data of each time can be recorded, and whether each power adapter is suitable for direct-current power distribution or not is recorded.
According to an embodiment of the application, the sampling circuit is connected with the controller, and the controller is used for acquiring a current signal acquired by the sampling circuit and automatically judging whether the power adapter is suitable for a direct current power distribution system or not according to the current signal.
According to one embodiment of the application, the system further comprises a human-computer interaction unit connected with the controller. The interaction unit comprises a touch screen, the touch screen can display the waveform of the sampled current every time, and the user can conveniently set the parameters of the controller.
According to one embodiment of the application, the system further comprises a communication interface connected with the controller, and the controller can transmit the detection result to other equipment through the communication interface.
According to one embodiment of the application, the controller is a single chip microcomputer; specifically, the controller can adopt a 32-chip microcomputer, the sampling period of the controller is not higher than 1us, sampling data of each time can be recorded, and whether each power adapter is suitable for direct-current power distribution or not is recorded.
According to one embodiment of the application, the low-voltage power supply is a 12V low-voltage power supply, and the power adapter cannot be damaged by applying low-voltage direct current to the power adapter, so that nondestructive testing is guaranteed.
According to one embodiment of the application, the sampling circuit is an AD sampling circuit; the sampling circuit transmits the current value flowing through the current limiting circuit (resistor R0) to the controller through an AD sampling interface of the controller (singlechip), and the controller compares the received current value with a reference value to judge whether the power adapter is suitable for a direct current power distribution system or not.
The detection method for detecting whether the power adapter is suitable for the direct-current power distribution system by the detection circuit comprises the following steps:
s1: connecting the detection circuit to the power adapter to be detected;
s2: the first point switch is turned on, the second switch is turned off, and the dynamic current value i flowing through the current limiting circuit is collected1；
S3: the second point switch is turned on, the first switch is turned off, and the dynamic current value i flowing through the current limiting circuit is collected2；
S4: according to the dynamic current value i1And a dynamic current value i2And judging whether the power adapter to be detected is suitable for the direct-current power distribution system.
The following describes the detection principle in detail by taking a conventional device power adapter as an example:
1. the existing device power adapter is analyzed as follows
(1) Alternating current side voltage transformation and direct current side linear power supply.
A step-down transformer is arranged on the AC side, and the output power and voltage of the transformer are matched with the final DC output voltage. A typical schematic diagram of such a power adapter is shown in fig. 3. This type of power supply cannot be used in a dc power supply system.
(2) Typical switching power supplies. A schematic diagram of such a power adapter is shown in fig. 4.
(3) In some devices, an isolation transformer is added at the input side of a power adapter for electrical safety and reducing harmonic influence, and the power adapter cannot be supplied with direct current. The schematic diagram is shown in fig. 5.
(4) A resistance-capacitance voltage reduction power adapter is adopted. Part low-cost power adopts the resistance-capacitance step-down mode, and this type of power adapter is too big to the direct current voltage division, uses direct current power supply can not reach the operation requirement, and this type of power can not use direct current power supply. A schematic diagram of a power adapter using resistance-capacitance voltage reduction is shown in fig. 6.
2. The detection principle is as follows:
(1) for the power adapter shown in fig. 3 and 5, the ac side is equivalent to a resistor and an inductor, and the detection schematic diagram is shown in fig. 5. U shapesThe power adapter is a low-voltage direct-current voltage power supply, i is current, R0 is a detection sampling resistor, R is an equivalent resistor on the alternating current side of the power adapter, L is an equivalent inductor on the alternating current side, and K is a switch and can be placed at a position 1 and a position 2.
When the K switch is in position 1, the equivalent circuit is shown in fig. 8.
A first order differential equation can be obtained:
by i (0) ═ 0, i (∞) ═ Us/(R + R)0) Solving equation (1) can yield:
the waveform of the current flowing through R0 at this time is shown in fig. 10.
When K is in position 2, the equivalent circuit is shown in fig. 9.
A first order differential equation can be obtained:
from i (0) to Us/(R + R)0) I (∞) is 0, solving equation (3) yields:
the waveform of the current flowing through R0 is shown in fig. 11.
Since the value of R is generally small, the steady state value of the current is large when the switch K is in position 1. According to the analysis, if the current waveform on the sampling resistor is as shown in fig. 10 and fig. 11 when the detection switch is at the positions 1 and 2, the power adapter cannot directly use direct current power supply.
(2) Power adapter for adopting resistance-capacitance voltage reduction
For the power adapter of fig. 6, the ac side is equivalent to a resistor and a capacitor, and the detection schematic is shown in fig. 12. U shapesThe low-voltage direct-current voltage power supply is a low-voltage direct-current voltage power supply, i is current, R0 is a detection sampling resistor, R1 and C1 are a resistance-capacitance voltage reduction resistor and a capacitor of the power adapter, C2 and R2 are an equivalent capacitor and a resistor on the alternating-current side of the power adapter, D is an equivalent rectifier diode, K is a switch and can be placed at the position 1 and the position 2.
