Owing to different parameter tolerances of the primary windings, grid current could be unbalanced.

What is it about?

Owing to different parameter tolerances of the primary windings, grid current could be unbalanced, which usually could not be solved through traditional control methods. To handle this problem, a current balancing method is adopted in this paper to improve former current control loop. Meanwhile, based on the principle of instantaneous power balance, a dual loop control strategy with an outer voltage loop and an inner current loop is designed. Besides, load current feedforward control is introduced to enhance the dynamic response. Moreover, phase-shift control is employed as the modulation method, in which duty ratios change along with sinusoidal signals.

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