CN203747501U - Mine Intrinsically Safe DC Uninterruptible Power Supply - Google Patents

Abstract

The utility model relates to a power supply circuit, in particular to an intrinsically safe DC uninterruptible power supply device for mines. An intrinsically safe direct current uninterruptible power supply for mining, including a step-down isolation transformer, a rectification filter circuit, a voltage stabilization circuit, and an intrinsically safe output module. circuit, wherein one output of the rectification and filtering circuit is connected to the DC-DC direct current conversion output circuit, and the output of the other rectification and filtering circuit is connected to the voltage stabilizing circuit, and the output of the voltage stabilizing circuit is connected to the storage battery; connected to the DC-DC direct current conversion output circuit and the storage battery There is a switching circuit; the DC-DC conversion output circuit and the storage battery are connected to the intrinsically safe output module through the switching circuit and the protection circuit. The utility model mine intrinsically safe DC uninterruptible power supply, when the external power supply is used, the backup power supply is in a floating charge state; when the external power supply is cut off, the backup power supply is automatically put into operation, and there are protective measures to prevent battery overcharging and over-discharging.

Description

Mine Intrinsically Safe DC Uninterruptible Power Supply

technical field

The utility model relates to a power supply circuit, in particular to an intrinsically safe DC uninterruptible power supply device for mines.

Background technique

The underground working environment of the mine is special, and accidents are prone to occur, resulting in the interruption of AC power supply. In order to repair the accident, many sensors and communication equipment must continue to work after the power grid stops. Therefore, the intrinsically safe power supply must have a backup battery so that the backup battery can continue to supply power to the load when the power grid fails. In addition, mine-used intrinsically safe DC uninterruptible power supply (referred to as intrinsically safe power supply) is required to operate under the conditions of -10～+40℃, relative humidity ≤95% (at 25℃), explosive mixture of methane or coal dust, etc. Can work safely and normally. In addition, according to the national standard GB3836.4-2010, the output voltage or current cannot ignite the surrounding flammable gas, and there must be reliable electrical isolation between intrinsically safe circuits and non-intrinsically safe circuits to meet the high requirements of mine work on power supplies.

Contents of the invention

Aiming at the deficiencies of the prior art, the utility model proposes an intrinsically safe DC uninterruptible power supply for mines with simple structure, small volume and low cost. Easy installation and strong practicability.

The technical scheme adopted in the utility model:

An intrinsically safe direct current uninterruptible power supply for mining, including a step-down isolation transformer, a rectification filter circuit, a voltage stabilization circuit, and an intrinsically safe output module. circuit, wherein one output of the rectification and filtering circuit is connected to the DC-DC direct current conversion output circuit, and the output of the other rectification and filtering circuit is connected to the voltage stabilizing circuit, and the output of the voltage stabilizing circuit is connected to the storage battery; connected to the DC-DC direct current conversion output circuit and the storage battery There is a switching circuit; the DC-DC conversion output circuit and the storage battery are connected to the intrinsically safe output module through the switching circuit and the protection circuit.

The DC-DC conversion output circuit adopts step-down DC/DC converter XL2576, the positive and negative poles output by the rectification filter circuit are respectively connected to pin 1 and pin 3 of the DC/DC converter XL2576, and the pins of the DC/DC converter XL2576 An adjustable resistor is connected between pin 2 and pin 4, a Zener diode is connected between pin 2 of the DC/DC converter XL2576 and the negative pole of the power supply, pin 5 of the DC/DC converter XL2576 is connected to a switch, and the DC/DC converter XL2576 After realizing DC-DC conversion, output DC power to supply power to the load.

The voltage regulator circuit uses a three-terminal adjustable voltage regulator tube LM317T to form a charging circuit to charge the Ni-MH battery; the input end of the three-terminal adjustable voltage regulator tube LM317T is connected to the output end of the rectifier filter circuit, and the three-terminal adjustable voltage regulator tube LM317T The output terminal is connected to the battery.

The protection circuit includes an overvoltage and undervoltage protection circuit and an overcurrent protection circuit. The overvoltage and undervoltage protection circuit includes two sets of parallel overvoltage and undervoltage comparison circuits. The output of the DC/DC converter XL2576 is sampled The circuits are respectively connected to overvoltage and undervoltage comparators, and the output terminals of the two comparators are connected to a transistor switch, and the transistor switch is connected to pin 5 of the DC/DC converter XL2576; the overcurrent protection circuit includes a current transformer, The sampling circuit, the reference regulated power supply and the comparator, the reference regulated power supply provides the reference voltage and power for the comparator, the output of the sampling circuit is connected to the comparator input terminal, and the comparator output terminal is connected to pin 5 of the DC/DC converter XL2576.

