JP2017079501A - LED lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED lighting device capable of achieving downsizing and high efficiency.SOLUTION: There is provided an LED lighting device which is equipped with a step-up type switching power supply. In the switching power supply, a plurality of inductors around which winding is wound in several layers are arranged. Using one of the plurality of inductors as a reference, each inductor has the number of layers which is determined on the basis of a correlation between the diameter of winding and the number of windings so that a coil loss Rac/Rdc becomes equal to or less than 3 within a range where switching frequency characteristics of the switching power supply are 38 kHz or more and 200 kHz or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an LED illumination device using an LED element as an illumination light source.

  2. Description of the Related Art Conventionally, LED illumination devices that use LED elements as illumination light sources are already known that include a power supply device for supplying power to the LED elements.

  At this time, the external power is supplied to the LED element via a step-up switching power supply.

  In addition, such a step-up switching power supply is known in which a plurality of coils constituting an inductor are directly arranged (see, for example, Patent Document 1).

JP 2009-050102 A

  However, in such a step-up type switching power supply in the LED lighting device, the efficiency of the inductor is inevitably increased with an increase in luminance, for example, while the entire arrangement space of the switching power supply is limited. Therefore, miniaturization and high efficiency are desired.

  In order to solve the above-described problems, an object of the present invention is to provide an LED lighting device that can be reduced in size and increased in efficiency.

  In order to achieve the above object, an LED lighting device according to the present invention is an LED lighting device including a step-up switching power supply, and the switching power supply includes a plurality of inductors each having a winding wound in several layers. In addition, on the basis of one of the plurality of inductors, each inductor has a winding diameter such that the coil loss Rac / Rdc is 3 or less when the switching frequency characteristic of the switching power supply is in the range of 38 kHz to 200 kHz. And the number of layers determined based on the correlation between the number of turns and the number of turns.

  According to the present invention, downsizing and high efficiency can be realized.

It is a block diagram of the principal part in the LED lighting apparatus which concerns on one Embodiment of this invention. It is sectional drawing of an inductor. It is a graph which shows the relationship between the switching frequency with respect to the number of winding layers in an inductor applied to the LED lighting apparatus which concerns on one embodiment of this invention, and alternating current resistance. The coil loss Rac / Rdc in the inductor applied to the LED lighting device according to the embodiment of the present invention is a graph showing the relationship with the switching frequency when the coil loss Rac / Rdc is 1 at 10 kHz. is there.

  Next, an embodiment according to the present invention will be described with reference to the drawings.

  Next, an LED lighting device according to an embodiment of the present invention will be described with reference to the drawings. In addition, although embodiment shown below is a suitable specific example in the LED illuminating device of this invention, and may have attached various technically preferable restrictions, the technical scope of this invention is especially this invention. Unless otherwise specified, the present invention is not limited to these embodiments. In addition, the constituent elements in the embodiment described below can be appropriately replaced with existing constituent elements, and various variations including combinations with other existing constituent elements are possible. Therefore, the description of the embodiment described below does not limit the contents of the invention described in the claims.

  As shown in FIG. 1, an LED lighting device 1 according to an embodiment of the present invention uses one or more LED elements as a light source for illumination, and includes a commercial power source 2, a load unit 3 including the LED elements, And a switching power supply 10 that controls the voltage and current of the power supply 2 to supply power to the load unit 3. The switching power supply 10 includes only a step-up type without including a step-down type. The LED element is lit.

  The LED lighting device 1 is not limited to a tube type (straight tube type) or a light bulb type, and is particularly applicable to the LED lighting device 1 that lights a large number of 100 or more LED elements. Further, a plurality of LED elements are arranged on at least one circuit board electrically connected to the switching power supply 10.

  A switching power supply 10 as a power supply circuit includes a first noise filter unit 11, a rectifier circuit unit 12 including a full-wave rectifier B1 composed of a diode bridge, a second noise filter unit 13, a boost switch power supply circuit unit 14, and an IC power supply. Power supply control circuit unit 15, switching power supply control unit 16, input low voltage protection circuit unit 17, and protection circuit unit 18.

  In addition, the power supply control circuit unit 15 includes a first IC power supply control circuit unit 15A serving as a first power supply for startup and a second IC power supply control circuit unit 15B serving as a second power supply for steady operation. The protection circuit unit 18 is arranged between the switching power supply 10 and the load unit 3, specifically, on the output side of the step-up switch power supply circuit unit 14 so as to regulate the output power to the load unit 3. The overvoltage protection circuit unit 18A, the inrush current protection circuit unit 18B, and the overinput protection circuit unit 18C are provided.

