In this paper, a novel passive filter installed at PWM inverter output terminals is proposed with an objective of eliminating the common-mode and differential-mode voltage generated by PWM inverter simultaneously. For determining the parameters of filter, the filter transfer function is utilized to achieve a desirable filtering performance. The detailed design procedure of the filter parameters is given. The validity and effectiveness of proposed filter are supported by the simulation and experimental results carried out on 380 V/3 kW induction motor system. Further investigations also demonstrate that the proposed filter permits motor to be connected with inverter through a long cable. The side-effects induced by common-mode and differential-mode voltage such as shaft voltage, bearing current and leakage current are mitigated effectively
[Show abstract][Hide abstract] ABSTRACT: Due to rapid developments of IGBT technology, switching time and frequency are dramatically increased. At higher carrier frequencies, IGBTs induce more capacitive coupled current into a rotor and a stator frame and lead to faster bearing damage. Common mode voltage enables motor to create shaft voltage through electrostatic couplings between the rotor and the stator windings and between the rotor and the frame, and it can caused bearing currents when the shaft voltage exceeds a breakdown voltage level of the bearing grease. Also, high frequency leakage current occurs through stray capacitors between stator winding and the motor frame due to a high rate of the common mode dv/dt at motor terminals which can produce induced shaft voltage. Conducted and radiated Electromagnetic Interference (EMI) emissions are major problems in recent motor drives that produce undesirable effects on electronic devices. In modern power electronic systems, increasing power density and decreasing cost and size of system are market requirements. Switching losses, Harmonics and EMI are the key factors which should be considered at the beginning stage of a design to optimise a drive system. In most of power electronic designs, EMI issues have not been taken into account as one of the main factors; and mitigation techniques for EMI are considered at the last stage of design. This paper presents main EMI issues in a modern AC drive system.
Power Engineering Conference, 2007. AUPEC 2007. Australasian Universities; 01/2008
[Show abstract][Hide abstract] ABSTRACT: The common mode and diﬀerential mode interference propagated through the single-phase power-line cable is usually suppressed with power-line ﬁlters. This kind of ﬁlters is composed by common-mode chokes, X capacitors and Y capacitors to mitigate both the common mode and the diﬀerential mode. However, the present-day power-line ﬁlter design methodologies present some disadvantages: they are designed to be placed in an ideal 50-Ω system and the common mode and diﬀerential mode attenuations are analyzed independently, without considering the mode conversion that can be produced by asymmetries in the power-line ﬁlter, in the power-line network or in the electric device. These facts lead to inaccurate predictions of the power-line ﬁlter behavior and, consequently, the suitable ﬁlter is usually selected by trial and error in long and expensive measurement sessions. In order to improve this situation, this work presents:
- New measurement systems and characterization methodologies to completely model the behavior of power-line ﬁlters, power-line networks and electric devices. To this end, a new characterization methodology is presented: the modal characterization, that conﬁnes the common mode and the diﬀerential mode into a diﬀerent port and provides the information about the propagation of the modal interference, information that can be useful to select the suitable ﬁlter for its mitigation.
- A new methodology to accurately predict the level of conducted emissions that an electric device supplies to the power-line network through its power-line ﬁlter, based on the measurement systems and characterization methodologies presented before. Accurate characterizationswillallowpredictionssimilartotheactualconductedemissions, avoiding long measurement sessions.
- New design methodologies of power-line ﬁlters to achieve optimal and low cost implementations. In a ﬁrst proposal, the components of the power-line ﬁlters are modally characterized to ﬁnd, by computation, the combination that gets the desired ﬁltering response with the minimum number of components. This methodology is further improved by using asymmetric power-line ﬁlters, obtaining an optimal mitigation of the common and diﬀerential mode.
All measurement systems, as well as characterization, prediction and designing methodologies, have been successfully tested on actual devices.
07/2010, Degree: PhD, Supervisor: Joan Ramon Regué
[Show abstract][Hide abstract] ABSTRACT: In this paper, a complete new methodology for the automated design of power-line filters is presented and tested. It is based on rigorous characterizations of power-line-filter components, devices under test, and line-impedance stabilization networks (or power-line networks) by means of S-parameter and interference measurements. The implemented automated design tool is able to find an optimal power-line filter for a given device under test under constraints such as cost or number of components, drastically reducing the design time as compared to the usual trial-and-error practice. Since the features of common-mode chokes are highly dependent on the 50-Hz current levels flowing through them, a measurement system of common-mode chokes under 50-Hz load conditions has also been developed and tested in order to complement the automated design tool. The whole system has been successfully validated by means of experimental measurements.
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