JP2014082148A - Led lighting device, and led illuminating fixture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED lighting device having a switching power supply circuit, capable of achieving a configuration by which a high input power factor can be obtained over a wide input current range, and thereby, to provide a standard power supply that matches various types of LED illuminating fixtures.SOLUTION: An LED lighting device 1 comprises: a rectification circuit 3 rectifying an AC input current; a first capacitor 4 in which an output of the rectification circuit is charged; a switching power supply circuit 5 converting a voltage of the first capacitor into a predetermined DC output, and applying it to an LED array; and a capacitor switching circuit 6. The capacitor switching circuit comprises: an input current detector detecting the AC input current; a switch part that becomes in a conduction state when an AC input current value detected at the input current detector becomes larger than a predetermined value; and a second capacitor 67 connected in series to the switch part. A series circuit of the switch part and the second capacitor is connected in parallel with the first capacitor.

Description

  The present invention relates to an LED lighting device and an LED lighting apparatus using the LED lighting device.

  In recent years, the brightness of LEDs has increased, and lighting fixtures using LED light sources instead of incandescent lamps, fluorescent lamps, high-pressure discharge lamps, and the like are becoming widespread. In the case of fluorescent lamps, high-pressure discharge lamps, etc., rated values (rated power, rated current) are set for each lamp type, so the electronic ballast that controls the lamp current also has a rated output for each lamp. Value is set. Therefore, there is an electronic ballast adapted for each lamp type. In the case of an LED light source, since the LED element emits light by a direct current, an LED lighting device composed of a direct current constant current power source is generally used as an electronic ballast. Here, the number of LED elements to be mounted varies depending on the specifications of the lighting fixture, that is, the number of connections can be arbitrarily set even if the type of LED elements is the same, so the output mode of the LED lighting device is not the type of LED elements It will be present depending on the type of lighting fixture.

  Here, if an LED lighting device having a dedicated output setting for each lighting fixture is designed, the model of the device becomes very large, so it is standardized so that one LED lighting device can support a plurality of lighting fixtures. It is desirable to design an LED lighting device (standard power supply). In this case, the number of LED elements is selected within the range of allowable power (rated power) and allowable current (rated current) of the standard power supply, and the LED current is adjusted. For example, when the maximum output power of the standard power supply is 100 W and the maximum output current is 500 mW, an arbitrary number of LED elements can be connected in series within a range in which the LED voltage is 200 V or less and the LED current is 500 mA or less. (Furthermore, the LED current is adjusted according to the required specifications).

  A circuit configuration of a general LED lighting device is disclosed in Patent Document 1, for example. Referring to this document, the input from the AC power source (Vs) is filtered by the filter circuit unit (3), is full-wave rectified by the full-wave rectifier (BD), and the full-wave rectified output is smoothed by the capacitor (C1). . The voltage smoothed by the capacitor is converted into a direct current by a switching power supply circuit unit (1) including a flyback converter and the direct current is input to the LED light emitting unit (2), and each LED emits light.

JP 2009-134945 A

  In the standard power supply as described above, it is required to secure a predetermined input power factor for the input voltage range defined by the specifications and the load power range corresponding to the number of LED elements connected. And with the diversification of LED lighting fixtures, the input voltage range and load power range (number of LED elements connected) that should correspond to one standard power supply tend to be expanded.

  Here, even when the input voltage range and the load power range are expanded, it is necessary to ensure a predetermined input power factor over the entire range. For example, as will be described in detail later, there may be a case where the input current is very small at the maximum input voltage and the minimum load power, or a case where the input current is maximum at the minimum input voltage and the maximum load power. However, in the configuration of a general LED lighting device, it is difficult to ensure a high input power factor (for example, 90% or more) for such extreme settings, that is, for a wide input current range. was there.

  Therefore, the present invention realizes a configuration capable of obtaining a high input power factor over a wide input current range in an LED lighting device having a switching power supply circuit, thereby providing a standard power supply suitable for various LED lighting fixtures. This is the issue.

  The LED lighting device of the present invention includes a rectifier circuit that rectifies an AC input current, a first capacitor that is charged with the output of the rectifier circuit, converts the voltage of the first capacitor into a predetermined DC output, and inputs it to the LED array. A switching power supply circuit and a capacitor switching circuit are provided. The capacitor switching circuit includes an input current detection unit that detects an AC input current, and a switch that is turned on when the AC input current value detected by the input current detection unit exceeds a predetermined value. And a second capacitor connected in series to the switch unit, and a series circuit of the switch unit and the second capacitor is connected in parallel to the first capacitor.

