CN112994169B - Load current detection system and detection method - Google Patents
Load current detection system and detection method Download PDFInfo
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- CN112994169B CN112994169B CN202110305088.8A CN202110305088A CN112994169B CN 112994169 B CN112994169 B CN 112994169B CN 202110305088 A CN202110305088 A CN 202110305088A CN 112994169 B CN112994169 B CN 112994169B
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- 238000001514 detection method Methods 0.000 title claims abstract description 97
- 230000005669 field effect Effects 0.000 claims description 7
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0047—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with monitoring or indicating devices or circuits
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Abstract
The invention relates to a load current detection system and a detection method, wherein the load current detection system comprises: the first current detection circuit comprises a first switch, one end of the first switch is connected with the power supply end of the charging circuit, and the other end of the first switch is connected with the load; the second current detection circuit comprises a switch II, and the switch II is connected with the switch I in parallel; the first current and the second current are used for representing the charging condition of the load; when the first current is smaller than the preset maximum current, the first switch is turned off, and the second switch is turned on; and when the second current is smaller than the preset minimum current, the switch II and the switch I are both turned off, and the load stops charging. The device can detect micro current on the electronic switch, can be compatible with large-current load charging, and has high detection precision and good mass production consistency.
Description
Technical Field
The invention relates to the technical field of current detection, in particular to a load current detection system and a load current detection method.
Background
For a battery charging system, a power converter charges a load, and when the load is full, a switch is required to control to disconnect the connection between the power converter and the load, so that the loss of the power conversion system can be reduced; on the other hand, for the application of parallel connection of multiple loads, when the electric quantity of one load is detected to be full or removed, the connection between the one load and the power converter can be disconnected, so that the charging capacity of the converter can be released to charge other loads.
A currently common way to detect that a load is removed or full is to detect the magnitude of the current flowing through the load. To increase efficiency and reduce cost, the sense current is typically equivalent to sensing the voltage drop across the switch. The voltage difference between two ends of the switch is generally detected directly by using a comparator with a threshold value, but in the application occasions of small on-resistance of the switch and small threshold current to be detected, high precision and batch consistency cannot be realized.
Therefore, a new load current detection system and detection method are needed.
Disclosure of Invention
The invention aims to solve the technical problem of providing a load current detection system and a detection method, which can detect micro current on an electronic switch, can be compatible with large-current load charging, and have high detection precision and good mass production consistency.
In order to solve the technical problem, the present invention provides a load current detection system for controlling on-off of charging of a charging circuit, which is characterized in that the load current detection system includes: the first current detection circuit comprises a first switch, one end of the first switch is connected with the power supply end of the charging circuit, and the other end of the first switch is connected with the load; the first current detection circuit is used for detecting a first current on the first switch; the second current detection circuit comprises a switch II, and the switch II is connected with the switch I in parallel; the second current detection circuit is used for detecting a second current on the second switch; the first current detection circuit and the second current detection circuit are arranged in parallel; the first current and the second current are used for representing the charging condition of the load; when the first current is smaller than the preset maximum current, the first switch is turned off, and the second switch is turned on; and when the second current is smaller than the preset minimum current, the switch II and the switch I are both turned off, and the load stops charging.
Preferably, the resistance of the second switch is larger than the resistance of the first switch.
Preferably, the first switch is a first field effect transistor; and the second switch is a second field effect transistor.
Preferably, the charging circuit includes a power converter and a load; the input end of the power converter is connected with an external power supply, and the output end of the power converter is connected with the input end of the load so as to charge the load.
Preferably, the first current detection circuit includes a first comparator; the positive pin of the first comparator is connected with the drain electrode of the first switch, the negative pin of the first comparator is connected with the source electrode of the first switch, and the output end of the first comparator is connected with the gate electrode of the first switch.
Preferably, the second current detection circuit includes a second comparator; the positive pin of the second comparator is connected with the drain electrode of the second switch, the negative electrode of the second comparator is connected with the source electrode of the second switch, and the output end of the second comparator is connected with the gate electrode of the second switch.
Preferably, an input capacitor is connected in parallel between the external power supply and the power converter, and an output capacitor is connected in parallel between the power converter and the load.
A load current detection method, preferably performed by said load current detection system.
Preferably, the load current detection method includes the steps of:
s1, a first current detection circuit works, and when the first current detected by the first current detection circuit is smaller than a preset maximum current I, a first switch is turned off, and a second switch is turned on;
s2, the second current detection circuit works, when the first current detected by the second current detection circuit is smaller than a preset minimum current i, the switch II and the switch I are both turned off, the load is full, and the charging is stopped.
Preferably, the preset maximum current I is n times the preset minimum current I; the resistance values of the switch II and the switch I meet the following relation: r2=n×r1, where R2 is the resistance of switch two, R1 is the resistance of switch one, and n=i/I.
Compared with the prior art, the technical scheme of the invention has the following advantages:
according to the invention, the first current detection circuit and the second current detection circuit are arranged, the first current detection circuit comprises a first switch, and the second current detection circuit comprises a second switch; the first current detection circuit is used for detecting a first current on the first switch, and the second current detection circuit is used for detecting a second current on the second switch. The detected first and second currents can be indicative of a charge condition of the load. And comparing the detected first current and second current with preset current to accurately judge whether the load is full or not, so as to realize higher detection precision.
