Intrinsic safety power supply capable of resisting impact of load starting current

Abstract

One end of a current sampling resistor R1 is connected with the positive electrode of the power supply, the other end of the current sampling resistor R1 is connected with the input end of an MOS tube unit, the positive input end and the negative input end of a high-speed operational amplifier are connected with the two ends of the current sampling resistor R1 respectively, and the output end of the high-speed operational amplifier is connected with the input end of a current limiting detection unit. A constant-current control signal output by the current limiting detection unit is transmitted to the input end of the MOS tube driving unit, a cut-off signal is transmitted to the input end of the MOS tube driving unit through the on-off switch SW1, the MOS tube driving unit is output to the control end of the MOS tube unit, the cathode of the voltage stabilizing diode W1 is connected with the output end of the MOS tube unit, the anode of the voltage stabilizing diode W1 is connected with one end of the resistor R2, and the other end of the resistor R2 is connected with the negative electrode of the power supply. The positive input end of the voltage comparator is connected with the anode of the voltage stabilizing diode W1, reference voltage is input into the negative input end of the voltage comparator, and the output end of the voltage comparator controls the on-off of the on-off switch SW1. The intrinsically safe power supply not only has the advantage of quick turn-off, but also has the constant current type characteristic of difficult interruption and restart, and optimizes the working condition of the load.

Description

TECHNICAL FIELD

[0001] The application relates to an intrinsically safe power supply for a mine monitoring substation, in particular to an intrinsically safe power supply resisting load starting current impact, and belongs to the technical field of coal mine safety monitoring equipment. BACKGROUND

[0002] Mine underground mining needs a large number of monitoring substations, and the power supply of the monitoring substation not only needs to ensure the reliable work of the substation itself, but also has high requirements for the output stability, applicability and reliability of the intrinsically safe power supply.

[0003] At present, the intrinsically safe power supply is roughly divided into two types: constant current type and current cut-off type. The constant current type intrinsically safe power supply is friendly to the load, and when the load is too large and exceeds the current limiting value, the output voltage decreases, and when the load is reduced, the voltage recovers. The disadvantage is that when the load is short-circuited, the power supply is slow to close.

[0004] The current cut-off type intrinsically safe power supply is characterized by fast closing speed when the load is short-circuited, and the disadvantage is that the output power supply is interrupted instantaneously when starting again, which leads to frequent restart of the heavy load. SUMMARY

[0005] The purpose of the application is to provide an intrinsically safe power supply resisting load starting current impact, which has the fast action of the current cut-off type power supply and the constant current output of the constant current type intrinsically safe power supply without frequent restart, and takes into account the continuity and safety.

[0006] The purpose of the application is achieved by the following technical scheme:

[0007] An intrinsically safe power supply resisting load starting current impact comprises a current sampling resistor R1, a high-speed operational amplifier, a current limiting detection unit, a MOS tube unit, a MOS tube driving unit, a on-off switch SW1, a voltage comparator, a voltage stabilizing diode W1 and a resistor R2. One end of the current sampling resistor R1 is connected to the positive electrode of the power supply, and the other end is connected to the input end of the MOS tube unit. The positive and negative input ends of the high-speed operational amplifier are connected to the two ends of the current sampling resistor R1. The output end of the high-speed operational amplifier is connected to the input end of the current limiting detection unit. The output of the current limiting detection unit is divided into two paths. The first path constant current control signal is output to the input end of the MOS tube driving unit. The second path cut-off shutdown signal is output to the input end of the MOS tube driving unit through the contact of the on-off switch SW1. The output end of the MOS tube driving unit is connected to the control end of the MOS tube unit. The cathode of the voltage stabilizing diode W1 is connected to the output end of the MOS tube unit. The anode of the voltage stabilizing diode W1 is connected to one end of the resistor R2. The other end of the resistor R2 is connected to the negative electrode of the power supply. The positive input end of the voltage comparator is connected to the anode of the voltage stabilizing diode W1. The negative input end of the voltage comparator inputs a reference voltage. The output end of the voltage comparator controls the on-off of the on-off switch SW1.

[0008] The purpose of the present invention can be further achieved by the following technical measures:

[0009] The above-mentioned intrinsically safe power supply that is resistant to load starting current impact, the current limiting detection unit outputs a constant current control signal and a cut-off signal after passing through the delay circuit.

[0010] Compared with the prior art, the beneficial effects of the present invention are: the intrinsically safe power supply has the advantages of fast shutdown of the current cut-off type and the characteristics of the constant current type that is not easy to interrupt the current output and cause the load to restart, thereby optimizing the load working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 The present invention is a schematic diagram of an intrinsically safe power supply circuit capable of resisting load starting current impact. DETAILED DESCRIPTION

