Isolated current detector based on bus communication

Abstract

The utility model relates to the technical field of current detectors, and particularly discloses an isolated current detector based on bus communication, which comprises a detector body. The detector body is provided with a current isolation circuit, a protection sampling circuit, a current amplification circuit, an RC filter circuit, a reference voltage generation circuit, a main control circuit, a two-bus communication circuit, a DCDC step-down circuit and an LDO voltage stabilizing circuit, and the protection sampling circuit is electrically connected with the current isolation circuit and the current amplification circuit. The RC filter circuit is electrically connected with the current amplification circuit and the main control circuit, and the two-bus communication circuit, the DCDC step-down circuit and the LDO voltage stabilizing circuit are electrically connected with the main control circuit. According to the utility model, internal and external currents are isolated by arranging the current isolation circuit, and current signals output by the external current transformer can be accessed without polarity, so that construction wiring is facilitated, and on-site rapid installation is facilitated.

Description

TECHNICAL FIELD

[0001] The utility model relates to current detector technical field, especially a kind of isolated current detector based on bus communication. BACKGROUND

[0002] Current detector is used for the real-time detection of fire-fighting equipment power supply, the current state of fire-fighting equipment power supply is monitored by detection, when overcurrent overload fault occurs in the working power supply of fire-fighting equipment, alarm signal is generated and delivered to host computer, the current state of fire-fighting equipment power supply is monitored in real time, and centralized display is carried out, so that the crisis situation that fire-fighting equipment power supply fails and causes fire-fighting equipment to work normally is effectively avoided.The current detector has the following shortcomings:

[0003] 1: no isolation with external current, when external mutual inductor is connected to ground, serious current leakage will be caused, current detector works under 24V safe voltage, 0-5A current is collected at power frequency, and the traditional current detector directly samples the current through on-board 0.05R resistance and sends it to MCU master control for processing, but one of the output current terminals of some mutual inductors is connected to ground to prevent high voltage line from being induced on the mutual inductor line, which will cause harm, the low voltage inside the current detector forms another current loop through 0.05R collection resistance to ground, which will greatly harm the internal devices of the current detector.

[0004] 2: external mutual inductor has no mutual isolation, whether the mutual inductor is grounded will also affect each other, and the common ground terminal also needs to be connected according to the line sequence when wiring, which is not convenient for on-site rapid installation. UTILITY MODEL CONTENTS

[0005] The utility model solves the technical problem, in view of the above-mentioned defects of prior art, provide a kind of isolated current detector based on bus communication, solve the low-cost isolated acquisition problem of key signal in fire-fighting field, the isolation of internal and external current is carried out by setting current isolation circuit, and the current signal output by external current mutual inductor can be accessed without polarity, which is convenient for construction wiring and is conducive to on-site rapid installation.

[0006] To solve the above technical problems, the technical scheme of the utility model is:

[0007] A kind of isolation type current detector based on bus communication, including detector body, current isolation circuit, protection sampling circuit, current amplification circuit, RC filter circuit, reference voltage generation circuit, main control circuit, two bus communication circuits, DCDC voltage reduction circuit and LDO voltage stabilizing circuit are arranged on the detector body, the protection sampling circuit is electrically connected with the current isolation circuit and current amplification circuit respectively, the RC filter circuit is electrically connected with the current amplification circuit and main control circuit respectively, the two bus communication circuits, DCDC voltage reduction circuit and LDO voltage stabilizing circuit are electrically connected with the main control circuit.

[0008] Preferably, the main control circuit includes single-chip microcomputer chip U1, crystal oscillator Y1, inductor L1, light touch switch S1, resistance R8, resistance R9, capacitor C1 and capacitor C2, the crystal oscillator Y1, inductor L1, light touch switch S1, resistance R8, resistance R9, capacitor C1 and capacitor C2 are connected with the single-chip microcomputer chip U1.