When the switch K is in position 1, the equivalent circuit is shown in fig. 13, and the system of equations can be obtained:
by using the laplace transform method, we can get:
wherein
The waveform of the current i (t) is shown in fig. 14.
When the switch K is in position 2, the capacitor cannot discharge because of the reverse cut-off function of the diode, i equals 0.
According to the analysis, if the current waveform on the sampling resistor is as shown in fig. 11 and the current is zero when the detection switch is at the positions 1 and 2, the power adapter cannot directly use the direct current power supply.
(3) For power adapter adopting switching power supply
For the power adapter of fig. 2, the ac side is equivalent to a resistor and a capacitor, and the detection schematic is shown in fig. 13. U shapesThe low-voltage direct-current voltage power supply is a low-voltage direct-current voltage power supply, i is current, R0 is a detection sampling resistor, D is an equivalent rectifier diode, R1 and C1 are equivalent capacitors and resistors on the alternating-current side of the power adapter, and K is a switch and can be placed at position 1 and position 2.
When the switch K is in position 1, the detection equivalent circuit is shown in fig. 14, and a first order differential equation can be obtained:
by uc1(0) When 0, we get:
the waveform of the current i (t) flowing through R0 at this time is shown in fig. 17.
When the switch K is in position 2, the capacitor cannot discharge because of the reverse cut-off function of the diode, i equals 0.
According to the analysis, if the detection switch is in the positions 1 and 2, the current waveform on the sampling resistor is as shown in fig. 15, and the current is 0, the power adapter can directly use direct current power supply.
Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered in the claims of the present invention.
Claims (10)
1. A detection circuit for a power adapter is characterized by comprising a low-voltage power supply, a first switch circuit, a second switch circuit, a current limiting circuit and a sampling circuit;
the positive end of the low-voltage power supply is connected with a first detection joint, and the first switching circuit and the current limiting circuit are sequentially connected in series to the positive end of the low-voltage power supply; the negative end of the low-voltage power supply is connected with a second detection joint, one end of the second switch circuit is connected with a node between the first switch circuit and the current-limiting circuit, and the other end of the second switch circuit is connected with the negative end of the low-voltage power supply and the second detection joint; the sampling circuit is connected with the current limiting circuit and is used for collecting the current of the current limiting circuit.
2. The detection circuit for the power adapter as claimed in claim 1, wherein the first switch circuit is a first field effect transistor, a source of the first field effect transistor is connected with a positive terminal of the low voltage power supply, a drain of the first field effect transistor is respectively connected with the second switch and the current limiting circuit, and a gate of the first field effect transistor is connected with the switch control signal.
3. The detection circuit for the power adapter as claimed in claim 1, wherein the second switch circuit is a second fet, a source of the second fet is connected to a positive terminal of the low voltage power supply, a drain of the second fet is connected to the first switch and the current limiting circuit, respectively, and a gate of the second fet is connected to the switch control signal.
4. The detection circuit for power adapter as claimed in any one of claims 1-3, further comprising a controller connected to the first and second switch circuits, respectively, the controller being configured to send switch control signals to the first and second switch circuits to control the first and second switch circuits to turn on and off.
5. The detection circuit for the power adapter as claimed in claim 4, wherein the sampling circuit is connected to the controller, and the controller is configured to obtain the current signal collected by the sampling circuit and automatically determine whether the power adapter is suitable for the dc power distribution system according to the current signal.
6. The detection circuit for a power adapter according to claim 5, wherein the system further comprises a human-machine interaction unit connected to the controller.
7. The detection circuit for a power adapter as recited in claim 5, further comprising a communication interface coupled to said controller.
8. The detection circuit for the power adapter as claimed in claim 4, wherein the controller is a single chip microcomputer.
9. The detection circuit for a power adapter according to claim 1, wherein said low voltage power supply is a 12V low voltage power supply.
10. The detection circuit for a power adapter according to claim 1, wherein the sampling circuit is an AD sampling circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122248449.8U CN215910574U (en) | 2021-09-16 | 2021-09-16 | Detection circuit for power adapter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122248449.8U CN215910574U (en) | 2021-09-16 | 2021-09-16 | Detection circuit for power adapter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN215910574U true CN215910574U (en) | 2022-02-25 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202122248449.8U Active CN215910574U (en) | 2021-09-16 | 2021-09-16 | Detection circuit for power adapter |
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| CN (1) | CN215910574U (en) |
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2021
- 2021-09-16 CN CN202122248449.8U patent/CN215910574U/en active Active
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