Design of an Optimal Stationary Frame Controller for Grid Connected AC-DC Converters

Development of current control schemes for use in PWM power electronic converters has been widely investigated. Linear PI regulators are well documented and show satisfactory results in the synchronous dq-frame. However, the use of PI regulators in the stationary frame is inadequate due to steady-state errors. Recently, a zero steady-state error P + resonant regulator has been introduced, however, the design is more complicated than that of a PI in the synchronous frame. This paper presents a two-step process to obtain an optimal stationary frame regulator. The proposed controller includes proportional (P) and resonant (R) regulators in addition to a cross-coupling regulator (X). The PRX controller offers excellent transient and steady-state responses and is derived directly from the design of a PI controller in the synchronous frame