Constant current circuit of load equipment on two fire-fighting buses

Abstract

The utility model discloses a constant current circuit of load equipment on two fire-fighting buses. The constant current circuit comprises a dynamic load, a current limiting circuit, a dynamic current monitoring circuit, a constant current control circuit and a current compensation circuit, the input end of the current limiting circuit is connected with the positive electrode of the fire-fighting two-bus, and the output end is connected with the input end of the dynamic load; the first end of the current compensation circuit is connected with the positive electrode of the fire-fighting two-bus, and the second end is connected with the output end of the dynamic load; the input end of the dynamic current monitoring circuit is connected with the output end of the dynamic load, and the output end of the dynamic current monitoring circuit is connected to the negative electrode of the fire-fighting two-bus; the input end of the constant current control circuit is connected with the output end of the dynamic current monitoring circuit, and the output end of the constant current control circuit is connected to the third end of the current compensation circuit. According to the utility model, the equipment on the bus is provided with the constant current circuit, and when the current is sent at a high level, the total current of other equipment on the bus is stable, so that the host can well identify the current signal from the bus.

Description

Technical Field

[0001] The utility model relates to the technical field of fire protection, in particular to a constant current circuit for load equipment on two fire protection buses. Background Art

[0002] At present, fire protection systems usually use two buses to realize communication and power supply between devices, and the signal and power supply share two cables. This greatly saves application costs and brings great convenience in on-site construction and maintenance. The two-bus technology is widely used in the field of fire protection.

[0003] The two fire protection buses basically communicate in a master-slave manner. The host outputs the digital quantity to be transmitted to the two buses in the form of voltage, and the slave outputs the digital quantity to be transmitted to the two buses in the form of current, realizing the information interaction between the master and the slave. The slave obtains power while obtaining the voltage signal from the bus, realizing the signal and power sharing the bus.

[0004] The host sends a variable voltage signal on the bus, which can be two-level, three-level, or a variety of encoding methods. The slave basically sends a current signal to the bus at a high level or an intermediate level. Sending current at an intermediate level requires the slave to have a faster signal processing speed and send a current with a valid duration during a limited intermediate level. There is no such high requirement for sending current at a high level.

[0005] However, there are many devices on the bus, and the working status of each device is inconsistent, and the power consumption is also changing. If the host wants to accurately identify the current signal sent by the slave, it must know the current value on the bus before the slave sends it, and obtain the current signal sent by the slave through subtraction. If a slave sends a current signal and other devices have large current fluctuations during the period, it is difficult for the host to identify a valid signal. This limits the application of sending current signals at high levels, so a solution that can stabilize the load current is needed. Utility Model Content

[0006] The utility model aims to provide a constant current circuit for load devices on two fire-fighting buses, so as to solve the problem of current fluctuation of other devices on the two fire-fighting buses that send current signals at high levels, so that the host can accurately identify the current signal sent by the slave device.

[0007] In order to achieve the purpose of the utility model, the utility model provides a constant current circuit for load equipment on two fire-fighting buses, including: a dynamic load 2, a current limiting circuit 1, a dynamic current monitoring circuit 3, a constant current control circuit 4 and a current compensation circuit 5;

[0008] The input end of the current limiting circuit 1 is connected to the positive pole of the two fire protection buses, and the output end thereof is connected to the input end of the dynamic load 2;

[0009] The first end of the current compensation circuit 5 is connected to the positive pole of the two fire protection buses, and the second end thereof is connected to the output end of the dynamic load 2;

[0010] The input end of the dynamic current monitoring circuit 3 is connected to the output end of the dynamic load 2, and the output end thereof is connected to the negative pole of the two fire protection buses;

[0011] The input end of the constant current control circuit 4 is connected to the output end of the dynamic current monitoring circuit 3 , and the output end thereof is connected to the third end of the current compensation circuit 5 .

[0012] Furthermore, the current limiting circuit 1 includes a current limiting integrated circuit U1, a resistor R1 and a resistor R2. The input end of the current limiting integrated circuit U1 is connected to the positive pole of the two fire protection buses, and its two output ends are respectively connected to the first end of the resistor R1 and the first end of the resistor R2. The second end of the resistor R1 and the second end of the resistor R2 are the output ends of the current limiting circuit 1.

[0013] Furthermore, the dynamic load 2 includes a parallel capacitor C1, a capacitor C2 and a load, the first end of the capacitor C1 and the first end of the capacitor C2 are connected to the positive electrode of the load as the input end of the dynamic load 2, and the second end of the capacitor C1, the second end of the capacitor C2 and the negative electrode of the load are connected as the output end of the dynamic load 2.

