Mining intrinsic safety type DC-DC conversion device

Abstract

The utility model discloses a mining intrinsic safety type DC-DC conversion device comprising a hardware circuit which comprises a single-end flyback switching power supply module, a voltage stabilization module, an overvoltage protection module and an overcurrent protection module. The single-end flyback switching power supply module comprises a PWM control module and a voltage transformation module. The overvoltage protection module comprises a first-stage protection circuit, a second-stage protection circuit and a third-stage protection circuit; the overcurrent protection module comprises a first-stage protection unit and a second-stage protection unit, the first-stage protection unit comprises a current sampling protection circuit, the second-stage protection unit comprises a gold resistor, and the gold resistor is externally connected with the output end of the hardware circuit. According to the mining intrinsic safety type DC-DC conversion device, the overvoltage protection module and the overcurrent protection module are arranged, so that the voltage and current protection requirements of the mining intrinsic safety type DC-DC conversion device are met.

Description

Technical Field

[0001] The utility model relates to the technical field of intrinsically safe power supply for coal mines, in particular to a mine intrinsically safe DC-DC conversion device. Background Art

[0002] For a conventional power supply, only a voltage stabilization feedback circuit needs to be well designed. However, in the power supply system for mine use, there are requirements different from those of conventional ones. Especially, there are significant differences in voltage stabilization accuracy, capacitive load, and overvoltage protection requirements compared with conventional DC outputs. In a mine intrinsically safe device, in addition to the voltage stabilization requirement, an overvoltage protection circuit with at least three levels is required, and a stepped voltage protection point needs to be set for each level of the protection circuit. However, the existing devices cannot well meet the relevant protection requirements. Summary of the Invention

[0003] In order to at least partially solve the problem that in a mine intrinsically safe device, an overvoltage protection circuit with at least three levels is required, and a stepped voltage protection point needs to be set for each level of the protection circuit, the utility model provides a mine intrinsically safe DC-DC conversion device. By setting a PWM control module, a voltage transformation module, a voltage stabilization module, an overvoltage protection module, and an overcurrent protection module, the voltage stabilization requirement is achieved, and three-level overvoltage protection and two-level overcurrent protection are realized.

[0004] To achieve the above object, the technical solution of the utility model is as follows:

[0005] The utility model provides a mine intrinsically safe DC-DC conversion device, including a hardware circuit, and the hardware circuit includes a flyback switching power supply module, a voltage stabilization module, an overvoltage protection module, and an overcurrent protection module;

[0006] The flyback switching power supply module includes a PWM control module and a voltage transformation module, and the output end of the PWM control module is connected to the input end of the voltage transformation module to facilitate adjusting the output voltage;

[0007] The overvoltage protection module includes a first-level protection circuit, a second-level protection circuit, and a third-level protection circuit. The output end of the first-level protection circuit is electrically connected to the input end of the second-level protection circuit, and the output end of the second-level protection circuit is electrically connected to the input end of the third-level protection circuit to facilitate realizing three-level overvoltage protection and reducing the failure rate of protection to an extremely low level;

[0008] The overcurrent protection module includes a first-level protection unit and a second-level protection unit. The first-level protection unit includes a current sampling protection circuit, and the second-level protection unit includes a gold resistor. The gold resistor is externally connected to the output end of the hardware circuit to ensure that the output current meets the requirements of mine intrinsic safety design.

[0009] Further, the PWM control module includes a UC3844 chip, and the UC3844 chip is connected to the voltage transformation module through the CS and OUTPUT serial ports, facilitating the control of the power output.

[0010] Further, the voltage transformation module includes a transformer, and the transformer includes a bobbin and a magnetic core. The bobbin includes an EFD25 bobbin, and the magnetic core is fixedly arranged on the bobbin. The magnetic core includes an EFD25 PC44 magnetic core.

[0011] Further, the voltage regulation module includes a three-terminal adjustable shunt regulator and an optocoupler. The output terminal of the three-terminal adjustable shunt regulator is connected to the input terminal of the optocoupler, ensuring the stable performance of the transformer.

[0012] Further, the first-stage protection circuit, the second-stage protection circuit, and the third-stage protection circuit all include a PMOS transistor and an optocoupler. The output terminal of the optocoupler is electrically connected to the input terminal of the PMOS transistor, realizing three-stage overvoltage protection and meeting the requirement that each protection circuit has a stepped voltage protection point.