Drawings
In order that the invention may be more readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings, in which:
fig. 1 is a schematic circuit diagram of the present invention.
Description of the specification reference numerals: the power supply comprises a first comparator U1, a second comparator U2, a switch one SW1, a switch two SW2, an output capacitor C1, an input capacitor C2, a power converter U3 and a load U4.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and specific examples, which are not intended to be limiting, so that those skilled in the art will better understand the invention and practice it.
Referring to fig. 1, the present invention discloses a load current detection system, comprising:
a charging circuit, a first current detection circuit, and a second current detection circuit.
Specifically, the charging circuit includes a power converter U3 and a load U4. The input end of the power converter U3 is connected to an external power source, and the output end of the power converter U3 is connected to the input end of the load U4. The external power source charges the load U4 through the power converter U3.
Preferably, an input capacitor C2 is connected in parallel between the external power source and the power converter U3, and an output capacitor C1 is connected in parallel between the power converter U3 and the load U4. Through the filtering action of the input capacitor C2 and the output capacitor C1, the output voltage can be more stable.
The first current detection circuit comprises a switch one SW1, and the second current detection circuit comprises a switch two SW2. The switch one SW1 and the switch two SW2 are arranged in parallel in the charging circuit, and can be used to control the connection between the power converter U3 and the load U4 to be turned on or off. Preferably, the first switch SW1 is a first field effect transistor, and the second switch SW2 is a second field effect transistor; the field effect transistor has the advantages of small noise, low power consumption, large dynamic range and easy integration. The field effect transistor is selected as an electronic switch in the charging circuit, so that the performance of the charging circuit is more excellent.
One end of the switch SW1 is connected to the power supply end of the charging circuit, and the other end of the switch SW1 is connected to the load. Preferably, the first current detection circuit is capable of detecting a first current on the switch one SW1, and the second current detection circuit is capable of detecting a second current on the switch two. Both the first current and the second current are indicative of the charge condition of the load.
Specifically, the first current detection circuit further includes a first comparator U1. The positive pin of the input end of the first comparator U1 is connected with the drain electrode of the switch one SW1, the negative pin of the input end of the first comparator U1 is connected with the source electrode of the switch one SW1, and the output end of the first comparator U1 is connected with the grid electrode of the switch one SW 1. By increasing the current detection threshold of the first comparator U1, the threshold detection voltage of the first comparator U1 is increased, and thus the detection accuracy of the first comparator U1 and the consistency of mass production can be improved. Preferably, by providing the first current detection circuit, the current signal flowing through the switch SW1 can be detected under the first condition to finally obtain the first current detection signal indicating the charging condition of the load U4.
Specifically, the second current detection circuit further includes a second comparator U2. The positive pin of the input end of the second comparator U2 is connected with the drain electrode of the second switch SW2, the negative pin of the input end of the second comparator U2 is connected with the source electrode of the second switch SW2, and the output end of the second comparator U2 is connected with the gate electrode of the second switch SW2. By increasing the on-resistance of the second switch SW2, the second comparator U2 can detect the tiny current on the second switch SW2, the detection precision is high, the detection effect is good, and the charging conversion efficiency is not affected. Preferably, by providing the second current detection circuit described above, the current signal flowing through the switch two SW2 can be detected in the second condition to finally obtain the second current detection signal indicative of the charging condition of the load U4.
The invention discloses a load current detection method which is executed by the load current detection system. The load current detection method comprises the following steps:
s1, a first current detection circuit works, and when the first current detected by the first current detection circuit is smaller than a preset maximum current, a first switch is turned off, and a second switch is turned on; the preset maximum current is set to I.
S2, the second current detection circuit works, when the first current detected by the second current detection circuit is smaller than the preset minimum current, the switch II and the switch I are both turned off, the load is full, and the charging is stopped; the preset minimum current is set to i.
Wherein the preset maximum current I is n times of the preset minimum current I; the resistance of the switch two SW2 is larger than that of the switch one SW1, and the resistance of the switch two SW2 is n times of that of the switch one SW 1.
Preferably, when the load current is set to i, the load U4 is full, and the connection between the power converter U3 and the load U4 is disconnected. In order to be compatible with detecting the charging of the heavy current load U4, the switch SW1 is an electronic switch with smaller resistance value, and the resistance value of the switch SW1 turned on is set as R1. Meanwhile, the current detection threshold of the first comparator U1 is increased, and the current detection threshold of the first comparator U1 is set to be I, where i=n×i, and the value of n is greater than 1. By increasing the current detection threshold of the first comparator U1, the threshold detection voltage of the first comparator U1 can be increased, and finally, the detection accuracy of the first comparator U1 and the consistency of mass production can be improved.
