Integrating giant magnetoresistive current and thermal sensors in power electronic modules

Motor drive technology relies on power electronic devices and current sensors for motor control. With active thermal control of IGBT junction temperatures, the reliability and full utilization of power devices can be improved. The intent of this research is to introduce the module-level integration of the GMR field detector as both a current and temperature sensor. The integration effort also includes a new type of flexible planar interconnect to replace conventional wire bonds. The integration goal is to improve the reliability and lower the cost of motor drive systems. Cost and reliability will benefit from a lower parts count and fewer interconnections. Because of the small size, inherent galvanic isolation, temperature dependence, high sensitivity and bandwidth, the magnetoresistive field detector offers promising options for both integrated current and temperature sensing methods. This research describes the operation of GMR, as well as the necessary signal conditioning circuitry for integrated current and temperature sensing. The measured performance attributes of the sensor are also shown. Finally, future plans are discussed which involve combining the current and temperature sensing capabilities with the design of an interconnect layout and observers for junction temperature estimation.