CN108387771B - Reverse current detection system - Google Patents
Reverse current detection system Download PDFInfo
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- CN108387771B CN108387771B CN201810204520.2A CN201810204520A CN108387771B CN 108387771 B CN108387771 B CN 108387771B CN 201810204520 A CN201810204520 A CN 201810204520A CN 108387771 B CN108387771 B CN 108387771B
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- 238000001514 detection method Methods 0.000 title claims abstract description 74
- 230000005669 field effect Effects 0.000 claims description 3
- 229910044991 metal oxide Inorganic materials 0.000 claims description 3
- 150000004706 metal oxides Chemical class 0.000 claims description 3
- 239000004065 semiconductor Substances 0.000 claims description 3
- 239000003990 capacitor Substances 0.000 claims description 2
- 230000001105 regulatory effect Effects 0.000 claims 2
- 238000000034 method Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 238000010168 coupling process Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/0046—Arrangements for measuring currents or voltages or for indicating presence or sign thereof characterised by a specific application or detail not covered by any other subgroup of G01R19/00
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Abstract
The application discloses a reverse current detection system, which comprises: the power device, the comparator and the rectifying circuit are coupled between the comparator and the power device, and the rectifying circuit is used for compensating mismatch voltage of the comparator so that detection errors are reduced when the reverse current detection system detects reverse current. By the mode, the detection error of the reverse current detection system during reverse current detection can be reduced.
Description
Technical Field
The application relates to the technical field of reverse current detection, in particular to a reverse current detection system.
Background
In order to ensure the normal operation of components such as battery management, motor control and the like and avoid reverse current faults caused by short circuits, overload and the like, a traditional reverse current detection system shown in fig. 1 is generally adopted for detection.
The conventional reverse current detection system includes: the comparator 10 compares voltages across the power device 12 to determine whether or not there is an inverse current.
The inventor of the present application has found that in a long-term development process, the comparator 10 often has process deviation, and the differential input terminal of the comparator 10 is easy to generate a mismatch phenomenon, namely, the input mismatch voltage V 0 is added to the input terminal of the comparator 10. Under the influence of the mismatch voltage V 0, an error is generated in the judgment value of the reverse current detection, the error value is I 0,I0＝V0/Ron, where R on is the equivalent impedance of the detected power device 12.
Disclosure of Invention
The application mainly solves the technical problem of providing a reverse current detection system which can reduce detection errors when the reverse current detection system detects reverse current.
In order to solve the technical problems, the application adopts a technical scheme that: there is provided a reverse current detection system, the system comprising: the power device, the comparator and the rectifying circuit are coupled between the comparator and the power device, and the rectifying circuit is used for compensating mismatch voltage of the comparator so that detection errors are reduced when the reverse current detection system detects reverse current.
The beneficial effects of the application are as follows: in contrast to the prior art, the reverse current detection system comprises a rectification circuit coupled between the comparator and the power device, and the rectification circuit can output a compensation voltage which is offset with the mismatch voltage of the comparator, so that the detection error is reduced when the reverse current detection system performs reverse current detection.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art. Wherein:
FIG. 1 is a schematic circuit diagram of one embodiment of a conventional reverse current detection system;
FIG. 2 is a schematic circuit diagram of an embodiment of a reverse current detection system according to the present application;
fig. 3 is a schematic diagram of a switching cycle of one embodiment of the power device and single pole double throw switch of fig. 2.
Detailed Description
The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
Referring to fig. 2, fig. 2 is a schematic circuit diagram of an embodiment of a reverse current detection system according to the present application, the system includes: the power device 20, the comparator 22 and the rectifying circuit 24, the rectifying circuit 24 is coupled between the comparator 22 and the power device 20, and the rectifying circuit 24 is used for compensating the mismatch voltage V 1 of the comparator 22, so that the detection error is reduced when the reverse current detection system performs the reverse current detection. It should be noted that V 1 in fig. 2 is only a mismatch voltage inside the comparator 22, and is not a real circuit element, and is drawn inside the comparator 22 by a dotted line for clarity of the following description.
