Research On Segmented Synchronous Modulation Strategy Of ANPPC Three-level Inverter

Active neutral-point-clamped topology is a kind of inverter structure commonly used in the field of high voltage and high power.Pulse width modulation technology is the core of its control technology.In this paper,ANPC three-level frequency inverter is studied indepth about its topology,space vector modulation,selective harmonic elimination pulse width modulation,segmented synchronous modulation strategy and impulse current at switching time,through theoretical analysis,mathematical model derivation,software simulation,experimental verification and other research methods.The flow path of the load current inside the inverter and the switching of the power device under different commutation methods are analyzed,taking the single-phase bridge arm as an example.The mathematical model of the inverter topology in three different coordinate systems is established in this paper.The space vector modulation algorithm is used in this paper,which judging the sector of the reference voltage vector by angle.The seven-segment SVPWM modulation is simulated and analyzed in this paper,and is divided into four-segment modules to analyze the reason why the three-level SVPWM phase voltage does not jump.The mathematical model of the three-level SHEPWM with 1 / 4-cycle symmetrical waveform is established in this paper.A segmented synchronous modulation strategy suitable for traction load using SHEPWM is proposed and simulated,which achieving minimum pulse width requirements by stitching multiple sets of solutions.The advantages and disadvantages of three modulation methods commonly used in three-level inverters are compared in this paper and then the reasons for the selection of IGCT operating frequency are explained from the perspective of output power.Then the full response of the RL first-order circuit is analyzed based on the simplified model of asynchronous motor.From the perspective of the motor flux linkage,a simple and effective angle compensation method is proposed to eliminate the current impulse,and the effectiveness of the method is verified by simulation and experiment.