A processing system and method for dealing with line leakage in DC lighting power supply

Abstract

The present invention relates to a processing system and method for dealing with line leakage in DC lighting power supply. A DC power supply cabinet, a power supply cable, a DC-DC driver and a lamp constitute a processing system for dealing with line leakage in a DC lighting power supply system. The DC-DC driver converts the input DC power into the voltage and current required by the lamp. The DC-DC driver includes an MCU microprocessor and an input voltage detection circuit, a PWM conversion circuit, a PWM control circuit, an input-end fault feedback circuit and an output-end fault feedback control circuit connected to the MCU microprocessor. Since the DC system is sensitive in protection, line leakage can easily cause overload protection of the DC system, resulting in lamp extinguishing. The present invention detects the input voltage by a DC-DC driver, adaptively adjusts the output power, and reduces the load change of the DC power cabinet by reducing the load power of the lamp when the line leaks, thereby greatly reducing the probability of its overload protection.

Description

Technical Field

[0001] The invention relates to a highway tunnel lighting power supply system, and in particular to a processing system and method for dealing with line leakage in direct current lighting power supply. Background Art

[0002] In existing highway tunnel lighting, DC power supply has gradually become the development trend of current highway tunnel lighting power supply because of its advantages of safety, energy saving, intelligence, and the ability to easily connect to photovoltaic and other energy storage power supply systems.

[0003] In DC lighting, the insulation requirements for the line are relatively high. Since there are many line nodes and the working environment is complex and harsh, small current leakage often occurs in the line. If the insulation is reduced, there is a risk of electric shock on the one hand, and it will also cause a waste of electricity on the other hand. At the same time, due to the high sensitivity of DC system protection, poor insulation can easily cause the system protection to malfunction, resulting in the lights going out, thus posing a traffic safety hazard.

[0004] To address line insulation issues, the main measure currently in place is to monitor the insulation of the lines. However, this is only a means of detection and early warning, and cannot address the increased load and system protection issues caused by leakage due to poor insulation.

[0005] Therefore, it is necessary to propose a system and method that can adaptively reduce load, so as to ensure that the DC system does not shut down for protection as much as possible while the line insulation monitoring alarm is sounded, and to ensure that the tunnel lighting is normally on. Summary of the invention

[0006] In view of the above-mentioned existing DC power supply system, the insulation monitoring function only has an early warning function. After the early warning, before the fault point is manually eliminated, the branch with poor insulation is directly shut down to ensure that the entire system can still supply power normally, which will cause the lamps loaded in this branch to turn off. The present invention provides a system for dealing with line leakage in DC lighting power supply and a method for dealing with line leakage in DC lighting power supply using the system, the purpose of which is to adaptively reduce the brightness of the leakage branch load lamps when the leakage current is not large due to poor insulation, and ensure that the branch can still light up before the subsequent manual troubleshooting of the fault point.

[0007] In order to achieve the above object, the present invention adopts the following technical solution.

[0008] The present invention first provides a processing system for dealing with line leakage in a DC lighting power supply for a highway tunnel lighting system that is applied to a DC-powered system. The lighting system comprises a plurality of lamps, a DC power supply cabinet for outputting DC power, and a power supply cable for transmitting DC power to the lamps. A DC-DC driver is arranged on a connection line between the DC power supply cabinet and the lamps. The DC-DC driver comprises an MCU microprocessor and an input voltage detection circuit, a PWM conversion circuit, a PWM control circuit, an input-end fault feedback circuit, and an output-end fault feedback control circuit connected to the MCU microprocessor. The lighting system is provided with a plurality of lamps, and a DC-DC driver is arranged on a connection line between each lamp group and the DC power supply cabinet. The DC-DC driver converts the DC power input by the DC power supply cabinet into the voltage and current required by the lamps, detects the input voltage, and adaptively adjusts the output power, thereby forming a processing system for dealing with line leakage in the DC lighting power supply.

[0009] Preferably, the DC-DC driver further comprises an input and filtering circuit connected to the DC input terminal, and an output rectification and filtering circuit connected to the voltage output terminal, and the PWM conversion circuit is arranged between the input and filtering circuit and the output rectification and filtering circuit.

[0010] In any of the above technical solutions, it is preferred that the DC-DC driver also includes a protection circuit and an isolation circuit I, the protection circuit is connected to the PWM control circuit, one end of the isolation circuit I is connected to the PWM control circuit, and the other end is connected to the output fault feedback control circuit, and the output fault feedback control circuit is arranged between the MCU microcontroller and the voltage output terminal.

