CN114914889A - Overcurrent and short-circuit protection method, circuit and proximity sensor - Google Patents
Overcurrent and short-circuit protection method, circuit and proximity sensor Download PDFInfo
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- CN114914889A CN114914889A CN202210607160.7A CN202210607160A CN114914889A CN 114914889 A CN114914889 A CN 114914889A CN 202210607160 A CN202210607160 A CN 202210607160A CN 114914889 A CN114914889 A CN 114914889A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/20—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for electronic equipment
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/02—Details
- H02H3/04—Details with warning or supervision in addition to disconnection, e.g. for indicating that protective apparatus has functioned
- H02H3/042—Details with warning or supervision in addition to disconnection, e.g. for indicating that protective apparatus has functioned combined with means for locating the fault
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/02—Details
- H02H3/06—Details with automatic reconnection
- H02H3/066—Reconnection being a consequence of eliminating the fault which caused disconnection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
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Abstract
The application discloses an overcurrent and short-circuit protection method, an overcurrent and short-circuit protection circuit and a proximity sensor, wherein the method is applied to the overcurrent and short-circuit protection circuit in the proximity sensor and comprises a control unit, a detection unit and a load unit, and the method comprises the following steps: when the load of the load unit is increased and the current value of the detection unit reaches a preset current threshold value, the control unit controls the output unit in the proximity sensor to be turned off; when the current value of the detection unit is 0, the control unit controls the output unit to be conducted; the output unit is used for outputting detection result information based on a detection signal of a detected target of the proximity sensor; repeating the steps until the load of the load unit is increased, and the current value of the detection unit is reduced to be below a preset current threshold value and is not 0; when the circuit is in overcurrent or short circuit, the working state of the circuit can be intuitively reflected through corresponding output detection result information, the circuit does not depend on temperature during short circuit and overcurrent protection, and the output current capability of the product is not influenced.
Description
Technical Field
The invention relates to the technical field of sensors, in particular to an overcurrent and short-circuit protection method, an overcurrent and short-circuit protection circuit and a proximity sensor.
Background
The proximity sensor is a generic term for a sensor for detecting a detection object without touching the detection object, and is capable of converting movement information and presence information of the detection object into an electrical signal, instead of a contact detection method such as a limit switch. The proximity sensor has the advantages that due to the product characteristics, the industry standard specifies that the product can be automatically protected when in overcurrent and short circuit, and can be automatically recovered without damage after the overcurrent and short circuit are eliminated.
At present, the industry mostly uses thermistors, namely self-recovery fuses and IC chips for design. The temperature of the positive thermistor rises sharply along with the increase of current mainly depending on the temperature characteristic of the thermistor, and meanwhile, the resistance value of the resistor increases sharply, so that the purpose of limiting the current is achieved. Alternatively, the output driving circuit and the overcurrent and short-circuit protection circuit are integrated in a chip by using an integrated IC, and most of such chips also adopt a thermal shutdown method.
The heat is increased sharply when the circuit is subjected to overcurrent and short circuit protection, the heat is serious, the resistance value of the thermistor is greatly changed along with the change of the temperature, so that the output current capability is different along with the difference of the temperature, the output current is different in magnitude, the output voltage drop is also large, and the magnitude of the output voltage drop is one of key indexes of product performance; the output voltage is reduced by adopting IC design, but the cost is expensive.
Disclosure of Invention
The application provides an overcurrent and short-circuit protection method, a circuit and a proximity sensor.
In a first aspect, an overcurrent and short-circuit protection method is provided, which is applied to an overcurrent and short-circuit protection circuit in a proximity sensor, wherein the overcurrent and short-circuit protection circuit comprises a control unit, a detection unit and a load unit; the method comprises the following steps:
when the load of the load unit is increased and the current value of the detection unit reaches a preset current threshold, the control unit controls the output unit in the proximity sensor to be turned off; when the current value of the detection unit is 0, the control unit controls the output unit to be conducted; the output unit is used for outputting detection result information based on a detection signal of a detected object of the proximity sensor;
repeating the above steps until the load of the load unit is increased, and the current value of the detection unit is reduced to be below the preset current threshold value and is not 0.
