KR101210761B1 - LED Drive Circuit for AC Power - Google Patents

Abstract

According to the present invention, it is useful for the control of lighting devices made of LEDs directly driven by AC power, and particularly has high power factor and low Total Harmonic Distortion (THD) characteristics. It has the advantage of increasing the size, reducing the size of the lighting device and applying a low voltage has the advantage of lowering the unit cost of applying a process for manufacturing a general IC, not a high-voltage semiconductor process.

Description

Light Emitting Diode Drive Circuit for AC Power {LED Drive Circuit for AC Power}

It is related to the driving circuit necessary to drive LED with AC power. It is realized in the form of integrated circuit by integrating electric, electronic, lighting control technology and especially semiconductor technology.

In general, the lighting LED is driven by a DC power source, but recently, there have been many examples of driving a commercial AC power (hereinafter, AC power).

This is a circuit that converts from a commonly used AC power source to a DC power source and a constant current source for driving an LED, which is inefficient and has a complicated circuit.

Recently, many circuits for driving LEDs with AC power have been developed. Especially, circuits for driving AC power through bridge diodes and connecting a plurality of LEDs are used. These circuits have many LEDs connected in series. To solve the various problems such as not turning on the low voltage of AC power before reaching the voltage to turn them on, power factor by using AC power, distortion caused by discontinuous flow of current, and so on. Accordingly, technologies have been developed in which some LED array modules are selectively driven to drive some or all of them.

In spite of the improvement of technology, the remaining problem is to control in a uniform order without considering the lifespan of using multiple LED modules, causing failure due to deterioration of LED modules that are vulnerable to some lifespan, or driving multiple LEDs. Because of the high voltage that can directly control the AC power supply, the driver IC must be made using a semiconductor process with high breakdown voltage.

In the lighting device that uses several LED modules, the overall life is dictated by the limited lifetime of the LED modules, and the lifespan is reduced due to the failure due to deterioration. In the case of the control circuit by AC commercial power, high breakdown voltage design is required. The goal is to reduce the burden of applying a high cost semiconductor production process.

This LED driver IC circuit is connected to one LED module in parallel to recognize the temperature of the LEDs to maximize the life of adjacent LED modules, to allow several LED modules to operate evenly, and to control only one LED module. As a structure, the driving circuit can be made of semiconductor technology with a low reverse breakdown voltage process, so that an economical advantage can be obtained.

According to the LED driving circuit for AC power according to the present invention, since the control of the plurality of LEDs are connected in series to drive the AC drive LED modules in the temperature order can maximize the life of each LED module and parallel to only one LED module As it is a structure that is connected, it is divided voltage in the whole series connection and the driving voltage is low. Therefore, when IC is integrated circuit, it can be manufactured by low voltage process, which has economic advantages. THD; Total Harmonic Distortion)

Block diagram of the configuration of the present invention connected in parallel to the LED module Application example of a circuit consisting of several LED modules in series

As shown in FIG. 1, the LED module consisting of a plurality of LED elements (10) is composed of a LED driving circuit of the structure connected in parallel, respectively, the power circuit (2) power smoothing capacitor (1) temperature resistance conversion element (3) inside And a plurality of analog comparators (4a, 4b, 4c) in which the external voltages of the plurality of voltage dividers (5a, 5b, 5c) are compared with voltages across the temperature resistance element (3) and the plurality of voltage dividers (5a, 5b, 5c). Switch to select the Priority RS Latch (6) that selectively operates the Falling Set signal and Rising Reset control signal from these outputs, and the Forward Voltage Reference (9) that provides this output and constant voltage reference (7). And MOSFET controlling power by switch output (8)

And it is made of a circuit or one integrated circuit IC composed of a Zero Crossing detector (11) that initializes Priority Latch (6) by detecting that the external AC power is 0 Volt.

As shown in FIG. 2, the above-described LED driving circuit or IC (13a, 13b, 13c) is connected in parallel to a position adjacent to the plurality of LED modules 14a, 14b, and 14c, and the parallel connections are connected in series. LED modules 14a, 14b, and 14c are connected to each other through a bridge diode (12) from an AC power source (15).

In more detail in FIG. 1, the voltage divided by the capacitance and the divided resistors 5a, 5b, and 5c changed into a resistance value by the temperature of the adjacent LED module 10 by the internal temperature resistance conversion element 3. In the comparator 4a, if a voltage over a certain voltage is detected in the comparator 4a, the LED module is deteriorated and disconnected at any part of the series connection. The voltage of (9) is applied to the MOSFET (8) so that the current flows as much as the forward voltage drop of the normal LED module 10 to the external terminal, so that some LED modules

(14a, 14b, 14c) Other LED modules can be turned on even when they are disconnected.

