JP2023058935A - Illumination system - Google Patents

Abstract

To provide an illumination system for supplying DC power to a plurality of luminaires, the illumination system being capable of performing lighting control of the luminaires depending on variations in supply voltage.SOLUTION: An illumination system 1 comprises: a DC power supply unit for supplying DC power; DC power supply lines 3A, 3B connected to its output end; and a plurality of luminaires 4A to 4C connected in parallel to the lines. The luminaire 4A includes: an LED row in which a plurality of LEDs are connected; and a control circuit for performing lighting control of the LED row depending on variations in supply voltage from the DC power supply unit to the LED row. The DC power supply unit is a combination of AC-DC conversion units 2A, 2B for converting AC power to DC power and renewable energy power supplies 5, 6. When supply voltage of the power supplies 5, 6 has been varied, lighting control of the LED row is performed depending on the variation. In changeover of a supply source of power between the renewable energy power supplies 5, 6 and the AC-DC conversion units 2A, 2B, the changeover is performed smoothly without interruption of supply power.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a lighting system for supplying DC power to a plurality of lighting fixtures, and more particularly to lighting fixtures having a dimming function.

The Intergovernmental Panel on Climate Change has set a goal of reducing greenhouse gas (CO ₂ ) emissions to virtually zero by 2050, and various technological developments are being made in accordance with this goal. Light-emitting diodes (LEDs) have hitherto been widely used for the lighting of roads and public facilities that support social infrastructure due to their advantages such as low power consumption and long life, but further technical development is required.

Since semiconductor light-emitting elements such as LEDs emit light using DC power, the power supply system for multiple lighting fixtures such as street lights, tunnel lighting, and ceiling lighting can be replaced with a DC power supply system from the conventional AC power supply system. (hereinafter referred to as a DC power supply system) is being studied (see Patent Document 1). In other words, a system in which a common DC power supply unit is provided, commercial AC power is converted into DC power by the DC power supply unit, and the converted DC power is supplied to a plurality of lighting fixtures via positive and negative power supply lines. is.

DC power supply systems are more compatible with renewable energy. No power loss is expected. Similarly, when a storage battery is used for backup during a power outage, there is also an expectation that the DC power of the storage battery can be supplied as it is.
In addition, in the conventional AC power supply system, in order to switch from AC power to DC power in the storage battery during a power failure, it is necessary to detect the disconnection from the AC power supply and then connect to the storage battery. It turns off temporarily. On the other hand, in the DC power supply system, constant connection with the storage battery is possible, and it can be expected to avoid temporary turning off during power failure.

On the other hand, due to the characteristics of LEDs, the flowing current fluctuates greatly in response to slight fluctuations in the applied DC voltage or temperature. It avoids deterioration of the light quality of lighting fixtures and breakage of LEDs. For example, the lighting system of Patent Document 1 includes a DC power supply unit, a positive electrode side and a negative electrode side DC power supply line connected thereto, and a plurality of lighting fixtures connected in parallel to the DC power supply line. is provided with a constant current circuit that keeps the LED current constant by operating a switching element that repeats on and off at high speed.

JP 2011-77009 A

The inventors paid attention to the fact that the DC power supply system is originally characterized by a large allowable range of voltage fluctuations, and when the voltage supplied from the DC power supply to the lighting equipment changes, the lighting equipment changes according to the change. We have been working hard to develop a lighting system that can make effective use of renewable energy, such as by linking the illuminance of lighting fixtures to changes in the surrounding environment (such as the amount of sunlight) if we can control the brightness of the lights. However, the constant current circuit of Patent Document 1 detects the LED current value from a current detection resistor connected in series with the LED, and adjusts the duty of the switching element so that this current value becomes a predetermined value. Even if the supply voltage from the power supply is increased or decreased, the LED current is only controlled to be constant, and the illuminance of the plurality of LEDs cannot be changed according to the supply voltage.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a lighting system that supplies DC power to a plurality of lighting fixtures, in which the lighting fixtures can be dimmed according to changes in the supply voltage.