  Here, the first capacitor may be a film capacitor of 0.1 μF to 1 μF. In addition, the input current detection unit includes a current transformer having a primary winding inserted in one of the input lines before the rectifier circuit, and when the voltage generated in the secondary winding of the current transformer exceeds a predetermined value, the switch unit It is preferable to be configured to be in a conductive state.

  The LED lighting apparatus of the present invention includes the LED lighting device, an LED array fed from the LED lighting device, and a housing that contains the LED lighting device.

It is a figure which shows the LED lighting device by the Example of this invention. It is a figure explaining operation | movement of the LED lighting device of an Example. It is a figure explaining operation | movement of the LED lighting device of an Example and a comparative example. It is a figure explaining operation | movement of the LED lighting device of an Example. It is a figure explaining operation | movement of the LED lighting device of an Example. It is a figure which shows the LED lighting device by the modification of this invention. It is a figure which shows the LED lighting device of a comparative example. It is a figure explaining operation | movement of the LED lighting device of a comparative example. It is a figure explaining operation | movement of the LED lighting device of a comparative example. It is a figure explaining operation | movement of the LED lighting device of a comparative example. It is a figure explaining operation | movement of the LED lighting device of a comparative example. It is a figure explaining operation | movement of the LED lighting device of a comparative example.

Example.
FIG. 1 shows a circuit diagram of an LED lighting device (hereinafter referred to as “lighting device”) according to an embodiment of the present invention. The lighting device 1 of the present invention includes a filter circuit 2, a rectifier circuit 3, a capacitor 4 (first capacitor), a switching power supply circuit 5, and a capacitor switching circuit 6. The lighting apparatus includes the lighting device 1, the LED array 7 to which power is supplied from the lighting device 1, and a housing (not shown) that encloses the lighting device 1. In the following description, it is convenient for each circuit element to belong to which circuit, and the present invention is not bound thereto. In the following description, “input voltage” means an AC input voltage supplied from the AC power source to the lighting device 1, and “input current” means an AC input current flowing from the AC power source to the lighting device 1. It means that.

  The filter circuit 2 includes a capacitor 20, a coil 21, and a capacitor 22, and reduces power line noise, that is, noise that can be propagated from the lighting device 1 to the AC power source. The rectifier circuit 3 is a full-wave rectifier such as a diode bridge, and full-wave rectifies the AC input that has passed through the filter circuit 2. The capacitor 4 is formed of a film capacitor of 0.1 μF or more and 1 μF or less, and the full wave rectified output of the rectifier circuit 3 is charged.

  The switching power supply circuit 5 is formed of a flyback converter using the capacitor 4 as a power source in this embodiment, and includes a transformer 50, a transistor 51, a diode 52, a capacitor 53, a current detection resistor 54, an operational amplifier 55, a voltage source 56, a photocoupler 57, And a control circuit 58. The transistor 51 is made of, for example, a MOSFET, and is controlled to be turned on / off at a high frequency (for example, several tens of kHz) by the control circuit 58 to switch the primary winding of the transformer 50. Based on the energy stored in the transformer 50 when the transistor 51 is turned on, the voltage generated in the secondary winding of the transformer 50 is rectified and smoothed by the diode 52 and the capacitor 53, and a DC output is obtained. As a result, a direct current output is input to the LED array 7.

  A detection voltage corresponding to the current flowing through the LED array 7 is generated in the current detection resistor 54, and the detection voltage is input to one terminal (−) of the operational amplifier 55. The set voltage from the voltage source 56 is input to the other terminal (+) of the operational amplifier 55. The operational amplifier 55 outputs an error between the detection voltage and the reference voltage, and determines the forward current of the diode of the photocoupler 57. A fixed voltage source is connected to the anode input terminal of the photocoupler 57. A fixed voltage source is connected to the transistor of the photocoupler 57 via a resistor.

  In this embodiment, the control circuit 58 is composed of a driver IC, and the output of the photocoupler 57 is averaged and input to the feedback (FB) terminal. In the control circuit 58, the FB terminal voltage is input to one terminal (+) of the comparator 58a, the output of the internal oscillator OSC is input to the other terminal (−), and the ON time of the transistor 51 is determined by the comparison output. Is done. Accordingly, the transistor 51 is PWM-controlled so that the ON width of the transistor 51 is increased when the LED current is smaller than the set value, and the ON width of the transistor 51 is decreased when the LED current is larger than the set value. Also, as shown in FIG. 2, the transistor 51 is intermittently switched for half a cycle of the input voltage, and this switching operation causes the input current waveform to be approximately proportional to the input voltage waveform and approaches a sine wave. Thereby, a high input power factor can be realized by a switching operation by one flyback converter circuit.

