Anne Roc'h

Common-Mode DC-Bus Filter Design for Variable-Speed Drive System via Transfer Ratio Measurements

Filters used in electromagnetic interference suppression are often described in literature on drive systems and have become a standard solution in industry. The effect of the commercial off-the-shelf filter depends significantly on how it is installed. A model that includes the installation parameters is made first and then the parameters of the model are extracted by transfer ratio measurements. One possibility is to include the filter on the dc-bus inside the converter. The differential mode DC-bus filter is well known, but the common-mode DC-bus filter has received little attention. Our model is used to show that the common-mode DC-bus filter can achieve the same or even better suppression of common-mode noise by careful design. The transfer ratio is used to evaluate the performance of filter design.

Noise propagation path identification of variable speed drive in time domain via common mode test mode

Electromagnetic Compatibility (EMC) debugging of power electronics systems depends heavily on the experience of specialists due to the complex mechanisms of electromagnetic noise. In this paper, the time domain approach is used instead of the conventional frequency domain method to identify noise propagation path. The proposed test mode switches the upper or lower transistors of the converter legs simultaneously on and off at a 50% fixed duty ratio. It is called common mode test mode. Because there is no significant functional current flowing, the differential mode noise is minimized and the remaining common mode noise and mixed mode noise are maximized. Therefore, the common mode noise in this test method gives its upper boundary of Electromagnetic Interference (EMI) level when the system is normal operated. A motor drive system is measured to show how this test mode works.

New materials for inductors

Traditional materials for coils and common mode chokes are iron and ferrites. Iron has a high saturation level but low permeability, and ferrite has low saturation and high permeability. Nanocrystalline materials are a rather new material with a high saturation and a high permeability. The advantages of this material and applications in EMC will be described.

Hierarchical EMC analysis approach for power electronics applications

In this paper, a novel method for EMI (electromagnetic interference) level prediction is proposed. The method is based on the hierarchical structure of the generation of EMI. That is, the determination of EMI level can be divided into three levels, namely the functional level, the transient level and propagation level. The lower level provides parameter values for the higher level. That makes the analysis to be a single direction chain. In functional level, the working points are obtained. Through transient level analysis, the exact noise sources are determined. In propagation level, the high frequency characteristics in the propagation path are expressed including the variation of parasitic parameters. Frequency analysis can be used to get the EMI level measured in the receiver side rapidly. Because this approach is a straight forward method, the impact of any components can be evaluated immediately instead of doing the simulation from begin to end.

Performance optimization aspects of common mode chokes

Optimization aspects of common mode chokes are presented. These are based on a behavioural model for common mode chokes and its sensitivity study. Results are used to show the influence of the designable parameters on the final performance of the choke placed in a circuit.

New Common Mode EMI filter for motor drive using a fourth leg in the inverter

In this paper, status and recent research trends related to the EMC issues in the variable speed drive system are first reviewed. The existing remedies are discussed in two parts. They are, passive filtering and active filtering. Their merits and demerits are presented. Based on the present solutions, a new common mode suppression approach is proposed. It is called the fourth leg active filter. The principle and benefit are presented. This approach is verified by simulation.

Behavioural Models for Common Mode EMI Filters

EMC is defined as the “ability of an equipment or system to function satisfactorily in its electromagnetic environment without producing intolerable electromagnetic disturbances to anything in that environment”. EMC means that equipment shall be designed and manufactured, in such way that: - The electromagnetic disturbance generated does not exceed the level above which radio and telecommunication equipment or other equipment cannot operate as intended. - It has a level of immunity to the electromagnetic disturbance to be expected in its environment which allows it to operate without unacceptable degradation of its indented use. Electric motors convert electrical power into mechanical power within a motor‐driven system. Electric motors and the systems they drive are the single largest electrical energy consumer, more than twice as much as lighting, the next largest energy consumer, and represent close to 70% of the electrical energy consumption in the industrial sector worldwide [1]. One of the major problems faced by motor drives is Electromagnetic Interference (EMI) which produces unwanted effects on surrounding electronic devices. A traditional way to control EMI in motor drives is the introduction of EMI filters. However a successful and first-time-right design is a ‘done thing’ only to a few experienced designers. The filter though is often not optimized in terms of weight, cost and EMI reduction abilities. Enhancing these performance criteria and supporting a first-time-design at the early stages of development, are the objectives of the work presented in this thesis.