In a second aspect, an overcurrent and short-circuit protection circuit is provided, which is applied to a proximity sensor, the proximity sensor further comprises a power circuit, a processing circuit and an output unit, wherein a first end of the processing circuit is connected with the power circuit;
the overcurrent and short-circuit protection circuit comprises a control unit, a detection unit and a load unit, wherein:
the first end of the control unit is connected with the first end of the detection unit and is connected with the power supply circuit; the second end of the control unit is connected with the signal output end of the processing circuit; the third end of the control unit is connected with the second end of the processing circuit; the fourth end of the control unit and the second end of the detection unit are connected with the first end of the output unit; the fifth end of the control unit is connected with the control end of the output unit; the first end of the load unit is connected with the second end of the output unit; the sixth end of the control unit and the second end of the load unit are grounded;
the power supply module is used for supplying power to the circuit of the proximity sensor;
the processing circuit is used for generating a magnetic field and obtaining a detection signal of a detected target based on the magnetic field;
the output unit is used for outputting detection result information based on the detection signal of the detected target;
the detection unit and the load unit are used for detecting the magnitude of the output current at the output unit; and the control unit is used for controlling the output unit to output corresponding state information when the output unit is in an overcurrent or short-circuit state.
Optionally, the control unit includes resistors R1 to R7, capacitors C1 and C2, a transistor Q3, and an operational amplifier U1; wherein:
one end of the resistor R4, one end of the capacitor C1, one end of the capacitor C2 and an emitter of the triode Q3 are first ends of the control unit; the other end of the capacitor C2 and one end of the resistor R2 are connected with the collector of the triode Q3; the other end of the resistor R2 and one end of the resistor R3 are connected with the negative electrode of the operational amplifier U1;
the other end of the capacitor C1 and one end of the resistor R1 are connected with the base electrode of the triode Q3; the other end of the resistor R1 is a fourth end of the control unit;
one end of the resistor R6 is a second end of the control unit; the other end of the resistor R6 is a fifth end of the control unit;
one end of the resistor R7 and the output end of the operational amplifier U1 are the third end of the control unit; the other end of the resistor R7, the other end of the resistor R4 and one end of the resistor R5 are connected with the anode of the operational amplifier U1;
the other end of the resistor R3 and the other end of the resistor R5 are the sixth end of the control unit.
Optionally, the detection unit includes a detection resistor, and the load unit includes a load resistor.
Optionally, the output unit is a transistor Q1; the first end of the output unit is the base electrode of the triode Q1, the second end of the output unit is the emitter electrode of the triode Q1, and the first end of the output unit is the collector electrode of the triode Q1.
Optionally, the processing circuit further includes an oscillation circuit, a detection circuit, and a shaping circuit, wherein:
the first end of the oscillating circuit, the first end of the detecting circuit and the first end of the shaping circuit are the first end of the processing circuit, and the output end of the shaping circuit is the signal output end of the processing circuit; the second end of the shaping circuit is the second end of the processing circuit; the oscillation circuit, the detection circuit and the shaping circuit are connected in sequence;
the oscillating circuit is used for outputting an oscillating signal to drive the coil to generate the magnetic field;
the detection circuit module is used for detecting a modulation signal in an input signal generated by the detected target in the magnetic field;
and the shaping circuit module is used for filtering the modulation signal to obtain a detection signal of the detected target.
Optionally, the coil is a coreless coil.
Optionally, the coil is formed by twisting a plurality of strands of insulated copper wires to form a strand and then winding the strand.
In a third aspect, there is provided a proximity sensor comprising any of the over-current and short-circuit protection circuits as described in the second aspect above.
Optionally, the proximity sensor further comprises a bobbin and a printed circuit assembly; circuitry in the printed circuit assembly that disposes the proximity sensor;
a bulge matched with one end of the coil framework is designed at one end of the printed circuit assembly and used for being connected with the coil framework; and the other end of the coil framework is used for fixing the coreless coil.
The embodiment of the application provides an overcurrent and short-circuit protection method, a circuit and a proximity sensor, wherein the method is applied to the overcurrent and short-circuit protection circuit in the proximity sensor, the proximity sensor comprises a control unit, a detection unit and a load unit, and the method comprises the following steps: when the load of the load unit is increased and the current value of the detection unit reaches a preset current threshold value, the control unit controls the output unit in the proximity sensor to be turned off; when the current value of the detection unit is 0, the control unit controls the output unit to be conducted; the output unit is used for outputting detection result information based on a detection signal of a detected target of the proximity sensor; repeating the steps until the load of the load unit is increased, and the current value of the detection unit is reduced to be below a preset current threshold value and is not 0; when the circuit is in overcurrent or short circuit, the working state of the circuit can be intuitively reflected through corresponding output detection result information, the overcurrent and short circuit response speed is high, the heating is low, the circuit does not depend on the temperature during short circuit and overcurrent protection, the output current capability of the product is not influenced, and the cost is lower.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments or the background art of the present application, the drawings required to be used in the embodiments or the background art of the present application will be described below.
