Quench Protection System of a 1 MW High Temperature Superconductor DC Induction Heater

This paper presents an active quench protection system of the high temperature superconductor (HTS) magnet with iron core in an MW-class direct current (dc) induction heater. The calculated inductance value of the iron core HTS magnet is approximately 98 H. The release of energy stored in the magnet during quench operations is a great challenge for the quench protection system design and is also the focus of this paper. A math model is developed by coupling a Matlab/Simulink model and finite-element method model to study the discharging behavior of the magnet during a quench protection operation. Based on the model, the quench protection system for a 1-MW HTS dc induction heater has been designed. The value of the energy dissipation resistor is calculated. The quench characteristics of the HTS coated conductors with claddings, including copper, brass, and stainless steel, are also investigated. The influence of different claddings on the threshold voltage for quench detection and the response time for quench protection are discussed. A small laboratory-scale dc induction heater prototype was tested to verify the simulation model. The results are of practical significance for setting the parameters of the quench protection system.