LED Light Chain Drive Work Analysis
2019年11月22日Perhaps some people know how to drive the LED light chain, which may be a popular method that most people agree with, but in fact, behind this popular method there are actually many tricks that many people don’t know. Ninghai Yuhua Company will take you from other places to better drive the LED light chain.
In mechanical and electrical systems, there is a critical relationship between power and frequency when operating at or near resonance. Sometimes resonance is a bad thing, if too much energy enters the single mode state, it may damage the system. But resonance can also be good. Resonance is typically used to regulate the frequency by keeping enough power to keep the system oscillating at resonant frequencies (eg, mechanical and electrical clocks). Many people may not know that resonance can be used to adjust power and can adjust the power to a variable size array of variable loads. For example, this can be applied to lighting arrays such as to achieve cost effectiveness and reliability of solid state lighting (SSL) systems.
LED applications are particularly interesting because LEDs are becoming more economical in lighting applications and are also cost and reliability issues due to conventional DC drives. LEDs are inherently low voltage DC devices, and the current-voltage (I-V) curve is very steep at certain operating points. Although a constant voltage source can be used to drive the LEDs, most designers actually use a constant current DC driver design. To be closer to working at typical power distribution levels (eg, 120/240 VAC), luminaires are typically equipped with many LED light chains. These LEDs must be closely matched because the light output of each LED is proportional to the current flowing through the lamp chain. Failure of a single LED (such as a short circuit or wiring fault) can result in failure of the entire light chain.
Distributed reactance component
The use of resonance to control the power of the LED array overcomes these shortcomings of AC LED drivers. In the simplest case, resonance can be used to control the power of a single load. Verdi Semiconductor has effectively utilized resonance to create a current driver that is less suitable for LED light chains and has high efficiency.
However, a more powerful approach is to distribute the reactive components between the arrays. In this way, not only can the overall power of the lighting elements be controlled, but in large networks, it is also possible to separately adjust the sub-network without adding a semiconductor device. Distributed reactive components deliver powerful new control capabilities with high efficiency and low cost. Typically, the reactive component can be a capacitor or an inductor. Between kilohertz to megahertz (or even gigahertz, if needed), suitable components are very small and inexpensive, and can be implemented as discrete devices or on-chip devices. Specifically, we assume that the capacitors are distributed throughout the network and use a smaller number of discrete inductors, but a low cost inductor design can also be fabricated.
Adding chain-connected and parallel reactive components (capacitors and/or inductors) opens up a whole new approach to power control. The reactive component can form a resonant tank, wherein the primary dissipation mechanism is the resistive load of the LED. At the same time, near-lossless reactances can replace energy-consuming resistors, which are commonly used as current regulators in the simplest DC circuits.
Unit and array
Imagine an illumination network consisting of a set of lighting units, each unit containing one or more lighting elements, such as a pair of anode-connected cathode LEDs, and chain-connected and shunt capacitors. There are many variations in the topology. Any number of such units, as well as units of the actual hybrid topology, may be connected in a chain and/or in parallel to form a resonant network of reactive chains. More generally, we refer to the network of reactive chains as the "solid state lighting reactance chain" (RSSL).
For example, an energy storage circuit consists of 10 reactive chains. Assume that all LEDs are of the same type and all capacitors have the same value C. The total capacitance of each unit is 2C. The total capacitance of the lamp chain is C/5. The resonant frequency is √(5LC). The reactance of a unit is 1/2 ωC. As long as X? R, where R is the actual resistance of the LED, then the reactance chain is expressed as pure reactance, which is equivalent to the requirement to use the resonant circuit to reduce the damping, Q? 1.
A detailed analysis of a particular resonant network can be performed using a circuit simulator, but it is also easy to make a rough estimate and roughly select the value of the component. For a given operating frequency, the relationship between inductance and capacitance is determined. The capacitor should be chosen so that the reactance is large enough to ensure a sufficiently high Q resonance. The current flowing through each cell is distributed by the LED and the shunt capacitor in parallel and is limited by the chain capacitor, which acts much like the case where a resistor is used in a DC circuit to control the current. You can find the desired value by simply using Ohm’s law for the reactance. Note that the function of the bypass capacitor is to locally store the recirculating current when current does not flow through the LED. In fact, in addition to the resonant control of the current through the entire lamp chain, there is actually a local resonance control for each LED current.
Multi-channel and line frequency suppression
Although the entire RSSL system can be operated at a single frequency using the same capacitance value, it is not necessary to do so. In fact, we can think of the two-wire lighting bus as supporting spectrum, including a lot of available channels. Since any one of the reactive chains only responds to the frequency band, as long as they have sufficient space between the frequency bands to operate, the multiple individual frequency bands can operate on the same wiring. Each center frequency can be further modulated as a data path between the sensor and the controller.
