JP2021197280A - Emergency lighting apparatus and lighting equipment - Google Patents

Abstract

To provide an emergency lighting apparatus and lighting equipment suitable for cost reduction.SOLUTION: An emergency lighting apparatus has a storage battery consisting of a plurality of storage battery cells connected in series or in parallel, a lighting circuit having a coil and a switch element, which is connected to the storage battery and constitutes a DC power conversion circuit, and a control circuit that controls the conduction state of the switch element, and the control circuit repeatedly turns the switch element on and off so that the current flows through the coil continuously, and the power stored in the storage battery is output.SELECTED DRAWING: Figure 4

Description

The present disclosure relates to emergency lighting devices and luminaires.

Among lighting fixtures that use LEDs (LIGHT EMITTING Diodes) as a light source, there is an emergency fixture that maintains a lighting state for a predetermined time when a power failure occurs due to a disaster or the like and a commercial power source cannot be obtained. Such an emergency lighting device includes a storage battery as a power source for lighting the light source, and a lighting circuit that converts the energy input from the storage battery into the DC voltage and current required for lighting the LED. In addition, the emergency lighting device converts the alternating current energy input from the commercial power supply into direct current and charges the storage battery with a predetermined current in order to charge the storage battery when a commercial power supply is obtained. Equipped with a circuit.

The time for the emergency lighting device to keep the light source lit in the event of a power outage is set, and in Japan, this is the standard of the Lighting Industry Association (JIL). Therefore, the storage battery used in the emergency lighting device has a discharge capacity required to satisfy a predetermined lighting time. The storage battery has, for example, a configuration of an assembled battery in which a plurality of cylindrical storage battery cells are connected, and the capacity is determined by the combination of the discharge capacity per cell and the number of cells.

When the voltage of the storage battery is lower than the voltage required to light the LED, a switching power supply capable of boosting operation such as a boosting chopper is used as the lighting circuit.

Since the discharge capacity of the storage battery decreases due to deterioration over time, it is not possible to maintain the capacity required to maintain a predetermined lighting time during the life of the luminaire. Therefore, the storage battery can be attached and detached from the main body of the lighting fixture, and the storage battery is replaced regularly. To improve the workability of replacement, the storage battery and the lighting circuit are connected via wire wiring or a connector.

The discharge current from the storage battery at the time of lighting may be as large as several A, and power loss occurs in the wire wiring and the wiring connecting the storage battery cells to each other. Therefore, for example, as described in Patent Document 1, the capacity of the storage battery is determined in consideration of the power loss of the wiring in addition to the power consumed by the light source, and the discharge capacity is increased.

Japanese Unexamined Patent Publication No. 2013-165598

When increasing the capacity of the storage battery by taking into account the power loss of the wiring in addition to the power consumed by the light source, it is necessary to increase the discharge capacity of the storage battery cell alone or increase the number of storage batteries. There is a problem that the volume of the storage battery increases as the cost increases.

The present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to provide an emergency lighting device and a lighting fixture suitable for cost reduction.

The emergency lighting device according to the present disclosure includes a storage battery in which a plurality of storage battery cells are connected in series or in parallel, a lighting circuit having a coil and a switch element, and being connected to the storage battery to form a DC power conversion circuit. A control circuit for controlling the continuity state of the switch element is provided, and the control circuit repeatedly turns on and off the switch element so that a continuous current flows through the coil, and outputs the power stored in the storage battery. It is characterized by.

Other features of this disclosure are clarified below.

According to the present disclosure, an emergency lighting device capable of avoiding an increase in the capacity of a storage battery by suppressing the magnitude of the discharge current of the storage battery, that is, the input current of the lighting circuit, or suppressing the loss in the gate drive circuit. Lighting equipment can be provided.

It is a circuit diagram of the lighting fixture which concerns on Embodiment 1. FIG. It is a perspective view which shows the structural example of a storage battery. It is a waveform diagram which shows the operation of the lighting circuit which concerns on a comparative example. It is a waveform diagram which shows the operation of the lighting circuit which concerns on Embodiment 1. FIG. It is a waveform diagram which shows the control example at the start of lighting. It is a circuit diagram of the lighting fixture which concerns on Embodiment 2. FIG. It is a waveform diagram which shows the operation of the gate drive circuit which concerns on a comparative example. It is a waveform diagram which shows the operation of the gate drive circuit which concerns on Embodiment 2.

The emergency lighting device and the lighting fixture according to the embodiment will be described with reference to the drawings. The same or corresponding components may be designated by the same reference numerals and the description may be omitted.

Embodiment 1.
FIG. 1 is a circuit diagram of a lighting fixture 100 according to a first embodiment. The luminaire 100 lights a light source under the condition that a commercial power source cannot be obtained due to the occurrence of a power failure. The lighting fixture 100 includes a charging lighting circuit 13, a control circuit 10, a gate drive circuit 11, and a constant voltage circuit 12. A commercial power supply 1, a storage battery 6, and an LED 9 are connected to the charging lighting circuit 13.

The charging lighting circuit 13 includes a rectifier circuit 2, a charging circuit 3, and a lighting circuit 7. The rectifier circuit 2 is connected to the commercial power supply 1 and converts the AC voltage input from the commercial power supply 1 into direct current. The charging circuit 3 electrically insulates the commercial power supply 1 and the storage battery 6, and outputs a constant voltage obtained by stepping down the DC voltage converted by the rectifier circuit 2. The voltage output by the charging circuit 3 is smoothed by the electrolytic capacitor 4. The regulator 5 charges the storage battery 6 with a constant current using the voltage of the electrolytic capacitor 4. The lighting circuit 7 converts the voltage of the storage battery 6 into a voltage at which the LED 9 can be lit when the voltage of the commercial power supply 1 cannot be obtained. The voltage output by the lighting circuit 7 is smoothed by the filter capacitor 8.

The LED 9 may be composed of a group of LEDs in which a plurality of LED chips are connected in series or in parallel. One end of the LED group is connected to the positive electrode side DC bus of the lighting circuit 7, and the other end of the LED group is connected to the negative electrode side DC bus of the lighting circuit 7.

