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
Device and method for quantizing and inverse quantizing LPC filters in a super-frame
Motor device and method of manufacturing the same
Expression of dirigent gene EG261 and its orthologs and paralogs enhances pathogen resistance in plants
Sericin cationic nanoparticles for application in products for hair and dyed hair
Secure data entry device
Electronic device with a screen
Film-forming resins as a carrier for topical application of pharmacologically active agents
  Randomly Featured Patents
Process for the controlled feeding of a melting crucible with particles during the drawing of crystals by the czochralski method
Dispersion, microcapsule, electrophoretic device, electro-optical device, and method of forming a dispersion
Noise assisted signal processor with nonlinearly coupled arrays of nonlinear dynamic elements
Method of tuning a sensor array for occupancy sensing in a vehicle seat
Hand-operated instrument for dental care or tooth treatment
Window latch member
Mirror
Plastic spring
Fiber optic cable end connector
Rehabilitation exercising equipment that can extend a user's legs