A generic PWM strategy for multi-leg VSI-fed machine drives

A generic pulse width modulation（PWM） strategy is proposed for the multi-leg voltage source inverter（VSI）.First, the multi-leg VSI is modeled, which is independent from the load structure. Secondly, the proposed PWM strategy is deduced by inverting the mathematical model of the multileg VSI. According to the relationship between the leg number of VSIs and the phase number of electrical machines, the multi-leg VSI-fed machine drives are classified into two types：matched and unmatched applications. The leg numbers of VSIs and the phase number of electrical machines are equal in matched applications while they are different in unmatched applications. The existing PWM strategies cannot be directly used for both matched and unmatched applications. However,the proposed PWM strategy can be general for both matched and unmatched applications, and no modifications are required. The effectiveness of the proposed PWM strategy is verified by experimental results.

Analysis and design of DSP-based dual-loop controlled UPS inverters

This paper presents a novel digital dual-loop control scheme of the PWM(PUlse width modulate)inverter. Deadbeat control technique are employed to enhance the performance. Half switching period delayed sampling and control timing strategy is used to improve the system dynamic response. Simulation and experimental results presented in the paper verified the validity of the proposed control scheme.

汉语官话方言连字调的几个基本问题思考

汉语官话方言连读变调的深入研究需要思考探讨相关理论问题,文中分析了连读变调域、节律轻重与连读变调的关系、协同发音与连读变调的区别、连读变调机制、连字调格局这几个基本问题,表述了作者的看法。

Biochemical regulation of pigment motility in vertebrate chromatophores： a review of physiological color change mechanisms

The fundamental unit of rapid, physiological color change in vertebrates is the dermal chromato- phore unit. This unit, comprised of cellular associations between different chromatophore types, is relatively conserved across the fish, amphibian, and reptilian species capable of physiological color change and numerous attempts have been made to understand the nature of the four major chro- matophore types （melanophores, erythrophores, xanthophores, and iridophores） and their bio- chemical regulation. In this review, we attempt to describe the current state of knowledge regard- ing what classifies a pigment cell as a dynamic chromatophore, the unique characteristics of each chromatophore type, and how different hormones, neurotransmitters, or other signals direct pig- ment reorganization in a variety of vertebrate taxa.

Bioelectrochemical control mechanism with variable-frequency regulation for skeletal muscle contraction-Biomechanics of skeletal muscle based on the working mechanism of myosin motors(Ⅱ)

This paper presents a bioelectrochemical model for the activation of action potentials on sarcolemma and variation of Ca2+ concentration in sarcomeres of skeletal muscle fibers.The control mechanism of muscle contraction generated by collective motion of molecular motors is elucidated from the perspective of variable-frequency regulation,and action potential with variable frequency is proposed as the control signal to directly regulate Ca2+ concentration and indirectly control isometric tension.Furthermore,the transfer function between stimulation frequency and Ca2+ concentration is deduced,and the frequency domain properties of muscle contraction are analyzed.Moreover the conception of "electro-muscular time constant" is defined to denote the minimum delay time from electric stimulation to muscle contraction.Finally,the experimental research aiming at the relation between tension and stimulation frequency of action potential is implemented to verify the proposed variable-frequency control mechanism,whose effectiveness is proved by good consistence between experimental and theoretical results.