A High Performance DSP Voltage Controller with PWM Synchronization for Parallel Operation of UPS Systems

A High Performance DSP Voltage Controller with PWM Synchronization for Parallel
Operation of UPS Systems

Kyung-Hwan Kim
Hanyang University
Department of Electrical Engineering
17 Haengdang-dong, Seongdong-Gu, Seoul KOREA

Inverter system, which uses LC component as the output filter, is essential for a UPS (Uninterruptible Power supply), UPQC (Universal Custom Power Conditioner) and PCS (Power Conditioning System) for the photovoltaic power system. This paper presents DSP (Digital Signal Processor) controlled voltage controller for a 3-phase UPS inverter, which is able to compensate the voltage distortions due to unbalanced and nonlinear loads. The paper discussed the problem of conventional control schemes for the compensation of voltage distortion when they are applied to UPS inverter, and proposes advanced synchronous reference frame control scheme which is able to overcome the problem. In order to solve the problem of low damping ratio of LC filter, the inverter current feed-forward compensator including the selection of the feed-forward gain is proposed. And the digital filter for a compensation of the voltage distortion due to unbalanced and nonlinear loads is also proposed, which makes PI controllers in the synchronous reference frame are able to operate with DC values even under nonlinear and unbalanced load, likewise ensures PI controllers are able to provide zero steady state error. In order to improve the practical usability of the proposed scheme in the paper, the realization of the PLL and the parallel operation, which are essential for UPS, using the proposed controller is also presented. Especially, this paper shows that the feed-forward compensation of the inverter current and the PWM synchronization method proposed in the paper ensures a high precise load-sharing performance in parallel operation of inverter system.

A New Equivalent Circuit Model of IGBT Current Sensors Chun-Chieh Tseng* Chia-Hsiung Kao**

 

A New Equivalent Circuit Model of IGBT Current Sensors
Chun-Chieh Tseng* Chia-Hsiung Kao**
ABSTRACT
A new equivalent circuit model for IGBT is presented. It takes into account both
electron and hole conduction in sensors and is incorporated with SPICE3 for the
simulation of three types of current sensors, namely active, bipolar, and MOS sensors.
It adopts a multi-MOS model to include the doping variation in the MOS body. The
results agree well with the current sensing measurements within an average error of
4.4%.

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ANALISIS DE SISTEMAS DE POTENCIA ING. ALVARO ACOSTA MONTOYA

TRANSFORMADORES DE POTENCIA DE MEDIDA Y DE PROTECCION ENRIQUE RAS

5. Z Transform MIT MIT 6.003 Signals and Systems, Fall 2011 V MASSACHUSETTS INSTITUTE OF TECHNOLOGY

Course Description

6.003 covers the fundamentals of signal and system analysis, focusing on representations of discrete-time and continuous-time signals (singularity functions, complex exponentials and geometrics, Fourier representations, Laplace and Z transforms, sampling) and representations of linear, time-invariant systems (difference and differential equations, block diagrams, system functions, poles and zeros, convolution, impulse and step responses, frequency responses). Applications are drawn broadly from engineering and physics, including feedback and control, communications, and signal processing.