The inventors have succeeded in developing a control circuit for dimming a semiconductor light-emitting element according to changes in the voltage supplied from a DC power supply unit, and have completed the present invention. That is, the lighting system according to the present invention is
a DC power supply unit that supplies DC power;
a DC power supply line connected to the output terminal of the DC power supply;
A plurality of lighting fixtures connected in parallel to the DC power supply line,
The lighting fixture is
a light emitting element array in which a plurality of semiconductor light emitting elements are connected;
and a control circuit for dimming the light emitting element array according to a change in the voltage supplied from the DC power supply to the light emitting element array.
Here, it is preferable that the DC power supply unit has an AC/DC conversion unit that converts AC power into DC power, a renewable energy power supply, a storage battery, or a combination thereof.

When the lighting system having the above configuration is used, when the supply voltage from the DC power supply section (for example, AC/DC conversion section, renewable energy power supply, storage battery, etc.) changes, the control circuit controls the light emitting element array according to the change. Dimmable. Furthermore, the DC power supply unit is composed of at least two types of power sources of the AC/DC conversion unit, the renewable energy power supply, and the storage battery, and it is desired to switch the DC power supply sources in order according to changes in the respective supply voltages. In this case, since the power supply is direct current, that is, the power supply with the higher supply voltage is preferentially the supply source, the supply source is switched smoothly without interruption of the supply power. Therefore, a mechanism for controlling switching of the DC power supply is not required. Subsequently, the control circuit can dim the light-emitting element array according to the switched supply voltage of the DC power supply unit.
When the supply voltage of the DC power supply changes in this way, the lighting equipment is dimmed according to the change. Dimming control becomes possible.

Further, the DC power supply unit includes at least an AC/DC conversion unit that converts AC power to DC power and a renewable energy power supply, and the supply voltage of the renewable energy power supply is higher than the supply voltage of the AC/DC conversion unit. is preferred.

Renewable energy power sources (photovoltaic power generation, wind power generation, etc.) have the characteristic that the voltage that can be supplied changes according to changes in the surrounding environment (the amount of sunlight, wind speed, etc.). According to the above configuration, the voltage supplied from the AC/DC conversion unit ensures a predetermined illuminance while the supply voltage of the renewable energy power source (solar power generation, wind power generation, etc.) is higher than the supply voltage of the AC/DC conversion unit. Renewable energy with low environmental impact will be preferentially supplied during this period. Therefore, it is possible to suppress the consumption of commercial AC power, and there are merits such as a reduction in the environmental load and a reduction in the burden of power charges.
In addition, during a period in which the supply voltage of the photovoltaic power generation is higher than the supply voltage of the AC/DC converter (the amount of sunlight is large), it is possible to adjust the brightness of the lighting fixture according to the amount of sunlight. For example, when the sunlight is strong in the daytime, the brightness of the lighting equipment is increased (or decreased), and when the sunlight is weak in the evening, the brightness of the lighting equipment is decreased (or increased). can be used.

In addition, the DC power supply unit includes at least an AC/DC conversion unit that converts AC power into DC power and a storage battery, and the storage battery supplies DC power to the DC power supply line via a diode, and the storage battery supplies the DC power to the DC power supply line. It is preferable that the voltage is lower than the supply voltage of the AC/DC converter.

According to the above configuration, while the AC/DC converter maintains the supply voltage above a certain level, the supply voltage is higher than the supply voltage of the storage battery, so the storage battery does not supply DC power. When the AC/DC converter cannot maintain the supply voltage due to a power failure or the like, and the supply voltage becomes lower than the supply voltage of the storage battery, the supply of DC power from the storage battery is started. Therefore, lighting can be continued without extinguishing the lighting equipment in the event of a power failure of the AC power or the like.

Further, it is preferable that the DC power supply section has at least an AC/DC conversion section that converts AC power into DC power, and that the AC/DC conversion section has a voltage variable section that changes the supply voltage of the AC/DC conversion section. Further, it is preferable that the voltage variable section is configured to receive a dimming signal from the outside and change the supply voltage of the AC/DC converting section according to the dimming signal.

According to the above configuration, since the voltage variable section is provided in the AC/DC conversion section, which is the DC power supply section, the supply voltage of the AC/DC conversion section can be positively changed, and the lighting fixture can be lit at a desired illuminance. can be done. Further, if the voltage variable section is configured so as to change the supply voltage according to a dimming signal from the outside, it is possible to realize remote control of dimming and automatic dimming according to the detected value of a sensor or the like.

