Modeling and Control of a Low Frequency Off-line LED Driver Based on Boost Pre-Regulator

This work presents the state-space average modeling of the low frequency off-line LED driver based on the boost pre-regulator converter with an LC filter output. The small signal modeling of the converter was derived. A control strategy of the current through the LED arrangement is also proposed. The converter was designed to supply power to a street lighting LED luminaire. The LED driver prototype was able to present a high power factor (PF) and a low total harmonic distortion (THD). The output power of the LED driver was 186 W with 93 % efficiency, when fed by 220 V, 60 Hz mains. The modeling presented in this paper aimed to seek a more precise derivation of the control to output transfer function, i.e., the transfer function concerning the output current and the duty cycle switch parameter. The paper also provides details of the frequency domain design of the current compensator by employing the improved transfer function. The compensator must perform two main tasks, which are the output luminous control (dimming feature) and the rejection of input voltage disturbances. In addition, the compensator transfer function was discretized for future implementation in a microcontroller. Simulation results of the digital compensator in open-loop and closed-loop are presented to validate the small signal modeling and to observe the dynamic response of the proposed compensator.