Primary Switched Power Supplies with Ferroresonant Stabilization

Primary switched power supplies operating at supersonic conversion frequencies (20-50 kHz) are usually based on duty cycle control. This paper presents another possible technique - ferroresonant control. The difficulties connected with the application of the ferroresonant principle at high frequencies can be eliminated by using the controlled ferroresonant technique. The paper covers the principle of operation and the evaluation of the performance of ferroresonant control, as compared with switched-mode duty-cycle-controlled devices. A practical implementation, a unit of 175 W output power, is described and its performance presented.