A method to derive on time mechanical power factor

Abstract

This paper takes care of window problem in mechanical power factor calcuration. Unlike power factor in electrical system, mechanical power factor contains problem of taking window in the motion. A motion is composed of various wave form which changes over time. On the other hand, wave form of the electrical system is always sinusoidal when it is alternative current system. When thinking about power factor in mechanical system, when to take window over the motion is critical. This paper addresses a problem by calculating power factor on time. Realtime power factor calcuration using shorttime Fourier transformation is explained in the paper. Reliability of the calcuration is shown by comparing experimental data with theoretical result.

DC signal based estimation of power factor in mechanical system

“…In mechanical system, such a situation occurs occasionally. The phenomenon is observed by online power factor derivation in [7] as well. Therefore in mechanical system, power factor for DC wave is 1 or -1.…”

“…Therefore in mechanical system, power factor for DC wave is 1 or -1. Its sign is determined from active power of the system since apparent power is always positive from its calculation procedure (5)- (7). Sign of active power is determined from multiplication of velocity and force.…”

“…However, the wave takes various forms in mechanical system, even though theory of power factor is only valid in sinusoidal wave signals. On reference [7], authors have proposed a method to obtain power factor in mechanical system by using short-time Fourier transformation (STFT). By taking STFT of signal in mechanical system, it is interpreted as a combination of series of sinusoidal waves.…”

“…In references [7], authors have introduced the power factor in mechanical system in order to describe dynamic behavior of the object during motion. Power factor can express energy transmission from robot to object during contact.…”