Dynamic Study of a Phase-Controlled Parallel-Series (LC_pC_s) Resonant Converter to Drive High- Brightness Power LEDs

摘要

This paper presents the study of the dynamics of a phase-controlled resonant converter suitable to drive high-brightness light emitting diode (LED) lamps. The transfer function of the control angle to output current is calculated through the envelope model of the resonant network and reduced to an equivalent L-R circuit. The approximate mathematical closed form of the transfer function is obtained using the new reduced-order envelope model. The model predicts that the current gain is set by the resonant inverter stage while the bandwidth is defined by the output filter capacitor and the LED dynamic resistance, providing a large bandwidth which leads to excellent dynamic behavior of the whole system using a simple integral control action. This performance is used to implement pulse width-modulated (PWM) light control.