Search

Fault tolerance in electric motor drives has been extensively studied due to their widespread usage in safety-critical applications, including more/all-electric aircraft and electric vehicles. Switched reluctance motors (SRMs) are renowned for their high robustness and excellent fault tolerance. However, they are not immune to faults, and a potential fault in any part of the motor drive could have serious implications for the system, even may lead to unexpected shutdown if the fault is not promptly remedied. The power converter is a key component and the most vulnerable to failure, as reported for 35% of the drive faults. Fault tolerance has typically been achieved through a combination of hardware and software reconfigurations. However, due to the simple structure of the standard asymmetrical half-bridge converter, hardware reconfiguration is more commonly used to remediate converter faults. Consequently, fault tolerance adds cost and complexity to a standard SRM drive system. This article presents an instructive survey of the recent research on fault-tolerant SRM drives. Moreover, the postfault performance, implementation costs, and fault-tolerant capabilities of advanced fault-tolerant converters are systematically quantified, evaluated and compared. Finally, the article is concluded with an investigation on the future research trends in fault tolerance in SRM drives.

Visible light communications (VLC) is a promising technology that combines the ubiquity of illumination devices with broadband communication to provide connectivity. The most recent VLC communication standards specify orthogonal frequency division multiplexing (OFDM) as the underlying modulation due to its spectral efficiency and compatibility with existing broadband modems. However, a key challenge remains in realizing VLC modulators capable of generating OFDM signal compatible with the primary illumination function, while ensuring the efficacy of the luminaires. In this paper, a novel method is proposed to integrate OFDM modulation into a switching power supply. Commutating diodes in the DC/DC converter are replaced by light-emitting diodes (LEDs) which are used for communication while the larger illumination string of LEDs is left unmodulated preserving the quality of illumination and luminaire lifetime. Biasing the switching MOSFET to its saturation region during its off states allows for the MOSFET to act as an amplifier, amplifying the OFDM communication signal and injecting it to the light-emitting commutating diode (LECD). As a result, energy efficient LED drivers capable of OFDM signal transmission are realized. Both simulation and experimental results are provided to demonstrate the feasibility of this approach, showcasing superior performance compared to existing literature in terms of component count, efficacy, illumination quality, and reliability. Notably, based on simulation results, the efficacy of our approach surpasses the bias-T approach by approximately 6.25%.

This article proposes a new active-front-end (AFE) control method for regenerative cascaded H-bridge (CHB) motor drives. Conventional CHB converters have dominated the market for the medium-voltage industrial motor drives. However, conventional CHB converters cannot provide regenerative capability. To enable regeneration; diode-front-ends in power cells are replaced with insulated-gate bipolar transistor (IGBT)-based pulsewidth modulation (PWM) AFEs. Despite the appealing dynamic performance of PWM AFEs, their integration to the CHB converters is not optimal. First, they introduce more semiconductor losses due to the high-frequency switching. Second, they introduce switching harmonics that are not cancelled by phase-shifting transformers. Therefore, they require additional harmonic filtering solutions to comply with grid harmonic standards. To resolve these challenges, this article proposes a new AFE control for regenerative CHB converters based on fundamental frequency switching (FFE) to reduce switching frequency and thus power losses. The operation of FFEs at nominal and sag voltage conditions is presented, in addition to the capability of filter-less interfacing to the transformer. Finally, the performance of the proposed control is validated experimentally on a seven-level regenerative CHB drive.