The charging circuit 3 includes a filter capacitor 3d connected in parallel to the rectifier circuit 2, a series circuit including the primary winding of the flyback transformer 3a connected in parallel with the filter capacitor 3d, and a MOSFET 3b, and a flyback transformer 3a. It includes a diode 3c connected to the secondary winding. Further, although not shown, in order to reduce a high frequency component superimposed on the current input from the commercial power supply 1 generated due to the switching operation of the charging circuit 3 between the commercial power supply 1 and the rectifier circuit 2. Input filter may be used. The input filter is composed of, for example, a filter capacitor connected in parallel with the commercial power supply 1 and a filter coil connected in series with the commercial power supply 1 or one of them.

The charging circuit 3 has a function of stepping down the voltage output by the rectifier circuit 2, outputting a constant voltage, and electrically insulating the commercial power supply 1 and the storage battery 6. It may also have a function of suppressing the harmonics of the current input from the commercial power source 1 to improve the power factor.

The rectifier circuit 2 is arranged between the commercial power supply 1 and the charging circuit 3, and converts the AC power supplied from the commercial power supply 1 into DC power. The rectifier circuit 2 is composed of, for example, a diode bridge in which four diodes are combined, and outputs a full-wave rectified DC voltage. The configuration of the rectifier circuit 2 is not limited to this, and may be configured by combining MOSFETs that are unidirectional conduction elements.

Further, by forming the rectifier circuit 2 with a diode bridge in which two diodes are combined, the number of parts can be reduced. In this case, the voltage output by the rectifier circuit 2 is a half-wave rectified DC voltage. Compared to the case of full-wave rectification using the above four diodes, the peak value of the current input from the commercial power supply 1 increases, but the power to charge the storage battery 6 is as low as 1 to 2 W. In many cases, there is a sufficient margin for the current rating, and there is no problem of increasing the component rating. Also in this case, a diode bridge for half-wave rectification may be configured by combining two MOSFETs.

The filter capacitor 3d is connected in parallel to the output of the rectifier circuit 2 and smoothes the output voltage of the rectifier circuit 2.

The charging circuit 3 is arranged between the rectifier circuit 2 and the storage battery 6. The charging circuit 3 includes a MOSFET 3b which is a switching element, a flyback transformer 3a, and a diode 3c. The charging circuit 3 steps on and off the MOSFET 3b by a control means (not shown) to step down the output voltage of the rectifier circuit 2 and output the stepped down voltage to the electrolytic capacitor 4. Further, the charging circuit 3 has a function of electrically insulating the commercial power supply 1 and the storage battery 6. This is because, as will be described later, the storage battery 6 needs to be replaced manually. Further, the charging circuit 3 may have a function of suppressing harmonics of the input current and improving the power factor. Here, an example in which the charging circuit 3 is configured by a flyback converter is shown, but in addition to the flyback converter, it is configured by a circuit such as a flyforward converter, an LLC converter, and an isolated SEPIC (SINGLE ENDED PRIMARY INDUCTOR CONVERTER). May be good.

The flyback transformer 3a is arranged between the filter capacitor 3d and the MOSFET 3b. The flyback transformer 3a can be formed by winding an insulating wire around the core. One end of the primary winding of the flyback transformer 3a is connected to one end of the filter capacitor 3d. The other end of the primary winding of the flyback transformer 3a is connected to the drain of the MOSFET 3b. Further, a snubber circuit including a diode, a capacitor and a resistor can be provided in parallel with the primary winding of the flyback transformer 3a. By providing the snubber circuit, the surge voltage associated with the switching of the MOSFET 3b can be suppressed, the loss of the MOSFET 3b can be reduced, and the temperature rise can be suppressed.

The drain of the MOSFET 3b is connected to the primary winding of the flyback transformer 3a, and the source of the MOSFET 3b is connected to the other end of the filter capacitor 3d. The gate of the MOSFET 3b is connected to a control means, and a control signal for controlling the on / off state of the MOSFET 3b is input to the gate of the MOSFET 3b from the control means.

The diode 3c is arranged between the flyback transformer 3a and the electrolytic capacitor 4. The anode of the diode 3c is connected to the secondary winding of the flyback transformer 3a, and the cathode of the diode 3c is connected to the electrolytic capacitor 4 and the regulator 5.

The electrolytic capacitor 4 is arranged between the charging circuit 3 and the storage battery 6. One end of the electrolytic capacitor 4 is connected to the cathode of the diode 3c and the regulator 5, and the other end of the electrolytic capacitor 4 is connected to the secondary winding of the flyback transformer 3a and the negative terminal of the storage battery 6.

Next, the operation of the regulator 5 will be described.

The regulator 5 is connected between the electrolytic capacitor 4 and the storage battery 6. The regulator 5 takes the voltage of the electrolytic capacitor 4 as an input and outputs a constant current to charge the storage battery 6. At this time, the difference between the voltage of the electrolytic capacitor 4 and the voltage of the storage battery 6 is lost as a heat loss in the regulator 5. Therefore, by changing the voltage output by the charging circuit 3 according to the charging status of the storage battery 6 and making it substantially the same as the voltage of the storage battery 6, the loss in the regulator 5 is suppressed and the rise in the component temperature is suppressed. Can be done.

Next, the configuration and operation of the lighting circuit 7 will be described.

The lighting circuit 7 includes a coil 7a, a switch element 7b, a diode 7c, a filter capacitor 7d, and a current detection circuit 7e. The switch element 7b is, for example, a MOSFET. The switch element 7b is arranged between the positive electrode side DC bus and the negative electrode side DC bus. The drain of the switch element 7b is connected to one end of the coil 7a and the anode of the diode 7c. The source of the switch element 7b is connected to one end of the filter capacitor 7d, the other end of the storage battery 6, and one end of the filter capacitor 8. The gate of the switch element 7b is connected to the gate drive circuit 11. A control signal for switching the on / off operation of the switch element 7b is input from the gate drive circuit 11 to the gate of the switch element 7b.

