Ryerson University

About: Ryerson University is a education organization based out in Toronto, Ontario, Canada. It is known for research contribution in the topics: Population & Poison control. The organization has 7671 authors who have published 20164 publications receiving 394976 citations. The organization is also known as: Ryerson Polytechnical Institute & Ryerson Institute of Technology.

A Flying-Capacitor Modular Multilevel Converter for Medium-Voltage Motor Drive

Abstract: This paper presents a flying-capacitor modular multilevel converter (FC-MMC) based on series-connected submodules. It is intended for completely improving the performance of a medium-voltage motor drive system in the entire speed range especially at zero/low speed under rated torque condition. The proposed FC-MMC circuit is characterized by the cross connection of upper and lower arm middle taps through a flying capacitor in per phase leg. By properly controlling the ac current flowing through the flying capacitor, the power balance between upper and lower arms is achieved, leading to very small voltage ripples on submodule dc capacitors in the entire speed range from standstill to rated speed even under the rated torque condition. Meanwhile, no common-mode voltage is injected. Simulation results obtained from a 4160-V 1-MW model show that the proposed FC-MMC along with the proposed control method performances satisfactorily in dynamic and static state even when operated at zero/low speed. Experiments on a downscaled prototype also prove the effectiveness of the proposal.

Cognitive Processing Therapy

Abstract: Cognitive processing therapy (CPT) is an evidence-based, cognitive-behavioral treatment designed specifically to treat posttraumatic stress disorder (PTSD) and comorbid symptoms. This chapter will first review the theoretical underpinnings of the intervention and then provide more detail about the actual protocol including a clinical case description. We then will review several special considerations and challenges in administering the protocol to specific groups of trauma survivors and finally end with an overview of the published randomized controlled clinical trials demonstrating the efficacy of the therapy.

A Generalized Formulation of Quarter-Wave Symmetry SHE-PWM Problems for Multilevel Inverters

Abstract: A generalized formulation of quarter-wave symmetrical selective harmonic elimination (SHE) problems according to the rising and falling edges of the pulsewidth modulation (PWM) waveforms for multilevel inverters is proposed. The SHE modulation scheme features a broad solution space and can eliminate a large number of low-order harmonics. An effective method for obtaining initial values of switching angles is proposed. This method is based on rules of equal area and superposition of center of gravity (cg) of the PWM section with the sine reference signal. To illustrate the effectiveness of the proposed SHE method, a five-level voltage source inverter with elimination of 11 low-order harmonics is investigated. The SHE-PWM equations that can eliminate harmonics from 5th to 35th with modulation index M varying from 0 to 1.15 are formulated, and solutions are presented. Simulations and experiments based on two sets of solutions are carried out. It is demonstrated that the experimental results agree well with simulated ones, which proves the validity and practicability of the new method proposed.