| Self excited induction generator(SEIG)has the technical advantages of easy maintenance,high protection level,easy weak magnetic control,output can be shortcircuited,etc.It has a broad application prospect in military equipment such as electric vehicles,radar,tank armor,etc.The combination of SEIG and three-phase PWM rectifier can form a class of cage-type Asynchronous motor power generation system,the system can still output high-quality DC energy in a wide range of speed changes,and can be used in the field of independent power systems such as vehicle power generation,small wind power generation.Because the mathematical model of the cage asynchronous motor power take-off system is strongly coupled,multivariable and nonlinear,there are internal and external uncertainties(such as the uptake of the physical parameters of the motor and external load disturbances)under wide speed operation and load shock conditions,so the robust and stable control of the cage asynchronous motor power take-off system becomes an important research content to improve the control performance of the power generation system.To this end,in this thesis,in-depth research and analysis have been conducted in nonlinear uncertainty model establishment,analysis of hybrid convergence law variable structure control algorithm,disturbance observer design,hardware system design and prototype system performance testing,and the following research results have been obtained:Firstly,based on the principle of spatial coordinate transformation,the SEIG,three-phase voltage-based PWM dynamic model under the orthogonal rotating coordinate system dq is established,and the intrinsic relationship between rectifier output voltage stability and electromagnetic torque variation is elaborated.Secondly,in order to solve the problem of weak dynamic response of traditional PI control under sudden changes in system conditions,a hybrid convergence law control strategy based on terminal attraction and exponential sliding-mode variable coefficients is proposed.Based on the instantaneous power balance of the power generation system,the new strategy uses the square of the magnetic chain and rectifier voltage as the state quantity of the outer loop subsystem,and adopts the variable coefficient mixed convergence law sliding mode control method to generate the target command of the current inner loop subsystem,and the current inner loop subsystem adopts the deviation decoupling control strategy to solve the mutual interference problem of AC and DC currents.The correctness of the proposed control method is verified by conducting the simulation and control characteristics analysis of the system under variable load operation.Thirdly,in order to reduce the influence of uncertainty factors on the stability of the control system,the Extended slip mode disturbance observer(ESM-DOB)is used to complete the estimation of the system model uncertainty and external disturbances,and the estimated values are introduced into the variable coefficient mixed convergence law to increase the resistance to disturbances,and at the same time This new method is a new class of composite control method with good anti-disturbance performance by suppressing the jitter phenomenon inherent in the sliding mode control.Simulation experiments prove that this control strategy can effectively improve the dynamic and static characteristics of the cage-type asynchronous motor power take-off system.Finally,physical parameter design of the main circuit,sampling circuit design,asynchronous generator parameter selection,IPM drive circuit design,communication interface design,etc.were carried out,and the control system software flow chart was given.Physical test tests such as DC bus voltage establishment,load shock resistance,and variable speed rectifier power generation were carried out on the caged asynchronous power generation test bench,and the test test waveforms were analyzed in detail to test the correctness and feasibility of the proposed control method. |
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