In addition, it is preferable that the DC power supply section has at least an AC/DC conversion section that converts AC power into DC power, and that the AC/DC conversion section has a rectifier circuit having six or more phases.
According to the above configuration, harmonics contained in the DC power from the AC/DC converter are less than in a lighting system using a conventional switching power supply, and the generation of electromagnetic noise is suppressed to provide a highly reliable lighting system. be able to.

Further, the light-emitting element array has a bypass path that bypasses at least one semiconductor light-emitting element among a plurality of semiconductor light-emitting elements that constitute the light-emitting element array, and a semiconductor switch element is provided on the bypass path,
Preferably, the control circuit is configured to change the degree of opening of the semiconductor switch element according to the magnitude of the supply voltage applied to the light emitting element array.

In the above configuration, for example, it is assumed that the opening degree of the semiconductor switch element of the bypass path is set to be fully open when the supply voltage of the DC power supply is maximum. Since all the current flows through the light emitting element array, the light emitting element array has the maximum brightness (dimming rate 100%). When the supply voltage drops, the control circuit changes the degree of opening of the semiconductor switch element from fully open to closed as the supply voltage drops. The illuminance of the semiconductor light emitting device provided with the bypass is reduced. In this way, dimming of the light emitting element array is performed according to the supply voltage.
Not limited to the above, for example, when the supply voltage is maximum, the semiconductor switch element is fully closed so that the amount of current flowing through the bypass is maximized (the current flowing through the light emitting element array is minimized). good too. The light emitting element array becomes the darkest. As the supply voltage decreases, the control circuit changes the opening of the semiconductor switch element from fully closed to open. Since the current flowing through the semiconductor light-emitting element is increased, the illuminance is increased.

In addition, it is preferable that the DC power supply unit has at least an AC/DC conversion unit that converts AC power into DC power, and the AC/DC conversion units are provided at both ends of the DC power supply line. As in this configuration, the AC/DC converters are provided at both ends of the DC power supply line, so even if one of the AC/DC converters experiences a problem such as a disconnection, the lighting fixture will still be able to operate completely by supplying power from the other AC/DC converter. It is possible to avoid turning off the light immediately.

Moreover, it is preferable that the DC power supply unit includes at least a storage battery and a battery checker that detects the deterioration state of the storage battery. According to this configuration, it is possible to remotely check the state of deterioration of the storage battery.

Preferably, the lighting system according to the present invention further comprises a resistance midpoint grounding circuit connecting between the positive and negative DC power supply lines and a grounding point. According to this configuration, the resistance midpoint grounding circuit acts as a safety circuit when energized, and deterioration of the insulation resistance of the DC power supply line can be detected.

Preferably, the lighting system according to the present invention further comprises an arc suppression circuit connecting the positive and negative terminals of the lighting fixture. According to this configuration, when the switch is released, the arc suppression circuit acts as a safety circuit to prevent arcing and disconnection.

Further, the lighting system according to the present invention is for tunnel lighting, wherein the DC power supply line is arranged along the tunnel, and the plurality of lighting fixtures are arranged at intervals along the tunnel. preferable.
Here, the lighting system for tunnel lighting further includes an illuminance sensor provided outside the tunnel, the DC power supply unit has at least an AC/DC conversion unit that converts AC power into DC power, and the AC/DC It is preferable that the conversion unit has a voltage variable unit that changes the supply voltage according to the illuminance measured by the illuminance sensor.

According to the above configuration, in the tunnel lighting, when the illuminance (amount of sunlight) outside the tunnel changes, the supply voltage of the AC/DC converter is changed according to the detection value of the illuminance sensor. is dimmed, it is possible to realize dimming control of tunnel lighting such that, for example, when the outside of the tunnel is bright, the inside of the tunnel is also brightened, and when the outside of the tunnel is dark, the inside of the tunnel is also darkened. With this configuration, there is no need to individually transmit dimming signals corresponding to the detection values of the illuminance sensors to a large number of lighting fixtures, and dimming can be performed only by changing the supply voltage in the AC/DC converter. The structure of dimming control for tunnel lighting can be realized simply and inexpensively.