[0011] In any of the above technical solutions, preferably, the DC-DC driver further includes an isolation circuit II, and the isolation circuit II is arranged between the MCU microcontroller and the input fault feedback circuit.

[0012] In any of the above technical solutions, preferably, the DC-DC driver further includes an isolation circuit III, and the isolation circuit III is arranged between the input voltage detection circuit and the MCU microcontroller.

[0013] In any of the above technical solutions, preferably, one end of the input voltage detection circuit is connected to the isolation circuit III, and the other end is connected to the input fault feedback circuit and the input and filtering circuit.

[0014] In any of the above technical solutions, it is preferred that one end of the PWM control circuit is connected to the protection circuit and the isolation circuit I, and the other end is connected to the PWM conversion circuit.

[0015] The present invention also provides a method for processing line leakage in DC lighting power supply, using the system for processing line leakage in DC lighting power supply as described in any one of the above items to process line leakage in DC lighting power supply, the method comprising:

[0016] The DC power supply cabinet, power supply cables, DC-DC drivers and lamps constitute a system for dealing with line leakage in the DC lighting power supply system. The DC power supply cabinet outputs DC power, the power supply cables are responsible for transmitting DC power, the DC-DC drivers and lamps serve as loads, and the DC-DC drivers convert the input DC power into the voltage and current required by the lamps. The DC-DC drivers include an MCU microprocessor and an input voltage detection circuit, a PWM conversion circuit, a PWM control circuit, an input fault feedback circuit and an output fault feedback control circuit connected to the MCU microprocessor.

[0017] The DC-DC driver detects the input voltage and records the stable input voltage value under the current good insulation state of the line. When the line has poor insulation and leakage, and the line leakage is within the output current range of the DC power supply cabinet, it is equivalent to that the DC power supply cabinet not only has the lamp load, but also has the added load of line leakage, which can easily trigger the overload protection and cause the lamp to go out. Based on this, when the line insulation is good, each DC-DC driver in the system records the input voltage under this state. When the line insulation is poor and leakage occurs, the system increases the load, the load current increases, and the line voltage drop increases accordingly. Then the input voltage of each DC-DC driver at this time becomes lower than the input voltage recorded before when the line insulation is good. According to the difference, the DC-DC driver reduces the output current in a certain proportion, so that the current of the entire load lamp becomes smaller. At this time, for the DC power supply cabinet, the lamp load becomes smaller and the line leakage current increases. The entire load change is equal to the lamp load plus the line leakage. With one increase and one decrease, the entire load change value is greatly reduced, and the possibility of overload protection is reduced.

[0018] The DC-DC driver has an input voltage detection circuit. In a DC power supply system with a DC power supply cabinet of 290Vdc, its output current dimming ratio changes automatically with the input voltage;

[0019] In the input voltage range of 260Vdc ~ 290Vdc, the dimming ratio of the DC-DC driver remains at 100% and does not change with the input voltage. When the line has poor insulation and causes the DC-DC driver input voltage to drop below 260V, its output dimming ratio decreases with the decrease in input voltage. When the input voltage is only 200V, the DC-DC driver shuts down directly. At this time, the line leakage current is too large and power-off protection is implemented.

[0020] Compared with the prior art, the above technical solution of the present invention has the following beneficial effects:

[0021] Since the DC system is sensitive to protection, line leakage can easily cause overload protection of the DC system, resulting in lamp extinguishing. The present invention uses a DC-DC driver to detect input voltage and adaptively adjust output power. When the line leaks, the load power of the lamp is reduced, so that the load change of the DC power cabinet is reduced, and the probability of overload protection is greatly reduced. At this time, the lamp in the leakage shunt is still lit normally, but the brightness of the lamp will decrease accordingly because the dimming reduces the current value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0023] Figure 1 A schematic diagram of the system structure of a preferred embodiment of a system for dealing with line leakage in DC lighting power supply according to the present invention;

[0024] Figure 2 A schematic diagram of the DC-DC driver structure and working principle of a preferred embodiment of a system for dealing with line leakage in DC lighting power supply according to the present invention;

[0025] Figure 3 The figure is a schematic diagram of a DC-DC driver load reduction curve according to a preferred embodiment of the system for dealing with line leakage in DC lighting power supply of the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the existing DC power supply system, the insulation monitoring function only has an early warning function. After the early warning, before the fault point is manually eliminated, the branch with poor insulation is directly shut down to ensure that the entire system can still supply power normally, which will cause the lamps loaded in this branch to turn off. The embodiment of the present invention provides a system for dealing with line leakage in DC lighting power supply and a method for dealing with line leakage in DC lighting power supply using the system. The purpose is to adaptively reduce the brightness of the leakage branch load lamp when the leakage current is not large due to poor insulation, and ensure that the branch can still light up before the subsequent manual troubleshooting of the fault point.