  The capacitor switching circuit 6 includes an input current detection unit that detects an input current, a switch unit that becomes conductive when an input current value detected by the input current detection unit exceeds a predetermined value, and a capacitor 67 that is connected in series to the switch unit. (Second capacitor) is provided, and a series circuit of the switch unit and the capacitor 67 is connected in parallel to the capacitor 4.

  The input current detection unit includes a current transformer 60, a diode 61, a capacitor 62, a resistor 63, and a Zener diode 64. The primary winding of the current transformer 60 is inserted into one input line L1 at the preceding stage of the rectifier circuit 3, and a rectifying and smoothing circuit including a diode 61, a capacitor 62, and a resistor 63 is connected to the secondary winding side. The negative terminal side of the capacitor 62 is connected to the reference potential line L2. The cathode of the Zener diode 64 is connected to the positive terminal side of the capacitor 62, and the anode of the Zener diode 64 is connected to the base of the transistor 65.

  The switch unit includes a transistor 65 and a diode 66, and the transistor 65 and the diode 66 are connected in antiparallel between the capacitor 67 and the reference potential line L2. That is, the collector of the transistor 65 and the cathode of the diode 66 are connected to the capacitor 67, and the emitter of the transistor 65 and the anode of the diode 66 are connected to the reference potential line L2.

  The operation of the capacitor switching circuit 6 will be described. When an AC input current flows through the input line L1, a voltage proportional to the input current is generated in the secondary winding of the current transformer 60. The voltage generated in the secondary winding is rectified and smoothed by the diode 61, the capacitor 62, and the resistor 63 having an appropriate resistance value, and a DC voltage proportional to the input current value is obtained. When the DC voltage of the capacitor 62 is equal to or lower than the Zener voltage of the Zener diode 64, the transistor 65 is maintained in an off state (non-conducting state), and no charging current flows through the capacitor 67. Therefore, the capacitor 67 is maintained in a non-connected state. On the other hand, when the DC voltage of the capacitor 62 exceeds the Zener voltage of the Zener diode 64, a current is supplied from the capacitor 62 to the base of the transistor 65, and the transistor 65 is maintained in an on state (conductive state).

  When the transistor 65 is conductive, the capacitor 67 is connected between the high potential line L3 and the reference potential line L2, similarly to the capacitor 4. Therefore, when the capacitor 67 is charged, current flows from the high potential line L3 on the cathode side of the rectifier circuit 3 to the reference potential line L2 via the capacitor 67 and the transistor 65, and when the capacitor 67 is discharged, the diode 66 and the capacitor are connected from the reference potential line L2. A current flows through the high potential line L3 via 67.

  Here, as a comparative example, a general lighting device 10 without the capacitor switching circuit 6 will be described. FIG. 6 shows a circuit diagram of the lighting device 10 of the comparative example, and its operation will be described with reference to FIGS. 2, 3, 7A, 7B, 8A, 8B, and 9. FIG.

  FIG. 3 shows voltage / current waveforms of respective parts during operation near the design center value of the lighting device 10 (that is, the design center value of the input current). When the input voltage shown in (a) is input, the input voltage is full-wave rectified by the rectifier circuit 3 as shown in (c), and this becomes the voltage of the capacitor 4. A DC voltage is applied to the LED array 7 by the operation of the switching power supply circuit 5 that receives the voltage of the capacitor 4 as shown in FIG. The LED voltage has a slight ripple synchronized with the input voltage, but is substantially a DC voltage. The current supplied to the LED array 7 is a direct current having a ripple synchronized with the power supply voltage due to the power factor improving operation by the switching power supply circuit 5 as shown in FIG. Further, as described above with reference to FIG. 2, the input current waveform is substantially proportional to the input voltage waveform by the switching control of the transistor 51 and approaches a sine wave. As a result, as shown in FIG. 3B, the input current waveform is approximated to a sine wave, so that a high input power factor is expected to be realized. However, the lighting device 10 has a problem that the range of the input current from which the high input power factor operation as described above is obtained is narrow.

  Here, it is assumed that the capacity of the capacitor 4 of the lighting device 10 is selected to a size that can supply the operating current of the switching power supply circuit 5 at the maximum load (at the time of the maximum input current). Specifically, the lighting device 10 is designed such that the maximum output power is 100 W and the maximum output current is 500 mA, and the capacitance of the capacitor 4 is 0.47 μF. Moreover, the lighting device 10 shall be designed to respond | correspond to the input voltage of AC100V, AC200V, and AC240V. FIG. 7A shows the relationship between LED power and input current (effective value) for each input voltage in this design. FIG. 7B shows the relationship between LED power and input power factor under the same conditions as in FIG. 7A.