  Next, an embodiment of the switching power supply 10 in the LED lighting device of the present invention will be described in detail.

  Between the commercial power source 2 and the first noise filter unit 11, a current fuse F1 and a surge voltage protection element ZNR1 are connected.

  The first noise filter unit 11 mainly functions as a noise filter for removing common mode noise. For example, a filter capacitor (not shown) in parallel with the surge voltage protection element ZNR1 and an input terminal of the full-wave rectifier B1 And one or more line filters (not shown) arranged in parallel between the positive electrode and the negative electrode. In the present embodiment, the first noise filter unit 11 arranges a damping resistor in parallel with the common mode choke coil as a line filter and is connected to each input / output end of the common mode choke coil. Thereby, the first noise filter unit 11 mainly reduces common noise components in the input stage of the rectifier circuit unit 12. The output terminal of the line filter is connected to the input terminal of the rectifier circuit unit 12.

  The output terminal of the full-wave rectifier B1 of the rectifier circuit unit 12 is connected in parallel with a high-frequency bypass capacitor C1. The negative terminal of the output terminal of the full-wave rectifier B1 is the ground of the circuit board and is grounded via the capacitor C1.

  The second noise filter unit 13 includes, for example, two or more line filters (not shown) arranged in parallel between the positive electrode and the negative electrode of the output terminal of the full-wave rectifier B1, and the output side of the line filter. And two or more line filters (not shown) connected in series to the positive electrode of the output terminal of the full-wave rectifier B1. Thereby, the second noise filter unit 13 reduces the common noise component and the normal noise component in the output stage of the rectifier circuit unit 12.

  Two or more line filters arranged in parallel on the input side of the second noise filter unit 13 function as a noise filter for removing common mode noise in the output stage of the rectifier circuit unit 12. In the line filter arranged in parallel, a damping resistor is arranged in parallel with each of the positive and negative common mode choke coils of the output terminal of the full-wave rectifier B1, and the input / output terminals of the common mode choke coils are also arranged. Connected to each.

  Two or more line filters arranged in series on the output side of the second noise filter unit 13 function as noise filters for removing normal mode noise in the output stage of the rectifier circuit unit 12. In this line filter arranged in series, a damping resistor is arranged in parallel with each normal mode choke coil of the positive terminal of the output terminal of the full-wave rectifier B1, and at each input / output end of each normal mode choke coil. Connected.

  The step-up switch power supply circuit unit 14 includes one or more transformers (inductors) T1, T2, T3 connected to the positive terminal of the output terminal of the full-wave rectifier B1 on the primary side, and switching elements connected to the primary side of the transformer T1 ( N-channel MOSFET) Q1, a controller U1 of the switching element Q1, a diode D1 anode-connected between the primary side of the transformer T1 and the drain of the switching element Q1, and a capacitor C2 cathode-connected to the diode D1 Yes. Transformers (inductors) T1, T2, T3 are arranged in series along the input direction. In the following description, the transformer (inductor) is simply referred to as “transformer”. Therefore, the inductance is also referred to as “transformer”. In addition, since the transformers T1, T2, and T3 basically have the same configuration, unless specifically limited, the transformers T1, T1, or generically referred to as the transformer T are used.

  As shown in FIG. 2, the transformer T <b> 1 is, for example, a core 20 in which windings 21 are stacked in several layers. Insulating tape is wound between the primary side winding and the secondary side winding and on the outside. For example, the inner side shown in FIG. 2 may be a secondary side winding and the outer side may be a primary side winding, or vice versa. The transformers T1 to T3 are set so that the ambient temperature including the controller U1 is 40 ° C. or lower when the input power is rated lighting (for example, 100 V). Specifically, in order to suppress heat generation, the diameter of the winding 21 and the number of winding layers are set so that the current value at the output end of the transformers T1 to T3 becomes a predetermined current value. At this time, the diameter and the number of winding layers of the winding 21 are set to be equal to or less than values calculated based on a predetermined current value at the output end of the transformer T1. For example, the winding diameter of the coil is in the range of 0.14 mm to 0.26 mm, and the number of winding layers is in the range of 4 to 7 layers. Here, the number of winding layers means the number of overlapping windings 21 from the inner side in the radial direction of the core 20 to the outer side, and the number of turns of the coil means the number in the direction along the axial direction of the core 20. The transformers T1 to T3 are driven at a switching frequency at which the ratio of the DC resistance to the AC resistance is 3 or less with one of them (for example, the transformer T1) as a reference.