The switching circuit includes a normally open relay K1, a normally closed relay K2, and a triode Q4; the output terminal of the three-terminal adjustable voltage regulator tube LM317T is connected with the normally open relay K1 and the normally closed relay K2 through a diode D8, and the normally open relay K1 controls the battery. For charging, the normally open relay K1 is connected to the triode Q4 under control, and the triode Q4 controls the sampling circuit whose base is connected to the output terminal of the voltage regulator circuit. The normally closed relay K2 is closed when the mains fails, so that the battery supplies power to the load and realizes conversion.

The beneficial effects of the utility model:

1. The intrinsically safe DC uninterruptible power supply for mines of this utility model, when powered by an external power supply, the backup power supply is in a floating charge state and has a protection function to prevent battery overcharging; when the external power supply is cut off, the backup power supply is automatically put into operation, and There are protective measures to prevent battery overcharge and overdischarge. It can be used in high-risk environments such as coal mines, chemicals, petroleum, etc., as well as energy-saving and environment-friendly production sites that require intrinsically safe DC regulated power supplies.

2. The intrinsically safe DC uninterruptible power supply of the utility model can realize DC voltage output, and also perform over-voltage and under-voltage protection, and use relays to realize fast switching of circuits. The utility model has the advantages of simple circuit, high conversion efficiency, uninterrupted power supply, and low cost. The intrinsically safe power supply voltage is 220V, the allowable fluctuation range is 80%-110%; the output voltage is 18V; the working current =<800mA, and its value can be adjusted according to the corresponding load demand.

3. The mine-used intrinsically safe DC uninterruptible power supply of this utility model adopts overcharge and overdischarge protection circuits to fully protect the charging and discharging process of the battery, and meets the high requirements of mine work on power supply. Adopt step-down DC/DC converter XL2576, three-terminal adjustable regulator tube LM317T and LM339 to realize the management of uninterrupted power supply, when the AC power supply is normal, the power is supplied by the AC power supply system; when the AC power fails, the battery provides power , to meet the requirements of mining uninterruptible power supply.

4. The intrinsically safe DC uninterruptible power supply for mines of this utility model uses circuits such as over-voltage and under-voltage, over-current, short-circuit protection and battery charging management to meet the high requirements of mine work on power supplies, and it also has a small size , Simple installation, low cost and a series of advantages, strong practical applicability.

Description of drawings

Fig. 1 is a block diagram of the composition of the utility model DC stabilized voltage supply;

Fig. 2 is the utility model DC stabilized power supply DC-DC direct current conversion output circuit;

Fig. 3 is the protection circuit of overvoltage and undervoltage of the DC stabilized power supply of the present invention;

Fig. 4 is the overcurrent protection circuit of the DC stabilized power supply of the utility model;

Fig. 5 is the charging and switching circuit of the DC stabilized power supply of the utility model.

Detailed ways

The technical solutions of the present invention will be further described in detail through specific implementation methods below.

Example 1

Referring to Fig. 1 , the utility model mine intrinsically safe DC uninterruptible power supply includes a step-down isolation transformer, a rectification filter circuit, a voltage stabilizing circuit, and an intrinsically safe output module. Input two rectifying and filtering circuits, wherein the output of one rectifying and filtering circuit is connected to the DC-DC conversion output circuit, and the output of the other rectifying and filtering circuit is connected to the voltage stabilizing circuit, and the output of the voltage stabilizing circuit is connected to the storage battery; and the output of the DC-DC direct current conversion The output circuit and the storage battery are connected with a switching circuit; the DC-DC conversion output circuit and the storage battery are connected to the intrinsically safe output module through the switching circuit and the protection circuit.

Example 2

Referring to Fig. 1 and Fig. 2, the mine intrinsically safe DC uninterruptible power supply of this embodiment is different from Embodiment 1 in that further: the DC-DC direct current conversion output circuit adopts a step-down DC/DC converter XL2576, the positive and negative electrodes of the rectification and filtering circuit are connected to pin 1 and pin 3 of the DC/DC converter XL2576 respectively, and the adjustable resistor is connected between pin 2 and pin 4 of the DC/DC converter XL2576, and the DC/DC converter XL2576 A Zener diode is connected between pin 2 of the DC/DC converter XL2576 and the negative pole of the power supply, and pin 5 of the DC/DC converter XL2576 is connected to a transfer switch.