1 is a diagram showing the overall configuration of a tunnel lighting system according to one embodiment of the present invention; FIG. The figure which shows an example of the AC/DC converter of the said lighting system. The figure which shows an example of the relationship between the supply voltage of the said lighting system, and a dimming rate. The figure which shows an example of the change of the illuminance in a tunnel by the said light control. The figure which shows the 1st example of the lighting fixture of the said lighting system. The figure for demonstrating operation|movement of the said lighting fixture. The figure which shows the 2nd example of the lighting fixture of the said lighting system. The figure which shows the 3rd example of the lighting fixture of the said lighting system. The figure which shows an example of the resistance midpoint grounding circuit of the said lighting system.

An embodiment of a tunnel lighting system according to the present invention will be specifically described with reference to the drawings.

FIG. 1 is a schematic diagram showing the overall configuration of the tunnel lighting system. The lighting system 1 includes AC/DC converters 2A and 2B provided at both ends of the lighting system as a main power supply for DC power, a positive DC power supply line 3A connecting the positive output terminals of the AC/DC converters 2A and 2B, A negative DC power supply line 3B connecting between the negative output ends thereof, a plurality of LED lighting fixtures 4A to 4C connected in parallel to the DC power supply lines 3A and 3B, and a solar power generator 5 as a first auxiliary power supply. , a wind power generator 6 as a second auxiliary power supply, a storage battery 7 as an emergency power supply, and a resistance midpoint grounding circuit 8 as a safety circuit.

A pair of DC power supply lines 3A, 3B are arranged along the tunnel, and the AC/DC converters 2A, 2B are installed near the entrance of the tunnel. Since the power supply from the other AC/DC converter is continued, it is possible to avoid completely turning off the lights in the tunnel. Further, the AC/DC converters 2A and 2B are connected to the illuminance sensor 9 outside the tunnel by a signal line, and acquire the illuminance signal outside the tunnel detected by the illuminance sensor 9 . FIG. 2A shows the circuit configuration of a center-tap rectifier circuit as a specific example of the AC/DC converter 2A. The AC/DC converter 2A includes a transformer T that converts an AC voltage from an AC power supply, diodes D1 and D2 whose anodes are connected to both ends of a secondary coil of the transformer T, and a load variable section that functions as a voltage variable section. and a tap changer 21 . The cathodes of the two rectifying elements D1 and D2 are connected to form a positive output terminal, which is connected to the positive DC power supply line 3A. The middle point of the secondary coil of the transformer T forms a negative output end and is connected to the negative DC power supply line 3B. The AC/DC converter 2B on the opposite side also has the same configuration as the AC/DC converter 2A. An applied voltage (positive electrode potential) is applied. The on-load tap changer 21 is a device that changes the turns ratio of the transformer T according to the illumination signal from the illumination sensor 9, and is used to change the DC power supply voltage according to the illumination outside the tunnel. .

Although FIG. 2 illustrates a single-phase AC/DC converter, if a rectifier circuit with six or more phases is used to convert a three-phase AC, harmonics will be further reduced, and noise will be less likely to occur. can supply For example, a 12-phase rectifier circuit or a 24-phase rectifier circuit may be used.

In the AC/DC converter 2C of the modification shown in FIG. 2B, both ends of the secondary coil of the transformer T are branched, and the branch lines are connected via additional diodes D3 and D4, DC power is output to the positive DC power supply line 3C of another system. Then, if two positive DC power supply lines 3A and 3C are arranged along the tunnel and the positive terminal of the lighting equipment is connected to both DC power supply lines 3A and 3C, either DC power supply line It is possible to avoid turning off the lighting equipment due to disconnection of the wiring.

Next, a plurality of LED lighting fixtures 4A to 4C are arranged at intervals along the tunnel, and the positive terminal of each is connected to the positive DC power supply line 3A via the diodes D5 to D7 for preventing backflow. be. The negative terminal is connected to the negative DC feeder 3B. A specific example of the lighting device 4A will be described later with reference to FIGS. 5 to 8. FIG.

Next, the photovoltaic power generator 5 and the wind power generator 6 both have their positive output ends connected to the positive DC power supply line 3A via diodes D8 and D9, and the outputs of the generators 5 and 6 are connected to the DC power supply line. Once the voltage of 3A is reached, these renewable energies are supplied to the DC feeder 3A.