[0013] Further, the current sampling protection circuit includes a plurality of resistors, and the plurality of resistors are connected in parallel for controlling the output current.

[0014] Further, the hardware circuit further includes a voltage protection module. The input terminal of the voltage protection module is connected to the output terminal of the flyback switching power supply module, and the output terminal of the voltage protection module is connected to the input terminal of the overvoltage protection module. The voltage protection module includes a first voltage protection unit, a second voltage protection unit, and a third voltage protection unit. The first voltage protection unit, the second voltage protection unit, and the third voltage protection unit all include a thyristor and a voltage regulator tube. The output terminal of the thyristor is connected to the input terminal of the voltage regulator tube for further realizing voltage protection.

[0015] Advantages of the present utility model:

[0016] (1) The present utility model realizes the voltage stability during power supply through the proposed PWM control module, voltage transformation module, and voltage regulation module, making its voltage regulation accuracy meet the requirements of mine use.

[0017] (2) The present utility model realizes three-stage overvoltage protection through the proposed overvoltage protection module, and each protection circuit has a stepped voltage protection point.

[0018] (3) The present utility model realizes two-stage protection against overcurrent through the proposed overcurrent protection module, ensuring the stability of the current. Description of the Drawings

[0019] Figure 1One of the electrical schematic diagrams of a mine intrinsically safe DC-DC conversion device provided by an embodiment of the present utility model.

[0020] Figure 2 Two of the electrical schematic diagrams of a mine intrinsically safe DC-DC conversion device provided by an embodiment of the present utility model.

[0021] Figure 3 Schematic diagram of a transformer of a mine intrinsically safe DC-DC conversion device provided by an embodiment of the present utility model.

[0022] Figure 4 Three of the electrical schematic diagrams of a mine intrinsically safe DC-DC conversion device provided by an embodiment of the present utility model.

[0023] Figure 5 Four of the electrical schematic diagrams of a mine intrinsically safe DC-DC conversion device provided by an embodiment of the present utility model.

[0024] Figure 6 Five of the electrical schematic diagrams of a mine intrinsically safe DC-DC conversion device provided by an embodiment of the present utility model.

[0025] Figure 7 Six of the electrical schematic diagrams of a mine intrinsically safe DC-DC conversion device provided by an embodiment of the present utility model.

[0026] Figure 8 Seven of the electrical schematic diagrams of a mine intrinsically safe DC-DC conversion device provided by an embodiment of the present utility model.

[0027] Figure 9 Eight of the electrical schematic diagrams of a mine intrinsically safe DC-DC conversion device provided by an embodiment of the present utility model.

[0028] The reference numerals in the drawings are: 1 is a PWM control module, 2 is a voltage transformation module, 3 is a voltage stabilization module, 4 is an overvoltage protection module, 5 is an overcurrent protection module, 6 is a voltage protection module, 7 is a flyback switching power supply module, 8 is a first-stage protection circuit, 9 is a second-stage protection circuit, 10 is a third-stage protection circuit, 11 is a current sampling protection circuit, 12 is a three-terminal adjustable shunt regulator, and 13 is a gold resistor. Detailed implementation manners

[0029] To make the objectives, technical solutions, and advantages of the present utility model clearer, the following will clearly describe the technical solutions in the embodiments of the present utility model with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0030] Embodiment 1

[0031] As Figures 1-9 shown, a mine intrinsically safe DC-DC conversion device includes a hardware circuit, and the hardware circuit includes a single-ended flyback switching power supply module 7, a voltage stabilizing module 3, an overvoltage protection module 4, and an overcurrent protection module 5.

[0032] Preferably, the input signal of a mine intrinsically safe DC-DC conversion device designed by the present utility model is 24V (18~36V), the output is 2 channels of 18V or 2 channels of 12V, and the maximum working current is 1.5A.

[0033] The single-ended flyback switching power supply module 7 includes a PWM control module 1 and a voltage transformation module 2, and the output end of the PWM control module 1 is connected to the input end of the voltage transformation module 2. Specifically, the PWM control module 1 includes a UC3844 chip. Using the PWM control module 1 as a switching device for the circuit of a mine intrinsically safe DC-DC conversion device, by working indirectly periodically, the duty cycle of the switching device is controlled to adjust the output voltage. The single-ended flyback switching power supply module 7 is a power supply circuit with the lowest cost, the output power is 20W~100W, the working frequency is between 20kHz~200kHz, different voltages can be output simultaneously, and it has a good voltage regulation rate.

