Comparative Study of Switched Capacitor Filter Techniques

T. Kandil, W. Zu, and J. Salmon (Canada)


--- Switched capacitor, active filters, harmonic distortion, hysteresis band current control.


-- In recent years there has been an increasing concern over the introduction of current harmonics in power supply systems owing to the use of nonlinear loads. However, conventional filtering techniques, which use passive filters, are inflexible because they cannot cope with variations in the filtering requirements as the load and system conditions vary. This has resulted in considerable interest in the development of active filtering techniques. This paper presents an assessment of the existing switched capacitor (SC) filter approaches to provide a broad perspective of the SC topology to researchers and application engineers dealing with power quality issues. Furthermore, it presents a brief description of a switched capacitor (SC) technique that was developed to mitigate the drawbacks of the existing SC filters [1]. A simple hysteresis-band-current controller that requires three bi-directional switches is used. Simulation results, based on PSCAD modeling of the proposed compensation scheme are presented. It is shown that the proposed scheme is simple, and capable of maintaining sinusoidal source current for extreme load harmonic distortions. Finally the theoretical analysis is verified by experimental results on a laboratory prototype.

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