Abstract-ThisHowever, IGBTs are known to be prone to failure [12]-[19], and the situation would only get worse when operating in the harsh environment beneath the bonnet of an electric vehicle. ) have received much attention by the industry. Nonetheless, when the bonding using these new technologies fails, the entire device will be damaged with catastrophic consequences.Without a doubt, the detection of an IGBT fault prior to (prognosis) or even after (diagnosis) its occurrence is of critical importance to the healthy operation of the system. Conventional vehicles are equipped with an on-board diagnostic (OBD) system which can detect a "happened" fault and flag it up to the driver of the vehicle. In the event of an IGBT failure, the detection must be quick enough (ideally, less than 10 μs) to prevent a fault from propagating, which places a limit on the hardware setup

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System efficiency and cost effectiveness are of critical importance for photovoltaic (PV) systems. This paper addresses the two issues by developing a novel three-port DC-DC converter for stand-alone PV systems, based on an improved Flyback-Forward topology. It provides a compact single-unit solution with a combined feature of optimized maximum power point tracking (MPPT), high step-up ratio, galvanic isolation and multiple operating modes for domestic and aerospace applications. A theoretical analysis is conducted to analyze the operating modes followed by simulation and experimental work. The paper is focused on a comprehensive modulation strategy utilizing both PWM and phase-shifted control that satisfies the requirement of PV power systems to achieve MPPT and output voltage regulation. A 250 W converter was designed and prototyped to provide experimental verification in term of system integration and high conversion efficiency. Index Terms-DC-DC power conversion, maximum power point tracking, phase shift, photovoltaic power system, voltage control. I. INTRODUCTION OLAR energy is a primary and renewable source of energy. As the cost of photovoltaic (PV) panels is seen to reduce continuously, PV-based power generation is gaining in

Abstract-This paper presents a novel real-time power device temperature estimation method which monitors the power MOSFET's junction temperature shift arising from thermal aging effects and incorporates the updated electrothermal models of power modules into digital controllers. Currently, the real-time estimator is emerging as an important tool for active control of device junction temperature as well as on-line health monitoring for power electronic systems but its thermal model fails to address the device's ongoing degradation. Because of a mismatch of coefficients of thermal expansion between layers of power devices, repetitive thermal cycling will cause cracks, voids and even delamination within the device components, especially in the solder and thermal grease layers. Consequently, the thermal resistance of power devices will increase, making it possible to use thermal resistance (and junction temperature) as key indicators for condition monitoring and control purposes. In this paper, the predicted device temperature via threshold voltage measurements is compared with the real-time estimated ones and the difference is attributed to the aging of the device. The thermal models in digital controllers are frequently updated to correct the shift caused by thermal aging effects. Experimental results on three power MOSFETs confirm that the proposed methodologies are effective to incorporate the thermal aging effects in the power device temperature estimator with good accuracy. The developed adaptive technologies can be applied to other power devices such as IGBTs and SiC MOSFETs, and have significant economic implications.

Abstract -This paper proposes a new thermography-based maximum power point tracking (MPPT) scheme to address photovoltaic (PV) partial shading faults. Solar power generation utilizes a large number of PV cells connected in series and in parallel in an array, and which are physically distributed across a large field. When a PV module is faulted or partial shading occurs, the PV system sees a non-uniform distribution of generated electrical power and thermal profile, and the generation of multiple maximum power points (MPPs). If left untreated, this reduces the overall power generation and severe faults may propagate resulting in damage to the system. In this paper, a thermal camera is employed for fault detection and a new MPPT scheme is developed to alter the operating point to match an optimized MPP. Extensive data mining is conducted on the images from the thermal camera in order to locate global MPPs. Based on this, a virtual MPPT is set out to find the global MPP. This can reduce MPPT time and be used to calculate the MPP reference voltage. Finally, the proposed methodology is experimentally implemented and validated by tests on a 600W PV array.