A floating ground current output circuit and method for replacing a dc voltage hall sensor

Abstract

The application discloses a floating ground current output circuit and method for replacing a direct current voltage Hall sensor, and the floating ground current output circuit comprises an operational amplifier, a resistor and a triode; the floating ground current output circuit adopts the operational amplifier virtual short and operational amplifier virtual break principles, converts bidirectional direct current voltage into bidirectional direct current output through the resistor, and expands the current output through the triode. The floating ground current output circuit provided by the application can be combined with a conventional electromagnetic isolation sensor, a photoelectric isolation sensor and a modulation demodulation sensor circuit, can replace the floating ground current output mode of the direct current voltage Hall sensor, can convert bidirectional direct current voltage into bidirectional direct current output, and can control the detection precision within a 0.1% error range. Compared with the floating ground current conversion circuit of the direct current voltage Hall sensor itself, the floating ground current output circuit has the advantages of low temperature drift, high precision and small power consumption.

Description

Technical Field

[0001] This invention relates to the field of Hall sensor output conversion technology, and specifically to a floating current output circuit and method that replaces a DC voltage Hall sensor. Background Technology

[0002] Existing DC voltage Hall effect sensors use a three-wire output mode, meaning the output terminal includes a positive power supply (+Vc), a negative power supply (-Vc), and an output (Is). The output is connected to the power supply ground via a sampling resistor (Rm) to achieve detection. The power supply ground is externally connected, as detailed below. Figure 1 As shown. However, conventional electromagnetic isolation sensors, opto-isolation sensors, and modem sensors all require a reference ground for both power supply and output, employing a four-wire output method. This means the output terminal includes a positive power supply (+), a negative power supply (-), power ground (GND), and output (Iout), as detailed below. Figure 2 As shown. Therefore, conventional isolation devices cannot meet the three-wire output mode of DC voltage Hall sensors.

[0003] Therefore, in order to connect conventional isolation sensors and Hall sensors, it is necessary to convert and adapt the output mode through a conversion circuit. However, the conversion circuit of the DC voltage Hall sensor itself has the disadvantages of high temperature drift, poor accuracy and high power consumption, and is not suitable for scenarios with high accuracy requirements and low power consumption requirements. Summary of the Invention

[0004] To address the issues of high temperature drift, poor accuracy, and high power consumption inherent in the mode output conversion circuits of existing DC Hall sensors, this invention provides a floating current output circuit and method to replace DC voltage Hall sensors. The floating current output circuit provided by this invention uses conventional analog devices to convert bidirectional DC voltage into a floating current output, offering advantages such as low temperature drift, high accuracy, and low power consumption.

[0005] This invention is achieved through the following technical solution:

[0006] A floating current output circuit is provided as an alternative to a DC voltage Hall sensor. The floating current output circuit adopts the principles of virtual short and virtual open operation of operational amplifiers. It converts bidirectional DC voltage into bidirectional DC current output through a resistor and amplifies the output through a transistor. The detection accuracy can be controlled within 0.1% error range according to actual needs, thus improving the detection accuracy. At the same time, the floating current output circuit of this invention can be implemented using ordinary analog devices, which is low in cost, has small temperature drift, and high detection accuracy.

[0007] The floating ground current output circuit provided by this invention adopts the principle of virtual short and virtual open input of operational amplifier, converts bidirectional DC voltage into bidirectional DC current through resistor, and then outputs it through transistor.

[0008] In a preferred embodiment, the floating current output circuit of the present invention includes an operational amplifier, resistor A, resistor B, resistor C, resistor D, transistor A, and transistor B.

[0009] In this circuit, one end of resistor A is connected to the output signal terminal of the front-end isolation circuit, the other end of resistor A is connected to the non-inverting input terminal of the operational amplifier and one end of resistor B, the other end of resistor B is connected to one end of resistor C, the common connection terminal of resistors B and C serves as the current output terminal of the floating ground current output circuit, the other end of resistor C is connected to the inverting input terminal of the operational amplifier and the internal floating ground plane of the front-end isolation circuit, the output terminal of the operational amplifier is connected to the base of transistor A and the base of transistor B, the collector of transistor A serves as the positive power supply terminal of the floating ground current output circuit, the emitter of transistor A is connected to the emitter of transistor B, the common connection terminal of the emitters of transistor A and B is connected to one end of resistor D, the other end of resistor D is connected to the internal floating ground plane of the front-end isolation circuit, and the collector of transistor B serves as the negative power supply terminal of the floating ground current output circuit.