[0028] The following combination Figures 1 to 3 , explaining the principles, technical features and specific processing procedures of the system for dealing with line leakage in DC lighting power supply described in this embodiment.

[0029] The lighting system includes a plurality of lamps, a DC power supply cabinet for outputting DC power, and a power supply cable for transmitting DC power to the lamps. The processing system for dealing with line leakage in the DC lighting power supply described in this embodiment is as follows: Figure 1 As shown, a DC-DC driver is arranged on the connection line between the DC power supply cabinet and the lamp; the DC-DC driver includes an MCU microprocessor and an input voltage detection circuit, a PWM conversion circuit, a PWM control circuit, an input end fault feedback circuit and an output end fault feedback control circuit connected to the MCU microprocessor; a plurality of groups of lamps are arranged in the lighting system, and a DC-DC driver is arranged on the connection line between each group of lamps and the DC power supply cabinet. The DC-DC driver converts the DC power input by the DC power supply cabinet into the voltage and current required by the lamp, detects the input voltage and adaptively adjusts the output power, and constitutes a processing system for dealing with line leakage in the DC lighting power supply.

[0030] The processing system described in this embodiment is as follows: Figure 1 As shown, the DC-DC driver also includes an input and filtering circuit connected to the DC input terminal, and an output rectification and filtering circuit connected to the voltage output terminal, and the PWM conversion circuit is arranged between the input and filtering circuit and the output rectification and filtering circuit.

[0031] The processing system described in this embodiment is as follows: Figure 1 As shown, the DC-DC driver also includes a protection circuit and an isolation circuit I; the protection circuit is connected to the PWM control circuit; one end of the isolation circuit I is connected to the PWM control circuit, and the other end is connected to the output fault feedback control circuit, and the output fault feedback control circuit is arranged between the MCU microcontroller and the voltage output end.

[0032] The processing system described in this embodiment is as follows: Figure 1 As shown, the DC-DC driver further includes an isolation circuit II, and the isolation circuit II is arranged between the MCU microcontroller and the input fault feedback circuit.

[0033] The processing system described in this embodiment is as follows: Figure 1 As shown, the DC-DC driver further includes an isolation circuit III, and the isolation circuit III is arranged between the input voltage detection circuit and the MCU microcontroller.

[0034] In the processing system described in this embodiment, if Figure 1 As shown, one end of the input voltage detection circuit is connected to the isolation circuit III, and the other end is connected to the input fault feedback circuit and the input and filtering circuit.

[0035] In the processing system described in this embodiment, if Figure 1 As shown, one end of the PWM control circuit is connected to the protection circuit and the isolation circuit I, and the other end is connected to the PWM conversion circuit.

[0036] Typical DC lighting power supply system such as Figure 1 As shown in the schematic diagram, its components include a DC power supply cabinet, power supply cables, lamps, and a DC-DC driver; the DC power supply cabinet outputs DC power, the power supply cable is responsible for transmitting DC power, the DC-DC driver and the lamp are used as loads, and the DC-DC driver is used to convert the input DC power into the voltage and current required by the lamp, so as to realize the processing of line leakage in DC lighting power supply.

[0037] Since the power supply cable has resistance, a line voltage drop is formed when current passes through it. Therefore, the closer the DC-DC driver is to the DC power supply cabinet, the higher the input DC voltage is, and the farther the DC-DC driver is, the lower the DC input voltage is. When the power supply cable is well insulated, since the DC power supply cabinet voltage, power supply cable resistance (voltage drop), and load lamps remain unchanged, the input voltage of each DC-DC driver also remains stable. The DC-DC driver has the function of detecting input voltage, and at this time, each can record the stable input voltage value when the current line insulation is good.

[0038] In specific implementation, when the line has poor insulation and leakage, there are three situations:

[0039] Case 1: The line leakage is slight (the leakage current is at the milliampere level). In this case, the insulation monitoring function will trigger an alarm. However, since the leakage current is very small, it will not cause protection of the DC power supply cabinet (but the leakage involves personal electric shock safety and still needs to be investigated and handled as soon as possible).

[0040] Case 2: The line leakage is serious and almost short-circuited. At this time, due to the sharp increase in load current, it will directly trigger the overcurrent or short-circuit protection, or even trigger the protection switch. The light is inevitably turned off.

[0041] Case 3: The line leakage is within the output current range of the DC power supply cabinet. In this case, the DC power supply cabinet not only has the lamp load, but also has the added load of line leakage, which can easily trigger the overload protection and cause the light to go out.

