In this paper, a novel method is proposed for measuring the current derivative signal with a closed loop Hall-Effect Current Sensor. For obtaining a current differential di/dt signal, an optimal internal signal of the sensor is used, which is proportional to the primary current in the conductor. A differentiator circuit is built in the sensor circuit in order to generate the current differential signal. The components of the differentiator, the low-pass filter and the amplifier are optimized for getting a useful differential output signal. Experiment results show that the developed analog circuit gives an optimal current derivative signal, which corresponds to the differential relation to the sinusoidal primary current, i.e., the phase shift between the both signals is 90deg. The developed circuit can be applied to all kinds of closed loop Hall-Effect current sensors, which are used in electrical drive systems etc.
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