Specifically, in one embodiment, the power device 20 includes a first terminal 200 and a second terminal 202, the first terminal 200 having a first input voltage V p and the second terminal 202 having a second input voltage V m. In the present embodiment, the power device 20 is a two-terminal device, and in other embodiments, the power device 20 may be another multi-terminal device, such as a three-terminal device, a four-terminal device, and the like. In one application scenario, the power device 20 is any one or more of a bipolar junction transistor BJT, a metal-oxide semiconductor field effect transistor MOSFET, for example, the power device 20 is a combination of at least two bipolar junction transistors, or the power device 20 is a combination of one bipolar junction transistor BJT and one metal-oxide semiconductor field effect transistor MOSFET, etc. In other application scenarios, the power device 20 may be other, and the application is not limited thereto.
The comparator 22 includes a first input 220, a second input 222, and an output 224, wherein in one application scenario, the first input is a non-inverting input, and the second input is an inverting input; when the voltage input from the first input terminal 220 is greater than the voltage input from the second input terminal 222, the output terminal 224 outputs a high level signal; conversely, when the voltage input from the first input terminal 220 is smaller than the voltage input from the second input terminal 222, the output terminal 224 outputs a low level signal.
The rectifying circuit 24 includes a control sub-circuit 240 and a compensating sub-circuit 242, the compensating sub-circuit 242 is configured to output a compensating voltage V 2 to compensate for the mismatch voltage V 1 of the comparator 22, and the control sub-circuit 240 is configured to receive a feedback voltage signal output by the output end 224 of the comparator 22, and adjust the compensating voltage output by the compensating sub-circuit 242 according to the feedback voltage signal, so as to reduce a detection error when the reverse current detection system performs the reverse current detection. Specifically, the control sub-circuit 240 adjusts the principle as follows: the mismatch voltage of the comparator 22 is V 1, and the control sub-circuit 240 adjusts the output voltage V 2 of the compensation sub-circuit 242 according to the feedback voltage signal output by the comparator 22 so that the value of V 1+V2 is 0, thereby canceling the mismatch voltage V 1 of the comparator 22. Of course, the physical phenomenon and the actual life are not completely ' zero value ', and the value of V 1+V2 in the reverse current detection system provided by the application is continuously and repeatedly switched around +/-zero value ', and the value can be precisely made, and can be regarded as approximate ' zero value ' in practical application.
In an application scenario, referring to fig. 2, the compensation sub-circuit 242 is coupled between the first input end 220 of the comparator 22 and the first end 200 of the power device 20, the control sub-circuit 240 is coupled between the output end 224 of the comparator 22 and the compensation sub-circuit 242, and the control sub-circuit 240 adjusts the compensation voltage V 2 output by the compensation sub-circuit 242 according to the feedback voltage signal output by the output end 224 of the comparator 22, so that the detection error is reduced when the reverse current detection system performs the reverse current detection. In other application scenarios, the coupling manner of the compensation sub-circuit 242 and the comparator 22 and the power device 20 may be other, which is not limited in the present application, and any coupling method equivalent to the coupling method in fig. 2 is within the scope of the present application. For example, the compensation subcircuit 242 may be coupled with the first terminal 200 of the power device 20, the first input terminal 220 of the comparator 22, and the second input terminal 222; for another example, the compensation sub-circuit 242 may be coupled only to the first and second inputs 220 and 222 of the comparator 22.
In one application scenario, the control sub-circuit 240 is a logic gate circuit, and after the control sub-circuit 240 receives the feedback voltage signal output by the comparator 22, it outputs an adjustment signal to the compensation sub-circuit 242 according to the built-in logic adjustment method, and the compensation sub-circuit 242 adjusts the self-output compensation voltage according to the adjustment signal. In another application scenario, the compensating sub-circuit 242 includes a coupled resistor and an amplifying circuit, or a coupled capacitor and an amplifying circuit, and in other application scenarios, the compensating sub-circuit 242 may be other, which is not limited by the present application.