[0009] Preferably, the current isolation circuit includes phase A current isolator CT1, phase B current isolator CT2 and phase C current isolator CT3, the protection sampling circuit includes TVS tube ZD1, TVS tube ZD2, TVS tube ZD3, sampling circuit R6, sampling resistance R15, sampling resistance R20, ground resistance R1, ground resistance R10 and ground resistance R16, the current amplification circuit includes operational amplifier U2A, operational amplifier U2B, operational amplifier U2C, resistance R2, resistance R3, resistance R12, resistance R13, resistance R17 and resistance R18, the RC filter circuit includes resistance R4, capacitor C3, capacitor C4, capacitor C8, capacitor C9, resistance R14, capacitor C10, capacitor C11 and resistance R19, the TVS tube ZD1 is connected with the phase A current isolator CT1, resistance R1, resistance R2 and resistance R6 respectively, the operational amplifier U2A is connected with the resistance R2, resistance R3, resistance R4 and capacitor C3 respectively, the resistance R4 and capacitor C4 are connected with the tenth pin of the single-chip microcomputer chip U1, the TVS tube ZD2 is connected with the phase B current isolator CT2, resistance R10, resistance R12 and resistance R15 respectively, the operational amplifier U2B is connected with the resistance R12, resistance R13, resistance R14 and capacitor C8 respectively, the resistance R1 and capacitor C9 are connected with the nineteenth pin of the single-chip microcomputer chip U1, the TVS tube ZD1 is connected with the phase C current isolator CT3, resistance R16, resistance R20 and resistance R17 respectively, the operational amplifier U2C is connected with the resistance R17, resistance R18, resistance R9 and capacitor C10 respectively, the resistance R19 and capacitor C10 are connected with the seventeenth pin of the single-chip microcomputer chip U1.

[0010] Preferably, the reference voltage generating circuit comprises an operational amplifier U2D, an inductor L3, a resistor R25, a resistor R26, a resistor R27, a resistor R28, a resistor R29, a capacitor C15, a capacitor C17, a capacitor C18, a capacitor C19, a capacitor C20, a capacitor C21 and a capacitor C26, the inductor L3 and the capacitor C18 are connected with the resistor R25, the operational amplifier U2D is connected with the resistor R25, the resistor R26, the resistor R28, the resistor R29, the capacitor C15, the capacitor C19 and the capacitor C26 respectively, and the resistor R27 is connected with the resistor R26, the capacitor C17, the capacitor C20, the capacitor C21 and the eighteenth pin of the single-chip microcomputer chip U1 respectively.

[0011] Preferably, the two-bus communication circuit comprises a slave communication chip U3, a fuse F1 and a voltage stabilizing tube T1, and the slave communication chip U3 is connected with the single-chip microcomputer chip U1, the fuse F1 and the voltage stabilizing tube T1 respectively.

[0012] Preferably, the DCDC voltage reduction circuit comprises a voltage reduction chip U4, a resistor R21, a resistor R22, a resistor R23, a resistor R24, a capacitor C12, a capacitor C13, a capacitor C14, a diode D2 and an inductor L2, the voltage reduction chip U4 is connected with the resistor R21, the resistor R22, the resistor R23, the resistor R24, the capacitor C12, the capacitor C13, the capacitor C14, the diode D2 and the inductor L2 respectively, and the resistor R22 and the inductor L2 are connected with the single-chip microcomputer chip U1.

[0013] Preferably, the LDO voltage stabilizing circuit comprises a power conversion chip U5, a capacitor C22, a capacitor C23, a capacitor C24, a capacitor C25, a capacitor C27 and a capacitor C28, and the power conversion chip U5 is connected with the single-chip microcomputer chip U1, the capacitor C22, the capacitor C23, the capacitor C24, the capacitor C25, the capacitor C27 and the capacitor C28 respectively.

[0014] Preferably, a plurality of external signal interfaces are further arranged on the detector body, the external signal interfaces comprise an interface J1, an interface J2, an interface J3, an interface J4 and an interface J5, the interface J4 is connected with the A-phase current isolator CT1, the B-phase current isolator CT2 and the C-phase current isolator CT3 respectively, and the interface J1, the interface J2, the interface J3 and the interface J5 are connected with the single-chip microcomputer chip U1.