[0042] For situation 3, the technical measures adopted by the present invention are: when the line insulation is good, each DC-DC driver records the input voltage in this state. When the line insulation is poor and leakage occurs, it is equivalent to the system increasing the load, the load current increases, and the line voltage drop increases accordingly. For each DC-DC driver, the input voltage at this time becomes lower than the input voltage previously recorded when the line insulation was good. According to the difference, the DC-DC driver can reduce the output current in a certain proportion, thereby reducing the current of the entire load lamp. At this time, for the DC power supply cabinet, the lamp load becomes smaller and the line leakage current increases. The entire load change is equal to the lamp load plus the line leakage. With one increase and one decrease, the entire load change value is greatly reduced, and the possibility of overload protection is reduced.

[0043] Since the DC system is sensitive to protection, line leakage can easily cause overload protection of the DC system, resulting in lamp extinguishing. The present invention detects the input voltage through the DC-DC driver and adaptively adjusts the output power. When the line leaks, the load power of the lamp is reduced, so that the load change of the DC power cabinet is reduced, and the probability of overload protection is greatly reduced.

[0044] At this time, the lamps in the leakage shunt circuit will still light up normally, but because the dimming reduces the current value, the brightness of the lamps will decrease accordingly.

[0045] In the specific implementation, Figure 2 As shown, in the DC-DC driver, an input voltage detection circuit is designed. In a DC power supply system with a DC power supply cabinet of 290Vdc, its output current dimming ratio is, for example, Figure 3 The display changes automatically with input voltage.

[0046] Since the DC power supply design standard allows a maximum voltage drop of 10% in the input voltage, the dimming ratio of the DC-DC driver remains at 100% within the input voltage range of 260Vdc to 290Vdc, and does not change with the input voltage (Note: it still responds to the dimming command at this time). When the line has poor insulation and causes the input voltage of the DC-DC driver to drop below 260V, its output dimming ratio decreases with the decrease in input voltage. When the input voltage is only 200V, the DC-DC driver directly shuts down. At this time, the line leakage current is too large and power must be cut off for protection.

[0047] The above description is only a description of the preferred implementation mode of the present invention, and is not intended to limit the scope of the present invention; the above description is only a specific implementation mode of the present invention, and is not intended to limit the protection scope of the present invention; without departing from the design spirit of the present invention, any modification, equivalent substitution, improvement, etc. made to the technical solution of the present invention by ordinary engineering and technical personnel in this field shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A system for dealing with line leakage in DC lighting power supply, applied to a DC-powered highway tunnel lighting system, the lighting system comprising a plurality of lamps, a DC power supply cabinet for outputting DC power, and a power supply cable for transmitting DC power to the lamps, characterized in that: A DC-DC driver is arranged on the connection line between the DC power supply cabinet and the lamp; the DC-DC driver includes an MCU microprocessor and an input voltage detection circuit, a PWM conversion circuit, a PWM control circuit, an input end fault feedback circuit and an output end fault feedback control circuit connected to the MCU microprocessor; the lighting system is provided with multiple groups of lamps, and a DC-DC driver is arranged on the connection line between each group of lamps and the DC power supply cabinet. The DC-DC driver converts the DC power input by the DC power supply cabinet into the voltage and current required by the lamp, detects the input voltage and adaptively adjusts the output power, and constitutes a processing system for dealing with line leakage in DC lighting power supply; The DC-DC driver detects the input voltage and records the stable input voltage value under the current good insulation state of the line. When the line has poor insulation and leakage, and the line leakage is within the output current range of the DC power supply cabinet, it is equivalent to that the DC power supply cabinet not only has the lamp load, but also has the added load of line leakage, which can easily trigger the overload protection and cause the lamp to go out. Based on this, when the line insulation is good, each DC-DC driver in the system records the input voltage under this state. When the line insulation is poor and leakage occurs, the system increases the load, the load current increases, and the line voltage drop increases accordingly. Then the input voltage of each DC-DC driver at this time becomes lower than the input voltage recorded before when the line insulation is good. According to the difference, the DC-DC driver reduces the output current in a certain proportion, so that the current of the entire load lamp becomes smaller. At this time, for the DC power supply cabinet, the lamp load becomes smaller and the line leakage current increases. The entire load change is equal to the lamp load plus the line leakage. With one increase and one decrease, the entire load change value is greatly reduced, and the possibility of overload protection is reduced. The DC-DC driver has an input voltage detection circuit. In a DC power supply system with a DC power supply cabinet of 290Vdc, its output current dimming ratio changes automatically with the input voltage; In the input voltage range of 260Vdc ~ 290Vdc, the dimming ratio of the DC-DC driver remains at 100% and does not change with the input voltage. When the line has poor insulation and causes the DC-DC driver input voltage to drop below 260V, its output dimming ratio decreases with the decrease in input voltage. When the input voltage is only 200V, the DC-DC driver shuts down directly. At this time, the line leakage current is too large and power-off protection is implemented.

