| Indirect Matrix Converter(IMC),which can realize Sinusoidal input and output performance,unity input power factor,energy bidirectional flow,high power density,etc,is Suitable for Aerospace,military equipment and other systems.However,its control structure is very complex,and the input Characteristics is coupled with the output.In this paper,the working mechanism of the system is analyzed,and the optimal control strategy is studied to realize the whole system optimization.Firstly,the traditional control strategy,which combines vector control of induction motor and indirect space vector modulation of IMC,is used in this paper.To confirm and suppress the characteristic of input current harmonics and improve power grid quality,the pulse barycentre concept,in which the amplitude,width and distribution position of a pulse are all considered,is introduced to analyze and determine both components and contents of main harmonics.In addition,the principle of the output voltage vector pulse proportional symmetric distribution for the vitual inverter circuit,which is able to simplify input current harmonics,is proposed and utilized in different modulation strategies.This principle can provide a theoretical basis for optimizing the PWM pulse sequence.Furthermore,the model predictive control strategy,which is Simple and intuitive,with good dynamic performance,is applied to the induction motor drive system fed by IMC.In order to simplify the commutation in the virtual rectifier,a zero current commutation model predictive control(ZCC-MPC)method is proposed.Switching states combination is adopted in the virtual inverter and the switching delay time is used for vitual rectifier which can ensure that the inverter stage keeps at zero voltage vectors during the whole commutation procedure between bi-directional switches.The commutation time is shorten and the current direction detection is not needed.To simplify the complex and nu merous sampling circuit of MPC strategy,an input voltage observer is designed based on the model of input filter.Moreover,the direct coupling between input reactive power prediction and input voltage is released.As a result,the weight and cost of sampling circuit can be decreased.Finally,the experimental platform of induction motor drive system fed by IMC is built.The vector control and model predictive control strategy are used to test the system.The simulation and experimental results verified the correctness and effectiveness of the pulse width distribution principle to simplify the input harmonics and the ZCC-MPC strategy with the input voltage observer. |
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