  According to the above design, as shown in FIG. 7B, when the input voltage is low or the LED power is high, that is, when the input current is large, a high input power factor is secured. On the other hand, when the input voltage is high (for example, AC 240 V) and the LED power is low, that is, when the input current is small, the input power factor decreases. This is because the ratio of the current flowing through the capacitor 4 to the input current corresponding to the power consumption in the LED array 7 is increased.

  On the other hand, it is assumed that the capacity of the capacitor 4 of the lighting device 10 is selected to be a size that can secure the input power factor at a low input current. Specifically, in the lighting device 10 described above, the capacitance of the capacitor 4 is changed to 0.1 μF. FIG. 8A shows the relationship between LED power and input current (effective value) for each input voltage in this design. FIG. 8B shows the relationship between LED power and input power factor under the same conditions as in FIG. 8A.

  According to the above design, as shown in FIG. 8B, when the input voltage is high or the LED power is low, that is, when the input current is small, a high input power factor is secured. On the other hand, when the input voltage is low (for example, AC 100V) and the LED power is high, that is, when the input current is large, the input power factor decreases. In particular, when the input current exceeds a certain point (near 0.9 A), the reduction of the input power factor becomes significant. This is because the capacity of the capacitor 4 is insufficient with respect to the high-frequency switching current in the switching power supply circuit 5, and the high-frequency current flows from the AC power supply to the lighting device 10 side through the filter circuit 2.

  FIG. 9 shows waveforms at various parts at the time of low input current in the settings of FIGS. 8A and 8B. 9 (a), (c), (d) and (e) substantially correspond to (a), (c), (d) and (e) of FIG. 3, but FIG. 9 (b) Is different from FIG. As shown in FIG. 9B, the input current waveform of the lighting device 10 is a waveform in which a high-frequency current is superimposed on a substantially sinusoidal input current. As a result, in addition to the decrease in the input power factor, the temperature rises in the coil 21 and the full-wave rectifier circuit 3 due to the increase in the input current, and the peripheral devices due to the high-frequency current flowing in the AC power line. Adverse effects such as noise can be a problem.

  On the other hand, in the lighting device 1 (FIG. 1) according to the embodiment of the present invention, as described above, when the input current is equal to or less than the predetermined value, the transistor 65 of the capacitor switching circuit 6 becomes non-conductive, and the predetermined value Is exceeded, the transistor 65 of the capacitor switching circuit 6 is configured to be in a conductive state. Therefore, when the input current is small, the capacitor 4 is connected singly and the operation is performed with a small composite capacity setting. When the input current exceeds a predetermined value, the parallel circuit of the capacitor 4 and the capacitor 67 is connected and large. The operation is performed with the composite capacity setting.

  Therefore, when the input current is small (the input voltage is high and the LED power is low), the capacitance of the capacitor connected between the output terminals of the rectifier circuit 3 can be reduced to ensure the input power factor. . On the other hand, when the input current is large, for example, when the input voltage is low (AC100V) and the LED power is high (the number of LED connection elements is large), the combined capacity of the capacitors connected between the input terminals of the switching power supply circuit 5 To increase the input power factor. That is, the waveforms of the respective parts shown in FIG. 3 are obtained over the entire range of the assumed input current.

  Therefore, assuming the same required specifications as the lighting device 10 of the comparative example, that is, the maximum output power is 100 W, the maximum output current is 500 mA, and the input voltage is AC100V to 240V, the capacity of the capacitor 4 is about 0.1 μF. The capacitance of the capacitor 67 may be any as long as the combined capacitance with the capacitor 4 is about 0.47 μF (0.33 μF to 0.47 μF, etc.). Note that the capacities of the capacitors 4 and 67 are set according to the maximum output power, the maximum output current, the input voltage range, and the like specified by the required specifications of the standard power supply. However, since film capacitors are used for the capacitors 4 and 67, it is desirable that each capacitance be 1 μF or less in consideration of availability, cost, size, and the like.

  In this embodiment, the specification of the current transformer 60 and the Zener diode 64 are set such that the transistor 65 is turned on at any point between 0.6 A and 0.8 A of the input current value (effective value), for example. The Zener voltage or the like may be selected. However, the input current value for turning on the transistor 65 is appropriately set according to the required specifications of the standard power supply.

  FIG. 4A shows the relationship between LED power and input current for each input voltage in lighting device 1, and FIG. 4B shows the relationship between LED power and input power factor under the same conditions. As can be seen from FIG. 4B, according to the lighting device 1 of the present embodiment, a high input power factor of 90% or more can be obtained in all ranges of LED power, input voltage, and input current.

