Abstract:As a kind of ocean energy, wave energy is a renewable energy with the character of widespread, abundant and highly energy flux density. But the extracting energy from waves is limited for its unstable power input and characterized with inputoutput power coupling. The main characters and needs were analyzed and a hydraulic transmission scheme for the power take off system was proposed. The hydraulic transformer principle was applied in the hydraulic circuit to achieve variable pressure network to constant pressure network and power inputoutput decoupling. Large capacity accumulator was installed in the circuit to absorb system pressure and flow pulsation. As a result, a constant power and speed output was achieved under different sea state condition. The mathematical model of the hydraulic power take off system was established, the simulation results show that it is possible to obtain a constant frequency and smooth voltage output from a ocean wave converter.