Optimal Trajectory Control for LLC Resonant Converter for LED PWM Dimming

摘要

Pulse width modulation is provided for controlling a resonant power converter, particularly for dimming of light emitting diode arrays without loss of efficiency. Dynamic oscillation due to the beginning of a pulse width modulated pulse burst is limited by shortening of the first and/or last pulse of a pulse bust such that the first pulse of a subsequent pulse burst close to or to connect with a full load steady-state voltage/current trajectory of the power converter. Pulse shortening made be made substantially exact to virtually eliminate dynamic oscillation but substantial reduction in dynamic oscillation is provided if inexact or even performed randomly.

主权项

1. A method of operating a resonant power converter, said method comprising steps of
generating a pulse waveform comprising pulses at a first frequency for controlling generation of switching signals to control application of input power to said power converter, generating a pulse width modulated signal comprising pulses of controllable duty cycle at a second frequency, and periodically interrupting said pulse waveform in accordance with said pulse width modulated signal wherein said first frequency is sufficiently greater than said second frequency to form pulse bursts from said pulse waveform, each said pulse burst comprising at least three of said pulses.