Research On High Performance Control Strategy Of Indirect Matrix Converter For Induction Motor Drive System

Indirect matrix converter(IMC)with adjustable power factor and high power density,without large energy storage components,are suitable for a motor drive.Therefore indirect matrix driving induction motor speed control system(IMC-IM)has a wide application potential.But due to the complexity of IMC topology,and ac motor has the characteristics of nonlinear and time-varying.It is necessary to consider the power grid,converter,motor and load performance requirements,and coordinate the whole new speed control system.In which,IMC is the key component of the whole system,Obviously,the research on the high performance control strategy of the system is of great significance to accelerate the industrialization application process of IMC-IM speed control system.The conventional control strategy use motor vector control and IMC space vector pulse width modulation,but it's difficult to achieve multi-objective optimization with constraint conditions because of the complex control structure.Therefore,the model predictive control(MPC)with the advantage of simple control idea is introduced into IMC-IM system.In which,in order to keep the requirements of grid power quality and induction motor speed control system performance,flux,torque and reactive power and corresponding weight factors were set up.Due to the large number of physical quantities and the large magnitude difference,the weight factors are difficult to set and adjust,and it is difficult to realize the optimal control of all the objectives performance of the system.Aiming at the problems existing in conventional MPC,this paper proposes a model predictive dual-current control strategy.Multiple performance indicators on the motor side and grid side are converted into two current objective.In which,the optimization objectives of the motor are stator current,the optimization objectives of the grid are grid current.And the p-q extraction method is selected to obtain the ideal grid current reference,which combines harnonics and reactive power two optimization objectives.In order to simplify the predictive model in the control algorithm,the input current is used to replace the grid current.Through simulation and experiment,compared with the conventional MPTC,the weight factor of the proposed control strategy can be reduced to one,and it's easier to realize the Parameter adjustment,and achieve motor side good dynamic and static performance,and the grid unit power factor operation.In addition,it can greatly improve the quality of the grid current waveform,and reduce the computational complexity of the algorithm.The predicted output voltage vectors based on the same input voltage and finite switching state is limited,which cannot satisfy the optimization requirements under all speed conditions.Therefore,at low and medium speed,the grid and output current harmonics are large.This paper presents a two vector model predictive double current control,through the inverter side insert duty ratio variable voltage zero vectors,which can modify the magnitude of the finite voltage vector,and ensure commutation of the rectifier.Through simulation and experiment,under the uniform grid voltage,when the operating condition is low speed or low power,the voltage vector amplitude involved in the prediction is relatively large,this method can reduce the grid and output current distortion,and obtains a good waveform quality,and implement safe,easy and reliable zero current converter at the rectifier.