2. The system for dealing with line leakage in DC lighting power supply according to claim 1, characterized in that: The DC-DC driver also includes an input and filtering circuit connected to the DC input terminal, and an output rectification and filtering circuit connected to the voltage output terminal. The PWM conversion circuit is arranged between the input and filtering circuit and the output rectification and filtering circuit.

3. The system for dealing with line leakage in DC lighting power supply according to claim 2, characterized in that: The DC-DC driver further includes a protection circuit and an isolation circuit I.

4. The system for dealing with line leakage in DC lighting power supply according to claim 3, characterized in that: The protection circuit is connected to the PWM control circuit.

5. The system for dealing with line leakage in DC lighting power supply according to claim 3, characterized in that: One end of the isolation circuit I is connected to the PWM control circuit, and the other end is connected to the output fault feedback control circuit, and the output fault feedback control circuit is arranged between the MCU microcontroller and the voltage output end.

6. The system for dealing with line leakage in DC lighting power supply according to claim 3, characterized in that: The DC-DC driver further includes an isolation circuit II, which is arranged between the MCU microcontroller and the input fault feedback circuit.

7. The system for dealing with line leakage in DC lighting power supply according to claim 6, characterized in that: The DC-DC driver further includes an isolation circuit III, and the isolation circuit III is arranged between the input voltage detection circuit and the MCU microcontroller.

8. The system for dealing with line leakage in DC lighting power supply according to claim 1, characterized in that: One end of the input voltage detection circuit is connected to the isolation circuit III, and the other end is connected to the input fault feedback circuit and the input and filtering circuit.

9. The system for dealing with line leakage in DC lighting power supply according to claim 1, characterized in that: One end of the PWM control circuit is connected to the protection circuit and the isolation circuit I, and the other end is connected to the PWM conversion circuit.

10. A method for dealing with line leakage in DC lighting power supply, using the system for dealing with line leakage in DC lighting power supply as claimed in any one of claims 1 to 9, characterized in that: The method includes: The DC power supply cabinet, power supply cables, DC-DC drivers and lamps constitute a system for dealing with line leakage in the DC lighting power supply system. The DC power supply cabinet outputs DC power, the power supply cables are responsible for transmitting DC power, the DC-DC drivers and lamps serve as loads, and the DC-DC drivers convert the input DC power into the voltage and current required by the lamps. The DC-DC drivers include an MCU microprocessor and an input voltage detection circuit, a PWM conversion circuit, a PWM control circuit, an input fault feedback circuit and an output fault feedback control circuit connected to the MCU microprocessor. The DC-DC driver detects the input voltage and records the stable input voltage value under the current good insulation state of the line. When the line has poor insulation and leakage, and the line leakage is within the output current range of the DC power supply cabinet, it is equivalent to that the DC power supply cabinet not only has the lamp load, but also has the added load of line leakage, which can easily trigger the overload protection and cause the lamp to go out. Based on this, when the line insulation is good, each DC-DC driver in the system records the input voltage under this state. When the line insulation is poor and leakage occurs, the system increases the load, the load current increases, and the line voltage drop increases accordingly. Then the input voltage of each DC-DC driver at this time becomes lower than the input voltage recorded before when the line insulation is good. According to the difference, the DC-DC driver reduces the output current in a certain proportion, so that the current of the entire load lamp becomes smaller. At this time, for the DC power supply cabinet, the lamp load becomes smaller and the line leakage current increases. The entire load change is equal to the lamp load plus the line leakage. With one increase and one decrease, the entire load change value is greatly reduced, and the possibility of overload protection is reduced. The DC-DC driver has an input voltage detection circuit. In a DC power supply system with a DC power supply cabinet of 290Vdc, its output current dimming ratio changes automatically with the input voltage; In the input voltage range of 260Vdc ~ 290Vdc, the dimming ratio of the DC-DC driver remains at 100% and does not change with the input voltage. When the line has poor insulation and causes the DC-DC driver input voltage to drop below 260V, its output dimming ratio decreases with the decrease in input voltage. When the input voltage is only 200V, the DC-DC driver shuts down directly. At this time, the line leakage current is too large and power-off protection is implemented.

Images