High-dynamic exciter system for next-generation high temperature superconducting (HTS) machines

  • High-dynamic exciter system for next-generation high temperature superconducting (HTS) machines

Overview

Field windings used in next-generation superconducting machines are trending towards higher currents (500-1000 A) and lower turn numbers (1-5 H). Consequently the energy stored in these field coils when full-excited is significant, typically > 1 MJ. Both managing the dynamic requirements and protection of the HTS winding is a significant challenge in this context.

In this project a high performance, modular and fail-safe excitation system was designed for next-generation HTS machines. Energy storage was incorporated into the converter for both protection, and to minimise the peak power required to be transferred to the rotor, enabling brushless designs.

High-dynamic exciter system architecture (left) and photographs of developed hardware modules (right): (a) power module, (b) cell balancing, control and isolation module, and (c) energy storage module.

Key features and advantages

  • Modular, multilevel architecture permits the use of low-voltage silicon to support very high currents with low losses.
  • High voltages may be applied to the winding for rapid excitation/de-excitation.
  • High effective switching frequency minimises current ripple and losses in steady state.
  • Integrated energy storage minimises peak power required to be transmitted to the rotor: losses only need to be supplied, enabling brushless systems.
  •  Integrated energy storage permits fail-safe de-excitation and protection of the HTS windings in the case of a fault, without requiring dump loads.

 

Funding

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Duration:

Partners:

  • Siemens
  • Defence Science Technology (DST) Group