As long as the line frequency is separated from the resonant frequency used for the reactive chain, the response to the line frequency is negligible, and even if there is no explicit line frequency filtering, there is no cable frequency flicker. Therefore, electrolytic capacitors are not required in the driver.
The SSL system itself has electromagnetic quietness and is resistant to noise spikes. Any energy that goes beyond the narrow passband will quickly disappear. Cells and unit light chains can be hot swapped or switched, with no effect on other parts of the network. With this property, many luminaires can share the same high-power drive. For example, a residential or commercial space can be powered by a two-wire bus using a single drive mounted in a power strip, with LEDs and capacitors, but without active semiconductor components, dimming and switching can be done separately.
The larger the array size, the higher the reliability of RSSL
For DC drives, the use of more LEDs is often considered to pose serious reliability and lifetime issues, especially considering the sensitivity of individual components (or connections) and drive failures. This is another point that makes the RSSL system shine. The failure analysis of the RSSL shows that the overall reliability and lifetime of the system will actually increase as the size of the array increases. This is because the adjustment of the remaining components is acceptable even with 50% component failure.
In addition, most high-power LEDs show a significant drop in lumen output at the upper end of their rated current, resulting in a loss of net wattage and radiant watt conversion efficiency. The low-cost design of the RSSL system allows these devices to make lumen output less noticeable at well below their rated maximum.
In addition, cost savings and reliability improvements can be achieved through a COB architecture including multi-junction chips. Instead of building several large-area devices on a single chip, you can choose the device area, power level, and cooling strategy to achieve maximum single device efficiency, then place as many of these devices as possible on a single chip to achieve Required performance specifications. By driving the illumination array with one or more resonant chains, we have a product line that can be arbitrarily cropped to any desired lumen output.
Using resonance to control the power of the LEDs in the reactance chain is a powerful new LED driving method that can be used in any array application including illumination. This article only touches on the features and benefits of the RSSL system. Resonant drives offer a rich and powerful set of innovative design tools that can be used further to create advanced, low-cost, multi-functional lighting systems.
Ninghai Haohua Company is a manufacturer that designs and produces various types of LED Light Chain . LED light chain products are complete in specifications and beautiful in style. The goods are exported to Europe, the United States, Australia and other countries and regions. Click on our website to view more LED light chain product picture information: https://www.nhhx.net
In mechanical and electrical systems, there is a critical relationship between power and frequency when operating at or near resonance. Sometimes resonance is a bad thing, if too much energy enters the single mode state, it may damage the system. But resonance can also be good. Resonance is typically used to regulate the frequency by keeping enough power to keep the system oscillating at resonant frequencies (eg, mechanical and electrical clocks). Many people may not know that resonance can be used to adjust power and can adjust the power to a variable size array of variable loads. For example, this can be applied to lighting arrays such as to achieve cost effectiveness and reliability of solid state lighting (SSL) systems.
LED applications are particularly interesting because LEDs are becoming more economical in lighting applications and are also cost and reliability issues due to conventional DC drives. LEDs are inherently low voltage DC devices, and the current-voltage (I-V) curve is very steep at certain operating points. Although a constant voltage source can be used to drive the LEDs, most designers actually use a constant current DC driver design. To be closer to working at typical power distribution levels (eg, 120/240 VAC), luminaires are typically equipped with many LED light chains. These LEDs must be closely matched because the light output of each LED is proportional to the current flowing through the lamp chain. Failure of a single LED (such as a short circuit or wiring fault) can result in failure of the entire light chain.
Distributed reactance component
The use of resonance to control the power of the LED array overcomes these shortcomings of AC LED drivers. In the simplest case, resonance can be used to control the power of a single load. Verdi Semiconductor has effectively utilized resonance to create a current driver that is less suitable for LED light chains and has high efficiency.
However, a more powerful approach is to distribute the reactive components between the arrays. In this way, not only can the overall power of the lighting elements be controlled, but in large networks, it is also possible to separately adjust the sub-network without adding a semiconductor device. Distributed reactive components deliver powerful new control capabilities with high efficiency and low cost. Typically, the reactive component can be a capacitor or an inductor. Between kilohertz to megahertz (or even gigahertz, if needed), suitable components are very small and inexpensive, and can be implemented as discrete devices or on-chip devices. Specifically, we assume that the capacitors are distributed throughout the network and use a smaller number of discrete inductors, but a low cost inductor design can also be fabricated.
