| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a simple and precise zero voltage switching circuit. SOLUTION: A zero voltage switching protection circuit 2 switching a zero voltage is zero voltage switched so as to supply electric current to a fluorescent lamp. The zero voltage switching protection circuit 2 detects the switching condition of a zero voltage switching unit 1. A control unit 3 compares a predetermined voltage signal Vo with a reference voltage Vr , and on the basis of the combination of the comparison result V1 and the information V4 from the zero voltage switching protection circuit 2, and regulates the switching duty of the zero voltage switching unit 1 which is transmitted as an inputs OUT1 and OUT2 of the zero voltage switching unit 1. As the zero voltage switching circuit 1 detects voltage, a precise zero voltage switching action can be carried out easily in comparison with a conventional way in which a resonance current is detected. The zero voltage switching action is secured against the input voltage fluctuation and the load fluctuation in a wide range, so that a switching loss in main switching electric power elements Q1 , Q2 can be minimized.</p> |
