Reduction of EMI coupling between motor and grid connections in a two-level voltage source AC drive
Kaipia, Perttu (2018)
2018
Sähkötekniikka
Tieto- ja sähkötekniikan tiedekunta - Faculty of Computing and Electrical Engineering
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Hyväksymispäivämäärä
2018-09-05
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201808292220
https://urn.fi/URN:NBN:fi:tty-201808292220
Tiivistelmä
Electromagnetic Compatibility (EMC) of a drive must be tested to make its use safe and disturbance free in an electric grid. The noise limits for drives are defined in the standard IEC 61800-03. The coupling between motor and grid cables in a conduit box of a drive bypasses the electromagnetic interference (EMI) filter and make it difficult to fulfil the standard. The goal of this study is to present design guidelines to reduce the coupling between connections with a cost effective way.
The first part of the study discusses the coupling between grid and motor connections theoretically. Based on the theory, the possible solutions for the problem are identified. The identified solutions are investigated with simulations and measurements with a simplified model of the drive connection environment. Assessment criterions are an effectiveness, a feasibility and a cost efficiency. The prototype drive is implemented with the best solutions and it is tested with standardized measurements. The investigated solutions were new placement of drive connections, shielding the drive connections and topology changes in an EMI filter.
The study presents that coupling between motor and grid connections of a drive has a significant impact to the amount of the conducted emissions to the grid. It also presents that proposed solutions reduce the coupling significantly. The most effective and still feasible proposed solutions were to shield the grid connection of the drive with an aluminium or a steel plate and increase the differential inductance in the grid connection. The conducted emissions of the prototype drive with the proposed solutions fulfils the C2 limit of the standard. The solution is estimated to reduce material costs of an EMI filter from 12 to 37 percent with an extra cost of the shield.
The first part of the study discusses the coupling between grid and motor connections theoretically. Based on the theory, the possible solutions for the problem are identified. The identified solutions are investigated with simulations and measurements with a simplified model of the drive connection environment. Assessment criterions are an effectiveness, a feasibility and a cost efficiency. The prototype drive is implemented with the best solutions and it is tested with standardized measurements. The investigated solutions were new placement of drive connections, shielding the drive connections and topology changes in an EMI filter.
The study presents that coupling between motor and grid connections of a drive has a significant impact to the amount of the conducted emissions to the grid. It also presents that proposed solutions reduce the coupling significantly. The most effective and still feasible proposed solutions were to shield the grid connection of the drive with an aluminium or a steel plate and increase the differential inductance in the grid connection. The conducted emissions of the prototype drive with the proposed solutions fulfils the C2 limit of the standard. The solution is estimated to reduce material costs of an EMI filter from 12 to 37 percent with an extra cost of the shield.