A Three Phase Interleaved High- Frequency Inverter with Single-Reference Eight-Pulse-Modulation Technique (SREPM) For Fuel Cell Vehicle Applications
T.RAMACHANDRA RAO, M.SIVA REDDY
Electric vehicles, fuel cell vehicles, high frequency, six-pulse modulation, three-phase four leg inverter.
This paper presents a three phase four leg inverter with neutral connected to load. The inverter hybrid modulation technique consisting of singe-reference eight-pulse-modulation (SREPM) for front-end dc/dc converter and 33% modulation for three-phase inverter. In proposed SREPM to control front-end dc/dc converter, high frequency (HF) pulsating dc voltage waveform is produced, which is equivalent to six-pulse output at 6× line frequency (rectified 6-pulse output of balanced three- phase ac waveforms) and the two more pulses to neutral connection leg. It reduces the control complexity owing to single-reference three-phase modulation as compared to conventional three-reference three-phase SPWM And also the harmonic content in currents. In addition, it relives the need of dc-link capacitor reducing the cost and volume.. It needs only33% (one third) modulation of the inverter devices to generate balanced three-phase voltage waveforms resulting in significant saving in (at least 66%) switching losses of inverter semiconductor devices. At any instant of line cycle, only two switches are required to switch at HF and remaining switches retain their unique state of either ON or OFF. Drop in switching loss accounts to be around 86.6% in comparison with a standard voltage source inverter (VSI) employing standard three- phase sine pulse width modulation. This paper explains operation and analysis of the HF two-stage inverter modulated by the proposed novel modulation scheme. Analysis has been verified by simulation results.