Full-bridge current-fed inverter with automatic frequency control for forging application

The paper describes a full-bridge current-fed inverter for forging applications. Inverter is implemented by using IGBT in series with diodes as its switching devices. The operating frequency is automatically tracked to maintain a small constant leading phase angle when load parameters change. The load voltage is controlled to protect the switches. The output power can be adjusted by varying the input current from phase controlled rectifiers which is a part of current source. The system has been operated at 15.5-16.8 kHz. The output power transferred to the load is 1,595 watts. It can heat the steel work pieces with 15 mm diameter and 120 mm long from room temperature to approximately 1100°C within 30 seconds with 0.97 leading power factors on the input side.