  Thus, assuming that the switching power is the same between the step-up converter and the step-down converter, the step-up type generates a voltage higher than that of the step-down type. Therefore, the switching current noise generated by switching of the switching power supply 10 is reduced. It can be made lower than the converter.

  As shown in FIG. 3, in this embodiment, the switching frequency is 40 kHz or less, and the AC resistance component Rac is constant with respect to the change of the switching frequency when the winding 21 is 4 layers or less. When the AC resistance component Rac is about 8Ω. When the number of winding layers is less than 4, the AC resistance component Rac increases. When the DC resistance component Rdc is constant, the coil loss Rac / Rdc increases and the power supply efficiency deteriorates.

  FIG. 4 shows the relationship between the coil loss Rac / Rdc and the switching frequency when the coil loss Rac / Rdc is 1 at 10 kHz. The coil loss Rac / Rdc increases in proportion to the 1.6th power of the frequency, and when the coil loss Rac / Rdc increases, the transformer temperature rises and the conversion efficiency decreases. Therefore, the coil loss as much as possible within a predetermined switching frequency range. Rac / Rdc is preferably low and constant. As shown in FIG. 4, even when the switching frequency is changed within the range of 40 kHz or less, the change of the coil loss Rac / Rdc is small and substantially constant when there are four layers, and the number of layers is more than that. As the AC resistance component Rac increases, the coil loss Rac / Rdc increases as the switching frequency increases.

  From the above, the optimum number of winding layers is four, the AC resistance Rac at that time is 8Ω, and the coil loss Rac / Rdc is substantially constant. Normally, the coil loss Rac / Rdc tends to increase exponentially as the switching frequency increases beyond a certain frequency range. When the number of winding layers is 4, when the switching frequency becomes 80 kHz or more, the coil loss Rac / Rdc tends to gradually increase. Assuming that the coil loss Rac / Rdc is up to 2, the switching frequency at that time is about 200 kHz. Therefore, the upper limit value of the switching frequency when using the transformers T1 to T3 is set to 200 kHz.

  As described above, the transformer T1 of the present embodiment has a switching frequency of 40 kHz or more and 200 kHz or less in consideration of the frequency characteristic of the self-inductance with the carrier frequency of the infrared remote controller being 38 kHz with reference to one transformer T1. By arranging the number of layers determined based on the correlation between the diameter of the winding 21 and the number of turns at the frequency, each parameter is simulated so as to reduce the loss (iron loss + copper loss) as much as possible. By deriving, the transformer T1 can be reduced in size and increased in efficiency.

  The controller U1 inputs the pin ZCD, the pin VDD connected to the output terminal of the switching power supply control unit 16, the pin DRV connected to the gate of the switching element Q1, the grounded pin GND, and the feedback signal of the protection circuit unit 18 And an integrated circuit having a pin CS.

  The controller U1 starts to operate when VDD reaches a starting voltage (for example, 12V). The controller U1 controls the switching element Q1 through the pin DRV. The controller U1 generates a control signal in the first state to the switching element Q1 through the pin DRV to turn on the switching element Q1, and sends a control signal in the second state to the switching element Q1 through the pin DRV. Occurs to turn off the switching element Q1.

  The pin ZCD is a terminal for detecting the turn-on timing of the controller U1, and the secondary winding detects that energy is released from the primary winding of the transformer T1. The controller U1 receives a detection signal at the pin ZCD via the secondary winding, whether the electrical state of the transformer T1, for example, whether the current flowing through the transformer T1 is at a predetermined current level. Furthermore, the controller U1 generates a control signal in the first state to the switching element Q1 through the pin DRV based on the received detection signal, and attempts to turn on the switching element Q1.

  The pin DRV is a drive terminal of the controller U1 and is connected to the gate of the switching element Q1 so that the switching element Q1 can be quickly switched.

  The pin CS is a terminal for detecting a current flowing through the light source 3 and performing feedback control by the controller U1. The pin CS is also connected to the voltage protection circuit 18A and the over-input protection circuit unit 18C. When an abnormal voltage is detected, the base current from the pin DRV of the controller U1 to the switching element Q1 is stopped, and the boost switch The power supply circuit unit 14 is stopped.

  On the other hand, since the current detected at the pin CS does not have to be abundant, the amount of current is limited by the detection resistor R1 to reduce power consumption. The detection resistor R1 functions as a pseudo detection value generation unit that generates a pseudo detection value.

  The first IC power supply control circuit unit 15A connects the input to the output side of the capacitor C1 at the positive electrode of the output terminal of the full-wave rectifier B1, that is, the primary side of the transformer T, and connects the output to the input end of the switching power supply control unit 16 doing. The first IC power supply control circuit unit 15A is disconnected after a predetermined time has elapsed after being activated, and functions as a first power supply for activation.

