Browsing by Author "Wu, Kao-Chih"

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Control of a Single-phase Grid Inverter with On-line Inductance Identification
(2016)
Liu, Shih-Chun
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Wu, Kao-Chih
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Tzou, Ying-Yu
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電控工程研究所
;
Institute of Electrical and Control Engineering
This paper proposes a novel on-line inductance identification method to account for inductance saturation in current controller design for single-phase grid-connected inverter with single inductor filter. The predictive control method with delay compensation is used which has wide bandwidth and reaches steady state within one switching period in current control loop. A multiple-sampling method is developed for instantaneous current feedback, which can get average current even in DCM operation and low duty ratio conditions. An on-line inductance identification technique is proposed to compensate the model inductance parameter variation and stabilize the transient disturbances. Simulation and experiment results have been carried out to verify the results.
Digital Control of a Bridgeless SEPIC PFC AC-DC Converter with Variable Voltage Output
(2015)
Ho, Kuan-Sheng
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Wu, Kao-Chih
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Tzou, Ying-Yu
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電控工程研究所
;
Institute of Electrical and Control Engineering
Instead of constant dc-link voltage, this paper proposes a PAM/PWM for PMSM drive, which provides variable dc-link voltage to PWM inverter to reduce switching loss and improve system efficiency. An optimal dc-link voltage reference can be found for a specified operation speed for a centrifugal load condition. In order to realize the variable dc-link voltage, this paper implements a variable output voltage power factor correction (VOPFC) AC-DC converter for PMSM drive with bridgeless single ended primary inductor converter (SEPIC) topology. When it operates in DCM mode input current is in-phase with input voltage automatically and yields unit power factor. Therefore current control loop can be omitted and control system is simplified. Simulation and experimental results have been carried out to verify the performance of the PFC converter.
Sensorless PMSM Drive with Large DC-link Voltage Fluctuation
(2017-01-01)
Tau, Jen-Hau
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Wu, Kao-Chih
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Tzou, Yin-Yu
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電控工程研究所
;
Institute of Electrical and Control Engineering
This paper realizes a high power factor, high reliability, and low cost PMSM drive system with small DC-link capacitor. Compared with conventional bulky electrolytic capacitor for the regulation of DC-link voltage, a small-size film capacitor with capacitance reduction to 1% is used to realize a seneorless PMSM drive with high power factor, high reliability, and high compactness. To overcome high DC-link voltage fluctuations due to the small capacitor, the d-q axis current commands are modified according to the measured dc-link voltage and a power factor derived torque control strategy. A dc-link voltage feed-forward compensation scheme is used to minimize speed ripples due to the large voltage fluctuation effect. Simulation results show that design compromise between power factor, dc-link voltage ripple ratio, and speed ripple ratio can be achieved for practical design considerations. Experimental results of a sensorless PMSM drive in rated condition with a measured power factor of 97% with a reduction of dc-link capacitance to 1% have been obtained.