Development For The Multi-level Programmable AC Power Supply

The amount and type of airborne electronic and electric equipment is greatly increased with the emergence of new military and civil aircrafts in our country. Without aircraft power adaptive authentication, the airborne electronic and electric equipment, which threatens flight safety at the worst case, may be quite harmful to the aircraft power supply system. Therefore, in order to test the power adaptability of the airborne electronic and electric equipment, a single-phase programmable AC power supply using multi-level inverter technology is proposed. The designed power supply can not only output sinusoidal voltage with a wide range of frequency and amplitude, but also can generate distortional voltage with harmonic and DC components defined beforehand, finally simulating a variety of aircraft power grid operating state.The simulation research of multi-level inverter technology is first studied, a 2H-bridge and 3H-bridge comparative simulation model is built based on MATLAB/SIMULINK simulation platform, and the simulation results show that no distortion occurs when 2H-bridge is used as the basic inverter unit instead of 3H-bridge. Nine-2H-bridge inverter simulation model is built based on the carrier phase shifting control strategy, and the simulation results verify that 2H-bridge tandem cascade inverter can eliminate the specific harmonic components. The modulation waveform generator simulation model is built based on direct digital frequency synthesis technology, and the simulation results show the bad influence of the frequency control word truncation error and the benchmark timer frequency error, and thus the optimized method is proposed.On the basis of research above, the overall scheme of the multi-level programmable AC power supply is proposed. The five-2H-bridge inverter is taken as the main power supply circuit topology; the carrier phase shifting control PWM control method is applied as the control strategy. The direct digital frequency synthesis technology is utilized to generate modulation waveform. According to overall scheme, multi-level programmable AC power supply simulation model is established based on MATLAB/SIMULINK platform, and simulation analyses on both steady output function mode and disturbance output function mode are performed respectively. The simulation results show that the designed scheme satisfies the power supply functional request and the requirements of technical indicators.The design of hardware and software is completed with the analysis of simulation results. A “back-board + functional sub-board” structure is adopted in design of hardware, and a “DSP + FPGA” minimum double CPU system is taken as the control core. Main circuits are analyzed, and key parameters and their selection methods are put forward. The design of software is based on functional analyses of overall scheme. Both program flow chart of DSP and top principle block diagram of FPGA are given.Finally, the multi-level programmable AC power supply prototype is developed, and functional experiments on prototype are performed. The experimental results show that the designed multi-level programmable AC power supply achieves the desired function.