[0015] The utility model provides a kind of isolated current detector based on bus communication, with following beneficial effects: the protective sampling circuit in the isolated current detector is electrically connected with current isolation circuit and current amplification circuit respectively, RC filter circuit is electrically connected with current amplification circuit and main control circuit respectively, two bus communication circuits, DCDC voltage reduction circuit and LDO voltage stabilizing circuit are electrically connected with main control circuit, the current isolation circuit is mainly to convert the rated input 5A current of external mutual inductor into 2.5mA micro current according to 2000:1 transformation ratio, protective sampling circuit is mainly to convert input current signal into voltage signal, amplification circuit is to multiply the small signal after isolation, AD sampling identification is facilitated, RC filter circuit is to send the signal after amplification to the AD sampling port sampling of main control circuit by RC conditioning, main control circuit samples and analyzes signal, two bus communication circuits are the circuit that communication and power supply are concentrated to a bus, wiring installation is facilitated;The isolation of internal and external currents is carried out by setting current isolation circuit, when high voltage surge or output line is connected to ground by external mutual inductor induction, the stable work of the internal circuit of detector body is not influenced, and the current signal output by external current mutual inductor can be accessed without polarity, facilitate construction wiring, be conducive to on-site rapid installation. BRIEF DESCRIPTION OF DRAWINGS

[0016] Fig. 1 It is the structural schematic diagram of the utility model;

[0017] Fig. 2 It is the circuit schematic diagram of the utility model;

[0018] In the drawing, 1-probe body, 2-external signal interface. DETAILED DESCRIPTION

[0019] The specific embodiments of the utility model are further explained in combination with the drawings. It needs to be explained here that the description of these embodiments is used to help understanding the utility model, but does not constitute the limitation to the utility model. In addition, the technical features involved in each embodiment of the utility model described below can be combined mutually as long as they do not conflict with each other.

[0020] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0021] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0022] like Figs. 1-2 As shown, the bus-communication-based isolated current detector includes a detector body 1. The detector body 1 is equipped with a current isolation circuit, a protection sampling circuit, a current amplification circuit, an RC filter circuit, a reference voltage generation circuit, a main control circuit, a two-bus communication circuit, a DC-DC step-down circuit, and an LDO voltage regulator circuit. The protection sampling circuit is electrically connected to the current isolation circuit and the current amplification circuit. The RC filter circuit is electrically connected to the current amplification circuit and the main control circuit. The two-bus communication circuit, the DC-DC step-down circuit, and the LDO voltage regulator circuit are all electrically connected to the main control circuit. It can be understood that this isolated current detector, through real-time measurement and judgment of the power supply of fire-fighting equipment, can accurately determine fault information when the monitored fire-fighting equipment power supply experiences overload, overcurrent, or other faults, and upload the fault information to the monitor via the two-bus communication circuit, achieving real-time monitoring of the fire-fighting equipment power supply. This isolated current detector solves the problem of low-cost isolation and acquisition of key signals in the fire-fighting field, and improves the overall technical level of the monitoring system.

[0023] Specifically, the main control circuit includes a microcontroller chip U1, a crystal oscillator Y1, an inductor L1, a tactile switch S1, resistors R8 and R9, and capacitors C1 and C2. The crystal oscillator Y1, inductor L1, tactile switch S1, resistors R8 and R9, and capacitors C1 and C2 are all connected to the microcontroller chip U1. It is understood that the microcontroller chip U1 uses an STM32030R8T6 chip, which can perform real-time monitoring and detection, with a sampling frequency of 100 times / second and a fault alarm time of less than 20 seconds.

