MODEL REFERENCE ADAPTIVE CONTROL IN DISCRETE-TIME APPLIED ON THE LLC LED DRIVER
This paper presents the model reference adaptive control (MRAC) applied to the DC/DC LLC resonant converter supplying a light emitting diode (LED) based load. The MRAC is employed in order to overcome the drawback of closed-loop control system with changeable controller gains, which are needed to obtain a good performance at different operating points of the converter. The MRAC is designed to maintain the average LED current controlled at the reference value, which will be changed to obtain LED current amplitude modulation, consequently dimming. Furthermore, to avoid LED current modulating, raised from the unavoidable bus voltage ripple in an off-line LED driver, the adaptive controller algorithm measures the bus voltage ripple and changes the control action to attenuate its effect on the output LED current. Experimental results shows the feasibility of adaptive control applied to the LED driver.