[0014] Further, the dynamic current monitoring circuit 3 includes a resistor R5, a resistor R6, a capacitor C4 and a capacitor C5 connected in parallel, and the node where the first end of the resistor R5, the first end of the resistor R6, the first end of the capacitor C4 and the first end of the capacitor C5 are connected to each other is the input end of the dynamic current monitoring circuit 3, and the node where the second end of the resistor R5, the second end of the resistor R6, the second end of the capacitor C4 and the second end of the capacitor C5 are connected to each other is the output end of the dynamic current monitoring circuit 3.

[0015] Further, the current compensation circuit 5 includes a D stage of the NMOS tube Q1 and a first end of the resistor R3 connected, the first end of the current compensation circuit 5 is the second end of the resistor R3, the S stage of the NMOS tube Q1 is the second end of the current compensation circuit 5, and the G stage of the NMOS tube Q1 is the third end of the current compensation circuit 5.

[0016] Further, the constant current control circuit 4 includes a constant current control integrated circuit U2, a resistor R4 and a capacitor C3;

[0017] The 4th pin of the integrated circuit U2 is the output end of the constant current control circuit 4, the 2nd pin and the 1st pin of the integrated circuit U2 are the input ends of the constant current control circuit 4, the 1st pin of the integrated circuit U2 is connected in series with the capacitor C3, the 5th pin is connected in series with R4 and is connected to the third pin at the same time.

[0018] Furthermore, the constant current circuit also includes a main switch circuit 6, which includes an NMOS tube Q2, and the D stage of the NMOS tube Q2 is connected to the output end of the dynamic current monitoring circuit 3; the S stage of the NMOS tube Q2 is connected to the negative pole of the two fire protection buses, the G stage of the MOS tube Q2 is connected in series with a resistor R7, and a resistor R8 is connected between the S stage and the G stage of the NMOS tube Q2.

[0019] Compared with the prior art, the utility model provides a constant current circuit for load equipment on two fire-fighting buses, which has the following beneficial effects:

[0020] The utility model is used for simulating current change equipment through dynamic load, assuming that the average current of the load is Iload; the current limiting circuit limits the current of the dynamic load, determines the current limiting value Ilim, and ensures that Ilim>Iload; the dynamic current monitoring circuit monitors the current change of the dynamic load in real time, and outputs the feedback amount VFB to the constant current control circuit; the constant current control circuit outputs the control signal Ctr to the current compensation circuit according to the feedback amount VFB; the current compensation circuit compensates the current on the bus according to the control signal Ctr, thereby achieving the purpose of bus constant current, Icomp>Ilim;

[0021] In this way, all devices on the bus are equipped with constant current circuits. When one device sends current at a high level, the total current of other devices on the bus is stable, so the host can identify the current signal well from the bus. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the principle block diagram of the constant current circuit of the load equipment on the two fire-fighting buses of the utility model;

[0023] Figure 2 The utility model is a constant current circuit schematic diagram of a load device on two fire-fighting buses.

[0024] U1-integrated circuit; U2-integrated circuit; D1-diode; C1-capacitor; C2-capacitor; C3-capacitor; C4-capacitor; C5-capacitor; R1-resistor; R2-resistor; R3-resistor; R4-resistor; R5-resistor; R6-resistor; R7-resistor; R8-resistor; Q1-NMOS tube; Q2-NMOS tube, LP+ is the positive voltage value of the bus, LP- is the positive voltage value of the bus. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0026] See also Figure 1-Figure 2 , the utility model embodiment provides the utility model provides a constant current circuit of a load device on two fire-fighting buses, including: a dynamic load 2, a current limiting circuit 1, a dynamic current monitoring circuit 3, a constant current control circuit 4 and a current compensation circuit 5;

[0027] The input end of the current limiting circuit 1 is connected to the positive pole of the two fire protection buses, and the output end thereof is connected to the input end of the dynamic load 2;

[0028] The first end of the current compensation circuit 5 is connected to the positive pole of the two fire protection buses, and the second end thereof is connected to the output end of the dynamic load 2;

[0029] The input end of the dynamic current monitoring circuit 3 is connected to the output end of the dynamic load 2, and the output end thereof is connected to the negative pole of the two fire protection buses;

[0030] The input end of the constant current control circuit 4 is connected to the output end of the dynamic current monitoring circuit 3 , and the output end thereof is connected to the third end of the current compensation circuit 5 .

