Fault Detection and Localization for Limp Home Functionality of Three-Level NPC Inverters With Connected Neutral Point for Electric Vehicles
Anton Kersten, Karl Oberdieck, Andreas Bubert, Markus Neubert, Emma Arfa Grunditz, Torbjörn Thiringer and Rik W. De Doncker; IEEE transactions on transportation electrification, 2019, Vol. 5, No. 2, Pages 416-432, doi: 10.1109/TTE.2019.2899722
This paper deals with the detection of single batteryor inverter switch faults during operation of a common and an
active three-level neutral-point-clamped (NPC) inverter with aconnected neutral point. Here, the main focus lies on the detectionand localization of open-circuit faults of the inverter’s switches. Therefore, a fault detection algorithm, using a current estimator, and two fault localization algorithms, a pulse pattern injection principle and an online adaption of the space vector modulation (SVM), are investigated and verified through simulations and experiments. Also, investigated is how the powertrain can be operated under a fault condition, so that the vehicle can drive with a limited maximum power using an adapted SVM, referred to as “limp home” mode, to the next service station. It is shown, that an active NPC inverter can cope with any single short or open-circuit fault of the inverter’s switches without bringing the vehicle to standstill, whereas a generic NPC inverter loses controllability if an open-circuit fault at an inner switch occurs. Furthermore, both inverter types are able to be operated just with half of the dc-link voltage in case of a failure in one part of the battery.