As shown in Figure 2, the DC-DC conversion output circuit uses a step-down DC/DC converter XL2576. XL2576 is a 52KHz fixed frequency pulse width modulation DC-DC converter, the pulse width modulation control circuit can linearly adjust the duty cycle from 0 to 100%, low ripple, built-in over-current and short-circuit protection functions, when over-current and When short-circuit protected, the operating frequency of XL2576 drops from 52KHz to 31KHz. Built-in frequency compensation, soft start, thermal shutdown, current limit and short circuit protection functions. The output voltage range of XL2576 is 1.23V to 38V, and the maximum load current is 3A. After the AC power is stepped down, rectified and filtered to filter out high-order harmonics, it is connected to the input pin of the step-down DC/DC converter XL2576. The input voltage range of the XL2576 is 3.6V to 40V, and an external bypass capacitor is connected to the ground to eliminate Input noise. Through the 2-pin output of XL2576, the 3-pin is the ground pin. This pin must be placed outside the Schottky diode and the output capacitor to the ground to prevent the switching current glitch caused by the inductor voltage noise from being input to the XL2576. The precision of adjusting the output voltage is improved through the fixed resistor R2 and an adjustable potentiometer R1.

Example 3

Referring to Fig. 1 and Fig. 2, the mine intrinsically safe DC uninterruptible power supply of this embodiment is different from Embodiment 2 in that further: the voltage stabilizing circuit adopts a three-terminal adjustable voltage stabilizing tube LM317T to form a charging circuit for Ni-MH battery charging; the input end of the three-terminal adjustable voltage regulator LM317T is connected to the output end of the rectifier filter circuit, and the output end of the three-terminal adjustable voltage regulator LM317T is connected to the storage battery.

The utility model mine intrinsically safe DC uninterruptible power supply, when mining AC power supply, the 220V AC power is converted and output by the isolation transformer, and after rectification and filtering all the way, through the three-terminal adjustable voltage regulator LM317T as the core The charging circuit charges the Ni-MH battery; the other circuit is rectified and filtered, and the XL2576 realizes DC-DC conversion and then outputs DC to supply power to the load. When the mining AC power is cut off, the switching switch with switching circuit switches automatically, and the 24V Ni-MH battery supplies power to the load.

As shown in Figure 1, the AC of the power supply network must be stepped down by the transformer, and two ACs of 18V and 24V are output on the secondary side of the transformer. The charging and switching circuit controlled by the regulator tube LM317T provides power. Since it is an intrinsically safe electrical equipment powered by the coal mine underground power grid, the transformer used for step-down is an R-type isolation transformer that meets the provisions of Article 6.1 of GB3836.4-83.

Example 4

Referring to Figures 1 to 4, the mine intrinsically safe DC uninterruptible power supply of this embodiment is different from the previous embodiments in that further: the protection circuit includes an overvoltage and undervoltage protection circuit and an overcurrent protection circuit, The overvoltage and undervoltage protection circuit includes two sets of parallel overvoltage and undervoltage comparison circuits, and the output terminals of the DC/DC converter XL2576 are respectively connected to the overvoltage and undervoltage comparators through the sampling circuit, and the two comparators The output terminal is connected to the transistor switch Q1, and the collector output terminal of the transistor switch Q1 is connected to pin 5 of the DC/DC converter XL2576; the overcurrent protection circuit includes a current transformer, a sampling circuit, a reference stabilized power supply and a comparator, The reference stabilized power supply provides the reference voltage and power supply for the comparator, the output of the sampling circuit is connected to the input terminal of the comparator, and the output terminal of the comparator is connected to pin 5 of the DC/DC converter XL2576.