[0031] in:

[0032] The current limiting circuit 1 includes a current limiting integrated circuit U1, a resistor R1 and a resistor R2. The input end of the current limiting integrated circuit U1 is connected to the positive poles of the two fire protection buses, and its two output ends are respectively connected to the first end of the resistor R1 and the first end of the resistor R2. The second end of the resistor R1 and the second end of the resistor R2 are the output ends of the current limiting circuit 1.

[0033] Dynamic load 2 is used to simulate an electrical device with current changes, including parallel capacitors C1, C2 and a load, the first end of capacitor C1 and the first end of capacitor C2 connected to the positive electrode of the load are the input end of the dynamic load 2, and the second end of capacitor C1, the second end of capacitor C2 and the negative electrode of the load are connected to form the output end of the dynamic load 2. Capacitors C1 and C2 provide instantaneous energy for the dynamic load, and the capacitance can be adjusted according to the load characteristics; it is assumed that the average current consumed by the load is Iload.

[0034] The dynamic current monitoring circuit 3 includes a current monitoring circuit composed of a resistor R5, a resistor R6, a capacitor C4 and a capacitor C5 connected in parallel. The node where the first end of the resistor R5, the first end of the resistor R6, the first end of the capacitor C4 and the first end of the capacitor C5 are connected to each other is the input end of the dynamic current monitoring circuit 3. The node where the second end of the resistor R5, the second end of the resistor R6, the second end of the capacitor C4 and the second end of the capacitor C5 are connected to each other is the output end of the dynamic current monitoring circuit 3. The current change of the load is sampled in real time by the resistor R5 and the resistor R6, and the feedback amount VFB is output to the constant current control circuit 4. The capacitor C4 and the capacitor C5 play a filtering role.

[0035] The constant current control circuit 4 includes a constant current control integrated circuit U2, a resistor R4 and a capacitor C3; the 4th pin of the integrated circuit U2 is the output end of the constant current control circuit 4, the 2nd pin and the 1st pin of the integrated circuit U2 are the input ends of the constant current control circuit 4, the 1st pin of the integrated circuit U2 is connected in series with the capacitor C3, the 5th pin is connected in series with R4 and is connected to the third pin at the same time. The integrated circuit U2 is a constant current control integrated circuit, and outputs a control signal Ctr to the current compensation circuit 5 according to the feedback amount VFB, the resistor R4 is a pull-up resistor, and the capacitor C3 is a power supply decoupling capacitor.

[0036] The current compensation circuit 5 is used as current compensation, including the connection between the D level of the NMOS tube Q1 and the first end of the resistor R3, the first end of the current compensation circuit 5 is the second end of the resistor R3, the S level of the NMOS tube Q1 is the second end of the current compensation circuit 5, and the G level of the NMOS tube Q1 is the third end of the current compensation circuit 5. The control signal Ctr controls the opening and closing of the NMOS tube Q1, and compensates the current on the bus through the resistor R3, thereby achieving the purpose of bus constant current. The compensation current Icomp=VLP+-VFB / R1, requiring Icomp>Ilim.

[0037] In this way, if all devices on the bus have this mechanism, then when one device sends current at a high level, the total current of other devices on the bus is stable, so that the host can identify the current signal well from the bus.

[0038] Furthermore, the constant current circuit of the utility model also includes a main switch circuit 6, which includes an NMOS tube Q2, and the D stage of the NMOS tube Q2 is connected to the output end of the dynamic current monitoring circuit 3; the S stage of the NMOS tube Q2 is connected to the negative pole of the two fire protection buses, the G stage of the MOS tube Q2 is connected in series with a resistor R7, and a resistor R8 is connected between the S stage and the G stage of the NMOS tube Q2.

[0039] Optionally, the current limiting circuit 1 can be placed at the lower end of the dynamic load 2 .

[0040] Optionally, the dynamic current monitoring circuit 3 can be placed at the upper end of the dynamic load 2 .

[0041] The utility model provides a method for realizing a constant current circuit of a load device on two fire-fighting buses, and the specific steps include the following:

[0042] Step 1: Dynamic load 2 is used to simulate the current change of the device, if the maximum load current Imax;

[0043] Step 2: The current limiting circuit 1 limits the current of the dynamic load, the current limiting value Ilim, and ensures that Ilim>Imax;

[0044] Step 3: The dynamic current monitoring circuit 3 monitors the current change of the dynamic load in real time and outputs the feedback amount FB to the constant current control circuit;

[0045] Step 4: The constant current control circuit 4 outputs a control signal Ctr to the current compensation circuit according to the feedback amount FB;

[0046] Step 5: The current compensation circuit 5 compensates the current on the bus according to the control signal Ctr, thereby achieving the purpose of bus constant current. The maximum compensation current Icomp>Ilim is required;

[0047] The above are only preferred specific implementation methods of the utility model, but the protection scope of the utility model is not limited to this. Any technician familiar with the technical field within the technical scope disclosed by the utility model, who makes equivalent replacements or changes based on the technical scheme and utility model concept of the utility model, should be covered by the protection scope of the utility model.