The positive output end of the storage battery 7 is connected to the anode of a diode D10, and the cathode of the diode D10 is connected to the DC power supply line 3A. In addition, a series connection consisting of a diode D11 opposite in polarity to the diode D10, a switch element SW1 and a resistor R1 is connected in parallel to the diode D10. The switch element SW1 is turned on when the voltage of the storage battery 7 drops below a specified value (charging start voltage), and charging is started by the voltage of the DC power supply line 3A. Further, the switch element SW1 is turned off to stop charging when the voltage of the storage battery 7 reaches another specified value (charging stop voltage) due to charging. These charging start/stops are automatically executed. The storage battery 7 also has a battery checker 71, which is used to remotely check information indicating the voltage value and deterioration state of the storage battery.

In addition, in the lighting system 1 of the present embodiment, the DC power supply includes the main power supply (AC/DC converters 3A and 3B), the auxiliary power supply (solar power generator 5 and wind power generator 6), and the emergency power supply (storage battery 7). However, it may be only the main power supply, only the auxiliary power supply, a combination of the main power supply and the auxiliary power supply, a combination of the main power supply and the emergency power supply, or a combination of the auxiliary power supply and the emergency power supply.

The lighting fixtures 4A to 4C are lighting fixtures having the same configuration, and the lighting fixture 4A includes a plurality of LEDs as a light source. These LEDs form an LED string, which is a group of LEDs, and there are multiple such LED strings.

The lighting fixture 4A also has a control circuit for dimming the plurality of LED rows according to the voltage supplied from the DC power supply line 3A. A specific example of the control circuit will be described later with reference to FIGS. Here, the features of the tunnel lighting system 1 using the lighting fixtures 4A to 4C that are capable of dimming a plurality of LED rows in accordance with the supply voltage will be described.

FIG. 3 illustrates a case where the relationship between the supply voltage (V) of the lighting system 1 and the dimming rate (%) is linear. In this example, the range of the supply voltage V1 of the AC/DC converter 2A of the main power supply is 225 to 300 V, and the range of the supply voltage V2 (or V3) of the solar power generator 5 (or the wind power generator 6) of the auxiliary power supply is 300 V. 380V, and the range of the supply voltage V4 of the storage battery 7 of the emergency power supply is 100 to 190V. That is, the range of supply voltage (100 to 380V) corresponding to the entire range of dimming rate (5% to 100%) is divided into multiple categories, and different types of DC power sources are responsible for power supply in each category. ing.

In FIG. 3, the supply voltage V2 of the solar power generator 5 is set higher than the supply voltage V1 of the AC/DC converter 2A.

The voltage that can be supplied to the photovoltaic power generator 5 tends to change due to changes in the amount of sunlight, but it is also possible to predict the supply voltage based on the time of day and weather information. Here, by setting V1<V2, the renewable energy of photovoltaic power generation is prioritized during the period when the supply voltage V2 of the photovoltaic power generator 5 is higher than the supply voltage V1 (225 to 300 V) of the AC/DC converter 2A. made to be supplied. At the same time, during the period when the photovoltaic power generator 5 cannot maintain the supply voltage V2 of 300 V or more, a predetermined illuminance is ensured by the supply voltage V1 from the AC/DC conversion unit, which is the main power supply. Since the switching of the supply source from the photovoltaic power generator 5 to the AC/DC converter 2A is based on the DC power supply system, the power source with the higher supply voltage simply becomes the supply source preferentially. Runs smoothly without power interruptions.

FIG. 4 shows an example of changes in illuminance inside the tunnel due to dimming control of the lighting system 1 . The upper graph shows changes in the supply voltage for one day, showing the supply voltage V2 of the photovoltaic power generator 5 and the supply voltage V1 of the AC/DC converter 2A. Here, the supply voltage V1 is kept constant. According to the lighting system 1, during the daytime (from 8:00 to 16:00), the lighting fixtures are dimmed according to changes in the supply voltage V2 of the solar power generator 5, so that the outside of the tunnel is illuminated as shown in the graph below. The illuminance in the tunnel will change in much the same way as the amount of sunlight in the tunnel changes. Lighting control that makes the inside of the tunnel brighter when the outside of the tunnel is bright, and darkens the inside of the tunnel when the outside of the tunnel is dark makes it possible to manage the illumination in the tunnel in a way that is friendly to drivers using the tunnel.

