Size Control Of Active-current Ripple Compensation LED Driver

Lighting energy consumption accounts for 20% of global energy consumption,therefore using new types of lighting can achieve power saving, reduce carbon dioxide emissions. The use of LED lighting provides a new way of energy saving and emission reduction.As a solid-state light source,LED lighting reuqire low-voltage DC to drive.Light quality as well as the normal service life of LED lighting depend on the stability of power driving.In the power driving,the output current contains AD component because of the effect of the charge and discharge components which the current ripple appears in the circuit.Due to the current ripple,the current which flows in power driving fluctuations.The flowing ripple can influence the luminescence of LED lighting,because of non-constant DC driving.The filter capacitor can absorb and filter the ripple in the circuit,it can stable output of power driving.But the electrolyte in the filter capacitor can influence filtering effect.With the extension of life cycle,the current which flows the whole circuit converts into heat energy.The loss of electroyte speeds up because of the higher temperture,reduces the filtering ability and the liftime of filter capacitor.In order to ensure the time of LED lighting,we need a new circuit topology to replace the fliter capacitor,so we can have a long time of using LED lighting and energy saving.To solve the problems,we design a new circuit using transistor and operational amplifier.The new circuit can export a waveform that have the same magnitude and the opposite phase compared with the ripple.The new circuit achieve DC current power drving.(1)Depending on the electrical,optical and thermal characteristics of LED lighting,we should choose a reasonalbe driving after analying and comparativing different of some driving mode.The new driving keep the DC current and ensure the LED lighting stable.(2)Analysis in the case of continuous inductance current, principle of the Buck converter,and introduced state-space modeling method for small signals.We use the method to establish the AD small-signal model of Buck converter,to solve the transfer functions of the circuit.In feedback sessions,advantages and disadvantages of current and voltage feedback is analyzed,according to the LED current-voltage characteristics,current feedback is more suitable for driving LED lighting.Simultaneous analysis of electrolytic capacitors in the power supply works and influence factors of electrolytic capacitors work hours.(3)Under the model of the feedback of current,we can choose the simple structure of the peak current control.But because of the loop of voltage in the peak current control and the negative temperature of LED,it case the LED to overheat and reducing the using timeof LED lighing.So we use the loop of output current instead of the voltage loop in the original system.In order to control average current and peak current,we put a intergral link in the loop of the inductor peak current.Awareness of the power of current modulation capabilities,built the circuit in the CPM of small signal model and corresponding transfer function,improved peak-current control transfer function block diagram.(4)The new circuit structure is proposed to compensate the ripple system.Implementation of the inductance of the sample and the amount of ripple compensation,combined with three port device model in the circuit,established the active ripple compensation circuit transfer function diagram,analyzes the when the input and reference were disturbed by PNP type triode and integral,constant output current is unchanged.(5)Using electronic Simulation Software Multisim 10 on the current square control active ripple compensation type LED driver simulation experiment and comparative analysis of inductance waveform,the ripple compensation waveform and the output waveform,using PNP type triode constitute the compensation current can achieve ripple compensation,using of components in a welding machine experiments, further validation control method and compensating circuit.Using compensation circuit can completely replace the drive power supply filter capacitor,and the compensation effect is better than that of filtering effect,while reducing the volume of the driving power design,achieving the miniaturization design.Lay the foundation for the widespread use of LED。...