[0024] Specifically, the current isolation circuit includes an A-phase current isolator CT1, a B-phase current isolator CT2, and a C-phase current isolator CT3, the protection sampling circuit includes TVS tubes ZD1, ZD2, and ZD3, a sampling circuit R6, sampling resistors R15 and R20, grounding resistors R1, R10, and R16, the current amplification circuit includes operational amplifiers U2A, U2B, and U2C, resistors R2, R3, R12, R13, R17, and R18, the RC filter circuit includes resistors R4 and R14 and capacitors C3, C4, C8, C9, C10, and C11, and resistor R19, the TVS tube ZD1 is connected with the A-phase current isolator CT1, resistor R1, resistor R2, and resistor R6, the operational amplifier U2A is connected with resistor R2, resistor R3, resistor R4, and capacitor C3, resistor R4 and capacitor C4 are connected with the tenth pin of the single-chip microcomputer chip U1, the TVS tube ZD2 is connected with the B-phase current isolator CT2, resistor R10, resistor R12, and resistor R15, the operational amplifier U2B is connected with resistor R12, resistor R13, resistor R14, and capacitor C8, resistor R14 and capacitor C9 are connected with the nineteenth pin of the single-chip microcomputer chip U1, the TVS tube ZD1 is connected with the C-phase current isolator CT3, resistor R16, resistor R20, and resistor R17, the operational amplifier U2C is connected with resistor R17, resistor R18, resistor R9, and capacitor C10, resistor R19 and capacitor C10 are connected with the seventeenth pin of the single-chip microcomputer chip U1. It can be understood that the current isolation circuit uses low-cost linear on-board micro current isolators to isolate internal and external currents, and the linearity is 0.2% in the 0-20A current range, which is very good. In addition, the on-board micro current isolator has a 3000V surge impact protection capability, which does not affect the stable operation of the internal circuit of the detector when a high-voltage surge is induced by an external current transformer or the output line is connected to ground. In addition, the current signal output by the external current transformer can be connected without polarity, which is convenient for construction; the protection sampling circuit uses a TVS tube to convert the voltage value of the incoming current into a voltage value within 6V to prevent damage to the operational amplifier and control circuit, which is a two-level protection to ensure the stable operation of the sampling circuit; in this circuit, ZD1, ZD2, and ZD3 are embedded diodes that control the voltage within a certain range, R6, R15, and R20 are sampling resistors that convert the current signal into a voltage signal, and R1, R10, and R16 provide a primary stable end to ensure that the collected current value is zero when the current end is suspended without connecting the current.

[0025] It can be understood that the current amplification circuit uses an operational amplifier to amplify the signal, and the amplification factor is 33 times (R3 / R2). R2 and R3, together with R1 above, act on the voltage values of the reference voltage 1.65 (3.3 / 2) and the input signal, mainly for biasing, so that the output voltage value of the operational amplifier is within the range supported by the operational amplifier (also related to the range of input signal voltage values), especially in the case of single power supply operation of the operational amplifier.

[0026] In particular, the reference voltage generating circuit includes an operational amplifier U2D, an inductor L3, a resistor R25, a resistor R26, a resistor R27, a resistor R28, a resistor R29, a capacitor C15, a capacitor C17, a capacitor C18, a capacitor C19, a capacitor C20, a capacitor C21 and a capacitor C26. The inductor L3 and the capacitor C18 are connected with the resistor R25. The operational amplifier U2D is connected with the resistor R25, the resistor R26, the resistor R28, the resistor R29, the capacitor C15, the capacitor C19 and the capacitor C26 respectively. The resistor R27 is connected with the resistor R26, the capacitor C17, the capacitor C20, the capacitor C21 and the eighteenth pin of the single-chip microcomputer chip U1 respectively. It can be understood that the R25 and R26 voltage dividing circuit constitutes a standard reference voltage, and R29 is a load. Since an integrated operational amplifier is used, the open-loop amplification factor of the operational amplifier is large enough, and a deep negative feedback is formed by the load. According to the virtual short characteristics of the operational amplifier, the voltages of the 12th pin and the 13th pin are equal. According to the voltage division principle, a stable voltage can be obtained at the 12th pin. Since the voltages of the 12th pin and the 13th pin are equal, a stable voltage can also be maintained at the 13th pin. Therefore, the voltage output through the 14th pin is also constant, thus forming a reference voltage source.

[0027] In particular, the two-bus communication circuit includes a slave communication chip U3, a fuse F1 and a voltage stabilizing tube T1. The slave communication chip U3 is connected with the single-chip microcomputer chip U1, the fuse F1 and the voltage stabilizing tube T1 respectively. It can be understood that the slave communication chip U3 uses a PB300 chip, which is a slave communication chip of two-bus technology. It uses voltage transmission and current signal return mode to provide high communication anti-interference ability, and ensures the reliable and stable operation of the system in various electromagnetic environments.