FIG. 3 shows that the lighting system 1 can control the dimming of lighting fixtures even in the range of the supply voltage V1 of the AC/DC converter 2A (225-300V). That is, the illuminance sensor 9 detects changes in the illuminance (amount of sunlight) outside the tunnel, and based on the illuminance signal, the on-load tap changers 21 of the AC/DC converters 2A and 2B operate to operate the AC/DC converters 2A and 2B. is changed. Therefore, the control circuits of the lighting fixtures 4A to 4C can perform dimming in conjunction with changes in the supply voltage V1 of the AC/DC converters 2A and 2B in the same manner as when the supply voltage V2 of the solar power generator 5 changes. can. Since the supply voltage V1 is adjusted collectively in the AC/DC converters 2A and 2B, there is no need to individually transmit the illuminance signal of the illuminance sensor to a large number of lighting fixtures, and the structure of dimming control for tunnel lighting is simple. become.

In this way, even after the supply source is switched from the solar power generator 5 to the AC/DC converter 2A, the lighting fixtures 4A to 4C continue to be dimmed according to changes in the supply voltage, so a wide supply of 225 to 380V is possible. Continuous dimming control over a range of voltages is possible. Here, for the sake of clarity, the illuminance adjustment in the tunnel according to changes in the amount of sunlight has been described, but the lighting system of the present invention can also be applied to dimming control based on conditions other than the amount of sunlight.

Further, in FIG. 3, the supply voltage V4 of the storage battery 6 is set lower than the supply voltage V1 of the AC/DC converter 2A.

Since the supply voltage V1 is higher than the supply voltage V4 of the storage battery 7 while the AC/DC converter 2A maintains the supply voltage V1 above a certain level, the storage battery 7 does not supply DC power. When the supply of AC power from the outside is stopped due to a power failure or the like, the supply voltage V1 of the AC/DC converter 2A is gradually lowered to 190 V while the light is on, and the power supply by the storage battery 7 of the emergency power supply is started. The lighting continues within the range of the amount of electric power held by the storage battery 7 . Further, as the supply voltage V4 of the storage battery 7 gradually decreases, the lighting fixtures 4A to 4C are dimmed according to the change in the supply voltage V4. That is, the light is turned off at the timing when the illuminance decreases to the lower limit (5%) of the dimming rate and the supply voltage V4 becomes 100 V or less.

Specific examples of the LED lighting device 4A will be described below with reference to FIGS. 5 to 8. FIG.

A lighting fixture 41 in FIG. 5 has LED rows 51 to 53 each composed of a plurality of LEDs. As shown in FIG. 5, the anode of the first LED row 51 is connected to the positive terminal of the lighting fixture 41, the cathode of the LED row 51 branches, and one of the branches is the anode of the second LED row 51. , and the other branch is connected to the drain of a field effect transistor (FET1). The source of FET1 is further branched, with one branch connected to the cathode of diode D12 and the other branch connected to the anode of the third LED string 53 . The anode of the diode D12 and the cathode of the second LED row 51 merge and are connected to the drain of the FET2. Then, the anode of the third LED row 53 and the source of the FET 2 are alternately connected to the negative terminal of the lighting fixture 41 via the constant current control circuit (CC control circuit) 60 .

In the lighting fixture 41 of FIG. 5, the connection state of the plurality of LED arrays 51 to 53 is switched from series to parallel depending on whether FETs 1 and 2 are turned on or off. This will be described with reference to FIGS. 6(A) and 6(B). FIG. 6 shows how the connection state of the five LED arrays 51 to 55 is switched from serial to parallel. For example, if the supply voltage is a maximum of 380V, CC control circuit 60 senses the supply voltage and operates FET control circuit 61 to generate a gate voltage that turns off FETs 1-4. As a result, all the FETs 1-4 are kept off, and a series connection circuit of five LED strings 51-55 is formed as shown in FIG. 6(A). That is, the current from the positive terminal flows in the order of LED row 51→LED row 52→diode D12→LED row 53→diode D13→LED row 54→diode D14→LED row 55. FIG. Since the CC control circuit 60 controls the current to be constant, the lighting fixture 41 lights at a dimming rate of 100%.