Adding chain-connected and parallel reactive components (capacitors and/or inductors) opens up a whole new approach to power control. The reactive component can form a resonant tank, wherein the primary dissipation mechanism is the resistive load of the LED. At the same time, near-lossless reactances can replace energy-consuming resistors, which are commonly used as current regulators in the simplest DC circuits.
Unit and array
Imagine an illumination network consisting of a set of lighting units, each unit containing one or more lighting elements, such as a pair of anode-connected cathode LEDs, and chain-connected and shunt capacitors. There are many variations in the topology. Any number of such units, as well as units of the actual hybrid topology, may be connected in a chain and/or in parallel to form a resonant network of reactive chains. More generally, we refer to the network of reactive chains as the "solid state lighting reactance chain" (RSSL).
For example, an energy storage circuit consists of 10 reactive chains. Assume that all LEDs are of the same type and all capacitors have the same value C. The total capacitance of each unit is 2C. The total capacitance of the lamp chain is C/5. The resonant frequency is √(5LC). The reactance of a unit is 1/2 ωC. As long as X? R, where R is the actual resistance of the LED, then the reactance chain is expressed as pure reactance, which is equivalent to the requirement to use the resonant circuit to reduce the damping, Q? 1.
A detailed analysis of a particular resonant network can be performed using a circuit simulator, but it is also easy to make a rough estimate and roughly select the value of the component. For a given operating frequency, the relationship between inductance and capacitance is determined. The capacitor should be chosen so that the reactance is large enough to ensure a sufficiently high Q resonance. The current flowing through each cell is distributed by the LED and the shunt capacitor in parallel and is limited by the chain capacitor, which acts much like the case where a resistor is used in a DC circuit to control the current. You can find the desired value by simply using Ohm’s law for the reactance. Note that the function of the bypass capacitor is to locally store the recirculating current when current does not flow through the LED. In fact, in addition to the resonant control of the current through the entire lamp chain, there is actually a local resonance control for each LED current.
Multi-channel and line frequency suppression
Although the entire RSSL system can be operated at a single frequency using the same capacitance value, it is not necessary to do so. In fact, we can think of the two-wire lighting bus as supporting spectrum, including a lot of available channels. Since any one of the reactive chains only responds to the frequency band, as long as they have sufficient space between the frequency bands to operate, the multiple individual frequency bands can operate on the same wiring. Each center frequency can be further modulated as a data path between the sensor and the controller.
As long as the line frequency is separated from the resonant frequency used for the reactive chain, the response to the line frequency is negligible, and even if there is no explicit line frequency filtering, there is no cable frequency flicker. Therefore, electrolytic capacitors are not required in the driver.
The SSL system itself has electromagnetic quietness and is resistant to noise spikes. Any energy that goes beyond the narrow passband will quickly disappear. Cells and unit light chains can be hot swapped or switched, with no effect on other parts of the network. With this property, many luminaires can share the same high-power drive. For example, a residential or commercial space can be powered by a two-wire bus using a single drive mounted in a power strip, with LEDs and capacitors, but without active semiconductor components, dimming and switching can be done separately.
The larger the array size, the higher the reliability of RSSL
For DC drives, the use of more LEDs is often considered to pose serious reliability and lifetime issues, especially considering the sensitivity of individual components (or connections) and drive failures. This is another point that makes the RSSL system shine. The failure analysis of the RSSL shows that the overall reliability and lifetime of the system will actually increase as the size of the array increases. This is because the adjustment of the remaining components is acceptable even with 50% component failure.
In addition, most high-power LEDs show a significant drop in lumen output at the upper end of their rated current, resulting in a loss of net wattage and radiant watt conversion efficiency. The low-cost design of the RSSL system allows these devices to make lumen output less noticeable at well below their rated maximum.
In addition, cost savings and reliability improvements can be achieved through a COB architecture including multi-junction chips. Instead of building several large-area devices on a single chip, you can choose the device area, power level, and cooling strategy to achieve maximum single device efficiency, then place as many of these devices as possible on a single chip to achieve Required performance specifications. By driving the illumination array with one or more resonant chains, we have a product line that can be arbitrarily cropped to any desired lumen output.
Using resonance to control the power of the LEDs in the reactance chain is a powerful new LED driving method that can be used in any array application including illumination. This article only touches on the features and benefits of the RSSL system. Resonant drives offer a rich and powerful set of innovative design tools that can be used further to create advanced, low-cost, multi-functional lighting systems.
Ninghai Haohua Company is a manufacturer that designs and produces various types of LED Light Chain . LED light chain products are complete in specifications and beautiful in style. The goods are exported to Europe, the United States, Australia and other countries and regions. Click on our website to view more LED light chain product picture information: https://www.nhhx.net
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