In order to prevent sparks from igniting flammable gases caused by abnormal discharge of the power supply caused by abnormal conditions of the power supply or abnormal discharge of the current, the utility model is designed with overvoltage protection and overcurrent protection for mining intrinsically safe DC uninterruptible power supply, such as Figure 3 shows. And when the power supply is abnormal, the protection circuit responds quickly and accurately. Component R9, capacitor C3, and diode D form a delay circuit, which is used to prevent the moment when the power supply starts, the impulse voltage is too high and the power supply does not work, causing false protection, so that the power supply cannot start normally. When the input voltage Vc and Vb are equal, the output of the undervoltage comparator N1 is low level, so the drive signal PWM is blocked, at this time, the transistor Q1 is turned off from the original conduction, and the drive signal received by pin 5 of the XL2576 is also From low level to high level, since XL2576 is triggered by low level, XL2576 stops working at this time, which plays a protective role. Adjusting RP5 can adjust the voltage threshold of overvoltage and undervoltage action. When the compared signal voltage Vc is between the threshold voltages, the window voltage △V=Vb-Va, this voltage is used to judge whether the input signal voltage is between the threshold voltages. In this design, we set Vb to 18.5V and Va to 17.5V, so the window voltage △V=Vb-Va=18.5-17.5=1V. Therefore, whether it is an overvoltage or undervoltage fault, the output level of the comparator changes from high to low, so the drive signal PWM is blocked. It also changes from low level to high level. Since XL2576 is triggered by low level, XL2576 stops working at this time, which plays a protective role.

As shown in Figure 4, a current transformer is used in the overcurrent protection circuit, and the collected current is converted into a voltage signal through a resistor, and the voltage signal is collected through a resistor series voltage divider circuit, and the signal is passed through the LM339 and the standard +5V voltage Compared. The standard voltage is input to the inverting input of the comparator, and the signal is input to the positive input. The output terminal of the comparator is connected to pin 5 of the DC-DC chip XL2576. The maximum current is set to 800mA, when the output current reaches 800mA, the comparator positive input terminal voltage is +5V, the comparator outputs a high level, and pin 5 of the XL2576 gets a high level signal, and the output is quickly cut off to protect the Effect. The margin of error is 5%.

Example 5

Referring to Figures 1 to 5, the intrinsically safe DC uninterruptible power supply for mining in this embodiment is different from Embodiment 4 in that further: the switching circuit includes a normally open relay K1, a normally closed relay K2, and a transistor Q4; The output terminal of the three-terminal adjustable voltage regulator tube LM317T is connected to the normally open relay K1 and the normally closed relay K2 through the diode D8. The normally open relay K1 controls the charging of the battery, and the normally open relay K1 is connected to the triode Q4 under control, and the triode Q4 controls the base. Connected to the sampling circuit at the output end of the voltage stabilizing circuit, the normally closed relay K2 realizes that the battery supplies power to the load when the mains fails.

The charging and switching circuit is mainly to charge the battery. When the mains stops working, it will quickly switch to the battery power supply state. When the battery is over-discharged, it will stop discharging and reduce unnecessary losses and hazards. The circuit principle is shown in Figure 5. Show. After the 220V AC is stepped down, the output from the bridge rectifier is a pulsating voltage, and the high-order harmonic component needs to be filtered out through the electrolytic capacitor before it can be connected to the input terminal of the three-terminal adjustable voltage regulator LM317T. Its output end is connected with normally open relay K1 and normally closed relay K2 through diode D8, normally open relay K1 controls the charging of the battery, normally closed relay K2 switches the circuit, and uses LED high-brightness light-emitting diodes to intuitively display the working status of the power supply. When the utility power is working normally, the green light-emitting diode D6 is on, the transistor Q4 is turned on, the coil of the relay K2 has current flowing, the relay is disconnected, and the battery is not discharged. There is current flowing in K1, the relay is closed, and charging starts. When the battery voltage reaches 26V, the voltage is collected by the resistor divider sampling circuit and compared with the standard +9V voltage. The standard signal is connected to the positive input terminal. When the collected voltage is greater than 9V, the comparator outputs a low level, Q4 is cut off, and the battery stops charging. When the mains fails, quickly switch to the battery, because the diode D8 has unidirectional conductivity, the transistor Q4 is cut off, there is no current in the coil of the relay K2, the normally closed relay is closed, the battery starts to work, and the conversion is realized. At this time, the red LED of D9 LED lights up. The storage battery is connected to pin 2 of the DC-DC chip XL2576 through a relay, and thus connected to the following overvoltage, undervoltage and overcurrent protection circuit. In the other way, use LM7809 to convert the 24V voltage of the battery into 9V to provide a reference voltage. By adjusting the value of R29, when the battery voltage is less than 22V, the voltage of R28 is less than 9V, and the comparator LM339 outputs a low level, and the transistor Q5 is turned off and Q4 is turned on. , The storage battery uses a single 1.2V Ni-MH battery with a total of 20 cells, and the minimum discharge voltage of a single-cell Ni-MH battery is 1V. Therefore, the minimum discharge voltage of a 24V battery cannot be lower than 20V, here, it is set to 22V.

