JP5929424B2 - LED lighting device and lighting device using the same - Google Patents

Description

  The present invention relates to an LED lighting device and a lighting device using the same, and more particularly to an LED lighting device including a protection circuit against a normal mode lightning surge and a lighting device using the LED lighting device.

  FIG. 6 shows a circuit diagram of a conventional LED lighting device. The LED lighting device 10 includes a rectifier 4 to which an AC power supply voltage is input, a surge absorber 12 connected to the input side of the rectifier 4, a filter capacitor 3 connected in parallel to the surge absorber 12, and an output of the rectifier 4. A smoothing capacitor 6 connected to the side, and a current control circuit 7 that generates an LED current from the voltage of the capacitor 6 and inputs the LED current to the LED 8 (see, for example, Patent Documents 1 and 2).

  A varistor or the like is used for the surge absorber 12 to protect the LED lighting device 10 from a surge voltage applied in a normal mode (between lines). Specifically, when the surge voltage between the lines reaches the operating voltage of the surge absorber 12, the internal resistance of the surge absorber 12 decreases and the line voltage (that is, the voltage between the input terminals of the rectifying element 4) is close to the operating voltage. Clamped. Since the AC power supply side has a lower impedance than the lighting device 10, the voltage between the input terminals of the rectifying element 4 also returns to the normal AC voltage value when the surge of the AC power supply disappears. If the surge is normal with low energy (low peak or short duration), the line-to-line voltage rises only to near the operating voltage of the surge absorber 12. In addition, since the rising period is short and the energy applied to the output side of the rectifying element 4 is small relative to the capacity of the capacitor 6, the voltage of the capacitor 6 hardly increases or even if it increases, the operating voltage Only rises.

JP 2010-178571 A JP 2010-287459 A

  However, the above configuration causes a problem when a surge having a very large energy such as a lightning surge enters the AC power line. When a lightning surge is applied between the lines, the surge absorber 12 has a current that is about five orders of magnitude larger than that of a normal surge. FIG. 7 shows an example of the current-voltage characteristic curve of the varistor (logarithm on both the vertical and horizontal axes) when a general varistor is used for the surge absorber 12. For example, in the case of a varistor having a voltage of about 500 V at a current of 1 mA (at the start of operation), the voltage at a current of 100 A is about 1000 V, which is about twice that of a current of 1 mA. A lightning surge generally has energy sufficient to generate the current 100A and voltage 1000V. Here, when the current control circuit 7 is in a standby state (a state where the AC power is turned on but the LED 8 is not turned on), the impedance on the output side of the rectifying element 4 is high when viewed from the AC power source side. The lightning surge energy is sufficiently large relative to the capacity of the capacitor 6. Therefore, when a lightning surge voltage is applied between the lines, the energy is charged in the capacitor 6 on the output side of the rectifying element 4, and the voltage of the capacitor 6 rises.

  FIG. 8 shows a change in voltage of each part when a lightning surge is applied between the lines of the LED lighting device 10 of FIG. The dotted line in the figure is an imaginary curve of the line voltage when the surge absorber 12 is not connected. Vz on the vertical axis is the operating voltage (for example, 500 V) of the surge absorber 12. When a lightning surge is applied at t0, the line voltage increases. When the line voltage (that is, the voltage V12 of the surge absorber 12) reaches the operating voltage Vz at t1, the clamp operation of the surge absorber 12 is started. However, since the lightning surge energy is very large, the current of the surge absorber 12 and The voltage rises. When the lightning surge passes the peak (Vmax) at t2, the voltage V12 of the surge absorber 12 decreases due to the clamping operation.

  On the other hand, when the lightning surge voltage is charged in the capacitor 6 from t0 to t2, the voltage Vmax is maintained as the voltage V6 of the capacitor 6 after t2. After t3, when the lightning surge voltage is lowered, the voltage V12 of the surge absorber 12 is also lowered together with the voltage on the AC power source side having a low impedance. However, on the output side of the rectifying element 4, even when the voltage on the AC power supply side returns to a normal state, the state where the high voltage Vmax is charged in the capacitor 6 continues. As described above, although the lightning surge is short, if the overvoltage is applied to the circuit element on the output side of the rectifying element 4 for a long time, the rectifying element 4, the capacitor 6 or the current control circuit 7 may be damaged. There is. Furthermore, when the current control circuit 7 is a non-insulated circuit, the LED 8 may be broken.

  Therefore, the present invention provides an LED lighting device and a lighting device using the same, in which countermeasures for the normal mode lightning surge are strengthened so that the circuit on the output side of the rectifying element can be protected even if a lightning surge is applied between the lines. The issue is to provide.

