Power Measurement and Current Feedback in a Resonant DC Link Inverter

摘要

Resonant dc link (RDCL) inverters employ zero-voltage switching to reduceswitching loss in power converters and to improve their efficiency. The project uses current feedback to eliminate zero-crossing failure in RDCL inverters. The zero-crossing failure is corrected by sensing the load current and feeding it back to control the operation of the link-shorting switch. The operation of the control scheme is first established by simulating the converter using computer simulation. The current feedback is implemented on an experimental RDCL inverter. The inverter is built using current-sensing Power MOSFETs that provide signals proportional to the current. The control signals to the inverter switches and the outputs from the current sensing MOSFETs are fed back to control the frequency and the duty cycle of the input to the link-shorting switch. The addition of proper level of current feedback is found to reduce the minimum link voltage to zero. The waveforms of the link voltage with and without current feedback are recorded and studied using a digital storage oscilloscope. The power loss in the RDCL inverter is also computed using the oscilloscope and it is seen the addition of current feedback results in a higher efficiency for the converter. jg.