Pengju Sun

An Active Clamp High Step-Up Boost Converter with a Coupled Inductor

An active clamp high step-up boost converter with a coupled inductor is proposed in this paper. In the proposed strategy, a coupled inductor is adopted to achieve a high voltage gain. The clamp circuit is included to achieve the zero-voltage-switching (ZVS) condition for both the main and clamp switches. A rectifier composed of a capacitor and a diode is added to reduce the voltage stress of the output rectifier diode. As a result, diodes with a low reverse-recovery time and forward voltage-drop can be utilized. Since the voltage stresses of the main and clamp switches are far below the output voltage, low-voltage-rated MOSFETs can be adopted to reduce conduction losses. Moreover, the reverse-recovery losses of the diodes are reduced due to the inherent leakage inductance of the coupled inductor. Therefore, high efficiency can be expected. Firstly, the derivation of the proposed converter is given and the operation analysis is described. Then, a steady-state performance analysis of the proposed converter is analyzed in detail. Finally, a 250 W prototype is built to verify the analysis. The measured maximum efficiency of the prototype is 95%.

Junction temperature management of IGBT module in power electronic converters

Abstract IGBT power module is the key component of the power electronic converter, but it has the lowest reliability. The junction temperature is the crucial factor which affects power module’s reliability. To some extent, the power handling capability of the converter depends on the thermal stress of the power module. Thermal management is an effective method to improve the reliability of power device, as well as enhance the power capability. For this purpose, this paper introduces the reliability design to the power converter’s traditional compensation controller design for the first time. A new concept of generalized dual-loop controller, which includes temperature control loop and electric power control loop, is proposed. The reliability and stability of the system are both considered, with the help of the hybrid controller, the power converter can operate steadily with higher reliability. The novelty of this paper is to improve the thermal control method of carrier frequency adjustment through experimental implementation during the full life cycle of the converter. The target is to control the temperature variation to be almost a constant value as well as extend the lifetime of the converter. IR sensor is used to measure the chip temperature of the unpackaged IGBT module. The temperature variation and the average temperature are all considered in thermal management, from the reliability improvement point of view. At last, the idea is digital implemented based on a varying load of power inverter system with real-time measurement of the chip’s surface temperature.

Junction Temperature Prediction of IGBT Power Module Based on BP Neural Network

In this paper, the artificial neural network is used to predict the junction temperature of the IGBT power module, by measuring the temperature sensitive electrical parameters (TSEP) of the module. An experiment circuit is built to measure saturation voltage drop and collector current under different temperature. In order to solve the nonlinear problem of TSEP approach as a junction temperature evaluation method, a Back Propagation (BP) neural network prediction model is established by using the Matlab. With the advantages of non-contact, high sensitivity, and without package open, the proposed method is also potentially promising for on-line junction temperature measurement. The Matlab simulation results show that BP neural network gives a more accuracy results, compared with the method of polynomial fitting.

Thermal network parameter identification of IGBT module based on the cooling curve of junction temperature

The thermal network parameters of IGBT module are wildly used for reliability evaluation, lifetime calculation, health monitoring, and predictive maintenance. Commonly used thermal network parameter identification methods include the finite element method (FEM) and the curve fitting of thermal impedance (Zth) method. The former method calculates directly using the IGBT geometric structure and material properties, but it is difficult to consider the aging procedure of IGBT. The curve fitting method mainly depends on constant loss constraints, which is difficult to guarantee in practical application. In this paper, we propose an IGBT thermal network parameter identification method using the measured junction temperature cooling curve in the procedure of converter shutdown. The relationship between the time constants of junction temperature curve and the thermal network parameters is investigated. We show that the RC parameters can be identified in two different cooling conditions. The obtained RC parameters are in good agreement with the results by JESD51-14 method. The proposed method is simple and easy to implement. In particular, it does not need to consider the dissipation loss of IGBT before shutdown, and is suitable for RC thermal parameter quasi-online measurement.

Lifetime estimation for IGBT modules in wind turbine power converter system considering ambient temperature

Abstract Power semiconductors in the wind turbine power converter system suffer from two-scale thermal loadings, the fundamental frequency thermal cycling caused by the output frequency of converter and the low frequency thermal cycling due to the variation of long-term wind speed. These two-scale thermal loadings introduce different consumed lifetimes. Accurate lifetime estimation in the wind power application is desired for reliability prediction and health management. This paper adopts the Bayerer lifetime model to evaluate the consumed lifetime of power semiconductors in wind power converter systems based on a numerical junction temperature calculation method. Lifetime estimation can be improved by taking into account the ambient temperature. Studies show that fluctuations of the ambient temperature increase the consumed lifetime due to the low frequency thermal cycling, but have little effect on the consumed lifetime due to the fundamental frequency thermal cycling. Our results also show that the consumed lifetime due to fundamental frequency thermal cycling mainly falls on the high wind speed area, whereas the consumed lifetime due to low frequency thermal cycling is clustered in the area due to large low frequency junction temperature fluctuations. The resulting distribution characteristics can be used in the thermal management for reliability improvement.

