The wind turbine blade is gradually developing towards large scale.In order to improve the excitation ability of wind turbine blade fatigue test and shorten the test cycle,the coupling vibration of two exciters has become a promising development direction in fatigue test methods.First of all,the coupling characteristic test of two exciters was carried out,the blade test plan of excitation source speed,phase and amplitude was designed.The wind turbine blade was tested under the effect of this excitation source,in which the two exciters initial speed were set to 35 r/min.The results showed that two excitation speed difference was in the range of ±5 r/min,phase existed coupling phenomenon and the blade amplitude was disorderly.In order to improve the synchronization effect of two exciters,based on the analysis of the existing control strategy,using parallel cross coupled structure,the sliding mode variable structure control algorithm was developed by using the Lyapunov function and the asymptotic stability of the algorithm was proved.Finally,a set of 10 MW large test platform of wind turbine blade fatigue was built,the fatigue excitation control system based on distributed network bus was developed,and the sliding mode variable structure control algorithm was applied to aeroblade 2.0~54.38 wind turbine blade fatigue test,in which test was driven by two exciters.Test results showed that in both the excitation source speed were 35 r/min,the rotational two exciters phase keep step,phase can also basic synchronized,and the blade amplitude was the largest and very stably.Under the different initial speed drive,respectively set as 40 and 30 r/min,the speed of the two exciters can quickly follow and keep respectively.Due to the inconsistency of the two rotational speeds,the amplitude of the blade was fluctuating.The test results showed that although the electromechanical coupling between two exciters was sequestration,the development of the sliding mode variable structure control algorithm could make two exciters keep step with rotational speed,phase,and had a good robust property,effectively guarantee the smooth progress of fatigue test.
