Showing papers by "Puqi Ning published in 2014"

Methodology for switching characterization evaluation of wide band-gap devices in a phase-leg configuration

Abstract: Double pulse tester (DPT) is a widely accepted method to evaluate the switching behavior of power devices. Considering the high switching-speed capability of wide band-gap (WBG) devices, the test results become significantly sensitive to the alignment of voltage and current (V-I) measurement. Also, because of the shoot-through current induced by Cdv/dt, during the switching transient of one device, the switching losses of its complementary device in the phase-leg is non-negligible. This paper summarizes the key issues of DPT, including layout design, measurement considerations, grounding effects and data processing. Among them, the latest probes for switching waveform measurement are compared, the methods of V-I alignment are discussed, and the impact of grounding effects induced by probes on switching waveforms are investigated. Also, for the WBG devices in a phase-leg configuration, a practical method is proposed for switching loss evaluation by calculating the difference between the input energy supplied by a dc capacitor and the output energy stored in a load inductor. Based on a phase-leg power module built with 1200 V SiC MOSFETs, the test results show that regardless of V-I timing alignment, this method can accurately indicate the switching losses of both the upper and lower switches by detecting only one switching current.

Development of Advanced All-SiC Power Modules

Abstract: A thermally integrated packaging structure for an all silicon carbide (SiC) power module was used to realize highly efficient cooling of power semiconductor devices through direct bonding of the power stage and a cold baseplate. The prototype power modules composed of SiC metal-oxide-semiconductor field-effect transistors and Schottky barrier diodes demonstrate significant improvements such as low-power losses and low-thermal resistance. Direct comparisons to their silicon counterparts, which are composed of insulated gate bipolar transistors and PiN diodes, as well as conventional thermal packaging, were experimentally performed. The advantages of this SiC module in efficiency and power density for power electronics systems have also been identified, with clarification of the SiC attributes and packaging advancements.

A Phase-Leg Power Module Packaged With Optimized Planar Interconnections and Integrated Double-Sided Cooling

Abstract: A multilayer planar interconnection structure was used for the packaging of liquid-cooled automotive power modules. The power semiconductor switch dies are sandwiched between two symmetric substrates, providing planar electrical interconnections and insulation. Two minicoolers are directly bonded to the outside of these substrates, allowing double-sided, integrated cooling. The power switch dies are orientated in a face-up/face-down 3-D interconnection configuration to form a phase leg. The bonding areas between the dies and substrates, and the substrates and coolers are designed to use identical materials and are formed in one heating process. A special packaging process has been developed so that high-efficiency production can be implemented. Incorporating high-efficiency cooling and low-loss electrical interconnections allows dramatic improvements in systems' cost, and electrical conversion efficiency. These features are demonstrated in a planar bond-packaged prototype of a 200 A/1200 V phase-leg power module made of silicon (Si) insulated gate bipolar transistor and PiN diodes.

A SiC MOSFET based inverter for wireless power transfer applications

Abstract: In a wireless power transfer (WPT) system, efficiency of the power conversion stages is crucial so that the WPT technology can compete with the conventional conductive charging systems. Since there are 5 or 6 power conversion stages, each stage needs to be as efficient as possible. SiC inverters are crucial in this case; they can handle high frequency operation and they can operate at relatively higher temperatures resulting in reduces cost and size for the cooling components. This study presents the detailed power module design, development, and fabrication of a SiC inverter. The proposed inverter has been tested at three center frequencies that are considered for the WPT standardization. Performance of the inverter at the same target power transfer level is analyzed along with the other system components. In addition, another SiC inverter has been built in authors' laboratory by using the ORNL designed and developed SiC modules. It is shown that the inverter with ORNL packaged SiC modules performs better than the inverter having commercially available SiC modules.

Impact of ringing on switching losses of wide band-gap devices in a phase-leg configuration

Abstract: This paper investigates the effects of ringing on the switching losses of wide band-gap (WBG) devices in a phase-leg configuration. An analytical switching loss model considering the parasitic inductance, stray resistance, devices' junction capacitances, and reverse recovery characteristics of the freewheeling diode is derived to identify the switching energy dissipation induced by damping ringing. This part of energy is found to be at most the reverse recovery energy and the energy stored in the parasitics, which is a small portion of the total switching energy. But the parasitic ringing causes interference between two devices in a phase-leg (i.e., cross talk). It is observed that during the turn-on transient of one device, the resonance among parasitics results in high overshoot voltage on the complementary device in a phase-leg. It worsens the cross talk, leading to large shoot-through current and excessive switching losses. The analysis results have been verified by double pulse test with a 1200 V SiC MOSFETs based phase-leg power module.

Forced-Air Cooling System Design Under Weight Constraint for High-Temperature SiC Converter

Abstract: An analytical model has been developed for predicting the forced-air cooling system performance, including a detailed optimization process to minimize the total weight. With a design example in a high-density high-temperature SiC converter, the presented design method was verified through numerical simulations and experiments.

A High Density 250 $^{\circ}{\rm C}$ Junction Temperature SiC Power Module Development

Abstract: A high temperature wirebond-packaged phase-leg power module was designed, developed, and tested. Details of the layout, gate drive, and cooling system designs are described. Continuous power tests confirmed that the designed high-density power module can be successfully operated with 250 °C junction temperature. The power module was further utilized in an all-SiC rectifier system that achieves a 2.78 kW/lb power density.