One end of the coil 7a is connected to the drain of the switch element 7b and the anode of the diode 7c. The other end of the coil 7a is connected to the other end of the filter capacitor 7d and one end of the storage battery 6. The cathode of the diode 7c is connected to the other end of the filter capacitor 8 and one end of the LED 9.

The lighting circuit 7 constitutes a DC power conversion circuit. In the example of FIG. 1, the lighting circuit 7 is composed of a step-up chopper circuit. It may be configured.

The MOSFET 3b and the switch element 7b can be made of, for example, a silicon-based semiconductor. According to another example, the MOSFET 3b and the switch element 7b may be formed of a wide bandgap semiconductor having a larger bandgap than silicon. Wide bandgap semiconductors include silicon carbide, gallium nitride based materials or diamond.

By using a wide bandgap semiconductor for the MOSFET 3b and the switch element 7b, these energization losses can be reduced. Further, even if the switching frequency, that is, the repetition frequency of the on / off operation is set to a high frequency, the heat dissipation is good. Therefore, by miniaturizing or deleting the heat radiating component of the charging circuit 3 or the lighting circuit 7, it is possible to realize the miniaturization and cost reduction of the charging lighting circuit 13. In addition, by setting the drive frequency to a high frequency, the flyback transformer 3a and the coil 7a can be miniaturized, so that the charging and lighting circuit 13 can be miniaturized and the cost can be reduced.

Next, the configuration and operation of the control circuit 10 will be described.

The control circuit 10 includes a power failure detection unit 10a, a current detection unit 10b, a voltage detection unit 10c, a calculation unit 10d, and a switching control unit 10e.

The power failure detection unit 10a is connected to one end of the secondary winding of the flyback transformer 3a and the anode of the diode 3c, and the power failure status of the commercial power supply 1, that is, whether the voltage of the commercial power supply 1 is normally obtained. It is a circuit for detecting whether or not. The specific configuration of the power failure detection unit 10a is, for example, a resistance voltage divider circuit in which resistors are connected in series. The resistance voltage divider circuit divides the voltage generated at one end of the secondary winding of the flyback transformer 3a into a voltage that can be input to the arithmetic unit 10d.

The current detection unit 10b is connected to the current detection circuit 7e and detects the magnitude of the current flowing through the LED 9. A shunt resistor can be used as the current detection circuit 7e. In this case, the voltage generated in the shunt resistor includes the ripple voltage caused by the switching of the switch element 7b. Therefore, the specific configuration of the current detection unit 10b is, for example, a low-pass filter circuit in which a resistor and a capacitor are connected in parallel. Such a low-pass filter circuit removes the ripple voltage generated in the voltage of the shunt resistor, and inputs the averaged voltage to the arithmetic unit 10d.

The voltage detection unit 10c is connected to the other end of the filter capacitor 8 and one end of the LED 9, and detects the voltage output by the lighting circuit 7. The specific configuration of the voltage detection unit 10c is, for example, a resistance voltage divider circuit in which resistors are connected in series. Such a resistance voltage dividing circuit divides the voltage output by the lighting circuit 7 into a voltage that can be input to the arithmetic unit 10d.

The calculation unit 10d calculates a signal for controlling the on / off state of the switch element 7b using the signals input from the power failure detection unit 10a, the current detection unit 10b, and the voltage detection unit 10c, and inputs the signal to the switching control unit 10e. Output.

Specifically, the calculation unit 10d determines whether or not a power failure has occurred in the commercial power supply 1 by using the signal input from the power failure detection unit 10a. When a power failure occurs in the commercial power supply 1, the voltage output to the secondary winding of the flyback transformer in the charging circuit 3 decreases. Therefore, for example, it can be detected that the voltage input from the power failure detection unit 10a has fallen below a predetermined voltage for a period of half a cycle of the frequency of the commercial power supply 1, and it can be determined that a power failure has occurred. Since the emergency lighting fixture needs to be turned on when a power failure occurs, the lighting operation of the LED 9 by the lighting circuit 7 can be started by the above means. Therefore, in the example of FIG. 1, the power failure detection unit 10a is connected to one end of the secondary winding of the flyback transformer 3a and the anode of the diode 3c, but the power failure detection unit 10a may be connected to one end of the filter capacitor 3d. good. When the power failure detection unit 10a is connected to one end of the filter capacitor 3d, the charging circuit 3 is configured to electrically insulate the commercial power supply 1 and the storage battery 6, so that the power failure detection unit 10a further includes an insulating element such as a photocoupler. , It is necessary to transmit a signal to the arithmetic unit 10d. However, when the power failure detection unit 10a is connected to one end of the filter capacitor 3d, the voltage at a location closer to the commercial power supply 1 can be detected, so that it can be determined earlier that a power failure has occurred in the commercial power supply 1. , It is possible to start lighting promptly in the event of a power failure.

The calculation unit 10d calculates a signal for on / off control of the switch element 7b by using the voltage detected by the current detection unit 10b and the voltage detection unit 10c. The current detected by the current detection unit 10b is the current output to the LED 9. Further, the voltage detected by the voltage detection unit 10c is the voltage output to the LED 9. Therefore, the calculation unit 10d can determine the power output to the LED 9 by multiplying the current detection unit 10b by the voltage detected by the voltage detection unit 10c. The calculation unit 10d calculates a period for turning on and off the switch element 7b so as to have a constant power according to the determined power, and outputs a control signal reflecting the calculation result to the switching control unit 10e. Since the brightness output by the LED 9 is determined by the magnitude of the current, the calculation unit 10d uses only the detection result of the current detection unit 10b to calculate a control signal for on / off control of the switch element 7b so that the current becomes constant. It may be that. However, in that case, when some points of the LED chips constituting the LED 9 fail and the short mode is set, the light output from the LED 9 is reduced. On the other hand, by using the voltage detected by the current detection unit 10b and the voltage detection unit 10c to control the on / off of the switch element 7b so as to have a constant power, some points of the LED chips constituting the LED 9 are obtained. It is possible to suppress a decrease in the light output from the LED 9 even when the LED 9 fails and the short mode is set.