Let I0 be the high current load application, where I < < I0. When the load current is smaller than I, the first comparator U1 is turned over, so that the first switch SW1 is closed, and meanwhile, the second switch SW2 is controlled to be opened. When the load current is less than I, the load is not applied to a heavy current load, so when the load current is less than or equal to I, a very small electronic switch is not needed to be selected, and the charging conversion efficiency is not affected. The on resistance R2 of the second switch SW2 is selected to be n times the resistance of the first switch, where n is greater than 1, n=i/I, and the second comparator U2 is capable of detecting a smaller current by increasing the resistance of the second switch SW2.
When the load current is further reduced to i, the second comparator U2 is turned over to turn off the switch two SW2, and at this time, both the switch one SW1 and the switch two SW2 are in the off mode, thereby disconnecting the power converter U3 and the load U4.
Preferably, in the load current detection system, the detection threshold current of the first comparator U1 and the on-resistance of the switch two SW2 are respectively improved. The voltage detection threshold is improved by n times, so that a voltage detection comparator with a higher threshold is used for detecting the set load current i, and higher detection precision and mass production consistency can be realized.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations and modifications of the present invention will be apparent to those of ordinary skill in the art in light of the foregoing description. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present invention.
Claims (7)
1. A load current detection system for controlling on-off of charging of a charging circuit, the load current detection system comprising:
the first current detection circuit comprises a first switch, one end of the first switch is connected with the power supply end of the charging circuit, and the other end of the first switch is connected with the load; the first current detection circuit is used for detecting a first current on the first switch;
the second current detection circuit comprises a switch II, and the switch II is connected with the switch I in parallel; the second current detection circuit is used for detecting a second current on the second switch;
the first current and the second current are used for representing the charging condition of the load; when the first current is smaller than the preset maximum current, the first switch is turned off, and the second switch is turned on; when the second current is smaller than the preset minimum current, the switch II and the switch I are both turned off, and the load stops charging;
the first current detection circuit comprises a first comparator; the positive pin of the first comparator is connected with the drain electrode of the first switch, the negative pin of the first comparator is connected with the source electrode of the first switch, and the output end of the first comparator is connected with the gate electrode of the first switch;
the second current detection circuit comprises a second comparator; the positive pin of the second comparator is connected with the drain electrode of the second switch, the negative electrode of the second comparator is connected with the source electrode of the second switch, and the output end of the second comparator is connected with the gate electrode of the second switch.
2. The load current detection system of claim 1, wherein the resistance of the second switch is greater than the resistance of the first switch.
3. The load current detection system of claim 1, wherein the switch one is a first fet; and the second switch is a second field effect transistor.
4. The load current detection system of claim 1, wherein the charging circuit comprises a power converter and a load; the input end of the power converter is connected with an external power supply, and the output end of the power converter is connected with the input end of the load so as to charge the load.
5. The load current detection system of claim 4, wherein an input capacitance is connected in parallel between the external power source and a power converter, and an output capacitance is connected in parallel between the power converter and the load.
6. Load current detection method, characterized in that it is performed by a load current detection system according to any one of claims 1-5, the load current detection method comprising the steps of:
s1, a first current detection circuit works, and when the first current detected by the first current detection circuit is smaller than a preset maximum current I, a first switch is turned off, and a second switch is turned on;
s2, the second current detection circuit works, when the first current detected by the second current detection circuit is smaller than a preset minimum current i, the switch II and the switch I are both turned off, the load is full, and the charging is stopped.
7. The load current detection method according to claim 6, wherein the preset maximum current I is n times the preset minimum current I; the resistance values of the switch II and the switch I meet the following relation: r2=n×r1, where R2 is the resistance of switch two, R1 is the resistance of switch one, and n=i/I.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110305088.8A CN112994169B (en) | 2021-03-18 | 2021-03-18 | Load current detection system and detection method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110305088.8A CN112994169B (en) | 2021-03-18 | 2021-03-18 | Load current detection system and detection method |
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| Publication Number | Publication Date |
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| CN112994169A CN112994169A (en) | 2021-06-18 |
| CN112994169B true CN112994169B (en) | 2024-03-29 |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107069909A (en) * | 2017-03-24 | 2017-08-18 | 浙江大学 | A kind of energy-saving mobile phone charger that can be automatically powered off |
| CN109212422A (en) * | 2018-11-13 | 2019-01-15 | 上海艾为电子技术股份有限公司 | Battery full charge testing circuit and its detection battery be full of method, electronic device |
| CN110601133A (en) * | 2019-09-10 | 2019-12-20 | 杰华特微电子（杭州）有限公司 | Leakage protection circuit, protection method and lighting circuit applying leakage protection circuit |
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2021
- 2021-03-18 CN CN202110305088.8A patent/CN112994169B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107069909A (en) * | 2017-03-24 | 2017-08-18 | 浙江大学 | A kind of energy-saving mobile phone charger that can be automatically powered off |
| CN109212422A (en) * | 2018-11-13 | 2019-01-15 | 上海艾为电子技术股份有限公司 | Battery full charge testing circuit and its detection battery be full of method, electronic device |
| CN110601133A (en) * | 2019-09-10 | 2019-12-20 | 杰华特微电子（杭州）有限公司 | Leakage protection circuit, protection method and lighting circuit applying leakage protection circuit |
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| CN112994169A (en) | 2021-06-18 |
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