Inaccurate Switching Loss Measurement of SiC MOSFET Caused by Probes: Modelization, Characterization, and Validation

Zeng, Zheng; Wang, Jin; Wang, Liang; Yu, Yue; Ou, Kaihong

doi:10.1109/tim.2020.3024356

Cited by 24 publications

(4 citation statements)

References 45 publications

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“…Voltage and current probes often exhibit significantly different time delays of their output signals entering an oscilloscope. For SiC MOSFET power modules, not considering these delays most often leads to significant errors in determining switching power losses [26]. To obtain accurate switching power losses, time alignment of voltage and current waveforms is crucial.…”

Section: Proper Time Alignment Of Waveformsmentioning

confidence: 99%

“…In order to determine switching power losses correctly, it is crucial to separate MOSFET channel current component and parasitic capacitances current components and use only the channel current component to determine instantaneous power losses in a tran-sistor. Considering fast switching processes in SiC MOSFETs and the fact that oscilloscope probes often exhibit different output signal delays, proper time alignment of the waveforms obtained with the oscilloscope probes during commutation tests is necessary and also crucial for proper switching power losses determination [26].…”

Section: Introductionmentioning

confidence: 99%

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Bulletin of the Polish Academy of Sciences: Technical Sciences

Zięba,

Rąbkowski

2022

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High-speed switching capabilities of SiC MOSFET power modules allow building high power converters working with elevated switching frequencies offering high efficiencies and high power densities. As the switching processes get increasingly rapid, the parasitic capacitances and inductances appearing in SiC MOSFET power modules affect switching transients more and more significantly. Even relatively small parasitic capacitances can cause a significant capacitive current flow through the SiC MOSFET power module. As the capacitive current component in the drain current during the turn-off process is significant, a commonly used method of determining the switching power losses based on the product of instantaneous values of drain-source voltage and drain current may lead to a severe error. Another problem is that charged parasitic capacitances discharge through the MOSFET resistive channel during the turn-on process. As this happens in the internal structure, that current is not visible on the MOSFET terminals. Fast switching processes are challenging to measure accurately due to the imperfections of measurement probes, like their output signals delay mismatch. This paper describes various problems connected with the correct determination of switching power losses in high-speed SiC MOSFET power modules and proposes solutions to these problems. A method of achieving a correct time alignment of waveforms collected by voltage and current probes has been shown and verified experimentally. In order to estimate SiC MOSFET channel current during the fast turn-off process, a method based on the estimation of nonlinear parasitic capacitances current has also been proposed and verified experimentally.

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Section: Proper Time Alignment Of Waveformsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Bulletin of the Polish Academy of Sciences: Technical Sciences

Zięba,

Rąbkowski

2022

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“…In recent years, wide bandgap (WBG) power devices, such as silicon carbide (SiC) and gallium nitride (GaN), have gained increasing attention and adoption in various fields, including automotive, renewable energy, and consumer electronics [ 1 , 2 , 3 , 4 , 5 ] to provide higher efficiency, switching frequency, and power density [ 6 , 7 , 8 ]. To research the properties and behaviors of WBG devices, the switching current measurement becomes an increasingly important study approach [ 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. Moreover, overcurrent protection is an essential functionality that prevents semiconductor switches from failure, especially in high-power applications at medium voltage levels, where the components are expensive and a failure may lead to catastrophic consequences [ 16 , 17 , 18 ].…”

Section: Introductionmentioning

confidence: 99%

A Nonlinear-Model-Based High-Bandwidth Current Sensor Design for Switching Current Measurement of Wide Bandgap Devices

Chen

et al. 2023

Sensors

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With the growing adoption of wide bandgap devices in power electronic applications, current sensor design for switching current measurement has become more important. The demands for high accuracy, high bandwidth, low cost, compact size, and galvanic isolation pose significant design challenges. The conventional modeling approach for bandwidth analysis of current transformer sensors assumes that the magnetizing inductance remains constant, which does not always hold true in high-frequency operations. This can result in inaccurate bandwidth estimation and affect the overall performance of the current sensor. To address this limitation, this paper provides a comprehensive analysis of nonlinear modeling and bandwidth, considering the varying magnetizing inductance in a wide frequency range. A precise and straightforward arctangent-based fitting algorithm was proposed to accurately emulate the nonlinear feature, and the fitting results were compared with the magnetic core’s datasheet to confirm its accuracy. This approach contributes to more accurate bandwidth prediction in field applications. In addition, the droop phenomenon of the current transformer and saturation effects are analyzed in detail. For high-voltage applications, different insulation methods are compared and an optimized insulation process is proposed. Finally, the design process is experimentally validated. The bandwidth of the proposed current transformer is around 100 MHz and the cost is around $20, making it a low-cost and high-bandwidth solution for switching current measurements in power electronic applications.

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“…An even higher bandwidth would be required to see the details of this edge and measure the switching loss accurately. This problem has been further investigated in [13] with modeling of the switching edge. It is also required that the system is well damped, inadequate damping of the measurement probe will cause measured overshoot and ringing that is not present in the real current.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast Current Shunt (UFCS): A Gigahertz Bandwidth Ultra-Low-Inductance Current Sensor

Shillaber

Jiang

et al. 2022

IEEE Trans. Power Electron.

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In an effort to reduce switching loss, increase switching frequencies and shrink passive component sizes, power device switching times are being pushed into nanosecond and sub-nanosecond intervals. However these fast switching times require high rates of change of current making the power devices susceptible to over-voltage damage from parasitic inductance in the power loop. This presents challenges in measuring the device switching current accurately and in turn makes accurate measurements of device switching energy and stored charge difficult. Traditional current measurement methods either do not have the required frequency response to view the switching edge accurately or have a high parasitic inductance that can significantly alter switching performance and cause damage to the power device. In this paper an active current measurement system is developed. This circuit achieves up to 1.6 GHz bandwidth with zero overshoot. By utilizing mutual inductance cancellation an insertion inductance down to 20 pH has been achieved. The research performed in this paper thereby allows for accurate measurement of device switching loss with minimal power circuit disturbance. The performance of this current measurement is experimentally verified in the frequency domain using a vector network analyzer (VNA) and time domain switching measurements are compared with state of the art current measurement.

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Inaccurate Switching Loss Measurement of SiC MOSFET Caused by Probes: Modelization, Characterization, and Validation

Cited by 24 publications

References 45 publications

Bulletin of the Polish Academy of Sciences: Technical Sciences

Bulletin of the Polish Academy of Sciences: Technical Sciences

A Nonlinear-Model-Based High-Bandwidth Current Sensor Design for Switching Current Measurement of Wide Bandgap Devices

Ultrafast Current Shunt (UFCS): A Gigahertz Bandwidth Ultra-Low-Inductance Current Sensor

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