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.