A first evaluation on the usage of threshold triggered magnetic field sensors for current polarity detection in power conversion systems

Dead-time effects as consequence of the finite switching time of the power switches in power conversion systems have been investigated over a long period. Multiple techniques to eliminate or reduce the dead-time effect have been proposed over the last years. Beside the reduction of the semiconductor switching times, the main idea is to compensate the dead-time effect with the averaged dead-time error-voltage. A more feasible method is based on the knowledge of the phase current polarity, whereas only those semiconductors are active switched, which are able to conduct the current in the actual direction. The resulting commutation strategy, already known as one-step commutation, is suitable for voltage source converters as well as for matrix converters. Beside conventional current sensors, based on the hall-effect, alternative techniques for phase current polarity determination, like the current detection adapted from the forward current-voltage characteristic of the used semiconductors, were described and tested. This paper focusses the potential of threshold triggered magnetic field sensors. Already known as sensor for discrete position and velocity measurement, the pulse wire sensor seems to be suitable as information source for phase current sign. Next to a statistical investigation of the sensor parameter, a proposal for solution, concerning the two basic problems, which accompany the operation of this sensor, is given and verified with experimental results.