Programmable analog filter in the discrete time for the control of PWM power converters | ||||||
Author(s) | F. Belloni; D. Della Giustina; P.G. Maranesi; M. Riva | |||||
Abstract | The possibility of changing the transfer function of a frequency compensation filter, without modifying its topology, allows to synthesize a feedback regulator of power converters that can be used in a wide variety of applications. By programming the transfer function, the dynamics of the filter can be optimized for each power cell obtaining the desired closed
loop behavior. In principle, the filter can be integrated within the power cell and programmed according to specific needs. Digital filters own this characteristic. Common analog filters, instead, does not offer such a possibility, since their transfer function depend upon their topology. A recursive linear filter in the discrete time, with programmable gains, allows its implementation, offering the same advantages of digital controllers, while avoiding some of their limitations. This paper considers a possible solution based upon switched capacitor circuits, made programmable by multiplying digital to analog converters. In some cases, this solution can be an alternative to digital controls. An analytic model in Z-transform domain and relevant forecasts of frequency responses are provided in the paper. A prototype is employed as external feedback network of a buck converter. Dynamic performances and output voltage transient responses to load variations are shown. |
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Type | Members Only | |||||
Date | Last modified 2012-04-18 by System | |||||
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