The switching control unit 10e outputs a control signal for controlling the on / off of the switch element 7b to the gate drive circuit 11 according to the period in which the switch element 7b calculated by the calculation unit 10d is turned on and off. Therefore, the control circuit 10 is provided to control the conduction state of the switch element 7b.

The arithmetic unit 10d can be realized as hardware that combines a plurality of analog ICs such as a multiplier. According to another example, the arithmetic unit 10d can be realized as software by a microcomputer or a DSP (DIGITAL SIGNAL PROCESSOR). In the latter case, the number of parts can be reduced and the board area can be reduced as compared with the case where the analog ICs are combined and configured. Further, the configuration of the switching control unit 10e can be realized as hardware in which an analog timer IC is combined, but by realizing it by a microcomputer or DSP as described above, the number of parts can be reduced and the board area can be reduced. It can be miniaturized. When both the arithmetic unit 10d and the switching control unit 10e are realized as software, they can be made into the same component.

The gate drive circuit 11 includes MOSFETs 11a, 11b, 11c, resistors 11d, 11f, and a first resistor 11e. The gate drive circuit 11 amplifies the signal output by the switching control unit 10e to a voltage capable of driving the gate of the switch element 7b.

The gate of the MOSFET 11a is connected to the switching control unit 10e. The drain of the MOSFET 11a is connected to one end of the resistor 11d and the gate of the MOSFETs 11b and 11c. The source of the MOSFET 11a is connected to the source of the MOSFET 11c and one end of the filter capacitor 12d. The other end of the resistor 11d is connected to the drain of the MOSFET 11b and the other end of the filter capacitor 12d. The drain of the MOSFET 11b is connected to one end of the resistor 11d and one end of the filter capacitor 12d, and the source is connected to one end of the first resistance 11e. The source of the MOSFET 11c is connected to the source of the MOSFET 11a and the other end of the filter capacitor 12d, and the drain is connected to one end of the resistor 11f. The other end of the first resistance 11e and the other end of the resistance 11f are connected to the gate of the switch element 7b.

In the MOSFET 11a and the resistance 11d, even if the voltage of the switching control unit 10e is increased, the increased voltage drives the gates of the MOSFETs 11b and 11c. For example, when the switching control unit 10e is configured by a microcomputer, the voltage output from the switching control unit 10e has a height of 0V to 3.3V, and this is used as the drive voltage of the gate drive circuit, for example, 0V to 0V. It is raised to a height of 5V. The drive voltage of the gate drive circuit 11 can be arbitrarily selected by the design of the constant voltage circuit 12. The MOSFETs 11b and 11c have a configuration generally called a push-pull type, and drive the gate of the switch element 7b at high speed. The first resistance 11e and the resistance 11f are the gate resistances of the switch element 7b.

The constant voltage circuit 12 is a circuit for generating a constant voltage for the gate drive circuit 11 to operate. The constant voltage circuit 12 includes a transistor 12a, a resistor 12b, a Zener diode 12c, and a filter capacitor 12d. According to one example, the voltage output by the constant voltage circuit 12 is a voltage higher than the gate threshold voltage of the switch element 7b, for example, 5V.

In the example of FIG. 1, the constant voltage circuit 12 is connected to the other end of the filter capacitor 8 and one end of the LED 9, and the drive voltage of the gate drive circuit 11 is obtained from the output of the lighting circuit 7. The location where the constant voltage circuit 12 is connected is not limited to this, and may be configured to be connected to the positive electrode side of the storage battery 6. In particular, the loss generated in the constant voltage circuit 12 can be suppressed by connecting the gate drive circuit 11 to a location where the voltage, which is the difference from the voltage for driving the gate drive circuit 11, is low.

FIG. 2 is an external perspective view showing the configurations of the storage battery 6, the LED 9, and the charging lighting circuit 13. Here, in reality, the storage battery 6, the LED 9, and the charging / lighting circuit 13 are each housed in a resin or sheet metal case, but the case is omitted for the sake of explanation.

The storage battery 6 is provided by connecting a plurality of storage battery cells in series or in parallel. In the example of FIG. 2, the storage battery 6 has the shape of an assembled battery in which a plurality of storage battery cells 6a, 6b, and 6c are connected in series. The number of storage battery cells included in the assembled battery can be adjusted according to the power consumption when the LED 9 is turned on. The storage battery cell is a cell. Since the positive electrode / negative electrode terminals of the storage battery cells 6a, 6b, 6c are generally made of steel, steel bus bar wirings 17a, 17b, 17c can be used as the wiring for connecting the plurality of storage battery cells. In the example of FIG. 2, the bus bar wirings 17a, 17b, and 17c have a plate-like shape. Steel has a resistivity 7 to 43 times higher than that of copper, which is a general wiring material, and has a large power loss in wiring. Therefore, as described above, when the assembled battery using steel is adopted, the electric power that can be taken out is reduced as compared with the cell alone. Therefore, it is necessary to use a storage battery cell having a discharge capacity larger than the capacity required for lighting the LED, or to increase the number of cells, which increases the cost.

FIG. 2 shows an example in which the charging / lighting circuit 13 is mounted on one substrate. Further, among the parts constituting the charging lighting circuit 13, only relatively large parts are shown in the figure. The LED 9 is composed of a plurality of LED chips and is mounted on the LED substrate 9a.

Since the discharge capacity of the storage battery 6 decreases due to deterioration over time, it is not possible to secure a sufficient lighting time for the entire life of the luminaire without replacement. Therefore, the storage battery 6 is treated as a replacement part. A structure is adopted in which the storage battery 6 can be removed and attached from the charging / lighting circuit 13.

The storage battery 6 and the LED 9 are connected to the charging lighting circuit 13 by lead wiring. In particular, the connection between the storage battery 6 and the charging / lighting circuit 13 will be described.

