Circuit and system integrating current acquisition and over-current detection

Abstract

The invention provides a circuit and system for integrating current acquisition and overcurrent detection, and the circuit comprises an amplifier, the positive input end and the negative input end of which are respectively connected with the two ends of a unit to be detected; the input end of the analog-to-digital converter is connected with the output end of the amplifier; the input end of the first filtering unit is connected with the output end of the analog-to-digital converter, and the output end of the first filtering unit serves as a current acquisition output end; and the input end of the second filtering unit is connected with the output end of the analog-to-digital converter, and the output end of the second filtering unit is used as an overcurrent detection output end. The circuit and system integrating current acquisition and overcurrent detection are simple in structure, and high-precision rapid overcurrent detection is realized on the basis of high-precision current acquisition.

Description

Technical Field

[0001] The present invention relates to the technical field of current acquisition, and particularly relates to a circuit and system integrating current acquisition and overcurrent detection. Background Art

[0002] There are mainly two types of overcurrent detection circuits integrated in traditional current acquisition systems: First, it is implemented through an overcurrent comparator directly connected to the unit under test as shown in Figure 1 , and the detection accuracy of this solution is poor; Second, it is implemented through a fast overcurrent ADC directly connected to the unit under test as shown in Figure 2 . Due to the kickback of the fast overcurrent ADC, this solution will affect the unit under test, and further affect the sampling value of the current acquisition ADC. The sampling frequencies of the two ADCs cannot be kept exactly the same. Summary of the Invention

[0003] The present invention provides a circuit and system integrating current acquisition and overcurrent detection to solve the problems of poor detection accuracy and kickback affecting the current sampling value in the prior art.

[0004] To solve the above technical problems, the present invention is implemented through the following technical solutions:

[0005] According to the first aspect of the present invention, there is provided a circuit integrating current acquisition and overcurrent detection, which includes:

[0006] An amplifier, whose positive input terminal and negative input terminal are respectively connected to both ends of the unit under test;

[0007] An analog-to-digital converter, whose input terminal is connected to the output terminal of the amplifier;

[0008] A first filtering unit, whose input terminal is connected to the output terminal of the analog-to-digital converter, and whose output terminal serves as the current acquisition output terminal; and,

[0009] A second filtering unit, whose input terminal is connected to the output terminal of the analog-to-digital converter, and whose output terminal serves as the overcurrent detection output terminal.

[0010] Optionally,

[0011] The order of the first filtering unit is greater than that of the second filtering unit.

[0012] Optionally, the first filtering unit includes: a plurality of cascaded low-order filters;

[0013] The second filtering unit includes: one low-order filter starting from the input terminal or several cascaded low-order filters in the first filtering unit; the number of low-order filters in the second filtering unit is less than the number of low-order filters in the first filtering unit.

[0014] Optionally, the order of the first filtering unit is a multiple of the order of the second filtering unit.

[0015] Optionally, the output end of the second filtering unit serves as an overcurrent detection output end, specifically: the output end of the second filtering unit serves as a first overcurrent detection output end;

[0016] The circuit further includes: an overcurrent comparator; its two input ends are respectively connected to both ends of the unit under test, and its output end serves as a second overcurrent detection output end to obtain a final overcurrent detection result according to the data of the first overcurrent detection output end and the data of the second overcurrent detection output end.

[0017] Optionally, the first overcurrent detection output end and the second overcurrent detection output end are respectively connected to two input ends of an AND operation unit, and the output end of the AND operation unit serves as the final overcurrent detection output end;

[0018] The AND operation unit further includes an enable input end. When the enable input end is valid, overcurrent detection reporting is enabled; when the enable input end is invalid, overcurrent detection reporting is masked.

[0019] Optionally, the circuit further includes: a first chopper, which is connected between the unit under test and the amplifier.

[0020] Optionally, the circuit further includes:

[0021] a second chopper, which is connected between the amplifier and the mode converter; and / or,

[0022] a third chopper, which is connected between the first chopper and the amplifier.

[0023] Optionally, the amplifier is a variable gain amplifier;

[0024] The circuit further includes: an automatic gain control unit, which is connected between the mode converter and the amplifier.

[0025] According to the second aspect of the present invention, there is provided a system integrating current acquisition and overcurrent detection, which includes:

[0026] a unit under test;

[0027] The integrated current acquisition and overcurrent detection circuit as described in any one of the above, which is used for current acquisition and overcurrent detection of the unit under test.

[0028] The circuit and system for integrated current acquisition and overcurrent detection provided by the present invention achieve overcurrent detection through a second filtering unit arranged after the analog-to-digital converter. The speed and accuracy of overcurrent can be flexibly balanced by adjusting the oversampling rate of the second filtering unit, enabling high-precision and fast overcurrent on the basis of achieving high-precision current acquisition; and the structure is simple.

