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Abslract: I n this paper, three different inverters: traditional PWM inverter, dc/dc boosted PWM inverter, and Zsource inverter for fuel cell vehicles were investigated. Total switching device power o f each of these inverters was calculated. For purposes of comparison, nu example of the total switching device power, requirement of passive components, efficiency, and the constant power speed ratio of the different inverters powered by the same fuel cell and loaded by the same motor were conducted. This comparison shows that the Zsource inverter is very promising for fuel cell vehicles. 0-7803-6538-

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Abstract-Cascade multilevel inverters have been developed by the authors for utility applications. A cascade M-level inverter consists of (M-1)/2 H-bridges in which each bridge has its own separate dc source. The new inverter: (1) can generate almost sinusoidal waveform voltage while only switching one time per fundamental cycle, (2) can eliminate transformers of multipulse inverters used in conventional utility interfaces and static var compensators, and (3) makes possible direct parallel o r series connection to medium-and high-voltage power systems without any transformers. In other words, the cascade inverter is much more efficient and suitable for utility applications than traditional multipulse and pulse width modulation (PWM) inverters. The authors have experimentally demonstrated the superiority of the new inverter for reactive power (var) and harmonic compensation. This paper will summarize features, feasibility, and control schemes of the cascade inverter for utility applications including utility interface of renewable energy, voltage regulation, var compensation, and harmonic filtering in power systems.Analytical, simulated, and experimental results demonstrate the superiority of the new inverters.