Fault-Tolerant Multilevel Converter to Feed a Switched Reluctance Machine

The switched reluctance machine (SRM) is one of the most interesting machines, being adopted for many applications. However, this machine requires a power electronic converter that usually is the most fragile element of the system. Thus, in order to ensure high reliability for this system, it is fundamental to design a power electronic converter with fault-tolerant capability. In this context, a new solution is proposed to give this capability to the system. This converter was designed with the purpose to ensure fault-tolerant capability to two types of switch faults, namely open- and short-circuit. Moreover, apart from this feature, the proposed topology is characterized by a multilevel operation that allows improvement of the performance of the SRM, taking into consideration a wide speed range. Although the proposed solution is presented for an 8/6 SRM, it can be used for other configurations. The operation of the proposed topology will be described for the two modes, fault-tolerant and normal operation. Another aspect that is addressed in this paper is the proposal of fault detection and diagnosis method for this fault-tolerant inverter. It was specifically developed for a multilevel SRM drive. The theoretical assumptions will be verified through two different types of tests, firstly by simulation and secondly by experiments with a laboratory prototype.

Single phase multifunctional integrated converter for electric vehicles

In this paper, a single phase multifunctional integrated converter is proposed for electric vehicles (EVs) with single stage power conversion. The main objective of the proposed topology is to reduce the weight, size, and cost of the power electronic converter system used in EVs compared to the existing topologies that are already available in the industries. The novelty of the proposed topology includes: (i) single converter for charging, propulsion and regenerative braking; (ii) reduction of number of switches to reduce the switching and conduction losses; (iii) improving the efficiency by reducing the value of inductor; (iv) power factor correction for AC grid; and (v) improving the total harmonic distortion of the grid current. The complete analysis of the various modes of operation of the proposed topology is analyzed and implemented through MATLAB/Simulink software simulation and a power factor of 0.9999 and a current total harmonic distortion (THD) of 2.16% is achieved. The proposed topology is also compared with the existing topologies in terms of number of switches, diodes, inductors and capacitors used.

Simulation of Shield Current in Automotive High Voltage Systems

In automotive high voltage (HV) systems, the switching operation of a power electronic converter causes current and voltage ripple in the frequency range of [10 Hz–150 kHz]. Automotive system engineering provides requirements that define the behaviour of HV components in that frequency range. Shielded HV cables must stand induced current in the frequency range of the ripple. One of the relevant requirements is the maximal current stress of the shielding. Several individually shielded cables are used in automotive HV systems, and these shields influence differential mode disturbance currents, such as the ripple current from the traction inverter. In this work, we provide a model and an analysis of shielded cables integrated into an automotive HV system in relation to system-level design parameters. To fill the gaps of existing research, we focused on two questions: How do design parameters influence the shield current value in the frequency range of the current ripple in a vehicle, and how should a shield and connector system be designed with respect to shield currents over the life-time? We applied analytical and simulative solutions to these problems through a co-simulation approach on the architecture of a real vehicle. The presented approach extends existing research by integrating simulations and vehicle measurements to life-time prediction. Moreover, the proposed methods enable the replacement of the state-of-the-art constant 10 A requirement to a driver profile based predicted shield current requirement on individually shielded HV cables in battery electric vehicles (BEV).

Hybrid Power Electronic Transformer Model for System-Level Benefits Quantification in Energy Distribution Systems

The Hybrid Power Electronic Transformer (HPET) has been proposed as an efficient and economical solution to some of the problems caused by Distributed Energy Resources and new types of loads in existing AC distribution systems. Despite this, the HPET has some limitations on the control it can exert due to its fractionally-rated Power Electronic Converter. Various HPET topologies with different capabilities have been proposed, being necessary to investigate the system benefits that they might provide in possible future scenarios. Adequate HPET models are needed in order to conduct such system-level studies, which are still not covered in the current literature. Consequently, this article presents a methodology to develop power flow models of HPET that facilitate the quantification of controllability requirements for voltage, active power and reactive power. A particular HPET topology composed of a three-phase three-winding Low-Frequency Transformer coupled with a Back-to-Back converter is modeled as an example. The losses in the Back-to-Back converter are represented through efficiency curves that are assigned individually to the two modules. The model performance is illustrated through various power flow simulations that independently quantify voltage regulation and reactive power compensation capabilities for different power ratings of the Power Electronic Converter. In addition, a set of daily simulations were conducted with the HPET supplying a real distribution network modeled in OpenDSS. The results show the HPET losses to be around 1.3 times higher than the conventional transformer losses over the course of the day. The proposed methodology offers enough flexibility to investigate different HPET features, such as power ratings of the Power Electronic Converter, losses, and various strategies for the controlled variables. The contribution of this work is to provide a useful tool that can not only assess and quantify some of the system-level benefits that the HPET can provide, but also allow a network-tailored design of HPETs. The presented model along with the simulation platform were made publicly available.