Research On Digital Contrl And Parallel Technology For Single Phase Middle Frequency Inyerter

As part of the AC power supply system, medium frequency inverter is widely used in the field of aviation, shipbuilding and vehicles. The Parallel control technology of inverters can make power supply redundant and high-capacity, which is one of inverter’s development trends. Based on Two5kVA middle frequency400Hz/115V inverters, the digital control and parallel technology for single-phase middle frequency inverter are investigated in this thesis.First, the circuit structure and waveform control technique of single phase inverter are introduced. According to the characteristics of medium frequency inverter, asymmetric regular sampling is improved to reduce the delay brought about by digital control, load current feed-forward control is adopted, Proportional resonant controller (PR) and low-order harmonics compensation are also applied to the control of inverter. A prototype of5kVA single phase inverter is made, the simulation and experimental results show that the output characteristics of inverter is good.Second, mathematical modeling and circulation analysis of the parallel system consisting of two inverters are done, parallel control strategy based on the average active and reactive power control is used. By communication based on CAN bus, the loop of average power regulates the phase and magnitude of output voltage according to the output active and reactive power difference. CAN bus is also responsible for the synchronization of each module’s voltage reference and the logic switch of master and slave. The experimental results of two inverters connected in parallel, show that the circulation of the parallel system is low.Finally, the strengths and weaknesses of the stand-alone and parallel control strategy designed in this thesis are summaried. The work of the next step of the work is presented.