[0034] The UC3844 chip is connected to the voltage transformation module 2 through the CS and OUTPUT serial ports. The voltage transformation module 2 includes a transformer, and the design of the transformer is determined by the requirements of conversion efficiency and the withstand voltage of the intrinsically safe and non-intrinsically safe ends. The present utility model adopts the connection method of an adjustable precision shunt regulator plus an optocoupler, specifically using a three-terminal adjustable shunt regulator of the TL431 model plus an optocoupler of the PC817 model. This method has a very high control accuracy and stable performance because a precision voltage source is used as the control reference voltage. The transformer includes a skeleton and a magnetic core. The skeleton includes an EFD25 skeleton, and a magnetic core is fixedly arranged on the skeleton. The magnetic core includes an EFD25PC44 magnetic core, and the transformer is horizontally packaged.

[0035] The output end of the voltage transformation module 2 is connected to the input end of the overvoltage protection module 4. The overvoltage protection module 4 includes a first-stage protection circuit 8, a second-stage protection circuit 9, and a third-stage protection circuit 10. The output end of the first-stage protection circuit 8 is electrically connected to the input end of the second-stage protection circuit 9, and the output end of the second-stage protection circuit 9 is electrically connected to the input end of the third-stage protection circuit 10. Specifically, the first-stage protection circuit 8, the second-stage protection circuit 9, and the third-stage protection circuit 10 all include a PMOS transistor and an optocoupler, and the output end of the optocoupler is electrically connected to the input end of the PMOS transistor. The working sequence of the three-stage overvoltage protection is set as follows: the protection voltage of the first-stage protection circuit 8 is 18.1V, the protection voltage of the second-stage protection circuit 9 is 18.3V, and the protection voltage of the third-stage protection circuit 10 is 18.5V. When the first-stage protection circuit fails, the second-stage protection circuit 9 can be quickly started. When the second-stage protection circuit 9 fails, the third-stage protection circuit 10 can also be quickly started, which can reduce the failure rate of protection to an extremely low level.

[0036] Preferably, the hardware circuit further includes a voltage protection module 6. The input end of the voltage protection module 6 is connected to the output end of the flyback switching power supply module 7, and the output end of the voltage protection module 6 is connected to the input end of the overvoltage protection module 4. The voltage protection module 6 includes a first voltage protection unit, a second voltage protection unit, and a third voltage protection unit. The first voltage protection unit, the second voltage protection unit, and the third voltage protection unit all include a thyristor and a zener diode, and the output end of the thyristor is connected to the input end of the zener diode. Finally, once the overvoltage protection module 4 fails, the voltage protection module 6 will short-circuit the thyristor to the ground, so that the output and the ground wire are short-circuited, which will force the input fuse to blow, thus achieving the purpose of protection.

[0037] The overcurrent protection module 5 is connected to the PWM control module 1 through the CS serial port. The overcurrent protection module 5 includes a first-stage protection unit and a second-stage protection unit. The first-stage protection unit includes a current sampling protection circuit 11. Specifically, the first-stage protection unit uses the current sampling protection circuit 11 of the MOS transistor in the PWM control module 1 for overcurrent protection. The current sampling protection circuit 11 includes three 0.33R sampling resistors, and the three sampling resistors are connected in parallel.

[0038] The second-stage protection unit includes a gold resistor 13, and the gold resistor 13 is externally connected to the output end of the hardware circuit. Specifically, the second-stage protection unit adopts the method of connecting a 16-ohm 75W gold resistor 13 in series outside the output end of the hardware circuit, so that the maximum working current is limited to 1.125A, which can ensure that the output meets the requirements of the mine intrinsically safe design under the most stringent conditions.

[0039] The voltage stabilization module 3 is serially connected to the PWM control module 1 through the VF and VREF serial ports. The voltage stabilization module 3 includes a three-terminal adjustable shunt regulator 12 and an optocoupler. The output terminal of the three-terminal adjustable shunt regulator 12 is connected to the input terminal of the optocoupler. Preferably, an adjustable precision shunt regulator plus an optocoupler connection method is adopted, specifically using a three-terminal adjustable shunt regulator 12 of the TL431 model plus an optocoupler of the PC817 model. Since this method uses a precision voltage source as the control reference voltage, the control accuracy is very high and the performance is stable.

