Pwm Strategies for Inverters with Fluctuating Dc Link Input
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چکیده
It is normally assumed that the dc-link is a perfect constant dc voltage. However. in a practical system. it contains ripple components due to the rectification process. An analysis of the power conversion process shows that the power at the dclink consists of constant active power as well as a pulsating component that fluctuates at twice the mains frequency. When a VSI is powered by the fluctuating dc-link voltage. it generates additional subharmonics because of the modulation heween the inverter switching function and the dc-link ripple [97]. Moreover. the ripple in the dc-link is the primary contributor for the appearance of harmonics in the inverter output not present in the PWM switching function 1981 and is responsible for the deterioration in the quality of the output voltage. Further the harsh loads on the invener power supply contrihutc to wa\.eform distortion and intmduce abnormal harmonics in the invener input current. The switching action further creates ripples at the dc-link.
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