Browsing by Author "Kuo, Chin-Chang"

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FPGA Control of a Single-Phase T-Type NPC Grid Inverter for Low THD and Robust Performance
(2017-01-01)
Kuo, Chin-Chang
;
Tzou, Ying-Yu
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents an FPGA-based adaptive predictive control scheme for single-phase T-type NPC inverter in applications to microgrids with high efficiency and robust performance. Predictive control is applied for current regulation to achieve fast dynamic response with low total harmonic distortion (THD). Implementation of a grid inverter with minimum inductor will result nonlinear inductance due to saturation effect. This nonlinearity can be tolerated with conventional PI controller with low bandwidth performance, however, oscillations or even instability may occur for predictive control with fast dynamic responses. An adaptive predictive control scheme with on-line inductance identification has been developed to ensure both fast dynamic response and robust stability. The proposed adaptive predictive controller has been realized using a mixed-signal FPGA Smartfusion (R) A2F500 from Microsemi. Experimental verification is carried out with a 3kW single-phase AT-NPC grid inverter. Experimental results show that the proposed control scheme can achieve both fast dynamic responses and high quality current regulation with THD close to its theoretical limits.
FPGA Control of a Three-Phase Three-Level T-Type NPC Grid-Connected Inverter with LCL Filter
(2018-01-01)
Kuo, Chin-Chang
;
Tzou, Ying-Yu
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents an FPGA control scheme for the active T-type neutral-point-clamped (AT-NPC) inverter with LCL filter in applications to three-phase grid-connected systems. The three-level AT-NPC inverter employs active bidirectional switches to produce an additional voltage level for its PWM generation and provide the advantages of lower conduction losses, lower switching losses, and lower common-mode voltage with superior output waveform quality. The LCL filter benefits from its significant harmonic attenuation capability but suffers from its resonance. A multi-loop control scheme is developed to control each state variable of LCL filer with predictive control applied for inner loop current regulation. Although fast dynamic response can be achieved by predictive control, it is very sensitive to measurement noises. To overcome these problems, multi-sampling technique is developed to improve the robustness of the control system. The proposed control scheme combines the advantages of digital control such as flexibility and accuracy with positive aspects of analog control such as real-time response and high bandwidth. The designed controller has been realized on a mixed-signal FPGA SmartFusion (R) A2F500. Experimental verification is carried out with a 9kW three-phase grid-connected inverter. The results show that the proposed control scheme can achieve both fast dynamic responses and high quality of current regulation.
FPGA Predictvie Control for Single-Phase Active NPC Grid Inverters with Multi-Sampling Technique
(2016-01-01)
Kuo, Chin-Chang
;
Tzou, Ying-Yu
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents an FPGA predictive control scheme for the active T-type neutral-point-clamped (AT-NPC) inverter in applications to grid inverters. Predictive control technique benefits from its fast response but also suffers with its high sensitivity to measurement noises and parameter uncertainties. To overcome the sensitivity problem of predictive controller, a multi-sampling strategy is developed to get its instantaneous average value and at the same to minimize possible sampling errors during the sampling process. The proposed control scheme can combine advantages of digital control with flexibility and accuracy and analog control with fast response. The designed predictive controller has been realized using a mixed-signal FPGA SmartFusion r A2F500 from Microsemi. Experimental verification is carried out with a 3kW single-phase AT-NPC grid inverter. Experimental results show that the proposed control scheme can achieve both fast dynamic responses and high quality current regulation with THD close to its theoretical limits.