Fig. 1 is a schematic diagram of a sensor circuit for overcurrent and short-circuit protection based on a thermistor according to an embodiment of the present disclosure;
fig. 2 is a schematic structural diagram of a sensor circuit for performing overcurrent and short-circuit protection based on an integrated IC according to an embodiment of the present disclosure;
fig. 3 is a schematic structural diagram of an overcurrent and short-circuit protection circuit according to an embodiment of the present disclosure;
fig. 4 is a schematic diagram of a sensor circuit according to an embodiment of the present disclosure;
fig. 5 is a schematic flowchart of an overcurrent and short-circuit protection method according to an embodiment of the present disclosure.
Detailed Description
In order to make the technical solutions of the present application better understood, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The terms "first," "second," and the like in the description and claims of the present application and in the above-described drawings are used for distinguishing between different objects and not for describing a particular order. Furthermore, the terms "include" and "have," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus.
Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.
An Integrated Circuit (IC) referred to in the embodiments of the present application is a kind of micro electronic device or component. The transistor, diode, resistance, capacitance and inductance elements and wiring required in a circuit are interconnected together by adopting a certain process, manufactured on a small or a plurality of small semiconductor wafers or medium substrates, and then packaged in a tube shell to form a micro structure with the required circuit function; all the elements are structurally integrated, so that the electronic elements are greatly miniaturized, low in power consumption and high in reliability.
The embodiments of the present application are described below with reference to the drawings.
To illustrate the method in the embodiment of the present application more clearly, two schemes of over-current and short-circuit protection circuits commonly used in proximity sensors are first introduced.
Referring to fig. 1, fig. 1 is a schematic diagram of a circuit structure of a sensor for performing overcurrent and short-circuit protection based on a thermistor according to an embodiment of the present disclosure, where the sensor circuit includes a detection coil, a power circuit, and an oscillation circuit, a detection circuit, and a shaping circuit, which are connected in sequence, and the thermistor, a load, a transistor Q1, and a resistor R5, where the connection relationship is as shown in fig. 1. A detection coil in the sensor circuit generates a magnetic field under the drive of the circuit, senses the distance between a detected object and the detection coil, changes the parameters of the circuit and detects the detected object in a non-contact manner.
Specifically, the oscillating circuit in the sensor circuit may output an oscillating signal of a certain frequency to drive the coil to generate the magnetic field. The detection coil can be formed by copper wires, and under different frequencies, the current flowing through the copper wires gradually tends to the outer surfaces of the copper wires, so that the higher the frequency of the copper wires is, the higher the resistance is, and the distribution of the magnetic field of the coil can be influenced. The detection circuit can detect a modulation signal in an input signal, wherein the input signal is generated by inductance variation of the coil under the action of a detection target; the shaping circuit can filter the modulation signal; the remaining transistor Q3 can detect the filtered signal to determine and output the sensor status, i.e., the detection status of the proximity sensor is indicated by turning on and off.
The proximity sensor shown in fig. 1 uses a positive thermistor, that is, a PTC, to perform overcurrent and short circuit, and mainly depends on the temperature characteristic of the thermistor, and as the current increases, the temperature of the positive thermistor rapidly increases, and at the same time, the resistance value of the resistor rapidly increases, so as to achieve the purpose of limiting the current.
In the scheme, the overcurrent and short-circuit protection heat is increased sharply, the heating is serious, the response speed is slow, Q1 has the risk of being burnt out, and the temperature can influence the load capacity of the product. Because the resistance value of the thermistor greatly changes along with the change of the temperature, the output current capability is different along with the difference of the temperature, the output current is different in size, and meanwhile, the output voltage drop is large.