Table 1 shows the test items and test result analysis of the utility model intrinsically safe DC uninterruptible power supply for mining. The results show that the actual simulation experiment value is basically consistent with the theoretical calculation value, and the error is very small, which is within the allowable range, which proves that the circuit design It is correct and scientifically sound.

Table 1: Test items and test result analysis

 

The utility model adopts step-down DC/DC converter XL2576, three-terminal adjustable voltage regulator tube LM317T and LM339 to realize the management of the uninterrupted power supply. When the AC power supply is normal, the AC power supply system supplies power; when the AC power fails, the The storage battery provides power, which meets the requirements of uninterruptible power supply for mining. The device uses circuits such as over-voltage and under-voltage, over-current, short-circuit protection and battery charging management to meet the high requirements of mine work for power supply, and it also has a series of advantages such as small size, simple installation, and low cost. Strong.

Claims (5)

1. A mining intrinsically safe DC uninterruptible power supply, comprising a step-down isolation transformer, a rectifier filter circuit, a voltage stabilizing circuit, and an intrinsically safe output module, is characterized in that: from the step-down isolation transformer, two conversion outputs are drawn respectively Connect to two rectification and filtering circuits, one of which is connected to the DC-DC conversion output circuit, and the output of the other rectification and filtering circuit is connected to the voltage stabilizing circuit, and the output of the voltage stabilizing circuit is connected to the battery; and the output of the DC-DC DC The conversion output circuit and the battery are connected with a switch circuit; the DC-DC conversion output circuit and the battery are connected to the intrinsically safe output module through the switch circuit and the protection circuit. 2. The intrinsically safe DC uninterruptible power supply for mining according to claim 1, characterized in that: the DC-DC conversion output circuit adopts a step-down DC/DC converter XL2576, and the rectification and filtering circuit outputs positive and negative The negative pole is connected to pin 1 and pin 3 of the DC/DC converter XL2576, an adjustable resistor is connected between pin 2 and pin 4 of the DC/DC converter XL2576, and pin 2 of the DC/DC converter XL2576 is connected to the negative pole of the power supply Zener diode, DC/DC converter XL2576 pin 5 is connected to the transfer switch, DC/DC converter XL2576 realizes DC-DC conversion and outputs DC to supply power to the load. 3. The mine intrinsically safe DC uninterruptible power supply according to claim 1 or 2 is characterized in that: the voltage stabilizing circuit adopts a three-terminal adjustable voltage stabilizing tube LM317T to form a charging circuit to charge the Ni-MH battery; The input end of the three-terminal adjustable voltage regulator tube LM317T is connected to the output end of the rectifier filter circuit, and the output end of the three-terminal adjustable voltage regulator tube LM317T is connected to the battery. 4. The mine intrinsically safe DC uninterruptible power supply according to claim 3, characterized in that: the protection circuit includes an overvoltage and undervoltage protection circuit and an overcurrent protection circuit, and the overvoltage and undervoltage protection circuit includes two groups of parallel The overvoltage and undervoltage comparison circuit of the DC/DC converter XL2576 is connected to the overvoltage and undervoltage comparators respectively through the sampling circuit, and the output terminals of the two comparators are connected to the transistor switch, and the transistor switch is connected to the DC 5 pins of /DC converter XL2576; the overcurrent protection circuit includes a current transformer, a sampling circuit, a reference regulated power supply and a comparator, the reference regulated power supply provides a reference voltage and power supply for the comparator, and the output of the sampling circuit is connected to the comparator The input terminal, the output terminal of the comparator is connected to pin 5 of the DC/DC converter XL2576. 5. The intrinsically safe DC uninterruptible power supply for mining according to claim 4, characterized in that: the switching circuit includes a normally open relay K1, a normally closed relay K2, and a triode Q4; the output of the three-terminal adjustable voltage regulator LM317T The terminal is connected to the normally open relay K1 and the normally closed relay K2 through the diode D8, the normally open relay K1 controls the charging of the storage battery, the normally open relay K1 is connected to the triode Q4 under control, and the triode Q4 controls the sampling circuit whose base is connected to the output end of the voltage stabilizing circuit. The normally closed relay K2 is closed when the mains power fails, to realize the conversion of the battery for the load power supply.