In another embodiment, referring to fig. 2, the reverse current detection system further includes a single pole double throw switch 26, where the single pole double throw switch 26 includes a stationary terminal a, a first closed terminal B and a second closed terminal C, the stationary terminal a is coupled to the second input terminal 222 of the comparator 22, the first closed terminal B is coupled to the first terminal 200 of the power device 20, and the second closed terminal C is coupled to the second terminal 202 of the power device 20. In one application scenario, the power device 20 includes a first switching frequency, and the single pole double throw switch 26 includes a first switching frequency that is the same as the first switching frequency. In other embodiments, single pole double throw switch 26 may be replaced with a type of switching device, as the application is not limited in this regard.
The reverse current detection system provided by the application is further described below in a specific application scenario.
The power device 20 provided by the application has a preset first switching frequency, the single-pole double-throw switch 26 has a preset first switching frequency, so that the reverse current detection system provided by the application is switched in a reverse current detection state and a deviation correction state, wherein when the power device is conducted, the reverse current detection system works in the reverse current detection state to execute a reverse current detection operation; when the power device is disconnected, the reverse current detection system works in a rectifying state to execute rectifying operation.
The nth switching period of the power device 20 is described as an example.
(1) Detecting state: in this state, the power device 20 is turned on, the stationary terminal a of the single pole double throw switch 26 is connected to the second closed terminal C, and at this time, the comparator 22, the compensation sub-circuit 242, and the power device 20 form a circuit loop, the output voltage of the compensation sub-circuit 242 at this time is the compensation voltage V 2(N-1) at the end of the last switching cycle, i.e., the N-1 switching cycle, and the reverse current detection system performs normal reverse current detection.
(2) Correcting: in this state, the power device 20 is turned off, and the stationary terminal a of the single pole double throw switch 26 is connected to the first closed terminal B, so that the comparator 22 is shorted, and the comparator 22 and the compensation sub-circuit 242 form a circuit loop. The output end 224 of the comparator 22 outputs a feedback voltage signal to the input end of the control sub-circuit 240, the control sub-circuit 240 outputs an adjustment signal to the compensation sub-circuit 242 according to the feedback voltage signal, the compensation sub-circuit 242 adjusts the original compensation voltage V 2(N-1) to V 2(N) according to the adjustment signal and outputs the adjusted compensation voltage V 2(N) at this time as the output voltage of the compensation sub-circuit 242 in the next switching cycle, i.e. when the nth switching cycle is in the detection state.
In an application scenario, please refer to fig. 3, when the reverse current detection system starts to perform the reverse current detection operation, the time t10 when the stationary end a of the single pole double throw switch 26 is switched to be connected to the second closed end C is no later than the time t20 when the power device 20 is turned on, that is, t10 is less than or equal to t20; in another application scenario, when the reverse current detection system starts to perform the rectification operation, the time t11 when the stationary end a of the single pole double throw switch 26 is switched to be connected to the first closed end B is not earlier than the time t21 when the power device 20 is disconnected, that is, t11 is not less than t21. In summary, it is within the scope of the present application to utilize the off-state of the power device 20 to perform the rectifying operation.
In one application scenario, the mismatch voltage V 1 of the comparator 22 is positive, and the output voltage V 2(N-1) of the compensation sub-circuit 242 is negative. If the output 224 of the comparator 22 outputs a high-level feedback voltage signal to the control sub-circuit 240, the control sub-circuit 240 determines that the value of V 1+V2(N-1) is greater than zero, the control sub-circuit 240 outputs an adjustment signal for adjusting the compensation voltage V 2(N-1) output by the current compensation sub-circuit 242 by one bit according to a predetermined step Δv to the compensation sub-circuit 242, and the compensation sub-circuit 242 adjusts the output compensation voltage V 2(N) to V 2(N-1) - Δv, that is, V 2(N)＝V2(N-1) - Δv, where the predetermined step Δv may be 1V, 0.1V, 0.01V, etc.