The storage battery 6 and the charging / lighting circuit 13 are connected via lead wirings 16a and 16b. In particular, the charging lighting circuit 13 includes a storage battery terminal 15b, and lead wirings 16a and 16b are connected to the storage battery terminal 15b. In the storage battery 6, the lead wirings 16a and 16b are connected to the bus bar wirings 17a and 17c, respectively. As a method of connection, means such as caulking, soldering or welding can be used. Since power loss also occurs in the lead wirings 16a and 16b, in order to suppress the discharge capacity of the storage battery cells 6a, 6b and 6c, the lengths and thicknesses of the lead wirings 16a and 16b are shortened and the resistance is increased. It is desirable to lower it.

The charging lighting circuit 13 includes a commercial power supply terminal 15a for connecting to the commercial power supply 1 and an LED board terminal 15c for connecting to the LED 9. Further, FIG. 2 shows an input filter 14 provided as the above-mentioned input filter.

FIG. 3 is a waveform diagram showing a switching operation of the lighting circuit according to the comparative example. FIG. 3 shows the waveforms of the discharge current input from the storage battery 6 to the lighting circuit 7, the current of the coil 7a, and the drain voltage indicating the on / off state of the switch element 7b.

The horizontal axis represents time, and the switching cycle Tsw is equal to the time from the time when the switch element 7b changes from off to on until the switch element 7b changes from off to on again. The switching cycle Tsw is set in advance in the calculation unit 10d. The on-time Ton is equal to the time from when the switch element 7b changes from off to on until it changes from on to off.

When the switch element 7b changes from the off state to the on state, a current path is formed through the storage battery 6, the coil 7a, and the switch element 7b, and the current flowing through the coil 7a increases as shown in FIG.

When the switch element 7b changes from the on state to the off state, the switch element 7b is cut off, so that a current path passing through the storage battery 6, the coil 7a, the diode 7c, and the LED 9 is formed. Since the voltage of the storage battery 6 is lower than that of the LED 9, the current flowing through the coil 7a decreases and reaches 0A. When the switching cycle Tsw has elapsed, the switch element 7b is changed from off to on again.

At this time, the current waveform flowing through the coil 7a becomes a triangular wave-shaped waveform including a discontinuous period, that is, a period in which the current of the coil 7a is 0A, but the current input from the storage battery 6 has a switching frequency due to the filter capacitor 7d. Pulsating current is reduced. Therefore, the average current Iave1'discharged by the storage battery 6 is substantially the same as the average current Iave1 flowing through the coil 7a, but the pulsation of the current due to switching is not the same and has a pulsation current of the magnitude of Ipp1'. .. After the current of the coil 7a drops to zero, the parasitic capacitance of the switch element 7b and the resonance circuit formed by the coil 7a generate a resonance current, but the description thereof is omitted.

The calculation unit 10d performs a feedback calculation so that the power of the LED 9 becomes a target magnitude. For example, the switching cycle Tsw for turning on the switch element 7b is fixed according to the values detected by the current detection unit 10b and the voltage detection unit 10c, and the on-time Ton is changed according to the magnitude of the electric power of the LED 9. Specifically, when the detected value is lower than the target size, the on-time Ton is lengthened, and when the detected value is higher than the target size, the on-time Ton is shortened. The control method for obtaining a specific output by adjusting the on-time ton in this way is called duty control because the ratio of the on-time ton to the switching cycle Tsw is called duty.

Although the case of performing duty control is shown in FIG. 3, as another general control means, a method of fixing the on-time Ton and changing the switching cycle Tsw can also be carried out. This is called frequency control because the reciprocal of the switching period Tsw is the frequency.

Next, the operation of the lighting circuit 7 according to the first embodiment will be described.

FIG. 4 is a waveform showing the switching operation of the lighting circuit 7 of the first embodiment. FIG. 4 shows a waveform of a discharge current input from the storage battery 6 to the lighting circuit 7, a current of the coil 7a, and a drain voltage indicating an on / off state of the switch element 7b.

The horizontal axis represents time, and the switching cycle Tsw is equal to the time from the time when the switch element 7b changes from off to on until the switch element 7b changes from off to on again. The switching cycle Tsw is set in advance in the calculation unit 10d. The on-time Ton is equal to the time from when the switch element 7b changes from off to on until it changes from on to off.

When the switch element 7b changes from the off state to the on state, a current path is formed through the storage battery 6, the coil 7a, and the switch element 7b, and the current flowing through the coil 7a increases as shown in FIG.

When the switch element 7b changes from the on state to the off state, the switch element 7b is cut off, so that a current path passing through the storage battery 6, the coil 7a, the diode 7c, and the LED 9 is formed. Since the voltage of the storage battery 6 is lower than that of the LED 9, the current flowing through the coil 7a is reduced. The switch element 7b is changed from off to on again before the current of the coil 7a decreases to 0A. Such an operation is called a current continuous mode because a current is continuously conducted to the coil 7a during the switching cycle Tsw. As described above, the control circuit 10 repeatedly turns on and off the switch element 7b so that a current continuously flows through the coil 7a, and outputs the electric power stored in the storage battery 6. On the other hand, in the comparative example shown in FIG. 3, the current of the coil 7a becomes 0A in the period of the switching cycle Tsw and has a discontinuous period. Such control is called a current discontinuous mode.

As shown in FIG. 4, the current flowing through the coil 7a has a triangular wave-like waveform in which a direct current component is superimposed. Since the pulsating current of the switching frequency of the current input from the storage battery 6 is reduced by the filter capacitor 7d, the average current Iave2'discharged by the storage battery 6 is substantially the same as the average current Iave2 flowing through the coil 7a. The discharge current of the storage battery 6 has a pulsating current having a magnitude of Ipp2'.

Comparing the average currents flowing through the coils 7a, if the voltage of the storage battery 6 is the same and the power consumption of the lighting circuit 7 is the same, the average current Iave1 of the comparative example and the average current Iave2 of the first embodiment are substantially the same. Similarly, the average current Iave 1'and the average current Iave 2'discharged from the storage battery 6 are also substantially the same. However, in the first embodiment, since the current of the coil 7a is controlled to be in the current continuous mode, the pulsation of the current of the coil 7a due to the switching of the switch element 7b becomes small. Therefore, the pulsating current Ipp2'in FIG. 4 can be made smaller than the pulsating current Ipp1' in FIG.

