Accelerated Testing of Module-Level Power Electronics for Long-Term Reliability

Flicker, Jack; TamizhMani, GovindaSamy; Moorthy, Mathan Kumar; Thiagarajan, Ramanathan

doi:10.1109/jphotov.2016.2621339

Cited by 19 publications

(15 citation statements)

References 9 publications

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“…However, central inverters suffered from significant performance degradation under partial shading due to multiple maximum power points and mismatches in PV modules. To solve the partial shading problem, MLPEs (Figure 1b), which include a DC-optimizer and a micro-inverter, were introduced [12][13][14][15][16]. MLPEs are connected to one PV module and harvest optimum power by performing module-level maximum power point tracking (MPPT); this is also known as distributed MPPT (DMPPT) [17][18][19].…”

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confidence: 99%

Advanced MPPT Algorithm for Distributed Photovoltaic Systems

Lee

Yun

2019

Energies

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The basic and adaptive maximum power point tracking algorithms have been studied for distributed photovoltaic systems to maximize the energy production of a photovoltaic (PV) module. However, the basic maximum power point tracking algorithms using a fixed step size, such as perturb and observe and incremental conductance, suffer from a trade-off between tracking accuracy and tracking speed. Although the adaptive maximum power point tracking algorithms using a variable step size improve the maximum power point tracking efficiency and dynamic response of the basic algorithms, these algorithms still have the oscillations at the maximum power point, because the variable step size is sensitive to external factors. Therefore, this paper proposes an enhanced maximum power point tracking algorithm that can have fast dynamic response, low oscillations, and high maximum power point tracking efficiency. To achieve these advantages, the proposed maximum power point tracking algorithm uses two methods that can apply the optimal step size to each operating range. In the operating range near the maximum power point, a small fixed step size is used to minimize the oscillations at the maximum power point. In contrast, in the operating range far from the maximum power point, a variable step size proportional to the slope of the power-voltage curve of PV module is used to achieve fast tracking speed under dynamic weather conditions. As a result, the proposed algorithm can achieve higher maximum power point tracking efficiency, faster dynamic response, and lower oscillations than the basic and adaptive algorithms. The theoretical analysis and performance of the proposed algorithm were verified by experimental results. In addition, the comparative experimental results of the proposed algorithm with the other maximum power point tracking algorithms show the superiority of the proposed algorithm.

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confidence: 99%

Advanced MPPT Algorithm for Distributed Photovoltaic Systems

Lee

Yun

2019

Energies

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“…However, there are also some challenges for PV MIs. First, the MIs are normally cooled by natural convection and they are installed close to the PV module, which means that they can be subjected to a more extreme environment than central inverters typically located in climate controlled environment [6]- [7]. In addition, there is a trend that the MI will be incorporated into the module frame in the future [6].…”

Section: Introductionmentioning

confidence: 99%

“…First, the MIs are normally cooled by natural convection and they are installed close to the PV module, which means that they can be subjected to a more extreme environment than central inverters typically located in climate controlled environment [6]- [7]. In addition, there is a trend that the MI will be incorporated into the module frame in the future [6]. The lifetime/warranty of PV modules is about 25 years, but the inverters have to be replaced every 5 to 10 years [8]; this implies that the lifetime of the MIs needs to be extended to match that of the PV modules.…”

Section: Introductionmentioning

confidence: 99%

“…Schematic of the impedance-source PV microinverter. market is relatively nascent and there is not enough long-term usage data or independent reliability testing; therefore, accelerated testing of PV MI products is conducted in [6] for a long-term reliability prediction. It turns out that the time-tofailure of MIs from different manufacturers deviates significantly due to the design.…”

Section: Introductionmentioning

confidence: 99%

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Wear-Out Failure Analysis of an Impedance-Source PV Microinverter Based on System-Level Electrothermal Modeling

Shen

Chub

Wang

et al. 2019

IEEE Trans. Ind. Electron.

