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In this paper, an iterative algorithm is proposed to retrieve the particle-size distributions via Fraunhofer diffraction. A dual integral inversion was proposed in our previous work, the inversion is robust and generates precise particle sizing, if the diffraction pattern can be accurately captured. In real applications, the pattern can only be partially detected, and the inversion fails to reconstruct the size distributions in detail. However, the results of the inversion can be used to produce an initial estimate. Then, a simulated diffraction pattern was generated from the estimated particle sizes. The deviation between the measured pattern and the simulated one was deduced to correct the results of particle sizing. The corrections can be achieved in an iterative approach, and the particle-size distribution was updated subsequently. The iteration stopped once the deviation was below the target value. Both simulation and experiment were conducted to validate the feasibility and effectiveness of the proposed algorithm. The results demonstrate that the size distribution from the proposed algorithm agrees well with the original phantoms for both noise-free and noise-contaminated data. [ABSTRACT FROM AUTHOR]

The switching transient properties from the switching power semiconductor gate side are sensitive to the device's junction temperature (Tj). Real-time Tj sensing methods based on gate drive switching transient properties have been investigated on silicon MOSFET and silicon IGBT, with a conventional push–pull-type gate drive, under fixed dc-bus voltage. In this paper, this method is applied to silicon-carbide (SiC) MOSFET. The Tj sensing methods are evaluated with different types of gate drive topologies. By implementing the SiC MOSFETs into an H-bridge inverter, the effect of dc-bus voltage for the Tj sensing method is investigated. Different “gate drive−semiconductor” dynamic models are built, including gate drive output power stage, gate drive parasitics, SiC MOSFET intrinsic parameters, and PCB parasitics. Experimental results are compared with circuit LTSpice model simulation. The device vertical temperature contours are evaluated. Suitable circuitry for Tj sensitivity extraction is provided. [ABSTRACT FROM PUBLISHER]

Switching power semiconductor online junction temperature Tj sensing is essential for device switching performance evaluation, device switching control, and device lifetime optimization. The contribution of this paper is a detailed evaluation of the implementation issues (including circuit invasiveness, hardware integration, signal processing, and so forth) of different online Tj sensing methods. This paper includes Tj sensing methods based on device power dissipation, Tj sensing methods based on the “sensor-on-die technology,” Tj sensing methods based on device on-state analysis, and Tj sensing methods based on device switching transients. Advantages and limits of these methods are also provided. [ABSTRACT FROM AUTHOR]

Junction temperature sensing for high-bandwidth power MOSFET junction temperature protection is usually achieved on the power converter’s high power side, by directly monitoring the power switches with additional temperature detectors. This requires special considerations for high voltage, high current, high temperature, and EMI protection. This paper presents a new method applied on the power converter’s low power side (MOSFET gate drive) so that junction temperature sensing can be integrated into MOSFET gate drive. For the purpose of demonstrating MOSFET junction temperature sensing, a push–pull gate drive is applied to a switching current divider circuit. The gate drive turn-on current transient waveform is used for MOSFET junction temperature estimation. A “gate drive-MOSFET” switching dynamic model is implemented indicating the mechanisms of MOSFET gate drive output dynamics. Modeling includes gate-drive push–pull output, gate drive output parasitics, power MOSFET intrinsic parameters, PCB parasitics, and load parasitics. LTSpice simulation of this model is studied and compared with experimental results. [ABSTRACT FROM AUTHOR]

Junction temperature (Tj) sensing requirements for fast MOSFET junction temperature control and high-power fast switching power converter protection are not easily met with nonintrusive techniques. This paper presents a noninvasive circuit-model-based sensing method suitable for a high-bandwidth hard-switching converter power MOSFET junction temperature estimation without any additional temperature detector. For the purpose of demonstrating MOSFET junction temperature sensing, a chopper circuit is used. The ringing superimposed with a circuit load current is used for MOSFET junction temperature estimation. A “gate drive- RDS-on-L-C” resonant model is implemented, indicating the mechanism of power MOSFET turn-on dynamics. Modeling includes the gate-drive output parasitics, power MOSFET intrinsic parameters, PCB parasitics, and load parasitics. To evaluate the methodology, LTspice simulation and experimental results are studied. [ABSTRACT FROM PUBLISHER]