Load Current estimation in single-phase inverters using D.C. line current

Single Phase Inverters are commonly used in computer power supply units. To implement the current control loop, Hall sensors at the load terminals are generally used. In this paper, the Load Current Sensor is substituted by a high bandwidth d.c. line current monitor. The actual load current of any waveform is estimated by monitoring the d.c. line current. A current sensing resistor along with an operational amplifier may be used for this purpose. The instantaneous load current estimator is almost at the ground potential and is not subjected to any large voltage swings. For implementing a sinusoidal trajectory tracking current controller, the output from the estimator is used as the feed back signal. The scheme was simulated in PSPICE and MATLAB. The Digital Controller for the Inverter was implemented using the FPGA chip EP1C3T100C7.