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The wear-out performance of an impedancesource photovoltaic (PV) microinverter (MI) is evaluated and improved based on two different mission profiles. The operating principle and hardware implementation of the MI are firstly described. With the experimental measurements on a 300-W MI prototype and system-level finite element method (FEM) simulations, the electro-thermal models are built for the most reliability-critical components, i.e., power semiconductor devices and capacitors. The dependence of the power loss on the junction/hotspot temperature is considered, the enclosure temperature is taken into account, and the thermal cross-coupling effect between components is modeled. Then the long-term junction/ hotspot temperature profiles are derived and further translated into components' annual damages with the lifetime and damage accumulation models. After that, the Monte Carlo simulation and Weibull analysis are conducted to obtain the system wear-out failure probability over time. It reveals that both the mission profile and the thermal cross-coupling effect have a significant impact on the prediction of system wear-out failure, and the dc-link electrolytic capacitor is the bottleneck of long-term reliability. Finally, the multi-mode control with a variable dclink voltage is proposed, and a more reliable dc-link electrolytic capacitor is employed, which results in a remarkable reliability improvement for the studied PV MI.

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“…Compared with central and string photovoltaic (PV) inverters, microinverters are favorable in low-power applications, due to the capability of module-level maximum power point tracking (MPPT), low installation efforts, easy monitoring and failure detection, and low maintenance cost [1]- [3]. Nevertheless, certain challenges remain for PV microinverters: 1) the efficiency performance of microinverters is relatively low compared with string inverters (e.g., the peak efficiency is around 99.2 % in [4]); 2) there is a trend that microinverters will be incorporated into PV modules in the future [5], [6], which implies that microinverters should be more compact (i.e., high power density and low profile); 3) panel-embedded micro- inverters may be inevitably heated up by the PV panels, accelerating the degradation [7], [8]. Improving the power conversion efficiency and reducing power losses can be an effective way to enhance the energy yield and reliability of PV microinverters [3], [9].…”

Section: Introductionmentioning

confidence: 99%

A 1-MHz Series Resonant DC–DC Converter With a Dual-Mode Rectifier for PV Microinverters

Shen

Wang

Shen

et al. 2019

IEEE Trans. Power Electron.

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The photovoltaic (PV) output voltage varies over a wide range depending on operating conditions. Thus, the PVconnected converters should be capable of handling a wide input voltage range while maintaining high efficiencies. This paper proposes a new series resonant dc-dc converter for PV microinverter applications. Compared with the conventional series resonant converter (SRC), a dual-mode rectifier (DMR) is configured on the secondary side, which enables a twofold voltage gain range for the proposed converter with a fixed-frequency phase-shift modulation scheme. The zero-voltage switching (ZVS) turn-on and zero-current switching (ZCS) turn-off can be achieved for active switches and diodes, thereby minimizing the switching losses. Moreover, a variable dc-link voltage control scheme is introduced to the proposed converter, leading to a further efficiency improvement and input-voltage-range extension. The operation principle and essential characteristics (e.g., voltage gain, soft-switching, and root-mean-square current) of the proposed converter are detailed in this paper, and the power loss modeling and design optimization of components are also presented. A 1-MHz 250-W converter prototype with an input voltage range of 17 V-43 V is built and tested to verify the feasibility of the proposed converter. Index terms-PV microinverter, dc-dc converter, series resonant converter, wide input voltage range, 1-MHz frequency.

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Accelerated Testing of Module-Level Power Electronics for Long-Term Reliability

Cited by 19 publications

References 9 publications

Advanced MPPT Algorithm for Distributed Photovoltaic Systems

Advanced MPPT Algorithm for Distributed Photovoltaic Systems

Wear-Out Failure Analysis of an Impedance-Source PV Microinverter Based on System-Level Electrothermal Modeling

A 1-MHz Series Resonant DC–DC Converter With a Dual-Mode Rectifier for PV Microinverters

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