[0010] In a preferred embodiment, the operational amplifier of the present invention is connected to an external power supply.

[0011] In a preferred embodiment, the positive and negative power supply terminals of the floating ground current output circuit of the present invention are connected to an external power supply.

[0012] In a preferred embodiment, the current output terminal of the floating current output circuit of the present invention can be connected to the external power supply reference ground through a sampling resistor to achieve detection. The floating current output circuit of the present invention is a three-wire output mode, which is the same as the wiring mode of a DC voltage Hall sensor. Therefore, the floating current output circuit of the present invention can be widely used in applications with high requirements for detection accuracy and cost to replace DC voltage Hall sensors.

[0013] In a preferred embodiment, the front-end isolation circuit of the present invention can generate a ±1V DC voltage signal by referencing the internal floating ground plane.

[0014] In a preferred embodiment, the floating ground current output circuit of the present invention outputs a current of ±50mA. Since the output current capability of operational amplifiers is limited, typically 10mA, the floating ground current output circuit proposed in this invention uses a transistor pair to amplify the current output, enabling it to achieve an output current of ±50mA.

[0015] In a preferred embodiment, transistor A of the present invention is used for forward current amplification;

[0016] The transistor B is used for negative current amplification.

[0017] On the other hand, the present invention also proposes a working method based on the above-mentioned floating ground current output circuit, the method comprising:

[0018] A 1V DC voltage signal is generated by referencing the internal floating ground plane through the front-end isolation circuit. Due to the virtual short of the op-amp, the voltage across resistor C is the same as the voltage across resistor B. Due to the virtual open of the op-amp, the voltage across resistor A generates a current that flows through resistor B. The voltage across resistor B is opposite to the voltage drop across resistor A, which is a -1V DC voltage signal. The current across resistor C is -50mA.

[0019] In a preferred embodiment, the method of the present invention further includes:

[0020] The front-end isolation short-circuit reference internal floating ground plane generates a -1V DC voltage signal. Due to the virtual short of the op-amp, the voltage across resistor C is the same as the voltage across resistor B. Due to the virtual open of the op-amp, the voltage across resistor A generates a current that flows through resistor B. The voltage across resistor B is opposite to the voltage drop across resistor A, which is a 1V DC voltage signal. The current across resistor C is +50mA.

[0021] The present invention has the following advantages and beneficial effects:

[0022] The floating current output circuit provided by this invention can be combined with conventional electromagnetic isolation sensors, opto-isolation sensors, and modulation / demodulation sensor circuits to replace the floating current output mode of DC voltage Hall sensors, converting bidirectional DC voltage into bidirectional DC current output, with detection accuracy controlled within the 0.1% error range.

[0023] Compared to the floating ground current conversion circuit of the DC voltage Hall sensor itself, the floating ground current output circuit provided by this invention uses conventional analog devices, which has the advantages of low cost, high detection accuracy, low temperature drift and low power consumption. It can be widely used in industries such as railway and industrial control to replace the floating ground current output mode of DC voltage Hall sensors. Attached Figure Description

[0024] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0025] Figure 1 This is a schematic diagram of the wiring method for a DC voltage Hall sensor.

[0026] Figure 2 This diagram illustrates the output methods of conventional electromagnetic isolation sensors, opto-isolation sensors, and modulation / demodulation sensors.

[0027] Figure 3 This is a block diagram of the floating ground current output circuit according to an embodiment of the present invention.

[0028] Figure 4 This is a schematic diagram of the floating ground current output circuit according to an embodiment of the present invention. Detailed Implementation

[0029] In the following, the terms “comprising” or “may include” as used in various embodiments of the invention indicate the presence of an inventive function, operation, or element, and do not limit the addition of one or more functions, operations, or elements. Furthermore, as used in various embodiments of the invention, the terms “comprising,” “having,” and their cognates are intended only to indicate a specific feature, number, step, operation, element, component, or combination of the foregoing, and should not be construed as primarily excluding the presence of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing, or adding one or more combinations of the foregoing.

[0030] In various embodiments of the invention, the expression "or" or "at least one of A and / or B" includes any combination or all combinations of the words listed simultaneously. For example, the expression "A or B" or "at least one of A and / or B" may include A, may include B, or may include both A and B.