[0012] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0013] like Figure 1 As shown, the intrinsically safe power supply with resistance to load startup current impact includes a current sampling resistor R1, a high-speed operational amplifier, a current limiting detection unit, a MOS tube unit, a MOS tube driving unit, an on-off switch SW1, a voltage comparator, a voltage regulator diode W1, and a resistor R2. One end of the current sampling resistor R1 is connected to the positive electrode of the power supply, and the other end is connected to the input end of the MOS tube unit. The positive and negative input ends of the high-speed operational amplifier are respectively connected to the two ends of the current sampling resistor R1. The output end of the high-speed operational amplifier is connected to the input end of the current limiting detection unit. The output of the current limiting detection unit is divided into two paths. The first path is a constant current control signal output to The MOS tube driving unit input end, the second cut-off signal is output to the MOS tube driving unit input end through the contact of the on-off switch SW1, the MOS tube driving unit output end is connected to the MOS tube unit control end, the cathode of the Zener diode W1 is connected to the MOS tube unit output end, the anode of the Zener diode W1 is connected to one end of the resistor R2, the other end of the resistor R2 is connected to the negative electrode of the power supply, the positive input end of the voltage comparator is connected to the anode of the Zener diode W1, the negative input end of the voltage comparator inputs the reference voltage, and the output end of the voltage comparator controls the on and off of the on-off switch SW1.

[0014] This circuit is a dual-protected intrinsically safe power supply that combines constant current control (closed-loop negative feedback) and current cut-off protection (switch control) to ensure safe output cut-off in the event of overcurrent or undervoltage, meeting mining explosion-proof requirements.

[0015] The input power supply on the non-intrinsically safe side is 24V DC. The core functional modules of the circuit of the present invention are:

[0016] Current detection and current limiting control (first channel): closed-loop negative feedback constant current control;

[0017] Current cut-off protection (second path): Forced turn-off of MOSFET when overcurrent occurs.

[0018] Voltage drop detection: Cut-off protection is released and constant current control is resumed when under-voltage occurs.

[0019] The detailed working process of the circuit of the embodiment of the present application is as follows:

[0020] (1) Normal working condition (for example, current < 500 mA):

[0021] Current detection: The input current flows through the sampling resistor R1 to generate a voltage drop signal, and the high-speed operational amplifier amplifies the signal and compares it with the reference voltage (corresponding to 500 mA).

[0022] First path constant current control loop: The operational amplifier output adjusts the MOSFET gate voltage through negative feedback to dynamically adjust the conduction degree, so that the output current is stabilized at the set value. Its closed-loop control is as follows: if the current increases, the sampling resistor voltage drop increases, the operational amplifier output adjusts, the MOSFET conduction weakens, and the current falls back.

[0023] Second path cut-off protection loop:

[0024] When the current is not over-limit, the voltage comparator output is low, the on-off switch SW1 is disconnected, and the circuit is controlled only by the first path.

[0025] (2) When overcurrent occurs (for example, current ≥ 500 mA):

[0026] Second path priority action: When the operational amplifier detects that the current is ≥ 500 mA, the on-off switch SW1 is connected, the second path output is high, and the MOSFET is forced to turn off (cut-off type control). The power output is immediately cut off to prevent the transmission of dangerous energy.

[0027] Voltage drop detection: After the MOSFET is cut off, the output voltage begins to drop. When the voltage ≤ 18 V, the voltage comparator output is low, and the cut-off control of the second path is disconnected. The first path resumes work: the closed-loop negative feedback works again to output constant current. Circuit oscillation risk: If the load fault is not eliminated, the cut-off may be triggered again. If the cut-off and recovery frequency is too high, a delay circuit can be added to delay the risk of oscillation.

[0028] The circuit has three mechanisms of closed-loop constant current + hard cut-off protection + voltage drop recovery, which ensures that the intrinsically safe power supply is quickly turned off when overcurrent occurs, and automatically recovers under safe conditions, which is very suitable for high-risk environments such as mining.

[0029] In addition to the above embodiment, the present application can have other implementation manners, and any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present application.

Claims

1. An intrinsically safe power supply that is resistant to load starting current shock, characterized in that: The device includes a current sampling resistor R1, a high-speed operational amplifier, a current limiting detection unit, a MOS tube unit, a MOS tube driving unit, an on-off switch SW1, a voltage comparator, a voltage stabilizing diode W1, and a resistor R2. One end of the current sampling resistor R1 is connected to the positive electrode of the power supply, and the other end is connected to the input end of the MOS tube unit. The positive and negative input ends of the high-speed operational amplifier are respectively connected to the two ends of the current sampling resistor R1. The output end of the high-speed operational amplifier is connected to the input end of the current limiting detection unit. The output of the current limiting detection unit is divided into two paths. The first path is a constant current control signal output to the input end of the MOS tube driving unit, and the second path is a cutoff signal output to the input end of the MOS tube driving unit through the contact of the on-off switch SW1. The output end of the MOS tube driving unit is connected to the control end of the MOS tube unit. The cathode of the voltage stabilizing diode W1 is connected to the output end of the MOS tube unit, the anode of the voltage stabilizing diode W1 is connected to one end of the resistor R2, and the other end of the resistor R2 is connected to the negative electrode of the power supply. The positive input end of the voltage comparator is connected to the anode of the voltage stabilizing diode W1, the negative input end of the voltage comparator is input with a reference voltage, and the output end of the voltage comparator controls the on and off of the on-off switch SW1.

2. The intrinsically safe power supply capable of resisting load starting current shock according to claim 1, characterized in that: The current limiting detection unit outputs a constant current control signal and a cut-off signal after passing through a delay circuit.

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