| With improved requirements of rectifier power factor, total harmonic factor in new aircraft power standard, the traditional passive PFC,which is operates in400 Hz frequency mode, has been difficult to meet the requirements of the application, PWM rectifier,which is based on full controlled devices, is more and more used in airborne power supply, compared with, the devices of three-level PWM rectifier withstand smaller voltage and current stress, at the same time in the same switching frequency and the harmonic requirements can choose smaller input filter inductance. Besides the advantages of three-level rectifier, compared to a diode block bit type and capacitor block type three-level rectifiers are, the Vienna rectifier needs little devices and has simple structure.In this paper, we first introduce the topic background and airborne power supply topology and control strategy, then the paper focuses on the working principle of three-phase three wire Vienna rectifier, the mathematical modeling and controller design. In order to get high DC voltage utilization rate of the space vector pulse width modulation(SVPWM) is appliced, Vienna rectifier belongs to the three-level topology, the space vector up to 25, and a higher degree of complexity compared to two level SVPWM. Firstly, this paper according to the input current division six sectors, three-level space vector transformation for the two level space vector so as to simplify the design in each sector. Aiming at solving the problem of DC side neutral point unbalance which is widespread in three-level rectifier, this paper according to the effect of short vectors on neutral point, by adjusting the action time of different short vector to achieve neutral point voltage balance. According to the requirement in THDi of the project, the paper proposes that the adaptive filtering algorithm is applied to the elimination of the harmonics..After the theoretical analysis, calculates the value of inductance,capacitance according to the performance requirements of the project and builds a policy model in MATLAB, policy results meets theory coincide; finally designs the hardware circuit and software system of the rectifier. Experimental results show that the system in the steady state and dynamic index can meet the requirements.Through the comparison of harmonic current and power factor before and after join ASHE, proved that adaptive filter based on LMS can effectively filter a certain number of harmonics to Vienna rectifier, thereby reducing the rectifier THDi of input current, improving the power factor of therectifier. |