  As described above, according to the present invention, in a lighting device having a switching power supply circuit, a high input power with a low power supply voltage and a high output power is ensured while ensuring a power factor at a low input current with a high power supply voltage and a low output power. The input power factor at the time of current can also be secured. Thereby, a standard power supply suitable for more types (specifications) of LED lighting fixtures can be provided. The capacitor switching circuit 6 can be implemented with a relatively simple configuration and is suitable in terms of cost and size. Furthermore, according to the present invention, it is possible to provide an LED lighting apparatus that covers a wide input voltage range and a wide output power range with a high input power factor.

Modified example.
The preferred embodiments of the present invention have been described above, but the present invention can be modified in various ways as follows.

  In the above embodiment, the switching power supply circuit 5 is a so-called one-converter type that performs power factor improvement and DC conversion with a single converter circuit. However, the switching power supply circuit 5 includes an individual power factor correction circuit (PFC) and A DC conversion circuit may be provided. For example, as shown in FIG. 5, the switching power supply circuit 5 may include a power factor correction circuit 8 and a DC / DC converter circuit 9. As described above, the capacitor 4 may be used alone or a parallel circuit of the capacitor 4 and the capacitor 67 may be connected to the input terminal of the power factor correction circuit 8 according to the input current. The power factor correction circuit 8 may be a step-up chopper circuit including a coil 80, a transistor (MOSFET) 81, a diode 82, a capacitor 83, and a control circuit 84, for example. Further, the DC / DC converter circuit 9 may be composed of a known flyback circuit and step-down chopper circuit. In this case, in the DC / DC converter circuit 9, it is not necessary to ensure the power factor improving effect, so that the degree of freedom in design increases.

  In the above embodiment, the combined capacitance of the capacitors is switched to two stages, but may be switched to three or more stages. For example, when switching to three stages, a set of the same configuration as the Zener diode 64, the transistor 65, the diode 66, and the capacitor 67 is further provided so that Zener diodes having different Zener voltages are selected for the two Zener diodes. do it.

  In the above embodiment, the current transformer 60 is connected to the front stage (input line L1) of the rectifier circuit 3, but is connected to the rear stage of the rectifier circuit 3 (reference potential line L2 or high potential line L3) and before the capacitor 67. Also good.

  In the above embodiment, the switch portion of the capacitor switching circuit 6 is configured by the transistor 65 and the diode 66, but the switch portion may be configured by a MOSFET with a regenerative diode. In this case, the capacitor switching circuit includes a comparator, the output of the input current detection unit is connected to the positive input terminal of the comparator, the constant voltage source for supplying a threshold is connected to the negative input terminal, and the gate terminal of the MOSFET is connected to the output terminal. What is necessary is just to make it connect. Thereby, when the detection value by the input current detection unit exceeds the threshold value, the output of the comparator is in a high state, the MOSFET is in a conductive state, and the same operation and effect as in the embodiment can be obtained.

1 LED lighting device 2 Filter circuit 3 Rectifier circuit 4 Capacitor (first capacitor)
5 Switching power supply circuit 6 Capacitor switching circuit 60 Current transformer 61 Diode 62 Capacitor 63 Resistor 64 Zener diode 65 Transistor 66 Diode 67 Capacitor (second capacitor)
7 LED array 8 Power factor improvement circuit 9 DC / DC converter circuit

Claims (4)

An LED lighting device,
Rectifier circuit to rectify AC input current,
A first capacitor in which the output of the rectifier circuit is charged;
A switching power supply circuit that converts the voltage of the first capacitor into a predetermined DC output and inputs it to the LED array, and a capacitor switching circuit, the input current detection unit for detecting the AC input current, the input current detection unit A switch unit that is rendered conductive when the AC input current value detected by the switch exceeds a predetermined value, and a second capacitor connected in series to the switch unit, the series circuit of the switch unit and the second capacitor An LED lighting device comprising a capacitor switching circuit connected in parallel to the first capacitor.   The LED lighting device according to claim 1, wherein the first capacitor is a film capacitor of 0.1 μF to 1 μF.   2. The LED lighting device according to claim 1, wherein the input current detection unit includes a current transformer in which a primary winding is inserted in one of the input lines of the preceding stage of the rectifier circuit, and the secondary winding of the current transformer An LED lighting device configured such that when the generated voltage exceeds a predetermined value, the switch unit becomes conductive.   The LED lighting device provided with the LED lighting device as described in any one of Claim 1 to 3, the LED array electrically fed from this LED lighting device, and the housing | casing which contains this LED lighting device.

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