Research On Key Technologies Of LED Driver With High Adaptive Ability

Owing to the high luminance efficiency and long life,LED is expected as an outstanding lighting source that has a positive impact on the environment.In the past decade,the luminance efficiency of LED kept increasing while the cost plummeted,which makes LED a preferred option in various applications.Consequently,the driving technology of LED has become an attractive research filed in power electronics.This paper begins with analyzing the current status of LED applications and summarizing its typical development characteristics as coexistence of LED and other light sources,coexistence of standardization and customerization,and networked control.Then after concluding pivotal challenges of the LED driving technology,the paper proposes a novel solution of a highly adaptive LED driver,including the adaptivity to different loads,the adaptivity to communication function and the adaptivity to networked control.Regarding the adaptivity to lighting sources,driving technology which can be compatible with various light sources is generated based on the flexible topology and illustrated as a compatible driver for selectively driving LED or HPS.HPS ballasts and LED driver are comparatively studied.And it is found that a vast majority of these two kinds of drivers are configured in half-bridge resonant converters whereas the resonant tanks are respectively LCC and LLC to accommodate different load characteristics.Therefore,a structure with variable resonant tank is produced,wherein most parts of the main circuit and control circuit are fixed to lower the replacement cost.The variable resonant tank allows the circuit topology to be restructured in accordance with the load characteristic while maintaining soft switching and dimming features of the resonant converter.With regard to the adaptivity to different LED loads,an adaptive driving solution is provided to facilitate the coexistence of standardization and customerization.The adaptive driver establishes a database to store voltage-current characteristic curves of various loads.The voltage and current of the load is automatically sensed and compared with the predetermined curves in the database to indentify the load.Based thereupon,appropriate current could be provided to the load.To ensure the accuracy of voltage and current sensing,the driver can further set up a run-up stage and a burn stage.This adaptive controlled driver can effectively cut down on the genres of LED drivers to satisfy the coexistence of standardization and customerization.In reference to the adaptivity to networked control,the paper completes two research aspects as below.Firstly,a power grid synchronization method which is adaptive to LED drivers with networked control is brought out.Through communication apparatuses,the operation commands are transmitted to the LED drivers,which allows each LED driver to time and conduct the operation based on its own internal clock.As both cycle and phase of the grid voltage are identical in the same power grid,the LED drivers utilize the grid voltage for synchronization correction,so as to decline the time difference among the operations and enhance the system performance.In the interest of demonstrating the effectiveness of the synchronization strategy,the paper additionally investigates measurable indicators representative of the system performance and generates a mathematic model based on statistics and probability theory.Secondly,a DC power grid LED driver network is proposed according to the power electronics variable mode control theory.In the DC grid,a computer is used to remotely control a bus converter through mobile internet.Connecting to the power grid to convert the grid voltage into a DC bus voltage,the bus converter involves the variable mode technology to change its working mode,so as to modulate information onto its output waveform.The distributed LED drivers connected to the bus can obtain energy to drive LEDs,demodulate the messages at the same time.Thus,through power electronics solution,this modified powerline carrier concept makes LED drivers compatible with communication technology.According to the research points mentioned above,this paper establishes multiple prototypes and experimental systems and verifies the feasibility of the proposed technologies of highly adaptive LED driver.