  A first aspect of the present invention is an LED lighting device that lights an LED in response to power supplied from an AC power source, and is connected between a rectifier element to which power supplied from the AC power source is input and an input terminal of the rectifier element. The first surge absorber, the second surge absorber connected between the output terminals of the rectifying element, the capacitor connected between the output terminals of the rectifying element, and the current that generates an LED current from the voltage of the capacitor and inputs it to the LED In the current-voltage characteristics of the first and second surge absorbers provided with a control circuit, the current flowing through the second surge absorber when the same voltage is applied is smaller than the current flowing through the first surge absorber.

  Here, the first and second surge absorbers are varistors, and the operating voltage of the second surge absorber is higher than the operating voltage of the first surge absorber.

  The first and second surge absorbers are made of the same material varistor, and the operating voltage of the second surge absorber is 1.05 to 1.21 times the operating voltage of the first surge absorber. It is preferable to do.

  Furthermore, the first and second surge absorbers are made of the same material varistor, and the operating voltage of the second surge absorber is 1.05 to 1.10 times the operating voltage of the first surge absorber. It is preferable to make it.

  Further, the first and second surge absorbers can be varistors of the same material having the nth and n + 1th operating voltages in the E24 series of the JIS C 5063 standard number sequence, respectively.

  A second aspect of the present invention is an illumination device including the LED lighting device according to the first aspect, an LED connected to an output end of the LED lighting device, and a housing that contains the LED lighting device.

It is a circuit diagram which shows the LED lighting device of this invention. It is a circuit diagram explaining the LED lighting device of this invention. It is a figure explaining operation | movement of the LED lighting device of this invention. It is a figure explaining the LED lighting device of this invention. It is a figure which shows the illuminating device of this invention. It is a circuit diagram which shows the conventional LED lighting device. It is a figure which shows the characteristic of a general varistor. It is a figure explaining operation | movement of the conventional LED lighting device.

  FIG. 1 shows an LED lighting device according to an embodiment of the present invention. The LED lighting device 1 includes a rectifier element 4 to which power supply from an AC power supply AC is input, a surge absorber 2 connected between input terminals of the rectifier element 4, a surge absorber 5 connected between output terminals of the rectifier element 4, A capacitor 6 connected between the output terminals of the rectifying element 4 and a current control circuit 7 that generates an LED current from the voltage of the capacitor 6 and inputs the LED current to the LED 8 are provided. The capacitor 3 is a filter capacitor, and the rectifying element 4 is a full-wave rectifier. Moreover, although a single element is illustrated as the LED 8, the LED 8 is illustrated to include a configuration in which a plurality of LED elements are connected in series.

  For example, a step-down chopper circuit as shown in FIG. 2 can be used for the current control circuit 7. The current control circuit 7 includes a PWM control circuit 71, a transistor 72, a capacitor 73, a coil 74, a diode 75, and a current detection resistor 76. When the transistor 72 is in the on state, a current flows through the diode 8, the coil 74, the transistor 72, and the current detection resistor 76. When the transistor 72 is in the off state, the current is converted to the diode 75 based on the energy stored in the coil 74. And the LED 8 flows. The PWM control circuit 71 drives the transistor 72 by determining the ON width of the transistor 72 so that the voltage generated in the current detection resistor 76, that is, the LED current becomes a predetermined value. In addition to the step-down chopper circuit, a known circuit configuration such as a flyback circuit using an insulating transformer can be used for the current control circuit 7.

  In the present invention, the surge absorbers 2 and 5 are clamp-type, that is, non-linear resistance surge absorbers that function to maintain a constant voltage when a surge voltage is applied. Specifically, metal oxide varistors (hereinafter referred to as “varistor 2” and “varistor 5”) are used as the surge absorbers 2 and 5 in this embodiment, but a Zener diode or the like can also be used. The operating voltage of the varistor 5 is slightly higher than the operating voltage of the varistor 2. The reason for this will be described later.

  FIG. 3 shows voltages at various parts when a lightning surge is applied between the lines of the LED lighting device of FIG. The dotted lines in the figure are curves showing virtual line voltages when the varistors 2 and 5 are not connected, and Vz2 and Vz5 on the vertical axis are the operating voltages of the varistors 2 and 5, respectively. When a lightning surge is applied at t0, the line voltage increases. When the line-to-line voltage reaches the operating voltage Vz2 at t1, the clamping operation of the varistor 2 is started. However, since the lightning surge energy is very large, the current and voltage of the varistor 2 increase. When the line voltage reaches the operating voltage Vz5 at t2, the clamping operation of the varistor 5 is started. When the lightning surge passes the peak (Vmax) at t3, the voltages V2 and V5 of the varistors 2 and 5 also decrease by the respective clamping operations.