[0029] In an alternative embodiment of the present invention, the first filtering unit includes a plurality of cascaded low-order filters, and the second filtering unit includes one or several low-order filters starting from the input end of the first filtering unit. That is, the second filtering unit is equivalent to a part of the first filtering unit, and the two achieve combined decimation. Thus, it is equivalent to implementing both current acquisition and overcurrent detection through the current acquisition module, further simplifying the circuit structure.

[0030] In an alternative embodiment of the present invention, a second overcurrent comparator connected across the unit under test is used for second overcurrent detection. The overcurrent comparator serves as a redundant supplement to the second filtering unit. When a fault occurs in the overcurrent detection of the second filtering unit, overcurrent detection can still be achieved, making the overcurrent detection safer and capable of meeting more application scenarios.

[0031] In an alternative embodiment of the present invention, frequency modulation of the amplifier is performed by a second chopper arranged before the amplifier and / or a third chopper arranged after the amplifier, which can eliminate the offset voltage of the amplifier and further improve the accuracy of overcurrent detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0033] Figure 1 It is a circuit diagram of an overcurrent detection for the prior art;

[0034] Figure 2 It is another circuit diagram of an overcurrent detection for the prior art;

[0035] Figure 3 It is a schematic circuit diagram of the integrated current acquisition and overcurrent detection according to an embodiment of the present invention;

[0036] Figure 4 It is a timing diagram of current acquisition and overcurrent detection according to an embodiment of the present invention;

[0037] Figure 5 It is a schematic circuit diagram of the integrated current acquisition and overcurrent detection according to another embodiment of the present invention;

[0038] Figure 6 Schematic diagram of a circuit integrating current acquisition and overcurrent detection according to another embodiment of the present invention;

[0039] Description of the reference numerals in the drawings:

[0040] 1 - Unit under test;

[0041] 2 - Circuit integrating current acquisition and overcurrent detection;

[0042] 201 - Amplifier;

[0043] 202 - Analog - to - digital converter;

[0044] 203 - First filtering unit;

[0045] 204 - Second filtering unit;

[0046] 205 - Automatic gain control unit;

[0047] 206 - First chopper. Detailed implementation manners

[0048] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0049] In the description of the specification of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "upper part", "lower part", "upper end", "lower end", "lower surface", "upper surface", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0050] In the description of the specification of the present invention, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0051] In the description of the present invention, "a plurality" means a plurality, such as two, three, four, etc., unless otherwise specifically defined.

[0052] In the description of the specification of the present invention, unless otherwise clearly specified and defined, terms such as "connection" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection, an electrical connection, or capable of communicating with each other; it may be directly connected, or indirectly connected through an intermediate medium, and may be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0053] The technical solution of the present invention will be described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0054] In one embodiment, a circuit 2 integrating current acquisition and overcurrent detection is provided. Please refer to Figure 3 , which includes:

[0055] An amplifier 201, whose positive input terminal and negative input terminal are respectively connected to both ends of the unit under test 1;

[0056] An analog-to-digital converter 202, whose input terminal is connected to the output terminal of the amplifier;

[0057] A first filtering unit 203, whose input terminal is connected to the output terminal of the analog-to-digital converter, and whose output terminal serves as the current acquisition output terminal CS, that is, the first filtering unit is used to implement current acquisition; and,

[0058] A second filtering unit 204, whose input terminal is connected to the output terminal of the analog-to-digital converter, and whose output terminal serves as the overcurrent detection output terminal OCD, that is, the second filtering unit is used to implement overcurrent detection.

[0059] The oversampling rate (OSR) of the first filtering unit and the second filtering unit can be freely set as needed.

[0060] Generally, current acquisition has relatively high requirements for accuracy, and overcurrent detection has relatively high requirements for conversion rate.

[0061] As an implementation manner, the first filtering unit and the second filtering unit can be implemented by a sinc filter.

[0062] As an implementation manner, the order of the first filtering unit is greater than that of the second filtering unit. A relatively large order of the first filtering unit can make the current acquisition meet relatively high accuracy requirements; when the accuracy requirements are high and the order is relatively high, the corresponding data conversion rate will be a little slower. The second filtering unit does not have as high requirements for accuracy as current acquisition. Therefore, the accuracy and data conversion rate can be compromised, and the order is selected to be smaller than that of the first filtering unit, which can not only meet overcurrent, but also the accuracy can reach certain requirements.

[0063] As an implementation manner, the order of the first filtering unit can be several times that of the second filtering unit, such as three times.

