Research On Modulation And Control Of Active-Neutral-Point-Clamp Converter

Due to the limitation of the power device voltage level,the traditional two-level,NPC three-level,T-type three-level converter cannot be applied in the high voltage field.In order to reduce the switching loss of the device,the harmonic content of the voltage and current,various multi-level converter topologies have emerged.The active netural pointed clamp(ANPC)fivelevel topology has received wide attention in the industry due to its advantages of only one floating capacitor and one DC bus per phase.In this paper,the vector control of permanent magnet synchronous motor is studied based on the active netural pointed clamp(ANPC)five-level converter.Firstly,the ANPC five-level topology is introduced to analyze the stress of the switch tube.Aiming at the disadvantages of traditional suspension capacitor control,a control method based on half-cycle floating capacitor voltage is proposed.The principle and implementation flow of the control method based on half-cycle floating capacitor voltage are given.Secondly,the reason of the fluctuation of the midpoint capacitor voltage and the proof process of the self-balancing of the midpoint capacitor voltage under ideal conditions are given.The influence of each switch combination on the midpoint voltage and the floating capacitor voltage under different states is analyzed in depth.The traditional SPWM modulation of level converters proposes a zero-sequence injection shifting carrier SPWM modulation method to effectively suppress the midpoint capacitor voltage.After that,the control method of the existing ANPC five-level SVPWM is given.The advantages and disadvantages of the existing control methods are analyzed.A SVPWM modulation strategy based on spatial origin mapping is proposed.The method simplifies the number of space vectors and establishes separately.The switch combination logic that forms the charge and discharge circuit.The system can be stabilized at the midpoint voltage by selecting the switch combination under different states.The dead zone state of switching between different states is analyzed,and the voltage state that may occur in the dead time is given,and the dead zone is compensated.The accuracy of the SVPWM control method based on spatial origin mapping is verified by simulation.Then,the traditional permanent magnet synchronous motor sliding mode observer is used to estimate the lag of the rotor position.A non-position control method for permanent magnet synchronous motor based on quasi-resonant observer is proposed.The quasi-resonant controller has the advantage of extracting specific frequency.The introduction of quasi-resonant control can accurately extract the back EMF of the permanent magnet synchronous motor,which effectively improves the estimation performance of the observer.Finally,the simulation model of vector control system is built by using PLECS simulation software.The simulation results show that the control system has excellent dynamic response.The software and hardware design of the control system with DSP28335+CPLD as the core is completed,and the experimental research is carried out on the experimental platform.The experimental results show that the system has good dynamic and static performance,and further demonstrates that the system has higher performance.The practical application value.