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
Chemically resistant membranes, coatings and films and methods for their preparation
Handbag
Methods and compositions for wound healing
Combining seismic data from sensors to attenuate noise
Light irradiation element, image forming structure, and image forming apparatus
Display screen or portion thereof with icon
Medical diagnosis, therapy, and prognosis system for invoked events and methods thereof
  Randomly Featured Patents
Exerciser
Examination table
Method and apparatus for detecting artifacts using common-mode signals in differential signal detectors
Image game cartridge
Composite polishing pad for semiconductor process
Method for embossing and crimping a multi-layer sheet material web assembly
Gaming device having an accumulating award symbol
Pixel-based digital watermarks located near edges of an image
Bracket
Charged particle beam device