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The introduction of multilevel converters makes possible the use of pulse width modulation (PWM) converters and fast switching medium power devices like insulated gate bipolar transistors (IGBTs) for high-voltage, high-power applications, such as flexible ac transmission systems (FACTS). This paper proposes a five-level voltage source inverter (VSI)-chopper for a superconductive magnetic energy storage (SMES) power conditioning system (PCS). The circuit topology and operation principles are presented. The advantages of the proposed power conditioning system have been investigated and compared with present PCS including a traditional transformer coupled multi-pulse VSI-chopper topology. The validity of the system is verified by computer simulation. [ABSTRACT FROM AUTHOR]

In this paper, a new controller for single-phase PWM converter without the ac voltage sensor is described. The proposed controller requires only the dc voltage sensor and the ac current sensor to compensate the power factor and harmonics. Detail simulation model including power circuit and controller was developed to verify the operation of proposed controller. The ape plication feasibility of the proposed controller was verified through experimental works with a prototype. The proposed controller has a simple structure in the point of hardware implementation, and shows excellent performance in normal operation as well as in sudden load change. [ABSTRACT FROM AUTHOR]

This paper presents a quadratic boost converter using a single quasi-resonant network to reach soft commutation. A resonant inductor, a resonant capacitor, and an auxiliary switch form the resonant network and the main switch operates in a zero-current-switching way. A complete analysis of this converter is presented. According to the simulation and experimental results, this quadratic boost converter provides a larger conversion ratio than that provided by the conventional boost converter (for a given duty ratio D), and presents optimum performance, which operates with soft-switch commutation using a single resonant network. [ABSTRACT FROM AUTHOR]

High-power synchronous motor drives are usually fed from naturally commutated cycloconverters. The output voltage of the cycloconverter contains interharmonics/subharmonics which affect the power quality and restrict the allowable frequency range. Further, a practical circulating current-free cycloconverter usually gives rise to stator current discontinuities The present paper deals with a simulation method to study the performance of a cycloconverter-fed synchronous motor drive in the presence of interharmonics/subharmonics taking into account the discontinuities in the output current as well as the effect of ripple in the output current on the input current of the cycloconverter. Interharmonics in output phase voltage, output phase current, input supply current, and the field current are estimated and verified with experimental results on a laboratory prototype. The significanct oscillating torque components due to these inter- harmonics are identified in a typical case. The simulation results are useful in power quality studies for such drives and in devising methods for suppression of these interharmonics/subharmonics. [ABSTRACT FROM AUTHOR]

This paper describes methods that control electromagnetic interference noises generated in power converters (pulsewidth-modulation converter and inverter) by using power printed circuit techniques. Two kinds of differential and common-mode noises are generated in motor drive systems. A method is proposed that controls the differential mode noises by symmetrically forming the structure of the positive (P)- and negative (N)-power transmission lines of the power converter using a four-layer printed power circuit technique. Simulations done using the method show that differential mode currents appearing between the terminals of the power converters and the smoothing capacitors can be almost completely eliminated and the common-mode currents are shunted into the artificial ground plane. Another method is also proposed that controls the shunted common-mode currents so as to prevent series resonance phenomena by inserting a damping impedance between the frame of the machine and the ground. Experiments verify that the common-mode currents generated in the motor drive systems can be effectively reduced by the two proposed methods. [ABSTRACT FROM AUTHOR]

In this paper a voltage modulation method based on a triangular carrier wave for the three-phase four-leg voltage source converter is described. The four-leg converter can produce three output voltages independently with one additional leg. The proposed modulation method for the four-leg converter can be implemented with a single carrier by a simple but useful "offset voltage" concept. The method is equivalent to the so called three-dimensional space vector PWM method, but its implementation is much easier. The maximum magnitude of the balanced three-phase voltage and the maximum magnitude of zero sequence voltage, which can be synthesized simultaneously, are derived. The feasibility of the proposed modulation technique is verified by computer simulation and experimental results. These results show that a proposed carrier-based pulse width modulation (PWM) technique can be easily implemented without conventional computational burden. [ABSTRACT FROM AUTHOR]

A new simplified simulation method for the calculation of conducted electromagnetic interference (EMI) caused by switched power converters (SPCs) is presented. EMI simulation in real SPCs presents particular problems due to complex geometry and the wide range of time constants involved. This makes the computation of EMI a complex matter. The method presented here is based on a "source-propagation-path-derived disturbance" simulation process and is specially designed to simplify the mentioned computation problems. In the design of the proposed method, quick and robust simulations were preferred rather than very accurate result. The resulting models allow quite accurate predictions and sensitivity analysis when certain changes in components or layout are introduced. The paper presents two validation cases, where simulation and experimental results of conducted EMI generated by a general-purpose VSI, with different switching patterns and different layout, are compared. [ABSTRACT FROM AUTHOR]