A novel control method is proposed for a series resonant converter (SRC) that switches synchronously with the zero-crossing points of the resonant current. Output voltage is controlled by proper selection of the switch modes, which is achieved by varying the duty ratio of the powering and free resonant modes. Each switch mode is analyzed and the DC transfer function obtained. Simulated and experimental results agree well. Advantages such as low current switching stress, low switching loss, low electromagnetic interference (EMI), high input power factor, and wide control range are obtained. Some of these characteristics are verified experimentally.