In the wind energy conversion system (WECS) based on the permanent magnet synchronous generator, the topology that a wind generator is connected to a voltage source inverter through a diode rectifier and a boost chopper is widely adopted for its low cost and high reliability. However, with the increasing power level of the WECS, the power switch device of a boost chopper in the topology has to endure high instantaneous voltage and current stress, thus reducing the system reliability. Although the traditional multiple boost converter reduces the transmission power level of single circuit units in terms of structure, it is still limited by narrow speed regulation range. Thus, a novel switchable-cascaded-mode boost chopper is proposed in this paper. The operation principle of the new converter and the generator speed control strategy are analyzed. At last, the effectiveness of the new converter is verified with an experimental prototype. The experimental results demonstrate that speed range is extended by using the new topology as generator-side converter in the permanent magnet wind generation system.