Claims

1. A constant current circuit for load equipment on two fire-fighting buses, characterized in that: include: A dynamic load (2), a current limiting circuit (1), a dynamic current monitoring circuit (3), a constant current control circuit (4) and a current compensation circuit (5); the input end of the current limiting circuit (1) is connected to the positive poles of the two fire protection buses, and the output end thereof is connected to the input end of the dynamic load (2); the first end of the current compensation circuit (5) is connected to the positive poles of the two fire protection buses, and the second end thereof is connected to the output end of the dynamic load (2); the input end of the dynamic current monitoring circuit (3) is connected to the output end of the dynamic load (2), and the output end thereof is connected to the negative poles of the two fire protection buses; the input end of the constant current control circuit (4) is connected to the output end of the dynamic current monitoring circuit (3), and the output end thereof is connected to the third end of the current compensation circuit (5).

2. A constant current circuit for load equipment on two fire-fighting buses according to claim 1, characterized in that: The current limiting circuit (1) comprises a current limiting integrated circuit U1, a resistor R1 and a resistor R2. The input end of the current limiting integrated circuit U1 is connected to the positive poles of the two fire protection buses, and the two output ends thereof are respectively connected to the first end of the resistor R1 and the first end of the resistor R2. The second end of the resistor R1 and the second end of the resistor R2 are the output ends of the current limiting circuit (1).

3. A constant current circuit for load equipment on two fire-fighting buses according to claim 1, characterized in that: The dynamic load (2) comprises a parallel capacitor C1, a capacitor C2 and a load, wherein the first end of the capacitor C1 and the first end of the capacitor C2 are connected to the positive electrode of the load as the input end of the dynamic load (2), and the second end of the capacitor C1, the second end of the capacitor C2 and the negative electrode of the load are connected to form the output end of the dynamic load (2).

4. A constant current circuit for load equipment on two fire-fighting buses according to claim 1, characterized in that: The dynamic current monitoring circuit (3) comprises a resistor R5, a resistor R6, a capacitor C4 and a capacitor C5 connected in parallel with each other; a node where the first end of the resistor R5, the first end of the resistor R6, the first end of the capacitor C4 and the first end of the capacitor C5 are connected to each other is the input end of the dynamic current monitoring circuit (3); and a node where the second end of the resistor R5, the second end of the resistor R6, the second end of the capacitor C4 and the second end of the capacitor C5 are connected to each other is the output end of the dynamic current monitoring circuit (3).

5. A constant current circuit for load equipment on two fire-fighting buses according to claim 1, characterized in that: The current compensation circuit (5) comprises a D-stage of an NMOS tube Q1 and a first end of a resistor R3 connected, the first end of the current compensation circuit (5) is the second end of the resistor R3, the S-stage of the NMOS tube Q1 is the second end of the current compensation circuit (5), and the G-stage of the NMOS tube Q1 is the third end of the current compensation circuit (5).

6. A constant current circuit for load equipment on two fire-fighting buses according to claim 1, characterized in that: The constant current control circuit (4) comprises a constant current control integrated circuit U2, a resistor R4 and a capacitor C3; the fourth pin of the integrated circuit U2 is the output end of the constant current control circuit (4), the second pin and the first pin of the integrated circuit U2 are the input ends of the constant current control circuit (4), the first pin of the integrated circuit U2 is connected in series with the capacitor C3, the fifth pin is connected in series with R4 and is simultaneously connected to the third pin.

7. A constant current circuit for load equipment on two fire-fighting buses according to claim 1, characterized in that: The constant current circuit also includes a main switch circuit (6), which includes an NMOS tube Q2, wherein the D stage of the NMOS tube Q2 is connected to the output end of the dynamic current monitoring circuit (3); the S stage of the NMOS tube Q2 is connected to the negative electrode of the two fire protection buses, the G stage of the MOS tube Q2 is connected in series with a resistor R7, and a resistor R8 is connected between the S stage and the G stage of the NMOS tube Q2.

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