In another application scenario, if the output end 224 of the comparator 22 outputs a low-level feedback voltage signal to the control sub-circuit 240, the control sub-circuit 240 determines that the value of V 1+V2(N-1) is smaller than zero, the control sub-circuit 240 outputs an adjustment signal for adjusting the compensation voltage V 2(N-1) output by the current compensation sub-circuit 242 by one bit according to a predetermined step Δv to the compensation sub-circuit 242, and the compensation sub-circuit 242 adjusts the output compensation voltage V 2(N) to V 2(N-1) +Δv, that is, V 2(N)＝V2(N-1) +Δv, where the predetermined step Δv may be 1V, 0.1V, 0.01V, etc.
In other application scenarios, in order to avoid erroneous judgment of the reverse current detection system, which results in continuous adjustment of the compensation voltage V 2, the control sub-circuit 240 may adjust the current compensation voltage V 2 only when the feedback voltage signal is a high level signal for a predetermined number of times or is a low level signal for a predetermined number of times. The predetermined number of times includes, but is not limited to, 0 times, 1 time, 2 times, 3 times, 4 times.
In another embodiment, when the power device 20 is in the 1 st switching cycle, the compensation sub-circuit 242 may preset an initial compensation voltage V 20, and the value of the initial compensation voltage V 20 may be set according to the previous experience.
In other embodiments, the method of adjusting the compensation voltage V 2 output by the current compensation sub-circuit 242 by the control sub-circuit 240 can be other, and the comparison is not limited.
In summary, unlike the prior art, the reverse current detection system of the present application includes a rectifying circuit coupled between the comparator and the power device, and the rectifying circuit is capable of outputting a compensation voltage that is offset with the mismatch voltage of the comparator, so that the detection error is reduced when the reverse current detection system performs the reverse current detection.
The foregoing description is only of embodiments of the present application, and is not intended to limit the scope of the application, and all equivalent structures or equivalent processes using the descriptions and the drawings of the present application or directly or indirectly applied to other related technical fields are included in the scope of the present application.
Claims (5)
1. A reverse current detection system, the system comprising:
The power device, the comparator, the rectifying circuit and the single-pole double-throw switch, wherein the rectifying circuit is coupled between the comparator and the power device;
the power device comprises a first end and a second end, wherein the first end is provided with a first input voltage Vp, and the second end is provided with a second input voltage Vm;
The comparator comprises a first input end, a second input end and an output end;
The correction circuit comprises a control sub-circuit and a compensation sub-circuit, wherein the compensation sub-circuit is used for outputting compensation voltage to compensate mismatch voltage of the comparator, and the control sub-circuit receives feedback voltage signals output by the output end of the comparator and adjusts the compensation voltage output by the compensation sub-circuit according to the feedback voltage signals, so that detection errors are reduced when the reverse current detection system performs reverse current detection;
The single pole double throw switch comprises a stationary end, a first closed end and a second closed end, wherein the stationary end is coupled with the second input end of the comparator, the first closed end is coupled with the first end of the power device, and the second closed end is coupled with the second end of the power device;
the reverse current detection system is switched between a reverse current detection state and a deviation correction state, and works in the reverse current detection state to execute reverse current detection operation when the power device is conducted; when the power device is disconnected, the reverse current detection system works in the rectifying state to execute rectifying operation;
when the reverse current detection system works in the deviation rectifying state, the comparator outputs the feedback voltage signal to the control sub-circuit, the control sub-circuit outputs an adjusting signal to the compensation sub-circuit according to the feedback voltage signal, and the compensation sub-circuit adjusts and outputs the compensation voltage according to the adjusting signal;
The control sub-circuit outputs an adjusting signal to the compensation sub-circuit according to the feedback voltage signal, and the compensation sub-circuit adjusts the output compensation voltage according to the adjusting signal, including: the feedback voltage signal is a low level signal continuously for a preset number of times, the control sub-circuit outputs a signal for adjusting the compensation voltage of the current compensation sub-circuit by one bit according to a preset step length to the compensation sub-circuit, and the compensation sub-circuit adjusts the current compensation voltage by one bit according to the preset step length and outputs the adjusted compensation voltage; the feedback voltage signal is a high-level signal continuously for a preset number of times, the control sub-circuit outputs a signal for downwards regulating the compensation voltage of the current compensation sub-circuit by one bit according to a preset step length to the compensation sub-circuit, and the compensation sub-circuit downwards regulates the current compensation voltage by one bit according to the preset step length and outputs the regulated compensation voltage; the predetermined number of times includes 1 time, 2 times, 3 times, 4 times.
