Developing MEMS Electric Current Sensors for End-use Monitoring of Power Supply: Part XI - A Nonlinear Error Correction Scheme

Cantilever current sensors (CCS) have received increasing attention recently because of a passive sensing signal correlating to a linear detecting one. When a two-wire appliance is energized however, the distance between the cantilever and the two-wire appliance will become a time variable, which will undermine the above linear relationship. As a result, a nonlinear error is generated, and the measurement accuracy is thus decreased. The larger the amplitude of the cantilever is, the greater the nonlinear error is. In this study, a nonlinear error correction scheme is proposed for the first time without decreasing the sensitivity. Since the nonlinear error can be decreased by increasing the initial distance, while the sensitivity of the cantilever current sensor (CCS) is also decreased. Therefore, it is necessary to compensate for the decrease in the sensitivity by increasing the magnetic induction intensity of the magnet located on the cantilever. When the magnetic induction intensity is increased by 3 times, the initial distance can be increased from 3.5 mm to 5.5mm while maintaining the same sensitivity, and the nonlinear error is decreased from 47% to 32%. The proposed correction scheme is proven to be valid for decreasing the nonlinearity error while maintaining the sensitivity.