Research On Tunnel Magnetoresistance Based Short-Circuit And Over-Current Protection For IGBT Module

As the most widely used power semiconductor device in the field of medium and high voltage power conversion,IGBTs have been widely used in power systems,rail transportation,defense industry,aerospace and other fields.According to industry data,among such devices,power devices such as IGBTs have the highest failure rate.In order to improve the reliability of IGBT-based devices,fast and reliable fault protection for IGBTs is one of the key technologies.This paper presents a short-circuit and over current protection method using a new current sensor—tunnel magnetoresistance(TMR).The resistance of TMR changes with the magnetic flux density and a bridge circuit based TMR can be used for current measurement.A toroid TMR current sensor is firstly proposed to measure the current through IGBT module,and the measured current is compared to references to achieve short-circuit and over current protection.A prototype based on a 1200V/200 A IGBT module is constructed to test the TMR sensor,and experimental results show good measurement accuracy.A 120 A over-current can be detected in 0.77?s.The measured current is also utilized to estimate the DC bus capacitance,experimental results show the maximum estimation error is 0.26%.Next,the TMR sensors are integrated into an IGBT module to expand the application scenario.Calculation method and finite element method(FEM)are proposed to find optimal install locations of the TMR inside a 62 mm IGBT module,and a differential TMR sensor circuit is employed to suppress the interference of adjacent magnetic field.Two 24mm×20mm differential TMR sensors are fabricated and integrated into the IGBT module.The maximum error of the current measured by the sensor is 0.85%,and the measured current is used for short-circuit fault detection,the detection and protection time with threshold current 280 A is 677 ns and 1.23?s respectively.