Dead-time compensation method of a 600KW Electrical Balance Of Plant with LC filter for Molten Carbonate Fuel Cell

Abstract

In this paper, we introduce a dead-time compensation method of a 600 KW electrical balance of plant (EBOP) with LC filter for molten carbonate fuel cell (MCFC). LC filter is adopted to reduce harmonics generated by PWM inverter and a filter controller suppresses resonance of LC circuit. Dead-time is inserted to prevent a shoot-through of dc-link and lots of methods for dead-time compensation have been suggested. Most of dead-time compensation schemes use sensed inverter currents processed by low pass filter (LPF) to eliminate undesired noise. A time delay, i.e. a few tens of micro second, caused by LPF generates a relatively large phase delay of sensed current due to high frequency components of a stiff capacitor current which is dominant under lightly loaded condition. If inaccurate sensed currents are used to compensate dead-time, it can distort an output voltage of inverter and even makes LC filter control to be unstable. So, we propose dead-time compensation based on estimated currents instead of sensed currents. Test waveforms are presented to verify the proposed dead-time compensation method and LC filter control.