Resources Contact Us Home
Browse by: INVENTOR PATENT HOLDER PATENT NUMBER DATE
 
 
Apparatus and method for measuring power factor and torque on the output of variable frequency drives










Image Number 3 for United States Patent #5003252.

An apparatus and method for sensing power factor and torque on the output of a variable frequency machine is disclosed. Initially, power is sensed in each phase of the three-phase machine by utilizing Hall generators for multiplying the phase current flowing through each phase by a current proportional to a phase voltage for each phase. The products are then summed to obtain a reading of the instantaneous power drawn by the three phase machine. The AC component is filtered out of the summed signal using a multistage filter which allows for maintaining a fast response time with low ripple. This output is divided by the speed of the machine and multiplied by a constant to result in a signal representing torque. For measuring power factor, power signal sensed in each phase is applied to a DC blocking capacitor, effectively separating the AC envelope proportional to voltage times current. The three signals are applied to absolute value amplifiers and summed to provide a signal yielding total power. The instantaneous power is then divided by this signal to provide power factor.








 
 
  Recently Added Patents
Azole derivatives, methods for producing the same, intermediate thereof, agro-horticultural agents
Generating compiled code that indicates register liveness
Methods and apparatus to determine impressions using distributed demographic information
Semiconductor thin film, thin film transistor, method for manufacturing same, and manufacturing equipment of semiconductor thin film
Proton conducting electrolytes with cross-linked copolymer additives for use in fuel cells
Front face of vehicle wheel
Methods and devices for detecting and measuring environmental conditions in high performance device packages
  Randomly Featured Patents
Isocyanurate esters of carboxyalkylthioalkanoesterphenol compounds and polyolefin polymeric compositions stabilized therewith
Implant material for replacing hard tissue of living body
Deer feeder
Method of forming p-type compound semiconductor layer
Food container with cooling pack
Door
Recombinant fibrinogenases, the preparation and use thereof
Pet toy with the face of a lion
Image compression and affine transformation for image motion compensation
Fluorescent lamp simulator