[0064] Assume that the second filtering unit is a first-order filter sinc1, and the first filtering unit can be a third-order filter sinc3. At this time, the conversion rate of the second filtering unit is three times that of the first filtering unit. Please refer to Figure 4 , the second filtering unit requires a complete conversion period to stabilize to a step input, and the internal ADC is completely stable at the end of one conversion period; for the first filtering unit, the delay is three conversion periods instead of one, and it requires three complete conversion periods to stabilize when there is a step input, and the internal ADC is stable at the end of three conversion periods.

[0065] As an implementation manner, the first filtering unit may include: a plurality of cascaded low-order filters, and the second filtering unit may include: one or several cascaded low-order filters starting from the input end in the first filtering unit; however, the number of low-order filters in the second filtering unit is less than the number of low-order filters in the first filtering unit.

[0066] As an example, the first filtering unit is formed by cascading three low-order filters, and the second filtering unit includes one low-order filter starting from the input end in the first filtering unit. In this implementation manner, the first filtering unit and the second filtering unit achieve combined decimation, that is, the second filtering unit is extracted from the first filtering unit, and the second filtering unit is equivalent to a part of the first filtering unit. The two achieve combined decimation, and thus it is equivalent to realizing both current acquisition and overcurrent detection through the current acquisition module (the first filtering unit), further simplifying the circuit structure.

[0067] In the above example, the second filtering unit takes one low-order filter as an example. In different examples, when the first filtering unit includes three cascaded low-order filters, the second filtering unit may also include two cascaded low-order filters starting from the input end of the first filtering unit. When the number of low-order filters included in the first filtering unit is other values, the principle of the number of low-order filters included in the second filtering unit is similar to the above, and it can be one or multiple, as long as it is ensured that the number of low-order filters it includes is less than the number of low-order filters included in the first filtering unit.

[0068] As an implementation manner, the circuit further includes: a first chopper 206, which is disposed between the unit under test 1 and the amplifier 201, and is used for frequency modulation of the unit under test.

[0069] Preferably, the amplifier 201 can be a variable gain amplifier. Please continue to refer to Figure 3, meanwhile, the circuit further includes: an automatic gain control unit 205, which is connected between the analog-to-digital converter 202 and the amplifier 201, and is used for automatically controlling the gain of the amplifier 201.

[0070] The circuit for integrated current acquisition and overcurrent detection provided by the above embodiment realizes overcurrent detection through the second filtering unit arranged after the analog-to-digital converter. The speed and accuracy of overcurrent can be flexibly balanced by adjusting the oversampling rate of the second filtering unit, and high-precision and fast overcurrent can be realized on the basis of realizing high-precision current acquisition; and the structure is simple.

[0071] In another embodiment, in addition to including each component in the circuit as Figure 3 shown, the circuit further includes frequency modulation of the amplifier. When calculating the overcurrent error in percentage, the error of large current needs to be made small enough, and a relatively high precision is required for a large overcurrent threshold; by setting the amplifier frequency modulation, the offset voltage of the amplifier can be eliminated, further improving the overcurrent precision, and thus making the overcurrent threshold range larger.

[0072] As an implementation manner, please refer to Figure 5 , a second chopper Fop is arranged before the amplifier, that is, it is arranged between the first chopper and the amplifier, and the frequency of the amplifier is modulated by the second chopper.

[0073] As another implementation manner, please continue to refer to Figure 5 , a third chopper Fop is arranged after the amplifier, that is, it is arranged between the amplifier and the analog-to-digital converter, and the frequency of the amplifier is modulated by the third chopper.

[0074] Preferably, please continue to refer to Figure 5 , not only a second chopper Fop is arranged before the amplifier, but also a third chopper Fop is arranged after the amplifier, and the frequency of the amplifier is modulated by the second chopper and the third chopper together.

[0075] In yet another embodiment, in addition to including each component in the circuit as Figure 5 shown, the circuit further includes: an overcurrent comparator, whose two input terminals are connected to both ends of the unit under test, and whose output terminal serves as the second overcurrent detection output terminal OCD2, please refer to Figure 6 ; at this time, the output terminal of the second filtering unit sinc1 is the first overcurrent detection output terminal OCD1, and the overcurrent detection data of the two overcurrent detection output terminals can be transmitted to the controller, and the controller can obtain the final overcurrent detection result according to the two overcurrent detection data. Specifically, when both overcurrent detection data report overcurrent, the final overcurrent detection report is triggered as a functional safety redundancy.

[0076] As an implementation manner, obtaining the final overcurrent detection result according to the two overcurrent detection data can be achieved through a program.

[0077] Of course, obtaining the final overcurrent detection result according to the two overcurrent detection data can also be achieved through a circuit. For example, it can be achieved through an AND operation unit. Please continue to refer to Figure 6. The first overcurrent detection output terminal OCD1 and the second overcurrent detection output terminal OCD2 are respectively connected to the two input terminals of the AND operation unit, and the output terminal of the AND operation unit is the final overcurrent detection output terminal.