  After t4, as the lightning surge voltage decreases, the voltage V2 of the varistor 2 also decreases together with the voltage on the AC power supply side. Further, the voltage V5 of the varistor 5 is lowered together with the voltage of the capacitor 6 by the clamping operation until the voltage V5 of the varistor 5 is lowered to the operating voltage Vz5. When the voltage V5 of the varistor 5 drops to the operating voltage Vz5 at t5, the state in which the capacitor 6 is charged is maintained. Thus, when the voltage on the AC power supply side returns to a normal state, the output side of the rectifying element 4 becomes a voltage equal to or lower than the operating voltage Vz5 of the varistor 5. Therefore, unlike the operation of FIG. 8 by the conventional circuit of FIG. 6, the voltage of the capacitor 6 is not maintained at the voltage Vmax at the time of lightning surge peak. That is, overvoltage protection on the output side of the rectifying element 4 during a lightning surge is realized.

  Here, regarding the relationship between the varistor 2 and the varistor 5, if the varistor 2 and the varistor 5 have the same specifications (the same material and operating voltage), the same current flows through both when a lightning surge is applied. Specifically, when the varistor shown in FIG. 7 is used for both the varistors 2 and 5, a current of about 50 A flows through each. Here, particularly in the case of a small LED current with an output power of several watts, the current flowing through the varistor 5 greatly exceeds the current capacity of the rectifying element 4 (for example, about 1 A), which may cause a failure of the rectifying element 4. is there. This overcurrent failure can occur regardless of whether the current control circuit 7 is in operation or is in standby (standby state).

  Therefore, in the present invention, the constant is set so that the operating voltage of the varistor 5 is higher than the operating voltage of the varistor 2. FIG. 4 is a voltage-current characteristic curve (logarithm on both the vertical and horizontal axes) for varistors A, B and C made of the same material (specifications other than the operating voltage are the same). The varistors A, B, and C are assumed to be the nth, n + 1th, and n + 2th in the E24 series of the JIS C 5063 standard number sequence. Therefore, the operating voltage of varistor B is about 10% higher than the operating voltage of varistor A, and the operating voltage of varistor C is about 21% higher than the operating voltage of varistor A.

  Comparing varistor A and varistor B, the current flowing through varistor B is about 10 A for the same applied voltage of about 1000 V, which is about 1/10 of the current flowing through varistor A (about 100 A). Comparing varistor A and varistor C, the current flowing through varistor C is about 1 A for the same applied voltage of about 1000 V, and is about 1/100 of the current flowing through varistor A (about 100 A). Further, assuming a varistor A ′ (not shown) whose operating voltage is about 5% higher than that of the varistor A, the current flowing through the varistor A ′ is about 1/5 of the current flowing through the varistor A with respect to the same voltage value. is expected. Therefore, when the applied voltage is 1000 V, the current flowing through the varistor A ′ is about 20 A, and approaches the upper limit of the current that does not cause a failure even if it flows through the rectifying element 4 for a short time (depending on the current withstand capability of the rectifying element 4). .

  As described above, for the varistors 2 and 5 made of the same material, the operating voltage of the varistor 5 is made higher than the operating voltage of the varistor 2, thereby reducing the current flowing through the varistor 5 through the rectifier 4 when a lightning surge is applied. be able to. That is, if the operating voltage of the varistor 5 is set to 1.05 to 1.21 times the operating voltage of the varistor 2, the ratio of the current flowing through the varistor 5 to the current flowing through the varistor 2 is set to about 5: 1 to 100: 1. be able to. If the operating voltage of the varistor 5 is 1.05 to 1.10 times the operating voltage of the varistor 2, the ratio of the current flowing through the varistor 5 to the current flowing through the varistor 2 is set to about 5: 1 to 10: 1. be able to.

  Moreover, if the operating voltage difference between the varistor 2 and the varistor 5 is large, it becomes difficult to ensure an appropriate overvoltage protection function. For example, if the operating voltage of the varistor 2 is too small, a protection operation (clamping operation of the varistor 2) is performed even for a surge with a low peak that does not require protection, and the life of the varistor 2 is shortened. On the other hand, if the operating voltage of the varistor 5 is too high, the overvoltage protection function on the output side of the rectifying element 4 is diminished. Therefore, the operating voltage of the varistor 5 is desirably 1.21 times or less, more preferably 1.10 times or less that of the varistor 2.

  From the above viewpoint, as one design example, when the AC power supply voltage is 200 V, the operating voltage of the varistor 2 is 430 V (nominal value) and the operating voltage of the varistor 5 is 470 V (nominal value). Specifically, when the voltage of the varistors 2 and 5 is 1000 V, the flowing current is divided into about 90 A and 10 A, respectively. Thereby, failure of the rectifying element 4 can be prevented even when the varistor 5 is operated. When the AC power supply voltage is 100 V, the operating voltage of the varistor 2 may be 200 V (nominal value), and the operating voltage of the varistor 5 may be 220 V (nominal value).