2. The system of claim 1, wherein the system further comprises a controller configured to control the controller,
When the reverse current detection system works in the reverse current detection state, the power device is conducted, the fixed end of the single-pole double-throw switch is connected with the second closed end, the output voltage of the compensation sub-circuit is the compensation voltage, and the reverse current detection system performs reverse current detection;
When the reverse current detection system works in the deviation rectifying state, the power device is disconnected, and the fixed end of the single-pole double-throw switch is connected with the first closed end, so that the comparator is short-circuited.
3. The system of claim 2, wherein the system further comprises a controller configured to control the controller,
When the reverse current detection system starts to execute the reverse current detection operation, the moment when the fixed end of the single-pole double-throw switch is switched to be connected with the second closed end is not later than the moment when the power device is conducted;
And/or when the reverse current detection system starts to execute the deviation rectifying operation, the moment that the fixed end of the single-pole double-throw switch is switched to be connected with the first closed end is not earlier than the moment that the power device is disconnected.
4. The system of claim 1, wherein the system further comprises a controller configured to control the controller,
The compensation sub-circuit comprises a resistor and an amplifying circuit which are coupled; or the compensation subcircuit includes a capacitor and an amplifying circuit coupled.
5. The system of claim 1, wherein the system further comprises a controller configured to control the controller,
The power device includes any one or a combination of a bipolar junction transistor BJT, a metal-oxide semiconductor field effect transistor MOSFET.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810204520.2A CN108387771B (en) | 2018-03-13 | 2018-03-13 | Reverse current detection system |
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| CN201810204520.2A CN108387771B (en) | 2018-03-13 | 2018-03-13 | Reverse current detection system |
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| CN108387771B true CN108387771B (en) | 2024-08-23 |
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| CN117134296B (en) * | 2022-05-20 | 2024-07-09 | 安世半导体科技(上海)有限公司 | Load switch and power supply system |
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| JP5422922B2 (en) * | 2008-05-29 | 2014-02-19 | 富士電機株式会社 | Backflow prevention circuit for synchronous rectification type DC-DC converter |
| US8896283B2 (en) * | 2011-01-07 | 2014-11-25 | Anpec Electronics Corporation | Synchronous switching power converter with zero current detection, and method thereof |
| TW201240341A (en) * | 2011-03-17 | 2012-10-01 | Anpec Electronics Corp | Zero current detecting circuit and related synchronous switching power converter |
| JP5962115B2 (en) * | 2012-03-26 | 2016-08-03 | 富士通株式会社 | Power circuit |
| CN105842526B (en) * | 2012-05-19 | 2019-05-24 | 快捷半导体(苏州)有限公司 | A kind of zero current detecting circuit and method and voltage conversion circuit |
| KR102031534B1 (en) * | 2013-01-07 | 2019-10-14 | 삼성전자 주식회사 | Switching regulator and method for detecting zero current of switching regulator |
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