1. A CURRENT CONTROLLER DESIGN FOR CURRENT SOURCE
INVERTER-FED AC MACHINE DRIVE SYSTEM
ABSTRACT:
A current source inverter (CSI) requires a capacitor filter for the commutation of switching device as
well as for attenuating switching harmonics. Hence, the CSI-fed ac machine has a second-order system in
the continuous time domain. This paper presents a design methodology for the closed-loop current controller
of the CSI-fed ac machine drive system. A multiloop current controller design using a pole/zero cancellation
method is employed with a transfer function matrix. To decouple the cross-coupling terms which cause
mutual interferences between the d- and q-axes in the synchronous reference frame, two types of controller
are proposed and implemented using different decoupling method. Additionally, active damping methods
are incorporated to enhance the stability of the system. A stability analysis in discrete-time domain is
investigated to verify the feasibility of the proposed closed-loop current controller. To evaluate the
effectiveness of the proposed current controller, computer simulations and experimental tests were
performed and the results are discussed.