Referring to fig. 2, fig. 2 is a schematic diagram of a circuit structure of a sensor for performing overcurrent and short-circuit protection based on an integrated IC according to an embodiment of the present disclosure, where the sensor circuit includes a detection coil, a power circuit, and an oscillation circuit, a detection circuit, a shaping circuit, and a dedicated IC, which are connected in sequence, where a connection relationship is as shown in fig. 2, which is similar to the circuit structure shown in fig. 1, and functions of the above circuit modules are not repeated here.
The integrated IC is used in the scheme, the output driving circuit and the over-current and short-circuit protection circuit are integrated in a chip, and the chip mostly adopts a thermal cut-off mode, so that the heat is serious and the price is high.
Referring to fig. 3, fig. 3 is a schematic structural diagram of an over-current and short-circuit protection circuit according to an embodiment of the present disclosure, where the over-current and short-circuit protection circuit can be applied to a proximity sensor to implement over-current and short-circuit protection; the proximity sensor may further include a power circuit, a processing circuit, and an output unit, the first end of the processing circuit being connected to the power circuit. As shown in fig. 3, the over-current and short-circuit protection circuit 300 includes a control unit 310, a detection unit 320 and a load unit 330, wherein:
a first end of the control unit 310 is connected to a first end of the detection unit 320 and to the power supply circuit; a second terminal of the control unit 310 is connected to a signal output terminal of the processing circuit; a third terminal of the control unit 310 is connected to a second terminal of the processing circuit; a fourth end of the control unit 310 and a second end of the detection unit 320 are connected to a first end of the output unit; a fifth terminal of the control unit 310 is connected to the control terminal of the output unit; a first end of the load unit 330 is connected to a second end of the output unit; a sixth terminal of the control unit 310 and a second terminal of the load unit 330 are grounded;
the power module is used for supplying power to the circuit of the proximity sensor;
the processing circuit is used for generating a magnetic field and acquiring a detection signal of a detected target based on the magnetic field;
the output unit is used for outputting detection result information based on the detection signal of the detected target;
the detecting unit 320 and the load unit 330 are configured to detect the magnitude of the output current at the output unit; the control unit 310 is configured to control the output unit to output corresponding state information when the output unit is in an overcurrent or short-circuit state.
In an optional implementation, the processing circuit further includes an oscillation circuit, a detection circuit, and a shaping circuit, wherein:
a first end of the oscillation circuit, a first end of the detection circuit, and a first end of the shaping circuit are first ends of the processing circuit, and an output end of the shaping circuit is a signal output end of the processing circuit; a second terminal of the shaping circuit is a second terminal of the processing circuit; the oscillation circuit, the detection circuit, and the shaping circuit are connected in this order;
the oscillating circuit is used for outputting an oscillating signal to drive the coil to generate the magnetic field;
the detection circuit module is used for detecting a modulation signal in an input signal generated by the detected object in the magnetic field;
the shaping circuit module is used for filtering the modulation signal to obtain a detection signal of the detected target.
Optionally, the processing circuit may be adaptively adjusted and modified based on the type and function of the proximity sensor, which is not limited in this embodiment of the application.
In an alternative embodiment, the coil may be a coreless coil. Generally, an inductive sensor with a magnetic core adopts a coil with the magnetic core, and is combined with a corresponding driving circuit to drive the coil with the magnetic core to generate a magnetic field, and the magnetic field senses the clamping distance of metal at the same time to change the parameters of the driving circuit, so that the aim of detecting the metal in a non-contact manner is fulfilled. The application provides a design method of a coreless coil, the coreless coil suitable for the inductive sensor is designed, a magnetic core structure does not need to be combined, meanwhile, large induction distance detection can be achieved, and sensitivity performance of the coreless inductive sensor is guaranteed.
Specifically, the design method of the coreless coil may include:
acquiring a target oscillation signal frequency of an oscillation circuit in the inductive sensor circuit; calculating the skin depth of the coil according to the target oscillation signal frequency; determining the wire diameter of the coil according to the skin depth; and adjusting and determining target size parameters of the coil through simulation operation based on the wire diameter and the initial design size of the coil.
A no magnetic core coil that reasonable design is arranged in inductance type sensor in this application to avoid the risk that the magnetic core brought to inductance type sensor's design, improve inductance type sensor's interference killing feature, and reduce design cost and development time when selecting the magnetic core.
In an alternative embodiment, the detecting unit 320 may include a detecting resistor, and the load unit 330 may select a load according to a requirement.
