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We propose pulse-mode dynamic Ron measurement as a method for analyzing the effect of stress on large-scale high-power AlGaN/GaN HFETs. The measurements were carried out under the soft-switching condition (zero-voltage switching) and aimed to minimize the self-heating problem that exists with the conventional hard-switching measurement. The dynamic Ron of the fabricated AlGaN/GaN MIS-HFETs was measured under different stabilization time conditions. To do so, the drain-gate bias is set to zero after applying the off-state stress. As the stabilization time increased from 0.1 μs to 100 ms, the dynamic Ron decreased from 160 Ω to 2 Ω. This method will be useful in developing high-performance GaN power FETs suitable for use in high-efficiency converter/inverter topology design. [ABSTRACT FROM AUTHOR]

In this paper, we present the design and characterization analysis of a cascode GaN field-effect transistor (FET) for switching power conversion systems. To enable normallyoff operation, a cascode GaN FET employs a low breakdown voltage (BV) enhancement-mode Si metaloxide-semiconductor FET and a high-BV depletion-mode (D-mode) GaN FET. This paper demonstrates a normallyon D-mode GaN FET with high power density and high switching frequency, and presents a theoretical analysis of a hybrid cascode GaN FET design. A TO-254 packaged FET provides a drain current of 6.04 A at a drain voltage of 2 V, a BV of 520 V at a drain leakage current of 250 μA, and an on-resistance of 331 mΩ. Finally, a boost converter is used to evaluate the performance of the cascode GaN FET in power conversion applications. [ABSTRACT FROM AUTHOR]

In this paper, we present the design and characterization analysis of cascode gallium nitride (GaN) field effect transistor (FET) for switching power conversion systems. To enable normally-off operation, a cascode GaN FET employs a low breakdown voltage (BV) enhancementmode (E-mode) silicon (Si) metal-oxide-semiconductor FET (MOSFET) and high BV depletion-mode (D-mode) GaN FET. This paper demonstrates normally-on D-mode GaN FET with high power density and high switching frequency and presents theoretical analysis for hybrid cascode GaN FET design. TO-254 packaged FET provides a drain current of 6.04 A at drain voltage of 2 V, BV of 520 V at drain leakage current of 250 uA, and onresistance of 331 mO. Finally, a boost converter is used to evaluate the performance of the cascode GaN FET in power conversion applications. [ABSTRACT FROM AUTHOR]

This paper proposes a fully sensorless driver for a permanent magnet synchronous motor (PMSM) integrated with a digital motor controller and an analog pre-driver, including sensing circuits and estimators. In the motor controller, a position estimator estimates the back electromotive force and rotor position using a sliding-mode observer. In the pre-driver, drivers for the power devices are designed with a level shifter and isolation technique. In addition, a current sensing circuit measures a three-phase current. All of these circuits are integrated in a single chip such that the driver achieves control of the speed with high accuracy. Using an IC fabricated using a 0.18 μm BCDMOS process, the performance was verified experimentally. The driver showed stable operation in spite of the variation in speed and load, a similar efficiency near 1% compared to a commercial driver, a low speed error of about 0.1%, and therefore good performance for the PMSM drive. [ABSTRACT FROM AUTHOR]

This work proposes a highly efficient sensorless motor driver chip for various permanent-magnet synchronous motors (PMSMs) in a wide power range. The motor driver chip is composed of two important parts. The digital part is a sensorless controller consisting mainly of an angle estimation block and a speed control block. The analog part consists of a gate driver, which is able to sense the phase current of a motor. The sensorless algorithms adapted in this paper include a sliding mode observer (SMO) method that has high robust characteristics regarding parameter variations of PMSMs. Fabricated SMO chips detect back electromotive force signals. Furthermore, motor current-sensing blocks are included with a 10-bit successive approximation analog-to-digital converter and various gain current amplifiers for proper sensorless operations. Through a fabricated SMO chip, we were able to demonstrate rated powers of 32 W, 200 W, and 1,500 W. [ABSTRACT FROM AUTHOR]

This paper presents an advanced sensorless permanent magnet (PM) brushless motor controller integrated circuit (IC) employing an automatic lead-angle compensator. The proposed IC is composed of not only a sensorless sinewave motor controller but also an isolated gate-driver and current self-sensing circuit. The fabricated IC operates in sensorless mode using a position estimator based on a sliding mode observer and an open-loop start-up. For high efficiency PM brushless motor driving, an automatic leadangle control algorithm is employed, which improves the efficiency of a PM brushless motor system by tracking the minimum copper loss under various load and speed conditions. The fabricated IC is evaluated experimentally using a commercial 200 W PM brushless motor and power switches. The proposed IC is successfully operated without any additional sensors, and the proposed algorithm maintains the minimum current and maximum system efficiency under 0 N∙m to 0.8 N∙m load conditions. The proposed IC is a feasible sensorless speed controller for various applications with a wide range of load and speed conditions. [ABSTRACT FROM AUTHOR]