Design and Simulation of Fast-Response Filter Based on Locomotive Battery Testing System

The locomotive battery requests its testing system special requirements of excellent DC charge/discharge current which is sensitive to the fluctuation of the voltage. It also needs a fast transfer speed between charge and discharge state. Simple converters without appropriate filter can´t meet the requirement mentioned above. The decay of the Chebyshev filter increases fast with frequency in the stop-band. As a low-pass filter, it avoids the influence to DC component when filtering low order harmonics. It is very benefit in filter design for bidirectional converters. But the traditional theory for filter-order design is based on the decay of not only stop-band but also pass-band, and the latter is not important in DC filter design. This paper extracts an equation of filter-order design for bidirectional converters which care more on the decay in stop band and introduced a method for enhance the response speed between bidirectional transitions. The theoretical deduction and simulation proved the practicability of the methods.