Miniaturized Current Shunt With High Bandwidth and Low Parasitics for High-Integrated Applications: Electro-Thermal Considerations and Co-Design

The development of current sensors for wide-bandgap (WBG) applications consistently emphasizes high bandwidth, minimal invasiveness, and integration. Despite the meticulous design that enables current shunts to achieve excellent performance with high bandwidth and low parasitics, their inherent bulkiness remains a significant challenge for their integration into high-integrated applications that depend on the high switching speeds of WBG power devices. This study thoroughly investigates and uncovers the trade-off faced by traditional current shunts in balancing miniaturization and high bandwidth. Building upon this understanding, the miniaturized current shunt (MiniShunt) concept is introduced to overcome inherent limitations and achieve both high performance and compact size. To realize this concept, a physical implementation that involves the high-density stacking of multiple coupled transmission lines is presented. Additionally, a thermal network model specifically for the proposed MiniShunt configuration is developed and a comprehensive thermal analysis methodology for the current shunts is established. By applying this methodology to finite element analysis (FEA), the thermal safe operating area (SOA) for the MiniShunt can be determined, further providing valuable insights into its maximum static power dissipation and maximum energy loss. These findings contribute to the development of a highly compact 9×9-mm, 100-mΩ current shunt with an ultrahigh bandwidth of 3 GHz, near-zero parasitic inductance, and a maximum energy loss of 2.0 J at a reference temperature rise limit of 20°C. Extensive experiments conducted in both the frequency and time domains serve to further validate the advantages of the MiniShunt in terms of its miniaturization, integration, ultrafast response, and low invasiveness for future high-integrated power electronics applications.

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