In an alternative embodiment, the control unit 310 may include resistors R1-R7, capacitors C1 and C2, a transistor Q3, and an operational amplifier U1. For better illustration, reference may be made to a schematic diagram of a sensor circuit configuration shown in fig. 4. As shown in fig. 4, similar to fig. 1 and fig. 2, the sensor circuit includes a detection coil, a power circuit, and an oscillation circuit, a detection circuit, and a shaping circuit that are connected in sequence, and the connection relationship is correspondingly shown, and reference may be made to the description in the foregoing embodiment, and details are not repeated here.
Further, in the structure shown in fig. 4, the output unit is a transistor Q1; the first terminal of the output unit is the base of the transistor Q1, the second terminal of the output unit is the emitter of the transistor Q1, and the first terminal of the output unit is the collector of the transistor Q1.
Wherein. One end of the resistor R4, one end of the capacitor C1, one end of the capacitor C2, and the emitter of the transistor Q3 are first ends of the control unit; the other end of the capacitor C2 and one end of the resistor R2 are connected to the collector of the transistor Q3; the other end of the resistor R2 and one end of the resistor R3 are connected to the negative electrode of the operational amplifier U1;
the other end of the capacitor C1 and one end of the resistor R1 are connected with the base electrode of the triode Q3; the other end of the resistor R1 is a fourth end of the control unit;
one end of the resistor R6 is a second end of the control unit; the other end of the resistor R6 is a fifth end of the control unit;
one end of the resistor R7 and the output end of the operational amplifier U1 are the third end of the control unit; the other end of the resistor R7, the other end of the resistor R4, and one end of the resistor R5 are connected to the positive electrode of the operational amplifier U1;
the other end of the resistor R3 and the other end of the resistor R5 are the sixth end of the control unit.
Based on the description of the device embodiment, the application also provides an overcurrent and short-circuit protection method. As shown in fig. 5, the method can be applied to an over-current and short-circuit protection circuit in a proximity sensor, where the over-current and short-circuit protection circuit includes a control unit, a detection unit, and a load unit, such as the over-current and short-circuit protection circuit shown in fig. 3; the method comprises the following steps:
501. when the load of the load unit is increased and the current value of the detection unit reaches a preset current threshold value, the control unit controls the output unit in the proximity sensor to be turned off; when the current value of the detection unit is 0, the control unit controls the output unit to be conducted; the output unit is configured to output detection result information based on a detection signal of the target to be detected of the proximity sensor;
502. repeating the above steps until the load of the load unit is increased, and the current value of the detection unit is reduced to be less than the preset current threshold value and is not 0.
The output unit may select a suitable element according to a need, for example, the suitable element includes a diode, a triode, or a buzzer, which can be turned on and off, so as to control the state of the output unit under the conditions of overcurrent and short circuit to visually reflect the state of the circuit, which is not limited in this embodiment of the application.
Specifically, to more clearly illustrate the overcurrent and short-circuit protection method in the present application, the work flow of the overcurrent and short-circuit protection is described as follows by taking fig. 4 as an example: q1 turns on and current begins to flow through the sense resistor and the load. The overcurrent and short-circuit protection circuit in the proximity sensor mainly has 3 working states:
1. when the current flowing through the detection resistor is smaller than the threshold value, Q3 and U1 do not work;
2. as the load decreases, the current flowing through the detection resistor gradually increases. When a set threshold value is reached, Q3 is conducted, the voltage of R3 rises, negative feedback is introduced through an operational amplifier U1, a shaping circuit is locked, Q1 is turned off, and the current flowing through an electrical measuring resistor and a load is reduced to Q;
3. after the current flowing through the detection resistor is reduced to 0, Q1 is conducted again, Q3 and U1 do not work, and the current flows through the detection resistor and the load again; the above steps are repeated until the load is increased and the current is reduced to be lower than the set current threshold.
Therefore, when the current is overlarge or short-circuited, the Q1 is switched between continuous on and off, and the product output indicator lamp continuously flickers as the detection result information; the user can judge that the product is in an overcurrent or short-circuit state through the continuously-flashing indicator lamp.
The capacitors C1 and C2 are used for adjusting the on and off time of the Q1, and can be selected according to requirements.
In the method, the temperature coefficient of the detection resistor is stable, so that the load carrying capacity is stable at different temperatures, and the change of the temperature of the shell cannot occur.