  If the varistors 2 and 5 having the nth and n + 1th operating voltages in the E24 series of the JIS C 5063 standard number sequence are used for the varistors of the same material (specifications other than the operating voltage are the same), the operation of the varistor 5 The voltage can be about 1.10 times the operating voltage of the varistor 2. As described above, when selecting varistors made of the same material, the design can be optimized and facilitated by using the adjacent values of the standard number sequence.

  Thus, by making the operating voltage of the varistor 5 5-21%, preferably 5-10% higher than the operating voltage of the varistor 2, overvoltage protection on the output side of the rectifying element 4 during lightning surge application is ensured. However, overcurrent prevention of the rectifying element 4 can be realized. Thereby, the probability that the LED lighting device will fail due to lightning surge can be greatly reduced.

  In the embodiment, varistors of the same material (same specifications except operating voltage) are used as the surge absorbers 2 and 5, but surge absorbers of different materials may be used. That is, for two surge absorbers having a current ratio of 5: 1 to 100: 1, preferably 5: 1 to 10: 1 when a voltage of about 1000 V is applied, the surge absorber having the larger current value is used. Second, the smaller current value may be applied to the surge absorber 5.

  FIG. 5 shows a schematic configuration of a lighting device equipped with the LED lighting device 1 of the above embodiment. The lighting device includes an LED lighting device 1 that is fed from an AC power source via wirings L1 and L2, an LED 8 connected to an output end of the LED lighting device 1, and a housing 9 that encloses the LED lighting device 1. In FIG. 5, the LED lighting device 1 and the LED 8 are integrated, but the LED 8 may be separately provided from the LED lighting device 1 and the housing 9 via a cable.

  In this way, by mounting the LED lighting device with enhanced lightning surge countermeasures, it is possible to provide an illumination device that can be installed even in areas where lightning strikes frequently.

1. LED lighting device 2. 2. Surge absorber Capacitor 4. 4. Rectifier element Surge absorber 6. Capacitor 7. 7. Current control circuit LED
9. Enclosure

Claims (6)

An LED lighting device that lights an LED by receiving power from an AC power source,
A rectifying element to which the power supply is input;
A first surge absorber connected between the input terminals of the rectifying element;
A second surge absorber connected between the output terminals of the rectifying element;
A capacitor connected between the output terminals of the rectifying element; and a current control circuit that generates an LED current from the voltage of the capacitor and inputs the LED current to the LED,
In the current-voltage characteristics of the first and second surge absorbers, the ratio of the current flowing through the first surge absorber and the current flowing through the second surge absorber when a voltage of 1000 V is applied is 5: 1 to 1. LED lighting device which is 100: 1 . 2. The LED lighting device according to claim 1, wherein in the current-voltage characteristics of the first and second surge absorbers, a current flowing through the first surge absorber and a second surge when a voltage of 1000 V is applied. The LED lighting device in which the ratio of the current flowing through the absorber is 5: 1 to 10: 1. An LED lighting device that lights an LED by receiving power from an AC power source,
A rectifying element to which the power supply is input;
A first surge absorber connected between the input terminals of the rectifying element;
A second surge absorber connected between the output terminals of the rectifying element;
A capacitor connected between the output terminals of the rectifying element; and
A current control circuit that generates an LED current from the voltage of the capacitor and inputs the LED current to the LED
With
The first and second surge absorbers are made of the same material varistor, and the operating voltage of the second surge absorber is 1.05 to 1.21 times the operating voltage of the first surge absorber Lighting device. 4. The LED lighting device according to claim 3 , wherein the first and second surge absorbers are made of the same material varistor, and the operating voltage of the second surge absorber is 1. LED lighting device which is 05 times or more and 1.10 times or less. An LED lighting device that lights an LED by receiving power from an AC power source,
A rectifying element to which the power supply is input;
A first surge absorber connected between the input terminals of the rectifying element;
A second surge absorber connected between the output terminals of the rectifying element;
A capacitor connected between the output terminals of the rectifying element; and
A current control circuit that generates an LED current from the voltage of the capacitor and inputs the LED current to the LED
With
The LED lighting device comprising the varistors of the same material, wherein the first and second surge absorbers have the n-th and n + 1-th value operating voltages in the E24 series of the JIS C 5063 standard number sequence, respectively. An LED lighting device according to any one of claims 1 to 5, an LED connected to an output end of the LED lighting device, and an illuminating device including a housing containing the LED lighting device.

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