When the AC power supply (15) detects the zero crossing time point of the wave rectified by the bridge diode 12 is 0V by the zero crossing detection unit (11), it passes through the MOSFET (6) through the priority RS latch and the switch (7). 8) Initial operation to be On

From a later point of view, the comparators (4a, 4b, 4c) do not operate because the divided voltages applied to the LED modules (14a, 14b, 14c) are low because the voltage before the predetermined time is low. ) Will remain On.

After a certain time, when the external inlet voltage becomes high, one of the comparators (4c) of the circuit adjacent to the low temperature LED module is activated first by the temperature resistance conversion element 3 and the voltage divider resistors 5a, 5b, and 5c. The output generated by the Priority RS Latch (6) operated by the rising edge of the output turns the MOSFET (8) off through the switch (6). In this case, the LED modules connected in parallel (10) are driven. The voltage applied to the module 10 is increased to the forward operating voltage of the LED module 10 at a low voltage when the MOSFET inside the LED driver ICs 13a, 13b, and 13c is turned on (8), and thus the other The voltage applied to the LED module 10 is lowered so that the comparator does not operate for a considerable time.

After a certain period of time, when the AC voltage of the AC power source becomes high, the driving circuit connected in parallel to the LED module of low temperature among other LED driver ICs other than the LED driver IC driven first, the IC operates to operate the corresponding LED module. It will turn on.

As the AC voltage of the AC power is increased in this way, the LED module is sequentially turned on from the LED module having a low temperature, and thus the LED is turned on.

After the AC voltage is lowered past the peak, the operation is reversed as described above. As the external AC power supply voltage decreases, the voltage generated by the temperature resistance conversion element and the voltage divider resistors (5a, 5b, 5c) The rising edge input of Priority RS Latch of adjacent LED driving circuit with high temperature of LED module 10 is generated by the comparator 4b comparing the input voltage, and the changed Priority RS Latch (6) output turns on the switch (7). After turning the MOSFET (8) on, the current flowing to the LED module (10) flows through the MOSFET (8). At this time, the forward voltage applied to the LED module (10)

When the MOSFET is turned on, it is changed to a low parallel voltage. In this case, the voltage applied to the other LED modules is made higher and maintained for a certain time.

After a certain period of time, the AC voltage is lowered again. (10) Adjacent drive circuit of the specific LED module with high temperature of LED module (10) In case of IC, internal MOSFET (8) Turn On Repeat the operation.

Eventually, all the MOSFETs (8) of the driving circuit and IC are turned on and all the LED modules

(10) It turns off and when the voltage of AC power supply (15) becomes 0 Volt, it repeats from the operation by Zero Crossing at the beginning.

Claims (7)

An AC driven LED lighting driving circuit comprising: One or more LEDs are connected in parallel to the LED modules connected in series or in parallel; A semiconductor power switching element therein; A detector for detecting a current flowing through the LED module or an applied voltage; A comparison determination unit determining whether a voltage or a current is greater than or equal to a predetermined value that enables the driving of the LED module or less than or equal to a predetermined value not suitable for driving the LED based on the value recognized by the detection unit; As a result of the comparison determination of the comparison determination unit, when the value of the sensor unit is greater than or equal to a predetermined value, the switching element is turned off so that current flows to the external LED module. When the switching element is off, when the comparison determination is less than the predetermined value, the switching element is A control unit for selectively turning on and off the LED module by adjusting the current flowing in the LED module to bypass the switching element; A temperature sensor for detecting a temperature of the LED module; If the temperature of the LED module is higher than the temperature of the other LED module, the On point of the controller is slower and the Off point is pulled more. On the contrary, if the temperature of the LED module is lower than the other modules, the On point of the controller is pulled further. The off point uses the output value of the temperature sensor as an input for adjusting the criterion of the comparison determination unit to be further delayed; As a result of the action of the temperature sensor and the comparison determination unit, as a result, the operation temperature of the high temperature LED module is reduced, and the low temperature LED module increases the on period so that each LED module generates heat evenly. Type LED lighting driving circuit
AC driving type LED lighting driving circuit characterized in that when the voltage applied in claim 1 is less than another specific value, it is recognized as a turn on time or zero crossing time of AC power and initialized by switching on.
AC driving type LED lighting driving circuit using a backflow prevention diode and a smoothing capacitor voltage stabilization circuit in order to utilize the voltage across the LED module, which is introduced when the switching element is turned off, as driving power of the controller and the detector.
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