The ECD is utilized for the conversion of both wind power and wave
energy. Consequently, the efficiency of the ECD is significant for the
W2P. The experimental scheme by using the power recovery method is
designed to test the efficiency of the ECD. And the test platform is built,
which is shown in Fig. 4b. Through the reduction gear box the output of
the hydraulic motor is transmitted to the ECD, which produce high
pressure oil cycling to the experimental hydraulic motor. The power
loss of the circulation is supplemented by the high pressure oil from the
main pump outside. The power loss of the reduction gear box can be
calculated using the data of the torque and speed sensors. The flywheel
increases the rotation inertia to weaken the fluctuation of speed. In the
stable configuration, the power loss of the ECD can be calculated by the
difference between the circulation power loss which equals to the
power supplement of the main pump and the sum of the power loss of
the reduction gear box and the hydraulic motor. The method has the
advantage in avoiding the energy consumption of the simulated load.
The efficiency of the ECD under various pressures and speeds shown in
Fig. 4c demonstrates that the efficiency η is over 80%