The effective value Iin of the discharge current from the storage battery 6 can be expressed by Iin = Iave + 1 / 2√3 × Ipp using the average current Iave and the pulsating current Ipp, assuming that the waveform of the current is a triangular wave. The pulsating current Ipp2'of the first embodiment is smaller than the pulsating current Ipp1' of the comparative example. Therefore, the effective value current can be suppressed while outputting the average current equivalent to that of the comparative example from the storage battery 6.

As described above, the storage battery 6 has the shape of an assembled battery in which a plurality of storage battery cells 6a, 6b, 6c are connected in series, and steel bus bar wirings 17a, 17b, 17c are used as wiring for connecting the cells. Compared to copper, which is a general wiring material, steel has a electrical resistivity 7 to 43 times higher and has a large loss in wiring. Therefore, by adopting the above-mentioned assembled battery, the electric power that can be taken out is reduced as compared with the cell alone. In the present embodiment, since the effective value current discharged from the storage battery 6 can be suppressed as described above, the power loss in the bus bar wiring is reduced, and the reduction in the power that can be taken out by using the assembled battery is suppressed. It has the effect of doing. Therefore, the discharge capacities of the storage battery cells 6a, 6b, and 6c used for the storage battery 6 can be reduced, and the number of storage battery cells can be reduced, so that the cost can be reduced.

Further, even if the resistance values of the bus bar wirings 17a, 17b, 17c are increased by reducing the thickness or width of the bus bar wirings 17a, 17b, 17c, the bus bar wiring is suppressed by suppressing the effective value current described above. The power loss in the above can be made equivalent to that of the comparative example. Further, even if the lengths of the bus bar wirings 17a, 17b, 17c or the lead wirings 16a, 16b are increased, the power loss can be made equivalent to that of the comparative example. By increasing the length of the bus bar wirings 17a, 17b, 17c or the lead wirings 16a, 16b and increasing the distance between the storage battery 6 and the charging / lighting circuit 13, the workability of replacing the storage battery 6 can be improved.

As one of the means for operating the lighting circuit 7 in the current continuous mode, there is a method of shortening the switching cycle Tsw. In this case, since the number of switchings increases, the switching loss generated in the switch element 7b and the diode 7c increases, and the power consumption of the lighting circuit 7 increases. On the other hand, as the material of the switch element 7b and the diode 7c, a wide bandgap semiconductor such as silicon carbide, gallium nitride based material, or diamond having a smaller switching loss is used instead of the conventional silicon-based semiconductor. It is possible to suppress an increase in the power consumption of the circuit 7.

As another means for operating the lighting circuit 7 in the current continuous mode, there is a method of increasing the inductance of the coil 7a. In this case, since the number of turns of the coil is increased, the copper loss generated in the coil 7a increases due to the increase in winding resistance. Therefore, the power consumption of the lighting circuit 7 increases. On the other hand, by using a litz wire having a low copper loss at high frequencies instead of a single copper wire as the winding material of the coil 7a, the power consumption of the lighting circuit 7 can be suppressed. A litz wire is a twist of multiple copper wires.

As another means of reducing the pulsating current of the discharge current of the storage battery 6, there is a method of increasing the capacity of the filter capacitor 7d. However, in order to increase the capacity of the filter capacitor 7d, there are disadvantages such as an increase in the size of parts and an increase in the number of parts due to parallelization of a large number of parts. Therefore, the measures according to the present embodiment are suitable.

FIG. 5 is a waveform diagram showing an example of the operation of the lighting circuit 7 immediately after a power failure occurs in the commercial power supply 1 and the lighting operation is started. In this waveform diagram, the current waveform of the coil 7a and the drain voltage waveform showing the on / off state of the switch element 7b are shown.

If a large overshoot occurs in the current output to the LED 9 immediately after the lighting of the LED 9 is started, the rated current of the LED 9 may be exceeded and the LED 9 may deteriorate or fail. FIG. 5 shows an operation for suppressing the occurrence of a large overshoot in the current of the LED 9.

In the example of FIG. 5, immediately after the operation of the lighting circuit 7 is started, the on-time Ton of the switch element 7b is set to be shorter than the steady state. Then, by lengthening the on-time Ton with the passage of time, the magnitude of the output is controlled so as to obtain the target output. In this way, after starting the on / off of the switch element 7b, the on time of the switch element 7b, which is set to a unit time, is lengthened over time to suppress the overshoot of the current output to the LED 9. As a result, deterioration or failure of the LED 9 can be suppressed.

Further, when the current continuous mode is carried out under the condition that the on-time Ton is short, it is necessary to shorten the switching cycle of the switch element 7b and drive it at a high frequency. Therefore, when a microcomputer is used as the arithmetic unit 10d, it is necessary to increase the time resolution with a high-speed operation clock, and in addition to increasing the power consumption in the arithmetic unit 10d, an expensive microcomputer is required.

Therefore, according to one example, in order to realize the operation shown in FIG. 5, the lighting circuit 7 can be operated in the discontinuous mode instead of the continuous mode in a predetermined period immediately after the operation is started. In other words, a predetermined period after starting the on / off of the switch element 7b is provided with a discontinuous period in which the current flowing through the coil 7a becomes substantially zero. This eliminates the need to set the switching frequency to a high frequency, so that the operating clock of the arithmetic unit 10d can be made relatively low. Reducing the operating clock makes it possible to reduce power consumption and use inexpensive microcomputers.

The modified example, modified example or alternative described in the first embodiment can be applied to the emergency lighting device and the lighting equipment according to the following embodiment. The differences between the emergency lighting device and the lighting fixture according to the following embodiments will be mainly described with respect to the first embodiment.

