Electro-mechanical set-up for automated calibration of current transducers

Electro-mechanical concerns of a precision current source for calibration of compensated current transducers are commonly overlooked. Consequently, the calibration setup tends to be bulky and inefficient, particularly if wide frequency range is in question. The proposed source is capable to generate a DC and AC (20 Hz to 6 kHz) current in a range from 0.3 A to 300 A. Its AC part consists a hybrid amplifier, which successfully combines the features of commercially available linear power amplifier and purposely developed switching power converter - amplifier. The supply voltage is fully utilized thanks to the improved clamp mechanism with low inductance and resistance. Special attention is paid to the implemented concept of an analogue/digital controller, which eliminates the nonlinear distortions caused by matching transformers, linking the high-current circuitry of a clamp arrangement to the hybrid amplifier. DC current generation is based on an interleaved operation of buck converter being additionally powered with variable supply voltage.