Gibok Lee

We present a new topology appropriate for “dynamic” wireless charging. Possible applications include charging of electric vehicles or robots moving in a large, predesignated area. We propose a system with a transmitter made from multiple coils commensurable with the moving receiver(s), and powered by a single inverter. The proposed system uses the reactance reflected by the receiver to automatically increase the field strength in coupled portions of the transmitter-receiver system, thus allowing

Contrastive representation learning has shown to be effective to learn representations from unlabeled data. However, much progress has been made in vision domains relying on data augmentations carefully designed using domain knowledge. In this work, we propose i-Mix, a simple yet effective domain-agnostic regularization strategy for improving contrastive representation learning. We cast contrastive learning as training a non-parametric classifier by assigning a unique virtual class to each data

In many industrial settings, momentary power disruptions commonly occur, resulting in tripping of large electric machines, which then have to be brought to zero speed before the machine can be restarted. This can result in frequent interruptions in an industrial process, which can have negative effects on productivity. A more practical approach would restart the machine back to the original speed as soon as power is restored, not having to wait for the machine to be at a standstill. This concept

This article proposes a new maximum torque per ampere (MTPA) control strategy for an induction motor (IM) controlled by the scalar ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">v</i> / <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> ) method. In scalar control, constant air-gap flux control is generally adopted for IM drives to provide the same torque capability in all operating ranges.

This paper presents a universal flying restart strategy for scalar ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V/f</i> ) controlled induction machines. The proposed method performs a frequency search to estimate the rotor speed, and applies the correct frequency and voltage to minimize the inrush current during the restart. This method uses the measured phase current and the motor nameplate parameters, thus making the approach ideal for sca

This paper presents a simple discontinuous pulse width modulation (DPWM) switching scheme to reduce the switching loss of a single DC-link dual two-level inverter fed an open-end winding (OW) induction motor (IM). The dual inverter system is attractive in many applications due to higher DC-link voltage utilization. Additionally, the OW motor has the potential fault-tolerant capability. However, the use of the dual inverter results in reduced system efficiency due to increased power losses in the

Lifelong learning with deep neural networks is well-known to suffer from catastrophic forgetting: the performance on previous tasks drastically degrades when learning a new task. To alleviate this effect, we propose to leverage a large stream of unlabeled data easily obtainable in the wild. In particular, we design a novel class-incremental learning scheme with (a) a new distillation loss, termed global distillation, (b) a learning strategy to avoid overfitting to the most recent task, and (c) a

In this paper, a new maximum torque per ampere (MTPA) control method for surface permanent magnet synchronous motors (SPMSMs) controlled by the scalar control (v/f) method is proposed. The scalar control is a sensorless method that controls only the magnitude and the frequency of the stator voltage vector without the information of the rotor position. This method suggests the injection of the high frequency voltage signal in the stator current vector reference frame, which can be calculated from

This paper presents a rotating restart method for v/f scalar controlled Synchronous Reluctance Machines (SynRMs) using a single DC-link current sensor. In such a case, the initial rotor position and speed are required to restart the machine due to the absence of a position sensor. The method proposes to inject three active voltage vectors in the stationary reference frame to induce the phase currents required for estimating the rotor position and speed. In addition, the phase current reconstruct

This letter presents a fault-tolerant control (FTC) for a one-phase current sensor failure in the open-ended winding permanent magnet synchronous motor (PMSM) fed by the dual inverter with a common dc bus. While many FTC strategies for stator winding and inverter leg faults have been researched, an FTC for one-phase current sensor fault has not yet been proposed. Unlike a single inverter, the dual inverter with a common dc bus needs three-phase current measurement due to the flow of zero-sequenc

This study proposes a novel pulsewidth modulation (PWM) strategy in high modulation index (MI) regions for the open-end winding permanent magnet synchronous motor fed by the dual inverter with the common dc bus. The dual-inverter system is getting attention due to the higher voltage utilization and the potential fault-tolerant capability. However, the dual-inverter system inherently suffers from the zero-sequence current (ZSC) flowing due to the opened neutral point of the stator windings and th

This paper presents an approach to implement the universal flying restart for an induction machine using a frequency search algorithm that determines the rotor speed so that the correct frequency and voltage can be applied to minimize the inrush current during the restart. This method only uses the measured phase current and the motor nameplate parameters, thus making it ideal for use with scalar-controlled motor drives. An additional benefit of the proposed approach is that the time to estimate