Embodiment 2.
FIG. 6 is a circuit diagram of the lighting fixture 200 according to the second embodiment. The same or corresponding configurations as the lighting fixture 100 of the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

Compared with the luminaire 100 according to the first embodiment, the luminaire 200 of FIG. 6 is different in that it does not have the constant voltage circuit 12 and includes the gate drive circuit 11'instead of the gate drive circuit 11. The gate drive circuit 11'includes a diode 11g, a bipolar transistor 11h, and a second resistor 11i.

In the second embodiment, since the gate of the switch element 7b is driven with a voltage higher than that of the gate drive circuit 11, the turn-on loss of the switch element 7b that occurs when the switch element 7b is operated in the continuous mode can be reduced. Further, by adopting a configuration that does not use the constant voltage circuit 12, it is possible to reduce the loss generated in the constant voltage circuit 12 and the number of parts, which is suitable for cost reduction.

As shown in FIG. 6, the gate of the MOSFET 11a is also connected to the switching control unit 10e. The drain of the MOSFET 11a is connected to one end of the resistor 11d and the gate of the MOSFET 11b. The source of the MOSFET 11a is connected to the second resistor 11i. The other end of the resistor 11d is connected to the drain of the MOSFET 11b. The drain of the MOSFET 11b is connected to the high voltage line of the lighting circuit 7. The high-voltage line is a DC bus on the positive electrode side. The source of the MOSFET 11b is connected to one end of the first resistor 11e. The other end of the first resistance 11e is connected to the anode of the diode 11g, the base of the bipolar transistor 11h, and one end of the second resistance 11i. Therefore, the anode of the diode 11g is connected to the source of the MOSFET 11b and the base of the bipolar transistor 11h via the first resistor 11e, and the cathode is connected to the emitter of the bipolar transistor 11h and the gate of the switch element 7b. .. The collector of the bipolar transistor 11h is connected to the source of the MOSFET 11a and the other end of the second resistance 11i.

The voltage of the switching control unit 10e is a control signal for controlling the on / off of the switch element 7b. The voltage of the switching control unit 10e is increased in the MOSFET 11a and the resistor 11d, and is used for driving the gate of the MOSFET 11b. For example, when the switching control unit 10e is configured by a microcomputer, the voltage output from the switching control unit 10e has a magnitude of 0V to 3.3V, and this is used as the drive voltage of the gate drive circuit, for example, 0V to 0V. The voltage is raised to 10V. The gate drive circuit 11'is connected to the other end of the filter capacitor 8 and one end of the LED 9, and the drive voltage of the gate drive circuit 11'is obtained from the output of the lighting circuit 7. In this case, the drive voltage becomes the same as the voltage output by the lighting circuit 7. Here, as an example, the voltage output by the lighting circuit 7 will be described as 10V. The location where the gate drive circuit 11'is connected is not limited to this, and may be configured to be connected to the positive electrode side of the storage battery 6. In particular, in order to reduce the turn-on loss in the switch element 7b, it is desirable that the drive voltage of the gate drive circuit 11'is high.

FIG. 7 is a waveform showing the operation of the gate drive circuit 11 when the constant voltage circuit 12 is deleted from the lighting fixture 100 of the first embodiment. FIG. 7 shows the output voltage of the switching control unit 10e, the drain voltage of the MOSFET 11a, the gate voltage of the MOSFET 11b, the drain voltage, the gate voltage of the MOSFET 11c, and the drain voltage from the top. The horizontal axis represents time.

In the example of FIG. 7, the operation when the switch element 7b is turned off will be described. At time t1, when the output of the switching control unit 10e goes down, the gate of the MOSFET 11a is discharged, the drain is cut off, and the power is turned off. At time t2, the voltage at the gate of the MOSFET 11c exceeds the on-threshold value Vth2, and the drain conducts and turns on. At time t3, the voltage at the gate of the MOSFET 11b falls below the on-threshold value Vth1, and the drain shuts off and turns off. When the MOSFET 11c is turned on and the MOSFET 11b is turned off, the gate of the switch element 7b is discharged and the drain is turned off. At this time, by deleting the constant voltage circuit 12, in addition to the increase in the drive voltage of the gate drive circuit 11, it is necessary to increase the resistance value of the resistor 11d in order to suppress the loss in the resistor 11d. The inclination when the drain is turned off is relatively large. Therefore, during the period t2 to t3, the gate voltages of the MOSFETs 11b and 11c both exceed the threshold value. That is, since both the MOSFETs 11b and 11c are turned on, a loss may occur in the first resistance 11e and the resistance 11f, and the effect of loss reduction may not be obtained.

The gate drive circuit 11'according to the second embodiment is a circuit in view of the above, and even in a configuration in which the constant voltage circuit 12 is deleted, an operation mode in which both of the two transistors connected in series are turned on. Does not have.

FIG. 8 is a waveform diagram showing the operation of the gate drive circuit 11'in the second embodiment. FIG. 8 shows the output voltage of the switching control unit 10e, the drain voltage of the MOSFET 11a, the gate voltage of the MOSFET 11b, the drain voltage, the base voltage of the bipolar transistor 11h, and the voltage between the emitter and collector from the top. The horizontal axis represents time.

The operation when the switch element 7b is turned off will be described. At time t1, when the output of the switching control unit 10e goes down, the gate of the MOSFET 11a is discharged, the drain is cut off, and the power is turned off. At time t3, the gate voltage of the MOSFET 11b falls below the on-threshold value Vth1, and the drain shuts off and turns off. During the period from time t1 to t3, the diode 11g is conducted as the MOSFET 11b is conducting, and the base of the bipolar transistor 11h is reverse-biased by the forward voltage of the diode 11g, so that the bipolar transistor 11h is in the off state. To maintain.

When the MOSFET 11b is turned off at time t3, the diode 11g is also turned off, so that the reverse bias of the base of the bipolar transistor 11h is released. Since the base-collector of the bipolar transistor 11h is connected by the second resistor 11i, the base is not reverse-biased, and when a voltage is applied to the emitter, the emitter-collector conducts and turns on. When the bipolar transistor 11h is turned on and the MOSFET 11b is turned off, the gate of the switch element 7b is discharged and the drain is turned off. Therefore, the bipolar transistor 11h conducts the discharge path for discharging the gate of the switch element 7b when the switch element 7b is turned off.