Then, when the supply voltage drops to the threshold, CC control circuit 60 causes FET control circuit 61 to generate a gate voltage that turns on FETs 1-4. As a result, all of the FETs 1 to 4 are turned on, and as shown in FIG. and a series connection of 55, forming a parallel connection circuit which is a parallel connection of two series connections. That is, the current from the LED string 51 branches, half of the current flows in the order of LED string 52→FET2→LED string 54→FET4, and the remaining half of the current flows through FET1→LED string 53→FET3→LED string 55. They flow in order and then merge. Since the CC control circuit 60 controls the current to be constant throughout the plurality of LED rows even after switching to the parallel connection circuit, the current flowing through each LED row is halved, and the lighting fixture 41 Lights at a dimming rate of 50%.

In this manner, the lighting fixture 41 performs dimming by switching the connection state of the plurality of LED rows 51 to 53 from series to parallel according to the supply voltage.

A specific example of the arc suppression circuit 70 will be described with reference to FIG. The arc suppression circuit 70 is connected so as to connect both ends of the connection circuit of the plurality of LED rows 51 to 53, and has a parallel connection portion of a resistor R2 and a diode D17, and a capacitor C2 connected in series therewith. Configuration. By providing the arc suppression circuit 70, arc generation at the time of switch release can be suppressed, and wire breakage can be avoided.

Also, as in the example shown in FIG. 7, a series connection circuit of a plurality of lighting fixtures 42 to 44 may be connected to the positive and negative DC power supply lines 3A and 3B. However, the CC control circuit 60 is provided only in the final lighting fixture 44 . In each of the lighting fixtures 42-44, FET control circuits 61-63 switch the LED strings from series connection to parallel connection.

In the lighting fixture 45 of FIG. 8, a plurality of LED rows 51 to 54 are connected in series, and the second and fourth LED rows 52 and 54 are provided with bypass paths. FET1 is connected to the bypass of the LED row 52, and FET2 is connected to the bypass of the LED row . Here, the major difference from the lighting fixture 41 of FIG. 5 is that FET1 and FET2 can continuously adjust the opening (or closing) between the drain and the source according to the gate voltage. In other words, the amount of current in the bypass is adjusted by the degree of opening (or closing) of the FET. In the luminaire 45, the CC control circuit 80 detects the supply voltage and operates the FET control circuit 81 to generate the gate voltages of the FETs 1 and 2 so that the opening degree corresponds to the supply voltage. In addition, since the CC control circuit 80 controls the current to be constant throughout the plurality of LED rows 51 to 54, when the FET control circuit 81 adjusts the opening of the FET, the bypass current decreases the illuminance of the LED arrays 52 and 54. In this manner, the illuminance of the LED arrays 51 to 54 as a whole is continuously changed according to the supply voltage.

Finally, with reference to FIG. 9, a specific example of the resistor midpoint grounding circuit 8 will be described. A resistance midpoint grounding circuit 8 is provided between the positive and negative DC power supply lines 3A, 3B and a ground point. Since the DC power supply lines 3A and 3B are non-grounded DC circuits, the resistance midpoint grounding circuit 8 functions as a circuit for detecting a drop in insulation resistance between the DC power supply lines 3A and 3B and the ground point.

The resistance midpoint grounding circuit 8 has a series connection circuit made up of resistors R3 and R4 with equal resistance values, and a parallel connection circuit made up of photocouplers 81 and 82 connected in opposite polarities. , R4 are connected between the positive and negative DC power supply lines 3A and 3B. A parallel connection circuit of the photocouplers 81 and 82 is connected to an electric path connecting the connection point of the resistors R and R and the ground point. One terminal of the light receiving element of the photocoupler 81 is connected to VCC, and the other terminal is connected to the light emitting diode 83. When a current flows from the ground point to the connection point of the resistors R, R, the photocoupler Light emitting and light receiving actions of 81 occur, and light emitting diode 83 lights up. Similarly, one terminal of the light receiving element of the photocoupler 82 is connected to VCC, the other terminal is connected to another light emitting diode 84, and current flows from the connection point of the resistors R, R to the ground point. When the photocoupler 82 emits light and receives light, the light emitting diode 84 lights up.

In the resistance midpoint grounding circuit 8 configured as described above, when the resistance value of the insulation resistance of the positive DC power supply line 3A decreases, a weak current flows through the light emitting element of the photocoupler 81. captures and the light-emitting diode 83 lights up. As a result, the decrease in the insulation resistance of the positive DC power supply line 3A is indicated by the light emission of the light emitting diode 83. FIG. Similarly, when the resistance value of the insulation resistance of the negative DC power supply line 3B decreases, a weak current flows through the light emitting element of the photocoupler 82 on the opposite side. lights up. As a result, the light emission of the light emitting diode 84 indicates the decrease in the insulation resistance of the negative DC power supply line 3B.

