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
Jacket liner
Beverage container lid
Visual processing apparatus and visual processing method
Method to prevent hyper frame number de-synchronization in a wireless communication system
Systems and methods for implementing multi-application tabs and tab sets
System and method for document orientation detection
Equipment to facilitate money transfers into bank accounts
  Randomly Featured Patents
Image forming device providing document reading mode and image recording mode
Snow ski with integral binding isolation mounting plate
Recombinant microbial 3-hydroxybutyrate dehydrogenase a process for its production and the use thereof
Refillable filter-drier assembly
System and method of scaling error signals of caseload second order modulators
Incineration control apparatus for a fluidized bed boiler
Supporting multiple access technologies in a wireless environment
Hoist gear lubricator
Hybrid turbine blade and related method
Camellia plant named `Nuccio's Bella Rossa`