Due to the successive switching actions in a power electronic system, considerable conducted electromagnetic interference (EMI) is generated. This has been a major concern in designing power converters, which requires additional EMI filtering efforts. Passive EMI filters are the most common solutions to EMI reduction but usually consume a large portion of the volume as well as weight in power converters. Active EMI filters (AEFs) or hybrid EMI filters (HEFs) are considered best candidates over traditional passive EMI filters to achieve higher power density in power converters. The utilization of current transformer to sense or to compensate the EMI noise can increase the volume of an AEF. In this article, a transformer-less AEF, sprung from the concept of virtual impedance enhancement, is proposed. The proposed design features feedforward control with current-sensing-voltage-compensating. The operation principle of the proposed AEF is thoroughly introduced, and its performance is evaluated through simulations and experiments. Experimental results with an ac–dc power converter and a dc–ac inverter show that the proposed AEF can be generally applied to reduce conducted EMI on either ac or dc power lines.

One of the major issues with pulse-width modulation (PWM) is that considerable conducted emissions will be generated from power electronics converters. Random modulations are considered one of the viable solutions to reduce conducted electromagnetic interference (EMI) without adding bulky passive filtering components. Literature that investigates the application of such techniques in active front end (AFE) drives is limited. In this paper, a novel random switching frequency PWM (RSF-PWM) is proposed for a grid-tied AFE drive to suppress conducted emissions. The statistical behavior of switching frequency is based on uniform distribution. Simulation and experiments are carried out on a 10-hp AFE drive. Results demonstrate that the proposed RSF-PWM can effectively reduce conducted EMI by approximately 20 dB within low-frequency range, compared with conventional constant switching frequency PWM (CSF-PWM).

Common-mode voltage produced by voltage source inverters (VSI) is of great concern in motor drive systems. Significant amount of conducted common-mode/bearing current will be induced and will interfere with system operation. As an alternative to inserting bulky passive filters to combat the adverse effect by common-mode voltage, this paper proposes a new topology of integrated active zero-state switch (IAZS). Minor adjustment to the standard space vector pulse-width modulation (SVPWM) is proposed to facilitate the use of IAZS, which enables common-mode voltage reduction in VSI-fed motor drives. Simulation and experimental results on a commercial VSI are presented as proof of concept to validate the effectiveness of proposed design in common-mode voltage reduction.

There are many methods for real-time estimation and identification for induction motor (IM) drives. In this study, dynamic mode decomposition with control (DMDc) and its variants are explored for voltage source inverter fed IM. For real-time identification, online variants of the DMDc are explored, including windowed online DMDc. These algorithms are tested in simulation for healthy and faulty behaviors of the IM drive. They are compared for estimation accuracy and implementation complexity. Lastly, these algorithms are tested on a dSpace experimental platform to further prove their potential and applicability for both healthy and faulty cases. With accurate DMDc estimation results across different variants, their applications have potentials in condition monitoring or fault-tolerant control.