A Compact Magnetoresistance-Rogowski Hybrid Sensor for Multichip Online Current Sensing in Press-Pack Power Module

Press-pack power module has recently become a crucial component for large-current and high-power facilities. Several semiconductor chips are connected in parallel inside the module. Due to the complex coupling of electrical, thermal, and mechanical fields within the device, the imbalance in pressure distribution and heat dissipation capacity may lead to uneven current distribution and potential overloading of certain chips. Chip-level online current sensing is an effective approach to provide current monitoring and fault diagnosis. However, it is difficult to accomplish high-accuracy chip-level current sensing considering the bandwidth and size of sensors. In this article, a compact hybrid sensor consisting of anisotropic magnetoresistance (AMR) and Rogowski coil for chip-level online sensing is proposed. Rogowski coil possesses the advantage to measure the high-frequency current and AMR sensor is used to expand the dc and low-frequency bandwidth of the coil. The principle and the design of Rogowski coil and AMR sensor are analyzed. The magnetic fields generated by multiple chips tend to couple with each other. To enhance the accuracy of AMR, a decoupling matrix is calculated to decouple the crosstalk of magnetic fields. The implementation of the hybrid sensor is proposed. The hybrid sensor is used to measure the chip-level current of a press-pack insulate gate bipolar transistorv (IGBT) in a buck converter whose frequency is 40 kHz. The output of hybrid sensor is verified by the commercial current transducer. The result shows that the hybrid sensor achieves chip-level current sensing for press-pack power module, with a measurement bandwidth ranging from dc to 30 MHz, an accuracy of 2% and excellent linearity.