[0031] The expressions used in the various embodiments of the present invention (such as "first," "second," etc.) may modify various constituent elements in the various embodiments, but do not limit the corresponding constituent elements. For example, the above expressions do not limit the order and / or importance of the elements. The above expressions are only used for the purpose of distinguishing one element from other elements. For example, a first user device and a second user device refer to different user devices, although both are user devices. For example, a first element may be referred to as a second element without departing from the scope of the various embodiments of the present invention, and similarly, a second element may also be referred to as a first element.

[0032] It should be noted that if a description is made of "connecting" one component to another, then the first component can be directly connected to the second component, and a third component can be "connected" between the first and second components. Conversely, when a component is "directly connected" to another component, it can be understood that there is no third component between the first and second components.

[0033] The terminology used in the various embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to limit the various embodiments of the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which the various embodiments of the invention pertain. The terms (such as those defined in a generally used dictionary) are to be interpreted as having the same meaning as in the context of the relevant technical field and are not to be interpreted as having an idealized or overly formal meaning, unless clearly defined in the various embodiments of the invention.

[0034] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0035] Example

[0036] The conversion circuit of a DC high-voltage Hall sensor suffers from high temperature drift, poor accuracy, and high power consumption. Therefore, this embodiment provides a floating current output circuit to replace the DC voltage Hall sensor, specifically as follows: Figure 3 As shown. The floating ground current output circuit provided in this embodiment of the invention is combined with a conventional electromagnetic / photoelectric / modulation / demodulation isolation circuit, thereby replacing the DC high-voltage Hall sensor, and has the advantages of low temperature drift, high accuracy, and low power consumption.

[0037] The floating ground current output circuit provided in this embodiment of the invention is based on the virtual short and virtual open principle of operational amplifiers. It converts bidirectional DC voltage into bidirectional DC current output through resistors, achieving high detection accuracy within the 0.1% error range. Finally, it uses transistors to amplify the current output.

[0038] Specifically, such as Figure 4As shown, the floating ground current output circuit provided in this embodiment of the invention comprises operational amplifiers, resistors, transistors, and other components. The output OUT of the conventional isolation circuit is connected to one end of resistor R27. The other end of resistor R27 is connected to the non-inverting input of operational amplifier N9A and one end of resistor R28. The other end of resistor R28 is connected to one end of resistor R29. The common connection of resistors R28 and R29 serves as the current output terminal L(G) of the floating ground current output circuit. The other end of resistor R29 is connected to the inverting input of operational amplifier N9A and the internal floating ground plane SGND of the conventional isolation circuit (independent of the power supply VCC). The positive power supply terminal of operational amplifier N9A is connected to the positive power supply output terminal + of the conventional isolation circuit. VCC, the negative power supply terminal of operational amplifier N9A, is connected to the negative power supply output terminal -VCC of the conventional isolation circuit. The output terminal of operational amplifier N9A is connected to the base of transistor V8 and the base of transistor V9. The collector of transistor V8 serves as the positive power supply terminal of the floating ground current output circuit. The emitter of transistor V8 is connected to the emitter of transistor V9. The common connection terminal of the emitters of transistor V8 and transistor V9 is connected to one end of resistor R30. The other end of resistor R30 is connected to the internal floating ground plane SGND of the conventional isolation circuit. The collector of transistor V9 serves as the negative power supply terminal of the floating ground current output circuit.

[0039] In this embodiment of the invention, Figure 4 The values ​​of R27 (39KΩ), R28 (39KΩ), and R29 (20KΩ) are provided for illustrative purposes only and are not intended to limit the application of these values. It should be noted that resistor R29 is less than 100 ohms, while resistors R27 and R28 are greater than 2K ohms, and their values ​​are at least 1000 times that of resistor R29 to ensure output accuracy.

[0040] The working principle of the floating ground current output circuit provided in this embodiment of the invention is as follows:

[0041] The front-end conventional electromagnetic / photoelectric / modulation / demodulation isolation circuit generates a DC 1V signal by referencing the internal floating ground plane SGND (which is independent of the power supply VCC). That is, the front-end conventional isolation circuit outputs a 1V DC voltage signal. Due to the virtual short of the op-amp, the voltage across resistor R29 is the same as the voltage across resistor R28. Due to the virtual open of the op-amp, the voltage across resistor R27 generates a current that flows through resistor R28, producing a DC -1V signal with the opposite voltage drop across resistor R27. Therefore, the current generated across resistor R29 is -50mA.