1 Tunnel lighting system 2A, 2B DC power supply lines 3A, 3B AC/DC converters 4A to 4C LED lighting equipment 5 Solar power generator 6 Wind power generator 7 Storage battery 8 Resistance midpoint ground circuit 9 Illuminance sensor 21 Load tap changer 41 ~ 45 LED lighting fixtures 51 ~ 57 LED rows 60, 80 CC control circuits 61 ~ 63, 81 FET control circuit 70 arc suppression circuit

Claims (14)

a DC power supply unit that supplies DC power;
a DC power supply line connected to the output terminal of the DC power supply;
A plurality of lighting fixtures connected in parallel to the DC power supply line,
The lighting fixture is
a light emitting element array in which a plurality of semiconductor light emitting elements are connected;
and a control circuit for dimming the light emitting element array according to a change in the voltage supplied from the DC power supply to the light emitting element array. The lighting system of claim 1, wherein
The lighting system, wherein the DC power supply unit includes an AC/DC conversion unit that converts AC power to DC power, a renewable energy power source, a storage battery, or a combination thereof. 3. The lighting system according to claim 1 or 2,
The DC power supply unit has at least an AC/DC conversion unit that converts AC power into DC power and a renewable energy power supply, and the supply voltage of the renewable energy power supply is higher than the supply voltage of the AC/DC conversion unit. A lighting system characterized by: 4. A lighting system according to any one of claims 1 to 3,
The DC power supply unit includes at least an AC/DC converter that converts AC power into DC power and a storage battery. The storage battery supplies DC power to the DC power supply line via a diode, and the storage battery supplies voltage A lighting system, wherein the voltage is lower than the supply voltage of the AC/DC converter. 5. The lighting system according to any one of claims 1 to 4,
The illumination, wherein the DC power supply unit has at least an AC/DC conversion unit that converts AC power into DC power, and the AC/DC conversion unit has a voltage variable unit that changes a supply voltage of the AC/DC conversion unit. system. 6. The lighting system of claim 5, wherein
The lighting system, wherein the voltage variable section receives a dimming signal from the outside and changes the supply voltage of the AC/DC converting section according to the dimming signal. 7. A lighting system according to any one of claims 1 to 6,
The lighting system, wherein the DC power supply unit includes at least an AC/DC conversion unit that converts AC power into DC power, and the AC/DC conversion unit includes a rectifier circuit having six or more phases. 8. A lighting system according to any one of claims 1 to 7,
the light-emitting element array has a bypass path that bypasses at least one semiconductor light-emitting element among a plurality of semiconductor light-emitting elements constituting the light-emitting element array, and a semiconductor switch element is provided on the bypass path;
The lighting system according to claim 1, wherein the control circuit is configured to adjust the opening degree of the semiconductor switch element according to the magnitude of the supply voltage applied to the light emitting element array. 9. A lighting system according to any one of claims 1 to 8,
The lighting system, wherein the DC power supply unit has at least an AC/DC conversion unit that converts AC power into DC power, and the AC/DC conversion units are provided at both ends of the DC power supply line. 10. A lighting system according to any one of claims 1 to 9,
The lighting system, wherein the DC power supply unit includes at least a storage battery and a battery checker that detects a deterioration state of the storage battery. 11. A lighting system according to any one of claims 1 to 10,
1. A lighting system, comprising: a resistance midpoint grounding circuit connecting between said positive and negative DC power supply lines and a grounding point. 12. A lighting system according to any one of claims 1 to 11,
A lighting system comprising an arc suppression circuit connected between positive and negative terminals of the lighting fixture. 13. The lighting system according to any one of claims 1 to 12, for tunnel lighting, wherein the DC feed line is arranged along a tunnel and the plurality of lighting fixtures are spaced along the tunnel. A lighting system characterized by: The lighting system for tunnel lighting according to claim 13, further comprising an illuminance sensor provided outside the tunnel, wherein the DC power supply includes at least an AC/DC converter for converting AC power into DC power, The lighting system, wherein the AC/DC conversion unit has a voltage variable unit that changes the supply voltage according to the illuminance measured by the illuminance sensor.

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