[0040] Embodiment 2

[0041] In actual application, the PWM control module 1 is used to control the output voltage and adjust it to an appropriate value. Then, the voltage transformation module 2 and the voltage stabilization module 3 are used to further adjust the single output voltage and perform voltage stabilization operations, so that the voltage output by the flyback switching power supply module 7 meets the requirements and ensures the stability of the voltage.

[0042] When the voltage output by the flyback switching power supply module 7 is too high, the overvoltage protection module 4 will start to work, and the maximum output voltage can be controlled by adjusting the potentiometer. When the voltage is greater than 18.1V, the first-stage protection circuit 8 will fail, and then the second-stage protection circuit 9 will start to work. When the voltage is greater than 18.5V, the second-stage protection circuit 9 will fail, and the third-stage protection circuit 10 will start to work, ensuring that the voltage will not be too large and reducing the protection failure rate to an extremely low level.

[0043] The overcurrent protection module 5 will prevent the current in the circuit from being too large. The magnitude of the current is restricted by the first-stage protection unit, and then the maximum current is restricted by the second-stage protection unit, so that the output can meet the requirements of the intrinsically safe design for mine use under the most stringent conditions.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. However, such modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A mine intrinsically safe DC-DC converter, characterized in that: The hardware circuit comprises a single-ended flyback switching power supply module (7), a voltage stabilization module (3), an overvoltage protection module (4) and an overcurrent protection module (5); The single-ended flyback switching power supply module (7) comprises a PWM control module (1) and a voltage conversion module (2), wherein the output end of the PWM control module (1) is connected to the input end of the voltage conversion module (2); The overvoltage protection module (4) comprises a first-level protection circuit (8), a second-level protection circuit (9) and a third-level protection circuit (10), wherein the output end of the first-level protection circuit (8) is electrically connected to the input end of the second-level protection circuit (9), and the output end of the second-level protection circuit (9) is electrically connected to the input end of the third-level protection circuit (10); The overcurrent protection module (5) comprises a first-level protection unit and a second-level protection unit, the first-level protection unit comprises a current sampling protection circuit (11), the second-level protection unit comprises a golden resistor (13), and the golden resistor (13) is externally connected to the output end of the hardware circuit.

2. A mining intrinsically safe DC-DC converter according to claim 1, characterized in that: The PWM control module (1) comprises a UC3844 chip, and the UC3844 chip is connected to the voltage conversion module (2) via CS and OUTPUT serial ports.

3. A mining intrinsically safe DC-DC converter according to claim 1, characterized in that: The transformer module (2) comprises a transformer, the transformer comprises a skeleton and a magnetic core, the skeleton comprises an EFD25 skeleton, a magnetic core is fixedly arranged on the skeleton, and the magnetic core comprises an EFD25 PC44 magnetic core.

4. A mining intrinsically safe DC-DC converter according to claim 1, characterized in that: The voltage stabilizing module (3) comprises a three-terminal adjustable shunt shunt regulator (12) and an optical coupler, wherein the output end of the three-terminal adjustable shunt shunt regulator (12) is connected to the input end of the optical coupler.

5. A mining intrinsically safe DC-DC converter according to claim 1, characterized in that: The first-level protection circuit (8), the second-level protection circuit (9) and the third-level protection circuit (10) all comprise a PMOS tube and an optical coupler, and the output end of the optical coupler is electrically connected to the input end of the PMOS tube.

6. A mining intrinsically safe DC-DC converter according to claim 1, characterized in that: The current sampling protection circuit (11) comprises a plurality of resistors, and the plurality of resistors are connected in parallel.

7. A mining intrinsically safe DC-DC converter according to claim 1, characterized in that: The hardware circuit further comprises a voltage protection module (6), the input end of the voltage protection module (6) being connected to the output end of the single-ended flyback switching power supply module (7), the output end of the voltage protection module (6) being connected to the input end of the overvoltage protection module (4), the voltage protection module (6) comprising a voltage protection unit 1, a voltage protection unit 2 and a voltage protection unit 3, the voltage protection unit 1, the voltage protection unit 2 and the voltage protection unit 3 all comprising a thyristor and a voltage regulator, the output end of the thyristor being connected to the input end of the voltage regulator.

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