Sensitive DC current imbalance detector and calibration method

A method for detecting current leakage between a power source and a load connected to the power source, the method comprising the steps of:

• providing a first sensing coil between the power source and the load;
• providing a second sensing coil in an opposing position to the first sensing coil between the load and the power source;
• providing a magnetic field sensor in proximity to the first and second sensing coils;
• providing a bias circuit;
• and
• utilizing the bias circuit to place the response of the magnetic field sensor within a preferred response range,
• wherein the step of providing a bias circuit further comprises:
• providing a bias coil;
• providing a bias coil driver to drive the bias coil;
• and
• providing a control unit to control the operation of the bias coil, and
• wherein the step of utilizing the bias circuit further comprises the steps of:
• measuring the magnetic field produced by the bias coil with the magnetic field sensor;
• adjusting the current applied to the bias coil to find the minimum voltage output by the magnetic field sensor;
• adjusting the current applied to the bias coil to find the maximum voltage output by the magnetic field sensor;
• adjusting the current applied to the bias coil to a point at which the voltage produced by the magnetic field sensor is a median value between the minimum voltage output by the magnetic field sensor and the maximum voltage output by the magnetic field sensor;
• and
• applying an initial bias current to the bias coil before the power source is connected to the load.