Subsequently, the operation when the switch element 7b is turned on will be described. At time t4, when the output of the switching control unit 10e rises, the gate of the MOSFET 11a is charged, and the drain conducts and turns on. Then, the voltage of the gate of the MOSFET 11b is charged, exceeds the on-threshold value Vth1, and the drain conducts and turns on. As a result, the diode 11g is conducted, and the base of the bipolar transistor 11h is reverse-biased by the forward voltage of the diode 11g, so that the collector is cut off and the bipolar transistor 11h is turned off. When the bipolar transistor 11h is turned off and the MOSFET 11b is turned on, the gate of the switch element 7b is charged and the drain is turned on. Therefore, the MOSFET 11b is turned on and off in response to a control signal, and conducts a charging path for charging the gate of the switch element 7b when the switch element 7b is turned on.

As described above, when the charging path of the gate of the switch element 7b is conducting, the bipolar transistor 11h is maintained in the off state, and when the conduction of the charging path is completed, the discharging path of the gate of the switch element 7b is conducted by the bipolar transistor 11h. Will be done.

In the gate drive circuit 11', even when the constant voltage circuit 12 is deleted and the drive voltage of the gate drive circuit 11' is increased and the resistance value of the resistor 11d is increased in order to suppress the loss in the resistor 11d, the MOSFET 11b And the bipolar transistor 11h are both turned on, and there is no operation mode in which a loss occurs in the first resistance 11e. Therefore, the loss generated in the constant voltage circuit 12 is reduced, and by driving the gate of the switch element 7b with a voltage higher than that of the gate drive circuit 11, the turn-on loss in the switch element 7b is reduced and the charging lighting circuit 13 is charged. Loss can be reduced. Further, by adopting a configuration that does not use the constant voltage circuit 12, the number of parts can be reduced and the cost can be reduced.

The configuration shown in the above embodiments shows an example of the contents of the present disclosure, can be combined with another known technique, and is configured as long as it does not deviate from the gist of the above technical features. It is also possible to omit or change a part.

Further, although the case where the LED 9 is used as a light source has been described, the light source is not limited to the LED and may be an organic EL (Electroluminescence).

1 Commercial power supply, 2 rectifier circuit, 3 charging circuit, 3a flyback transformer, 3b, 11a, 11b, 11c MOSFET, 3c, 7c, 11g diode, 3d, 7d, 8, 12d filter capacitor, 4 electrolytic capacitor, 5 regulator, 6 storage battery, 6a, 6b, 6c storage battery cell, 7 lighting circuit, 7a coil, 7b switch element, 7e current detection circuit, 9 LED, 9a LED board, 10 control circuit, 10a power failure detection unit, 10b current detection unit, 10c voltage Detection unit, 10d arithmetic unit, 10e switching control unit, 11, 11'gate drive circuit, 11d, 11f, 12b resistance, 11e first resistance, 11i second resistance, 12 constant current circuit, 11h, bipolar transistor, 12a transistor, 12c Zener diode, 13 charging lighting circuit, 14 input filter, 15a commercial power supply terminal, 15b storage battery terminal, 15c LED board terminal, 16a, 16b lead wiring, 17a, 17b, 17c bus bar wiring, 100, 200 lighting equipment

Claims (10)

With a storage battery in which multiple storage battery cells are connected in series or in parallel,
A lighting circuit that has a coil and a switch element, is connected to the storage battery, and constitutes a DC power conversion circuit.
A control circuit for controlling the continuity state of the switch element is provided.
The control circuit is an emergency lighting device characterized in that the switch element is repeatedly turned on and off so that a current continuously flows through the coil, and the electric power stored in the storage battery is output. The control circuit is
After starting the on / off of the switch element, the on time of the switch element, which is set to a unit time, is lengthened with time.
The emergency lighting device according to claim 1, wherein a predetermined period after starting the on / off of the switch element is provided with a discontinuous period in which the current flowing through the coil becomes substantially zero. The emergency lighting device according to claim 1 or 2, further comprising a steel bus bar wiring for connecting the plurality of storage battery cells. With a storage battery
A lighting circuit that has a coil and a switch element, is connected to the storage battery, and constitutes a DC power conversion circuit.
A control circuit that outputs a control signal for controlling the on / off of the switch element, and
A MOSFET that turns on and off in response to the control signal, a diode whose anode is connected to the source of the MOSFET via a first resistor, a base connected to the anode, an emitter connected to the cathode of the diode, and a collector second. An emergency lighting device comprising: a bipolar transistor connected to the base via a resistor, and a gate drive circuit in which the emitter is connected to the gate of the switch element. The emergency lighting device according to claim 4, wherein the drain of the MOSFET is connected to a high-voltage line of the lighting circuit. With a storage battery
A lighting circuit that has a coil and a switch element, is connected to the storage battery, and constitutes a DC power conversion circuit.
A control circuit that outputs a control signal for controlling the on / off of the switch element, and
It has a MOSFET that conducts a charging path that charges the gate of the switch element when the switch element is turned on, and a bipolar transistor that conducts a discharge path that discharges the gate when the switch element is turned off. It is characterized by comprising a gate drive circuit in which the bipolar transistor is maintained in an off state when the charging path is conducting, and the discharging path is conducted by the bipolar transistor when the conduction of the charging path is completed. Emergency lighting device. The emergency lighting device according to any one of claims 1 to 6, wherein a litz wire obtained by twisting a plurality of copper wires is used as the winding material of the coil. The emergency lighting device according to any one of claims 1 to 7, wherein the switch element is formed of a wide bandgap semiconductor. The emergency lighting device according to claim 8, wherein the wide bandgap semiconductor is silicon carbide, a gallium nitride based material, or diamond. The emergency lighting device according to any one of claims 1 to 9.
A lighting fixture comprising a light source connected to the emergency lighting device.

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