Electroluminescence-based isolated high voltage bus DC current sensor

摘要

Many high voltage sources, used in measurements, have mA order of maximum current. Implementing a miniature and isolated, high side output current monitoring is a challenge. Available isolated current sensing techniques either are aimed for high current, bulky, draw significant power from high voltage source or require isolated power source. Solution proposed draw just 0.04% of power delivered to the load. It is simple, small, provides high voltage isolation, does not require isolated power source, is immune to common mode transients and is suitable for direct microcomputer interfacing. Electroluminescence phenomenon is used: current to be measured is passed through the LED and produced light is registered using photodiode and transimpedance amplifier. Comparison between three optocouplers and readout topologies is given. Sensor is linear within 10% in 1 mA to 30 mA range. Nonlinear approximation was proposed, which extends the measurement range to three decades at 2% errors. (C) 2019 Elsevier Ltd. All rights reserved.