Cryogenic Power Conversion for SMES Application in a Liquid Hydrogen Powered Fuel Cell Electric Vehicle

Cryogenic power conversion for superconducting magnetic energy storage (SMES) application in a liquid hydrogen (LH₂) powered fuel cell electric vehicle (FCEV) is investigated. Principle and operation strategy of the SMES-based onboard energy system are presented for various operational models. A typical FCEV system equipped with a 720-kJ SMES device is conceptually designed and theoretically modeled with a bridge-type cryogenic chopper, which consists of four metal-oxide- semiconductor field-effect transistors (MOSFETs) cooled by low-temperature gas hydrogen (GH₂). The bridge-type cryogenic chopper has higher energy storage and utilization efficiencies than the conventional one because the MOSFETs have much less thermal loss compared with normal operations of the MOSFETs and diodes. Both the start-up time and the regenerative braking time of the FCEV are significantly reduced with the introduction of the SMES. The design and tests of an experimental energy exchange prototype are also presented to verify the feasibility of the proposed high-efficiency SMES system incorporated with the FCEV.