R. Knorr

Bio: R. Knorr is an academic researcher from VDO. The author has contributed to research in topics: Electronic circuit & Power electronics. The author has an hindex of 1, co-authored 1 publications receiving 14 citations.

Reliability of High Temperature Inverters for HEV

Abstract: The requirements for the reliability of electronic circuits becomes constantly higher. Therefore, in particular, the strongly growing automotive industry will be influenced, where the number of electronic circuits and the installed power is constantly increasing. Meanwhile for example a hybrid vehicle can be powered by an electrical system with more than 100 kW. The increasing power density of these circuits and the use of the components at higher ambient temperatures lead to the fact that the electronic components will heat up more and more. Additionally the further integration of electronic components requires a higher reliability of single semiconductors. With higher complexity it is more and more a challenge to prove the total reliability of these circuits by accelerated tests. Siemens has been working on the reliability of high temperature applications for years. This article describes a simulation concept, which calculates the crack propagation speed of bond and solder joint connections. Input parameters for the simulation are: Material properties, geometry and different stress types as current loads or temperature. This procedure is demonstrated on the basis of the power electronics for a hybrid drive system.

A comprehensive review on hybrid electric vehicles: architectures and components

Abstract: The rapid consumption of fossil fuel and increased environmental damage caused by it have given a strong impetus to the growth and development of fuel-efficient vehicles. Hybrid electric vehicles (HEVs) have evolved from their inchoate state and are proving to be a promising solution to the serious existential problem posed to the planet earth. Not only do HEVs provide better fuel economy and lower emissions satisfying environmental legislations, but also they dampen the effect of rising fuel prices on consumers. HEVs combine the drive powers of an internal combustion engine and an electrical machine. The main components of HEVs are energy storage system, motor, bidirectional converter and maximum power point trackers (MPPT, in case of solar-powered HEVs). The performance of HEVs greatly depends on these components and its architecture. This paper presents an extensive review on essential components used in HEVs such as their architectures with advantages and disadvantages, choice of bidirectional converter to obtain high efficiency, combining ultracapacitor with battery to extend the battery life, traction motors’ role and their suitability for a particular application. Inclusion of photovoltaic cell in HEVs is a fairly new concept and has been discussed in detail. Various MPPT techniques used for solar-driven HEVs are also discussed in this paper with their suitability.

Performance trends and limitations of power electronic systems

Abstract: In 2003 the Roadmapping Initiative of the European Center of Power Electronics (ECPE) has been started based on a future vision of society in 2020 in order to define the future role of power electronics, and to identify technological barriers and prepare new technologies well in time. In the framework of this initiative a new mathematically supported approach for the roadmapping in power electronics has been developed. As described in this paper the procedure relies on a comprehensive mathematical modeling and subsequent multi-objective optimization of a converter system. The relationship between the technological base and the performance of the system then exists as a mathematical representation, whose optimization assures the best possible exploitation of the available degrees of freedom and technologies. Thus an objective Technology Node of a system is obtained, whereby physical limits are implicitly taken into account. Furthermore, the sensitivity of the system performance with regard to the technological base can be calculated directly and the internal interdependence of Performance Indices directly studied. Accordingly, the improvement in performance achievable by improvements in the technology base can be tested and assessed in advance. Moreover, different system concepts, i.e. circuit topologies, control procedures, etc. can be evaluated and directly compared with regard to achievable efficiency, power density and costs in the form of the associated Pareto Front which defines the boundary of the Feasible Performance Space. If the target performance lies outside the Pareto Envelope of known system concepts and state-of-the-art technologies, a new technology must be employed. The necessity of a technological leap, i.e. the introduction of a Disruptive Technology can thus be recognized at an early stage. This offers an excellent basis for effective roadmapping for various main application areas in power electronics.

Performance trends and limitations of power electronic systems

Abstract: In 2003 the Roadmapping Initiative of the European Center of Power Electronics (ECPE) has been started based on a future vision of society in 2020 in order to define the future role of power electronics, and to identify technological barriers and prepare new technologies well in time. In the framework of this initiative a new mathematically supported approach for the roadmapping in power electronics has been developed. As described in this paper the procedure relies on a comprehensive mathematical modeling and subsequent multi-objective optimization of a converter system. The relationship between the technological base and the performance of the system then exists as a mathematical representation, whose optimization assures the best possible exploitation of the available degrees of freedom and technologies. Thus an objective Technology Node of a system is obtained, whereby physical limits are implicitly taken into account. Furthermore, the sensitivity of the system performance with regard to the technological base can be calculated directly and the internal interdependence of Performance Indices directly studied. Accordingly, the improvement in performance achievable by improvements in the technology base can be tested and assessed in advance. Moreover, different system concepts, i.e. circuit topologies, control procedures, etc. can be evaluated and directly compared with regard to achievable efficiency, power density and costs in the form of the associated Pareto Front which defines the boundary of the Feasible Performance Space. If the target performance lies outside the Pareto Envelope of known system concepts and state-of-the-art technologies, a new technology must be employed. The necessity of a technological leap, i.e. the introduction of a Disruptive Technology can thus be recognized at an early stage. This offers an excellent basis for effective roadmapping for various main application areas in power electronics.

Evaluation methodology and control strategies for improving reliability of HEV power electronic system

Abstract: The reliability prediction of hybrid electric vehicles (HEVs) is of paramount importance for planning, design, control, and operation management of vehicles, since it can provide an objective criterion for comparative evaluation of various configurations and topologies and can be used as an effective tool to improve the design and control of the overall system. This paper presents a mission-profile-dependent simulation model based on MATLAB for quantitatively assessing the reliability of the electric drivetrain of HEVs. This model takes into consideration the variable driving scenarios, dormant mode, electrical stresses, and thermal stresses. Therefore, more reliable and accurate prediction of system reliability has been achieved. The methodology is explained in detail, and the results of reliability assessment based on a series HEV are presented. Based on reliability analysis, two control strategies are proposed to increase the mean time to failure of HEV powertrains: 1) variable dc-link voltage control and 2) hybrid discontinuous pulsewidth modulation scheme. These novel control schemes reduce the power losses and thermal stresses of power converters, and consequently, enhance system reliability. Numerical simulation results verify the benefits of two proposed control strategies in terms of power losses and reliability.

High temperature (≫200°C) isolated gate drive topologies for Silicon Carbide (SiC) JFET

Abstract: Volume and weight limitations for components in hybrid electrical vehicle (HEV) propulsion systems demand highly-compact and highly-efficient power electronics The application of silicon carbide (SiC) semiconductor technology in conjunction with high temperature (HT) operation allows the power density of the DC-DC converters and inverters to be increased Elevated ambient temperatures of above 200degC also affects the gate drives attached to the power semiconductors This paper focuses on the selection of HT components and discusses different gate drive topologies for SiC JFETs with respect to HT operation capability, limitations, dynamic performance and circuit complexity An experimental performance comparison of edge-triggered and phase-difference HT drivers with a conventional room temperature JFET gate driver is given The proposed edge-triggered gate driver offers high switching speeds and a cost effective implementation Switching tests at 200degC approve an excellent performance at high temperature and a low temperature drift of the driver output voltage