A Non-Invasive Wideband Isolated Current Sensor for High Frequency Power Electronics Applications

1 online resource (123 pages) : PDF

2018

University of North Carolina at Charlotte

With the introduction of new generation of wide-bandgap (WBG) power devices, the size and volume of the modern power electronic converters are getting significantly miniaturized. For effective control of power converters maintaining high efficiency and reliability, loss-less and accurate current measurement is a fundamental pre-requisite. Consequently, traditional current sensing techniques are no longer viable for measurement of currents in high frequency converters. Hence, there is a need to investigate alternative approaches to measure the current which should yield to be wideband, fast, accurate, topology-independent and loss-less. In addition, having higher voltage devices (>30V) using wide-bandgap semiconductors that allow high frequency power converters (>1MHz) necessitates having isolated current sensors.Extraction of the current information is one of the major challenges in high frequency power electronics. Typically, high frequency current passing through a printed circuit board (PCB) trace induces a highly non-uniform magnetic field which varies as a function of frequency and position relative to the current trace. This non-uniform distribution of magnetic fields limits the effective detection bandwidth of most magnetic field transducers used as isolated current sensors such as Hall-effect and Magnetoresistor (MR) sensors. However, the non-uniform magnetic fields can be normalized by means of Magnetic Field Concentrators (MCON) using conductive materials. Smart implementation of the MCON by selecting the best material having specific thickness and dimensions can result in a much more uniform magnetic distribution through the sensor which consequently improves the effective detection bandwidth of current sensing in power converters.To meet the demand for high bandwidth loss-less current sensors having fast response time, we have proposed a non-invasive wideband current sensing scheme for high frequency power electronics applications. The proposed current sensor utilizes two different current sensing techniques having complementary characteristics to achieve a very wideband performance - a Magnetoresistor (MR) as the primary sensing element and a Rogowski coil as the secondary sensing element. A magnetic field concentrator (MCON) is also utilized around the sensors to normalize the magnetic field distribution over the wide frequency range as well as to achieve shielding for the sensor from outside interfering fields. The proposed current sensor provides an alternative hybrid current sensing solution having wideband performance while still maintaining desired characteristics such as loss-less and isolated sensing.

doctoral dissertations

Electrical engineering

Ph.D.

Electrical Engineering

Parkhideh, Babak

Cox, Robert
Chowdhury, Badrul
Sonin, Isaac

Thesis (Ph.D.)--University of North Carolina at Charlotte, 2018.

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Nibir_uncc_0694D_11804

http://hdl.handle.net/20.500.13093/etd:262