Auto-calibration of Hall effect sensors for home energy consumption monitoring

A technique to improve the accuracy of an electrical energy consumption monitoring system is proposed. This system is based on a network of Hall effect wireless sensors attached to the wire at the output of every circuit breaker in the electrical distribution panel. The readings provided by the Hall effect sensors show significant gain errors due to their sensitivity to the distance between the sensor and the monitored wire. To mitigate these gain errors and increase the system accuracy, the addition of a single high-precision current transformer sensor at the main electrical input is proposed, measuring the total current. This signal is used as the reference signal in a least-mean square algorithm to compensate for the unknown gains of the Hall effect sensors. Experimental results using three prototype Hall effect sensors show that the proposed solution converges within 1.7 min, reducing the average current measurement error from 2.54 to 0.46 A_rms.