Power Module and Cooling System Thermal Performance Evaluation for HEV Application

Abstract: To further reduce system costs and package volumes of hybrid electric vehicles, it is important to optimize the power module and associated cooling system. This paper reports the thermal performance evaluation and analysis of three commercial power modules and a proposed planar module with different cooling system. Results show that power electronics can be better merged with the mechanical environment. Experiments and simulations were conducted to help further optimization.

Design & analysis of a novel IGBT package with double-sided cooling

Abstract: Conventional IGBT modules with bonding wires have been suffered from relatively high thermal resistance from junction to case (Rthjc) due to unavoidable single-sided cooling (SSC), and also suffered from uneven current distribution due to unsymmetrical electrical interconnection. A novel IGBT package with double-sided cooling (DSC) geometry was proposed in this paper to overcome these problems. A comprehensive comparative study between the DSC geometry and the SSC geometry has been conducted by simulations. The analytical results demonstrate that the DSC geometry is well superior to the conventional SSC geometry in both electrical and thermal behavior, which predicts a brighter future in various key applications for this emerging package.

All-SiC power module for delta-type current source rectifier

Abstract: To reduce the conduction loss, a novel three-phase current source rectifier, named Delta-type Current Source Rectifier (DCSR), has been proposed in previous paper. This rectifier has delta-type connection on its input side, and its dc-link current can be shared by multiple devices at a time to reduce up to 20% conduction loss. The SiC devices are expected to be the next-generation power devices due to their low conduction and switching losses. In this paper, an all-SiC power module is built to realize a high-density DCSR. The switching performance of the power module is characterized under different operation conditions. Then DCSR is compared with the traditional CSR on both switching speed and switching loss. It is shown that the turn-on speed is accelerated and the switching energy is lower in DCSR. The equivalent parasitic inductance is also lower in DCSR with two paralleled minor commutation loops. The switches can operate at higher switching speed without serious resonance in DCSR.

Comprehensive comparative analysis of two types of commonly-used layouts of IGBT packages

Abstract: A reasonable design of IGBT internal layout is essential to maximize the overall electrical and thermal performance of an IGBT module. For two types of typical layouts of one commonly-used IGBT package with multiple chips connected in parallel, a module-level IGBT equivalent circuit based on chip-level model and accurate interconnection parasitics was constructed in this paper. Comparative simulations have been done to evaluate the advantages and disadvantages of the two types of layouts. The results not only demonstrate the internal electromagnetic & thermal physics which is very hard to be observed in experiments, but also offers a useful guidance for practical application of high power IGBT modules.

A physical modeling method for NPT IGBTs verified by experiments

Abstract: This paper presents a physical modeling method for Non Punch Through (NPT) Insulated Gate Bipolar Transistors (IGBTs). The model is based on the solution to ambipolar diffusion equation (ADE) and can be achieved by engineering software MATLAB or PSPICE. The presented model is verified by experiments. With an interface between the presented model and thermal model of IGBT module, the model can be extended to thermo-electric model easily.

The IGBT module layout design considering the electrical and thermal performance

Abstract: The EV/HEV have a large demand on the IGBT module for the electric motor drive application, and the severe requirements on electric performance, heat dissipation and environment reliability have been put forwards by the customers and the designers. The layout design has direct influence on the electric, electromagnetic interference and heat dissipation performance. The current and temperature balances of the chips in paralleling are the key points of the layout design of IGBT module, and the current differences of the chips leads to imbalance losses and temperature, which cause increasing failure of the chip with highest temperature. In this paper, the transient electric performance and heat dissipation are analyzed respectively, and an electric-thermal coupling module and analyzing method are put forward in this paper. The module not only can be applied to help the layout design, but also used for the system level analysis.

A physical model for high power trench gate IGBTs

Abstract: This paper presents a physical based model for high power trench gate Insulated Gate Bipolar Transistors (IGBTs). The presented model is developed and improved based on Fourier Based Model for IGBTs and power diodes. With the model realization based Matlab Simulink/ Pspice, the model is verified by experiments. Comparing with the conventional IGBT models, the present model gives high speed and accurate results.

Finite Differential Method based Diode and IGBT model in PSPICE

Abstract: Other than the conventional Fourier model, the carrier diffusion equation which retains the distributed nature of charge dynamics in power bipolar devices can be solved by a fast Finite Differential Method in PSPICE. The paper presents the physical basis and the practical consideration of the new modeling approach of PiN Diode and IGBT. The models are also verified by simulations and experiments.

A novel method of gate capacitances extraction for IGBT physical models

Abstract: This paper presents a novel method for gate capacitances extraction of Insulated Gate Bipolar Transistor (IGBT). Gate capacitances are critical for IGBT physical models with accurate turn-on/off transient characteristics. The model is developed and expanded based on the conventional IGBT physical model, and the developed method can be obtained by several simple experiments. The presented method was verified by both IGBT datasheet and professional measurements, and can be used for gate capacitances extraction of Power Metal-Oxide- Semiconductor Field Effect Transistor (MOSFET) and Integrated Gate Commutated Thyristor (IGCT).