In the embodiment of the application, the proximity sensor uses the resistor to detect the output current at the output driving end, negative feedback is introduced through the discrete component triode and the operational amplifier to construct a circuit shown in fig. 3, the on or off of the output driving circuit is controlled, and the temperature change is not relied on, so that heat cannot be generated during product protection. When overcurrent or short circuit occurs, the pulse type output is realized, so that the function indicating lamp flickers, and the state of the sensor can be obtained more intuitively.
In the embodiment of the application, a plurality of strands of insulated copper wires can be mutually twisted to form a strand, and then the strand is wound to form the coil with a corresponding structure, so that the skin effect and the proximity effect between the coils can be eliminated to a certain extent, the quality factor of the coil is improved, the phenomenon of uneven distribution of current in the wire is weakened, and the magnetic field intensity of the coil is further enhanced.
When the coil with the same size is wound by the single-stranded wire and the multi-stranded wire, the number of turns of the coil wound by the multi-stranded wire is reduced, the inductance is reduced, the magnetic induction wire in unit area is increased, the magnetic field intensity is higher, the electromagnetic induction phenomenon is more severe, and the coil wound by the multi-stranded wire has higher impedance change rate when the same target is detected.
Based on the above description of the embodiment of the coreless coil design method, an embodiment of the present application also discloses a proximity sensor, which includes an over-current and short-circuit protection circuit provided in the embodiment of the present application, such as the over-current and short-circuit protection circuit in the embodiment shown in fig. 3 or fig. 4. Through the overcurrent and short-circuit protection circuit, when overcurrent or short circuit occurs, the working state of the overcurrent and short-circuit protection circuit can be intuitively reflected through corresponding output detection result information, the overcurrent and short-circuit protection circuit does not depend on temperature during short circuit and overcurrent protection, the output current capability of a product is not influenced, and compared with the integrated IC, the cost is saved.
In an alternative embodiment, the proximity sensor further comprises a bobbin and a printed circuit assembly; a circuit in which the proximity sensor is provided in the printed circuit assembly;
one end of the printed circuit assembly is provided with a bulge matched with one end of the coil framework for being connected with the coil framework; the other end of the coil framework is used for fixing the coreless coil.
The proximity sensor uses a non-magnetic core coil, has strong anti-jamming capability and simple structural process, and can achieve positioning and structural matching without a positioning and assembling method in the manufacturing process of a common inductance type sensor with a magnetic core.
The structure of the proximity sensor may also be adaptively adjusted according to needs, which is only illustrated above, and the embodiment of the present application does not limit this.
It can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described apparatuses and modules may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the division of the module is only one logical division, and other divisions may be possible in actual implementation, for example, a plurality of modules or components may be combined or integrated into another system, or some features may be omitted, or not performed. The shown or discussed mutual coupling, direct coupling or communication connection may be an indirect coupling or communication connection of devices or modules through some interfaces, and may be in an electrical, mechanical or other form.
Modules described as separate parts may or may not be physically separate, and parts displayed as modules may or may not be physical modules, may be located in one place, or may be distributed on a plurality of network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment.
In the above embodiments, all or part of the implementation may be realized by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. The procedures or functions according to the embodiments of the present application are wholly or partially generated when the computer program instructions are loaded and executed on a computer. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored on or transmitted over a computer-readable storage medium. The computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center by wire (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)), or wirelessly (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device, such as a server, a data center, etc., that includes one or more of the available media. The usable medium may be a read-only memory (ROM), or a Random Access Memory (RAM), or a magnetic medium, such as a floppy disk, a hard disk, a magnetic tape, a magnetic disk, or an optical medium, such as a Digital Versatile Disk (DVD), or a semiconductor medium, such as a Solid State Disk (SSD).
Claims (10)
1. The over-current and short-circuit protection method is characterized by being applied to an over-current and short-circuit protection circuit in a proximity sensor, wherein the over-current and short-circuit protection circuit comprises a control unit, a detection unit and a load unit; the method comprises the following steps:
when the load of the load unit is increased and the current value of the detection unit reaches a preset current threshold, the control unit controls the output unit in the proximity sensor to be turned off; when the current value of the detection unit is 0, the control unit controls the output unit to be conducted; the output unit is used for outputting detection result information based on a detection signal of a detected object of the proximity sensor;
repeating the above steps until the load of the load unit is increased, and the current value of the detection unit is reduced to be below the preset current threshold value and is not 0.