  Immediately after the start-up, which is immediately after power-on, since no alternating current has yet occurred in the transformer T, power is not supplied to the second IC power supply control circuit unit 15B, and the first IC power supply control circuit unit 15A is started first. To do. When the first IC power supply control circuit unit 15A starts operation, power is supplied to the controller U1 via the switching power supply control unit 16.

  When the controller U1 receives the output current of the input low voltage protection circuit unit 17 to the pin CS by this power supply and determines that the current value is safe inside the controller U1, the controller U1 sends a switching control signal from the DRV to the switching element. The switching element Q1 performs a switching operation and starts a boosting operation.

  When the step-up operation is started, an AC voltage is applied to the primary side of the transformer T, an AC voltage is generated on the secondary side, and the voltage extracted from the intermediate tap becomes the supply power of the first IC power supply control circuit unit 15A. The circuit unit 15A constantly supplies power to the controller U1. When the operation of the first IC power supply control circuit unit 15A starts, no current flows through the first IC power supply control circuit unit 15A, so the first IC power supply control circuit unit 15A stops operating.

  The second IC power supply control circuit unit 15 </ b> B has an input connected to the secondary side of the transformer T <b> 1 and an output connected to the input terminal of the input low voltage protection circuit unit 17. The second IC power supply control circuit unit 15B functions as a second power supply for steady operation that is driven at the same time as the operation of the first IC power supply control circuit unit 15A stops.

  The input low voltage protection circuit unit 17 has a possibility that the current increases and other circuits may be damaged when the input voltage becomes lower than the specified value. The current is controlled so as not to flow out of the input low voltage protection circuit unit 17 when the value is less than.

  The overvoltage protection circuit unit 18A connects the input between the diode D1 and the capacitor C2, and connects the pin CS and the output of the controller U1 on the input side of the detection resistor R1.

  The overvoltage protection circuit unit 18A protects the output voltage from exceeding the withstand voltage of the load unit 3 for some reason. When the overvoltage protection circuit unit 18A operates, the controller U1 stops the output by the feedback signal. In this case, it returns when the power is turned on again.

  The inrush current protection circuit unit 18B is disposed between the step-up switching power supply 10 and the load unit 3 and further on the output side of the capacitor C2, and suppresses an inrush current of power supplied to the load unit 3. The inrush current is an excessive initial current that flows until the filter (smoothing) electrolytic capacitor C2 having a relatively large capacitance value is charged immediately after the power switch is turned on. If this initial current is too large, the LED element as a load may be destroyed.

  Therefore, in the present embodiment, the inrush current protection circuit unit 18B connects the input on the output side of the capacitor C2, and connects the pin CS and the output of the controller U1 on the input side of the detection resistor R1. The inrush current protection circuit unit 18B has a capacitor C3 arranged in parallel with the capacitor C2 on the output side of the capacitor C2. Further, the inrush current protection circuit unit 18B has a thermistor RT1 and a switching element (N-channel MOSFET) Q2 arranged in parallel on the output side of the capacitors C2 and C3.

  The gate of the switching element Q2 is connected to the starting power supply via a bypass capacitor C4, one or more resistors (not shown), and the like. The drain of the switching element Q2 is connected to the output side of the capacitor C3, and the input terminal of the thermistor RT1 is connected to the output terminal of the capacitor C2. The source of the switching element Q2 and the output terminal of the thermistor RT1 are grounded in a connected state.

  Thereby, the capacitor C3 and the switching element Q2 can be arranged in series at close positions. Accordingly, the capacitor C3 is one or more connected in series with the switching element Q2 and the input side in the vicinity of the switching element Q2, apart from the capacitor C2 arranged on the input side of the switching element Q2. Functions as an input side capacitor.

  Therefore, the capacitor C2 has a function to prevent flickering of the load unit 3 with respect to the LED light source in addition to the function as the step-up switch power supply circuit unit 14, and the capacitor C3 functions to prevent inrush current.

  In other words, in the present embodiment, a plurality of capacitors C2 and C3 arranged in parallel at the input end of the load unit 3 cooperate to actually function as one for filtering and flicker prevention and the other as the other. They are divided so as to function for preventing inrush current from the commercial power source 2. For power saving, an aluminum electrolytic capacitor having a dielectric loss tangent (tan δ) of 3% or less (frequency 20 kHz to 200 kHz) is used as the capacitor C2.

