Research On Carrier-Based PWM Control Strategy For Three Level Indirect Matrix Converter

Matrix Converter(MC),also known as "green converter",has many advantages,including smaller common mode voltage and switching stress,lower distortion of the output voltage waveform,etc.The Three Level Indirect Matrix Converter(TLIMC)is a new type of converter that combines three-level technology and MC technology to improve voltage transmission efficiency and standardize output waveforms.TLIMC is becoming more and more widely used in high voltage,large capacity and high power applications.In the power system,especially in the power conversion,the research on TLIMC is of great significance.In this paper,the diode-clamped TLIMC is used as the research object.First of all,in terms of topology,TLIMC is divided into rectifier stage and inverter stage.The rectifier stage runs from the traditional single rectifier to the two identical rectifiers.The rectifiers operate synchronously.The inverter stage is a three-level inverter structure.Each output phase is connected in parallel by two diodes as a clamped circuit.Then,in terms of control strategy,the Space Vector Pulse Width Modulation(SVPWM)method is used to control the TLIMC by calculating the duty cycle of the rectification stage and the inverter stage,and the output characteristics is analyzed.The duty cycles are used as important conditions of Carrier-Based Pulse Width Modulation(CBPWM).At the same time,an isosceles triangular carrier is constructed.Combined with the calculated duty cycles,the modulation waveforms of the rectifier stage and the inverter stage are obtained by derivation.Then,the modulation waveforms are compared with the same triangular carrier and the CBPWM method is realized through logic calculation.Comparing two control strategies studied in this paper,the similarities and differences between the two strategies,including calculation amount,output effect and switching loss.The CBPWM method can avoid complex trigonometric functions,thus reducing the amount of computation.The two strategies are equivalent in output effects,commutation strategies,and switching losses.Finally,through the MATLAB/Simulink simulation platform,the topology model of TLIMC is built.The functions of two strategies are written by the S function,and they are simulated,respectively.The simulation results prove the accuracy of the proposed control strategies.