[0078] Preferably, the AND operation unit further includes an enable input terminal OCD_EN. Please continue to refer to Figure 6 , and the overcurrent reporting function can be controlled through the enable input terminal. Specifically, when the enable input terminal OCD_EN of the AND operation unit is valid, that is, OCD_EN = 1, the overcurrent reporting function is enabled; when the enable input terminal OCD_EN of the AND operation unit is invalid, that is, OCD_EN = 0, the overcurrent reporting function is masked.

[0079] In different embodiments, it is also possible not to judge the two overcurrent detection data through a controller, but directly output the two overcurrent detection data, and let a person or other subsequent components determine the final overcurrent detection result according to needs.

[0080] In this embodiment, on the basis of the second filtering unit implementing overcurrent detection, an overcurrent comparator is further added. The overcurrent comparator also performs overcurrent detection. Only when both overcurrent detections report overcurrent will the final overcurrent detection report be triggered. That is, the overcurrent comparator verifies the overcurrent detection of the second filtering unit, provides redundant supplementation for the second filtering unit, makes the overcurrent detection safer, and can meet more application scenarios.

[0081] In one embodiment, a system integrating current acquisition and overcurrent detection is also provided. Please refer to Figure 3 , which includes: a unit under test 1; and further includes: a circuit 2 integrating current acquisition and overcurrent detection, which is used to perform current acquisition and overcurrent detection on the unit under test. The circuit integrating current acquisition and overcurrent detection can be the circuit integrating current acquisition and overcurrent detection described in any of the above embodiments, and will not be elaborated here.

[0082] In the description of this specification, the descriptions referring to terms such as "an implementation manner", "an embodiment", "specific implementation process", "an example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A circuit integrating current acquisition and overcurrent detection, characterized in that: include: An amplifier, whose positive input terminal and negative input terminal are respectively connected to two ends of the unit under test; an analog-to-digital converter, whose input end is connected to the output end of the amplifier; A first filtering unit, whose input end is connected to the output end of the analog-to-digital converter and whose output end serves as a current acquisition output end; as well as, The second filtering unit has an input end connected to the output end of the analog-to-digital converter and an output end serving as an overcurrent detection output end.

2. The integrated current acquisition and overcurrent detection circuit according to claim 1, characterized in that: The order of the first filtering unit is greater than the order of the second filtering unit.

3. The integrated current acquisition and overcurrent detection circuit according to claim 2, characterized in that: The first filtering unit comprises: a plurality of cascaded low-order filters; The second filtering unit includes: a low-order filter or several cascaded low-order filters starting from the input end of the first filtering unit; the number of low-order filters in the second filtering unit is less than the number of low-order filters in the first filtering unit.

4. The integrated current acquisition and overcurrent detection circuit according to claim 2, characterized in that: The order of the first filtering unit is several times the order of the second filtering unit.

5. The integrated current acquisition and overcurrent detection circuit according to claim 1, characterized in that: The output end of the second filtering unit is used as an over-current detection output end, specifically: the output end of the second filtering unit is used as a first over-current detection output end; The circuit also includes: an overcurrent comparator; its two input ends are respectively connected to the two ends of the unit to be tested, and its output end serves as a second overcurrent detection output end to obtain a final overcurrent detection result based on the data of the first overcurrent detection output end and the data of the second overcurrent detection output end.

6. The integrated current acquisition and overcurrent detection circuit according to claim 5, characterized in that: The first over-current detection output terminal and the second over-current detection output terminal are respectively connected to two input terminals of an AND operation unit, and the output terminal of the AND operation unit serves as a final over-current detection output terminal; The AND operation unit also includes an enable input terminal. When the enable input terminal is valid, overcurrent detection and reporting are enabled; when the enable input terminal is invalid, overcurrent detection and reporting are disabled.

7. The circuit for integrated current acquisition and overcurrent detection according to any one of claims 1 to 6, characterized in that: The circuit further includes: a first chopper connected between the unit under test and the amplifier.

8. The integrated current acquisition and overcurrent detection circuit according to claim 7, characterized in that: The circuit also includes: a second chopper connected between the amplifier and the mode converter; and / or, A third chopper is connected between the first chopper and the amplifier.

9. The integrated current acquisition and overcurrent detection circuit according to any one of claims 1 to 6, characterized in that: The amplifier is a variable gain amplifier; The circuit further includes: an automatic gain control unit connected between the mode converter and the amplifier.

10. A system integrating current acquisition and overcurrent detection, characterized in that: include: Unit under test; The integrated current acquisition and overcurrent detection circuit according to any one of claims 1 to 9 is used to perform current acquisition and overcurrent detection on the unit to be tested.

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