[0028] In particular, the DCDC step-down circuit includes a step-down chip U4, a resistor R21, a resistor R22, a resistor R23, a resistor R24, a capacitor C12, a capacitor C13, a capacitor C14, a diode D2 and an inductor L2. The step-down chip U4 is connected with the resistor R21, the resistor R22, the resistor R23, the resistor R24, the capacitor C12, the capacitor C13, the capacitor C14, the diode D2 and the inductor L2 respectively. The resistor R22 and the inductor L2 are connected with the single-chip microcomputer chip U1. It can be understood that the step-down chip U4 uses an MP2451 chip to reduce the voltage to 5V.

[0029] Specifically, the LDO voltage stabilizing circuit comprises a power conversion chip U5, capacitors C22, C23, C24, C25, C27 and C28, and the power conversion chip U5 is connected with the single-chip microcomputer chip U1, capacitors C22, C23, C24, C25, C27 and C28 respectively.

[0030] Specifically, the detector body is further provided with a plurality of external signal interfaces 2, the external signal interfaces 2 comprising interfaces J1, J2, J3, J4 and J5, the interface J4 being connected with the A-phase current isolator CT1, B-phase current isolator CT2 and C-phase current isolator CT3 respectively, and the interfaces J1, J2, J3 and J5 being connected with the single-chip microcomputer chip U1.

[0031] It can be understood that the current isolation circuit mainly converts the 5A current input by the external mutual inductor into a 2.5mA micro current according to a 2000:1 transformation ratio; the protection sampling circuit mainly converts the input current signal into a voltage signal; the amplification circuit is used for amplifying the small signal after isolation by multiple times, facilitating AD sampling and identification; the RC filter circuit is used for sending the signal after the RC conditioning circuit to the AD sampling port of the single-chip microcomputer chip U1 for sampling; the main control circuit adopts a high-performance 32-bit ARM processor to sample and analyze the signal; the two-bus communication circuit is a circuit for concentrating communication and power supply on one bus, facilitating wiring and installation; the DCDC voltage reduction circuit is used for reducing the 24V voltage from the two-bus to 5V, and the LDO voltage stabilizing circuit is used for stabilizing the 5V voltage to 3.3V for the main control circuit.

[0032] It can be understood that the utility model discloses reasonable design, unique structure, and has the following advantages in actual application process: 1, internally with 3KV electric isolator, and the isolator has the characteristics of low cost and good linear calibration degree, 2, adopt non-polarity signal two bus, and facilitate construction wiring.

[0033] The embodiments of the utility model are described in detail in combination with the drawings, but the utility model is not limited to the described embodiments. For those skilled in the art, various changes, modifications, replacements and modifications can be made to these embodiments without departing from the principles and spirits of the utility model, and still fall within the protection scope of the utility model.

Claims

1. An isolated current probe based on bus communication, comprising a probe body, characterized in that: The probe body is provided with a current isolation circuit, a protection sampling circuit, a current amplification circuit, an RC filter circuit, a reference voltage generating circuit, a main control circuit, a two-bus communication circuit, a DCDC voltage reduction circuit and an LDO voltage stabilization circuit, the protection sampling circuit is electrically connected with the current isolation circuit and the current amplification circuit respectively, the RC filter circuit is electrically connected with the current amplification circuit and the main control circuit respectively, and the two-bus communication circuit, the DCDC voltage reduction circuit and the LDO voltage stabilization circuit are electrically connected with the main control circuit.

2. The isolated current probe based on bus communication according to claim 1, characterized in that: The main control circuit comprises a single-chip microcomputer chip U1, a crystal oscillator Y1, an inductor L1, a light touch switch S1, a resistor R8, a resistor R9, a capacitor C1 and a capacitor C2, and the crystal oscillator Y1, the inductor L1, the light touch switch S1, the resistor R8, the resistor R9, the capacitor C1 and the capacitor C2 are connected with the single-chip microcomputer chip U1.

