Pulse with modulation (PWM) is widely used in proportional control systems for it is efficient, flexible and anti-interference. Due to the friction and hysteresis of electromagnet, hysteresis exists when hydraulic valve in steady-state, and hysteresis influences the dynamic characteristics of the valve seriously, the hysteresis can be improved by superimposing dithers with certain frequency and...

LED PWM dimming application for large scale LED video displays is analyzed. The need for short light pulse duration is outlined. PWM dimming with short driving pulses is investigated experimentally. The LED response time skew introduces the nonlinearity for PWM dimming. For LED response time skew estimation, a method is suggested that has been successfully applied to measure some of today’s mar...

In this paper, dynamic overmodulation characteristics of current-regulated carrier-based high-performance pulsewidth modulation (PWM) voltage-source inverter drives are investigated. Dynamic and steady-state overmodulation operating modes are clearly distinguished, and the requirements for obtaining high performance in each mode are shown to be significantly different. Dynamic overmodulation ch...

Abetmct A concept of optimal surplus harmonies distribution in selective harmonic elimination PWM teehnique for multilevel inverters is introduced in this paper. There m e several performance indexes that fan he optimized in PWM inverters, e.g., distortion factor, current or voltage total harmonic distortion, or efficiency. Minimisation of magnetic noise is selected as an example here. Several ...

A novel soft switching PWM converter for high frequency ACIDC andlor DCIAC power conversion is presented by using a new parallel resonant dc-link(PRDCL) and by adopting single phase soft switching(SPSS) technique. The new PRDCL provides variable link pulse position as well as variable link pulse ,width. which is quite different feature from the other resonant dc-links and thus the PWM capabilit...

Voltage source inverter (VSI) fed induction motors are widely used in variable speed applications. The harmonic distortion in the line currents of the inverter depends on the switching frequency and the pulse width modulation (PWM) technique employed to switch the inverter. The inverter switching loss is also strongly influenced by the PWM technique used. This paper compares the harmonic distor...

Activation of T lymphocytes by pokeweed mitogen (PWM) is strictly monocyte (Mo)-dependent and results in T-cell mitogenesis and interleukin-2 (IL-2) secretion, coupled with an inability to utilize IL-2 due to an impaired expression of functional IL-2 receptor (IL-2R). Such IL-2R impairment could arise in PWM-activated T cells themselves or, alternatively, be the result of Mo-derived influences,...