| The magnetic shape memory alloy (MSMA) is a new functional material with largemagnetic-field-induce strain, great output strain, high response speed and strong energydensity. In this dissertation, the experimental studies of magneto-mechanical-thermalcoupling properties and control strategies with Ni2MnGa alloy have been carried out.The main research contents are as follows:（1）Based on the experimental studies of magneto-mechanical-thermal couplingproperties, the closely nonlinear relationship among pre-stress, controlling magneticfield, operating temperature and deformation rate of MSMA was obtained. A predictionmodel of the driving performance of MSMA was proposed based on BP neural network,and parameter of the prediction model was optimized through the genetic algorithm.The results showed a good corresponding relationship among pre-stress, controledmagnetic field, operating temperature and deformation rate of MSMA.（2）In view of the traditional MSMA actuator which was used the excitationcoilthat led to rise the temperature of MSMA actuator. In this thesis, the optimum measureswere proposed. Compared with the traditional magnetic control loop of MSMA actuator,there were permanent magnet and cooler installations to lower the temperature ofMSMA. Some simulations were carried out upon electromagnetic field and temperaturefield. The simulations indicated that the designed driving magnetic control loop ofMSMA actuator can meet the requirements.（3）Based on the model of MSMA actuator, the relationship between the inputvoltage and the output displacement was obtained. Based on the inherent hysteresisnonlinearity of MSMA actuator, the hysteresis model of MSMA actuator was botained.In order to reduce hysteresis nonlinearity of MSMA actuator and improve thepositioning accuary, we used two control strategies which were the closed loop controland the compound control. The final results indicated that the control effect of theclosed-loop was better than that of compound. |
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