[0042] The front-end conventional electromagnetic / photoelectric / modulation / demodulation isolation circuit generates a DC -1V signal by referencing the internal floating ground plane SGND. This means the front-end conventional isolation circuit outputs a -1V DC voltage signal. Due to the op-amp's virtual short, the voltage across resistor R29 is the same as the voltage across resistor R28. Due to the op-amp's virtual open, the voltage across resistor R27 generates a current flowing through resistor R28, producing a DC 1V signal with the opposite voltage drop across R27. Therefore, a +50mA current is generated across resistor R29. The output current is connected to the external power supply VCC reference ground through a sampling resistor to achieve detection; the wiring method is the same as for a Hall sensor.

[0043] Since the operational amplifier has a limited output current capability, typically 10mA, this embodiment of the invention uses transistors V8 and V9 to amplify the output current to ±50mA. Transistor V8 is used for positive current amplification, and transistor V9 is used for negative current amplification.

[0044] It should be noted that the power supply connected to the operational amplifier in the embodiments of the present invention can be an external power supply, and the power supply connected to the collector of the downstream current-amplifying transistor is an external ±VCC power supply.

[0045] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A floating current output circuit that replaces a DC voltage Hall sensor, characterized in that, The floating ground current output circuit adopts the operational amplifier virtual short and operational amplifier virtual open principles, converts bidirectional DC voltage into bidirectional DC current output through resistors, and amplifies the current output through transistors; the floating ground current output circuit includes an operational amplifier, resistors A, B, C, and D, transistors A and B; In this circuit, one end of resistor A is connected to the output signal terminal of the front-end isolation circuit, the other end of resistor A is connected to the non-inverting input terminal of the operational amplifier and one end of resistor B, the other end of resistor B is connected to one end of resistor C, the common connection terminal of resistors B and C serves as the current output terminal of the floating ground current output circuit, the other end of resistor C is connected to the inverting input terminal of the operational amplifier and the internal floating ground plane of the front-end isolation circuit, the output terminal of the operational amplifier is connected to the base of transistor A and the base of transistor B, the collector of transistor A serves as the positive power supply terminal of the floating ground current output circuit, the emitter of transistor A is connected to the emitter of transistor B, the common connection terminal of the emitters of transistor A and B is connected to one end of resistor D, the other end of resistor D is connected to the internal floating ground plane of the front-end isolation circuit, and the collector of transistor B serves as the negative power supply terminal of the floating ground current output circuit.

2. The floating current output circuit for replacing a DC voltage Hall sensor according to claim 1, characterized in that, The operational amplifier is connected to an external power source.

3. The floating current output circuit for replacing a DC voltage Hall sensor according to claim 1, characterized in that, The positive and negative power supply terminals of the floating ground current output circuit are connected to external power sources.

4. The floating current output circuit for replacing a DC voltage Hall sensor according to claim 1, characterized in that, The current output terminal of the floating ground current output circuit can be connected to the external power supply reference ground through a sampling resistor to achieve detection.

5. A floating current output circuit for replacing a DC voltage Hall sensor according to claim 1, characterized in that, The front-end isolation circuit can generate a ±1V DC voltage signal by referencing the internal floating ground plane.

6. A floating current output circuit for replacing a DC voltage Hall sensor according to claim 5, characterized in that, The floating ground current output circuit outputs a current of ±50mA.

7. A floating current output circuit for replacing a DC voltage Hall sensor according to any one of claims 1-6, characterized in that, The transistor A is used for forward current amplification; The transistor B is used for negative current amplification.

8. The operating method of the floating ground current output circuit according to any one of claims 1-7, characterized in that, include: A 1V DC voltage signal is generated by referencing the internal floating ground plane through the front-end isolation circuit. Due to the virtual short of the op-amp, the voltage across resistor C is the same as the voltage across resistor B. Due to the virtual open of the op-amp, the voltage across resistor A generates a current that flows through resistor B. The voltage across resistor B is opposite to the voltage drop across resistor A, which is a -1V DC voltage signal. The current across resistor C is -50mA.

9. The working method according to claim 8, characterized in that, Also includes: The front-end isolation short-circuit reference internal floating ground plane generates a -1V DC voltage signal. Due to the virtual short of the op-amp, the voltage across resistor C is the same as the voltage across resistor B. Due to the virtual open of the op-amp, the voltage across resistor A generates a current that flows through resistor B. The voltage across resistor B is opposite to the voltage drop across resistor A, which is a 1V DC voltage signal. The current across resistor C is +50mA.

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