2. The over-current and short-circuit protection circuit is applied to a proximity sensor, the proximity sensor further comprises a power supply circuit, a processing circuit and an output unit, and a first end of the processing circuit is connected with the power supply circuit;
the overcurrent and short-circuit protection circuit comprises a control unit, a detection unit and a load unit, wherein:
the first end of the control unit is connected with the first end of the detection unit and is connected with the power supply circuit; the second end of the control unit is connected with the signal output end of the processing circuit; the third end of the control unit is connected with the second end of the processing circuit; the fourth end of the control unit and the second end of the detection unit are connected with the first end of the output unit; the fifth end of the control unit is connected with the control end of the output unit; the first end of the load unit is connected with the second end of the output unit; the sixth end of the control unit and the second end of the load unit are grounded;
the power supply module is used for supplying power to the circuit of the proximity sensor;
the processing circuit is used for generating a magnetic field and obtaining a detection signal of a detected target based on the magnetic field;
the output unit is used for outputting detection result information based on the detection signal of the detected target;
the detection unit and the load unit are used for detecting the magnitude of the output current at the output unit; and the control unit is used for controlling the output unit to output corresponding state information when the output unit is in an overcurrent or short-circuit state.
3. The over-current and short-circuit protection circuit according to claim 2, wherein the control unit comprises resistors R1-R7, capacitors C1 and C2, a transistor Q3 and an operational amplifier U1; wherein:
one end of the resistor R4, one end of the capacitor C1, one end of the capacitor C2 and an emitter of the triode Q3 are first ends of the control unit; the other end of the capacitor C2 and one end of the resistor R2 are connected with the collector of the triode Q3; the other end of the resistor R2 and one end of the resistor R3 are connected with the negative electrode of the operational amplifier U1;
the other end of the capacitor C1 and one end of the resistor R1 are connected with the base electrode of the triode Q3; the other end of the resistor R1 is a fourth end of the control unit;
one end of the resistor R6 is a second end of the control unit; the other end of the resistor R6 is a fifth end of the control unit;
one end of the resistor R7 and the output end of the operational amplifier U1 are the third end of the control unit; the other end of the resistor R7, the other end of the resistor R4 and one end of the resistor R5 are connected with the anode of the operational amplifier U1;
the other end of the resistor R3 and the other end of the resistor R5 are the sixth end of the control unit.
4. The over-current and short-circuit protection circuit according to claim 2, wherein the detection unit comprises a detection resistor, and the load unit comprises a load resistor.
5. The over-current and short-circuit protection circuit according to claim 2, wherein the output unit is a transistor Q1; the first end of the output unit is a base electrode of the triode Q1, the second end of the output unit is an emitting electrode of the triode Q1, and the first end of the output unit is a collecting electrode of the triode Q1.
6. The over-current and short-circuit protection circuit according to claim 2, wherein the processing circuit further comprises an oscillating circuit, a detecting circuit and a shaping circuit, wherein:
the first end of the oscillating circuit, the first end of the detecting circuit and the first end of the shaping circuit are the first end of the processing circuit, and the output end of the shaping circuit is the signal output end of the processing circuit; the second end of the shaping circuit is the second end of the processing circuit; the oscillation circuit, the detection circuit and the shaping circuit are connected in sequence;
the oscillating circuit is used for outputting an oscillating signal to drive the coil to generate the magnetic field;
the detection circuit module is used for detecting a modulation signal in an input signal generated by the detected target in the magnetic field;
and the shaping circuit module is used for filtering the modulation signal to obtain a detection signal of the detected target.
7. The overcurrent and short circuit protection circuit of claim 6, wherein said coil is a coreless coil.
8. The overcurrent and short-circuit protection circuit of claim 6, wherein said coil is formed by twisting a plurality of insulated copper wires to form a strand, and winding said strand.
9. A proximity sensor comprising an overcurrent and short-circuit protection circuit according to any one of claims 2 to 8.
10. The proximity sensor of claim 9, further comprising a bobbin and a printed circuit assembly; circuitry in the printed circuit assembly that disposes the proximity sensor;
a bulge matched with one end of the coil framework is designed at one end of the printed circuit assembly and used for being connected with the coil framework; and the other end of the coil framework is used for fixing the coreless coil.
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| CN114914889B (en) | 2023-04-07 |
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