  A multilayer ceramic capacitor is used as the output-side bypass capacitor C4. In the present embodiment, the bypass capacitor C4 has a smaller capacity and is smaller than the capacitors C2 and C3 on the input side set for the voltage to be supplied to the load unit 3 according to the number of LED elements arranged. Further, the bypass capacitor C4 can absorb noise generated unexpectedly in the switching power supply circuit and can be lit stably.

  Although the electrolytic capacitor (for example, capacitor C2) used in the power supply circuit of the LED lighting device 1 is hardly deteriorated in an environment where the ambient temperature is 40 ° C. or lower, there is a high possibility that the electrolytic capacitor is deteriorated when the ambient temperature is increased.

  Therefore, in the case of the straight tube / series LED lighting device 1 adopting the arrangement structure in which the LED element and the power supply circuit are close to each other in the same housing, the ambient temperature of the capacitor C2 is likely to deteriorate as low as possible. Become.

  If an electrolytic capacitor having low heat resistance is used and the ambient temperature of the electrolytic capacitor is 70 ° C., the capacitor capacity is said to drop by 10% in about one year. In general, for an electrolytic capacitor, the time during which the capacitance is reduced to 50% is set as the lifetime. Therefore, in the power supply integrated LED lighting device 1, the life of the electrolytic capacitor is directly connected to the life of the LED lighting device 1.

  Therefore, in the present embodiment, as described above, not only the heat generation of the capacitor itself is suppressed, but also the heat generation of the transformer T1, which is a heat generating component, is suppressed to an ambient temperature of 40 ° C. or lower.

  Thereby, the ambient temperature of the capacitor C2, the capacitor C3, and the bypass capacitor C4 can be suppressed to 40 ° C. or less, and the lifetime of the capacitor, that is, the lifetime of the LED lighting device 1 is secured.

  The over-input protection circuit unit 18C prevents the light source 3 and the switching power source 10 from being damaged due to the input power being lower than the specified power and the current larger than the specified value flowing from the constant current circuit. Can do.

  On the other hand, when the power is turned on, an inrush current of a load several times to several tens of times the rated current may occur. Accordingly, the over-input protection circuit unit 18C is provided on the output side of the load unit 3 to ensure a capacity that allows a sufficient starting current to flow, and also has a drooping characteristic in which the over-current protection point is greater than or equal to the starting current. The start-up characteristic in the step-up type switch power supply circuit unit 14 including the slidable current does not cross the drooping characteristic of overcurrent protection.

  Further, the over-input protection circuit unit 18C protects the switching power supply 10 when the light source is short-circuited for some reason, that is, when a current more than expected flows through the load unit 3.

  Therefore, the over-input protection circuit unit 18C is connected to the input on the output side of the load unit 3, and is connected to the pin CS of the controller U1 via the detection resistor R1. Further, the output of the over-input protection circuit unit 18C is connected to the ground side of the load unit 3. At this node, a resistor R2 and a capacitor C5 are connected in parallel as a peak suppression unit that suppresses the effective value obtained by converting the peak value of an AC waveform component (for example, a 2A rectangular wave) into a DC waveform component. Yes.

  In the switching power supply 10 according to the present embodiment, it is possible to save power because the circuit can be simplified by including only the step-up type without including the step-down type.

  As described above, in the LED lighting device 1 of the present invention, the switching power supply 10 includes the inductor T (transformers T1 to T3) and uses one inductor (for example, the transformer T1) constituting the switching power supply 10 as a reference. Thus, the number of winding layers determined based on the correlation between the diameter of the winding 21 and the number of turns at a frequency of 38 kHz or higher is arranged.

  Thereby, the LED lighting device 1 has an effect that it can be reduced in size and increase in efficiency, and can be applied to all LED lighting devices using a step-up type switching power supply.

DESCRIPTION OF SYMBOLS 1 LED lighting apparatus 2 Commercial power supply 3 Load part (LED element)
10 Switching power supply (power supply circuit)
T transformer (inductor)

Claims (3)

An LED lighting device including a step-up switching power supply,
The switching power supply is
A plurality of inductors in which windings are wound in several layers are arranged, and each inductor has a coil loss in a range where the switching frequency characteristic of the switching power supply is 38 kHz or more and 200 kHz or less with reference to one of the plurality of inductors. The number of layers is determined based on the correlation between the diameter of the winding and the number of turns so that Rac / Rdc is 3 or less.
LED lighting device. The plurality of inductors are:
The LED lighting device according to claim 1, wherein the LED lighting device is arranged in series along an input direction.     3. The LED illumination device according to claim 1, wherein the plurality of inductors have an AC resistance of 8Ω or less in a range where a switching frequency characteristic of a switching power supply is 40 kHz or less.