Dual Three-Pulse Modulation-Based High-Frequency Pulsating DC Link Two-Stage Three-Phase Inverter for Electric/Hybrid/Fuel Cell Vehicles Applications

Abstract

This paper proposes a new modulation technique dual three-pulse modulation (DTPM) to switch dual full-bridge output capacitorless dc/dc converters to develop a pulsating dc link voltage encoding six pulse rectified output information. The pulsating voltage is directly fed to a standard six-pack inverter to develop three-phase ac output voltage. Proposed inverter and modulation are suitable for electric, hybrid electric, and fuel cell vehicles. The absence of the dc link capacitor and DTPM produce pulsating dc voltage that retains the sine-wave information (six- or three-phase rectified output) at the input of three-phase inverter. Inverter devices are modulated for 33% (one-third) of the line cycle and remains in their unique switching state (either on for 33% or off for 33%) and results in average device switching frequency of one-third of switching frequency. This results in 66% savings in switching losses. In addition, devices are not switched when the current through them is at its peak value and total savings in switching loss accounts to be up to 86.7% in comparison with a standard voltage source inverter with sine pulsewidth modulation. This paper presents operation and analysis of the pulsating dc link two-stage inverter controlled by the proposed DTPM at the front end and 33% modulation for the six-pack inverter along with the implementation. Design of the two-stage three-phase inverter has been illustrated. Analysis has been verified through simulation results using PSIM 9.0.4. Experimental results on a lab prototype have been demonstrated to validate the claims and the proposal.