Monitoring chip fatigue in an IGBT module based on grey relational analysis

Abstract Chip fatigue inside an insulated gate bipolar transistor (IGBT) module is a kind of incipient defect. It can be considered as an indication of the impending failure, and is utmost important for the safe operation of IGBT modules. Therefore, monitoring the chip fatigue is one of crucial measures to enhance the operating reliability of IGBT modules. This paper presents a prognostic approach for the chip fatigue based on grey relational analysis (GRA), which uses dynamic change of the gate voltage as precursor parameter. This dynamic change is caused by aging of the intrinsic parasitic elements involved in gate drive circuit, which reflect the advent of chip fatigue. Grey relational grade is employed in this proposed prognostic approach to quantify the extent of those dynamic changes by little data, and find out potential chip fatigue. Then the operator would have a chance to schedule the maintenance and replace defective IGBT modules timely to avoid wear out. So it can be seen as a prefault diagnostic method. Finally, a confirmatory experiment is also carried out, and the correctness of the proposed approach is verified.

Condition Monitoring IGBT Module Bond Wires Fatigue Using Short-Circuit Current Identification

Finding and replacing the defective insulated-gate bipolar transistor (IGBT) module timely by monitoring the ageing state of IGBT can improve the reliability of a power converter and reduce the loss caused by IGBT failure. A method for detecting the condition of bond wires in IGBT module by identifying the short-circuit current of IGBT module is presented in this paper. It is based on the fact that parasitic parameters of IGBT module are affected by the local damage induced by ageing over time, and these changes can be easily detected by monitoring the difference of short-circuit current. The study results indicate that short-circuit current of IGBT module decreases with module ageing over time, and the difference of short-circuit current caused by junction temperature is much smaller than that caused by bond wires fatigue on a specific gate driving voltage. Therefore, the IGBT module in the power converter can be diagnosed by detecting the difference of short-circuit current without considering the effects of junction temperature. Finally, a confirmatory experiment is carried out, and the correctness of the method proposed in this paper is verified.

A hybrid modulation method for lifetime extension of power semiconductors in wind power converters

Pulse width modulation (PWM) techniques can be classified into continuous pulse width modulation (CPWM) and discontinuous pulse width modulation (DPWM) types. The switching loss of power devices in DPWM converters is lower than that in CPWM converters. Lower loss could reduce the junction temperature fluctuation in converters of wind turbine generator system (WTGS) and may result in longer power devices lifetime. However, employing DPWM scheme under all WTGS operation conditions will lead to power quality concern. To solve this problem, a new hybrid modulation scheme which combines the CPWM and DPWM methods for WTGS converters is presented in this paper. In the presented hybrid modulation method, two modulation schemes are switched back and forth according to the wind speed in the wind farm site. The performance of the presented modulation scheme is verified and compared with that of other PWM schemes through a case study of 1.2 MW WTGS in long-term mission profiles. The results show that the lifetime of power devices with the presented hybrid approach is longer than that with the CPWM, and is shorter than that with the DPWMs. Moreover, the power quality of the power converters with the hybrid modulation scheme can be guaranteed in all operation conditions, which may not be achieved with DPWMs.

Control of IGBT junction temperature in small-scale wind power converter

In wind power converters, the junction temperature of the power module is the crucial factor which affects its reliability. This paper developed a comprehensive thermal management strategy to improve the operational reliability of a small-scale wind power converter. Theoretical analysis, simulation and frequency conversion experiment are given to verify the effectiveness. And the specific goal of thermal management has also been investigated. Firstly, the idea of thermal management which combines the reliability as well as the stability is introduced. Then, in order to smooth the temperature fluctuations, the flexible continuous adjustment of the switching frequency and the exterior thermal management method are applied. A FPGA based temperature-controlled oscillator and fan speed regulator are designed. Lastly, numerical simulation was carried out to verify the correctness of the proposed thermal smooth control method. Meanwhile, the rain-flow counting method and Miners linear cumulative damage law are applied to check whether the goal is achieved or not, from the system reliability point of view. This study shows that the thermal management is not mean only to suppress the fluctuation of the IGBT junction temperature as much as possible. But full consideration should be given for both the temperature fluctuation as well as its average value, so as to improve the reliability and to extend the lifetime of the power converter.

Corrigendum to “Junction temperature management of IGBT module in power electronic converters” [Microelectron. Reliab. 54 (2014) 2788–2795]

http://dx.doi.org/10.1016/j.microrel.2014.12.003 0026-2714/ 2014 Elsevier Ltd. All rights reserved. DOI of original article: http://dx.doi.org/10.1016/j.microrel.2014.07.002 ⇑ Corresponding author at: Room 6217-1, College of Electrical Engineering, Campus A, Chongqing University, No. 174, Shazheng Road, Shapingba District, Chongqing 400044, China. Tel.: +86 13509490203. E-mail address: allen_wjk@163.com (J. Wu). Luowei Zhou, Junke Wu ⇑, Pengju Sun, Xiong Du