• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.5
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• pp.404-408
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• 2006

This paper presents an anti-windup gain selection method for a complex vector synchronous frame PI current controller. The complex vector PI current controller is more robust to the parameter variation than the state feedback decoupling PI current controller. The complex vector PI current controller also includes an integral term, which can results in windup problem when the controller is saturated due to physical limitation of the system. Furthermore, even an anti-windup is utilized, inappropriate gain can deteriorate the performance of the current controller. Therefore, appropriate anti-windup gain selection method for a complex vector current controller has been proposed based on the mathematical description of the current control system. The superior performance of the current control system with the proposed anti-windup gain has been verified by the experimental results.

• Journal of Power Electronics
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• v.18 no.2
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• pp.502-510
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• 2018

A circulating current is a major problem caused by directly connecting voltage-source inverters (VSIs) in parallel. This circulating current occurs as a zero-sequence current between the inverters by specific switch states. Several studies have presented alternatives using hardware and software methods. When coupled inductors (CIs) are employed for the high-frequency circulating current, a controller is required to prevent the low-frequency circulating current from saturating the CIs. In this study, the zero-sequence circulating current and its alternatives are investigated using hardware and mathematical description. A high-performance circulating current controller is proposed by applying a repetitive controller to the zero-sequence current control loop. The proposed controller can effectively minimize the low-frequency circulating current without any data sharing between the inverters in unfavorable conditions. It can also be applicable to the modular configuration of parallel three-phase VSIs. Experimental results verify the performance of the proposed controller.