Tomas Reiter

Efficiency Optimized Single-Stage Reconfigurable DC/DC Converter for Hybrid and Electric Vehicles

This paper proposes a single-stage reconfigurable topology for an isolated dc/dc converter that supplies the 12 V power net from high voltage (HV) battery pack in hybrid and electric vehicles. The proposed topology solves the problem of reduced converter efficiency in the upper range of HV battery voltages. The converter is based on a zero voltage transition (ZVT) phase shift (PS) full bridge dc/dc converter that is during its operation, depending on the instantaneous value of battery voltage, reconfigured into a push-pull converter. The more efficient ZVT PS configuration covers the upper range of input voltages whereas the hard-switching push-pull configuration covers the lower, less significant range. The ZVT PS configuration, due to tighter voltage range, operates with reduced turn-off losses, significantly decreased circulating current in the freewheeling period as well as improved efficiency of the rectifier stage. The point of reconfiguration is chosen to maximize the average efficiency according to the histogram of HV battery voltage during a typical driving cycle. The operation of the proposed converter and the efficiency improvement are validated experimentally.

Analysis of rectifier topologies for automotive HV to LV phase shift ZVT DC/DC converter

Full bridge phase shift zero voltage transition (ZVT) converter is a standard topology for the automotive high voltage (HV) to low voltage (LV) DC/DC converter. One of the major issues due to the required wide input and output voltage range is the voltage overshoot during the turn-off process of rectifier MOSFET switches. This paper presents a model to simulate turn-off voltage waveforms of switches for different rectifier topologies. Experimental verification on a 3kW converter prototype shows that the model is accurate regarding voltage overshoot value and the oscillation frequency, and that reverse recovery of body diodes has no significant effect on the overshoot. In comparison to two other rectifier topologies, the bridge rectifier has the lowest requirements regarding the switch breakdown voltage, resulting in decreased power losses and eliminating the need for complex clamping/snubber circuits in this specific application.

Mission profile analysis and calorimetric loss measurement of a SiC hybrid module for main inverter application of electric vehicles

This paper evaluates the benefits of replacing the Si diodes of a commercial IGBT module for the main inverter application of an electric vehicle with SiC diodes, leaving the other components of the package and the system unchanged. This will give a direct comparison of Si vs SiC diodes, without giving scope for discrepancies arising out of differences in the packaging, gate-driver circuit etc. The IGBT-module chosen for comparison is a low inductance (8nH) HybridPACK Drive module from Infineon, suitable for high speed switching. A loss model is developed for the modules, and the resulting model is used to investigate the performance for various drive cycles (Artemis, WLTP, NEDC). A calorimetric loss measurement setup is developed for experimental verification of the results.

Soft Switching of IGBTs in Lagging Lag of ZVT Phase Shift DC/DC Converter

Abstract The additional effort to achieve zero voltage transition (ZVT) in the lagging leg of a frequently used ZVT phase shift full bridge converter can be avoided by designing the converter with ‘high speed’ trench fieldstop IGBTs. Thanks to their reduced turn-off but at the same time low turn-on losses, the loss of ZVT in the lagging leg is not anymore critical to converter’s efficiency. Moreover, it can be beneficial due to their improved ‘switching to conduction loss’ ratio. Based on that conclusion, a simple method to maximize their efficiency by minimizing the resonant inductance is proposed.

Single-stage reconfigurable DC/DC converter for wide input voltage range operation in HEVs

This paper proposes a single-stage reconfigurable topology (1) for an isolated DC/DC converter that supplies the 12V power net from a HV-battery pack in hybrid and electric vehicles. The proposed topology solves the problem of reduced converter efficiency in the upper range of HV-battery voltages. The converter is based on the ZVT phase shift full bridge DC/DC converter that is depending on the instantaneous value of battery voltage reconfigured into the push-pull converter. The ZVT phase shift configuration covers upper range of input voltages whereas it is reconfigured into the less efficient, hard- switching, push-pull configuration to cover the lower range. The point of reconfiguration is chosen to maximize the average efficiency according to the histogram of HV-battery voltage during typical driving cycle. Experimental validation of the proposed converter and the efficiency improvement is also presented.