Research on amplitude-modulating and phase-modulating wavelet modulation strategy for high-power three-level inverters
When the traditional wavelet modulation strategy is applied to inverter control,it is difficult to adjust the output voltage phase accurately.This paper introduces the principle of the traditional wavelet modulation strategy,and then proposes an improved amplitude-modulated and phase-modulated wavelet modulation strategy for the first time,and expounds its basic working principle and procedure.By using two different ways of determining wavelet scale factor,the problem of adjusting the output voltage phase of the inverter is solved,and the feasibility of the amplitude-modulated and phase-modulated wavelet modulation strategy for harmonic control is further discussed.At 700 Hz switching frequency of power devices,the proposed amplitude-modulated and phase-modulated wavelet modulation strategy,the traditional wavelet modulation,carrier phase-reverse cascade modulation,and intermittent pulse width modulation and other modulation strategies are respectively applied to a three-level midpoint clamp inverter circuit,and the performances of the output phase voltage and midpoint potential balance are compared.The simulation and experimental results show that for the proposed amplitude-modulated and phase-modulated wavelet modulation strategy,the non-integer scale factor method has a good effect on the suppression and accurate control of the inverter output voltage subharmonics.The integer scale factor method makes the inverter have a higher fundamental voltage amplitude,and the DC side midpoint potential fluctuation is the smallest.
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