3. The isolated current probe based on bus communication according to claim 2, characterized in that: The current isolation circuit comprises an A-phase current isolator CT1, a B-phase current isolator CT2 and a C-phase current isolator CT3, the protection sampling circuit comprises TVS tubes ZD1, ZD2 and ZD3, a sampling circuit R6, sampling resistors R15 and R20, ground resistors R1, R10 and R16, the current amplification circuit comprises operational amplifiers U2A, U2B and U2C, resistors R2, R3, R12, R13, R17 and R18, the RC filter circuit comprises resistors R4, C3, C4, C8, C9, R14, C10, C11 and R19, the TVS tube ZD1 is connected with the A-phase current isolator CT1, resistors R1, R2 and R6 respectively, the operational amplifier U2A is connected with resistors R2, R3, R4 and C3 respectively, the resistor R4 and the capacitor C4 are connected with the tenth pin of the single-chip microcomputer chip U1, the TVS tube ZD2 is connected with the B-phase current isolator CT2, resistors R10, R12 and R15 respectively, the operational amplifier U2B is connected with resistors R12, R13, R14 and C8 respectively, the resistor R14 and the capacitor C9 are connected with the nineteenth pin of the single-chip microcomputer chip U1, the TVS tube ZD1 is connected with the C-phase current isolator CT3, resistors R16, R20 and R17 respectively, the operational amplifier U2C is connected with resistors R17, R18, R9 and C10 respectively, and the resistor R19 and the capacitor C10 are connected with the seventeenth pin of the single-chip microcomputer chip U1.

4. The isolated current probe based on bus communication according to claim 2, characterized in that: The reference voltage generating circuit includes an operational amplifier U2D, an inductor L3, a resistor R25, a resistor R26, a resistor R27, a resistor R28, a resistor R29, a capacitor C15, a capacitor C17, a capacitor C18, a capacitor C19, a capacitor C20, a capacitor C21 and a capacitor C26, the inductor L3 and the capacitor C18 are connected with the resistor R25, the operational amplifier U2D is connected with the resistor R25, the resistor R26, the resistor R28, the resistor R29, the capacitor C15, the capacitor C19 and the capacitor C26 respectively, the resistor R27 is connected with the resistor R26, the capacitor C17, the capacitor C20, the capacitor C21 and the eighteenth pin of the single-chip microcomputer chip U1 respectively.

5. The isolated current probe based on bus communication according to claim 2, characterized in that: The two-bus communication circuit includes a slave station communication chip U3, a fuse F1 and a voltage stabilizing tube T1, the slave station communication chip U3 is connected with the single-chip microcomputer chip U1, the fuse F1 and the voltage stabilizing tube T1 respectively.

6. The isolated current probe based on bus communication according to claim 2, characterized in that: The DCDC voltage reduction circuit includes a voltage reduction chip U4, a resistor R21, a resistor R22, a resistor R23, a resistor R24, a capacitor C12, a capacitor C13, a capacitor C14, a diode D2 and an inductor L2, the voltage reduction chip U4 is connected with the resistor R21, the resistor R22, the resistor R23, the resistor R24, the capacitor C12, the capacitor C13, the capacitor C14, the diode D2 and the inductor L2 respectively, the resistor R22 and the inductor L2 are connected with the single-chip microcomputer chip U1.

7. The isolated current probe based on bus communication according to claim 2, characterized in that: The LDO voltage stabilizing circuit includes a power conversion chip U5, a capacitor C22, a capacitor C23, a capacitor C24, a capacitor C25, a capacitor C27 and a capacitor C28, the power conversion chip U5 is connected with the single-chip microcomputer chip U1, the capacitor C22, the capacitor C23, the capacitor C24, the capacitor C25, the capacitor C27 and the capacitor C28 respectively.

8. The isolated current probe based on bus communication according to claim 3, characterized in that: The detector body is further provided with a plurality of external signal interfaces, the external signal interfaces include an interface J1, an interface J2, an interface J3, an interface J4 and an interface J5, the interface J4 is connected with the A-phase current isolator CT1, the B-phase current isolator CT2 and the C-phase current isolator CT3 respectively, the interface J1, the interface J2, the interface J3 and the interface J5 are connected with the single-chip microcomputer chip U1.

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