METODO DI RILEVAZIONE DI UN EVENTO DI ZERO-CROSSING DELLA CORRENTE CHE ATTRAVERSA UN CARICO INDUTTIVO E OTTIMIZZAZIONE DI UN SISTEMA DI

摘要

PROBLEM TO BE SOLVED: To detect the zerocross of the current of an inductive load without monitoring the current of an exclusive detective resistor in series with inductive load. SOLUTION: To detect the zero-cross of the current of the inductive load Ls driven in voltage mode through the half bridge consisting of a switch on high order side and a switch on low order side driven in opposite phases to each other by PWM signals, the voltage value at the output node A of the half bridge is compared with a fixed reference voltage value Vref, and the direction of the current in the inductive load Ls is judged from the comparison result. The comparison results are sampled cyclically during the period when both the switches mentioned above are off. Then, the zero cross can be detected by the inversion of the comparative value between the two continuous samplings.